Bone is a dynamic tissue that constantly undergoes remodeling processes throughout life to maintain its structure and integrity. During this process, physiological bone turnover, which is shaped by apoptosis, occurs in cells in the bone microenvironment. The clearance of these apoptotic cells (ACs) is executed by phagocytes through a process called efferocytosis, which simply means taking to the grave "burial." Efferocytosis is a multistage process involving the recognition, binding, internalization, and digestion of ACs, culminating in the resolution of inflammation. Critically, aberrations in efferocytosis lead to the accumulation of apoptotic corpses, impairing tissue homeostasis and contributing to various pathologies as well as bone-related diseases. Emerging evidence suggests that modulating/activating efferocytosis at any stage represents a promising therapeutic strategy for managing bone-related diseases, especially those associated with aging and inflammation. This review discusses the current understanding of the cellular and molecular mechanisms of efferocytosis, its roles within the bone microenvironment, and potential therapeutic interventions targeting efferocytosis in age-related bone diseases.

Rationally coupling natural biochemical reactions for live-cell synthesis of inorganic nanocrystals with fluorescence, such as quantum dots (QDs) especially near-infrared (NIR), holds significant potential for in situ labeling and bioimaging. However, the introduced exogenous reactants and intracellularly produced species, e.g., reactive oxygen species (ROS), often cause cell damage, decreasing the fluorescence of the QDs. Herein, we have found that cell-adaptable selenocystine ((Cys-Se)2) can be reduced to biocompatible low-valence Se precursors, which could be subsequently hijacked by timely added Ag-glutathione (AgSG) to be transformed into NIR Ag2Se QDs. Such a comprehensive control strategy can inhibit the production of cytotoxic Se species and ROS bursts, significantly increasing the cell viability from 4 to 80% and enhancing the fluorescence of intracellularly synthesized Ag2Se QDs by over 8.7 times. Notably, the proliferative and in vivo tumorigenic capacities of the cells with strong NIR fluorescence-emitting functions could be maintained, enabling long-term tracking of cell division and disease progression. This work has provided new insights into fully excavating the potential of cells for the synthesis of inorganic nanocrystals by designing biocompatible precursors and also opened a new window for conventional synthetic biology from organic to inorganic.

Cytotoxic lymphocytes counter intracellular pathogens and cancer by recognizing and destroying infected or transformed target cells. The basis for their function is the cytolytic immune synapse, a structurally stereotyped cell-cell interface through which lymphocytes deliver toxic proteins to target cells. The immune synapse is a highly dynamic contact capable of exerting nanonewton-scale forces against the target cell. In recent years, it has become clear that the interplay between these forces and the biophysical properties of the target influences the entirety of the cytotoxic response, from the initial activation of cytotoxic lymphocytes to the release of dying target cells. As a result, cellular cytotoxicity has become an exemplar of the ways in which biomechanics can regulate immune cell activation and effector function. This Review covers recent progress in this area, which has prompted a reconsideration of target cell killing from a more mechanobiological perspective.

The immune system relies on carefully calibrated cellular machineries to enable distinction between endogenous and foreign molecules, with autoimmunity arising when this balance is disrupted. As potent autoantibody factories, B cells are major drivers of many autoimmune diseases. A significant fraction of patients affected by chronic autoimmune diseases such as systemic lupus erythematosus (SLE) exhibit pathogenic accumulation of B-cell subsets that are believed to be derived from the extrafollicular (EF) differentiation pathway. These B-cell subsets, although variously named and exhibiting intrinsic heterogeneity, are all poised producers of autoantibodies that correlate with patient pathophysiology. In addition, they are often characterized by biomarkers known to drive the innate immune response, including toll-like receptors and complement receptors. Although many innate receptors have well-established functions in myeloid cells and other immune cell types, their B cell-specific functions are still under active investigation and are crucial for understanding the molecular pathways that drive B-cell breaks of tolerance. In this review, we summarize studies on innate immune receptors that serve prominent roles in regulating EF B-cell activation in health and autoimmunity. By discussing independent and collaborative functions of these receptors, we hope to provide new perspectives in autoimmune disease signature research.

The Masquelet technique that combines a foreign body reaction (FBR)-induced vascularized tissue membrane with staged bone grafting for reconstruction of segmental bone defect has gained wide attention in Orthopedic surgery. The success of Masquelet hinges on its ability to promote formation of a "periosteum-like" FBR-induced membrane at the bone defect site. Inspired by Masquelet's technique, here a novel approach is devised to create periosteum mimetics from decellularized extracellular matrix (dECM), engineered in vivo through FBR, for reconstruction of segmental bone defects. The approach involved 3D printing of polylactic acid (PLA) template with desired pattern/architecture, followed by subcutaneous implantation of the template to form tissue, and depolymerization and decellularization to generate dECM with interconnected channels. The dECM matrices produces from the same mice (autologous) or from different mice (allogenic) are used as a functional periosteum for repair of structural bone allograft in a murine segmental bone defect model. This study shows that autologous dECM performed better than allogenic dECM, further permitting local delivery of low dose BMP-2 to enhance allograft incorporation. The success of this current approach can establish a new line of versatile, patient-specific, and periosteum-like autologous dECM for bone regeneration, offering personalized therapeutics to patients with impaired healing.

Monosodium glutamate (MSG) is one of the most commonly used food additives, known for its adverse health effects. Alogliptin (ALO) is a highly selective dipeptidyl peptidase-4 inhibitor, but its role in male reproductive function remains debated. The study was designed to evaluate and compare the potential of ALO in mitigating MSG-induced testicular toxicity in juvenile and adult male rats. Juvenile and adult male rats were treated with either MSG or pretreated with ALO before MSG administration. The rats then received ALO and MSG concurrently for 28 days. Testicular tissues were isolated and subjected to histo-biochemical and molecular assessments. Our results demonstrated that ALO reversed MSG-induced testicular injury, as evidenced by the restoration of reproductive hormone balance (increased serum luteinizing hormone and testosterone concentrations), suppression of oxidative stress injury (decreased testicular malondialdehyde, increased superoxide dismutase activity, and minimal 8-hydroxy-2'-deoxyguanosine immunoreactivity), inflammation (reduced testicular tumor necrosis factor-alpha levels), and fibrosis (decreased testicular collagen fiber deposition). Additionally, ALO impeded apoptosis and activated autophagy by decreasing caspase-3 activity, stimulating the AMPK/mTOR pathway, downregulating Bax and SQSTM-1/p62 expression, upregulating Bcl2 and Beclin 1, promoting testicular proliferation (increased number of proliferating cell nuclear antigen-positive cells in the testis), restoring glycogen content in the testis (mild to moderate periodic acid-Schiff reaction), and preserving testicular architecture. MSG induced more severe adverse testicular effects in juvenile rats, while ALO pretreatment was more protective in adult rats. ALO's anti-inflammatory, antioxidant, antiapoptotic, pro-autophagic, antifibrotic, and proliferative actions in the testis suggest its promising potential for combating male reproductive dysfunction.

The rising aging population and changing lifestyles have led to a global increase in diabetes and its complications, making it one of the most prevalent diseases worldwide. Chronic inflammation is a key pathogenic feature of diabetes and its complications, yet the precise mechanisms remain unclear, impeding the development of targeted therapies. Recent studies have highlighted the β cell-macrophage crosstalk pathway as a crucial factor in chronic low-grade inflammation and glucose homeostasis imbalance in both type 1 and type 2 diabetes. Furthermore, impaired macrophage phagocytic functions, including pathogen phagocytosis, efferocytosis, and autophagy, play a significant role in diabetes complications. Given their high plasticity, macrophages represent a promising research target. This review summarizes recent findings on macrophage phagocytic dysfunction in diabetes and its complications, and explores emerging therapies targeting macrophage phagocytic function. We also discuss the current challenges in translating basic research to clinical practice, aiming to guide researchers in developing targeted treatments to regulate macrophage status and phagocytic function, thus preventing and treating metabolic inflammatory diseases.

Paclitaxel (PTX) is a first-line chemotherapeutic drug for non-small cell lung cancer (NSCLC) but it can induce indoleamine 2,3-dioxygenase (IDO) activation, which severely lowers down its immuno-chemotherapeutic effect. To address this issue, a smart peptide hydrogelator Nap-Phe-Phe-Phe-Lys-Ser-Thr-Gly-Gly-Lys-Ala-Pro-Arg-OH (Nap-T), which co-assembles with PTX and an IDO inhibitor GDC0919 to form a hydrogel GP@Gel Nap-T, is rationally designed. Upon specific phosphorylation by pyruvate kinase M2 (PKM2), an overexpressed biomarker of NSCLC, Nap-T is gradually converted to Nap-Phe-Phe-Phe-Lys-Ser-Thr(H2PO3)-Gly-Gly-Lys-Ala-Pro-Arg-OH (Nap-Tp), leading to dehydrogelation and sustained release of PTX and GDC0919 within NSCLC tissues. The released PTX exerts chemotherapy on NSCLC cells as well as immunogenic cell death induction, while GDC0919 promotes the immuno-chemotherapeutic effect of PTX through IDO inhibition. We find that GP@Gel Nap-T enhances the infiltration of tumor-infiltrating immune cells and reduces the number of immunosuppressive cells in either tumor tissues or tumor-draining lymph nodes, thus enhancing the immuno-chemotherapy of PTX toward NSCLC. With this PKM2-responsive drug release strategy, the smart peptide hydrogel platform might be applied for NSCLC treatment in clinic in near future.

Lysosomes in mammalian cells are recognized as key digestive organelles, containing a variety of hydrolytic enzymes that enable the processing of both endogenous and exogenous substrates. These organelles digest various macromolecules and recycle them through the autophagy-lysosomal system. Recent research has expanded our understanding of lysosomes, identifying them not only as centers of degradation but also as crucial regulators of nutrient sensing, immunity, secretion, and other vital cellular functions. The lysosomal pathway plays a significant role in vascular regulation and is implicated in diseases such as atherosclerosis. During atherosclerotic plaque formation, macrophages initially engulf large quantities of lipoproteins, triggering pathogenic responses that include lysosomal dysfunction, foam cell formation, and subsequent atherosclerosis development. Lysosomal dysfunction, along with the inefficient degradation of apoptotic cells and the accumulation of modified low-density lipoproteins, negatively impacts atherosclerotic lesion progression. Recent studies have highlighted that lysosomal dysfunction contributes critically to atherosclerosis in a cell- and stage-specific manner. In this review, we discuss the mechanisms of lysosomal biogenesis and its regulatory role in atherosclerotic lesions. Based on these lysosomal functions, we propose that targeting lysosomes could offer a novel therapeutic approach for atherosclerosis, shedding light on the connection between lysosomal dysfunction and disease progression while offering new insights into potential anti-atherosclerotic strategies.

Liver transplantation is the only curative option for end-stage liver disease and is necessary for an increasing number of patients with advanced primary or secondary liver cancer. Many patient groups can benefit from this treatment, however the shortage of liver grafts remains an unsolved problem. Liver bioengineering offers a promising method for expanding the donor pool through the production of acellular scaffolds that can be seeded with recipient cells. Decellularization protocols involve the removal of cells using various chemical, physical, and enzymatic steps to create a collagenous network that provides support for introduced cells and future vascular and biliary beds. However, the removal of the cells causes varying degrees of matrix damage, that can affect cell seeding and future organ performance. The main objective of this review is to present the existing techniques of producing decellularized livers, with an emphasis on the assessment and definition of acellularity. Decellularization agents are discussed, and the standard process of acellular matrix production is evaluated. We also introduce the concept of the stepwise assessment of the matrix during decellularization through decellularization cycles. This method may lead to shorter detergent exposure times and less scaffold damage. The introduction of apoptosis induction in the field of organ engineering may provide a valuable alternative to existing long perfusion protocols, which lead to significant matrix damage. A thorough understanding of the decellularization process and the action of the various factors influencing the final composition of the scaffold is essential to produce a biocompatible matrix, which can be the basis for further studies regarding recellularization and retransplantation.

The body's immune response plays a critical role in defending against external or foreign antigens while also preserving tolerance to self-antigens. This equilibrium, referred to as immune homeostasis, is paramount for overall health. The regulatory mechanisms governing the maintenance of this delicate immune balance are notably complex. It is currently accepted that immune tolerance is a dynamic outcome regulated by multiple factors, including central and peripheral mechanisms. Its induction or elimination plays a significant role in autoimmune diseases, organ transplantation, and cancer therapy, markedly impacting various major diseases in modern clinical practice. Overall, our current understanding of immune tolerance is still very limited. In this review article, we summarized the main mechanisms that have been known to mediate immune tolerance so far, including endogenous immune tolerance, adaptive immune tolerance, other immune tolerance mechanisms, and the homeostasis of immune tolerance, identified the key factors that regulate immune tolerance, and provided new clues for immune system recovery in many autoimmune diseases, organ transplantation, and tumor therapy.

Last twenties, tissue engineering has rapidly advanced to address the shortage of organ donors. Decellularization techniques have been developed to mitigate immune rejection and alloresponse in transplantation. However, a clear definition of effective decellularization remains elusive. This study compares various decellularization protocols using the human fascia lata model. Morphological, structural and cytotoxicity/viability analyses indicated that all the five tested protocols were equivalent and met Crapo's criteria for successful decellularization. Interestingly, only the in vivo immunization test on rats revealed differences. Only one protocol exhibited Human Leucocyte Antigen (HLA) content below 1% residual threshold, the only criterion preventing rat immunization with an absence of rat anti-human IgG switch after one month (N=4 donors for each of the 7 groups, added by negative and positive controls, n=28). By respecting a refined set of criteria, i.e. lack of visible nuclear material, <50ng DNA/mg dry weight of extracellular matrix, and <1% residual HLA content, the potential for adverse host reactions can be drastically reduced. In conclusion, this study emphasizes the importance of considering not only nuclear components but also major histocompatibility complex in decellularization protocols and proposes new guidelines to promote safer clinical development and use of bioengineered scaffolds.

The lungs are highly susceptible to damage during sepsis, with severe lung injury potentially progressing to acute respiratory distress syndrome and even fatal sepsis. Effective efferocytosis of apoptotic cells is crucial in alleviating inflammation and tissue injury.

We established a septic lung injury mouse model via intraperitoneal injection of lipopolysaccharide. Lung injury was assessed by histology, immunofluorescence, neutrophil immunohistochemistry staining, and cytokine detection. We extracted alveolar macrophages by bronchoalveolar lavage and primary macrophages from mouse bone marrow to investigate the regulatory effects of Dexmedetomidine (DEX) on efferocytosis. We further validated the molecular mechanisms underlying the regulation of macrophage efferocytosis by DEX through knockdown of AXL expression. Additionally, we examined the efferocytic ability of monocytes isolated from patients.

We discovered that DEX treatment effectively alleviated pulmonary injury and inflammation. Lipopolysaccharide reduced macrophage efferocytosis and AXL expression which were reversed by DEX. We also found DEX inhibited the increased activation of A Disintegrin And Metalloproteinase 10 (ADAM10) and the production of soluble AXL. Moreover, our findings demonstrated that DEX decreased the elevated ROS production linked to higher ADAM10 activation. Blocking AXL negated DEX's benefits on efferocytosis and lung protection. Efferocytosis in monocytes from septic lung injury patients was notably lower than in healthy individuals.

Our findings demonstrated that DEX treatment effectively reduces septic lung injury by promoting macrophage efferocytosis through ROS/ADAM10/AXL signaling pathwway.

Systemic lupus erythematosus (SLE) is an autoimmune disease, the pathophysiology and genetic basis of which are incompletely understood. Using a forward genetic screen in multiplex families with SLE, we identified an association between SLE and compound heterozygous deleterious variants in the non-receptor tyrosine kinases (NRTKs) ACK1 and BRK. Experimental blockade of ACK1 or BRK increased circulating autoantibodies in vivo in mice and exacerbated glomerular IgG deposits in an SLE mouse model. Mechanistically, NRTKs regulate activation, migration, and proliferation of immune cells. We found that the patients' ACK1 and BRK variants impair efferocytosis, the MERTK-mediated anti-inflammatory response to apoptotic cells, in human induced pluripotent stem cell (hiPSC)-derived macrophages, which may contribute to SLE pathogenesis. Overall, our data suggest that ACK1 and BRK deficiencies are associated with human SLE and impair efferocytosis in macrophages.

Acellular nerve grafts (ANGs) are a promising therapeutic for patients with nerve defects caused by injuries. Conventional decellularization methods utilize a variety of detergents and enzymes. However, these methods have disadvantages, such as long processing times and the presence of detergents that remain on the graft. In this study, we aimed to reduce process time and minimize the risks associated with residual detergents by replacing them with supercritical carbon dioxide (scCO2) and compared the effectiveness to Hudson's decellularization method, which uses several detergents. The dsDNA and the expression of MHC1 and 2 were significantly reduced in both decellularized groups, which confirmed the effective removal of cellular debris. The extracellular matrix proteins and various factors were found to be better preserved in the scCO2 ANGs compared to the detergent-ANGs. We conducted behavioral tests and histological analyses to assess the impact of scCO2 ANGs on peripheral nerve regeneration in animal models. Compared with Hudson's method, the scCO2 method effectively improved the efficacy of peripheral nerve regeneration. Therefore, the decellularization method using scCO2 is not only beneficial for ANG synthesis, but it may also be helpful for therapeutics by enhancing the efficacy of peripheral nerve regeneration.

Voltage-dependent anion channels (VDACs) are important proteins of the outer mitochondrial membrane (OMM). Their beta-barrel structure allows for efficient metabolite exchange between the cytosol and mitochondria. VDACs have further been implicated in the control of regulated cell death. Historically, VDACs have been pictured as part of the mitochondrial permeability transition pore (MPTP). New concepts of regulated cell death involving VDACs include its oligomerisation to form a large pore complex in the OMM; however, alternative VDAC localisation to the plasma membrane has been suggested in the literature and will be discussed regarding its potential role during cell death. Very recently, a phospholipid scramblase activity has been attributed to VDAC dimers, which explains the manifold lipidomic changes observed in VDAC-deficient yeast strains. In this review, I highlight the recent advances regarding VDAC's phospholipid scramblase function and discuss how this new insight sheds new light on VDAC's implication in regulated cell death, autophagy, and ageing.

Breast cancer (BC) is the second deadliest cancer after lung cancer. Similar to all cancers, it is also driven by a 3D microenvironment. The extracellular matrix (ECM) is an essential component of the 3D tumor micro-environment, wherein it functions as a scaffold for cells and provides metabolic support. BC is characterized by alterations in the ECM. Various studies have attempted to mimic BC-specific ECMs using artificial materials, such as Matrigel. Nevertheless, research has proven that naturally derived decellularized extracellular matrices (dECMs) are superior in providing the essential in vivo-like cues needed to mimic a cancer-like environment. Developing in vitro 3-D BC models is not straightforward and requires extensive analysis of the data established by researchers. For the benefit of researchers, in this review, we have tried to highlight all developmental studies that have been conducted by various scientists so far. The analysis of the conclusions drawn from these studies is also discussed. The advantages and drawbacks of the decellularization methods employed for generating BC scaffolds will be covered, and the review will shed light on how dECM scaffolds help develop a BC environment. The later stages of the article will also focus on immunogenicity issues arising from decellularization and the origin of the tissue. Finally, this review will also discuss the biofabrication of matrices, which is the core part of the bioengineering process.

Extracellular vesicles (EVs) are lipid bilayer vesicles containing proteins, lipids, nucleic acids, and metabolites secreted by cells under various physiological and pathological conditions that mediate intercellular communication. The main types of EVs include exosomes, microvesicles, and apoptotic bodies (ABs). ABs are vesicles released during the terminal stages of cellular apoptosis, enriched with diverse biological entities and characterized by distinct morphological features. As a result, ABs possess great potential in fields like disease diagnosis, immunotherapy, regenerative therapy, and drug delivery due to their specificity, targeting capacity, and biocompatibility. However, their therapeutic efficacy is notably heterogeneous, and an overdose can lead to side effects such as accumulation in the liver, spleen, lungs, and gastrointestinal system. Through bioengineering, the properties of ABs can be optimized to enhance drug-loading efficiency, targeting precision, and multifunctionality for clinical implementations. This review focuses on strategies such as transfection, sonication, electroporation, surface engineering, and integration with biomaterials to enable ABs to load cargoes and enhance targeting, providing insights into the engineering of ABs.

Apoptosis is a genetically programmed form of cell death that is substantially conserved across the evolutionary tree. Apoptotic cell elimination includes recognition, phagocytosis, and degradation. Failure to clear apoptotic cells can ultimately cause a series of human diseases, such as systemic lupus erythematosus, Alzheimer's disease, atherosclerosis, and cancer. Consequently, the timely and effective removal of apoptotic cells is crucial to maintaining the body's homeostasis. GPCRs belong to the largest membrane receptor family. Its intracellular domain exerts an effect on the trimer G protein. By combining with a variety of ligands, the extracellular domain of G protein initiates the dissociation of G protein trimers and progressively transmits signals downstream. Presently, numerous G protein-coupled receptors (GPCRs) have been identified as participants in the apoptosis signal transduction pathway and the apoptotic cell clearance pathway. Therefore, studies on the mechanism of GPCRs in the clearance of apoptotic cells is important for the development of GPCRs therapeutics.

Cancer vaccines based on single-source (exogenous or endogenous) tumor-associated antigens (TAAs) are often challenged by the insufficient T cell response and the immunosuppressive tumor microenvironment (TME). Herein, a dual TAAs-boosted nanovaccine based on cancer cell (4T1) membrane-cloaked, CO-immobilized Prussian blue nanoparticles (4T1-PB-CO NPs) is developed and coupled with anti-interleukin (IL)-10 therapy to maximize the efficacy of antitumor immunotherapy. 4T1 cell membrane not only endows NPs with tumor targeting ability, but also serves as exogenous TAAs to trigger CD4+ T cell response and M1-phenotype polarization of tumor-associated macrophages. Under near-infrared light irradiation, 4T1-PB-CO NPs release CO to induce immunogenic cell death (ICD) of tumor cells, thus generating endogenous TAAs to activate CD8+ T cell response. Meanwhile, ICD triggers release of damage-associated molecular patterns, which can promote DC maturation to amplify the antitumor T cell response. When combined with anti-IL-10 that reverses the immunosuppressive TME, 4T1-PB-CO NPs efficiently suppress the primary tumors and produce an abscopal effect to inhibit distant tumors in a breast tumor-bearing mouse model. Such a two-pronged cancer vaccine represents a promising paradigm for robust antitumor immunotherapy.

Cognitive losses resulting from severe brain trauma have long been associated with the focal region of tissue damage, leading to devastating functional impairment. For decades, researchers have focused on the sequelae of cellular alterations that exist within the perilesional tissues; however, few clinical trials have been successful. Here, we employed a mouse brain injury model that resulted in expansive synaptic damage to regions outside the focal injury. Our findings demonstrate that synaptic damage results from the prolonged increase in D-serine release from activated microglia and astrocytes, which leads to hyperactivation of perisynaptic NMDARs, tagging of damaged synapses by complement components, and the reactivation of developmental pruning processes. We show that this mechanistic pathway is reversible at several stages within a prolonged and progressive period of synaptic loss. Importantly, these key factors are present in acutely injured brain tissue acquired from patients with brain injury, which supports a therapeutic neuroprotective strategy.

Planarian flatworms undergo continuous internal turnover, wherein old cells are replaced by the division progeny of adult pluripotent stem cells (neoblasts). How cell turnover is carried out at the organismal level remains an intriguing question in planarians and other systems. While previous studies have predominantly focused on neoblast proliferation, little is known about the processes that mediate cell loss during tissue homeostasis. Here, we use the planarian epidermis as a model to study the mechanisms of cell removal. We established a covalent dye-labeling assay and image analysis pipeline to quantify the cell turnover rate in the planarian epidermis. Our findings indicate that the ventral epidermis is highly dynamic and epidermal cells undergo internalization via basal extrusion, followed by a relocation toward the intestine and ultimately digestion by intestinal phagocytes. Overall, our study reveals a complex homeostatic process of cell clearance that may generally allow planarians to catabolize their own cells.

Rheumatoid arthritis (RA) combined with hashimoto thyroiditis (HT) is an important cause of various fatal comorbidities of RA. There is no precise conclusion about the cause of this disease.

Peripheral blood and synovial tissue were collected from healthy participants, patients with RA, and patients with both RA and HT. Immunofluorescence staining and Pearson correlation analysis were used to detect the levels of γδTCR and the correlation between IL-17 and p-STAT3, respectively. ELISA, chemiluminescence assays, qRT-PCR and Western blot were performed to detect the levels of IgG, IgM, IFN-γ, IL-1β, TNF-α, Tg-Ab, Tpo-Ab, IL-17, IL-2, p-SATA3, and STAT3, respectively.

There was increased proportion of γδT cells, IL-17, and p-STAT3 levels in RA and HT patients. IL-17 was positively correlated with p-STAT3. γδT cells significantly promoted the expression of IgG, Tg-Ab, Tpo-Ab, and IL-17. When γδT and human fibroblast-like synoviocytes (FLSs) were co-cultured, the levels of IL-2, IFN-γ, IL-1β, TNF-α, and IL-17 were increased, and the IL-17/STAT3 signaling pathway was activated. When IL-17-silenced γδT cells and STAT3-silenced FLSs were co-cultured, the levels of IL-1β and TNF-α in FLSs were significantly decreased. Furthermore, when STAT3-silenced FLSs were added to the co-culture medium of B cells and γδT cells, the levels of IL-1β and TNF-α were also decreased significantly.

γδT cells induced RA directly or by stimulating B cells to activate STAT3 through IL-17.

Carbon dots (CDs) are quasi-spherical carbon nanoparticles with excellent photoluminescence, good biocompatibility, favorable photostability, and easily modifiable surfaces. CDs, serving as fluorescent probes, have emerged as an ideal tool for cellular differentiation owing to their outstanding luminescence performance and tunable surface properties. In this review, we summarize the recent research progress with CDs in the differentiation of cancer/normal cells, Gram-positive/Gram-negative bacteria, and live/dead cells, as well as the cellular differences used for differentiation. Additionally, we summarize the preparation methods, raw materials, and properties of the CDs used for cell discrimination. The differentiation mechanisms and the advantages or limitations of the differentiation methods are also introduced. Finally, we propose several research challenges in this field and future research directions that require extensive investigation. It is hoped that this review will help researchers in the design of new CDs as ideal fluorescent probes for realizing diverse cell differentiation applications.

Toll-like receptors (TLRs) play a crucial role in mediating immune responses by recognizing pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), as well as facilitating apoptotic cell (ACs) clearance (efferocytosis), thus contributing significantly to maintaining homeostasis and promoting tissue resolution. In this study, we investigate the impact of TLR agonists on macrophage efferocytosis. Our findings demonstrate that pretreatment with the TLR agonist lipopolysaccharide (LPS) significantly enhances macrophage phagocytic ability, thereby promoting efferocytosis both in vitro and in vivo. Moreover, LPS pretreatment confers tissue protection against damage by augmenting macrophage efferocytic capacity in murine models. Further examination reveals that LPS modulates efferocytosis by upregulating the expression of Tim4.These results underscore the pivotal role of TLR agonists in regulating the efferocytosis process and suggest potential therapeutic avenues for addressing inflammatory diseases. Overall, our study highlights the intricate interplay between LPS pretreatment and efferocytosis in maintaining tissue homeostasis and resolving inflammation.

Systemic Lupus Erythematosus (SLE) is an autoimmune disease, the pathophysiology and genetic basis of which are incompletely understood. Using a forward genetic screen in multiplex families with systemic lupus erythematosus (SLE) we identified an association between SLE and compound heterozygous deleterious variants in the non-receptor tyrosine kinases (NRTKs) ACK1 and BRK. Experimental blockade of ACK1 or BRK increased circulating autoantibodies in vivo in mice and exacerbated glomerular IgG deposits in an SLE mouse model. Mechanistically, non-receptor tyrosine kinases (NRTKs) regulate activation, migration, and proliferation of immune cells. We found that the patients' ACK1 and BRK variants impair efferocytosis, the MERTK-mediated anti-inflammatory response to apoptotic cells, in human induced Pluripotent Stem Cell (hiPSC)-derived macrophages, which may contribute to SLE pathogenesis. Overall, our data suggest that ACK1 and BRK deficiencies are associated with human SLE and impair efferocytosis in macrophages.

Programmed cell death is an evolutionally conserved cellular process in multicellular organisms that eliminates unnecessary or rogue cells during development, infection, and carcinogenesis. Hematopoietic stem cells (HSCs) are a rare, self-renewing, and multipotent cell population necessary for the establishment and regeneration of the hematopoietic system. Counterintuitively, key components necessary for programmed cell death induction are abundantly expressed in long-lived HSCs, which often survive myeloablative stress by engaging a prosurvival response that counteracts cell death-inducing stimuli. Although HSCs are well known for their apoptosis resistance, recent studies have revealed their unique vulnerability to certain types of programmed necrosis, such as necroptosis and ferroptosis. Moreover, emerging evidence has shown that programmed cell death pathways can be sublethally activated to cause nonlethal consequences such as innate immune response, organelle dysfunction, and mutagenesis. In this review, we summarized recent findings on how divergent cell death programs are molecularly regulated in HSCs. We then discussed potential side effects caused by sublethal activation of programmed cell death pathways on the functionality of surviving HSCs.

Phagocytes remove dead and dying cells by engaging "eat-me" ligands such as phosphatidylserine (PtdSer) on the surface of apoptotic targets. However, PtdSer is obscured by the bulky exofacial glycocalyx, which also exposes ligands that activate "don't-eat-me" receptors such as Siglecs. Clearly, unshielding the juxtamembrane "eat-me" ligands is required for the successful engulfment of apoptotic cells, but the mechanisms underlying this process have not been described. Using human and murine cells, we find that apoptosis-induced retraction and weakening of the cytoskeleton that anchors transmembrane proteins cause an inhomogeneous redistribution of the glycocalyx: actin-depleted blebs emerge, lacking the glycocalyx, while the rest of the apoptotic cell body retains sufficient actin to tether the glycocalyx in place. Thus, apoptotic blebs can be engaged by phagocytes and are targeted for engulfment. Therefore, in cells with an elaborate glycocalyx, such as mucinous cancer cells, this "don't-come-close-to-me" barrier must be removed to enable clearance by phagocytosis.

Overnutrition, driven by the consumption of high-fat, high-sugar diets, has reached epidemic proportions and poses a significant global health challenge. Prolonged overnutrition leads to the deposition of excessive lipids in adipose and non-adipose tissues, a condition known as lipotoxicity. The intricate interplay between overnutrition-induced lipotoxicity and the immune system plays a pivotal role in the pathogenesis of various diseases. This review aims to elucidate the consequences of impaired efferocytosis, caused by lipotoxicity-poisoned macrophages, leading to chronic inflammation and the subsequent development of severe infectious diseases, autoimmunity, and cancer, as well as chronic pulmonary and cardiovascular diseases. Chronic overnutrition promotes adipose tissue expansion which induces cellular stress and inflammatory responses, contributing to insulin resistance, dyslipidemia, and metabolic syndrome. Moreover, sustained exposure to lipotoxicity impairs the efferocytic capacity of macrophages, compromising their ability to efficiently engulf and remove dead cells. The unresolved chronic inflammation perpetuates a pro-inflammatory microenvironment, exacerbating tissue damage and promoting the development of various diseases. The interaction between overnutrition, lipotoxicity, and impaired efferocytosis highlights a critical pathway through which chronic inflammation emerges, facilitating the development of severe infectious diseases, autoimmunity, cancer, and chronic pulmonary and cardiovascular diseases. Understanding these intricate connections sheds light on potential therapeutic avenues to mitigate the detrimental effects of overnutrition and lipotoxicity on immune function and tissue homeostasis, thereby paving the way for novel interventions aimed at reducing the burden of these multifaceted diseases on global health.

Periprosthetic joint infection (PJI) is a challenging complication that can occur following joint replacement surgery. Efficacious strategies to prevent and treat PJI and its recurrence remain elusive. Commensal bacteria within the gut convey beneficial effects through a defense strategy named "colonization resistance" thereby preventing pathogenic infection along the intestinal surface. This blueprint may be applicable to PJI. The aim is to investigate Lactobacillus acidophilus spp. and their isolated extracellular-derived proteins (LaEPs) on PJI-relevant Staphylococcus aureus, methicillin-resistant S. aureus, and Escherichia coli planktonic growth and biofilm formation in vitro. The effect of LaEPs on cultured macrophages and osteogenic, and adipogenic human bone marrow-derived mesenchymal stem cell differentiation is analyzed. Data show electrostatically-induced probiotic-pathogen species co-aggregation and pathogenic growth inhibition together with LaEP-induced biofilm prevention. LaEPs prime macrophages for enhanced microbial phagocytosis via cathepsin K, reduce lipopolysaccharide-induced DNA damage and receptor activator nuclear factor-kappa B ligand expression, and promote a reparative M2 macrophage morphology under chronic inflammatory conditions. LaEPs also significantly augment bone deposition while abating adipogenesis thus holding promise as a potential multimodal therapeutic strategy. Proteomic analyses highlight high abundance of lysyl endopeptidase, and urocanate reductase. Further, in vivo analyses are warranted to elucidate their role in the prevention and treatment of PJIs.

Granzyme B, mostly expressed by cytotoxic T lymphocytes in the fight against cancer and infection, is known to induce cell death based on its active enzymatic activity as a serine protease. Recent studies showed cytotoxicity of a non-enzymatic granzyme B-like peptide (also referred to as granzyme B-associated peptide or GP1 in this report) in tumor cells and presence of binding targets for GP1R (i.e., GP1 conjugated with rhodamine fluorochrome) in tumor cells, bacteria, and circulating platelets/neutrophils of healthy hosts. But there were no data on "sick" hosts to help substantiate any potential GP1 based medical applications. Thus, we adopted similar GP1R binding protocols to further study binding of GP1 in different biological samples (including different blood samples of hosts in sickness and in health, cancer cell lines, and trigeminal ganglia culture of infected hosts treated with and without GP1) and determine if any binding patterns might have any associations with different health conditions. The overall preliminary results appear to show certain GP1R + binding patterns in certain blood components (especially neutrophils) have potential correlations with certain health conditions of hosts at sampling times, indicating potential GP1R applications for diagnostic purposes. Findings of different GP1R binding patterns in different cancer cell lines, whole blood samples and trigeminal ganglia culture of experimental mice infected with HSV-1 virus (might cause neuropathy) within a week post-infection, and blood samples of GP1-treated mouse survivors on day 21 post-infection provided preliminary evidence of potential GP1-led tumor cell-specific cell death and treatment efficacy for greater survival.

The ongoing phagocytic activity of macrophages necessitates an extraordinary capacity to digest and resolve incoming material. While the initial steps leading to the formation of a terminal phagolysosome are well studied, much less is known about the later stages of this process, namely the degradation and resolution of the phagolysosomal contents. We report that the degradation of targets such as splenocytes and erythrocytes by phagolysosomes occurs in a stepwise fashion, requiring lysis of their plasmalemmal bilayer as an essential initial step. This is achieved by the direct extraction of cholesterol facilitated by Niemann-Pick protein type C2 (NPC2), which in turn hands off cholesterol to NPC1 for export from the phagolysosome. The removal of cholesterol ulimately destabilizes and permeabilizes the membrane of the phagocytic target, allowing access of hydrolases to its internal compartments. In contrast, we found that saposins, which activate the hydrolysis of sphingolipids, are required for lysosomal tubulation, yet are dispensable for the resolution of targets by macrophages. The extraction of cholesterol by NPC2 is therefore envisaged as rate-limiting in the clearance of membrane-bound targets such as apoptotic cells. Selective cholesterol removal appears to be a primary mechanism that enables professional phagocytes to distinguish the target membrane from the phagolysosomal membrane and may be conserved in the resolution of autolysosomes.

Atherosclerosis is the main cause of a series of fatal cardiovascular diseases, characterized by pathological accumulation of apoptotic cells and lipids. Pro-phagocytic antibody-based or pro-autophagy gene-based therapies are currently being explored to stimulate the phagocytic clearance of apoptotic cells and lipid metabolism; however, monotherapies are only moderately effective or require high doses with unacceptable side effects. Herein, we engineered a specific nano-bioconjugate loaded with antisense oligonucleotides (ASOs) of mammalian target of rapamycin (mTOR) and modified with anti-signal-regulated protein-α antibody (aSIRPα) for macrophage-mediated atherosclerosis therapy. The specific nano-bioconjugate utilized acid-responsive calcium phosphate (CaP) as a carrier to load mTOR ASOs, coated with lipid on the surface of CaP nanoparticles (ASOs@CaP), and subsequently modified with aSIRPα. The resulting nano-bioconjugates could accumulate within atherosclerotic plaques, target to macrophages and reactivate lesional phagocytosis through blocking the CD47-SIRPα signaling axis. In addition, efficient delivery of mTOR ASOs inhibited mTOR expression, which significantly restored impaired autophagy. The combined action of mTOR ASOs and aSIRPα reduced apoptotic cells and lipids accumulation. This nanotherapy significantly reduced plaque burden and inhibited progression of atherosclerotic lesions. These results show the potential of specific nano-bioconjugates for the prevention of atherosclerotic cardiovascular disease. STATEMENT OF SIGNIFICANCE: Atherosclerosis is the main cause of a series of fatal cardiovascular diseases. Pro-phagocytic antibody-based or pro-autophagy gene-based therapies are currently being explored to stimulate the phagocytic clearance of apoptotic cells and lipid metabolism; however, monotherapies are only moderately effective or require high doses with unacceptable side effects. Herein, we engineered a specific nano-bioconjugate loaded with antisense oligonucleotides (ASOs) of mammalian target of rapamycin (mTOR) and modified with anti-signal-regulated protein-α antibody (aSIRPα) for macrophage-mediated atherosclerosis therapy. Our study demonstrated that the combined action of mTOR ASOs and aSIRPα reduced apoptotic cells and lipids accumulation. This nanotherapy significantly reduced plaque burden and inhibited progression of atherosclerotic lesions. These results show the potential of specific nano-bioconjugates for the prevention of atherosclerotic cardiovascular disease.

Cytotoxic chemo-, radio-, and targeted therapies frequently elicit apoptotic cancer cell death. Mitochondrial outer membrane permeabilization (MOMP) is a critical, regulated step in this apoptotic pathway. The residual cancer cells that survive treatment serve as the seeds of eventual relapse and are often functionally characterized by their transient tolerance of multiple therapeutic treatments. New studies suggest that, in these cells, a sublethal degree of MOMP, reflective of incomplete apoptotic commitment, is widely observed. Here, we review recent evidence that this sublethal MOMP drives the aggressive features of residual cancer cells while templating a host of unique vulnerabilities, highlighting how failed apoptosis may counterintuitively enable new therapeutic strategies to target residual disease (RD).

Three-dimensional bioprinting is an emerging technology that has high potential application in tissue engineering and regenerative medicine. Increasing advancement and improvement in the decellularization process have led to an increase in the demand for using a decellularized extracellular matrix (dECM) to fabricate tissue engineered products. Decellularization is the process of retaining the extracellular matrix (ECM) while the cellular components are completely removed to harvest the ECM for the regeneration of various tissues and across different sources. Post decellularization of tissues and organs, they act as natural biomaterials to provide the biochemical and structural support to establish cell communication. Selection of an effective method for decellularization is crucial, and various factors like tissue density, geometric organization, and ECM composition affect the regenerative potential which has an impact on the end product. The dECM is a versatile material which is added as an important ingredient to formulate the bioink component for constructing tissue and organs for various significant studies. Bioink consisting of dECM from various sources is used to generate tissue-specific bioink that is unique and to mimic different biometric microenvironments. At present, there are many different techniques applied for decellularization, and the process is not standardized and regulated due to broad application. This review aims to provide an overview of different decellularization procedures, and we also emphasize the different dECM-derived bioinks present in the current global market and the major clinical outcomes. We have also highlighted an overview of benefits and limitations of different decellularization methods and various characteristic validations of decellularization and dECM-derived bioinks.

Decades of research have shown that two-dimensional cell culture studies are insufficient for preclinical cancer diagnosis and treatment, and that cancer cells in three-dimensional (3D) culture systems have better cell-cell and cell-matrix interactions, gene expression, heterogeneity, and structural complexity that more closely resemblein vivotumors. Researchers are still optimizing 3D culturing settings for different cancers. Despite promising tumor spheroid research, tumor cell-only aggregates lack the tumor microenvironment and cannot model tumors. Here, MCF-7 breast cancer cell derived decellularized extracellular matrix (CD-dECMs) were obtained and converted into autologous, biologically active, biocompatible, and non-immunogenic hydrogels to be used as micro-environment in both organoid formation and culture. For the production of organoids, CD-dECM doping concentrations ranging from 0.1 mg ml-1to 1.5 mg ml-1were evaluated, and the lowest concentration was found to be the most effective. For organoid culture, 8 mg ml-1CD-dECM, 4 mg ml-1rat tendon collagen type I (Col I) (4 mg ml-1) and a 1:1 (v/v) mixture of these two were used and the most viable and the biggest organoids were discovered in CD-dECM/Col I (1:1) group. The results show that autologous CD-dECM can replace hydrogels in tumor organoid generation and culture at low and high concentrations, respectively.

Advancements in regenerative medicine have highlighted the potential of decellularized extracellular matrix (ECM) as a scaffold for organ bioengineering. Although the potential of ECM in major organ systems is well-recognized, studies focusing on the angiogenic effects of pancreatic ECM are limited. This study investigates the capabilities of pancreatic ECM, particularly its role in promoting angiogenesis. Using a Triton-X-100 solution, porcine pancreas was successfully decellularized, resulting in a significant reduction in DNA content (97.1% removal) while preserving key pancreatic ECM components. A three-dimensional ECM hydrogel was then created from this decellularized tissue and used for cell culture. Biocompatibility tests demonstrated enhanced adhesion and proliferation of mouse embryonic stem cell-derived endothelial cells (mES-ECs) and human umbilical vein endothelial cells (HUVECs) in this hydrogel compared to conventional scaffolds. The angiogenic potential was evaluated through tube formation assays, wherein the cells showed superior tube formation capabilities in ECM hydrogel compared to rat tail collagen. The RT-PCR analysis further confirmed the upregulation of pro-angiogenic genes in HUVECs cultured within the ECM hydrogel. Specifically, HUVECs cultured in the ECM hydrogel exhibited a significant upregulation in the expression of MMP2, VEGF and PAR-1, compared to those cultured in collagen hydrogel or in a monolayer condition. The identification of ECM proteins, specifically PRSS2 and Decorin, further supports the efficacy of pancreatic ECM hydrogel as an angiogenic scaffold. These findings highlight the therapeutic promise of pancreatic ECM hydrogel as a candidate for vascularized tissue engineering application.

Studies trying to understand cell death, this ultimate biological process, can be traced back to a century ago. Yet, unlike many other fashionable research interests, research on cell death is more alive than ever. New modes of cell death are discovered in specific contexts, as are new molecular pathways. But what is "cell death", really? This question has not found a definitive answer yet. Nevertheless, part of the answer is irreversibility, whereby cells can no longer recover from stress or injury. Here, we identify the most distinctive features of different modes of cell death, focusing on the executive final stages. In addition to the final stages, these modes can differ in their triggering stimulus, thus referring to the initial stages. Within this framework, we use a few illustrative examples to examine how intercellular communication factors in the demise of cells. First, we discuss the interplay between cell-cell communication and cell death during a few steps in the early development of multicellular organisms. Next, we will discuss this interplay in a fully developed and functional tissue, the gut, which is among the most rapidly renewing tissues in the body and, therefore, makes extensive use of cell death. Furthermore, we will discuss how the balance between cell death and communication is modified during a pathological condition, i.e., colon tumorigenesis, and how it could shed light on resistance to cancer therapy. Finally, we briefly review data on the role of cell-cell communication modes in the propagation of cell death signals and how this has been considered as a potential therapeutic approach. Far from vainly trying to provide a comprehensive review, we launch an invitation to ponder over the significance of cell death diversity and how it provides multiple opportunities for the contribution of various modes of intercellular communication.

Discovery of new small molecules that can activate distinct programmed cell death pathway is of significant interest as a research tool and for the development of novel therapeutics for pathological conditions such as cancer and infectious diseases. The small molecule raptinal was discovered as a pro-apoptotic compound that can rapidly trigger apoptosis by promoting the release of cytochrome c from the mitochondria and subsequently activating the intrinsic apoptotic pathway. As raptinal is very effective at inducing apoptosis in a variety of different cell types in vitro and in vivo, it has been used in many studies investigating cell death as well as the clearance of dying cells. While examining raptinal as an apoptosis inducer, we unexpectedly identified that in addition to its pro-apoptotic activities, raptinal can also inhibit the activity of caspase-activated Pannexin 1 (PANX1), a ubiquitously expressed transmembrane channel that regulates many cell death-associated processes. By implementing numerous biochemical, cell biological and electrophysiological approaches, we discovered that raptinal can simultaneously induce apoptosis and inhibit PANX1 activity. Surprisingly, raptinal was found to inhibit cleavage-activated PANX1 via a mechanism distinct to other well-described PANX1 inhibitors such as carbenoxolone and trovafloxacin. Furthermore, raptinal also interfered with PANX1-regulated apoptotic processes including the release of the 'find-me' signal ATP, the formation of apoptotic cell-derived extracellular vesicles, as well as NLRP3 inflammasome activation. Taken together, these data identify raptinal as the first compound that can simultaneously induce apoptosis and inhibit PANX1 channels. This has broad implications for the use of raptinal in cell death studies as well as in the development new PANX1 inhibitors.