Liver fibrosis is characterized by an abnormal accumulation of extracellular matrix proteins, leading to impaired liver function. The pyruvate dehydrogenase alpha 1 (PDHA1) gene, encoding the E1 alpha subunit of the pyruvate dehydrogenase complex, has demonstrated reduced expression in pulmonary fibrosis, suggesting a protective role in fibrotic diseases. This study aimed to identify PDHA1-related gene signatures and explore potential targets for liver fibrosis treatment. Datasets GSE15654 and GSE84044 were sourced from the gene expression omnibus database. Prognostic genes were identified through Pearson correlation analysis, LASSO, and Cox regression in the discovery dataset (GSE15654) and validated using the verification dataset (GSE84044). A prognostic model was constructed and validated with quantitative reverse transcriptase-PCR analysis on surgical resection samples. High PDHA1 expression correlated with improved prognosis in liver fibrosis. Four PDHA1-related prognostic genes (ALDH9A1, ARG1, APOH, and FABP1) were identified as protective factors. Our model accurately predicted patient prognosis, and initial validation with clinical samples supported these conclusions. The prognostic model based on PDHA1-related genes (ALDH9A1, ARG1, APOH, and FABP1) effectively predicts liver fibrosis progression and prognosis. This research provides a novel approach for liver fibrosis prediction and potential treatment strategies.

Epidemiological evidence suggests that environmental pollutants precipitate the occurrence of allergic rhinitis (AR). The aryl hydrocarbon receptor (AhR), a receptor or sensor for various contaminants, is closely related to immunomodulation and the polarization of M2 macrophages. However, the mechanisms involving AhR and M2 macrophages in AR remain unclear.

Bioinformatics analysis of GEO datasets (GSE180697 and GSE180697) assessed AhR and IL4I1 expression levels, which were then verified in the nasal mucosa, monocytes and serum of patients with AR using western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). Primary human mononuclear cells were isolated from peripheral blood using a magnetic separation technique, and THP-1 cell lines with IL4I1 overexpression or downexpression were established through lentiviral constructs. M2 macrophages were induced with the cytokines CSF, IL4 and IL13 and then treated with the AhR agonist FICZ or inhibitor CH223191. The polarization of M2 macrophages was measured by flow cytometry and western blotting. Furthermore, primary nasal epithelial cells and macrophages were co-cultured to assess the epithelial-mesenchymal transition (EMT) in epithelial cells. The AR murine model was established using ovalbumin (OVA). Inflammation within the nasal mucosa and lung tissue was examined after CH223191 or IL4I1 treatment.

Nuclear translocation of AhR and upregulation of IL4I1 was observed in peripheral mononuclear cells and nasal mucosal tissue of patients with AR. Through the activation of AhR, IL4I1 promoted M2 macrophage polarization. Furthermore, modulation of the IL4I1/AhR axis regulated the migratory impact of OVA on T-M2 cells. The IL4I1/AhR axis was involved in the regulation of M2 macrophage-associated EMT and contributed to the expression of IL-33 and STAT6 phosphorylation in epithelial cells. In AR mice, increased AhR nuclear translocation and higher expression of IL4I1 and the M2 macrophage marker CD206 in the lungs was observed. The IL4I1/AhR axis exacerbated allergic symptoms in AR mice, fostering allergic inflammation within the nasal mucosa and lungs.

The IL4I1/AhR axis is activated within the mononuclear phagocyte system of patients with AR. This activation facilitates the polarization of mononuclear cells into M2 macrophages, which further aggravates EMT in epithelial cells and exacerbates inflammation in AR. This study may provide novel strategies for the precise treatment of AR.

Arginase activity and arginine metabolism in immune cells have important consequences for health and disease. Their dysregulation is commonly observed in cancer, autoimmune disorders and infectious diseases. Following the initial description of a role for arginase in the dysfunction of T cells mounting an antitumour response, numerous studies have broadened our understanding of the regulation and expression of arginases and their integration with other metabolic pathways. Here, we highlight the differences in arginase compartmentalization and storage between humans and rodents that should be taken into consideration when assessing the effects of arginase activity. We detail the roles of arginases, arginine and its metabolites in immune cells and their effects in the context of cancer, autoimmunity and infectious disease. Finally, we explore potential therapeutic strategies targeting arginases and arginine.

Macrophages are immune cells belonging to the mononuclear phagocyte system. They play crucial roles in immune defense, surveillance, and homeostasis. This review systematically discusses the types of hematopoietic progenitors that give rise to macrophages, including primitive hematopoietic progenitors, erythro-myeloid progenitors, and hematopoietic stem cells. These progenitors have distinct genetic backgrounds and developmental processes. Accordingly, macrophages exhibit complex and diverse functions in the body, including phagocytosis and clearance of cellular debris, antigen presentation, and immune response, regulation of inflammation and cytokine production, tissue remodeling and repair, and multi-level regulatory signaling pathways/crosstalk involved in homeostasis and physiology. Besides, tumor-associated macrophages are a key component of the TME, exhibiting both anti-tumor and pro-tumor properties. Furthermore, the functional status of macrophages is closely linked to the development of various diseases, including cancer, autoimmune disorders, cardiovascular disease, neurodegenerative diseases, metabolic conditions, and trauma. Targeting macrophages has emerged as a promising therapeutic strategy in these contexts. Clinical trials of macrophage-based targeted drugs, macrophage-based immunotherapies, and nanoparticle-based therapy were comprehensively summarized. Potential challenges and future directions in targeting macrophages have also been discussed. Overall, our review highlights the significance of this versatile immune cell in human health and disease, which is expected to inform future research and clinical practice.

In a rapidly expanding body of literature, the major role of energy metabolism in determining the response and polarization status of macrophages has been examined, and it is currently a very active area of research. The metabolic flux through different metabolic pathways in the macrophage is interconnected and complex and could influence the polarization of macrophages. Earlier studies suggested glucose flux through cytosolic glycolysis is a prerequisite to trigger the pro-inflammatory phenotypes of macrophages while proposing that fatty acid oxidation is essential to support anti-inflammatory responses by macrophages. However, recent studies have shown that this understanding is oversimplified and that the metabolic control of macrophage polarization is highly complex and not fully defined yet. In this review, we systematically reviewed and summarized the literature regarding the role of energy metabolism in controlling macrophage activity and how that might be altered in cardiometabolic diseases, namely heart failure, obesity, and diabetes. We critically appraised the experimental studies and methodologies in the published studies. We also highlighted the challenging concepts in macrophage metabolism and identified several research questions yet to be addressed in future investigations.

Macrophage metabolic reprogramming has a central role in the progression of autoimmune and auto-inflammatory diseases. The heart is a major target organ in many autoimmune conditions and can sustain functional and structural impairments, potentially leading to irreversible cardiac damage. There is mounting clinical evidence pointing to a link between autoimmune disease and cardiac damage. However, this association remains poorly understood, and numerous patients do not receive appropriate preventive measures, which poses serious cardiovascular risks and significantly impacts their quality of life. This review discusses the relationship between macrophage metabolic reprogramming and cardiac damage in patients with autoimmune diseases and the role of adaptive immunity in macrophage reprogramming. It also provides an overview of the immunosuppressive therapies used at present. Exploiting the properties of macrophage reprogramming could lead to development of novel treatments for patients with autoimmune-related cardiac damage.

Sepsis is a systemic inflammatory condition associated with severe organ failure, particularly splenic injury. Fraxetin (Fra), a natural product isolated from ash bark, exhibits anti-inflammatory and antioxidant properties. This study explores the function and mechanism of Fra in sepsis-induced splenic injury using an in vivo mouse model induced by Cecal Ligation and Puncture and an in vitro sepsis model based on LPS/ATP co-stimulated J774A.1 cells. The experimental groups are as follows: Sham operation or control group, Fra control group, CLP or LPS/ATP group, CLP + Fra group or LPS/ATP + Fra group, with Dexamethasone as a positive control. The results indicated that Fra improved the survival rate, inhibited bacteria burden, and reduced spleen edema. Fra also alleviated spleen necrosis, and restored the structural integrity. Blood results showed that Fra restored platelet count and lymphocyte percentage, reduced neutrophil ratio and C-reactive protein increase, and prevented lymphocyte depletion. Immunohistochemistry demonstrated that Fra inhibited MPO levels. Additionally, Fra downregulated Procalcitonin, inhibited pro-inflammatory cytokines, NO release and Arg-1 expression, illustrating its anti-inflammatory effects. DHE staining revealed that Fra inhibited ROS and MDA, enhanced CAT, GSH-PX, and SOD activities. Furthermore, Fra inhibited NLRP3 inflammasome activation, p-IKKβ expression and NF-κB pathway. Mechanistically, molecular docking studies revealed that Fra could bind to IKKβ, thereby blocking the NF-κB pathway and NLRP3 inflammasome, functioning anti-inflammatory effects. In summary, Fra targets IKKβ to block the NF-κB pathway and NLRP3 inflammasome activation, alleviating sepsis-induced splenic injury, making it a promising therapeutic strategy for treating sepsis-induced splenic injury.

Osteoporosis results from a disruption in skeletal homeostasis caused by an imbalance between bone resorption and bone formation. Conventional treatments, such as pharmaceutical drugs and hormone replacement therapy, often yield suboptimal results and are frequently associated with side effects. Recently, biomaterial-based approaches have gained attention as promising alternatives for managing osteoporosis. This review summarizes the current advancements in 3D-printed biomaterials designed for osteoporosis treatment. The benefits of biomaterial-based approaches compared to traditional systemic drug therapies are discussed. These 3D-printed materials can be broadly categorized based on their functionalities, including promoting osteogenesis, reducing inflammation, exhibiting antioxidant properties, and inhibiting osteoclast activity. 3D printing has the advantages of speed, precision, personalization, etc. It is able to satisfy the requirements of irregular geometry, differentiated composition, and multilayered structure of articular osteochondral scaffolds with boundary layer structure. The limitations of existing biomaterials are critically analyzed and future directions for biomaterial-based therapies are considered.

Metabolic flexibility is key for the function of myeloid cells. Arginine metabolism is integral to the regulation of myeloid cell responses. Nitric oxide (NO) production from arginine is vital for the antimicrobial and pro-inflammatory responses. Conversely, the arginase 1 (ARG1)-dependent switch between the branch of NO production and polyamine synthesis downregulates inflammation and promotes recovery of tissue homeostasis. Creatine metabolism is key for energy supply and proline metabolism is required for collagen synthesis. Myeloid ARG1 also regulates extracellular arginine availability and T cell responses in parasitic diseases and cancer. Cancer, surgery, sepsis and persistent inflammation in chronic inflammatory diseases, such as neuroinflammatory diseases or arthritis, are associated with dysregulation of arginine metabolism in myeloid cells. Here, we review current knowledge on arginine metabolism in different myeloid cell types, such as macrophages, neutrophils, microglia, osteoclasts, tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs) and myeloid-derived suppressor cells (MDSCs). A deeper understanding of the function of arginine metabolism in myeloid cells will improve our knowledge on the pathology of several diseases and may set the platform for novel therapeutic applications.

Selenium (Se), a critically essential trace element, plays a crucial role in diverse physiological processes within the human body, such as oxidative stress response, inflammation regulation, apoptosis, and lipid metabolism. Organ fibrosis, a pathological condition caused by various factors, has become a significant global health issue. Numerous studies have demonstrated the substantial impact of Se on fibrotic diseases. This review delves into the latest research advancements in Se and Se-related biological agents for alleviating fibrosis in the heart, liver, lungs, and kidneys, detailing their mechanisms of action within fibrotic pathways. Additionally, the article summa-rizes some of the anti-fibrotic drugs currently in clinical trials for the aforementioned organ fibroses.

Rationale: The mannose receptor (CD206, expressed by the gene Mrc1) is a surface marker overexpressed by anti-inflammatory and pro-tumoral macrophages. As such, CD206+ macrophages play key roles in the immune response to different pathophysiological conditions and represent a promising diagnostic and therapeutic target. However, methods to specifically target these cells remain challenging. In this study, we describe a multi-mannose approach to develop CD206-targeting fluorescent and MRI agents that specifically and sensitively detect and monitor CD206+ macrophage immune response in different disease conditions. Methods: We designed and synthesized fluorescent agents MR1-cy5 and MR2-cy5, and MRI agents Mann2-DTPA-Gd and MannGdFish. Cellular assays using pro-inflammatory and anti-inflammatory macrophages differentiated from RAW 264.7 cells were performed, and signals were detected by fluorescence microscopy and inductively coupled plasma mass spectrometry (ICP-MS) to validate specificity in vitro. In vivo specificity and efficacy of the agents were evaluated by MRI in a subcutaneous wound healing model and experimental glioma with Mrc1 +/+ without and with D-mannose treatment, Mrc1 +/-, and Mrc1 -/- mice, and in stroke. One-way ANOVA and two-way ANOVA tests were used for data analysis. P < 0.05 was considered statistically different. Results: Both in vitro fluorescence imaging with MR2-cy5, ICP-MS with Mann2-DTPA-Gd, and in vivo MRI in Mrc1 -/- mice confirmed the specificity of our approach. Mann2-DTPA-Gd MRI can track the changes of CD206+ macrophages at different stages of wound healing, correlating well with flow cytometry data using another anti-inflammatory macrophage marker (arginase-1). The specificity and efficacy of Mann2-DPTA-Gd were further validated in experimental glioma, in which Mann2-DTPA-Gd imaging detected CD206+ tumor-associated macrophages (TAMs), demonstrated significantly decreased signals in Mrc1 +/- mice and Mrc1 -/- mice, and tracked treatment changes in D-mannose-treated Mrc1 +/+ mice. Furthermore, Mann2-DTPA-Gd can report microglia/macrophages and correlate with histology in stroke. The more Gd-stable agent MannGdFish demonstrated similar efficacy as Mann2-DTPA-Gd in vivo with favorable biodistribution and pharmacokinetics. Conclusion: We have developed a fluorescent agent (MR2-cy5) and MRI agents (Mann2-DTPA-Gd and MannGdFish) with two mannose moieties that are highly specific to CD206 and can track CD206+ macrophages in disease models of wound healing, tumor, and neurological disease. Importantly, MannGdFish, with its high specificity, stability, favorable biodistribution, and pharmacokinetics, is a promising translational candidate to noninvasively monitor CD206+ macrophages in repair/regeneration and tumors in patients. In addition, with the specific binding motif to CD206, other imaging modalities and therapeutic agents could also be introduced for theranostic applications.

The molecular mechanisms by which worm parasites evade host immunity are incompletely understood. In a mouse model of intestinal helminth infection using Heligmosomoides polygyrus bakeri (Hpb), we show that helminthic glutamate dehydrogenase (heGDH) drives parasite chronicity by suppressing macrophage-mediated host defense. Combining RNA-seq, ChIP-seq, and targeted lipidomics, we identify prostaglandin E2 (PGE2) as a major immune regulatory mechanism of heGDH. The induction of PGE2 and other immunoregulatory factors, including IL-12 family cytokines and indoleamine 2,3-dioxygenase 1, by heGDH required p300-mediated histone acetylation, whereas the enzyme's catalytic activity suppressed the synthesis of type 2-promoting leukotrienes by macrophages via 2-hydroxyglutarate. By contrast, the induction of immunoregulatory factors involved the heGDH N terminus by potentially mediating interactions with cellular targets (CD64 and GPNMB) identified by proteomics. Type 2 cytokines counteracted suppressive effects of heGDH on host defense, indicating that type 2 immunity can limit helminth-driven immune evasion. Thus, helminths harness a ubiquitous metabolic enzyme to epigenetically target type 2 macrophage activation and establish chronicity.

Human papilloma virus (HPV) infections vary in their oncogenic potential, and whether an infection progresses to cervical intraepithelial neoplasia (CIN) also depends on the immune response. Therefore, the aim of the present study was to explore biomarkers related to the immune system and cell proliferation, in combination with HPV classified as having high (HOP) or low oncogenic potential (LOP), that can possibly guide a more accurate identification of women following cervical cancer screening programmes in need for immediate follow-up with a biopsy. A next-generation sequencing transcriptomic immune profile analysis applied to 28 persistent CIN3 lesions and 14 normal biopsies identified four genes, the immune markers ARG1 and HLA-DQB2 and the tumour markers CDKN2A and KRT7, as possible markers for differentiating between CIN3 and normal tissue. To validate these findings, analysis of the relative gene expression of these markers by use of reverse transcriptase real-time quantitative polymerase chain reaction was performed in an independent cohort of 264 (82 normal, 64 CIN1, and 118 CIN2/CIN3) biopsies, and the data were combined with information on the HOP- or LOP-HPV identified in the biopsies. Statistical analysis was performed with receiver operating characteristic curves, reporting area under the curve (AUC) with 95% confidence intervals (CIs), and logistic regression. Statistically significantly higher median expression levels of CDKN2A (p < 0.001) and KRT7 (p = 0.045) and significantly lower expression of ARG1 (p = 0.012) were found in biopsies with HOP-HPV infections, with no difference detected for HLA-DQB2 (p = 0.82). Models using expression levels of CDKN2A (AUC, 0.91; 95% CI, 0.86-0.95), KRT7 (0.86, 0.81-0.91), or ARG1 (0.78, 0.70-0.85) together with HOP/LOP-HPV class were significantly better than HPV class alone (0.72, 0.66-0.79) in discriminating CIN2/3 versus CIN1 (p < 0.001, p < 0.001, and p = 0.014, respectively).

Mucosal healing is associated with better clinical outcomes in patients with inflammatory bowel disease. But the epithelial-specific contribution to mucosal healing in vivo is poorly understood. We evaluated mucosal healing in an acute dextran sulfate sodium mouse model that shows an alleviated colitis response after epithelial-specific loss of Smad4. We find that enhanced epithelial wound healing alleviates the fibrotic response. Dextran sulfate sodium caused increased mesenchymal collagen deposition-indicative of fibrosis-within a week in the WT but not in the Smad4 KO colon. The fibrotic response correlated with decreased epithelial proliferation in the WT, whereas uninterrupted proliferation and an expanded zone of proliferation were observed in the Smad4 KO colon epithelium. Furthermore, the Smad4 KO colon showed epithelial extracellular matrix alterations that promote epithelial regeneration. Our data suggest that epithelium is a key determinant of the mucosal healing response in vivo, implicating mucosal healing as a strategy against fibrosis in inflammatory bowel disease patients.

Schistosomiasis is characterized by egg-induced hepatic granulomas and subsequent fibrosis. Monocyte-derived macrophages play critical and plastic roles in the progression and regression of liver fibrosis, adopting different polarization phenotypes. Mammalian STE20-like protein kinase 1 (MST1), a serine/threonine kinase, has been established to act as a negative regulator of macrophage-associated inflammation. However, the specific role of MST1 in Schistosoma-induced liver fibrosis has not been fully understood. In this study, we demonstrate that macrophage MST1 functions as an inhibitor of inflammation and fibrosis following infection with Schistosoma japonicum (S. japonicum). Mice with macrophages-specific Mst1 knockout (termed Mst1△M/△M) mice developed exacerbated liver pathology, characterized by larger egg-induced granulomas, and increased fibrosis post infection. This was accompanied by enhanced production of proinflammatory cytokines (IL1B, IL6, IL23, TNFA and TGFB) and a shift in macrophage phenotype towards Ly6Chigh. Mechanistically, MST1 activation by soluble egg antigen (SEA) promoted PPARγ-mediated CD36 expression, enhancing phagocytosis and consequently upregulation of fibrolytic genes such as Arg1 and Mmps. Conversely, MST1 deletion leads to up-regulation of pro-inflammatory genes instead of fibrolytic genes in macrophages, accompanied by decreased expression of CD36 and impaired phagocytosis. Furthermore, the ablation of MST1 enhances NF-κB activation in S. japonicum-infected and SEA-stimulated macrophages, resulting in increased production of proinflammatory cytokines. Overall, our data identified MST1 as a novel regulator for egg-induced liver fibrosis via modulation of macrophage function and phenotype by CD36-mediated phagocytosis and suppression of NF-κB pathway.

Abnormal scarring imposes considerable challenges and burdens on the lives of patients and healthcare system. Macrophages at the wound site are found to be of great concern to overall wound healing. There have been many studies indicating an inextricably link between dysfunctional macrophages and fibrotic scars. Macrophages are not only related to pathogen destruction and phagocytosis of apoptotic cells, but also involved in angiogenesis, keratinization and collagen deposition. These abundant cell functions are attributed to specific heterogeneity and plasticity of macrophages, which also add an extra layer of complexity to correlational researches.

This article summarizes current understanding of macrophage polarization in scar formation and several prevention and treatment strategies on pathological scarring related to regulation of macrophage behaviors by utilizing databases such as PubMed, Google Scholar and so on.

There are many studies proving that macrophages participate in the course of wound healing by converting their predominant phenotype. The potential of macrophages in managing hypertrophic scars and keloid lesions have been underscored.

Macrophage polarization offers new prevention strategies for pathological scarring. Learning about and targeting at macrophages may be helpful in achieving optimum wound healing.

Riboflavin kinase (RFK) is essential in riboflavin metabolism, converting riboflavin to flavin mononucleotide (FMN), which is further processed to flavin adenine dinucleotide (FAD). While RFK enhances macrophage phagocytosis of Listeria monocytogenes, its role in macrophage polarization is not well understood. Our study reveals that RFK deficiency impairs M(IFN-γ) and promotes M(IL-4) polarization, both in vitro and in vivo. Mechanistically, RFK interacts with inducible nitric oxide (NO) synthase (iNOS), which requires FMN and FAD as cofactors for activation, leading to increased NO production that alters energy metabolism by inhibiting the tricarboxylic acid cycle and mitochondrial electron transport chain. Exogenous FAD reverses the metabolic and polarization changes caused by RFK deficiency. Furthermore, bone marrow adoptive transfer from high-riboflavin-fed mice into wild-type tumor-bearing mice reprograms tumor-associated macrophage polarization and inhibits tumor growth. These results suggest that targeting RFK-iNOS or modulating riboflavin metabolism could be potential therapies for macrophage-related immune diseases.

Herbacetin, a flavonol abundant in traditional medicines, is documented as an anti-inflammatory agent. However, information regarding its attributes on lipopolysaccharide (LPS)-induced inflammatory immunopathies has not been delineated yet. The present study aimed to comprehend herbacetin effects on LPS-induced aspects of unwarranted, non-resolving inflammation, particularly via targeting the vicious circle of oxi-inflammatory stress, autophagy-apoptosis, macrophages polarization, impaired inflammasome activation, and inflammatory cascades.

In-vitro model of LPS-stimulated RAW 264.7 macrophage was recapitulated to investigate different inflammatory anomalies using enzyme-linked immunosorbent assay, qRT-PCR (Real-Time Quantitative Reverse Transcription PCR), immunoblotting. Concanavalin A challenged splenocytes and in silico studies were performed to measure Tregs population and binding affinity, respectively.

Herbacetin administration caused remarkable reduction in nitric oxide, reactive oxygen species, mitochondrial membrane potential hyperpolarization, tumor necrosis factor-α, interferon-γ, interleukin-6, inducible nitric oxide synthase and ratio of M1/M2 markers (inducible nitric oxide synthase/arginase-1/macrophage scavenger receptor-1/mannose receptor C type-1) in in vitro model of persistent inflammation. Suppression of interleukins-5,17 and matrix metalloproteinases-2,3,9,13 and proliferating cell nuclear antigen, signifies its anti-inflammatory attributes. Noticeable decline in monodansylcadaverine-Lysotracker staining, caspase-6, and enhanced p62, B-cell lymphoma-2 expression indicates apoptosis-autophagosome accumulation inhibition and lysosomal destabilization. These were accompanied by reduced NLRP3 activation, caspase-1, AIM-2 expression, and interleukin-1β release. Subsequently, up-regulated activation of TLR-4, NF-κB, PI3K, Akt, ERK1/2, and JNK was decisively thwarted by herbacetin. In silico investigation signified the interaction of herbacetin with these targets. Decreased cytokines and enhanced Tregs conferred its role in extenuating inflammation facilitated by T-cells depletion.

Collectively, these findings comprehend attributes of herbacetin as an alternative therapeutic strategy in relieving LPS-associated chronic inflammatory disorders.

Numerous viruses that propagate through the respiratory tract may be initially engulfed by macrophages (Mφs) within the alveoli, where they complete their first replication cycle and subsequently infect the adjacent epithelial cells. This process can lead to significant pathological damage to tissues and organs, leading to various diseases. As essential components in host antiviral immune systems, Mφs can be polarized into pro-inflammatory M1 Mφs or anti-inflammatory M2 Mφs, a process involving multiple signaling pathways and molecular mechanisms that yield diverse phenotypic and functional features in response to various stimuli. In general, when infected by a virus, M1 macrophages secrete pro-inflammatory cytokines to play an antiviral role, while M2 macrophages play an anti-inflammatory role to promote the replication of the virus. However, recent studies have shown that some viruses may exhibit the opposite trend. Viruses have evolved various strategies to disrupt Mφ polarization for efficient replication and transmission. Notably, various factors, such as mechanical softness, the altered pH value of the endolysosomal system, and the homeostasis between M1/M2 Mφs populations, contribute to crucial events in the viral replication cycle. Here, we summarize the regulation of Mφ polarization, virus-induced alterations in Mφ polarization, and the antiviral mechanisms associated with these changes. Collectively, this review provides insights into recent advances regarding Mφ polarization in host antiviral immune responses, which will contribute to the development of precise prevention strategies as well as management approaches to disease incidence and transmission.

Wound dressing changes are essential procedures for wound management. However, ~50% of patients experience severe pain during these procedures despite the availability of analgesic medications, indicating a need for novel therapeutics that address underlying causes of pain. Along with other clinical factors, wound pathogens and inflammatory immune responses have previously been implicated in wound pain. To test whether these factors could contribute to severe pain during wound dressing changes, we conducted an exploratory, cross-sectional analysis of patient-reported pain, inflammatory immune responses, and wound microbiome composition in 445 wounds at the time of a study dressing change. We profiled the bacterial composition of 406 wounds using 16S ribosomal RNA amplicon sequencing and quantified gene expression of 13 inflammatory markers in wound fluid using quantitative real-time polymerase chain reaction (qPCR). Neither inflammatory gene expression nor clinically observed inflammation were associated with severe pain, but Corynebacterium and Streptococcus were of lower relative abundance in wounds of patients reporting severe pain than those reporting little or no pain. Wound microbiome composition differed by wound location, and correlated with six of the inflammatory markers, including complement receptor C5AR1, pro-inflammatory cytokine interleukin (IL)1β, chemokine IL-8, matrix metalloproteinase MMP2, and the antimicrobial peptide encoding cathelicidin antimicrobial peptide. Interestingly, we found a relationship between the wound microbiome and vacuum-assisted wound closure (VAC). These findings identify preliminary, associative relationships between wound microbiota and host factors which motivate future investigation into the directional relationships between wound care pain, wound closure technologies, and the wound microbiome.

ARL13B is a small regulatory GTPase that controls ciliary membrane composition in both motile cilia and non-motile primary cilia. In this study, we investigated the role of ARL13B in the efferent ductules, tubules of the male reproductive tract essential to male fertility in which primary and motile cilia co-exist. We used a genetically engineered mouse model to delete Arl13b in efferent ductule epithelial cells, resulting in compromised primary and motile cilia architecture and functions. This deletion led to disturbances in reabsorptive/secretory processes and triggered an inflammatory response. The observed male reproductive phenotype showed significant variability linked to partial infertility, highlighting the importance of ARL13B in maintaining a proper physiological balance in these small ducts. These results emphasize the dual role of both motile and primary cilia functions in regulating efferent duct homeostasis, offering deeper insights into how cilia related diseases affect the male reproductive system.

Interstitial lung diseases (ILDs) include a variety of inflammatory and fibrotic pulmonary conditions. This study employs high-resolution metabolomics (HRM) to explore plasma metabolites and pathways across ILD phenotypes, including non-fibrotic ILD, idiopathic pulmonary fibrosis (IPF), and non-IPF fibrotic ILD. The study used 80 plasma samples for HRM, and involved linear trend and group-wise analyses of metabolites altered in ILD phenotypes. We utilized limma one-way ANOVA and mummichog algorithms to identify differences in metabolites and pathways across ILD groups. Then, we focused on metabolites within critical pathways, indicated by high pathway overlap sizes and low p-values, for further analysis. Targeted HRM identified putrescine, hydroxyproline, prolyl-hydroxyproline, aspartate, and glutamate with significant linear increases in more fibrotic ILD phenotypes, suggesting their role in ILD fibrogenesis. Untargeted HRM highlighted pathway alterations in lysine, vitamin D3, tyrosine, and urea cycle metabolism, all associated with pulmonary fibrosis. In addition, methylparaben level had a significantly increasing linear trend and was higher in the IPF than fibrotic and non-ILD groups. This study highlights the importance of specific amino acids, metabolic pathways, and xenobiotics in the progression of pulmonary fibrosis.

Acute ischemic stroke (AIS) is a major global health concern due to its high mortality and disability rates. Hemorrhagic transformation, a common complication of AIS, leads to poor prognosis yet lacks effective treatments. Preclinical studies indicate that hyperbaric oxygen (HBO) treatment within 12 h of AIS onset alleviates ischemia/reperfusion injuries, including hemorrhagic transformation. However, clinical trials have yielded conflicting results, suggesting some underlying mechanisms remain unclear. In this study, we confirmed that HBO treatments beginning within 1 h post reperfusion significantly alleviated the haemorrhage and neurological deficits in hyperglycemic transient middle cerebral arterial occlusion (tMCAO) mice, partly due to the inhibition of the NLRP3 inflammasome-mediated pro-inflammatory response in microglia. Notably, reactive oxygen species (ROS) mediate the anti-inflammatory and protective effect of early HBO treatment, as edaravone and N-Acetyl-L-Cysteine (NAC), two commonly used antioxidants, reversed the suppressive effect of HBO treatment on NLRP3 inflammasome-mediated inflammation in microglia. Furthermore, NAC countered the protective effect of early HBO treatment in tMCAO mice with hyperglycemia. These findings support that early HBO treatment is a promising intervention for AIS, however, caution is warranted when combining antioxidants with HBO treatment. Further assessments are needed to clarify the role of antioxidants in HBO therapy for AIS.

Kidney transplantation is the most efficient renal replacement therapy. Current diagnostics for monitoring graft health are either invasive or lack precision. Metabolomics is an emerging discipline focused on the analysis of the small molecules involved in metabolism. Given the kidneys' central role in metabolic homeostasis and previous observations of altered metabolites correlating with restricted kidney graft function, metabolomics is highly promising for the discovery of novel biomarkers and the development of novel diagnostics. In this perspective, we summarize the known metabolic roles for the kidney, discuss biomarkers of graft health and immune status emerging from metabolomics research, and provide our perspective on how these and future findings can be integrated in clinical practice to enable precision diagnostics.

Delta (B.1.617.2) and Omicron (B.1.1.529) variants of SARS-CoV-2 represents unique clinical characteristics. However, their role in altering immunometabolic regulations during acute infection remains convoluted. Here, we evaluated the differential immunopathogenesis of Delta vs. Omicron variants in Golden Syrian hamsters (GSH). The Delta variant resulted in higher virus titers in throat swabs and the lungs and exhibited higher lung damage with immune cell infiltration than the Omicron variant. The gene expression levels of immune mediators and metabolic enzymes, Arg-1 and IDO1 in the Delta-infected lungs were significantly higher compared to Omicron. Further, Delta/Omicron infection perturbed carbohydrates, amino acids, nucleotides, and TCA cycle metabolites and was differentially regulated compared to uninfected lungs. Collectively, our data provide a novel insight into immunometabolic/pathogenic outcomes for Delta vs. Omicron infection in the GSH displaying concordance with COVID-19 patients associated with inflammation and tissue injury during acute infection that offered possible new targets to develop potential therapeutics.

Influenza virus infections are a major global health problem. Influenza can result in mild/moderate disease or progress to more severe disease, leading to high morbidity and mortality. Severity is thought to be primarily driven by immunopathology, but predicting which individuals are at a higher risk of being hospitalized warrants investigation into host genetics and the molecular signatures of the host response during influenza infections.

Here, we performed transcriptome and genotype analysis in healthy controls and patients exhibiting mild/moderate or severe influenza (ICU patients). A unique aspect of our study was the genotyping of all participants, which allowed us to assign ethnicities based on genetic variation and assess whether the variation was correlated with expression levels.

We identified 169 differentially expressed genes and related molecular pathways between patients in the ICU and those who were not in the ICU. The transcriptome/genotype association analysis identified 871 genes associated to a genetic variant and 39 genes distinct between African-Americans and Caucasians. We also investigated the effects of age and sex and found only a few discernible gene effects in our cohort.

Together, our results highlight select risk factors that may contribute to an increased risk of ICU admission for influenza-infected patients. This should help to develop better diagnostic tools based on molecular signatures, in addition to a better understanding of the biological processes in the host response to influenza.

Monocytes and macrophages play an indispensable role in maintaining intestinal homeostasis and modulating mucosal immune responses in inflammatory bowel disease (IBD). Although numerous studies have described macrophage properties in IBD, the underlying mechanisms whereby the monocyte-macrophage lineage modulates intestinal homeostasis during gut inflammation remain elusive.

In this review, we decipher the cellular and molecular mechanisms governing the generation of intestinal mucosal macrophages and fill the knowledge gap in understanding the origin, maturation, classification, and functions of mucosal macrophages in intestinal niches, particularly the phagocytosis and bactericidal effects involved in the elimination of cell debris and pathogens. We delineate macrophage-mediated immunoregulation in the context of producing pro-inflammatory and anti-inflammatory cytokines, chemokines, toxic mediators, and macrophage extracellular traps (METs), and participating in the modulation of epithelial cell proliferation, angiogenesis, and fibrosis in the intestine and its accessory tissues. Moreover, we emphasize that the maturation of intestinal macrophages is arrested at immature stage during IBD, and the deficiency of MCPIP1 involves in the process via ATF3-AP1S2 signature. In addition, we confirmed the origin potential of IL-1B+ macrophages and defined C1QB+ macrophages as mature macrophages. The interaction crosstalk between the intestine and the mesentery has been described in this review, and the expression of mesentery-derived SAA2 is upregulated during IBD, which contributes to immunoregulation of macrophage. Moreover, we also highlight IBD-related susceptibility genes (e.g., RUNX3, IL21R, GTF2I, and LILRB3) associated with the maturation and functions of macrophage, which provide promising therapeutic opportunities for treating human IBD.

In summary, this review provides a comprehensive, comprehensive, in-depth and novel description of the characteristics and functions of macrophages in IBD, and highlights the important role of macrophages in the molecular and cellular process during IBD.

Venous leg ulcers (VLUs) pose a growing healthcare challenge due to aging, obesity, and sedentary lifestyles. Despite various treatments available, addressing the complex nature of VLUs remains difficult. In this context, this study investigates repurposing boronated drugs to inhibit arginase 1 activity for VLU treatment. The molecular docking study conducted by Schrodinger GLIDE targeted the binuclear manganese cluster of arginase 1 enzyme (2PHO). Further, the ligand-protein complex was subjected to molecular dynamic studies at 500 ns in Gromacs-2019.4. Trajectory analysis was performed using the GROMACS simulation package of protein RMSD, RMSF, RG, SASA, and H-Bond. The docking study revealed intriguing results where the tavaborole showed a better docking score (-3.957 Kcal/mol) compared to the substrate L-arginine (-3.379 Kcal/mol) and standard L-norvaline (-3.141 Kcal/mol). Tavaborole interaction with aspartic acid ultimately suggests that the drug molecule binds to the catalytic site of arginase 1, potentially influencing the enzyme's function. The dynamics study revealed the compounds' stability and compactness of the protein throughout the simulation. The RMSD, RMSF, SASA, RG, inter and intra H-bond, PCA, FEL, and MMBSA studies affirmed the ligand-protein and protein complex flexibility, compactness, binding energy, van der waals energy, and solvation dynamics. These results revealed the stability and the interaction of the ligand with the catalytic site of arginase 1 enzyme, triggering the study towards the VLU treatment.

Immune response is pivotal in the secondary injury of spinal cord injury (SCI). Polarization of macrophages (MΦ) influences the immune response in the secondary injury, which is regulated by several immune-related proteins. M2Φ plays the immunomodulatory role in the central nervous system. This study used bioinformatic analysis and machine algorithms to screen hub immune-related proteins after SCI and experimentally investigate the role of the target protein in the M2Φ polarization and immunomodulation in rats and in vitro after SCI. We downloaded GSE151371 and GSE45006, hub immune-related genes were screened using machine learning algorithms, and the expression of S100A9 was verified by datasets. Allen's weight-drop injury SCI model in Sprague-Dawley rat and bone marrow-derived rat MΦ with myelin debris model were used to study the effects of S100A9 on M2Φ polarization and immunomodulation at the lesion site and in vitro. Bioinformatic analysis showed that S100A9 acts as a hub immune-related gene in the SCI patients and rats. S100A9 increased at the lesion site in SCI rats, and its inhibition reduced CD206 and ARG-1 expression. Exogenous S100A9 promoted CD206 and ARG-1 expression in MΦ. S100A9 also increased the expression of PD-L1 and decreased MHC II at the lesion site in SCI rats and MΦ with myelin debris, and enhanced mitochondrial activity in rat MΦ with myelin debris. In conclusion, S100A9 is an indispensable factor in the immune process in secondary injury following SCI.

Monocyte-derived macrophages recruited to injured tissues induce a maladaptive fibrotic response characterized by excessive production of collagen by local fibroblasts. Macrophages initiate this programming via paracrine factors, but it is unknown whether reciprocal responses from fibroblasts enhance profibrotic polarization of macrophages. We identify macrophage-fibroblast crosstalk necessary for injury-associated fibrosis, in which macrophages induced interleukin 6 ( IL-6 ) expression in fibroblasts via purinergic receptor P2rx4 signaling, and IL-6, in turn, induced arginase 1 ( Arg1 ) expression in macrophages. Arg1 contributed to fibrotic responses by metabolizing arginine to ornithine, which fibroblasts used as a substrate to synthesize proline, a uniquely abundant constituent of collagen. Imaging of idiopathic pulmonary fibrosis (IPF) lung samples confirmed expression of ARG1 in myeloid cells, and arginase inhibition suppressed collagen expression in cultured precision-cut IPF lung slices. Taken together, we define a circuit between macrophages and fibroblasts that facilitates cross-feeding metabolism necessary for injury-associated fibrosis.

Gadolinium is a component of the MRI contrast agent Dotarem. Although Dotarem is the least toxic among MRI contrasts used, gadolinium present in Dotarem accumulates for many years in various organs and tissues exerting toxic effects. We showed previously that gadolinium remains in macrophages for at least 7 days after exposure to Dotarem. However, very little is known about the effect of gadolinium retention on the immune cells such as macrophages. We studied the effect of 1-day and 7-day retention of gadolinium on various functions and molecular pathways of macrophages. Gadolinium retention for 7 days decreased macrophage adhesion and motility and dysregulated the expression of adhesion and fibrotic pathway-related proteins such as Notch1 and its ligand Jagged1, adhesion/migration-related proteins PAK1 and Shp1, immune response-related transcription factors Smad3 and TCF19, and chemokines CXCL10 and CXCL13, and dysregulated the mRNA expression of fibrosis-related genes involved in extracellular matrix (ECM) synthesis, such as Col6a1, Fibronectin, MMP9, and MMP12. It also completely (below a level of detection) shut down the transcription of anti-inflammatory M2 macrophage polarization marker the Arg-1. Such changes, if they occur in MRI patients, can be potentially detrimental to the patient's immune system and immune response-related processes.

Post-traumatic stress disorder (PTSD) is a debilitating mental health disease related to traumatic experience, and its treatment outcomes are unsatisfactory. Accumulating research has indicated that cannabidiol (CBD) exhibits anti-PTSD effects, however, the underlying mechanism of CBD remains inadequately investigated. Although many studies pertaining to PTSD have primarily focused on aberrations in neuronal functioning, the present study aimed to elucidate the involvement and functionality of microglia/macrophages in PTSD while also investigated the modulatory effects of CBD on neuroinflammation associated with this condition. We constructed a modified single-prolonged stress (SPS) mice PTSD model and verified the PTSD-related behaviors by various behavioral tests (contextual freezing test, elevated plus maze test, tail suspension test and novel object recognition test). We observed a significant upregulation of Iba-1 and alteration of microglial/macrophage morphology within the prefrontal cortex and hippocampus, but not the amygdala, two weeks after the PTSD-related stress, suggesting a persistent neuroinflammatory phenotype in the PTSD-modeled group. CBD (10 mg/kg, i.p.) inhibited all PTSD-related behaviors and reversed the alterations in both microglial/macrophage quantity and morphology when administered prior to behavioral assessments. We further found increased pro-inflammatory factors, decreased PSD95 expression, and impaired synaptic density in the hippocampus of the modeled group, all of which were also restored by CBD treatment. CBD dramatically increased the level of anandamide, one of the endocannabinoids, and cannabinoid type 2 receptors (CB2Rs) transcripts in the hippocampus compared with PTSD-modeled group. Importantly, we discovered the expression of CB2Rs mRNA in Arg-1-positive cells in vivo and found that the behavioral effects of CBD were diminished by CB2Rs antagonist AM630 (1 mg/kg, i.p.) and both the behavioral and molecular effects of CBD were abolished in CB2Rs knockout mice. These findings suggest that CBD would alleviate PTSD-like behaviors in mice by suppressing PTSD-related neuroinflammation and upregulation and activation of CB2Rs may serve as one of the underlying mechanisms for this therapeutic effect. The present study offers innovative experimental evidence supporting the utilization of CBD in PTSD treatment from the perspective of its regulation of neuroinflammation, and paves the way for leveraging the endocannabinoid system to regulate neuroinflammation as a potential therapeutic approach for psychiatric disorders.

The sialic acid-binding immunoglobulin-like lectins (Siglecs) are a family of receptors expressed widely on cells of the hematopoietic system. Siglecs recognize terminal sialic acid residues on glycans and often initiate intracellular signaling upon ligation. Cells can express several Siglec family members concurrently with each showing differential specificities for sialic acid linkages to the underlying glycan as well as varied hydroxyl substitutions, allowing these receptors to fine tune downstream responses. Macrophages are among the many immune cells that express Siglec family members. Macrophages exhibit wide diversity in their phenotypes and functions, and this diversity is often mediated by signals from the local environment, including those from glycans. In this review, we detail the known expression of Siglecs in macrophages while focusing on their functional importance and potential clinical relevance.

The tumor microenvironment comprises both tumor and non-tumor stromal cells, including tumor-associated macrophages (TAMs), endothelial cells, and carcinoma-associated fibroblasts. TAMs, major components of non-tumor stromal cells, play a crucial role in creating an immunosuppressive environment by releasing cytokines, chemokines, growth factors, and immune checkpoint proteins that inhibit T cell activity. During tumors develop, cancer cells release various mediators, including chemokines and metabolites, that recruit monocytes to infiltrate tumor tissues and subsequently induce an M2-like phenotype and tumor-promoting properties. Metabolites are often overlooked as metabolic waste or detoxification products but may contribute to TAM polarization. Furthermore, macrophages display a high degree of plasticity among immune cells in the tumor microenvironment, enabling them to either inhibit or facilitate cancer progression. Therefore, TAM-targeting has emerged as a promising strategy in tumor immunotherapy. This review provides an overview of multiple representative metabolites involved in TAM phenotypes, focusing on their role in pro-tumoral polarization of M2.

An extreme thermophilic bacterium, Thermus thermophilus produces more than 20 unusual polyamines, but their biosynthetic pathways, including homospermidine, are not yet fully understood. Two types of homospermidine synthases have been identified in plants and bacteria, which use spermidine and putrescine or two molecules of putrescine as substrates. However, homospermidine synthases with such substrate specificity have not been identified in T. thermophilus. Here we identified a novel agmatine homocoupling enzyme that is involved in homospermidine biosynthesis in T. thermophilus. The reaction mechanism is different from that of a previously described homospermidine synthase, and involves conjugation of two molecules of agmatine, which produces a diamidino derivative of homospermidine (caldomycin) as an immediate precursor of homospermidine. We conclude that there is a homospermidine biosynthetic pathway from agmatine via caldomycin synthase followed by ureohydrolase in T. thermophilus. Furthermore, it is shown that caldomycin is a novel compound existing in nature.