Inflammatory bowel disease (IBD) is closely associated with immune dysfunction, where nutrient-mediated metabolic flux dictates immune cell fate and function. Thiamine is a central water-soluble vitamin involved in cellular energy metabolism, and its deficiency has been reported in IBD patients. However, whether thiamine deficiency is a cause or consequence of IBD pathogenesis remains unclear. The current study aimed to reveal the immunometabolic regulation of macrophages and underlying mechanism of thiamine deficiency in colitis development.

Thiamine deficiency was induced in C57BL/6 mice and bone marrow-derived macrophages (BMDMs), by administering a thiamine-deficient diet/medium together with pyrithiamine hydrobromide. The frequency of macrophage phenotypes and their intracellular metabolism were detected using flow cytometry and non-targeted metabolomics, respectively.

Thiamine deficiency aggravated ulcerative colitis in mice and promoted the infiltration of proinflammatory M1 macrophages in colonic lamina propria. Our mechanistic study revealed that thiamine deficiency impaired pyruvate dehydrogenase (PDH) activity, thereby reprogramming cellular glucose metabolism to enhance glycolysis and lactic acid accumulation in M1 macrophages. Using a well-established PDH inhibitor (CPI-613) and lactic acid dehydrogenase inhibitor (galloflavin), we further demonstrated that PDH inhibition mimics, while lactate dehydrogenase inhibition partially rescues, thiamine deficiency-induced proinflammatory macrophage infiltration and experimental colitis in mice.

Our study provides evidence linking thiamine deficiency with proinflammatory macrophage activation and colitis aggravation, suggesting that monitoring thiamine status and adjusting thiamine intake is necessary to protect against colitis.

Macrophages can maintain gut immune homeostasis by driving clearance of infection, but also can prevent chronic inflammation and induce tissue repair. Reduced nicotinamide adenine dinucleotide (NAD+) levels in macrophages have been reported to be associated with the onset of severe colitis. Given that dysregulation of gut macrophages plays a significant role in inflammatory bowel disease (IBD), they represent a potential target for novel therapies. Here we show an IBD therapeutic candidate LMT503, a substrate that modulates NADH quinone oxidoreductase (NQO1), which induces anti-inflammatory macrophage polarization by NAD+ enhancement. To determine the anti-inflammatory effect of LMT503, a dextran sulfate sodium (DSS)-induced colitis mouse model was used in this study. Treatment of bone marrow-derived macrophages (BMDMs) with LMT503 increased IL-10 and Arg1 levels but decreased levels of TNF-α, iNOS, and IL-6. LMT503 also increased levels of SIRT1, SIRT3, and SIRT6, suggesting that macrophages were driven to an anti-inflammatory character. In a murine DSS-induced colitis model, oral treatment with LMT503 ameliorated colonic inflammation and decreased infiltrating monocytes and neutrophils. Although NAD+ enhancement did not alter CX3CR1intCD206- or CX3CR1hiCD206+ colon macrophage population, it decreased levels of TNF-α and iNOS and increased IL-10 level, with colonic macrophages showing an anti-inflammatory character shift. Depletion of CX3CR1 expressing gut resident macrophages abrogated the immune regulatory effect of LMT503 in the colon. These data suggest that LMT503 is a therapeutic candidate that can target macrophages to drive polarization with an immunosuppressive character and ameliorate IBD.

The analysis of murine immune cell types is a critical component of immunological research, necessitating precise and reproducible methodologies. Here, we present a comprehensive protocol and pipeline designed to streamline the process from murine gastric organoid transplant sample preparation to figure generation. This pipeline includes a detailed staining panel tailored for murine immune cells, ensuring accurate and comprehensive identification of various cell types. Additionally, it integrates an R-based analysis script (MARMOT Pipeline), encompassing data processing and visualisation. A key feature of this pipeline is its ability to produce publication-quality figures with minimal direct R coding, thus making advanced data analysis accessible to researchers with limited programming experience. Additionally, figures can be customised using a provided Shiny application. This approach both enhances the efficiency of data analysis and enables the reproducibility required for high-quality scientific research.

Chronic inflammation of the intestine is a significant risk factor in the development of colorectal cancer. The emergence of colitis and colorectal cancer is a complex, multifactorial process involving chronic inflammation, immune regulation, and tumor microenvironment remodeling. Macrophages represent one of the most prevalent cells in the colorectal cancer microenvironment and play a pivotal role in maintaining intestinal health and the development of colitis-associated colon cancer (CAC). Macrophages are activated mainly in two ways and resulted in three phenotypes: classically activated macrophages (M1), alternatively activated macrophages (M2). The most characteristic of these cells are the pro-inflammatory M1 and anti-inflammatory M2 types, which play different roles at different stages of the disease. During chronic inflammation progresses to cancer, the proportion of M2 macrophages gradually increases. The M2 macrophages secrete cytokines such as IL-10 and TGF-β, which promote angiogenesis and matrix remodeling, and create the favorable conditions for cancer cell proliferation, infiltration, and migration. Therefore, macrophage polarization has a dual effect on the progression of colitis to CAC. The combination of immunotherapy with reprogrammed macrophages and anti-tumor drugs may provide an effective means for enhancing the therapeutic effect. It may represent a promising avenue for developing novel treatments for CAC. In this review, we focus on the process of intestinal macrophage polarization in CAC and the role of intestinal macrophage polarization in the progression of colitis to colon cancer, and review the immunotherapy targets and relevant drugs targeting macrophages in CAC.

Ulcerative colitis (UC) involves chronic, complex pathology of the intestinal mucosa. Current treatments are limited in efficacy and associated with adverse effects, highlighting the urgent need for improved therapeutic options. Lentinan (LNT), a polysaccharide drug commonly used in clinical immune modulation therapies, shows potential for UC treatment, though its specific targets and mechanisms remain unclear. In this study, LNT administration effectively mitigated DSS-induced colitis in mice, enhanced mucosal barrier function and antimicrobial defense. Specifically, LNT modulated the balance between tissue-resident and infiltrating macrophages, thereby improving pathogen clearance and enhancing the immunological barrier. Notably, we identified a novel effect of LNT in regulating the macrophage Dectin-1-ILC3 axis to increase IL-22 secretion. This led to the modulation of epithelial O-glycan fucosylation, antimicrobial peptides, and epithelial stem cells, thereby strengthening antimicrobial defenses and the physicochemical barrier. Neutralization with anti-IL-22 antibodies diminished the therapeutic effect of LNT in UC, underscoring the critical role of IL-22 in LNT-mediated treatment. Overall, this study highlights the potential of LNT as a novel therapeutic agent for UC, offering new insights into its molecular mechanisms and clinical application.

Inflammatory bowel disease (IBD) is a multifaceted disease characterised by compromised integrity of the epithelial barrier, the gut microbiome, and mucosal inflammation. While leukocyte recruitment and infiltration into intestinal tissue are well-studied and targeted in clinical practice, the role of galectins in modulating mucosal immunity remains underexplored. Galectins, a family of lectin-binding proteins, mediate critical interactions between immune cells and the intestinal epithelium. This study investigated the effect of endogenous Galectin-9 (Gal-9), as well as the combined effects with Galectin-3 (Gal-3), in modulating disease progression in murine models of colitis, using global knockout (KO) models for Gal-3, Gal-9, and Gal-3/Gal-9. Global deficiency in both galectins demonstrated improved disease parameters in Dextran sodium sulfate (DSS)-driven colitis. In contrast, in a model of adoptive T cell driven colitis, the addition of recombinant Gal-9 (rGal-9) was associated with reduced intestinal inflammation and an improvement in disease parameters. Further in vitro studies revealed no change in bone marrow-derived macrophage cytokine production in the absence of endogenous Gal-9, whereas the addition of rGal-9 to human macrophages stimulated pro-inflammatory cytokine production. Collectively, these findings demonstrate that Gal-9 plays distinct, context-dependent effects in intestinal inflammation, with both pro-inflammatory and anti-inflammatory effects. The contrasting functions of endogenous and exogenous Gal-9 underscore its complex involvement in IBD pathogenesis and highlight the need to differentiate its physiological function from therapeutic applications.

Infection by Mycobacterium tuberculosis (Mtb) continues to cause more than 1 million deaths annually, due to pathogen persistence in lung macrophages and dendritic cells derived from blood monocytes. While accumulation of monocyte-derived cells in the Mtb-infected lung partially depends on the chemokine receptor CCR2, the other chemoattractant receptors regulating trafficking remain undefined. We used mice expressing knock-in/knockout reporter alleles of Ccr2 and Cx3cr1 to interrogate their expression and function in monocyte-derived populations of the lungs and draining mediastinal lymph nodes during Mtb infection. CCR2 and CX3CR1 expression varied across monocyte-derived subsets stratified by cell surface Ly6C expression in both organs. We found that expression of CCR2 predicted dependence of monocyte-derived cells on the receptor for lung and lymph node accumulation. CCR2-deficient mice were also observed to have worsened lung and lymph node Mtb burden. While CX3CR1 deficiency, alone or in combination with CCR2 deficiency, did not affect cell frequencies or lung Mtb control, its absence was associated with altered positioning of monocyte-derived dendritic cells in mediastinal lymph nodes. We found that combined loss of Ccr2 and Cx3cr1 also worsened Mtb control in the mediastinal lymph node, suggesting a rationale for the persistent expression of CX3CR1 among monocyte-derived cells in pulmonary tuberculosis.

Mycobacterium tuberculosis is the respiratory pathogen responsible for the deadliest infectious disease worldwide. Susceptible humans exhibit ineffective immune responses, in which infected phagocytes are not able to eliminate the pathogen. Since recruited monocyte-derived cells serve as reservoirs for persistent infection, understanding how these phagocytes accumulate in the lung and why they are unable to eliminate Mtb can inform development of therapies that can synergize with antimicrobials to achieve faster and more durable Mtb elimination. Monocyte-derived cells express the chemokine receptors CCR2 and CX3CR1, but the role of the latter in Mtb infection remains poorly defined. The significance of our study is in elucidating the roles of these receptors in the trafficking of monocyte-derived cells in the infected lung and mediastinal lymph node. These data shed light on the host response in tuberculosis and in other pulmonary infections.

Perianal fistulizing Crohn's disease (PFCD) is a challenging and debilitating phenotype of Crohn's disease that can negatively affect quality of life. Studies have begun to uncover the physiologic mechanisms involved in wound repair as it relates to PFCD and how aberrations in these mechanisms may contribute to fistula persistence.

To review the physiologic and pathophysiologic mechanisms of wound repair in PFCD and how specific therapeutic strategies may impact their outcomes.

We reviewed the latest published literature on wound repair as it relates to PFCD.

Wound repair can be categorised into three overlapping biological phases: localised inflammation, cell recruitment/proliferation and tissue remodelling. Each is tightly regulated since insufficient or excessive activation can result in, respectively, chronic wounds and fibrotic tissue, both of which can impair organ function. In PFCD, the outcomes of wound repair include restitution (complete healing), epithelialisation and chronic wounds. Treatment of PFCD should take into consideration the distinct phases of wound repair. Therefore, the ability to differentiate between each phase of wound repair and their outcomes may help physicians deliver the most effective treatment strategy at the most appropriate time.

This review provides a comprehensive overview of the phases of wound repair and specific treatment strategies for each to provide clinicians with a rational framework for managing PFCD.

The intestine hosts the largest immune system and peripheral nervous system in the human body. The gut‒brain axis orchestrates communication between the central and enteric nervous systems, playing a pivotal role in regulating overall body function and intestinal homeostasis. Here, using a human three-dimensional in vitro culture model, we investigated the effects of serotonin, a neuromodulator produced in the gut, on immune cell and intestinal tissue interactions. Serotonin attenuated the tumor necrosis factor-induced proinflammatory response, mostly by affecting the expression of chemokines. Serotonin affected the phenotype and distribution of tissue-migrating monocytes, without direct contact with the cells, by remodeling the intestinal tissue. Collectively, our results show that serotonin plays a crucial role in communication among gut-brain axis components and regulates monocyte migration and plasticity, thereby contributing to gut homeostasis and the progression of inflammation. In vivo studies focused on the role of neuromodulators in gut inflammation have shown controversial results, highlighting the importance of human experimental models. Moreover, our results emphasize the importance of human health research in human cell-based models and suggest that the serotonin signaling pathway is a new therapeutic target for inflammatory bowel disease.

Macrophages have great plasticity. Typically, there are two of activated macrophages: M1 macrophages and M2 macrophages. Of them, M1 macrophages play a major role in responses that are pro-inflammatory, while M2 macrophages play an important part in responses that are anti-inflammatory. Ulcerative colitis (UC) is a chronic, non-specific inflammatory disease of the intestine. The pathophysiology and course of UC are significantly influenced by the inflammatory response triggered by macrophage activation. M1 is a possible cause of increased inflammation in UC whereas M2 has a significant function in the healing of inflammation. The polarization imbalance of intestinal M1/M2 macrophages is closely linked to UC. Thus, by suppressing M1 polarization, encouraging M2 polarization, and reestablishing macrophage polarization balance, the treatment of UC based on macrophage polarization is beneficial for UC. Not only chemical drugs, but also traditional Chinese medicine compounds and herbal extracts have been shown to restore the balance of macrophage polarization, providing a new idea in the treatment of UC.

Macrophages are members of the human innate immune system, and the majority reside in the liver. In recent years, they have been recognized as essential players in the maintenance of liver and intestinal homeostasis as well as key guardians of their respective immune systems, and they are increasingly being recognized as such. Paradoxically, they are also likely involved in chronic pathologies of the gastrointestinal tract and potentially in the alteration of the gut-liver axis in alcohol use disorder (AUD) and alcohol-associated liver disease (ALD). To date, the causal relationship between macrophages, the pathogenesis of ALD, and the immune dysregulation of the gut remains unclear. In this review, we will discuss our current understanding of the heterogeneity of intestinal and hepatic macrophages, their ontogeny, the potential factors that regulate their origin, and the evidence of how they are associated with the manifestation of chronic inflammation. We will also illustrate how the micro-environment of the intestine shapes the phenotypes and functionality of the macrophage compartment in both the intestines and liver and how they change during chronic alcohol abuse. Finally, we highlight the obstacles to current research and the prospects for this field.

A number of drug treatments are known to alter the dialogue between the gut microbiota and the immune system components in the digestive mucosa. Alterations in intestinal homeostasis are now well known to affect peripheral immune responses and favor the occurrence of a number of pathologies such as allergies and cancers. Erythropoietin's known pleiotropic effects might explain the adverse events sometimes observed in anemic patients treated by erythropoiesis-stimulating agents (ESA). However, the impact of this therapeutic cytokine on the homeostasis of the intestinal tract has not previously been investigated in detail. By studying a mouse model of erythropoietin (EPO) supplementation for 28 days, we observed EPO-induced dysbiosis of the fecal microbiota characterized by a greater bacterial load, lower bacterial diversity and taxonomic changes. With regard to the mucosal immune system, an analysis of leukocyte populations in the small intestine and colon treatment revealed low proportions of ileal CD4 lymphocyte subpopulations (Treg, Tr17 and Th17 cells), IgA-secreting plasma cells, and a major macrophage subpopulation, involved in the control of lymphocyte responses. Our results provide for the first time a descriptive analysis of intestinal EPO's regulatory properties and raise questions about the involvement of EPO-induced alterations in the microbiota and the gut immune effectors in the control of intestinal and peripheral immune responses.

Immune cell populations in the intestinal muscularis propria during colitis are poorly resolved. Maintaining homeostasis in this niche is critical, highlighted by the poorer prognosis of inflammatory bowel disease associated with muscularis propria inflammation.

This study utilizes single-cell RNA sequencing to survey the immune cell populations within the muscularis propria of normal colon and dextran sodium sulfate-induced colitis. Findings are validated by immunohistochemistry, flow cytometry and cell-lineage tracing in vivo, and in vitro assays with muscularis macrophages (MMφ).

In naïve conditions, transcriptional duality is observed in MMφs with 2 major subpopulations: conventional resident Cx3cr1+ MMφs and Lyve1+ MMφs. The Lyve1+ population is phagocytic and expresses several known MMφ markers in mouse and human, confirming their identity as a bona fide MMφ subset. Single-cell transcriptomics indicate that resident MMφs are retained during colitis and exhibit plasticity toward an inflammatory profile. Lyve1+ MMφs, which express anti-inflammatory marker CD163, are absent during colitis, as confirmed by flow cytometry. In contrast, lineage tracing finds that resident Cx3cr1+ MMφs remain during colitis and are not completely replaced by the inflammatory infiltrating monocytes. In vitro studies provide biological evidence of the plasticity of resident Cx3cr1+ MMφs in response to lipopolysaccharide (LPS), mirroring transcriptional observations in vivo of their inflammatory plasticity. Potential markers for colitic MMφs, validated in animal models and in individuals with ulcerative colitis, are identified.

Our findings contribute to the understanding of the immune system in the muscularis propria niche during colitis by resolving the heterogeneity and origins of colitic MMφs.

Aging is a complex biological process that involves the gradual decline of cellular, tissue, and organ functions. In kidney, aging manifests as tubular atrophy, glomerulosclerosis, and progressive renal function decline. The critical role of senescence-associated macrophage in diseases, particularly kidney diseases, is increasingly recognized. During this process, macrophages exhibit a range of pro-damage response to senescent tissues and cells, while the aging of macrophages themselves also significantly influences disease progression, creating a bidirectional regulatory role between aging and macrophages. To explore this bidirectional mechanism, this review will elucidate the origin, characteristic, phenotype, and function of macrophages in response to the senescence-associated secretory phenotype (SASP), extracellular vesicles from senescent cells, and the senescence cell-engulfment suppression (SCES), particularly in the context of kidney disease. Additionally, it will discuss the characteristics of senescent macrophage, such as common markers, and changes in autophagy, metabolism, gene regulation, phagocytosis, antigen presentation, and exosome secretion, along with their physiological and pathological impacts on renal tissue cells. Furthermore, exploring therapies and drugs that modulate the function of senescent macrophages or eliminate senescent cells may help slow the progression of kidney aging and damage.

Lipid Nanoparticles (LNPs) recently emerged as an invaluable RNA delivery platform. With many LNP-based therapeutics in the pre-clinical and clinical pipelines, there is extensive research dedicated to improving LNPs. These efforts focus mainly on the tolerability and transfectability of new ionizable lipids and RNAs, or modulating LNPs biodistribution with active targeting strategies. However, most formulations follow the well-established lipid proportions used in clinically approved products. Nevertheless, investigating the effects of LNPs composition on their biodistribution can expand the toolbox for particle design, leading to improved delivery strategies. Herein, a new LNPs (30-n-LNPs) formulation with increasing amounts of phospholipids is investigated as a possible mRNA delivery system for treating Inflammatory Bowel Diseases. Compared to LNPs with benchmark composition (b-LNPs), n-LNPs containing 30% distearoylphosphatidylcholine (DSPC) are well tolerated following intravenous administration and display natural targeting toward the inflamed colon in dextran sodium sulfate (DSS)-colitis bearing mice, while de-targeting clearing organs such as the liver and spleen. Using interleukin-10-encoding mRNA as therapeutic cargo, n-LNPs demonstrated a reduction of pathological burden in colitis-bearing mice. n-LNPs represent a starting point to further investigate the influence of LNPs composition on systemic biodistribution, ultimately opening new therapeutic modalities in different pathologies.

Organs of the gastrointestinal tract contain tissue-resident immune cells that function during tissue development, homeostasis, and disease. However, most published human organoid model systems lack resident immune cells, thus limiting their potential as disease avatars. For example, human intestinal organoids (HIOs) derived from pluripotent stem cells contain epithelial and various mesenchymal cell types but lack immune cells. In this study, we aimed to develop an HIO model with functional tissue-resident macrophages.

HIOs and macrophages were generated separately through the directed differentiation of human pluripotent stem cells and combined in vitro. Following 2 weeks of coculture, the organoids were used for transcriptional profiling, functional analysis of macrophages, or transplanted into immunocompromised mice and matured in vivo for an additional 10-12 weeks.

Macrophages were incorporated into developing HIOs and persisted for 2 weeks in vitro HIOs and for at least 12 weeks in HIOs in vivo. These cocultured macrophages had a transcriptional signature that resembled those in the human fetal intestine, indicating that they were acquiring the features of tissue-resident macrophages. HIO macrophages could phagocytose bacteria and produced inflammatory cytokines in response to proinflammatory signals, such as lipopolysaccharide, which could be reversed with interleukin-10.

We generated an HIO system containing functional tissue-resident macrophages for an extended period. This new organoid system can be used to investigate the molecular mechanisms involved in inflammatory bowel disease.

Acute exacerbations of idiopathic pulmonary fibrosis (AE-IPF) are the leading cause of mortality among patients with IPF. There is still a lack of effective treatments for AE-IPF, resulting in a hospitalization mortality rate as high as 70%-80%. To reveal the complicated mechanism of AE-IPF, more attention has been paid to its disturbed immune environment, as patients with IPF exhibit deficiencies in pathogen defense due to local immune dysregulation. During the development of AE-IPF, the classical stimulatory signals in adaptive immunity are inhibited, while the nonclassical immune reactions (Th17) are activated, attracting numerous neutrophils and monocytes to lung tissues. However, there is limited information about the specific changes in the immune response of AE-IPF. We summarized the immune mechanisms of AE-IPF in this review.

The past 15 years have witnessed a leap in understanding the life cycle, gene expression profiles, origins and functions of mouse macrophages in many tissues, including macrophages of the artery wall and heart that have critical roles in cardiovascular health. Here, we review the phenotypical and functional diversity of macrophage populations in multiple organs and discuss the roles that proliferation, survival, and recruitment and replenishment from monocytes have in maintaining macrophages in homeostasis and inflammatory states such as atherosclerosis and myocardial infarction. We also introduce emerging data that better characterize the life cycle and phenotypic profiles of human macrophages. We discuss the similarities and differences between murine and human macrophages, raising the possibility that tissue-resident macrophages in humans may rely more on bone marrow-derived monocytes than in mouse.

Dietary micronutrients, particularly vitamin B12 (VB12), profoundly influence the physiological maintenance and function of intestinal cells. However, it is still unclear whether VB12 modulates the transcriptional and metabolic programming of ileal macrophages (iMacs), thereby contributing to intestinal homeostasis. Using multiomic approaches, we demonstrated that VB12 primarily supports the cell cycle activity and mitochondrial metabolism of iMacs, resulting in increased cell frequency compared to VB12 deficiency. VB12 also retained the ability to promote maintenance and metabolic regulation of iMacs during intestinal infection with Salmonella Typhimurium (STm). On the contrary, depletion of iMacs by inhibiting CSF1R signaling significantly increased host susceptibility to STm and prevented VB12-mediated pathogen reduction. These results thus suggest that regulation of VB12-dependent iMacs critically controls STm expansion, which may be of new relevance to advance our understanding of this vitamin and to strategically formulate sustainable therapeutic nutritional regimens that improve human gut health.

Ezrin, an actin-binding protein, orchestrates the organization of the cortical cytoskeleton and plasma membrane during cell migration, adhesion, and proliferation. Its role in monocytes/macrophages (MΦs) is less understood. Here, we used a monocyte/MΦ-specific ezrin knock-out mouse model to investigate the contribution of ezrin to monocyte recruitment and adaptation to the lung extracellular matrix (ECM) in response to lipopolysaccharide (LPS). Our study revealed that LPS induces ezrin expression in monocytes/MΦs and is essential for monocytes to adhere to lung ECM, proliferate, and differentiate into tissue-resident interstitial MΦs. Mechanistically, the loss of ezrin in monocytes disrupts activation of focal adhesion kinase and AKT serine-threonine protein kinase signaling, essential for lung-recruited monocytes and monocyte-derived MΦs to adhere to the ECM, proliferate, and survive. In summary, our data show that ezrin plays a role beyond structural cellular support, influencing diverse monocytes/MΦ processes and signaling pathways during inflammation, facilitating their differentiation into tissue-resident macrophages.

The intestinal immune system is the largest immune organ in the human body. Excessive immune response to intestinal cavity induced by harmful stimuli including pathogens, foreign substances and food antigens is an important cause of inflammatory diseases such as celiac disease and inflammatory bowel disease (IBD). Although great progress has been made in the treatment of IBD by some immune-related biotherapeutic products, yet a considerable proportion of IBD patients remain unresponsive or immune tolerant to immunotherapeutic strategy. Therefore, it is necessary to further understand the mechanism of immune cell populations involved in enteritis, including dendritic cells, macrophages and natural lymphocytes, in the steady-state immune tolerance of IBD, in order to find effective IBD therapy. In this review, we discussed the important role of innate and adaptive immunity in the development of IBD. And the relationship between intestinal immune system disorders and microflora crosstalk were also presented. We also focus on the new findings in the field of T cell immunity, which might identify novel cytokines, chemokines or anti-cytokine antibodies as new approaches for the treatment of IBD.

Dendritic cells (DCs) are present in almost all tissues, where they act as sentinels involved in innate recognition and the initiation of adaptive immune responses. The DC family consists of several cell lineages that are heterogenous in their development, phenotype, and function. Within these DC lineages, further subdivisions exist, resulting in smaller, less characterized subpopulations, each with its unique immunomodulatory capabilities. Given the interest in utilizing DC for experimental studies and for vaccination purposes, it becomes increasingly crucial to thoroughly classify and characterize these diverse DC subpopulations. This understanding is vital for comprehending their relative contribution to the initiation, regulation, and propagation of immune responses. To facilitate such investigation, we here provide an easy and ready-to-use multicolor flow cytometry staining panel for the analysis of conventional DC, plasmacytoid DC, and monocyte-derived DC populations isolated from mouse spleens. This adaptable panel can be easily customized for the analysis of other tissue-specific DC populations, providing a valuable tool for DC research.

Mesenchymal stem cells (MSCs) have shown potential in treating immune-mediated diseases due to their immunomodulatory properties, which can be enhanced by priming with inflammatory cytokines like interferon-gamma (IFN-γ). This study evaluates the therapeutic effects of IFN-γ-primed canine adipose tissue-derived MSCs (AMSCs) in a mouse model of inflammatory bowel disease (IBD). Canine AMSCs were primed with 50 ng/mL recombinant canine IFN-γ for 48 h, and the effects were compared to those seen in naïve (unprimed) AMSCs. IBD was induced in mice using dextran sodium sulfate (DSS), and AMSCs were injected intraperitoneally on days 1 and 3. The mice treated with IFN-γ-primed AMSCs showed improved clinical outcomes, including a reduced disease activity index (DAI), less body weight loss, and longer colon length compared to the mice treated with naïve AMSCs. A histological analysis revealed less damage to the intestinal structures and reduced inflammatory cell infiltration. IFN-γ priming led to a shift in the immune cell balance in the gut, decreasing pro-inflammatory macrophages (Ly6Chi) and increasing anti-inflammatory macrophages (Ly6Clo/MHC-IIhi). This was associated with the reduced expression of inflammatory cytokine genes (Il-1β, Il-6, and Il-18) and increased expression of the intestinal stem cell marker Lgr5. These findings suggest that IFN-γ-primed AMSCs offer enhanced therapeutic potential for treating CE in veterinary medicine.

In this study, we aimed to explore the role of Tarm1 in juvenile mice with dextran sulfate sodium (DSS)-induced colitis and elucidate the mechanisms that affect intestinal barrier function.

A DSS-induced pediatric inflammatory bowel disease mouse model was established using 4-week-old juvenile mice. Disease activity index and histopathological damage scores were determined using hematoxylin and eosin (H&E) staining. Tarm1, F4/80, CD68, and CD86 levels were detected using qPCR, western blotting, and immunofluorescence. Trans epithelial electric resistance (TEER) was detected using the transwell assay.

Results revealed that juvenile colitis mice fed 4% DSS drinking water had increased Tarm1 expression in the colon tissue, increased macrophage M1 polarization, higher expression of pro-inflammatory cytokines, and an impaired intestinal mucosal barrier, compared with the control group. Tarm1-knockdown RAW264.7 cells inhibited lipopolysaccharide (LPS)-induced M1 polarization and attenuated barrier damage in co-cultured intestinal epithelial cells.

Tarm1 expression was increased in colonic tissues of juvenile mice with colitis, and LPS-induced M1 polarization and intestinal barrier damage were attenuated in Tarm1-knockdown RAW264.7 cells. This suggests that attenuation of Tarm1 expression is a potential target for pediatric inflammatory bowel disease therapy.

The IL-23 signaling pathway in both innate and adaptive immune cells is vital for orchestrating type 17 immunity, which is marked by the secretion of signature cytokines such as IL-17, IL-22, and GM-CSF. These proinflammatory mediators play indispensable roles in maintaining intestinal immune equilibrium and mucosal host defense; however, their involvement has also been implicated in the pathogenesis of chronic inflammatory disorders, such as inflammatory bowel diseases and autoimmunity. However, the implications of type 17 immunity across diverse inflammation models are complex. This review provides a comprehensive overview of the multifaceted roles of these cytokines in maintaining gut homeostasis and in perturbing gut barrier integrity, leading to acute and chronic inflammation in various models of gut infection and colitis. Additionally, this review focuses on type 17 immunity interconnecting multiple organs in autoimmune conditions, with a particular emphasis on the pathogenesis of autoimmune arthritis and neuroinflammation driven by T cells primed within the gut microenvironment.

The gut-brain axis plays an important role in mental health. The intestinal epithelial surface is colonized by billions of commensal and transitory bacteria, known as the Gut Microbiota (GM). However, potential pathogens continuously stimulate intestinal immunity when they find the place. The last two decades have witnessed several studies revealing intestinal bacteria as a key factor in the health-disease balance of the gut, as well as disease-emergent in other parts of the body. Various neurological processes, such as cognition, learning, and memory, could be affected by dysbiosis in GM. Additionally, the aging process and longevity are related to systemic inflammation caused by dysbiosis. Commensal GM affects brain development, behavior, and healthy aging suggesting that building changes in GM might be a potential therapeutic method. The innovation in GM dysbiosis is intervention by Fecal Microbiota Transplantation (FMT), which has been confirmed as a therapy for recurrent Clostridium difficile infections and is promising for other clinical disorders, such as Parkinson's disease, Multiple Sclerosis (MS), Alzheimer's disease, and depression. Additionally, FMT may be possible to promote healthy aging, and extend longevity. This review aims to connect dysbiosis, neurological disorders, and aging and the potential of FMT as a therapeutic strategy to treat these disorders, and to enhance the quality of life in the elderly.

With the frequent occurrence of heatwaves, heatstroke (HS) is expected to become one of the main causes of global death. Being a multi-organized disease, HS can result in circulatory disturbance and systemic inflammatory response, with the gastrointestinal tract being one of the primary organs affected. Intestinal damage plays an initiating and promoting role in HS. Multiple pathways result in damage to the integrity of the intestinal epithelial barrier due to heat stress and hypoxia brought on by blood distribution. This usually leads to intestinal leakage as well as the infiltration and metastasis of toxins and pathogenic bacteria in the intestinal cavity, which will eventually cause inflammation in the whole body. A large number of studies have shown that intestinal damage after HS involves the body's stress response, disruption of oxidative balance, disorder of tight junction proteins, massive cell death, and microbial imbalance. Based on these damage mechanisms, protecting the intestinal barrier and regulating the body's inflammatory and immune responses are effective treatment strategies. To better understand the pathophysiology of this complex process, this review aims to outline the potential processes and possible therapeutic strategies for intestinal damage after HS in recent years.

Colorectal cancer (CRC) remains a significant healthcare burden worldwide, characterized by a complex interplay between obesity and chronic inflammation. While the relationship between CRC, obesity and altered lipid metabolism is not fully understood, there are evidences suggesting a link between them. In this study, we hypothesized that dysregulated lipid metabolism contributes to local accumulation of foam cells (FC) in CRC, which in turn disrupts antitumor immunosurveillance.

Tumor infiltrating FC and CD8+ were quantified by digital pathology in patients affected by T2-T4 CRC with any N stage undergoing radical upfront surgery (n=65) and correlated with patients' clinical outcomes. Multiparametric high-resolution flow cytometry analysis and bulk RNAseq of CRC tissue were conducted to evaluate the phenotype and transcriptomic program of immune cell infiltrate in relation to FC accumulation. The immunosuppressive effects of FC and mechanistic studies on FC-associated transforming growth factor-beta (TGF-β) and anti-PD-L1 inhibition were explored using an in-vitro human model of lipid-engulfed macrophages.

FC (large CD68+ Bodipy+ macrophages) accumulated at the tumor margin in CRC samples. FChigh tumors exhibited reduced CD8+ T cells and increased regulatory T cells (Tregs). Functional transcriptional profiling depicted an immunosuppressed milieu characterized by reduced interferon gamma, memory CD8+ T cells, and activated macrophages mirrored by increased T-cell exhaustion and Treg enrichment. Furthermore, FChigh tumor phenotype was independent of standard clinical factors but correlated with high body mass index (BMI) and plasma saturated fatty acid levels. In CD8low tumors, the FChigh phenotype was associated with a 3-year disease-free survival rate of 8.6% compared with 28.7% of FClow (p=0.001). In-vitro studies demonstrated that FC significantly impact on CD8 proliferation in TFG-β dependent manner, while inhibition of TGF-β FC-related factors restored antitumor immunity.

FC exert immunosuppressive activity through a TGF-β-related pathway, resulting in a CD8-excluded microenvironment and identifying immunosuppressed tumors with worse prognosis in patients with primary CRC. FC association with patient BMI and dyslipidemia might explain the link of CRC with obesity, and offers novel therapeutic and preventive perspectives in this specific clinical setting.

This study aimed to assess the effect of aerobic exercise on capillary density and vascular smooth muscle cell (VSMC) phenotype in the visceral and subcutaneous adipose tissue of high-fat-diet (HFD) mice in order to understand the mechanisms underlying improvements in insulin resistance (IR) and chronic inflammation in adipose tissue (AT).

Male C57BL/6J mice were divided into HFD and normal diet groups for 12 weeks and then further split into sedentary and aerobic exercise subgroups for an additional 8 weeks. Various parameters including body weight, fat weight, blood glucose, lipid profile, insulin levels, glucose tolerance, and inflammatory cytokines were evaluated.

Aerobic exercise reduced HFD-induced weight gain, IR, and improved lipid profiles. HFD had a minimal effect on inflammatory cytokines except in visceral adipose tissue (VAT). IR was associated with capillary density in subcutaneous adipose tissue (SAT) and VSMC phenotype in VAT. Aerobic exercise promoted anti-inflammatory responses in VAT, correlating with VSMC phenotype in this tissue.

Aerobic exercise can alleviate HFD-induced IR and inflammation through the modulation of VSMC phenotype in AT.

Ulcerative colitis (UC) belongs to chronic inflammatory disease with a relapsing characterization. Conventional oral drugs of UC are restricted in clinical by premature degradation in the gastrointestinal tract, modest efficacy, and adverse effects. CX5461 can treat autoimmune disease, immunological rejection, and vascular inflammation. However, low solubility, intravenous administration, and non-inflammatory targeting limited its clinical application. Herein, this work aims to develop Sophora Flavescens-derived exosomes-like nanovesicles carrying CX5461 (SFELNVs@CX5461) for efficient CX5461 oral delivery for UC therapy. We identified SFELNVs as nano-diameter (80 nm) with negative zeta potential (-32mV). Cellular uptake has shown that SFELNVs were targeted uptake by macrophages, thus increasing drug concentration. Additionally, oral SFELNVs@CX5461 exhibited good safety and stability, as well as inflammation-targeting ability in the gastrointestinal tract of dextran sodium sulfate (DSS)-induced colitis mice. In vivo, oral administration of SFELNVs and CX5461 could relieve mice colitis. More importantly, combined SFELNVs and CX5461 alleviated mice colitis by inhibiting pro-inflammatory factors (TNF-α, IL-1β, and IL-6) expression and promoting M2 macrophage polarization. Furthermore, SFELNVs promoted M2 polarization by miR4371c using miRNA sequencing. Our results suggest that SFELNVs@CX5461 represents a novel orally therapeutic drug that can ameliorate colitis, and a promising targeting strategy for safe UC therapy.

Malnutrition is linked to 45% of global childhood mortality, however, the impact of maternal malnutrition on the child's health remains elusive. Previous studies suggested that maternal malnutrition does not affect breast milk composition. Yet, malnourished children often develop a so-called environmental enteropathy, assumed to be triggered by frequent pathogen uptake and unfavorable gut colonization. Here, we show in a murine model that maternal malnutrition induces a persistent inflammatory gut dysfunction in the offspring that establishes during nursing and does not recover after weaning onto standard diet. Early intestinal influx of neutrophils, impaired postnatal development of gut-regulatory functions, and expansion of Enterobacteriaceae were hallmarks of this enteropathy. This gut phenotype resembled those developing under deficient S100a8/a9-supply via breast milk, which is a known key factor for the postnatal development of gut homeostasis. We could confirm that S100a8/a9 is lacking in the breast milk of malnourished mothers and the offspring's intestine. Nutritional supply of S100a8 to neonates of malnourished mothers abrogated the aberrant development of gut mucosal immunity and microbiota colonization and protected them lifelong against severe enteric infections and non-infectious bowel diseases. S100a8 supplementation after birth might be a promising measure to counteract deleterious imprinting of gut immunity by maternal malnutrition.

Colorectal cancer (CRC) resulting from chronic inflammation is a crucial issue in patients with inflammatory bowel disease (IBD). Although many reports established that intestinal resident CX3CR1high macrophages play an essential role in suppressing intestinal inflammation, their function in colitis-related CRC remains unclear. In this study, we found that colonic CX3CR1high macrophages, which were positive for MHC-II, F4/80 and CD319, promoted colitis-associated CRC. They highly expressed Col1a1, Tgfb, II10, and II4, and were considered to be fibrocytes with an immunosuppressive M2-like phenotype. CX3CR1 deficiency led to reductions in the absolute numbers of CX3CR1high fibrocytes through increased apoptosis, thereby preventing the development of colitis-associated CRC. We next focused statins as drugs targeting CX3CR1high fibrocytes. Statins have been actively discussed for patients with IBD and reported to suppress the CX3CL1/CX3CR1 axis. Statin treatment after azoxymethane/dextran sulfate sodium-induced inflammation reduced CX3CR1high fibrocyte counts and suppressed colitis-associated CRC. Therefore, CX3CR1high fibrocytes represent a potential target for carcinogenesis-preventing therapy, and statins could be safe therapeutic candidates for IBD.

Ulcerative colitis (UC) is a prevalent inflammatory bowel disease primarily impacting the mucosa of the colon. It is characterized by recurring and incurable symptoms and causes immense suffering and significant economic burden due to limited treatment options. Typical symptoms of UC include diarrhea, alterations in bowel patterns, bleeding from the rectum, rectal pain or urgency, anemia, and tiredness. Therefore, developing novel and effective treatment strategies for UC is imperative.

This review aimed to explain how macrophage polarization contributes to UC development and compiled information on natural compounds with promising therapeutic potential that can target the macrophage phenotype and shed light on its potential mode of action.

The phenotypic alteration of macrophages profoundly affects the development of UC, and these cells are essential for preserving intestinal immunological homeostasis. Evidence from research suggests that one effective method for UC prevention and therapy is to guide macrophage polarization toward the M2 phenotype. Phytochemicals, which are compounds extracted from plants, possess a wide array of biological activities. For example: Ginsenoside Rg1 emerges as a crucial regulator of macrophage polarization, promoting the M2 phenotype while inhibiting the M1 phenotype. Notably, their low toxicity and high effectiveness render them promising candidates for therapeutic interventions. These compounds have demonstrated encouraging protective effects against inflammation in the colon.

Exploring phytochemicals as a therapeutic avenue targeting macrophage polarization presents an innovative approach to treating UC.

Immune cells residing at the gingiva experience diverse and unique signals, tailoring their functions to enable them to appropriately respond to immunological challenges and maintain tissue integrity. The gingiva, defined as the mucosal barrier that surrounds and supports the teeth, is the only barrier site completely transected by a hard structure, the tooth. The tissue is damaged in early life during tooth eruption and chronically throughout life by the process of mastication. This occurs alongside challenges typical of barrier sites, including exposure to invading pathogens, the local commensal microbial community and environmental antigens. This review will focus on the immune network safeguarding gingival integrity, which is far less understood than that resident at other barrier sites. A detailed understanding of the gingiva-resident immune network is vital as it is the site of the inflammatory disease periodontitis, the most common chronic inflammatory condition in humans which has well-known detrimental systemic effects. Furthering our understanding of how the immune populations within the gingiva develop, are tailored in health, and how this is dysregulated in disease would further the development of effective therapies for periodontitis.

Ulcerative colitis, a subtype of chronic inflammatory bowel disease (IBD), is characterized by relapsing colonic inflammation and ulcers. The traditional Chinese herbal formulation Huang Lian Jie Du (HLJD) decoction is used clinically to treat diarrhea and colitis. However, the mechanisms associated with the effects of treatment remain unclear. This study aims to elucidate the molecular mechanistic effects of HLJD formulation on colitis.

Chronic colitis in mice was induced by adding 1% dextran sulfate sodium (DSS) to their drinking water continuously for 8 weeks, and HLJD decoction at the doses of 2 and 4 g/kg was administered orally to mice daily from the second week until experimental endpoint. Stool consistency scores, blood stool scores, and body weights were recorded weekly. Disease activity index (DAI) was determined before necropsy, where colon tissues were collected for biochemical analyses. In addition, the fecal microbiome of treated mice was characterized using 16S rRNA amplicon sequencing.

HLJD decoction at doses of 2 and 4 g/kg relieved DSS-induced chronic colitis in mice by suppressing inflammation through compromised macrophage activity in colonic tissues associated with the colony-stimulating factor 1 receptor (Csf1r)/Src pathway. Furthermore, the HLJD formula could modify the gut microbiota profile by decreasing the abundance of Bacteroides, Odoribacter, Clostridium_sensu_stricto_1, and Parasutterella. In addition, close correlations between DAI, colon length, spleen weight, and gut microbiota were identified.

Our findings revealed that the HLJD formula attenuated DSS-induced chronic colitis by reducing inflammation via Csf1r/Src-mediated macrophage infiltration, as well as modulating the gut microbiota profile.