Role of regulatory T cell in the pathogenesis of inflammatory bowel disease

The immune suppressive functions of macrophages are impaired in patients with ulcerative colitis

Chronic inflammation is the pathological feature of inflammatory bowel diseases (IBD), but its etiology is unknown. Macrophages are one of the major immune cell fractions in the colon. The objectives of this study are to characterize the immune regulatory functions of macrophages in the colon of patients with ulcerative colitis (UC). UC patients (n = 30) were recruited into this study. Colon lavage fluid (CLF) was collected. Macrophages are isolated from the cellular components of CLF. The immune suppressive functions of macrophages were assessed using immunological approaches. We observed that macrophages occupied about half of the proportions of the cellular components in CLF. Lower amounts of IL10 mRNA and proteins were detected in macrophages of the UC group than the normal control (NC) group. The expression of IL10 in CLF macrophages was positively correlated with the UC-associated cytokines, including tumor necrosis factor-α, interleukin (IL)-1β, IFN-γ, eosinophil-derived mediators, in CLF. The immune suppressive functions of CLF macrophages in UC patients were impaired. The inducibility of IL10 expression of UC M0 cells was defective as compared with NC M0 cells. Exposure to CpG restored the inducibility of IL10 expression in UC M0 cells, and gain the potential to acquire the immune suppressive functions. To sum up, the immune suppressive functions of UC macrophages are impaired. The inducibility of IL10 expression of M0 cells is impaired, which can be restored by the treatment with CpG.

Ginsenosides from Panax ginseng as potential therapeutic candidates for the treatment of inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is characterized by a chronic inflammation of the intestine, which significantly affects patients' quality of life. As a perennial plant with the homology of medicine and food, Panax ginseng is known for its substantial anti-inflammatory effects in various inflammatory disorders. Ginsenosides, the main bioactive compounds of P. ginseng, are recognized for their efficacy in ameliorating inflammation.

PURPOSE

Over the past decade, approximately 150 studies have investigated the effects of P. ginseng and ginsenosides on IBD treatment and new issues have arisen. However, there has yet to be a comprehensive review assessing the potential roles of ginsenosides in IBD therapy.

METHOD

This manuscript strictly adheres to the PRISMA guidelines, thereby guaranteeing systematic synthesis of data. The research articles referenced were sourced from major scientific databases, including Google Scholar, PubMed, and Web of Science. The search strategy employed keywords such as "ginsenoside", "IBD", "colitis", "UC", "inflammation", "gut microbiota", and "intestinal barrier". For image creation, Figdraw 2.0 was methodically employed.

RESULTS

Treatment with various ginsenosides markedly alleviated clinical IBD symptoms. These compounds have been observed to restore intestinal epithelia, modulate cellular immunity, regulate gut microbiota, and suppress inflammatory signaling pathways.

CONCLUSION

An increasing body of research supports the potential of ginsenosides in treating IBD. Ginsenosides have emerged as promising therapeutic agents for IBD, attributed to their remarkable efficacy, safety, and absence of side effects. Nevertheless, their limited bioavailability presents a substantial challenge. Thus, efforts to enhance the bioavailability of ginsenosides represent a crucial and promising direction for future IBD research.

Curcumin attenuates aflatoxin B1-induced ileum injury in ducks by inhibiting NLRP3 inflammasome and regulating TLR4/NF-κB signaling pathway

Aflatoxin B1 (AFB1) is a widespread toxic contamination in feed for animals. The primary active component of turmeric, curcumin (Cur), is an antioxidant and an anti-inflammatory. However, it is yet unknown how AFB1 affects the intestinal epithelial barrier and whether Cur acts as a protective mechanism when exposed to AFB1. Here, we explored the mechanism of AFB1-induced intestinal injury from intestinal epithelial barrier, inflammation, pyroptosis, and intestinal flora, and evaluated the protective role of Cur. We found that AFB1 caused weight loss and intestinal morphological damage that is mainly characterized by shortened intestinal villi, deepened crypts, and damaged intestinal epithelium. Exposure to AFB1 decreased the expression of Claudin-1, MUC2, ZO-1, and Occludin and increased the expression of pyroptosis-related factors (NLRP3, GSDMD, Caspase-1, IL-1β, and IL-18) and inflammation-related factors (TLR4, NF-κB, IκB, IFN-γ, and TNF-α). Furthermore, ileal gut microbiota was altered, and simultaneously, the Lactobacillus abundance was decreased. The gut microbiota interacts with a wide range of physiologic functions and disease development in the host through its metabolites, and disturbances in gut microbial metabolism can cause functional impairment of the ileum. Meanwhile, Cur can ameliorate histological ileum injuries and intestinal flora disturbance caused by AFB1. We found that Cur reversed the effects of AFB1 through modulating both NLRP3 inflammasome and the TLR4/NF-κB signaling pathway. In conclusion, AFB1 can induce inflammatory damage and pyroptosis in duck ileum, while Cur has obviously protective effects on all the above damages.

A Pro-Regenerative Supramolecular Prodrug Protects Against and Repairs Colon Damage in Experimental Colitis

Structural repair of the intestinal epithelium is strongly correlated with disease remission in inflammatory bowel disease (IBD); however, ulcer healing is not addressed by existing therapies. To address this need, this study reports the use of a small molecule prolyl hydroxylase (PHD) inhibitor (DPCA) to upregulate hypoxia-inducible factor one-alpha (HIF-1α) and induce mammalian regeneration. Sustained delivery of DPCA is achieved through subcutaneous injections of a supramolecular hydrogel, formed through the self-assembly of PEG-DPCA conjugates. Pre-treatment of mice with PEG-DPCA is shown to protect mice from epithelial erosion and symptoms of dextran sodium sulfate (DSS)-induced colitis. Surprisingly, a single subcutaneous dose of PEG-DPCA, administered after disease onset, leads to accelerated weight gain and complete restoration of healthy tissue architecture in colitic mice. Rapid DPCA-induced restoration of the intestinal barrier is likely orchestrated by increased expression of HIF-1α and associated targets leading to an epithelial-to-mesenchymal transition. Further investigation of DPCA as a potential adjunctive or stand-alone restorative treatment to combat active IBD is warranted.

Cutting Edge: Hypoxia Sensing by the Histone Demethylase UTX (KDM6A) Limits Colitogenic CD4+ T Cells in Mucosal Inflammation

Hypoxia is a hallmark of inflammatory conditions (e.g., inflammatory bowel disease [IBD]), and adaptive responses have consequently evolved to protect against hypoxia-associated tissue injury. Because augmenting hypoxia-induced protective responses is a promising therapeutic approach for IBD, a more complete understanding of these pathways is needed. Recent work has demonstrated that the histone demethylase UTX is oxygen-sensitive, but its role in IBD is unclear. In this study, we show that hypoxia-induced deactivation of UTX downregulates T cell responses in mucosal inflammation. Hypoxia results in decreased T cell proinflammatory cytokine production and increased immunosuppressive regulatory T cells, and these findings are recapitulated by UTX deficiency. Hypoxia leads to T cell accumulation of H3K27me3 histone modifications, suggesting that hypoxia impairs UTX's histone demethylase activity to dampen T cell colitogenic activity. Finally, T cell-specific UTX deletion ameliorates colonic inflammation in an IBD mouse model, implicating UTX's oxygen-sensitive demethylase activity in counteracting hypoxic inflammation.

Mediator complex subunit 1 architects a tumorigenic Treg cell program independent of inflammation

While immunotherapy has revolutionized cancer treatment, its safety has been hampered by immunotherapy-related adverse events. Unexpectedly, we show that Mediator complex subunit 1 (MED1) is required for T regulatory (Treg) cell function specifically in the tumor microenvironment. Treg cell-specific MED1 deletion does not predispose mice to autoimmunity or excessive inflammation. In contrast, MED1 is required for Treg cell promotion of tumor growth because MED1 is required for the terminal differentiation of effector Treg cells in the tumor. Suppression of these terminally differentiated Treg cells is sufficient for eliciting antitumor immunity. Both human and murine Treg cells experience divergent paths of differentiation in tumors and matched tissues with non-malignant inflammation. Collectively, we identify a pathway promoting the differentiation of a Treg cell effector subset specific to tumors and demonstrate that suppression of a subset of Treg cells is sufficient for promoting antitumor immunity in the absence of autoimmune consequences.

Immunomodulatory Effects of Vitamin D and Zinc on Viral Infection

Several nutrients are crucial in enhancing the immune system and preserving the structural integrity of bodily tissue barriers. Vitamin D (VD) and zinc (Zn) have received considerable interest due to their immunomodulatory properties and ability to enhance the body's immune defenses. Due to their antiviral, anti-inflammatory, antioxidative, and immunomodulatory properties, the two nutritional powerhouses VD and Zn are crucial for innate and adaptive immunity. As observed with COVID-19, deficiencies in these micronutrients impair immune responses, increasing susceptibility to viral infections and severe disease. Ensuring an adequate intake of VD and Zn emerges as a promising strategy for fortifying the immune system. Ongoing clinical trials are actively investigating their potential therapeutic advantages. Beyond the immediate context of the pandemic, these micronutrients offer valuable tools for enhancing immunity and overall well-being, especially in the face of future viral threats. This analysis emphasizes the enduring significance of VD and Zn as both treatment and preventive measures against potential viral challenges beyond the current health crisis. The overview delves into the immunomodulatory potential of VD and Zn in combating viral infections, with particular attention to their effects on animals. It provides a comprehensive summary of current research findings regarding their individual and synergistic impacts on immune function, underlining their potential in treating and preventing viral infections. Overall, this overview underscores the need for further research to understand how VD and Zn can modulate the immune response in combatting viral diseases in animals.

The NF-κB signaling system in the immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is an idiopathic, chronic condition characterized by episodes of inflammation in the gastrointestinal tract. The nuclear factor κB (NF-κB) system describes a family of dimeric transcription factors. Canonical NF-κB signaling is stimulated by and enhances inflammation, whereas noncanonical NF-κB signaling contributes to immune organogenesis. Dysregulation of NF-κB factors drives various inflammatory pathologies, including IBD. Signals from many immune sensors activate NF-κB subunits in the intestine, which maintain an equilibrium between local microbiota and host responses. Genetic association studies of patients with IBD and preclinical mouse models confirm the importance of the NF-κB system in host defense in the gut. Other studies have investigated the roles of these factors in intestinal barrier function and in inflammatory gut pathologies associated with IBD. NF-κB signaling modulates innate and adaptive immune responses and the production of immunoregulatory proteins, anti-inflammatory cytokines, antimicrobial peptides, and other tolerogenic factors in the intestine. Furthermore, genetic studies have revealed critical cell type-specific roles for NF-κB proteins in intestinal immune homeostasis, inflammation, and restitution that contribute to the etiopathology of IBD-associated manifestations. Here, we summarize our knowledge of the roles of these NF-κB pathways, which are activated in different intestinal cell types by specific ligands, and their cross-talk, in fueling aberrant intestinal inflammation. We argue that an in-depth understanding of aberrant immune signaling mechanisms may hold the key to identifying predictive or prognostic biomarkers and developing better therapeutics against inflammatory gut pathologies.

Effectiveness and safety of darvadstrocel in patients with complex perianal fistulizing Crohn's disease: a systematic review

Background

Managing complex perianal fistulizing Crohn's disease (CD) remains challenging, despite current medical and surgical treatment approaches. Darvadstrocel, a therapy utilizing adipose-derived stem cells, shows promise in promoting tissue regeneration and healing, offering a novel and effective treatment for fistula management.

Method

A systematic literature search was conducted on PubMed and Scopus to identify studies involving patients with complex perianal fistulizing CD treated with darvadstrocel.

Results

In total, 2 randomized controlled trials (RCT), 5 observational studies with retrospective data collection and 2 observational studies with prospective design were included in the final review. Data from the European ADMIRE-CD RCT demonstrated that darvadstrocel is superior to placebo in terms of clinical and imaging improvement over both the short and long term. These findings align with the prospective studies analyzed in this systematic review. The rate of treatment-emergent adverse events in the ADMIRE-CD trial's RCTs was similar in both the darvadstrocel and control groups, with perianal abscess being the most common adverse event up to 52 weeks after drug administration. Retrospective studies indicated no side-effects beyond 52 weeks.

Conclusions

Darvadstrocel appears to be a new, potentially effective and safe treatment option for the management of complex perianal fistulas. However, more randomized clinical trials are needed to evaluate the efficacy and safety profile of the drug.

Recent advances on emerging nanomaterials for diagnosis and treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic idiopathic inflammatory disorder that affects the entire gastrointestinal tract and is associated with an increased risk of colorectal cancer. Mainstream clinical testing methods are time-consuming, painful for patients, and insufficiently sensitive to detect early symptoms. Currently, there is no definitive cure for IBD, and frequent doses of medications with potentially severe side effects may affect patient response. In recent years, nanomaterials have demonstrated considerable potential for IBD management due to their diverse structures, composition, and physical and chemical properties. In this review, we provide an overview of the advances in nanomaterial-based diagnosis and treatment of IBD in recent five years. Multi-functional bio-nano platforms, including contrast agents, near-infrared (NIR) fluorescent probes, and bioactive substance detection agents have been developed for IBD diagnosis. Based on a series of pathogenic characteristics of IBD, the therapeutic strategies of antioxidant, anti-inflammatory, and intestinal microbiome regulation of IBD based on nanomaterials are systematically introduced. Finally, the future challenges and prospects in this field are presented to facilitate the development of diagnosis and treatment of IBD.

An Immune Atlas of T Cells in Transplant Rejection: Pathways and Therapeutic Opportunities

Short-term outcomes in allotransplantation are excellent due to technical and pharmacological advances; however, improvement in long-term outcomes has been limited. Recurrent episodes of acute cellular rejection, a primarily T cell-mediated response to transplanted tissue, have been implicated in the development of chronic allograft dysfunction and loss. Although it is well established that acute cellular rejection is primarily a CD4 + and CD8 + T cell mediated response, significant heterogeneity exists within these cell compartments. During immune responses, naïve CD4 + T cells are activated and subsequently differentiate into specific T helper subsets under the influence of the local cytokine milieu. These subsets have distinct phenotypic and functional characteristics, with reported differences in their contribution to rejection responses specifically. Of particular relevance are the regulatory subsets and their potential to promote tolerance of allografts. Unraveling the specific contributions of these cell subsets in the context of transplantation is complex, but may reveal new avenues of therapeutic intervention for the prevention of rejection.

Exploring Colitis through Dynamic T Cell Adoptive Transfer Models

Numerous animal models of colitis have provided important insights into the pathogenesis of inflammatory bowel disease (IBD), contributing to a better understanding of the underlying mechanisms for IBD. As aberrant CD4+ T cell responses play a critical role in the pathogenesis and development of IBD, T cell adoptive transfer models of colitis have become a valuable tool in investigating the immunopathogenesis of intestinal inflammation. While the adoptive transfer of CD4+ CD45RBhi T cells into immunedeficient recipient mice was the first discovered and is currently the most widely used model, several variations of the T cell transfer model have also been developed with distinct features. Here, we describe the history, principle, and characteristics of adoptive transfer colitis models and discuss their strengths, limitations, and applications.

Mechanistic insights into the role of probiotics in modulating immune cells in ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a persistent inflammatory disorder that affects the gastrointestinal tract, mainly the colon, which is defined by inflammatory responses and the formation of ulcers. Probiotics have been shown to directly impact various immune cells, including dendritic cells (DCs), macrophages, natural killer (NK) cells, and T and B cells. By interacting with cell surface receptors, they regulate immune cell activity, produce metabolites that influence immune responses, and control the release of cytokines and chemokines.

METHODS

This article is a comprehensive review wherein we conducted an exhaustive search across published literature, utilizing reputable databases like PubMed and Web of Science. Our focus centered on pertinent keywords, such as "UC," 'DSS," "TNBS," "immune cells," and "inflammatory cytokines," to compile the most current insights regarding the therapeutic potential of probiotics in managing UC.

RESULTS

This overview aims to provide readers with a comprehensive understanding of the effects of probiotics on immune cells in relation to UC. Probiotics have a crucial role in promoting the proliferation of regulatory T cells (Tregs), which are necessary for preserving immunological homeostasis and regulating inflammatory responses. They also decrease the activation of pro-inflammatory cells like T helper 1 (Th1) and Th17 cells, contributing to UC development. Thus, probiotics significantly impact both direct and indirect pathways of immune cell regulation in UC, promoting Treg differentiation, inhibiting pro-inflammatory cell activation, and regulating cytokine and chemokine release.

CONCLUSION

Probiotics demonstrate significant potential in modulating the immune reactions in UC. Their capacity to modulate different immune cells and inflammation-related processes makes them a promising therapeutic approach for managing UC. However, further studies are warranted to optimize their use and fully elucidate the molecular mechanisms underlying their beneficial effects in UC treatment.

Clinical Usefulness of Immune Profiling for Differential Diagnosis between Crohn's Disease, Intestinal Tuberculosis, and Behcet's Disease

It is important to make a differential diagnosis between inflammatory diseases of the bowel with similar clinical and endoscopic features. The profiling of immune cells could be helpful for accurately diagnosing inflammatory bowel diseases. We compared immune marker expression between Crohn's disease (CD), intestinal Behcet's disease (BD), and intestinal tuberculosis (TB) and evaluated the usefulness of immune profiling in differentiating between these diseases. Biopsy specimens were acquired around ulcerations on the terminal ileum or cecum from five patients with each disease. Panel 1 included multiplex immunohistochemistry staining for CD8, CD4, Foxp3, CD20, programmed death-1, and granzyme B. CD56, CD68, CD163, CD11c, and HLA-DR were analyzed in panel 2. The differences in cytotoxic T cells (CD8+CD4-Fopx3-CD20-), helper T cells (CD8-CD4+Fopx3-CD20-), and regulatory T cells (CD8-CD4+Fopx3+CD20-) were also not significant. However, M1 macrophage (CD68+CD163-HLA-DR-) cell densities were significantly higher in intestinal BD than in other diseases. The expression level of dendritic cells (CD56-CD68-CD163-CD11c+HLA-DR+) was highest in intestinal TB and lowest in intestinal BD. The expression of immune cells, including M1 macrophages and dendritic cells, was different between CD, intestinal BD, and intestinal TB. Immune profiling can be helpful for establishing differential diagnoses of inflammatory bowel diseases.

Hypoxia-sensing by the Histone Demethylase UTX ( KDM6A ) Controls Colitogenic CD4 + T cell Fate and Mucosal Inflammation

Hypoxia is a feature of inflammatory conditions [e.g., inflammatory bowel disease (IBD)] and can exacerbate tissue damage in these diseases. To counteract hypoxia's deleterious effects, adaptive responses have evolved which protect against hypoxia-associated tissue injury. To date, much attention has focused on hypoxia-activated HIF (hypoxia-inducible factor) transcription factors in these responses. However, recent work has identified epigenetic regulators that are also oxygen-sensitive, but their role in adaptation to hypoxic inflammation is currently unclear. Here, we show that the oxygen-sensing epigenetic regulator UTX is a critical modulator of colitis severity. Unlike HIF transcription factors that act on gut epithelial cells, UTX functions in colitis through its effects on immune cells. Hypoxia results in decreased CD4 + T cell IFN-γ production and increased CD4 + regulatory T cells, and these findings are recapitulated by T cell-specific UTX deficiency. Hypoxia impairs the histone demethylase activity of UTX, and loss of UTX function leads to accumulation of repressive H3K27me3 epigenetic marks at IL12/STAT4 pathway genes ( Il12rb2, Tbx21, and Ifng ). In a colitis mouse model, T cell-specific UTX deletion ameliorates colonic inflammation, protects against weight loss, and increases survival. Together these findings implicate UTX's oxygen-sensitive histone demethylase activity in mediating protective, hypoxia-induced pathways in colitis.

Targeted Application of Functional Foods as Immune Fitness Boosters in the Defense against Viral Infection

In recent times, the emergence of viral infections, including the SARS-CoV-2 virus, the monkeypox virus, and, most recently, the Langya virus, has highlighted the devastating effects of viral infection on human life. There has been significant progress in the development of efficacious vaccines for the prevention and control of viruses; however, the high rates of viral mutation and transmission necessitate the need for novel methods of control, management, and prevention. In recent years, there has been a shift in public awareness on health and wellbeing, with consumers making significant dietary changes to improve their immunity and overall health. This rising health awareness is driving a global increase in the consumption of functional foods. This review delves into the benefits of functional foods as potential natural means to modulate the host immune system to enhance defense against viral infections. We provide an overview of the functional food market in Europe and discuss the benefits of enhancing immune fitness in high-risk groups, including the elderly, those with obesity, and people with underlying chronic conditions. We also discuss the immunomodulatory mechanisms of key functional foods, including dairy proteins and hydrolysates, plant-based functional foods, fermentates, and foods enriched with vitamin D, zinc, and selenium. Our findings reveal four key immunity boosting mechanisms by functional foods, including inhibition of viral proliferation and binding to host cells, modulation of the innate immune response in macrophages and dendritic cells, enhancement of specific immune responses in T cells and B cells, and promotion of the intestinal barrier function. Overall, this review demonstrates that diet-derived nutrients and functional foods show immense potential to boost viral immunity in high-risk individuals and can be an important approach to improving overall immune health.

Chlorella vulgaris Modulates Gut Microbiota and Induces Regulatory T Cells to Alleviate Colitis in Mice

Chlorella vulgaris (C. vulgaris) is unicellular green algae consumed worldwide as a functional food. The immune stimulatory function of C. vulgaris is known; however, no study has elucidated its immune regulatory potential and associated microbiome modulation. In the current study, we aimed to validate the immune regulatory role of C. vulgaris mediated through two mechanisms. Initially, we assessed its ability to promote the expansion of the regulatory T cell (Treg) population. Subsequently, we investigated its impact on gut microbiota composition and associated metabolites. The supplementation of C. vulgaris altered the gut microbiota composition, accompanied by increased short-chain fatty acid (SCFAs) production in mice at homeostasis. We later used C. vulgaris in the treatment of a DSS-induced colitis model. C. vulgaris intervention alleviated the pathological symptom of colitis in mice, with a corresponding increase in Treg levels. As C. vulgaris is a safe and widely used food supplement, it can be a feasible strategy to instigate cross-talk between the host immune system and the intestinal flora for the effective management of inflammatory bowel disease (IBD).

Hypoxia in the Pathophysiology of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an idiopathic disease of disordered chronic inflammation in the intestines that affects many people across the world. While the disease is still being better characterized, greater progress has been made in understanding the many components that intersect in the disease. Among these components are the many pieces that compose the intestinal epithelial barrier, the various cytokines and immune cells, and the population of microbes that reside in the intestinal lumen. Since their discovery, the hypoxia-inducible factors (HIFs) have been found to play an expansive role in physiology as well as diseases such as inflammation due to their role in oxygen sensing-related gene transcription, and metabolic control. Making use of existing and developing paradigms in the immuno-gastroenterology of IBD, we summarized that hypoxic signaling plays as another component in the status and progression of IBD, which may include possible functions at the origins of inflammatory dysregulation. © 2023 American Physiological Society. Compr Physiol 13:4767-4783, 2023.

Hesperidin Attenuates Hypothyroidism-Induced Lung Damage in Adult Albino Rats by Modulating Oxidative Stress, Nuclear Factor Kappa-B Pathway, Proliferating Cell Nuclear Antigen and Inflammatory Cytokines

The occurrence of worsening pulmonary function has been connected to hypothyroidism (HPO). Hesperidin (HES) was suggested to have antioxidant, anti-proliferative, and anti-inflammatory potential. Our study's objective was to determine whether HES could reduce carbimazole (CBZ)-induced lung injury more effectively than Eltroxin (ELT) in adult male albino rats or not. At random, 32 rats were distributed into four groups: Group I: normal control, to induce HPO, the remaining three groups were given CBZ (20 mg/kg/day) dissolved in distilled water for 1 week. They were then split up into three groups. Group II: orally administered CBZ (20 mg/kg b.w in water/day), Group III: HES (200 mg/kg/day) dissolved in 1% carboxymethyl-cellulose + CBZ treated, and Group IV: ELT (0.045 mg/kg/day) dissolved in distilled water + CBZ treated. All treatments were delivered for 12 weeks. Blood was collected to assess thyroid-stimulating hormone (TSH) and thyroid hormones (THs). Lung injury was evaluated based on the pulmonary content of interleukin (IL)-35, IL-6, and tumor necrosis factor-alpha (TNF-α), along with the estimation of lipid peroxidation, catalase, glutathione levels, superoxide dismutase, heme oxygenase-1 (HO-1), and nuclear factor erythroid 2-related factor 2 (Nrf2). The histological, ultrastructural, and immunohistochemical study of nuclear factor Kappa-B (NF-κB) and inducible nitric oxide synthase (iNOS), together with estimating the proliferation of cells using Antigen Ki-67 in lung tissue were performed. HES and ELT primarily suppressed variable lung damage mechanisms by suppressing TSH, the NF-κB/TNF-α pathway, iNOS, lipid peroxidation, Ki-67, and inflammatory mediators. On the other hand, they improved THs, antioxidant parameters, and the Nrf2/HO-1 pathway. HES and ELT exhibited an ameliorative effect that was reflected in the histopathological, immunohistochemical, and ultrastructural results. These results indicate that HES is a pneumoprotective agent that could be a promising treatment for oxidative stress, inflammation, and proliferation.

AHR/TET2/NT5E axis downregulation is associated with the risk of systemic lupus erythematosus and its progression

The prognosis of systemic lupus erythematosus (SLE) is unpredictable. This study aimed to examine the regulatory mechanism of the AHR/TET2/NT5E pathway during SLE progression. The AHR, TET2 and NT5E expression levels were examined in T regulatory cells (Tregs) of patients with SLE. The correlation of AHR, TET2 or NT5E expression levels with the immunosuppressive functions of Tregs was analysed. In patients with SLE, the number of CD4⁺ IL2RA^- FOXP3⁺ T cell subset was positively correlated with the SLE disease activity index value and negatively correlated with the AHR and TET2 expression levels in CD4⁺ IL2RA⁺ FOXP3⁺ Tregs. Transcriptional profiles of 79 patients with SLE obtained from the Gene Expression Omnibus database (GSE61635 dataset) revealed a significant positive correlation between the mRNA expression levels of AHR and TET2. In silico analysis predicted that the TET2 promoter comprises an AHR-binding site. Kynurenine (KYN) promoted the binding of AHR to the TET2 promoter in Tregs of patients with SLE and Jurkat T cell lines. Furthermore, NT5E expression was significantly downregulated in Tregs of patients with SLE, which can be attributed to the dysregulation of NT5E promoter methylation status induced by downregulated TET2 activity. Furthermore, the Treg immunosuppressive activity, which is mediated through the TET2 and A2AR-adenosine pathways, in the KYN-treated group was approximately two-fold higher than that in the control group. The AHR/TET2/NT5E axis mediates the Treg immunosuppressive activity. These findings provide novel insights for the development of therapeutic approaches for SLE and related autoimmune diseases.

Cornus mas L. Extract Targets the Specific Molecules of the Th17/Treg Developmental Pathway in TNBS-Induced Experimental Colitis in Rats

Given that one of the crucial events in the pathogenesis of inflammatory bowel disease is the loss of homeostasis between Th17 and Treg cells, targeting the specific molecules of the Th17/Treg axis developmental pathway is a promising strategy for inflammatory bowel disease prevention and treatment. The current study aimed to assess the impact of cornelian cherry (Cornus mas L.) extract, rich in iridoids and polyphenols known for their potential anti-inflammatory activity, at two doses (20 or 100 mg/kg) on the crucial factors for Th17/Treg cell differentiation in the course of experimental colitis and compare this action with that of sulfasalazine. This study was conducted on the biobank colon tissue samples collected during the previous original experiment, in which colitis in rats was induced by trinitrobenzenesulfonic acid (TNBS). The levels of IL-6, RORγt, total STAT3, p-STAT3, and Foxp3 were determined by ELISA. The expression of PIAS3 mRNA was quantified by qPCR. Cornelian cherry extract at a dose of 100 mg/kg counteracted the TNBS-induced elevation of IL-6, RORγt, and p-STAT3 levels and a decrease in Foxp3 level and PIAS3 mRNA expression, while given concomitantly with sulfasalazine was more effective than sulfasalazine alone in reversing the TNBS-induced changes in IL-6, RORγt, total STAT3, p-STAT3, Foxp3 levels, and PIAS3 mRNA expression. The beneficial effect of cornelian cherry extract on experimental colitis may be due to its immunomodulatory activity reflected by the influence on factors regulating the Th17/Treg axis.

Blood regulatory T cells in inflammatory bowel disease, a systematic review, and meta-analysis

INTRODUCTION

Inflammatory bowel disease (IBD) is an autoimmune disease involving various parts of the gastrointestinal (GI) tract, which includes Crohn's disease (CD) and ulcerative colitis (UC). Due to the contradictory results regarding the percentage of peripheral blood (PB) regulatory T cells (Tregs) in IBD patients, this meta-analysis aimed to determine the Tregs frequency in IBD patients.

METHOD

We searched PubMed, Web of Science, SCOPUS, and Google Scholar databases for relevant observational articles that analyzed and reported the frequency of PB Tregs in IBD patients and healthy control groups. After choosing the related articles by two reviewers, the data regarding the definition of Tregs and their frequencies in different groups were recorded.

RESULT

In 22 studies, the results showed a nonsignificant difference in the frequency of PB Tregs between IBD cases and control subjects (SMD: -0.27, 95 % CI: -0.78, 0.23). However, the frequency of CD4⁺CD25⁺CD127^- (SMD: -0.89, 95 % CI: -1.52, -0.26) and CD4⁺CD25⁺FoxP3⁺ (SMD: -1.32, 95 % CI: -2.37, -0.26) Tregs were significantly lower in IBD cases, compared to healthy subjects. Also, UC cases and active IBD cases showed a significantly lower frequency of Treg cells, compared to controls and remission IBD cases, respectively (SMD: -0.68, 95 % CI: -1.24, -0.11 and SMD: -0.60, 95 % CI: -0.93, -0.27).

CONCLUSION

Our study highlighted a probable decrease of Tregs in IBD patients, especially the patients with active states of the disease. The decrease of Treg cells might cause an imbalance in the immune system and the over-activation of auto-immune responses against the digestive tract.

How does carrageenan cause colitis? A review

Carrageenan is a common additive, but mounting studies have reported that it may cause or aggravate inflammation in the intestines. The safety of carrageenan remains controversial and its inflammatory mechanisms are unclear. In this review, the pathogenesis of colitis by carrageenans was discussed. We analyzed the pathogenesis of inflammatory bowel disease, followed that line of thought, the existing evidence of carrageenans causing colitis in cellular and animal models was summarized to draw its colitis pathogenesis. Two pathways were described including: 1) carrageenan changed the composition of intestinal microbiota, especially Akkermansia muciniphila, which destroyed the mucosal barrier and triggered the inflammatory immune response; and 2) carrageenan directly contacted with receptors on epithelial cells and activated the NF-κB inflammatory pathway. This review aim to provide guidance for exploring the treatment of colitis caused by carrageenan, and safe processing and utilization of carrageenan in food industry, which is worthy of study in the future.

Innate and Adaptive Immunity during SARS-CoV-2 Infection: Biomolecular Cellular Markers and Mechanisms

The coronavirus 2019 (COVID-19) pandemic was caused by a positive sense single-stranded RNA (ssRNA) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, other human coronaviruses (hCoVs) exist. Historical pandemics include smallpox and influenza, with efficacious therapeutics utilized to reduce overall disease burden through effectively targeting a competent host immune system response. The immune system is composed of primary/secondary lymphoid structures with initially eight types of immune cell types, and many other subtypes, traversing cell membranes utilizing cell signaling cascades that contribute towards clearance of pathogenic proteins. Other proteins discussed include cluster of differentiation (CD) markers, major histocompatibility complexes (MHC), pleiotropic interleukins (IL), and chemokines (CXC). The historical concepts of host immunity are the innate and adaptive immune systems. The adaptive immune system is represented by T cells, B cells, and antibodies. The innate immune system is represented by macrophages, neutrophils, dendritic cells, and the complement system. Other viruses can affect and regulate cell cycle progression for example, in cancers that include human papillomavirus (HPV: cervical carcinoma), Epstein-Barr virus (EBV: lymphoma), Hepatitis B and C (HB/HC: hepatocellular carcinoma) and human T cell Leukemia Virus-1 (T cell leukemia). Bacterial infections also increase the risk of developing cancer (e.g., Helicobacter pylori). Viral and bacterial factors can cause both morbidity and mortality alongside being transmitted within clinical and community settings through affecting a host immune response. Therefore, it is appropriate to contextualize advances in single cell sequencing in conjunction with other laboratory techniques allowing insights into immune cell characterization. These developments offer improved clarity and understanding that overlap with autoimmune conditions that could be affected by innate B cells (B1+ or marginal zone cells) or adaptive T cell responses to SARS-CoV-2 infection and other pathologies. Thus, this review starts with an introduction into host respiratory infection before examining invaluable cellular messenger proteins and then individual immune cell markers.

Mitotic spindle positioning protein (MISP) deficiency exacerbates dextran sulfate sodium (DSS)-induced colitis in mice

Inflammatory bowel disease (IBD) is classified into two types: Crohn's disease and ulcerative colitis. In IBD, the imbalance between the pro-inflammatory and anti-inflammatory cytokines prevents recovery from the inflammatory state, resulting in chronic inflammation in the colon. The mitotic spindle positioning protein (MISP) is localized to the apical membrane in the colon. In this study, we observed increased expression of MISP in the intestinal epithelial cells in dextran sulfate sodium (DSS)-induced colitis in mice. MISP-deficient mice receiving DSS showed significant exacerbation of colitis (e.g., weight loss, loss of the crypts). The intestinal epithelial cells of the MISP-deficient mice showed a trend towards decreased cell proliferation after DSS treatment. Reverse transcription followed by quantitative polymerase chain reaction revealed that the expression levels of Tgfb1, an anti-inflammatory cytokine, were significantly reduced in the colon of MISP-deficient mice compared with the wild-type mice regardless of DSS treatment. These findings indicate that MISP may play a role in the recovery of the colon after inflammation through its anti-inflammatory and proliferative activities, suggesting that MISP may be a new therapeutic target for IBD.

CD83 Regulates the Immune Responses in Inflammatory Disorders

Activating the immune system plays an important role in maintaining physiological homeostasis and defending the body against harmful infections. However, abnormalities in the immune response can lead to various immunopathological responses and severe inflammation. The activation of dendritic cells (DCs) can influence immunological responses by promoting the differentiation of T cells into various functional subtypes crucial for the eradication of pathogens. CD83 is a molecule known to be expressed on mature DCs, activated B cells, and T cells. Two isotypes of CD83, a membrane-bound form and a soluble form, are subjects of extensive scientific research. It has been suggested that CD83 is not only a ubiquitous co-stimulatory molecule but also a crucial player in monitoring and resolving inflammatory reactions. Although CD83 has been involved in immunological responses, its functions in autoimmune diseases and effects on pathogen immune evasion remain unclear. Herein, we outline current immunological findings and the proposed function of CD83 in inflammatory disorders.

A Protective Role of NOD2 on Oxazolone-induced Intestinal Inflammation Through IL-1β-mediated Signalling Pathway

BACKGROUND AND AIMS

NOD2 has emerged as a critical player in the induction of both Th1 and Th2 responses for potentiation and polarisation of antigen-dependent immunity. Loss-of-function mutations in the NOD2-encoding gene and deregulation of its downstream signalling pathway have been linked to Crohn's disease. Although it is well documented that NOD2 is capable of sensing bacterial muramyl dipeptide, it remains counter-intuitive to link development of overt intestinal inflammation to a loss of bacterial-induced inflammatory response. We hypothesised that a T helper bias could also contribute to an autoimmune-like colitis different from inflammation that is fully fledged by Th1 type cells.

METHODS

An oedematous bowel wall with a mixed Th1/Th2 response was induced in mice by intrarectal instillation of the haptenating agent oxazolone. Survival and clinical scoring were evaluated. At several time points after instillation, colonic damage was assessed by macroscopic and microscopic observations. To evaluate the involvement of NOD2 in immunochemical phenomena, quantitative polymerase chain reaction [PCR] and flow cytometry analysis were performed. Bone marrow chimera experimentation allowed us to evaluate the role of haematopoietic/non-hematopoietic NOD2-expressing cells.

RESULTS

Herein, we identified a key regulatory circuit whereby NOD2-mediated sensing of a muramyl dipeptide [MDP] by radio-resistant cells improves colitis with a mixed Th1/Th2 response that is induced by oxazolone. Genetic ablation of either Nod2 or Ripk2 precipitated oxazolone colitis that is predominantly linked to a lack of interferon-gamma. Bone marrow chimera experiments revealed that inactivation of Nod2 signalling in non-haematopoietic cells is causing a biased M1-M2 polarisation of macrophages and a decreased frequency of splenic regulatory T cells that correlates with an impaired activation of CD4 + T cells within mesenteric lymph nodes. Mechanistically, mice were protected from oxazolone-induced colitis upon administration of MDP in an interleukin-1- and interleukin-23-dependent manner.

CONCLUSIONS

These findings indicate that Nod2 signalling may prevent pathological conversion of T helper cells for maintenance of tissue homeostasis.

Anti-Amnesic Effect of Synbiotic Supplementation Containing Corni fructus and Limosilactobacillus reuteri in DSS-Induced Colitis Mice

This study was conducted to compare the synbiotic activity between Corni fructus (C. fructus) and Limosilactobacillus reuteri (L. reuteri) on dextran sulfate sodium (DSS)-induced colitis and cognitive dysfunction in C57BL/6 mice. C. fructus (as prebiotics, PRE), L. reuteri (as probiotics, PRO), and synbiotics (as a mixture of L. reuteri and C. fructus, SYN) were fed to mice for 3 weeks. Consumption of PRE, PRO, and SYN ameliorated colitis symptoms in body weight, large intestinal length, and serum albumin level. Moreover, SYN showed a synergistic effect on intestinal permeability and intestinal anti-inflammation response. Also, SYN significantly improved cognitive function as a result of measuring the Y-maze and passive avoidance tests in DSS-induced behavioral disorder mice. Especially, SYN also restored memory function by increasing the cholinergic system and reducing tau and amyloid β pathology. In addition, PRE, PRO, and SYN ameliorated dysbiosis by regulating the gut microbiota and the concentration of short-chain fatty acids (SCFAs) in feces. The bioactive compounds of C. fructus were identified with quinic acid, morroniside, loganin, and cornuside, using ultra-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS2). In conclusion, synbiotic supplementation alleviated DSS-induced colitis and cognitive dysfunction by modulating gut microbiota, proinflammatory cytokines, and SCFAs production.

Extracellular vesicles produced by bone marrow mesenchymal stem cells overexpressing programmed death-ligand 1 ameliorate dextran sodium sulfate-induced ulcerative colitis in rats by regulating Th17/Treg cell balance through PTEN/PI3K/AKT/mTOR axis

BACKGROUND AND AIM

Programmed death-ligand 1 (PD-L1) was involved in regulating Th17/Treg cell balance in ulcerative colitis (UC). Extracellular vesicles (EVs) from genetically modified bone marrow mesenchymal stem cells (BMSCs) can serve as a stable delivery system to overexpress PD-L1. The study was designed to evaluate the therapeutic mechanism of BMSC-EVs overexpressing PD-L1 (PD-L1-EVs) on ulcerative colitis.

METHODS

Experimental model of UC was established in rats by drinking 5% dextran sulfate sodium (DSS). Apoptosis-related proteins, inflammatory response-related factors and oxidative stress related mediators were detected. Westernblot was used to detecte key proteins in the PI3K/AKT signaling pathway and its downstream effectors. The CD4⁺ Foxp3⁺ Treg cells and CD4⁺ IL-17A⁺ Th17 cells in spleen and mesenteric lymph nodes (MLNs) was detected by flow cytometry.

RESULTS

PD-L1-EVs significantly alleviated the manifestations and pathological damage of UC rats by inhibiting the expression of IFN-γ, IL-1β, IL-8, IL-6, IL-2, BAX, NF-κB, TNF-α, MPO, and MDA, and up-regulating the expression of IL-4, BCL-2, SOD, and GSH. Furthermore, the proportions of Th17 cells were decreased and that of Treg cells were upregulated by PD-L1-EVs treatment. PTEN inhibitors (bpv) partially abolished the inhibitory effect of PD-L1-EVs on PI3K-AKT signaling and impaired the therapeutic efficacy of PD-L1-EVs.

CONCLUSIONS

PD-L1-EVs mitigated colonal inflammation, apoptosis and oxidative stress through blocking the activation of PI3K/Akt/mTOR pathway and regulating the balance of Th17/Treg cells.

Screening of ulcerative colitis biomarkers and potential pathways based on weighted gene co-expression network, machine learning and ceRNA hypothesis

BACKGROUND

Ulcerative colitis (UC) refers to an intractable intestinal inflammatory disease. Its increasing incidence rate imposes a huge burden on patients and society. The UC etiology has not been determined, so screening potential biomarkers is critical to preventing disease progression and selecting optimal therapeutic strategies more effectively.

METHODS

The microarray datasets of intestinal mucosal biopsy of UC patients were selected from the GEO database, and integrated with R language to screen differentially expressed genes and draw proteins interaction network diagrams. GO, KEGG, DO and GSEA enrichment analyses were performed to explore their biological functions. Through machine learning and WGCNA analysis, targets that can be used as UC potential biomarkers are screened out. ROC curves were drawn to verify the reliability of the results and predicted the mechanism of marker genes from the aspects of immune cell infiltration, co-expression analysis, and competitive endogenous network (ceRNA).

RESULTS

Two datasets GSE75214 and GSE87466 were integrated for screening, and a total of 107 differentially expressed genes were obtained. They were mainly related to biological functions such as humoral immune response and inflammatory response. Further screened out five marker genes, and found that they were associated with M0 macrophages, quiescent mast cells, M2 macrophages, and activated NK cells in terms of immune cell infiltration. The co-expression network found significant co-expression relationships between 54 miRNAs and 5 marker genes. According to the ceRNA hypothesis, NEAT1-miR-342-3p/miR-650-SLC6A14, NEAT1-miR-650-IRAK3, and XIST-miR-342-3p-IRAK3 axes were found as potential regulatory pathways in UC.

CONCLUSION

This study screened out five biomarkers that can be used for the diagnosis and treatment of UC, namely SLC6A14, TIMP1, IRAK3, HMGCS2, and APOBEC3B. Confirmed that they play a role in the occurrence and development of UC at the level of immune infiltration, and proposed a potential RNA regulatory pathway that controls the progression of UC.

Computational modeling of complex bioenergetic mechanisms that modulate CD4+ T cell effector and regulatory functions

We built a computational model of complex mechanisms at the intersection of immunity and metabolism that regulate CD4+ T cell effector and regulatory functions by using coupled ordinary differential equations. The model provides an improved understanding of how CD4+ T cells are shaping the immune response during Clostridioides difficile infection (CDI), and how they may be targeted pharmacologically to produce a more robust regulatory (Treg) response, which is associated with improved disease outcomes during CDI and other diseases. LANCL2 activation during CDI decreased the effector response, increased regulatory response, and elicited metabolic changes that favored Treg. Interestingly, LANCL2 activation provided greater immune and metabolic modulation compared to the addition of exogenous IL-2. Additionally, we identified gluconeogenesis via PEPCK-M as potentially responsible for increased immunosuppressive behavior in Treg cells. The model can perturb immune signaling and metabolism within a CD4+ T cell and obtain clinically relevant outcomes that help identify novel drug targets for infectious, autoimmune, metabolic, and neurodegenerative diseases.

Polyphenols and inflammatory bowel disease: Natural products with therapeutic effects?

Inflammatory bowel disease (IBD) is a long-life disease with periods of recurrence and relief. Oxidative stress plays an important role in the pathogenesis of this disease. Recent years' studies in the field of IBD treatment mostly have focused on targeting cytokines and immune cell trafficking using antibodies and inhibitors, altering the composition of intestinal bacteria in the line of attenuation of inflammation using probiotics and prebiotics, and attenuating oxidative stress through antioxidant supplementation. Studies in animal models of IBD have shown that some polyphenolic compounds including curcumin, quercetin, resveratrol, naringenin, and epigallocatechin-3-gallate can affect almost all of the above aspects and are useful compounds in the treatment of IBD. Clinical studies performed on IBD patients have also confirmed the findings of animal model studies and have shown that supplementation with some of the above-mentioned polyphenolic compounds has positive effects in reducing disease clinical and endoscopic activity, inducing and maintaining remission, and improving quality of life. In this review article, in addition to a detailed reviewing the effects of the above-mentioned polyphenolic compounds on the events involved in the pathogenesis of IBD, the results of these clinical studies will also be reviewed.

Cytochrome P450 1A1 is essential for the microbial metabolite, Urolithin A-mediated protection against colitis

Background

Cytochrome P450 Family 1 Subfamily A Member 1 (CYP1A1) pathway, which is regulated by aryl hydrocarbon receptor (AhR) plays an important role in chemical carcinogenesis and xenobiotic metabolism. Recently, we demonstrated that the microbial metabolite Urolithin A (UroA) mitigates colitis through its gut barrier protective and anti-inflammatory activities in an AhR-dependent manner. Here, we explored role of CYP1A1 in UroA-mediated gut barrier and immune functions in regulation of inflammatory bowel disease (IBD).

Methods

To determine the role of CYP1A1 in UroA-mediated protectives activities against colitis, we subjected C57BL/6 mice and Cyp1a1^-/- mice to dextran sodium sulphate (DSS)-induced acute colitis model. The phenotypes of the mice were characterized by determining loss of body weight, intestinal permeability, systemic and colonic inflammation. Further, we evaluated the impact of UroA on regulation of immune cell populations by flow cytometry and confocal imaging using both in vivo and ex vivo model systems.

Results

UroA treatment mitigated DSS-induced acute colitis in the wildtype mice. However, UroA-failed to protect Cyp1a1^-/- mice against colitis, as evident from non-recovery of body weight loss, shortened colon lengths and colon weight/length ratios. Further, UroA failed to reduce DSS-induced inflammation, intestinal permeability and upregulate tight junction proteins in Cyp1a1^-/- mice. Interestingly, UroA induced the expansion of T-reg cells in a CYP1A1-dependent manner both in vivo and ex vivo models.

Conclusion

Our results suggest that CYP1A1 expression is essential for UroA-mediated enhanced gut barrier functions and protective activities against colitis. We postulate that CYP1A1 plays critical and yet unknown functions beyond xenobiotic metabolism in the regulation of gut epithelial integrity and immune systems to maintain gut homeostasis in IBD pathogenesis.

Astragaloside Ⅳ alleviates ulcerative colitis by regulating the balance of Th17/Treg cells

BACKGROUND

Restoring immune homeostasis by targeting the Th17/Treg response is a potentially valuable therapeutic strategy for ulcerative colitis (UC). Astragaloside IV (AS-Ⅳ) is a phytochemical naturally occurring in Astragalus membranaceus that has good anti-inflammatory, anti-oxidant and anti-stress properties. However, the effects of AS-IV on the homeostasis of Th17/Treg cells in colitis mice remains unknown.

PURPOSE

To investigate the protective effects and potential immunomodulatory mechanisms of AS-IV on UC.

METHODS

This study was constructed for DSS-induced acute colitis and recurrent colitis, with AS-IV administered prophylactically and therapeutically, respectively. The balance of Th17/Treg cells was analyzed by flow cytometry, their specific nuclear transcription factors were detected by RT-PCR as well as their secreted inflammatory cytokines were detected by ELISA and RT-PCR. Notch signaling-related proteins were detected by RT-PCR and Western blotting. Oxidative stress indicators were measured by biochemical technology.

RESULTS

In this study, AS-IV treatment not only effectively prevented and alleviated the clinical symptoms of DSS-induced colitis mice, including weight loss, DAI soaring, colon length shortening and colon weight gain, but also significantly improved ulcer formation, inflammatory cell infiltration and index, and regulated the expression of inflammatory cytokines in colon tissues. Importantly, the efficacy of high-dose AS-IV (100 mg/kg/day) in mice with recurrent colitis in this study was comparable to that of 5-ASA. AS-IV early administration was able to reshape the homeostasis of Th17/Treg cells in mice with acute colitis; meanwhile, AS-IV inhibited Th17 cell responses and promoted Treg cell responses in mice with recurrent colitis. Moreover, AS-IV not only inhibited the activation of Notch signaling pathway in colitis mice, but also prevented and ameliorated DSS-induced oxidative stress injury.

CONCLUSION

In conclusion, AS-IV effectively prevented and alleviated UC by reshaping Th17/Treg cell homeostasis and anti-oxidative stress.

Targeting Lineage-Specific Transcription Factors and Cytokines of the Th17/Treg Axis by Novel 1,3,4-Oxadiazole Derivatives of Pyrrolo[3,4-d]pyridazinone Attenuates TNBS-Induced Experimental Colitis

The pharmacotherapy of inflammatory bowel disease (IBD) is still not fully effective and safe. Attempts to search for new IBD drugs remain an incessant research aim. One of the novel approaches is targeting the developmental pathway molecules and effector cytokines of Th17/Treg axis. This study aimed to elucidate the impact of new pyrrolo[3,4-d]pyridazinone derivatives, compounds 7b, 10b, or 13b, on the course of experimental colitis in rats and to assess whether these new compounds may influence Th17/Treg axis. Rats were pretreated with studied compounds intragastrically before intrarectal administration of 2,4,6-trinitrobenzenesulfonic acid used for colitis induction. Body weight loss, disease activity index, colon index, and colon tissue damage were analyzed to evaluate the severity of colitis. The colonic levels of RORγt, STAT3, CCR6, Foxp3, IL-6, IL-10, IL-17, TNF-α, IL-23, and PGE₂ were assessed. Pretreatment with compounds 7b and 13b alleviated the severity of colitis and concomitantly counteracted the increased levels of RORγt, STAT3, CCR6, IL-6, IL-17, IL-23, TNF-α, and PGE₂. The beneficial effect of compounds 7b and 13b may be due to the decrease in the levels of Th17-specific transcription factors and cytokines. The studied compounds might therefore constitute a promising therapeutic strategy in Th17/Treg imbalance-driven inflammatory conditions such as IBD.

DMGV Is a Rheostat of T Cell Survival and a Potential Therapeutic for Inflammatory Diseases and Cancers

Activated effector T cells (Teff) and/or compromised regulatory T cells (Treg) underlie many chronic inflammatory diseases. We discovered a novel pathway to regulate survival and expansion of Teff without compromising Treg survival and a potential therapeutic to treat these diseases. We found dimethylguanidino valeric acid (DMGV) as a rheostat for Teff survival: while cell-intrinsic DMGV generated by Alanine-Glyoxylate Aminotransferase 2 (AGXT2) is essential for survival and expansion by inducing mitochondrial ROS and regulation of glycolysis, an excessive (or exogenous) DMGV level inhibits activated Teff survival, thereby the AGXT2-DMGV-ROS axis functioning as a switch to turn on and off Teff expansion. DMGV-induced ROS is essential for glycolysis in Teff, and paradoxically DMGV induces ROS only when glycolysis is active. Mechanistically, DMGV rapidly activates mitochondrial calcium uniporter (MCU), causing a surge in mitochondrial Ca2+ without provoking calcium influx to the cytosol. The mitochondrial Ca2+ surge in turn triggers the mitochondrial Na+/Ca2+ exchanger (NCLX) and the subsequent mitochondrial Na+ import induces ROS by uncoupling the Coenzyme Q cycle in Complex III of the electron transport chain. In preclinical studies, DMGV administration significantly diminished the number of inflammatory T cells, effectively suppressing chronic inflammation in mouse models of colitis and rheumatoid arthritis. DMGV also suppressed expansion of cancer cells in vitro and in a mouse T cell leukemic model by the same mechanism. Our data provide a new pathway regulating T cell survival and a novel mode to treat autoimmune diseases and cancers.

Intestine epithelial cell-derived extracellular vesicles alleviate inflammation induced by Clostridioides difficile TcdB through the activity of TGF-β1

Background

Clostridioides difficile infection (CDI) has been primarily associated with the toxin B (TcdB), one of the three known protein toxins secreted by C. difficile, which can activate the intestinal immune system and lead to pathological damage. Even though the biological functions of intestine epithelial cell-derived extracellular vesicles (I-Evs) have been well documented, the role of I-Evs in the process of CDI is still unknown.

Objectives

The protective effect of I-Evs against C. difficile TcdB was investigated both in cultured murine colon carcinoma MC38 cells and a mouse model used in this study.

Results

Mouse I-Evs with mean diameter ranging from 100 to 200 nm and a density of 1.09-1.17 g/mL were obtained and confirmed containing the Ev-associated specific surface markers CD63 and TSG101 as well as high level of TGF-β1. In MC38 cells, I-Evs were able to decrease the gene expression of IL-6, TNF-α, IL-1β, and IL-22 induced by C. difficile TcdB, but to increase both the gene expression and protein levels of TGF-β1. I-Evs treatment via intraperitoneal administration alleviates C. difficile TcdB-induced local colon inflammation in mice and increased their survival rate from 50% up to 80%. Furthermore, I-Evs induced an increase in the proportion of CD4+Foxp3+Tregs in vitro and in vivo through a TGF-β1-dependent mechanism by activating the TGF-β1 pathway and prompting phosphorylation of the downstream proteins Smad 2/3.

Conclusion

For the first time, our study demonstrated that I-Evs originated from intestine epithelial cells can alleviate inflammation induced by C. difficile TcdB both in vitro and in vivo. Therefore, I-Evs might be potentially a novel endogenous candidate for effective treatment of CDI.

The Business of T Cell Subsets and Cytokines in the Immunopathogenesis of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder and one of the most common inflammatory diseases of gastrointestinal (GI) tract in young adults. It is now equally prevalent in western countries as well as in Asian countries. Recently, there has been an increasing IBD burden in low- to middle-income countries as opposed to the earlier notion of this being a disease of the affluents. It occurs due to a variety of factors, namely, local immune alteration, disruption and inflammation of the mucosa, environmental factors, microbial commensals, and pathogen-induced genetic predisposition or genetic alteration in protective factors, etc.

So far, an exact etiopathogenesis of IBD is yet to be completely elucidated. Several recent types of research have emphasized the role of altered innate and humoral immunity in its causation, many of them based on animal models of IBD. Due to the poor understanding of its etiopathogenesis, IBD is still a challenge for the treating clinicians leading to persistent and recurrent disease in many cases.

Immune dysregulation in the GI tract incited by various pathogenic stimuli has gained great attention from researchers in the field of IBD. This review focuses on highlighting the role of various T cell subsets, their interplay, and associated cytokines involved in the pathogenesis of IBD along with a short description of genetic as well as other immunological factors. A better understanding of the pathogenic factors and subsequent randomized controlled trials targeting these factors is prudent for better therapeutic approaches for IBD.

Mineralocorticoid Receptor Deficiency in Treg Cells Ameliorates DSS-Induced Colitis in a Gut Microbiota-Dependent Manner

Mineralocorticoid receptor (MR) is a classic nuclear receptor and an effective drug target in the cardiovascular system. The function of MR in immune cells such as macrophages and T cells has been increasingly appreciated. The aim of this study was to investigate the function of Treg MR in the process of inflammatory bowel disease (IBD). We treated Treg MR-deficient (MR^flox/flox Foxp3^YFP-Cre , KO) mice and control (Foxp3^YFP-Cre , WT) mice with dextran sodium sulphate (DSS) to induce colitis and found that the severity of DSS-induced colitis was markedly alleviated in Treg MR-deficient mice, accompanied by reduced production of inflammatory cytokines, and relieved infiltration of monocytes, neutrophils and interferon γ⁺ T cells in colon lamina propria. Fecal microbiota of mice with colitis was analyzed by 16S rRNA gene sequencing and the composition of gut microbiota was vastly changed in Treg MR-deficient mice. Furthermore, depletion of gut microbiota by antibiotics abolished the protective effects of Treg MR deficiency and resulted in similar severity of DSS-induced colitis in WT and KO mice. Fecal microbiota transplantation from KO mice attenuated DSS-induced colitis characterized by alleviated inflammatory infiltration compared to that from WT mice. Hence, our study demonstrates that Treg MR deficiency protects against DSS-induced colitis by attenuation of colonic inflammatory infiltration. Gut microbiota is both sufficient and necessary for Treg MR deficiency to exert the beneficial effects.

microRNA-92a promotes CNS autoimmunity by modulating the regulatory and inflammatory T cell balance

A disequilibrium between immunosuppressive Tregs and inflammatory IL-17-producing Th17 cells is a hallmark of autoimmune diseases, including multiple sclerosis (MS). However, the molecular mechanisms underlying the Treg and Th17 imbalance in CNS autoimmunity remain largely unclear. Identifying the factors that drive this imbalance is of high clinical interest. Here, we report a major disease-promoting role for microRNA-92a (miR-92a) in CNS autoimmunity. miR-92a was elevated in experimental autoimmune encephalomyelitis (EAE), and its loss attenuated EAE. Mechanistically, miR-92a mediated EAE susceptibility in a T cell-intrinsic manner by restricting Treg induction and suppressive capacity, while supporting Th17 responses, by directly repressing the transcription factor Foxo1. Although miR-92a did not directly alter Th1 differentiation, it appeared to indirectly promote Th1 cells by inhibiting Treg responses. Correspondingly, miR-92a inhibitor therapy ameliorated EAE by concomitantly boosting Treg responses and dampening inflammatory T cell responses. Analogous to our findings in mice, miR-92a was elevated in CD4+ T cells from patients with MS, and miR-92a silencing in patients' T cells promoted Treg development but limited Th17 differentiation. Together, our results demonstrate that miR-92a drives CNS autoimmunity by sustaining the Treg/Th17 imbalance and implicate miR-92a as a potential therapeutic target for MS.

Dendritic cell combination therapy reduces the toxicity of triptolide and ameliorates colitis in murine models

Triptolide (TP) exerts a promising effect in the treatment of ulcerative colitis (UC). However, its toxicity seriously hinders its application in the clinic. Previous studies indicated that dendritic cells (DCs) are the main target through which TP exerts its immunoregulatory effect. Thus, we designed an approach to target DCs in vitro to avoid the direct exposure of organs to TP. Our results revealed that DCs pretreated with TP (DCTP) exerted satisfactory therapeutic effects in mice with colitis, resulting in improved colonic inflammation and alleviated local lesion damage. In addition, no obvious toxicity was observed. DCTP also reshaped the immune milieu by decreasing CD4⁺ T cell numbers and increasing regulatory T cell numbers in the spleen, mesenteric lymph nodes, peripheral blood and colon; these effects were further confirmed in vitro. Downregulation of CD80/86, ICAM-1, MHCI, TLR2/4, TNF-α, and IL-6 expression and upregulation of programmed cell death ligand 1 (PDL1) and IL-10 expression were observed, indicating that DCs were converted into tolerogenic DCs. In conclusion, DCTP can effectively reduce toxicity and alleviate colonic inflammation and local lesion damage in mice with colitis. The immune mechanism underlying the effects of DCTP included the conversion of DCs into tolerogenic DCs and the alteration of T cell differentiation to produce immunoinhibitory rather than immunostimulatory T cells.

Reactive Oxygen Species-Responsive Polyether Micelle Nanomaterials for Targeted Treatment of Ulcerative Colitis

As one of the most challenging inflammatory diseases, the incidence of ulcerative colitis (UC) is increasing year by year, but the existing therapeutic drugs are not effective and lack of targeting. Nanomaterials are expected to become promising delivery system due to their good targeting effects. Here, we designed a nanomaterial sensitive to reactive oxygen species, which can be used to treat IBD, especially UC. It is a self-assembled polyether micelle that can be oxidized at the inflammation site where the concentration of reactive oxygen increases, and effectively release the encapsulated budesonide (Bud). Experiments have proved that for DSS-induced colitis, the synthetic drug-loaded nanoparticles have excellent therapeutic effects, can effectively repair intestinal barrier, and significantly improve the damaged colon tissue. At the same time, it has a beneficial regulatory effect on inflammatory factors. Molecular mechanism studies have shown that it achieves its therapeutic effects by activating the peroxisome proliferators-activated receptors-γ (PPAR-γ) pathway and inhibiting the nuclear factor (NF)-κB pathway. This study proves that oral nano-micelles have an important impact on improving the efficacy of UC treatment drugs and have far-reaching significance for the targeted treatment of gastrointestinal diseases.

Hyperoside Ameliorates DSS-Induced Colitis through MKRN1-Mediated Regulation of PPARγ Signaling and Th17/Treg Balance

Hyperoside (HYP), a naturally occurring flavonoid compound, exerts multiple biological functions including myocardial protection, antiredox, and anti-inflammatory activities. However, the role of HYP on inflammatory bowel disease (IBD) and the underlying mechanism need to be further established. Here, we show that HYP treatment profoundly alleviated dextran sulfate sodium-induced ulcerative colitis in mice, characterized by reduced pathological scores, preserved tissue integrity, suppressed colonic inflammation, and balanced Th17/Treg response. Mechanistically, HYP was shown to restrain the expression of the E3 ubiquitin ligase, makorin ring finger protein 1 (MKRN1), which in turn promoted the ubiquitination and proteasomal degradation of peroxisome proliferator-activated receptor gamma (PPARγ), an essential regulator of Th17 and Treg differentiation. Consequently, HYP treatment enhanced PPARγ signaling and hence promoted Treg differentiation while suppressing Th17 cell development during colitis. Thus, our data indicate that HYP acts through the MKRN1/PPARγ axis to modulate the Th17/Treg axis and thereby confers protection against experimental colitis. The findings extend our understanding about HYP action and may provide a potential therapeutic target for IBD.

The neonatal microbiome in utero and beyond: perinatal influences and long-term impacts

The neonatal microbiome offers a valuable model for studying the origins of human health and disease. As the field of metagenomics expands, we also increase our understanding of early life influences on its development. In this review we will describe common techniques used to define and measure the microbiome. We will review in utero influences, normal perinatal development, and known risk factors for abnormal neonatal microbiome development. Finally, we will summarize current evidence that links early life microbial impacts on the development of chronic inflammatory diseases, obesity, and atopy.

New Insights on CD8+ T Cells in Inflammatory Bowel Disease and Therapeutic Approaches

CD8⁺ T cells are involved in the pathogenesis of inflammatory bowel disease (IBD), a complex multifactorial chronic disease. Here, we present an overview of the current research with the controversial findings of CD8⁺ T cell subsets and discuss some possible perspectives on their therapeutic value in IBD. Studies on the role of CD8⁺ T cells in IBD have contradictory outcomes, which might be related to the heterogeneity of the cells. Recent data suggest that cytotoxic CD8⁺ T cells (Tc1) and interleukin (IL) 17-producing CD8⁺ (Tc17) cells contribute to the pathogenesis of IBD. Moreover, subsets of regulatory CD8⁺ T cells are abundant at sites of inflammation and can exhibit pro-inflammatory features. Some subsets of tissue resident memory CD8⁺ T cells (Trm) might be immunosuppressant, whereas others might be pro-inflammatory. Lastly, exhausted T cells might indicate a positive outcome for patients. The function and plasticity of different subsets of CD8⁺ T cells in health and IBD remain to be further investigated in a challenging field due to the limited availability of mucosal samples and adequate controls.

E-cadherin activating antibodies limit barrier dysfunction and inflammation in mouse inflammatory bowel disease

Deficits in gastrointestinal (GI) paracellular permeability has been implicated in etiology of Inflammatory Bowel Disease (IBD), and E-cadherin, a key component of the epithelial junctional complex, has been implicated in both barrier function and IBD. We have previously described antibodies against E-cadherin that activate cell adhesion, and in this study, we show that they increase transepithelial electrical resistance in epithelial cell monolayers in vitro. We therefore tested the hypothesis that adhesion activating E-cadherin mAbs will enhance epithelial barrier function in vivo and limit progression of inflammation in IBD. Activating mAbs to mouse E-cadherin were tested in different mouse models of IBD including the IL10-/- and adoptive T cell transfer models of colitis. Previously established histological and biomarker measures of inflammation were evaluated to monitor disease progression. Mouse E-cadherin activating mAb treatment reduced total colitis score, individual histological measures of inflammation, and other hallmarks of inflammation compared to control treatment. Activating mAbs also reduced the fecal accumulation lipocalin2 and albumin content, consistent with enhanced barrier function. Therefore, E-cadherin activation could be a potential strategy for limiting inflammation in UC.