Interleukin-22 suppresses major histocompatibility complex II in mucosal epithelial cells

Cannabidiol Targets Colorectal Cancer Cells via Cannabinoid Receptor 2, Independent of Common Mutations

Cannabidiol (CBD) is a non-neurotoxic, phytocannabinoid from cannabis with reported medicinal properties, including antiepileptic and anti-inflammatory activity. Several in vitro and in vivo studies have shown that CBD has antitumor potential against colorectal cancer (CRC), the third deadliest cancer in the world. However, as different mutations influence the antitumor effects and CBD can bind a variety of receptors, it is yet to be determined whether specific CRC mutations affect CBD's efficacy in treatment of CRC. To investigate this, we selected four CRC cell lines, including HCT116, HT-29, LS174T, and LS153, which harbor distinct mutations. Cells were treated with a range of concentrations of CBD to evaluate its cytotoxic effects and impact on cell proliferation, migration, and invasion by using a live-cell imaging system. IC50 values were then calculated for each parameter. The level of endoplasmic reticulum (ER) stress pathway markers was also measured using qRTPCR. The requirements for CB1 or CB2 receptor-medicated signaling were investigated using the selective inhibitors AM251 and SR144528, respectively. Our results demonstrate that CBD induces apoptosis and halts proliferation, migration, and invasion of CRC cell lines in a concentration-dependent manner. CBD showed potent antitumor effects in the tested cell lines with no obvious effect from different mutations such as KRAS, BRAF, APC, PTEN, etc. CBD also induced ER stress in CRC cells but not in healthy intestinal organoids. Cotreatment with SR144528 inhibited the effects of indicating involvement of CB2 receptor activation in the anticancer effects of CBD. Together, these results demonstrated that CBD could be effective for CRC regardless of the underlying mutation through CB2 receptor activation.

Fiber- and acetate-mediated modulation of MHC-II expression on intestinal epithelium protects from Clostridioides difficile infection

Here, we explore the relationship between dietary fibers, colonic epithelium major histocompatibility complex class II (MHC-II) expression, and immune cell interactions in regulating susceptibility to Clostridioides difficile infection (CDI). We find that a low-fiber diet increases MHC-II expression in the colonic epithelium, which, in turn, worsens CDI by promoting the development of pathogenic CD4+ intraepithelial lymphocytes (IELs). The influence of dietary fibers on MHC-II expression is mediated by its metabolic product, acetate, and its receptor, free fatty acid receptor 2 (FFAR2). While acetate activation of FFAR2 on epithelial cells helps resist CDI, it does not directly regulate MHC-II expression. Instead, MHC-II is regulated by FFAR2 in type 3 innate lymphoid cells (ILC3s). Acetate enhances interleukin-22 (IL-22) production by ILC3s, which then suppresses MHC-II expression on the colonic epithelium. In conclusion, a low-fiber diet reduces acetate-induced IL-22 production by ILC3s, leading to increased MHC-II on the colonic epithelium. This change affects recovery from CDI by expanding the population of pathogenic CD4+ IELs.

Amlexanox targeted inhibition of TBK1 regulates immune cell function to exacerbate DSS-induced inflammatory bowel disease

Amlexanox (ALX) is a small-molecule drug for the treatment of inflammatory, autoimmune, metabolic, and tumor diseases. At present, there are no studies on whether ALX has a therapeutic effect on inflammatory bowel disease (IBD). In this study, we used a mouse model of dextran sulfate sodium-induced colitis to investigate the effect of ALX-targeted inhibition of TBK1 on colitis. We found that the severity of colitis in mice was correlated with TBK1 expression. Notably, although ALX inhibited the activation of the TBK1-NF-κB/TBK1-IRF3 pro-inflammatory signaling pathway, it exacerbated colitis and reduced survival in mice. The results of drug safety experiments ruled out a relationship between this exacerbating effect and drug toxicity. In addition, ELISA results showed that ALX promoted the secretion of IL-1β and IFN-α, and inhibited the production of cytokines IL-6, TNF-α, IL-10, TGF-β, and secretory IgA. Flow cytometry results further showed that ALX promoted T-cell proliferation, activation, and differentiation, and thus played a pro-inflammatory role; also, ALX inhibited the generation of dendritic cells and the polarization of macrophages to M1 type, thus exerting anti-inflammatory effect. These data suggest that the regulation of ALX on the function of different immune cells is different, so the effect on the inflammatory response is bidirectional. In conclusion, our study demonstrates that simply inhibiting TBK1 in all immune cells is not effective for the treatment of colitis. Further investigation of the anti-inflammatory mechanism of ALX on dendritic cells and macrophages may provide a new strategy for the treatment of IBD.

I don't know about you, but I'm feeling IL-22

Defense of the human body against damaging and pathogenic insults is a heavily regulated affair. A primary mechanism of defense at sites of insult are soluble mediators whose defensive maneuvers increase barrier integrity and promote pro-reparative and resolution processes. IL-22 is a cytokine in the IL-10 cytokine family that has garnered increased attention in recent years due to its intimate link in promoting resolution of inflammatory insults, while simultaneously being over expressed in certain fibrotic and chronic inflammatory-skewed diseases. The spatial action of IL-22 centers around the barrier sites of the body, including the skin, lungs, and gut mucosa. As such, a detailed understanding of the role of this cytokine, the producers and responders, and the diseases resulting from over- or under-expression have prominent impacts on a variety of disease outcomes. Herein we present a comprehensive review of IL-22; from historical perspectives and initial discovery, as well as more recent data that dramatically expands on the cellular sources and impact of this cytokine. We aim to showcase the duality of IL-22 and highlight addressable gaps in the field of IL-22 crosstalk and impacts at the ever-important mucosal and tissue barrier sites.

Harnessing IL-22 for metabolic health: promise and pitfalls

Primarily perceived as an anti-inflammatory and antimicrobial mediator in mucosa and skin, interleukin-22 (IL-22) has emerged as a pivotal metabolic regulator. Central to IL-22 signaling is its receptor, IL-22RA1. Through IL-22RA1, IL-22 orchestrates glucose homeostasis by modulating insulin secretion, reducing cellular stress in pancreatic islets, promoting beta-cell regeneration, and influencing hepatic glucose and lipid metabolism. These actions suggest its potential as a therapeutic for metabolic dysfunctions like diabetes, obesity, and steatohepatitis. However, clinical applications of IL-22 face challenges related to off-target effects and safety concerns. This review explores IL-22's physiological roles, regulatory mechanisms, and profound influence on metabolic tissues. It also underscores IL-22's dual role in metabolic health and disease, advocating further research to harness its therapeutic potential.

Type 17 immunity: novel insights into intestinal homeostasis and autoimmune pathogenesis driven by gut-primed T cells

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.

Pancreatic beta-cell IL-22 receptor deficiency induces age-dependent dysregulation of insulin biosynthesis and systemic glucose homeostasis

The IL-22RA1 receptor is highly expressed in the pancreas, and exogenous IL-22 has been shown to reduce endoplasmic reticulum and oxidative stress in human pancreatic islets and promote secretion of high-quality insulin from beta-cells. However, the endogenous role of IL-22RA1 signaling on these cells remains unclear. Here, we show that antibody neutralisation of IL-22RA1 in cultured human islets leads to impaired insulin quality and increased cellular stress. Through the generation of mice lacking IL-22ra1 specifically on pancreatic alpha- or beta-cells, we demonstrate that ablation of murine beta-cell IL-22ra1 leads to similar decreases in insulin secretion, quality and islet regeneration, whilst increasing islet cellular stress, inflammation and MHC II expression. These changes in insulin secretion led to impaired glucose tolerance, a finding more pronounced in female animals compared to males. Our findings attribute a regulatory role for endogenous pancreatic beta-cell IL-22ra1 in insulin secretion, islet regeneration, inflammation/cellular stress and appropriate systemic metabolic regulation.

Intestine proteomic and metabolomic alterations in dogs infected with Toxocara canis

Toxocariasis is an important zoonotic parasitic disease. Toxocaris canis adults live and reproduce in the intestinal tract of dogs and other canine hosts, and the infectious eggs are continuously excreted in feces, which causes environmental contamination and has an important public health significance. In this study, TMT proteomic and untargeted metabolomic methods were used to explore the physiological and pathological effects on the intestinal tract of dogs which infected with T. canis, and a series of bioinformatics analyses were conducted to identify differentially expressed proteins (DEPs) and differentially expressed metabolites (DEMs). The proteomics results showed that 198 DEPs were mainly enriched in the immune system and signal transduction pathway, and involved in the regulation of the occurrence and development of cancer and infectious diseases. T. canis could disrupt intestinal permeability by increasing the expression of proteins such as zinc finger protein DZIP1L and myosin heavy chain 10. Additionally, T. canis infection could also inhibit the host immune response by decreasing the expression of MHC-II, NF-κB, DLA and other immune-related molecules. While, the metabolomics results revealed that the expression of oxoglutaric acid, glutamate, d-aspartate, arginine, taurochenodeoxycholic acid and taurocholic acid which participated in tricarboxylic acid (TCA) cycle, glycolysis/gluconeogenesis, bile secretion, biosynthesis of amino acids pathway were significantly decreased. The correlation results of proteomics and metabolomics showed that DEPs and DEMs were mainly co-enriched in bile secretion pathway to regulate intestinal peristalsis. Analyzing DEPs and DEMs will not only provide insights into the mechanisms of host parasite interaction, but also aid in identifying potential targets for therapy and diagnosis, thus setting the groundwork for effectively preventing and managing toxocariasis.

Functions of mucosal associated invariant T cells in eye diseases

Mucosal-associated invariant T (MAIT) cells are a unique subset of T cells that recognizes metabolites derived from the vitamin B2 biosynthetic pathway. Since the identification of cognate antigens for MAIT cells, knowledge of the functions of MAIT cells in cancer, autoimmunity, and infectious diseases has been rapidly expanding. Recently, MAIT cells have been found to contribute to visual protection against autoimmunity in the eye. The protective functions of MAIT cells are induced by T-cell receptor (TCR)-mediated activation. However, the underlying mechanisms remain unclear. Thus, this mini-review aims to discuss our findings and the complexity of MAIT cell-mediated immune regulation in the eye.

IL-22: Immunity's bittersweet symphony

Epithelial cells play a crucial role in barrier defense. Here, Moniruzzaman et al. (2023. J. Exp. Med.https://doi.org/10.1084/jem.20230106) discovered that interleukin-22 (IL-22) represses MHC class II expression by epithelial cells with an opposite impact on chronic inflammatory disease and viral infection.