IL-22 promotes occludin expression by activating autophagy and treats ulcerative colitis

Modulation of occludin, NF-κB, p-STAT3, and Th17 response by DJ-X-025 decreases inflammation and ameliorates experimental colitis

SCOPE

Inflammatory bowel disease (IBD) involves a range of immune-mediated disorders marked by systemic and local intestinal inflammation. We synthesized a novel compound DJ-X-025 and uncovered its anti-inflammatory properties using lipopolysaccharide (LPS)-induced RAW 264.7 macrophages in vitro and a dextran sodium sulfate (DSS)-induced model of colitis.

METHODS AND RESULTS

We evaluated the alteration in cell morphology, cytoskeletal proteins, and inflammatory markers of DJ-X-025 treated LPS-stimulated RAW 264.7 macrophages. We administered DJ-X-025 by oral gavage in DSS-induced colitis, examined colon histology, and alterations of immune cells by flow cytometry, and performed molecular studies using RT-qPCR and western blot analysis. DJ-X-025 treatment markedly altered the morphology of LPS-treated RAW 264.7 macrophages from elongated to round shapes, modulated actin and tubulin, and reduced the level of inflammatory markers like TNF-α, IL-1β, IL-6, and iNOS. Further, we observed that DJ-X-025 steered to improve colon length, muscularis mucosa thickness, and colon inflammatory score compared to the DSS group alone. DJ-X-025 effectively inverted the increased population of activated T cells, Th17, and macrophages in lamina propria by DSS treatment, leading to a substantial reduction in the inflammatory response in the colon. Strikingly, DJ-X-025 treatment enhanced the expression of occludin and diminished the expression of NF-κB and phosphorylation of STAT3 in the colon of DSS-treated mice compared to DSS-alone. Additionally, DJ-X-025 induced the expression of Foxp3 in the colon and, reduced systemic inflammatory cytokine/chemokine levels further supporting its immunomodulatory effects. These results suggest that DJ-X-025 is linked to the induction of occludin expression and decreased expression of p-STAT3/NF-κB and Th17 response in the colon, which together suppresses systemic and colon inflammatory cytokines for effective amelioration of experimental colitis.

CONCLUSION

These findings suggest that DJ-X-025 might be a promising therapeutic agent for the treatment of IBD.

Lipidated IL-22 Alone or Combined with Immunomodulatory Agents Improves Disease Endpoints and Promotes Mucosal Healing in a Mouse Model of Chronic Dextran Sodium Sulfate-Induced Colitis

BACKGROUND

IL-22 facilitates mucosal healing by directly inducing epithelial regeneration and barrier integrity, which is essential for achieving remission and thereby treating inflammatory bowel disease.

AIMS

Here, we evaluated efficacy of a novel lipidated IL-22 alone and in combination with immunomodulatory agents in addressing chronic dextran sodium sulfate (DSS)-induced colitis in mice and demonstrated action of IL-22 on mucosal healing.

METHODS

Mice were treated with DSS, followed by various doses of lipidated IL-22, anti-TNF antibody, fingolimod, or anti-mouse α4β7 integrin antibody. Additionally, gene expression was determined in colonic biopsies from ulcerative colitis patients to assess effects of IL-22 stimulation.

RESULTS

Lipidated IL-22 significantly improved all aspects of chronic DSS-induced colitis in mice, with dose-dependent efficacy. Combinations of a range of immunomodulatory agents with lipidated IL-22 showed further additive reductions in disease activity, significantly greater than those of monotherapies. Immunohistochemistry revealed that lipidated IL-22 increased epithelial cell proliferation and reduced CD3+ T-cell infiltration, indicating enhanced mucosal healing. This was further supported gene expression data from colonic biopsies from ulcerative colitis patients after IL-22 stimulation.

CONCLUSIONS

Given the challenges in achieving long-term remission in IBD due to inflammation and mucosal damage, lipidated IL-22 presents a promising treatment option that directly promotes mucosal healing, unlike traditional immunomodulatory therapies.

The emerging role of intestinal stem cells in ulcerative colitis

Ulcerative colitis (UC) is a chronic idiopathic inflammatory disease affecting the colon and rectum. Characterized by recurrent attacks, UC is often resistant to traditional anti-inflammatory therapies, imposing significant physiological, psychological, and economic burdens on patients. In light of these challenges, innovative targeted therapies have become a new expectation for patients with UC. A crucial pathological feature of UC is the impairment of the intestinal mucosal barrier, which underlies aberrant immune responses and inflammation. Intestinal stem cells (ISCs), which differentiate into intestinal epithelial cells, play a central role in maintaining this barrier. Growing studies have proved that regulating the regeneration and differentiation of ISC is a promising approach to treating UC. Despite this progress, there is a dearth of comprehensive articles describing the role of ISCs in UC. This review focuses on the importance of ISCs in maintaining the intestinal mucosal barrier in UC and discusses the latest findings on ISC functions, markers, and their regulatory mechanisms. Key pathways involved in ISC regulation, including the Wnt, Notch, Hedgehog (HH), Hippo/Yap, and autophagy pathways, are explored in detail. Additionally, this review examines recent advances in ISC-targeted therapies for UC, such as natural or synthetic compounds, microbial preparations, traditional Chinese medicine (TCM) extracts and compounds, and transplantation therapy. This review aims to offer novel therapeutic insights and strategies for patients who have long struggled with UC.

Liver abscess induced by intestinal hypervirulent Klebsiella pneumoniae through down-regulation of tryptophan-IPA-IL22 axis

Hypervirulent Klebsiella pneumoniae (hvKp) is a significant causative agent of invasive hepatic abscess syndrome in Asia, presenting substantial clinical challenges due to its intricate pathogenesis. This study revealed the crucial role of the gut microbiota in fortifying the host's defense against hvKp infection by enhancing interleukin-22 (IL-22), probably through regulating downstream antimicrobial peptides such as Reg3β. In antibiotic-treated mice, we observed that gut microbiota disruption impaired the transformation of tryptophan to indole, a key ligand for the aryl hydrocarbon receptor (AhR), consequently affecting the regulatory functions of IL-22. Our experimental findings revealed that administering rIL-22 or indole propionic acid notably diminished the translocation of hvKp from the intestine to the liver. This research not only underscores the pivotal role of the gut microbiome in modulating tryptophan metabolism and the IL-22 pathway but also highlights its critical function in preventing hvKp migration from the colon to the liver.

MITOCHONDRIAL ANTIVIRAL PATHWAYS CONTROL ANTI-HIV RESPONSES AND ISCHEMIC STROKE OUTCOMES VIA THE RIG-1 SIGNALING AND INNATE IMMUNITY MECHANISMS

Occludin (ocln) is one of the main regulatory cells of the blood-brain barrier (BBB). Ocln silencing resulted in alterations of the gene expression signatures of a variety of genes of the innate immunity system, including IFN-stimulated genes (ISGs) and the antiviral retinoic acid-inducible gene-1 (RIG-1) signaling pathway, which functions as a regulator of the cytoplasmic sensors upstream of the mitochondrial antiviral signaling protein (MAVS). Indeed, we observed dysfunctional mitochondrial bioenergetics, dynamics, and autophagy in our system. Alterations of mitochondrial bioenergetics and innate immune protection translated into worsened ischemic stroke outcomes in EcoHIV-infected ocln deficient mice. Overall, these results allow for a better understanding of the molecular mechanisms of viral infection in the brain and describe a previously unrecognized role of ocln as a key factor in the control of innate immune responses and mitochondrial dynamics, which affect cerebral vascular diseases such as ischemic stroke.

Safflower polysaccharide ameliorates acute ulcerative colitis by regulating STAT3/NF-κB signaling pathways and repairing intestinal barrier function

This study is to investigate the effect of SPS on the UC model. An animal model of UC induced by DSS was developed using C57BL/6 mice. The body weight was recorded every day, and the symptoms related to UC were detected. H&E staining, AB-PAS staining and PSR staining were used to evaluate the histopathological changes of the colon. Inflammation and mucosal barrier indicators were detected by qRT-PCR, and the 16 S rRNA sequence was used to detect the intestinal flora. SPS can significantly prevent and treat DSS-induced ulcerative colitis in animals. SPS significantly improved clinical symptoms, alleviated pathological damage, inhibited the infiltration of intestinal inflammatory cells. SPS treatment can protect goblet cells, enhance the expression of tight junction proteins and mucins, inhibit the expression of antimicrobial peptides, thereby improving intestinal barrier integrity. The prevention and treatment mechanism of SPS may be related to the inhibition of STAT3/NF-κB signaling pathway to regulate intestinal barrier function. In particular, SPS also significantly adjusted the structure of intestinal flora, significantly increasing the abundance of Akkermansia and Limosilactobacillus and inhibiting the abundance of Bacteroides. Overall, SPS has a significant therapeutic effect on ulcerative colitis mice, and is expected to play its value effectively in clinical treatment.

The role of interleukin-22 in mammalian intestinal homeostasis: Friend and foe

Interleukin-22 (IL-22) is an important cytokine in the intestinal environment. IL-22 is mainly produced by immune cells and targeted at nonimmune cells such as epithelial and stromal cells in a broad array of tissues such as -but not restricted to- the liver and adipose tissue. IL-22 therefore connects immune functions with metabolic functions of the host, and since it is induced by the microbiota, connects host functioning to the outside environment. IL-22 induces epithelial cell proliferation aiding in rapid epithelium regeneration and wound healing. Additionally, IL-22 activates antiapoptotic genes and DNA damage response pathways, enhancing epithelial cell survival. Recently, it has also been shown that IL-22 induces Paneth cell differentiation in humans. However, IL-22 can also contribute to intestinal epithelium damage and reduces microbial diversity in the intestine directly or indirectly by inducing excessive antimicrobial peptide production by epithelial cells. Moreover, IL-22 enhances angiogenesis and may therefore support tumorigenesis in the intestine. In conclusion, it appears that whether IL-22 has a beneficial or harmful effect in the mammalian intestine largely depends on its regulation. This review aims to provide a comprehensive overview of the current literature and emphasizes that IL-22 signaling outcome depends on the timing and duration of IL-22 production, the presence of it regulators such as IL-22BP, and the specific location of the cytokine production in the gastrointestinal tract.