Differential dose effects of recombinant IL-25 on the development of dextran sulfate sodium-induced colitis

A novel pH-responsive berberine-loaded attapulgite microsphere for IBD therapy via the regulation of gut immunity and flora

Inflammatory bowel disease (IBD) is an idiopathic, lifelong, and devastating chronic inflammatory disease of the gastrointestinal tract. Berberine, an alkaloid extracted from the Chinese herb Huanglian, is a pharmaceutical ingredient with antibacterial, anti-inflammatory, and antiviral pharmacological effects in Chinese medicine. However, direct administration of berberine requires high doses due to its low bioavailability and high waste in the stomach. In this study, we prepared berberine-loaded pH-responsive Eudragit® FS 30D-attapulgite (FS-ATT) microspheres for the targeted treatment of colitis. The microspheres had pH-responsive release behavior, with minimal berberine release (about 5.97%) in simulated gastric fluid and high berberine release in simulated colonic fluid (about 69.27%). In addition, it was revealed by in vivo biological evaluations that, compared with drugs in an equivalent solution form taken orally, a significant improvement in IBD symptoms was observed after oral administration of drug-loaded FS-ATT microspheres, leading to an increase in the diversity of intestinal microbiota, inhibition of inflammatory cytokines, and enhanced therapeutic effects of berberine. The pH-responsive FS-ATT microspheres could offer a promising drug delivery platform for managing and treating many gastrointestinal diseases.

So Shiho Tang Reduces Inflammation in Lipopolysaccharide-Induced RAW 264.7 Macrophages and Dextran Sodium Sulfate-Induced Colitis Mice

So Shiho Tang (SSHT) is a traditional herbal medicine commonly used in Asian countries. This study evaluated the anti-inflammatory effect of SSHT and the associated mechanism using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages and murine dextran sodium sulfate (DSS)-induced ulcerative colitis models. Pre-treatment of RAW 264.7 macrophages with SSHT significantly reduced LPS-induced inflammation by decreasing nitrite production and regulating the mitogen-activated protein kinase pathway. Meanwhile, in mice, DSS-induced colitis symptoms, including colon shortening and body weight loss, were attenuated by SSHT. Moreover, representative compounds of SSHT, including glycyrrhizic acid, ginsenoside Rb1, baicalin, saikosaponin A, and saikosaponin B2, were quantified, and their effects on nitrite production were measured. A potential anti-inflammatory effect was detected in LPS-induced RAW 264.7 cells. Our findings suggest that SSHT is a promising anti-inflammatory agent. Its representative components, including saikosaponin B2, ginsenoside Rb1, and baicalin, may represent the key active compounds responsible for eliciting the anti-inflammatory effects and can, therefore, serve as quality control markers in SSHT preparations.

Could IL-25 be a potential therapeutic target for intestinal inflammatory diseases?

As a member of the IL-17 cytokine family, IL-25 (also called IL-17E) induces and sustains type 2 immunity. IL-25, which is mainly produced by intestinal epithelial cells, has been gradually investigated in recent years for its function in intestinal inflammation but is not yet fully understood. This review summarizes the expression and function of IL-25 in the intestine, especially the progression of its regulatory role on type 2 immunity-related cells. Finally, we discuss the dual role of IL-25 based on inflammatory bowel disease to inform research on targeting IL-25 for the treatment of intestinal inflammatory diseases.

Out of the shadow of interleukin-17A: the role of interleukin-17F and other interleukin-17 family cytokines in spondyloarthritis

PURPOSE OF REVIEW

The last decade has witnessed tremendous advances in revealing an important role for the interleukin (IL)-17 cytokine family in the pathogenesis of spondyloarthritis (SpA). Although most attention has been focused on IL-17A, a potential role of other IL-17 family members in inflammation and tissue remodelling is emerging. Herein, I review recent studies covering the role of IL-17B-F cytokines in the pathogenesis of SpA.

RECENT FINDINGS

Several recent studies provided new insights into the cellular source, regulation and function of IL-17F. IL-17F/IL-17A expression ratio is higher in psoriatic skin compared to SpA synovitis. IL-17F-expressing T cells produce different proinflammatory mediators than IL-17A-expressing cells, and IL-17F and IL-17A signal through different receptor complex. Dual IL-17A and IL-17F neutralization resulted in greater suppression of downstream inflammatory and tissue remodelling responses. Furthermore, there is additional evidence of IL-23-independent IL-17 production. In contrast to IL-17A, IL-17F and IL-17C, which play proinflammatory roles in skin and joint inflammation, an anti-inflammatory function is proposed for IL-17D. An increase in IL-17E is associated with subclinical gut microbiome alterations after anti-IL-17A therapy in SpA patients.

SUMMARY

IL-17 family cytokines may act as agonists or antagonists to IL-17A contributing in concert to local inflammatory responses. Understanding their function and identifying their cellular sources, and molecular mechanisms driving their expression will be the key to designing rational therapies in SpA.

Possible role of microRNA miRNA-IL-25 interaction in mice with ulcerative colitis

Background: The regulatory network of ulcerative colitis (UC)-associated miRNAs is not fully understood. In this study, we aim to investigate the global profile and regulatory network of UC associated miRNAs in the context of dextran sulfate sodium (DSS). Methods: UC was induced in C57BL mice using DSS. Differentially expressed miRNAs were screened by RNA sequencing and subjected to the Kyoto Encyclopedia of Genes and Genomes Pathway enrichment analysis. RT-qPCR was used to verify the differential expression of miRNAs and candidate target mRNA. Luciferase reporter vector bearing a miRNA binding site was constructed to verify the binding site of the miRNA on mRNA. Results:A total of 95 miRNAs (31 were up-regulated and 64 were down regulated) differentially expressed in the colonic tissues of the UC mice. Among the differentially expressed miRNAs, IL-25 pathway genes were enriched. Subsequent RT-qPCR confirmed a decreased expression of IL-25 and a significant up regulation of IL-25 target miRNAs including mmu-miR-135b-5p, mmu-miR-7239-5p and mmu-miR-691 in UC mice. Conclusion: Using the luciferase assay, we verified the biding sites of mmu-miR-135b-5p and mmu-miR-691 to the IL-25 3ʹUTR. In conclusion, mmu-miR-135b-5p:IL-25 and mmu-miR-691:IL-25 interactions are important pathways that may exert a protective role in UC.

Roles for Interleukin 17 and Adaptive Immunity in Pathogenesis of Colorectal Cancer

Sporadic colorectal cancer is one of the most common and lethal cancers worldwide. The locations and functions of immune cells in the colorectal tumor microenvironment are complex and heterogeneous. T-helper (Th)1 cell-mediated responses against established colorectal tumors are associated with better outcomes of patients (time of relapse-free or overall survival), whereas Th17 cell-mediated responses and production of interleukin 17A (IL17A) have been associated with worse outcomes of patients. Tumors that develop in mouse models of colorectal cancer are rarely invasive and differ in many ways from human colorectal tumors. However, these mice have been used to study the mechanisms by which Th17 cells and IL17A promote colorectal tumor initiation and growth, which appear to involve their direct effects on colon epithelial cells. Specific members of the colonic microbiota may promote IL17A production and IL17A-producing cell functions in the colonic mucosa to promote carcinogenesis. Increasing our understanding of the interactions between the colonic microbiota and the mucosal immune response, the roles of Th17 cells and IL17 in these interactions, and how these processes are altered during colon carcinogenesis, could lead to new strategies for preventing or treating colorectal cancer.

IL-25 attenuates rheumatoid arthritis through suppression of Th17 immune responses in an IL-13-dependent manner

IL-25, a new member of the IL-17 cytokine family, is involved in type 2 immunity initiation and has been associated with the pathogenesis of rheumatoid arthritis (RA). However, its exact role remains unclear. Here, we aimed to analyse IL-25 expression in the serum and synovial fluid of RA patients and evaluated the correlations between serum IL-25 levels, clinical and laboratory values and inflammation cytokines. Additionally, we investigated whether IL-25 can suppress Th1/Th17 responses involved in RA pathogenesis. We further determined whether IL-25 can alleviate collagen-induced arthritis (CIA) development in mice and the underlying mechanisms using in vitro and in vivo experiments. Our results showed that IL-25 was upregulated in the serum and synovial fluid of RA patients. Increased serum IL-25 levels were associated with disease severity and inflammatory response in RA patients. Furthermore, IL-25 inhibited CD4⁺ T-cell activation and differentiation into Th17 cells, without affecting Th1 cells in human RA and CIA models. Administration of IL-25 could attenuate CIA development by Th17 suppression in an IL-13-dependent manner. Our findings indicate that IL-25 plays a potent immunosuppressive role in the pathogenesis of RA and CIA by downregulating Th17 cell response, and thus, may be a potential therapeutic agent for RA.

Acute blockade of IL-25 in a colitis associated colon cancer model leads to increased tumor burden

Chronic inflammation within the gastrointestinal tract results in an increased risk for developing colorectal cancer. Epithelial cytokines, including interleukin-25 (IL-25), are produced in the colon and are critical for protection from parasites, but can also be pathogenic in the context of inflammatory bowel diseases and allergy. Whether IL-25 is involved in the progression from inflammation to cancer is still largely unexplored. Using a well-established murine model for colitis-induced colon cancer; we aimed to determine the role of IL-25 in this process. We found that acute IL-25 blockade resulted in greater tumor burdens compared to isotype control treated mice. Histologically, α-IL-25 treated mice had increased colitis scores compared to mice receiving isotype control antibody, as well as decreased eosinophilia. This is the first study to explore the therapeutic potential of using an IL-25 blocking antibody during a chronic inflammatory setting. Taken together these data suggest that IL-25 plays an inhibitory role in the growth and development of colonic tumors.

The roles and functional mechanisms of interleukin-17 family cytokines in mucosal immunity

The mucosal immune system serves as our front-line defense against pathogens. It also tightly maintains immune tolerance to self-symbiotic bacteria, which are usually called commensals. Sensing both types of microorganisms is modulated by signalling primarily through various pattern-recognition receptors (PRRs) on barrier epithelial cells or immune cells. After sensing, proinflammatory molecules such as cytokines are released by these cells to mediate either defensive or tolerant responses. The interleukin-17 (IL-17) family members belong to a newly characterized cytokine subset that is critical for the maintenance of mucosal homeostasis. In this review, we will summarize recent progress on the diverse functions and signals of this family of cytokines at different mucosal edges.

Distinctive expression pattern of interleukin-17 cytokine family members in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers in both genders. Even though interleukin (IL)-17A was shown to play an important role in intestinal tumourigenesis and CRC, other IL-17 family members were not studied well. We therefore studied the expression of IL-17 cytokine family members in CRC. Ten healthy colons and ten CRC mucosa were immunostained for IL-17B, IL-17C, IL-17E, and IL-17F, and their receptors IL-17RA, IL-17RB, and IL-17RC. Double immunofluorescence staining of the CRC mucosa was done for IL-17B with markers of neutrophils, endothelial cells, macrophages, T cells, mast cells, or fibroblasts. While IL-17B was increased in CRC with a strong presence both in the epithelial and stromal compartments, IL-17C showed different expression depending on the grade of differentiation and IL-17E remained unchanged. In contrast, IL-17F was decreased in CRC compared to healthy control. Colon epithelial cells stained positive for IL-17RA, IL-17RB, and IL-17RC in both healthy control and CRC. Neutrophils were the main source of IL-17B in the stroma. IL-17 family members demonstrated distinct expression patterns in CRC, suggesting a differential role exerted by each member in colon carcinogenesis.

Genetic deletion of IL-25 (IL-17E) confers resistance to dextran sulfate sodium-induced colitis in mice

BACKGROUND

IL-25 is emerging as a key regulator of inflammation in the intestinal mucosa because of its ability to promote type 2 while suppressing Th1 and Th17 responses. Several previous studies reported inconsistent results on the role of exogenous IL-25 in development of colonic inflammation and none were performed in animals with a genetic deletion of IL-25. We investigated the contribution of endogenous IL-25 to DSS-induced colitis using mice deficient in IL-25.

RESULTS

Mice were exposed to DSS in drinking water ad libitum either for seven days (acute) or for three cycles of seven days with DSS followed by 14 days without DSS (chronic) to induce colitis, respectively. The loss of body weight, appearance of diarrhea and bloody stools, and shortening of colon length were significantly less pronounced in IL-25(-/-) mice compared to WT mice after exposure to acute DSS. Histological examination showed that DSS-treated IL-25(-/-) mice had only mild inflammation in the colon, while severe inflammation developed in DSS-treated WT mice. A significant up-regulation of IL-33 was observed in acute DSS-treated WT but not in the IL-25(-/-) mice. There was significantly lower expression of pro-inflammatory cytokines in the colon of acute DSS-treated IL-25(-/-) compared to WT mice. IL-25(-/-) mice were also partially protected from chronic DSS challenge especially during the first 2 cycles of DSS exposure. In contrast to IL-25(-/-) mice, IL-13(-/-) mice were more susceptible to DSS-induced colitis. Finally, stimulation of T84 colonic epithelial cells with IL-25 up-regulated the expression of IL-33 and several pro-inflammatory cytokines.

CONCLUSIONS

These data indicate that endogenous IL-25 acts as a pro-inflammatory factor in DSS-induced colitis, which is unlikely to be mediated by IL-13 but possibly the induction of IL-33 and other pro-inflammatory mediators from colonic epithelial cells. The present study suggests that IL-25 may contribute to the pathogenesis of inflammatory bowel disease in at least a subgroup of patients.

Smooth muscle-specific overexpression of PGC-1α protects mice from acute colitis

AIM: To investigate the effect of smooth muscle-specific overexpression of peroxidase proliferator-activated receptor gamma coactivator-1α (PGC-1α) on dextran sulfate sodium (DSS)-induced acute colitis in mice.

METHODS: Two-month-old male mice were divided into four groups according to genotype (non-Tg/Tg) and treatment (H₂O/DSS), 10-13 mice for each group. Mice were administered with 3% DSS in drinking water for 7 days (+DSS) to induce inflammatory bowel disease (IBD). Control groups were given normal drinking water (+H₂O). At the end of the study, the symptoms and pathological changes were evaluated using disease activity index (DAI) and histopathological score (HPS) of acute colitis, respectively. The mRNA levels of inflammatory cytokines in the colon were determined.

RESULTS: Compared to control groups, DSS-treated groups had significantly decreased body weight (both P < 0.01), increased DAI (both P < 0.01) and HPS (9.6 ± 1.2 vs 1.2 ± 0.4; 5.0 ± 0.8 vs 1.2 ± 0.6, in non-Tg and Tg groups, respectively, both P < 0.01), and significantly shorter colon (5.0 cm ± 0.3 cm vs 7.8 cm ± 0.2 cm; 4.9 cm ± 0.1 cm vs 8.0 cm ± 0.3 cm, in non-Tg and Tg groups, respectively, both P < 0.01). Compared to the DSS-treated non-Tg group, the treated Tg group had significantly decreased DAI (P < 0.01), HPS (5.0 ± 0.8 vs 9.6 ± 1.2, P < 0.01) and tumor necrosis factor α (TNFα) mRNA level (0.24 ± 0.07 vs 0.45 ± 0.10, P < 0.05), and increased peroxidase proliferator-activated receptor γ (PPARγ) mRNA level (0.98 ± 0.15 vs 0.41 ± 0.07, P < 0.05).

CONCLUSION: Smooth muscle-specific overexpression of PGC-1α protects against DSS-induced acute colitis by reducing the expression of inflammatory factor TNFα, which might result from the activation of PPARγ.