Facilitation of colonic T cell immune responses is associated with an exacerbation of dextran sodium sulfate-induced colitis in mice lacking microsomal prostaglandin E synthase-1

Sinomenine hydrochloride improves DSS-induced colitis in mice through inhibition of the TLR2/NF-κB signaling pathway

BACKGROUND

Sinomenine hydrochloride (SH) has anti-inflammatory and immunosuppressive effects, and its effectiveness in inflammatory diseases, such as rheumatoid arthritis, has been demonstrated. However, whether SH has a therapeutic effect on dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) in mice and its mechanism of action have not been clarified. This study aimed to investigate the therapeutic effects and mechanism of action of SH on UC.

METHODS

Twenty-four mice were randomly divided into control, model, SH low-dose (SH-L, 20mg/kg), and SH high-dose (SH-H, 60mg/kg) groups with six mice in each group. Disease activity index (DAI), colonic mucosal damage index, and colonic histopathology scores were calculated. The expression levels of related proteins, genes, and downstream inflammatory factors in the Toll-like receptor 2/NF-κB (TLR2/NF-κB) signaling pathway were quantified.

RESULTS

SH inhibited weight loss, decreased DAI and histopathological scores, decreased the expression levels of TLR2, MyD88, P-P65, P65 proteins, and TLR2 genes, and also suppressed the expression of inflammatory factors TNF-α, IL-1 β, and IL-6 in the peripheral blood of mice.

CONCLUSION

The therapeutic effect of SH on DSS-induced UC in mice may be related to the inhibition of the TLR2/NF-κB signaling pathway.

Dual regulation of osteosarcoma hypoxia microenvironment by a bioinspired oxygen nanogenerator for precise single-laser synergistic photodynamic/photothermal/induced antitumor immunity therapy

The hypoxic tumor microenvironment (TME) of osteosarcoma (OS) is the Achilles' heel of oxygen-dependent photodynamic therapy (PDT), and tremendous challenges are confronted to reverse the hypoxia. Herein, we proposed a "reducing expenditure of O2 and broadening sources" dual-strategy and constructed ultrasmall IrO2@BSA-ATO nanogenerators (NGs) for decreasing the O2-consumption and elevating the O2-supply simultaneously. As O2 NGs, the intrinsic catalase (CAT) activity could precisely decompose the overexpressed H2O2 to produce O2 in situ, enabling exogenous O2 infusion. Moreover, the cell respiration inhibitor atovaquone (ATO) would be at the tumor sites, effectively inhibiting cell respiration and elevating oxygen content for endogenous O2 conservation. As a result, IrO2@BSA-ATO NGs systematically increase tumor oxygenation in dual ways and significantly enhance the antitumor efficacy of PDT. Moreover, the extraordinary photothermal conversion efficiency allows the implementation of precise photothermal therapy (PTT) under photoacoustic guidance. Upon a single laser irradiation, this synergistic PDT, PTT, and the following immunosuppression regulation performance of IrO2@BSA-ATO NGs achieved a superior tumor cooperative eradicating capability both in vitro and in vivo. Taken together, this study proposes an innovative dual-strategy to address the serious hypoxia problem, and this microenvironment-regulable IrO2@BSA-ATO NGs as a multifunctional theranostics platform shows great potential for OS therapy.

Animal models of inflammatory bowel disease: category and evaluation indexes

Inflammatory bowel disease (IBD) research often relies on animal models to study the etiology, pathophysiology, and management of IBD. Among these models, rats and mice are frequently employed due to their practicality and genetic manipulability. However, for studies aiming to closely mimic human pathology, non-human primates such as monkeys and dogs offer valuable physiological parallels. Guinea pigs, while less commonly used, present unique advantages for investigating the intricate interplay between neurological and immunological factors in IBD. Additionally, New Zealand rabbits excel in endoscopic biopsy techniques, providing insights into mucosal inflammation and healing processes. Pigs, with their physiological similarities to humans, serve as ideal models for exploring the complex relationships between nutrition, metabolism, and immunity in IBD. Beyond mammals, non-mammalian organisms including zebrafish, Drosophila melanogaster, and nematodes offer specialized insights into specific aspects of IBD pathology, highlighting the diverse array of model systems available for advancing our understanding of this multifaceted disease. In this review, we conduct a thorough analysis of various animal models employed in IBD research, detailing their applications and essential experimental parameters. These include clinical observation, Disease Activity Index score, pathological assessment, intestinal barrier integrity, fibrosis, inflammatory markers, intestinal microbiome, and other critical parameters that are crucial for evaluating modeling success and drug efficacy in experimental mammalian studies. Overall, this review will serve as a valuable resource for researchers in the field of IBD, offering insights into the diverse array of animal models available and their respective applications in studying IBD.

Role of interleukin-6-mediated inflammation in the pathogenesis of inflammatory bowel disease: focus on the available therapeutic approaches and gut microbiome

Inflammatory bowel disease (IBD) is considered a chronic inflammatory and multifactorial disease of the gastrointestinal tract. Crohn's disease (CD) and ulcerative colitis (UC) are two types of chronic IBD. Although there is no accurate information about IBD pathophysiology, evidence suggests that various factors, including the gut microbiome, environment, genetics, lifestyle, and a dysregulated immune system, may increase susceptibility to IBD. Moreover, inflammatory mediators such as interleukin-6 (IL-6) are involved in the immunopathogenesis of IBDs. IL-6 contributes to T helper 17 (Th17) differentiation, mediating further destructive inflammatory responses in CD and UC. Moreover, Th1-mediated responses participate in IBD, and the antiapoptotic IL-6/IL-6 receptor (IL-6R)/signal transducer and activator of transcription 3 (STAT3) signals are responsible for preserving Th1 cells in the site of inflammation. It has been revealed that fecal bacteria isolated from UC-active and UC-remission patients stimulate the hyperproduction of several cytokines, such as IL-6, tumor necrosis factor-α (TNF-α), IL-10, and IL-12. Given the importance of the IL-6/IL-6R axis, various therapeutic options exist for controlling or treating IBD. Therefore, alternative therapeutic approaches such as modulating the gut microbiome could be beneficial due to the failure of the target therapies so far. This review article summarizes IBD immunopathogenesis focusing on the IL-6/IL-6R axis and discusses available therapeutic approaches based on the gut microbiome alteration and IL-6/IL-6R axis targeting and treatment failure.

Protective effect of 7-hydroxyl-1-methylindole-3-acetonitrile on the intestinal mucosal damage response to inflammation in mice with DSS-induced colitis

Ulcerative colitis (UC), a pathological condition of inflammatory bowel disease, is a chronic inflammatory disorder that involves an abnormal immune response and epithelial barrier dysfunction. Although we have previously reported the anti-inflammatory effects of 7-hydroxyl-1-methylindole-3-acetonitrile (7-HMIA), a synthesized analog of arvelexin on macrophages and paw edema, its anti-colitis effect and its mechanism are not known. In this study, colitis was induced in mice model by 4% (w/v) dextran sodium sulfate (DSS) solution in drinking water for 9 days. At the same time, from the first day of administering drinking water containing DSS, the animals were treated with 5-aminosalicylic acid (5-ASA), 75 mg/kg/day, orally) or 7-HMIA (10 or 20 mg/kg/day, intraperitoneally), depending on the experimental group, respectively. The studies were terminated on the tenth day of the experiment. Our data showed that 7-HMIA reduced the disease activity index and spleen/body weight (S/B) ratio, and improved the shortened colon length comparable to the effects of 5-ASA observed in the DSS-exposed mice. 7-HMIA, like 5-ASA, inhibited the histological damage, such as a thickened colonic muscle layer and shortened crypt length in the colon of the mice with DSS-induced colitis. 7-HMIA restored the tight junction-related proteins (occludin, claudin-1, and claudin-2) and epithelial-mesenchymal transition-mediated proteins (E-cadherin, N-cadherin, and vimentin) in the colon tissue of mice with DSS-induced colitis. Additionally, 7-HMIA (20 mg/kg/day) showed the inhibitory effects similar to that of 5-ASA on the myeloperoxidase activity, interleukin (IL)-6 production, and expression levels of inducible nitric oxide synthase (iNOS), and even showed greater inhibition of IL-1β production in the DSS-induced mice. Furthermore, the DSS-induced activation of nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3) were effectively suppressed by 7-HMIA treatment like the effects of 5-ASA. Overall, our findings revealed that 7-HMIA decreased the severity of colitis by protecting the inflamed mucosal barrier by interfering with NF-κB and STAT3 activation.

Possible Future Avenues for Rheumatoid Arthritis Therapeutics: Hippo Pathway

Rheumatoid arthritis (RA) is a persistent systemic autoimmune disease with the hallmarks of swelling of the joint, joint tenderness, and progressive joint destruction, which may cause synovial inflammation and pannus as a basic pathological change, resulting in joint malformations and serious disorders. At present, the precise etiology and mechanism of pathogenesis of RA are unknown. The imbalance of immune homeostasis is the origin of RA. Hippo pathway is widely expressed in a range of cell lineages and plays a fundamental role in maintaining the immune steady state and may be involved in the pathogenic mechanism of RA. This study reviews the progress of Hippo pathway and its main members in the pathogenesis of RA from three aspects: regulating the maintenance of autoimmune homeostasis, promoting the pathogenicity of synovial fibroblasts and regulating the differentiation of osteoclasts. The study also presents a new way to recognize the pathogenesis of rheumatoid arthritis, which is favorable for finding a new way for treating the rheumatoid arthritis.

Pretreatment with IPA ameliorates colitis in mice: Colon transcriptome and fecal 16S amplicon profiling

3-Indolepropionic acid (IPA) is a tryptophan metabolite that has anti-inflammatory properties. The present study try to investigate the phylactic effects of IPA on dextran sodium sulfate (DSS)-induced colitis mice. The results showed that IPA pretreatment ameliorated the DSS-induced decrease in growth performance, and intestinal damage and enhanced immunity in mice. RNA-seq analysis of mouse colon samples revealed that the differentially expressed genes (DEGs) were mainly enriched in immune-related pathways. 16S rRNA sequencing showed that IPA pretreatment ameliorated DSS-induced colonic microbiota dysbiosis. Moreover, the expression levels of gut immune genes were positively correlated with the relative abundance of several probiotics, such as Alloprevotella and Catenibacterium. In conclusion, IPA alleviates DSS-induced acute colitis in mice by regulating inflammatory cytokines, balancing the colonic microbiota and modulating the expression of genes related to inflammation, which would also provide a theoretical basis for IPA as a strategy to improve intestinal health.