Cerebroside D, a glycoceramide compound, improves experimental colitis in mice with multiple targets against activated T lymphocytes

Carbon monoxide produced by HO-1 upregulation is the main factor behind the abnormal motility seen in experimental ulcerative colitis in mice

The colonic motility is altered in patients with ulcerative colitis (UC), but the mechanism is not clear. Carbon monoxide (CO) is the molecule regulating the resting membrane potential (RMP) gradient across colonic smooth muscle wall. Changes in RMP will affect the contractility of smooth muscle. In this study, we investigated the altered colonic motility in dextran sodium sulfate-induced UC mice and the role of CO. The results showed that in the UC group, the frequency of spontaneous colonic contractions was increased while the AUC was decreased compared with the control group. HO-1-, but not HO-2-, positive cells were increased in the colonic smooth muscle wall of the UC group. These HO-1-positive cells were mainly in the myenteric plexus and PGP9.5 positive, suggesting neuronal overproduction of CO. The RMP of circular smooth muscle cells (SMCs) in the colon of UC group was hyperpolarized compared with that of control group. In control group, application of CORM-3, a CO donor, altered colonic spontaneous contractions by increasing their frequency and decreasing amplitude. In the UC group, ZnPPIX, a HO-1 inhibitor, reduced the frequency and increased the amplitude. CORM-3 hyperpolarized the RMP of colonic SMCs and abolished its gradient in the control group, while ZnPPIX depolarized the RMP of colonic SMCs and restored its gradient in the UC group. CO produced by HO-1 upregulation is the main factor behind the altered colonic motility seen in UC mice. CO is a potential candidate as a therapeutic target for patients with UC who suffer from abnormal colonic motility.NEW & NOTEWORTHY Carbon monoxide (CO) produced by HO-1 upregulation in myenteric plexus is the main factor that abolishes the RMP gradient across colonic muscle wall causing the altered colonic motility seen in experimental ulcerative colitis (UC) mice. CO is a potential candidate as a therapeutic target for patients with UC who suffer from abnormal colonic motility.

The Interaction between Mushroom Polysaccharides and Gut Microbiota and Their Effect on Human Health: A Review

Mushroom polysaccharides are a kind of biological macromolecule extracted from the fruiting body, mycelium or fermentation liquid of edible fungi. In recent years, the research on mushroom polysaccharides for alleviating metabolic diseases, inflammatory bowel diseases, cancers and other symptoms by changing the intestinal microenvironment has been increasing. Mushroom polysaccharides could promote human health by regulating gut microbiota, increasing the production of short-chain fatty acids, improving intestinal mucosal barrier, regulating lipid metabolism and activating specific signaling pathways. Notably, these biological activities are closely related to the molecular weight, monosaccharide composition and type of the glycosidic bond of mushroom polysaccharide. This review aims to summarize the latest studies: (1) Regulatory effects of mushroom polysaccharides on gut microbiota; (2) The effect of mushroom polysaccharide structure on gut microbiota; (3) Metabolism of mushroom polysaccharides by gut microbiota; and (4) Effects of mushroom polysaccharides on gut microbe-mediated diseases. It provides a theoretical basis for further exploring the mechanism of mushroom polysaccharides for regulating gut microbiota and gives a reference for developing and utilizing mushroom polysaccharides as promising prebiotics in the future.

Meisoindigo attenuates dextran sulfate sodium-induced experimental colitis via its inhibition of TAK1 in macrophages

At present, inflammatory bowel disease (IBD) seriously threatens human health, and its treatment is a huge challenge for people. In our studies, we found that meisoindigo, a derivative of indirubin, significantly ameliorated dextran sulfate sodium (DSS)-induced experimental colitis in mice. Meisoindigo treatment markedly elevated the level of glutathione, while suppressed the activities of alkaline phosphatase and myeloperoxidase in colonic tissues. Moreover, the mRNA expression of vascular cell adhesion molecule 1, intercellular adhesion molecule 1, cyclooxygenase-2 which are important colitis-related molecules and the levels of the inflammatory cytokines interleukin (IL)-18, IL-1β, IL-6, tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS) were suppressed dose-dependently following treatment with meisoindigo. Immunofluorescence results indicated that meisoindigo inhibited macrophage infiltration and nuclear factor (NF)-κB activation in colons from DSS-treated mice. Therefore, mouse RAW264.7 and human THP-1 cells were treated with lipopolysaccharide (LPS) alone or combined adenosine triphosphate to activate NF-κB pathway in vitro. It was shown that meisoindigo reduced the elevated levels of NO, IL-18, IL-1β and TNF-α after LPS treatment in both cells. In addition, meisoindigo showed inhibitory effects on NF-κB by using a luciferase reporter gene that depends on NF-κB. Through molecular docking, microscale thermophoresis and cellular thermal shift assay. It was further found that meisoindigo targeted transforming growth factor β activated kinase-1 (TAK1), which is an important regulator in the upstream of NF-κB pathway. In conclusion, our findings show that meisoindigo can alleviate IBD effectively at low doses, and negatively regulate proinflammatory responses by inhibiting the activation of TAK1, which provides new ideas for clinical anti-inflammatory therapy.

Molecular Characterization and Anti-inflammatory Activity of Galactosylglycerides and Galactosylceramides from the Microalga Isochrysis galbana

Isochrysis galbana is a marine microalga rich in PUFAs that is widely used as feed in aquaculture and more recently investigated for its potential in food applications and as source of bioactive compounds. In this study, the biomass obtained from cultures of I. galbana has been investigated to determine its content in glycosylglycerides and glycosylceramides. By using NMR, UPLC-MS/MS, and fatty acid profiles, the structures of ten monogalactosyldiacylglycerols (MGDGs 1-10) and nine digalactosyldiacylglycerols (DGDGs 11-19) have been established. Two distinctive features of the galactosylglycerides from I. galbana are the wide presence of highly unsaturated acyl chains derived from stearidonic acid (18:4Δ^{6Z,9Z,12Z,15Z}) and octadecapentaenoic acid (18:5Δ^{3Z,6Z,9Z,12Z,15Z}), as well as the unusual coexistence of αβ-DGDGs and ββ-DGDGs. Three new galactosylceramides, isogalbamides A-C (20-22), have also been isolated and characterized by NMR and MS/MS. These metabolites, which are the first galactosylceramides described from microalgae, derive from unprecedented tetraolefinic sphingoid bases. In anti-inflammatory assays, the MGDG and DGDG mixtures and the isolated DGDGs 11 and 12 showed significant activity as inhibitors of the production of the pro-inflammatory cytokine TNF-α in lipopolysaccharide-stimulated human THP-1 macrophages, while the galactosylceramides showed moderated activity.

Fostering Inflammatory Bowel Disease: Sphingolipid Strategies to Join Forces

Complex sphingolipids are essential structural components of intestinal membranes, providing protection and integrity to the intestinal mucosa and regulating intestinal absorption processes. The role of sphingolipid signaling has been established in numerous cellular events, including intestinal cell survival, growth, differentiation, and apoptosis. A significant body of knowledge demonstrates that intestinal sphingolipids play a crucial role, as such and through their signaling pathways, in immunity and inflammatory disorders. In this review, we report on and discuss the current knowledge on the metabolism, signaling, and functional implications of sphingolipids in inflammatory bowel disease (IBD), focusing on the different aspects of sphingolipid actions on inflammatory responses and on the potential of sphingolipid-targeted molecules as anti-IBD therapeutic agents.

Anti-inflammatory activity on mice of extract of Ganoderma lucidum grown on rice via modulation of MAPK and NF-κB pathways

Ganoderma lucidum is a popular medicinal mushroom with anti-inflammatory potential. In the present study, the aim was to determine the anti-inflammatory effect and mode of action of G. lucidum grown on germinated brown rice (GLBR) in a mouse model of colitis. It was shown that GLBR suppressed the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-stimulated macrophages and decreased the expression of COX-2, TNF-α, iNOS, IL-1β, IL-6, and IL-10 mRNAs. GLBR also inhibited activation of p38, ERK, JNK, MAPKs, and nuclear factor kappa-B (NF-κB). In a mouse model of colitis, colonic mucosal injury was evaluated using macroscopic, biochemical, and histopathological testing. Disease activity index (DAI), macroscopic score, and histological score significantly decreased upon GLBR treatment. Moreover, immunofluorescence studies indicated that DSS activates nuclear translocation of NF-κB in colon tissue, which is attenuated by GLBR extract. These findings suggest that GLBR is protective against colitis via inhibition of MAPK phosphorylation and NF-κB activation.

Suppression of NF-κB signaling and NLRP3 inflammasome activation in macrophages is responsible for the amelioration of experimental murine colitis by the natural compound fraxinellone

Inflammatory bowel disease (IBD) affects millions of people worldwide. Although the etiology of this disease is uncertain, accumulating evidence indicates a key role for the activated mucosal immune system. In the present study, we examined the effects of the natural compound fraxinellone on dextran sulfate sodium (DSS)-induced colitis in mice, an animal model that mimics IBD. Treatment with fraxinellone significantly reduced weight loss and diarrhea in mice and alleviated the macroscopic and microscopic signs of the disease. In addition, the activities of myeloperoxidase and alkaline phosphatase were markedly suppressed, while the levels of glutathione were increased in colitis tissues following fraxinellone treatment. This compound also decreased the colonic levels of interleukin (IL)-1β, IL-6, IL-18 and tumor necrosis factor (TNF)-α in a concentration-dependent manner. These effects of fraxinellone in mice with experimental colitis were attributed to its inhibition of CD11b(+) macrophage infiltration. The mRNA levels of macrophage-related molecules in the colon, including intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2), were also markedly inhibited following fraxinellone treatment. The results from in vitro assays showed that fraxinellone significantly reduced lipopolysaccharide (LPS)-induced production of nitric oxide (NO), IL-1β and IL-18 as well as the activity of iNOS in both THP-1 cells and mouse primary peritoneal macrophages. The mechanisms responsible for these effects were attributed to the inhibitory role of fraxinellone in NF-κB signaling and NLRP3 inflammasome activation. Overall, our results support fraxinellone as a novel drug candidate in the treatment of colonic inflammation.

Tupistra chinensis extract attenuates murine fulminant hepatitis with multiple targets against activated T lymphocytes

OBJECTIVES

The extract of Tupistra chinensis (TCE) is traditionally used for the treatment of inflammatory diseases in southwestern China for hundreds of years. The present study was designed to investigate the effects of the TCE against experimental hepatitis and to illustrate its potential mechanisms.

METHODS

Effects of TCE were investigated on Con A-induced hepatitis. Profiles of multiple cytokines were measured with biometric immuno-sandwich ELISA. Proliferation, activation and apoptosis of T lymphocytes were evaluated using Western blot, MTT analysis and flow cytometry.

KEY FINDINGS

TCE significantly inhibited levels of serum transaminases and lactic dehydrogenase in mice with Con A-induced hepatitis, accompanied with marked alleviation of the liver microscopic appearances. Moreover, it decreased levels of inflammatory cytokines in a concentration-dependent manner both in vivo and in vitro. It also suppressed mitogen-activated protein kinases and NF-κB-signalling in liver. These effects of TCE are attributed to its inhibition on activated T cells but not to hepatocytes protection. Flow cytometry and immunoblot assay data showed its effects on STAT1/NF-κB-signalling blockage and apoptosis induction in activated T cells.

CONCLUSION

Our findings illustrate the significant potential of TCE as a novel approach for treatment of T cell-mediated inflammatory diseases.

A novel benzo[d]imidazole derivate prevents the development of dextran sulfate sodium-induced murine experimental colitis via inhibition of NLRP3 inflammasome

NLRP3 inflammasome has been reported to be associated with various kinds of immunological diseases including colitis. However, there are few drug candidates targeting inflammasomes for the treatment of colitis. In the present study, we aimed at examining the effect of 1-ethyl-5-methyl-2-phenyl-1H-benzo[d]imidazole, a synthetic small molecular compound also named Fc11a-2, for the treatment of dextran sulfate sodium (DSS)-induced experimental colitis in mice via targeting NLRP3 inflammasome. Treatment with Fc11a-2 dose-dependently attenuated the loss of body weight and shortening of colon length induced by DSS. In addition, the disease activity index, histopathologic scores and myeloperoxidase activity were also significantly reduced by Fc11a-2 treatment. Moreover, protein and mRNA levels of DSS-induced proinflammatory cytokines in colon, including TNF-α, IL-1β, IL-18, IL-17A and IFN-γ, were markedly suppressed by Fc11a-2. Furthermore, a decreased CD11c⁺ macrophage infiltration in colons and inactivation of caspase-1 in peritoneal macrophages were detected in Fc11a-2-treated mice. The mechanism of action of Fc11a-2 was related to the inhibition of the cleavage of pro-caspase-1, pro-IL-1β and pro-IL-18 which in turn suppressed the activation of NLRP3 inflammasome. Taken together, our results demonstrate the ability of Fc11a-2 to inhibit NLRP3 inflammasome activation and its potential use in the treatment of inflammatory bowel diseases.

Inhibition of Th1/Th17 responses via suppression of STAT1 and STAT3 activation contributes to the amelioration of murine experimental colitis by a natural flavonoid glucoside icariin

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder in the intestine which involves overproduction of pro-inflammatory cytokines and excessive functions of inflammatory cells. However, current treatments for IBD may have potential adverse effects including steroid dependence, infections and lymphoma. Therefore new therapies or drug candidates for the treatment of IBD are desperately needed. In the present study we found that icariin, a major bioactive compound from plants in Epimedium family, exerted protective effect on intestinal inflammation in mice induced by dextran sulfate sodium. Oral administration of icariin significantly attenuated the disease progression and alleviated the pathological changes of colitis. It also inhibited the production of pro-inflammatory cytokines and expression of p-p65, p-STAT1 and p-STAT3 in colon tissues. Further study showed that icariin dose-dependently inhibited the proliferation and activation of T lymphocytes, and suppressed pro-inflammatory cytokine levels of activated T cells. Moreover, icariin treatment inhibited the phosphorylations of STAT1 and STAT3 in CD4(+) T cells, which were the crucial transcription factors for Th1 and Th17 respectively. Taken together, these results indicate that icariin is a potential therapeutic agent for IBD.