Knockdown of ghrelin‐O‐acyltransferase attenuates colitis through the modulation of inflammatory factors and tight junction proteins in the intestinal epithelium

Ghrelin‐O‐acyltransferase (GOAT) is a membrane‐bound enzyme that attaches eight‐carbon octanoate to a serine residue in ghrelin and thereby acylates inactive ghrelin to produce active ghrelin. In this study, we investigated the function of GOAT in the intestinal mucosal barrier. The intestinal mucosal barrier prevents harmful substances such as bacteria and endotoxin from entering the other tissues, organs, and blood circulation through the intestinal mucosa. Here, we established 5% dextran sodium sulfate (DSS)‐induced colitis in mice and found that the body weight and colon weight were significantly decreased in these mice. Furthermore, increased inflammation and apoptosis were observed in the tissues of DSS‐induced colitis mice, with increased expression of tumor necrosis factor‐α, interleukin‐6, phosphorylation of nuclear factor kappa B‐p65 (p‐NF‐κB‐p65), and cleaved caspase‐3, and decreased expression of tight junction (TJ) proteins such as zonula occluden‐1 and occludin. The knockdown of GOAT significantly attenuated colitis‐induced inflammation responses and apoptosis, while GOAT overexpression significantly enhanced the induction of colitis. These results suggest that knockdown of GOAT may attenuate colitis‐induced inflammation, ulcers, and fecal occult blood by decreasing the intestinal mucosal permeability via the modulation of inflammatory factors and TJ proteins.     

Metformin attenuates the effect of Staphylococcus aureus on airway tight junctions by increasing PKCζ‐mediated phosphorylation of occludin

Airway epithelial tight junction (TJ) proteins form a resistive barrier to the external environment, however, during respiratory bacterial infection TJs become disrupted compromising barrier function. This promotes glucose flux/accumulation into the lumen which acts as a nutrient source for bacterial growth. Metformin used for the treatment of diabetes increases transepithelial resistance (TEER) and partially prevents the effect of bacteria but the mechanisms of action are unclear. We investigated the effect of metformin and Staphylococcus aureus on TJ proteins, zonula occludins (ZO)‐1 and occludin in human airway epithelial cells (H441). We also explored the role of AMP‐activated protein kinase (AMPK) and PKCζ in metformin‐induced effects. Pretreatment with metformin prevented the S. aureus‐induced changes in ZO‐1 and occludin. Metformin also promoted increased abundance of full length over smaller cleaved occludin proteins. The nonspecific PKC inhibitor staurosporine reduced TEER but did not prevent the effect of metformin indicating that the pathway may involve atypical PKC isoforms. Investigation of TJ reassembly after calcium depletion showed that metformin increased TEER more rapidly and promoted the abundance and localization of occludin at the TJ. These effects were inhibited by the AMPK inhibitor, compound C and the PKCζ pseudosubstrate inhibitor (PSI). Metformin increased phosphorylation of occludin and acetyl‐coA‐carboxylase but only the former was prevented by PSI. This study demonstrates that metformin improves TJ barrier function by promoting the abundance and assembly of full length occludin at the TJ and that this process involves phosphorylation of the protein via an AMPK‐PKCζ pathway.     

Mutual regulation between butyrate and hypoxia‐inducible factor‐1α in epithelial cell promotes expression of tight junction proteins

Inflammatory bowel disease is a kind of multi‐aetiological chronic disease that is driven by multidimensional factors. Hypoxia‐inducible factor‐1α (HIF‐1α) plays an important role in anti‐inflammatory and cellular responses to hypoxia. Previous studies have found that B or T‐cell‐specific HIF‐1α knock out mice exhibit severe colonic inflammation. However, we know very little about other functions of HIF‐1α in intestinal epithelial cells (IECs). In our study, HIF‐1α^ΔIEC mice were used to study the function of HIF‐1α in IECs. HIF‐1α was knocked down in Caco‐2 cells by transfection with a small interfering (si) RNA. Immunohistochemical staining and western blotting were used to detect the expression of zonula occluden‐1 (ZO‐1) and Occludin. The content of colon was harvested for high‐performance liquid chromatography analysis to examine the levels of butyrate in the gut. Our research found that HIF‐1α played a protective role in dextran sulphate sodium‐induced colitis, which was partly due to its regulation of tight junction (TJ) protein expression. Further study revealed that HIF‐1α mediated TJ proteins levels by moderating the content of butyrate. Moreover, we found that butyrate regulated TJ protein expression, which is dependent on HIF‐1α. These results indicated that there is a mutual regulatory mechanism between butyrate and HIF‐1α, which has an important role in the maintenance of barrier function of the gastrointestinal tract.     

Wogonoside alleviates colitis by improving intestinal epithelial barrier function via the MLCK/pMLC2 pathway

BackgroundIntestinal epithelial barrier dysfunction, which involves myosin light chain kinase (MLCK) activation, contributes to the occurrence and progression of inflammation in inflammatory bowel disease (IBD). Wogonoside helps maintain intestinal homeostasis in mice with dextran sulfate sodium (DSS)-induced colitis, but it is unclear whether it modulates intestinal barrier function.PurposeHere, we demonstrate that wogonoside protects against intestinal barrier dysfunction in colitis via the MLCK/pMLC2 pathway both in vivo and in vitro.MethodsCaco-2 cell monolayers treated with the proinflammatory cytokine TNF-α showed barrier dysfunction and were assessed in the absence and presence of wogonoside for various physiological, morphological, and biochemical parameters. Colitis was induced by 3% DSS in mice, which were used as an animal model to explore the pharmacodynamics of wogonoside. We detected MLCK/pMLC2 pathway proteins via western blot analysis, assessed the cytokines IL-13 and IFN-γ via ELISA, tested bacterial translocation via fluorescence in situ hybridization (FISH) and a proper sampling of secondary lymphoid organs for bacterial culture. In addition, the docking affinity of wogonoside and MLCK was observed with DS2.5 software.ResultsWogonoside alleviated the disruption of transepithelial electrical resistance (TER) in TNF-α exposured Caco-2 cell; FITC-dextran hyperpermeability; loss of the tight junction (TJ) proteins occludin, ZO-1 and claudin-1 in Caco-2 cell monolayers; and bacterial translocation in colitic mice. Moreover, wogonoside reduced the levels of the proinflammatory cytokines IL-13 and IFN-γ to maintain intestinal immune homeostasis. Transmission electron microscopy (TEM) confirmed that wogonoside ameliorated the destruction of intestinal epithelial TJs. Wogonoside not only inhibited the cytoskeletal F-actin rearrangement induced by TNF-α, stabilized the cytoskeletal structure, suppressed MLCK protein expression, and reduced MLC2 phosphorylation. In addition, the results of molecular docking analysis showed that wogonoside had a high affinity for MLCK and formed hydrogen bonds with the amino acid residue LYS261 and π bonds with LYS229.ConclusionCollectively, our study indicates that wogonoside alleviates colitis by protecting against intestinal barrier dysfunction, and the potential mechanism may involve regulation of TJs via the MLCK/pMLC2 signaling pathway. Meanwhile, our study also explains the success of S. baicalensis in the treatment of ulcerative colitis (UC).     

Attenuation by dietary taurine of dextran sulfate sodium-induced colitis in mice and of THP-1-induced damage to intestinal Caco-2 cell monolayers

The effects of dietary taurine on the experimental colitis induced by dextran sulfate sodium (DSS) in mice were evaluated. C57BL/6 female mice were given 3% DSS in drinking water for 5 d to induce acute colitis. Taurine at 2% was added to the drinking water 5 d before and during the DSS-treatment to investigate its preventive effect. Taurine supplementation significantly attenuated the weight decrease, diarrhea severity, colon shortening, and the increase in the colonic tissue myeloperoxidase activity induced by DSS. Taurine also significantly inhibited the increase in the expression of a pro-inflammatory chemokine, macrophage inflammatory protein 2 (MIP-2), but not of interleukin (IL)-1beta or tumor necrosis factor (TNF)-alpha mRNA. Furthermore, taurine significantly protected the intestinal Caco-2 cell monolayers from the damage by macrophage-like THP-1 cells in an in vitro coculture system. These results suggest that taurine prevented DSS-induced colitis partly in association with (1) its inhibitory effects on the secretion of MIP-2 from the intestinal epithelial cells and on the infiltration of such inflammatory cells as neutrophils and (2) its cytoprotective functions on the epithelial barrier from the direct toxicity of DSS and from the inflammatory cell-induced injury.     

Nrf2 attenuates inflammatory response in COPD/emphysema: Crosstalk with Wnt3a/β‐catenin and AMPK pathways

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation and abnormal inflammatory response. Wnt/β‐catenin and AMP‐activated protein kinase (AMPK) have been shown to modulate lung inflammatory responses and injury. However, it remains elusive whether Wnt/β‐catenin and AMPK modulate nuclear factor erythroid‐2 related factor‐2 (Nrf2)‐mediated protective responses during the development of emphysema. Here we showed that treatment with a Wnt pathway activator (LiCl) reduced elastase‐induced airspace enlargement and cigarette smoke extract (CSE)‐induced lung inflammatory responses in WT mice, which was associated with increased activation of Nrf2 pathway. Interestingly, these effects of LiCl were not observed in Nrf2^?/? mice exposed to elastase. In normal human bronchial epithelial (NHBE) cells, Wnt3a overexpression up‐regulated, whereas Wnt3a knockdown further down‐regulated the levels of Nrf2 and its target proteins heme oxygenase‐1 (HO‐1) and NAD(P)H: quinone oxidoreductase 1 (NQO1) by CSE treatment. In contrast, Nrf2 deficiency did not have any effects on Wnt/β‐catenin pathway in mouse lungs and NHBE cells. Both elastase and CSE exposures reduced AMPK phosphorylation. A specific AMPK activator metformin increased Wnt3a, β‐catenin, Nrf2 phosphorylation and activation but reduced the levels of IL‐6 and IL‐8 in NHBE cells and mouse lungs exposed to CSE. Furthermore, Nrf2 deficiency abolished the protection of metformin against CSE‐induced increase in IL‐6 and IL‐8 in NHBE cells. In conclusion, Nrf2 mediates the protective effects of both Wnt3a/β‐catenin and AMPK on lung inflammatory responses during the development of COPD/emphysema. These findings provide potential therapeutic targets for the intervention of COPD/emphysema.     

Mogrol,an aglycone of mogrosides,attenuates ulcerative colitis by promoting AMPK activation

BackgroundUlcerative colitis (UC) is a non-specific chronic inflammatory disease. The incidence of UC in China has been increasing in recent years. Mogrol is an aglycone of mogrosides. Studies have shown that mogrosides have anti-oxygenation, anti-inflammatory, and laxative effects as well as other biological activities.PurposeTo investigate the beneficial effects of mogrol on UC and identify its underlying mechanisms.Study designWe used the dextran sodium sulphate (DSS)-induced UC model in mice, TNF-α-damaged NCM460 colonic epithelial cells, macrophage cells THP-M stimulated with lipopolysaccharide (LPS) / adenosine triphosphate (ATP) and compound C (an AMPK inhibitor) to confirm the key role of AMPK (AMP-activated protein kinase) activation.MethodsHistological evaluation, immunohistochemical staining, Western blot analysis, immunofluorescence assay and quantitative real time-PCR were used in the study.ResultsOral administration of mogrol (5 mg/kg/daily) in vivo significantly attenuated pathological colonic damage, inhibited inflammatory infiltration and improved the abnormal expression of NLRP3 inflammasome in colonic mucosa via the AMPK and NF-κB signaling pathways. In vitro, mogrol protected against intestinal epithelial barrier dysfunction by activating AMPK in TNF-α-treated NCM460 cells and inhibited the production of inflammatory mediator in LPS-stimulated THP-M cells. Furthermore, mogrol's effects were reversed by compound C intervention in DSS-induced UC model.ConclusionMogrol exerts protective effects in experimental UC and inhibits production of inflammatory mediators through activation of AMPK-mediated signaling pathways.     

Metformin sensitizes insulin signaling through AMPK-mediated PTEN down-regulation in preadipocyte 3T3-L1 cells

Insulin resistance is the primary cause responsible for type 2 diabetes. Phosphatase and tensin homolog (PTEN) plays a negative role in insulin signaling and its inhibition improves insulin sensitivity. Metformin is a widely used insulin-sensitizing drug; however, the mechanism by which metformin acts is poorly understood. To gain insight into the role of PTEN, we examined the effect of metformin on PTEN expression. Metformin suppressed the expression of PTEN in an AMP-activated protein kinase (AMPK)-dependent manner in preadipocyte 3T3-L1 cells. Knock-down of PTEN potentiated the increase in insulin-mediated phosphorylation of Akt/ERK. Metformin also increased the phosphorylation of c-Jun N-terminal kinase (JNK)-c-Jun and mammalian target of rapamycin (mTOR)-p70S6 kinase pathways. Both pharmacologic inhibition and knock-down of AMPK blocked metformin-induced phosphorylation of JNK and mTOR. Knock-down of AMPK recovered the metformin-induced PTEN down-regulation, suggesting the involvement of AMPK in PTEN regulation. PTEN promoter activity was suppressed by metformin and inhibition of mTOR and JNK by pharmacologic inhibitors blocked metformin-induced PTEN promoter activity suppression. These findings provide evidence for a novel role of AMPK on PTEN expression and thus suggest a possible mechanism by which metformin may contribute to its beneficial effects on insulin signaling.     

Picroside III,an Active Ingredient of Picrorhiza scrophulariiflora,Ameliorates Experimental Colitis by Protecting Intestinal Barrier Integrity

This study aims to explore the protective effects of Picroside III, an active ingredient of Picrorhiza scrophulariiflora, on the intestinal epithelial barrier in tumor necrosis factor-α (TNF-α) induced Caco-2 cells and dextran sulfate sodium (DSS) induced colitis in mice. Results show that Picroside III significantly alleviated clinical signs of colitis including body weight loss, disease activity index increase, colon shortening, and colon tissue damage. It also increased claudin-3, ZO-1 and occludin expressions and decreased claudin-2 expression in the colon tissues of mice with colitis. In vitro, Picroside III also significantly promoted wound healing, decreased the permeability of cell monolayer, upregulated the expressions of claudin-3, ZO-1 and occludin and downregulated the expression of claudin-2 in TNF-α treated Caco-2 cells. Mechanism studies show that Picroside III significantly promoted AMP-activated protein kinase (AMPK) phosphorylation in vitro and in vivo, and blockade with AMPK could significantly attenuate the upregulation of Picroside III in ZO-1 and occludin expressions and the downregulation of claudin-2 expression in TNF-α treated Caco-2 cells. In conclusion, this study demonstrates that Picroside III attenuated DSS-induced colitis by promoting colonic mucosal wound healing and epithelial barrier function recovery via the activation of AMPK.     

Crosstalk between AMPK activation and angiotensin II‐induced hypertrophy in cardiomyocytes: the role of mitochondria

AMP‐kinase (AMPK) activation reduces cardiac hypertrophy, although underlying molecular mechanisms remain unclear. In this study, we elucidated the anti‐hypertrophic action of metformin, specifically, the role of the AMPK/eNOS/p53 pathway. H9c2 rat cardiomyocytes were treated with angiotensin II (AngII) for 24 hrs in the presence or absence of metformin (AMPK agonist), losartan [AngII type 1 receptor (AT1R) blocker], Nω‐nitro‐L‐arginine methyl ester (L‐NAME, pan‐NOS inhibitor), splitomicin (SIRT1 inhibitor) or pifithrin‐α (p53 inhibitor). Results showed that treatment with metformin significantly attenuated AngII‐induced cell hypertrophy and death. Metformin attenuated AngII‐induced activation (cleavage) of caspase 3, Bcl‐2 down‐regulation and p53 up‐regulation. It also reduced AngII‐induced AT1R up‐regulation by 30% (P < 0.05) and enhanced AMPK phosphorylation by 99% (P < 0.01) and P‐eNOS levels by 3.3‐fold (P < 0.01). Likewise, losartan reduced AT1R up‐regulation and enhanced AMPK phosphorylation by 54% (P < 0.05). The AMPK inhibitor, compound C, prevented AT1R down‐regulation, indicating that metformin mediated its effects via AMPK activation. Beneficial effects of metformin and losartan converged on mitochondria that demonstrated high membrane potential (Δψ_m) and low permeability transition pore opening. Thus, this study demonstrates that the anti‐hypertrophic effects of metformin are associated with AMPK‐induced AT1R down‐regulation and prevention of mitochondrial dysfunction through the SIRT1/eNOS/p53 pathway.     

Metformin reduces TRPC6 expression through AMPK activation and modulates cytoskeleton dynamics in podocytes under diabetic conditions

Podocytes have foot processes that comprise an important cellular layer of the glomerular barrier involved in regulating glomerular permeability. The disturbance of podocyte function plays a central role in the development of proteinuria in diabetic nephropathy. AMP-activated protein kinase (AMPK), a key regulator of glucose and fatty acid metabolism, plays a major role in obesity and type 2 diabetes. Accumulating evidence suggests that TRPC6 channels are crucial mediators of calcium transport in podocytes, and these channels are involved in disturbing the glomerular filtration barrier in diabetes.Metformin is an anti-diabetic drug widely used for treating patients with type 2 diabetes. Recent studies have suggested that the therapeutic effect of metformin might be mediated by AMPK. The precise function of metformin on cellular function and intracellular signaling in podocytes under diabetic conditions is not fully understood.In this study, we demonstrated that metformin normalized TRPC6 expression via AMPKα1 activation in podocytes exposed to high glucose concentrations. A quantitative analysis showed that metformin increased the colocalization of TRPC6 and AMPKα1 subunits from 42% to 61% in standard glucose (SG) medium and from 29% to 52% in high glucose (HG) medium. AMPK activation was also necessary for maintaining appropriate levels of Rho-family small GTPase activity in HG conditions. Moreover, metformin through AMPK activation remodeled cytoskeleton dynamics, and consequently, reduced filtration barrier permeability in diabetic conditions.     

Therapeutic effects of lentinan on inflammatory bowel disease and colitis‐associated cancer

In this study, we investigated the therapeutic potential of lentinan in mouse models of inflammatory bowel disease (IBD) and colitis‐associated cancer (CAC). Lentinan decreased the disease activity index and macroscopic and microscopic colon tissue damage in dextran sulphate sodium (DSS)‐induced or TNBS‐induced models of colitis. High‐dose lentinan was more effective than salicylazosulfapyridine in the mouse models of colitis. Lentinan decreased the number of tumours, inflammatory cell infiltration, atypical hyperplasia and nuclear atypia in azoxymethane/DSS‐induced CAC model. It also decreased the expression of pro‐inflammatory cytokines, such as IL‐13 and CD30L, in IBD and CAC model mice possibly by inhibiting Toll‐like receptor 4 (TLR4)/NF‐κB signalling and the expression of colon cancer markers, such as carcinoembryonic antigen, cytokeratin 8, CK18 and p53, in CAC model mice. In addition, lentinan restored the intestinal bacterial microbiotal community structure in IBD model mice. Thus, it shows therapeutic potential in IBD and CAC model mice possibly by inhibiting TLR4/NF‐κB signalling‐mediated inflammatory responses and disruption of the intestinal microbiotal structure.     

Berberine suppresses neuroinflammatory responses through AMP‐activated protein kinase activation in BV‐2 microglia

The AMPK cascade is a sensor of cellular energy change, which monitors the AMP/ATP ratio to regulate cellular metabolism by restoring ATP levels, but its regulation of neuroinflammation mechanism remains unclear. Berberine, one of the major constituents of Chinese herb Rhizoma coptidis, has been shown to improve several metabolic disorders, such as obesity and type II diabetes. However, the effect of berberine on neuroinflammatory responses in microglia are poorly understood. This study shows that berberine represses proinflammatory responses through AMP‐activated protein kinase (AMPK) activation in BV‐2 microglia. Our findings also demonstrate that berberine significantly down‐regulates LPS‐ or interferon (IFN)‐γ‐induced nitric oxide synthase (iNOS) and cyclo‐oxygenase‐2 (COX‐2) expression in BV‐2 microglia cells. Berberine also inhibited LPS‐ or IFN‐γ‐induced nitric oxide production. In addition, berberine effectively inhibited proinflammatory cytokines such as TNF‐α, IL‐1β, and IL‐6 expression. On the other hand, upon various inflammatory stimulus including LPS and IFN‐γ, berberine suppressed the phosphorylated of ERK but not p38 and JNK in BV‐2 microglia. AMPK activation is catalyzed by upstream kinases such as LKB1 and Ca2+/calmodulin‐dependent protein kinase kinase‐II (CaMKK II). Moreover, berberine induced LKB1 (Ser428), CaMKII (Thr286), and AMPK (Thr172) phosphorylation, but not AMPK (Ser485). Furthermore, the inhibitory effect of berberine on iNOS and COX‐2 expression was abolished by AMPK inhibition via Compound C, an AMPK inhibitor. Berberine‐suppressed ERK phosphorylation was also reversed by Compound C treatment. Our data demonstrate that berberine significantly induces AMPK signaling pathways activation, which is involved in anti‐neuroinflammation. J. Cell. Biochem. 110: 697–705, 2010. © 2010 Wiley‐Liss, Inc.     

MicroRNA‐21 regulates intestinal epithelial tight junction permeability

Increased tight junction (TJ) barrier permeability, induced by tumour necrosis factor (TNF)‐α, may lead to the defects in TJ barrier and subsequent development of inflammation. Recent evidence suggests that miR‐21 is implicated in inflammatory diseases. However, the physiological role of miR‐21 in intestinal permeability remains elusive. This study aimed to explore the role of miR‐21 in intestinal epithelial tight junction permeability. The filter‐grown Caco‐2 monolayers model system was established to mimic intestinal barrier defect. The tight junction proteins were detected by immunofluorescence and western blot analysis. The expression of miR‐21 was assessed by real‐time polymerase chain reaction (PCR). We found that the expression of miR‐21 was increased significantly in TNF‐α induced intestinal TJ barrier defect model. miR‐21 overexpression significantly enhanced while miR‐21 knockdown significantly decreased intestinal permeability. In addition, miR‐21 overexpression significantly increased while miR‐21 knockdown significantly decreased the levels of interleukin‐6, interleukin‐8 and prostaglandin E2 in cell culture medium. Furthermore, miR‐21 positively regulated Akt phosphorylation and negatively regulated Phosphatase and tensin homolog (PTEN) expression in Caco‐2 cells. Our results suggest that miR‐21 may regulate intestinal epithelial tight junction permeability through PTEN/PI3K/Akt signalling pathway. This promotes the feasibility of targeting miR‐21 in the clinical to preserve the intestinal barrier. Copyright © 2015 John Wiley & Sons, Ltd.     

Epithelial PBLD attenuates intestinal inflammatory response and improves intestinal barrier function by inhibiting NF-κB signaling

Intestinal barrier function defects and dysregulation of intestinal immune responses are two key contributory factors in the pathogenesis of ulcerative colitis (UC). Phenazine biosynthesis-like domain-containing protein (PBLD) was recently identified as a tumor suppressor in gastric cancer, hepatocellular carcinoma, and breast cancer; however, its role in UC remains unclear. Therefore, we analyzed colonic tissue samples from patients with UC and constructed specific intestinal epithelial PBLD-deficient (PBLD^IEC−/−) mice to investigate the role of this protein in UC pathogenesis. We found that epithelial PBLD was decreased in patients with UC and was correlated with levels of tight junction (TJ) and inflammatory proteins. PBLD^IEC−/− mice were more susceptible to dextran sulfate sodium (DSS)- and 2,4,6-trinitrobenzene sulfonic acid-induced colitis compared with wild-type (WT) mice. In DSS-induced colitis, PBLD^IEC−/− mice had impaired intestinal barrier function and greater immune cell infiltration in colonic tissue than WT mice. Furthermore, TJ proteins were markedly reduced in PBLD^IEC−/− mice compared with WT mice with colitis. Nuclear factor (NF)-κB activation was markedly elevated and resulted in higher expression levels of downstream effectors (C–C motif chemokine ligand 20, interleukin [IL]-1β, IL-6, and tumor necrosis factor [TNF]-α) in colonic epithelial cells isolated from PBLD^IEC−/− mice than WT mice with colitis. PBLD overexpression in intestinal epithelial cells (IECs) consistently inhibited TNF-α/interferon-γ-induced intestinal barrier disruption and TNF-α-induced inflammatory responses via the suppression of NF-κB. In addition, IKK inhibition (IKK-16) rescued excessive inflammatory responses induced by TNF-α in PBLD knockdown FHC cells. Co-immunoprecipitation assays showed that PBLD may interact with IKKα and IKKβ, thus inhibiting NF-κB signaling, decreasing inflammatory mediator production, attenuating colonic inflammation, and improving intestinal barrier function. Modulating PBLD expression may provide a novel approach for treatment in patients with UC.Subject terms: Ulcerative colitis, Chronic inflammation     

Zearalenone can relieve dextran sulfate sodium‐induced inflammatory reaction

In this study, we investigated the influence of zearalenone (ZEA) on the dextran sulfate sodium (DSS)‐induced colitis model both in vitro and in vivo. Our results show that the mRNA levels of IL‐1β, IL‐18, NLRP3, ASC, and caspase‐1 in the DSS+ZEA‐treated group are lower than those in either the DSS or ZEA group, and the protein expression trends are similar. Furthermore, colitis, which is characterized by body weight loss, stool consistency, and the presence of bloody feces, was significantly alleviated in the DSS+ZEA group when compared with that in the DSS group. In addition, histological analysis showed that inflammatory cell infiltration and tissue damage of the colon in the DSS+ZEA group were recovered compared with that in the DSS‐treated group. These results suggest that, instead of aggravating DSS‐induced colitis, ZEA relieves the inflammatory reaction in colon tissue, which may be related to its estrogenic activity.     

Spontaneous colitis in IL‐10‐deficient mice was ameliorated via inhibiting glutaminase1

Immunity imbalance and barrier damage in the intestinal mucosa are the main pathogenic factors of Crohn's disease (CD). Bis‐2‐(5‐phenylacetamido‐1,2,4‐thiadiazol‐2‐yl) ethyl sulfide (BPTES) is a glutaminase 1 (Gls1) inhibitor with the dual functions of increasing glutamine levels and immune regulation. In this study, we focused on the role of BPTES in CD‐like enteritis and the possible mechanisms. We found that Gls1 expression was significantly increased in CD intestinal tissue compared with control tissue. Bis‐2‐(5‐phenylacetamido‐1,2,4‐thiadiazol‐2‐yl) ethyl sulfide treatment significantly ameliorated chronic colitis in the IL‐10^?/?, as manifested by decreased disease activity index, body weight change, histological inflammatory degree and inflammatory cytokine expression. Bis‐2‐(5‐phenylacetamido‐1,2,4‐thiadiazol‐2‐yl) ethyl sulfide treatment exerted protective effects on CD that were associated with the maintenance of intestinal barrier integrity and the Th/Treg balance. Bis‐2‐(5‐phenylacetamido‐1,2,4‐thiadiazol‐2‐yl) ethyl sulfide treatment may act in part through TCR‐mediated mammalian target of rapamycin complex 1 (mTORC1) signalling activation. In conclusion, inhibition of Gls1 expression attenuated chronic colitis by maintaining intestinal barrier integrity and the Th/Treg balance, thereby ameliorating CD‐like colitis.     

Sodium salicylate modulates inflammatory responses through AMP‐activated protein kinase activation in LPS‐stimulated THP‐1 cells

Sodium salicylate (NaSal) is a nonsteroidal anti‐inflammatory drug. The putative mechanisms for NaSal's pharmacologic actions include the inhibition of cyclooxygenases, platelet‐derived thromboxane A2, and NF‐κB signaling. Recent studies demonstrated that salicylate could activate AMP‐activated protein kinase (AMPK), an energy sensor that maintains the balance between ATP production and consumption. The anti‐inflammatory action of AMPK has been reported to be mediated by promoting mitochondrial biogenesis and fatty acid oxidation. However, the exact signals responsible for salicylate‐mediated inflammation through AMPK are not well‐understood. In the current study, we examined the potential effects of NaSal on inflammation‐like responses of THP‐1 monocytes to lipopolysaccharide (LPS) challenge. THP‐1 cells were stimulated with or without 10 ug/mL LPS for 24 h in the presence or absence of 5 mM NaSal. Apoptosis was measured by flow cytometry using Annexin V/PI staining and by Western blotting for the Bcl‐2 anti‐apoptotic protein. Cell proliferation was detected by EdU incorporation and by Western blot analysis for proliferating cell nuclear antigen (PCNA). Secretion of pro‐inflammatory cytokines (TNF‐α, IL‐1β, IL‐6) was determined by enzyme‐linked immunosorbent assay (ELISA). We observed that the activation of AMPK by NaSal was accompanied by induction of apoptosis, inhibition of cell proliferation, and increasing secretion of TNF‐α and IL‐1β. These effects were reversed by Compound C, an inhibitor of AMPK. In addition, NaSal/AMPK activation inhibited LPS‐induced STAT3 phosphorylation, which was reversed by Compound C treatment. We conclude that AMPK activation is important for NaSal‐mediated inflammation by inducing apoptosis, reducing cell proliferation, inhibiting STAT3 activity, and producing TNF‐α and IL‐1β.