TLR4 monoclonal antibody blockade suppresses dextran-sulfate-sodium-induced colitis in mice

Resatorvid (TAK-242) Ameliorates Ulcerative Colitis by Modulating Macrophage Polarization and T Helper Cell Balance via TLR4/JAK2/STAT3 Signaling Pathway

Resatorvid (TAK-242), a specific inhibitor of Toll-like receptor-4 (TLR4), has attracted attention for its anti-inflammatory properties. Despite this, few studies have evaluated its effects on ulcerative colitis (UC). This study aimed to investigate the effects of TAK-242 on macrophage polarization and T helper cell balance and the mechanism by which it alleviates UC. Our findings indicated that TLR4 expression was elevated in patients with UC, a mouse model of UC, and HT29 cells undergoing an inflammatory response. TAK‑242 treatment reduced apoptosis in TNF-α and LPS-stimulated HT29 cells and alleviated symptoms of dextran sulfate sodium (DSS)‑induced colitis in vivo. TAK‑242 downregulated TLR4 expression and decreased the secretion of pro-inflammatory cytokines TNF-α, IL-6, and IL-1β while enhancing IL-10 production. TAK-242 also reduced M1 macrophage polarization and diminished Th1 and Th17 cell infiltration while increasing Th2 cell infiltration and M2 macrophage polarization both in vitro and in vivo. Mechanistically, TAK-242 inhibited the JAK2/STAT3 signaling pathway, an important regulator of macrophage polarization and T helper cell balance. Furthermore, the in vivo and in vitro effects of TAK-242 were partially negated by the administration of the JAK2/STAT3 antagonist AG490, suggesting that TAK-242 inhibits the JAK2/STAT3 pathway to exert its biological activities. Taken together, this study underscores TAK-242 as a promising anti-UC agent, functioning by modulating macrophage polarization and T helper cell balance via the TLR4/JAK2/STAT3 signaling pathway.

Research trends in ulcerative colitis: A bibliometric and visualized study from 2011 to 2021

Background: Ulcerative colitis (UC) is an idiopathic inflammatory bowel disease with repeated relapses and remissions. Despite decades of effort, numerous aspects, including the initiating event and pathogenesis of UC, still remain ambiguous, which requires ongoing investigation. Given the mass of publications on UC, there are multidimensional challenges to evaluating the scientific impact of relevant work and identifying the current foci of the multifaceted disease. Accordingly, herein, we aim to assess the global growth of UC research production, analyze patterns of research areas, and evaluate trends in this area.

Methods: The Web of Science Core Collection of Clarivate Analytics was searched for articles related to UC published from 2011 to 2021. Microsoft Office Excel 2019 was used to visualize the number of publications over time. Knowledge maps were generated using CiteSpace and VOSviewer to analyze collaborations among countries, institutions, and authors and to present the journey of UC research as well as to reveal the current foci of UC research.

Results: A total of 5,088 publications were evaluated in the present study. China had the most publications (1,099, 22.5%). Univ Calif San Diego was the most productive institution (126, 2.48%). William J Sandborn published the greatest number of articles (100, 1.97%). Toshifumi Hibi was the most influential author in the field with a betweenness centrality of 0.53. Inflammatory bowel diseases was identified as the most prolific journal (379, 7.45%). Gastroenterology was the most co-cited journal (3,730, 4.02%). “Vedolizumab,” “tofacitinib,” “Faecalibacterium prausnitzii,” “fecal microbiota transplantation (FMT),” “toll-like receptor 4,” and “nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome” were considered the hot topics.

Conclusion: In UC research, manuscripts that had high impacts on the scientific community provided an evidence base. UC therapy has entered the era of personalized and precision therapy. As research on FMT, anti-integrin antibodies, Janus kinase inhibitors, and anti-tumor necrosis factor drugs continues to grow, their use in the clinical setting may also expand.

Toll-like receptor 4 prevents AOM/DSS-induced colitis-associated colorectal cancer in Bacteroides fragilis gnotobiotic mice

Bacteroides fragilis (BF) plays a critical role in developing and maintaining the mammalian immune system. We previously found that BF colonization could prevent inflammation and tumor formation in a germ-free (GF) colitis-associated colorectal cancer (CAC) mouse model. The role of Toll-like receptor 4 (TLR4) in CAC development has not been clearly elucidated in BF mono-colonized gnotobiotic mice. The wild-type (WT) and TLR4 knockout (T4K) germ-free mice were raised with or without BF colonization for 28 days (GF/WT, GF/T4K, BF/WT, and BF/T4K) and then CAC was induced under azoxymethane (AOM)/dextran sulfate sodium (DSS) administration. The results showed that tumor formation and tumor incidence were significantly inhibited in the BF/WT group compared to those observed in the GF/WT group. However, the tumor prevention effect was not observed in the BF/T4K group unlike in the BF/WT group. Moreover, the CAC histological severity of the BF/WT group was ameliorated, but more severe lesions were found in the GF/WT, GF/T4K, and BF/T4K groups. Immunohistochemistry showed decreased cell proliferation (PCNA, β-catenin) and inflammatory markers (iNOS) in the BF/WT group compared to those in the BF/T4K group. Taken together, BF mono-colonization of GF mice might prevent CAC via the TLR4 signal pathway.

Toll-like receptor 4 (TLR4) antagonists as potential therapeutics for intestinal inflammation

Gastrointestinal inflammation is a hallmark of highly prevalent disorders, including cancer treatment-induced mucositis and ulcerative colitis. These disorders cause debilitating symptoms, have a significant impact on quality of life, and are poorly managed. The activation of toll-like receptor 4 (TLR4) has been proposed to have a major influence on the inflammatory signalling pathways of the intestinal tract. Inhibition of TLR4 has been postulated as an effective way to treat intestinal inflammation. However, there are a limited number of studies looking into the potential of TLR4 antagonism as a therapeutic approach for intestinal inflammation. This review surveyed available literature and reported on the in vitro, ex vivo and in vivo effects of TLR4 antagonism on different models of intestinal inflammation. Of the studies reviewed, evidence suggests that there is indeed potential for TLR4 antagonists to treat inflammation, although only a limited number of studies have investigated treating intestinal inflammation with TLR4 antagonists directly. These results warrant further research into the effect of TLR4 antagonists in the intestinal tract.

Atherosclerosis and Inflammatory Bowel Disease-Shared Pathogenesis and Implications for Treatment

Atherosclerosis and inflammatory bowel disease (IBD) are often regarded as 2 distinct entities. The commonest manifestation of atherosclerosis is ischemic heart disease (IHD), and an association between IHD and IBD has been reported. Atherosclerosis and IBD share common pathophysiological mechanisms in terms of their genetics, immunology, and contributing environmental factors. Factors associated with atherosclerosis are implicated in the development of IBD and vice versa. Therefore, treatments targeting the common pathophysiology pathways may be effective in both conditions. The current review considers the pathophysiological pathways that are shared between the 2 conditions and discusses the implications for treatment and research.

β-patchoulene simultaneously ameliorated dextran sulfate sodium-induced colitis and secondary liver injury in mice via suppressing colonic leakage and flora imbalance

Ulcerative colitis (UC) often occurs accompanied by colonic leakage and flora imbalance, resulting in secondary liver injury (SLI). SLI, in turn, aggravates UC, so the treatment of UC should not ignore it. β-patchoulene (β-PAE), a tricyclic sesquiterpene isolated from Pogostemon cablin, has been reported to exert a protective effect in gastrointestinal disease in our previous studies. However, its protection against UC and SLI remains unknown. Here we explored the protective effect and underlying mechanism of β-PAE against dextran sulfate sodium-induced UC and SLI in mice. The results indicated that β-PAE significantly reduced disease activity index, splenic index and attenuated the shortening of colonic length in UC mice. It alleviated colonic pathological changes and apoptosis through protecting tight junctions, reducing neutrophil aggregation, and inhibiting the release of pro-inflammatory cytokines and adhesion molecules. These effects of β-PAE were associated with the inhibition of TLR4/MyD88/NF-κB and ROCK1/MLC2 signalling pathway. UC-induced colonic leakage caused abnormally high LPS levels to result in SLI, and β-PAE markedly inhibited it. β-PAE simultaneously ameliorated SLI with reduced biomarker levels of endotoxin exposure and hepatic inflammation. High levels of LPS were also associated with flora imbalance in UC mice. However, β-PAE restored the diversity of gut microbiota and altered the relative abundance of characteristic flora of UC mice. Escherichia-dominated gut microbiota of UC mice was changed to Oscillospira-dominated after β-PAE treatment. In conclusion, pharmacological effects of β-PAE on UC and SLI were mainly contributed by suppressing colonic leakage and flora imbalance. The findings may have implications for UC treatment that not neglect the treatment of SLI.

Effect of chemical modulation of toll-like receptor 4 in an animal model of ulcerative colitis

PURPOSE

The partial ineffectiveness and side effects of inflammatory bowel disease (IBD) current therapies drive basic research to look for new therapeutic target in order to develop new drug lead. Considering the pivotal role played by toll-like receptors (TLRs) in gut inflammation, we evaluate here the therapeutic effect of the synthetic glycolipid TLR4 antagonist FP7.

METHODS

The anti-inflammatory effect of FP7, active as TLR4 antagonist, was evaluated on peripheral blood mononuclear cells (PBMCs) and lamina propria mononuclear cells (LPMCs) isolated from IBD patients, and in a mouse model of ulcerative colitis.

RESULTS

FP7 strongly reduced the inflammatory responses induced by lipopolysaccharide (LPS) in vitro, due to its capacity to compete with LPS for the binding of TLR4/MD-2 receptor complex thus inhibiting both the MyD88- and TRIF-dependent inflammatory pathways. Colitic mice treated with FP7 exhibit reduced colonic inflammation and decreased levels of pro-inflammatory cytokines.

CONCLUSIONS

This study suggests that TLR4 chemical modulation can be an effective therapeutic approach to IBD. The selectivity of FP7 on TLR4 makes this molecule a promising drug lead for new small molecules-based treatments.

Curcumin ameliorates dextran sulfate sodium-induced colitis in mice via regulation of autophagy and intestinal immunity

BACKGROUND/AIMS

Inflammatory bowel disease (IBD) is regarded as a kind of chronic and unspecific intestinal inflammatory disorder. Its exact pathogenesis has not been elucidated. Curcumin, as an herbal drug, has been used in the treatment of IBD due to its immunoregulation. Autophagy has been reported to play an important role in the mechanism of IBD. In the present study, we focused on the autophagic regulation role of curcumin in the murine model of dextran sulfate sodium (DSS)-induced colitis.

MATERIALS AND METHODS

We investigated the effects of curcumin on the progress of DSS-induced acute colitis in mice by evaluating the disease activity index (DAI) and histopathological score. Meanwhile, the mRNA and protein expression of autophagy-related key genes from colon tissues comprising autophagy-related 5 (ATG5), LC3-phosphatidylethanolamine conjugate (LC-3II), beclin-1, and B cell lymphoma 2 (bcl-2) was examined by quantitative reverse transcription polymerase chain reaction and Western blot. Furthermore, the mRNA and protein expression of cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL) 6, IL-10, and IL-17A, was examined. Autophagosome was also examined under transmission electron microscopy.

RESULTS

Both DAI and histopathological score increased in mice with DSS-induced colitis and obviously decreased after curcumin intervention. The expression levels of TNF-α, IL-6, IL-17, ATG5, LC-3II, and beclin-1 were significantly higher in mice with colitis than in normal ones, whereas those of IL-10 and bcl-2 decreased accordingly. However, curcumin intervention adjusted the expression level of those factors toward normal level. The number of autophagosome in the colon epithelia increased after DSS stimulation and decreased after curcumin administration.

CONCLUSION

Curcumin could prevent the development of DSS-induced colitis through the inhibition of excessive autophagy and regulation of following cytokine networks.

Artesunate exerts protective effects against ulcerative colitis via suppressing Toll‑like receptor 4 and its downstream nuclear factor‑κB signaling pathways

Artesunate (ART) is a semi-synthetic derivative of artemisinin used in the treatment of patients with malaria, which has also been reported to have immunoregulatory, anticancer and anti-inflammatory properties. The aim of the present study was to investigate the possible beneficial effects of ART on ulcerative colitis (UC) rats and to detect the possible mechanisms underlying these effects. A UC rat model was established using dextran sulfate sodium (DSS). Rats were randomly divided into the following groups: Normal control, UC model group, UC rats treated with a low, medium or high dose of ART (10, 30 and 50 mg/kg/day, respectively), and the positive control group (50 mg/kg/day 5-aminosalicylic acid). The damage status of colonic mucosal epithelial tissue was investigated by hematoxylin and eosin staining, and then the weight, colon length and disease activity index (DAI) were measured. Western blotting and reverse transcription-quantitative polymerase chain reaction analysis were used to detect the levels of cytokines associated with UC and proteins associated with Toll-like receptor 4 (TLR4)-nuclear factor (NF)-κB pathway. ELISA was also performed to measure the levels of inflammatory cytokines. In addition, the viability and infiltration of RAW264.7 cells were examined using Cell Counting Kit-8 and Transwell assays. The results demonstrated that treatment with ART significantly alleviated the UC symptoms induced by DSS in the rat model, lowered the DAI, ameliorated pathological changes, attenuated colon shortening, inhibited the levels of pro-inflammatory mediators and myeloperoxidase activity, and increased hemoglobin expression. Additionally, inflammatory and apoptotic markers were found to be significantly downregulated following treatment with ART in UC rats and RAW264.7 cells. To the best of our knowledge, the present study is the first to demonstrate that ART exerts anti-inflammatory effects via regulating the TLR4-NF-κB signaling pathway in UC.

Effect of Soothing Gan (Liver) and Invigorating Pi (Spleen) Recipes on TLR4-p38 MAPK Pathway in Kupffer Cells of Non-alcoholic Steatohepatitis Rats

OBJECTIVE

To investigate the mechanism of inflflammatory-mediated toll-like receptor 4 (TLR4)-p38 mitogen-activated protein kinase (p38 MAPK) pathway in Kupffer cells (KCs) of non-alcoholic steatohepatitis (NASH) rats and the intervention effect of soothing Gan (Liver) and invigorating Pi (Spleen) recipes on this pathway.

METHODS

After 1 week of acclimatization, 120 Sprague-Dawley male rats were randomly divided into 8 groups using a random number table (n=15 per group): normal group, model group, low-dose Chaihu Shugan Powder (, CHSG) group (3.2 g/kg), high-dose CHSG group (9.6 g/kg), low-dose Shenling Baizhu Powder (, SLBZ) group (10 g/kg), high-dose SLBZ (30 g/kg) group, and low- and highdose integrated recipe (L-IR, H-IR) groups. All rats in the model and treatment groups were fed with a high-fat diet (HFD). The treatments were administrated by gastrogavage once daily and lasted for 26 weeks. The liver tissues were detected with hematoxylin-eosin (HE) and oil red O staining. Levels of liver lipids, serum lipids and transaminases were measured. KCs were isolated from the livers of rats to evaluate the mRNA expressions of TLR4 and p38 MAPK by real-time flfluorescence quantitative polymerase chain reaction, and proteins expressions of TLR4, p-p38 MAPK and p38 MAPK by Western blot. Levels of inflammatory cytokines including tumor necrosis factor α (TNF-α), interleukin (IL)-1 and IL-6 in KCs were measured by enzyme-linked immunosorbent assay.

RESULTS

After 26 weeks of HFD feeding, HE and oil red O staining showed that the NASH model rats successfully reproduced typical pathogenesis and histopathological features. Compared with the normal group, the model group exhibited significant increases in body weight, liver weight, liver index, serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol, and aspartate aminotransferase as well as TC and TG levels in liver tissues, and significant decrease in serum level of high-density lipoprotein cholesterol (Plt;0.05 or Plt;0.01), while those indices were significantly ameliorated in the H-IR group (Plt;0.05 or Plt;0.01). Higher levels of TNF-α, IL-1 and IL-6 in KCs were observed in the model group compared with the normal group (Plt;0.01). Significant decreases in TNF-α, IL-1 and IL-6 were observed in the H-SLBZ, H-IR and L-IR groups compared with the model group (Plt;0.05 or Plt;0.01). The mRNA expressions of TLR4 and p38 MAPK and protein expressions of TLR4, p38 MAPK and p-p38 MAPK in KCs in the model group were significantly higher than the normal group (Plt;0.01), while those expression levels in the L-IR and H-IR groups were significantly lower than the model group (Plt;0.05 or Plt;0.01).

CONCLUSION

Inflflammation in KCs might play an important role in the pathogenesis of NASH in rats. The data demonstrated the importance of TLR4-p38MAPK signaling pathway in KCs for the anti-inflflammatory effect of soothing Gan and invigorating Pi recipes.

Inflammasome-independent role of NLRP12 in suppressing colonic inflammation regulated by Blimp-1

NLRP12 is a member of the Nod-like receptor (NLR). Previous studies have reported enhanced colitis-associated inflammatory responses in NLRP12-deficient mice. In this study, we sought to investigate the role of NLRP12 in DSS-stimulated proinflammatory response in dendritic cells and mice colitis, and the molecular mechanisms involved in the development of the inflammation. Our results showed that down-regulation of NLRP12 is required for DSS-induced release of proinflammatory cytokines IL-1β and TNF-α; that PR domain zinc finger protein 1 (also known as Blimp-1) induces NLRP12 down-regulation during DSS-induced proinflammatory response and colitis; and that TLR4 is implicated in the up-regulation of Blimp-1 that led to the down-regulation of NLRP12 expression in DSS-induced colitis. Taken together, the results suggest that the TLR4-Blimp-1 axis promotes DSS induced experimental colitis through the down-regulation of NLRP12.

Effects of probiotics on Toll‑like receptor expression in ulcerative colitis rats induced by 2,4,6‑trinitro‑benzene sulfonic acid

The present study aimed to investigate the regulatory effect of probiotics on the expression of Toll‑like receptors (TLRs) in an ulcerative colitis (UC) rat model, and to determine the role of probiotics in the underlying mechanisms through which UC develops and progresses in rat models. Rats were randomly allocated to one of the four following groups: i) The healthy control, ii) the model, iii) the Golden bifid treatment group, and iv) the TLR4 monoclonal antibody (TLR4mAb) intervention group. The UC rat model was established using 2,4,6‑trinitro‑benzene sulfonic acid. The general status and histological changes of rats were scored using the disease activity index and the histopathological scoring method, respectively. In these rats, the expression of TLR4 and TLR2 was measured using reverse transcription‑quantitative polymerase chain reaction. The expression of TLR4 and TLR2 in the model group was significantly higher than that in the healthy control group. However, when compared with the model rats, those that received either Golden bifid treatment or TLR4mAb intervention exhibited significantly decreased mRNA expression levels of TLR4 and TLR2 (P<0.05). The development of UC is characterized by an abnormal immune response in the intestines. Probiotics alleviated inflammatory reactions in rats with UC. The underlying mechanism of UC may be associated with the expression of TLRs and the subsequent release of inflammatory cytokines.

miR-511-3p, embedded in the macrophage mannose receptor gene, contributes to intestinal inflammation

MiR-511-3p is embedded in intron 5 of the CD206/MRC1 gene Mrc1, expressed by macrophage and dendritic cell populations. CD206 and miR-511-3p expression are co-regulated, and their contribution to intestinal inflammation is unclear. We investigated their roles in intestinal inflammation in both mouse and human systems. Colons of CD206-deficient mice displayed normal numbers of monocytes, macrophage, and dendritic cells. In experimental colitis, CD206-deficient mice had attenuated inflammation compared with wild-type (WT) mice. However, neither a CD206 antagonist nor a blocking antibody reproduced this phenotype, suggesting that CD206 was not involved in this response. Macrophages isolated from CD206-deficient mice had reduced levels of miR-511-3p and Tlr4 compared with WT, which was associated with reduced pro-inflammatory cytokine production upon lipopolysaccharides (LPS) and fecal supernatant stimulation. Macrophages overexpressing miR-511-3p showed 50% increase of Tlr4 mRNA, whereas knockdown of miR-511-3p reduced Tlr4 mRNA levels by 60%, compared with scrambled microRNA (miRNA)-transduced cells. Response to anti-tumor necrosis factor (TNF) treatment has been associated with elevated macrophage CD206 expression in the mucosa. However, in colon biopsies no statistically significant change in miR-511-3p was detected. Taken together, our data show that miR-511-3p controls macrophage-mediated microbial responses and is involved in the regulation of intestinal inflammation.

Cardiolipins Act as a Selective Barrier to Toll-Like Receptor 4 Activation in the Intestine

Intestinal homeostasis mechanisms must protect the host intestinal tissue from endogenous lipopolysaccharides (LPSs) produced by the intestinal microbiota. In this report, we demonstrate that murine intestinal fecal lipids effectively block Toll-like receptor 4 (TLR4) responses to naturally occurring Bacteroidetes sp. LPS. Cardiolipin (CL) represents a significant proportion of the total intestinal and fecal lipids and, furthermore, potently antagonizes TLR4 activation by reducing LPS binding at the lipopolysaccharide binding protein (LBP), CD14, and MD-2 steps of the TLR4 signaling pathway. It is further demonstrated that intestinal lipids and CL are less effective at neutralizing more potent Enterobacteriaceae-type LPS, which is enriched in feces obtained from mice with dextran sodium sulfate (DSS)-treated inflammatory bowel disease. The selective inhibition of naturally occurring LPS structures by intestinal lipids may represent a novel homeostasis mechanism that blocks LPS activation in response to symbiotic but not dysbiotic microbial communities.

IMPORTANCE

The guts of animals harbor a variety of Gram-negative bacteria associated with both states of intestinal health and states of disease. Environmental factors, such as dietary habits, can drive the microbial composition of the host animal's intestinal bacterial community toward a more pathogenic state. Both beneficial and harmful Gram-negative bacteria are capable of eliciting potentially damaging inflammatory responses from the host intestinal tissues via a lipopolysaccharide (LPS)-dependent pathway. Physical mucosal barriers and antibodies produced by the intestinal immune system protect against the undesired inflammatory effects of LPS, although it is unknown why some bacteria are more effective at overcoming the protective barriers than others. This report describes the discovery of a lipid-type protective barrier in the intestine that reduces the deleterious effects of LPSs from beneficial bacteria but is less effective in dampening the inflammatory effects of LPSs from harmful bacteria, providing a novel mechanistic insight into inflammatory intestinal disorders.

Mutual reinforcement of inflammation and carcinogenesis by the Helicobacter pylori CagA oncoprotein

Helicobacter pylori cagA-positive strain delivers the CagA oncoprotein into gastric epithelial cells and at the same time elicits stomach inflammation. To experimentally investigate the pathophysiological interplay between CagA and inflammation, transgenic mice systemically expressing the bacterial cagA gene were treated with a colitis inducer, dextran sulfate sodium (DSS). Compared with control mice, DSS-induced colitis was markedly deteriorated in cagA-transgenic mice. In the colonic epithelia of cagA-transgenic mice, there was a substantial decrease in the level of IκB, which binds and sequesters NF-κB in the cytoplasm. This IκB reduction was due to CagA-mediated inhibition of PAR1, which may stimulate IκB degradation by perturbing microtubule stability. Whereas the CagA-mediated IκB reduction did not automatically activate NF-κB, it lowered the threshold of NF-κB activation by inflammogenic insults, thereby contributing to colitis exacerbation in cagA-transgenic mice. CagA also activates inflammasomes independently of NF-κB signaling, which further potentiates inflammation. The incidence of colonic dysplasia was elevated in DSS-treated cagA-transgenic mice due to a robust increase in the number of pre-cancerous flat-type dysplasias. Thus, CagA deteriorated inflammation, whereas inflammation strengthened the oncogenic potential of CagA. This work revealed that H. pylori CagA and inflammation reinforce each other in creating a downward spiral that instigates neoplastic transformation.

Royal Jelly and its dual role in TNBS colitis in mice

Royal Jelly (RJ) is widely consumed in diets throughout the world due to its beneficial effects: antioxidant, antitumor and anti-inflammatory. We have investigated the role of RJ in the development of TNBS colitis in mice. Colitis was induced by a rectal instillation of TNBS at 0.1 mL per mouse. Intestine samples of the animals orally treated with RJ (100, 150, and 200 mg/kg) were collected for antioxidant assays (GSH and GSH-Px), proinflammatory protein quantification (COX-2 and NF-κB), and histological analyses. RJ 100 mg/kg maintained GSH levels and increased the activity of GSH-Px, downregulated key inflammatory mediators (COX-2 and NF-κB), and decreased the lesions caused by TNBS as shown by the histological analyses. In conclusion, RJ showed anti-inflammatory and antioxidant properties in experimental colitis, resulting in the amelioration of the macroscopic and histological analyses. These results corroborate with the RJ supplementation in diets.

Effects of Chaihu-Shugan-San and Shen-Ling-Bai-Zhu-San on p38 MAPK Pathway in Kupffer Cells of Nonalcoholic Steatohepatitis

This study aimed to investigate the effects of Chaihu-Shugan-San (CSS), Shen-Ling-Bai-Zhu-San (SLBZS), and integrated recipe of the above two recipes on inflammatory markers and proteins involved in p38 MAPK pathway in Kupffer cells of NASH rats induced by high fat diet (HFD). Rats were administered at low or high dose of CSS, SLBZS, and integrated recipe except normal group and model group for 16 weeks. The levels of hepatic lipid, TNF- α , IL-1, and IL-6 in liver tissues were measured. Kupffer cells were isolated from livers to evaluate expressions of TLR4, p-p38 MAPK, and p38 MAPK by Western blotting. The results showed that the NASH model rats successfully reproduced typical pathogenetic and histopathological features. Levels of hepatic lipid and liver tissues inflammatory factors in high-dose SLBZS group and integrated recipe group were all lower than that of model group decreased observably. Expressions of TLR4, p-p38 MAPK, and p38 MAPK in Kupffer cells were decreased in all treatment groups, but there was no significant difference between treatment groups. The high-dose SLBZS group had the lowest expression levels of TLR4, and the most visible downtrend in the expression levels of p-p38 MAPK and p38 MAPK was found in the high-dose integrated recipe group. The ratio of p-p38 MAPK to total p38 MAPK protein was obviously increased in all treatment groups. Therefore, our study showed that the activation of p38 MAPK pathway in Kupffer cells might be related to the release of inflammatory factors such as TNF- α , IL-1, and IL-6 in NASH rats. High dose of SLBZS and integrated recipe might work as a significant anti-inflammatory effect in Kupffer cells of NASH rats induced by HFD through suppression of p38 MAPK pathway. It indicated that p38 MAPK pathway may be the possible effective target for the recipes.

Paeoniflorin abrogates DSS-induced colitis via a TLR4-dependent pathway

Paeonia lactiflora Pall is one of the most well-known herbs in China, Korea, and Japan for more than 1,200 years. Paeoniflorin, the major bioactive component of peony root, has recently been reported to have anticolitic activity. However, the underlying molecular mechanism is unclear. The present study was to explore the possible mechanism of paeoniflorin in attenuating dextran sulfate sodium (DSS)-induced colitis. Pre- and coadministration of paeoniflorin significantly reduced the severity of colitis and resulted in downregulation of several inflammatory parameters in the colon, including the activity of myeloperoxidase (MPO), the levels of TNF-α and IL-6, and the mRNA expression of proinflammatory mediators (MCP-1, Cox2, IFN-γ, TNF-α, IL-6, and IL-17). The decline in the activation of NF-κB p65, ERK, JNK, and p38 MAPK correlated with a decrease in mucosal Toll-like receptor 4 (TLR4) but not TLR2 or TLR5 expression. In accordance with the in vivo results, paeoniflorin downregulated TLR4 expression, blocked nuclear translocation of NF-κB p65, and reduced the production of IL-6 in LPS-stimulated mouse macrophage RAW264.7 cells. Transient transfection assay performed in LPS-stimulated human colon cancer HT-29 cells indicated that paeoniflorin inhibits NF-κB transcriptional activity in a dose-dependent manner. TLR4 knockdown and overexpression experiments demonstrated a requirement for TLR4 in paeoniflorin-mediated downregulation of inflammatory cytokines. Thus, for the first time, the present study indicates that paeoniflorin abrogates DSS-induced colitis via decreasing the expression of TLR4 and suppressing the activation of NF-κB and MAPK pathways.

p38 MAPK signal pathway involved in anti-inflammatory effect of Chaihu-Shugan-San and Shen-ling-bai-zhu-San on hepatocyte in non-alcoholic steatohepatitis rats

BACKGROUND

Traditional Chinese Medicine (TCM), has over thousands-of-years history of use. Chaihu-Shugan-San (CSS), and Shen-ling-bai-zhu-San (SLBZS), are famous traditional Chinese herbal medicine formulas, which have been used in China, for the treatment of many chronic diseases.

MATERIALS AND METHODS

This study investigated the anti-inflammatory effects of CSS and SLBZS on signaling molecules involved in p38 mitogen-activated protein kinase (p38 MAPK), pathway on hepatocytes of non-alcoholic steatohepatitis (NASH), rats induced by high fat diet. SD male rats were randomly divided into 8 groups: negative control group, model control group, high (9.6g/kg/day)/low (3.2g/kg/day)-dose CSS group, high (30g/kg/day)/low (10g/kg/day)-dose SLBZS group, high (39.6g/kg/day)/low (13.2g/kg/day)-dose integrated group. The rats of NASH model were induced by feeding a high-fat diet. After 16, wks, Hepatocytes were isolated from 6, rats in each group by collagenase perfusion. The liver histopathological changes and serum inflammatory cytokines TNF-α, IL-6 were determined. The proteins of TLR4, phosphor-p38 MAPK and p38 MAPK involved in p38 MAPK signal pathway were assayed.

RESULTS

The statistical data indicated the NASH model rats reproduced typical histopathological features of NASH in human. CSS and SLBZS ameliorated lipid metabolic disturbance, attenuated NASH progression, decreased the levels of TNF-α and IL-6 in serum, as well as inhibited TLR4 protein expression, p38 MAPK phosphorylation, and activation of p38 MAPK. In conclusion, CSS and SLBZS might work as a significant anti-inflammatory effect on hepatocyte of NASH by inhibiting the activation of TLR4, p-p38 MAPK and p38 MAPK involved in p38 MAPK signal pathway.

CONCLUSION

To some extent, CSS and SLBZS may be a potential alternative and complementary medicine to protect against liver injury, alleviate the inflammation reaction, moderate NASH progression.

Host-microbe interactions: the difficult yet peaceful coexistence of the microbiota and the intestinal mucosa

The immune system has evolved to live in a collaborative relationship with the microbiota, while still serving its seminal function to fight off invasive pathogenic bacteria. The mechanisms that rule the interactions between the intestinal microbiota and the intestinal immune system are the focus of intense research. Here, we describe how the innate immunity is, to a great extent, in charge of the control of the microbiota in the intestine and relies on non-specific receptors called pathogen-recognition receptors. While the microbiota has a well-defined effect on the host immune homoeostasis, it has become clear that the opposite is also true, i.e., the mucosal immune system has the capacity to shape the microbial population. The mechanisms that rule the reciprocal regulation between host immunity and commensal bacteria (including specific bacteria) are currently being elucidated and will be described here. A better knowledge of how the host and bacteria interact and how the intestinal microbiota and the immune system are co-regulated will provide the basis for a better understanding of intestinal and systemic immunopathologies and for the development of new therapeutic approaches.

Readressing the role of Toll-like receptor-4 alleles in inflammatory bowel disease: colitis, smoking, and seroreactivity

BACKGROUND

Toll-like receptor (TLR) polymorphisms, and especially TLR-4 Asp299Gly and TLR-4 Thr399Ile, have been linked with Crohn's disease (CD) and to a lesser extent with ulcerative colitis (UC), CD behavior, and compromised seroreactivity to microbial antigens. Available data, however, are conflicting.

AIMS

To address these issues, the distribution of TLR-4 polymorphic alleles was assessed in patients with UC, CD, and healthy controls (HC), considering patient and disease characteristics as well as related serological markers.

METHODS

TLR-4 Asp299Gly and TLR-4 Thr399Ile polymorphisms were determined in 187 UC and 163 CD patients and 274 randomly selected HC. C reactive protein, anti-Saccharomyces cerevisiae mannan antibodies, anti-mannobioside carbohydrate antibodies, anti-laminariobioside carbohydrate antibodies IgG, and anti-chitobioside carbohydrate antibodies (ACCA) IgA levels were also assessed.

RESULTS

UC and especially pancolitis patients carried the mutant alleles more frequently compared to CD patients and HC or UC patients with different disease extents (P = 0.002 and P < 0.0001, respectively). Involvement of the colon was more frequent in CD patients with mutant TLR-4 compared to those with wild-type alleles (P = 0.004). Levels and positivity rates of ACCA IgA were lower in inflammatory bowel disease (IBD) patients carrying the mutant compared to those with wild-type alleles (0.075 < P < 0.05). Despite the mutant TLR-4 predisposition for UC pancolitis, smoking was associated with more limited disease (P < 0.001).

CONCLUSIONS

The presence of TLR-4 Asp299Gly and TLR-4 Thr399Ile polymorphisms is related to UC pancolitis, involvement of the colon in CD, and lower ACCA IgA levels. Smoking reduces the extent of UC, even in the presence of mutant alleles.

Toll-like receptors promote inflammation in idiopathic inflammatory myopathies

The roles of Toll-like receptors (TLRs) and their myeloid differentiation response gene 88 (MyD88)-dependent and MyD88-independent signaling cascade particularly with regard to the pathogenesis and regulation of immune responses in idiopathic inflammatory myopathies are unclear. We investigated these pathways in muscle biopsies from 5 cases each of polymyositis, inclusion body myositis, dermatomyositis, vasculitis-associated interstitial myositis, and noninflammatory neurogenic atrophy. Toll-like receptor 2, TLR4, TLR9, and MyD88 mRNA transcripts and protein expression were increased in all subtypes of idiopathic inflammatory myopathies. Upregulation of MyD88 was associated with increased mRNA levels of interferon-γ, interleukin 12p40, and interleukin 17, suggesting NF-κB activation via the MyD88-dependent pathway in early stages. The costimulatory molecules CD80 and CD86 were expressed on inflammatory infiltrates in idiopathic inflammatory myopathies and may additionally contribute to activation of the MyD88-independent pathway, leading to nuclear factor-κB activation in late stages. Our data suggest that nuclear factor-κB activation via both the MyD88-dependent and the MyD88-independent pathways contributes to the proinflammatory milieu in idiopathic inflammatory myopathies.

Peracetylated (-)-epigallocatechin-3-gallate (AcEGCG) potently suppresses dextran sulfate sodium-induced colitis and colon tumorigenesis in mice

Previous studies reported that peracetylated (-)-epigallocatechin-3-gallate (AcEGCG) has antiproliferative and anti-inflammatory activities. Here, we evaluated the chemopreventive effects and underlying molecular mechanisms of dietary administration of AcEGCG and EGCG in dextran sulfate sodium (DSS)-induced colitis in mice. The mice were fed a diet supplemented with either AcEGCG or EGCG prior to DSS induction. Our results indicated that AcEGCG administration was more effective than EGCG in preventing the shortening of colon length and the formation of aberrant crypt foci (ACF) and lymphoid nodules (LN) in mouse colon stimulated by DSS. Our study observes that AcEGCG treatment inhibited histone 3 lysine 9 (H3K9) acetylation but did not affect histone acetyltransferase (HAT) activity and acetyl- CREB-binding protein (CBP)/p300 levels. In addition, pretreatment with AcEGCG decreased the proinflammatory mediator levels by down-regulating of PI3K/Akt/NFκB phosphorylation and p65 acetylation. We also found that treatment with AcEGCG increased heme oxygenase-1(HO-1) expression via activation of extracellular signal-regulated protein kinase (ERK)1/2 signaling and acetylation of NF-E2-related factor 2 (Nrf2), thereby abating DSS-induced colitis. Moreover, dietary feeding with AcEGCG markedly reduced colitis-driven colon cancer in mice. Taken together, these results demonstrated for the first time the in vivo chemopreventive efficacy and molecular mechanisms of dietary AcEGCG against inflammatory bowel disease (IBD) and potentially colon cancer associated with colitis. These findings provide insight into the biological actions of AcEGCG and might establish a molecular basis for the development of new cancer chemopreventive agents.

Modulation of toll-like receptors by insulin

Toll-like receptors (TLRs) are first-line molecules for initiating the innate immune responses and mediating functional activation in immune effector cells. A family of 10 functional human TLRs altogether can recognize the ligands that do not exist in the host and initiate the inflammatory cascades. This triggers the production of inflammatory cytokines, chemokines, and interferons. Overactivation of innate immunity might lead to immune-mediated inflammatory disorders. Besides that, TLRs are currently viewed as active participants in the cross-communication between immunity and metabolic health. Recent data directly implicate the activation of inflammatory pathways in the pathogenesis of type 1 and type 2 diabetes, atherosclerosis, obesity, and also cancer. The following approaches to develop new TLR drugs have been undertaken: generating TLR agonists/antagonists, creating monoclonal antibody to TLRs, blocking the key molecules in the signaling pathways, down-modulating TLR signaling. In this article, we briefly review the involvement of TLRs in diseases associated with metabolic alterations, underscoring the modulation of TLRs by insulin.

Toll-like receptor 2 monoclonal antibody or/and Toll-like receptor 4 monoclonal antibody increase counts of Lactobacilli and Bifidobacteria in dextran sulfate sodium-induced colitis in mice

BACKGROUND AND AIM

The accurate pathogenesis of ulcerative colitis (UC) is not yet well understood. Recently, Toll-like receptor 2 (TLR2), TLR4 and gut microbial flora have been proved as playing important roles in the process of UC. This study was to evaluate the effect of TLR2 and TLR4 monoclonal antibodies on gut microbial flora in dextran sulfate sodium (DSS)-induced colitis in a mouse model.

METHODS

We evaluated the effects of the TLR2 and TLR4 monoclonal antibodies on the development of DSS-induced colitis. Clinical symptoms were evaluated by the disease activity index (DAI), while tissue samples were evaluated by histological scoring (HS). Meanwhile, the mucosal mRNA expressions of TLR2, TLR4, interferon-γ (IFN-γ), interleukin-4 (IL-4) and IL-17 were analyzed by Realtime polymerase chain reaction (PCR). The mucosal protein TRAF6, TAB1, P-IKK, P-P38α mitogen-activated protein kinase (MAPL) and c-jun expressions of the TLR2 and TLR4 signaling pathways were analyzed using Western blot. The mucosal nuclear factor kappa B (NF-κB) was analyzed using electrophoretic mobility shift assay. Fecal samples were obtained directly from the cecum for microbiological studies.

RESULTS

Expressions of TLR2 and TLR4 in colonic epithelial cells on DSS-induced colitis were much higher than normal ones. After the treatment with TLR2mAb and TLR4mAb, DAI and HS were decreased significantly. The UC model group showed a conspicuous increase of Escherichia coli and decreases of Lactobacillus spp. and Bifidobacterium spp. After being treated with TLR2mAb or/and TLR4mAb, Lactobacillus spp. and Bifidobacterium spp. increased to the normal level.

CONCLUSIONS

TLR2mAb and TLR4mAb can suppress the development of DSS-induced colitis and increase counts of Lactobacilli and Bifidobacteria.

Worms, flies and four-legged friends: the applicability of biological models to the understanding of intestinal inflammatory diseases

Diseases of intestinal inflammation, including Crohn's disease, ulcerative colitis and necrotizing enterocolitis, cause substantial acute and chronic disability in a large proportion of the population. Crohn's disease and ulcerative colitis, which are collectively referred to as inflammatory bowel disease (IBD), lead to recurrent episodes of intestinal dysfunction and systemic illness, whereas necrotizing enterocolitis is characterized by the development of dramatic and all too often fatal intestinal necrosis in infants. To determine the molecular underpinnings of these disorders, investigators have explored a variety of animal models that vary widely in their complexity. These experimental systems include the invertebrate nematode Caenorhabditis elegans, the more complex invertebrate Drosophila melanogaster, and vertebrate systems including mice, rats and other mammals. This review explores the experimental models that are used to mimic and evaluate the pathogenic mechanisms leading to these diseases of intestinal inflammation. We then highlight, as an example, how the use of different experimental models that focus on the role of Toll-like receptor 4 (TLR4) signaling in the gut has revealed important distinctions between the pathogenesis of IBD and necrotizing enterocolitis. Specifically, TLR4-mediated signaling plays a protective role in the development of Crohn's disease and ulcerative colitis, whereas this signaling pathway plays a causative role in the development of necrotizing enterocolitis in the newborn small intestine by adversely affecting intestinal injury and repair mechanisms.

DNA attenuates enterocyte Toll-like receptor 4-mediated intestinal mucosal injury after remote trauma

Intestinal mucosal injury occurs after remote trauma although the mechanisms that sense remote injury and lead to intestinal epithelial disruption remain incompletely understood. We now hypothesize that Toll-like receptor 4 (TLR4) signaling on enterocytes after remote injury, potentially through the endogenous TLR4 ligand high-mobility group box-1 (HMGB1), could lead to intestinal dysfunction and bacterial translocation and that activation of TLR9 with DNA could reverse these effects. In support of this hypothesis, exposure of TLR4-expressing mice to bilateral femur fracture and systemic hypotension resulted in increased TLR4 expression and signaling and disruption of the ileal mucosa, leading to bacterial translocation, which was not observed in TLR4-mutant mice. TLR4 signaling in enterocytes, not immune cells, was required for this effect, as adenoviral-mediated inhibition of TLR4 in enterocytes prevented these findings. In seeking to identify the endogenous TLR4 ligands involved, the expression of HMGB1 was increased in the intestinal mucosa after injury in wild-type, but not TLR4-mutant, mice, and administration of anti-HMGB1 antibodies reduced both intestinal mucosal TLR4 signaling and bacterial translocation after remote trauma. Strikingly, mucosal injury was significantly increased in TLR9-mutant mice, whereas administration of exogenous DNA reduced the extent of TLR4-mediated enterocyte apoptosis, restored mucosal healing, and maintained the histological integrity of the intestinal barrier after remote injury. Taken together, these findings identify a novel link between remote injury and enterocyte TLR4 signaling leading to barrier injury, potentially through HMGB1 as a ligand, and demonstrate the reversal of these adverse effects through activation of TLR9.

Xanthorrhizol attenuates dextran sulfate sodium-induced colitis via the modulation of the expression of inflammatory genes in mice

AIMS

The aim of this study was to investigate the effects of xanthorrhizol (5-(1,5-dimethyl-4-hexenyl)-2-methylphenol, XA) in a mouse model of dextran sulfate sodium (DSS)-induced colitis.

MAIN METHODS

Experimental colitis was induced by exposing male BALB/c mice to 5% DSS in drinking water for 7days. XA (10 or 100mg/kg) was administered orally once a day, together with the DSS. We evaluated body weight, colon length, histological changes, and myeloperoxidase (MPO) activity. A cDNA microarray was used to assess the gene expression profiles that were affected by XA and DSS treatment and a co-citation analysis was used to examine the biological relationship between XA-responsive genes and colitis.

KEY FINDINGS

Decreased body weight, shortened colon length, and damaged colon were observed in the group that was exposed to DSS. Oral administration of XA (10 or 100mg/kg) rescued these symptomatic and histopathological features. The DSS-induced increase in MPO activity, which was used as an index of neutrophil infiltration, was significantly decreased after treatment with XA. Microarray analysis revealed that XA treatment regulated the expression of 34 genes that were altered by exposure to DSS, and that these XA-responsive genes were associated with colonic inflammation. Furthermore, co-citation analysis and graphing of XA-responsive genes revealed a network associated with the gene that encodes for MPO.

SIGNIFICANCE

These results suggest that XA attenuates acute DSS-induced colitis, possibly by modulating the expression of genes mostly associated with colonic inflammation.

Corticotropin-releasing factor regulates TLR4 expression in the colon and protects mice from colitis

BACKGROUND & AIMS

Defects in the colonic innate immune response have been associated with inflammatory bowel disease (IBD). Corticotropin-releasing hormone (CRH, or corticotropin-releasing factor [CRF]) is a neuropeptide that mediates the stress response in humans, is an immunomodulatory factor with proinflammatory effects, and regulates transcription of Toll-like receptors (TLR)-2 and TLR4. We investigated the role of CRF in an innate immunity-dependent mouse model of IBD.

METHODS

Crh(-/-) and wild-type (Crh(+/+)) mice, which are glucocorticoid insufficient, were given dextran sodium sulfate in their drinking water to induce colitis; in some experiments, mice were also given glucocorticoids. Phenotypes of mice were compared; tissues were analyzed by histology and for expression of immune mediators.

RESULTS

Crh(-/-) mice had more colonic inflammation than Crh(+/+) mice, characterized by reduced numbers of crypts and severe epithelial damage and ulcerations. Colonic tissue levels of the proinflammatory factors interleukin-12 and prostaglandin E(2) were increased in the Crh(-/-) mice. Colons of Crh(-/-) mice expressed lower levels of Tlr4 than wild-type mice before, but not after, colitis was induced. Administration of glucocorticoid at low levels did not prevent Crh(-/-) mice from developing severe colitis. Crh(-/-) mice were unable to recover from acute colitis, as indicated by their increased death rate.

CONCLUSIONS

Mice deficient in CRF down-regulate TLR4 and are more susceptible to dextran sodium sulfate-induced colitis. CRF has anti-inflammatory effects in innate immunity-dependent colitis and its recovery phase; these are independent of glucocorticoid administration. CRF might therefore be developed as a therapeutic target for patients with IBD.

Differential regulation of TLR4 expression in human B cells and monocytes

Toll-like receptor 4 (TLR4) is an innate immune receptor that is constitutively and inducibly activated in monocytes. Although TLR4 is expressed at very low levels on human B cells from healthy individuals, recent reports showed that TLR4 expression and function is elevated in B cells from inflammatory disease patients. New data showed that TLR4 expression on B cells is increased upon stimulation through surface Igμ and CD40 in combination with IL-4. In contrast, monocyte stimulation through CD40 and IL-4 receptors decreased TLR4 surface expression. Analysis of molecular signatures of TLR4 activation in stimulated B cells suggested that TLR4 is regulated by different mechanisms in B cells compared to monocytes. PU.1 and interferon regulatory factor association with the TLR4 promoter are sufficient for TLR4 transcription, but are not sufficient for surface TLR4 expression on B cells. In contrast, the PU.1/IRF combination is sufficient for surface TLR4 expression on monocytes. These data identify mechanisms that can activate B cell TLR4 expression in inflammatory disease patients, and demonstrate that B cells have additional layers of TLR4 regulation absent in monocytes.