Divergent expression of bacterial wall sensing toll-like receptors 2 and 4 in colorectal cancer

AIM To characterize the expression of toll-like receptors(TLR) 2 and 4 in colorectal cancer(CRC) and in normal colorectal mucosa.METHODS We analysed tissue samples from a prospective series of 118 unselected surgically treated patients with CRC. Sections from formalin fixed, paraffin embedded specimens were analysed for TLR2 and TLR4 expression by immunohistochemistry. Two independent assessors evaluated separately expression at the normal mucosa, at the invasive front and the bulk of the carcinoma, and in the lymph node metastases when present. Expression levels in different locations were compared and their associations with clinicopathological features including TNM-stage and the grade of the tumour and 5-year follow-up observations were analysed.RESULTS Normal colorectal epithelium showed a gradient of expression of both TLR2 and TLR4 with low levels in the crypt bases and high levels in the surface. In CRC, expression of both TLRs was present in all cases and in the major proportion of tumour cells. Compared to normal epithelium, TLR4 expression was significantly weaker but TLR2 expression stronger in carcinoma cells. Weak TLR4 expression in the invasive front was associated with distant metastases and worse cancerspecific survival at 5 years. In tumours of the proximal colon the cancer-specific survival at 5 years was 36.9% better with strong TLR4 expression as compared with those with weak expression(P = 0.044). In contrast, TLR2 expression levels were not associated with prognosis. Tumour cells in the lymph node metastases showed higher TLR4 expression and lower TLR2 expression than cells in primary tumours.CONCLUSION Tumour cells in CRC show downregulation of TLR4 and upregulation of TLR2. Low expression of TLR4 in the invasive front predicts poor prognosis and metastatic disease.

Fecal microbiota transplantation prevents hepatic encephalopathy in rats with carbon tetrachloride-induced acute hepatic dysfunction

AIM To investigate whether fecal microbiota transplantation(FMT) prevents hepatic encephalopathy(HE) in rats with carbon tetrachloride(CCl4)-induced acute hepatic dysfunction.METHODS A rat model of HE was established with CCl4. Rat behaviors and spatial learning capability were observed, and hepatic necrosis, intestinal mucosal barrier, serum ammonia levels and intestinal permeability were determined in HE rats receiving FMT treatment. Furthermore, the expression of tight junction proteins(Claudin-1, Claudin-6 and Occludin), Toll-like receptor(TLR) 4/TLR9, interleukin(IL)-1β, IL-6 and tumor necrosis factor(TNF)-α was examined.RESULTS FMT improved rat behaviors, HE grade and spatial learning capability. Moreover, FMT prevented hepaticnecrosis and intestinal mucosal barrier damage, leading to hepatic clearance of serum ammonia levels and reduced intestinal permeability. The expression of TLR4 and TLR9, two potent mediators of inflammatory response, was significantly downregulated in the liver of rats treated with FMT. Consistently, circulating proinflammatory factors such as interleukin(IL)-1β, IL-6 and tumor necrosis factor-α were remarkably decreased, indicating that FMT is able to limit systemic inflammation by decreasing the expression of TLR4 and TLR9. Importantly, HE-induced loss of tight junction proteins(Claudin-1, Claudin-6 and Occludin) was restored in intestinal tissues of rats receiving FMT treatment. CONCLUSION FMT enables protective effects in HE rats, and it improves the cognitive function and reduces the liver function indexes. FMT may cure HE by altering the intestinal permeability and improving the TLR response of the liver.

Toll-like receptors in pathophysiology of liver diseases

Toll-like receptors(TLRs) are pattern recognition receptors that participate in host defense by recognizing pathogen-associated molecular patterns alongside inflammatory processes by recognizing damage associated molecular patterns. Given constant exposure to pathogens from gut, strict control of TLR-associated signaling pathways is essential in the liver, which otherwise may lead to inappropriate production of pro-inflammatory cytokines and interferons and may generate a predisposition to several autoimmune and chronic inflammatory diseases. The liver is considered to be a site of tolerance induction rather than immunity induction, with specificity in hepatic cell functions and distribution of TLR. Recent data emphasize significant contribution of TLR signaling in chronic liver diseases via complex immune responses mediating hepatocyte(i.e., hepatocellular injury and regeneration) or hepatic stellate cell(i.e., fibrosis and cirrhosis) inflammatory or immune pathologies. Herein, we review the available data on TLR signaling, hepatic expression of TLRs and associated ligands, as well as the contribution of TLRs to the pathophysiology of hepatic diseases.

Factoring the intestinal microbiome into the pathogenesis of autoimmune hepatitis

The intestinal microbiome is a reservoir of microbial antigens and activated immune cells. The aims of this review were to describe the role of the intestinal microbiome in generating innate and adaptive immune responses, indicate how these responses contribute to the development of systemic immune-mediated diseases, and encourage investigations that improve the understanding and management of autoimmune hepatitis. Alterations in the composition of the intestinal microflora(dysbiosis) can disrupt intestinal and systemic immune tolerances for commensal bacteria. Toll-like receptors within the intestine can recognize microbe-associated molecular patterns and shape subsets of T helper lymphocytes that may cross-react with host antigens(molecular mimicry). Activated gutderived lymphocytes can migrate to lymph nodes, and gut-derived microbial antigens can translocate to extra-intestinal sites. Inflammasomes can form within hepatocytes and hepatic stellate cells, and they can drive the pro-inflammatory, immune-mediated, and fibrotic responses. Diet, designer probiotics, vitamin supplements, re-colonization methods, antibiotics, drugs that decrease intestinal permeability, and molecular interventions that block signaling pathways may emerge as adjunctive regimens that complement conventional immunosuppressive management. In conclusion, investigations of the intestinal microbiome are warranted in autoimmune hepatitis and promise to clarify pathogenic mechanisms and suggest alternative management strategies.

Wound healing of intestinal epithelial cells

The intestinal epithelial cells(IECs) form a selective permeability barrier separating luminal content from underlying tissues.Upon injury,the intestinal epithelium undergoes a wound healing process.Intestinal wound healing is dependent on the balance of three cellular events;restitution,proliferation,and differentiation of epithelial cells adjacent to the wounded area.Previous studies have shown that various regulatory peptides,including growth factors and cytokines,modulate intestinal epithelial wound healing.Recent studies have revealed that novel factors,which include toll-like receptors(TLRs),regulatory peptides,particular dietary factors,and some gastroprotective agents,also modulate intestinal epithelial wound repair.Among these factors,the activation of TLRs by commensal bacteria is suggested to play an essential role in the maintenance of gut homeostasis.Recent studies suggest that mutations and dysregulation of TLRs could be major contributing factors in the predisposition and perpetuation of inflammatory bowel disease.Additionally,studies have shown that specific signaling pathways are involved in IEC wound repair.In this review,we summarize the function of IECs,the process of intestinal epithelial wound healing,and the functions and mechanisms of the various factors that contribute to gut homeostasis and intestinal epithelial wound healing.

Inhibitory effect of oxymatrine on hepatocyte apoptosis via TLR4/PI3K/Akt/GSK-3β signaling pathway

AIM To evaluate the effect of oxymatrine(OMT) on hepatocyte apoptosis in rats with lipopolysaccharide(LPS)/D-galactosamine(D-Gal N)-induced acute liver failure(ALF). METHODS LPS/D-Gal N was used to establish a model of ALF in rats. To evaluate the effect of OMT, we assessed apoptosis by transmission electron microscopy, and the pathological changes in the liver by light microscopy with hematoxylin and eosin staining. An automated biochemical analyzer was used to measure serum alanine aminotransferase(ALT) and aspartate aminotransferase(AST). Enzyme-linked immunosorbent assay was used to determine the levels of tumor necrosis factor(TNF)-α and interleukin(IL)-1β. Western blotting was used to detect protein levels in liver tissues. Streptavidin peroxidase immunohistochemistry was used to observe expression of Toll-like receptor(TLR)4, active caspase-3, Bax and Bcl-2. RESULTS All rats in the normal control and OMT-pretreated groups survived. The mortality rate in the model group was 30%. OMT preconditioning down-regulated apoptosis of hepatocytes and ameliorated pathological changes in liver tissue. The levels of AST, ALT, TNF-α and IL-1β in the model group increased significantly, and were significantly reduced by OMT pretreatment. OMT pretreatment down-regulated expression of TLR4 and active caspase-3 and the Bax/Bcl-2 ratio, and upregulated expression of P-AktSer473(Akt phosphorylated at serine 473) and P-GSK3βSer9(glycogen synthase kinase 3β phosphorylated at serine 9) induced by LPS/D-Gal N. CONCLUSION OMT inhibits hepatocyte apoptosis by suppressing the TLR4/PI3K/Akt/GSK-3β signaling pathway, which suggests that OMT is an effective candidate for ameliorating acute liver failure.

Dysregulation of innate immunity in ulcerative colitis patients who fail anti-tumor necrosis factor therapy

AIM To study the innate immune function in ulcerative colitis(UC) patients who fail to respond to anti-tumor necrosis factor(TNF) therapy.METHODS Effects of anti-TNF therapy, inflammation and medications on innate immune function were assessed by measuring peripheral blood mononuclear cell(PBMC) cytokine expression from 18 inflammatory bowel disease patients pre- and 3 mo post-anti-TNF therapy. Toll-like receptor(TLR) expression and cytokine production post TLR stimulation was assessed in UC "responders"(n = 12) and "non-responders"(n = 12) and compared to healthy controls(n = 12). Erythrocyte sedimentation rate(ESR) and C-reactive protein(CRP) levels were measured in blood to assess disease severity/activity and inflammation. Pro-inflammatory(TNF, IL-1β, IL-6), immuno-regulatory(IL-10), Th1(IL-12, IFNγ) and Th2(IL-9, IL-13, IL-17A) cytokine expression was measured with enzyme-linked immunosorbent assay while TLR cellular composition and intracellular signalling was assessed with FACS.RESULTS Prior to anti-TNF therapy, responders and nonresponders had similar level of disease severity and activity. PBMC's ability to respond to TLR stimulation was not affected by TNF therapy, patient's severity of the disease and inflammation or their medication use. At baseline, non-responders had elevated innate but not adaptive immune responses compared to responders(P < 0.05). Following TLR stimulation, nonresponders had consistently reduced innate cytokine responses to all TLRs compared to healthy controls(P < 0.01) and diminished TNF(P < 0.001) and IL-1β(P < 0.01) production compared to responders. This innate immune dysfunction was associated with reduced number of circulating plasmacytoid dendritic cells(p DCs)(P < 0.01) but increased number of CD4+ regulatory T cells(Tregs)(P = 0.03) as well as intracellular accumulation of IRAK4 in non-responders following TLR-2,-4 and-7 activation(P < 0.001). CONCLUSION Reduced innate immunity in non-responders may explain reduced efficacy to anti-TNF therapy. These serological markers may prove useful in predicting the outcome of costly anti-TNF therapy.

Genetic polymorphism in CD14 gene, a co-receptor of TLR4 associated with non-alcoholic fatty liver disease

AIM To evaluate the pathogenic role of toll-like receptor(TLR) gene polymorphisms in patients with nonalcoholic fatty liver disease(NAFLD).METHODS Two hundred and fifty subjects(NAFLD = 200, healthy volunteers = 50) underwent polymerase chain reaction and restriction fragment length polymorphism to assess one polymorphism in the toll-like receptor 2(TLR2) gene(A753G), two polymorphisms in the TLR4 gene(TLR4 Asp299 Gly and Thr399 Ile allele), and two polymorphisms in the cluster of differentiation 14(CD14)(C-159 T and C-550T) gene, a co-receptor of TLR4. Association of TLR gene polymorphisms with NAFLD and its severity was evaluated by genetic models of association.RESULTS On both multiplicative and recessive models of gene polymorphism association, there was significant association of CD14 C(-159) T polymorphism with NAFLD; patients with TT genotype had a 2.6 fold increased risk of developing NAFLD in comparison to CC genotype. There was no association of TLR2 Arg753 Gln, TLR4 Asp299 Gly, Thr399 Ile, and CD14 C(-550) T polymorphisms with NAFLD. None of the TLR gene polymorphisms had an association with histological severity of NAFLD.CONCLUSION Patients with CD14 C(-159) T gene polymorphism, a co-receptor of TLR4, have an increased risk of NAFLD development.

May the assessment of baseline mucosal molecular pattern predict the development of gluten related disorders among microscopic enteritis?

AIM To evaluate mucosal baseline m RNA expression of tissue transglutaminase 2(t TG2), interferon gamma(IFNγ), toll-like receptor 2(TLR2) and Myeloid Differentiation factor 88(MyD 88) in patients with microscopic enteritis(ME).METHODS We retrospectively enrolled 89 patients with ME of different etiology, which was defined within a 2-year mean period of follow-up. Baseline histological examination was performed on Hematoxylin-Eosin stained sections and CD3 lymphocyte immunohistochemistry was used for intraepithelial lymphocyte count(IELs). ME was defined according to the criteria of Bucharest Consensus Conference. For each patient, formalin embedded biopsy samples of the duodenum referred to the period of ME diagnosis were retrieved. Real-time polymerase chain reaction(RT-PCR) was used to detect the amount of mR NA coding for tT G2, IFNγ, TLR2 and My D88, and the quantity was expressed as fold change compared to controls. Control group was represented by duodenal normal specimens from 15 healthy subjects undergoing endoscopy for functional symptoms. Comparisons among continuous variables were performed by One way analysis of variance(ANOVA) and Bonferroni’s test. The χ~2 test was used for categorical variables. Pearson’s test was used to evaluate correlations. Receiver operating curves were drawn for all four markers to estimate sensitivity and specificity in discriminating the development of CD and GS.RESULTS After a period of follow up of 21.7 ± 11.7 mo, the following diagnoses were achieved: gluten related disorders in 48 subjects(31 CD; 17 GS) and non-gluten related ones in 41(29 Irritable Bowel Syndrome- IBS; 12 Others). CD patients had the highest tT G2 levels(8.3 ± 4.5). The ANOVA plus Bonferroni analysis showed that CD > Other ME > GS = IBS > negative controls. A cut off value of 2.258 was able to discriminate between CD and GS with a sensitivity of 52.94% and a specificity of 87.1%. Additionally, CD patients had the highest IFNγ levels(8.5 ± 4.1). ANOVA plus Bonferroni demonstrated CD > Other ME > GS = IBS > negative controls. A cut off of 1.853 was able to differentiate CD and GS with a sensitivity of 47.06% and a specificity of 96.77%. Patients with non gluten-related causes of ME exhibited the highest TLR2 levels(6.1 ± 1.9) as follows: Other ME > CD = GS = IBS > negative controls. TLR2 was unable to discriminate CD from GS. Patients with CD overexpressed MyD 88 levels similarly to non gluten-related causes of DL(7.8 ± 4.9 and 6.7 ± 2.9), thus CD = Other ME > GS = IBS > negative controls. A cut off of 3.722 was able to differentiate CD from GS with a sensitivity of 52.94% and a specificity of 74.19%. IELs count(15-25 and more than 25/100 enterocytes) strongly correlated with mR NA levels of all tested molecules(P < 0.0001).CONCLUSION Our results confirm that a single marker is unable to predict a discrimination among ME underlying conditions as well as between CD and GS. Mucosal high levels of t TG and IFNγ m RNA may predict the development of CD more than GS with high specificity, despite an expected low sensitivity. TLR2 does not discriminate the development of CD from GS. My D88 levels indicate that intestinal permeability is more increased when a severe intestinal damage underlies ME in both gluten related and unrelated conditions. Therefore, the results of the present paper do not seem to show a clear translational value.

Association between TLR7 copy number variations and hepatitis B virus infection outcome in Chinese

AIM To explore whether copy number variations (CNVs) of toll-like receptor 7 (TLR7) are associated with susceptibility to chronic hepatitis B virus (HBV) infection.METHODS This study included 623 patients(495 males and 128 females) with chronic hepatitis B virus infection(CHB) and 300 patients (135 females and 165 males) with acute hepatitis B virus infection (AHB) as controls. All CHB patients were further categorized according to disease progression after HBV infection (CHB, liver cirrhosis, or hepatocellular carcinoma). Copy numbers of the TLR7 gene were measured using the Accu Copy method. χ2 tests were used to evaluate the association between TLR7 CNVs and infection type. P values, odds ratios, and 95% confidence intervals(CIs) were used to estimate the effects of risk. RESULTS A m o n g m a l e p a t i e n t s, t h e r e w e r e s i g n i f i c a n t differences between the AHB group and CHB group in the distribution of TLR7 CNVs. Low copy numberof TLR7 was significantly associated with chronic HBV infection (OR = 0.329, 95%CI: 0.229-0.473, P < 0.001). Difference in TLR7 copy number was also found between AHB and CHB female patients, with low copy number again associated with an increased risk of chronic HBV infection (OR = 0.292, 95%CI: 0.173-0.492, P < 0.001). However, there were no significant differences in TLR7 copy number among the three types of chronic HBV infection (CHB, liver cirrhosis, or hepatocellular carcinoma). In addition, there was no association between TLR7 copy number and titer of the HBV e antigen.CONCLUSION Low TLR7 copy number is a risk factor for chronic HBV infection but is not associated with later stages of disease progression.

Involvement of Cbl-b-mediated macrophage inactivation in insulin resistance

Aging and overnutrition cause obesity in rodents and humans. It is well-known that obesity causes various diseases by producing insulin resistance(IR). Macrophages infiltrate the adipose tissue(AT) of obese individuals and cause chronic low-level inflammation associated with IR. Macrophage infiltration is regulated by the chemokines that are released from hypertrophied adipocytes and the immune cells in AT. Saturated fatty acids are recognized by toll-like receptor 4(TLR4) and induce inflammatory responses in AT macrophages(ATMs). The inflammatory cytokines that are released from activated ATMs promote IR in peripheral organs, such as the liver, skeletal muscle and AT. Therefore, ATM activation is a therapeutic target for IR in obesity. The ubiquitin ligase Casitas b-lineage lymphoma-b(Cbl-b) appears to potently suppress macrophage migration and activation. Cbl-b is highly expressed in leukocytes and negatively regulates signals associated with migration and activation. Cbl-b deficiency enhances ATM accumulation and IR in aging- and diet-induced obese mice. Cbl-b inhibits migration-related signals and SFA-induced TLR4 signaling in ATMs. Thus, targeting Cbl-b may be a potential therapeutic strategy to reduce the IR induced by ATM activation. In this review, we summarize the regulatory functions of Cbl-b in ATMs.

Hyaluronic acid as a rescue therapy for trinitrobenzene sulfonica cid-induced colitis through Cox-2 and PGE_2 in a Toll-like receptor 4-dependent way

We hypothesized whether systemic administration of high-molecular-weight hyaluronic acid(HMW HA) could rescue trinitrobenzene sulfonic acid(TNBS)-induced colitis through Toll-like receptor 4(TLR4) signal.C3H/HeN mice and C3H/HeJ mice were used.Mice were divided into four groups:control,50% ethanol treatment group,TNBS treatment group,and TNBS plus HA treatment group.The weight changes,clinical scores,macroscopic scores,and histological scores were recorded.Cyclooxygenase 2(Cox-2) and prostaglandin E 2(PGE 2) expressions were measured both in colons and peritoneal macrophages from these mice.HA was a rescue therapy for the colitis induced by TNBS only in C3H/HeN mice.The clinical score,macroscopic score,and histological score were much lower in C3H/HeN mice receiving TNBS plus HA treatment.Cox-2 and PGE 2 expressions only increased in C3H/HeN mice.These Cox-2 expressing cells were macrophages.HA can also promote the production of Cox-2 and PGE 2 in peritoneal macrophages from C3H/HeN mice.Our data demonstrated that HMW HA can rescue TNBS-induced colitis through inducing Cox-2 and PGE 2 expressions in a TLR4-dependent way.Macrophages may be the effector cells of HMW HA.