Hepatic Toll-Like Receptor 3 expression in chronic hepatitis C genotype 1 correlates with treatment response to peginterferon plus ribavirin

Pattern Recognition Receptors: Significance of Expression in the Liver

Pattern recognition receptors (PRRs) are a pivotal part of the immune system. They are distributed in almost every site of higher organisms, able to recognize foreign pathogens or unwanted remnants of metabolism and mount innate immune response. Moreover, PRRs create bridging signaling to initiate adaptive immunity. The liver being the largest organ of the body, exposed to myriads of foreign substances often being immunogenic, is well equipped with PRRs. They act as sentinels of the organ, both in health and disease. In viral hepatitis C at least two of them, RIG-1 and TLR3 sense HCV, induce protective interferon production and create proinflammatory status. The hepatitis B virus is apparently invisible to PRRs, which has recently been denied. Besides, they are active in the course of infection. In liver injury and hepatic fibrogenesis Toll-like receptors (TLRs), predominantly TLR4, TLR3 and TLR9 are associated with gut microflora-related products and DNA from dying hepatocytes, lead to the activation of hepatic stellate cells. The latter initiate production of fibrillar collagens, the main agents forming hepatic fibrosis. Tumor cells of primary liver cancer also express PRRs, mainly TLRs. In concert with non-resolving liver inflammation, they are considered pivotal factors leading to carcinogenesis.

Peripheral blood toll-like receptor 4 correlates with rapid virological response to pegylated-interferon and ribavirin therapy in hepatitis C genotype 1 patients

BACKGROUND

Toll-like receptors (TLRs) are effectors of the innate immune system that are able to recognize hepatitis C virus (HCV) and give rise to an immune response. Failure of interferon (IFN)-α-based treatment is related to host immunity. Therefore, we sought to study the clinical importance of TLRs in HCV genotype 1 patients who received pegylated IFN (PEG-IFN) plus ribavirin (RBV) therapy.

METHODS

We enrolled 79 treatment-naïve patients with HCV genotype 1. Patients completed a 24- to 48-week course of response-guided therapy. Peripheral blood monocyte (PBMC) expression of mRNA for TLRs 2, 3, 4, 7, and 9 was quantified by real-time PCR before therapy. TLR mRNA expression is shown as a log ratio relative to GAPDH mRNA (log 2 (-(∆Ct))).

RESULTS

Forty-five patients (57.0 %) showed a rapid virological response (RVR). Univariate analysis revealed that TLR 2, 3, 4, 7, and 9 were significantly lower in the RVR group than in the non-RVR group (P = 0.001, 0.014, < 0.001, 0.008, and 0.001, respectively). Multivariate analysis revealed that TLR 4 < -2 log (OR: 7.17, 95 % CI: 1.70-30.34, P = 0.007) was an independent predictor for RVR. In addition, levels of TLR 2, 3, 4, 7, and 9 were positively correlated with HCV viral load (P = 0.009, 0.013, < 0.001, 0.007, and 0.001, respectively).

CONCLUSIONS

A low level of TLR 4 mRNA in PMBCs was correlated with RVR, which indicates that TLR4 may play a critical role in HCV recognition and activation of innate immunity. TLR expression levels were correlated with HCV viral load, indicating that TLR activation upon exposure to HCV may subsequently limit HCV replication.

Regulatory phenotype, PD-1 and TLR3 expression in T cells and monocytes from HCV patients undergoing antiviral therapy: a randomized clinical trial

BACKGROUND & AIMS

The cellular immunity has a profound impact on the status of hepatitis C virus (HCV) infection. However, the response of cellular immunity on the virological response in patients with antiviral treatment remains largely unclear. We aimed to clarify the response of peripheral T cells and monocytes in chronic hepatitis C patients with antiviral treatment.

METHODS

Patients with chronic hepatitis C were treated either with interferon alpha-2b plus ribavirin (n = 37) or with pegylated interferon alpha-2a plus ribavirin (n = 33) for up to 24 weeks. Frequencies of peripheral regulatory T-cells (Tregs), programmed death-1 (PD-1) expressing CD4+ T-cells or CD8+ T-cells and toll-like receptor (TLR) 3 expressing CD14+ monocytes were evaluated by flow cytometry in patients at baseline, 12 and 24 weeks following treatment and in 20 healthy controls.

RESULTS

Frequencies of Tregs, PD-1 and TLR3 expressing cells were higher in patients than those in control subjects (P<0.05). Patients with complete early virological response (cEVR) showed lower Tregs, PD-1 expressing CD4+ or CD8+ T-cells than those without cEVR at 12 weeks (P<0.05). Patients with low TLR3 expressing CD14+ monocytes at baseline had a high rate of cEVR (P<0.05).

CONCLUSIONS

Low peripheral TLR3 expressing CD14+ monocytes at baseline could serve as a predictor for cEVR of antiviral therapy in chronic HCV-infected patients. The cEVR rates were significantly increased in the patients with reduced circulating Tregs, PD-1 expressing CD4+ or CD8+ T-cells.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR10001090.

Involvement of Differential Relationship between HCV Replication and Hepatic PRR Signaling Gene Expression in Responsiveness to IFN-Based Therapy

Aim. To gain an insight into the effect of HCV replication-associated interference with the IFN system on hepatic mRNA expression involved in IFN production. Methods. Relative mRNA expression of TLR3/RIG-I signaling genes involved in IFN-β production was correlated with positive- and negative-strand HCV RNAs in pretreatment liver tissues responsive and nonresponsive to peginterferon and ribavirin for chronic hepatitis C genotype 1. Treatment response was analyzed for per protocol population at weeks 12 (n = 45) and 24 (n = 40) and at 24 weeks aftertreatment (n = 38). Results. HCV replication had no relation to the expression of TLR3, RIG-I, TRIF, IPS-1, IRF3, and IFN-β mRNAs in responders. In striking contrast, positive- and/or negative-strand HCV showed positive correlations with TLR3, RIG-I, TRIF, IPS-1, and IRF3 mRNAs in week-12 nonresponders; with RIG-I, TRIF, IPS-1, and IRF3 mRNAs in week-24 nonresponders; and with TLR3, RIG-I, and IRF3 mRNAs in posttreatment nonresponders. Thus mRNA expression of TLR3/RIG-I signaling genes was increased in relation to viral replication in nonresponders. Conclusions. The findings in IFN nonresponders may imply a host feedback response to severe impairment of the IFN system associated with HCV replication.

Toll like receptor 3 expression as a novel predictor of response to treatment in chronic hepatitis C virus patients

PURPOSE

This work was carried out to study the level of pretreatment hepatic expression of Toll like receptor 3 (TLR3) among chronic HCV patients, aiming to determine if there are consistent differences in gene expression, between those who show complete early virological response (cEVR) at week-12 of Pegylated-Interferon α-2a plus ribavirin treatment and others who are not responding to this combination, also if this could be used to predict treatment outcomes.

METHOD

A total of 61 chronic hepatitis C patients were enrolled in the study. For all of them, baseline hepatitis C virus (HCV) viral load was determined and TLR3 gene expression was examined in their hepatic percutaneous needle biopsy specimens using a real time-polymerase chain reaction technique. Hepatic TLR3 was also traced using immunohistochemistry. All patients followed a 12-week regimen of Pegylated-Interferon α-2a plus ribavirin then post-treatment viral load was assayed.

RESULTS

Hepatic expression of TLR3 was significantly increased in the non-responder group as compared to those who showed complete early virological response to the used treatment regimen. Using receiver operator characteristic (ROC) curve analysis, a cutoff level of 1.5 was set for TLR3 expression to distinguish responders from non-responders to the 12-week treatment regimen used.

CONCLUSION

In conclusion, measuring the hepatic expression of the interferon stimulated gene, TLR3 could provide a new molecular marker for pre-treatment prediction of complete early viral clearance, thus helping in patients' selection and optimizing treatment outcomes.

Early interferon-based treatment after detection of persistent hepatitis C virus infection: a critical decision

Approximately 170 million people are infected with the hepatitis C virus (HCV) worldwide. Infection with this pathogen is persistent in more than 80% of cases, frequently developing severe forms of liver damage such as cirrhosis and hepatocellular carcinoma. No preventive vaccine is available against HCV, and current treatment based on the combination of pegylated interferon and ribavirin is effective in ∼55% of patients infected with genotype 1, the most prevalent genotype. This review analyzes several factors influencing the achievement of a sustained virological response, namely undetectable HCV RNA at 6 months after conclusion of therapy. Particularly, the relevant issue of age and duration of infection is discussed in detail. Indeed, the final decision for starting treatment should be a case-by-case point. However, the cost-benefit analysis seems to indicate that in patients who are motivated and without contraindications, starting the treatment as early as possible is probably the best choice for success.