Polymorphisms of HLA-DM on Treatment Response to Interferon/Ribavirin in Patients with Chronic Hepatitis C Virus Type 1 Infection

Revisiting nonclassical HLA II functions in antigen presentation: Peptide editing and its modulation

The nonclassical major histocompatibility complex of class II molecules (ncMHCII) HLA-DM (DM) and HLA-DO (DO) feature essential functions for the selection of the peptides that are displayed by classical MHCII proteins (MHCII) for CD4⁺ T_h cell surveillance. Thus, although the binding groove of classical MHCII dictates the main features of the peptides displayed, ncMHCII function defines the preferential loading of peptides from specific cellular compartments and the extent to which they are presented. DM acts as a chaperone for classical MHCII molecules facilitating peptide exchange and thereby favoring the binding of peptide-MHCII complexes of high kinetic stability mostly in late endosomal compartments. DO on the other hand binds to DM blocking its peptide-editing function in B cells and thymic epithelial cells, limiting DM activity in these cellular subsets. DM and DO distinct expression patterns therefore define specific antigen presentation profiles that select unique peptide pools for each set of antigen presenting cell. We have come a long way understanding the mechanistic underpinnings of such distinct editing profiles and start to grasp the implications for ncMHCII biological function. DM acts as filter for the selection of immunodominant, pathogen-derived epitopes while DO blocks DM activity under certain physiological conditions to promote tolerance to self. Interestingly, recent findings have shown that the unexplored and neglected ncMHCII genetic diversity modulates retroviral infection in mouse, and affects human ncMHCII function. This review aims at highlighting the importance of ncMHCII function for CD4⁺ T_h cell responses while integrating and evaluating what could be the impact of distinct editing profiles because of natural genetic variations.

Association between human leucocyte antigen-DO polymorphisms and interferon/ribavirin treatment response in hepatitis C virus type 1 infection in Chinese population: a prospective study

OBJECTIVE

The human leucocyte antigen-DO (HLA-DO) gene located in the HLA non-classical class-II region may play a role in treatment response to hepatitis C virus (HCV). This study was conducted to explore the role of single nucleotide polymorphisms (SNPs) in HLA-DO in responding to HCV therapy.

SETTING

All patients were recruited between January 2011 and September 2016 from the Jurong People's Hospital, Jiangsu Province, China.

PARTICIPANTS

A total of 346 chronic hepatitis C (CHC) patients who finished the 48-week pegylated interferon-alpha and ribavirin (PEG IFN-α/RBV) treatment were enrolled in this study. All patients were former remunerated blood donors. The inclusion criteria for patients were as follows: (1) treatment-naive and treated with PEG IFN-α/RBV, (2) HCV RNA was present in serum for over 6 months before treatment, (3) negative for hepatitis B (HBV) or HIV infection and (4) lacked any other hepatic diseases.All participants in this study were Chinese Han population and infected with HCV genotype 1b and treated with subcutaneous PEG IFN-α at a dose of 180 µg once a week with the addition of 800-1000 mg/d RBV according to weight orally for 48 weeks.

RESULTS

The SNPs HLA-DOA rs1044429 and HLA-DOB rs2284191 and rs2856997 of 18 SNPs were correlated with HCV treatment response in the Chinese Han population. The dominant model indicated that patients carrying favourable genotypes at rs1044429 AA and rs2284191 AA were more likely to achieve sustained virological response (SVR) (OR 1.99, 95% CI 1.25 to 3.19; OR 2.71, 95% CI 1.58 to 4.63, respectively), while patients carrying unfavourable genotypes at rs2856997 GG were less likely to achieve SVR (OR 0.48, 95% CI 0.29 to 0.78).

CONCLUSION

Genetic variations at rs1044429, rs2284191 and rs2856997 were independent predictors of HCV treatment response in the Chinese Han population.

Research progress on the direct antiviral drugs for hepatitis C virus

Hepatitis C, caused by the hepatitis C virus (HCV) that attacks the liver and leads to inflammation, is a severe threat to human health. Pegylated interferon α (INF-α) and ribavirin based therapy was once the standard therapy for HCV infection. However, it is suboptimal in efficacy and poorly tolerated in some patients. In the last five years, four classes of direct antiviral drugs (NAAs) that target non-structural proteins (NS) of the virus including NS3/NS4A, NS5A, and NS5B have been developed and opened a new era in HCV treatment as they are more effective and tolerable than the INF-α and ribavirin combination regimen. Importantly, the newly introduced multiple NAAs combination therapy makes it possible to eradicate all genotypes of HCV. We review recent progress on the research and development of DAAs in the present article.