Inflammatory and oncogenic gene signatures in chronic hepatitis delta infection

Abstract

Background and aims: Hepatitis delta virus (HDV) causes the most severe form of chronic viral hepatitis due to rapid progression towards end-stage liver disease including cirrhosis and hepatocellular carcinoma (HCC). Factors driving disease acceleration need to be investigated to prevent advanced disease progression. We aimed to identify molecular signatures predicting the rapid onset of severe hepatic ailment in chronic HDV infection.

Method: We investigated peripheral blood transcriptomic profiles in chronic HBV and HDV coinfected (CHB/CHD-coinfection) patients and compared with CHB-monoinfection matched for liver fibrosis to recognize gene signatures associated with CHD-induced disease progression. Multiplex cytokine bead array and flow cytometry assays were performed to validate RNAseq and examine the markers of inflammation, fibrosis and immune exhaustion.

Results: Transcriptomic profile revealed significant upregulation of genes related to inflammation, oncogenesis, tumor growth, invasion, metastasis and inhibition of anti-tumor response such as CXCL2, 3, 8, TNFSF9, IFITM1, IL-17, IGHA2, AREG, SEMA3F, CSF1R, TREML4, ANGPTL4 and LILRB2 in CHB/CHD-coinfection than CHB-monoinfection. Interestingly, none of CHB/CHD-coinfected patients we analyzed had cirrhosis or HCC, yet these patients experienced significant elevation of inflammatory and oncogenic genes, indicating HDV triggers these genes much before the onset of cirrhosis or HCC that contributes to rapid disease acceleration towards end-stage disease. Analysis of the top canonical pathways further confirmed the association of these differentially expressed genes in severe inflammatory response and oncogenic process. ELISA further confirmed induction of inflammatory and fibrogenic cytokines (IL-17, CXCL2, CXCL13 and TGF-β) in the plasma of CHB/CHD-coinfection. Additionally, these patients experienced severe immune exhaustion in effector T cell (CD4 and CD8) compartment by displaying higher inhibitory receptors PD-1 and TIGIT, which then resulted in poor antiviral response in terms of IFN-gamma, TNF-alpha, perforin and granzyme B secretion along with impaired polyfunctional responses against HBV and HDV than CHB-moninfection alone.

Conclusion: HDV coinfection leads to a dichotomous immune response, whereby suppressing antiviral (HBV and HDV-specific) T cell immunity, while having an exaggerated inflammatory and oncogenic responses resulting in accelerated liver disease progression, cirrhosis and HCC.