Characterization of the intrahepatic immune microenvironment and gene expression profile in hepatitis B and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) and hepatitis B virus (HBV) infection remain significant global health challenges, often leading to complications such as cirrhosis, liver failure, and increased mortality. The liver microenvironment plays a crucial role in the course of chronic hepatitis B (CHB), the progression of HCC, and the clinical outcomes of treatments like selective internal radiation therapy (SIRT). However, the immune mechanisms within the liver are poorly understood. My project aimed to characterize the liver microenvironment in these patients, focusing on immune cell infiltration, gene expression profiles, and the impact on treatment responses and survival outcomes. In the first project, I studied a cohort of HBV patients classified into different clinical phases, including the “gray zone” (GZ), by transcriptomic analyses that revealed significant immune activation in active phases and GZ. These patients showed up-regulation of genes involved in adaptive immune processes such as T and B cell activation. This result highlights the need for closer monitoring and potential early intervention treatment in GZ patients, as the risk of liver fibrosis progression and HCC development remains high. In the second project, I study the immune profile of patients with HCC before and after treatment by radioembolization. First, we examined the tumor microenvironment of patients before undergoing SIRT to evaluate its influence on treatment response. An unsupervised hierarchical clustering analysis identified two clusters of patients. Cluster 1 was associated with gene expression profiles related to immune response activation, while Cluster 2 was linked to cell proliferation and differentiation. These findings align with previous research suggesting that SIRT, similar to external radiotherapy, may trigger the release of pro-inflammatory mediators, transforming immunologically "cold" tumors into "hot" tumors. This process may boost the effectiveness of combining SIRT with immunotherapy, offering new treatment options for patients with HCC in the intermediate/advanced stage. Second, we analyzed the tumor microenvironment of 25 patients who underwent surgery post-SIRT,40% of whom achieved a complete radiological response (CR). Transcriptomic analysis revealed distinct differences in immune responses between responders and non-responders. CR patients showed a significant downregulation of immune response pathways. In contrast, non-responders exhibited increased immune infiltration and over-expression of genes associated with aggressive HCC subtypes, characterized by poor differentiation, higher AFP levels, and microvascular invasion. Interestingly, the study identified a proinflammatory tumor microenvironment in non-responders, marked by elevated levels of chemokines and pathways involved in tumor progression and immune regulation. This immune landscape was linked to a higher risk of recurrence post-surgery, suggesting that these patients might benefit from the addition of immunotherapy to enhance anti-tumor responses and reduce recurrence risk. In contrast, CR patients demonstrated a more controlled immune response, potentially explaining their favorable outcomes. In conclusion, this project highlights the importance of the liver tumor microenvironment in determining clinical outcomes for HBV and HCC patients. The immune activity observed in GZ patients suggests that expanded antiviral treatment options could mitigate the risk of liver disease progression and carcinogenesis. Meanwhile, the differing immune responses between SIRT responders and non-responders underscore the importance of personalized treatment strategies, particularly in the context of combination treatment with the integration of immunotherapy in high-risk HCC cases. Ongoing research into the immune and molecular mechanisms within the liver microenvironment will be crucial in refining therapeutic approaches, ultimately improving patient outcomes.