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Study shows unexpected immune activity in chronic hepatitis B / New approach to treating the previously incurable disease / Around 257 million people affected worldwide

Researchers at the Faculty of Medicine - University of Freiburg have gained surprising insights into the immune response in chronic hepatitis B (HBV). Contrary to previous assumptions, some of the immune cells that destroy virus-infected body cells are also active in chronic hepatitis B infection. They can continue to actively contribute to controlling the viral infection. The study, which the researchers from the Medical Center - University of Freiburg published in Nature Immunology on August 28, 2024, thus offers new therapeutic approaches. Around 257 million people worldwide suffer from the previously incurable chronic viral infection, around 16,000 people in Germany alone.

"Our results offer new insights into the mechanisms of the immune response in chronic hepatitis B infection," says Prof. Dr. Robert Thimme, Medical Director of the Department of Medicine II at the Medical Center - University of Freiburg. "In particular, the role of cytotoxic T cells, formerly known as T killer cells, could be important for future therapeutic strategies."

Quiet does not mean powerless: T cells are weaker, but still active

Under the direction of Thimme and Heisenberg Professor Prof. Dr. Maike Hofmann, Head of the Translational Experimental Immunology Section at the Department of Medicine II, the research team investigated the properties of these T cells in more detail. They analyzed immune cells from patients with chronic hepatitis B. The team identified a subgroup of cells that continue to play a role in fighting the virus despite a weakened immune response. These cells attack virus-infected cells, but not as intensively as in an acute virus infection.

The researchers compare the immune system to an orchestra: at the beginning of the infection, all cellular players play their instruments loudly and clearly. In the course of a chronic infection, some members of the orchestra "run out of breath" and can no longer make music. The cells that have now been identified, on the other hand, continue to play, albeit more quietly. "The discovery of these special T cells gives us a deeper insight into the complex processes of the immune response in chronic HBV infection. Our hope now is that the development of new therapies will allow these cells to play 'loudly' again and thus expel the virus," says Hofmann. "However, we are only at the very beginning."

Original title of the publication: "Attenuated effector T cells are linked to control of chronic HBV infection"
DOI: 10.1038/s41590-024-01928-4
Link to the study: https://www.nature.com/articles/s41590-024-01928-4