Researchers at the Helmholtz Centre in Braunschweig demonstrate how the immune system reacts to a hepatitis B infection.
Hepatitis B is the most prevalent infectious disease in the world. It results in either an acute infection or, in rare cases, it can develop into a chronic disease. Researchers at the Helmholtz Centre for Infection Research (HZI) in Braunschweig have now examined the way in which the immune system reacts differently to both chronic and acute hepatitis B. To achieve this, Carlos A. Guzmán, Head of the "Vaccinology and Applied Microbiology" working group and Robert Geffers, Head of the "Gene Expression Analysis" platform, examined the incidence and species of special defence cells, T helper cells, along with their role in the development of the disease in conjunction with their Indian colleagues. With the aid of genetic analysis, they showed how the genes in these immune cells are regulated differently according to the development of the disease. These new results can help doctors to discover whether an infection is curable or whether by settling in the liver, it will develop into a chronic case. These results are now published in the scientific journal, "Hepatology".
Approximately 300 to 420 million people (5 to 7% of the world's population) have a chronic hepatitis B infection. India is one of the countries, in which hepatitis B is very common. A differentiation is made with the development of the disease between acute and chronic hepatitis B. The most common symptom of an acute infection is jaundice. In 5% of the infections, the disease becomes chronic, that is to say, the viruses remain in the liver. If left untreated, chronic hepatitis B can lead to a change in consciousness, cirrhosis and cancer of the liver. Until today scientists have not fully understood the role that the immune system plays in characterising an acute or chronic hepatitis B infection.
A decisive factor in achieving an appropriate immune reaction is the quick mobilisation of immune cells. These specifically attack the infected liver cells without destroying any unnecessary liver tissue in the process. Subspecies of the T helper cells play a decisive role in achieving this necessary balance between immunological defence and tolerance: effector T cells and regulatory T cells (Treg). Whilst the effector T cells fight a virus infection and kill off the infected host cells, the Treg cells shut down an immune reaction and cut off the effector T cells. They counteract any destruction of the tissue.
The international team of research scientists examined how these T helper cells influence the development of the hepatitis B disease. To this end, they took blood samples from Indian patients with hepatitis B and compared the extent to which the altered incidence of the T cell subsets in the blood influences the development of the illness and which genes are responsible for this.