When acute hepatitis develops into chronic hepatitis

[Guest guest]

http://www.eurekalert.org/pub_releases/2009-02/haog-wah021609.php

Public release date: 16-Feb-2009

[ Print Article | E-mail Article | Close Window ]

Contact: Dr. Bastian Dornbach

bad@...

49-053-161-811-407

Helmholtz Association of German Research Centres

When acute hepatitis develops into chronic hepatitis

Researchers at the Helmholtz Center in Braunschweig demonstrate how the immune

system reacts to a hepatitis B infection

To achieve this, A. Guzmán, Head of the " Vaccinology and Applied

Microbiology " working group and 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.

Guzman's and Geffers's teams were able to show that, with acute hepatitis B, the

effector T cells are extremely active and destroy infected host cells. Treg

cells prevent effector T cells damaging healthy liver tissue during this stage

of the infection. On the other hand, T effector cells are largely inactive with

chronic hepatitis B infections: the Treg cells prevent an immune reaction and,

in doing so, increase the number of hepatitis B viruses that are able to live in

the organ. The immune system's constant struggle against the virus leads to a

slow destruction of the liver tissue. The researchers checked their observations

with gene activity: They demonstrated that more that one hundred genes in

effector T cells are regulated differently in an immune reaction to acute

hepatitis B than to a chronic case.

" The molecular mechanisms and the specific gene activities of a hepatitis B

infection were unknown up until now. We now have a much better understanding of

how acute and chronic hepatitis B infections develop and which processes are

involved " , says A. Guzmán. " With gene analysis we are able to further

investigate the molecular links, which, in many ways, are a reason for the

clinical observations " . The doctor thus has an opportunity to improve his

diagnosis with so-called " marker genes " and to improve his treatment of the

patients with targeted, immunotherapeutic measures " , says Geffers, who

conducted the gene analysis of the blood tests.

###

[Guest guest]

http://www.eurekalert.org/pub_releases/2009-02/haog-wah021609.php

Public release date: 16-Feb-2009

[ Print Article | E-mail Article | Close Window ]

Contact: Dr. Bastian Dornbach

bad@...

49-053-161-811-407

Helmholtz Association of German Research Centres

When acute hepatitis develops into chronic hepatitis

Researchers at the Helmholtz Center in Braunschweig demonstrate how the immune

system reacts to a hepatitis B infection

To achieve this, A. Guzmán, Head of the " Vaccinology and Applied

Microbiology " working group and 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.

Guzman's and Geffers's teams were able to show that, with acute hepatitis B, the

effector T cells are extremely active and destroy infected host cells. Treg

cells prevent effector T cells damaging healthy liver tissue during this stage

of the infection. On the other hand, T effector cells are largely inactive with

chronic hepatitis B infections: the Treg cells prevent an immune reaction and,

in doing so, increase the number of hepatitis B viruses that are able to live in

the organ. The immune system's constant struggle against the virus leads to a

slow destruction of the liver tissue. The researchers checked their observations

with gene activity: They demonstrated that more that one hundred genes in

effector T cells are regulated differently in an immune reaction to acute

hepatitis B than to a chronic case.

" The molecular mechanisms and the specific gene activities of a hepatitis B

infection were unknown up until now. We now have a much better understanding of

how acute and chronic hepatitis B infections develop and which processes are

involved " , says A. Guzmán. " With gene analysis we are able to further

investigate the molecular links, which, in many ways, are a reason for the

clinical observations " . The doctor thus has an opportunity to improve his

diagnosis with so-called " marker genes " and to improve his treatment of the

patients with targeted, immunotherapeutic measures " , says Geffers, who

conducted the gene analysis of the blood tests.

###