Hemorrhagic Fever Circulatory collapse now preventable?

Hope for new therapeutic approaches to haemorrhagic fever
In various viral infections such as Ebola infections, a hemorrhagic fever is part of the symptoms that includes high fever and internal bleeding, liver and kidney damage. Often this virus infection leads to a fatal circulatory shock.

Scientists at the University of Basel have now been able to identify messenger substances of the immune system that lead to shock states in mice with hemorrhagic fever. By blocking the messenger substances, according to the researchers new possibilities for the treatment of haemorrhagic fever are opened. The scientists have published their results in the journal "Cell Host & Microbe".

Hemorrhagic fever is the result of certain viral infections and often leads to a fatal circulatory collapse. (Image: psdesign1 / fotolia.com)

Deadly circulatory failure threatens
Hemorrhagic fever can be triggered by various viral infections. These include infections with the lavavirus of the arenavirus family, which is transmitted to humans by rodents in West Africa and causes tens of thousands of haemorrhagic fever deaths annually, the researchers explain. In the final stage, it often comes to shock states or a fatal circulatory failure, but the underlying mechanisms so far remained largely unclear.

Excessive inflammatory reaction the cause
The research team led by Prof. Daniel Pinschewer from the Department of Biomedicine at the University of Basel has investigated the causes of the onset of shock conditions in haemorrhagic fever and found that an excessive inflammatory response, which is caused by the viruses, an important cause of circulatory failure after arenavirus infections.

Paradoxically, immune cells contribute to the onset of the disease
In earlier work, the group around Prof. Pinschewer had already shown that the immune cells in the infection with the Lassavirus can paradoxically contribute to the disease. In viral infections, T cells play a central role in our body's defense, but over-zealous T cells apparently stimulate phagocytes to produce large amounts of nitric oxide (NO) during arenavirus infection. Although this is an important defense mechanism for bacterial infections, but does not help against viruses, explain the scientists.

If the messenger substance is blocked, no circulatory collapse occurs
In experiments on arenavirus-infected mice, it became clear that nitric oxide dilates the blood vessels, leading to the exudation of fluid into the tissue, causing a decrease in effective blood volume and ultimately a circulatory collapse. The scientists were also able to show that the NO production of the messenger's phagocytes requires interferon-gamma, as produced by T-cells. If "this messenger substance was blocked by medication, the mice remained susceptible to the virus infection, but they suffered no circulatory collapse and survived largely unscathed," said the University of Basel.

Hope for timely improvements in therapy
To date, the treatment options for Lassavirus infection and other viral haemorrhagic fevers remain inadequate according to the researchers. But the current study results give reason for hope. Because drugs for blocking interferon-gamma or its effect are already being used in humans, and the results of the present study could now help ensure that these drugs are also used successfully in the future for the treatment of haemorrhagic fever. (Fp)