Reducing ‘cytokine storm’ in flu victims

World Health Matters: Australia by Gary Finnegan – Highly virulent forms of the influenza virus can cause serious illness and may be fatal. Some of the damage is caused by a particularly strong immune response, especially in the lungs. Scientists are working to understand this immune reaction in order to reduce the most severe consequences of flu infection.

A new study published in PLOS Pathogens identifies the SOCS4 protein as a key regulator of the immune response, suggesting it could be a target for immunotherapy. Researchers from the Institute of Medical Research and the University of Melbourne studied mice with a mutation in the gene which codes for the SOCS4 protein and tested how they responded to infection with a virulent strain of influenza.

Compared to normal mice, the mutants were more sensitive to the virus; they got much sicker and were at higher risk of death. Even when exposed to a weaker virus, the mutant mice showed more severe symptoms than normal mice.

The mutant mice responded to influenza virus with abnormally high levels of cytokines and chemokines – biochemical that promote inflammation. This ‘cytokine storm’ is thought to cause the lung tissue damage associated with virulent influenza strains. Such research may help to deepen understanding of how the immune system can over-react to flu.

A separate study by Germany researchers highlights the importance of IL-27, a cytokine, in reducing damage to the lung tissue caused by the immune system.

Alf Hamann, from Deutsches Rheuma-Forschungszentrum and Charité Universitätsmedizin Berlin, Germany, and colleagues, found that mice with disrupted IL-27 function were more likely than normal mice likely to die when infected with the flu virus, and that they died as a consequence of rampant lung inflammation.

The authors suggest that well-timed IL-27 application could help to treat life-threatening inflammation during lung infection.