Scientists identify key protein driving severe flu in older people

Scientists have discovered why older people are more likely to suffer severely from the flu, and can now use their findings to address this risk.

In a new study, which is published in PNAS, experts discovered that older people produce a glycosylated protein called apoplipoprotein D (ApoD), which is involved in lipid metabolism and inflammation, at much higher levels than in younger people. This has the effect of reducing the patient's ability to resist virus infection, resulting in a more serious disease outcome.

The team established that highly elevated ApoD production with age in the lung drives extensive tissue damage during infection to reduce the protective antiviral type I interferon response.

The research was an international collaboration led by scientists from the China Agricultural University, University of Notttingham, Institute of Microbiology (Chinese Academy of Sciences), National Institute for Viral Disease Control and Prevention (Chinese Centre for Disease Control and Prevention) and the University of Edinburgh.

Aging is a leading risk factor in influenza-related deaths. Furthermore, the global population is aging at an unprecedented rate in human history, posing major issues for healthcare and the economy. So we need to find out why older patients often suffer more severely from influenza virus infection."

Professor Kin-Chow Chang, School of Veterinary Medicine and Science, University of Nottingham, and co-author on the paper

In this new study, the team investigated the mechanisms behind increased severity of influenza virus infection with age using an aging-mouse model and appropriate donor human tissue sections.

They identified ApoD as an age-related cell factor that impairs the activation of the immune system's antiviral response to influenza virus infection by causing extensive breakdown of mitochondria (mitophagy) resulting in greater production of virus and lung damage during infection. Mitochondria are essential for cellular production of energy and for induction of protective interferons.

ApoD is therefore a target for therapeutic intervention to protect against severe influenza virus infection in the elderly which would have a major impact on reducing morbidity and mortality in the aging population.

Professor Chang, added: "There is now an exciting opportunity to therapeutically ameliorate disease severity of the elderly from influenza virus infection by the inhibitory targeting of ApoD."