Free radicals shown to protect the heart

Scientists at King’s College London have discovered that some ‘free radicals’ protect the heart, providing a possible reason why trials of antioxidant therapies for heart disease have so far failed.

Researchers discovered that in mice, chemically-reactive molecules - normally thought to be damaging for the body - may in fact help the heart adapt to chronic stress, preventing heart failure.

Heart failure occurs when the heart can’t adapt to chronic conditions that put pressure on the organ, such as high blood pressure or heart attacks. More than 700,000 in the UK are living with heart failure, which can be debilitating and has a poor prognosis.

The research, funded by the British Heart Foundation (BHF), showed that some examples of highly-reactive molecules known as ‘reactive oxygen species’, which include free radicals, had protective effects.

BHF Professor, Ajay Shah, who led the study at King’s College London, said: ’The bad reputation of free radicals has led many to believe that antioxidants – which mop them up – could be beneficial for heart health. But trials of non-specific antioxidant therapies have failed to show benefits. Our discovery could partly explain why.

’In fact, some of these reactive molecules act as signals to promote protective pathways. We need to develop targeted therapies that remove damaging free radicals or promote the protective ones.’

The team at the King’s College London BHF Centre of Research Excellence investigated the effects of Nox4, an enzyme that produces reactive oxygen species in the heart. They tested the effects of Nox4 on the heart by engineering mice that lacked Nox4, and those that over-produced it.

They found that the mice with extra Nox4 adapted much better to stress, protecting the heart from becoming enlarged or failing.

Professor Jeremy Pearson, Associate Medical Director at the BHF, said: ’Heart failure is a debilitating condition with inadequate treatments. Teasing out the heart’s natural defence mechanisms through research is vital for developing more effective treatments and improving life for those affected.’

The research is published this week in the journal PNAS.