London: A class of anti-retroviral drugs
commonly used to treat HIV/AIDS, particularly in Africa and
low income countries, can cause premature ageing, a new study
has claimed.
The study, published in the journal Nature Genetics,
found that the drugs damage DNA in the patient`s mitochondria
the `batteries` which power their cells.
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According to the researchers, the findings may explain
why HIV-infected people treated with anti-retroviral drugs
sometimes show advanced signs of frailty and age-associated
diseases such as cardiovascular disease and dementia at an
early age.
"The DNA in our mitochondria gets copied throughout
our lifetimes and, as we age, naturally accumulates errors. We
believe that these HIV drugs accelerate the rate at which
these errors build up," said lead researcher Professor Patrick
Chinnery from the Institute of Genetic Medicine at Newcastle
University.
He said: "So over the space of, say, ten years, a
person`s mitochondrial DNA may have accumulated the same
amount of errors as a person who has naturally aged twenty or
thirty years.
"What is surprising, though, is that patients who came
off the medication many years ago may still be vulnerable to
these changes."
Nucleoside analogue reverse-transcriptase inhibitors
(NRTIs) -- of which the most well known is Zidovudine, also
known as AZT -- were the first class of drug developed to
treat HIV.
They were a major breakthrough in the treatment of the
disease, greatly extending lifespan and leading the condition
to be seen as a chronic, rather than terminal, condition.
In high income countries, the older NRTIs are used
less commonly now due to concerns over toxicity and
side-effects. But, the drugs have proved to be an important
lifeline for people infected with HIV in Africa and low income
countries.
Professor Chinnery said: "HIV clinics were seeing
patients who had otherwise been successfully treated but who
showed signs of being much older than their years. This was a
real mystery.
"But colleagues recognised many similarities with
patients affected by mitochondrial diseases -- conditions that
affect energy production in our cells -- and referred them to
our clinic."
In an attempt to understand what was happening at a
cellular level, the researchers studied muscle cells from
HIV-infected adults, some of whom had previously been given
NRTIs.
They found that patients treated with NRTIs -- even as
long ago as a decade previously -- had damaged mitochondria
which resembled that of a healthy aged person.
Co-author and HIV specialist, Dr Brendan Payne, also
from Newcastle, believes that despite the side effects caused
by NRTIs, they are still important drugs and the risks are
relative.
"These drugs may not be perfect, but we must remember
that when they were introduced they gave people an extra ten
or twenty years when they would otherwise have died," he says.
"In Africa, where the HIV epidemic has hit hardest and
where more expensive medications are not an option, they are
an absolute necessity."
PTI
