Age-related Macular degeneration occurs in old age and causes serious disability where these patients cannot recognize things or people because of darkening and blurring of their central field of vision. In most of the patients, almost 90%, the disease is incurable. However, due to recent advancement in the field of medicine, a new property was unmasked for the drugs that are prevalent and are used for the treatment of AIDS caused by HIV.
The drugs, nucleosides reverse transcriptase inhibitors most commonly known as NRTIs, were the first group of drugs that were granted approval for the treatment of AIDS by the FDA. As suggested by the name, these drugs block an enzyme reverse transcriptase in the HIV that blocks its replication and consequently transmission and infection.
At the University of Kentucky Lexington, professor and vice chair of Department of Ophthalmology and Visual Sciences, Jayakrishna Ambati, lead a team of researchers where they investigated the effects of NRTIs in mice that had features of macular degeneration.
There are 2 types of AMD: the wet AMD and the Dry AMD. The wet AMD is the more serious and more debilitating kind that occurs rarely and is rapidly progressive. This kind is associated with an increase in blood vessels that damage the cells. The dry AMD is characterized by yellow depositions in the macula called drudens. Many drugs have been approved for wet AMD while no therapies were instituted for dry AMD.
The researchers worked on mice that had disease resembling AMD and demonstrated how the NRTIs stopped progression of the dry AMD. They determined how this happens. Basically there is an inflammasome known as NLPR3, which is a large protein that causes initiation of the inflammatory cascade that causes destruction of cells.
In cases where the NRTIs could not block reverse transcriptase they were still able to block the inflammasome and therefore reduce the injury to macula cells by these agents.
Scientists believe that other diseases that use the same pathway can also be treated with these FDA approved drugs if therapies are developed that can address these particular diseases.
“Moreover, through decades of clinical experience, we know that some of the drugs we tested are incredibly safe. Since these NRTIs are already FDA-approved, they could be rapidly and inexpensively translated into therapies for a variety of untreatable or poorly treatable conditions.” Says Ambati.