Inhibition of Reverse Transcription in Type I Interferon Mediated Neuropathology

Aicardi-Goutières syndrome (AGS) is a severe childhood disease of the brain associated with very high levels of a chemical called type I interferon. Normally humans only produce interferon when they are infected with a virus. In AGS, there is no obvious viral infection. Instead, due to changes (mutations) in the genetic code in these individuals, it is believed that the cells in the body are fooled into thinking that the person's own DNA is viral - that is to say, there is a confusion in telling 'self' from 'non-self'.

In fact, a large amount of our own DNA is made up of ancient virus (called 'endogenous retrovirus' and sometimes also referred to as 'junk DNA'), that have been included into our own genetic material over millions of years. These endogenous retroviruses can still act like a virus coming from outside of the body, so that they need to be controlled. The Investigators have wondered if the genetic changes causing AGS mean that these normal control mechanisms don't work. If that is true, the endogenous retroviruses could start to make copies of themselves which might be recognised by our immune system as 'non-self' ('foreign' i.e. viral), leading to the continuous production of interferon which then damages the cells in our body.

Since humans cannot repair the genetic code in every cell, the investigators wish to treat AGS patients with drugs called reverse transcriptase inhibitors (RTIs). RTIs are used to fight the HIV-1 virus that causes AIDS. In the case of AGS, it is not treating HIV-1, but the investigators wonder if the same drugs might be able to control endogenous retroviruses that are driving interferon production. Indeed, in a recently completed study the investigators gathered early information to suggest that treatment of patients with AGS with RTIs for one year did lead to a reduction in interferon, with levels increasing again when we stopped the drugs.

The current study will involve three treatment arms, and an assessment of interferon status and other markers which we think will give us information about AGS, and about how RTIs may work in the treatment of AGS.

This study is of potential importance for patients with AGS and their families since there are no licenced drugs for this disorder at the present time. Scientifically, the project will be of considerable interest if the results support the possibility that 'junk DNA' can be associated with human disease. RTIs are very safe drugs, that have been used in millions of people with HIV-1 around the world. If the results turn out to be convincing, the investigators believe that it might be worth thinking about using RTIs to treat other diseases that have also been linked to increased levels of type I interferon, for example the relatively common immune condition called systemic lupus erythematosus.