Although the current therapeutic regimens are effective in suppressing HIV infection, they do not eradicate it, and prolonged treatment may be complicated by development of drug resistance and an array of side effects. Despite continued concerns over the safety of interrupting therapy, a large proportion of subjects in clinical practice interrupt therapy for reasons related to drug toxicity, treatment fatigue and/or drug costs.
New research at the Sahlgrenska University, Sweden, and San Francisco General Hospital, CA, USA, suggests that resurgence of active HIV replication may result in injury of the central nervous system (CNS).
The neurofilaments are major structural components of the neuronal cytoskeleton, particularly concentrated in axons and have a major role to play in the maturation of axons and the maintenance of axonal integrity. Increased concentrations of the light chain of the neurofilament protein (NFL) in the cerebrospinal fluid (CSF) can serve as a sensitive indicator of CNS injury.
In the study, published in the second volume of AIDS Research and Therapy, 2005, the researchers measured NFL levels in HIV-infected subjects interrupting therapy in order to assess whether interrupting antiretroviral treatment of HIV infection might have a deleterious effect on the CNS. NFL is a sensitive marker of axonal injury, which in the present setting seems to disclose subclinical injury. Three of a total of eight subjects studied after stopping antiretroviral therapy showed substantial increase in CSF NFL, thereby indicating brain injury in this setting.
This study, while raising the concern that treatment interruption may enhance the risk of brain injury, also suggests that once started, continued treatment might prevent subclinical brain damage.