Increased immune activation in people living with HIV on antiretroviral therapy but not when compared with persons on HIV preexposure prophylaxis.

Background: Residual immune activation is common in people living with HIV (PWH) despite antiretroviral therapy (ART) and may be associated with HIV-specific, as well as lifestyle-related factors.

Objective: We aimed to investigate markers of immune activation and neuronal injury in PWH on ART compared with controls with similar lifestyle.

Methods: Cerebrospinal fluid (CSF) and blood were collected from 50 men who have sex with men (MSM) with HIV on ART, 50 HIV-negative MSM on preexposure prophylaxis (PrEP), and 25 HIV-negative controls without PrEP. β2-microglobulin, neopterin, and neurofilament light protein (NfL) were analyzed. Cytomegalovirus and herpes simplex virus-2 serostatus, as well as sexually transmitted bacterial infections were registered.

Results: Serum and CSF β2-microglobulin and neopterin did not differ significantly between MSM with HIV and MSM on PrEP. However, both groups had significantly higher serum levels of β2-microglobulin and neopterin compared with HIV-negative controls without PrEP. Age-adjusted CSF NfL levels were also similar in MSM with HIV and MSM on PrEP, but higher than in controls without PrEP. A recent syphilis infection was associated with increased immune activation in CSF and blood.

Conclusion: Increased levels of immune activation and neuronal injury markers were found in virologically suppressed MSM with HIV and MSM on PrEP compared with controls. These findings imply that other factors than HIV contribute to the residual immune activation and impact on neurons observed in MSM with HIV on ART, and emphasize the importance of appropriate controls with similar lifestyle in studies of biomarkers in PWH.