Injection Drug Use Frequency Related to Markers of Immune Activation in HIV

Injection drug use (IDU) is linked to an increase in immune activation, and new data suggest that reducing the frequency of IDU and encouraging injection cessation could have positive health benefits by reducing immune activation.

In a study published in the Journal of Acquired Immune Deficiency Syndromes, investigators sought to examine the relationship between IDU and immune activation in samples of HIV-positive and HIV-negative people who inject drugs (PWID).

“Injection drug use, with or without HIV-infection, is associated with an increase in immune activation, measured in blood and in the GI tract,” said co-investigator Sauarabh Mehandru, MD.

Included in the study were current and former PWID and a control of participants who never injected drugs.

The high prevalence of the hepatitis C virus (HCV) among PWID created a challenge in distinguishing between the effects of IDU and active HCV infection. To address this issue, the investigators compared immune markers between active PWID and individuals who had ceased injection for 1 to 4 months.

“Cessation of injection resulted in a decline in immune activation,” said principal investigator Martin Markowitz, MD. “But only in the absence of HCV viremia, ie, there was no decline in immune activation among those who stopped injecting who were HCV viremic.”

The investigators also examined 3 risk behaviors: sharing injection equipment, duration of injection frequency in years; and injection frequency over the past 30 days.

“Existing research on the relationship between injection behaviors and immune activation has primarily focused on people who were HIV-infected and yielded inconsistent results,” said co-investigator Sherry Deren, PhD. “One contributing factor to these mixed results may be the lack of attention to HCV, which is hyper-endemic worldwide among PWID and was found by our team to be related to immune activation.”

When examining the relationship between injection behaviors and immune activation—–controlling for HCV viremia––the investigators found that frequency of injection and duration of injection was related to the immune markers.

HCV-negative PWID can normalize their levels of immune activation by discontinuing injections, the authors noted.

The findings suggest that efforts to decrease injection frequency can have a positive effect in reducing immune activation.

“Harm reduction efforts for PWID should include treatment of HCV infection, to reduce immune activation and enhance related health benefits,” Dr Markowitz said. “A longitudinal study to test the impact of curing HCV on immune activation among PWID is underway by our group.”

The authors noted that more research needs to be done to determine the mechanisms of the relationship between IDU behaviors and immune activation.

“Frequency of injection was positively related to markers of immune activation, as was duration of injection,” the authors wrote. “Findings suggest that efforts to encourage injection cession or reduction in frequency can have positive health benefits through reducing immune activation.”