Cocaine reduces thymic endocrine function: another mechanism for accelerated HIV disease progression

Area of Science:

• Immunology
• Virology
• Pharmacology

Background:

• Thymulin is a crucial thymic peptide for immune cell development.
• Depressed thymulin levels are observed in HIV patients with poor CD4(+) T-cell recovery.
• Substance use, particularly cocaine, is linked to accelerated HIV progression through mechanisms beyond ART adherence.

Purpose of the Study:

• To investigate the relationship between thymulin activity, CD4(+) and CD8(+) cell counts, and the CD4(+)/CD8(+) ratio in HIV(+) individuals.
• To assess the impact of substance use, specifically cocaine, on thymulin activity and its association with HIV disease markers.
• To determine if thymulin activity predicts HIV disease progression independently of antiretroviral treatment (ART) and viral load.

Main Methods:

• Cross-sectional and longitudinal study involving 80 HIV(+) active substance users.
• Plasma thymulin activity measured using a modified sheep rosette bioassay.
• Analysis of CD4(+) and CD8(+) cell counts and CD4(+)/CD8(+) ratio, with covariate analysis for substance use.

Main Results:

• Thymulin activity was negatively associated with cocaine use (p=0.026) and cocaine users were less likely to have detectable thymulin (RR=0.634, p=0.045).
• Cocaine users showed a significantly higher likelihood of decreased thymulin activity over time (OR=74.7, p=0.028).
• Thymulin activity positively correlated with CD4(+) cell count (p=0.002), and increases in CD4(+) counts were associated with increases in thymulin activity over time (OR=1.02, p=0.041).

Conclusions:

• Thymulin activity is a significant predictor of HIV disease progression.
• Cocaine use depresses thymulin activity independently of ART and HIV viral load, contributing to immunosuppression.
• Targeting thymulin activity may offer novel strategies to counteract immune dysfunction in HIV patients who use substances.