Myeloperoxidase Activities Under Highly Effective Host Immunological Control of HIV-1 Disease Progression

Myeloperoxidase (MPO), a neutrophil-derived enzyme, plays a critical role in oxidative host defense and inflammatory modulation during HIV infection. While untreated HIV and early antiretroviral therapy (ART) phases are associated with increased MPO activity, its behavior under highly effective immunological control remains unclear.

This cross-sectional study enrolled 40 participants: 30 HIV-1–infected individuals (10 OFF-HAART, 10 ON-HAART, 10 AIDS progressors) and 10 HIV-negative controls. Socio-demographic, immunological, and biochemical parameters were assessed, and MPO activity was measured by dianisidine-H₂O₂ assay. Correlation and ROC analyses evaluated associations with HIV progression markers.

Age and gender significantly associated with HIV stage (p = 0.002 and p = 0.013, respectively), with AIDS progressors predominantly ≤30 years (60%) and male (80%). HAART duration was also significant (p = 0.011), but infection duration showed no difference (p = 0.653). Circulating MPO activity did not differ significantly across groups (p = 0.629), with slightly higher levels in HIV-negative controls (0.11 ± 0.02 U) versus OFF-HAART (0.08 ± 0.02 U), ON-HAART (0.08 ± 0.02 U), and AIDS progressors (0.07 ± 0.02 U). MPO activity inversely correlated with viral load (r = -0.413, p = 0.023), CD8 count (r = -0.335, p = 0.035), and WBC (r = -0.339, p = 0.032), but not CD4 count or IL-8. CD4 strongly correlated negatively with viral load (r = -0.562, p = 0.001) and positively with albumin (r = 0.609, p < 0.001). ROC analysis showed CD4 had the highest predictive accuracy (AUC = 0.895, p = 0.001), while MPO showed fair discrimination (AUC = 0.653, p = 0.180).

Despite significant immune perturbations in HIV-positive individuals, systemic MPO activity did not increase compared to controls, possibly reflecting tissue compartmentalization or sampling limitations. However, inverse correlations with viral load suggest a potential role for MPO in immunological control, warranting longitudinal and mechanistic studies.