# Maladaptive Trained Immunity Drives Persistent IL-6 Production and Enhanced TLR Responsiveness in Monocyte-Derived Macrophages from People Living with HIV

## TL;DR

This study shows that people living with HIV have a faulty immune response that causes ongoing inflammation without protecting against the virus.

## Contribution

The study identifies maladaptive trained immunity in HIV patients, linking it to persistent inflammation without antiviral benefits.

## Key findings

- PLWH macrophages show heightened IL-6 production after TLR2 and TLR7 stimulation.
- IL-6 output correlates with HIV infection duration, suggesting cumulative immune reprogramming.
- Maladaptive trained immunity does not reduce HIV susceptibility in macrophages.

## Abstract

Trained immunity (TRIM) enhances innate immune responses through epigenetic and metabolic reprogramming but may become maladaptive, contributing to chronic inflammation. In people living with HIV (PLWH), maladaptive TRIM has been proposed but remains insufficiently characterized. We examined inflammatory cytokine production in monocyte-derived macrophages (MDMs) obtained from PLWH and age-matched individuals without HIV infection. Baseline cytokine output and responses to stimulation of Toll-like receptors (TLR) were measured. We further examined whether TRIM influenced susceptibility to HIV infection in MDMs derived from monocytes exposed to extracellular vesicles carrying the HIV-1 Nef protein (Nef EVs). Baseline IL-6 production did not differ between unstimulated MDMs from PLWH and uninfected controls. Although sex-associated differences were initially observed, these effects were no longer significant after adjustment for infection duration. IL-6 responses following TLR2 and TLR7 stimulation, but not TLR4 stimulation, were significantly amplified in PLWH-derived MDMs, consistent with a trained phenotype. Similar trends were observed in sex-stratified analyses but did not reach statistical significance. The magnitude of unstimulated IL-6 production positively correlated with duration of HIV infection, suggesting cumulative TRIM imprinting over time. Despite heightened inflammatory responsiveness, TRIM did not reduce susceptibility to HIV infection in Nef EV-exposed MDMs, indicating functional maladaptation rather than protective priming. These findings provide evidence of maladaptive TRIM in PLWH, characterized by preserved basal cytokine output but exaggerated inflammatory responses to innate immune stimulation without antiviral benefit. The association with infection duration supports progressive innate immune reprogramming as a contributor to HIV-associated inflammation. No statistically significant differences in trained immune responses were observed between male and female PLWH after accounting for duration of infection. Further studies are needed to define the mechanisms underlying this maladaptation and its clinical consequences.