Objective: Monocyte/macrophage activation is increased among people with HIV, and may contribute to the heightened risk of atherosclerosis and neurocognitive dysfunction in this population. Insulin-like growth factor 1 (IGF-1) has been shown to attenuate the innate immune response in animal models of atherosclerosis and inflammatory bowel disease. We investigated, for the first time, relationships of circulating IGF-1 with monocyte/macrophage-specific indices among HIV-infected individuals and uninfected controls.
Design: Observational.
Methods: One hundred and thirty-one HIV-infected patients and 65 well matched controls without known cardiac disease or viral hepatitis were recruited previously. IGF-1, expressed as a z-score relative to the age-adjusted and sex-adjusted population mean, was related to log-transformed inflammatory markers within HIV and non-HIV groups.
Results: In HIV, IGF-1 inversely related to sCD163 (r = -0.28, P = 0.002), sCD14 (r = -0.29, P = 0.002), and high-sensitivity IL-6 (r = -0.27, P = 0.006). There was no association of IGF-1 with high-sensitivity CRP, MCP-1, IL-18, or LPS in HIV, or between IGF-1 and any inflammatory marker in controls. Relationships of IGF-1 with sCD163 and sCD14 remained significant in HIV after controlling for age, sex, smoking, BMI, visceral fat, statin use, viral load, and antiretroviral therapy. For every one-unit decline in IGF-1 z-score, sCD163 and sCD14 increased by 14% (95% CI, 0.23-29%) and 29% (95% CI, 1.4-63%), respectively.
Conclusion: Low IGF-1 was robustly associated with high sCD163 and sCD14 in HIV. Prospective studies are needed to investigate augmentation of IGF-1 as a novel strategy to reduce monocyte/macrophage activation in this population.