PROJECT SUMMARY/ABSTRACT People with human immunodeficiency virus (HIV), (PWH), are at increased risk of frailty, which increases the risk of adverse age-related outcomes, including falls, hospitalization and mortality. The mechanisms of frailty are not completely understood, particularly among PWH. The objectives of this proposal are to study the extent to which free testosterone and sex hormone binging globulin (SHBG) concentrations are associated with frailty and inflammation in men with HIV. We hypothesize that free testosterone and SHBG are key biomarkers for identifying PWH at the highest risk of frailty and who may benefit from intervention with anabolic agents. Our specific aims are to: 1) Determine the association of circulating free testosterone and SHBG with incident frailty using state-of-the-art hormone measurements among men with HIV, 2) Determine the association of diurnal variation in free testosterone with HIV serostatus in men and its association with systemic inflammation, 3) Determine the association of novel SHBG glycans with frailty among men with HIV. In Aim 1, we will measure serum free testosterone with state-of-the-art methods and SHBG in men with HIV who are part of the Multicenter AIDS Cohort Study (MACS), an ongoing prospective study since 1984 studying the natural and treated histories of HIV-1 infection in homosexual and bisexual men. We will determine the associations of these hormones with incident frailty, collected at semi-annual visits since 2007. In Aim 2, we will select men with and without HIV that have collected blood samples in AM and PM to assess diurnal variation in free testosterone and systemic inflammation [Interleukin 6 (IL6) and soluble TNF-alpha receptors II (sTNFRII)]. In Aim 3, we will study novel SHBG glycoforms in men with HIV, the identification and quantification of SHBG glycoforms will be performed by capillary electrophoresis and lectin microarray. The proposed research aims to provide new insights to the contribution of free testosterone and SHBG in frailty and its relationship with systemic inflammation. The goals during the award period include gaining advanced expertise in biostatistical methods, design and conduct epidemiological studies, as well as hands-on experience in the measurement of glycoforms from plasma proteins and interpretation of glycomic data through mentored research, tailored didactic coursework, and supervised performance of relevant laboratory techniques. Long-term goals include developing a career as an independent investigator in translational epidemiology and developing new approaches to treating and preventing age-related outcomes such as frailty in PWH.