Background The CDC reports that the prevalence of obesity in US adults has risen to nearly 42%. The underlying mechanisms of obesity, insulin resistance, and the metabolic syndrome are not well characterized. This study aims to identify how adipose cellular senescence affects metabolic outcomes in the context of obesity and aging. Senescent cells have a proclivity to aggregate in adipose and act on neighboring tissues through the release of markers dictated by their senescence-associated secretory phenotypes. It is theorized that inflammatory cytokines may contribute to the pathogenesis of cardiometabolic disease. Furthermore, a high volume of adipocytes may be associated with increased immune cells and fat oxidation, contributing to the development of insulin resistance. Methods The ongoing clinical trial in the Musi lab will enroll 160 subjects to account for a dropout rate of approximately 25%. 120 subjects will complete the study. Based on their baseline characteristics they will be divided in the following groups:

Younger Lean (n=24) Group, age 18-30 years, BMI 18.5-24.9 kg/m² Older Lean (n=24) Group, age ≥ 65 years, BMI 18.5-24.9 kg/m² Older Obese (n=72) Group, age ≥ 65 years, BMI 30-39.9 kg/m²

Subjects will be enrolled and studied at Cedars Sinai Medical Center in Los Angeles, California (n=120 completers). We will recruit patients of any sex, race, and ethnic background. All subjects will be nondiabetic (fasting plasma glucose < 126 mg/dl, 2-h glucose during oral glucose tolerance test <200 mg/dl, and A1c <6.5%), community-dwelling, and sedentary (≤1.5 h of exercise per week).

Exclusion criteria include history of diabetes, participation in structured exercise >1.5h per week, chronic inflammatory / neurologic / autoimmune / pulmonary disorders, GI or heart disease, use of anti-arrhythmic or weight altering medications, smoking/alcohol use, previous bariatric surgery, and use of/allergy to senolytic agents.

All subjects will undergo initial screening, OGTT analysis, DXA/cardiopulmonary testing, insulin clamp and adipose/skin biopsy (which will be used for sn RNA-seq analyses of senescence). The older obese cohort will be further randomized into three arms: lifestyle intervention (n=24), senolytics (n=24), or placebo (n=24). They will undergo repeat adipose biopsies, snRNA-seq, and metabolic/physiologic assessment after respective 10-week interventions

Conclusion Characterizing the relationship between adipose senescence and metabolic outcomes will provide greater insight into the underlying mechanism of insulin resistance. While preliminary murine data are promising, assessing these hypotheses in human subjects will reveal the degree to which senolytic agents can improve metabolic function. Furthermore, this study study may help us gain better understanding of the aging process and identify potential molecular targets for prevention of metabolic disease.