Daily Caloric Restriction in Overweight and Obese Adults With ADPKD

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by development and continued growth of numerous fluid-filled renal cysts that ultimately result in renal failure. Similar to the general population, the prevalence of overweight and obesity have been rising in ADPKD patients, effecting about two-thirds of individuals. Adipocytes do not simply act as a fat reservoir, but are active endocrine organs that promote release of pro-inflammatory cytokines, and thus, may be a promising clinical target for ADPKD management. Mounting evidence also suggests that a metabolic defect exists in ADPKD, which likely contributes to cystic epithelial proliferation and subsequent cyst growth. Additionally, the investigators recently reported that overweight and obesity are strong independent predictors of more rapid kidney growth. Collectively, these data suggest that interventions to reduce abdominal adiposity may slow ADPKD progression.

Initial results from the investigators' R03-funded pilot and feasibility study support that a 12-month daily caloric restriction (DCR)-based behavioral weight loss intervention in adults with ADPKD and overweight or obesity: 1) is feasible and acceptable; 2) slowed kidney growth (annual %∆ in height-adjusted TKV [htTKV]), which was highly correlated with weight loss; 3) reduced abdominal adiposity; and 4) altered pathways implicated in ADPKD progression and metabolism. These initial results suggest that a DCR-based behavioral weight loss intervention offers a promising strategy to slow ADPKD progression. However, the pilot and feasibility study was limited by a small sample size, relatively short duration, and lack of a control group. Thus, to translate these promising results of the pilot study towards clinical practice, the investigators are conducting a randomized, controlled clinical trial in a larger number of adults with ADPKD and overweight or obesity to directly compare the efficacy of a DCR-based behavioral weight loss intervention compared to control for slowing kidney growth (primary outcome) over a longer duration. Changes in abdominal adiposity will serve as a secondary outcome and effects of weight loss on circulating and adipose markers of biological pathways will provide mechanistic insight.

In a subset of participants recruited for this clinical trial, we will measure change in kidney oxidative metabolism, insulin sensitivity, plasma metabolomics, and gut microbiota. These additional measures will aim to compare kidney oxidative metabolism, insulin sensitivity, plasma metabolome and gut microbiota at baseline and 2 years. In addition, the investigators aim to define the relations among changes in kidney oxidative metabolism, insulin sensitivity, plasma metabolome, gut microbiota, total kidney volume, and body weight over 2 years. Currently, it is unknown if weight loss via DCR modifies renal energy expenditure, substrate utilization, plasma metabolomics, or the gut microbiome.