Increase in Free and Total Plasma TGF-beta 1 Following Physical Activity

Objective To evaluate effects of physical activity and food consumption on plasma concentrations of free and total transforming growth factor beta-1 (TGF-beta 1), beta-2 (TGF-beta 2), and beta-3 (TGF-beta 3) in individuals with knee osteoarthritis (OA). Methods Participants (n = 40 in 2 cohorts of 20; mean age 70 years) with radiographic knee OA were admitted overnight for serial blood sampling. Cohorts 1 and 2 assessed the impacts of food intake and activity, respectively, on TGF-beta concentrations. Cohort 1 blood draws included 2 hours postprandial the evening of day 1 (T3), fasting before rising on day 2 (T0), nonfasting 1 hour after rising (T1B), and 4 hours after rising (T2). Cohort 2 blood draws included T3, T0, fasting 1 hour after rising and performing activities of daily living (T1A), and nonfasting 2 hours after rising (T1B). By sandwich ELISAs, we quantified plasma free and total TGF-beta 1 concentrations in all samples, and plasma total TGF-beta 2 and TGF-beta 3 in cohort 2. Results Free TGF-beta 1 represented a small fraction of the total systemic concentration (mean 0.026%). In cohort 2, free and total TGF-beta 1 and total TGF-beta 2 concentration significantly increased in fasting samples collected after an hour (T1A) of activities of daily living (free TGF-beta 1: P = 0.006; total TGF-beta 1: P < 0.001; total TGF-beta 2: P = 0.001). Total TGF-beta 3 increased nonsignificantly following activity (P = 0.590) and decreased (P = 0.035) after food consumption while resting (T1B). Conclusions Increased plasma concentrations of TGF-beta with physical activity suggests activity should be standardized prior to TGF-beta 1 analyses.