TLR4 Is Lower in Resistance-Trained Older Women and Related to Inflammatory Cytokines BRIAN K. MCFARLIN 3 , MICHAEL G. FLYNN 1 , WAYNE W. CAMPBELL 2 , LAURA K. STEWART 1 , and KYLE L. TIMMERMAN 1 1 Wastl Human Performance Laboratory, Department of Health and Kinesiology, 2 Department of Foods and Nutrition, and 3 Department of Health and Human Performance, University of Houston, Houston, TX ABSTRACT MCFARLIN, B. K., M. G. FLYNN, W. W. CAMPBELL, L. K. STEWART, and K. L. TIMMERMAN. TLR4 Is Lower in Resistance-Trained Older Women and Related to Inflammatory Cytokines. Med. Sci. Sports Exerc., Vol. 36, No. 11, pp. 1876 –1883, 2004. Introduction/Purpose: Regular exercise may offset age-associated increases in inflammatory cytokines and reduce the risk of developing diseases with an inflammatory etiology by exerting “anti-inflammatory” effects. Toll-like receptor 4 (TLR4) signaling stimulates inflammatory cytokine production, and may explain the “anti-inflammatory” effect attributed to regular exercise. Therefore, the purpose of the present study was to compare the effect of acute (3 sets, 9 exercises, 10 repetitions at 80% of the 1-repetition maximum) and chronic resistance exercise on TLR4 and inflammatory cytokines. Methods: Venous blood samples were collected from trained (TR, N = 10) and untrained (UT, N = 10) older (65– 80 yr) postmenopausal women: before (PRE), immediately post (POST), and 2 h (2H), 6 h (6H), and 24 h (24H) after completion of exercise. Cell-surface expression of TLR4 (two-color immunofluorescent cytometry), LPS (25 g·mL -1 )-stimulated cytokine production (ELISA), plasma cytokines (ELISA), and mRNA expression of TLR4 and cytokines (RT-PCR) were determined for each sample. Results: TR had 124% less cell-surface TLR4 expression than UT (P  0.05). A significant time effect was found for LPS-stimulated IL-6, IL-1, and TNF-, where 6H was significantly greater than all other samples. No significant effects were found for plasma (IL-6 and TNF-) or mRNA expression (IL-6, TNF-, and IL-1) of inflammatory cytokines. When subjects were grouped according to cell-surface TLR4 expression (HI and LO), LPS-stimulated TNF- (302%), IL-1 (209%), and IL-6 (167%) production was greater for HI than LO (P  0.05). Conclusion: Regularly exercising older women expressed less cell-surface TLR4 but did not have lower plasma levels or produce less LPS-stimulated inflammatory cytokines at rest or in response to a single bout of resistance exercise. TLR4 changes may explain the “anti-inflammatory” effect that has recently been attributed to chronic (2 wk -1 for previous 24 months) resistance exercise training. Key Words: LIPOPOLYSACCHARIDE, AGING, STRENGTH-TRAINING, FLOW CYTOMETRY, INFLAMMATION E levated inflammatory cytokines are associated with increased risks of developing cardiovascular disease (3), osteoporosis (25), diabetes mellitus (7), and ge- riatric cachexia (2) in later life. The onset of disease in older persons may accentuate the increase in tumor necrosis fac- tor-alpha (TNF-) and interleukin-6 (IL-6) that is typically associated with normal aging (5,6,27). Regular exercise may exert “anti-inflammatory” effects (11,27) that counter the age-associated increase in inflammatory cytokines, reducing the risk of developing diseases of physical inactivity and decreasing the rate of morbidity and mortality (11,21). Strenuous exercise appears to provide the greatest stim- ulus for release of inflammatory cytokines. Rhind et al. (24) reported that 4 h of combined strenuous exercise (4.9-km run, 3  800-m run, resistance exercise on four arm exer- cises at 70% of the 1-repetition maximum (1RM) to failure, and four 20-min exercise bouts at 65% of V ˙ O 2peak ) in- creased both lipopolysaccharide (LPS)-stimulated intracel- lular and serum IL-6, interleukin-1 (IL-1), and TNF-. Similar changes in inflammatory cytokines have been re- ported following a 5-km run (20), 80 min of cycling (22), and a single resistance exercise session (9,14,23). With respect to chronic training, Smith et al. (27) reported that 24 wk of combined resistance and endurance training reduced mitogen-stimulated inflammatory cytokine produc- tion at rest. In a recent study from our lab (23), we found that 10 wk of resistance exercise training caused a significant reduction in LPS-stimulated inflammatory cytokine produc- tion. Collectively, previous findings from our lab and others suggest that regular exercise training may produce anti- inflammatory effects (9,11,27). Whereas the mechanism by which regular exercise mod- ulates inflammatory cytokines is not fully understood, we have hypothesized a potential role of Toll-like receptors Address for correspondence: Brian K. McFarlin, Ph.D., University of Houston, Department of Health and Human Performance, Houston, TX 77204-6015; E-mail: bkmcfarlin@att.net. Submitted for publication January 2004. Accepted for publication June 2004. 0195-9131/04/3611-1876 MEDICINE & SCIENCE IN SPORTS & EXERCISE ® Copyright © 2004 by the American College of Sports Medicine DOI: 10.1249/01.MSS.0000145465.71269.10 1876