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Calorie Restriction Modulates Inactivity-Induced Changes in the Inflammatory Markers C-Reactive Protein and Pentraxin-3

Department of Clinical, Technological, and Morphological Sciences (A.B., M.Z., G.G., G.B.), Division of Internal Medicine, University of Trieste, Trieste 34149, Italy; Departments of Biomedical Sciences (G.M.) and Internal Medicine (P.C.), University of Catania, 95121 Catania, Italy; and Deutsches Zentrum für Luft-und Raumfahrt (DLR)-Institute of Aerospace Medicine (M.H.), 51147 Cologne, Germany

Address all correspondence and requests for reprints to: Gianni Biolo, Department of Clinical, Technological, and Morphological Sciences, University of Trieste, Clinica Medica, Ospedale di Cattinara, Strada di Fiume 447, Trieste 34149, Italy. E-mail: biolo{at}units.it.

Context: Energy balance and physical activity potentially influence systemic inflammation.

Objective: Our objective was to test the hypothesis that moderate energy restriction may prevent activation of inactivity-induced inflammatory response.

Design: Participants were studied four times at the end of 14-d periods of experimental bed rest or controlled ambulation, after receiving eucaloric or hypocaloric diets.

Setting: The study was conducted at the clinical research center of the German Space Agency.

Subjects: Nine healthy young volunteers participated.

Interventions: Energy intake was calibrated to physical activity and decreased by about 20% in hypocaloric conditions.

Main Outcome Measures: Changes in body fat by dual-energy x-ray absorptiometry as well as plasma inflammatory markers and cytokine mRNA levels in blood cells were measured.

Results: Fat mass did not change significantly in eucaloric conditions and decreased in hypocaloric periods (–1.0 ± 0.3 and –1.0 ± 0.3 kg in ambulatory and bed rest, respectively). Bed rest in eucaloric conditions increased plasma C-reactive protein (CRP) (+143 ± 53%) and both the ratios between plasma IL-6 and IL-10 (4±1 times) and white blood cell IL-6 and IL-10 mRNAs (5 ± 1 times). Energy restriction prevented bed-rest-mediated increases in CRP and the IL-6 to IL-10 ratio. Bed rest increased (P = 0.03) long pentraxin-3 (PTX3) plasma concentration, without significant activity-by-diet interaction. In all conditions (n = 36), CRP and PTX3 were inversely correlated (r = –0.61; P < 0.001). Changes in fat mass, leptin, and IL-6 directly correlated with CRP and inversely correlated with PTX3. IL-10 inversely correlated with CRP and directly correlated with PTX3 (r = 0.52; P < 0.01).

Conclusions: Calorie restriction prevents the inflammatory response induced by 14 d of bed rest. We suggest an inverse regulation of CRP and PTX3 in response to changes in energy balance.