The purpose of this study was to determine whether obesity would reduce the capacity of peripheral blood mononuclear cells (PBMCs) to produce the anti-inflammatory protein pentraxin 3 (PTX3) in response to ex vivo stimulation with lipopolysaccharide (LPS), and if acute aerobic exercise would enhance this PTX3 production capacity. In addition, the inter-relationships of LPS-induced PTX3 with the inflammatory cytokines (interleukin 6 [IL-6], IL-10, and tumor necrosis factor alpha) were examined. Twenty-one healthy subjects (10 obese and 11 normal-weight) performed an acute bout of aerobic exercise at 75% VO2max. The capacity of PBMCs to produce PTX3 ex vivo following LPS stimulation was the same in obese and normal-weight subjects at rest, and decreased equally in both subject groups following acute aerobic exercise. This is in contrast to plasma PTX3, which is lower in obese subjects at rest and increased equally in both obese and normal-weight subjects following exercise. In addition, ex vivo PTX3 production was positively associated with IL-6 and IL-10 in response to acute aerobic exercise ( r = 0.686, P = 0.020; r = 0.744, P = 0.009, respectively) in normal-weight, but not in obese individuals ( r = 0.429, P = 0.249; r = 0.453, P = 0.189, respectively). These findings indicate that concentrations of PTX3 observed in plasma are relatively independent of those produced by PBMCs ex vivo and the mechanisms associated with PTX3-mediated anti-inflammatory signaling may differ during obesity. Impact statement Our laboratory has previously demonstrated that obese individuals present with lower plasma concentrations of the anti-inflammatory protein pentraxin 3 (PTX3), whereas acute aerobic exercise increases plasma PTX3 levels similarly compared to normal-weight individuals. As a follow-up, the present study demonstrates that PBMCs isolated from obese and normal-weight individuals produce comparable amounts of PTX3 ex vivo in response to lipopolysaccharide (LPS). Furthermore, given that acute aerobic exercise reduced the ex vivo production of PTX3 in both groups, our results clearly indicate that plasma PTX3 levels are relatively independent of those produced by PBMCs ex vivo. In addition, our findings suggest that the mechanisms associated with PTX3-mediated production of the anti-inflammatory cytokine interleukin 10 may be impaired in obese individuals, and thus provides a key finding necessary for the elucidation of PTX3's role in the mediation of anti-inflammatory profiles and the subsequent amelioration of inflammatory disease during obesity.
Keywords: Pentraxin 3; aerobic exercise; cardiovascular disease; inflammatory cytokines; monocytes; obesity.