Organ failure in the obese adipocytes prime polymorphonuclear cell inflammation under stress conditions

Obesity is associated with a higher risk of remote organ failure after shock and trauma. The mechanism(s) is poorly understood. Polymorphonuclear cell (PMN) inflammatory responses are important in the pathogenesis of organ injury following shock. Morbid obesity is a low-grade inflammatory state associated with proinflammatory mediator production from adipose tissue. We hypothesized that adipose tissue may modulate PMN inflammatory potential and is dependent on the magnitude of the injury-related stress response. This was studied in an in vitro model.

Adipose-derived stem cells (ADSCs) conditioned to behave as mature adipocytes were incubated with physiologic and stress concentrations of adrenaline for 12 hours, and cell culture supernatants were obtained. PMNs from normal human volunteers were cocultured with the ADSC supernatants (priming) followed by addition of 1-μM fMLP (activation). PMNs alone served as control. PMN activation was indexed by superoxide anion (O2) production, elastase release (%) and CD11b expression (mean fluorescent intensity).

Physiologic and stress levels of adrenaline resulted in significantly increased PMN activation in the presence or absence of adipocytes. However, the largest increase was noted in PMNs exposed to ADSC culture supernatants that had been cocultured with stress levels of adrenaline for 12 hours, twofold increase in CD11b expression and fourfold increase in superoxide anion and percent elastase release.

Adipocyte-derived mediators prime PMNs in vitro. There was a graded PMN response to adrenaline concentration with or without adipocytes in these experiments. The most profound increase in PMN inflammatory potential was noted with the adipocyte supernatant + stress adrenaline group. The clinical impact of obesity on remote organ injury is likely dependent on patient body mass index and the injury-related sympathetic responses. These data suggest a potential role for β blockade in this patient population.