Characterizing the effect of bariatric surgery on circulating S100A9

Area of Science:

• Biochemistry
• Cardiovascular Science
• Inflammation Research

Background:

• Obesity is linked to increased cardiovascular risk, potentially mediated by inflammation.
• S100A9, a pro-inflammatory cytokine, is elevated in obesity and associated with cardiovascular risk, especially when expressed in platelets.
• The effect of bariatric surgery (BS) on S100A9 levels in obesity is not well understood.

Purpose of the Study:

• To investigate the impact of bariatric surgery on circulating and platelet S100A9 levels in individuals with obesity.
• To explore the relationship between S100A9 levels, obesity, and cardiovascular risk markers.
• To differentiate S100A9 expression in serum, plasma, and platelet components.

Main Methods:

• Quantified S100A9 levels in serum, plasma, and platelet supernatants from obese and lean subjects pre- and post-bariatric surgery using an immunoassay.
• Assessed changes in S100A9 levels and compared them across different blood components and subject groups.
• Correlated S100A9 levels with neutrophil and platelet counts.

Main Results:

• Serum and plasma S100A9 were elevated in obesity and normalized to lean levels one year post-bariatric surgery.
• Decreased circulating S100A9 post-surgery correlated with reduced neutrophil counts, suggesting neutrophilia resolution drives the decrease.
• Platelet S100A9 levels were low and did not change post-surgery, indicating a minimal role in systemic S100A9 reduction.

Conclusions:

• Bariatric surgery effectively reduces elevated circulating S100A9 levels in obesity, potentially contributing to improved cardiovascular outcomes.
• The reduction in S100A9 is largely attributed to the resolution of obesity-associated neutrophilia rather than changes in platelet S100A9.
• While systemic S100A9 is not significantly influenced by platelets post-surgery, a local inflammatory role cannot be entirely ruled out.