Characterizing the effect of bariatric surgery on circulating S100A9
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Published on: June 11, 2012
Hamza Ahmed1, Alondra Guzman1, Ruina Zhang1
1Leon H. Charney Division of Cardiology, NYU Grossman School of Medicine, New York, NY, USA.
Insights
Bariatric surgery reduces elevated S100A9, a pro-inflammatory cytokine, in obesity. This decrease, mainly from reduced neutrophils, may lower cardiovascular risk and inflammation.
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.
Background:
Bariatric surgery (BS) is associated with improved cardiovascular (CV) outcomes in individuals with obesity. One proposed mechanism is reduced inflammation. S100A9, a pro-inflammatory cytokine, is elevated in obesity. S100A9, particularly expression in platelets, has been associated with CV risk. The impact of BS on circulating and platelet S100A9 in obesity is unknown.
Methods:
We studied serum, plasma, and platelet supernatants from subjects with obesity pre- and post-BS (n = 23) and lean volunteers (n = 8). S100A9 levels were quantified using an S100A9 immunoassay. Wilcoxon, Mann-Whitney, and t-tests were performed to assess changes in S100A9 levels pre- and post-operatively and compare levels across sample and subject types. Spearman tests were used to assess correlations between S100A9 levels in different sample types and neutrophil/platelet counts.
Results:
Serum and plasma S100A9 concentrations were elevated in individuals with obesity relative to lean individuals. Levels decreased to lean subject levels at 1-year post-BS, despite subjects with obesity remaining overweight. Circulating neutrophil counts also decreased post-BS, and post-BS differences in serum S100A9 were eliminated when calculated per-neutrophil. Platelet supernatant S100A9 levels were lower than in serum and plasma and did not change post-BS. Platelet supernatant S100A9 correlated with plasma, but not serum, levels.
Conclusion:
We found that S100A9 concentrations differ substantially between blood components, are elevated in obesity, and normalize post-BS. Reductions in circulating S100A9 may contribute to reduced inflammation and be largely driven by resolution of obesity-associated neutrophilia. Our data suggest minimal platelet contribution to circulating (or systemic) S100A9, but a local level inflammatory impact cannot be excluded.
