Vitamin D reduces LPS-induced cytokine release in omental adipose tissue of women but not men

Abstract

Context: Both vitamin D deficiency and inflammation have been associated with insulin resistance and type 2 diabetes risk. In vitro vitamin D treatment of subcutaneous (SC) adipose tissue (AT) may reduce inflammation, but data are conflicting.

Objectives: To evaluate the effects of vitamin D (25(OH)D3 and 1,25(OH)2D3) on the secretion of inflammatory cytokines (TNF-α and IL-6) in omental (OM) and SC human AT and to explore factors that could correlate with the individual response to vitamin D including age, smoking status, BMI, comorbidities, medication, HbA1c, apolipoprotein B, serum 25-hydroxyvitamin D and high sensitivity C-reactive protein.

Patients: 7 men and 8 women with severe obesity undergoing bariatric surgery.

Intervention: Fresh OM and SC AT explants sampled during surgery (n=15) were incubated for 24h in a control, 25(OH)D3 (150 nM) or 1,25(OH)2D3 (1 nM) medium. Lipopolysaccharide (LPS) (10 ng/ml) was added for another 24h.

Main outcome measure: Change in TNF-α and IL-6 levels in collected media after vitamin D treatment (ELISA).

Results: Mean age and BMI of the patients were 46.4±10.9 years and 48.8±7.5 kg/m(2), respectively. Eleven patients had type 2 diabetes. 25(OH)D3 and 1,25(OH)2D3 reduced the LPS-induced increases in cytokine levels in OM AT of women but not in men. No effect was observed in SC AT. Apart from gender, none of the factors analyzed correlated with vitamin D response.

Conclusion: We showed that 25(OH)D3 and 1,25(OH)2D3 can lower cytokine release from OM but not SC AT explants and only in women.

Keywords: Adipose tissue; Human; Inflammation; Vitamin D.