Astha, Sachan, Archna, Singh, Sakshi, Shukla, Sandeep, Aggarwal, Ishfaq, Mir, Rakhee, Yadav
Obese adipose tissue secretes a variety of adipocytokines that act as metabolic regulators with complex mechanisms. These mechanisms are largely unknown. Our objective was to compare serum concentration of a panel of adipocytokines between obese and non-obese individuals and identify any distinct patterns correlating with insulin sensitivity in obesity.
We designed a cross-sectional study among obese (body mass index [BMI] ≥30 kg/m2, n=62) and non-obese (BMI <25 kg/m2, n=32) individuals to compare circulating levels of the adipokines adiponectin and resistin known to affect insulin sensitivity. We also measured and compared levels of inflammatory cytokines including C-reactive protein (CRP), interleukin (IL)- 6, IL-8, monocyte chemoattractant protein (MCP)-1, and tumor necrosis factor (TNF)-α using Luminex multiplex immunoassay with drop array technology. Correlations between circulating adipocytokine levels and those of multiple well-established markers of insulin resistance including homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of β-cell function (HOMA-β) and quantitative insulin sensitivity check index were also established.
CRP, IL-8, MCP-1 and TNF-α levels were higher in obese than non-obese individuals; the CRP and IL-8 differences were statistically significant. We divided the group of obese individuals on the basis of HOMA-IR levels into insulin-resistant (IR; HOMA-IR ≥2.5) and insulin-sensitive (IS; HOMA-IR <2.5) groups and found that 43 out of 62 participants were insulin-resistant despite comparable BMIs. An overall proinflammatory profile was analyzed in IR obese participants, but the difference in levels of cytokines was not significant. CRP correlated significantly with most of our markers of insulin resistance, and adiponectin correlated with a marker of HOMA-β in obese individuals.
Obesity is associated with a general inflammatory milieu, but crosstalk between adipocytokines and insulin resistance is not only complex but also multifactorial.