Publication: Immunology

Obesity-associated chronic low-grade tissue inflammation is an important factor in the development of obesity-related pathologies, such as insulin resistance and type II diabetes. The cause and stimulus of persistent inflammatory activation in obesity is largely unknown. Toll like receptors (TLRs) are pattern recognition receptors expressed abundantly on monocytes and macrophages. TLRs and their activation lead to the increased transcription of pro-inflammatory cytokines, chemokines, and reactive oxygen species which may aggravate pathology in obese individuals. We investigated here whether TLRs could contribute to the progression and induction of diabetes in obese individuals. Peripheral blood and abdominal subcutaneous adipose tissue samples were collected from healthy as well as overweight and obese individuals, with or without diabetes. The expression of TLR2 and TLR4 was quantified by Immunohistochemistry, Flow Cytometry and RT-PCR. Proinflammatory cytokines were quantified by ELISA. Obese and overweight individuals showed significantly increased expression of TLR2 and TLR4 in monocytes and adipose tissue as compared with lean individuals (P < 0.05). Interestingly, a remarkably higher expression of TLRs in obese and overweight individuals with diabetes type II (P < 0.05) was observed. An increased expression of TLR2 and TLR4 was correlated with BMI (P < 0.05) but there was no major difference of TLR5 expression between lean and overweight/ obese individuals. Moreover, a notable association of TLRs with the blood glucose level was observed (P < 0.05). Our findings suggest that the elevated expression of TLR-2 and 4, and associated-cytokines in overweight/obese individuals may play a role in obesity-associated inflammation and insulin resistance.

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