Inflammation is associated with a decrease of lipogenic factors in omental fat in women.

Area of Science:

• Endocrinology and Metabolism
• Molecular Biology
• Human Physiology

Background:

• Obesity is linked to systemic low-grade inflammation, with adipose tissue playing a crucial role.
• Previous research indicated inflammation impairs preadipocyte differentiation in cell lines.
• The in vivo relevance of inflammation's impact on adipocyte differentiation in humans remained to be explored.

Purpose of the Study:

• To investigate the in vivo relationship between inflammation and adipocyte differentiation markers in human adipose tissue.
• To compare gene expression profiles in omental versus subcutaneous adipose depots across different glycemic states.

Main Methods:

• Quantitative real-time PCR was used to assess gene expression in paired omental and subcutaneous adipose tissue biopsies.
• Samples were obtained from lean and obese women with varying glycemic statuses (normoglycemic, glucose-intolerant, type 2 diabetic).
• Genes analyzed included those related to inflammation (CD14, IL-18) and adipocyte differentiation (leptin, adiponectin, SREBP1, PPARgamma, etc.).

Main Results:

• CD14 and IL-18 were significantly overexpressed in omental adipose tissue compared to subcutaneous, regardless of obesity or diabetes status.
• Lipoprotein lipase (LPL), glycerol-3-phosphate dehydrogenase 1 (GPD1), and leptin expression were decreased in omental tissue.
• An inverse correlation was observed between inflammatory markers (CD14, IL-18) and lipogenic markers (PPARgamma, LPL, FABP4), with this effect amplified in glucose-intolerant individuals.
• Adiponectin and sterol regulatory element binding transcription factor 1 (SREBP1) were downregulated in omental tissue of type 2 diabetic patients.

Conclusions:

• Human omental adipose tissue exhibits increased inflammation, evidenced by elevated CD14 and IL-18 expression.
• This inflammatory state in the omental depot is associated with reduced expression of key lipogenic markers.
• The downregulation of lipogenic markers is more pronounced in individuals with glucose intolerance and type 2 diabetes, highlighting depot-specific metabolic alterations in obesity and diabetes.