Galectin 3 in Obesity

Background: Recent epidemiological studies demonstrated a rapid increase in the prevalence of obesity, which is related to the metabolic syndrome. Galectin 3 is a lectin with predominantly pro-inflammatory activities that can also stimulate adipocyte proliferation. Levels of galectin 3 are markedly elevated in obesity. We hypothesize that galectin 3 deficiency leads to reduced adiposity and inflammation in mice. Methods: Adult WT and Galectin 3 KO male C57BL6 mice (8 weeks, n=10) were fed a low fat (LFD) or high fat diet (HFD) for 12 weeks. Body composition was measured by Dual-energy X-ray Absorptiometry (DEXA). Levels of circulating mediators were assessed by Enzyme-linked Immunosorbent Assay (ELISA), mRNA expression by quantitative RT-PCR. Adipocyte size was evaluated by Image J. Results: Galectin 3 KO mice on either LFD or HFD had significantly increased adiposity compared to diet-matched WT mice as measured by % fat mass (p<0.01) and serum leptin (p<0.05). Galectin 3 KO mice had a trend towards bigger adipocytes compared to diet-matched WT mice. Galectin 3 KO mice developed more severed systemic inflammation compared to WT mice. The acute phase protein Serum Amyloid A (SAA) was significantly increased in galectin 3 KO mice compared to diet-matched WT mice in serum and liver (p<0.05). In both visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), expression of inflammatory markers Chemokine (C-C motif) Ligand 2 (CCL2) and CD 68 was significantly higher in galectin 3 KO mice in the HFD group (p<0.05). Expression of adiponectin in VAT of galectin 3 KO mice on either LFD or HFD was significantly lower compared to diet-matched WT mice (p<0.01). However, other markers of inflammation in VAT and SAT did not significantly differ between WT and galectin 3 KO mice. Conclusion: Our studies demonstrate that galectin 3 KO mice have increased adiposity and inflammation in liver and adipose tissue. Although these results negate our initial hypothesis, this evidence indicates that galectin 3 plays an important role in the development of inflammation and obesity.