Endocrine Abstracts

Introduction: Microparticles (MP) are circulating submicron particles released from cell membranes. They have an important role in intercellular endocrine signalling and may be increased in numerous conditions including cardiovascular disease. However, the influences of gender on MP characteristics are not fully understood.

Aim: To compare MP characteristics (size, concentration, cellular origin and inflammatory profile) in healthy males and females across the age and body weight spectrum.

Methods: Fasting blood samples were taken from healthy volunteers (males n=14; age 33±6 years, BMI 28.1±7.2 kg/m²; females n=16; age 35±12 years, BMI 26.4±6.5 kg/m², P=NS). MPs obtained by ultracentrifugation were subjected to nanoparticle tracking analysis and time resolved fluorescence to determine MP concentration, size, cellular origin (CD41 platelet; CD11b leukocyte; CD235a erythrocyte; CD144: endothelial) and inflammatory profile (interleukin 6 (IL6), tumour necrosis factor alpha (TNFα), interferon gamma (IFNγ), fatty acid binding protein 4 (FABP4), peroxisome proliferator activated-receptor gamma (PPARγ)).

Results: Males had higher MP concentration than females (5.7×10¹¹/ml±3.3 vs 3.8×10¹¹/ml±1.2, P<0.05) but no difference in mean size (138±10 nm vs 143±15 nm respectively, P=0.29). Males had significantly higher fluorescence signals for platelet and endothelial-derived MPs (CD41:4141±2309 vs 2499±1087, P<0.05; CD144: 3865±2365 vs 1123±1247, P<0.05) along with increased signal for IFNγ (14160±6268 vs 8885±4548, P<0.05), IL6 (2435±1689 vs 1356±1195, P=0.05) and FABP4 (6597±3613 vs 2915±2120, P<0.01). TNFα signal was also higher in males but this did not quite reach significance (1822±1900 vs 921±649, P=0.085).

Conclusions: Healthy men have increased circulating MPs compared to women, which are characterised by a more procoagulant and proinflammatory profile. These findings may contribute to gender-related differences in cardiovascular risk.