The expression of SPARC in adipose tissue and its increased plasma concentration in patients with coronary artery disease

Objective: Adipocytes secrete various cytokines and matrix proteins. Severa l of them precipitate in obesity-associated diseases, including atheroscler osis. In the current study, we have examined the expression of secreted pro tein, acidic and rich in cysteine (SPARC) in adipose tissue and its signifi cance in obesity and coronary artery disease (CAD). Research Methods and Procedures: The SPARC mRNA expressions both in vivo an d in vitro were detected by Northern blot analysis. Plasma SPARC concentrat ions were measured by enzyme immunosorbent assay. First, we investigated th e plasma SPARC levels of 88 unrelated adult Japanese subjects (62 men and 2 6 women; average age: [+/- SD] 50 +/- 12 years; body mass index [BMI]: 16 t o 46 kg/m(2)). Additionally 31 subjects with CAD diagnosed by coronary angi ography (20 men and 11 women) were also investigated. Results: Human adipose tissues expressed abundant SPARC mRNA. SPARC express ion in adipose tissues was upregulated in obese db/db mice. Markedly enhanc ed expression of SPARC mRNA was observed in 3T3-L1 fibroblasts during adipo cyte differentiation. Consistent with these results, plasma SPARC levels pr oved a positive correlation with BMI in humans (r = 0.27; p < 0.01). Intere stingly, plasma SPARC concentrations were significantly elevated in age- an d BMI-matched subjects with CAD (p < 0.05). Discussion: SPARC was expressed in adipose tissues and its expression was e nhanced in obese mice. In human, plasma SPARC levels were elevated in obesi ty and CAD patients. This elevated SPARC may be involved in the progression of CAD.