Serum CTRP9 and high-molecular weight adiponectin are associated with ischemic stroke.

BACKGROUND: C1q/TNF-related protein 9 (CTRP9) and adiponectin (APN) have beneficial metabolic regulatory and vasoprotective effects. This study explored alteration of CTRP9 and APN multimers during onset of ischemic stroke and development, to provide novel clinical and experimental basis for recognition and prevention of ischemic stroke. METHODS: There were 269 patients with ischemic stroke and 182 control subjects included in this study. Serum levels of CTRP9 and APN multimers in different disease stages were measured. RESULTS: Serum CTRP9, total APN (tAPN), and high-molecular weight (HMW) APN decreased gradually in stage I (acute stage, within 72 h of onset) of ischemic stroke and increased during stage III (11th day to one month) and stage IV (1 month after), compared to control. In the non-hyperlipidemia group, serum CTRP9, tAPN, and HMW were decreased in ischemic stroke patients compared to control (P < 0.05). Serum CTRP9 is closely related to serum tAPN and HMW (r = 0.992, 0.991). Serum CTRP9 are protective against ischemic stroke (OR = 0.400, 95% CI 0.197-0.810, P < 0.05). CONCLUSIONS: Lower serum CTRP9, tAPN, LMW, and HMW are significantly associated with increased ischemic stroke risk in non-hyperlipidemia subjects. CTRP9, tAPN, and HMW isoforms may be valuable clinical indicators for patients with ischemic stroke.

Hyperlipidemic plasma molecules bind and inhibit adiponectin activity.

INTRODUCTION: Adiponectin is a potent vascular protective molecule. Recent findings have suggested adiponectin resistance during early diabetes. However, the molecular mechanisms responsible remain unidentified. Here, we took an unbiased approach to identify whether hyperlipidemic plasma molecules exist that bind and inhibit adiponectin function, contributing to adiponectin resistance and diabetic vascular injury. METHODS: Adult rats were randomly assigned to receive either a normal or a high-fat diet for 8 weeks. Plasma was co-immunoprecipitated with anti-APN antibody and analyzed by mass spectrometry. The APN binding molecules and their effect upon APN biological activity were determined. RESULTS: As expected, the high-fat-diet increased plasma triglyceride, total cholesterol, and low-density lipoprotein. Importantly, the circulating APN level was significantly increased at this time point. Mass spectrometry identified 18 proteins with increased APN binding in hyperlipidemic plasma, among which four proteins critical in lipid metabolism, including apolipoprotein A1 (APOA1), APOA4, APOC1, and paraoxonase 1, were further investigated. Incubating recombinant APN with APOA1 markedly (P < 0.01), and incubating with APOC1 significantly (P < 0.05), inhibited APN activity as evidenced by the reduced AMPK activation in HUVECs. APOA4 and paraoxonase 1 incubation had no effect upon APN activity. Finally, plasma APOA1 was significantly increased (P < 0.05) in hyperlipidemic plasma compared with the control plasma. CONCLUSIONS: It was demonstrated for the first time that increased APOA1 and APOC1 in hyperlipidemic plasma binds and inhibits APN activity. This result not only identifies a novel molecular mechanism responsible for adiponectin resistance during early stage diabetes, but also provides additional new insight into the diverse/controversial (protective and harmful) functions of high-density lipoprotein.