Single injections of apoA-I acutely improve in vivo glucose tolerance in insulin-resistant mice

Aims/hypothesis

Apolipoprotein A-I (apoA-I), the main protein constituent of HDL, has a central role in the reverse cholesterol-transport pathway, which together with the anti-inflammatory properties of apoA-I/HDL provide cardioprotection. Recent findings of direct stimulation of glucose uptake in muscle by apoA-I/HDL suggest that altered apoA-I and HDL functionality may be a contributing factor to the development of diabetes. We have studied the in vivo effects of short treatments with human apoA-I in a high-fat diet fed mouse model. In addition to native apoA-I, we investigated the effects of the cardioprotective Milano variant (Arg173Cys).

Methods

Male C57Bl6 mice on a high-fat diet for 2 weeks that received a single injection of human apoA-I proteins (wild-type and Milano) were analysed for blood glucose and insulin levels during a 3 h incubation followed by glucose tolerance tests. Incorporation of injected human apoA-I protein into HDLs was analysed by native gel electrophoresis.

Results

ApoA-I treatment significantly improved insulin secretion and blood glucose clearance in the glucose tolerance test, with an efficiency exceeding that of lean control animals, and led to decreased basal glucose during the 3 h incubation. Notably, the two apoA-I variants triggered insulin secretion and glucose clearance to the same extent.

Conclusions/interpretation

ApoA-I treatment leads to insulin- and non-insulin-dependent effects on glucose homeostasis. The experimental model of short-term (2 weeks) feeding of a high-fat diet to C57Bl6 mice provides a suitable and time-efficient system to unravel the resulting tissue-specific mechanisms of acute apoA-I treatment that lead to improved glucose homeostasis.     

Total left main coronary artery occlusion in a female patient after AVSD surgical repair in childhood as a cause of non ST elevation myocardial infarction

A case of a 51-year-old woman with symptoms of non-ST-segment elevation acute coronary syndrome and concomitant atrial flutter is presented. Patient underwent atrioventricular septal defect repair in childhood. Coronary angiography showed total occlusion of left main coronary artery and massive collateral network originating from right coronary artery supplying entire left coronary artery. Ablation of atrial flutter had been performed and patient was subsequently submitted to mitral valve replacement, tricuspid valvuloplasty and coronary artery bypass grafting. The potential causes of left main occlusion are in this case discussed.     

Serum concentration of interleukin 15, interleukin 2 receptor and TNF receptor in patients with polymyositis and dermatomyositis: correlation to disease activity

Cytokines are implied in polymyositis/dermatomyositis (PM/DM) pathogenesis. Our aim was to evaluate the serum levels of interleukin-15 (IL-15), soluble receptors for IL-2 (sIL-2R) and TNF-alpha type 1 receptor (sTNF-R1) in PM/DM patients and their relation to disease activity and clinical symptoms. Thirty-eight patients who met definite or probable criteria of Bohan and Peter for DM/PM were included into the study. Results in patients with active (41 observations) and inactive disease (24 observations) were compared with control (15 subjects). The median level of IL-15 was 47.6 ± 170 pg/ml in active patients, 25.15 ± 240 pg/ml in inactive and 28.5 ± 28.89 pg/ml in controls. We demonstrated significant differences between active patients and controls in levels of IL-15 (0.016, 95%CI 1.39–57.1). The median level of sIL-2R was 314 ± 388, 235.3 ± 269 and 144.3 ± 152.9 pg/ml, and the median level of sTNF-R1 was 350 ± 388; 294.7 ± 204.7; 209.5 ± 105.9 pg/ml in active, inactive and control subjects, respectively. There were significantly higher serum levels of these cytokines in active patients than in control subjects (for sIL-2R P = 0.05, CI95% 0.4–331; and sTNF-R1 P = 0.031, CI95% 15.1–321.5). The interleukin levels did not differ between inactive patients and controls. Elevation of IL-15, sIL2-R and sTNF-R1 in active patients provides preliminary evidence for the activation of inflammatory response during PM/DM flares. Further studies may be needed to explain the mechanisms driving these diseases.