Apolipoprotein CI stimulates the response to lipopolysaccharide and reduces mortality in Gram-negative sepsis

Gram-negative sepsis is a major death cause in intensive care units. Accumulating evidence indicates the protective role of plasma lipoproteins such as high-density lipoprotein (HDL) in sepsis. It has recently been shown that septic HDL is almost depleted from apolipoprotein CI (apoCI), suggesting that apoCI may be a protective factor in sepsis. Sequence analysis revealed that apoCI possesses a highly conserved consensus KVKEKLK binding motif for lipopolysaccharide (LPS), an outer-membrane component of gram-negative bacteria. Through avid binding to LPS involving this motif, apoCI improved the presentation of LPS to macrophages in vitro and in mice, thereby stimulating the inflammatory response to LPS. Moreover, apoCI dose-dependently increased the early inflammatory response to Klebsiella pneumoniae-induced pneumonia, reduced the number of circulating bacteria, and protected mice against fatal sepsis. Our data support the hypothesis that apoCI is a physiological protector against infection by enhancing the early inflammatory response to LPS and suggest that timely increase of apoCI levels could be used to efficiently prevent and treat early sepsis. Chemicals / CAS: Apolipoprotein C-I; Apolipoproteins C; Lipopolysaccharide

Ritonavir impairs lipoprotein lipase-mediated lipolysis and decreases uptake of fatty acids in adipose tissue

Objective - The use of the HIV protease inhibitor ritonavir (RTV) is frequently associated with hypertriglyceridemia and lipodystrophy. The aim of our study was to determine the mechanism underlying the observed hypertriglyceridemia. Methods and Results - Feeding female APOE*3-Leiden transgenic mice a Western-type diet supplemented with RTV (35 mg/kg per day) for 2 weeks resulted in a 2-fold increase in fasting plasma triglyceride (TG) levels, which was specific for very low-density lipoprotein (VLDL). RTV did not change the hepatic VLDL-TG production. Instead, RTV did increase the postprandial TG response to an oral fat load (area under the curve, 25.5 +/- 12.1 versus 13.8 +/- 6.8 mmol/L per hour in controls; P <0.05). Likewise, RTV hampered the plasma clearance of intravenously injected glycerol tri[H-3]oleate-labeled VLDL - like emulsion particles (half time, 19.3 +/- 10.5 versus 5.0 +/- 1.3 minutes in controls; P <0.05) associated with a decrease of 44% in plasma lipoprotein lipase activity. Accordingly, RTV decreased the uptake of TG-derived fatty acids (FAs) into adipose tissue, as well as the uptake of albumin-bound FA. Conclusions - We conclude that RTV causes hypertriglyceridemia via decreased lipoprotein lipase - mediated clearance of VLDL-TG. In addition, RTV specifically impairs the uptake of FA in adipose tissue, which may contribute to the lipodystrophy that is frequently observed in HIV-infected subjects on antiretroviral therapy

Inactivation of the E3 Ubiquitin Ligase IDOL Attenuates Diet-Induced Obesity and Metabolic Dysfunction in Mice

Diabetes mellitus: pathophysiological changes and therap