Leucine supplementation attenuates macrophage foamâ cell formation: Studies in humans, mice, and cultured macrophages

Whereas atherogenicity of dietary lipids has been largely studied, relatively little is known about the possible contribution of dietary amino acids to macrophage foamâ cell formation, a hallmark of early atherogenesis. Recently, we showed that leucine has antiatherogenic properties in the macrophage model system. In this study, an inâ depth investigation of the role of leucine in macrophage lipid metabolism was conducted by supplementing humans, mice, or cultured macrophages with leucine. Macrophage incubation with serum obtained from healthy adults supplemented with leucine (5 g/d, 3 weeks) significantly decreased cellular cholesterol mass by inhibiting the rate of cholesterol biosynthesis and increasing cholesterol efflux from macrophages. Similarly, leucine supplementation to C57BL/6 mice (8 weeks) resulted in decreased cholesterol content in their harvested peritoneal macrophages (MPM) in relation with reduced cholesterol biosynthesis rate. Studies in J774A.1 murine macrophages revealed that leucine doseâ dependently decreased cellular cholesterol and triglyceride mass. Macrophages treated with leucine (0.2 mM) showed attenuated uptake of very lowâ density lipoproteins and triglyceride biosynthesis rate, with a concurrent downâ regulation of diacylglycerol acyltransferaseâ 1, a key enzyme catalyzing triglyceride biosynthesis in macrophages. Similar effects were observed when macrophages were treated with αâ ketoisocaproate, a key leucine metabolite. Finally, both in vivo and in vitro leucine supplementation significantly improved macrophage mitochondrial respiration and ATP production. The above studies, conducted in human, mice, and cultured macrophages, highlight a protective role for leucine attenuating macrophage foamâ cell formation by mechanisms related to the metabolism of cholesterol, triglycerides, and energy production. © 2018 BioFactors, 44(3):245â 262, 2018Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144642/1/biof1415.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144642/2/biof1415_am.pd

Heparanase Inhibition Reduces Glucose Levels, Blood Pressure, and Oxidative Stress in Apolipoprotein E Knockout Mice

Background. Atherosclerosis is a multifactorial process. Emerging evidence highlights a role of the enzyme heparanase in various disease states, including atherosclerosis formation and progression. Objective. The aim of the study was to investigate the effect of heparanase inhibition on blood pressure, blood glucose levels, and oxidative stress in apoE−/− mice. Methods. Male apoE−/− mice were divided into two groups: one treated by the heparanase inhibitor PG545, administered intraperitoneally weekly for seven weeks, and the other serving as control group (injected with saline). Blood pressure was measured a day before sacrificing the animals. Serum glucose levels and lipid profile were measured. Assessment of oxidative stress was performed as well. Results. PG545 significantly lowered blood pressure and serum glucose levels in treated mice. It also caused significant reduction of the serum oxidative stress. For safety concerns, liver enzymes were assessed, and PG545 caused significant elevation only of alanine aminotransferase, but not of the other hepatic enzymes. Conclusion. Heparanase inhibition by PG545 caused marked reduction of blood pressure, serum glucose levels, and oxidative stress in apolipoprotein E deficient mice, possibly via direct favorable metabolic and hemodynamic changes caused by the inhibitor. Possible hepatotoxic and weight wasting effects are subject for future investigation

AT₁ levels.

<p>(A) A semi-quantative measure of AT1 protein levels in AEC II by western blotting; AT1 levels were significantly increased by 1.67 fold after Ang II administration. *P<0.0001 as compared to control group. CT—Control. Ang II—Angiotensin II. AT1—Angiotensin-II receptor type 1. The bars represent mean ± SEM. (B) An immunohestochemical staining of AT1 receptor in AEC II cells treated or untreated with Ang II. The representative figure showing stronger staining of AT1 in the Ang II treated group compared to the control. CT—Control. Ang II—Angiotensin II.</p

Effect of Ang II on AFC.

<p>(A) % Alveolar fluid clearance of the initial instilled volume was decreased in the Ang II groups in a dose dependent manner, from 8.6% ± 0.19 in control rats to 6.66% ± 0.13, 6.15% ± 0.11, 5.03% ± 0.31, 4.42% ± 0.29 and 5.25% ± 0.23 in Ang II (10⁻¹⁰ M, 10^-9M, 10⁻⁸ M, 10⁻⁷ M and 10⁻⁶ M) respectively. * P<0.001 As compared to control group; ** P<0.05 As compared to the rest of 10⁻¹⁰ M and 10⁻⁹ M Ang II treated groups. CT—Control. The bars represent mean ± SEM. (B) The albumin movement across the alveolar-capillary barrier did not differ significantly among the study groups indicating that the barrier was intact. CT—Control. The bars represent mean ± SEM.</p

A comparable scheme of AFC under normal vs. Ang II stimulated conditions.

<p>Under normal conditions Na+ is extruded out of the alveolar airspace by apical epithelial Na+ channels (ENaC), specifically highly selective cation channels composed of α, β and γ subunits (HSC) and basolateral Na,K-ATPase pump with water following osmoticaly, Whereas Ang II stimulation down regulated cAMP levels in AEC II, via AT1 receptors triggering, thus leading to the decrease of the two important AFC players; αNa,K-ATPase and the HSC, and an increase of the NSC (non-selective cation channels composed of α subunit alone), with a resultant impairment of sodium reabsorption and conceivable AFC decrease.</p