Objective Hyperlipidemia-induced endothelial cell (EC) activation is considered as an initial event responsible for monocyte recruitment in atherogenesis. However, it remains poorly defined what is the mechanism underlying hyperlipidemia-induced EC activation. Here we tested a novel hypothesis that mitochondrial reactive oxygen species (mtROS) serve as signaling mediators for EC activation in early atherosclerosis. Approach and Results Metabolomics and transcriptomics analyses revealed that several lysophosphatidylcholine (LPC) species, such as 16:0, 18:0 and 18:1, and their processing enzymes, including Pla2g7 and Pla2g4c, were significantly induced in the aortas of apolipoprotein E knockout (ApoE−/−) mice during early atherosclerosis. Using electron spin resonance and flow cytometry, we found that LPC 16:0, 18:0 and 18:1 induced mtROS in primary human aortic ECs (HAECs), independently of the activities of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Mechanistically, using confocal microscopy and Seahorse XF mitochondrial analyzer, we showed that LPC induced mtROS via unique calcium entry-mediated increase of proton leak and mitochondrial O2 reduction. In addition, we found that mtROS contributed to LPC-induced EC activation by regulating nuclear binding of AP-1 and inducing intercellular adhesion molecule 1 (ICAM-1) gene expression in vitro. Furthermore, we showed that mtROS inhibitor MitoTEMPO suppressed EC activation and aortic monocyte recruitment in ApoE−/− mice using intravital microscopy and flow cytometry methods. Conclusions ATP synthesis-uncoupled, but proton leak-coupled mtROS increase mediates LPC-induced EC activation during early atherosclerosis. These results indicate that mitochondrial antioxidants are promising therapies for vascular inflammation and cardiovascular diseases.

Obesity paradox (OP) describes a widely observed clinical finding of improved cardiovascular fitness and survival in some overweight or obese patients. The molecular mechanisms underlying OP remain enigmatic partly due to a lack of animal models mirroring OP in patients. Using apolipoprotein E knock-out (apoE) mice on a high fat (HF) diet as an atherosclerotic obesity model, we demonstrated 1) microRNA-155 (miRNA-155, miR-155) is significantly up-regulated in the aortas of apoE mice, and miR-155 deficiency in apoE mice inhibits atherosclerosis; 2) apoE/miR-155 (double knock-out (DKO)) mice show HF diet-induced obesity, adipocyte hypertrophy, and present with non-alcoholic fatty liver disease; 3) DKO mice demonstrate HF diet-induced elevations of plasma leptin, resistin, fed-state and fasting insulin and increased expression of adipogenic transcription factors but lack glucose intolerance and insulin resistance. Our results are the first to present an OP model using DKO mice with features of decreased atherosclerosis, increased obesity, and non-alcoholic fatty liver disease. Our findings suggest the mechanistic role of reduced miR-155 expression in OP and present a new OP working model based on a single miRNA deficiency in diet-induced obese atherogenic mice. Furthermore, our results serve as a breakthrough in understanding the potential mechanism underlying OP and provide a new biomarker and novel therapeutic target for OP-related metabolic diseases.

Background: Interleukin-35 is a novel inhibitory cytokine. Results: Interleukin-35 inhibits vascular endothelial cell activation by suppressing MAPK-AP1-mediated VACM-1 expression in LPS-induced acute inflammation. Conclusion: Interleukin-35 suppresses acute vascular endothelium response. Significance: Interleukin-35 may be an attractive reagent for anti-inflammatory therapy.

Interleukin-17 (IL-17)-secreting T helper 17 cells were recently identified as a CD4؉ T helper subset and implicated in various inflammatory and autoimmune diseases.

Insufficient hydrogen sulfide (H2S) has been implicated in Type 2 diabetic mellitus (T2DM) and hyperhomocysteinemia (HHcy)-related cardiovascular complications. We investigated the role of H2S in T2DM and HHcy-induced endothelial dysfunction in small mesenteric artery (SMA) of db/db mice fed a high methionine (HM) diet. HM diet (8 weeks) induced HHcy in both T2DM db/db mice and non-diabetic db/+ mice (total plasma Hcy: 48.4 and 31.3 µM, respectively), and aggravated the impaired endothelium-derived hyperpolarization factor (EDHF)-induced endothelium-dependent relaxation to acetylcholine (ACh), determined by the presence of eNOS inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME) and prostacyclin (PGI2) inhibitor indomethacin (INDO), in SMA from db/db mice but not that from db/+ mice. A non-selective Ca2+-active potassium channel (KCa) opener NS309 rescued T2DM/HHcy-impaired EDHF-mediated vascular relaxation to ACh. EDHF-induced relaxation to ACh was inhibited by a non-selective KCa blocker TEA and intermediate-conductance KCa blocker (IKCa) Tram-34, but not by small-conductance KCa (SKCa) blocker Apamin. HHcy potentiated the reduction of free sulfide, H2S and cystathionine γ-lyase protein, which converts L-cysteine to H2S, in SMA of db/db mice. Importantly, a stable H2S donor DATS diminished the enhanced O2- production in SMAs and lung endothelial cells of T2DM/HHcy mice. Antioxidant PEG-SOD and DATS improved T2DM/HHcy impaired relaxation to ACh. Moreover, HHcy increased hyperglycemia-induced IKCa tyrosine nitration in human micro-vascular endothelial cells. EDHF-induced vascular relaxation to L-cysteine was not altered, whereas such relaxation to NaHS was potentiated by HHcy in SMA of db/db mice which was abolished by ATP-sensitive potassium channel blocker Glycolamide but not by KCa blockers.ConclusionsIntermediate HHcy potentiated H2S reduction via CSE-downregulation in microvasculature of T2DM mice. H2S is justified as an EDHF. Insufficient H2S impaired EDHF-induced vascular relaxation via oxidative stress and IKCa inactivation in T2DM/HHcy mice. H2S therapy may be beneficial for prevention and treatment of micro-vascular complications in patients with T2DM and HHcy.