Mitochondria are known to generate approximately 90% of cellular reactive oxygen species (ROS). The imbalance between mitochondrial reactive oxygen species (mtROS) production and removal due to overproduction of ROS and/or decreased antioxidants defense activity results in oxidative stress (OS), which leads to oxidative damage that affects several cellular components such as lipids, DNA, and proteins. Since the kidney is a highly energetic organ, it is more vulnerable to damage caused by OS and thus its contribution to the development and progression of chronic kidney disease (CKD). This article aims to review the contribution of mtROS and OS to CKD progression and kidney function deterioration.

Background—: Essential hypertension has been recognized as a disease resulting from a combination of environmental and genetic factors. Recent studies demonstrated that microRNAs (miRNAs) are involved in cardiac hypertrophy and heart failure. However, little is known about the roles of miRNAs in essential hypertension. Methods and Results—: Using microarray-based miRNA expression profiling, we compared the miRNA expressions in plasma samples from 13 hypertensive patients and 5 healthy control subjects. Twenty-seven miRNAs were found to be differentially expressed. The expressions of selected miRNAs (miR-296–5p, let-7e, and a human cytomegalovirus [HCMV]–encoded miRNA, hcmv-miR-UL112) were validated independently in plasma samples from 24 hypertensive patients and 22 control subjects. The absolute expression levels of hcmv-miR-UL112, miR-296–5p, and let-7e were further determined in 127 patients and 67 control subjects (fold changes are 2.5, 0.5, and 1.7 respectively; all P <0.0001). Additionally, we demonstrated that interferon regulatory factor 1 is a direct target of hcmv-miR-UL112. Increased HCMV seropositivity and quantitative titers were found in the hypertension group compared with the control group (52.7% versus 30.9%, P =0.0005; 1870 versus 54 copies per 1 mL plasma, P <0.0001). Seropositivity, log-transformed copies of HCMV, and hcmv-miR-UL112 were independently associated with an increased risk of hypertension (odds ratio, 2.48; 95% confidence interval, 1.48 to 4.15; P =0.0005; odds ratio, 1.97; 95% confidence interval, 1.58 to 2.46; P <0.0001; and odds ratio, 2.55; 95% confidence interval, 1.98 to 3.27; P <0.0001, respectively). Conclusions—: We report for the first time a circulating miRNA profile for hypertensive patients and demonstrate a novel link between HCMV infection and essential hypertension. These findings may reveal important insights into the pathogenesis of essential hypertension. Clinical Trial Registration—: URL: http://www.clinicaltrials.gov . Unique identifier: NCT00420784.

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 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, independently of the activities of nicotinamide adenine dinucleotide phosphate 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 O ₂ reduction. In addition, we found that mtROS contributed to LPC-induced EC activation by regulating nuclear binding of activator protein-1 and inducing intercellular adhesion molecule-1 gene expression in vitro. Furthermore, we showed that mtROS inhibitor MitoTEMPO suppressed EC activation and aortic monocyte recruitment in apolipoprotein E knockout 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.

Objective—: The role of receptors for endogenous metabolic danger signals–associated molecular patterns has been characterized recently as bridging innate immune sensory systems for danger signals–associated molecular patterns to initiation of inflammation in bone marrow–derived cells, such as macrophages. However, it remains unknown whether endothelial cells (ECs), the cell type with the largest numbers and the first vessel cell type exposed to circulating danger signals–associated molecular patterns in the blood, can sense hyperlipidemia. This report determined whether caspase-1 plays a role in ECs in sensing hyperlipidemia and promoting EC activation. Approach and Results—: Using biochemical, immunologic, pathological, and bone marrow transplantation methods together with the generation of new apoplipoprotein E (ApoE) ^−/− /caspase-1 ^−/− double knockout mice, we made the following observations: (1) early hyperlipidemia induced caspase-1 activation in ApoE ^−/− mouse aorta; (2) caspase-1 ^−/− /ApoE ^−/− mice attenuated early atherosclerosis; (3) caspase-1 ^−/− /ApoE ^−/− mice had decreased aortic expression of proinflammatory cytokines and attenuated aortic monocyte recruitment; and (4) caspase-1 ^−/− /ApoE ^−/− mice had decreased EC activation, including reduced adhesion molecule expression and cytokine secretion. Mechanistically, oxidized lipids activated caspase-1 and promoted pyroptosis in ECs by a reactive oxygen species mechanism. Caspase-1 inhibition resulted in accumulation of sirtuin 1 in the ApoE ^−/− aorta, and sirtuin 1 inhibited caspase-1 upregulated genes via activator protein-1 pathway. Conclusions—: Our results demonstrate for the first time that early hyperlipidemia promotes EC activation before monocyte recruitment via a caspase-1–sirtuin 1–activator protein-1 pathway, which provides an important insight into the development of novel therapeutics for blocking caspase-1 activation as early intervention of metabolic cardiovascular diseases and inflammations.

Objective—: IL-35 (interleukin-35) is an anti-inflammatory cytokine, which inhibits immune responses by inducing regulatory T cells and regulatory B cells and suppressing effector T cells and macrophages. It remains unknown whether atherogenic stimuli induce IL-35 and whether IL-35 inhibits atherogenic lipid-induced endothelial cell (EC) activation and atherosclerosis. EC activation induced by hyperlipidemia stimuli, including lysophosphatidylcholine is considered as an initiation step for monocyte recruitment and atherosclerosis. In this study, we examined the expression of IL-35 during early atherosclerosis and the roles and mechanisms of IL-35 in suppressing lysophosphatidylcholine-induced EC activation. Approach and Results—: Using microarray and ELISA, we found that IL-35 and its receptor are significantly induced during early atherosclerosis in the aortas and plasma of ApoE (apolipoprotein E) knockout mice—an atherosclerotic mouse model—and in the plasma of hypercholesterolemic patients. In addition, we found that IL-35 suppresses lysophosphatidylcholine-induced monocyte adhesion to human aortic ECs. Furthermore, our RNA-sequencing analysis shows that IL-35 selectively inhibits lysophosphatidylcholine-induced EC activation-related genes, such as ICAM-1 (intercellular adhesion molecule-1). Mechanistically, using flow cytometry, mass spectrometry, electron spin resonance analyses, and chromatin immunoprecipitation-sequencing analyses, we found that IL-35 blocks lysophosphatidylcholine-induced mitochondrial reactive oxygen species, which are required for the induction of site-specific H3K14 (histone 3 lysine 14) acetylation, increased binding of proinflammatory transcription factor AP-1 in the promoter of ICAM-1, and induction of ICAM-1 transcription in human aortic EC. Finally, IL-35 cytokine therapy suppresses atherosclerotic lesion development in ApoE knockout mice. Conclusions—: IL-35 is induced during atherosclerosis development and inhibits mitochondrial reactive oxygen species-H3K14 acetylation-AP-1–mediated EC activation.

Acute kidney injury (AKI), associated with significant morbidity and mortality, is widely known to involve epithelial apoptosis, excessive inflammation, and fibrosis in response to ischemia or reperfusion injury, which results in either chronic pathological changes or death. Therefore, it is imperative that investigations are conducted in order to find effective, early diagnoses, and therapeutic targets needed to help prevent and treat AKI. However, the mechanisms modulating the pathogenesis of AKI still remain largely undetermined. MicroRNAs (miRNAs), small non-coding RNA molecules, play an important role in several fundamental biological and pathological processes by a post transcriptional regulatory function of gene expression. MicroRNA-21 (miR-21) is a recently identified, typical miRNA that is functional as a regulator known to be involved in apoptosis as well as inflammatory and fibrotic signaling pathways in AKI. As a result, miR-21 is now considered a novel biomarker when diagnosing and treating AKI. This article reviews the correlative literature and research progress regarding the roles of miR-21 in AKI.