CD36-mediated podocyte lipotoxicity promotes foot process effacement.

Background: Lipid metabolism disorders lead to lipotoxicity. The hyperlipidemia-induced early stage of renal injury mainly manifests as podocyte damage. CD36 mediates fatty acid uptake and the subsequent accumulation of toxic lipid metabolites, resulting in podocyte lipotoxicity. Methods: Male Sprague-Dawley rats were divided into two groups: the normal control group and the high-fat diet group (HFD). Podocytes were cultured and treated with palmitic acid (PA) and sulfo-N-succinimidyl oleate (SSO). Protein expression was measured by immunofluorescence and western blot analysis. Boron-dipyrromethene staining and Oil Red O staining was used to analyze fatty acid accumulation. Results: Podocyte foot process (FP) effacement and marked proteinuria occurred in the HFD group. CD36 protein expression was upregulated in the HFD group and in PA-treated podocytes. PA-treated podocytes showed increased fatty acid accumulation, reactive oxygen species (ROS) production, and actin cytoskeleton rearrangement. However, pretreatment with the CD36 inhibitor SSO decreased lipid accumulation and ROS production and alleviated actin cytoskeleton rearrangement in podocytes. The antioxidant N-acetylcysteine suppressed PA-induced podocyte FP effacement and ROS generation. Conclusions: CD36 participated in fatty acid-induced FP effacement in podocytes via oxidative stress, and CD36 inhibitors may be helpful for early treatment of kidney injury.

Prognosis and risk factors for cardiac valve calcification in Chinese end-stage kidney disease patients on combination therapy with hemodialysis and hemodiafiltration.

BACKGROUND: Cardiac valve calcification (CVC) is an important risk factor for cardiovascular complications. However, limited data are available concerning the prevalence, clinical features and risk factors for CVC in end-stage kidney disease (ESKD) patients. In this study, we aimed to assess these parameters in Chinese ESKD patients receiving combination therapy with hemodialysis and hemodiafiltration. METHODS: We conducted a cross-sectional study on 293 ESKD patients undergoing combination therapy of hemodialysis and hemodiafiltration at the First Affiliated Hospital of Chongqing Medical University from October 2014 to December 2015. CVC was evaluated via echocardiography. RESULTS: ESKD patients with CVC had a higher prevalence of diabetes mellitus, aortic and/or coronary artery calcification, arrhythmia, heart failure and coronary heart disease; increased systolic, diastolic and pulse pressure; longer duration of hemodialysis and hypertension; reduced hemoglobin, albumin and high-density lipoprotein cholesterol levels; and increased serum calcium and calcium-phosphorus product levels compared with those without CVC. Logistic regression analysis showed that increased dialysis duration (p = 0.006, OR = 2.25), serum calcium levels (p = 0.046, OR = 2.04) and pulse pressure (p < 0.001, OR = 3.22), the presence of diabetes (p = 0.037, OR = 1.81) and decreased serum albumin levels (p = 0.047, OR = 0.54) were risk factors for CVC. The correlation analysis indicated a significantly increased CVCs prevalence with an increase prevalence of heart failure, aortic and coronary artery calcification. CONCLUSIONS: CVC represents a common complication and a danger signal for cardiovascular events in ESKD patients undergoing combination therapy of hemodialysis and hemodiafiltration. The presence of diabetes, increased pulse pressure, long dialysis duration, hypoalbuminemia and high serum calcium levels were independent risk factors for CVC.

Hypoxia Exacerbates Inflammatory Acute Lung Injury via the Toll-Like Receptor 4 Signaling Pathway.

Acute lung injury (ALI) is characterized by non-cardiogenic diffuse alveolar damage and often leads to a lethal consequence, particularly when hypoxia coexists. The treatment of ALI remains a challenge: pulmonary inflammation and hypoxia both contribute to its onset and progression and no effective prevention approach is available. Here, we aimed to investigate the underlying mechanism of hypoxia interaction with inflammation in ALI and to evaluate hypoxia-inducible factor 1 alpha (HIF-1α)-the crucial modulator in hypoxia-as a potential therapeutic target against ALI. First, we developed a novel ALI rat model induced by a combined low-dose of lipopolysaccharides (LPS) with acute hypoxia. Second, we used gene microarray analysis to evaluate the inflammatory profiles of bronchi alveolar lavage fluid cells of ALI rats. Third, we employed an alveolar macrophage cell line, NR8383 as an in vitro system together with a toll-like receptor 4 (TLR4) antagonist TAK-242, to verify our in vivo findings from ALI animals. Finally, we tested the therapeutic effects of HIF-1α augmentation against inflammation and hypoxia in ALI. We demonstrated that (i) LPS upregulated inflammatory genes, tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1ß), and interleukin-6 (IL-6), in the alveolar macrophages of ALI rats, which were further enhanced when ALI combined with hypoxia; (ii) hypoxia exposure could further enhance the upregulation of alveolar macrophageal TLR4 that was noticed in LPS-induced inflammatory ALI, conversely, TLR4 antagonist TAK-242 could suppress the macrophageal expression of TLR4 and inflammatory cytokines, including TNF-α, IL-1ß, and IL-6, suggesting that the TLR4 signaling pathway as a central link between inflammation and hypoxia in ALI; (iii) manipulation of HIF-1α in vitro could suppress TLR4 expression induced by combined LPS and hypoxia, via suppressing promoter activity of the TLR4 gene; (iv) preconditioning augmentation of HIF-1α in vivo by HIF hydroxylase inhibitor, DMOG excreted protection against inflammatory, and hypoxic processes in ALI. Together, we see that hypoxia can exacerbate inflammation in ALI via the activation of the TLR4 signaling pathway in alveolar macrophages and predispose impairment of the alveolar-capillary barrier in the development of ALI. Targeting HIF-1α can suppress TLR4 expression and macrophageal inflammation, suggesting the potential therapeutic and preventative value of HIF-1α/TLR4 crosstalk pathway in ALI.

The Orphan Nuclear Receptor TLX/NR2E1 in Neural Stem Cells and Diseases.

The human TLX gene encodes an orphan nuclear receptor predominantly expressed in the central nervous system. Tailess and Tlx, the TLX homologues in Drosophila and mouse, play essential roles in body-pattern formation and neurogenesis during early embryogenesis and perform crucial functions in maintaining stemness and controlling the differentiation of adult neural stem cells in the central nervous system, especially the visual system. Multiple target genes and signaling pathways are regulated by TLX and its homologues in specific tissues during various developmental stages. This review aims to summarize previous studies including many recent updates from different aspects concerning TLX and its homologues in Drosophila and mouse.

The role of Nogo-A in neuroregeneration: a review.

Nogo, also known as Reticulon-4, is a protein that is specific to the central nervous system (CNS), and has been identified as an inhibitor of neurite outgrowth. Nogo-A is the largest member of the Nogo family and is responsible for inhibition of CNS regeneration. The structural information and biological functions of Nogo family members are reviewed in this study. The Nogo-66 receptor (NgR), a membrane protein which binds to Nogo, may play an important role in signal transduction for several myelin-associated inhibitors. The discovery of the Nogo family and the NgR provides an opportunity to develop interventions to promote axonal regeneration in the CNS after brain injury. Basic and clinical research of Nogo has increased our understanding of the mechanisms underlying spinal cord injury, multiple sclerosis, and neuroregenerative diseases. Understanding the biological functions of Nogo family members may open up a new avenue for the development of therapeutic agents. The anatomical and biological plastic changes are reviewed in animal models of injuries in the adult CNS. The role of Nogo A in neuroregeneration, and the mechanisms underlying functional recovery after CNS injury, are also detailed in this review.

Tailless-like (TLX) protein promotes neuronal differentiation of dermal multipotent stem cells and benefits spinal cord injury in rats.

Spinal cord injury (SCI) remains a formidable challenge in the clinic. In the current study, we examined the effects of the TLX gene on the proliferation and neuronal differentiation of dermal multipotent stem cells (DMSCs) in vitro and the potential of these cells to improve SCI in rats in vivo. DMSCs were stably transfected with TLX-expressing plasmid (TLX/DMSCs). Cell proliferation was examined using the MTT assay, and neuronal differentiation was characterized by morphological observation combined with immunocytochemical/immunofluorescent staining. The in vivo functions of these cells were evaluated by transplantation into rats with SCI, followed by analysis of hindlimb locomotion and post-mortem histology. Compared to parental DMSCs, TLX/DMSCs showed enhanced proliferation and preferential differentiation into NF200-positive neurons in contrast to GFAP-positive astrocytes. When the undifferentiated cells were transplanted into rats with SCI injury, TLX/DMSCs led to significant improvement in locomotor recovery and healing of SCI, as evidenced by reduction in scar tissues and cavities, increase in continuous nerve fibers/axons and enrichment of NF200-positive neurons on the histological level. In conclusion, TLX promotes the proliferation and neuronal differentiation of DMSCs and thus, may serve as a promising therapy for SCI in the clinic.

[The role of myeloid differentiation protein-2 in lipopolysaccharide-induced cellular activation of human endothelial cells].

OBJECTIVE: To investigate the expression of myeloid differentiation protein-2 (MD-2) in the human endothelial cells and its role in lipopolysaccharide (LPS)-induced NF-kappaB activation in endothelial cells. METHODS: In vitro cultured human umbilical vein endothelial cells (HUVEC) were employed in the study. The expression of MD-2 mRNA and protein, and the effect of LPS on the expression of its mRNA and protein were assessed with RT-PCR and Western blotting. The role of MD-2 in LPS-induced NF-kappaB activation and IL-8 production were investigated with gene transfection of mutant MD-2 cDNA (0.5, 1.0, 2.0 microg), pEF-BOS vacant vector (2.0 microg) and MD-2 plasmid (2.0 microg) into HUVEC, respectively. RESULTS: There was MD-2 mRNA and protein expression in HUVECs before LPS stimulation, and it could be obviously upregulated by LPS in time and dose-dependent manner (MD-2 protein absorbency was 25 196 +/- 1 723 without LPS stimulation, which was obviously lower than that stimulated with 0.01 mg/L LPS (58 817 +/- 3 241, P < 0.01) for 6 hours. Transfection of mutant MD-2 cDNA could remarkably inhibit LPS-induced NF-kappaB activation and IL-8 production in endothelial cells. CONCLUSION: MD-2 might play an important role in the LPS-induced NF-kappaB activation in HUVECs.

Novel multi-probe RNase protection assay set for detection of endotoxin associated receptors gene expression.

OBJECTIVE: To construct the multi-probe ribonuclease protection assay (RPA) template set to be used for detecting expression patterns of MD-2, TLR4, CD14 mRNAs in human peripheral blood mononuclear cells. METHODS: The designed cDNA fragments of the three genes were generated by polymerase chain reaction (PCR) using specific primers and directionally cloned into EcoR I and Hind III sites of expression plasmid pSP72 containing the T7 promoter, the linearized plasmids was used as template to synthesize anti-sense RNA probes. Then we extracted total RNA from peripheral blood mononuclear cells (PBMC) and detected the dynamic expression patterns of the three genes with RPA method. RESULTS: The proper sequence and orientation of the template set were confirmed by sequencing and the template set was successfully used to assay TLR4, MD-2 and CD14 mRNAs in human PBMC. The results showed that the three detected genes decreased transiently 1-3 hours after 100 ng/ml LPS stimulation. CONCLUSIONS: These new RPA multi-probe set provided valuable tool for the simultaneous quantitative determination of expression of TLR4, CD14 and MD-2 mRNAs in both constitutive and inducible types.