Canagliflozin ameliorates hypobaric hypoxia-induced pulmonary arterial hypertension by inhibiting pulmonary arterial smooth muscle cell proliferation

ABSTRACTPulmonary arterial hypertension (PAH) is a disease with a high mortality and few treatment options to prevent the development of pulmonary vessel remodeling, pulmonary vascular resistance, and right ventricular failure. Canagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, is originally used in diabetes patients which could assist the glucose excretion and decrease blood glucose. Recently, a few studies have reported the protective effect of SGLT2 inhibitor on monocrotaline-induced PAH. However, the effects of canagliflozin on hypobaric hypoxia-induced PAH as well as its mechanism still unclear. In this study, we used hypobaric hypoxia-induced PAH mice model to demonstrate if canagliflozin could alleviate PAH and prevent pulmonary vessel remodeling. We found that daily canagliflozin administration significantly improved survival in mice with hypobaric hypoxia-induced PAH compared to vehicle control. Canagliflozin treatment significantly reduced right ventricular systolic pressure and increased pulmonary acceleration time determined by hemodynamic assessments. Canagliflozin significantly reduced medial wall thickening and decreased muscularization of pulmonary arterioles compared to vehicle treated mice. In addition, canagliflozin inhibited the proliferation and migration of pulmonary arterial smooth muscle cells through suppressing glycolysis and reactivating AMP-activated protein kinase signaling pathway under hypoxia condition. In summary, our findings suggest that canagliflozin is sufficient to inhibit pulmonary arterial remodeling which is a potential therapeutic strategy for PAH treatment

The role of G protein-coupled receptor kinase 4 in cardiomyocyte injury after myocardial infarction.

AIMS: G protein-coupled receptor kinase 4 (GRK4) has been reported to play an important role in hypertension, but little is known about its role in cardiomyocytes and myocardial infarction (MI). The goal of present study is to explore the role of GRK4 in the pathogenesis and progression of MI. METHODS AND RESULTS: We studied the expression and distribution pattern of GRK4 in mouse heart after MI. GRK4 A486V transgenic mice, inducible cardiomyocyte-specific GRK4 knockout mice, were generated and subjected to MI with their control mice. Cardiac infarction, cardiac function, cardiomyocyte apoptosis, autophagic activity, and HDAC4 phosphorylation were assessed. The mRNA and protein levels of GRK4 in the heart were increased after MI. Transgenic mice with the overexpression of human GRK4 wild type (WT) or human GRK4 A486V variant had increased cardiac infarction, exaggerated cardiac dysfunction and remodelling. In contrast, the MI-induced cardiac dysfunction and remodelling were ameliorated in cardiomyocyte-specific GRK4 knockout mice. GRK4 overexpression in cardiomyocytes aggravated apoptosis, repressed autophagy, and decreased beclin-1 expression, which were partially rescued by the autophagy agonist rapamycin. MI also induced the nuclear translocation of GRK4, which inhibited autophagy by increasing HDAC4 phosphorylation and decreasing its binding to the beclin-1 promoter. HDAC4 S632A mutation partially restored the GRK4-induced inhibition of autophagy. MI caused greater impairment of cardiac function in patients carrying the GRK4 A486V variant than in WT carriers. CONCLUSION: GRK4 increases cardiomyocyte injury during MI by inhibiting autophagy and promoting cardiomyocyte apoptosis. These effects are mediated by the phosphorylation of HDAC4 and a decrease in beclin-1 expression

Ecology of the Tick-Borne Phlebovirus Causing Severe Fever with Thrombocytopenia Syndrome in an Endemic Area of China

<div><p>Background</p><p>Severe fever with thrombocytopenia syndrome (SFTS) is caused by SFTS virus (SFTSV), a tick-borne phlebovirus in family <i>Bunyaviridae</i>. Studies have found that humans, domestic and wildlife animals can be infected by SFTSV. However, the viral ecology, circulation, and transmission remain largely unknown.</p><p>Methodology/Principal Findings</p><p>Sixty seven human SFTS cases were reported and confirmed by virus isolation or immunofluorescence assay between 2011 and 2014. In 2013–2014 we collected 9,984 ticks from either vegetation or small wild mammals in the endemic area in Jiangsu, China, and detected SFTSV-RNA by real-time RT-PCR in both questing and feeding <i>Haemaphysalis longicornis</i> and <i>H</i>. <i>flava</i>. Viral RNA was identified in larvae of <i>H</i>. <i>longicornis</i> prior to a first blood meal, which has never been confirmed previously in nature. SFTSV-RNA and antibodies were also detected by RT-PCR and ELISA, respectively, in wild mammals including <i>Erinaceus europaeus</i> and <i>Sorex araneus</i>. A live SFTSV was isolated from <i>Erinaceus europaeus</i> captured during the off tick-feeding season and with a high SFTSV antibody titer. Furthermore, SFTSV antibodies were detected in the migratory birds <i>Anser cygnoides</i> and <i>Streptopelia chinensis</i> using ELISA.</p><p>Conclusions/Significance</p><p>The detection of SFTSV-RNA in non-engorged larvae indicated that vertical transmission of SFTSV in <i>H</i>. <i>longicornis</i> might occur in nature, which suggests that <i>H</i>. <i>longicornis</i> is a putative reservoir host of SFTSV. Small wild mammals such as <i>Erinaceus europaeus</i> and <i>Sorex araneus</i> could be infected by SFTSV and may serve as natural amplifying hosts. Our data unveiled that wild birds could be infected with SFTSV or carry SFTSV-infected ticks and thus might contribute to the long-distance spread of SFTSV via migratory flyways. These findings provide novel insights for understanding SFTSV ecology, reservoir hosts, and transmission in nature and will help develop new measures in preventing its rapid spread both regionally and globally.</p></div

Phylogenetic analysis of SFTSV strains isolated from Jiangsu Province during 2011 and 2014, compared with SFTSV strains from other areas.

<p>The phylogenetic tree was constructed by using the Neighbor-Joining method with the MEGA5.1 software. The reliability values indicated at the branch nodes were determined using 1,000 bootstrap replications. Isolated SFTSV strains from places located in the north of the Yangtze River were labeled by black solid circles; Isolated SFTSV strains from places located in the south of the Yangtze river were labeled by black solid squares; Isolated SFTSV strains distributed in Japanese clades were labeled by black solid triangles. Phylogenetic relationship of SFTSV with other bunyaviruses, based on the complete L segment sequences, is shown in the figure.</p

Distribution of Sampling Sites for Ticks and Wild Animals in Jiangsu, an SFTS Endemic Area.

<p>A, Map of P. R. China; B, Map of Jiangsu Province. Sampling sites were where SFTS cases were reported.</p

Detection of SFTSV RNA in Various Stages of <i>Haemaphysalis longicornis</i> and <i>Haemaphysalis flava</i> Ticks Collected from Vegetation and Animals in 2013–2014 in Jiangsu.

<p>Detection of SFTSV RNA in Various Stages of <i>Haemaphysalis longicornis</i> and <i>Haemaphysalis flava</i> Ticks Collected from Vegetation and Animals in 2013–2014 in Jiangsu.</p

Detection of SFTSV RNA/Antibodies and Collection of Attached Ticks in Wild Animals in 2013–2014.

<p>Detection of SFTSV RNA/Antibodies and Collection of Attached Ticks in Wild Animals in 2013–2014.</p

Detection of SFTSV RNA and Antibodies in Wild Mammals and Birds Captured in 2013–2014 in Jiangsu Province.

<p>Detection of SFTSV RNA and Antibodies in Wild Mammals and Birds Captured in 2013–2014 in Jiangsu Province.</p