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Abstract Objectives Anti‐signal recognition particle (SRP) antibodies, markers of immune‐mediated necrotising myopathy, are reportedly related to cardiac involvement; however, whether they are pathogenic to the myocardium remains unclear. We aimed, therefore, to explore the pathogenicity of anti‐SRP antibodies against the myocardium through in vivo and in vitro studies. Methods Total immunoglobulin G (IgG), purified from patients with positive anti‐SRP antibodies, was passively transferred into C57BL/6 mice. Cardiac function was evaluated via echocardiography and the ventricular pressure–volume loop; cardiac histological changes were analysed using haematoxylin–eosin staining, picrosirius red staining, immunofluorescence and immunohistochemistry. Additionally, reactive oxygen species (ROS) formation was evaluated by dihydroethidium (DHE) staining; mitochondrial morphology and function were evaluated using transmission electron microscopy and seahorse mitochondrial respiration assay, respectively. The myositis cohort at our centre was subsequently reviewed in terms of cardiac assessments. Results After the passive transfer of total IgG from patients with positive anti‐SRP antibodies, C57BL/6 mice developed significant left ventricular diastolic dysfunction (LVDD). Transcriptomic analysis and corresponding experiments revealed increased oxidative stress and mitochondrial damage in the hearts of the experimental mice. Cardiomyocytes exposed to anti‐SRP‐specific IgG, however, recovered normal mitochondrial metabolism after treatment with N‐acetylcysteine, an ROS scavenger. Moreover, patients positive for anti‐SRP antibodies manifested worse diastolic but equivalent systolic function compared to their counterparts after propensity score matching. Conclusion Anti‐SRP antibodies may play a pathogenic role in the development of LVDD by promoting ROS production and subsequent myocardial mitochondrial impairment. The inhibition of oxidative stress was effective in reversing anti‐SRP antibody‐induced LVDD.

Background Catestatin has been reported as a pleiotropic cardioprotective peptide. Heart failure with preserved ejection fraction (HFpEF) was considered a heterogeneous syndrome with a complex cause. We sought to investigate the role of catestatin in HFpEF and diastolic dysfunction. METHODS AND RESULTS Administration of recombinant catestatin (1.5 mg/kg/d) improved diastolic dysfunction and left ventricular chamber stiffness in transverse aortic constriction mice with deoxycorticosterone acetate pellet implantation, as reflected by Doppler tissue imaging and pressure‐volume loop catheter. Less cardiac hypertrophy and myocardial fibrosis was observed, and transcriptomic analysis revealed downregulation of mitochondrial electron transport chain components after catestatin treatment. Catestatin reversed mitochondrial structural and respiratory chain component abnormality, decreased mitochondrial proton leak, and reactive oxygen species generation in myocardium. Excessive oxidative stress induced by Ru360 abolished catestatin treatment effects on HFpEF‐like cardiomyocytes in vitro, indicating the beneficial role of catestatin in HFpEF as a mitochondrial ETC modulator. The serum concentration of catestatin was tested among 81 patients with HFpEF and 76 non–heart failure controls. Compared with control subjects, serum catestatin concentration was higher in patients with HFpEF and positively correlated with E velocity to mitral annular e′ velocity ratio, indicating a feedback compensation role of catestatin in HFpEF. Conclusions Catestatin protects against diastolic dysfunction in HFpEF through attenuating mitochondrial electron transport chain–derived reactive oxygen species generation. Serum catestatin concentration is elevated in patients with HFpEF, probably as a relatively insufficient but self‐compensatory mechanism.

In this study, a C/TiC nanocomposite coating has been prepared by magnetron sputtering technology and vacuum heat treatment technology on a titanium surface, which is used for bipolar plates (BPs) in a proton exchange membrane fuel cell (PEMFC). This prepared C/TiC nanocomposite coating was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, electrochemical testing and interfacial contact resistance (ICR). The results show that a C/TiC nanocomposite coating consists of a single C surface layer (~28.88 nm) and TiC interface layer (~19.5 nm). In addition, compared with commercially pure titanium substrate (icorr = 345.10 μA cm−2), the corrosion resistance of a C/TiC nanocomposite coating (icorr = 0.74 μA cm−2) was greatly improved in 0.5 M H2SO4 + 5 ppm HF solution at 80 °C. The corrosion current density (icorr) decreased 3 orders of magnitude in a simulated cathodic environment. Moreover, the interfacial contact resistance of a C/TiC nanocomposite coating is 2.34 mΩ cm2 under 1.4 MPa compaction force, which is much lower than that of raw CP Ti (38.66 mΩ cm2).