FGF13 enhances the function of TRPV1 by stabilizing microtubules and regulates acute and chronic itch.

Itching is an aversive somatosensation that triggers the desire to scratch. Transient receptor potential (TRP) channel proteins are key players in acute and chronic itch. However, whether the modulatory effect of fibroblast growth factor 13 (FGF13) on acute and chronic itch is associated with TRP channel proteins is unclear. Here, we demonstrated that conditional knockout of Fgf13 in dorsal root ganglion neurons induced significant impairment in scratching behaviors in response to acute histamine-dependent and chronic dry skin itch models. Furthermore, FGF13 selectively regulated the function of the TRPV1, but not the TRPA1 channel on Ca2+ imaging and electrophysiological recordings, as demonstrated by a significant reduction in neuronal excitability and current density induced by TRPV1 channel activation, whereas TRPA1 channel activation had no effect. Changes in channel currents were also verified in HEK cell lines. Subsequently, we observed that selective modulation of TRPV1 by FGF13 required its microtubule-stabilizing effect. Furthermore, in FGF13 knockout mice, only the overexpression of FGF13 with a tubulin-binding domain could rescue TRP channel function and the impaired itch behavior. Our findings reveal a novel mechanism by which FGF13 is involved in TRPV1-dependent itch transduction and provide valuable clues for alleviating pathological itch syndrome.

Inducible Fgf13 ablation alleviates cardiac fibrosis via regulation of microtubule stability.

Fibroblast growth factor (FGF) isoform 13, a distinct type of FGF, boasts significant potential for therapeutic intervention in cardiovascular dysfunctions. However, its impact on regulating fibrosis remains unexplored. This study aims to elucidate the role and mechanism of FGF13 on cardiac fibrosis. Here, we show that following transverse aortic constriction (TAC) surgery, interstitial fibrosis and collagen content increase in mice, along with reduced ejection fraction and fractional shortening, augmented heart mass. However, following Fgf13 deletion, interstitial fibrosis is decreased, ejection fraction and fractional shortening are increased, and heart mass is decreased, compared with those in the TAC group. Mechanistically, incubation of cardiac fibroblasts with transforming growth factor ß (TGFß) increases the expressions of types I and III collagen proteins, as well as α-smooth muscle actin (α-SMA) proteins, and enhances fibroblast proliferation and migration. In the absence of Fgf13, the expressions of these proteins are decreased, and fibroblast proliferation and migration are suppressed, compared with those in the TGFß-stimulated group. Overexpression of FGF13, but not FGF13 mutants defective in microtubule binding and stabilization, rescues the decrease in collagen and α-SMA protein and weakens the proliferation and migration function of the Fgf13 knockdown group. Furthermore, Fgf13 knockdown decreases ROCK protein expression via microtubule disruption. Collectively, cardiac Fgf13 knockdown protects the heart from fibrosis in response to haemodynamic stress by modulating microtubule stabilization and ROCK signaling pathway.

Fatal unexpected death due to X-linked lymphoproliferative disease.

X-linked lymphoproliferative disease (XLP) is a rare immunodeficiency disease characterized by severe immune disorder and extreme vulnerability to Epstein-Barr virus (EBV) infections. Here we report a 14-month-old Chinese boy presenting with fulminant infectious mononucleosis (FIM) following EBV infection, and died of hepatic failure within one week of disease progression. Postmortem examination revealed icterus, ascites, extensive enlarged mesenteric lymphnodes and hepatosplenomegaly. Histopathological examination showed diffuse proliferation of cytotoxic T lymphoid cells and hemophagocytosis in multiple organs. The family history revealed his brother had died under similar circumstances at 5 five years of age. The cause of death of the boy was ascribed to XLP. To the best of our knowledge, there is few autopsy-confirmed XLP case in the forensic practice. The complicatedmanifestations and systemic pathological changes should be well recognized by clinicians and forensic pathologists.

Sudden cardiac death owing to arrhythmogenic right ventricular cardiomyopathy: Two case reports and systematic literature review.

BACKGROUND AND OBJECTIVE: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is increasingly recognized in forensic practice with controversial diagnosis. Here we described the epidemiological characteristics and reported the pathogenetic mechanism, diagnostic challenges, and forensic implications of Chinese ARVC autopsy cases. METHODS: Two cases of sudden cardiac death owing to ARVC were reported. Retrospective analysis were performed on such 2 cases and 45 cases of separate ARVC complete autopsy case reports through Chinese literature databases in the last 30 years. RESULTS: There were 27 males and 20 females, and the mean age at death was 35 years. Sudden cardiac death was the first manifestation observed in most patients, with no previous family and medical history. Exercise, acute stress, increased cardiac workload, and ethanol are frequently involved. The mean heart weight was 393 g (range, 240-590 g), and 10 cases had relative heart hypertrophy. Microscopic abnormalities included replacement of myocardium by adipose infiltration in 68.09% cases and fibroadipose in 31.91% cases; 80.85% cases were restricted to the right ventricle (RV), whereas biventricular subtype was seen in the remaining 19.15% cases. The preliminary quantitative histology showed 60.7% of fat tissues, 12.1% of fibrosis, and 27.2% residual myocytes in RV. Inflammatory cell infiltration was found in 25.53% cases, but myocyte necrosis was found in only 1 case. In 10.64% of cases, cardiac conduction was infiltrated by fibrosis, adipose, or both. CONCLUSION: In this review, the most characteristic and distinct histopathologic features that are diagnostic or highly suggestive of ARVC for forensic pathologists were identified. Combining gross and histological examinations with postmortem genetic analysis is recommended for identifying ARVC.