G-MDSCs promote aging-related cardiac fibrosis by activating myofibroblasts and preventing senescence.

Aging is one of the most prominent risk factors for heart failure. Myeloid-derived suppressor cells (MDSCs) accumulate in aged tissue and have been confirmed to be associated with various aging-related diseases. However, the role of MDSCs in the aging heart remains unknown. Through RNA-seq and biochemical approaches, we found that granulocytic MDSCs (G-MDSCs) accumulated significantly in the aging heart compared with monocytic MDSCs (M-MDSCs). Therefore, we explored the effects of G-MDSCs on the aging heart. We found that the adoptive transfer of G-MDSCs of aging mice to young hearts resulted in cardiac diastolic dysfunction by inducing cardiac fibrosis, similar to that in aging hearts. S100A8/A9 derived from G-MDSCs induced inflammatory phenotypes and increased the osteopontin (OPN) level in fibroblasts. The upregulation of fibroblast growth factor 2 (FGF2) expression in fibroblasts mediated by G-MDSCs promoted antisenescence and antiapoptotic phenotypes of fibroblasts. SOX9 is the downstream gene of FGF2 and is required for FGF2-mediated and G-MDSC-mediated profibrotic effects. Interestingly, both FGF2 levels and SOX9 levels were upregulated in fibroblasts but not in G-MDSCs and were independent of S100A8/9. Therefore, a novel FGF2-SOX9 signaling axis that regulates fibroblast self-renewal and antiapoptotic phenotypes was identified. Our study revealed the mechanism by which G-MDSCs promote cardiac fibrosis via the secretion of S100A8/A9 and the regulation of FGF2-SOX9 signaling in fibroblasts during aging.

[Clinical and biopsy-based myopathological features of 5 cases with centronuclear myopathy].

OBJECTIVE: To analyze the clinical and pathological features of the centronuclear myopathy (CNM) in 5 Chinese patients and evaluate their diagnostic and differential diagnostic value. METHODS: A standard series of histochemical and enzymohistochemical investigations were performed on all muscle specimens of CNM cases obtained via biopsy. The clinical manifestations and myopathological features of 5 CNM patients were retrospectively analyzed. RESULTS: The age of onset ranged from 3 to 12 years. All patients primarily presented with limb girdle muscle weakness. In 3 patients extraocular muscles, facial muscles and cervical muscles were affected, respectively. The proximal muscles were affected more seriously than the distal and the lower limbs more seriously than the upper. Tendon reflex was reduced and no evident muscular atrophy was seen. The course of the disease ranged from 4 to 46 years and progressed slowly. The ability of walking could be maintained for many years and the fast movements such as running and jumping were impaired early. The serum creatine kinase (CK) level was normal or elevated slightly. Electromyography showed myopathic pattern in all cases. Two patients (mother and son) were from the same family and the son's two siblings had similar symptoms indicating autosomal dominant inherited pattern. There was mild variation in fiber size and most small fibers were round. Interstitial tissue increase slightly. Fibers with centrally placed nuclei accounted for 23% - 93%. Neither necrotic and regenerated fibers nor infiltration of inflammatory cells were seen. Type I fiber predominance and hypotrophy were present in all patients. Abnormal arrangement of the sarcoplasmic strands in appearance of "spokes of a wheel", increased oxidative enzyme activity around centronuclear and perinuclear halo were observed in 2 patients by NADH-TR staining. CONCLUSIONS: For the patients who had the onset during the childhood and presented with slow progressive limb girdle muscle weakness, disability of fast movements and normal serum CK level, the possibility of benign congenital myopathy should be considered. High percentage of centronuclear fibers as well as type I fiber predominance and hypotrophy in muscle biopsy pathology may provide a morphological evidence for the definite diagnosis of CNM.

[Clinical and pathological features and prognosis of Chinese patients with distal myopathy with rimmed vacuoles: study of 17 cases].

OBJECTIVE: To clarify the clinical and pathological features and prognosis of Chinese patients with distal myopathy with rimmed vacuoles (DMRV). METHODS: The clinical data of 17 Chinese DMRV patients with the courses of disease of 1-21 years, 5 males and 12 females, aged 28.9 (19-41), were collected. Biopsy of muscle specimens of 17 Chinese DMRV patients were summarized retrospectively. Muscle specimens were collected from the biceps brachii, tibialis anterior, gastrocnemius, or quadriceps femoris and underwent light microscopy. Eight muscle specimens underwent electron microscopy. 11 patients were followed up for 4 months to 15 years. RESULTS: The age of onset ranged from 5 to 40 years (averaging 23 years). Distal muscle weakness and atrophy of the lower extremities, especially anterior tibial muscle, was predominant in the early stage. Proximal and trunk muscles were involved in the advanced stage. Quadriceps femoris were slightly involved. The striking and characteristic pathological finding was the presence of rimmed vacuoles in atrophic muscle fibers with little evidence of necrotic or regenerative processes. Electron microscopy showed accumulation of myeloid structure and cytoplasmic or intranuclear tubofilamentous inclusion bodies. Although atrophy and weakness of the leg muscle appeared as initial symptoms, severe generalized skeletal muscle involvement with sparing of the facial, extraocular, bulbar, intercostals, and diaphragm muscles was recognized in the advanced stage. The patients became non-ambulant about 7-10 years after the onset of the disease. They lost the self-care ability and the quality of their life was rather low. CONCLUSION: The clinical and pathological features of the Chinese DMRV patients are basically similar to those of the Japanese patients. With the disease progressing slowly, the patients become wheelchair-bound and lose the self-care ability. As to daily life, the prognosis of DMRV is extremely poor.

[Dysferlin expression in limb-girdle muscular dystrophy and Miyoshi myopathy: analysis of 45 cases].

OBJECTIVE: To clarify the expression patterns of dysferlin in limb-girdle muscular dystrophy (LGMD) and Miyoshi myopathy (MM), and to investigate the frequency and clinicopathologic features of dysferlinopathy. METHODS: The expressing patterns of dysferlin were analyzed by immunohistochemistry, with a set of antibodies against dystrophin, alpha-sarcoglycan and dysferlin, in the biopsied muscle specimens from 45 patients with LGMD or MM diagnosed on the basis of clinical manifestations and muscle pathological features. The specimens with abnormal dysferlin expression shown by IHC were further analyzed with Western blotting for a quantitative evaluation. RESULTS: Eight patients were proved to be primary dysferlinopathy according to total dysferlin deficiency or a significant decrease of dysferlin (less than 15% that of normal value). The clinical manifestations of 5 of the 8 dysferlinopathy patients were consistent with those of typical MM, and the other 3 were diagnosed as with LGMD. All patients had an average onset at the age of 18.8 years. Two of them had family history, and one patient had consanguineous mating parents, meaning an autosomal recessive inheritance pattern. The serum CK levels were 6240 IU/L on average. EMG showed myogenic patterns in all patients. Muscular pathology showed typical changes of muscular dystrophy in all patients. Focal or scattered inflammatory cellular infiltrations were found in 3 cases. CONCLUSION: The clinical and pathological features of dysferlinopathy are nonspecific. Inflammatory cellular infiltrations are relatively common in biopsied muscles of dysferlinopathy patients, which may cause misdiagnosis of inflammatory myopathy. Identification of dysferlin expression by IHC and Western blotting are essential for the diagnosis of dysferlinopathy and differential diagnosis of inflammatory myopathy.