Identification of potential microRNAs and KEGG pathways in denervation muscle atrophy based on meta-analysis

Neutrophil-macrophage communication via extracellular vesicle transfer promotes itaconate accumulation and ameliorates cytokine storm syndrome

Cytokine storm syndrome (CSS) is a life-threatening systemic inflammatory syndrome involving innate immune hyperactivity triggered by various therapies, infections, and autoimmune conditions. However, the potential interplay between innate immune cells is not fully understood. Here, using poly I:C and lipopolysaccharide (LPS)-induced cytokine storm models, a protective role of neutrophils through the modulation of macrophage activation was identified in a CSS model. Intravital imaging revealed neutrophil-derived extracellular vesicles (NDEVs) in the liver and spleen, which were captured by macrophages. NDEVs suppressed proinflammatory cytokine production by macrophages when cocultured in vitro or infused into CSS models. Metabolic profiling of macrophages treated with NDEV revealed elevated levels of the anti-inflammatory metabolite, itaconate, which is produced from cis-aconitate in the Krebs cycle by cis-aconitate decarboxylase (Acod1, encoded by Irg1). Irg1 in macrophages, but not in neutrophils, was critical for the NDEV-mediated anti-inflammatory effects. Mechanistically, NDEVs delivered miR-27a-3p, which suppressed the expression of Suclg1, the gene encoding the enzyme that metabolizes itaconate, thereby resulting in the accumulation of itaconate in macrophages. These findings demonstrated that neutrophil-to-macrophage communication mediated by extracellular vesicles is critical for promoting the anti-inflammatory reprogramming of macrophages in CSS and may have potential implications for the treatment of this fatal condition.

Pleiotrophin-Neuregulin1 promote axon regeneration and sorting in conduit repair of critical nerve gap injuries

Significant challenges remain in the treatment of critical nerve gap injuries using artificial nerve conduits. We previously reported successful axon regeneration across a 40 mm nerve gap using a biosynthetic nerve implant (BNI) with multi-luminal synergistic growth factor release. However, axon sorting, remyelination, and functional recovery were limited. Neuregulin1 (NRG1) plays a significant role in regulating the proliferation and differentiation of Schwann cells (SCs) during development and after injury. We hypothesize that the release of NRG1 type III combined with pleiotrophin (PTN) in the BNI will enhance axon growth, remyelination, and function of regenerated nerves across a critical gap. A rabbit 40 mm peroneal gap injury model was used to investigate the therapeutic efficacy of BNIs containing either NRG1, PTN, or PTN+NRG1 growth factor release. We found that NRG1 treatment doubled the number of regenerated axons (1276±895) compared to empty controls (633±666) and PTN tripled this number (2270±989). NRG1 also significantly increased the number of SOX10+ Schwann cells in mid-conduit (20.42%±11.78%) and reduced the number of abnormal Remak axon bundles. The combination of PTN+NRG1 increased axon diameter (1.70±1.06) vs control (1.21±0.77) (p<0.01), with 15.35% of axons above 3 μm, comparable to autograft. However, the total number of remyelinated axons was not increased by the added NRG1 release, which correlated with absence of axonal NRG1 type III expression in the regenerated axons. Electrophysiological evaluation showed higher muscle force recruitment (23.8±16.0 mN vs 17.4±1.4 mN) and maximum evoked compound motor action potential (353 μV vs 37 μV) in PTN-NRG1 group versus control, which correlated with the improvement in the toe spread recovery observed in PTN-NRG1 treated animals (0.64±0.02) vs control (0.50±0.01). These results revealed the need of a combination of pro-regenerative and remyelinating growth factor combination therapy for the repair of critical nerve gaps.

MicroRNA-142a-3p regulates neurogenic skeletal muscle atrophy by targeting Mef2a

Peripheral nerve injury can lead to progressive muscle atrophy and poor motor function recovery, which is a difficult point of treatment, and the mechanism needs to be further explored. In previous studies, we found that miR-142a-3p was significantly upregulated and persistently highly expressed in denervated mouse skeletal muscle. Here, we show that overexpression of miR-142a-3p inhibited the growth and differentiation of C2C12 myoblast, while knockdown of miR-142a-3p had a promoting effect. In vitro, knockdown of miR-142a-3p in denervated mouse skeletal muscle effectively increased proliferating muscle satellite cells and ameliorated muscle atrophy. Mechanistically, the myoregulator Mef2a was proved to be an important downstream target of miR-142a-3p, and miR-142a-3p regulates skeletal muscle differentiation and regeneration by inhibiting the expression of Mef2a. The co-knockdown of Mef2a and miR-142a-3p effectively alleviated or offset the biological effects of miR-142a-3p knockdown. In conclusion, our data revealed that miR-142a-3p regulates neurogenic skeletal muscle atrophy by targeting Mef2a.

Qing`e Pill Inhibits Osteoblast Ferroptosis via ATM Serine/Threonine Kinase (ATM) and the PI3K/AKT Pathway in Primary Osteoporosis

Osteoporosis (OP) is an aging-related disease that is the main etiology of fragility fracture. Qing’e Pill (QEP) is a mixture of traditional Chinese medicine (TCM) consisting of Eucommia ulmoides Oliv., Psoralea corylifolia L., Juglans regia L., and Allium sativum L. QEP has an anti-osteoporosis function, but the underlying mechanism remains unclear. In this study, online databases were employed to determine the chemical compounds of QEP and potential target genes in osteoporosis. Potential pathways associated with genes were defined by Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) databases. A compound–target–disease network was constructed. Hub genes screened through Cytoscape were intersected with the FerrDB database. The potential key genes were validated in HFOB 1.19 cells, and rat models were ovariectomized through Western blot, RT-qPCR, ELISA, HE staining, immunohistochemistry, and immunofluorescence analyses. The intersection targets of QEP and osteoporosis contained 121 proteins, whereas the target–pathway network included 156 pathways. We filtered five genes that stood out in the network analysis for experimental verification. The experiments validated that QEP exerted therapeutic effects on osteoporosis by inhibiting ferroptosis and promoting cell survival via the PI3K/AKT pathway and ATM. In conclusion, combining the application of network analysis and experimental verification may provide an efficient method to validate the molecular mechanism of QEP on osteoporosis.