Myeloid cell-specific mutation of Spi1 selectively reduces M2-biased macrophage numbers in skeletal muscle, reduces age-related muscle fibrosis and prevents sarcopenia

Single-Cell RNA Sequencing Reveals a Unique Fibroblastic Subset and Immune Disorder in Lichen Sclerosus Urethral Stricture

Purpose

Lichen sclerosus urethral stricture disease (LS USD) is a refractory and progressive disease primarily affecting the anterior urethra in males. Various potential etiological factors, such as genetics, autoimmunity, infection, and exposure to infectious urine, have been suggested. However, the accurate etiology of LS in the male urethra remains unclear.

Patients and Methods

In this study, we conducted single-cell RNA sequencing to identify the transcriptional profiles of three patients with LS USD and three patients with non-LS USD. Immunofluorescence was used to confirm the single-cell sequence results.

Results

Our study revealed distinct subsets of vein endothelial cells (ECs), smooth muscle cells (SMCs), and fibroblasts (FBs) with high proportions in LS USD, contributing to the tissue microenvironment primarily involved in proinflammatory and immune responses. In particular, FBs displayed a unique subset, Fib7, which is exclusively present in LS USD, and exhibited high expression levels of SAA1 and SAA2. The accumulation of macrophages, along with the dysregulated ratios of M1/M2-like phenotype macrophages, may be engaged in the pathogenesis of LS USD. Through cell-cell communication analysis, we identified significant interactions involving CXCL8/ACKR1 and CCR7/CCL19 in LS USD. Remarkably, Fib7 exhibited exclusive communication with IL-1B macrophages through the SAA1/FPR2 receptor-ligand pair.

Conclusion

Our study provides a profound understanding of the tissue microenvironment in LS USD, which may be valuable for understanding the pathogenesis of LS USD.

Interleukin 25 promotes muscle regeneration in sarcopenia by regulating macrophage-mediated Sonic Hedgehog signaling

OBJECTIVE

Sarcopenia manifests as a chronic, low-level inflammation along with multiple inflammatory cells infiltration. Interleukin (IL)-25 can regulate the function of macrophages. However, the specific role and mechanisms through which IL-25 functions in sarcopenia are still not fully understood and require further investigation.

METHODS

Aged mice were utilized as sarcopenia models and examined the expression of inflammatory factors. To investigate the effects of IL-25 on sarcopenia, the model mice received IL-25 treatment and underwent in vivo adoptive transfer of IL-25-induced macrophages. Meanwhile, RAW264.7 cells, bone marrow-derived macrophages, satellite cells and C2C12 cells were used in vitro. Shh insufficiency was induced through intramuscular administration of SHH-shRNA adenoviruses. Then, various assays including scratch wound, cell counting kit-8 and Transwell assays, as well as histological staining and molecular biological methods, were conducted.

RESULTS

Aged mice exhibited an accelerated decline in muscle strength and mass, along with an increased muscle lipid droplets and macrophage infiltration, and decreased IL-25 levels compared to the young group. IL-25 therapy and the transfer of IL-25-preconditioned macrophages could improve these conditions by promoting M2 macrophage polarization in vivo as well as in vitro. M2 macrophage conditioned medium enhanced satellite cell proliferation and migration, as well as the vitality, migration, and differentiation of C2C12 cells in vitro. Furthermore, IL-25 enhanced Shh expression in macrophages in vitro, and activated the Shh signaling pathway in muscle tissue of aged mice, which could be suppressed by either the inhibitor cyclopamine or Shh knockdown. Mechanistic studies showed that Shh insufficiency suppressed the activation of Akt/mTOR signaling pathway in muscle tissue of aged mice.

CONCLUSION

IL-25 promotes the secretion of Shh by M2 macrophages and activates the Shh/Akt/mTOR signaling pathway, which improves symptoms and function in sarcopenia mice. This suggests that IL-25 has potential as a therapeutic agent for treating sarcopenia.

Identification of the cuproptosis-related hub genes and therapeutic agents for sarcopenia

Background: Along with acceleration of population aging, the increasing prevalence of sarcopenia has posed a heavy burden on families as well as society. In this context, it is of great significance to diagnose and intervene sarcopenia as early as possible. Recent evidence has indicated the role of cuproptosis in the development of sarcopenia. In this study, we aimed to seek the key cuproptosis-related genes that can be used for identification and intervention of sarcopenia.

Methods: The GSE111016 dataset was retrieved from GEO. The 31 cuproptosis-related genes (CRGs) were obtained from previous published studies. The differentially expressed genes (DEGs) and Weighed gene co-expression network analysis (WGCNA) were subsequently analyzed. The core hub genes were acquired by the intersection of DEGs, WGCNA and CRGs. Through logistic regression analysis, we established a diagnostic model of sarcopenia based on the selected biomarkers and was validated in muscle samples from GSE111006 and GSE167186. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analysis were performed on these genes. Furthermore, the gene set enrichment analysis (GSEA), and immune cell infiltration were also conducted on the identified core genes. Finally, we screened the potential drugs targeting the potential biomarkers of sarcopenia.

Results: A total of 902 DEGs and WGCNA containing 1,281 significant genes were preliminarily selected. Intersection of DEGs, WGCNA and CRGs yielded four core genes (PDHA1, DLAT, PDHB, and NDUFC1) as potential biomarkers for the prediction of sarcopenia. The predictive model was established and validated with high AUC values. KEGG pathway and Gene Ontology biological analysis indicated these core genes may play a crucial role in energy metabolism in mitochondria, oxidation process, and aging-related degenerative diseases. In addition, the immune cells may be involved in the development of sarcopenia through mitochondrial metabolism. Finally, metformin was identified as a promising strategy of sarcopenia treatment via targeting NDUFC1.

Conclusion: The four cuproptosis-related genes PDHA1, DLAT, PDHB and NDUFC1 may be the diagnostic biomarkers for sarcopenia, and metformin holds great potential to be developed as a therapy for sarcopenia. These outcomes provide new insights for better understanding of sarcopenia and innovative therapeutic approaches.

The roles of ETS transcription factors in liver fibrosis

E26 transformation specific or E twenty-six (ETS) protein family consists of 28 transcription factors, five of which, named ETS1/2, PU.1, ERG and EHF, are known to involve in the development of liver fibrosis, and are expected to become diagnostic markers or therapeutic targets of liver fibrosis. In recent years, some small molecule inhibitors of ETS protein family have been discovered, which might open up a new path for the liver fibrosis therapy targeting ETS. This article reviews the research progress of ETS family members in the development liver fibrosis as well as their prospect of clinical application.