Biology subjects

Bensalah, M.

Publications and source records attributed to Bensalah, M..

6 recordsLinked to original sources

bioRxiv2026

Aging remodels the human muscle secretome, impairing stem cell via sphingolipid metabolism

Aging reduces skeletal muscle regenerative capacity, but how the aged environment impairs muscle stem cells (MuSCs) remains unclear. Skeletal muscle acts as a secretory organ, yet age-related changes in its secretome and impact on stem cells are poorly understood. We performed proteomic and lipidomic analyses of conditioned media from primary muscle cells of young (15-25 years) and aged (60-86 years) donors. We identified 127 age-dependent secreted proteins, revealing major remodeling. The lysosomal enzyme acid sphingomyelinase (ASM), which converts sphingomyelin into ceramide, was the most upregulated factor. Recombinant ASM reduced PAX7+ MuSCs in young cultures, showing extracellular ASM impairs stem cell maintenance. Lipidomics revealed disruption of the sphingomyelin-ceramide-S1P axis, with decreased sphingomyelin and S1P, a lipid promoting MuSC proliferation. Exogenous S1P restored the stem cell pool in aged cultures. These findings link secretome remodeling and sphingolipid metabolism to MuSC decline and identify ASM and S1P as targets

cell biology↗

bioRxiv2026

Increased utrophin expression in healthy and DMD patient derived myoblasts in response to ERK1/2 and EZH2 inhibitor treatment

BackgroundThe X-linked muscle wasting disorder Duchenne muscular dystrophy (DMD) is a progressive and ultimately fatal disease caused by loss of function mutations in the dystrophin (DMD) gene. Upregulation of utrophin (UTRN), an embryonic homologue of dystrophin, has been proposed as a therapeutic option that could ameliorate disease. We previously generated a bioluminescent screen for utrophin-upregulating compounds using a mouse reporter of endogenous utrophin expression and discovered that inhibition of ERK1/2 and EZH2, increases utrophin expression in myoblasts. MethodologyHere we extend this analysis to show that treatment of human myoblasts with the ERK1/2 inhibitor LY3214996 and the EZH2 inhibitor GSK503, increases UTRN expression in primary and immortalised myoblasts derived from healthy volunteers and DMD patients. ResultsShort-term (24 hours) inhibition of ERK1/2 and EZH2 resulted in increased expression of utrophin in proliferating myoblasts. Surprisingly, in patient-derived samples, but not healthy controls, increased UTRN expression was sustained following drug removal and in vitro differentiation. Furthermore, dystrophin deficient myoblasts have altered expression of myogenic transcription factors MYOD1 and MYOG and proliferation marker Ki67, signalling an altered regenerative capacity of these cells, while ERK1/2 inhibition, alone or combined with EZH2i, reversed this transcriptional signature. ConclusionsTreatment with ERK1/2 and EZH2 inhibitors could offer a therapeutic option for DMD by increasing UTRN and MYOD1 expression. We propose that this may compensate for DMD loss and help restore productive muscle differentiation and regeneration.

pharmacology and toxicology↗

bioRxiv2026

Serotypic heterogeneity in the response to pneumococcal vaccine

The assessment of pneumococcal vaccine response currently relies on a single IgG concentration threshold, identical for all serotypes, as recommended by the WHO and AAAAI. However, the recommended thresholds do not take the wide inter-serotype variability into account. The purpose of this study was to determine if the antibody threshold linked to a functional immune response varies according to serotype. We performed a retrospective analysis on 729 samples from adults at risk of invasive pneumococcal disease (IPD), sent between 2018 and 2024 to assess vaccine response. Specific IgG concentrations for seven vaccine serotypes were measured by ELISA and compared to opsonophagocytic assay (OPA) results, a functional test considered as the gold standard. For each serotype, we determined the most predictive IgG concentration (PIC) for a positive OPA result using ROC curves, Youdens index, and bootstrap analysis with 1,000 resamples. The resulting PIC were then compared using non-parametric tests (Kruskal-Wallis test followed by Dunns post-hoc test with Holms correction). The PIC varied considerably among serotypes, ranging from 0.84 to 4.74 {micro}g/mL. This variability was found to be statistically significant (p<0.0001). Areas Under the Curve (AUC), ranging from 0.73 to 0.87, demonstrate good diagnostic performance. Overall, the application of serotype-specific thresholds in patients significantly change the classification of vaccination status compared to a single threshold (Cochran, McNemar). These results indicate that the protective antibody threshold is not universal. A serotype-specific approach would allow a more precise and relevant assessment of the pneumococcal vaccine response. Author summaryThe introduction of the 7-valent pneumococcal conjugate vaccine (PCV-7) in the early 2000s significantly changed the epidemiology of invasive pneumococcal disease by modifying serotype distribution. However, vaccine-induced immunity varies across serotypes, and this heterogeneity remains incompletely understood. In this study, we first assessed differences in vaccine responses according to serotype. We then determined predictive serotype-specific immunoglobulin concentration for the seven routinely serotypes tested in our laboratory, defined as the minimal levels required to induce a positive opsonophagocytic activity (OPA) response. The results enable a more accurate assessment of serotype-specific vaccine immunity, supporting improved patient stratification and guiding booster vaccination in individuals with insufficient responses.

immunology↗

bioRxiv2025

Collagen VI is a conserved pro-fibrotic signal disrupting muscle regeneration across distinct human myopathies

Muscle fibrosis is a major driver of progression in diverse myopathies, yet the conserved molecular mediators of this process in humans remains poorly defined. Here, we identify collagen VI as a common pro-fibrotic and regeneration-impairing extracellular matrix (ECM) component across three distinct human myopathies: Duchenne Muscular Dystrophy (DMD), Oculopharyngeal Muscular Dystrophy (OPMD), and Inclusion Body Myositis (IBM). Proteomic profiling of fibrotic biopsies revealed consistent upregulation of collagen VI and laminin {gamma}1, alongside disease-specific alterations involving other ECM proteins. Fibro-adipogenic progenitors (FAPs) are the predominant source of these ECM components, including collagen VI and laminin {gamma}1. Functionally, xenotransplantation of patient-derived FAPs into regenerating mouse muscle induced localized collagen deposition, myofiber atrophy, and depletion of Pax7 muscle stem cells. Mechanistic assays demonstrated that FAP-derived collagen VI is sufficient to impair myogenic fusion, while silencing COL6 in patient FAPs restores fusion capacity, directly linking pathological collagen VI deposition to regeneration failure. Our findings uncover collagen VI as a conserved effector of fibrosis and stem cell niche disruption in human myopathies, positioning it as a potential therapeutic target across genetically and clinically distinct muscle diseases.

cell biology↗

bioRxiv2025

EMILIN1 emerges as a TGFbeta/SETDB1-regulated secreted biomarker in Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy (DMD) is an incurable muscle-wasting disorder characterized by chronic membrane damage, inflammation, and progressive fibrosis. Fibrosis in DMD is driven by sustained TGF{beta} signaling, which promotes extracellular matrix (ECM) accumulation. We previously showed that SETDB1 sustains the TGF{beta}-induced fibrotic response in DMD myotubes. Here, we further show that SETDB1 modulates the TGF{beta}-induced secretome, particularly by regulating ECM-related proteins. Comparison of the basal secretome from DMD patient-derived myotubes and healthy controls revealed a distinct disease-specific profile. Integrating both secretome analyses, we identified EMILIN1, an ECM glycoprotein not previously studied in skeletal muscle, as a robust shared candidate; EMILIN1 is enriched in the DMD secretome, further upregulated by TGF{beta}, and downregulated upon SETDB1 depletion. We confirmed EMILIN1 overexpression in DMD patient muscle biopsies, validating its pathological relevance. Functionally, EMILIN1 depletion modulated myogenic differentiation and reduced expression of the fibrotic marker SERPINE1. These findings establish EMILIN1 as a novel secreted regulator of myogenesis and fibrosis, and implicate SETDB1 in shaping the TGF{beta}-dependent secretome in DMD. Our integrative proteomic approach provides new insights into the molecular drivers of impaired regeneration in DMD and highlights potential therapeutic targets.

genetics↗

bioRxiv2019

A gold standard method for human cell quantification after xenotransplantation

Xenotransplantation of human cells into immunodeficient mouse models is a very powerful tool and an essential step for the pre-clinical evaluation of therapeutic cell-and gene-based strategies. Here we describe an optimized protocol combining immunofluorescence and real-time quantitative PCR to both quantify and visualize the fate and localization of human myogenic cells after injection in regenerating muscles of immunodeficient mice. Whereas real-time quantitative PCR-based method provides an accurate quantification of human cells, it does not document their specific localization. The addition of an immunofluorescence approach using human-specific antibodies recognizing engrafted human cells gives information on the localization of the human cells within the host muscle fibres, in the stem cell niche or in the interstitial space.\n\nThese two combined approaches offer an accurate evaluation of human engraftment including cell number and localization and should provide a gold standard to compare results obtained either using different types of human stem cells or comparing healthy and pathological muscle stem cells between different research laboratories worldwide.

cell biology↗