AUTHOR=Boccanegra Brigida , Cappellari Ornella , Mantuano Paola , Trisciuzzi Daniela , Mele Antonietta , Tulimiero Lisamaura , De Bellis Michela , Cirmi Santa , Sanarica Francesca , Cerchiara Alessandro Giovanni , Conte Elena , Meanti Ramona , Rizzi Laura , Bresciani Elena , Denoyelle Severine , Fehrentz Jean-Alain , Cruciani Gabriele , Nicolotti Orazio , Liantonio Antonella , Torsello Antonio , De Luca Annamaria 

TITLE=Growth hormone secretagogues modulate inflammation and fibrosis in mdx mouse model of Duchenne muscular dystrophy

JOURNAL=Frontiers in Immunology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2023.1119888

DOI=10.3389/fimmu.2023.1119888

ISSN=1664-3224

ABSTRACT=<sec><title>Introduction</title><p>Growth hormone secretagogues (GHSs) exert multiple actions, being able to activate GHS-receptor 1a, control inflammation and metabolism, to enhance GH/insulin-like growth factor-1 (IGF-1)-mediated myogenesis, and to inhibit angiotensin-converting enzyme. These mechanisms are of interest for potentially targeting multiple steps of pathogenic cascade in Duchenne muscular dystrophy (DMD).</p></sec><sec><title>Methods</title><p>Here, we aimed to provide preclinical evidence for potential benefits of GHSs in DMD, <italic>via</italic> a multidisciplinary <italic>in vivo</italic> and <italic>ex vivo</italic> comparison in <italic>mdx</italic> mice, of two <italic>ad hoc</italic> synthesized compounds (EP80317 and JMV2894), with a wide but different profile. 4-week-old <italic>mdx</italic> mice were treated for 8 weeks with EP80317 or JMV2894 (320 µg/kg/d, s.c.).</p></sec><sec><title>Results</title><p><italic>In vivo</italic>, both GHSs increased mice forelimb force (recovery score, RS towards WT: 20% for EP80317 and 32% for JMV2894 at week 8). In parallel, GHSs also reduced diaphragm (DIA) and gastrocnemius (GC) ultrasound echodensity, a fibrosis-related parameter (RS: ranging between 26% and 75%). <italic>Ex vivo</italic>, both drugs ameliorated DIA isometric force and calcium-related indices (<italic>e.g.</italic>, RS: 40% for tetanic force). Histological analysis highlighted a relevant reduction of fibrosis in GC and DIA muscles of treated mice, paralleled by a decrease in gene expression of <italic>TGF-β1</italic> and <italic>Col1a1</italic>. Also, decreased levels of pro-inflammatory genes (<italic>IL-6, CD68</italic>), accompanied by an increment in <italic>Sirt-1, PGC-1α</italic> and <italic>MEF2c</italic> expression, were observed in response to treatments, suggesting an overall improvement of myofiber metabolism. No detectable transcript levels of <italic>GHS receptor-1a</italic>, nor an increase of circulating IGF-1 were found, suggesting the presence of a novel receptor-independent mechanism in skeletal muscle. Preliminary docking studies revealed a potential binding capability of JMV2894 on metalloproteases involved in extracellular matrix remodeling and cytokine production, such as ADAMTS-5 and MMP-9, overactivated in DMD.</p></sec><sec><title>Discussion</title><p>Our results support the interest of GHSs as modulators of pathology progression in <italic>mdx</italic> mice, disclosing a direct anti-fibrotic action that may prove beneficial to contrast pathological remodeling.</p></sec>