RNA-Seq of Dermal Fibroblasts from Patients with Hypermobile Ehlers–Danlos Syndrome and Hypermobility Spectrum Disorders Supports Their Categorization as a Single Entity with Involvement of Extracellular Matrix Degrading and Proinflammatory Pathomechanisms

Abstract

Hypermobile Ehlers–Danlos syndrome (hEDS) and hypermobility spectrum disorders (HSD) are clinically overlapping connective tissue disorders of unknown etiology and without any validated diagnostic biomarker and specific therapies. Herein, we in-depth characterized the cellular phenotype and gene expression profile of hEDS and HSD dermal fibroblasts by immunofluorescence, amplicon-based RNA-seq, and qPCR. We demonstrated that both cell types show a common cellular trait, i.e., generalized extracellular matrix (ECM) disarray, myofibroblast differentiation, and dysregulated gene expression. Functional enrichment and pathway analyses clustered gene expression changes in different biological networks are likely relevant for the disease pathophysiology. Specifically, the complex gene expression dysregulation (mainly involving growth factors, structural ECM components, ECM-modifying enzymes, cytoskeletal proteins, and different signal transducers), is expected to perturb many ECM-related processes including cell adhesion, migration, proliferation, and differentiation. Based on these findings, we propose a disease model in which an unbalanced ECM remodeling triggers a vicious cycle with a synergistic contribution of ECM degradation products and proinflammatory mediators leading to a functional impairment of different connective tissues reflecting the multisystemic presentation of hEDS/HSD patients. Our results offer many promising clues for translational research aimed to define molecular bases, diagnostic biomarkers, and specific therapies for these challenging connective tissue disorders.

Looking back and beyond the 2017 diagnostic criteria for hypermobile Ehlers‐Danlos syndrome: A retrospective cross‐sectional study from an Italian reference center

“…Overall, our results offer an exhaustive clinical context to the ongoing dispute over whether hEDS and HSD should be categorized as distinct disorders or as variants of the same condition. Based on the clinical experience presented here, our previously published findings, showing a common myofibroblast‐like cellular phenotype and dysregulated transcriptional profile in hEDS and HSD patients' dermal fibroblasts (Ritelli et al, 2022; Zoppi et al, 2018), and ongoing in vivo studies, we firmly believe that the majority of individuals classified as hEDS and HSD should be placed along a continuous phenotypic spectrum. Considering the clinical and molecular evidence that we have gathered, we advocate for a revision of the 2017 diagnostic criteria.…”

“…This is especially true for HSD patients living in nations with a public healthcare system, such as Italy, where, unlike hEDS, HSD is not officially recognized and thus exemptions are not provided, creating debilitating care gaps, financial hardship, and injustices leading to psychological distress for patients diagnosed with this condition, further exacerbating their poor quality of life. Based on our clinical experience and cellular and molecular evidence we have gathered on hEDS and HSD patients' fibroblasts (Ritelli et al, 2022; Zoppi et al, 2018) and in ongoing in vivo studies, we propose revising the 2017 diagnostic criteria for hEDS to be more inclusive, using the latest knowledge about clinical findings and laboratory abnormalities. Expanding the diagnostic criteria could officially recognize a wider spectrum of patients who deserve an official diagnosis and appropriate care and support, while constraining the vague HSD umbrella term.…”

Joint Hypermobility Syndrome and Membrane Proteins: A Comprehensive Review

“…Mutations occurring in collagen genes, notably types III and V, are significant contributors to the development of Ehlers-Danlos syndrome (EDS). Furthermore, the functions of other ECM constituents, such as tenascin XB (TNXB), vitronectin (VTN), and proteoglycans and glycosaminoglycans (GAGs), are explored within the context of regulating connective tissue equilibrium and understanding pathogenesis [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Acquiring insights into these mechanisms is imperative for the advancement of targeted therapeutic interventions and enhancing the clinical management of connective tissue disorders [37][38][39][40].…”

“…Several mutations in type V collagen have been discovered in JHS/EDS-HT, including COL5A1 and COL5A2 (Figure 1). In addition to mutations in types I and III collagen (COL1A1, COL1A2, and COL3A1), these mutations exhibit an autosomal dominant inheritance pattern in JHS/EDS-HT [23][24][25][26]. Approximately fifty percent of point mutations are observed within the glycine residues of the G-X-Y tripeptide unit, constituting the repetitive sequence of the triple helix [41,42].…”

“…Besides these points, nowadays, attempts to diagnose this syndrome are based on the 2017 diagnostic criteria [8,19,20], since no instrumental, histopathological, structural, or molecular information is currently available to be used as a specific biomarker [21,22]. However, some patients whose signs and symptoms do not fit completely with the 2017 diagnostic criteria are not officially recognized by all healthcare systems and are categorized only as having hypermobility syndrome disorder (HSD) [23,24].…”