Longitudinal Course of Circulating miRNAs in a Patient with Hypophosphatasia and Asfotase alfa Treatment: a Case Report

Abstract

Hypophosphatasia (HPP) is a rare genetic bone disease characterized by low activity of tissue non-specific alkaline phosphatase (TNSALP). The enzyme replacement therapy asfotase alfa has been approved for childhood-onset forms of HPP. MicroRNAs (miRNAs) have emerged recently as a novel disease biomarker, with potential application in therapy monitoring. Circulating miRNAs were analyzed at baseline, months 1, 2, 4 and 16 in a 49-year-old woman with childhood-onset HPP, chronic musculoskeletal pain and multiple non-traumatic fractures prior to enzyme replacement therapy. Serum RNA was extracted and sequenced using miRNeasy Mini Kit (Qiagen, Germany), RealSeq Biosciences Kit (Santa Cruz, US) together with miND spike-in control kit (TAmiRNA, Austria) and Illumina NovaSeq 6000 SP1 flow cell (San Diego, US). Brief Pain Inventory Severity and Interference scores (BPI-S/BPI-I), fatigue severity scale (FSS), Patient Global Impression of Improvement (PGI-I), Western Ontario and McMaster university hip disability and osteoarthritis outcome score (WOMAC) and fibromyalgia impact questionnaire (FIQ), 6-Minute Walking Test (6-MWT), chair-rise-test (CRT) and handgrip dynamometry (HD) were performed at baseline and different timepoints during the therapy. Out of >800 screened, 84 miRNAs were selected based on differences in expression profiles between 24 HPP patients and 24 healthy controls (Haschka et al. 2024). Six miRNAs showed a clear graphic trend and were up- or downregulated by ≥50% reads per million (rpm). These included hsa-let-7i-5p (+50%), hsa-miR-1-3p (-66.66%), hsa-miR-1294 (+63.63%), hsa-miR-206 (-85.57%), hsa-miR-375-3p (-71.43%) and hsa-miR-624-5p (+69,44%). hsa-miR-1-3p and hsa-miR-206 were identified as muscle-specific miRNAs. hsa-mir-375-3p, which negatively regulates osteogenesis, was significantly downregulated. In terms of patient-reported outcomes, BPI-S, BPI-I, FSS, PGI-I, WOMAC and FIQ showed a reduction by -58.62%, -68.29%, -33,33%, -75.00%, -63.29% and -43.02%, respectively. 6-MWT improved by +33,89% and CRT by -44.46%. Mean hand grip strength of the right/left hand measured by HD improved by +12.50% and + 23.53%, respectively. miRNA profile changes during the therapy with asfotase alfa, accompanying improvements in functionality tests and quality of life scores.