Stromal Cell-Derived Factor 1 Alpha (SDF-1α), Cartilage Oligomeric Matrix Protein (COMP) and Circulating microRNAs 208a-3p and 221-3p: Potential Signature Biomarkers of Hemophilic Arthropathy

Introduction.

Hemophilia A is a rare constitutional bleeding disorder due to a deficiency in Factor VIII. Recurrent hemarthroses, one of the major complications of the disease, lead to hemophilic arthropathy, a disabling condition difficult to diagnose with current strategies (ultrasound and magnetic resonance imaging [MRI]), with possible delayed diagnosis.

MRI, the gold standard, is not of easy access nor cheap and requires sedation in young children. Ultrasound is liable to inter-operator variability and difficult to apply to such joints as ankles, especially in children for whom this is the most frequently involved location of hemophilic arthropathy. Circulating MicroRNAs are a group of endogenous, small, non-coding RNA molecules that regulate gene expression ; and knowledge on the potential roles of miRNAs in haemophilia is very limited.

Aim.

The aim of this project was to assess plasmatic biomolecules indicative of osteo-cartilaginous damage in patients with hemophilia with or without known arthropathy, in order to improve the diagnosis of this major complication of the disease. We also investigated microRNA expression in patients with haemophilia A with and without inhibitors, compared to healthy controls.

Methods

In this monocentric retrospective study, 40 patients with hemophilia A or B, for whom a plasma sample was available, provided informed consent for further analyses (multiplex immunoassays and ELISA) and collection of relevant clinical information in their medical files. Correlations were sought for between biomarkers of interest and the severity of joint lesions assessed according to Pettersson radiologic score.

For miRNAs analysis, all RNAs were extracted from plasma samples. We synthesised complementary DNA from the RNA samples, and used to quantitative PCR and microarray analysis to allow us to look at changes in expression levels.

Results

Two biomarkers were identified, respectively SDF-1α and COMP. Their plasmatic levels were significantly increased in patients with arthropathy compared to controls and patients without arthropathy. These values correlated significantly with the Pettersson score in patients under regular prophylaxis.

We also identified two microRNAs of interest, the microRNA 208a-3p was significantly downregulated in hemophilia patients with arthropathy but not in patients without arthropathy and the microRNA 221-3p had a clear tendency for statistically significant down regulation in hemophiliacs with arthropathy. Interestingly, miRNA 221-3p has been shown to be involved in rheumatoid arthritis. Dysregulation of this microRNA leads to a reduced anti-inflammatory response and drives macrophages into a pro-inflammatory state.

Conclusion

Two plasma proteins SDF-1 alfa and COMP and two circulating micro-RNAs have been identified as potential biomarkers that could help physicians to assess the presence and severity of hemophilic arthropathy.