Angiogenic and intraplatelet growth biomarkers in systemic sclerosis

Systemic sclerosis (SSc) is a systemic autoimmune disease characterized by vasculopathy, immune system dysregulation, and fibrosis. There is growing evidence regarding the role of platelets in innate immunity and inflammatory processes, as they are an important source of mediators that may be key factors in the pathogenesis of SSc. Here we study the intraplatelet and plasma levels of various growth factors (GFs) and angiogenic factors in patients with SSc. The sample included 23 SSc patients and 16 controls. We determined the subjects' levels of factors (TGF-β, VEGF-A, PDGF-BB, FGF2, G-CSF, HGF, MCP-1), interleukins (IL-1α, IL-1β, IL-6, IL-8, IL-13), serotonin, and histamine in platelet-rich plasma (PRP) and platelet-poor plasma (PPP) samples obtained by apheresis. We quantify the factors using multiplex immunoassays. The results were normalized to plateletcrit. P -values ≤0.05 were considered statistically significant. The intraplatelet levels of the factors analyzed in this study were greater than the plasma levels in both the patients and control groups ( P ≤ 0.05). The intergroup comparison (patients vs. controls) revealed that all the factors were at similar levels in PRP and PPP, apart from VEGF-A, which was lower in PRP samples from SSc patients compared to controls (193.10 pg/mL vs. 574.31 pg/mL; P < 0.0001). We only found significant differences in VEFG-A which was lower in PRP collected from SSc patients compared to controls. We should ask ourselves whether platelets as such lack VEGF-A, making them less effective in angiogenesis and the tissue repair process. • VEGF-A levels are lower in PRP samples from SSc compared to healthy controls. • The PRP and PPP samples were obtained using plateletpheresis. This procedure yields high-quality platelet lysate sample and represents added value when trying to obtain more reliable results. • We use the plateletcrit to normalize the levels of the factors analyzed. This methodological approximation can be helpful to draw comparisons between studies carry on in PRPs.