Endothelial Progenitor Cell CD34⁺ and CD133⁺ Concentrations and Soluble HLA-G Concentrations During Pregnancy and in Cord Blood in Undifferentiated Connective Tissue Diseases Compared to Controls

The objective of this study is to evaluate endothelial progenitor cells (EPCs) CD34⁺ CD133^- and CD34⁺ CD133⁺ and soluble HLA-G (sHLA-G) concentrations among undifferentiated connective tissue disease (UCTD) subjects, compared to controls, during pregnancy and in cord blood. This is a case-control study including 29 controls and 29 UCTDs. CD34⁺ CD133^-, CD34⁺ CD133⁺, and sHLA-G concentrations were detected in maternal plasma and in cord blood. This study was approved by the Medical-Ethical Committee of our Institution (Current Research Project N. 901-rcr2017i-23 of IRCCS Foundation Policlinico San Matteo of Pavia). Circulating CD34⁺ CD133^- and CD34⁺ CD133⁺ counts and sHLA-G (soluble human leucocyte antigen G) concentrations in maternal peripherical blood were higher in UCTD compared to those in controls in first and third trimester of pregnancy and at delivery (p < 0.001). Maternal CD34⁺ CD133^- and CD34⁺ CD133⁺ counts were strongly and significantly correlated in UCTD (Spearman's rho = 0.79, p < 0.0001) but not in controls (Spearman's rho = 0.10, p = 0.35). Cord blood CD34⁺ CD133^- and CD34⁺ CD133⁺ median counts and median sHLA-G concentrations were higher among UCTD subjects than in controls (p < 0.001). Cord blood CD34⁺ and CD133⁺ counts were inversely and significantly correlated with sHLA-G concentrations among UCTDs, but not in controls. Early UCTD is characterized by increased EPC levels in maternal plasma and in cord blood and higher levels of sHLA-G, compared to controls. Data suggest that fetoplacental unit plays an independent role in the EPC response to a systemic autoimmune disease.