Soluble HLA-G in pregnancies complicated by autoimmune rheumatic diseases

- Maternal sHLA-G levels in rheumatic and healthy pregnant women.
- Fetal sHLA-G levels in the cord blood of rheumatic and healthy pregnant women.
- Maternal and fetal HLA-G polymorphism in rheumatic and healthy pregnant women.

Autoimmune rheumatic diseases in pregnancies are associated with increased adverse obstetric outcomes. We compared maternal soluble human leucocyte antigen-G (sHLA-G) blood levels in subjects with a rheumatic disease preexisting pregnancy and unaffected controls. Third-trimester blood maternal sHLA-G concentrations were significantly higher in subjects with rheumatic diseases than in controls (mean 93.1 ng/ml [SD 42.1] vs 58.1 ng/ml [SD 96.3], p = 0.003). Cord blood sHLA-G concentrations were significantly higher in rheumatic disease than in those born to control mothers (median 41.2 ng/ml [IQR: 3.3-44.0] vs 17.9 ng/ml [IQR: 17.2-88.1], p = 0.007). A strict positive correlation (r = 0.88, p < 0.001) was found between the maternal and fetal titers of ANA autoantibodies as well as between maternal and fetal sHLAG circulating levels (r = 0.58 and r = 0.67, respectively, for controls and cases, p < 0.001). Maternal s-HLA-G blood concentrations were significantly higher in subjects with rheumatic disease DEL/DEL homozygous for a polymorphism of the 3′ untranslated regulatory region of HLA-G (HLA-G 14 bp) than in the corresponding healthy controls (mean values 141.5 ng/ml [SD: 166] vs 54.2 ng/ml [SD: 35], p = 0.009). Increasing maternal and cord blood levels of s-HLA-G concentrations among pregnant subjects with rheumatic diseases compared with controls suggest that autoimmune diseases prompt a maternal and fetal immune response that favors pregnancy immune tolerance.