Soluble HLA-G Expression Inversely Correlates With Fetal Microchimerism Levels in Peripheral Blood From Women With Scleroderma

Abstract

Women with scleroderma (SSc) maintain significantly higher quantities of persisting fetal microchimerism (FMc) from complete or incomplete pregnancies in their peripheral blood compared to healthy women. The non-classical class-I human leukocyte antigen (HLA) molecule HLA-G plays a pivotal role for the implantation and maintenance of pregnancy and has often been investigated in offspring from women with pregnancy complications. However data show that maternal HLA-G polymorphisms as well as maternal soluble HLA-G (sHLA-G) expression could influence pregnancy outcome. Here, we aimed to investigate the underlying role of maternal sHLA-G expression and HLA-G polymorphisms on the persistence of FMc. We measured sHLA-G levels by enzyme linked immunosorbent assay in plasma samples from 88 healthy women and 74 women with SSc. Male Mc was quantified by DYS14 real-time PCR in blood samples from 58 women who had previously given birth to at least one male child. Furthermore, eight HLA-G 5′URR/3′UTR polymorphisms, previously described as influencing HLA-G expression, were performed on DNA samples from 96 healthy women and 106 women with SSc. Peripheral sHLA-G was at lower concentration in plasma from SSc (76.2 ± 48.3 IU/mL) compared to healthy women (117.5 ± 60.1 IU/mL, p < 0.0001), independently of clinical subtypes, autoantibody profiles, disease duration, or treatments. Moreover, sHLA-G levels were inversely correlated to FMc quantities (Spearman correlation, p < 0.01). Finally, women with SSc had lower sHLA-G independently of the eight HLA-G 5′URR/3′UTR polymorphisms, although they were statistically more often homozygous than heterozygous for HLA-G polymorphism genotypes −716 (G/T), −201 (G/A), 14 bp (ins/del), and +3,142 (G/A) than healthy women. In conclusion, women with SSc display less sHLA-G expression independently of the eight HLA-G polymorphisms tested. This decreased production correlates with higher quantities of persisting FMc commonly observed in blood from SSc women. These results shed some lights on the contribution of the maternal HLA-G protein to long-term persistent fetal Mc and initiate new perspectives in this field.

HLA-G: An Important Mediator of Maternal-Fetal Immune-Tolerance

“…Fetal micro-chimeras are highly associated with maternal autoimmune disease and are found in patients with lower morbidity rates for cancer (154,155). In a study of women with scleroderma, compared to disease-free women, there was reduced sHLA-G expression and higher quantities of persistent fetal micro-chimeras in the circulation (156). Interestingly, high levels of fetal micro-chimeras do not lead to higher levels of sHLA-G in offspring (157).…”

Association of parental HLA-G polymorphisms with soluble HLA-G expressions and their roles on recurrent implantation failure: A systematic review and meta-analysis

“…Besides, sHLA-G levels are reported to be associated with oocyte competence (121,122), endometriosis progression (123), pregnancy-related conditions such as SGA neonates (124), GDM (125), advanced labor (126), preterm premature rupture of membranes (127), intrauterine growth retardation (IUGR) (112), and preeclampsia (113,(128)(129)(130). Moreover, maternal circulating sHLA-G levels in the second trimester were significantly lower in pregnant women with 18-trisomy fetuses (T18) and significantly higher in those with 21-trisomy fetuses (T21) compared to the normal controls (131), and it is inversely correlated with fetal microchimerism levels (132). Also, there are contrary results that the HLA-G expression is similar between samples of normal and abnormal karyotypes, and there is no association between the HLA-G polymorphisms and altered expression in reduced abortion and miscarriage groups (133).…”