HLA-G gene expression influenced at allelic level in association with end stage renal disease and acute allograft rejection.

BACKGROUND

Human leukocyte antigen (HLA)-G is a non-classical major-histocompatibility complex class-I molecule associated with immunosuppressive function. We have evaluated the impact of HLA-G allele associated with untranslated-region (UTR)-haplotype in end stage renal disease (ESRD) and acute allograft rejection (AR) cases. The mRNA levels of different HLA-G isoforms were evaluated in ESRD and AR cases. Subsequently, the total HLA-G mRNA levels and protein concentration were evaluated against its UTR-haplotype among ESRD and AR cases.

METHODOLOGY

Sequence based typing of the promoter region was carried-out to evaluate the impact of HLA-G haplotype in 350 ESRD cases and 300 controls. HLA-G gene expression was evaluated at the transcriptional level using semi-quantitative and quantitative PCR, whereas protein concentration was determined by ELISA among both cases and control.

RESULTS

Increased risk was observed for G01:01:01:03, G01:01:02, G01:06 and G01:05:N haplotypes while G01:01:01:01 and G01:04:01 haplotypes showed a protective effect in ESRD and AR cases. Higher level of soluble HLA-G isoforms (G5 and G6) was observed among ESRD cases. Reduced levels of soluble isoform (G5) and increased levels of membrane bound (G1 and G3) isoforms were found among AR cases, revealing risk association. Decreased HLA-G expression was observed at both mRNA and protein level for G01:01:01:03 and G01:05:N haplotypes in ESRD and AR cases.

CONCLUSIONS

These results suggest that the variation in the expression profile of membrane bound and soluble isoforms may modulate the risk for ESRD and AR. UTR-haplotypes appear to be involved in different HLA-G expression patterns at transcriptional and translational levels.