The complex HLA-E-nonapeptide in Behçet disease

Area of Science:

• Immunogenetics
• Molecular Biology
• Rheumatology

Background:

• Behçet disease (BD) is an immune-mediated vasculitis with limited understanding of its etiology.
• Human Leukocyte Antigen (HLA) molecules, particularly HLA-B51, are associated with BD, but the underlying mechanisms are unclear.
• Natural Killer (NK) cells are implicated in BD pathogenesis, with their activity regulated by interactions with HLA class I molecules.

Purpose of the Study:

• To investigate the role of HLA-E and its nonapeptide ligands in susceptibility to Behçet disease.
• To explore the association between specific HLA-E-derived nonapeptide sequences and BD risk.
• To examine the contribution of HLA-E functional dimorphism to BD susceptibility.

Main Methods:

• Analysis of HLA-derived nonapeptide frequencies in 466 BD patients and 444 controls.
• Genotyping for an HLA-E functional dimorphism in a subgroup of patients and controls.
• Statistical analysis including odds ratios (OR) and corrected p-values (Pc) to assess significance.

Main Results:

• In HLA-B51 negative patients, the nonapeptide VMAPRTLLL was less frequent (70.4% vs. 80.0% in controls, P=0.006), suggesting a protective effect.
• The nonapeptide VMAPRTLVL was more frequent in HLA-B51 negative patients (81.6% vs. 71.4% in controls, P=0.004), indicating increased risk.
• Homozygosity for VMAPRTLLL was protective, VMAPRTLVL conferred risk, and heterozygosity was neutral; no significant HLA-E dimorphism contribution was found.

Conclusions:

• The study findings explain the association of BD with various HLA-A molecules.
• Results support the hypothesis of NK cell involvement in the etiopathology of Behçet disease.
• Polymorphism in HLA-E does not appear to significantly contribute to BD susceptibility.