Gametic association of HSP70-1 promoter region alleles and their inclusion in extended HLA haplotypes

Genetic variations of HSPA1A, the heat shock protein levels, and risk of atherosclerosis

HSPA1A is a serum and intracellular heat shock protein with antiapoptotic and antithrombotic properties. The present study examines the hypothesis that a decrease in the synthesis of this protein in relation to certain polymorphisms of the regulatory region of the HSPA1A gene can define a vascular disease risk phenotype. A randomly selected population was studied and stratified into groups according to the degree of vascular risk. After applying the Task Force Chart to 452 people, the subjects were divided into three groups: group 0 (no vascular risk factor or risk < 5%), n = 239; group 1 (moderate (10-20%) risk, with no clinical cardiovascular disease), n = 161; and group 2 (overt atherosclerosis), n = 52. Serum and intragranulocytic HSPA1A was quantified, and direct Sanger sequencing was performed in all subjects. An analysis was made of the association of two single nucleotide polymorphisms (db rs1008438 -110A/C and db rs1043618 +190 G/C) with circulating and intragranulocytic HSPA1A and the risk of atherosclerosis. The atherosclerotic subjects showed significantly lower circulating HSPA1A levels than the other groups, regardless of the genotype. The patients with CC genotype for both polymorphisms showed significantly lower intragranulocytic HSPA1A levels than the other genotypes. Serum HSPA1A concentrations could be proposed as a biomarker of cardiovascular disease. CC homozygosis for polymorphisms db rs1008438 and db rs1043618 is associated with a decrease in the intragranulocytic production of HSPA1A. Given the antiatherogenic functions of intracellular HSPA1A, the -110A and +190 G alleles could constitute potential genetic biomarkers of a less severe clinical phenotype for the risk of developing atherosclerosis.

D6S273 microsatellite polymorphism and susceptibility to rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic articular inflammatory disease associated with HLA-DR genes that share a five amino acid sequence motif, QKRAA or QRRAA, from position 70 to 74 in the third hypervariable region of the DRB1 molecule. Since these associations between DRB1 genes and susceptibility to RA are incomplete, we examined the role of a CA repeat polymorphic microsatellite marker, D6S273, located between HSP70 and Bat2 genes in the class III region of MHC, in susceptibility to RA. Ninety-seven adult patients with seropositive RA and 100 normal healthy subjects were studied. Two D6S273 alleles (132 and 138) showed significant differences in their prevalence in RA patients as compared to normal controls; allele 132 was significantly higher in total patients and in DRB1 QKRAA/QRRAA epitope-positive patients, and allele 138 was significantly higher in QKRAA/QRRAA-negative patients. Analysis of data suggested that the association of D6S273 132 allele with RA was secondary to that of DRB1 genes. On the other hand, D6S273 138 allele showed primary association with RA susceptibility in QKRAA/QRRAA epitope-negative patients. The D6S273 138 allele thus provides an additional risk in RA susceptibility. The results in the present study therefore suggest that two regions in MHC, DRB1 and D6S273, contribute to susceptibility to RA.

A vigorous virus-specific CD4+ T cell response may contribute to the association of HLA-DR13 with viral clearance in hepatitis B

A strong virus-specific CD4+ and CD8+ T lymphocyte response to hepatitis B virus (HBV) has been associated with viral clearance, but little is known about factors determining the individual's ability to mount such a T cell response. Recently a strong association between the HLA class II allele DR13 and a self-limited course of HBV infection has been described. In the present study of 33 patients with acute hepatitis B we show that individuals carrying HLA-DR13 mount a more vigorous CD4+ T cell response to HBV core (5706 ct/min (25th/75th percentile 3239 ct/min; 10,552 ct/min)) than patients without HLA-DR 13 (1365 ct/min (490 ct/min; 5334 ct/min); P = 0.006). However, peptide epitopes aa 50-69, aa 61-85, and aa 81-105 were recognized most frequently by both patient groups. Moreover, among 14 HBV core-specific CD4+ T cell clones from two patients with HLA-DR13, only one T cell clone was HLA-DR13-restricted. Our data suggest that the beneficial effect of the HLA-DR13 alleles on the outcome of HBV infection could be explained by a more vigorous HBV core-specific CD4+ T cell response, which may either be due to more proficient antigen presentation by the HLA-DR13 molecules themselves or a linked polymorphism in a neighbouring immunoregulatory gene.

Analysis of HLA-A, C, B, DR and DQ loci in an Italian sample of possible Celtic origin

Trino Vercellese, a village of Piedmont (Italy), was selected with the aim at reconstructing the genetic history of a putative Celtic sample known to be settled in Italy with the name of Rigomagus since pre-roman times. The HLA-A, Cw, B, DR and DQ antigens of 101 unrelated individuals have been typed. The antigens characterizing this sample for their higher frequency are shown to be A3, A11, A32, B35, B39, Bw52, Cw4, DRw11, DRw13, DQw7. Gene frequencies are estimated by maximum likelihood and Hardy-Weinberg equilibrium was tested with no deviant genetic locus. Two-locus haplotype frequencies were also estimated and those with significant associations tabulated. "Extended" haplotypes were reconstructed: the three most frequent haplotypes (covering a total frequency of 11.5%) share the same Cw, B, DR and DQ alleles. Comparisons with other Italian and European samples are indicated to challenge archeological evidence of a pre-roman genetic stratification of the people living in our old Rigomagus.

HLA supratypes in an Italian population

A supratype analysis of a North Italian population was performed, using 16 polymorphisms in the HLA region spanning the HLA-A-DP segment. Fourteen supratypes were identified, mostly corresponding to those found in other Caucasoid populations. The degree of their conservation both within the B-DR/DQ region and in the regions telomeric and centromeric from HLA-A and DP was evaluated and linkage disequilibria among several DR and DP alleles were identified. Notably, the degree of association with DP increased when the DR marker was part of a conserved B-DR/DQ supratype. These data are relevant to the definition of the genetic structure of the population and to the prediction of probabilities of histocompatibility matching between unrelated individuals.