Frequency of carriers of 8.1 ancestral haplotype and its fragments in two Caucasian populations.

Within the human MHC region larger stretches of conserved DNA, called conserved ancestral haplotypes exist. However, many MHC haplotypes contain only fragments of an ancestral haplotype. Little is known, however, on relative distribution of the ancestral haplotypes to their fragments. Therefore we determined the frequency of carriers of the whole ancestral haplotype 8.1 (AH8.1) and its fragments in 127 healthy Hungarian people, 101 healthy Ohioian females, and in nine Hungarian families. The HLA-DQ2, HLA-DR3(17), RAGE -429C allele, the mono-S-C4B genotype, the HSP70-2 1267G allele and the TNF -308A (TNF2) allele were used as markers of the AH8.1. Frequency of carriers of the whole AH8.1 and its fragments was similar in the both populations. 18% of the subjects carried the whole AH8.1 in at least one chromosome, while 17-20%, 36-39%, and 24-29%, respectively carried two or three constituents of the haplotype, only one constituent or none of them. Similar results were obtained in the family study. In addition, marked differences were found in the relationship of the constituents' alleles to the whole AH8.1. In both populations, 29%, 50-59%, 52-56% and 76-96%, respectively of the carriers of HSP70-2 1267G, RAGE-429C, TNF2, and mono-S carriers carried the whole 8.1 haplotype. These findings may have important implications for studies of the disease associations with different MHC ancestral haplotypes.

The HLA 8.1 ancestral haplotype is strongly linked to the C allele of -429T>C promoter polymorphism of receptor of the advanced glycation endproduct (RAGE) gene. Haplotype-independent association of the -429C allele with high hemoglobinA1C levels in diabetic patients.

Previously we reported on strong linkage disequilibrium (LD) between the mono-S-C4B-RCCX module (mono-S) and the TNF2 allele (both known constituents of the 8.1 ancestral haplotype (8.1 AH)) in two Caucasian populations. The gene for the receptor of advanced glycation endproducts (RAGE) is encoded between the RCCX module and the HLA class II genes in the central MHC region. In order to assess the relationship between the promoter polymorphisms of the RAGE gene and the 8.1 AH, we performed a family study in eight informative families affected with type 1 diabetes mellitus; haplotypes of a RAGE promoter SNP (-429T>C) with the HLA-DQ2, -DR-3(17) and TNF2 alleles, as well as the mono-S genotype were determined. A similar analysis was performed in 82 unrelated patients with type 1 diabetes mellitus, and in unrelated healthy individuals of three different Caucasian populations (Hungarians, Ohioian females, Icelandics). In the diabetic patients clinical correlations were also investigated. Out of the 32 paternal and maternal chromosome 6 from the eight families, 15 different MHC haplotypes were found. Haplotypes containing at least three of the known constituents of the 8.1 AH (HLA-DQ2, -DR17, mono-S, TNF2) were always linked to the RAGE -429C allele. The RAGE -429C allele exhibited highly significant (p<0.0001) LD coefficients to known constituents of the 8.1 AH both in healthy persons and patients with type 1 diabetes. In the group of patients with diabetes we found significantly (p=0.013) higher maximal hemoglobinA1C concentration in the carriers of the RAGE -429C allele, this trait, however was not linked to the 8.1 AH. Our present findings indicate that the RAGE -429C allele can be considered as a candidate member of the 8.1 AH. The results also reveal a spectrum of recombinant MHC haplotypes in addition to the conserved ancestral haplotypes.

Genetic basis of tobacco smoking: strong association of a specific major histocompatibility complex haplotype on chromosome 6 with smoking behavior.

The genetic basis for addiction to tobacco smoking--particularly that of the perception of olfactory stimuli that may be important in reinforcing smoking addiction--is largely unknown. A cluster of genes for olfactory receptors is in close proximity to the MHC region on chromosome 6. Polymorphisms of MHC class III genes (RCCX modules, TNFA promoter polymorphisms) were determined in 101 healthy subjects and 232 coronary artery disease (CAD) patients from Hungary with defined tobacco smoking habits. A highly significant association between ever smoking (past + current smokers) and a specific MHC haplotype was observed (odds ratios = 2.14-4.13; P-values = 0.012 to <0.001). This haplotype is characterized by the presence of C4A null alleles and a solitary short C4B gene linked to the TNF2 allele of the promoter for TNFA gene. This haplotype occurred more frequently in the ever smokers than in the never smokers [odds ratio: 4.97 (1.96-12.62); P = 0.001], and such associations were stronger in women (odds ratio = 13.6) than in men (odds ratio = 2.79). An independent study of complement C4 protein polymorphism and smoking habits in Icelandic subjects (n = 351) yielded similar and confirmative results. Considering the documented link between olfactory stimuli and smoking in females, and the presence of a cluster of odorant receptor genes close to the MHC class I region, our findings implicate a potential role of the MHC-linked olfactory receptor genes in the initiation of smoking.

Diversity in intrinsic strengths of the human complement system: serum C4 protein concentrations correlate with C4 gene size and polygenic variations, hemolytic activities, and body mass index.

Among the genes and proteins of the human immune system, complement component C4 is extraordinary in its frequent germline variation in the size and number of genes. Definitive genotypic and phenotypic analyses were performed on a central European population to determine the C4 polygenic and gene size variations and their relationships with serum C4A and C4B protein concentrations and hemolytic activities. In a study population of 128 healthy subjects, the number of C4 genes present in a diploid genome varied between two to five, and 77.4% of the C4 genes belonged to the long form that contains the endogenous retrovirus HERV-K(C4). Intriguingly, higher C4 serum protein levels and higher C4 hemolytic activities were often detected in subjects with short C4 genes than those with long genes only, suggesting a negative epistatic effect of HERV-K(C4) on the expression of C4 proteins. Also, the body mass index appeared to affect the C4 serum levels, particularly in the individuals with medium or high C4 gene dosages, a phenomenon that was dissimilar in several aspects from the established correlation between body mass index and serum C3. As expected, there were strong, positive correlations between total C4 gene dosage and serum C4 protein concentrations, and between serum C4 protein concentrations and C4 hemolytic activities. There were also good correlations between the number of long genes with serum levels of C4A, and the number of short genes with serum levels of C4B. Thus, the polygenic and gene size variations of C4A and C4B contribute to the quantitative traits of C4 with a wide range of serum protein levels and hemolytic activities, and consequently the power of the innate defense system.

Relationship between the tumor necrosis factor alpha polymorphism and the serum C-reactive protein levels in inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract, including ulcerative colitis (UC) and Crohn's disease (CD). The aim of the study was to determine the prevalence of the tumor necrosis factor alpha (TNF-alpha) promoter polymorphisms at positions -238 and -308, and to measure the serum CRP levels in CD and UC patients and in a healthy population. The TNF-alpha gene polymorphisms were determined by the PCR-RFLP method. Samples of 74 CD and 50 UC patients and 138 healthy Hungarian volunteers were examined. The G-->A substitution at position -308 (designated the TNF2 allele) was significantly less frequent among IBD patients than in the control group (P=0.0009); 15% of the CD patients and 18% of the UC patients carried the mentioned allele, which was significantly less frequent compared with the healthy population (33%, P=0.0035 and P=0.036, respectively). No difference in the G-->A substitution at position -238 was observed. We found the median CRP levels to be significantly higher in the active phase of the disease than in the inactive phase among the -308A allele carriers (P=0.002), while this difference was not significant when the CRP levels in the active and inactive phases were compared among the -308GG homozygous patients (P=0.084). The decreased frequency of the TNF2 allele (known to be associated with elevated TNF-alpha production) in IBD may determine the severity of IBD through its interaction with plasma CRP levels, and may modify the pathogenesis of this chronic inflammatory disease.

Relationship between complement components C4A and C4B diversities and two TNFA promoter polymorphisms in two healthy Caucasian populations.

The RP-C4-CYP21-TNX (RCCX) modules and the tumor necrosis factor (TNF) gene cluster are probably the most polymorphic genomic regions in the human central major histocompatibility complex (MHC). Using definitive methods for genotypic and phenotypic analyses of complement components C4A and C4B, determination of the RCCX length variants, and SSP-PCR/RFLP analyses of TNFA promoter polymorphisms at positions -308 and -238, we studied the complex relationships between the C4 and TNFA polymorphisms in two normal Caucasian populations. The patterns of the RCCX modular structures and the allelic frequency of -308A TNFA (TNF2) were similar between the Budapest (n = 125) and the Ohio (n = 80) Caucasians. However, the frequency of the -238A allele was significantly higher in the Ohio (11.3%) than in the Budapest (1.6%) study population (p < 0.0001). Marked features were found in the RCCX length variants in the TNF2 carriers and noncarriers. Strong associations were found between the C4AQ0 B1 haplotype from the monomodular short (mono-S) RCCX structure and the TNF2 allele, and between the C4A6 B1 haplotype from the bimodular long-short (LS) structure of the RCCX and the TNFA -238A allele. However, 36%-46% of the TNF2 carriers did not associate with a mono-S in both study cohorts, and 57.1% of the TNFA -238A carriers in Ohio did not associate with C4A6, which has a defective complement C5 convertase activity. The carriers of TNF2 allele had significantly lower C4A serum concentration (0.17 +/- 0.08 g/l) than noncarriers (0.23 +/- 0.09 g/l) (p < 0.001). The lowest C4A serum levels were found in TNF2 carriers with mono-S structures (0.14 +/- 0.06 g/l). In essence, our results demonstrated the heterogeneities of the TNFA promoter polymorphisms, and the linkage disequilibrium of TNFA -308A and -238A alleles with complement C4A deficiency and impaired C4A protein function, respectively.

Similar genetic features and different islet cell autoantibody pattern of latent autoimmune diabetes in adults (LADA) compared with adult-onset type 1 diabetes with rapid progression.

OBJECTIVE: To compare the clinical parameters, C-peptide levels, pattern of islet cell-specific autoantibodies, and prevalence of predisposing genotypes in subjects with latent autoimmune diabetes in adults (LADA) and those with adult-onset type 1 diabetes with rapid progression. RESEARCH DESIGN AND METHODS: We evaluated the clinical parameters, C-peptide levels, and islet cell-specific autoantibodies in 54 LADA, 57 adult-onset type 1 diabetic, and 190 type 2 diabetic patients. Islet cell autoantibodies were also compared between subgroups of newly diagnosed patients with LADA and those with newly diagnosed adult-onset and childhood-onset type 1 diabetes. The genetic study was performed in subjects with LADA and those with adult-onset type 1 diabetes in comparison with a control population. RESULTS: There were no differences in the clinical parameters between LADA and adult-onset type 1 diabetes. Patients with LADA had lower BMI (P < 0.0001), waist-to-hip ratio (0.0029), total cholesterol (P = 0.001), and triglycerides (P = 0.001); higher HDL cholesterol levels (P < 0.0001); and lower prevalence of hypertension (P = 0.0028) compared with patients with type 2 diabetes. C-peptide levels were similar at onset (P = 0.403) but decreased less rapidly in LADA than in adult-onset type 1 diabetes (P = 0.0253). Single-autoantibody positivity was more often seen in LADA than in type 1 diabetes (P = 0.0001). The prevalence of predisposing HLA-DQB1*0302, -DR4, -DR3, and -DR3/DR4 genotypes and the DR4-DQB1*0302 haplotype were increased in both LADA and adult-onset type 1 diabetic subjects compared with the control population. There were no differences in the frequencies of these risk alleles and haplotypes between the two patient groups. CONCLUSIONS: Subjects with LADA had clinical characteristics similar to those with adult-onset type 1 diabetes with rapid progression. C-peptide levels did not differ at onset but decreased less rapidly in LADA. Patients with LADA rather had single islet cell-specific autoantibody positivity. The prevalence of HLA-DQB1*0302, -DR4, -DR3, and -DR3/DR4 risk alleles and the DR4-DQB1*0302 high-risk haplotype did not differ in the two forms of autoimmune diabetes.

Antibodies against the human heat shock protein hsp70 in patients with severe coronary artery disease.

Heat shock proteins (hsps) play complex role in the function of the immune system, they can activate both humoral and cellular immune response, as well the complement system. Although autoimmunity to hsp70 was implicated in certain autoimmune diseases and other conditions, the exact role of anti-hsp70 antibodies is not known. It was demonstrated by our previous work and other's findings that antibodies against the 60 kDa hsps are strongly associated with coronary atherosclerosis and carotis disease. It is also known that there is increased hsp70 expression at different sites of atherosclerosis. Therefore our aim was to study whether level of anti-hsp70 antibodies correlate with the presence of severe coronary artery disease (CAD). We measured and compared anti-hsp70 IgG antibody levels in CAD patients (n = 99) and healthy subjects (n = 99) with ELISA. The frequency of these antibodies was high in both groups and there was no significant difference in the median level of anti-hsp70 antibodies between patients with severe CAD and controls (653 (400-1141) vs. 630 (326-1152) AU/mL, P = 0.337). Adjustment for age, sex, BMI and lipid parameters did not change this result. Furthermore we did not find a correlation between anti-hsp70 antibody levels and certain risk factors of CAD (age, lipid parameters, body mass index, C-reactive protein, gender, smoking, diabetes and anti-hsp60 antibodies). By contrast, in accordance with our previous findings, anti-hsp60 and anti-hsp65 antibody levels were significantly higher in CAD patients, compared to this control group (p < 0.0001 for both variables). We did not find any correlation between the levels of anti-hsp70 and anti-hsp60 or anti-hsp65 antibodies either in the patients or the controls. The exact role of hsp70 in atherosclerosis is controversial, but we suggest that humoral immunity against human hsp70 does not contribute to coronary atherosclerosis in contrast to antibodies against 60kDa hsps.

Differences in the genetic background of latent autoimmune diabetes in adults (LADA) and type 1 diabetes mellitus.

OBJECTIVES: According to the recent classification of diabetes mellitus the Latent Autoimmune Diabetes in Adults (LADA) belongs to the group of type 1 autoimmune diabetes, as a slowly progressive form. Our aim was to determine (i) the prevalence of HLA-DRB1 and DQB1 genotypes, and (ii) to determine the tumor necrosis factor (TNF) alpha promoter polymorphism at position -308 (the G-->A substitution, designated the TNF2 allele) in patients with type 1 diabetes and with LADA compared with the healthy population. METHODS: The major histocompatibility complex (MHC) II genotypes and the TNF alpha promoter polymorphism were determined by PCR method. We examined 69 type 1 diabetic and 42 LADA patients. As control samples of 336 cadaver kidney donors and 138 volunteers were used. RESULTS: Both type 1 diabetes mellitus and LADA were positively associated with the DRB1*04-DQB1*0302 (DR4/DQ8) haplotype (P=0.00001, and P=0.0005, respectively), and negatively associated with the DRB1*11-DQB1*0301 (DR11/DQ7) haplotype (P=0.00006, and P=0.007, respectively) compared with control population. There were differences between the two disease entities in the frequency of the DRB1*03-DQB1*02 (DR3/DQ2) haplotype (P=0.00008 vs. P=0.177) compared with control group. The presence of the TNF2 allele was significantly lower in LADA than type I diabetes (P=0.022) or control group (P=0.017). CONCLUSION: Our findings indicate that there are marked differences in the genetic background of type 1 diabetes and LADA. The low presence of TNF2 allele (known to be associated with high amount of TNF alpha production) in LADA could be one of the factors responsible for the relatively slow progression.