Human leucocyte antigens in idiopathic nephrotic syndrome in children

Strong Association of the HLA-DR/DQ Locus with Childhood Steroid-Sensitive Nephrotic Syndrome in the Japanese Population

Background Nephrotic syndrome is the most common cause of chronic glomerular disease in children. Most of these patients develop steroid-sensitive nephrotic syndrome (SSNS), but the loci conferring susceptibility to childhood SSNS are mainly unknown.Methods We conducted a genome-wide association study (GWAS) in the Japanese population; 224 patients with childhood SSNS and 419 adult healthy controls were genotyped using the Affymetrix Japonica Array in the discovery stage. Imputation for six HLA genes (HLA-A, -C, -B, -DRB1, -DQB1, and -DPB1) was conducted on the basis of Japanese-specific references. We performed genotyping for HLA-DRB1/-DQB1 using a sequence-specific oligonucleotide-probing method on a Luminex platform. Whole-genome imputation was conducted using a phased reference panel of 2049 healthy Japanese individuals. Replication was performed in an independent Japanese sample set including 216 patients and 719 healthy controls. We genotyped candidate single-nucleotide polymorphisms using the DigiTag2 assay.Results The most significant association was detected in the HLA-DR/DQ region and replicated (rs4642516 [minor allele G], combined P_allelic=7.84×10^-23; odds ratio [OR], 0.33; 95% confidence interval [95% CI], 0.26 to 0.41; rs3134996 [minor allele A], combined P_allelic=1.72×10^-25; OR, 0.29; 95% CI, 0.23 to 0.37). HLA-DRB1*08:02 (Pc=1.82×10^-9; OR, 2.62; 95% CI, 1.94 to 3.54) and HLA-DQB1*06:04 (Pc=2.09×10^-12; OR, 0.10; 95% CI, 0.05 to 0.21) were considered primary HLA alleles associated with childhood SSNS. HLA-DRB1*08:02-DQB1*03:02 (Pc=7.01×10^-11; OR, 3.60; 95% CI, 2.46 to 5.29) was identified as the most significant genetic susceptibility factor.Conclusions The most significant association with childhood SSNS was detected in the HLA-DR/DQ region. Further HLA allele/haplotype analyses should enhance our understanding of molecular mechanisms underlying SSNS.

Idiopathic nephrotic syndrome in Polish children - its variants and associations with HLA

HLA-DR and HLA-DQ antigens were investigated in 127 Polish children with idiopathic nephrotic syndrome (INS) followed-up for the median time of 11 years (minimum 7 years). HLA typing was performed using the polymerase chain reaction sequence-specific oligonucleotide probing technique and the microlymphocytotoxicity test. Histopathologic INS categories and a response to therapy were analyzed according to particular HLA associations. The results were compared with 330 healthy individuals. In INS children, we observed an increased frequency of HLA-DR7, DR3/7, DQ2 and DQ8, whereas HLA-DR13, DR15, DQ5 and DQ6 were decreased. In minimal change nephrotic syndrome, a relationship with HLA-DR3, DR7, DR3/7 and DQ2 was found. Evolved from minimal changes, focal segmental glomerulosclerosis was associated with HLA-DR7, while primary focal segmental glomerulosclerosis with HLA-DR4 and DQ8. In steroid-dependence and secondary steroid-resistance, an increased frequency of HLA-DR3, DR7, DR3/7 and DQ2 was documented. In contrast, primary steroid-resistant nephrotic syndrome was associated with HLA-DR4 and DQ8. Steroid-dependent patients bearing HLA-DR3 achieved longer remissions after chlorambucil therapy compared with HLA-DR3-negative. In steroid-resistant focal segmental glomerulosclerosis, a reduced response to cyclosporine A was associated with HLA-DR4. Associations with HLA differentiate between pathoanatomic entities of INS and may influence a response to immunosuppressive therapy.

HLA alleles in frequently relapsing steroid-dependent and -resistant nephrotic syndrome in Egyptian children

The association between HLA class II antigens and childhood primary nephrotic syndrome has been reported in different populations. To investigate this association in Egyptian children, DRB1 alleles were typed by DNA polymerase chain reverse hybridization in 20 frequent relapsers/steroid-dependent and 14 steroid-resistant children with minimal change nephrotic syndrome (MCNS) and 121 unrelated healthy controls from the northern part of Egypt. The strength of the association was expressed as the relative risk (RR) estimated by the odds ratio. The DRBI*07011 allele frequency was significantly higher among patients than controls (78.9% vs. 16%, Pc <0.001). The etiological fraction (EF) was high at 0.75 [RR=20.1, confidence interval (CI)=6.0-66.7]. Similarly, patients with steroid-resistant MCNS had a higher frequency of the DRBI*07011 allele than controls (64.3% vs. 16.5%, P c<0.001). The EF was high at 0.57 (RR=9.6, CI 2.9-31.7). In the whole group of patients the frequency of DRBI*11 alleles was low compared with controls (11.4% vs. 32.2%, P =0.02), but was not significant when P was corrected. In conclusion, the DRBI*07011 allele confers susceptibility to a frequently relapsing and steroid-dependent or steroid-resistant course of childhood MCNS. These patterns of the disease seem to have the same immunogenetic components.

HLA class I and II in black children with hepatitis B virus-associated membranous nephropathy

BACKGROUND

The pathogenetic mechanisms by which individuals with chronic hepatitis B virus (HBV) infection develop membranous nephropathy (MN) are probably dependent on interactions between viral, host and environmental factors; some evidence suggests a genetic predisposition. HBVMN constitutes a major etiological group in black children with nephrotic syndrome. We therefore explored the HLA associations in black children with HBVMN.

METHOD

Thirty black children, age range 2 to 16 years, with biopsy-proven HBVMN, were the subjects of the study. HBV status was determined using third generation ELISA. HLA A, B and C antigens were determined using a two-stage lymphocytotoxic test. HLA DRB1* and DQB1* typing was done using sequence-specific primers. HLA class 1 and II antigen frequencies of the study subjects were compared to controls that were randomly chosen healthy blood donors from the same population.

RESULTS

HLA DQB1*0603 was increased in patients with HBVMN compared to controls (chi2 = 13.65, RR = 4.3). DRB1*07 and DQB1*02 were increased in frequency in the study subjects but failed to reach statistical significance. There was no significant difference in the frequencies of class 1 antigens in the study group compared to controls.

CONCLUSION

To our knowledge, this is the first report of HLA associations in black patients with HBVMN in whom Class 1 and 11 antigens were determined using molecular methodology. There was a high frequency of DQB1*0603 in subjects compared to controls, suggesting a possible genetic predisposition to the development of HBVMN.

Dominant T cells in idiopathic nephrotic syndrome of childhood

BACKGROUND

Because of several studies, idiopathic nephrotic syndrome (INS) of childhood is suspected to have an immunologic pathogenesis with T cells playing a major role. To investigate this hypothesis further, we studied the diversity of the CDR3 region of the T-cell receptor (TCR) beta-chain from peripheral T cells isolated from patients with INS.

METHODS

The study was performed over a three-year period to obtain longitudinal data on the repertoire of peripheral T cells. mRNA from peripheral mononuclear cells (PBMCs) of seven INS patients and two healthy controls (NHD) was prepared and analyzed for CDR3 length polymorphism of TCR beta-chain by spectratyping.

RESULTS

All INS patients presented individually skewed spectratype histograms in at least one Vbeta-family. Patients suffering from a frequent relapsing course of INS or a focal global sclerosis showed some alterations to persist in all samples isolated in the observation period (up to 3 years). In addition, sequence analyses of the beta-chain of the TCR CDR3 region confirmed clonal expansion of peripheral T cells in those patients who had displayed spectratype alterations.

CONCLUSIONS

The data give strong evidence for an direct involvement of CD8+ T cells in the complicated course of INS.

HLA-DQB1 allele associates with idiopathic nephrotic syndrome in Japanese children

HLA-DQA1 and -DQB1 genes were investigated in 30 Japanese children with idiopathic nephrotic syndrome (INS) using the polymerase chain reaction-restriction fragment length polymorphism method. Compared with control children, there was a significant increase in the HLA-DQA1*0501, DQB1*0301 and DQB1*0601 alleles, whereas the frequency of DQB1*0501 showed a significant decrease in the patients. The increase of DQA1*0501 can be explained as being a result of a linkage disequilibrium with DQB1*0301. The previous result demonstrating a positive association of DRw6 and DRw8 with INS is also assumed to be attributable to a linkage disequilibrium with DQB1*0301 and 0601. A total of 83% of patients compared with 37% of controls possessed DQB1*0301 and/or DQB1*0601 allele (P < 0.001, RR = 8.6). Only these alleles have alanine at residue 13 and tyrosine at residue 26 in the hypervariable region in the Beta 1 domain of DQB1 gene. These findings suggest that the unique amino acid residues in the DQB1 gene may contribute to disease susceptibility in Japanese children with INS.

HLA class II associations with idiopathic nephrotic syndrome in children

The occasional familial occurrence of idiopathic nephrotic syndrome (NS) points to a genetic predisposition. Reports on associations with certain HLA class II antigens support this hypothesis. In order to define the immunogenetic background of NS more precisely, HLA class II allele frequencies in 161 children with NS were studied by restriction fragment length polymorphism (RFLP) typing. The patient cohorts consisted of 87 children from Southwest-France and 74 from Southwest-Germany. The control group consisted of 118 French and 101 German unrelated individuals from the same geographical areas. HLA alleles were defined in patients with steroid-sensitive (SS) and steroid-resistant (SR) NS and in controls. RFLP typing revealed that the previously reported association between SSNS and HLA-DR7 is confined to the RFLP split 7.1 (DRB1*07) with a combined relative risk (RRcomb) of 6.2. HLA-DQB typing showed an increased frequency of the allele DQB2b (DQB1*0201) (RRcomb = 7.8). HLA-DQA typing showed an association of SSNS with DQA3 (DQA1*0201,0301,0302) (RRcomb = 4.1). The highest RR (16.5) for SSNS was found in German patients who carried the two DRB1 specificities 17.1 (DRB1*0301) and 7.1 (DRB1*07). All associations were stronger in SS patients with frequent relapses or steroid dependency than in non- or infrequent relapsers. SR patients exhibited no significant associations with HLA class II alleles.

Major histocompatibility complex class II antigens in steroid-sensitive nephrotic syndrome in Chinese children

Steroid-sensitive nephrotic syndrome (SSNS) has been postulated to have an immunopathogenic basis. To determine whether SSNS is associated with specific class II antigens of the major histocompatibility complex, we studied HLA-DR and DQ in 40 children with SSNS. HLA-DR7 was found in 40% of SSNS patients compared with only 11.23% of controls (P = 0.00025). HLA-DR9 occurred in 71.40% of patients with frequent relapses, compared with 27.37% of controls (P = 0.016). It seems likely that SSNS has an immunogenetic basis.

The polymorphism of the immunoglobulin heavy chain switch region gene in IgA nephropathy, Henoch-Schönlein nephritis and idiopathic nephrotic syndrome

It is well known genetic predisposition may play an important role in the pathogenesis of renal diseases. Recently, there has been some controversy about the possible role of the polymorphism of the immunoglobulin heavy chain switch region gene. We have studied this gene by SstI restriction fragment length polymorphisms using DNA from 41 children with IgA nephropathy, 44 with Henoch-Schönlein nephritis and 60 with idiopathic nephrotic syndrome. There was no association of specific genotype with these diseases, in contrast to previous reports. These results are probably due to the differing genetic background of Japanese and Caucasoid patients as far as the switch region is concerned; no switch region genotype constitutes a genetic risk factor for the Japanese in these diseases.

Human leukocyte antigens in childhood idiopathic nephrotic syndrome

An association of human leukocyte antigens (HLA) with idiopathic nephrotic syndrome (INS) in childhood was studied to characterize the immunogenetic background. We determined the class I antigens using the microlymphocytotoxicity test as well as class II antigens (DRB, DQB, DQA) and class III antigen (complement 4) using DNA restriction fragment length polymorphism (RFLP) in 36 children with INS. In the current study, neither the single allele in HLA class I antigen nor the single gene frequency in the class II region was significantly increased, in contrast to the results in Caucasian INS patients in whom a genetic predisposition to the HLA system, especially to HLA B8, DR3, and DR7, has been frequently reported. Also, in our data, the frequency of deletion of complement 4 gene was not different from that of the controls. These data suggest that there is a difference in immunogenetic background between Caucasian and Japanese INS patients as far as HLA is concerned.