Protective and susceptible HLA polymorphisms in IgA nephropathy patients with end-stage renal failure

Homozygosity in any HLA locus is a risk factor for specific antibody production: the taboo concept 2.0

Objective

In a cooperative study of the University Hospital Leipzig, University of Leipzig, and the Charité Berlin on kidney transplant patients, we analysed the occurrence of HLA-specific antibodies with respect to the HLA setup of the patients. We aimed at the definition of specific HLA antigens towards which the patients produced these antibodies.

Methods

Patients were typed for the relevant HLA determinants using mainly the next-generation technology. Antibody screening was performed by the state-of-the-art multiplex-based technology using microspheres coupled with the respective HLA alleles of HLA class I and II determinants.

Results

Patients homozygous for HLA-A*02, HLA-A*03, HLA-A*24, HLA-B*07, HLA-B*18, HLA-B*35, HLA-B*44, HLA-C*03, HLA-C*04, and HLA-C*07 in the class I group and HLA-DRB1*01, HLA-DRB1*03, HLA-DRB1*07, HLA-DRB1*15, HLA-DQA1*01, HLA-DQA1*05, HLA-DQB1*02, HLA-DQB1*03(7), HLA-DQB1*06, HLA-DPA1*01, and HLA-DPB1*04 in the class II group were found to have a significant higher antibody production compared to the heterozygous ones. In general, all HLA determinants are affected. Remarkably, HLA-A*24 homozygous patients can produce antibodies towards all HLA-A determinants, while HLA-B*18 homozygous ones make antibodies towards all HLA-B and selected HLA-A and C antigens, and are associated with an elevation of HLA-DRB1, parts of DQB1 and DPB1 alleles. Homozygosity for the HLA class II HLA-DRB1*01, and HLA-DRB1*15 seems to increase the risk for antibody responses against most of the HLA class I antigens (HLA-A, HLA-B, and HLA-C) in contrast to HLA-DQB1*03(7) where a lower risk towards few HLA-A and HLA-B alleles is found. The widely observed differential antibody response is therefore to be accounted to the patient's HLA type.

Conclusion

Homozygous patients are at risk of producing HLA-specific antibodies hampering the outcome of transplantation. Including this information on the allocation procedure might reduce antibody-mediated immune reactivity and prevent graft loss in a patient at risk, increasing the life span of the transplanted organ.

Risk factors and outcomes of IgA nephropathy recurrence after kidney transplantation: a systematic review and meta-analysis

Background

IgA nephropathy may recur in patients receiving kidney transplantation due to IgA nephropathy induced renal failure. The risk factors for recurrence are still at issue. The aim of this study was to conduct a systematic review and meta-analysis to assess risk factors and outcomes for IgA nephropathy recurrence.

Methods

We used PubMed, EMBASE, Cochrane Library, Web of Science, Scopus, CNKI, WanFang, VIP and CBM to search for relevant studies published in English and Chinese. Cohort or case-control studies reporting risk factors or outcomes for IgA nephropathy recurrence were included.

Results

Fifty-eight studies were included. Compare to no recurrence group, those with IgAN recurrence had younger age (mean difference [MD]=-4.27 years; risk ratio [RR]=0.96), younger donor age (MD=-2.19 years), shorter time from IgA nephropathy diagnosis to end stage renal disease (MD=-1.84 years; RR=0.94), shorter time on dialysis (MD=-3.14 months), lower human leukocyte-antigen (HLA) mismatches (MD=-0.11) and HLA-DR mismatches (MD=-0.13). HLA-B46 antigen (RR=0.39), anti-IL-2-R antibodies induction (RR=0.68), mycophenolate mofetil (RR=0.69), and pretransplant tonsillectomy (RR=0.43) were associated with less IgAN recurrence. Of note, male recipient gender (RR=1.17), related donor (RR=1.53), retransplantation (RR=1.43), hemodialysis (RR=1.68), no induction therapy (RR=1.73), mTOR inhibitor (RR=1.51), angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers (RR=1.63) were risk factors for IgAN recurrence. Recurrence increased the risk of graft loss (RR=2.19).

Conclusions

This study summarized the risk factors for recurrence of IgA nephropathy after kidney transplantation. Well-designed prospective studies are warranted for validation.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=377480, identifier CRD42022377480.

The role of HLA antigens in recurrent primary focal segmental glomerulosclerosis

Primary focal segmental glomerulosclerosis (FSGS), typically characterized by diffuse podocyte foot process effacement and nephrotic syndrome (diffuse podocytopathy), is generally attributed to a circulating permeability factor. Primary FSGS can recur after transplantation where it manifests as diffuse foot process effacement in the early stages, with subsequent evolution of segmental sclerotic lesions. Previous published literature has been limited by the lack of stringent selection criteria to define primary FSGS. Although immunogenetic factors play an important role in many glomerular diseases, their role in recurrent primary FSGS post-transplantation has not been systematically investigated. To address this, we retrospectively studied a multicenter cohort of 74 kidney allograft recipients with end stage kidney disease due to primary FSGS, confirmed by clinical and histologic parameters. After adjusting for race/ethnicity, there was a numeric higher frequency of HLA-A30 antigen in primary FSGS (19%) compared to each of 22,490 healthy controls (7%, adjusted OR=2.0, P=0.04) and 296 deceased kidney donors (10%, OR=2.1, P=0.03). Within the group of transplant patients with end stage kidney disease due to primary FSGS, donor HLA-A30 was associated with recurrent disease (OR=9.1, P=0.02). Multivariable time-to-event analyses revealed that recipients who self-identified as Black people had lower risk of recurrent disease, probably reflecting enrichment of these recipients with APOL1 high-risk genotypes. These findings suggest a role for recipient and donor immunogenetic makeup in recurrent primary FSGS post-transplantation. Further larger studies in well-defined cohorts of primary FSGS that include high-resolution HLA typing and genome-wide association are necessary to refine these hereditary signals.

Association of end-stage renal disease with HLA phenotypes and panel reactive antibodies in patients awaiting renal transplantation in Hunan Province

Objectives

To explore the immune‐related genetic susceptibility of human leukocyte antigen (HLA) alleles and their correlation with panel reactive antibody (PRA) generation during end‐stage renal disease (ESRD) progression.

Materials and methods

Data of the expression patterns of HLA‐A, ‐B, and ‐DR alleles and PRAs of 347 ESRD patients awaiting renal transplantation in Hunan Province from 2015 to 2019 were retrospectively studied. The polymerase chain reaction with sequence‐specific primers was used for HLA genotyping and the enzyme‐linked immunosorbent assay for PRA detection. SPSS 21.0 software was used for all allele frequency and statistical analyses.

Results

Thirteen HLA‐A, 25 HLA‐B, and 13 HLA‐DR alleles were expressed. The allele frequencies of HLA‐A2, ‐B48, ‐B52, and ‐B55 were significantly higher in the case group than in the control group (p < 0.05), whereas that of HLA‐B60 was significantly higher in the control group (p < 0.05). The frequency of HLA alleles in the PRA‐positive group was significantly higher in females than in males (p < 0.05). The allele frequencies of HLA‐A2, ‐B38, and ‐B46 were significantly higher in the PRA‐positive group than in the PRA‐negative one (p < 0.05), whereas that of HLA‐60 was significantly higher in the PRA‐negative group (p < 0.05).

Conclusion

HLA‐A2, ‐B48, ‐B52, and ‐B55 may be the ESRD susceptibility alleles in Han Chinese patients in Hunan Province, whereas HLA‐B60 may be the protective allele. Patients carrying HLA‐A2, ‐B38, and ‐B46 are more likely to develop PRA positivity, whereas the opposite is true for those with HLA‐B60.

Clinical Predictors and Prognosis of Recurrent IgA Nephropathy in the Kidney Allograft

Introduction

Although IgA nephropathy (IgAN) is the most common recurrent glomerulonephritis encountered in the kidney allograft, the clinical and immunogenetic characteristics remain poorly understood. We sought to study determinants and prognosis of recurrent IgAN with special focus on HLA antigens.

Materials and Methods

Between 2005 and 2019, we identified 282 transplanted patients with failure secondary to IgAN from two North American and one European Medical Centers, including 80 with recurrent IgAN and 202 without recurrence. Prevalence of HLA antigens was compared to external healthy controls of European ancestry (n=15,740). Graft survival was assessed by Kaplan-Meier method and log rank test. Cox proportional hazards were used for multivariable analyses.

Results

Compared to external controls of European ancestry, kidney transplant recipients of European ancestry with kidney failure secondary to IgAN had higher frequency of HLA-DQ5 (42% vs. 30%, OR=1.68, P=0.002) and lower frequency of HLA-DR15 (15% vs. 28%, OR=0.46, P<0.001) and HLA-DQ6 (32% vs. 45%, OR=0.59, P=0.003); however, the frequency of these HLA antigens were similar in recurrent versus non-recurring IgAN. Younger recipient age at transplantation was an independent predictor of recurrence. HLA-matching was an independent predictor for recurrent IgAN only in recipients of living-related but not deceased or living unrelated transplants. Recurrent IgAN was an independent predictor of allograft failure, along with acute rejection. In patients with recurrent IgAN, serum creatinine at biopsy, degree of proteinuria, and concurrent acute rejection were associated with inferior allograft survival.

Discussion/ Conclusion

Recurrent IgAN negatively affects allograft survival. Younger recipient age at transplantation is an independent predictor of recurrent IgAN, while the presence of HLA antigens associated with IgAN in the native kidney and HLA-matching in recipients of deceased or living unrelated transplants are not.

Systematic review of associations between HLA and renal function

Introduction

Kidney dysfunction is a highly significant disease, both in the United Kingdom and globally. Many previous studies have reported associations between human leukocyte antigens (HLA) and renal function; this systematic review attempts to identify, summarize and appraise all published studies of these associations.

Methods

A literature search was performed using Medline, Embase and Cochrane Central Register of Controlled Trials to identify papers whose keywords included each of the following concepts: HLA, renal failure and genetic association. A total of 245 papers were identified and assessed for eligibility; 35 of these were included in the final study.

Results

A total of 95 HLA types and 14 three‐locus haplotypes were reported to be associated with either increased or decreased renal function. A number of these findings were replicated by independent studies that reported 16 types were protective against renal dysfunction and 15 types were associated with reduced renal function. A total of 20 HLA types were associated with both increased risk of renal disease and decreased risk by independent studies.

Discussion

There is very little consensus on which HLA types have a protective or deleterious effect on renal function. Ethnicity may play a role, with HLA types possibly having different effects among different populations, and it is possible that the different primary diseases that lead to ESRD may have different HLA associations. Some of the studies may contain type I and type II errors caused by insufficient sample sizes, cohort selection and statistical methods. Although we have compiled a comprehensive list of published associations between renal function and HLA, in many cases, it is unclear which associations are reliable. Further studies are required to confirm or refute these findings.

Relevance of HLA gene polymorphisms in Romanian patients with chronic renal insufficiency undergoing renal transplantation

BACKGROUND

Chronic renal insufficiency (CRI) is a global public health problem with a high incidence in the Romanian population. In this study, we aimed to investigate genomic HLA polymorphisms in Romanian patients with CRI waiting for kidney transplantation. To determine the existence of a potential strong link between certain HLA polymorphisms and CRI, we also looked at HLA specificity combinations within the same locus or even different loci, referring to randomly inherited allelic combinations rather than potential haplotypes.

METHODS

A total of 2199 patients with CRI on the kidney transplantation waiting list were included. A total of 2786 healthy individuals were included as controls. Both patients and controls were assessed for both HLA I and class II genes. HLA genes were typed using the low-resolution method polymerase chain reaction sequence-specific primer.

RESULTS

Certain class I and class II HLA allele groups, genotypes and haplotypes were significantly more frequent in patients with CRI than in the control individuals (eg B* 40 (p ≤ .001, pc ≤ .001), C* 12 (p ≤ .001, pc ≤ .001), DRB1*14 (p = .0022, pc = .04), C*12,- (p < .001, pc < .001), A*01-C*15 (p = .0003, pc = .03) and A*02-C*12 (p = .0005, pc = .0486)).

CONCLUSIONS

HLA gene polymorphisms could be clinically relevant CRI-associated genetic profiles in Romanian patients with CRI.

Associations between human leukocyte antigens and renal function

Human leukocyte antigens (HLA) have been associated with renal function, but previous studies report contradictory findings with little consensus on the exact nature or impact of this observation. This study included 401,307 white British subjects aged 39–73 when they were recruited by UK Biobank. Subjects’ HLA types were imputed using HLA*IMP:02 software. Regression analysis was used to compare 362 imputed HLA types with estimated glomerular filtration rate (eGFR) as a primary outcome and clinical indications as secondary outcome measures. 22 imputed HLA types were associated with increased eGFR (and therefore increased renal function). Decreased eGFR (decreased renal function) was associated with 11 imputed HLA types, seven of which were also associated with increased risk of end-stage renal disease and/or chronic kidney disease. Many of these HLA types are commonly inherited together in established haplotypes, for example: HLA-A*01:01, B*08:01, C*07:01, DRB1*03:01, DQB1*02:01. This haplotype has a population frequency of 9.5% in England and each allele was associated with decreased renal function. 33 imputed HLA types were associated with kidney function in white British subjects. Linkage disequilibrium in HLA heritance suggests that this is not random and particularly affects carriers of established haplotypes. This could have important applications for the diagnosis and treatment of renal disease and global population health.

Human leukocyte antigen associations with renal function among ethnic minorities in the United Kingdom

Human leukocyte antigens (HLA) have been associated with renal function, but previous studies report contradictory findings. There has been a lack of research into how HLA affects renal function in Black, Asian and Minority Ethnic (BAME) people in the UK, despite BAME people being disproportionately affected by renal dysfunction. This study included >27 000 UK Biobank subjects of six ethnicities (>12 100 Irish, >5400 Indian, >4000 Black Caribbean, >3000 Black African, >1600 Pakistani, and >1400 Chinese) aged 39 to 73. Subjects' high-resolution HLA genotypes were imputed using HLA*IMP:02 software. Regression analysis was used to compare 108 imputed HLA alleles with two measures of estimated glomerular filtration rate (eGFR): one based on serum creatinine; one based on serum cystatin. Secondary analysis compared CKD stage 2 subjects to healthy controls. Nine imputed HLA alleles were associated with eGFR (adjusted P < .05). Six associations were based on creatinine in Black African subjects: HLA-B*53:01 (beta = -2.628, adjusted P = 4.69 × 10^-4 ); C*04:01 (beta = -1.667, adjusted P = .0269); DPA1*02:01 (beta = -1.569, adjusted P = .0182); and DPA1*02:02 (beta = -1.716, adjusted P = .0251) were linked to decreased renal function, while DRB1*03:01 (beta = 3.200, adjusted P = 3.99 × 10^-3 ) and DPA1*01:03 (beta = 2.276, adjusted P = 2.31 × 10^-5 ) were linked to increased renal function. Two of these (HLA-B*53:01 and C*04:01) are commonly inherited together. In Irish subjects, HLA-DRB1*04:01 (beta = 1.075, adjusted P = .0138) was linked to increased eGFR (based on cystatin); in Indian subjects, HLA-DRB1*03:01 (beta = -1.72, adjusted P = 4.78 × 10^-3 ) and DQB1*02:01 (beta = -1.755, adjusted P = 2.26 × 10^-3 )were associated with decreased eGFR (based on cystatin). No associations were found in the other three ethnic groups. Nine HLA alleles appear to be associated with kidney function in BAME people in the UK. This could have applications for the diagnosis and treatment of renal disease and could help reduce health inequalities in the UK.

Impact of HLA polymorphisms among cadaveric donors on kidney graft allocation

This study provides data on HLA-A, -B, and -DRB1 frequencies among 861 end-stage renal disease (ESRD) patients from Croatia and estimates the benefit of the kidney exchange program by comparing HLA distribution and assessing HLA mismatches (MMs) within a group of ESRD patients who received kidney grafts from 707 cadaveric donors (422 from Croatia and 285 from Eurotransplant). Patients positive for HLA-B*07, -B*08, or -B*44 genes more often received a kidney from ET donors, while HLA-DRB1*11 and -DRB1*16 positive patients more frequently received a kidney from CRO donors. ABDR MM 000 was more frequently present in the case of transplantation from ET donors, while MM 222 was significantly more frequent when the donor was from Croatia. Sensitized patients received kidney more frequently from ET donors (P < .0001). A large pool of organ donors with different HLA gene distributions allows for a higher probability of transplantation from HLA highly matched donor.

Clinical Role of Human Leukocyte Antigen in Health and Disease

Most of the genes in the major histocompatibility complex (MHC) region express high polymorphism that is fundamental for their function. The most important function of human leukocyte antigen (HLA) molecule is in the induction, regulation of immune responses and the selection of the T cell repertoire. A clinician's attention is normally drawn to a system only when it malfunctions. The HLA system is no exception in this regard, but in contrast to other systems, it also arouses interest when it functions well - too well, in fact. Population studies carried out over the last several decades have identified a long list of human diseases that are significantly more common among individuals that carry particular HLA alleles including inflammatory, autoimmune and malignant disorders. HLA-disease association is the name of this phenomenon, and the mechanism underlying is still a subject of hot debate. Social behaviours are affected by HLA genes and preference for HLA disparate mates may provide 'good genes' for an individual's offspring. Also, certain HLA genes may be associated with shorter life and others with longer lifespan, but the effects depend both on the genetic background and on the environmental conditions. The following is a general overview of the important functional aspects of HLA in health and diseases.

Association between human leucocyte antigen subtypes and risk of end stage renal disease in Taiwanese: a retrospective study

Background

End stage renal disease (ESRD) is prevalent in Taiwan. Human leukocyte antigens (HLA) have been found to be associated with the pathogenesis of autoimmune diseases, allergies and inflammatory bowel diseases, and there are emerging evidences of correlations between HLA genotypes and renal diseases such as diabetic nephropathy, IgA nephropathy, and glomerulonephritis. The aim of this study is to investigate detailed HLA subtypes in a case-control study of Taiwanese individuals.

Methods

The polymorphisms of HLA class I and II antigens in ESRD patients and a healthy control group were retrospectively analyzed. The information of 141 ESRD patients was obtained from the medical record of the Keelung branch of Chang Gung Memorial Hospital and was compared to the HLA type of a control group comprized of 190 healthy unrelated Taiwanese from one of our previous studies. In order to standardize the HLA designation of prior low-resolution typings with the more advanced DNA based typings, all HLA-A, −B and -DR were analyzed using a low resolution serologic equivalent.

Results

The current work suggests that HLA-DR3 (odds ratio = 1.91, 95 % CI = 1.098–3.324, P = 0.024, Pc = 0.312) and HLA-DR11 (odds ratio = 2.06, 95 % CI = 1.133–3.761, P = 0.021, Pc = 0.273) may represent susceptibility risk factors for the development of ESRD in Taiwanese individuals. On the other hand, HLA-DR8 (odds ratio = 0.47, 95 % CI = 0.236–0.920, p = 0.027. Pc = 0.351) may be a protective factor. HLA-A and -B antigens did not show any contribution of progression to ESRD. However, we note that the significance of all these findings is lost when the results are corrected for multiple comparisons according to Bonferroni. Further investigation with a larger group of patients and control is needed to resolve this issue.

Conclusions

HLA typing might be a useful clinical method for screening patients with high risk of progression to ESRD.

Association between Human Leukocyte Antigens (HLA-A, -B, and -DR) and end-stage renal disease in Kuwaiti patients awaiting transplantation

The number of patients with end stage renal disease (ESRD) is increasing considerably worldwide. Human Leukocyte Antigens (HLAs) are relevant for the expression of many immunological diseases and contribute to the development of different nephropathies. Therefore, we aimed from the present work to investigate the possible association between the frequency of HLA-A, -B, and -DR antigens and ESRD in Kuwaiti patients awaiting renal transplant. HLA-A, -B, and -DR typing was performed by complement-dependent cytotoxicity (CDC) method for 334 patients with ESRD awaiting renal transplantation and 191 healthy controls. The frequency of HLA-B8 antigen was significantly higher in ESRD patients (OR = 2.62, p = 0.001, pc = 0.038), and the frequency of HLA-A28, HLA-DR11 antigens was significantly higher in healthy controls (OR 0.42, p = 0.0001; pc = 0.0021, and OR = 0.44, p = 0.0007, pc = 0.01 respectively). While the HLA-B8 antigen may be a susceptibility risk factor for development of ESRD, the HLA-A28, and HLA-DR11 antigens may be protective against development of ESRD in Kuwaiti population.

HLA polymorphism and susceptibility to end-stage renal disease in Cantonese patients awaiting kidney transplantation

Background

End-Stage Renal Disease (ESRD) is a worldwide public health problem. Currently, many genome-wide association studies have suggested a potential association between human leukocyte antigen (HLA) and ESRD by uncovering a causal relationship between HLA and glomerulonephritis. However, previous studies, which investigated the HLA polymorphism and its association with ESRD, were performed with the modest data sets and thus might be limited. On the other hand, few researches were conducted to tackle the Chinese population with ESRD. Therefore, this study aims to detect the susceptibilities of HLA polymorphism to ESRD within the Cantonese community, a representative southern population of China.

Methods

From the same region, 4541 ESRD patients who were waiting for kidney transplantation and 3744 healthy volunteer bone marrow donors (controls) were randomly chosen for this study. Polymerase chain reaction-sequence specific primer method was used to analyze the HLA polymorphisms (including HLA-A, HLA-B and HLA-DRB1 loci) in both ESRD patients and controls. The frequencies of alleles at these loci and haplotypes were compared between ESRD patients and controls.

Results

A total of 88 distinct HLA alleles and 1361 HLA A-B-DRB1 haplotypes were detected. The frequencies of five alleles, HLA-A*24, HLA-B*55, HLA-B*54, HLA-B*40(60), HLA-DRB1*04, and one haplotype (HLA-A*11-B*27-DRB1*04) in ESRD patients are significantly higher than those in the controls, respectively.

Conclusions

Five HLA alleles and one haplotype at the HLA-A, HLA-B and HLA-DRB1 loci appear to be associated with ESRD within the Cantonese population.

Genetic evidence for involvement of adaptive immunity in the development of IgA nephropathy: MHC class II alleles are protective in a Caucasian population

There is evidence suggesting that IgA nephropathy (IgAN) is an immunological disease. The role of HLA class II DR beta 1 (DRB1) has previously not been well studied. The aim of our study was to investigate the association of HLA-DRB1 variants with IgAN in a Swedish Caucasian cohort. Our study consisted of 213 patients with biopsy proven IgAN, all of self-reported Caucasian ancestry. As a control cohort, 1569 healthy subjects from the same population in Sweden were included. HLA-DRB1 low-resolution genotyping was performed and odds ratios were calculated to assess the risk. In an allelic model the HLA-DRB1(*)03 and (*)10, demonstrated association for IgAN after correction for multiple comparison, with subsequent OR=0.54 (95% CI 0.37-0.78) and 3.44 (95% CI 1.67-7.07). When the influence of risk allelic groups was adjusted for protective allelic groups and vice versa, only a protective effect of HLA-DRB1(*)03 remained significant. In conclusion, the variants of HLA-DRB1 were associated with IgAN of which the HLA-DRB1(*)03 revealed a strong protective effect for IgAN. Our data replicates finding from other Caucasian populations and suggest that involvement of adaptive immunity may be of importance in the development of the disease.

The genetic variants at the HLA-DRB1 gene are associated with primary IgA nephropathy in Han Chinese

Background

Immunoglobulin A nephropathy (IgAN), an immune-complex-mediated glomerulonephritis defined immunohistologically by the presence of glomerular IgA deposits, is the most common primary glomerular disease worldwide and a significant cause of end-stage renal disease. Familial clustering of patients with IgAN suggests a genetic predisposition.

Methods

In this study, 192 patients with IgAN and 192 normal controls in the Sichuan cohort and 935 patients with IgAN and 2,103 normal controls in the Beijing cohort were investigated. HLA-DRB1*01–DRB1*10 specificities were genotyped by the PCR–SSP technique in both cohorts. Based on the HLA-DRB1*04-positive results, the subtypes of HLA-DRB1*04 were analyzed using sequencing-based typing (SBT) in 291 IgAN cases and 420 matched controls.

Results

The frequency of HLA-DRB1*04 in the IgAN group was significantly higher than that in the control group (0.129 vs. 0.092, P = 8.29 × 10^-5, odds ratio (OR) =1.381, 95% confidence interval (CI) 1.178–1.619). Other alleles at the HLA-DRB1 locus were observed with no significant differences between the case and control groups. The dominant alleles of the HLA-DRB1*04 subtypes were DRB1*0405 in both cohorts. The frequencies of HLA-DRB1*0405 and 0403 were significantly increased in the patients compared to healthy subjects.

Conclusion

HLA-DRB1*04 was significantly associated with primary IgAN in Chinese population. This result implies that HLA-DRB1 gene plays a major role in primary IgAN.

HLA-A*01 is associated with late onset of Alzheimer's disease in Italian patients

In this study, the distribution of HLA-A alleles was analyzed in Italian Alzheimer's Disease (AD)patients. Interaction between HLA alleles, APOE genotypes, age of onset, and gender were also analyzed. The results were compared to those obtained in healthy controls (HC). One hundred-seventy-three AD patients and 258 age-and-sex-matched healthy controls were enrolled in the study. AD patients were classified according to age at the onset of disease using quartiles of the distribution. HLA-A genotyping was performed by PCR-SSP; APOE genotyping was performed by RFLP. A correlation between late disease onset and HLA-A*01 was observed. Thus, HLA-A*01, calculated as number of alleles, was significantly more present in patients with age of onset > 74.0 years than in HC (20% vs 10.5%; p=0.014); the distribution of this allele was skewed also in patients 68.1-74 years of age (16.3%), even if the difference did not reach statistical significance. The relative risk ratio (RRR) of AD onset calculated by a multinomial logistic regression adjusted for sex and presence of APOE-4 confirmed a significant association of HLA-A*01 with AD onset > 74.0 years of age (RRR=2.2; 95%CI: 1.1-4.6; p=0.033). A high RRR (2.04) was also present in patients 68.1-74 years (p=0.064). Lower age of disease onset did not correlate with HLA-A*01. Data herein suggest that the presence of HLA-A*01 results in delayed AD development, even in patients carrying APOE-4. These results could offer new insights into the etiopathogenesis of Alzheimer's disease.

HLA-B8, DR3: a new risk factor for graft failure after renal transplantation in patients with underlying immunoglobulin A nephropathy

BACKGROUND

The HLA-B8, DR3 haplotype has been associated with high immune reactivity. In this study, we have tested whether this haplotype has differential effect on graft survival in patients with IgAN compared with control patients.

METHODS

From the Eurotransplant Registry we analyzed graft survival of 1207 recipients with IgAN and 7935 control patients with non-glomerular diseases. Death-censored graft loss according to the HLA-B8, DR3 haplotype was calculated with Kaplan-Meier analysis and Cox-regression model was used to correct for various risk factors.

RESULTS

The frequency of the HLA-B8, DR3 haplotype was significantly lower in IgAN patients compared with controls (10.3% vs. 15.4%, p < 0.001). Ten-year graft survival was identical in the control group with and without the HLA-B8, DR3 haplotype (71.1% and 70.2%, respectively), but significantly worse in IgAN patients carrying the HLA-B8, DR3 haplotype compared with patients without it (52.5% vs. 69.1%, respectively, p = 0.009). The risk of graft loss was increased by 66% (HR 1.6, 95% CI 1.14, 2.29) in IgAN with the HLA-B8, DR3 haplotype and independent of well-known risk factors.

CONCLUSIONS

We have identified a new risk factor for graft loss unique to patients with IgAN. This finding emphasizes the exclusive immune characteristics of IgAN patients after transplantation.

A novel HLA-B*2730 allele found in a Slovene patient affected with IgA nephropathy

A novel allele HLA-B*2730 and the haplotype HLA-A*03-B*2730-Cw*02-DRB1*16-DRB5 have been found in a Slovene patient and his mother. The exon 2 sequence is identical to that of HLA-B*2702, and the exon 3 sequence is identical to that of HLA-B*2719. A possible mechanism for the generation of B*2730 is a gene conversion event.

Central MHC genes affect IgA levels in the human: reciprocal effects in IgA deficiency and IgA nephropathy

This study investigates the hypothesis that alternative alleles of one or more genes in the central major histocompatibility complex (MHC) predispose carriers to IgA deficiency (IgAD) or IgA Nephropathy (IgAN). Australian caucasian IgAD, IgAN patients, and controls were typed at HLA loci, single nucleotide polymorphisms, and microsatellites in the MHC. Alleles of the D6S273 microsatellite exhibited strong associations with IgAD and IgAN. D6S273*129 and *139 were more frequent in IgAD and less frequent in IgAN patients than controls. The reverse was true for D6S273*133 and *131. Alleles of other microsatellites exhibited weak associations with IgAD or IgAN. D6S273*129 is found on the 65.1 ancestral haplotype [HLA-B14(65),DR1], which has been reported to be increased in IgAD, but the majority of IgAD patients with D6S273*129 did not have other alleles of the haplotype. D6S273*139 is characteristic of the 8.1 ancestral haplotype (HLA-A1,B8,DR3), which was common in IgAD and rare in IgAN patients. Further studies of the 8.1 haplotype in Australian, German and Spanish caucasian subjects revealed that HLA-DR3, in the absence of -B8, is not associated with IgAD. However -B8 is associated with IgAD in the absence of -DR3, consistent with a susceptibility locus in the central MHC. Provisional mapping within this region is discussed.