Lars Wramner

Association of soluble CD89 levels with disease progression but not susceptibility in IgA nephropathy

The Fc-α receptor (FcαR/CD89) is involved in IgA complex formation and may affect the development of IgA nephropathy (IgAN). In this study, we tested the genetic variations of the CD89 gene in relation to disease susceptibility in IgAN and the expression of soluble CD89 (sCD89) in sera of patients with IgAN and in controls. There was a significant difference between the levels of sCD89-IgA complexes, measured by sandwich enzyme-linked immunosorbent assay (ELISA), in 177 patients with IgAN with and without disease progression at the time of first diagnosis. No such difference was found in 42 patients with other renal diseases. The patients with IgAN without disease progression had stable but high levels of sCD89 over 5-15 years of follow-up in contrast to stable but low levels of sCD89 in the disease progression group. Moreover, levels of sCD89 complexes were correlated with one of the five CD89 genetic variants in 212 patients with IgAN and 477 healthy Caucasians; the single-nucleotide polymorphism (SNP) rs11084377 was significantly associated with a lower expression of sCD89. However, no association between CD89 gene polymorphisms and susceptibility to IgAN was detected. Thus, we found an association between the levels of sCD89-IgA complexes in serum and the severity of IgAN, and a possible genetic component in regulating the production or expression of sCD89.

Genetic variation in the transforming growth factor-β1 gene is associated with susceptibility to IgA nephropathy

Background. There is growing evidence of genetic risk for susceptibility to IgA nephropathy. Among several candidate genes related to immunological regulation in renal tissue, TGFB1 is known to be a contributor to proliferation and the development of fibrosis. Methods. We analysed several SNPs in a region of this gene using 212 DNA samples from biopsy-proven IgA nephropathy patients, 146 men and 66 women and 477 healthy age-matched controls (321 men and 156 women) from the same population in Sweden. Results. Frequencies of four out of five selected SNPs (rs6957, rs2241715, rs1800471, rs1982073 and rs1800469) were found to significantly differ between male patients and male controls in a co-dominant model (corrected P ≤ 0.05) and of two SNPs (rs1982073 and rs1800469) in the allelic model (P ≤ 0.05 in 100 000 permutation test). Haplotype analysis for five selected SNPs revealed a significant association of TGGCG with protective effect (P = 0.0012, empirical P = 0.006, 100 000 permutations) and of CTGTA with susceptibility effect (P = 0.0018, empirical P = 0.008, 100 000 permutations). In our study, no association with TGFB1 variations was found when comparing female patients and female controls. No association was found for TGFB1 markers with disease progression for selected individuals from the patients group. In addition, meta-analysis performed for SNP rs1982073 for combined patients and controls from our study together with published data from two independent studies showed a significant association. Conclusions. Our experimental data together with the meta-analysis suggest TGFB1 as an important candidate gene for further biological studies of IgA nephropathy and as a possible target for therapy. Our data also indicate a possibility of a gender effect in the genetic background of IgA nephropathy.

Genetic Risk Factors in Lupus Nephritis and IgA Nephropathy – No Support of an Overlap

Background IgA nephropathy (IgAN) and nephritis in Systemic Lupus Erythematosus (SLE) are two common forms of glomerulonephritis in which genetic findings are of importance for disease development. We have recently reported an association of IgAN with variants of TGFB1. In several autoimmune diseases, particularly in SLE, IRF5, STAT4 genes and TRAF1-C5 locus have been shown to be important candidate genes. The aim of this study was to compare genetic variants from the TGFB1, IRF5, STAT4 genes and TRAF1-C5 locus with susceptibility to IgAN and lupus nephritis in two Swedish cohorts. Patients and Methods We genotyped 13 single nucleotide polymorphisms (SNPs) in four genetic loci in 1252 DNA samples from patients with biopsy proven IgAN or with SLE (with and without nephritis) and healthy age- and sex-matched controls from the same population in Sweden. Results Genotype and allelic frequencies for SNPs from selected genes did not differ significantly between lupus nephritis patients and SLE patients without nephritis. In addition, haplotype analysis for seven selected SNPs did not reveal a difference for the SLE patient groups with and without nephritis. Moreover, none of these SPNs showed a significant difference between IgAN patients and healthy controls. IRF5 and STAT4 variants remained significantly different between SLE cases and healthy controls. In addition, the data did not show an association of TRAF1-C5 polymorphism with susceptibility to SLE in this Swedish population. Conclusion Our data do not support an overlap in genetic susceptibility between patients with IgAN or SLE and reveal no specific importance of SLE associated SNPs for the presence of lupus nephritis.

Renal function in renal or liver transplant recipients after conversion from a calcineurin inhibitor to sirolimus

Abstract:  Two Six‐month pilot studies were conducted in renal (n=17) or liver (n=15) transplant recipients to evaluate renal function after conversion from calcineurin inhibitor (CI)‐ to sirolimus (SRL)‐based immunosuppression. After an SRL loading dose, doses were individualized to achieve whole blood trough levels of 10–22 ng/mL. Overall, serum creatinine did not change from baseline to six months post‐conversion but an improvement from 219.9 to 201.4 μmol/L at three months was noted in renal transplant recipients (p<0.05). Another finding was a numerical increase in the mean glomerular filtration rate (GFR) from 26.8 to 33.2 mL/min/1.73 m2 at six months among liver transplant recipients (NS). All patients survived and all grafts were functioning at the end of the study. In conclusion, renal function remained stable, with a tendency towards improvement, after abrupt conversion from CI‐ to SRL‐based therapy in renal or liver transplant recipients with moderate renal insufficiency.

Macrovascular disease after simultaneous pancreas and kidney transplantation.

Abstract:  The objective of this study was to evaluate the outcome of simultaneous pancreas and kidney transplantation (SPK) with focus on cardiovascular mortality and morbidity in relation to graft function. From January 1985 through 1999, 87 SPK were performed in the unit. Sixty recipients were males, median age at diabetes onset 13 yr (1–40) and age at transplantation 39 yr (29–54). No case was lost to follow‐up. Morbidity and mortality during median 8 yr of follow‐up (range 1–15 yr) were recorded. Major macrovascular disease (MVD) was defined as myocardial infarction or sudden death (AMI), stroke or peripheral gangrene requiring amputation of leg, foot or fingers. At the evaluation, 26 of 87 patients (30%) had died, 19 after loss of the pancreas graft and 20 after loss of the kidney. MVD was the dominant cause of death. Non‐lethal MVD had previously been recorded in 62%. Of the 61 patients alive, 22 had lost their pancreas graft and 12 the concomitant kidney. MVD had occurred in 32%. Whereas 89% of the concomitant kidneys functioned when the pancreas graft did so, only 37% of the kidneys functioned if the pancreas had been lost, p < 0.0001. The mortality rate was significantly higher among patients who lost both grafts (16/26) than in those who lost only the pancreas graft (3/15), p = 0.01. Progressive MVD is a major clinical problem for SPK transplant patients, particularly if the kidney fails.

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.