Focal segmental glomerulosclerosis histologic variants and renal outcomes based on nephrotic syndrome, immunosuppression, and proteinuria remission

BACKGROUND

The associations of focal segmental glomerulosclerosis (FSGS) histologic variants with renal outcomes have rarely been investigated comprehensively by clinically relevant subgroups in this modern age.

METHODS

Data on 304 (173 nephrotic and 131 non-nephrotic) patients with biopsy-confirmed FSGS from 2010 to 2013 were analyzed using the Japanese nationwide renal biopsy registry. The primary outcome was a composite of a 30% decline in estimated glomerular filtration rate or progression to end stage kidney disease 5 years from the biopsy. We compared outcomes of FSGS variants according to the Columbia classification using survival analyses. Subgroup analyses were performed based on nephrotic syndrome (NS), immunosuppression, and proteinuria remission (PR, proteinuria <0.3 g/day) during follow-up. Additionally, associations of NS, immunosuppression, and PR with outcomes were examined for each variant.

RESULTS

The distribution of variants was 48% (n = 145) FSGS not otherwise specified (NOS), 19% (n = 57) tip, 15% (n = 47) perihilar, 13% (n = 40) cellular, and 5% (n = 15) collapsing. The outcome event occurred in 87 patients (29%). No significant differences in the outcome were found among the variants. Subgroup analyses yielded similar results. However, there was a trend toward improved outcome in patients with PR irrespective of variants (hazard ratio adjusted for histologic variant and potential confounders [adjusted HR]: 0.19 [95% confidence interval (CI), 0.10-0.34]). NS was marginally associated with better outcome compared with non-NS (adjusted HR: 0.50 [95% CI, 0.25-1.01].

CONCLUSIONS

FSGS variants alone might not have significant impacts on the renal outcome after 5 years, while PR could be predictive of improved renal prognosis for any variant. Specific strategies and interventions to achieve PR for each variant should be implemented for better renal outcomes.

Clinical manifestations of focal segmental glomerulosclerosis in Japan from the Japan Renal Biopsy Registry: age stratification and comparison with minimal change disease

Focal segmental glomerulosclerosis (FSGS) is a serious condition leading to kidney failure. We aimed to investigate the clinical characteristics of FSGS and its differences compared with minimal change disease (MCD) using cross-sectional data from the Japan Renal Biopsy Registry. In Analysis 1, primary FSGS (n = 996) were stratified by age into three groups: pediatric (< 18 years), adult (18–64 years), and elderly (≥ 65 years), and clinical characteristics were compared. Clinical diagnosis of nephrotic syndrome (NS) was given to 73.5% (97/132) of the pediatric, 41.2% (256/622) of the adult, and 65.7% (159/242) of the elderly group. In Analysis 2, primary FSGS (n = 306) and MCD (n = 1303) whose clinical diagnosis was nephrotic syndrome (NS) and laboratory data were consistent with NS, were enrolled. Logistic regression analysis was conducted to elucidate the variables which can distinguish FSGS from MCD. On multivariable analysis, higher systolic blood pressure, higher serum albumin, lower eGFR, and presence of hematuria associated with FSGS. In Japanese nationwide registry, primary FSGS patients aged 18–64 years showed lower rate of NS than those in other ages. Among primary nephrotic cases, FSGS showed distinct clinical features from MCD.

Association of kidney transplantation with mortality on hemodialysis after graft failure

BACKGROUND

Although a substantial number of patients return to dialysis after kidney transplant failure, it remains controversial whether transplant-failure patients have a higher mortality risk than transplant-naïve patients on dialysis who have never undergone kidney transplantation. We compared outcomes of transplant-failure and transplant-naïve patients on hemodialysis.

METHODS

Data from the Japanese National Dialysis Registry (2012-2013) were analyzed, including 220,438 prevalent hemodialysis patients. Multivariable Cox models were used to compare all-cause, cardiovascular, and infection-related mortality during 1-year follow-up between transplant-failure and transplant-naïve patients. Multiple imputation and propensity score matching were utilized as sensitivity analyses.

RESULTS

During 209,377 patient-years of follow-up, 18,648 all-cause deaths (8.5% of all patients), 7700 cardiovascular deaths (41% of all-cause deaths), and 3806 infection-related deaths (20% of all-cause deaths) were observed. Adjusted hazard ratios [95% confidence intervals] for all-cause, cardiovascular, and infection-related deaths among transplant-failure patients were 0.81 [0.59-1.11], 0.54 [0.30-0.98], and 1.54 [0.92-2.59], respectively. Sensitivity analyses using multiple imputation and propensity score matching yielded similar results.

CONCLUSIONS

This Japanese cohort study suggested that a cardiovascular mortality risk of transplant-failure patients could be significantly lower than that of transplant-naïve patients, while there might be a trend toward a higher infection-related mortality risk in transplant-failure patients. However, this retrospective, single-country study can introduce an immortal time bias in transplant-failure patients, and limit the external validity. Further prospective studies are warranted to improve the comparability of outcomes between transplant-failure and transplant-naïve patients, and to examine worldwide the generalizability of the potential cardiovascular benefit of kidney transplantation even after returning to dialysis.

P0370RELATIONSHIP BETWEEN ATTENUATION OF C3 GLOMERULAR DEPOSITION AND CLINICAL PROGNOSIS IN IGA NEPHROPATHY: REPEAT-BIOPSY BASED OBSERVATION

Background and Aims

In IgA nephropathy (IgAN), mesangial IgA deposition activates the complement systems and amplifies the local inflammation, resulting in renal injuries. Although previous studies based on repeat biopsies suggested that the change of MEST-C scores of Oxford classification might be related to the prognosis, there have been few reports about immunofluorescence (IF) changes in repeat biopsies. In this study, we aimed to elucidate the relationship between the changes in the degree of glomerular IgA and C3 depositions and clinical prognosis of IgAN based on repeat biopsy observation.

Method

Fifty-five patients with IgAN who underwent repeat biopsies at our hospital between 2000 and 2019 were analyzed retrospectively. IF staining in each case was graded with a semiquantitative scale from 0 to 3 (0, negative; 1, weak; 2, moderate; 3, strong staining). MEST-C scores of the Oxford classification were also evaluated. When each score of IF staining or MEST-C in second biopsy was less compared with that in the first biopsy, it was regarded as “improved”. The primary outcome was the time to achieve complete remission (CR), which is defined as disappearance of both urinary protein (UP) (&lt;0.3 g/gCr) and microhematuria (&lt;5/HPF). The secondary outcome was disappearance of microhematuria, disappearance of UP and the rate of eGFR decline. Multivariate analyses were conducted using Cox proportional hazards regression models or linear regression models, adjusted for age, sex and eGFR at the first biopsy.

Results

Twenty-seven patients (48%) were male. At the first biopsy, median age and eGFR were 38.5 years (Interquartile ratio (IQR) 17-49) and 92 mL/min/1.73 m2 (IQR 63-108). Median urinary protein creatinine ratio was 0.6 g/gCr (IQR 0.3-1.7) and 45 patients (80%) had microhematuria. Thirty-three patients (59%) were treated by renin angiotensin system inhibitors and forty-three patients (78%) were treated by immunosuppressive therapy. Median period between the two biopsies was 36 months (IQR 25-55). Median IF scores of glomerular IgA and C3 were 2 (IQR 2-3) and 2 (IQR 1-2) in the first biopsies and 2 (IQR 1-2) and 1 (IQR 1-2) in the second biopsies, respectively. During the median 55 months (IQR 17-99) follow up period, disappearance of UP and microhematuria were observed in 47 (84%) and 36 (64%). Thirty-three (59%) patients reached CR. Improvement of the degree of C3 deposition between two biopsies was significantly associated with CR (Hazard ratio (HR) 0.37; 95% confidential interval (CI) 0.17-0.80, p=0.012), while that of IgA deposition had no association (HR 057; CI 0.27-1.19, p=0.125). Improvement of the degree of C3 deposition was also significantly associated with disappearance of microhematuria (HR 0.45; 95%CI 0.24-0.86, p=0.016), but not with disappearance of UP (HR 0.60; 95%CI 0.34-1.2, p=0.15). Multivariate linear regression revealed that the rate of eGFR decline was not related to IF scores. Any of the Oxford classification scores were not associated with these outcomes.

Conclusion

Attenuation of glomerular C3 deposition is associated with CR. This suggest that C3 deposition, rather than IgA deposition, may be related with the clinical prognosis of IgAN.

Glomerular basement membrane duplication is a predictor of the prognosis of diabetic nephropathy in patients with type 2 diabetes

BACKGROUND

Several clinical parameters and pathological findings are known to be predictors of the deterioration of diabetic nephropathy (DN). Glomerular basement membrane duplication (GBM-DP) is a pathological feature representing endothelial injury, which is commonly observed in DN. In the present study, we investigated the association between GBM-DP and the renal prognosis in DN.

METHODS

The study enrolled 80 patients with renal biopsy-proven DN who were managed at Chiba-East Hospital from 2005 to 2012. We confirmed the pathological findings according to the Renal Pathology Society classifications, and we further evaluated the GBM-DP, which was defined as double contours of the GBM that expanded more than 10% of capillary loops in the most affected nonsclerotic glomerulus. We used Cox regression models to estimate hazard ratios (HRs) for end-stage renal disease (ESRD), with adjustment for age, sex, systolic blood pressure, HbA1c, estimated glomerular filtration rate (eGFR), and urinary protein excretion (UP) at baseline.

RESULTS

Of the 80 patients, 56 were male (70.0%) and the mean age was 59.1 years. The median eGFR and UP were 42 ml/min/1.73 m² (IQR 30, 59) and 3.1 g/gCr (IQR 1.2, 5.2). Twenty-seven patients progressed to ESRD and one patient died during the median observational period of 2.9 years (IQR 1.5, 4.3). The multivariable analyses showed that GBM-DP was significantly associated with ESRD (HR 3.18 [95% confidence interval (CI): 1.02-9.87], p = 0.045).

CONCLUSION

We newly identified GBM-DP as a strong prognostic predictor in DN patients. Further study is needed to clarify the pathogenic mechanism of GBM-DP in DN.

Hemodialysis patients born with a low birth weight should have a different time course of kidney diseases than those born with a normal birth weight

Low birth weight (LBW) is thought to be one of the risk factors for the progression of kidney diseases. This study hypothesized that the onset age of kidney disease, the rate of progression of kidney disease, or the age at the time of hemodialysis (HD) induction among HD patients that were born with LBW is different from those without a history of LBW. A questionnaire survey in nine dialysis units in Japan was performed and 427 answer sheets were collected. There were statistically significant differences in the present age, the age of kidney disease onset, and the age of HD induction between LBW group and normal birth weight group (NBW). An analysis limited to participants whose underlying disease was diabetic nephropathy revealed that the duration from the onset of nephropathy to HD induction was much shorter in HD patients with a history of LBW than those with a NBW history. In addition, the Pearson's correlation coefficient between the birth weight and the period from onset of diabetic nephropathy to HD induction was 0.283. Although these results might partly support the primary hypothesis, the necessity to perform other clinical studies is also emphasized.

Transforming growth factor-beta1 gene polymorphism modifies the histological and clinical manifestations in Japanese patients with IgA nephropathy

Transforming growth factor (TGF)-beta1, a multifunctional cytokine, which regulates proliferation and differentiation of a variety of cell types, has the central role in the development and progression of renal injury in both animal models and human. Although it has been suggested that genetic variations in the TGF-beta1 gene are associated with the activity of the gene product, their clinical significance in glomerular disease is unknown. We investigated whether the polymorphisms of C-509T and T869C in TGF-beta1 account for interindividual variation in manifestations of IgA nephropathy (IgAN) using 626 Japanese subjects including 329 patients with histologically proven IgAN and 297 healthy controls with normal urinalysis. The frequencies of genotypes, alleles, and major haplotypes were similar between the patients and controls. The C-509T and T869C polymorphisms were in tight linkage disequilibrium, and the major haplotypes were C-C and T-T, which accounted for more than 95% of the total. In patients with -509CC and in those with the 869CC, urinary protein excretion was higher than in those with other genotypes, whereas no difference in other clinical manifestations was noted. Moreover, patients with -509CC and those with 869CC genotypes presented with a significant higher score of mesangial cell proliferation than in those with other genotypes. These results suggest that TGF-beta1 gene polymorphisms are specifically associated with heavy proteinuria and mesangial cell proliferation in Japanese patients with IgAN, although they do not confer susceptibility to this disease.

Discovery of imprinted transcripts in the mouse transcriptome using large-scale expression profiling

Candidate imprinted transcriptional units in the mouse genome were identified systematically from 27,663 FANTOM2 full-length mouse cDNA clones by expression profiling. Large-scale cDNA microarrays were used to detect differential expression dependent upon chromosomal parent of origin by comparing the mRNA levels in the total tissue of 9.5 dpc parthenogenote and androgenote mouse embryos. Of the FANTOM2 transcripts, 2114 were identified as candidates on the basis of the array data. Of these, 39 mapped to known imprinted regions of the mouse genome, 56 were considered as nonprotein-coding RNAs, and 159 were natural antisense transcripts. The imprinted expression of two transcripts located in the mouse chromosomal region syntenic to the human Prader-Willi syndrome region was confirmed experimentally. We further mapped all candidate imprinted transcripts to the mouse and human genome and were shown in correlation with the imprinting disease loci. These data provide a major resource for understanding the role of imprinting in mammalian inherited traits.

Novel glomerular lipoprotein deposits associated with apolipoprotein E2 homozygosity

BACKGROUND

Hyperlipoproteinemia is occasionally associated with severe glomerular injury caused by abnormal accumulation of lipid in glomeruli, which occurs in conditions such as lipoprotein glomerulopathy (LPG). This study investigates the cases of two siblings with homozygous apolipoprotein (apo) E2 who show unique histologic features, massive proteinuria, and dysbetalipoproteinemia.

METHODS

Histologic studies were performed using renal biopsy specimens. Plasma lipoproteins were extensively characterized. The exons of the apo E genes were sequenced to avoid missing any mutations.

RESULTS

Histologically, the siblings' condition resembled LPG by light microscopy studies. Electron microscopy studies revealed large lipoid deposits in the paramesangium, subendothelium, and subepithelium of the glomeruli, which were different from LPG in terms of not forming the layered structure resembling a fingerprint even in large lipoprotein thrombi, and mesangial foam cells. Immunohistochemically, the lipoid deposits contained apo E and apo B. These patients did not have either diabetic nephropathy or other known forms of glomerulonephritis. The sequence of exons of the apo E genes revealed homozygosity for apo E2 in both cases.

CONCLUSION

The extensive lipoprotein deposition in glomeruli, which resembles LPG, can also occur in apo E2 homozygous individuals, but in a distinct fashion. Because the two cases were siblings, they may have other shared alleles, in addition to the apo E2 allele, that negatively affect processing of lipoproteins and lead to abnormal accumulation of lipoprotein deposits in glomeruli.