Primary focal segmental glomerulosclerosis: clinical course, predictors of renal outcome and treatment

C1q nephropathy in adults is a form of focal segmental glomerulosclerosis in terms of clinical characteristics

Although C1q nephropathy (C1qN) was introduced three decades ago, the clinical significance and renal outcomes of C1qN remain unclear. This study aimed to evaluate the clinical characteristics of C1qN, including renal outcomes, by performing a matched comparison within a multicenter cohort. We enrolled 6,413 adult patients who underwent kidney biopsy between January 2000 and January 2018 at three tertiary hospitals in Korea. We compared the clinical characteristics of 23 patients with C1qN with those of patients with focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD) who were matched by age, sex, diabetic status, and a period of biopsy. Histological and clinical parameters in patients with C1qN were also evaluated according to the different pathological phenotypes. For a mean follow-up period of 92 months, 4 patients with C1qN (17.4%) developed end-stage renal disease (ESRD). None of the matched patients with MCD had ESRD, but 7 (30.4%) of patients with FSGS progressed to ESRD, which was not different from that of C1qN patients (p = 0.491). Laboratory and pathological findings, except segmental glomerulosclerosis, were not notably different between FSGS and C1qN. The presence of segmental glomerulosclerosis, mesangial hypercellularity, and podocyte effacement did not affect both the short- and long-term renal outcomes in patients with C1qN. Our study showed that the renal outcomes of C1qN are comparable with those of FSGS, and not with MCD. Specific pathological findings, including segmental glomerulosclerosis in C1qN, were not associated with renal outcomes, which may suggest homogeneity in the clinical features of C1qN.

Long-term outcomes for primary glomerulonephritis: New Zealand Glomerulonephritis Study

AIMS

Due to the paucity of studies focusing on primary glomerulonephritis, the second commonest cause of end-stage-kidney-disease in most of the developed world, we sought to review outcomes of these renal pathologies.

METHODS

We reviewed renal outcomes and mortality for primary glomerulonephritis patients enrolled in the New Zealand Glomerulonephritis Study between 1972 and 1983.

RESULTS

There were 765 patients with median follow-up of 30 years (range 0.1-42 years). They were predominantly New Zealand European, male and hypertensive. Poor renal outcomes and increased mortality were associated with hypertension, heavy proteinuria, impaired renal function and older age at diagnosis. Ethnicity was not significantly associated with progression to end-stage-kidney-disease although NZ Maori patients were at significantly increased risk of death. Patients with rapidly progressive glomerulonephritis had the highest risk of reaching end-stage-kidney-disease while the cumulative incidence of end-stage-kidney-disease was 20% and 30% for those with immunoglobulin-A nephropathy and membranous nephropathy respectively. Mortality risk was high for patients with rapidly progressive glomerulonephritis and anti-glomerular basement membrane disease. The era of diagnosis did not have much effect on outcomes except for patients with focal segmental glomerulosclerosis or immunoglobulin A nephropathy but this could be type II error.

CONCLUSION

We report one of the longest follow-up studies on biopsy-proven glomerulonephritides. Age, hypertension, and severity of chronic kidney disease at diagnosis were strong predictors of the development of end-stage-kidney-disease and death. The specific renal pathology had a profound impact upon prognosis and therefore should continue to drive efforts to find targeted therapeutic options for these glomerulonephritides.

Kidney biopsy results versus clinical parameters on mortality and ESRD progression in 2687 patients with glomerulonephritis

BACKGROUND

Physicians refer proteinuric patients to kidney biopsy in order to clarify the issue of underlying renal disease. We compared kidney biopsy results with classical outcome parameters in a large cohort of patients with biopsy proven glomerulonephritis (GN).

METHODS

In a retrospective analysis, 2687 patients with different forms of GN from 123 Austrian centres were investigated. Patient characteristics, the diagnosis of GN and its respective subtype and clinical symptoms such as arterial hypertension, haematuria, amount of proteinuria and estimated glomerular filtration rate (eGFR) were tested for their association with all-cause mortality and progression to end-stage renal disease (ESRD).

RESULTS

During a median follow-up of 129·9 months (IQR 89·6; 177·7), 688 patients (25·6%) died and 718 patients required dialysis (29·4%). In multivariate Cox's regression analysis age (HR 1·06), female sex (HR 0·71), eGFR (HR 0·74), the diagnosis of GN and its subtypes predicted patient survival (all P < 0·01), whereas the amount of proteinuria was not associated with patient survival. The incidence of progression to ESRD was associated with female sex (HR 0·71), eGFR (HR 0·65), amount of proteinuria (HR 1·15) and the diagnosis of GN and its subtypes (all P < 0·01). Nephrotic or nephritic syndromes were not associated with patient survival or progression to ESRD and did not add further predictive value to outcome of GN.

CONCLUSIONS

Our study demonstrates histological diagnosis of GN and its specific subtype predicts patient survival and dialysis incidence. Therefore, kidney biopsy should be an integral part of routine diagnostic assessment in patients with any forms of suspected GN.

Independent or synergistic relationship of proteinuria and glomerular filtration rate on patient and renal survival in patients with glomerulonephritis?

BACKGROUND

Glomerular filtration rate (GFR) in patients with chronic kidney disease (CKD) identifies patients at risk for death or end-stage renal disease (ESRD). CKD staging by GFR should incorporate proteinuria to augment risk stratification. We therefore tested the predictive power of the combination of GFR with proteinuria in patients with different histologically-diagnosed types of glomerulonephritis (GN).

METHODS

In a retrospective analysis, 2,687 patients with different forms of GN from 123 Austrian centres were investigated. Full data sets were available from 1,892 subjects. Classes of CKD on the basis of estimated GFR (eGFR) and of proteinuria grouped as <1, 1-3.5, and >3.5 g/24 h were tested for their association with all-cause mortality and ESRD.

RESULTS

During a median follow-up of 130 months [interquartile range (IQR) 90; 178] 478 patients (25.3 %) died. Median eGFR was 49 ml/min/1.73 m(2) (IQR 24; 81) and proteinuria 3.8 g/24 h (IQR 1.7; 8.0). Adjusted multivariate Cox regression indicated that renal survival but not overall survival is related to proteinuria >3.5 g/24 h [as opposed to <1 g/24 h; hazard ratio (HR) 1.91] and shows progression to ESRD. However, subgroup analyses revealed that this risk with proteinuria >3.5 g/24 h exists only in patients with immunoglobulin (Ig)A GN (HR 4.93), miscellaneous GN (HR 1.74), and CKD stage 5 (HR 2.50). Additionally, proteinuria is a risk factor for renal survival in males more than in females with GN and proteinuria >3.5 g/24 h (HR 1.91).

CONCLUSION

Proteinuria is a strong risk factor for renal survival particularly in patients with proteinuria >3.5 g/24 but not for all types of GN, nor for all CKD stages. Proteinuria is not a risk factor for overall survival in patients with GN.

The expression of cytoskeletal proteins in kidney specimens of children with primary focal segmental glomerulosclerosis

Several studies have evaluated cytoskeletal proteins as prognostic factors for some types of nephrotic syndrome. However, studies concerning children with FSGS are scarce. This study was done to evaluate the glomerular, tubular, and interstitial expression of vimentin, desmin, and alpha smooth muscle actin (α-SMA) in kidney specimens of children with FSGS. Clinical and histologic data of 31 children with FSGS were reviewed. Thirty one formalin-fixed, paraffin-embedded kidney biopsy sections (3 μm) were selected for immunohistochemical staining. Double immunohistochemistry using a microwave-based two-color staining was applied. The mean age at onset in male and female was 56.3 ± 41.4 and 78.0 ± 60.4 months, respectively. The duration of follow-up was 46.3 ± 56.5 months. Interstitial fibrosis and tubular atrophy were reported in 42% and 54% of the patients, respectively. The latest evaluated mean blood pressure was significantly correlated with the expression of both vimentin and α-SMA in the interstitium (P < 0.05). However, we were not able to demonstrate any cytoskeletal protein expression as an independent predictor for renal survival. Further studies with larger sample size and longer follow-up periods are warranted to investigate the prognostic values of other histopathologic features in pediatrics with FSGS.

Kidney biopsy in patients with glomerulonephritis: is the earlier the better?

BACKGROUND

Interventional diagnostic procedures are established for several diseases in medicine. Despite the KDOQI guideline recommendation for histological diagnosis of kidney disease to enable risk stratification, its optimal time point has not been evaluated. We have therefore analyzed whether histological diagnosis of glomerulonephritis (GN) at an early stage of chronic kidney disease (CKD) is associated with different outcome compared to diagnosis at a more advanced stage.

METHODS

A cohort of 424 consecutive patients with histological diagnosis of GN were included in a retrospective data analysis. Kidney function was assessed by glomerular filtration rate (GFR) estimation at the time point of kidney biopsy and after consecutive immunosuppressive therapy. Censored events were death, initiation of dialysis or kidney transplantation, or progression of disease, defined as deterioration of CKD stage ≥ 1 from kidney biopsy to last available kidney function measurement.

RESULTS

Occurrence of death, dialysis/transplantation or progression of disease were associated with GFR and CKD stage at the time of kidney biopsy (p < 0.001 for all). Patients with CKD stage 1 and 2 at kidney biopsy had fewer endpoints compared to patients with a GFR of <60 ml/min (p < 0.001).

CONCLUSION

Kidney function at the time point of histological GN diagnosis is associated with clinical outcome, likely due to early initiation of specific drug treatment. This suggests that selection of therapy yields greatest benefit before renal function is impaired in GN.

A phase 1, single-dose study of fresolimumab, an anti-TGF-β antibody, in treatment-resistant primary focal segmental glomerulosclerosis

Primary focal segmental glomerulosclerosis (FSGS) is a disease with poor prognosis and high unmet therapeutic need. Here, we evaluated the safety and pharmacokinetics of single-dose infusions of fresolimumab, a human monoclonal antibody that inactivates all forms of transforming growth factor-β (TGF-β), in a phase I open-label, dose-ranging study. Patients with biopsy-confirmed, treatment-resistant, primary FSGS with a minimum estimated glomerular filtration rate (eGFR) of 25  ml/min per 1.73  m(2), and a urine protein to creatinine ratio over 1.8  mg/mg were eligible. All 16 patients completed the study in which each received one of four single-dose levels of fresolimumab (up to 4  mg/kg) and was followed for 112 days. Fresolimumab was well tolerated with pustular rash the only adverse event in two patients. One patient was diagnosed with a histologically confirmed primitive neuroectodermal tumor 2 years after fresolimumab treatment. Consistent with treatment-resistant FSGS, there was a slight decline in eGFR (median decline baseline to final of 5.85 ml/min per 1.73  m(2)). Proteinuria fluctuated during the study with the median decline from baseline to final in urine protein to creatinine ratio of 1.2  mg/mg with all three Black patients having a mean decline of 3.6  mg/mg. The half-life of fresolimumab was ∼14 days, and the mean dose-normalized Cmax and area under the curve were independent of dose. Thus, single-dose fresolimumab was well tolerated in patients with primary resistant FSGS. Additional evaluation in a larger dose-ranging study is necessary.

Expression of JAKs/STATs pathway molecules in rat model of rapid focal segmental glomerulosclerosis

The objective of this study was to investigate the role of the Janus kinase-signal transducers and activators of transcription (JAKs/STATs) pathway in focal segmental glomerulosclerosis. Sixty specific pathogen-free male Wistar rats were randomly divided into two groups: a model group (MG) and a control group (CG). In the MG group, nephropathy was induced by unilateral nephrectomy and a single tail vein injection of adriamycin (5 mg/kg). Ten rats were sacrificed every 2 weeks in each group. The expressions of smooth muscle alpha actin (alpha-SMA), collagen (COL)-IV, STAT1, and STAT3 were examined using histochemical techniques, and Western blotting was used to examine the protein levels of STAT1, STAT3, phosphorylated (P)-STAT1, P-STAT3, and transforming growth factor beta1 (TGFbeta(1)). The expressions of JAK1, JAK2, STAT1, STAT3, suppressors of cytokine signaling (SOCS)1, SOCS3, protein inhibitors of activated STAT (PIAS)1, and PIAS3 were also measured by real-time quantitative reverse transcriptase-PCR. A steady and significant increase in the expressions of alpha-SMA, COL-IV and TGFbeta(1) were observed in MG rats over the whole experimental course. Increased STAT1 and P-STAT1 levels in MG rats were observed by week 6, whereas increased levels of STAT3 and P-STAT3 were noted by week 2. At the mRNA levels, JAK1, STAT1, and PIAS1 were significantly increased in MG rats in week 2, whereas JAK2 mRNA showed a significant decrease by weeks 2 and 4, followed by an significant increase in week 6. Significantly increased STAT3 levels were noted in week 2, followed by a steady and significant decrease in weeks 4 and 6. Significantly reduced levels of SOCS1, SOCS3, and PIAS3 mRNA were noted at all time points. We conclude that the JAKs/STATs signaling pathway may play an important role in the pathological process of rapid focal segmental glomerulosclerosis in the rat model.

Rituximab treatment of collapsing C1q glomerulopathy: clinical and histopathological evolution

A 13-year-old girl with obesity and hyperinsulinism developed steroid-resistant nephrotic syndrome due to collapsing glomerulopathy with dominant C1q-containing mesangial immune deposits (CG/C1qN). She became overtly diabetic while receiving alternate-day prednisone and tacrolimus, requiring insulin injections. Despite the addition of mycophenolate mofetil to the treatment regimen, renal function subsequently declined. Rituximab (four weekly doses of 375 mg/m2) was tried 6 months after initial presentation and 3 months after weaning all glucocorticoids. Glomerular filtration rate (GFR) and proteinuria improved. Unexpectedly, blood sugar control normalized 6 weeks after antibody infusion. Rituximab was readministered 20 months after the first course because of deteriorating renal function, but the effect on GFR and proteinuria was modest. A retrospective analysis revealed that tubulointerstitial infiltrates present in the biopsies prior to treatment with rituximab contained numerous CD20+ and CD3+ (CD4 > CD8) lymphocyte aggregates. Rebiopsy 10 weeks after repeat rituximab therapy demonstrated the elimination of B-cell infiltrates and the apparent decrease of interstitial T-cell infiltrates, yet persistent, advanced global glomerulosclerosis, interstitial fibrosis and tubular atrophy. In conclusion, CG/C1qN was associated with B- and T-cell-rich tubulointerstitial infiltrates. B-cell-directed therapy delayed clinical progression during early disease but failed to prevent or ameliorate chronic changes, despite effective tissue B-cell clearance. The incidental resolution of diabetes was noted after rituximab treatment.

Predictors of long-term outcome of children with idiopathic focal segmental glomerulosclerosis

Clinical and histological data of children presenting with steroid-resistant nephrotic syndrome and renal biopsy showing focal and segmental glomerulosclerosis from 1980 with a follow-up of over 10 years were reviewed. There were 66 patients; 38 male and 28 female. Age at onset ranged from 0.4-14.1 years (mean 6.4). Tubular atrophy was present at first biopsy in 50/66, capsular adhesions in 35/66, glomerular tip lesions in 8/66 and mesangial expansion in 31/66 patients. In 51 children, cyclophosphamide was prescribed as the first cytotoxic agent, while 15 received cyclosporine A and complete remission was induced in 43 and 40% of the children, respectively. Complete and stable remission was maintained in 35 children, while 22 had reduction of proteinuria with symptomatic relief. Nine were refractory to cytotoxic therapy. Of the 35 patients who entered complete and stable remission, the renal survival was over 90%, while in the 31 non-responders it was 48% in 10 years. The multivariate analysis using unconditional logistic regression method identified the presence of mesangial expansion (p=0.011) and tip lesions (p=0.005) as the independent predictors of favourable response to cytotoxic therapy and the presence of renal impairment (p=0.008) and extensive focal segmental sclerosis (p=0.025) as independent predictors of unfavourable response.

Angiotensin II induces apoptosis in renal proximal tubular cells

ANG II has been demonstrated to play a role in the progression of tubulointerstial injury. We studied the direct effect of ANG II on apoptosis of cultured rat renal proximal tubular epithelial cells (RPTECs). ANG II promoted RPTEC apoptosis in a dose- and time-dependent manner. This effect of ANG II was attenuated by anti-transforming growth factor (TGF)-beta antibody. Moreover, TGF-beta triggered RPTEC apoptosis in a dose-dependent manner. ANG II also enhanced RPTEC expression of Fas and Fas ligand (FasL); furthermore, anti-FasL antibody attenuated ANG II-induced RPTEC apoptosis. In addition, ANG II increased RPTEC expression of Bax, a cell death protein. Both ANG II type 1 (AT(1)) and type 2 (AT(2)) receptor blockers inhibited ANG II-induced RPTEC apoptosis. SB-202190, an inhibitor of p38 MAPK phosphorylation, and caspase-3 inhibitor also attenuated ANG II-induced RPTEC apoptosis. ANG II enhanced RPTEC heme oxygenase (HO)-1 expression. Interestingly, pretreatment with hemin as well as curcumin (inducers of HO-1) inhibited the ANG II-induced tubular cell apoptosis; conversely, pretreatment with zinc protoporphyrin, an inhibitor of HO-1 expression, promoted the effect of ANG II. These results suggest that ANG II-induced apoptosis is mediated via both AT(1) and AT(2) receptors through the generation of TGF-beta, followed by the transcription of cell death genes such as Fas, FasL, and Bax. Modulation of tubular cell expression of HO-1 has an inverse relationship with the ANG II-induced tubular cell apoptosis.