C3 glomerulopathy: experience of a pediatric nephrology center

C3 glomerulopathy in children: a European longitudinal study evaluating outcome

BACKGROUND

C3 glomerulopathy is a rare clinical entity characterized by dysregulation of the alternative complement pathway in glomerular disease. Studies defining the natural history of C3G in the pediatric population are scarce.

METHODS

Patients included in this retrospective study were diagnosed between 2011 and 2020 in 12 European pediatric nephrology units. Data were collected from baseline, 6 months, 12 months and at the last follow-up. Complete remission (CR) was defined as a urinary protein creatinine ratio (UPCR) < 0.3 mg/mg with normal estimated glomerular filtration rate (eGFR). Partial remission was defined as a decrease in UPCR to 0.3 and 3 mg/mg with normal eGFR. Lack of remission was defined as non-response.

RESULTS

A total of 108 pediatric patients were included. Complete remission was achieved in 71/108 patients (65.7%), with probability of CR of 50% at 1.8 years and of 78% at 7 years. At presentation by univariate analysis the predictive factors at presentation associated with CR included eGFR (p = 0.028), UPCR (p = 0.004), serum C3 levels (p = 0.018), elevated plasma sC5b9 levels, defined as > 400 ng/ml, (p = 0.037), the presence of endocapillary proliferation (p = 0.017), and the absence of dense deposits on electron microscopy (p = 0.032). By multivariate analysis a low UPCR at presentation (p < 0.001) and the presence of endocapillary proliferation (p < 0.01) remained positively associated with CR.

CONCLUSIONS

Our data confirm that C3G has a more benign outcome in children compared to previous reports in adults, and suggest that endocapillary proliferation and the degree of proteinuria at onset are the most relevant prognostic factors.

Predictors of poor kidney outcome in children with C3 glomerulopathy

BACKGROUND

C3 glomerulopathy (C3G) is characterized by heterogeneous clinical presentation, outcome, and predominant C3 accumulation in glomeruli without significant IgG. There is scarce outcome data regarding childhood C3G. We describe clinical and pathological features, treatment and outcomes, and risk factors for progression to chronic kidney disease stage 5 (CKD5) in the largest pediatric series with biopsy-proven C3G.

METHODS

Sixty pediatric patients with C3G from 21 referral centers in Turkey were included in this retrospective study. Patients were categorized according to CKD stage at last visit as CKD5 or non-CKD5. Demographic data, clinicopathologic findings, treatment, and outcome data were compared and possible risk factors for CKD5 progression determined using Cox proportional hazards model.

RESULTS

Mean age at diagnosis was 10.6 ± 3.0 years and follow-up time 48.3 ± 36.3 months. Almost half the patients had gross hematuria and hypertension at diagnosis. Nephritic-nephrotic syndrome was the commonest presenting feature (41.6%) and 1/5 of patients presented with nephrotic syndrome. Membranoproliferative glomerulonephritis was the leading injury pattern, while 40 patients had only C3 staining. Patients with DDD had significantly lower baseline serum albumin compared with C3GN. Eighteen patients received eculizumab. Clinical remission was achieved in 68.3%. At last follow-up, 10 patients (16.6%) developed CKD5: they had lower baseline eGFR and albumin and higher frequency of nephrotic syndrome and dialysis requirement than non-CKD5 patients. Lower serum albumin and eGFR at diagnosis were independent predictors for CKD5 development.

CONCLUSIONS

Children with C3G who have impaired kidney function and hypoalbuminemia at diagnosis should be carefully monitored for risk of progression to CKD5. Graphical abstract.

Therapy and outcomes of C3 glomerulopathy and immune-complex membranoproliferative glomerulonephritis

BACKGROUND

Data on therapy and outcome of dense deposit disease (DDD), C3 glomerulonephritis (C3GN), and immune-complex MPGN (IC-MPGN) in children are limited.

METHODS

In this retrospective single-center study from 2007 to 2019, kidney biopsies were reviewed to include patients aged <18-years with C3 glomerulopathy and IC-MPGN. Initial immunosuppression comprised prednisolone, mycophenolate mofetil (n = 51), tacrolimus (n = 11), and/or IV cyclophosphamide (n = 20). Clinicopathological features, response to therapy, and adverse outcome (eGFR_cr < 15 mL/min/1.73 m² or death) were evaluated.

RESULTS

A total of 92 patients were classified as DDD (n = 48, 52.2%), C3GN (n = 26, 28.3%), and IC-MPGN (n = 18, 19.6%) by immunohistochemistry and electron microscopy; 8 patients with DDD were misclassified as IC-MPGN on immunofluorescence. At last follow-up (median 4.3 years), complete or partial remission occurred in 28.5, 36.1, and 16.7% patients with DDD, C3GN, and IC-MPGN, respectively. Serum albumin at onset < 2.5 g/dL (HR = 0.29, P = 0.005) and persistently low serum C3 (HR = 0.34, P = 0.02) were associated with lack of remission. The 5-year kidney survival was 62.6, 85.5, and 88.5% in patients with DDD, C3GN, and IC-MPGN, respectively (log-rank, P = 0.006). Presentation as rapidly progressive GN (HR = 11.2, P < 0.001), age > 10 years at onset (HR = 4.0, P = 0.004), and DDD (HR = 4.2, P = 0.02) were independently associated with adverse outcome; achieving remission was protective (HR = 0.04; P < 0.001).

CONCLUSION

Outcome in patients with C3 glomerulopathy and IC-MPGN was unsatisfactory, and only a small proportion of patients achieved complete or partial remission. Patients with DDD were more likely to present with rapidly progressive GN and were at higher risk of adverse outcomes, including kidney failure.