Advances in the understanding of complement mediated glomerular disease: implications for recurrence in the transplant setting

Successful Use of Mycophenolate Mofetil as Adjunct to Prednisolone for Treatment of Acute Kidney Injury Secondary to Human Serum Albumin Administration in a Dog

The use of human serum albumin (HSA) is described in dogs receiving critical care. However, despite the high degree of homology, anaphylactic and delayed hypersensitivity reactions are reported. Delayed type III hypersensitivity reactions can lead to glomerulonephritis and acute kidney injury (AKI). Undiluted 20% HSA was administered to a 4.8 yr old intact male Labrador Retriever with severe hypoalbuminemia, following surgical management of septic peritonitis of gastrointestinal origin. Nineteen days after HSA administration, the dog developed peracute high magnitude renal proteinuria and AKI. Rapid immunosuppression, using a combination of prednisolone and mycophenolate mofetil, resulted in full resolution of AKI, hypoalbuminemia, and proteinuria. Addition of mycophenolate mofetil may have resulted in the first documented case of full renal recovery from hypersensitivity-induced AKI caused by HSA administration.

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.

Evaluation of the children with C3 glomerulopathy

C3 glomerulopathy (C3G) is a clinical spectrum that presents with a variety of symptoms, ranging from a mild disease with asymptomatic microhematuria and/or proteinuria to severe disease with nephritic or nephrotic syndrome and renal impairment. Herein, we aim to document the clinical and laboratory findings, response to immunosuppressive and supportive treatment and prognosis of the children with C3G. We retrospectively reviewed the medical records of patients diagnosed with membranoproliferative glomerulonephritis (MPGN). Kidney biopsy materials were reexamined for the diagnosis of C3G. The inclusion criteria for C3G are the dominant C3 staining with or without scanty immunoglobulins (Ig) deposition on immuno- fluorescence (IF) and MPGN patterns on light microscope. Twelve of 69 patients with MPGN were included in the study based on the definition criteria of C3G. Ten of them had only C3 staining and the rest of the patients had both C3 staining and a small amount of IgG/M staining on IF microscopy. One patient was on remission with only ACEI. The rest of the patients used immunosuppressive treatment and two of them needed eculizumab therapy. One of them did not respond to the treatment of eculizumab and progressed to end-stage renal failure. C3G is a disease characterized by a heterogeneous clinical presentation and outcome. Because of this broad spectrum of disease, treatment may vary widely. We think that complement-targeting therapy with eculizumab should be an alternative option for refractory cases, especially in the early stage of disease, if they did not respond to immunosuppressive treatment.

C3-glomerulonephritis in New Zealand - a case series

Background

C3-glomerulonephritis can lead to progressive renal impairment from complement-mediated glomerular injury. Incidence and outcomes of C3-glomerulonephritis are not known in the New Zealand population.

Methods

We reviewed all cases of C3-glomerulonephritis from the past 10 years at a tertiary referral centre in New Zealand. Descriptive information on baseline characteristics and clinical outcomes was collected.

Results

Twenty-six patients were included (16 men; mean ± SD age 44 ± 25 years) with a median follow-up of 30 months. Disease incidence was 1.3 cases per million individuals, of which 42% were Pacific Islanders. Most patients presented with renal impairment, with a median (IQR) creatinine at diagnosis of 210 (146–300) μmol/L, and 11 (42%) patients presented with nephrotic syndrome. Seven (27%) patients progressed to end stage renal disease and 2 (8%) had died. End stage renal disease occurred in 20% of patients treated with immunosuppression and in 50% of those not treated. Complete remission was seen in 25% of patients treated with some form of immunosuppression and in 17% of those not treated.

Conclusions

Our results are consistent with previous descriptions of C3-glomerulonephritis. There was a suggestion of better clinical outcomes in patients treated with immunosuppression. There was a higher disease incidence in Pacific Islanders, which may indicate an underlying susceptibility to complement dysfunction in this population.

Recurrent Glomerulonephritis after Renal Transplantation: The Clinical Problem

Glomerulonephritis (GN) continues to be one of the main causes of end-stage kidney disease (ESKD) with an incidence rating from 10.5% to 38.2%. Therefore, recurrent GN, previously considered to be a minor contributor to graft loss, is the third most common cause of graft failure 10 years after renal transplantation. However, the incidence, pathogenesis, and natural course of recurrences are still not completely understood. This review focuses on the most frequent diseases that recur after renal transplantation, analyzing rate of recurrence, epidemiology and risk factors, pathogenesis and bimolecular mechanisms, clinical presentation, diagnosis, and therapy, taking into consideration the limited data available in the literature. First of all, the risk for recurrence depends on the type of glomerulonephritis. For example, recipient patients with anti-glomerular basement membrane (GBM) disease present recurrence rarely, but often exhibit rapid graft loss. On the other hand, recipient patients with C3 glomerulonephritis present recurrence in more than 50% of cases, although the disease is generally slowly progressive. It should not be forgotten that every condition that can lead to chronic graft dysfunction should be considered in the differential diagnosis of recurrence. Therefore, a complete workup of renal biopsy, including light, immunofluorescence and electron microscopy study, is essential to provide the diagnosis, excluding alternative diagnosis that may require different treatment. We will examine in detail the biomolecular mechanisms of both native and transplanted kidney diseases, monitoring the risk of recurrence and optimizing the available treatment options.

Outcome of C3 glomerulopathy patients: largest single-centre experience from South Asia

BACKGROUND

C3 glomerulopathy (C3G) is related to dysfunction of alternative complement pathway (ACP) because of its hyperactivation. Triggering factors and genetic profile are likely to be different in developing countries as compared to the Western world. Data regarding C3G from South Asian is scanty.

STUDY DESIGN

In the present study, 115 patients of C3G from 2012 to 2017 were analyzed. Clinical details were reviewed; serological levels of C3, C4, complement factor H or B and autoantibody testing was done by nephelometry/ELISA. Limited genetics workup for CFH and CFHR5 genes was done.

RESULTS

The prevalence of C3G was 1.52%. There was no difference in demographic and histopathologic profiles of C3G patients. Majority of patients had low functional assay and C3 levels. C3 nephritic factor was present in 47.5% of DDD and 38.6% of C3GN. Autoantibodies to CFH were present more often in the patients of C3GN (29.5%) than DDD (12.5%). Autoantibodies to CFB were equally common in both groups. Past history of infections was present in one-third patients and monoclonal paraproteins were present only in two patients. No pathogenic variants were noted in CFH/CFHR5 gene. On follow-up (3.2 + 1.6 years), complete and partial remission was achieved in one-fourth patients and 26% had resistance disease. About 40% progressed to ESRD and 18 underwent renal transplantation of which nine had a post-transplant recurrence.

CONCLUSIONS

Indian cohort had some differences in the immunological and genetic profile when compared to the Western literature; most significant was the absence of monoclonal immunoglobulins as a trigger for C3G.

Poor allograft outcome in Indian patients with post-transplant C3 glomerulopathy

Background

Complement 3 glomerulopathy (C3G) results from dysfunction of the alternative complement pathway (ACP). No data are available on post-transplant C3G in South Asia.

Methods

In this study, renal allograft biopsies of C3G patients performed from 2012 to 2017 were analysed for ACP functional assay (APFA), serum complement levels, complement factor H (CFH), complement factor B (CFB) and autoantibodies to CFH and CFB. Limited genetic screening for CFH/CFHR5 genes was carried out. All study patients were also followed up.

Results

A total of 21 cases of C3G were included, of which 11 had native C3G disease (that is, recurrent C3G). Of these 11 recurrent cases, 7 presented with allograft dysfunction and 4 with proteinuria and renal dysfunction. Early post-transplant recurrence (<1 month) was noted in six patients, whereas recurrence in five patients occurred within 8–17 months of transplant. Biopsies showed mild focal mesangial expansion with or without endocapillary proliferation and thrombotic microangiopathy. Rejection was also noted in six patients. APFA/C3 levels were low in all cases. Serum CFH levels were low [dense deposit disease (DDD), 44%; C3 glomerulonephritis (C3GN), 25%], whereas CFB levels were normal. Autoantibodies to CFH, CFB and C3 nephritic factor were present in 11, 0 and 44% of DDD cases, respectively, and in 17, 17 and 33% of C3GN cases, respectively. Genetic analysis revealed only non-pathogenic CFH gene variants (93%). No novel mutation was found. At follow-up (140 months), stable graft was noted in 28% of cases, progressive renal failure in 19%, graft loss in 34%, and 19% of patients died.

Conclusion

Post-transplant C3G can present with graft dysfunction and/or proteinuria. Subtle histological findings demand careful interpretation of immunofluorescence results. Autoantibodies to complement pathway regulatory proteins are common, and no novel mutation has been found from limited genetic workup. Clinical outcome is poor.

Clinical course and outcome after kidney transplantation in patients with C3 glomerulonephritis due to CFHR5 nephropathy

BACKGROUND

Complement factor H-related protein 5 (CFHR5) nephropathy is an inherited renal disease characterized by microscopic and synpharyngitic macroscopic haematuria, C3 glomerulonephritis and renal failure. It is caused by an internal duplication of exons 2-3 within the CFHR5 gene resulting in dysregulation of the alternative complement pathway. The clinical characteristics and outcomes of transplanted patients with this rare familial nephropathy remain unknown.

METHODS

This is a retrospective case series study of 17 kidney transplant patients with the established founder mutation, followed-up over a span of 30 years.

RESULTS

The mean (±SD) age of patients at the time of the study and at transplantation was 58.6 ± 9.9 and 46.7 ± 8.8 years, respectively. The 10- and 15-year patient survival rates were 100 and 77.8%, respectively. Proteinuria was present in 33.3% and microscopic haematuria in 58.3% of patients with a functional graft. Serum complement levels were normal in all. 'Confirmed' and 'likely' recurrence of CFHR5 nephropathy were 16.6 and 52.9%, respectively; however, 76.5% of patients had a functional graft after a median of 120 months post-transplantation. Total recurrence was not associated with graft loss (P = 0.171), but was associated with the presence of microscopic haematuria (P = 0.001) and proteinuria (P = 0.018). Graft loss was associated with the presence of proteinuria (P = 0.025).

CONCLUSIONS

We describe for the first time the clinical characteristics and outcome of patients with CFHR5 nephropathy post-transplantation. Despite the recurrence of CFHR5 nephropathy, we provide evidence for a long-term favourable outcome and support the continued provision of kidney transplantation as a renal replacement option in patients with CFHR5 nephropathy.

Association Between Promoter Polymorphisms in CD46 and CD59 in Kidney Donors and Transplant Outcome

Complement regulating proteins, including CD46, CD55, and CD59, protect cells against self-damage. Because of their expression on the donor endothelium, they are hypothesized to be involved in accommodation. Polymorphisms in their promoter regions may affect their expression. The aim of this study was to investigate if donor polymorphisms in complement regulating proteins influence kidney transplant outcomes. We included 306 kidney transplantations between 2005 and 2010. Five polymorphisms in the promoters of CD46, CD55, and CD59 were genotyped. A CD59 promoter polymorphism (rs147788946) in donors was associated with a lower 1-year rejection-free survival [adjusted hazard ratio (aHR) 2.18, 95% CI 1.12–4.24] and a trend toward impaired 5-year graft survival (p = 0.08). Patients receiving a kidney with at least one G allele for the CD46 promoter polymorphism rs2796267 (A/G) showed a lower rejection-free survival, though this became borderline significant after adjustment for potential confounders (aHR 1.87, 95% CI 0.96–3.65). A second CD46 promoter polymorphism (rs2796268, A/G), was also associated with a lower freedom from acute rejection in the presence of at least one G allele (aHR 1.95, 95% CI 1.03–3.68). Finally, the combined presence of both favorable genotypes of rs2796267 and rs147788946 had an additional protective effect both on acute rejection (p = 0.006) and graft survival (p = 0.03). These findings could help to identify patients who could benefit from intensified immunosuppressive therapy or novel complement inhibitory therapeutics.

Precision Transplant Medicine: Biomarkers to the Rescue

The concept that individuals with the same disease and a similar clinical presentation may have very different outcomes and need very different therapies is not novel. With the development of many innovative tools derived from the omics technologies, transplant medicine is slowly entering the era of precision medicine. Biomarkers are the cornerstone of precision medicine, which aims to integrate biomarkers with traditional clinical information and tailor medical care to achieve the best outcome for an individual patient. Here, we discuss the basic concepts of precision medicine and biomarkers, with a specific focus on progress in renal transplantation. We delineate the different types of biomarkers and provide a general assessment of the current applications and shortcomings of previously proposed biomarkers. We also outline the potential of precision medicine in transplantation. Moving toward precision medicine in the field of transplantation will require transplant physicians to embrace the increased complexity and expanded decision algorithms and therapeutic options that are associated with improved disease nosology.

Immunosuppressive Treatment in C3 Glomerulopathy: Is it Really Effective?

BACKGROUND

C3 glomerulopathy (C3GP) is a recently identified and described disease that has a high risk of progressing into end-stage renal disease. We aimed to evaluate the effects of various immunosuppressive regimens on C3GP progression because there are conflicting data on the treatment modalities.

METHODS

In this retrospective study of 66 patients with C3GP, 27 patients received mycophenolate mofetil (MMF)-based treatment, 23 received non-MMF-based treatment (prednisolone or cyclophosphamide), and 16 received conservative care. The study groups were compared with each other with specific focus on primary outcomes defined as (1) kidney failure and (2) estimated glomerular filtration rate (eGFR) decline ≥50% from the baseline value.

RESULTS

Overall, 17 (25.8%) patients reached the primary outcome after a median period of 28 months. The number of patients who reached the primary outcome were similar among the study groups (MMF-based: 8/27 [29.6%], non-MMF-based: 4/23 [17.4%], and conservative care: 5/16 [31.3%], p = 0.520). In the Cox regression analysis, age (HR 0.912, p = 0.006), eGFR (HR 0.945, p = 0.001), and proteinuria levels (HR 1.418, p = 0.015) at the time of biopsy, percentage of crescentic (HR 1.035, p = 0.001) and sclerotic glomeruli (HR 1.041, p = 0.006), severity of interstitial fibrosis (HR 1.981, p = 0.048), as well as no remission of proteinuria (HR 2.418, p = 0.002) predicted the primary outcome.

CONCLUSION

Although patients receiving immunosuppressive treatments had higher proteinuria and lower serum albumin at baseline, there were no differences between these patients and those receiving conservative care alone in proteinuria remission or in the decline of renal function. Younger age, higher proteinuria, lower eGFR, and the presence of crescentic and sclerotic glomeruli, severity of interstitial fibrosis, and no remission of proteinuria predicted the progression of kidney disease.

Complement related kidney diseases: Recurrence after transplantation

The recurrence of renal disease after renal transplantation is becoming one of the main causes of graft loss after kidney transplantation. This principally concerns some of the original diseases as the atypical hemolytic uremic syndrome (HUS), the membranoproliferative glomerulonephritis (MPGN), in particular the MPGN now called C3 glomerulopathy. Both this groups of renal diseases are characterized by congenital (genetic) or acquired (auto-antibodies) modifications of the alternative pathway of complement. These abnormalities often remain after transplantation because they are constitutional and poorly influenced by the immunosuppression. This fact justifies the high recurrence rate of these diseases. Early diagnosis of recurrence is essential for an optimal therapeutically approach, whenever possible. Patients affected by end stage renal disease due to C3 glomerulopathies or to atypical HUS, may be transplanted with extreme caution. Living donor donation from relatives is not recommended because members of the same family may be affected by the same gene mutation. Different therapeutically approaches have been attempted either for recurrence prevention and treatment. The most promising approach is represented by complement inhibitors. Eculizumab, a monoclonal antibody against C5 convertase is the most promising drug, even if to date is not known how long the therapy should be continued and which are the best dosing. These facts face the high costs of the treatment. Eculizumab resistant patients have been described. They could benefit by a C3 convertase inhibitor, but this class of drugs is by now the object of randomized controlled trials.

Likely Recurrence of C3 Glomerulonephritis in Kidney Transplantation: An Entity to Bear in Mind: Case Report

BACKGROUND

C3 glomerulonephritis (C3GN) is an unusual entity that is caused by dysregulation and hyperactivity of the alternative complement pathway. Renal biopsy immunofluorescence study shows C3 deposits with absence of immunoglobulins and markers of the classical complement pathway. More than 50% of cases develop end-stage renal disease. Less well-known is the course of C3GN after kidney transplantation.

CASE REPORT

We present the case of a 60-year-old woman with chronic kidney disease secondary to chronic glomerulonephritis of unknown origin who received a kidney transplant. Two years later, she presented worsening renal function with non-nephrotic proteinuria and microhematuria. Complement testing revealed low serum levels of C3. Kidney biopsy showed alterations compatible with C3GN that we interpreted as a relapse of the underlying disease.

Reclassification of membranoproliferative glomerulonephritis: Identification of a new GN: C3GN

This review revises the reclassification of the membranoproliferative glomerulonephritis (MPGN) after the consensus conference that by 2015 reclassified all the glomerulonephritis basing on etiology and pathogenesis, instead of the histomorphological aspects. After reclassification, two types of MPGN are to date recognized: The immunocomplexes mediated MPGN and the complement mediated MPGN. The latter type is more extensively described in the review either because several of these entities are completely new or because the improved knowledge of the complement cascade allowed for new diagnostic and therapeutic approaches. Overall the complement mediated MPGN are related to acquired or genetic cause. The presence of circulating auto antibodies is the principal acquired cause. Genetic wide association studies and family studies allowed to recognize genetic mutations of different types as causes of the complement dysregulation. The complement cascade is a complex phenomenon and activating factors and regulating factors should be distinguished. Genetic mutations causing abnormalities either in activating or in regulating factors have been described. The diagnosis of the complement mediated MPGN requires a complete study of all these different complement factors. As a consequence, new therapeutic approaches are becoming available. Indeed, in addition to a nonspecific treatment and to the immunosuppression that has the aim to block the auto antibodies production, the specific inhibition of complement activation is relatively new and may act either blocking the C5 convertase or the C3 convertase. The drugs acting on C3 convertase are still in different phases of clinical development and might represent drugs for the future. Overall the authors consider that one of the principal problems in finding new types of drugs are both the rarity of the disease and the consequent poor interest in the marketing and the lack of large international cooperative studies.

Acute and Chronic Allograft Dysfunction in Kidney Transplant Recipients

Allograft dysfunction after a kidney transplant is often clinically asymptomatic and is usually detected as an increase in serum creatinine level with corresponding decrease in glomerular filtration rate. The diagnostic evaluation may include blood tests, urinalysis, transplant ultrasonography, radionuclide imaging, and allograft biopsy. Whether it occurs early or later after transplant, allograft dysfunction requires prompt evaluation to determine its cause and subsequent management. Acute rejection, medication toxicity from calcineurin inhibitors, and BK virus nephropathy can occur early or later. Other later causes include transplant glomerulopathy, recurrent glomerulonephritis, and renal artery stenosis.