Prognostic value of complement serum C3 level and glomerular C3 deposits in anti-glomerular basement membrane disease

Background and objectives

Activation of the complement system is involved in the pathogenesis of anti-glomerular basement membrane (anti-GBM) disease. Glomerular deposits of complement 3 (C3) are often detected on kidney biopsies. The primary objective of this study was to analyze the prognostic value of the serum C3 level and the presence of C3 glomerular deposits in patients with anti-GBM disease.

Methods

We conducted a retrospective cohort study of 150 single-positive patients with anti-GBM disease diagnosed between 1997 and 2017. Patients were categorized according to the serum C3 level (forming a low C3 (C3<1.23 g/L) and a high C3 (C3≥1.23 g/L) groups) and positivity for C3 glomerular staining (forming the C3+ and C3- groups). The main outcomes were kidney survival and patient survival.

Results

Of the 150 patients included, 89 (65%) were men. The median [interquartile range (IQR)] age was 45 [26-64]. At diagnosis, kidney involvement was characterized by a median [IQR] peak serum creatinine (SCr) level of 578 [298-977] µmol/L, and 106 (71%) patients required dialysis. Patients in the low C3 group (72 patients) had more severe kidney disease at presentation, as characterized by higher prevalences of oligoanuria, peak SCr ≥500 µmol/L (69%, vs. 53% in the high C3 group; p=0.03), nephrotic syndrome (42%, vs. 24%, respectively; p=0.02) and fibrous forms on the kidney biopsy (21%, vs. 8%, respectively; p=0.04). Similarly, we observed a negative association between the presence of C3 glomerular deposits (in 52 (41%) patients) and the prevalence of cellular forms (83%, vs. 58% in the C3- group; p=0.003) and acute tubulo-interstitial lesions (60%, vs. 36% in the C3- group; p=0.007). When considering patients not on dialysis at diagnosis, the kidney survival rate at 12 months was poorer in the C3+ group (50% [25-76], vs. 91% [78-100] in the C3- group; p=0.01), with a hazard ratio [95% confidence interval] of 5.71 [1.13-28.85] (p=0.04, after adjusting for SCr).

Conclusion

In patients with anti-GBM disease, a low serum C3 level and the presence of C3 glomerular deposits were associated with more severe disease and histological kidney involvement at diagnosis. In patients not on dialysis at diagnosis, the presence of C3 deposits was associated with worse kidney survival.

Early Renal Recovery after the First Flare of Pauci-Immune Glomerulonephritis

INTRODUCTION

Renal involvement is a severe manifestation of antineutrophil cytoplasmic antibody-associated vasculitis. Patients often progress to end-stage renal disease. The potential for renal recovery after the first flare has seldom been studied. Our objectives were to describe the evolution of the estimated glomerular filtration rate (eGFR) and identify factors associated with the change in the eGFR between diagnosis and the follow-up at 3 months (ΔeGFRM0-M3).

METHODS

This was a retrospective study over the period 2003-2018 of incident patients in the Nord-Pas-de-Calais (France). The primary outcome was the ΔeGFRM0-M3.

RESULTS

One hundred and seventy-seven patients were included. The eGFR at 3 months was significantly higher than at diagnosis (mean ± standard deviation, 40 ± 24 vs. 28 ± 26 mL/min/1.73 m2, p < 0.001), with a ΔeGFRM0-M3 of 12 ± 19 mL/min/1.73 m2. The eGFR at 12 months was higher than at 3 months (44 ± 13 vs. 40 ± 24 mL/min/1.73 m2, p = 0.003). The factors significantly associated with the ΔeGFRM0-M3 in multivariate analysis were the percentage of cellular crescents and neurological involvement. The mean increase in the eGFR was 2.90 ± 0.06 mL/min/1.73 m2 for every 10-point gain in the percentage of cellular crescents.

CONCLUSIONS

Early renal recovery after the first flare of pauci-immune glomerulonephritis occurred mainly in the first 3 months of treatment. The percentage of cellular crescents was the main independent predictor of early renal recovery.

MO282EARLY RENAL RECOVERY AFTER A FIRST FLARE OF PAUCI IMMUNE GLOMERULONEPHRITIS

Background and Aims

Renal involvement is a severe manifestation of ANCA-associated vasculitis. Patients often progress to end-stage renal disease. The potential for renal recovery after a first flare has seldom been studied. Our objectives were to describe the evolution of the estimated glomerular filtration rate (eGFR) and identify factors associated with the change in eGFR between diagnosis and follow-up at 3 months (ΔeGFRM0–M3) in a cohort of patients with a first flare of pauci-immune glomerulonephritis.

Methods

This was a retrospective study over the period 2003–2018 of incident patients in the Nord-Pas-de-Calais (France). Patients were recruited if they had a first histologically-proven flare of pauci immune glomerulonephritis with at least 1 year of follow up. Kidney function was estimated with MDRD-equation and analysed at diagnosis, 3rd, 6th and 12th months. The primary outcome was ΔeGFRM0–M3. Factors evaluated were histological (Berden classification, interstitial fibrosis, percentage of crescents), clinical (extra-renal manifestations, sex, age) or biological (severity of acute kidney injury, dialysis, ANCA subtype).

Results

One hundred and seventy-seven patients were included. The eGFR at 3 months was significantly higher than at diagnosis (mean ± standard deviation, 40 ± 24 vs 28 ± 26 ml/min/1.73 m2, p &lt; 0.001), with a ΔeGFRM0–M3 of 12 ± 19 ml/min/1.73 m2. The eGFR at 12 months was higher than at 3 months (44 ± 13 vs 40 ± 24 ml/min/1.73m2, p = 0.003). The factors significantly associated with ΔeGFRM0–M3 in univariate analysis were: sclerotic class according to Berden classification, percentage of interstitial fibrosis, percentage of cellular crescents, acute tubular necrosis, neurological involvement. The factors associated with ΔeGFRM0–M3 in multivariate analysis were the percentage of cellular crescents and neurological involvement. The mean increase in eGFR was 2.90 ± 0.06 ml/min/1.73m2 for every 10-point gain in the percentage of cellular crescents. ΔeGFRM0–M3 was not associated with the risks of end-stage renal disease or death in long-term follow-up.

Conclusions

Early renal recovery after a first flare of pauci-immune glomerulonephritis occurred mainly in the first three months of treatment. The percentage of cellular crescents was the main independent predictor of early renal recovery.

[Kidney disease care for the elderly]

In our aging population, kidney disease management needs to take into account the frailty of the elderly. Standardized geriatric assessments can be proposed to help clinicians apprehend this dimension in their daily practice. These tools allow to better identify frail patients and offer them more personalized and harmless treatments. This article aims to focus on the kidney diseases commonly observed in elderly patients and analyze their specific nephrogeriatric care modalities. It should be noticed that all known kidney diseases can be also observed in the elderly, most often with a quite similar clinical presentation. This review is thus focused on the diseases most frequently and most specifically observed in elderly patients (except for monoclonal gammopathy associated nephropathies, out of the scope of this work), as well as the peculiarities of old age nephrological care.

Differential Determinants of Tubular Phosphate Reabsorption: Insights on Renal Excretion of Phosphates in Kidney Disease

We assessed the tubular reabsorption of phosphate (TRP) and maximal renal threshold for phosphate reabsorption to glomerular filtration rate (TmPi/GFR) and their determinants in 64 stages 2-4 chronic kidney disease (CKD) patients in order to define the early changes in phosphate metabolism in CKD. In multivariable analysis, TmPi/GFR correlates were estimated GFR (eGFR), intact parathyroid hormone (iPTH), and hemoglobin (R2 = 0.417), while TRP correlates were eGFR, iPTH, 24-h phosphaturia, and calcitriol (R2 = 0.72). This suggests that TmPi/GFR and TRP, respectively, assess hemoglobin-phosphate and bowel-kidney phosphate regulation axis. Iron supplementation based on TmPi/GFR or earlier phosphate restriction based on TRP should be investigated in view of modifying clinical outcomes in CKD.

[Renal malakoplakia: an underestimate cause of renal failure]

Malakoplakia is an inflammatory granulomatous disease induced by defective phagocytic activity of macrophage. Malakoplakia is histologically characterized by the presence of Michaelis-Gutmann bodies in macrophages. Although not uncommon in the genito-urinary tract, isolated malakoplakia of the kidney is rarely found. Its main clinical presentation associates acute renal failure and acute pyelonephritis. The clue for diagnosis of renal malakoplakia is based on renal biopsy showing Michaelis-Gutmann bodies. Establishing the diagnosis of renal malakoplakia is essential as it determines the choice of antibiotics and duration of treatment. Prognosis remains poor, leading frequently to chronic renal failure. In this paper, we report four cases of renal malakoplakia and discuss clinical presentation, biological and pathological features, treatment and prognosis of this disease.

[Cognitive impairment and chronic kidney disease: which links?]

Ageing of the population leads to an increase of cognitive disorders and chronic renal failure incidence. Compared to the general population, prevalence of cognitive impairment is more important in renal failure patients, especially in dialyzed patients. No direct link has been established between renal failure and cognitive impairment. The care of older and older patients and the high frequency of vascular risk factors, in particular hypertension and diabetes, partially explain the prevalence of vascular dementia and Alzheimer disease in this population. Other factors as the anemia, phosphocalcic metabolism disorders facilitate the cognitive impairment. The present work reviews the links existing between chronic renal failure and cognitive impairment.

Soluble receptor for advanced glycation end products: a new biomarker in diagnosis and prognosis of chronic inflammatory diseases

The formation of advanced glycation end products (AGEs) is a result of the non-enzymatic reaction between sugars and free amino groups of proteins. AGEs, through interacting with their specific receptor for AGEs (RAGE), result in activation of pro-inflammatory states and are involved in numerous pathologic situations. The soluble form of RAGE (sRAGE) is able to act as a decoy to avoid interaction of RAGE with its pro-inflammatory ligands (AGEs, HMGB1, S100 proteins). sRAGE levels have been found to be decreased in chronic inflammatory diseases including atherosclerosis, diabetes, renal failure and the aging process. The use of measuring circulating sRAGEs may prove to be a valuable vascular biomarker and in this review, we describe the implications of sRAGE in inflammation and propose that this molecule may represent a future therapeutic target in chronic inflammatory diseases.

Peritoneal aging during PD: implication of RAGE, the receptor for AGEs

During last years, the number of patients who have been continuously treated by peritoneal dialysis (PD) for over 5 or 10 years has markedly increased. Sclerosing syndromes and membrane failure are the most common complications that are now currently observed in long-term PD patients. Exposure to conventional PD fluids (PDFs) with poor biocompatibility induces a kind of <<chemical peritonitis>> in response of bad <<biotolerance>>. Theperitoneal fibroblasts, mesothelial cells and especially endothelial cells function as a filtration barrier, but also control intraperitoneal inflammation as well as leukocytes and macrophages.Peritoneal exposure to conventional poorly biocompatible PDFs which combine non-physiological pH, high glucose concentrations,and high levels of glucose degradation products (GDPs), is associated with an accelerated peritoneal aging. Heat sterilization of PDFs induces the formation of GDPs which are involved in the formation of advanced glycation end-products (AGEs).Glucose, GDPs and AGEs participate to the peritoneal membrane failure and aging. AGEs via RAGE (receptor for AGEs) are involved in human peritoneal mesothelial cell (HPMC) activation.In the present work, we summarize our previous in vitro works regarding mesothelial RAGE implication in the peritoneal membrane aging. Two periods of aging are distinguished: i) early peritoneal changes related to mesothelial cell activation and loss, ii)late membrane alteration correlated to submesothelial fibrosis and neovascularization.