The AKI-to-CKD Transition: The Role of Uremic Toxins.

After acute kidney injury (AKI), renal function continues to deteriorate in some patients. In a pro-inflammatory and profibrotic environment, the proximal tubules are subject to maladaptive repair. In the AKI-to-CKD transition, impaired recovery from AKI reduces tubular and glomerular filtration and leads to chronic kidney disease (CKD). Reduced kidney secretion capacity is characterized by the plasma accumulation of biologically active molecules, referred to as uremic toxins (UTs). These toxins have a role in the development of neurological, cardiovascular, bone, and renal complications of CKD. However, UTs might also cause CKD as well as be the consequence. Recent studies have shown that these molecules accumulate early in AKI and contribute to the establishment of this pro-inflammatory and profibrotic environment in the kidney. The objective of the present work was to review the mechanisms of UT toxicity that potentially contribute to the AKI-to-CKD transition in each renal compartment.

Rare manifestations of cryoglobulinemic vasculitis: a case report.

Introduction: Cryoglobulinemic vasculitis is a type of small vessel vasculitis diseases that can cause dysfunction in multiple organs. It is characterized by general symptoms, often accompanied by nonspecific cutaneous, articular, neurological, and renal manifestations. Diagnosing cryoglobulinemia through biological testing can be time-consuming and sometimes yields negative results, making diagnosis challenging. There are also other potentially life-threatening complications that can significantly impact prognosis and delay urgent treatment, including digestive manifestations and heart failure. Case presentation: We report the case of a 60-year-old male patient with a medical history of rheumatoid arthritis. He was admitted to the Nephrology Department for investigation of necrotic vascular purpura, acute kidney injury, and pancytopenia. Laboratory tests revealed consumption of the C3 and C4 complement fractions and the presence of mixed-type III cryoglobulinemia. Despite the initiation of the treatment, the patient rapidly developed multiple severe organ failures, including renal, cardiac, respiratory, and finally digestive complications. Acute colic ischemia led to emergency surgery and the patient was transferred to the Intensive Care Unit. Despite surgical intervention and hemodynamic support, the patient experienced multi-visceral organ failure and died two hours after admission. Discussion: Mixed cryoglobulinemia vasculitis may result in rare cases of acute and life-threatening organ damage, such as cardiac or respiratory failure with pulmonary hemorrhage, gastrointestinal ischemia, and neurological disorders. These severe manifestations are associated with a poor prognosis and it is crucial to promptly initiate an aggressive therapeutic strategy.

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.

The Role of Gut-Derived, Protein-Bound Uremic Toxins in the Cardiovascular Complications of Acute Kidney Injury.

Acute kidney injury (AKI) is a frequent disease encountered in the hospital, with a higher incidence in intensive care units. Despite progress in renal replacement therapy, AKI is still associated with early and late complications, especially cardiovascular events and mortality. The role of gut-derived protein-bound uremic toxins (PBUTs) in vascular and cardiac dysfunction has been extensively studied during chronic kidney disease (CKD), in particular, that of indoxyl sulfate (IS), para-cresyl sulfate (PCS), and indole-3-acetic acid (IAA), resulting in both experimental and clinical evidence. PBUTs, which accumulate when the excretory function of the kidneys is impaired, have a deleterious effect on and cause damage to cardiovascular tissues. However, the link between PBUTs and the cardiovascular complications of AKI and the pathophysiological mechanisms potentially involved are unclear. This review aims to summarize available data concerning the participation of PBUTs in the early and late cardiovascular complications of AKI.

Evaluation of Changes Over Time in the Drug Burden and Medication Regimen Complexity in ESRD Patients Before and After Renal Transplantation.

BACKGROUND: Medication regimen complexity (MRC) has not been characterized in detail in patients with end-stage renal disease (ESRD). The objective of the present study was to quantify changes over time in the prescription drug burden and MRC in patients with ESRD (before transplantation, on discharge after kidney transplantation [M0], and 4 months [M4] and 12 months [M12] afterward). METHODS: We retrospectively studied adult patients having undergone kidney transplantation. The number and types of drug prescribed, the pill burden, and the MRC index (MRCI) at 4 different time points (before transplantation, M0, M4, and M12) were extracted from the patients' medical records. MRCI was calculated by adding each drug score (calculated according to its formulation, dosing frequency, and additional instructions concerning administration). Hence, the MRCI took account of all prescription drugs. A logistic regression model was used to identify factors associated with an elevated MRCI at M12. RESULTS: The median (interquartile range) age of the 354 study participants was 52 years (42-62). Respectively 21%, 42%, 53%, and 38% of the patients were taking 10 or more drugs before transplantation and at M0, M4, and M12. At M12, the 3 most frequently prescribed drug classes were immunosuppressants, cardiovascular system drugs, and drugs acting on the alimentary tract and metabolism. The pill burden and MRCI before transplantation were significantly lower (P < 0.001) than at each time point after transplantation. Diabetes and dyslipidemia were independently associated with an elevated MRCI at M12. CONCLUSION: In kidney transplant recipients, the drug burden and MRCI were greater at all time points after transplantation than before transplantation. The impact of the drug burden and MRC on medication adherence and clinical outcomes in these patients requires further evaluation.

Two rapid, accurate liquid chromatography tandem mass spectrometry methods for the quantification of seven uremic toxins: An application for describing their accumulation kinetic profile in a context of acute kidney injury.

Acute kidney injury (AKI) is a frequent, serious complication in critically ill patients. Even if renal replacement therapy is rapidly initiated, AKI may lead to the acute accumulation of metabolic waste products called uremic toxins (UTs). Although the accumulation and effects of UTs have been extensively described in the setting of chronic kidney disease (CKD), few data are available for AKI. A rapid, sensitive, specific method with simple sample preparation is required to facilitate routine blood monitoring of UTs in a context of acute accumulation. We have developed and validated two fast liquid chromatography tandem mass spectrometry methods for the quantification of seven UTs in human serum. The first method (in negative ionization mode) enables the quantification of five UTs (hippuric acid (HA), indoxyl sulfate (IxS), para-cresyl sulfate (pCS), para-cresyl glucuronide (pCG), 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF)). The second method (in positive ionization mode) enables the quantification of two UTs (indole-3-acetic acid (IAA), and trimethylamine N-oxide (TMAO)). Sample preparation consisted of the deproteinization of a small volume of serum (50 µL). The run-times required to assay all the UTs in negative and positive ionization modes were only 2.5 and 2 min, respectively. In order to obtain a reliable, toxin-free matrix for the preparation of calibration standards and quality controls, serum was pretreated with activated charcoal. We used these methods to determine the time course of UT accumulation in eight patients who developed an AKI after cardiac surgery. The calibration curves ranged from 0.1 to 100 µg mL-1 for all the UTs (except for IAA: 0.5 to 100 µg mL-1), and the correlation coefficients were above 0.999 for all. The methods were reproducible, repeatable, and accurate, with all coefficients of variation and biases below 15%. The highest concentrations measured in patients with AKI were lower than those reported in CKD stages 4 and 5 but higher than those observed in patients with no impairment of renal function (particularly for IxS and pCS). Our results also highlighted low accumulation of the other toxins (IAA, HA, TMAO, pCG, and CMPF). The UT concentrations did not rise earlier than that of creatinine; although the return to baseline took longer than for creatinine for some compounds. Lastly, assessment of the time course of UT accumulation as a prognostic marker for AKI (particularly for pCS and IxS) appears to be promising and should be continued in a larger number of patients.

Severe Infection in Anti-Glomerular Basement Membrane Disease: A Retrospective Multicenter French Study.

In patients presenting with anti-glomerular basement membrane (GBM) disease with advanced isolated kidney involvement, the benefit of intensive therapy remains controversial due to adverse events, particularly infection. We aim to describe the burden of severe infections (SI) (requiring hospitalization or intravenous antibiotics) and identify predictive factors of SI in a large cohort of patients with anti-GBM disease. Among the 201 patients (median [IQR] age, 53 [30-71] years) included, 74 had pulmonary involvement and 127 isolated glomerulonephritis. A total of 161 SI occurred in 116 patients during the first year after diagnosis. These infections occurred during the early stage of care (median [IQR] time, 13 [8-19] days after diagnosis) with mainly pulmonary (45%), catheter-associated bacteremia (22%) and urinary tract (21%) infections. In multivariable analysis, positive ANCA (HR [95\% CI] 1.62 [1.07--2.44]; p = 0.02) and age at diagnosis (HR [95% CI] 1.10 [1.00-1.21]; p = 0.047) remained independently associated with SI. Age-adjusted severe infection during the first three months was associated with an increased three-year mortality rate (HR [95% CI] 3.13 [1.24-7.88]; p = 0.01). Thus, SI is a common early complication in anti-GBM disease, particularly in the elderly and those with positive anti-neutrophil cytoplasmic antibodies (ANCA). No significant association was observed between immunosuppressive strategy and occurrence of SI.