Risk factors associated with immune checkpoint inhibitor-induced acute kidney injury compared with other immune-related adverse events: a case-control study.

Background: Immune checkpoint inhibitors (ICIs) foster anti-cancer immune responses. Their efficacy comes at the cost of immune-related adverse events (IRAEs). The latter affects various organs, including kidneys, mostly as acute tubulointerstitial nephritis, the pathophysiology of which remains unclear. We conducted a multicentre case-control study to compare the characteristics of patients with renal IRAEs (ICI-AKI) with those of patients diagnosed with other IRAEs. Methods: We queried the French pharmacovigilance database for all adverse events involving ICIs. Reports were classified as ICI-AKI or extrarenal IRAE. For each ICI-AKI report, four reports of extrarenal IRAEs were randomly included (control group, 4:1 ratio). Variables showing an association with a P < 0.05 were included as covariates in a multivariate analysis. Results: Therefore, 167 ICI-AKI reports were compared with 668 extrarenal IRAEs. At least one concomitant extrarenal IRAE was mentioned in 44.3% of ICI-AKI reports. Patients with ICI-AKI were significantly older than patients with extrarenal IRAEs (69.1 versus 64.6 years; P = 0.0135), and chronic kidney disease was significantly more prevalent (12.0% versus 3.3%; P = 0.0125). Patients with ICI-AKI were significantly more likely to be treated with fluindione [adjusted odds ratio (OR) 6.53, 95% confidence interval (95% CI) 2.21-19.31; P = 0.0007], a non-steroidal anti-inflammatory drug (NSAID, OR 3.18, 95% CI 1.07-9.4; P = 0.0368) or a proton-pump inhibitor (PPI, OR 2.18, 95% CI 1.42-3.34; P = 0.0004). Conclusion: This study is limited by a lack of data, preventing confirmation of numerous reports therefore not included in the analysis. We are unable to draw definite pathophysiological conclusions from our data. Nonetheless, we suggest that ICIs may be a 'second-hit' that precipitates acute kidney injury caused by another concomitant drug (fluindione, NSAID or PPI).

New Strategies for Volume Control in Patients with Diabetes Mellitus, a Narrative Review.

Sodium is reabsorbed all along the renal tubules. The positive impacts of sodium-glucose cotransporter-2 inhibitors (SGLT2i), angiotensin receptor neprilysin inhibitor (ARNI) and mineralocorticoid receptor antagonists (MRA) on hard renal and/or cardiac endpoints calls for the role of diuretics in nephroprotection and cardioprotection in patients with diabetes mellitus to be reviewed. Here, we review: (a) the mechanisms of action of the available natriuretics; (b) the physiological adaptations to chronic loop diuretic usage that lead to increased sodium reabsorption in the proximal and distal convoluted tubules; (c) the physiology of sodium retention in patients with diabetes mellitus; and (d) the mechanisms of aldosterone breakthrough. We show the rationale for combined diuretics to target not only the loop of Henle, but also the proximal and distal convoluted tubules. Indeed, higher residual proteinuria in patients treated with renin-angiotensin-aldosterone system (RAAS) blockers portends poorer renal and cardiovascular outcomes. Diuretics are known to optimize the reduction of proteinuria, in addition to RAAS blockers, but may favor aldosterone breakthrough in the absence of MRA. The aim of our study is to support a combined diuretics strategy to improve the management of patients with diabetes mellitus and chronic kidney disease or heart failure.

Arterial Calcifications in Patients with Liver Cirrhosis Are Linked to Hepatic Deficiency of Pyrophosphate Production Restored by Liver Transplantation.

Liver fibrosis is associated with arterial calcification (AC). Since the liver is a source of inorganic pyrophosphate (PPi), an anti-calcifying compound, we investigated the relationship between plasma PPi ([PPi]pl), liver fibrosis, liver function, AC, and the hepatic expression of genes regulating PPi homeostasis. To that aim, we compared [PPi]pl before liver transplantation (LT) and 3 months after LT. We also assessed the expression of four key regulators of PPi in liver tissues and established correlations between AC, and scores of liver fibrosis and liver failure in these patients. LT candidates with various liver diseases were included. AC scores were assessed in coronary arteries, abdominal aorta, and aortic valves. Liver fibrosis was evaluated on liver biopsies and from non-invasive tests (FIB-4 and APRI scores). Liver functions were assessed by measuring serum albumin, ALBI, MELD, and Pugh−Child scores. An enzymatic assay was used to dose [PPi]pl. A group of patients without liver alterations from a previous cohort provided a control group. Gene expression assays were performed with mRNA extracted from liver biopsies and compared between LT recipients and the control individuals. [PPi]pl negatively correlated with APRI (r = −0.57, p = 0.001, n = 29) and FIB-4 (r = −0.47, p = 0.006, n = 29) but not with interstitial fibrosis index from liver biopsies (r = 0.07, p = 0.40, n = 16). Serum albumin positively correlated with [PPi]pl (r = 0.71; p < 0.0001, n = 20). ALBI, MELD, and Pugh−Child scores correlated negatively with [PPi]pl (r = −0.60, p = 0.0005; r = −0.56, p = 0.002; r = −0.41, p = 0.02, respectively, with n = 20). Liver fibrosis assessed on liver biopsies by FIB-4 and by APRI positively correlated with coronary AC (r = 0.51, p = 0.02, n = 16; r = 0.58, p = 0.009, n = 20; r = 0.41, p = 0.04, n = 20, respectively) and with abdominal aorta AC (r = 0.50, p = 0.02, n = 16; r = 0.67, p = 0.002, n = 20; r = 0.61, p = 0.04, n = 20, respectively). FIB-4 also positively correlated with aortic valve calcification (r = 0.40, p = 0.046, n = 20). The key regulator genes of PPi production in liver were lower in patients undergoing liver transplantation as compared to controls. Three months after surgery, serum albumin levels were restored to physiological levels (40 [37−44] vs. 35 [30−40], p = 0.009) and [PPi]pl was normalized (1.40 [1.07−1.86] vs. 0.68 [0.53−0.80] µmol/L, p = 0.0005, n = 12). Liver failure and/or fibrosis correlated with AC in several arterial beds and were associated with low plasma PPi and dysregulation of key proteins involved in PPi homeostasis. Liver transplantation normalized these parameters.

Relationships between Plasma Pyrophosphate, Vascular Calcification and Clinical Severity in Patients Affected by Pseudoxanthoma Elasticum.

Pseudoxanthoma elasticum (PXE; OMIM 264800) is an autosomal recessive metabolic disorder characterized by progressive calcification in the skin, the Bruch's membrane, and the vasculature. Calcification in PXE results from a low level of circulating pyrophosphate (PPi) caused by ABCC6 deficiency. In this study, we used a cohort of 107 PXE patients to determine the pathophysiological relationship between plasma PPi, coronary calcification (CAC), lower limbs arterial calcification (LLAC), and disease severity. Overall, our data showed a deficit in plasma PPi in PXE patients compared to controls. Remarkably, affected females showed higher PPi levels than males, but a lower LLAC. There was a strong correlation between age and PPi in PXE patients (r = 0.423, p < 0.0001) but not in controls (r = 0.059, p = 0.828). A weak correlation was found between PPi and CAC (r = 0.266, p < 0.02); however, there was no statistically significant connection with LLAC (r = 0.068, p = 0.518) or a severity score (r = 0.077, p = 0.429). Surprisingly, we found no significant correlation between plasma alkaline phosphatase activity and PPi (r = 0.113, p = 0.252) or between a 10-year cardiovascular risk score and all other variables. Multivariate analysis confirmed that LLAC and CAC were strongly dependent on age, but not on PPi. Our data showed that arterial calcification is only weakly linked to circulating PPi levels and that time (i.e., age) appears to be the major determinant of disease severity and calcification in PXE. These data are important to better understand the natural history of this disease but also for the follow-up and management of patients, and the design of future clinical trials. Our results also show that PPi is not a good biomarker for the evaluation of disease severity and progression.

Case Report: Severe Hypercalcemia Following Vitamin D Intoxication in an Infant, the Underestimated Danger of Dietary Supplements.

Vitamin D supplementation is routinely introduced in infants, according to medical guidelines. However, vitamin D overdose can result in life-threatening hypercalcemia. We report the case of a 3-month-old infant who suffered from severe hypercalcemia. Upon detailed questioning of the parents, a vitamin D administration error has been identified. Indeed, the parents had followed the advice of their midwife. They substituted the prescribed medicinal vitamin D by a dietary supplement, different in concentration and dosing, without performing the dose conversion needed. In fact, many different medications and dietary supplements with vitamin D exist, offering various concentrations and units of measurement. This case highlights the pivotal role of therapeutic education. Broadly, there is a need for harmonization of the regulation and labeling of dietary supplements and medications containing vitamin D.

Extracellular fluid volume: A suitable indexation variable to assess impact of bariatric surgery on glomerular filtration rate in patients with chronic kidney disease.

BACKGROUND: Bariatric surgery (BS) might be a nephroprotective treatment in obese patients with chronic kidney disease (CKD), and the non-linear relation between body surface area (BSA) and extracellular fluid volume (ECFV) in obese people raises the question of the most relevant way to scale glomerular filtration rate (GFR) for assessing renal function changes after BS. METHODS: We screened 1774 BS candidates and analysed 10 consecutive participants with CKD stage 3. True GFR (mGFR), measured by the renal clearance of 51Cr-ethylenediaminetetraacetic acid (EDTA), was scaled either to BSA (mGFRBSA) or to ECFV measured by 51Cr-EDTA distribution volume (mGFRECFV) before and one year after BS. RESULTS: The 10 candidates for BS had a mean body mass index of 43.3 ± 3.6 kg/m2 and a mean GFR of 48 ± 8 mL/min/1.73 m2. Six participants had a sleeve gastrectomy and four had a Roux-en-Y gastric bypass. One year after BS, ECFV decreased (23.2 ± 6.2 to 17.9 ± 4.3 L, p = 0.001), absolute mGFR was not significantly modified (74 ± 23 versus 68 ±19 mL/min), mGFRBSA did not change significantly (53 ± 18 versus 56 ± 17 mL/min/1.73 m2) whereas mGFRECFV significantly increased (42 ± 13 versus 50 ± 14 mL/min/12.9 L, p = 0.037). The relation between mGFRECFV and mGFRBSA was different from the identity line before (p = 0.014) but not after BS (p = 0.09). CONCLUSION: There is a difference between mGFRBSA and mGFRECFV following BS and the latter might better reflect the adequacy between renal function and corpulence.

Regulation of Monocytes/Macrophages by the Renin-Angiotensin System in Diabetic Nephropathy: State of the Art and Results of a Pilot Study.

Diabetic nephropathy (DN) is characterized by albuminuria, loss of renal function, renal fibrosis and infiltration of macrophages originating from peripheral monocytes inside kidneys. DN is also associated with intrarenal overactivation of the renin-angiotensin system (RAS), an enzymatic cascade which is expressed and controlled at the cell and/or tissue levels. All members of the RAS are present in the kidneys and most of them are also expressed in monocytes/macrophages. This review focuses on the control of monocyte recruitment and the modulation of macrophage polarization by the RAS in the context of DN. The local RAS favors the adhesion of monocytes on renal endothelial cells and increases the production of monocyte chemotactic protein-1 and of osteopontin in tubular cells, driving monocytes into the kidneys. There, proinflammatory cytokines and the RAS promote the differentiation of macrophages into the M1 proinflammatory phenotype, largely contributing to renal lesions of DN. Finally, resolution of the inflammatory process is associated with a phenotype switch of macrophages into the M2 anti-inflammatory subset, which protects against DN. The pharmacologic interruption of the RAS reduces albuminuria, improves the trajectory of the renal function, decreases macrophage infiltration in the kidneys and promotes the switch of the macrophage phenotype from M1 to M2.

LRRC8/VRAC Channels and the Redox Balance: A Complex Relationship.

More than three decades after their first biophysical description, Volume Regulated Anion Channels (VRACs) still remain challenging to understand. Initially, VRACs were identified as the main pathway for the cell to extrude Cl- ions during the regulatory volume decrease (RVD) mechanism contributing in fine to the recovery of normal cell volume. For years, scientists have tried unsuccessfully to find their molecular identity, leading to controversy within the field that only ended in 2014 when two independent groups demonstrated that VRACs were formed by heteromers of LRRC8 proteins. This breakthrough gave a second breath to the research field and was followed by many publications regarding LRRC8/VRACs structure/ function, physiological roles and 3D structures. Nevertheless, far from simplifying the field, these discoveries have instead exponentially increased its complexity. Indeed, the channel's biophysical properties seem to be dependent on the LRRC8 subunits composition with each heteromer showing different ion/molecule permeabilities and regulatory mechanisms. One clear example of this complexity is the intricate relationship between LRRC8/VRACs and the redox system. On one hand, VRACs appear to be directly regulated by oxidation or reduction depending on their subunit composition. On the other hand, VRACs can also impact the redox balance within the cells, through their permeability to reduced glutathione or through other as yet uncharacterized pathways. Unravelling this issue is particularly crucial as LRRC8/VRACs play an important role in a wide variety of physiological processes involving oxidative stress signaling. In this regard, we have tried to systematically identify in the literature both preand post-LRRC8 discovery as well as the interplay between VRACs and the redox system to provide new insights into this complex relationship.

Remdesivir and Acute Renal Failure: A Potential Safety Signal From Disproportionality Analysis of the WHO Safety Database.

Remdesivir is approved for emergency use by the US Food and Drug Administration (FDA) and authorized conditionally by the European Medicines Agency (EMA) for patients with coronavirus disease 2019 (COVID-19). Its benefit-risk ratio is still being explored because data in the field are rather scant. A decrease of the creatinine clearance associated with remdesivir has been inconstantly reported in clinical trials with unclear relevance. Despite these uncertainties, we searched for a potential signal of acute renal failure (ARF) in pharmacovigilance postmarketing data. An analysis of the international pharmacovigilance postmarketing databases (VigiBase) of the World Health Organization (WHO) was performed, using two disproportionality methods. Reporting odds ratio (ROR) compared the number of ARF cases reported with remdesivir, with those reported with other drugs prescribed in comparable situations of COVID-19 (hydroxychloroquine, tocilizumab, and lopinavir/ritonavir). The combination of the terms "acute renal failure" and "remdesivir" yielded a statistically significant disproportionality signal with 138 observed cases instead of the 9 expected. ROR of ARF with remdesivir was 20-fold (20.3; confidence interval 0.95 [15.7-26.3], P < 0.0001]) that of comparative drugs. Based on ARF cases reported in VigiBase, and despite the caveats inherent to COVID-19 circumstances, we detected a statistically significant pharmacovigilance signal of nephrotoxicity associated with remdesivir, deserving a thorough qualitative assessment of all available data. Meanwhile, as recommended in its Summary of Product Characteristics, assessment of patients with COVID-19 renal function should prevail before and during treatment with remdesivir in COVID-19.

Alkaline Phosphatases Account for Low Plasma Levels of Inorganic Pyrophosphate in Chronic Kidney Disease.

INTRODUCTION: Patients on dialysis and kidney transplant recipients (KTR) present the syndrome of mineral and bone disorders (MBD), which share common traits with monogenic calcifying diseases related to disturbances of the purinergic system. Low plasma levels of inorganic pyrophosphate (PPi) and ectopic vascular calcifications belong to these two conditions. This suggests that the purinergic system may be altered in chronic kidney disease with MBD. Therefore, we perform a transversal pilot study in order to compare the determinants of PPi homeostasis and the plasma levels of PPi in patients on dialysis, in KTR and in healthy people. PATIENTS AND METHODS: We included 10 controls, 10 patients on maintenance dialysis, 10 early KTR 3 ± 1 months after transplantation and nine late KTR 24 ± 3 months after transplantation. We measured aortic calcifications, plasma and urine levels of PPi, the renal fractional excretion of PPi (FePPi), nucleoside triphosphate hydrolase (NPP) and ALP activities in plasma. Correlations and comparisons were assessed with non-parametric tests. RESULTS: Low PPi was found in patients on dialysis [1.11 (0.88-1.35), p = 0.004], in early KTR [0.91 (0.66-0.98), p = 0.0003] and in late KTR [1.16 (1.07-1.45), p = 0.02] compared to controls [1.66 (1.31-1.72) µmol/L]. Arterial calcifications were higher in patients on dialysis than in controls [9 (1-75) vs. 399 (25-526) calcium score/cm2, p < 0.05]. ALP activity was augmented in patients on dialysis [113 (74-160), p = 0.01] and in early KTR [120 (84-142), p = 0.002] compared to controls [64 (56-70) UI/L]. The activity of NPP and FePPi were not different between groups. ALP activity was negatively correlated with PPi (r = -0.49, p = 0.001). DISCUSSION: Patients on dialysis and KTR have low plasma levels of PPi, which are partly related to high ALP activity, but neither to low NPP activity, nor to increased renal excretion of PPi. Further work is necessary to explore comprehensively the purinergic system in chronic kidney disease.

The ABCC6 Transporter: A New Player in Biomineralization.

Pseudoxanthoma elasticum (PXE) is an inherited metabolic disease with autosomal recessive inheritance caused by mutations in the ABCC6 gene. Since the first description of the disease in 1896, alleging a disease involving the elastic fibers, the concept evolved with the further discoveries of the pivotal role of ectopic mineralization that is preponderant in the elastin-rich tissues of the skin, eyes and blood vessel walls. After discovery of the causative gene of the disease in 2000, the function of the ABCC6 protein remains elusive. More than 300 mutations have been now reported and the concept of a dermal disease has progressively evolved toward a metabolic disorder resulting from the remote effects caused by lack of a circulating anti-mineralization factor. Very recently, evidence has accumulated that this anti-mineralizing factor is inorganic pyrophosphate (PPi). This leads to decreased PPi/Pi (inorganic phosphate) ratio that results from the lack of extracellular ATP release by hepatocytes and probably renal cells harboring the mutant ABCC6 protein. However, the mechanism by which ABCC6 dysfunction causes diminished ATP release remains an enigma. Studies of other ABC transporters, such as ABCC7 or ABCC1 could help our understanding of what ABCC6 exact function is. Data and a hypothesis on the possible roles of ABCC6 in acquired metabolic diseases are also discussed.