Pharmacology of Tyrosine Kinase Inhibitors: Implications for Patients with Kidney Diseases.

Tyrosine kinase inhibitors (TKI) have introduced a significant advancement in cancer management. These compounds are administered orally, and their absorption holds a pivotal role in determining their variable efficacy. They exhibit extensive distribution within the body, binding strongly to both plasma and tissue proteins. Often reliant on efflux and influx transporters, TKI undergo primary metabolism by intestinal and hepatic cytochrome P450 enzymes, with nonkidney clearance being predominant. Owing to their limited therapeutic window, many TKI display considerable intraindividual and interindividual variability. This review offers a comprehensive analysis of the clinical pharmacokinetics of TKI, detailing their interactions with drug transporters and metabolic enzymes, while discussing potential clinical implications. The prevalence of kidney conditions, such as AKI and CKD, among patients with cancer is explored in their effect on TKI pharmacokinetics. Finally, the potential nephrotoxicity associated with TKI is also examined.

Proteomics of Plasma and Plasma-Treated Podocytes: Application to Focal and Segmental Glomerulosclerosis.

Focal and segmental glomerulosclerosis (FSGS) is a severe form of idiopathic nephrotic syndrome (INS), a glomerulopathy of presumably immune origin that is attributed to extrarenal pathogenic circulating factors. The recurrence of FSGS (rFSGS) after transplant occurs in 30% to 50% of cases. The direct analysis of patient plasma proteome has scarcely been addressed to date, mainly due to the methodological difficulties associated with plasma complexity and dynamic range. In this study, first, we compared different methods of plasma preparation, second, we compared the plasma proteomes of rFSGS and controls using two preparation methods, and third, we analyzed the early proximal signaling events in podocytes subjected to patient plasma, through a combination of phosphoproteomics and lipid-raft proteomics (raftomics). By combining immunodepletion and high pH fractionation, we performed a differential proteomic analysis of soluble plasma proteins and of extracellular vesicles (EV) obtained from healthy controls, non-INS patient controls, and rFSGS patients (n = 4). In both the soluble- and the EV-protein sets from the rFSGS patients, we found a statistically significant increase in a cluster of proteins involved in neutrophil degranulation. A group of lipid-binding proteins, generally associated with lipoproteins, was found to be decreased in the soluble set from the rFSGS patients. In addition, three amino acid transporters involved in mTORC1 activation were found to be significantly increased in the EV from the rFSGS. Next, we incubated human podocytes for 30 min with 10% plasma from both groups of patients. The phosphoproteomics and raftomics of the podocytes revealed profound differences in the proteins involved in the mTOR pathway, in autophagy, and in cytoskeleton organization. We analyzed the correlation between the abundance of plasma and plasma-regulated podocyte proteins. The observed changes highlight some of the mechanisms involved in FSGS recurrence and could be used as specific early markers of circulating-factor activity in podocytes.

Stage lighting on PAR-1: a step further in the understanding of acquired focal and segmental glomerulosclerosis.

The pathogenic mechanisms of acquired focal and segmental glomerular sclerosis are only partially known and represent a medical challenge in nephrology. The article by May et al. sheds additional light on previous data indicating the key role of the protease-activated receptor 1. The new evidence is based on in vivo studies in relevant animal models and on patient biopsies and represents a significant step forward in the understanding of this pathologic condition.

9-O Acetylated Gangliosides in Health and Disease.

Glycosphingolipids comprise a lipid class characterized by the presence of sugar moieties attached to a ceramide backbone. The role of glycosphingolipids in pathophysiology has gained relevance in recent years in parallel with the development of analytical technologies. Within this vast family of molecules, gangliosides modified by acetylation represent a minority. Described for the first time in the 1980s, their relation to pathologies has resulted in increased interest in their function in normal and diseased cells. This review presents the state of the art on 9-O acetylated gangliosides and their link to cellular disorders.

Long-term health-related quality of life outcomes of adults with pediatric onset of frequently relapsing or steroid-dependent nephrotic syndrome.

BACKGROUND: Long-term psychosocial outcomes and health-related quality of life (HRQOL) in adults with pediatric onset of frequently relapsing or steroid-dependent idiopathic nephrotic syndrome (FRNS or SDNS) remain to be determined. METHODS: In this prospective cohort study, 59 adults with pediatric onset of FRNS/SDNS and persistent active glomerular disease in adulthood completed the GEDEPAC-2 questionnaire exploring 11 well-being domains. Data were compared to the French general population (FGP) with standardized incidence ratio ([SIR]; adjusted for period, age, gender). Regression models were performed to identify predictive factors of psychosocial well-being. RESULTS: In 82% of cases, the questionnaire was completed while the participants (n = 59; 47 men; median age = 32 years; median number of relapses = 13) were in complete remission (under specific therapy in 76% of cases). Participants had higher educational degree than in the FGP (SIR = 6.3; p < 0.01) and more frequently a managerial occupation (SIR = 3.1; p < 0.01). Social integration was acceptable with regard to marital status and experience of sexual intercourse, but experiences of discrimination were far more frequent (SIR = 12.5; p < 0.01). The SF-12 mental component summary (MCS) score was altered (Z-score = - 0.6; p < 0.01) and mean multidimensional fatigue inventory (MFI-20) global fatigue score appeared high (12). Transfer from pediatric to adult healthcare was followed by a period of discontinued care for 33% of participants. Multivariate analysis revealed a close relationship between MFI-20, physical health, and MCS. CONCLUSIONS: This study shows that pediatric onset FRNS and SDNS may have a long-term negative impact on mental HRQOL and highlights the impact of fatigue, which is often not adequately considered in routine care.

CMIP interacts with WT1 and targets it on the proteasome degradation pathway.

BACKGROUND: The Wilms tumor 1 suppressor gene, WT1, is expressed throughout life in podocytes and is essential for their function. Downregulation of WT1 has been reported in podocyte diseases but the underlying mechanisms remain unclear. Podocyte injury is the hallmark of idiopathic nephrotic syndrome (INS), the most frequent glomerular disease in children and young adults. An increase in the abundance of Cmaf-inducing protein (CMIP) has been found to alter podocyte function, but it is not known whether CMIP affects WT1 expression. METHODS: Transcriptional and post-transcriptional regulation of WT1in the presence of CMIP was studied using transient transfection, mouse models, and siRNA handling. RESULTS: We showed that overproduction of CMIP in the podocyte was consistently associated with a downregulation of WT1 according to two mechanisms. We found that CMIP prevented the NF-kB-mediated transcriptional activation of WT1. We demonstrated that CMIP interacts directly with WT1 through its leucine-rich repeat domain. Overexpression of CMIP in the M15 cell line induced a downregulation of WT1, which was prevented by lactacystin, a potent proteasome inhibitor. We showed that CMIP exhibits an E3 ligase activity and targets WT1 to proteasome degradation. Intravenous injection of Cmip-siRNA specifically prevented the repression of Wt1 in lipopolysaccharides-induced proteinuria in mice. CONCLUSIONS: These data suggest that CMIP is a repressor of WT1 and might be a critical player in the pathophysiology of some podocyte diseases. Because WT1 is required for podocyte integrity, CMIP could be considered a therapeutic target in podocyte diseases.

Impact of pre-eclampsia on renal outcome in sickle cell disease patients.

The long-term consequences of pre-eclampsia (PrE) for renal function have never been determined in patients with sickle cell disease (SCD). Between 2008 and 2015, we screened 306 pregnancies in women with SCD and identified 40 with PrE (13%). The control group consisted of 65 pregnant SCD patients without PrE. In multivariable analysis, PrE events were associated with an increase of 1 log of lactate dehydrogenase level (adjusted odds ratio, aOR = 3·83, P = 0·05), a decrease of 10 g/l of haemoglobin levels (aOR = 2·48, P = 0·006) and one or more vaso-occlusive crisis during pregnancy (aOR = 16·68, P = 0·002). Estimated glomerular filtration rate (eGFR) was similar in the two groups at steady state but was significantly lower in the PrE group after one year of follow-up and at last follow-up (130 vs 148 ml/min/1·73 m2 , P < 0·001 and 120 vs 130 ml/min/1·73 m2 , P < 0·001, respectively). In multivariable analysis, eGFR had returned to steady-state levels one year after pregnancy in patients without PrE but continued to decrease in patients with PrE (ß = -18·15 ml/min/1·73 m2 , P < 0·001). This decline was more marked at the end of follow-up (ß = -31·15 ml/min, P < 0·001). In conclusion, PrE episodes are associated with a significant risk of subsequent renal function decline in SCD patients.

[Renal failure and renal symptoms associated with molecular targeted therapies in oncology]. / Insuffisance rénale et symptômes rénaux associés aux thérapies moléculaires ciblées en oncologie.

"Targeted therapies and pathophysiological mechanisms of proteinuria Targeted therapy represents a promising therapeutic approach for patients with diverse cancers and has enabled significant development in medical oncology. This new class of anticancer drugs includes antibodies, fusion-proteins and receptor tyrosine kinase inhibitors among others. Depending on their molecular targeting, side effects can affect multiple organs, especially the kidney. Antiangiogenic agents inhibit the VEGF/VEGFR pathway resulting in reduction of nitric oxide production and alteration of podocytes function, which causes hypertension and proteinuria. EGFR inhibitors are responsible of electrolytic disorders. Hereby, we synthetized the current knowledge on renal toxicities on main molecular targeted therapies. Toxicities management is mainly based on clinical and biological monitoring, which can lead to drug withdrawing or dose adaptation."

"Thérapies ciblées et mécanismes physiopathologiques de la protéinurie Les thérapies ciblées occupent désormais une place majeure en oncologie médicale. Elles existent sous plusieurs formes d'administration, parentérale ou per os, et comportent entre autres des anticorps, des protéines de fusion et des inhibiteurs de récepteur des tyrosine kinases. Les effets indésirables liés à ces thérapies dépendent généralement de leur classe thérapeutique. Les antiangiogéniques, qui altèrent les podocytes et la production de monoxyde d'azote via l'inhibition de la voie VEGF/VEGFR, entraînent hypertension artérielle et protéinurie et sont parfois à l'origine de microangiopathies thrombotiques. Les inhibiteurs de l'EGFR entraînent principalement des troubles hydroélectrolytiques par inhibition de transporteurs rénaux. D'autres toxicités sont plus rares, comme les inhibiteurs de BRAF, parfois à l'origine d'insuffisances rénales aiguës immuno-allergiques. La prise en charge de ces toxicités repose généralement sur la surveillance clinique et biologique et peut conduire à la suspension des traitements ou à leur adaptation posologique."

Nephrotoxicity of Anti-Angiogenic Therapies.

The use of inhibitors of vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling for the treatment of cancer has increased over the last decade. This signaling pathway plays a fundamental role in angiogenesis and also in kidney physiology. The emergence of anti-angiogenic therapies has led to adverse nephrotoxic effects, despite improving the outcomes of patients. In this review, we will present the different anti-angiogenic therapies targeting the VEGFR pathway in association with the incidence of renal manifestations during their use. In addition, we will discuss, in detail, the pathophysiological mechanisms of frequent renal diseases such as hypertension, proteinuria, renal dysfunction, and electrolyte disorders. Finally, we will outline the cellular damage described following these therapies.

The Enigmatic Emerging Role of the C-Maf Inducing Protein in Cancer.

The C-Maf-Inducing protein (CMIP) was first described as overexpressed in T cell subpopulations of idiopathic nephrotic syndrome (INS) patients. Later, it was found concomitantly upregulated in podocytes. CMIP expression has also been reported in several types of cancer, including blood malignancies and solid tumors, in many cases accompanied by nephrotic syndrome. In addition to these observations, the duality of CMIP overexpression in the kidney and INS lesions, has been extensively reported as one of the adverse effects of anticancer therapy based on anti-receptor tyrosine kinase drugs. As a consequence, a growing body of evidence points at CMIP as playing a role in cancer. This includes its reciprocal regulatory ties with NF-κB and WT1, and the more recent reports showing an involvement in regulatory circuits in cancer cells. The ensemble of the current information justifies to propose CMIP as an important piece of the puzzle of biological systems involved in cancer and other diseases and its potential as a target.

De Novo Focal and Segmental Glomerulosclerosis After COVID-19 in a Patient With a Transplanted Kidney From a Donor With a High-risk APOL1 Variant.

BACKGROUND: There is compelling evidence that renal complications in a native kidney are a major concern in patients infected with severe acute respiratory syndrome coronavirus 2, the causal agent of coronavirus disease 2019 (COVID-19). The spectrum of renal lesions observed on renal grafts in this context remains to be determined. METHODS: We report the case of a renal transplant recipient with non-severe COVID-19, who subsequently developed nephrotic syndrome associated with acute renal injury. RESULTS: Renal biopsy demonstrated focal and segmental glomerulosclerosis lesions classified as not otherwise specified histological variant. Genotyping for 2 risk alleles of the apolipoprotein L1 gene demonstrated that the donor was homozygous for the G2/G2 genotype. CONCLUSIONS: In renal transplant patients receiving kidneys from donors with high-risk apolipoprotein L1 variants, COVID-19 may promote acute glomerular injury in the form of focal and segmental glomerulosclerosis.

Circulating plasmablasts and high level of BAFF are hallmarks of minimal change nephrotic syndrome in adults.

BACKGROUND: The recent success achieved with the use of B cell-depleting agents in some patients with minimal change nephrotic syndrome (MCNS) suggests an unexpected role for B lymphocytes in the pathogenesis of this immune-mediated glomerular disease. Nevertheless, no extensive B-cell phenotyping analysis has ever been performed in untreated adult patients soon after MCNS diagnosis. METHODS: We investigated the distribution of the different B-cell subpopulations in 22 untreated adult patients with biopsy-proven MCNS [MCNS relapse (MCNS-Rel)]. We compared these data with those for 24 healthy controls, 13 MCNS patients in remission (with no specific treatment) and 19 patients with idiopathic membranous nephropathy (IMN). RESULTS: Patients with MCNS-Rel or IMN had higher proteinuria and lower serum albumin and gammaglobulin levels (P < 0.0001 for all comparisons) than MCNS patients in remission. Plasmablasts were the only B-cell subsets present at significantly higher levels in MCNS-Rel patients than in the patients of the other three groups (P < 0.05 for all comparisons). The lower albumin levels and higher proteinuria levels were positively correlated with the percentage of circulating plasmablasts (Spearman test's ρ = -0.54, P = 0.01 and ρ = 0.65, P = 0.002, respectively). Similarly, the increase of immunoglobulin M (IgM) and the decrease of IgG levels were significantly associated with the percentage of plasmablasts in MCNS-Rel patients (Spearman's ρ = 0.36, P = 0.01 and Spearman's ρ = -0.60, P = 0.01, respectively). Increased production of interleukin (IL)-21, IL-6 and B-cell activating factor (BAFF) in the serum of MCNS-Rel patients was found significantly correlated with the percentage of plasmablasts (ρ = 0.72, P = 0.0002, ρ = 0.49, P = 0.04 and ρ = 0.62, P = 0.009, respectively). CONCLUSIONS: An increase in the proportion of circulating plasmablasts seems to be a hallmark of untreated MCNS in adult patients. Further studies are required to more precisely determine the phenotype and functions of these cells.

Gangliosides in Podocyte Biology and Disease.

Gangliosides constitute a subgroup of glycosphingolipids characterized by the presence of sialic acid residues in their structure. As constituents of cellular membranes, in particular of raft microdomains, they exert multiple functions, some of them capital in cell homeostasis. Their presence in cells is tightly regulated by a balanced expression and function of the enzymes responsible for their biosynthesis, ganglioside synthases, and their degradation, glycosidases. The dysregulation of their abundance results in rare and common diseases. In this review, we make a point on the relevance of gangliosides and some of their metabolic precursors, such as ceramides, in the function of podocytes, the main cellular component of the glomerular filtration barrier, as well as their implications in podocytopathies. The results presented in this review suggest the pertinence of clinical lipidomic studies targeting these metabolites.

A sensitive S-Trap-based approach to the analysis of T cell lipid raft proteome.

The analysis of T cell lipid raft proteome is challenging due to the highly dynamic nature of rafts and the hydrophobic character of raft-resident proteins. We explored an innovative strategy for bottom-up lipid raftomics based on suspension-trapping (S-Trap) sample preparation. Mouse T cells were prepared from splenocytes by negative immunoselection, and rafts were isolated by a detergent-free method and OptiPrep gradient ultracentrifugation. Microdomains enriched in flotillin-1, LAT, and cholesterol were subjected to proteomic analysis through an optimized protocol based on S-Trap and high pH fractionation, followed by nano-LC-MS/MS. Using this method, we identified 2,680 proteins in the raft-rich fraction and established a database of 894 T cell raft proteins. We then performed a differential analysis on the raft-rich fraction from nonstimulated versus anti-CD3/CD28 T cell receptor (TCR)-stimulated T cells. Our results revealed 42 proteins present in one condition and absent in the other. For the first time, we performed a proteomic analysis on rafts from ex vivo T cells obtained from individual mice, before and after TCR activation. This work demonstrates that the proposed method utilizing an S-Trap-based approach for sample preparation increases the specificity and sensitivity of lipid raftomics.

Malaria, Collapsing Glomerulopathy, and Focal and Segmental Glomerulosclerosis.

BACKGROUND AND OBJECTIVES: Malaria, a potentially life-threatening disease, is the most prevalent endemic infectious disease worldwide. In the modern era, the spectrum of glomerular involvement observed in patients after malarial infections remains poorly described. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We therefore performed a retrospective multicenter study to assess the clinical, biologic, pathologic, and therapeutic characteristics of patients with glomerular disease demonstrated by kidney biopsy in France within 3 months of an acute malaria episode. RESULTS: We identified 23 patients (12 men), all but 1 of African ancestry and including 10 patients with concomitant HIV infection. All of the imported cases were in French citizens living in France who had recently traveled back to France from an endemic area and developed malaria after their return to France. Eleven patients had to be admitted to an intensive care unit at presentation. Plasmodium falciparum was detected in 22 patients, and Plasmodium malariae was detected in 1 patient. Kidney biopsy was performed after the successful treatment of malaria, a mean of 24 days after initial presentation. At this time, all patients displayed AKI, requiring KRT in 12 patients. Nephrotic syndrome was diagnosed in 17 patients. Pathologic findings included FSGS in 21 patients and minimal change nephrotic syndrome in 2 patients. Among patients with FSGS, 18 had collapsing glomerulopathy (including 9 patients with HIV-associated nephropathy). In four patients, immunohistochemistry with an antibody targeting P. falciparum histidine-rich protein-2 demonstrated the presence of the malaria antigen in tubular cells but not in podocytes or parietal epithelial cells. An analysis of the apoL1 risk genotype showed that high-risk variants were present in all seven patients tested. After a mean follow-up of 23 months, eight patients required KRT (kidney transplantation in two patients), and mean eGFR for the other patients was 51 ml/min per 1.73 m2. CONCLUSIONS: In patients of African ancestry, imported Plasmodium infection may be a new causal factor for secondary FSGS, particularly for collapsing glomerulopathy variants in an APOL1 high-risk variant background.

CMIP is a negative regulator of T cell signaling.

Upon their interaction with cognate antigen, T cells integrate different extracellular and intracellular signals involving basal and induced protein-protein interactions, as well as the binding of proteins to lipids, which can lead to either cell activation or inhibition. Here, we show that the selective T cell expression of CMIP, a new adapter protein, by targeted transgenesis drives T cells toward a naïve phenotype. We found that CMIP inhibits activation of the Src kinases Fyn and Lck after CD3/CD28 costimulation and the subsequent localization of Fyn and Lck to LRs. Video microscopy analysis showed that CMIP blocks the recruitment of LAT and the lipid raft marker cholera toxin B at the site of TCR engagement. Proteomic analysis identified several protein clusters differentially modulated by CMIP and, notably, Cofilin-1, which is inactivated in CMIP-expressing T cells. Moreover, transgenic T cells exhibited the downregulation of GM3 synthase, a key enzyme involved in the biosynthesis of gangliosides. These results suggest that CMIP negatively impacts proximal signaling and cytoskeletal rearrangement and defines a new mechanism for the negative regulation of T cells that could be a therapeutic target.

Cationic poly(cyclodextrin)/alginate nanocapsules: From design to application as efficient delivery vehicle of 4-hydroxy tamoxifen to podocyte in vitro.

Most of the drug molecules are partially insoluble in aqueous solution and then may accumulate in fat tissues hampering efficient therapy. Innovative drug delivery strategies have emerged in industry or academia over the last decades, however preserving the activity of the encapsulated drug, having high drug loading capacity and controlling drug release kinetics, are still challenging. In this context, we explored the preparation of new nanocarriers, namely nanocapsules, via a templating method, and using polysaccharides exhibiting biological functions. Cationic poly(cyclodextrin) (P(CD+)) and alginate (alg-) were initially self-assembled layer-by-layer on colloidal gold nanoparticles. Removal of gold nanoparticles was then induced thorough cyanide-assisted hydrolysis, enabling the recovery of nanocapsules. A hydrophobic drug known to allow the mutation of genes inside cells, namely 4-hydroxy-tamoxifen, was loaded within the nanocapsules' shell via inclusion with the cyclodextrin cavities. The so-designed nanomaterials were incubated with immortalized podocytes to investigate i) their incorporation inside cells and ii) their efficiency for in vitro 4-hydroxy-tamoxifen-induced CreERT2 recombination. This work undoubtedly highlights a proof-of-concept for drug delivery using polysaccharides-based capsules with host properties.

Kidney Lipidomics by Mass Spectrometry Imaging: A Focus on the Glomerulus.

Lipid disorders have been associated with glomerulopathies, a distinct type of renal pathologies, such as nephrotic syndrome. Global analyses targeting kidney lipids in this pathophysiologic context have been extensively performed, but most often regardless of the architectural and functional complexity of the kidney. The new developments in mass spectrometry imaging technologies have opened a promising field in localized lipidomic studies focused on this organ. In this article, we revisit the main works having employed the Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) technology, and the few reports on the use of TOF-Secondary Ion Mass Spectrometry (TOF-SIMS). We also present a first analysis of mouse kidney cortex sections by cluster TOF-SIMS. The latter represents a good option for high resolution lipid imaging when frozen unfixed histological samples are available. The advantages and drawbacks of this developing field are discussed.