Acute kidney injury induced by ischemia/reperfusion is an independent risk factor for chronic kidney disease. Macrophage recruitment plays an essential role during the injury and repair phases after ...an ischemic episode in the kidney. Here we show that the novel non-steroidal mineralocorticoid receptor antagonist finerenone or selective myeloid mineralocorticoid receptor ablation protects against subsequent chronic dysfunction and fibrosis induced by an episode of bilateral kidney ischemia/reperfusion in mice. This protection was associated with increased expression of M2-antiinflamatory markers in macrophages from finerenone-treated or myeloid mineralocorticoid receptor-deficient mice. Moreover, the inflammatory population of CD11b+, F4/80+, Ly6Chigh macrophages was also reduced. Mineralocorticoid receptor inhibition promoted increased IL-4 receptor expression and activation in the whole kidney and in isolated macrophages, thereby facilitating macrophage polarization to an M2 phenotype. The long-term protection conferred by mineralocorticoid receptor antagonism was also translated to the Large White pig pre-clinical model. Thus, our studies support the rationale for using mineralocorticoid receptor antagonists in clinical practice to prevent transition of acute kidney injury to chronic kidney disease.
Inflammation is a prominent feature of ischemia-reperfusion injury (IRI), which is characterized by leukocyte infiltration and renal tubular injury. However, signals that initiate these events remain ...poorly understood. We examined the role of the nuclear alarmin IL-33 in tissue injury and innate immune response triggered by experimental kidney ischemia-reperfusion. In wild-type mice, we found that IL-33 was constitutively expressed throughout the kidney in peritubular and periglomerular spaces, mainly by microvascular endothelial cells, from which it was released immediately during IRI. Compared with wild-type mice, mice lacking IL-33 (IL-33
) exhibited reductions in early tubular cell injury and subsequent renal infiltration of IFN-
/IL-17A-producing neutrophils, with preservation of renal functions. This protection associated with decreased renal recruitment of myeloid dendritic cells, natural killer (NK) cells, and invariant natural killer T (iNKT) cells, the latter of which were reported as deleterious in IRI. Increases in the level of circulating IL-12, a key IL-33 cofactor, and the expression of ST2, an IL-33-specific receptor, on the surface of iNKT cells preceded the IL-33- and iNKT cell-dependent phase of neutrophil infiltration. Furthermore, IL-33 directly targeted iNKT cells
, inducing IFN-
and IL-17A production. We propose that endogenous IL-33 is released as an alarmin and contributes to kidney IRI by promoting iNKT cell recruitment and cytokine production, resulting in neutrophil infiltration and activation at the injury site. Our findings show a novel molecular mediator contributing to innate immune cell recruitment induced by renal ischemia-reperfusion and may provide therapeutic insights into AKI associated with renal transplantation.
Ischemia reperfusion injury is a complex process consisting of a seemingly chaotic but actually organized and compartmentalized shutdown of cell function, of which oxidative stress is a key ...component. Studying oxidative stress, which results in an imbalance between reactive oxygen species (ROS) production and antioxidant defense activity, is a multi-faceted issue, particularly considering the double function of ROS, assuming roles as physiological intracellular signals and as mediators of cellular component damage. Herein, we propose a comprehensive overview of the tools available to explore oxidative stress, particularly in the study of ischemia reperfusion. Applying chemistry as well as biology, we present the different models currently developed to study oxidative stress, spanning the vitro and the silico, discussing the advantages and the drawbacks of each set-up, including the issues relating to the use of in vitro hypoxia as a surrogate for ischemia. Having identified the limitations of historical models, we shall study new paradigms, including the use of stem cell-derived organoids, as a bridge between the in vitro and the in vivo comprising 3D intercellular interactions in vivo and versatile pathway investigations in vitro. We shall conclude this review by distancing ourselves from "wet" biology and reviewing the in silico, computer-based, mathematical modeling, and numerical simulation options: (a) molecular modeling with quantum chemistry and molecular dynamic algorithms, which facilitates the study of molecule-to-molecule interactions, and the integration of a compound in a dynamic environment (the plasma membrane...); (b) integrative systemic models, which can include many facets of complex mechanisms such as oxidative stress or ischemia reperfusion and help to formulate integrated predictions and to enhance understanding of dynamic interaction between pathways.
Cell therapy, i.e., the use of cells to repair an affected tissue or organ, is at the forefront of regenerative and personalized medicine. Among the multiple cell types that have been used for this ...purpose including adult stem cells such as mesenchymal stem cells or pluripotent stem cells, urine-derived stem cells (USCs) have aroused interest in the past years. USCs display classical features of mesenchymal stem cells such as differentiation capacity and immunomodulation. Importantly, they have the main advantage of being isolable from one sample of voided urine with a cheap and unpainful procedure, which is broadly applicable, whereas most adult stem cell types require invasive procedure. Moreover, USCs can be differentiated into renal cell types. This is of high interest for renal cell therapy-based regenerative approaches. This review will firstly describe the isolation and characterization of USCs. We will specifically present USC phenotype, which is not an object of consensus in the literature, as well as detail their differentiation capacity. In the second part of this review, we will present and discuss the main applications of USCs. These include use as a substrate to generate human induced pluripotent stem cells, but we will deeply focus on the use of USCs for cell therapy approaches with a detailed analysis depending on the targeted organ or system. Importantly, we will also focus on the applications that rely on the use of USC-derived products such as microvesicles including exosomes, which is a strategy being increasingly employed. In the last section, we will discuss the remaining barriers and challenges in the field of USC-based regenerative medicine.Cell therapy, i.e., the use of cells to repair an affected tissue or organ, is at the forefront of regenerative and personalized medicine. Among the multiple cell types that have been used for this purpose including adult stem cells such as mesenchymal stem cells or pluripotent stem cells, urine-derived stem cells (USCs) have aroused interest in the past years. USCs display classical features of mesenchymal stem cells such as differentiation capacity and immunomodulation. Importantly, they have the main advantage of being isolable from one sample of voided urine with a cheap and unpainful procedure, which is broadly applicable, whereas most adult stem cell types require invasive procedure. Moreover, USCs can be differentiated into renal cell types. This is of high interest for renal cell therapy-based regenerative approaches. This review will firstly describe the isolation and characterization of USCs. We will specifically present USC phenotype, which is not an object of consensus in the literature, as well as detail their differentiation capacity. In the second part of this review, we will present and discuss the main applications of USCs. These include use as a substrate to generate human induced pluripotent stem cells, but we will deeply focus on the use of USCs for cell therapy approaches with a detailed analysis depending on the targeted organ or system. Importantly, we will also focus on the applications that rely on the use of USC-derived products such as microvesicles including exosomes, which is a strategy being increasingly employed. In the last section, we will discuss the remaining barriers and challenges in the field of USC-based regenerative medicine.
Optimizing kidney preservation is a primary issue in transplantation, particularly in relation to new donor sources, such as expanded criteria donors (ECDs) and donation after cardiac death (DCD). ...Kidneys from these donors are highly sensitive to ischemia-reperfusion injuries--the emblematic lesions encountered during transplantation. Despite years of research, static cold storage, with solutions designed in the 1980s, remains the gold standard in kidney transplantation. This kind of preservation, however, is unable to fully protect an ECD or DCD kidney, highlighting the need for novel strategies to improve kidney preservation or promote kidney recovery. This Review provides an overview of the emerging strategies to prevent ischemia-reperfusion injuries in donor kidneys and describes strategies that are aimed at the donor, organ or recipient to improve graft outcome. These approaches include management of donors, preconditioning of the kidney, improvements in organ preservation solutions, postconditioning and regenerative therapies of the kidney graft following transplantation. In addition, machine perfusion provides an interesting opportunity to evaluate kidney graft quality before transplantation. Overall, a combination of therapeutic approaches seem to provide the best outcome, but preclinical studies using relevant models are needed before these approaches can be incorporated into clinical practice.
Inhibition of the eukaryotic initiation factor 5A activation by the spermidine analogue GC7 has been shown to protect proximal cells and whole kidneys against an acute episode of ischaemia. The ...highlighted mechanism involves a metabolic switch from oxidative phosphorylation toward glycolysis allowing cells to be transiently independent of oxygen supply. Here we show that GC7 decreases protein expression of the renal GLUT1 glucose transporter leading to a decrease in transcellular glucose flux. At the same time, GC7 modifies the native energy source of the proximal cells from glutamine toward glucose use. Thus, GC7 acutely and reversibly reprogrammes function and metabolism of kidney cells to make glucose its single substrate, and thus allowing cells to be oxygen independent through anaerobic glycolysis. The physiological consequences are an increase in the renal excretion of glucose and lactate reflecting a decrease in glucose reabsorption and an increased glycolysis. Such a reversible reprogramming of glucose handling and oxygen dependence of kidney cells by GC7 represents a pharmacological opportunity in ischaemic as well as hyperglycaemia-associated pathologies from renal origin.
Organ transplantation remains the treatment of last resort in case of failure of a vital organ (lung, liver, heart, intestine) or non-vital organ (essentially the kidney and pancreas) for which ...supplementary treatments exist. It remains the best alternative both in terms of quality-of-life and life expectancy for patients and of public health expenditure. Unfortunately, organ shortage remains a widespread issue, as on average only about 25% of patients waiting for an organ are transplanted each year. This situation has led to the consideration of recent donor populations (deceased by brain death with extended criteria or deceased after circulatory arrest). These organs are sensitive to the conditions of conservation during the ischemia phase, which have an impact on the graft's short- and long-term fate. This evolution necessitates a more adapted management of organ donation and the optimization of preservation conditions. In this general review, the different aspects of preservation will be considered. Initially done by hypothermia with the help of specific solutions, preservation is evolving with oxygenated perfusion, in hypothermia or normothermia, aiming at maintaining tissue metabolism. Preservation time is also becoming a unique evaluation window to predict organ quality, allowing repair and/or optimization of recipient choice.
Cross-species immunological incompatibilities have hampered pig-to-human xenotransplantation, but porcine genome engineering recently enabled the first successful experiments. However, little is ...known about the immune response after the transplantation of pig kidneys to human recipients. We aimed to precisely characterise the early immune responses to the xenotransplantation using a multimodal deep phenotyping approach.
We did a complete phenotyping of two pig kidney xenografts transplanted to decedent humans. We used a multimodal strategy combining morphological evaluation, immunophenotyping (IgM, IgG, C4d, CD68, CD15, NKp46, CD3, CD20, and von Willebrand factor), gene expression profiling, and whole-transcriptome digital spatial profiling and cell deconvolution. Xenografts before implantation, wild-type pig kidney autografts, as well as wild-type, non-transplanted pig kidneys with and without ischaemia-reperfusion were used as controls.
The data collected from xenografts suggested early signs of antibody-mediated rejection, characterised by microvascular inflammation with immune deposits, endothelial cell activation, and positive xenoreactive crossmatches. Capillary inflammation was mainly composed of intravascular CD68+ and CD15+ innate immune cells, as well as NKp46+ cells. Both xenografts showed increased expression of genes biologically related to a humoral response, including monocyte and macrophage activation, natural killer cell burden, endothelial activation, complement activation, and T-cell development. Whole-transcriptome digital spatial profiling showed that antibody-mediated injury was mainly located in the glomeruli of the xenografts, with significant enrichment of transcripts associated with monocytes, macrophages, neutrophils, and natural killer cells. This phenotype was not observed in control pig kidney autografts or in ischaemia-reperfusion models.
Despite favourable short-term outcomes and absence of hyperacute injuries, our findings suggest that antibody-mediated rejection in pig-to-human kidney xenografts might be occurring. Our results suggest specific therapeutic targets towards the humoral arm of rejection to improve xenotransplantation results.
OrganX and MSD Avenir.
Kidneys from donation after circulatory death (DCD) are highly sensitive to ischemia‐reperfusion injury and thus require careful reconditioning, such as normothermic regional perfusion (NRP). ...However, the optimal NRP protocol remains to be characterized. NRP was modeled in a DCD porcine model (30 minutes of cardiac arrest) for 2, 4, or 6 hours compared to a control group (No‐NRP); kidneys were machine‐preserved and allotransplanted. NRP appeared to permit recovery from warm ischemia, possibly due to an increased expression of HIF1α‐dependent survival pathway. At 2 hours, blood levels of ischemic injury biomarkers increased: creatinine, lactate/pyruvate ratio, LDH, AST, NGAL, KIM‐1, CD40 ligand, and soluble‐tissue‐factor. All these markers then decreased with time; however, AST, NGAL, and KIM‐1 increased again at 6 hours. Hemoglobin and platelets decreased at 6 hours, after which the procedure became difficult to maintain. Regarding inflammation, active tissue‐factor, cleaved PAR‐2 and MCP‐1 increased by 4‐6 hours, but not TNF‐α and iNOS. Compared to No‐NRP, NRP kidneys showed lower resistance during hypothermic machine perfusion (HMP), likely associated with pe‐NRP eNOS activation. Kidneys transplanted after 4 and 6 hours of NRP showed better function and outcome, compared to No‐NRP. In conclusion, our results confirm the mechanistic benefits of NRP and highlight 4 hours as its optimal duration, after which injury markers appear.
The authors report a preclinical porcine model for normothermic regional perfusion in the kidney donor used to specify the mechanisms involved and to optimize the duration of the procedure.
PDF
