Harnessing Endogenous T-Regulatory Cells in Acute Kidney Injury.
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ABSTRACT:
SUBMITTER: Sharma R
PROVIDER: S-EPMC7708413 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The mechanism of mesenchymal stem cell therapy in acute kidney injury remains uncertain. Previous studies indicated that mesenchymal stem cells could attenuate inflammation-related organ injury by induction of regulatory T cells. Whether regulatory T-cell induction is a potential mechanism of mesenchymal stem cell therapy in ischemic acute kidney injury and how these induced regulatory T cells orchestrate local inflammation are unknown. Here we found that mesenchymal stem cells decrease serum creatinine and urea nitrogen levels, improve tubular injury, and downregulate IFN-? production of T cells in the ischemic kidney. In addition to the lung, mesenchymal stem cells persisted mostly in the spleen. Mesenchymal stem cells increased the percentage of regulatory T cells in the spleen and the ischemic kidney. Antibody-dependent depletion of regulatory T cells blunted the therapeutic effect of mesenchymal stem cells, while coculture of splenocytes with mesenchymal stem cells caused an increase in the percentage of regulatory T cells. Splenectomy abrogated attenuation of ischemic injury, and downregulated IFN-? production and the induction of regulatory T cells by mesenchymal stem cells. Thus, mesenchymal stem cells ameliorate ischemic acute kidney injury by inducing regulatory T cells through interactions with splenocytes. Accumulated regulatory T cells in ischemic kidney might be involved in the downregulation of IFN-? production.
| S-EPMC3778762 | biostudies-literature
Project description:Acute kidney injury is a frequent complication of cardiac surgery and increases morbidity and mortality. As preoperative biomarkers predicting the development of acute kidney injury are not available, we have tested the hypothesis that preoperative plasma levels of endogenous ouabain may function as this type of biomarker.Endogenous ouabain is an adrenal stress hormone associated with adverse cardiovascular outcomes. Its involvement in acute kidney injury is unknown. With studies in patients and animal settings, including isolated podocytes, we tested the above mentioned hypothesis.Preoperative endogenous ouabain was measured in 407 patients admitted for elective cardiac surgery and in a validation population of 219 other patients. We also studied the effect of prolonged elevations of circulating exogenous ouabain on renal parameters in rats and the influence of ouabain on podocyte proteins both "in vivo" and "in vitro."In the first group of patients, acute kidney injury (2.8%, 8.3%, 20.3%, p < 0.001) and ICU stay (1.4±0.38, 1.7±0.41, 2.4±0.59 days, p = 0.014) increased with each incremental preoperative endogenous ouabain tertile. In a linear regression analysis, the circulating endogenous ouabain value before surgery was the strongest predictor of acute kidney injury. In the validation cohort, acute kidney injury (0%, 5.9%, 8.2%, p < 0.0001) and ICU stay (1.2±0.09, 1.4±0.23, 2.2±0.77 days, p = 0.003) increased with the preoperative endogenous ouabain tertile. Values for preoperative endogenous ouabain significantly improved (area under curve: 0.85) risk prediction over the clinical score alone as measured by integrate discrimination improvement and net reclassification improvement. Finally, in the rat model, elevated circulating ouabain reduced creatinine clearance (-18%, p < 0.05), increased urinary protein excretion (+ 54%, p < 0.05), and reduced expression of podocyte nephrin (-29%, p < 0.01). This last finding was replicated ex vivo by incubating podocyte primary cell cultures with low-dose ouabain.Preoperative plasma endogenous ouabain levels are powerful biomarkers of acute kidney injury and postoperative complications and may be a direct cause of podocyte damage.
| S-EPMC3763989 | biostudies-literature
Project description:Current stem cell-based strategies for tissue regeneration involve ex vivo manipulation of these cells to confer features of the desired progenitor population. Recently, the concept that endogenous stem/progenitor cells could be used for regenerating tissues has emerged as a promising approach that potentially overcomes the obstacles related to cell transplantation. Here we applied this strategy for the regeneration of injured tendons in a rat model. First, we identified a rare fraction of tendon cells that was positive for the known tendon stem cell marker CD146 and exhibited clonogenic capacity, as well as multilineage differentiation ability. These tendon-resident CD146+ stem/progenitor cells were selectively enriched by connective tissue growth factor delivery (CTGF delivery) in the early phase of tendon healing, followed by tenogenic differentiation in the later phase. The time-controlled proliferation and differentiation of CD146+ stem/progenitor cells by CTGF delivery successfully led to tendon regeneration with densely aligned collagen fibers, normal level of cellularity, and functional restoration. Using siRNA knockdown to evaluate factors involved in tendon generation, we demonstrated that the FAK/ERK1/2 signaling pathway regulates CTGF-induced proliferation and differentiation of CD146+ stem/progenitor cells. Together, our findings support the use of endogenous stem/progenitor cells as a strategy for tendon regeneration without cell transplantation and suggest this approach warrants exploration in other tissues.
| S-EPMC4563693 | biostudies-literature
Project description:Impact statementThis work provides in-depth insights on catalytic iron-induced cytotoxicity and the resultant triggering of endogenous vitamin D synthesis in experimental acute kidney injury. Our results reveal significantly elevated levels of catalytic iron culminating in oxidant-mediated renal injury and a concomitant increase in 1,25-dihdyroxyvitamin D3 levels. Also, changes in other iron-related proteins including transferrin, ferritin, and hepcidin were observed both in the serum as well as in their mRNA expression. We consider all these findings vital since no connection between catalytic iron and vitamin D has been established so far. Furthermore, we believe that this work provides new and interesting results, with catalytic iron emerging as an important target in ameliorating renal cellular injury, possibly by timely administration of vitamin D. It also needs to be seen if these observations made in rats could be translated to humans by means of robust clinical trials.
| S-EPMC7553091 | biostudies-literature
Project description:Foxp3-expressing CD4+ regulatory T cells (Tregs) make up one subset of the helper T cells (Th) and are one of the major mechanisms of peripheral tolerance. Tregs prevent abnormal activation of the immune system throughout the lifespan, thus protecting from autoimmune and inflammatory diseases. Recent studies have elucidated the role of Tregs beyond autoimmunity. Tregs play important functions in controlling not only innate and adaptive immune cell activation, but also regulate nonimmune cell function during insults and injury. Inflammation contributes to a multitude of acute and chronic diseases affecting the kidneys. This review examines the role of Tregs in pathogenesis of renal inflammatory diseases and explores the approaches for enhancing Tregs for prevention and therapy of renal inflammation.
| S-EPMC6031912 | biostudies-literature
Project description:Acute kidney injury (AKI) is associated with high morbidity and mortality. Recent genetic fate mapping studies demonstrated that recovery from AKI occurs from intrinsic tubular cells. It is unresolved whether these intrinsic cells (so-called "scattered tubular cells") represent fixed progenitor cells or whether recovery involves any surviving tubular cell. Here, we show that the doxycycline-inducible parietal epithelial cell (PEC)-specific PEC-reverse-tetracycline transactivator (rtTA) transgenic mouse also efficiently labels the scattered tubular cell population. Proximal tubular cells labeled by the PEC-rtTA mouse coexpressed markers for scattered tubular cells (kidney injury molecule 1, annexin A3, src-suppressed C-kinase substrate, and CD44) and showed a higher proliferative index. The PEC-rtTA mouse labeled more tubular cells upon different tubular injuries but was independent of cellular proliferation as determined in physiological growth of the kidney. To resolve whether scattered tubular cells are fixed progenitors, cells were irreversibly labeled before ischemia reperfusion injury (genetic cell fate mapping). During recovery, the frequency of labeled tubular cells remained constant, arguing against a fixed progenitor population. In contrast, when genetic labeling was induced during ischemic injury and subsequent recovery, the number of labeled cells increased significantly, indicating that scattered tubular cells arise from any surviving tubular cell. In summary, scattered tubular cells do not represent a fixed progenitor population but rather a phenotype that can be adopted by almost any proximal tubular cell upon injury. Understanding and modulating these phenotypic changes using the PEC-rtTA mouse may lead to more specific therapies in AKI.
| S-EPMC3910599 | biostudies-literature
Project description:Purpose of reviewRecent advances in T cell biology have shed light on the role of T cell subsets in the pathogenesis of acute kidney injury (AKI). The purpose of this review is to harness our understanding of recent advances in T cell biology in tissue injury and repair and provide a mechanistic insight into the role of T cells in the inflammation of AKI.Recent findingsNew specific reagents and genetic animal models have led to advances in our understanding of the role of T cell subsets involved in renal injury. Whereas some T cells promote innate renal inflammation and injury, other T cells promote protection and repair. Recent studies illuminated the pathogenic mechanisms of invariant natural killer T (NKT) cells and T helper1-type responses, and the beneficial functions of regulatory T cells and NKT cells are just beginning to be explored. Pharmacologic and cell-based therapies that influence T cell responses to experimental AKI suggest that this is a promising approach to preserve renal function.SummaryThe recent insights gained into how T cells modulate renal injury suggest that strategies targeting specific types of T cells, to either inhibit or enhance their activity, may ameliorate renal injury in patients.
| S-EPMC3909711 | biostudies-literature
Project description:Dendritic cells (DCs) are critical initiators of innate immunity in the kidney and orchestrate inflammation following ischemia-reperfusion injury. The role of the mammalian/mechanistic target of rapamycin (mTOR) in the pathophysiology of renal ischemia-reperfusion injury has been characterized. However, the influence of DC-based alterations in mTOR signaling is unknown. To address this, bone marrow-derived mTORC2-deficient (Rictor-/-) DCs underwent hypoxia-reoxygenation and then analysis by flow cytometry. Adoptive transfer of wild-type or Rictor-/- DC to C57BL/6 mice followed by unilateral or bilateral renal ischemia-reperfusion injury (20 min ischemia) was used to assess their in vivo migratory capacity and influence on tissue injury. Age-matched male DC-specific Rictor-/- mice or littermate controls underwent bilateral renal ischemia-reperfusion, followed by assessment of renal function, histopathology, and biomolecular and cell infiltration analysis. Rictor-/- DCs expressed more costimulatory CD80/CD86 but less coinhibitory programmed death ligand 1 (PDL1), a pattern that was enhanced by hypoxia-reoxygenation. They also demonstrated enhanced migration to the injured kidney and induced greater tissue damage. Following ischemia-reperfusion, Rictor-/- DC mice developed higher serum creatinine levels, more severe histological damage, and greater proinflammatory cytokine production compared to littermate controls. Additionally, a greater influx of both neutrophils and T cells was seen in Rictor-/- DC mice, along with CD11c+MHCII+CD11bhiF4/80+ renal DC, that expressed more CD86 but less PDL1. Thus, DC-targeted elimination of Rictor enhances inflammation and migratory responses to the injured kidney, highlighting the regulatory roles of both DCs and Rictor in the pathophysiology of acute kidney injury.
| S-EPMC6200603 | biostudies-literature
Project description:BackgroundAcute kidney injury (AKI) is an important complication of cardiac surgery. Recently, elevated levels of endogenous ouabain (EO), an adrenal stress hormone with haemodynamic and renal effects, have been associated with worse renal outcome after cardiac surgery. Our aim was to develop and evaluate a new risk model of AKI using simple preoperative clinical parameters and to investigate the utility of EO.MethodsThe primary outcome was AKI according to Acute Kidney Injury Network stage II or III. We selected the Northern New England Cardiovascular Disease Study Group (NNECDSG) as a reference model. We built a new internal predictive risk model considering common clinical variables (CLIN-RISK), compared this model with the NNECDSG model and determined whether the addition of preoperative plasma EO improved prediction of AKI.ResultsAll models were tested on >800 patients admitted for elective cardiac surgery in our hospital. Seventy-nine patients developed AKI (9.9%). Preoperative EO levels were strongly associated with the incidence of AKI and clinical complication (total ICU stay and in-hospital mortality). The NNECDSG model was confirmed as a good predictor of AKI (AUC 0.74, comparable to the NNECDSG reference population). Our CLIN-RISK model had improved predictive power for AKI (AUC 0.79, CI 95% 0.73-0.84). Furthermore, addition of preoperative EO levels to both clinical models improved AUC to 0.79 and to 0.83, respectively (ΔAUC +0.05 and +0.04, respectively, P < 0.01).ConclusionIn a population where the predictive power of the NNECDSG model was confirmed, CLIN-RISK was more powerful. Both clinical models were further improved by the addition of preoperative plasma EO levels. These new models provide improved predictability of the relative risk for the development of AKI following cardiac surgery and suggest that EO is a marker for renal vascular injury.
| S-EPMC4200038 | biostudies-literature
Project description:To analyze the predictive value of the Th17/Treg ratio for renal injury in sepsis patients, a prospective observational study was conducted. Adult patients with sepsis were enrolled and divided into a sepsis-induced acute kidney injury (SAKI) group and a sepsis-without-AKI group. Logistic regression was used to analyze the independent predictors of SAKI, and the ROC curve was plotted to evaluate the predictive value of the Th17/Treg ratio for renal injury in patients with sepsis. A total of 124 patients were enrolled in this study, including 60 cases (48.39%) of SAKI. Patients who developed sepsis-induced acute kidney injury had a higher Th17/Treg ratio level compared to patients without it (0.11 [0.07, 0.28] versus 0.06 [0.05, 0.16], p < 0.05, respectively. The area under the receiver operating characteristic curve of the Th17/Treg ratio to predict sepsis-induced acute kidney injury was 0.669 (95% CI 0.574-0.763, p < 0.05). The Th17/Treg ratio was associated with SAKI (OR 1.15, 95%CI [1.06-1.24], p < 0.05, non-adjusted and R 1.12, 95%CI [1.00-1.25], p < 0.05, adjusted). The use of the Th17/Treg ratio improved the prediction performance of the prediction model of NAGL. The median Th17/Treg ratio significantly increased with the stratified KDIGO stage (p < 0.05). Th17/Treg imbalance was associated with occurrence of acute kidney injury and AKI severity in patients with sepsis. The Th17/Treg ratio could be a potential predictive marker of sepsis-induced acute kidney injury.
| S-EPMC9320223 | biostudies-literature