Cells In Acute Kidney Injury Research Articles

Lymphocytes and innate immune cells in acute kidney injury and repair.

Acute kidney injury (AKI) is a common and serious disease entity that affects native kidneys and allografts but for which no specific treatments exist. Complex intrarenal inflammatory processes driven by lymphocytes and innate immune cells have key roles in the development and progression of AKI. Many studies have focused on prevention of early injury in AKI. However, most patients with AKI present after injury is already established. Increasing research is therefore focusing on mechanisms of renal repair following AKI and prevention of progression from AKI to chronic kidney disease. CD4+ and CD8+ T cells, B cells and neutrophils are probably involved in the development and progression of AKI, whereas regulatory T cells, double-negative T cells and type 2 innate lymphoid cells have protective roles. Several immune cells, such as macrophages and natural killer T cells, can have both deleterious and protective effects, depending on their subtype and/or the stage of AKI. The immune system not only participates in injury and repair processes during AKI but also has a role in mediating AKI-induced distant organ dysfunction. Targeted manipulation of immune cells is a promising therapeutic strategy to improve AKI outcomes.

Elevated Serum KIM-1 in Sepsis Correlates with Kidney Dysfunction and the Severity of Multi-Organ Critical Illness.

The kidney injury molecule (KIM)-1 is shed from proximal tubular cells in acute kidney injury (AKI), relaying tubular epithelial proliferation. Additionally, KIM-1 portends complex immunoregulation and is elevated after exposure to lipopolysaccharides. It thus may represent a biomarker in critical illness, sepsis, and sepsis-associated AKI (SA-AKI). To characterise and compare KIM-1 in these settings, we analysed KIM-1 serum concentrations in 192 critically ill patients admitted to the intensive care unit. Irrespective of kidney dysfunction, KIM-1 serum levels were significantly higher in patients with sepsis compared with other critical illnesses (191.6 vs. 132.2 pg/mL, p = 0.019) and were highest in patients with urogenital sepsis, followed by liver failure. Furthermore, KIM-1 levels were significantly elevated in critically ill patients who developed AKI within 48 h (273.3 vs. 125.8 pg/mL, p = 0.026) or later received renal replacement therapy (RRT) (299.7 vs. 146.3 pg/mL, p < 0.001). KIM-1 correlated with markers of renal function, inflammatory parameters, hematopoietic function, and cholangiocellular injury. Among subcomponents of the SOFA score, KIM-1 was elevated in patients with hyperbilirubinaemia (>2 mg/dL, p < 0.001) and thrombocytopenia (<150/nL, p = 0.018). In univariate and multivariate regression analyses, KIM-1 predicted sepsis, the need for RRT, and multi-organ dysfunction (MOD, SOFA > 12 and APACHE II ≥ 20) on the day of admission, adjusting for relevant comorbidities, bilirubin, and platelet count. Additionally, KIM-1 in multivariate regression was able to predict sepsis in patients without prior (CKD) or present (AKI) kidney injury. Our study suggests that next to its established role as a biomarker in kidney dysfunction, KIM-1 is associated with sepsis, biliary injury, and critical illness severity. It thus may offer aid for risk stratification in these patients.

#2339 All-trans retinoic acid enhances the efficacy of mesenchymal stem cells in acute kidney injury

Abstract Background and Aims Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic strategy for acute kidney injury (AKI), but still suffer from the drawbacks of low survival rate, low homing rate, and uncertain differentiation. In search of better therapeutic strategies, we explored all-trans retinoic acid (ATRA) pretreatment of MSCs to observe whether it could improve the therapeutic efficacy on AKI. Method We established a renal ischemia/reperfusion (I/R) injury model induced by clamping of left renal artery for 30 minutes and contralateral nephrectomy. C57BL/6 mice were randomly divided into 4 groups: sham group, IRI group, MSCs group, and ATRA-MSCs group. MSCs or ATRA-pretreated MSCs were injected via tail vein. GFR was measured by transcutaneous monitoring the clearance of FITC-sinistrin. These mice were sacrificed 3 days after surgery, and the serum creatinine (SCr) and blood urea nitrogen (BUN) levels were measured. The renal pathological changes were examined by Periodic Acid-Schiff staining (PAS). The in vitro hypoxia/reoxygenation (H/R) model was established using human proximal tubular epithelial cells (HK-2 cells). Co-culturing HK-2 cells with MSCs or ATRA-pretreated MSCs. Western blot, quantitative real time-PCR (qRT-PCR), and immunohistochemistry were used to detect mRNA or protein expression. We performed RNA sequencing (RNA-seq) analysis in ATRA-pretreated MSCs. The content of hyaluronic acid (HA) in the supernatant of ATRA-pretreated MSCs culture was detected by ELISA. Hyaluronan synthase mRNA expression level in ATRA-pretreated MSCs assessed by qRT-PCR analysis. The HAS2 promoter-binding transcription factors were forecasted by the JASPAR Transcription Factor Binding Site database. Western blot was used to detect whether P13K/AKT pathway was activated by ATRA-pretreated MSCs. Whether this nephroprotective effect could be reversed were explored by silencing HAS2 or CD44 antibodies. Results The AKI mice showed a significant decrease in GFR and even complete loss of renal function. Administration of MSCs significantly increased GFR, and MSCs pretreated with ATRA further increased GFR. Mice injected with ATRA-pretreated MSCs had significantly lower levels of SCr, BUN and ATN scores compared with untreated MSCs. Western blot, quantitative real-time PCR (qRT-PCR), and immunohistochemistry showed that ATRA pretreated MSCs were more effective in reducing AKI inflammation and apoptosis and promoting proliferative repair than untreated MSCs. GO enrichment analysis demonstrated that the hyaluronan biosynthetic process may be a significantly expressed. HAS2 expression and HA content of MSCS were significantly increased after the addition of ATRA. Analysis for potential transcription factor binding sites revealed that the HAS2 promoter region has multiple potential binding sites for the retinoic acid receptor. Based on the predictions from the JASPAR database, the RXR-RAR heterodimer had the highest prediction score. We then performed ChIP analysis to experimentally verify the binding of RXR-RAR heterodimer transcription factor to HAS2 promoters. We further found that ATRA-pretreated MSCs activated the PI3K/AKT signaling pathway in AKI. As expected, we found that ATRA-pretreated MSCs anti-inflammatory, anti-apoptosis, and pro-proliferation effects were substantially reversed by silencing HAS2 or blocking CD44. Conclusion ATRA promotes HA secretion from MSCs and activates the PI3K/AKT pathway, which in turn enhances the therapeutic efficacy of MSCs on AKI.

WCN24-944 All-trans retinoic acid enhances the efficacy of mesenchymal stem cells in acute kidney injury

WCN24-944 All-trans retinoic acid enhances the efficacy of mesenchymal stem cells in acute kidney injury

WTAP-mediated N6-methyladenosine modification promotes the inflammation, mitochondrial damage and ferroptosis of kidney tubular epithelial cells in acute kidney injury by regulating LMNB1 expression and activating NF-κB and JAK2/STAT3 pathways.

Acute kidney injury (AKI) is a serious complication of sepsis patients, but the pathogenic mechanisms underlying AKI are still largely unclear. In this view, the roles of the key component of N6-methyladenosine (m6A)-wilms tumor 1 associated protein (WTAP) in AKI progression were investigated. AKI mice model was established by using cecal ligation and puncture (CLP). AKI cell model was established by treating HK-2 cells with LPS. Cell apoptosis was analyzed by TdT-mediated dUTP Nick-End Labeling (TUNEL) staining and flow cytometry analysis. Cell viability was analyzed by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay. The concentrations of inflammatory factors were examined with ELISA kits. Reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH) and Fe2+ levels were detected with related kits. Gene expression was detected by western blot assay or quantitative real-time polymerase chain reaction (qRT-PCR) assay. The relation between WTAP and lamin B1 (LMNB1) was verified by Methylated RNA Immunoprecipitation (meRIP) assay, RIP assay, dual-luciferase reporter assay and Actinomycin D assay. CLP induced significant pathological changes in kidney tissues in mice and promoted inflammation, mitochondrial damage and ferroptosis. LMNB1 level was induced in HK-2 cells by LPS. LMNB1 knockdown promoted LPS-mediated HK-2 cell viability and inhibited LPS-mediated HK-2 cell apoptosis, inflammation, mitochondrial damage and ferroptosis. Then, WTAP was demonstrated to promote LMNB1 expression by m6A Methylation modification. Moreover, WTAP knockdown repressed LPS-treated HK-2 cell apoptosis, inflammation, mitochondrial damage and ferroptosis, while LMNB1 overexpression reversed the effects. Additionally, WTAP affected the pathways of NF-κB and JAK2/STAT3 by LMNB1. WTAP-mediated m6A promoted the inflammation, mitochondrial damage and ferroptosis in LPS-induced HK-2 cells by regulating LMNB1 expression and activating NF-κB and JAK2/STAT3 pathways.

Xanthine oxidase/NADPH oxidase inhibition by hydralazine attenuates acute kidney injury and prevents the transition of acute kidney injury to chronic kidney disease

AimsThe enhancement of inflammation and reactive oxygen species leads to the damage of renal tubular cells in acute kidney injury (AKI), and the upregulation of inflammation increases the risk of AKI being converted into chronic kidney disease (CKD). Hydralazine has shown renoprotective effects in multiple kidney diseases and was shown to be a potent xanthine oxidase (XO) inhibitor. This study aimed to investigate the mechanisms of hydralazine in ischemia–reperfusion (I/R)-stimulated renal proximal tubular epithelial cells in vitro and in AKI animals in vivo. Main methodsThe effects of hydralazine in AKI-to-CKD transition were also evaluated. Human renal proximal tubular epithelial cells were stimulated by I/R conditions in vitro. To generate a mouse model of AKI, a right nephrectomy was performed, followed by left renal pedicle I/R using a small atraumatic clamp. Key findingsIn the in vitro part, hydralazine could protect renal proximal tubular epithelial cells against insults from the I/R injury through XO/NADPH oxidase inhibition. In the in vivo part, hydralazine preserved renal function in AKI mice and improved the AKI-to-CKD transition by decreasing renal glomerulosclerosis and fibrosis independently of blood pressure lowering. Furthermore, hydralazine exerted antioxidant, anti-inflammatory, and anti-fibrotic effects both in vitro and in vivo. SignificanceHydralazine, as a XO/NADPH oxidase inhibitor, could protect renal proximal tubular epithelial cells from the insults of I/R and prevent kidney damage in AKI and AKI-to-CKD. The above experimental studies strengthen the possibility of repurposing hydralazine as a potential renoprotective agent through its antioxidative mechanisms.

LncRNA136131 suppresses apoptosis of renal tubular epithelial cells in acute kidney injury by targeting the miR-378a-3p/Rab10 axis.

The pathogenesis of acute kidney injury (AKI) is not fully understood. To date, the exact role and regulatory mechanism of long non-coding RNA (lncRNA)136131 in AKI remains unclear. Here, we demonstrate that lncRNA136131 in BUMPT cells is induced by antimycin A. Furthermore, after incubating BUMPT cells in antimycin for two hours, lncRNA136131 prevented BUMPT cell apoptosis and cleaved caspase-3 expression. Mechanistically, lncRNA136131 sponged miR-378a-3p and then increased the expression of Rab10 to suppress apoptosis. Finally, I/R-induced decline of renal function, tubular damage, renal tubular cells apoptosis, and the upregulation of cleaved caspase-3 were aggravated by lncRNA136131 siRNA. In contrast, this effect was attenuated by the overexpression of lncRNA136131. In conclusion, lncRNA136131 protected against I/R-induced AKI progression by targeting miR-378a-3p/Rab10 and may be utilized as a novel target for AKI therapeutics.

Therapeutic role of uterine-derived stem cells in acute kidney injury

BackgroundAcute kidney injury (AKI) causes abrupt deterioration in kidney function that disrupts metabolic, electrolyte and fluid homeostasis. Although the prevalence of AKI is steadily increasing, no definitive treatment options are available, leading to severe morbidity and mortality. We evaluated the role of uterine-derived multipotent stem cells in kidney regeneration after ischemic AKI.MethodsFemale C57BL/6J mice were hysterectomized and subsequently subject to AKI by either unilateral or bilateral renal ischemia–reperfusion injury. Uterine-derived cells (UDCs), containing a population of uterine stem cells, were isolated from the uteri of female transgenic DsRed mice and injected intravenously to AKI mice. Engraftment of DsRed cells was analyzed by flow cytometry while serum creatinine levels were determined colorimetrically. Expression of UDC markers and cytokine markers were analyzed by immunohistochemical and qRT-PCR methods, respectively. The Kaplan–Meier method was used to analyze survival time while unpaired t test with Welch’s correction used for data analysis between two groups.ResultsMice with an intact uterus, and hence an endogenous source of UDCs, had a higher survival rate after bilateral ischemic AKI compared to hysterectomized mice. Mice treated with infusion of exogenous UDCs after hysterectomy/AKI had lower serum creatinine levels and higher survival rates compared to controls that did not receive UDCs. Engraftment of labeled UDCs was significantly higher in kidneys of bilateral ischemic AKI mice compared to those that underwent a sham surgery. When unilateral ischemic AKI was induced, higher numbers of UDCs were found in the injured than non-injured kidney. Immunofluorescence staining demonstrated double-positive DsRed/Lotus tetragonolobus agglutinin (LTA) positive cells and DsRed/CD31 positive cells indicating contribution of UDCs in renal tubular and vascular regeneration. Expression of Cxcl12, Bmp2, Bmp4, and Ctnf in renal tissue was significantly higher in the UDCs injection group than the control group.ConclusionsUDCs engrafted injured kidneys, contributed to proximal tubule and vascular regeneration, improved kidney function and increased survival in AKI mice. UDC administration is a promising new therapy for AKI. Endogenous uterine stem cells likely also preserve kidney function, suggesting a novel interaction between the uterus and kidney. We suggest that hysterectomy may have a detrimental effect on response to renal injury.

Deletion of STAT3 from Foxd1 cell population protects mice from kidney fibrosis by inhibiting pericytes trans-differentiation and migration.

Signal transduction and activator of transcription 3 (STAT3) is a key transcription factor implicated in the pathogenesis of kidney fibrosis. Although Stat3 deletion in tubular epithelial cells is known to protect mice from fibrosis, vFoxd1 cells remains unclear. Using Foxd1-mediated Stat3 knockout mice, CRISPR, and inhibitors of STAT3, we investigate its function. STAT3 is phosphorylated in tubular epithelial cells in acute kidney injury, whereas it is expanded to interstitial cells in fibrosis in mice and humans. Foxd1-mediated deletion of Stat3 protects mice from folic-acid- and aristolochic-acid-induced kidney fibrosis. Mechanistically, STAT3 upregulates the inflammation and differentiates pericytes into myofibroblasts. STAT3 activation increases migration and profibrotic signaling in genome-edited, pericyte-like cells. Conversely, blocking Stat3 inhibits detachment, migration, and profibrotic signaling. Furthermore, STAT3 binds to the Collagen1a1 promoter in mouse kidneys and cells. Together, our study identifies a previously unknown function of STAT3 that promotes kidney fibrosis and has therapeutic value in fibrosis.

The Role of Myeloid Cells in Acute Kidney Injury and Kidney Repair.

AKI remains highly prevalent, yet no optimal therapy is available to prevent it or promote recovery after initial insult. Experimental studies have demonstrated that both innate and adaptive immune responses play a central role during AKI. In response to injury, myeloid cells are first recruited and activated on the basis of specific signals from the damaged microenvironment. The subsequent recruitment and activation state of the immune cells depends on the stage of injury and recovery, reflecting a dynamic and diverse spectrum of immunophenotypes. In this review, we highlight our current understanding of the mechanisms by which myeloid cells contribute to injury, repair, and fibrosis after AKI.

Therapeutic potential of extracellular vesicles secreted by adipose tissue-derived mesenchymal stromal cells in acute kidney injury induced by sepsis

Therapeutic potential of extracellular vesicles secreted by adipose tissue-derived mesenchymal stromal cells in acute kidney injury induced by sepsis

Stromal-Cell Deletion of STAT3 Protects Mice from Kidney Fibrosis by Inhibiting Pericytes Trans-Differentiation and Migration

Signal transducer and activator of transcription 3 (STAT3) is a key transcription factor implicated in the pathogenesis of kidney fibrosis. Although tubular Stat3 deletion in tubular epithelial cells is known to protect mice from kidney fibrosis, the exact function of STAT3 in stromal cells remains unknown. We utilized stromal-cell Stat3 knock-out (KO) mice, CRISPR and pharmacologic activators and inhibitors of STAT3 to investigate its function in pericyte-like cells. STAT3 is phosphorylated in tubular epithelial cells in acute kidney injury whereas its activation expanded to interstitial cells in chronic kidney disease in mice and humans. Stromal cell-specific deletion of Stat3 protects mice from folic acid- and aristolochic acid-induced kidney fibrosis. Mechanistically, STAT3 directly regulates the inflammatory pathway, differentiation of pericytes into myofibroblasts. Specifically, STAT3 activation leads to an increase in migration and profibrotic signaling in genome-edited pericyte-like cells, 10T1/2. Conversely, Stat3 KO or blocking STAT3 function inhibits detachment, spreading, migration, and profibrotic signaling. Furthermore, STAT3 binds to Collagen1a1 promoter of fibrotic mouse kidneys and in pericyte-like cells. Together, our study identifies a previously unknown function of STAT3 in stromal cells that promotes kidney fibrosis and may have therapeutic value in fibrotic kidney disease.

LncRNA136131 Suppresses Apoptosis of Renal Tubular Epithelial Cells in Acute Kidney Injury by Targeting the miR -378a-3p/Rab10 Axis

Background: The pathogenesis of acute kidney injury (AKI) is not fully understood. To the data, the exact role and regulation mechanism of Long non-coding RNA (LncRNA) 136131 in AKI remains unclear. Methods: Real-time qPCR to detect the expression level of lncRNA136131 induced by I / R treatment at different time points. In addition, Knockdown or over-expression of lncRNA136131 confirmed its function. The interaction between lncRNA136131 and miR-378a-3p was revealed by bioinformatics analysis RNA FISH assay and Luciferase reporter analysis. The data further showed that lncRNA136131 upregulated Rab10 expression. These results were further confirmed in vivo experiments. Findings: Qe demonstrated that LncRNA 136131 was induced by antimycin incubation of BUMPT cells. after antimycin incubation of BUMPT cells for 2 hours, the data showed that LncRNA 136131 protested against BUMPT cells apoptosis and the expression of cleaved-caspase3. Mechanistically, LncRNA 136131 sponged miR-378a-3p and then increased the expression of Rab10 to suppress apoptosis. Finally, I/R-induced decline of renal function, the tubular damage, renal tubular cells apoptosis, and the increasing of cleaved caspase3 was aggravated by LncRNA 136131 siRNA, by the contrast, this effect was notably attenuated by the overexpression of LncRNA 136131. Interpretation: The data suggest LncRNA 136131 protested against the I/R-induced the progression of AKI via targeting miR-378a-3p/Rab10, which provides a new therapy target of AKI. Funding: The study was supported in part by a grant from National Natural Science Foundation of China [81870475]. The Basic and Frontier Research Program of Chongqing (cstc2017jcyjBX0014). Changsha Science and Technology Bureau project [kq2001039]. Key Project of Hunan provincial science and technology innovation [2020SK1014]. Department of Science and Technology of Hunan Province project of International Cooperation and Exchanges [2020WK2009] .Fundamental Research Funds for the Central Universities of Central South University [2020zzts282]. Declaration of Interest: The authors have declared that no conflict of interest exists. Ethical Approval: C57BL/6J mice were purchased from Shanghai Animal Center (Shanghai, People’s Republic of China). Animal experiments were carried out in accord with the guidelines constructed by the Animal Care Ethics Committee of Second Xiangya Hospital, People’s Republic of China.

Cellular senescence, a novel therapeutic target for mesenchymal stem cells in acute kidney injury

Cellular senescence is a widespread cellular programme that is characterized by permanent cell cycle arrest. Senescent cells adopt a changed secretory phenotype that can alter cellular function. For years, cellular senescence has been thought to be a protective factor against cancer; however, it is now recognized that it has a dual effect on individuals. Co‐ordinated activation of cellular senescence provides advantages during embryogenesis, wound healing, tissue repair and inhibition of tumorigenesis. On the other hand, the aberrant generation and accumulation of abnormal senescent cells lead to the development of age‐related conditions and tissue deterioration. During acute kidney injury (AKI), the kidney faces multiple types of stressors and challenges, which can easily drive cellular senescence. How to appropriately progress through the cell cycle and minimize long‐term damage is of great importance to the acquisition of adaptive repair considering that no available therapeutic interventions can reliably limit injury, speedy recovery or improve the prognosis of this syndrome. Whether the manipulation of cellular senescence can become a novel therapeutic target in AKI and reignite clinical and research interest remains to be determined. Here, we share our current understanding of the role of cellular senescence in AKI, along with examples of the application of mesenchymal stem cells (MSCs) for targeting this disorder during its treatment.

Recent Advances in the Role of Natural Killer Cells in Acute Kidney Injury.

Growing evidence is revealing a central role for natural killer (NK) cells, cytotoxic cells belonging to the broad family of innate lymphoid cells (ILCs), in acute and chronic forms of renal disease. NK cell effector functions include both the recognition and elimination of virus-infected and tumor cells and the capability of sensing pathogens through Toll-like receptor (TLR) engagement. Notably, they also display immune regulatory properties, exerted thanks to their ability to secrete cytokines/chemokines and to establish interactions with different innate and adaptive immune cells. Therefore, because of their multiple functions, NK cells may have a major pathogenic role in acute kidney injury (AKI), and a better understanding of the molecular mechanisms driving NK cell activation in AKI and their downstream interactions with intrinsic renal cells and infiltrating immune cells could help to identify new potential biomarkers and to select clinically valuable novel therapeutic targets. In this review, we discuss the current literature regarding the potential involvement of NK cells in AKI.

Protective function of exosomes from adipose tissue-derived mesenchymal stem cells in acute kidney injury through SIRT1 pathway

AimsTo investigate the protective function of exosomes from adipose tissue-derived mesenchymal stem cells (AMSCs) in sepsis-induced acute kidney injury (AKI) in mice and the possible underlying mechanism in order to provide a theoretical and experimental basis for using exosomes in clinical. Main methodsThe AKI model was prepared through cecal ligation and puncture (CLP). Exosomes were injected via the tail vein of mice. Male C57/BL6 mice (18–22 g; 6-8 weeks old) were randomly grouped. Firstly, after mice were modeled, the variations of inflammatory cytokines and kidney functions at different time points (0, 6, 12, 24 and 48 h) were comprehended. Secondly, mice were divided into Sham, CLP and CLP + Exo, and the survival rates of each group were observed. Lastly, a time point (24 h) was selected for exploring the effect and mechanism of exosomes. The levels of inflammatory cytokines in serum were detected by ELISA, while the kidney was by immunohistochemistry. Kidney histopathological score were analyzed by hematoxylin-eosin (HE) staining. The protein levels of sirtuin 1 (SIRT1), inflammation-related and apoptosis-related were detected by western blot. Key findingsIn CLP group, renal function gradually deteriorated, and the kidneys was in a state of inflammation, apoptosis and microcirculation disorders. However, SIRT1 was activated after intervention of exosomes in CLP mice, which reversed above changes. The mortality was reduced with treatment of exosomes in AKI mice. SignificanceIn mice of sepsis-induce AKI, the intervention of AMSCs derived exosomes played a renal protective effect. The mechanism may be through SIRT1 signaling pathway.

Therapeutic effect of mesenchymal stromal cells in acute kidney injury after hemorrhagic shock

Background & Aim Hemorrhagic shock (HS) is an absolute hypovolemia and an abnormality of the circulatory system secondary to a sudden and significant extravascular blood loss. At the cellular level, the imbalance between systemic oxygen delivery and consumption lead to a transition from aerobic to anaerobic metabolism, lactic acid, inorganic phosphates and oxygen radicals start to accumulate. Release of damage-associated molecular patterns triggers a systemic inflammatory response. As ATP supplies decrease, cellular homeostasis ultimately fails leading to cell death. Among organ failures, acute kidney injury (AKI) affects up to 50% of the patients, is responsible for high morbidity. AKI following HS management is only symptomatic and no etiologic treatment is available. Mesenchymal Stromal Cells (MSC) are multipotent cells found in a large number of adult tissues and used in clinical cell therapy for immunomodulation and tissue repair. Many studies have highlighted their immunomodulatory, anti-apoptotic/anti-oxidative stress or stimulation of endogenous regenerative process by direct contact or by secreting bioactive molecules. Our objective was to evaluate the effect of an early MSC therapy after HS to prevent the onset of AKI. Methods, Results & Conclusion We have developed in vivo HS model. Sprague Dawley rats are subjected to 1h30 of HS at a fixed Mean Arterial Pressure of 35mmHg, followed by resuscitation and retransfusion of spoliated blood. Rat Bone Marrow MSC are intravenously administered at the beginning of the resuscitation phase. Blood gases, lactate and blood glucose are measured at the end of each experimental phase. Biological, histological and transcript analyses are performed at sacrifice, 6h after the end of hemorrhagic phase. Plasma markers indicating AKI (urea, creatinine, cystatin C) increased 6 hours after hemorrhage. The administration of MSC tends to decrease all these markers. Histological scoring of kidney injury and KIM-1 immunostaining (biomarker of tubule injury) are increased in hemorrhagic animals and also shows a tendency to decrease in MSC treated group. Finally, the mRNA levels of IFNγ, IL1β and IL10 increase with hemorrhage and tends to decrease with MSC treatment. Jointly, CD11b/c cell phenotyping in rat blood seems expressed increase activations markers. In conclusion our preliminary results suggest that MSC could prevent kidney damage induced by hemorrhagic shock. Hemorrhagic shock (HS) is an absolute hypovolemia and an abnormality of the circulatory system secondary to a sudden and significant extravascular blood loss. At the cellular level, the imbalance between systemic oxygen delivery and consumption lead to a transition from aerobic to anaerobic metabolism, lactic acid, inorganic phosphates and oxygen radicals start to accumulate. Release of damage-associated molecular patterns triggers a systemic inflammatory response. As ATP supplies decrease, cellular homeostasis ultimately fails leading to cell death. Among organ failures, acute kidney injury (AKI) affects up to 50% of the patients, is responsible for high morbidity. AKI following HS management is only symptomatic and no etiologic treatment is available. Mesenchymal Stromal Cells (MSC) are multipotent cells found in a large number of adult tissues and used in clinical cell therapy for immunomodulation and tissue repair. Many studies have highlighted their immunomodulatory, anti-apoptotic/anti-oxidative stress or stimulation of endogenous regenerative process by direct contact or by secreting bioactive molecules. Our objective was to evaluate the effect of an early MSC therapy after HS to prevent the onset of AKI. We have developed in vivo HS model. Sprague Dawley rats are subjected to 1h30 of HS at a fixed Mean Arterial Pressure of 35mmHg, followed by resuscitation and retransfusion of spoliated blood. Rat Bone Marrow MSC are intravenously administered at the beginning of the resuscitation phase. Blood gases, lactate and blood glucose are measured at the end of each experimental phase. Biological, histological and transcript analyses are performed at sacrifice, 6h after the end of hemorrhagic phase. Plasma markers indicating AKI (urea, creatinine, cystatin C) increased 6 hours after hemorrhage. The administration of MSC tends to decrease all these markers. Histological scoring of kidney injury and KIM-1 immunostaining (biomarker of tubule injury) are increased in hemorrhagic animals and also shows a tendency to decrease in MSC treated group. Finally, the mRNA levels of IFNγ, IL1β and IL10 increase with hemorrhage and tends to decrease with MSC treatment. Jointly, CD11b/c cell phenotyping in rat blood seems expressed increase activations markers. In conclusion our preliminary results suggest that MSC could prevent kidney damage induced by hemorrhagic shock.

High-mobility group box 1 protein antagonizes the immunosuppressive capacity and therapeutic effect of mesenchymal stem cells in acute kidney injury

BackgroundKidney ischemia reperfusion injury (IRI) is a common cause of acute kidney injury and an unavoidable consequence of kidney transplantation and still lacks specific therapeutics. Recently, mesenchymal stem cell (MSC) has been emerging as a promising cell-based therapy for IRI in the context of transplantation. MSC negatively regulates the secretion of pro-inflammatory as well as the activation of immune cells during IRI through its unique immunosuppressive property.MethodsWe employed mice kidney IRI model and MSC cell line to monitor the IRI related checkpoints. siRNAs were utilized to knock down the potential key factors for mechanistic analysis. Statistical analysis was performed by using one-way ANOVA with Tukey’s post hoc procedure by SPSS.ResultsThe expression of high-mobility group box 1 protein (HMGB1) is increased in the acute phase as well as the recovery stage of IRI. Importantly, the HMGB1 upregulation is correlated with the injury severity. HMGB1 diminishes the MSC induced immunosuppressive capacity in the presence of pro-inflammatory cytokines in vitro. Toll like receptor 4 (TLR4)-mediated inducible nitric oxide synthase (iNOS) inhibition contributes to the negative effect of HMGB1 on MSCs. HMGB1-TLR4 signaling inhibition augments the therapeutic efficacy of MSCs in mice renal IRI model.ConclusionsThese findings demonstrate that HMGB1 plays a crucial role in shaping the immunoregulatory property of MSCs within the microenvironments, providing novel insights into the crosstalk between MSCs and microenvironment components, suggesting HMGB1 signals as a promising target to improve MSC-based therapy.

Regulation of Innate Lymphoid Cells in Acute Kidney Injury: Crosstalk between Cannabidiol and GILZ.

Innate lymphoid cells (ILCs) have emerged as largely tissue-resident archetypal cells of the immune system. We tested the hypotheses that renal ischemia-reperfusion injury (IRI) is a contributing factor to polarization of ILCs and that glucocorticoid-induced leucine zipper (GILZ) and cannabidiol regulate them in this condition. Mice subjected to unilateral renal IRI were treated with the following agents before restoration of renal blood flow: cannabidiol, DMSO, transactivator of transcription- (TAT-) GILZ, or the TAT peptide. Thereafter, kidney cells were prepared for flow cytometry analyses. Sham kidneys treated with either cannabidiol or TAT-GILZ displayed similar frequencies of each subset of ILCs compared to DMSO or TAT, respectively. Renal IRI increased ILC1s and ILC3s but reduced ILC2s compared to the sham group. Cannabidiol or TAT-GILZ treatment of IRI kidneys reversed this pattern as evidenced by reduced ILC1s and ILC3s but increased ILC2s compared to their DMSO- or TAT-treated counterparts. While TAT-GILZ treatment did not significantly affect cells positive for cannabinoid receptors subtype 2 (CB2+), cannabidiol treatment increased frequency of both CB2+ and GILZ-positive (GILZ+) cells of IRI kidneys. Subsequent studies showed that IRI reduced GILZ+ subsets of ILCs, an effect less marked for ILC2s. Treatment with cannabidiol increased frequencies of each subset of GILZ+ ILCs, but the effect was more marked for ILC2s. Indeed, cannabidiol treatment increased CB2+ GILZ+ ILC2s. Collectively, the results indicate that both cannabidiol and GILZ regulate ILC frequency and phenotype, in acute kidney injury, and that the effects of cannabidiol likely relate to modulation of endogenous GILZ.

Emerging Roles of Interleukin-33-responsive Kidney Group 2 Innate Lymphoid Cells in Acute Kidney Injury

Interleukin (IL)-33, a member of the IL-1 family of cytokines, is involved in innate and adaptive immune responses. IL-33 triggers pleiotropic immune functions in multiple types of immune cells, which express the IL-33 receptor, ST2. Recent studies have revealed the potential applications of IL-33 for treating acute kidney injury in preclinical animal models. However, IL-33 and IL-33-responding immune cells are reported to exhibit both detrimental and beneficial roles. The IL-33-mediated immunomodulatory functions have been investigated using loss-of-function approaches, such as IL33-deficient mice, IL-33 antagonists, or administration of exogenous IL-33 recombinant protein. This review will discuss the key findings on IL-33-mediated activation of kidney resident group 2 innate lymphoid cells (ILC2s) and summarize the current understanding of the differential functions of endogenous IL-33 and exogenous IL-33 and their potential implications in treating acute kidney injury.