Inflammation In Acute Kidney Injury Research Articles

Acteoside and isoacteoside alleviate renal dysfunction and inflammation in lipopolysaccharide-induced acute kidney injuries through inhibition of NF-κB signaling pathway.

Acute kidney injury (AKI) is a sudden loss of renal function with a high mortality rate and inflammation is thought to be the underlying cause. The phenylpropanoid components acteoside (ACT) and isoacteoside (ISO), which were isolated from Cistanche deserticola Y.C.Ma, have been reported to have preventive effects against kidney disorders. This study aimed to investigate the anti-inflammatory properties and protective mechanisms of ACT and ISO. In this investigation, kidney function was assessed using a semi-automatic biochemical analyzer, histopathology was examined using Hematoxylin-Eosin staining and immunohistochemistry, and the concentration of inflammatory cytokines was assessed using an enzyme-linked immunosorbent assay (ELISA) test. In addition, using Western blot and q-PCR, the expression of proteins and genes connected to the NF-κB signaling pathway in mice with lipopolysaccharide (LPS)-induced AKI was found. The findings showed that under AKI intervention in LPS group, ACT group and ISO group, the expression of Rela (Rela gene is responsible for the expression of NFκB p65 protein) and Tlr4 mRNA was considerably elevated (P<0.01), which led to a significant improvement in the expression of MyD88, TLR4, Iκ-Bɑ and NF-κB p65 protein (P<0.001). The levels of Alb, Crea and BUN (P<0.001) increased along with the release of downstream inflammatory factors such as IL-1β, IL-6, Cys-C, SOD1 and TNF-α (P<0.001). More importantly, the study showed that ISO had a more favorable impact on LPS-induced AKI mice than ACT. In conclusion, by inhibiting NF-κB signaling pathway, ACT and ISO could relieve renal failure and inflammation in AKI, offering a fresh possibility for the therapeutic management of the condition.

Derangement in Nicotinamide Adenine Dinucleotide Metabolism is Observed During Acute Kidney Injury Among Male Agricultural Workers at Risk for Mesoamerican Nephropathy

IntroductionMesoamerican Nephropathy (MeN) is a chronic kidney disease (CKD) which may be caused by recurrent acute kidney injury (AKI). We investigated urinary quinolinate to tryptophan ratio (Q/T), a validated marker of nicotinamide adenine dinucleotide (NAD+) biosynthesis elevated during ischemic and inflammatory AKI, in a sugarcane worker population with high rates of MeN in Nicaragua. MethodsAmong 693 male sugarcane workers studied, we identified 45 who developed AKI during the harvest season. We matched them 1:1 based on age and job category with two comparison groups: (1) “no kidney injury,” active sugarcane workers with serum creatinine <1.1mg/dL; and (2) “CKD,” individuals no longer working in sugarcane due to their CKD, who had additional 1:1 matching for serum creatinine. We measured urine metabolites using liquid chromatography-coupled tandem mass spectrometry, and compared Q/T and other metabolic features between the AKI and comparison groups. ResultsUrine Q/T was significantly higher in workers with AKI than in those with no kidney injury (median [IQR] 0.104 [0.074-0.167] vs 0.060 [0.045-0.091], P < 0.0001) and marginally higher than in workers with CKD (0.086 (0.063-0.142), P = 0.059). Urine levels of the NAD+ precursor nicotinamide were lower in the AKI group than in comparison groups. ConclusionWorkers at risk for MeN who develop AKI demonstrate features of impaired NAD+ biosynthesis, providing new insights into the metabolic mechanisms of injury in this population. Therapeutic use of oral nicotinamide, which may ameliorate NAD+ biosynthetic derangement and fortify against kidney injury, should be investigated to prevent AKI in this setting.

STING antagonist-loaded renal tubule epithelial cell-mimicking nanoparticles ameliorate acute kidney injury by orchestrating innate and adaptive immunity

Inflammatory responses profoundly contribute to the development of renal damage in acute kidney injury (AKI), a frequent clinical syndrome with high morbidity and mortality. However, the effects of existing strategies aiming to suppress the inflammation in AKI remain unsatisfactory due to the inability to simultaneously regulate innate and adaptive immune responses. Here, STING antagonist-loaded renal tubule epithelial cell membrane-coated nanoparticles (SNP@TEC) are developed to ameliorate AKI by orchestrating innate and adaptive immunity. As the reservation of cell membrane αV integrin, biomimetic SNP@TEC are able to target renal tubules via homotypic tropism. The carried antagonist can suppress innate immune responses through relieving STING-triggered inflammatory reaction and repolarizing macrophages to the anti-inflammatory M2 phenotype. Owing to the presence of cell membrane PD-L1, SNP@TEC can also elicit an anti-inflammatory adaptive immune response by blocking the CD80 on dendritic cells to inhibit T-cell activation. In two murine models of AKI induced by cisplatin or ischemia/reperfusion, systemic injection with SNP@TEC significantly alleviates renal damage and restores renal function. In a prophylactic model, SNP@TEC effectively prevent the transition of AKI to chronic kidney disease. SNP@TEC propose a unique approach to orchestrate innate and adaptive immunity, opening a window to remit inflammation for treating renal injury.

#5165 STING CONTRIBUTES TO LPS-INDUCED TUBULAR INFLAMMATION BY ACTIVATING IRE1/XBP1 PATHWAY IN ACUTE KIDNEY INJURY

Abstract Background and Aims Innate immunity and inflammation were recognized as the key factors for the progression of acute kidney injury (AKI) induced by lipopolysaccharide (LPS). Stimulator of interferon genes (STING) has emerged as a critical component of innate immune and inflammatory responses. This study aimed to explore the role of STING in LPS-induced tubular inflammation in AKI. Method 1. The AKI mice models were induced by intraperitoneal injection of LPS. Mice were randomly divided into CTL group, LPS 24 h group and LPS 48 h group: (1) STING protein expression in tubules was detected by IHC staining; (2) STING protein expression in kidney cortices was detected by WB. 2. The tubule-specific STING knockout (STING-cKO) mice were generated. Then WT mice and STING-cKO mice were randomly divided into WT group, WT+LPS group, STING-cKO group and STING-cKO+LPS group: (1) Blood samples and urine samples were collected for Scr, BUN and ACR measurement; (2) Tubular pathological changes were detected by PAS staining; (3) Inflammatory cell infiltration in kidney cortices was detected by IHC and IF staining; (4) Pro-inflammatory cytokines’ mRNA level in kidney cortices was detected by QPCR; (5) IRE1, XBP1, IL-1β and IL-18 protein expression in kidney cortices was detected by WB. 3. HK2 cells were randomly divided into CTL group, si-STING (STING siRNA) group, LPS group, LPS+si-STING group, Ad-IRE1 (IRE1 overexpression plasmid) group, si-STING+ Ad-IRE1 group, LPS+ Ad-IRE1 group and LPS+ si-STING+ Ad-IRE1 group: (1) Pro-inflammatory cytokines’ mRNA level was detected by QPCR; (2) IL-1β, IL-18 protein expression was detected by WB. Results 1. STING was activated in tubules from LPS-induced AKI mice. 2. STING-cKO significantly suppressed LPS-induced renal dysfunction, tubular pathological changes, tubular inflammation and IRE1/XBP1 pathway activation. 3.IRE1 overexpression significantly promoted LPS-activated HK2 cells’ inflammation, even though STING was silenced. Conclusion STING contributes to LPS-induced tubular inflammation by activating IRE1/XBP1 pathway. Targeting STING may be a promising therapeutic strategy for preventing septic AKI.

Circular RNA_HIPK3-Targeting miR-93-5p Regulates KLF9 Expression Level to Control Acute Kidney Injury.

Acute kidney injury (AKI) is a clinical syndrome caused by various reasons that results in the rapid decline of renal function in a short period of time. Severe AKI can lead to multiple organ dysfunction syndrome. Circular RNA HIPK3 (circHIPK3) derived from the HIPK3 gene is involved in multiple inflammatory processes. The present research was performed to explore the function of circHIPK3 on AKI. The AKI model was established by ischemia/reperfusion (I/R) in C57BL/6 mice or hypoxia/reoxygenation (H/R) in HK-2 cells. The function and mechanism of circHIPK3 on AKI were explored via biochemical index measurement; hematoxylin and eosin (HE) staining; 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT); flow cytometry; enzyme-linked immunosorbent assay (ELISA); western blot; quantitative real-time polymerase chain reaction (RT-qPCR); detection of reactive oxygen species (ROS) and adenosine triphosphate (ATP); and luciferase reporter assays. circHIPK3 was upregulated in kidney tissues of I/R-induced mice and in H/R-treated HK-2 cells, while the microRNA- (miR-) 93-5p level was decreased in H/R-stimulated HK-2 cells. Furthermore, circHIPK3 silencing or miR-93-5p overexpression could reduce the level of proinflammatory factors and oxidative stress and recover the cell viability in H/R-stimulated HK-2 cells. Meanwhile, the luciferase assay showed that Krüppel-like transcription factor 9 (KLF9) was the downstream target of miR-93-5p. Forced expression of KLF9 blocked the function of miR-93-5p on H/R-treated HK-2 cells. Knockdown of circHIPK3 improved the renal function and reduced the apoptosis level in vivo. In conclusion, circHIPK3 knockdown alleviated oxidative stress and apoptosis and inhibited inflammation in AKI via miR-93-5p-mediated downregulation of the KLF9 signal pathway.

PS-B08-9: INHIBITION OF PERIOSTIN PROTECTED FROM EXACERBATION OF INFLAMMATION IN RHABDOMYOLYSIS-INDUCED ACUTE KIDNEY INJURY

Objective: Rhabdomyolysis is the breakdown of damaged skeletal muscle and the leakage of muscle-cell contents, including myoglobin, and other sarcoplasmic proteins into the circulation. These products may be filtered through the glomeruli, leading to acute kidney injury (AKI) via several mechanisms, such as inflammation and intratubular obstruction secondary to protein precipitation. New therapeutic strategy to lessen AKI are urgently needed. Thus far, several cellular pathways, nuclear factor kappa beta (NF-KB) as well as including pro-inflammatory effects on epithelial and tubular epithelial cells, have been identified as the major avenues for the initiation of the matrix-producing cells in AKI. Recently, it is suggested that periostin, extracellular matrix, is involved in the development of inflammation through the modulation of NF-KB pathway. However, periostin on the progression of the inflammation protection in AKI due to rhabdomyolysis is unclear. This study aimed to investigate the role of periostin in a rhabdomyolysis mice model of AKI. Design and method: In vivo, rhabdomyolysis-induced AKI was created by an intramuscular injection of 50% glycerol (5 mg/kg body weight). The expression level of periostin during the progression of acute renal failure after glycerol intramuscular injection for C57BL/6J wild type (WT) mice model was investigated. The mice were sacrificed at 72 hours after glycerol injection. We have developed periostin null mice to examine the role of periostin on acute renal failure. The role of periostin were further investigated through in vitro methods. In vitro, the development of renal inflammation is associated with NF-KB pathway. To investigate the function of periostin, we administrated Hemin(100uM) on NIH-3T3 fibroblast cells and the subsequent signaling pathways was examined. Results: The expression of periostin was highly increased, peaking at approximately 72 hours after gycerol injection. Inflammation-associated mRNA such as Monocyte Chemotactic Protein-1, tumor necrosis factor-alpha and IL6 expression and tubular injury score in H-E staining was more reduced in periostin null mice than WT mice at 72 hours after gycerol injection. Finally, an intraperitoneal injection of periostin antibody suppressed the mortality. These findings suggest a causal link between periostin and inflammation in AKI induced by rhabdomyolysis. In addition, an intraperitoneal injection of antibody for periostin antibody might be a new therapeutic strategy against the development of AKI induced by rhabdomyolysis. Conclusions: Periostin were highly expressed in kidney via rhabdomyolysis, and were a positive regulator of AKI. Targeting periostin might offer a new therapeutic strategy against the development of renal failure.

Abstract 14940: Neonatal Cardiac Mesenchymal Stem Cells Target ERK/MAPK Signaling Pathway to Ameliorate Oxidative Stress and Inflammation in Acute Kidney Injury

Introduction: Failure of multidrug therapy and the multifactorial nature of kidney injury has paved the path way regenerative medicine with over 45 clinical trials using stem cells-based therapy underway. Neonatal cardiac mesenchymal stem cells (nMSC) are one of the most potent stem cells due to their secretome. HYPOTHESIS: SOD2 and anti-inflammatory miRNAs (miR-214 &amp; 95p) in paracrine secretions (secretome) of nMSC provides renoprotection in a rodent model of glycerol-induced AKI. Methods: nMSC were generated from neonatal myocardium using enzymatic digestion and antibodies-based selection. Secretome was collected by conditioning nMSCs for 72 hours in serum free basal medium. Human kidney cells (HKC) were used for in vitro anti-oxidation assays using cisplatin. THP-1 cells were used for anti-inflammatory assessment. CD1 mice were used for glycerol-induced AKI model. Mice were subjected to AKI via IM glycerol (9mg/kg). nMSC-derived secretome was intravenously administered immediately after, or 4 hours post-glycerol. Blood urea nitrogen (BUN) and creatinine were analyzed in serum. Cell survival/KIM1 was assessed by immunohistology/FACS. Other experiments utilized cisplatin toxicity in HKC. Results: Administration of nMSC secretome (5 or 10mg/kg) at the same time or 4-hours post-glycerol administration significantly reduced serum creatinine and BUN in a glycerol induced AKI animal model. Caspase-9 and KIM1 expression was significantly decreased in tubular cells as compared to placebo at a dose of 10mg/kg. KIM-1 was significantly downregulated as compared to placebo following nMSC-secretome administration. Western blot analysis of HKC treated with cisplatin in presence of nMSC-secretome showed significant reduction in NFkb and pERK expression (p&lt;0.05) at 200 μg/ml of nMSC-secretome. IL-8 secretion from macrophages was significantly decreased by nMSC-secretome. Data showing the role of miR-210 in renoprotection will also be shown. Conclusion: nMSC and nMSC-derived secretome provide a renoprotective effect in the setting of glycerol-induced AKI. The mechanism of this effect is driven, at least in part, by a reduction in NfκB and pERK related signaling.

Phosphoglycerate mutase 5 initiates inflammation in acute kidney injury by triggering mitochondrial DNA release by dephosphorylating the pro-apoptotic protein Bax

Acute kidney injury (AKI) is a worldwide public health problem characterized by excessive inflammation with no specific therapy in clinic. Inflammation is not only a feature of AKI but also an essential promoter for kidney deterioration. Phosphoglycerate mutase 5 (PGAM5) was up-regulated and positively correlated with kidney dysfunction in human biopsy samples and mouse kidneys with AKI. PGAM5 knockout in mice significantly alleviated ischemia/reperfusion-induced kidney injury, mitochondrial abnormality and production of inflammatory cytokines. Elevated PGAM5 was found to be mainly located in kidney tubular epithelial cells and was also related to inflammatory response. Knockdown of PGAM5 inhibited the hypoxia/reoxygenation-induced cytosolic release of mitochondrial DNA (mtDNA) and binding of mtDNA with the cellular DNA receptor cGAS in cultured cells. cGAS deficiency also attenuated the inflammation and kidney injury in AKI. Mechanistically, as a protein phosphatase, PGAM5 was able to dephosphorylate the pro-apoptotic protein Bax and facilitate its translocation to mitochondrial membranes, and then initiate increased mitochondrial membrane permeability and release of mtDNA. Leaked mtDNA recognized by cGAS then initiated its downstream-coupled STING pathway, a component of the innate immune system that functions to detect the presence of cytosolic DNA. Thus, our results demonstrated mtDNA release induced by PGAM5-mediated Bax dephosphorylation and the activation of cGAS-STING pathway as critical determinants of inflammation and kidney injury. Hence, targeting this axis may be useful for treating AKI.

Essential Roles of the Histone Demethylase KDM4C in Renal Development and Acute Kidney Injury.

Background: Lysine demethylase 4C (KDM4C) is a nuclear protein that is essential for histone modification and acts as an important regulator of several transcription factors. Previous studies have shown that KDM4C may also play a role in mediating stress responses. The purpose of this study was to examine the roles of KDM4C in kidney development and acute kidney injury (AKI). Methods: The effect of KDM4C on kidney development was assessed by comparing the kidney phenotype between 96 zebrafish embryos treated with kdm4c-morpholino oligonucleotide and 96 untreated zebrafish embryos. We further examined whether KDM4C is essential for maintaining cell survival in AKI. Cultured human renal tubular cells were used for the in vitro study. Wild-type and Kdm4c knockout mice (C57BL/6NTac-Kdm4ctm1a(KOMP)Wtsi) were divided into a sham group and model group, and then subjected to ischemic reperfusion kidney injury (IRI-AKI). Blood samples and kidneys were collected at different time points (day 3, day 7, day 14, and day 28) and were processed for in vivo studies (n = 8 in each group). Results: Kdm4c knockdown significantly decreased zebrafish embryo survival and impaired kidney development. The in vitro study showed that KDM4C inhibition by JIB04 significantly increased cellular apoptosis under oxidative stress conditions. KDM4C knockdown cells had impaired autophagy function under stress conditions. The IRI-AKI mice study showed that KDM4C protein levels dynamically changed and were significantly correlated with HIF-1α levels in AKI. Kdm4c−/− mice had significantly more severe renal impairment and increased kidney fibrosis than the wild-type mice. Cytokine array results also indicated that the kidneys of Kdm4c−/− mice had increased inflammation in AKI compared with the wild-type mice. Further RNA sequence analysis revealed that KDM4C may regulate transcription factors related to mitochondrial dynamics and function. Conclusions: Our study suggests that KDM4C may play a critical role in regulating mitochondria, which is related to a protective effect on maintaining cell survival in AKI.

Inhibition of Circ-Snrk ameliorates apoptosis and inflammation in acute kidney injury by regulating the MAPK pathway

Background Circular RNA (circRNA) is involved in the process of acute kidney injury (AKI), but only a few circRNAs have been reported. In the study, we investigated a new circRNA and its association with AKI. Methods An AKI model was established in Sprague-Dawley rats, followed by serum creatinine and urea nitrogen tests measured by a biochemical analyzer. The pathological changes and apoptosis in the renal tissue were detected by Hematoxylin and Eosin, and TUNEL staining. Then, circRNA expression in AKI was determined by quantitative real-time-PCR (qRT-PCR). NRK-52E cells were induced with hypoxia/reoxygenation (H/R) as in vitro models and the circ-Snrk level was tested by qRT-PCR. The effects of circ-Snrk in H/R-induced NRK-52E cells were assessed by flow cytometry, western blot, and enzyme-linked immunosorbent assay. Finally, RNA sequencing and western blot analysis were used to validate the mRNA profile and pathways involved in circ-Snrk knockdown in H/R-induced NRK-52E. Results A reliable AKI rat model and H/R cell model were established. qRT-PCR demonstrated that circ-Snrk level was upregulated in AKI left kidney tissue and NRK-52E cells with H/R treatment. Circ-Snrk knockdown inhibited apoptosis of NRK-52E cells and secretion of inflammatory factors (IL-6 and TNF-α). RNA sequencing showed that the mRNA profile changed after inhibition of circ-Snrk and differential expression of mRNA mainly enriched various signaling pathways, including MAPK signaling pathway. Furthermore, western blot indicated that circ-Snrk knockdown could inhibit the activation of p-JNK and p-38 transcription factors. Conclusions Circ-Snrk is involved in AKI development and associated with the MAPK signaling pathway in AKI.

Single Cell RNA Sequencing Identifies a Unique Inflammatory Macrophage Subset as a Druggable Target for Alleviating Acute Kidney Injury (Adv. Sci. 12/2022)

Alleviating Acute Kidney Injury In article number 2103675, Ying Chen, Fan Bai, Li Yang, and co-workers revealed S100a8/a9high infiltrated macrophage initiated and amplified inflammation in acute kidney injury. The “Comets” represent S100a8/a9high infiltrated macrophages which derive from bone marrow, response the earliest to the signals sent by the injured kidney, infiltrate and cause further damage to the kidney (the kidney with flame). Two small molecule drugs (little cartoon people in light or dark blue color) which specifically inhibit S100a8/a9, could reduce renal inflammation and protect kidney from acute injury (the kidney without flame).

Bone Marrow-Derived RIPK3 Mediates Kidney Inflammation in Acute Kidney Injury.

Receptor-interacting protein kinase 3 (RIPK3), a component of necroptosis pathways, may have an independent role in inflammation. It has been unclear which RIPK3-expressing cells are responsible for the anti-inflammatory effect of overall Ripk3 deficiency and whether Ripk3 deficiency protects against kidney inflammation occurring in the absence of tubular cell death. We used chimeric mice with bone marrow from wild-type and Ripk3-knockout mice to explore RIPK3's contribution to kidney inflammation in the presence of folic acid-induced acute kidney injury AKI (FA-AKI) or absence of AKI and kidney cell death (as seen in systemic administration of the cytokine TNF-like weak inducer of apoptosis [TWEAK]). Tubular and interstitial cell RIPK3 expressions were increased in murine AKI. Ripk3 deficiency decreased NF-κB activation and kidney inflammation in FA-AKI but did not prevent kidney failure. In the chimeric mice, RIPK3-expressing bone marrow-derived cells were required for early inflammation in FA-AKI. The NLRP3 inflammasome was not involved in RIPK3's proinflammatory effect. Systemic TWEAK administration induced kidney inflammation in wild-type but not Ripk3-deficient mice. In cell cultures, TWEAK increased RIPK3 expression in bone marrow-derived macrophages and tubular cells. RIPK3 mediated TWEAK-induced NF-κB activation and inflammatory responses in bone marrow-derived macrophages and dendritic cells and in Jurkat T cells; however, in tubular cells, RIPK3 mediated only TWEAK-induced Il-6 expression. Furthermore, conditioned media from TWEAK-exposed wild-type macrophages, but not from Ripk3-deficient macrophages, promoted proinflammatory responses in cultured tubular cells. RIPK3 mediates kidney inflammation independently from tubular cell death. Specific targeting of bone marrow-derived RIPK3 may limit kidney inflammation without the potential adverse effects of systemic RIPK3 targeting.

POS-058 THE CORRELATION BETWEEN C-REACTIVE PROTEIN AND ACUTE KIDNEY INJURY IN PATIENTS WITH SEPSIS

Acute kidney injury (AKI) is a syndrome characterized by a sudden decrease in kidney function. Global estimates suggest that 13 million people have AKI every years. C-reactive protein (CRP) is a protein that appears in the acute phase and is a marker of inflammation. Several studies have shown that there is an increasing CRP levels in AKI patients, so CRP is proposed as a biomarker of inflammation in AKI. This study aims to examine the relationship between CRP levels with AKI in patients with sepsis.

Rhodomeroterpene alleviates macrophage infiltration and the inflammatory response in renal tissue to improve acute kidney injury.

Inflammation is broadly recognized as an important factor in the pathogenesis of acute kidney injury (AKI), but pharmacological approaches to alleviate inflammation in AKI have not been proved successful in clinical trials. Macrophage infiltration into renal tissue promotes inflammatory responses that contribute to the pathogenesis of AKI. Suppression of renal tissue inflammatory responses is postulated to improve renal injury of patients and animals. Rhodomeroterpene (RMT) is a novel meroterpenoid isolated from the Rhododendron genus that was shown to exert anti-inflammatory action in vivo or in vitro in this study. We investigated the treatment effects of RMT on LPS-induced sepsis and two different AKI models. The results showed that pretreatment with RMT (30mgkg-1 d-1 , ip, for 3days) significantly inhibited acute inflammatory responses in LPS-induced septic mice. In both renal ischemia-reperfusion injury (I/R) and sepsis-induced AKI models, RMT (30mgkg-1 d-1 , ip, for 3days) ameliorated renal function and injury and alleviated inflammation by reducing the infiltration of immune cells, including macrophages and neutrophils. Furthermore, our study demonstrated that RMT inhibits inflammatory responses in macrophages. The anti-inflammatory effects of RMT may be due to the inactivation of the IKK/NF-κB and PI3K/PDK1/Akt inflammatory signaling pathways in macrophages. Collectively, our findings indicate that RMT ameliorates renal injury and alleviates the renal inflammatory state in different AKI models, suggesting that RMT may be a potential agent for the treatment of AKI.

Acute Kidney Injury Model Induced by Cisplatin in Adult Zebrafish.

Cisplatin is commonly used as chemotherapy. Although it has positive effects in cancer-treated individuals, cisplatin can easily accumulate in the kidney due to its low molecular weight. Such accumulation causes the death of tubular cells and can induce the development of Acute Kidney Injury (AKI), which is characterized by a quick decrease in kidney function, tissue damage, and immune cells infiltration. If administered in specific doses cisplatin can be a useful tool as an AKI inducer in animal models. The zebrafish has appeared as an interesting model to study renal function, kidney regeneration, and injury, as renal structures conserve functional similarities with mammals. Adult zebrafish injected with cisplatin shows decreased survival, kidney cell death, and increased inflammation markers after 24 h post-injection (hpi). In this model, immune cells infiltration and cell death can be assessed by flow cytometry and TUNEL assay. This protocol describes the procedures to induce AKI in adult zebrafish by intraperitoneal cisplatin injection and subsequently demonstrates how to collect the renal tissue for flow cytometry processing and cell death TUNEL assay. These techniques will be useful to understand the effects of cisplatin as a nephrotoxic agent and will contribute to the expansion of AKI models in adult zebrafish. This model can also be used to study kidney regeneration, in the search for compounds that treat or prevent kidney damage and to study inflammation in AKI. Moreover, the methods used in this protocol will improve the characterization of tissue damage and inflammation, which are therapeutic targets in kidney-associated comorbidities.

Acute Kidney Injury Model Induced by Cisplatin in Adult Zebrafish

Cisplatin is commonly used as chemotherapy. Although it has positive effects in cancer-treated individuals, cisplatin can easily accumulate in the kidney due to its low molecular weight. Such accumulation causes the death of tubular cells and can induce the development of Acute Kidney Injury (AKI), which is characterized by a quick decrease in kidney function, tissue damage, and immune cells infiltration. If administered in specific doses cisplatin can be a useful tool as an AKI inducer in animal models. The zebrafish has appeared as an interesting model to study renal function, kidney regeneration, and injury, as renal structures conserve functional similarities with mammals. Adult zebrafish injected with cisplatin shows decreased survival, kidney cell death, and increased inflammation markers after 24 h post-injection (hpi). In this model, immune cells infiltration and cell death can be assessed by flow cytometry and TUNEL assay. This protocol describes the procedures to induce AKI in adult zebrafish by intraperitoneal cisplatin injection and subsequently demonstrates how to collect the renal tissue for flow cytometry processing and cell death TUNEL assay. These techniques will be useful to understand the effects of cisplatin as a nephrotoxic agent and will contribute to the expansion of AKI models in adult zebrafish. This model can also be used to study kidney regeneration, in the search for compounds that treat or prevent kidney damage and to study inflammation in AKI. Moreover, the methods used in this protocol will improve the characterization of tissue damage and inflammation, which are therapeutic targets in kidney-associated comorbidities.

Eriocitrin attenuates ischemia reperfusion-induced oxidative stress and inflammation in rats with acute kidney injury by regulating the dual-specificity phosphatase 14 (DUSP14)-mediated Nrf2 and nuclear factor-κB (NF-κB) pathways.

BackgroundIschemia reperfusion (IR)-induced acute kidney injury (AKI) is accompanied by increased inflammatory response and oxidative stress. Eriocitrin is a flavonoid that is mainly derived from lemon or citrate juice. It exhibits various pharmacological effects and is known to have antioxidant and anti-steatotic benefits. However, research on the effect of eriocitrin against IR-induced oxidative stress and inflammation in AKI is limited.MethodsIn this study, an OGD/R of HK-2 cell in vitro and rat model of AKI in vivo were constructed. Then the cell or rats were treated with eriocitrin at different doses (60, 30, 10 mg/kg). The levels of apoptotic were detected by flow cytometry. Inflammatory and oxidative stress factors in supernatant in vitro and tissue in vivo. Meanwhile, Western blot was used to detect the change of dual-specificity phosphatase 14 (DUSP14), Nrf2 and nuclear factor-κB (NF-κB).ResultsEriocitrin attenuated apoptosis of the human renal tubular epithelial cell line HK-2 mediated by oxygen glucose deprivation/reperfusion via the repression of inflammation and oxidative stress in a dose-dependent manner. Eriocitrin also enhanced the levels of dual-specificity phosphatase 14 (DUSP14) and Nrf2, and decreased NF-κB phosphorylation. Furthermore, the in vivo experiments indicated that eriocitrin dose-dependently alleviated IR-induced AKI and apoptosis in rats. By elevating DUSP14, eriocitrin promoted the expression of Nrf2 and inactivated NF-κB, thereby downregulating inflammation and oxidative stress. Moreover, inhibiting DUSP14 expression with protein tyrosine phosphatase (PTP) inhibitor IV reversed the kidney-protective effects of Eriocitrin.ConclusionsEriocitrin protected IR-induced AKI by attenuating oxidative stress and inflammation via elevating DUSP14, thereby providing a theoretical basis for the treatment of IR-induced AKI.

Toll-Like Receptors in Acute Kidney Injury.

Acute kidney injury (AKI) is an important health problem, affecting 13.3 million individuals/year. It is associated with increased mortality, mainly in low- and middle-income countries, where renal replacement therapy is limited. Moreover, survivors show adverse long-term outcomes, including increased risk of developing recurrent AKI bouts, cardiovascular events, and chronic kidney disease. However, there are no specific treatments to decrease the adverse consequences of AKI. Epidemiological and preclinical studies show the pathological role of inflammation in AKI, not only at the acute phase but also in the progression to chronic kidney disease. Toll-like receptors (TLRs) are key regulators of the inflammatory response and have been associated to many cellular processes activated during AKI. For that reason, a number of anti-inflammatory agents targeting TLRs have been analyzed in preclinical studies to decrease renal damage during AKI. In this review, we updated recent knowledge about the role of TLRs, mainly TLR4, in the initiation and development of AKI as well as novel compounds targeting these molecules to diminish kidney injury associated to this pathological condition.

Mitochondrial DNA-Mediated Inflammation in Acute Kidney Injury and Chronic Kidney Disease.

The integrity and function of mitochondria are essential for normal kidney physiology. Mitochondrial DNA (mtDNA) has been widely a concern in recent years because its abnormalities may result in disruption of aerobic respiration, cellular dysfunction, and even cell death. Particularly, aberrant mtDNA copy number (mtDNA-CN) is associated with the development of acute kidney injury and chronic kidney disease, and urinary mtDNA-CN shows the potential to be a promising indicator for clinical diagnosis and evaluation of kidney function. Several lines of evidence suggest that mtDNA may also trigger innate immunity, leading to kidney inflammation and fibrosis. In mechanism, mtDNA can be released into the cytoplasm under cell stress and recognized by multiple DNA-sensing mechanisms, including Toll-like receptor 9 (TLR9), cytosolic cGAS-stimulator of interferon genes (STING) signaling, and inflammasome activation, which then mediate downstream inflammatory cascades. In this review, we summarize the characteristics of these mtDNA-sensing pathways mediating inflammatory responses and their role in the pathogenesis of acute kidney injury, nondiabetic chronic kidney disease, and diabetic kidney disease. In addition, we highlight targeting of mtDNA-mediated inflammatory pathways as a novel therapeutic target for these kidney diseases.

BAY61-3606 protects kidney from acute ischemia/reperfusion injury through inhibiting spleen tyrosine kinase and suppressing inflammatory macrophage response.

Acute kidney injury (AKI) is a highly prevalent clinical syndrome with high mortality and morbidity. Previous studies indicated that inflammation promotes tubular damage and plays a key role in AKI progress. Spleen tyrosine kinase (Syk) has been linked to macrophage-related inflammation in AKI. Up to date, however, no Syk-targeted therapy for AKI has been reported. In this study, we employed both cell model of LPS-induced bone marrow-derived macrophage (BMDM) and mouse model of ischemia/reperfusion injury (IRI)-induced AKI to evaluate the effects of a Syk inhibitor, BAY61-3606 (BAY), on macrophage inflammation in vitro and protection of kidney from AKI in vivo. The expression and secretion of inflammatory cytokines, both in vitro and in vivo, were significantly inhibited even back to normal levels by BAY. The upregulated serum creatinine and blood urea nitrogen levels in the AKI mice were significantly reduced after administration of BAY, implicating a protective effect of BAY on kidneys against IRI. Further analyses from Western blot, immunofluorescence staining and flow cytometry revealed that BAY inhibited the Mincle/Syk/NF-κB signaling circuit and reduced the inflammatory response. BAY also inhibited the reactive oxygen species (ROS), which further decreased the formation of inflammasome and suppressed the mature of IL-1β and IL-18. Notably, these inhibitory effects of BAY on inflammation and inflammasome in BMDM were significantly reversed by Mincle ligand, trehalose-6,6-dibehenate. In summary, these findings provided compelling evidence that BAY may be an efficient inhibitor of the Mincle/Syk/NF-κB signaling circuit and ROS-induced inflammasome, which may help to develop Syk-inhibitors as novel therapeutic agents for AKI.