Prevention of Transition from Acute Kidney Injury to Chronic Kidney Disease Using Clinical-Grade Perinatal Stem Cells in Non-Clinical Study

Acute kidney injury (AKI) is widely recognized as a precursor to the onset or rapid progression of chronic kidney disease (CKD). However, there is currently no effective treatment available for AKI, underscoring the urgent need for the development of new strategies to improve kidney function. Human placental mesenchymal stromal cells (hpMSCs) were isolated from donor placentas, cultured, and characterized with regard to yield, viability, flow cytometry, and potency. To mimic AKI and its progression to CKD in a rat model, a dedicated sensitive non-clinical bilateral kidney ischemia-reperfusion injury (IRI) model was utilized. The experimental group received 3 × 105 hpMSCs into each kidney, while the control group received IRI and saline and the untreated group received IRI only. Urine, serum, and kidney tissue samples were collected over a period of 28 days. The hpMSCs exhibited consistent yields, viability, and expression of mesenchymal lineage markers, and were also shown to suppress T cell proliferation in a dose-dependent manner. To ensure optimal donor selection, manufacturing optimization, and rigorous quality control, the rigorous Good Manufacturing Practice (GMP) conditions were utilized. The results indicated that hpMSCs increased rat survival rates and improved kidney function by decreasing serum creatinine, urea, potassium, and fractionated potassium levels. Furthermore, the study demonstrated that hpMSCs can prevent the initial stages of kidney structural fibrosis and improve kidney function in the early stages by mitigating late interstitial fibrosis and tubular atrophy. Additionally, a robust manufacturing process with consistent technical parameters was established.

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.

Venetoclax efficacy on acute myeloid leukemia is enhanced by the combination with butyrate

Venetoclax has been approved recently for treatment of Acute myeloid leukemia (AML). Venetoclax is a BH3-mimetic and induces apoptosis via Bcl-2 inhibition. However, venetoclax's effect is still restrictive and a novel strategy is needed. In the present study, we demonstrate that sodium butyrate (NaB) facilitates the venetoclax's efficacy of cell death in AML cells. As a single agent, NaB or venetoclax exerted just a weak effect on cell death induction for AML cell line KG-1. The combination with NaB and venetoclax drastically induced cell death. NaB upregulated pro-apoptotic factors, Bax and Bak, indicating the synergistic effect by the collaboration with Bcl-2 inhibition by venetoclax. The combined treatment with NaB and venetoclax strongly cleaved a caspase substrate poly (ADP-ribose) polymerase (PARP) and a potent pan-caspase inhibitor Q-VD-OPh almost completely blocked the cell death induced by the combination, meaning that the combination mainly induced apoptosis. The combination with NaB and venetoclax also strongly induced cell death in another AML cell line SKNO-1 but did not affect chronic myeloid leukemia (CML) cell line K562, indicating that the effect was specific for AML cells. Our results provide a novel strategy to strengthen the effect of venetoclax for AML treatment.

Caspase inhibition improves viability and efficiency of liposomal transfection

High transfection efficiency is the most important point for experiments of DNA and RNA introduction into cells. Decrease of cell viability during the transfection procedure is a crucial issue, resulting in transfection failure. However, the mechanism underlying cell growth inhibition has not been fully elucidated. Lipofection is frequently used for transfection experiments, whereases, depending on cell type, it causes a decrease in cell viability. The present study demonstrates here that a potent pan-caspase inhibitor Q-VD-OPh blocked cell death during the lipofection, indicating apoptosis was induced in lipofection. Moreover, Q-VD-OPh drastically increased transfected cells. This method provides easier and more effective transfection system of lipofection and may be useful for transfection of not only cell lines but also clinical uses such as gene therapy and nucleic acids vaccine.

Formulation of lipid polymer hybrid nanoparticles of the phytochemical Fisetin and its in vivo assessment against severe acute pancreatitis

Fisetin (FST) is a naturally occurring flavonol that has recently emerged as a bioactive phytochemical with an impressive array of biological activities. To the author knowledge, boosting the activity of FST against severe acute pancreatitis (SAP) through a nanostructured delivery system (Nanophytomedicine) has not been achieved before. Thereupon, FST-loaded lipid polymer hybrid nanoparticles (FST-loaded LPHNPs) were prepared through conjoined ultrasonication and double emulsion (w/o/w) techniques. Comprehensive in vitro and in vivo evaluations were conducted. The optimized nanoparticle formula displayed a high entrapment efficiency % of 61.76 ± 1.254%, high loading capacity % of 32.18 ± 0.734, low particle size of 125.39 ± 0.924 nm, low particle size distribution of 0.357 ± 0.012, high zeta potential of + 30.16 ± 1.416 mV, and high mucoadhesive strength of 35.64 ± 0.548%. In addition, it exhibited a sustained in vitro release pattern of FST. In the in vivo study, oral pre-treatment of FST-loaded LPHNPs protected against L-arginine induced SAP and multiple organ injuries in rats compared to both FST alone and plain LPHNPs, as well as the untreated group, proven by both biochemical studies, that included both amylase and lipase activities, and histochemical studies of pancreas, liver, kidney and lungs. Therefore, the study could conclude the potential efficacy of the novel phytopharmaceutical delivery system of FST as a prophylactic regimen for SAP and consequently, associated multiple organ injuries.

Overview of Antibiotic-Induced Nephrotoxicity

Drug-induced nephrotoxicity accounts for up to 60% of cases of acute kidney injury (AKI) in hospitalized patients and is associated with increased morbidity and mortality in both adults and children. Antibiotics are one of the most common causes of drug-induced nephrotoxicity. Mechanisms of antibiotic-induced nephrotoxicity include glomerular injury, tubular injury or dysfunction, distal tubular obstruction from casts, and acute interstitial nephritis (AIN) mediated by a type IV (delayed-type) hypersensitivity response. Clinical manifestations of antibiotic-induced nephrotoxicity include acute tubular necrosis (ATN), AIN, and Fanconi syndrome. Given the potential nephrotoxic effects of antibiotics on critically ill patients, the use of novel biomarkers can provide information to optimize dosing and duration of treatment and can help prevent nephrotoxicity when traditional markers, such as creatinine, are unreliable. Use of novel kidney specific biomarkers, such as cystatin C and urinary kidney injury molecule-1 (KIM-1), may result in earlier detection of AKI, dose adjustment, or discontinuation of antibiotic and development of nonnephrotoxic antibiotics.

Sirtuin4 alleviates severe acute pancreatitis by regulating HIF-1α/HO-1 mediated ferroptosis

Acute pancreatitis (AP) is a common emergency of the digestive system and serious cases can develop into severe acute pancreatitis (SAP), which ortality rates up to 30%. Sirtuin4 (SIRT4) is a member of the sirtuin family, and plays a key role in inflammation and oxidative stress. However, the potential role of SIRT4 in SAP has yet to be elucidated. In the present study, we found that the expression level of SIRT4 in human AP was downregulated by screening a public database, suggesting that SIRT4 may play a role in AP. Subsequently, we used L-arginine (L-Arg) to induce SAP in SIRT4 knockout (SIRT4_KO) and SIRT4 overexpression (AAV_SIRT4) mice. The results showed that the pancreatic tissue injury and related lung and kidney injury were serious in SIRT4_KO mice after SAP induction, but were significantly reduced in AAV_SIRT4 mice. More importantly, we found that the levels of antioxidant factors GSH and SOD were decreased in SIRT4_KO mice, and the production of oxidative products and lipid peroxidation markers was increased, suggesting that SIRT4 was involved in inflammation and oxidative stress during SAP. Further studies showed that the absence or overexpression of SIRT4 affected the expression level of Hypoxia-inducible factor-1α (HIF-1α) after SAP induction, and regulated the expression of ferroptosis related proteins by mediating HIF-1α/HO-1 pathway. Collectively, our study revealed that SIRT4 plays a protective role in SAP by regulating the HIF-1α/HO-1 pathway to inhibit ferroptosis.

Therapeutic Effect of Three-Dimensional Cultured Adipose-Derived Stem Cell-Conditioned Medium in Renal Ischemia-Reperfusion Injury

BACKGROUND AND OBJECTIVES

We evaluated the effect of adipose-derived stem cell-derived conditioned medium (ADSC-CM) on the renal function of rats with renal ischemia-reperfusion injury (IRI)-induced acute kidney injury.

METHODS AND RESULTS

Forty male Sprague-Dawley rats were randomly divided into four groups: sham, nephrectomy control, IRI control, ADSC-CM. The ADSC-CM was prepared using the three-dimensional spheroid culture system and injected into renal parenchyme. The renal function of the rats was evaluated 28 days before and 1, 2, 3, 4, 7, and 14 days after surgical procedures. The rats were sacrificed 14 days after surgical procedures, and kidney tissues were collected for histological examination. The renal parenchymal injection of ADSC-CM significantly reduced the serum blood urea nitrogen and creatinine levels compared with the IRI control group on days 1, 2, 3, and 4 after IRI. The renal parenchymal injection of ADSC-CM significantly increased the level of creatinine clearance compared with the IRI control group 1 day after IRI. Collagen content was significantly lower in the ADSC-CM group than in the IRI control group in the cortex and medulla. Apoptosis was significantly decreased, and proliferation was significantly increased in the ADSC-CM group compared to the IRI control group in the cortex and medulla. The expressions of anti-oxidative makers were higher in the ADSC-CM group than in the IRI control group in the cortex and medulla.

CONCLUSIONS

The renal function was effectively rescued through the renal parenchymal injection of ADSC-CM prepared using a three-dimensional spheroid culture system.

Independent role of caspases and Bik in augmenting influenza A virus replication in airway epithelial cells and mice

Caspases and poly (ADP-ribose) polymerase 1 (PARP1) have been shown to promote influenza A virus (IAV) replication. However, the relative importance and molecular mechanisms of specific caspases and their downstream substrate PARP1 in regulating viral replication in airway epithelial cells (AECs) remains incompletely elucidated. Here, we targeted caspase 2, 3, 6, and PARP1 using specific inhibitors to compare their role in promoting IAV replication. Inhibition of each of these proteins caused significant decline in viral titer, although PARP1 inhibitor led to the most robust reduction of viral replication. We previously showed that the pro-apoptotic protein Bcl-2 interacting killer (Bik) promotes IAV replication in the AECs by activating caspase 3. In this study, we found that as compared with AECs from wild-type mice, bik-deficiency alone resulted in ~ 3 logs reduction in virus titer in the absence of treatment with the pan-caspase inhibitor (Q-VD-Oph). Inhibiting overall caspase activity using Q-VD-Oph caused additional decline in viral titer by ~ 1 log in bik-/- AECs. Similarly, mice treated with Q-VD-Oph were protected from IAV-induced lung inflammation and lethality. Inhibiting caspase activity diminished nucleo-cytoplasmic transport of viral nucleoprotein (NP) and cleavage of viral hemagglutinin and NP in human AECs. These findings suggest that caspases and PARP1 play major roles to independently promote IAV replication and that additional mechanism(s) independent of caspases and PARP1 may be involved in Bik-mediated IAV replication. Further, peptides or inhibitors that target and block multiple caspases or PARP1 may be effective treatment targets for influenza infection.

Gal-9/Tim-3 signaling pathway activation suppresses the generation of Th17 cells and promotes the induction of Foxp3+ regulatory T cells in renal ischemia-reperfusion injury

CD4⁺ T cells mediate the pathogenesis of renal ischemia-reperfusion injury (IRI). Emerging research suggests that a Th17/regulatory T cell (Treg) imbalance plays a pivotal role in the development of renal IRI. A recently identified negative checkpoint protein, T cell immunoglobulin domain and mucin domain family 3 (Tim-3), inhibits the immune response by binding to its ligand, galectin-9 (Gal-9). However, the role of the Gal-9/Tim-3 signaling pathway in the regulation of CD4⁺ T cell subsets in renal IRI remains unclear. In this study, we investigated the effect of the Gal-9/Tim-3 signaling pathway on Th17/Treg subsets in renal IRI using a mouse model. Renal IRI induced the expression of Gal-9 in renal tubular epithelial cells and increased the proportion of Tim-3⁺ Th17 cells and Tim-3⁺ forkhead box P3 (Foxp3)⁺ Treg cells in the ischemia-reperfusion (IR) kidneys. Administration of rAAV9-Gal-9 suppressed kidney inflammation, reduced the mortality of mice with renal IRI, increased Foxp3⁺ Treg cells, and reduced Th17 cells. In contrast, the blockade of Tim-3 in vivo using an anti-Tim-3 monoclonal antibody aggravated renal inflammation, decreased Foxp3⁺ Treg cells, and promoted Th17 cells. Thus, Gal-9/Tim-3 signaling pathway activation may protect against renal IRI by inhibiting Th17 cell production and inducing Foxp3⁺ Treg cell expansion. Our study suggests that the Gal-9/Tim-3 signaling pathway may be targeted by immunotherapy in renal IRI.

Early effects of bone marrow-derived mononuclear cells on lung and kidney in experimental sepsis

BACKGROUND

In experimental sepsis, functional and morphological effects of bone marrow-derived mononuclear cell (BMDMC) administration in lung tissue have been evaluated 1 and 7 days after therapy. However, to date no study has evaluated the early effects of BMDMCs in both lung and kidney in experimental polymicrobial sepsis.

MATERIAL AND METHODS

Twenty-five female C57BL/6 mice were randomly divided into the following groups: 1) cecal ligation and puncture (CLP)-induced sepsis; and 2) Sham (surgical procedure without CLP). After 1 h, CLP animals received saline (NaCl 0.9%) (CLP-Saline) or 10⁶ BMDMCs (CLP-Cell) via the jugular vein. At 6, 12, and 24 h after saline or BMDMC administration, lungs and kidneys were removed for histology and molecular biology analysis.

RESULTS

In lungs, CLP-Saline, compared to Sham, was associated with increased lung injury score (LIS) and keratinocyte chemoattractant (KC) mRNA expression at 6, 12, and 24 h. BMDMCs were associated with reduced LIS and KC mRNA expression regardless of the time point of analysis. Interleukin (IL)- 10 mRNA content was higher in CLP-Cell than CLP-Saline at 6 and 24 h. In kidney tissue, CLP-Saline, compared to Sham, was associated with tubular cell injury and increased neutrophil gelatinase-associated lipocalin (NGAL) levels, which were reduced after BMDMC therapy at all time points. Surface high-mobility-group-box (HMGB)- 1 levels were higher in CLP-Saline than Sham at 6, 12, and 24 h, whereas nuclear HMGB-1 levels were increased only at 24 h. BMDMCs were associated with decreased surface HMGB-1 and increased nuclear HMGB-1 levels. Kidney injury molecule (KIM)- 1 and IL-18 gene expressions were reduced in CLP-Cell compared to CLP-Saline at 12 and 24 h.

CONCLUSION

In the present experimental polymicrobial sepsis, early intravenous therapy with BMDMCs was able to reduce lung and kidney damage in a time-dependent manner. BMDMCs thus represent a potential therapy in well-known scenarios of sepsis induction.

PURPOSE

To evaluate early bone marrow-derived mononuclear cell (BMDMC) therapy on lung and kidney in experimental polymicrobial sepsis.

METHODS

Twenty-five female C57BL/6 mice were randomly divided into the following groups: cecal ligation and puncture (CLP)-induced sepsis; and sham (surgical procedure without CLP). After 1 h, CLP animals received saline (CLP-saline) or 10⁶ BMDMCs (CLP-cell) via the jugular vein. Lungs and kidneys were evaluated for histology and molecular biology after 6, 12, and 24 h.

RESULTS

In lungs, BMDMCs reduced the lung injury score and keratinocyte chemoattractant mRNA expression regardless of the time point of analysis; interleukin-10 mRNA content was higher in CLP-cell than CLP-saline at 6 and 24 h. In kidneys, BMDMCs reduced neutrophil gelatinase-associated lipocalin levels at all time points. BMDMCs decreased surface high mobility group box (HMGB)- 1 but increased nuclear HMGB-1 levels.

CONCLUSION

Early BMDMC therapy reduced lung and kidney damage in a time-dependent manner.

Clinical Characteristics of Acute Kidney Injury Associated with Tropical Acute Febrile Illness

Tropical acute febrile illness (TAFI) is one of the most frequent causes of acute kidney injury (AKI). The prevalence of AKI varies worldwide because there are limited reports available and different definitions are used. This retrospective study aimed to determine the prevalence, clinical characteristics, and outcomes of AKI associated with TAFI among patients. Patients with TAFI were classified into non-AKI and AKI cases based on the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Of 1019 patients with TAFI, 69 cases were classified as having AKI, a prevalence of 6.8%. Signs, symptoms, and laboratory results were significantly abnormal in the AKI group, including high-grade fever, dyspnea, leukocytosis, severe transaminitis, hypoalbuminemia, metabolic acidosis, and proteinuria. 20.3% of AKI cases required dialysis and 18.8% received inotropic drugs. Seven patients died, all of which were in the AKI group. Risk factors for TAFI-associated AKI were being male (adjusted odds ratio (AOR) 3.1; 95% CI 1.3–7.4), respiratory failure (AOR 4.6 95% CI 1.5–14.1), hyperbilirubinemia (AOR 2.4; 95% CI 1.1–4.9), and obesity (AOR 2.9; 95% CI 1.4–6). We recommend clinicians investigate kidney function in patients with TAFI who have these risk factors to detect AKI in its early stages and offer appropriate management.

Urinary levels of kidney injury molecule-1 (KIM-1) and interleukin-18 (IL-18) in children and adolescents with hyperuricemia

PURPOSE

Hyperuricemia may lead to silent tissue damage and increase the risk of some diseases, including kidney diseases. Increased serum uric acid concentration induces inflammatory pathways and promotes kidney damage. This study aimed to determine whether hyperuricemia influences the levels of urinary kidney injury markers in children and adolescents with hyperuricemia, assessed by the urinary concentrations of interleukin-18, a biomarker of inflammation, and kidney injury molecule-1 (KIM-1), a biomarker of kidney injury.

MATERIAL AND METHODS

The study included 73 children and adolescents (32 males and 41 females) aged 2-18 years. They were divided into two groups: hyperuricemia (HU) group (n ​= ​48) and normouricemia - reference group (R) (n ​= ​25). The concentrations of urinary interleukin-18 and KIM-1 were measured using an ELISA kit and were normalized for urinary creatinine (cr.) concentration.

RESULTS

The median interleukin-18/cr. Levels in the HU group were significantly higher than in the R group (median, Q1-Q3) 21.83 (11.32-35.96) and 12.68 (7.11-24.04), respectively, (p ​< ​0.05). The KIM-1/cr. in the HU group and the R group were (median, Q1-Q3) 0.79 (0.45-1.03) and 0.81 (0.59-1.01), respectively, and the difference was not significant. KIM-1/cr. did not differ between the groups. Interleukin-18/cr. ratio correlated positively with serum uric acid concentration (r ​= ​0.24, p ​< ​0.05).

CONCLUSIONS

Interleukin-18/cr., but not KIM-1/cr. was higher in children with hyperuricemia. Hyperuricemia results in increased IL-18 in urine, in absence of other markers of kidney injury, suggesting inflammation in the kidney. Additional studies on the adults should be done, to confirm this hypothesis.

Curcumin and Vitamin C Attenuate Gentamicin-Induced Nephrotoxicity by Modulating Distinctive Reactive Species

Gentamicin remains widely used in all age groups despite its well-documented nephrotoxicity; however, no adjuvant therapies have been established to counteract this side effect. Our study aimed to experimentally determine whether curcumin and vitamin C have nephroprotective effects and whether certain reactive species could be used as markers of early gentamicin nephrotoxicity. Wistar adult male rats were evenly distributed into four groups: control, gentamicin, curcumin and gentamicin, vitamin C and gentamicin (gentamicin: 60 mg/kg/day, intraperitoneally, 7 days). We determined renal function (urea, creatinine), oxidative stress (malondialdehyde, nitric oxide, 3-nitrotyrosine, total oxidative stress), and antioxidant and anti-inflammatory status (thiols, total antioxidant capacity, interleukin-10). Nephrotoxicity was successfully induced, as shown by the elevated creatinine levels in the gentamicin group. In contrast, supplementation with curcumin and vitamin C prevented an increase in urea levels while decreasing total oxidative stress levels compared to the gentamicin group. Moreover, vitamin C and curcumin distinctively modulate the levels of nitric oxide and malondialdehyde. Histological analysis showed more discrete lesions in rats that received vitamin C compared to the curcumin group.

Chronic Exposure to Vinclozolin Induced Fibrosis, Mitochondrial Dysfunction, Oxidative Stress, and Apoptosis in Mice Kidney

Vinclozolin is one of the most used fungicides in the control of fungi in fruits, vegetables, and ornamental plants. The effects of its exposure on different organs have been described, but information regarding its relevance to vinclozolin-induced nephrotoxicity is largely missing. This study focuses on the potential mechanism of vinclozolin-induced nephrotoxicity. CD1 male mice were administered vinclozolin (100 mg/kg) by oral gavage for 28 days. Vinclozolin administration decreased body weight over the treatment period and at the end of the experiment, increased the ratio of kidney weight to body weight and increased serum urea nitrogen and creatinine contents. Vinclozolin also induced histopathological alterations, including tubular dilatation and necrosis and impaired the integrity of the renal-tubular architecture and kidney fibrosis. The analyses conducted showed that vinclozolin administration altered the mRNA levels of mitochondrial function-related proteins (SIRT3, SIRT1, PGC-1α, TFAM, NRF1, VDAC-1, and Cyt c) and oxidative stress (increased lipid peroxidation and decreased total antioxidative capacity, catalase, and superoxide dismutase activities, glutathione levels, and glutathione peroxidase activity) in the kidneys. Furthermore, vinclozolin induced toxicity that altered Nrf2 signalling and the related proteins (HO-1 and NQO-1). Vinclozolin administration also affected both the extrinsic and intrinsic apoptotic pathways, upregulating the expression of proapoptotic factors (Bax, Caspase 3, and FasL) and downregulating antiapoptotic factor (Bcl-2) levels. This study suggests that vinclozolin induced nephrotoxicity by disrupting the transcription of mitochondrial function-related factors, the Nrf2 signalling pathway, and the extrinsic and intrinsic apoptotic pathways.

Pathophysiology of Acute Kidney Injury in Critical Illness: A Narrative Review

Acute kidney injury (AKI) is a syndrome that entails a rapid decline in kidney function with or without injury. The consequences of AKI among acutely ill patients are dire and lead to higher mortality, morbidity, and healthcare cost. To prevent AKI and its short and long-term repercussions, understanding its pathophysiology is essential. Depending on the baseline kidney histology and function reserves, the number of kidney insults, and the intensity of each insult, the clinical presentation of AKI may differ. While many factors are capable of inducing renal injury, they can be categorized into a few processes. The three primary processes reported in the literature are hemodynamic changes, inflammatory reactions, and nephrotoxicity. The majority of patients with AKI will suffer from more than one during their development and/or progression of AKI. Moreover, the development of one usually leads to the instigation of another. Thus, the interactions and progression between these mechanisms may determine the severity and duration of the AKI. Other factors such as organ crosstalk and how our concurrent therapies interact with these mechanisms complicate the pathophysiology of the progression of the AKI even further. In this narrative review article, we describe these three main pathophysiological processes that lead to the development and progression of AKI. © 2022 American Physiological Society. Compr Physiol 12: 1-14, 2022.

CCL-2 and CXCL-8: Potential Prognostic Biomarkers of Acute Kidney Injury after a Bothrops atrox Snakebite

In the Brazilian Amazon, the snake Bothrops atrox is the primary cause of snakebites. B. atrox (BaV) venom can cause systemic pathophysiological changes such as acute kidney injury (AKI), which leads to the production of chemokines and cytokines in response to the envenomation. These soluble immunological molecules act by modulating the inflammatory response; however, the mechanisms associated with the development of AKI are still poorly understood. Here, we characterize the profile of these soluble immunological molecules as possible predictive biomarkers of the development of AKI. The study involved 34 patients who had been victims of snakebites by Bothrops sp. These were categorized into two groups according to the development of AKI (AKI(-)/AKI(+)), using healthy donors as the control (HD). Peripheral blood samples were collected at three-time points: before antivenom administration (T0) and at 24 and 48 hours after antivenom (T1 and T2, respectively). The soluble immunological molecules (CXCL-8, CCL-5, CXCL-9, CCL-2, CXCL-10, IL-6, TNF, IL-2, IL-10, IFN-γ, IL-4, and IL-17A) were quantified using cytometric bead array. Our results demonstrated an increase in CXCL-9, CXCL-10, IL-6, IL-2, IL-10, and IL-17A molecules in the groups of patients who suffered Bothrops snakebites (AKI(-) and AKI(+)) before antivenom administration, when compared to HD. In the AKI(+) group, levels of CXCL-8 and CCL-2 molecules were elevated on admission and progressively decreased during the clinical evolution of patients after antivenom administration. In addition, in the signature analysis, these were produced exclusively by the group AKI(+) at T0. Thus, these chemokines may be related to the initiation and extension of AKI after envenomation by Bothrops and present themselves as two potential biomarkers of AKI at T0.

Eplerenone reduces renal ischaemia/reperfusion injury by modulating Klotho, NF-κB and SIRT1/SIRT3/PGC-1α signalling pathways

OBJECTIVES

Acute kidney injury (AKI) is a sudden impairment in kidney function that is associated with high morbidity and mortality. Inflammation, oxidative stress, mitochondrial impairment and energy depletion, along with organ dysfunction are hallmarks of AKI. This study aimed to evaluate the effects of Eplerenone, an aldosterone receptor antagonist, on the kidney injury caused by ischaemia/reperfusion (I/R).

METHODS

Male Wistar rats (n = 24) were randomly allocated into four groups: sham, IR, Eplerenone and Eplerenone+IR. Rats in the two last groups 1 h before I/R induction, were treated with Eplerenone (100 mg/kg) via intraperitoneal injection. Protein levels of Klotho, heat shock protein 70 (HSP70), sirtuin1 (SIRT1), SIRT3 and peroxisome proliferator-activated receptor-gamma coactivator 1-α (PGC-1α) along with antioxidant, apoptotic (caspase 3, Bax and Bcl2) and inflammatory [nuclear factor kappa-B (NF-κB) p65, Interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2)] factors were evaluated in the kidney tissues of the experimental groups.

KEY FINDINGS

Eplerenone pre-treatment significantly could improve IR-induced pathological changes and kidney function and increase the renal antioxidant factors compared to the IR group (P < 0.05). Furthermore, in the Eplerenone + IR group, significant elevation of the Klotho, SIRT1, SIRT3 and PGC-1α at the protein level was identified compared to the IR group. Eplerenone pretreatment could not only downregulate NF-κB signalling and its downstream inflammatory factors (IL-6, COX-2 and TNF-α) but also could decrease apoptotic factors (P ≤ 0.01).

CONCLUSIONS

The results recommended that Eplerenone exerts a protective effect against kidney IR injury by up-regulating Klotho, HSP70, sirtuins and PGC-1α to preserve mitochondrial function and cell survival. Moreover, it hinders renal inflammation by suppressing NF-κB signalling. These results offer insight into the prevention or treatment of AKI in the future.

HDAC6 inhibition attenuates renal injury by reducing IL-1β secretion and RIP kinase mediated necroptosis in acute oxalate nephropathy

BACKGROUND

Pathogenesis of acute kidney injury is driven by necro-inflammation, which is comprised of IL-1β mediated inflammation and RIP-1 mediated tubular necroptosis. HDAC6 is reported to regulate both inflammation and cell death. In the present study, we explored the role of HDAC6 in the lysosomal exocytosis of IL-1β and RIP-1 mediated necroptosis in the context of oxalate nephropathy.

METHODS

Raw 264.7 macrophages and NRK52E stimulated with oxalate crystals and LPS with or without HDAC6 inhibitor for in vitro experiments. Acute oxalate nephropathy was induced in C57BL/6 mice by injecting sodium oxalate (75 mg/kg). For the drug intervention study, Tubastain A (TSA) was given an hour before injection of sodium oxalate. Mice were sacrificed 24 hrs after the oxalate injection, blood and kidney were harvested. Blood samples were analyzed for BUN and IL-1β levels. Renal tissues were analyzed for histology, immunohistochemistry, RNA, and protein expression.

RESULTS

HDAC6 and IL-1β upregulated in crystal stimulated macrophages and acute oxalate nephropathy. Pre-treatment of macrophages with TSA reduced IL-1β in supernatant without affecting the expression of pro-IL-1β and mature IL-1β in cell lysate. The effect of TSA on IL-1β secretion was influenced by tubulin acetylation. Renal epithelial cell NRK52E stimulated with crystals showed upregulation of necroptosis pathway markers and concentration-dependent cell death. TSA inhibited RIP-1, RIP3, and MLKL expression along with p-MLKL in stimulated epithelial cells. TSA treatment of oxalate nephropathy mice showed decreased inflammation and tubular cell death by regulating IL-1β and necroptosis and reduced renal injury.

CONCLUSION

This study highlights the role of HDAC6 in regulating the tubulin-mediated secretion of IL-1β and RIP kinase mediated necroptosis in acute oxalate nephropathy.

Comparison of Stromal Vascular Fraction and Adipose-Derived Stem Cells for Protection of Renal Function in a Rodent Model of Ischemic Acute Kidney Injury

Aims

Few studies have compared the use of different cell types derived from adipose tissue or the optimal route for efficient and safe cell delivery in ischemic acute kidney injury (AKI). We compared the abilities of stromal vascular fraction (SVF) and adipose-derived stem cells (ADSC), injected via three different routes, to protect renal function in a rodent model of ischemic AKI.

Methods

Ninety male Sprague-Dawley rats were randomly divided into 9 groups: sham, nephrectomy control, AKI control, transaortic renal arterial SVF injection, renal parenchymal SVF injection, tail venous SVF injection, transaortic renal arterial ADSC injection, renal parenchymal ADSC injection, and tail venous ADSC injection groups. Their renal function was assessed 4 days before and 1, 2, 3, 4, 7, and 14 days after surgical procedures to induce ischemic AKI. The histomorphometric studies were performed 14 days after surgical procedures.

Results

Renal parenchymal injection of SVF notably reduced the level of serum blood urea nitrogen and creatinine elevation compared to the AKI control group. Renal parenchymal injection of SVF notably reduced the level of creatinine clearance decrease. In addition, collagen content was lower in the renal parenchymal SVF injection group, and fibrosis was reduced. Apoptosis was reduced in the renal parenchymal SVF injection group, and proliferation was increased. The expression levels of antioxidative markers such as glutathione reductase and peroxidase were higher in the renal parenchymal SVF injection group.

Conclusions

Our findings suggest that renal function is protected from ischemic AKI through renal parenchymal injection of SVF, which has enhanced antifibrotic, antiapoptotic, and antioxidative effects.

The IL-18/IL-18R1 signalling axis: Diagnostic and therapeutic potential in hypertension and chronic kidney disease

Chronic kidney disease (CKD) is inherently an inflammatory condition, which ultimately results in the development of end stage renal disease or cardiovascular events. Low-grade inflammatory diseases such as hypertension and diabetes are leading causes of CKD. Declines in renal function correlate with elevated circulating pro-inflammatory cytokines in patients with these conditions. The inflammasome is an important inflammatory signalling platform that has been associated with low-grade chronic inflammatory diseases. Notably, activation and assembly of the inflammasome causes the auto cleavage of pro-caspase-1 into its active form, which then processes the pro-inflammatory cytokines pro-interleukin (IL)-1β and pro-IL-18 into their active forms. Currently, the nod-like receptor protein 3 (NLRP3) inflammasome has been implicated in the development of CKD in pre-clinical and clinical settings, and the ablation or inhibition of inflammasome components have been shown to be reno-protective in models of CKD. While clinical trials have demonstrated that neutralisation of IL-1β signalling by the drug anakinra lowers inflammation markers in haemodialysis patients, ongoing preclinical studies are showing that this ability to attenuate disease is limited in progressive models of kidney disease. These results suggest a potential predominant role for IL-18 in the development of CKD. This review will discuss the role of the inflammasome and its pro-inflammatory product IL-18 in the development of renal fibrosis and inflammation that contribute to the pathophysiology of CKD. Furthermore, we will examine the potential of the IL-18 signalling axis as an anti-inflammatory target in CKD and its usefulness as diagnostic biomarker to predict acute kidney injury.

Circulating LIGHT (TNFSF14) and Interleukin-18 Levels in Sepsis-Induced Multi-Organ Injuries

The novel therapeutic target cytokine LIGHT (TNFSF14) was recently shown to play a major role in COVID-19-induced acute respiratory distress syndrome (ARDS). This study aims to investigate the associations of plasma LIGHT and another potentially targetable cytokine, interleukin-18 (IL-18), with ARDS, acute hypoxic respiratory failure (AHRF), or acute kidney injury (AKI), caused by non-COVID-19 viral or bacterial sepsis. A total of 280 subjects diagnosed with sepsis, including 91 cases with sepsis triggered by viral infections, were investigated in this cohort study. Day 0 plasma LIGHT and IL-18, as well as 59 other biomarkers (cytokines, chemokines, and acute-phase reactants) were measured by sensitive bead immunoassay and associated with symptom severity. We observed significantly increased LIGHT level in both bacterial sepsis patients (p = 1.80 × 10⁻⁵) and patients with sepsis from viral infections (p = 1.78 × 10⁻³). In bacterial sepsis, increased LIGHT level was associated with ARDS, AKI, and higher Apache III scores, findings also supported by correlations of LIGHT with other biomarkers of organ failure. IL-18 levels were highly variable across individuals and consistently correlated with Apache III scores, mortality, and AKI in both bacterial and viral sepsis. There was no correlation between LIGHT and IL-18. For the first time, we demonstrate independent effects of LIGHT and IL-18 in septic organ failure. The association of plasma LIGHT with AHRF suggests that targeting the pathway warrants exploration, and ongoing trials may soon elucidate whether this is beneficial. Given the large variance of plasma IL-18 among septic subjects, targeting this pathway requires precise application.

Effect of Fc-Elabela-21 on renal ischemia/reperfusion injury in mice: Mediation of anti-apoptotic effect via Akt phosphorylation

INTRODUCTION

Renal ischemia/reperfusion injury (IRI) is the most common cause of acute kidney injury (AKI), and patients with AKI have a high rate of mortality. Apelin is a therapeutic candidate for treatment of IRI and Elabela (ELA) is a recently discovered hormone that also activates the apelin receptor (APJ). We examined the use of ELA as a preventive treatment for IRI using in vitro and in vivo models.

METHODS

Male mice were subjected to renal IRI, with or without administration of a stabilized form of ELA (Fc-ELA-21) for 4 days. Renal tubular lesions were measured using H&E staining, reactive oxygen species (ROS) were measured using a dihydroethidium stain assay, and renal cell apoptosis was measured using the TUNEL assay and flow cytometry. Immortalized human proximal tubular epithelial (HK-2) cells were pretreated with or without LY294002 and/or ELA-32, maintained at normoxic or hypoxic conditions, and then returned to normal culture conditions to mimic IRI. Cell apoptosis was determined using the TUNEL assay and cell proliferation was determined using the MTT assay. The levels of Akt, p-Akt, ERK1/2, p- ERK1/2, Bcl-2, Bax, caspase-3 and cleaved caspase-3 were measured using western blotting.

RESULTS

Fc-ELA-21 administration reduced renal tissue damage, ROS production, and apoptosis in mice that had renal IRI. ELA-32 reduced HK-2 cell apoptosis and restored the proliferation of cells subjected to IRI. Akt phosphorylation had a role in the anti-apoptotic effect of ELA.

CONCLUSION

This study of in vitro and in vivo models of IRI indicated that the preventive and anti-apoptotic effects of ELA were mediated via the PI3K/Akt signaling pathway.

Calorie Restriction Protects against Contrast-Induced Nephropathy via SIRT1/GPX4 Activation

Calorie restriction (CR) extends lifespan and increases resistance to multiple forms of stress, including renal ischemia-reperfusion (I/R) injury. However, whether CR has protective effects on contrast-induced nephropathy (CIN) remains to be determined. In this study, we evaluated the therapeutic effects of CR on CIN and investigated the potential mechanisms. CIN was induced by the intravenous injection of iodinated contrast medium (CM) iopromide (1.8 g/kg) into Sprague Dawley rats with normal food intake or 40% reduced food intake, 4 weeks prior to iopromide administration. We found that CR was protective of CIN, assessed by renal structure and function. CM increased apoptosis, reactive oxygen species (ROS), and inflammation in the renal outer medulla, which were decreased by CR. The silent information regulator 1 (SIRT1) participated in the protective effect of CR on CIN, by upregulating glutathione peroxidase 4 (GPX4), a regulator of ferroptosis, because this protective effect was reversed by EX527, a specific SIRT1 antagonist. Our study showed that CR protected CIN via SIRT1/GPX4 activation. CR may be used to mitigate CIN.

Targeting HMGB1/TLR4/NF-κB signaling pathway by protocatechuic acid protects against l-arginine induced acute pancreatitis and multiple organs injury in rats

Acute pancreatitis (AP) is a common pancreatic inflammation associated with substantial morbidity and mortality. AP may be mild or severe which can spread systemically causing multiple organs failure (MOF) and even death. In the current study, protocatechuic acid (PCA), a natural phenolic acid, was investigated for its possible protective potential against L-arginine induced AP and multiple organs injury (MOI) in rats. AP was induced by L-arginine (500 mg/100 g, ip). Two dose levels of PCA were tested (50 and 100 mg/kg, oral, 10 days before L-arginine injection). PCA successfully protected against L-arginine induced AP and MOI that was manifested by normalizing pancreatic, hepatic, pulmonary, and renal tissue architecture and restoring the normal values of pancreatic enzymes (amylase and lipase), serum total protein, liver enzymes (alanine transaminase (ALT) and aspartate transaminase (AST)) and kidney function biomarkers (blood urea nitrogen (BUN) and serum creatinine (Cr)) that were significantly elevated upon L-arginine administration. Additionally, PCA restored balanced oxidant/antioxidants status that was disrupted by L-arginine and normalized pancreatic levels of inducible nitric oxide synthase (iNOS) and nitric oxide (NO) content. Moreover, PCA significantly decreased L-arginine induced elevation in pancreatic high motility group box protein 1 (HMGB1), toll like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), nuclear factor kappa B (NF-κB), tumor necrosis factor- α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) expression. PCA significantly ameliorated L-arginine-induced AP and MOI through its anti-inflammatory and antioxidant effects. HMGB1/TLR4/NF-κB was the major pathway involved in the observed protective potential.

Chess Not Checkers: Complexities Within the Myeloid Response to the Acute Kidney Injury Syndrome

Immune dysregulation in acute kidney injury (AKI) is an area of intense interest which promises to enhance our understanding of the disease and how to manage it. Macrophages are a heterogeneous and dynamic population of immune cells that carry out multiple functions in tissue, ranging from maintenance to inflammation. As key sentinels of their environment and the major immune population in the uninjured kidney, macrophages are poised to play an important role in the establishment and pathogenesis of AKI. These cells have a profound capacity to orchestrate downstream immune responses and likely participate in skewing the kidney environment toward either pathogenic inflammation or injury resolution. A clear understanding of macrophage and myeloid cell dynamics in the development of AKI will provide valuable insight into disease pathogenesis and options for intervention. This review considers evidence in the literature that speaks to the role and regulation of macrophages and myeloid cells in AKI. We also highlight barriers or knowledge gaps that need to be addressed as the field advances.

The impact of Caspase-1 deletion on apoptosis and acute kidney injury in a murine transplant model

BACKGROUND

Caspase-1 knockout mice (Casp1KO) are protected from Acute Kidney Injury (AKI) after warm ischemia/reperfusion injury in non-transplant models. Since Caspase-1 plays a central role as an inflammatory response initiator, we hypothesized that Casp1KO mice would be protected from AKI following transplant.

METHODS

Renal tubular cells (RTECs) were subjected to cold storage and rewarming (CS/REW). C57Bl/6 J wild type or Casp1KO kidneys were subjected to CI for 30 min and then transplanted into wild type recipients (CI + Txp). The recipients underwent bilateral native nephrectomy at the time of transplant. Serum creatinine (sCr) was measured 24 h after native nephrectomy to assess transplant function.

RESULTS

We found that RTECs subjected to CS/REW had significantly increased expression of the Caspase-1 and inflammasome protein NLRP1. Wild type kidneys subjected to CI + Txp into wild type recipients also demonstrated significantly increased Caspase-1 and NLRP1 protein expression compared to kidneys transplanted from Casp1KO donors into wild type recipients. Caspase-1 deletion results in significantly decreased RTEC apoptosis in transplanted Casp1KO vs WT kidneys. Surprisingly, however, renal function, ATN scores including brush border injury, cast formation and tubular simplification were similar in both groups and not significantly different.

CONCLUSIONS

Our data suggest that other triggers of inflammation and programmed necrosis may need to be inhibited in addition to attenuating Caspase-1 to fully prevent AKI after kidney transplant. Importantly, requirements may be distinct for AKI induced by transplantation as opposed to other transient models such as the clamp model of AKI.

Effect of taxifolin/dapagliflozin combination on colistin-induced nephrotoxicity in rats

Colistin is an antimicrobial agent that is used in resistant gram-negative infections. Its most common dose-limiting adverse effect is nephrotoxicity. The objective of our study was to explore the possible effects of each of taxifolin and dapagliflozin alone and in combination on colistin-induced nephrotoxicity in rats. Sixty male rats were randomized into six groups: Control; colistin; colistin + taxifolin; colistin + dapagliflozin; colistin + carboxymethyl cellulose (CMC) and colistin + taxifolin + dapagliflozin. Dapagliflozin, taxifolin, and CMC were given daily for 7 days, 4 hours before colistin injection. Kidney weight/body weight ratio and renal function tests were determined. Renal tissue nerve growth factor-β (NGF-β), transforming growth factor beta 1 (TGF-β1), proinflammatory cytokines, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), toll-like receptor 4 (TLR4), nuclear factor kappa B (NF-κB) p65, signal transducer and activator of transcription 3 (STAT3), oxidative stress parameters, beclin-1 and c-Jun NH2-terminal kinase (JNK) activities were measured. Kidneys were examined histopathologically and immunohistochemically. Taxifolin and/or dapagliflozin induced significant improvement in the renal functions and oxidative stress parameters with significant increase in tissue Nrf2, STAT3 and NGF-β accompanied with significant decrease in kidney weight/body weight ratio, tissue proinflammatory cytokines, TGF-β1, NF-κB (p65), TLR4, beclin-1 and JNK activities and improved the histopathological picture when compared to rats treated with colistin alone. This improvement was significant with taxifolin/dapagliflozin combination compared to rats treated with each of these agents alone. So, we concluded that the combined use of taxifolin and dapagliflozin may confer a therapeutic tool for attenuation of colistin-induced nephrotoxicity.

The Role of Endothelins, IL-18, and NGAL in Kidney Hypothermic Machine Perfusion

Ischemia-reperfusion injury (IRI) occurring after renal transplantation is a complex biochemical process that can be monitored by specific biomarkers. The roles of those are not yet fully elucidated. The aim of this study was to analyze the concentrations of endothelins (ET-1, ET-2, and ET-3), interleukin-18 (IL-18), and neutrophil gelatinase-associated lipocalin (NGAL) during the reperfusion of human kidneys grafted from brain dead donors and later transplanted. The study group (n = 44) was analyzed according to the method of kidney storage: Group 1 underwent hypothermic machine perfusion (HMP) in the LifePort perfusion pump (n = 22), and Group 2 underwent static cold storage (SCS) (n = 22). The analysis of kidney function was performed daily during the first seven days after transplantation. The kidneys in Group 1 were characterized by higher absolute concentrations of ET-1, IL-18, and NGAL, as well as a lower concentration of ET-2 (p = 0.017) and ET-3. The relative increase of ET-1 (p = 0.033), ET-2, and ET-3 during reperfusion was lower in this group, while the relative decrease of NGAL was higher. Group 1 was also characterized by significant decrease of IL-18 (p = 0.026) and a tendency for better kidney function based on the higher total diuresis, higher glomerular filtration rate (GFR), higher potassium level, lower serum creatinine, and lower urea concentration during the seven-day postoperative observation period. The long-term beneficial impact of hypothermic machine perfusion on the outcome of transplanted kidneys may rely on the early modified proceedings and intensity of ischemia-reperfusion injury reflected by the dynamics of the concentrations of examined biomarkers.

The combination of G-CSF and AMD3100 mobilizes bone marrow-derived stem cells to protect against cisplatin-induced acute kidney injury in mice

BACKGROUND

Several studies have confirmed that mobilizing bone marrow-derived stem cells (BMSCs) ameliorates renal function loss following cisplatin-induced acute kidney injury (AKI). The aim of this study was to explore whether the combination of granulocyte-colony stimulating factor (G-CSF) and plerixafor (AMD3100) exerts beneficial effects on renal function recovery in a model of cisplatin-induced nephrotoxicity.

METHODS

C57BL/6J mice received intraperitoneal injections of G-CSF (200 μg/kg/day) for 5 consecutive days. On the day of the last injection, the mice received a single subcutaneous dose of AMD3100 (5 mg/kg) 1 h before cisplatin 20 mg/kg injection. Ninety-six hours after cisplatin injection, the mice were euthanized, and blood and tissue samples were collected to assess renal function and tissue damage. Cell mobilization was assessed by flow cytometry (FCM).

RESULTS

Mice pretreated with G-CSF/AMD3100 exhibited longer survival and lower serum creatinine and blood urea nitrogen (BUN) levels than mice treated with only G-CSF or saline. Combinatorial G-CSF/AMD3100 treatment attenuated tissue injury and cell death, enhanced cell regeneration, and mobilized a higher number of stem cells in the peripheral blood than G-CSF or saline treatment. Furthermore, the mRNA expression of proinflammatory factors was lower, whereas that of anti-inflammatory factors was higher, in the G-CSF/AMD3100 group than in the G-CSF or saline group (all P < 0.05).

CONCLUSIONS

These results suggest that combinatorial G-CSF/AMD3100 therapy mobilizes BMSCs to accelerate improvements in renal functions and prevent cisplatin-induced renal tubular injury. This combinatorial therapy may represent a new therapeutic option for the treatment of AKI and should be further investigated in the future.

Differential role of nicotinamide adenine dinucleotide deficiency in acute and chronic kidney disease

BACKGROUND

Nicotinamide adenine dinucleotide (NAD+) is a ubiquitous coenzyme involved in electron transport and a co-substrate for sirtuin function. NAD+ deficiency has been demonstrated in the context of acute kidney injury (AKI).

METHODS

We studied the expression of key NAD+ biosynthesis enzymes in kidney biopsies from human allograft patients and patients with chronic kidney disease (CKD) at different stages. We used ischaemia-reperfusion injury (IRI) and cisplatin injection to model AKI, urinary tract obstruction [unilateral ureteral obstruction (UUO)] and tubulointerstitial fibrosis induced by proteinuria to investigate CKD in mice. We assessed the effect of nicotinamide riboside (NR) supplementation on AKI and CKD in animal models.

RESULTS

RNA sequencing analysis of human kidney allograft biopsies during the reperfusion phase showed that the NAD+de novo synthesis is impaired in the immediate post-transplantation period, whereas the salvage pathway is stimulated. This decrease in de novo NAD+ synthesis was confirmed in two mouse models of IRI where NR supplementation prevented plasma urea and creatinine elevation and tubular injury. In human biopsies from CKD patients, the NAD+de novo synthesis pathway was impaired according to CKD stage, with better preservation of the salvage pathway. Similar alterations in gene expression were observed in mice with UUO or chronic proteinuric glomerular disease. NR supplementation did not prevent CKD progression, in contrast to its efficacy in AKI.

CONCLUSION

Impairment of NAD+ synthesis is a hallmark of AKI and CKD. NR supplementation is beneficial in ischaemic AKI but not in CKD models.

A pilot study evaluating GSK1070806 inhibition of interleukin-18 in renal transplant delayed graft function

INTRODUCTION

Delayed graft function (DGF) following renal transplantation is a manifestation of acute kidney injury (AKI) leading to poor long-term outcome. Current treatments have limited effectiveness in preventing DGF. Interleukin-18 (IL18), a biomarker of AKI, induces interferon-γ expression and immune activation. GSK1070806, an anti-IL18 monoclonal antibody, neutralizes activated (mature) IL18 released from damaged cells following inflammasome activation. This phase IIa, single-arm trial assessed the effect of a single dose of GSK1070806 on DGF occurrence post donation after circulatory death (DCD) kidney transplantation.

METHODS

The 3 mg/kg intravenous dose was selected based on prior studies and physiologically based pharmacokinetic (PBPK) modeling, indicating the high likelihood of a rapid and high level of IL18 target engagement when administered prior to kidney allograft reperfusion. Utilization of a Bayesian sequential design with a background standard-of-care DGF rate of 50% based on literature, and confirmed via extensive registry data analyses, enabled a statistical efficacy assessment with a minimal sample size. The primary endpoint was DGF frequency, defined as dialysis requirement ≤7 days post transplantation (except for hyperkalemia). Secondary endpoints included safety, pharmacokinetics and pharmacodynamic biomarkers.

RESULTS

GSK1070806 administration was associated with IL18-GSK1070806 complex detection and increased total serum IL18 levels due to IL18 half-life prolongation induced by GSK1070806 binding. Interferon-γ-induced chemokine levels declined or remained unchanged in most patients. Although the study was concluded prior to the Bayesian-defined stopping point, 4/7 enrolled patients (57%) had DGF, exceeding the 50% standard-of-care rate, and an additional two patients, although not reaching the protocol-defined DGF definition, demonstrated poor graft function. Six of seven patients experienced serious adverse events (SAEs), including two treatment-related SAEs.

CONCLUSION

Overall, using a Bayesian design and extensive PBPK dose modeling with only a small sample size, it was deemed unlikely that GSK1070806 would be efficacious in preventing DGF in the enrolled DCD transplant population.

TRIAL REGISTRATION

NCT02723786.

Gm614 Protects Germinal Center B Cells From Death by Suppressing Caspase-1 Transcription in Lupus-Prone Mice

Only a few signaling pathways have been reported in germinal center (GC) B-cell proliferation and death. In this study, we showed that a novel uncharacterized Gm614 protein is highly expressed in GC B cells from lupus-prone mice. Critically, ablation of this GC B-cell-specific Gm614 promoted GC B-cell death and mitigation of autoimmune symptoms, whereas overexpression protected GC B cells from death and exacerbated autoimmune symptoms. We demonstrated that mechanistically, nuclear-localized Gm614 reduced caspase-1 expression in GC B cells by binding with caspase-1 promoter to suppress its activation. Our results suggest that Gm614 protects GC B cells from death by suppressing caspase-1 transcription in autoimmune diseases. This may provide some hints for targeting the cell proliferation involved in autoimmune diseases.

Investigation of the Effects and Mechanisms of Dendrobium loddigesii Rolfe Extract on the Treatment of Gout

Objective

Gout is a chronic disease that causes inflammatory arthritis, which is closely related to urate accumulation induced by a disorder of uric acid metabolism and the consequent deposition of monosodium urate crystals. Dendrobium loddigesii Rolfe is an herbal medicine that has been used in some traditional Chinese medicine formulae in the treatment of gout. This study aimed to explore and verify the antigout activity of Dendrobium loddigesii extract (DLE) on alleviating the hyperuricaemia of mice and the acute gouty arthritis of rats.

Methods

An animal model of hyperuricaemia was established using potassium oxonate (PO). We analysed the expression of uric acid transporter mRNA in the kidney in the hyperuricaemic mice after treatment with DLE. Simultaneously, a monosodium urate crystal-induced acute gouty arthritis rat model was used to evaluate the effects of DLE, according to the level of ankle swelling, as well as the protein levels of inflammatory receptors and cytokines, as assayed by WB and ELISA.

Results

DLE alleviated hyperuricaemia in mice and inhibited acute gouty arthritis in rats (P < 0.05). Meanwhile, DLE regulated the levels of uric acid transporters mRNA transcripts, including mouse organic anion transporter 1 (mOAT1), organic anion transporter 3 (mOAT3), urate transporter 1 (mURAT1), and glucose transporter 9 (mGLUT9) in the kidney (P < 0.05), suggesting that DLE promoted uric acid metabolism. Furthermore, DLE significantly suppressed the protein levels of TLRs, MyD88, and NF-κB in the ankle joint's synovium (P < 0.05), and the serum levels of IL-1β, IL-6, and TNF-α were also reduced, which demonstrated the anti-inflammatory effects of DLE.

Conclusion

DLE alleviates hyperuricaemia by regulating the transcription level of uric acid transporters in the kidney. It also inhibits acute gouty arthritis by inhibiting the pathway of TLRs/MyD88/NF-κB in the ankle joint's synovium. The findings of the present study imply that DLE alleviates gout by promoting uric acid metabolism and inhibiting inflammation related to the TLRs/MyD88/NF-κB pathway.

Assessing the health of the nephron in acute kidney injury: biomarkers of kidney function and injury

PURPOSE OF REVIEW

Serum creatinine and urine output continue to be the mainstays of diagnosis of acute kidney injury, though both of these measures have significant limitations, especially in acutely hospitalized patients. Biomarkers in both blood and urine have been studied extensively in the research setting and are on the verge of clinical practice to improve diagnosis of AKI.

RECENT FINDINGS

Blood and urine biomarkers can be localized to specific areas or functions within the nephron. Biomarkers can help to characterize glomerular or tubular function; glomerular, tubular, or interstitial injury; inflammation; or repair. Further, biomarkers can improve diagnosis of AKI in various clinical settings including acute interstitial nephritis, acute tubular injury, and hepatorenal syndrome, and cardiorenal syndrome.

SUMMARY

Biomarkers are becoming more prevalent in both research and getting close to clinical use. Both blood and urine biomarkers can help to localize impairment in nephron health by either location or function within the nephron and among various causes of AKI.

Aldehyde dehydrogenase 2 regulates autophagy via the Akt-mTOR pathway to mitigate renal ischemia-reperfusion injury in hypothermic machine perfusion

AIMS

Ischemia-reperfusion injury (IRI) is harmful to patients following kidney transplantation. Hypothermic machine perfusion (HMP) can be adopted to preserve grafts and reduce consequential injury. We hypothesized that aldehyde dehydrogenase 2 (ALDH2) partly mitigates kidney IRI via regulating excessive autophagy in HMP.

MATERIALS AND METHODS

The rabbits were assigned to 5 groups: Normal, HMP, HMP + Alda-1, HMP + CYA and cold storage (CS). After the rabbit autologous kidney transplantation, renal pathology and function were evaluated by histological analysis, glomerular related proteins (desmin, nephrin), tubular injury factors (NGAL, Ki67), serum creatinine (Cr) and blood urea nitrogen (BUN). Oxidative stress molecular Malondialdehyde (MDA) and superoxide dismutase (SOD2) expression, as well as inflammatory cytokines (TNF-α, IL-6, IL-10) were assessed by immunohistochemistry. The expression of LC3, p62, ALDH2, p-Akt, mTOR, PTEN, p-PTEN, and 4-HNE were measured by immunohistochemistry, RT-PCR, Western blot analysis or ELISA.

KEY FINDINGS

HMP was more effective than CS for kidney preservation, with p- ALDH2 expressed in greater quantities in HMP. The results of kidney pathology and function in HMP + Alda-1 were the best. The MDA & SOD2 and the Vyacheslav score were improved in HMP + CYA. ALDH2 reduced 4-HNE-induced oxidative stress, inflammatory infiltration, the expression of LC3, p62 and inhibited autophagy accompanied by activation of p-Akt and mTOR via p-PTEN/PTEN.

SIGNIFICANCE

Akt-mTOR autophagy pathway is a novel target for ALDH2 to reduce renal IRI partly by inhibition of 4-HNE in HMP, then protecting the donated kidney received after cardiac death (DCD).

Kinin B1 receptor: a potential therapeutic target in sepsis-induced vascular hyperpermeability

Background

In sepsis, the endothelial barrier becomes incompetent, with the leaking of plasma into interstitial tissues. VE-cadherin, an adherens junction protein, is the gatekeeper of endothelial cohesion. Kinins, released during sepsis, induce vascular leakage and vasodilation. They act via two G-protein coupled receptors: B1 (B1R) and B2 (B2R). B1R is inducible in the presence of pro-inflammatory cytokines, endotoxins or after tissue injury. It acts at a later stage of sepsis and elicits a sustained inflammatory response. The aim of our study was to investigate the relationships between B1R and VE-cadherin destabilization in vivo in a later phase of sepsis.

Methods

Experimental, prospective study in a university research laboratory. We used a polymicrobial model of septic shock by cecal ligation and puncture in C57BL6 male mice or C57BL6 male mice that received a specific B1R antagonist (R-954). We studied the influence of B1R on sepsis-induced vascular permeability 30 h after surgery for several organs, and VE-cadherin expression in the lung and kidneys by injecting R-954 just before surgery. The 96-h survival was determined in mice without treatment or in animals receiving R-954 as a “prophylactic” regimen (a subcutaneous injection of 200 µg/kg, prior to CLP and 24 h after CLP), or as a “curative” regimen (injection of 100 µg/kg at H6, H24 and H48 post-surgery).

Results

B1R inactivation helps to maintain MAP above 65 mmHg but induces different permeability profiles depending on whether or not organ perfusion is autoregulated. In our model, VE-cadherin was destabilized in vivo during septic shock. At a late stage of sepsis, the B1R blockade reduced the VE-cadherin disruption by limiting eNOS activation. The survival rate for mice that received R-954 after sepsis induction was higher than in animals that received an antagonist as a prophylactic treatment.

Conclusions

B1R antagonizing reduced mortality in our model of murine septic shock by limiting the vascular permeability induced by VE-cadherin destabilization through maintenance of the macrohemodynamics, consequently limiting organ dysfunctions.

Hypoxia-induced apoptosis of astrocytes is mediated by reduction of Dicer and activation of caspase-1

Hypoxia is a condition in which the whole body or a region of the body is deprived of oxygen supply. The brain is very sensitive to the lack of oxygen and cerebral hypoxia can rapidly cause severe brain damage. Astrocytes are essential for the survival and function of neurons. Therefore, protecting astrocytes against cell death is one of the main therapeutic strategies for treating hypoxia. Hence, the mechanism of hypoxia-induced astrocytic cell death should be fully elucidated. In this study, astrocytes were exposed to hypoxic conditions using a hypoxia work station or the hypoxia mimetic agent cobalt chloride (CoCl₂ ). Both the hypoxic gas mixture (1% O₂ ) and chemical hypoxia-induced apoptotic cell death in T98G glioblastoma cells and mouse primary astrocytes. Reactive oxygen species were generated in response to the hypoxia-mediated activation of caspase-1. Active caspase-1 induced the classical caspase-dependent apoptosis of astrocytes. In addition, the microRNA processing enzyme Dicer was cleaved by caspase-3 during hypoxia. Knockdown of Dicer using antisense oligonucleotides induced apoptosis of T98G cells. Taken together, these results suggest that astrocytic cell death during hypoxia is mediated by the reactive oxygen species/caspase-1/classical caspase-dependent apoptotic pathway. In addition, the decrease in Dicer levels by active caspase-3 amplifies this apoptotic pathway via a positive feedback loop. These findings may provide a new target for therapeutic interventions in cerebral hypoxia.

The role of inflammasomes in kidney disease

Inflammasomes are multiprotein innate immune complexes that regulate caspase-dependent inflammation and cell death. Pattern recognition receptors, such as nucleotide-binding oligomerization domain (NOD)-like receptors and absent in melanoma 2 (AIM2)-like receptors, sense danger signals or cellular events to activate canonical inflammasomes, resulting in caspase 1 activation, pyroptosis and the secretion of IL-1β and IL-18. Non-canonical inflammasomes can be activated by intracellular lipopolysaccharides, toxins and some cell signalling pathways. These inflammasomes regulate the activation of alternative caspases (caspase 4, caspase 5, caspase 11 and caspase 8) that lead to pyroptosis, apoptosis and the regulation of other cellular pathways. Many inflammasome-related genes and proteins have been implicated in animal models of kidney disease. In particular, the NLRP3 (NOD-, LRR- and pyrin domain-containing 3) inflammasome has been shown to contribute to a wide range of acute and chronic microbial and non-microbial kidney diseases via canonical and non-canonical mechanisms that regulate inflammation, pyroptosis, apoptosis and fibrosis. In patients with chronic kidney disease, immunomodulation therapies targeting IL-1β such as canakinumab have been shown to prevent cardiovascular events. Moreover, findings in experimental models of kidney disease suggest that small-molecule inhibitors targeting NLRP3 and other inflammasome components are promising therapeutic agents.

"Point of no return" in unilateral renal ischemia reperfusion injury in mice

Background

In the past years evidence has been growing about the interconnection of chronic kidney disease and acute kidney injury. The underlying pathophysiological mechanisms remain unclear. We hypothesized, that a threshold ischemia time in unilateral ischemia/reperfusion injury sets an extent of ischemic tubule necrosis, which as “point of no return” leads to progressive injury. This progress is temporarily associated by increased markers of inflammation and results in fibrosis and atrophy of the ischemic kidney.

Methods

Acute tubule necrosis was induced by unilateral ischemia/reperfusion injury in male C57BL/6 N mice with different ischemia times (15, 25, 35, and 45 min). At multiple time points between 15 min and 5 weeks we assessed gene expression of markers for injury, inflammation, and fibrosis, histologically the injury of tubules, cell death (TUNEL), macrophages, neutrophil influx and kidney atrophy.

Results

Unilateral ischemia for 15 and 25 min induced upregulation of markers for injury after reperfusion for 24 h but no upregulation after 5 weeks. None of the markers for inflammation or fibrosis were upregulated after ischemia for 15 and 25 min at 24 h or 5 weeks on a gene expression level, except for Il-6. Ischemia for 35 and 45 min consistently induced upregulation of markers for inflammation, injury, and partially of fibrosis (Tgf-β1 and Col1a1) at 24 h and 5 weeks. The threshold ischemia time for persistent injury of 35 min induced a temporal association of markers for inflammation and injury with peaks between 6 h and 7 d along the course of 10 d. This ischemia time also induced persistent cell death (TUNEL) throughout observation for 5 weeks with a peak at 6 h and progressing kidney atrophy beginning 7 d after ischemia.

Conclusions

This study confirms the evidence of a threshold extent of ischemic injury in which markers of injury, inflammation and fibrosis do not decline to baseline but remain upregulated assessed in long term outcome (5 weeks). Excess of this threshold as “point of no return” leads to persistent cell death and progressing atrophy and is characterized by a temporal association of markers for inflammation and injury.

Time-dependent effects of histone deacetylase inhibition in sepsis-associated acute kidney injury

BACKGROUND

Sepsis, a dysregulated host response to infection with results in organ dysfunction, has been a major challenge to the development of effective therapeutics. Sepsis-associated acute kidney injury (S-AKI) results in a 3-5-fold increase in the risk of hospital mortality compared to sepsis alone. The development of therapies to reverse S-AKI could therefore significantly affect sepsis outcomes. However, the translation of therapies from preclinical studies into humans requires model systems that recapitulate clinical scenarios and the development of renal fibrosis indicative of the transition from acute to chronic kidney disease.

RESULTS

Here we characterized a murine model of S-AKI induced by abdominal sepsis developing into a chronic phenotype. We applied a small molecule histone deacetylase-8 inhibitor, UPHD186, and found that early treatment, beginning at 48 h post-sepsis, worsened renal outcome accompanied by decreasing mononuclear cell infiltration in the kidney, skewing cells into a pro-inflammatory phenotype, and increased pro-fibrotic gene expression, while delayed treatment, beginning at 96 h post-sepsis, after the acute inflammation in the kidney had subsided, resulted in improved survival and kidney histology presumably through promoting proliferation and inhibiting fibrosis.

CONCLUSIONS

These findings not only present a clinically relevant S-AKI model, but also introduce a timing dimension into S-AKI therapeutic interventions that delayed treatment with UPHD186 may enhance renal histologic repair. Our results provide novel insights into successful repair of kidney injury and sepsis therapy.

Inflammatory Targets in Diabetic Nephropathy

One of the most frequent complications in patients with diabetes mellitus is diabetic nephropathy (DN). At present, it constitutes the first cause of end stage renal disease, and the main cause of cardiovascular morbidity and mortality in these patients. Therefore, it is clear that new strategies are required to delay the development and the progression of this pathology. This new approach should look beyond the control of traditional risk factors such as hyperglycemia and hypertension. Currently, inflammation has been recognized as one of the underlying processes involved in the development and progression of kidney disease in the diabetic population. Understanding the cascade of signals and mechanisms that trigger this maladaptive immune response, which eventually leads to the development of DN, is crucial. This knowledge will allow the identification of new targets and facilitate the design of innovative therapeutic strategies. In this review, we focus on the pathogenesis of proinflammatory molecules and mechanisms related to the development and progression of DN, and discuss the potential utility of new strategies based on agents that target inflammation.

Apoptosis and autophagy in polycystic kidney disease (PKD)

Apoptosis in the cystic epithelium is observed in most rodent models of polycystic kidney disease (PKD) and in human autosomal dominant PKD (ADPKD). Apoptosis inhibition decreases cyst growth, whereas induction of apoptosis in the kidney of Bcl-2 deficient mice increases proliferation of the tubular epithelium and subsequent cyst formation. However, alternative evidence indicates that both induction of apoptosis as well as increased overall rates of apoptosis are associated with decreased cyst growth. Autophagic flux is suppressed in cell, zebra fish and mouse models of PKD and suppressed autophagy is known to be associated with increased apoptosis. There may be a link between apoptosis and autophagy in PKD. The mammalian target of rapamycin (mTOR), B-cell lymphoma 2 (Bcl-2) and caspase pathways that are known to be dysregulated in PKD, are also known to regulate both autophagy and apoptosis. Induction of autophagy in cell and zebrafish models of PKD results in suppression of apoptosis and reduced cyst growth supporting the hypothesis autophagy induction may have a therapeutic role in decreasing cyst growth, perhaps by decreasing apoptosis and proliferation in PKD. Future research is needed to evaluate the effects of direct autophagy inducers on apoptosis in rodent PKD models, as well as the cause and effect relationship between autophagy, apoptosis and cyst growth in PKD.

Mechanisms of haemolysis-induced kidney injury

Intravascular haemolysis is a fundamental feature of chronic hereditary and acquired haemolytic anaemias, including those associated with haemoglobinopathies, complement disorders and infectious diseases such as malaria. Destabilization of red blood cells (RBCs) within the vasculature results in systemic inflammation, vasomotor dysfunction, thrombophilia and proliferative vasculopathy. The haemoprotein scavengers haptoglobin and haemopexin act to limit circulating levels of free haemoglobin, haem and iron - potentially toxic species that are released from injured RBCs. However, these adaptive defence systems can fail owing to ongoing intravascular disintegration of RBCs. Induction of the haem-degrading enzyme haem oxygenase 1 (HO1) - and potentially HO2 - represents a response to, and endogenous defence against, large amounts of cellular haem; however, this system can also become saturated. A frequent adverse consequence of massive and/or chronic haemolysis is kidney injury, which contributes to the morbidity and mortality of chronic haemolytic diseases. Intravascular destruction of RBCs and the resulting accumulation of haemoproteins can induce kidney injury via a number of mechanisms, including oxidative stress and cytotoxicity pathways, through the formation of intratubular casts and through direct as well as indirect proinflammatory effects, the latter via the activation of neutrophils and monocytes. Understanding of the detailed pathophysiology of haemolysis-induced kidney injury offers opportunities for the design and implementation of new therapeutic strategies to counteract the unfavourable and potentially fatal effects of haemolysis on the kidney.

CPUY192018, a potent inhibitor of the Keap1-Nrf2 protein-protein interaction, alleviates renal inflammation in mice by restricting oxidative stress and NF-κB activation

The Keap1-Nrf2-ARE pathway regulates the constitutive and inducible transcription of various genes that encode detoxification enzymes, antioxidant proteins and anti-inflammatory proteins and has pivotal roles in the defence against cellular oxidative stress. In this study, we investigated the therapeutic potential of CPUY192018, a potent small-molecule inhibitor of the Keap1-Nrf2 protein-protein interaction (PPI), in renal inflammation. In human proximal tubular epithelial HK-2 cells, CPUY192018 treatment significantly increased Nrf2 protein level and Nrf2 nuclear translocation, which enhanced Nrf2-ARE transcription capacity and the downstream protein content in a Nrf2 dependent manner. In lipopolysaccharide (LPS)-challenged human HK-2 cells, CPUY192018 exhibited cytoprotective effects by enhancing the Nrf2-ARE regulated antioxidant system and diminished the LPS-induced inflammatory response by hindering the ROS-mediated activation of the NF-κB pathway. In the LPS-induced mouse model of chronic renal inflammation, by activating Nrf2, CPUY192018 treatment balanced renal oxidative stress and suppressed inflammatory responses. Hence, administration of CPUY192018 reduced kidney damage and ameliorated pathological alterations of the glomerulus. Taken together, our study suggested that small-molecule Keap1-Nrf2 PPI inhibitors can activate the Nrf2-based cytoprotective system and protect the kidney from inflammatory injury, raising a potential application of Keap1-Nrf2 PPI inhibitors in the treatment of inflammatory kidney disorders.

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CPUY192018 activated Nrf2-ARE pathway to protect against LPS-induced renal inflammation both in cells and in vivo.

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CPUY192018 also inhibited NF-κB involved inflammatory response both in cells and kidney.

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The development of Keap1-Nrf2 PPI inhibitors may create treatment options for kidney diseases with reduced off-target effects.

Dexmedetomidine alleviates lipopolysaccharide-induced acute kidney injury by inhibiting the NLRP3 inflammasome activation via regulating the TLR4/NOX4/NF-κB pathway

Dexmedetomidine (DEX) prevents kidney damage caused by sepsis, but the mechanism of this effect remains unclear. In this study, the protective molecular mechanism of DEX in lipopolysaccharide (LPS)-induced acute kidney injury was investigated and its potential pharmacological targets from the perspective of inhibiting oxidative stress damage and the nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome activation. Intraperitoneal injection of DEX (30 μg/kg) significantly improved LPS (10 mg/kg) induced renal pathological damage and renal dysfunction. DEX also ameliorated oxidative stress damage by reducing the contents of reactive oxygen species, malondialdehyde and hydrogen peroxide, and increasing the level of glutathione, as well as the activity of superoxide dismutase and catalase. In addition, DEX prevented nuclear factor-kappa B (NF-κB) activation and I-kappa B (IκB) phosphorylation, as well as the expressions of NLRP3 inflammasome-associated protein and downstream IL-18 and IL-1β. The messengerRNA (mRNA) and protein expressions of toll-like receptor 4 (TLR4), NADPH oxidase-4 (NOX4), NF-κB, and NLRP3 were also significantly reduced by DEX. Their expressions were further evaluated by immunohistochemistry, yielding results were consistent with the results of mRNA and protein detection. Interestingly, the protective effects of DEX were reversed by atipamezole-an alpha 2 adrenal receptor (α₂ AR) inhibitor, whereas idazoxan-an imidazoline receptor (IR) inhibitor failed to reverse this change. In conclusion, DEX attenuated LPS-induced AKI by inhibiting oxidative stress damage and NLRP3 inflammasome activation via regulating the TLR4/NOX4/NF-κB pathway, mainly acting on the α₂ AR rather than IR.

Antithrombin III Attenuates AKI Following Acute Severe Pancreatitis

BACKGROUND

Antithrombin III (ATIII), the predominant coagulation factor inhibitor, possesses anti-inflammatory properties and exerts renoprotective effects on renal ischemia-reperfusion injury in animal models. However, the ATIII's protective effects of ATIII on acute kidney injury (AKI) following severe acute pancreatitis (SAP) need to be confirmed.

METHODS

We assessed the association between ATIII activities and the incidence of AKI in patients with SAP, and explored therapeutic effects and potential mechanisms of ATIII on kidney injury in sodium taurocholate induced SAP rat model. Rats were intravenously injected with ATIII (500 μg/kg) before or after the induction of SAP.

RESULTS

The results demonstrated ATIII did not attenuate pancreatic injury, but significantly ameliorate renal dysfunction and renal histological injury. ATIII administration alleviated renal inflammation response, oxidative stress, and cell apoptosis. Moreover, ATIII attenuated tumor necrosis factor α (TNFα)-stimulated intercellular cell adhesion molecule 1(ICAM-1) and monocyte chemotactic protein 1 (MCP-1) upregulation in cultured renal tubular epithelial cells.

CONCLUSION

ATIII appears to ameliorate SAP-induced kidney injury by inhibiting inflammation, oxidative stress, and apoptosis. ATIII supplementation may have a potential prophylactic and therapeutic effect on SAP induced AKI.

Ischaemia reperfusion injury: mechanisms of progression to chronic graft dysfunction

The increasing use of extended criteria organs to meet the demand for kidney transplantation raises an important question of how the severity of early ischaemic injury influences long-term outcomes. Significant acute ischaemic kidney injury is associated with delayed graft function, increased immune-associated events and, ultimately, earlier deterioration of graft function. A comprehensive understanding of immediate molecular events that ensue post-ischaemia and their potential long-term consequences are key to the discovery of novel therapeutic targets. Acute ischaemic injury primarily affects tubular structure and function. Depending on the severity and persistence of the insult, this may resolve completely, leading to restoration of normal function, or be sustained, resulting in persistent renal impairment and progressive functional loss. Long-term effects of acute renal ischaemia are mediated by several mechanisms including hypoxia, HIF-1 activation, endothelial dysfunction leading to vascular rarefaction, sustained pro-inflammatory stimuli involving innate and adaptive immune responses, failure of tubular cells to recover and epigenetic changes. This review describes the biological relevance and interaction of these mechanisms based on currently available evidence.

Gcm1 is involved in cell proliferation and fibrosis during kidney regeneration after ischemia-reperfusion injury

In acute kidney injury (AKI), the S3 segment of the proximal tubule is particularly damaged, as it is most vulnerable to ischemia. However, this region is also involved in renal tubular regeneration. To deeply understand the mechanism of the repair process after ischemic injury in AKI, we focused on glial cells missing 1 (Gcm1), which is one of the genes expressed in the S3 segment. Gcm1 is essential for the development of the placenta, and Gcm1 knockout (KO) is embryonically lethal. Thus, the function of Gcm1 in the kidney has not been analyzed yet. We analyzed the function of Gcm1 in the kidney by specifically knocking out Gcm1 in the kidney. We created an ischemia-reperfusion injury (IRI) model to observe the repair process after AKI. We found that Gcm1 expression was transiently increased during the recovery phase of IRI. In Gcm1 conditional KO mice, during the recovery phase of IRI, tubular cell proliferation reduced and transforming growth factor-β1 expression was downregulated resulting in a reduction in fibrosis. In vitro, Gcm1 overexpression promoted cell proliferation and upregulated TGF-β1 expression. These findings indicate that Gcm1 is involved in the mechanisms of fibrosis and cell proliferation after ischemic injury of the kidney.