Acute hepatic ischemic-reperfusion injury induces a renal cortical "stress response," renal "cytoresistance," and an endotoxin hyperresponsive state

NGAL in the Development of Acute Kidney Injury in a Murine Model of Remote Ischaemic Preconditioning and Liver Ischaemia Reperfusion

Acute kidney injury (AKI) is common following liver transplantation and is associated with liver ischeamia reperfusion (IR) injury. The purpose of this study was to use a mouse model of liver IR injury and AKI to study the role of Neutrophil Gelatinase Associated Lipocalin (NGAL), a biomarker of AKI, in liver IR injury and AKI. We demonstrate an adapted, reproducible model of liver IR injury and AKI in which remote ischemic preconditioning (RIPC) by repeated episodes of hindleg ischemia prior to liver IR reduced the severity of the IR injury. In this model, serum NGAL at 2 h post reperfusion correlated with AKI development early following IR injury. This early rise in serum NGAL was associated with hepatic but not renal upregulation of NGAL mRNA, suggesting NGAL production in the liver but not the kidney in the early phase post liver IR injury.

Vagus nerve stimulation attenuates acute kidney injury induced by hepatic ischemia/reperfusion injury in rats

Hepatic ischemia/reperfusion (I/R) injury, caused by limited blood supply and subsequent blood supply, is a causative factor resulting in morbidity and mortality during liver transplantation and liver resection. Hepatic I/R injury frequently contributes to remote organ injury, such as kidney, lung, and heart. It has been demonstrated that vagus nerve stimulation (VNS) is effective in remote organ injury after I/R injury. Here, our aim is to investigate the potential action of VNS on hepatic I/R injury-induced acute kidney injury (AKI) and explore its underlying mechanisms. To test this hypothesis, male Sprague-Dawley rats were randomly assigned into three experimental groups: Sham group (sham operation, n = 6); I/R group (hepatic I/R with sham VNS, n = 6); and VNS group (hepatic I/R with VNS, n = 6). VNS was performed during the entire hepatic I/R process. Our results showed that throughout the hepatic I/R process, VNS significantly regulated the expression levels of various iconic factors and greatly enhanced the protein expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) in the kidneys. These findings suggested that VNS may ameliorate hepatic I/R injury-induced AKI by suppressing inflammation, oxidative stress, and apoptosis probably through activating the Nrf2/HO-1 signaling pathway.

Oxidant- induced preconditioning: A pharmacologic approach for triggering renal 'self defense'

Acute kidney injury (AKI) is a common event, occurring in ~5% and ~35% of hospitalized and ICU patients, respectively. The development of AKI portends an increased risk of morbidity, mortality, prolonged hospitalization, and subsequent development of chronic kidney disease (CKD). Given these facts, a multitude of experimental studies have addressed potential methods for inducing AKI prevention in high-risk patients. However, successful clinical translation of promising experimental data has remained elusive. Over the past decade, our laboratory has focused on developing a method for safely triggering AKI protection by inducing "kidney preconditioning" in mice by the intravenous administration of a combination of Fe sucrose (FeS) + tin protoporphyrin (SnPP). These agents induce mild, but short lived, 'oxidant stress' which synergistically activate a number of kidney 'self-defense' pathways (e.g., Nrf2, ferritin, IL-10). Within 18-24 h of Fe/SnPP administration, marked protection against diverse forms of experimental toxic and ischemic AKI results. FeS/SnPP-mediated reductions in kidney injury can also indirectly decrease injury in other organs by mitigating the so called "organ cross talk" phenomenon. Given these promising experimental data, three phase 1b clinical trials were undertaken in healthy subjects and patients with stage 3 or 4 CKD. These studies demonstrated that FeS/SnPP were well tolerated and that they up-regulated the cytoprotective Nrf2, ferritin, and IL-10 pathways. Two subsequent phase 2 trials, conducted in patients undergoing 'on-pump' cardiovascular surgery or in patients hospitalized with COVID 19, confirmed FeS/SnPP safety. Furthermore, interim data analyses revealed statistically significant improvements in several clinical parameters. The goals of this review are to: (i) briefly discuss the historical background of renal "preconditioning"; (ii) present the experimental data that support the concept of FeS/SnPP- induced organ protection; and (iii) discuss the initial results of clinical trials that suggest the potential clinical utility of an 'oxidant preconditioning' strategy.

Vagus Nerve Stimulation Attenuates Acute Kidney Injury Induced by Hepatic Ischemia/Reperfusion Injury by Suppressing Inflammation, Oxidative Stress, and Apoptosis in Rats.. [DOI: 10.21203/rs.3.rs-1937916/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Hepatic ischemia reperfusion (I/R) injury, caused by limited blood supply and subsequent blood supply, is a causative factor resulting in morbidity and mortality during liver transplantation (LT) and liver resection. Hepatic I/R injury frequently contributes to remote organ injury, such as kidney, lung, and heart. It has been demonstrated that vagus nerve stimulation (VNS) is effective in remote organ injury after ischemia reperfusion injury. Here, our aim is to investigate the potential action of VNS on hepatic I/R injury-induced acute kidney injury (AKI) and explore its underlying mechanisms. To test this hypothesis, male Sprague-Dawley rats were randomly assigned into three experimental groups: Sham group (sham operation, n=6); I/R group (hepatic I/R with sham VNS, n=6); and VNS group (hepatic I/R with VNS, n=6). VNS was performed during the entire hepatic I/R process. Our results showed that throughout the hepatic I/R process, VNS significantly reduced inflammation, oxidative stress, and apoptosis, and greatly enhanced the protein expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) in the kidneys. These findings suggest that VNS may ameliorate hepatic I/R injury-induced AKI by suppressing inflammation, oxidative stress, and apoptosis probably through activating the Nrf2/HO-1 signaling pathway.

Crosstalk between kidney and liver in non-alcoholic fatty liver disease: mechanisms and therapeutic approaches

Liver and kidney are vital organs that maintain homeostasis and injury to either of them triggers pathogenic pathways affecting the other. For example, non-alcoholic fatty liver disease (NAFLD) promotes the progression of chronic kidney disease (CKD), vice versa acute kidney injury (AKI) endorses the induction and progression of liver dysfunction. Progress in clinical and basic research suggest a role of excessive fructose intake, insulin resistance, inflammatory cytokines production, activation of the renin-angiotensin system, redox imbalance, and their impact on epigenetic regulation of gene expression in this context. Recent developments in experimental and clinical research have identified several biochemical and molecular pathways for AKI-liver interaction, including altered liver enzymes profile, metabolic acidosis, oxidative stress, activation of inflammatory and regulated cell death pathways. This review focuses on the current preclinical and clinical findings on kidney-liver crosstalk in NAFLD-CKD and AKI-liver dysfunction settings and highlights potential molecular mechanisms and therapeutic targets.

Systemic and local hepcidin as emerging and important peptides in renal homeostasis and pathology

Recent data suggest that the importance of hepcidin goes beyond its classical role in controlling systemic iron metabolism. Local hepcidins are emerging as important peptides for organ homeostasis in the brain, heart, blood vessels, and in cancer as well. Similarly, accumulating data indicate that hepcidin does seem to be an important factor in renal homeostasis. This review encompasses present knowledge concerning the role of hepcidin in renoprotection and its use as a biomarker of kidney diseases. Understanding the role of hepcidin in kidneys is important due to its relevance for kidney physiology and its potential therapeutic application in kidney pathologies. © 2018 BioFactors, 45(2):118-134, 2019.

Molecular differences in susceptibility of the kidney to sepsis-induced kidney injury

BACKGROUND

Septic acute kidney injury affects 40-50% of all septic patients. Molecular differences between septic patients with and without acute kidney injury (AKI) are only poorly understood. Here, we investigated gene expression changes that differentiated the subjects who developed septic AKI from those who did not and coupled this approach with traditional parameters of renal physiology.

METHODS

In 15 anesthetized, mechanically ventilated and instrumented pigs, progressive sepsis was induced either by peritonitis or by continuous intravenous infusion of Pseudomonas aeruginosa. Animals received standard intensive care including goal-directed hemodynamic management. Analyses were performed on kidneys from sham operated animals, septic pigs without AKI, and pigs with septic AKI. Before, and at 12, 18 and 22 h of progressive sepsis, systemic and renal hemodynamics, cortex microcirculation and plasma IL-6 and TNF-α were measured. At 22 h whole kidney expression of pre-selected genes was analyzed by quantitative Real Time PCR.

RESULTS

Animals with septic AKI had systemic hemodynamic phenotype (normo- or hyperdynamic) comparable with non-AKI subjects, but demonstrated higher plasma levels of cytokines, an increase in renal vascular resistance and early fall in cortical microcirculatory blood flow. The genes whose expression discriminated septic AKI from non-AKI included Toll like receptor 4 (up-regulated 2.7-fold, P = 0.04); Cyclooxygenase-2 (up-regulated 14.6-fold, P = 0.01), Angiotensin II Receptor (up-regulated 8.1-fold, P = 0.01), Caspase 3 (up-regulated 5.1-fold, P = 0.02), Peroxisome Proliferator-Activated Receptor Gamma, Coactivator 1 Alpha (down-regulated 2-fold, P = 0.02).

CONCLUSIONS

In this preliminary experimental study, kidney gene expression was profoundly different in animals that developed septic AKI as opposed to septic animals that did not. The biological functions of the genes differentially expressed support a role of inflammatory overstimulation coupled with metabolic and apoptotic molecular responses in early septic AKI. Cyclooxygenase-2 and angiotensin type 2 receptor-dependent downstream mechanisms appear fruitful targets for future mechanistic research.

Hepatic ischemia/reperfusion injury disrupts the homeostasis of kidney primary cilia via oxidative stress

Acute kidney injury (AKI) is a major complication of hepatic surgeries. The primary cilium protrudes to the lumen of kidney tubules and plays an important role in renal functions. Disruption of primary cilia homeostasis is highly associated with human diseases including AKI. Here, we investigated whether transient hepatic ischemia induces length change and deciliation of kidney primary cilia, and if so, whether reactive oxygen species (ROS)/oxidative stress regulates those. HIR induced damages to the liver and kidney with increases in ROS/oxidative stress. HIR shortened the cilia of kidney epithelial cells and caused them to shed into the urine. This shortening and shedding of cilia was prevented by Mn(III) tetrakis(1-methyl-4-pyridyl) porphyrin (MnTMPyP, an antioxidant). The urine of patient undergone liver resection contained ciliary proteins. These findings indicate that HIR induces shortening and deciliation of kidney primary cilia into the urine via ROS/oxidative stress, suggesting that primary cilia is associated with HIR-induced AKI and that the presence of ciliary proteins in the urine could be a potential indication of kidney injury.

Iron transport in the kidney: implications for physiology and cadmium nephrotoxicity

The kidney has recently emerged as an organ with a significant role in systemic iron (Fe) homeostasis. Substantial amounts of Fe are filtered by the kidney, which have to be reabsorbed to prevent Fe deficiency. Accordingly Fe transporters and receptors for protein-bound Fe are expressed in the nephron that may also function as entry pathways for toxic metals, such as cadmium (Cd), by way of "ionic and molecular mimicry". Similarities, but also differences in handling of Cd by these transport routes offer rationales for the propensity of the kidney to develop Cd toxicity. This critical review provides a comprehensive update on Fe transport by the kidney and its relevance for physiology and Cd nephrotoxicity. Based on quantitative considerations, we have also estimated the in vivo relevance of the described transport pathways for physiology and toxicology. Under physiological conditions all segments of the kidney tubules are likely to utilize Fe for cellular Fe requiring processes for metabolic purposes and also to contribute to reabsorption of free and bound forms of Fe into the circulation. But Cd entering tubule cells disrupts metabolic pathways and is unable to exit. Furthermore, our quantitative analyses contest established models linking chronic Cd nephrotoxicity to proximal tubular uptake of metallothionein-bound Cd. Hence, Fe transport by the kidney may be beneficial by preventing losses from the body. But increased uptake of Fe or Cd that cannot exit tubule cells may lead to kidney injury, and Fe deficiency may facilitate renal Cd uptake.

Combined iron sucrose and protoporphyrin treatment protects against ischemic and toxin-mediated acute renal failure

Tissue preconditioning, whereby various short-term stressors initiate organ resistance to subsequent injury, is well recognized. However, clinical preconditioning of the kidney for protection against acute kidney injury (AKI) has not been established. Here we tested whether a pro-oxidant agent, iron sucrose, combined with a protoporphyrin (Sn protoporphyrin), can induce preconditioning and protect against acute renal failure. Mice were pretreated with iron sucrose, protoporphyrin, cyanocobalamin, iron sucrose and protoporphyrin, or iron sucrose and cyanocobalamin. Eighteen hours later, ischemic, maleate, or glycerol models of AKI were induced, and its severity was assessed the following day (blood urea nitrogen, plasma creatinine concentrations; post-ischemic histology). Agent impact on cytoprotective gene expression (heme oxygenase 1, hepcidin, haptoglobin, hemopexin, α1-antitrypsin, α1-microglobulin, IL-10) was assessed as renal mRNA and protein levels. AKI-associated myocardial injury was gauged by plasma troponin I levels. Combination agent administration upregulated multiple cytoprotective genes and, unlike single agent administration, conferred marked protection against each tested model of acute renal failure. Heme oxygenase was shown to be a marked contributor to this cytoprotective effect. Preconditioning also blunted AKI-induced cardiac troponin release. Thus, iron sucrose and protoporphyrin administration can upregulate diverse cytoprotective genes and protect against acute renal failure. Associated cardiac protection implies potential relevance to both AKI and its associated adverse downstream effects.

Long-term remote organ consequences following acute kidney injury

Acute kidney injury (AKI) has been a global health epidemic problem with soaring incidence, increased long-term risks for multiple comorbidities and mortality, as well as elevated medical costs. Despite the improvement of patient outcomes following the advancements in preventive and therapeutic strategies, the mortality rates among critically ill patients with AKI remain as high as 40–60 %. The distant organ injury, a direct consequence of deleterious systemic effects, following AKI is an important explanation for this phenomenon. To date, most evidence of remote organ injury in AKI is obtained from animal models. Whereas the observations in humans are from a limited number of participants in a relatively short follow-up period, or just focusing on the cytokine levels rather than clinical solid outcomes. The remote organ injury is caused with four underlying mechanisms: (1) “classical” pattern of acute uremic state; (2) inflammatory nature of the injured kidneys; (3) modulating effect of AKI of the underlying disease process; and (4) healthcare dilemma. While cytokines/chemokines, leukocyte extravasation, oxidative stress, and certain channel dysregulation are the pathways involving in the remote organ damage. In the current review, we summarized the data from experimental studies to clinical outcome studies in the field of organ crosstalk following AKI. Further, the long-term consequences of distant organ-system, including liver, heart, brain, lung, gut, bone, immune system, and malignancy following AKI with temporary dialysis were reviewed and discussed.

Marked protection against acute renal and hepatic injury after nitrited myoglobin + tin protoporphyrin administration

The phenomenon known as renal "ischemic preconditioning," whereby an initial ischemic insult induces resistance against subsequent kidney damage, has been well established in the experimental literature. However, a clinically applicable way to safely recapitulate this state has not been defined. We hypothesized that a unique combination of agents (nitrited myoglobin [N-Mgb] + tin protoporphyrin [SnPP]) can achieve these ends safely and synergistically, increasing cytoprotective proteins (eg, heme oxygenase 1 [HO-1], interleukin 10 [IL-10], and haptoglobin) in kidney cells. To test this hypothesis, CD-1 mice received 1 mg of N-Mgb and 1 μmol of SnPP, either alone or in combination. Renal cortical HO-1, haptoglobin, and IL-10 gene expressions (messenger RNA [mRNA], protein levels) were determined 4 and 18 hours later. Cytoresistance to 3 forms of acute kidney injury (AKI; glycerol-induced rhabdomyolysis, maleate nephrotoxicity, and postischemic AKI progression to chronic kidney disease [CKD]) was assessed. To ascertain whether cytoresistance might emerge in extrarenal organs, hepatic HO-1, IL-10, and haptoglobin levels were also measured, and resistance to 25 minutes of hepatic ischemia-reperfusion injury and hepatotoxicity (intraperitoneal glycerol injection) was sought. N-Mgb + SnPP induced additive or synergistic increases in renal HO-1, haptoglobin, and IL-10 mRNA and protein levels (up to 20-fold) without inducing any apparent renal or extrarenal damage. After 18 hours of post-treatment, marked or complete protection against glycerol-induced AKI, maleate-induced AKI, and postischemic AKI progression to CKD had emerged. Combined N-Mgb + SnPP was more protective than either agent alone (assessed in glycerol model). N-Mgb + SnPP also upregulated cytoprotective pathways in liver and induced marked protection against both hepatic ischemia-reperfusion and toxic liver damage. In conclusion, we posit that "preconditioning" with combined administration of N-Mgb + SnPP represents a promising approach for protecting against diverse forms of renal and nonrenal (hepatic) forms of tissue damage.