Powerful protection against renal ischemia reperfusion injury by T cell-specific NF-κB inhibition

Protective effects of pioglitazone in renal ischemia-reperfusion injury (RIRI): focus on oxidative stress and inflammation

BACKGROUND

Renal ischemia-reperfusion injury (RIRI) is a critical phenomenon that compromises renal function and is the most serious health concern related to acute kidney injury (AKI). Pioglitazone (Pio) is a known agonist of peroxisome proliferator-activated receptor-gamma (PPAR-γ). PPAR-γ is a nuclear receptor that regulates genes involved in inflammation, metabolism, and cellular differentiation. Activation of PPAR-γ is associated with antiinflammatory and antioxidant effects, which are relevant to the pathophysiology of RIRI. This study aimed to investigate the protective effects of Pio in RIRI, focusing on oxidative stress and inflammation.

METHODS

We conducted a comprehensive literature search using electronic databases, including PubMed, ScienceDirect, Web of Science, Scopus, and Google Scholar.

RESULTS

The results of this study demonstrated that Pio has antioxidant, anti-inflammatory, and anti-apoptotic activities that counteract the consequences of RIRI. The study also discussed the underlying mechanisms, including the modulation of various pathways such as TNF-α, NF-κB signaling systems, STAT3 pathway, KIM-1 and NGAL pathways, AMPK phosphorylation, and autophagy flux. Additionally, the study presented a summary of various animal studies that support the potential protective effects of Pio in RIRI.

CONCLUSION

Our findings suggest that Pio could protect the kidneys from RIRI by improving antioxidant capacity and decreasing inflammation. Therefore, these findings support the potential of Pio as a therapeutic strategy for preventing RIRI in different clinical conditions.

Tim-3 deficiency aggravates cadmium nephrotoxicity via regulation of NF-κB signaling and mitochondrial damage

Kidney is the target organ of serious cadmium injury. Kidney damage caused by cadmium exposure is greatly influenced by the inflammatory response and mitochondrial damage. T cell immunoglobulin domain and mucin domain 3 (Tim-3) is an essential protein that functions as a negative immunological checkpoint to regulate inflammatory responses. Mice were given cadmium treatments at various dosages (0, 1.5, 3, 4.5 mg/kg) and times (0, 3, 5, 7 days) to assess the effects of cadmium on kidney damage. We found that the optimal way to induce kidney injury in mice was to inject 4.5 mg/kg of cadmium intraperitoneally for five days. It is interesting that giving mice 4.5 mg/kg of cadmium intravenously for seven days drastically lowered their survival rate. After cadmium exposure, Tim-3 knockout mice exhibited higher blood concentrations of urea nitrogen and creatinine compared to control mice. Tim-3 impacted the expression of oxidative stress-associated genes such as UDP glucuronosyltransferase family 1 member A9 (Ugt1a9), oxidative stress-induced growth inhibitor 2 (Osgin2), and S100 calcium binding protein A8 (S100a8), according to RNA-seq and real-time RT-PCR data. Tim-3 deficiency also resulted in activated nuclear factor-kappa B (NF-κB) signaling pathway. The NF-κB inhibitor 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1) significantly alleviated cell apoptosis, oxidative stress response, and renal tubule inflammation in Tim-3 knockout mice exposed to cadmium. Furthermore, cadmium caused obvious B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax) translocation from cytoplasm to mitochondria, which can be inhibited by TPCA-1. In conclusion, Tim-3 prevented mitochondrial damage and NF-κB signaling activation, hence providing protection against cadmium nephrotoxicity.

IKK1 aggravates ischemia-reperfusion kidney injury by promoting the differentiation of effector T cells

Ischemia-reperfusion injury (IRI) is one of the major causes of acute kidney injury (AKI), and experimental work has revealed detailed insight into the inflammatory response in the kidney. T cells and NFκB pathway play an important role in IRI. Therefore, we examined the regulatory role and mechanisms of IkappaB kinase 1 (IKK1) in CD4⁺T lymphocytes in an experimental model of IRI. IRI was induced in CD4cre and CD4IKK1Δ mice. Compared to control mice, conditional deficiency of IKK1 in CD4⁺T lymphocyte significantly decreased serum creatinine, blood urea nitrogen (BUN) level, and renal tubular injury score. Mechanistically, lack in IKK1 in CD4⁺T lymphocytes reduced the ability of CD4 lymphocytes to differentiate into Th1/Th17 cells. Similar to IKK1 gene ablation, pharmacological inhibition of IKK also protected mice from IRI. Together, lymphocyte IKK1 plays a pivotal role in IRI by promoting T cells differentiation into Th1/Th17 and targeting lymphocyte IKK1 may be a novel therapeutic strategy for IRI.

Minimizing Ischemia Reperfusion Injury in Xenotransplantation

The recent dramatic advances in preventing "initial xenograft dysfunction" in pig-to-non-human primate heart transplantation achieved by minimizing ischemia suggests that ischemia reperfusion injury (IRI) plays an important role in cardiac xenotransplantation. Here we review the molecular, cellular, and immune mechanisms that characterize IRI and associated "primary graft dysfunction" in allotransplantation and consider how they correspond with "xeno-associated" injury mechanisms. Based on this analysis, we describe potential genetic modifications as well as novel technical strategies that may minimize IRI for heart and other organ xenografts and which could facilitate safe and effective clinical xenotransplantation.

Intratubular, Intracellular, and Mitochondrial Angiotensin II/AT1 (AT1a) Receptor/NHE3 Signaling Plays a Critical Role in Angiotensin II-Induced Hypertension and Kidney Injury

Hypertension is well recognized to be the most important risk factor for cardiovascular diseases, stroke, and end-stage kidney failure. A quarter of the world’s adult populations and 46% of the US adults develop hypertension and currently require antihypertensive treatments. Only 50% of hypertensive patients are responsive to current antihypertensive drugs, whereas remaining patients may continue to develop cardiovascular, stroke, and kidney diseases. The mechanisms underlying the poorly controlled hypertension remain incompletely understood. Recently, we have focused our efforts to uncover additional renal mechanisms, pathways, and therapeutic targets of poorly controlled hypertension and target organ injury using novel animal models or innovative experimental approaches. Specifically, we studied and elucidated the important roles of intratubular, intracellular, and mitochondrial angiotensin II (Ang II) system in the development of Ang II-dependent hypertension. The objectives of this invited article are to review and discuss our recent findings that (a) circulating and intratubular Ang II is taken up by the proximal tubules via the (AT₁) AT_1a receptor-dependent mechanism, (b) intracellular administration of Ang II in proximal tubule cells or adenovirus-mediated overexpression of an intracellular Ang II fusion protein selectively in the mitochonria of the proximal tubules induces blood pressure responses, and (c) genetic deletion of AT₁ (AT_1a) receptors or the Na⁺/H⁺ exchanger 3 selectively in the proximal tubules decreases basal blood pressure and attenuates Ang II-induced hypertension. These studies provide a new perspective into the important roles of the intratubular, intracellular, and mitochondrial angiotensin II/AT₁ (AT_1a) receptor signaling in Ang II-dependent hypertensive kidney diseases.

Ursolic acid: A systematic review of its pharmacology, toxicity and rethink on its pharmacokinetics based on PK-PD model

Ursolic acid (UA) is a natural pentacyclic triterpenoid compound existing in various traditional Chinese medicinal herbs, and it possesses diverse pharmacological actions and some undesirable adverse effects, even toxicological activities. Due to UA's low solubility and poor bioavailability, and its interaction with gut microbiota after oral administration, the pharmacokinetics of UA remain elusive, leading to obscurity in the pharmacokinetics-pharmacodynamics (PK-PD) profile and relationship for UA. Based on literatures from PubMed, Google Scholar, ResearchGate, Web of Science and Wiley Online Library, with keywords of "pharmacology", "toxicology", "pharmacokinetics", "PK-PD" and "ursolic acid", herein we systematically review the pharmacology and toxicity of UA, and rethink on its pharmacokinetics on the basis of PK-PD model, and seek to delineate the underlying mechanisms for the characteristics of pharmacology and toxicology of UA, and for the pharmacokinetic features of UA particularly from the organ tropism and the interactions between UA and gut microbiota, and lay a solid foundation for development of UA-derived therapeutic agents in clinical settings.

Neurogenic tachykinin mechanisms in experimental nephritis of rats

We demonstrated earlier that renal afferent pathways combine very likely “classical” neural signal transduction to the central nervous system and a substance P (SP)–dependent mechanism to control sympathetic activity. SP content of afferent sensory neurons is known to mediate neurogenic inflammation upon release. We tested the hypothesis that alterations in SP-dependent mechanisms of renal innervation contribute to experimental nephritis. Nephritis was induced by OX-7 antibodies in rats, 6 days later instrumented for recording of blood pressure (BP), heart rate (HR), drug administration, and intrarenal administration (IRA) of the TRPV1 agonist capsaicin to stimulate afferent renal nerve pathways containing SP and electrodes for renal sympathetic nerve activity (RSNA). The presence of the SP receptor NK-1 on renal immune cells was assessed by FACS. IRA capsaicin decreased RSNA from 62.4 ± 5.1 to 21.6 ± 1.5 mV s (*p < 0.05) in controls, a response impaired in nephritis. Suppressed RSNA transiently but completely recovered after systemic administration of a neurokinin 1 (NK1-R) blocker. NK-1 receptors occurred mainly on CD11⁺ dendritic cells (DCs). An enhanced frequency of CD11c⁺NK1R⁺ cell, NK-1 receptor⁺ macrophages, and DCs was assessed in nephritis. Administration of the NK-1R antagonist aprepitant during nephritis reduced CD11c⁺NK1R⁺ cells, macrophage infiltration, renal expression of chemokines, and markers of sclerosis. Hence, SP promoted renal inflammation by weakening sympathoinhibitory mechanisms, while at the same time, substance SP released intrarenally from afferent nerve fibers aggravated immunological processes i.e. by the recruitment of DCs.

Histone Methylation Inhibitor DZNep Ameliorated the Renal Ischemia-Reperfusion Injury via Inhibiting TIM-1 Mediated T Cell Activation

Renal ischemia-reperfusion injury (IRI) after renal transplantation often leads to the loss of kidney graft function. However, there is still a lack of efficient regimens to prevent or alleviate renal IRI. Our study focused on the renoprotective effect of 3-Deazaneplanocin A (DZNep), which is a histone methylation inhibitor. We found that DZNep significantly alleviated renal IRI by suppressing nuclear factor kappa-B (NF-κB), thus inhibiting the expression of inflammatory factors in renal tubular epithelial cells in vivo or in vitro. After treatment with DZNep, T cell activation was impaired in the spleen and kidney, which correlated with the downregulated expression of T-cell immunoglobulin mucin (TIM)-1 on T cells and TIM-4 in macrophages. In addition, pretreatment with DZNep was not sufficient to protect the kidney, while administration of DZNep from before to after surgery significantly ameliorated IRI. Our findings suggest that DZNep can be a novel strategy for preventing renal IRI following kidney transplantation.

Protective effects of hydroalcoholic extracts from an ancient apple variety 'Mela Rosa dei Monti Sibillini' against renal ischemia/reperfusion injury in rats

The purpose of this work was to investigate the effect of hydroalcoholic extracts from the peel (APE) and pulp (APP) of a traditional apple variety of central Italy, the 'Mela Rosa dei Monti Sibillini', on the damage caused by renal ischemia/reperfusion injury (IRI) in rats. Thirty mg per kg b.w. of the extracts were administered intraperitoneally to male adult Wistar rats 3 days before the induction of IRI by pedicle clamping. A significant decrease in the levels of malondialdehyde (MDA), tumor necrosis factor-α (TNFα), interleukin 1 beta (IL-1β) and nuclear factor-κB (NF-κB) was observed in the groups pre-treated with APE when compared with IRI rats. The chemical composition of APE was determined by HPLC-DAD-MSⁿ highlighting a significant amount of proanthocyanidins (52.9 mg g^-1), flavonols (42.27 mg g^-1) and dihydrochalcones (11.75 mg g^-1). These findings indicated that this ancient apple variety is a promising source of nutraceuticals and functional foods helpful to manage complications of renal disorders.

NFκB and Kidney Injury

The global burden of chronic kidney disease will increase during the next century. As NFκB, first described more than 30 years ago, plays a major role in immune and non-immune-mediated diseases and in inflammatory and metabolic disorders, this review article summarizes current knowledge on the role of NFκB in in vivo kidney injury and describes the new and so far not completely understood crosstalk between canonical and non-canonical NFκB pathways in T-lymphocyte activation in renal disease.

FTY720 Effects on Inflammation and Liver Damage in a Rat Model of Renal Ischemia-Reperfusion Injury

Objective

Ischemia-reperfusion injury (IRI) produces systemic inflammation with the potential for causing organ failure in tissues peripheral to the initial site of injury. We speculate that treatment strategies that dampen inflammation may be therapeutically beneficial to either the initial site of injury or peripheral organs. To test this, we evaluated the impact of FTY720-induced sequestration of circulating mature lymphocytes on renal IRI and secondary organ injury.

Methods

A microvascular clamp was surgically placed around the left renal pedicle of anesthetized male Sprague-Dawley rats with either vehicle or FTY720 treatment (0.3 mg/kg) intravenously injected after 15 min of ischemia. Blood flow was restored after 60 min. Cohorts of anesthetized rats were euthanized at 6, 24, or 72 hrs with tissue samples collected for analysis.

Results

FTY720 treatment resulted in profound T lymphocyte reduction in peripheral blood. Histopathologic examination, clinical chemistries, and gene transcript expression measurements revealed that FTY720 treatment reduced hepatocellular degeneration, reduced serum markers of liver injury (ALT/AST), and reduced the expression of gene targets associated with IRI.

Conclusion

These findings support an anti-inflammatory effect of FTY720 in the liver where the expression of genes associated with apoptosis, chemotaxis, and the AP-1 transcription factor was reduced. Findings presented here provide the basis for future studies evaluating FTY720 as a potential therapeutic agent to treat complications resulting from renal IRI.

Bruton Tyrosine Kinase Inhibition Attenuates Liver Damage in a Mouse Warm Ischemia and Reperfusion Model

BACKGROUND

Bruton tyrosine kinase (Btk) is a central player in multiple signaling pathways of lymphoid and myeloid cells. Myeloid cells are crucial early effectors in organ ischemia-reperfusion (IR) injury. BTKB66 is a selective, irreversible inhibitor of Btk. In this study, we hypothesized that Btk inhibition would reduce hepatocellular injury in a murine model of liver warm hepatic IR.

METHODS

First, BTKB66 was tested in in vitro models of lipopolysaccharide-mediated neutrophil and macrophage activation. Then, to assess its efficacy in vivo, BTKB66 was administered orally to mice for 7 days before subjecting them to 90 minutes of warm hepatic ischemia followed by reperfusion for 6 or 24 hours. Clinical and pathologic features in the livers, including AST, ALT, and a panel of cytokines and chemokines, were examined.

RESULTS

BTKB66 potently inhibited lipopolysaccharide-mediated activation of bone marrow-derived neutrophils and macrophages in vitro. It also reduced the severity of IR injury as determined by AST and ALT levels, as well as immune cell infiltrates. BTKB66 significantly decreased hepatic markers of sterile inflammation, such as C-X-C motif chemokine 1, C-X-C motif chemokine 2, and C-X-C motif chemokine 10, in parallel with depression of serum markers of the myeloid cell activation, such as CCL5, CCL11, and C-X-C motif chemokine 5.

CONCLUSIONS

BTKB66 treatment ameliorated hepatocellular injury in a well-established model of liver partial warm ischemia and in situ reperfusion. These findings confirm that neutrophil recruitment and activation play an essential role in IR stress, and that targeting Btk activity may provide a useful approach for preventing hepatocellular damage and improving outcomes in liver transplantation.

Dual antiplatelet and anticoagulant APAC prevents experimental ischemia-reperfusion-induced acute kidney injury

BACKGROUND

Renal ischemia-reperfusion predisposes to acute kidney injury (AKI) and mortality. APAC, mast cell heparin proteoglycan mimetic is a potent dual antiplatelet and anticoagulant inhibiting thrombosis in several vascular models.

METHODS

Clinically relevant (0.06 and 0.13 mg/kg) and high (0.32 and 7.3 mg/kg) heparin doses of APAC and unfractionated heparin (UFH) were administered i.v. in pharmacological studies. Antithrombotic action of APAC and UFH was assessed with platelet aggregation to collagen, activated partial thromboplastin (APTT) and prothrombin (PT) times. Pharmacodynamics of [⁶⁴Cu]-APAC or -UFH were monitored by PET/CT. Next, APAC and UFH doses (0.06 and 0.13 mg/kg) were i.v. administered 10 min prior to renal ischemia-reperfusion injury (IRI) in rats.

RESULTS

APAC in contrast to UFH inhibited platelet aggregation. During 0.06 and 0.13 mg/kg dose regimens APTT and PT remained at baseline, but at the high APTT prolonged fourfold to sixfold. Overall bio-distribution and clearance of APAC and UFH were similar. After bilateral 30-min renal artery clamping, creatinine, urea nitrogen and neutrophil gelatinase-associated lipocalin concentrations and histopathology indicated faster renal recovery by APAC (0.13 mg/kg). APAC, unlike UFH, prevented expression of innate immune ligand hyaluronan and tubulointerstitial injury marker Kim-1. Moreover, in severe bilateral 1-h renal artery clamping, APAC (0.13 mg/kg) prevented AKI, as demonstrated both by biomarkers and survival. Compatible with kidney protection APAC reduced the circulating levels of vascular destabilizing and pro-inflammatory angiopoietin-2 and syndecan-1. No tissue bleeding ensued.

CONCLUSION

APAC and UFH were similarly eliminated via kidneys and liver. In contrast to UFH, APAC (0.13 mg/kg) was reno-protective in moderate and even severe IRI by attenuating vascular injury and innate immune activation.

Low-dose testosterone protects against renal ischemia-reperfusion injury by increasing renal IL-10-to-TNF-α ratio and attenuating T-cell infiltration

Renal ischemia-reperfusion (I/R) in male rats causes reductions in plasma testosterone, and infusion of testosterone 3 h postreperfusion is protective. We tested the hypotheses that acute high doses of testosterone promote renal injury after I/R, and that acute low-dose testosterone is protective by the following: 1) increasing renal IL-10 and reducing TNF-α; 2) its effects on nitric oxide; and 3) reducing intrarenal T-cell infiltration. Rats were subjected to renal I/R, followed by intravenous infusion of vehicle or testosterone (20, 50, or 100 μg/kg) 3 h postreperfusion. Low-dose testosterone (20 μg/kg) reduced plasma creatinine, increased nitrate/nitrite excretion, increased intrarenal IL-10, and reduced intrarenal TNF-α, whereas 50 μg/kg testosterone failed to reduce plasma creatinine, increased IL-10, but failed to reduce TNF-α. A higher dose of testosterone (100 mg/kg) not only failed to reduce plasma creatinine, but significantly increased both IL-10 and TNF-α compared with other groups. Low-dose nitro-l-arginine methyl ester (1 mg·kg(-1)·day(-1)), given 2 days before I/R, prevented low-dose testosterone (20 μg/kg) from protecting against I/R injury, and was associated with lack of increase in intrarenal IL-10. Intrarenal CD4(+) and CD8(+) T cells were significantly increased with I/R, but were attenuated with low-dose testosterone, as were effector T helper 17 cells. The present studies suggest that acute, low-dose testosterone is protective against I/R AKI in males due to its effects on inflammation by reducing renal T-cell infiltration and by shifting the balance to favor anti-inflammatory cytokine production rather than proinflammatory cytokines.

Pharmacological inhibition of MyD88 homodimerization counteracts renal ischemia reperfusion-induced progressive renal injury in vivo and in vitro

The activation of innate immunity via myeloid differentiation factor 88 (MyD88) contributes to ischemia reperfusion (I/R) induced acute kidney injury (AKI) and chronic kidney injury. However, since there have not yet been any effective therapy, the exact pharmacological role of MyD88 in the prevention and treatment of renal ischemia reperfusion injury (IRI) is not known. We designed a small molecular compound, TJ-M2010-2, which inhibited MyD88 homodimerization. We used an established unilateral I/R mouse model. All mice undergoing 80 min ischemia through uninephrectomy died within five days without intervention. However, treatment with TJ-M2010-2 alone significantly improved the survival rate to 58.3%. Co-treatment of TJ-M2010-2 with the CD154 antagonist increased survival rates up to 100%. Twenty-eight days post-I/R of 60 min ischemia without nephrectomy, TJ-M2010-2 markedly attenuated renal interstitial and inhibited TGF-β1-induced epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells. Furthermore, TJ-M2010-2 remarkably inhibited TLR/MyD88 signaling in vivo and in vitro. In conclusion, our findings highlight the promising clinical potential of MyD88 inhibitor in preventing and treating acute or chronic renal I/R injuries, and the therapeutic functionality of dual-system inhibition strategy in IRI-induced AKI. Moreover, MyD88 inhibition ameliorates renal I/R injury-induced tubular interstitial fibrosis by suppressing EMT.

Update on ischemia-reperfusion injury in kidney transplantation: Pathogenesis and treatment

Ischemia/reperfusion injury is an unavoidable relevant consequence after kidney transplantation and influences short term as well as long-term graft outcome. Clinically ischemia/reperfusion injury is associated with delayed graft function, graft rejection, chronic rejection and chronic graft dysfunction. Ischemia/reperfusion affects many regulatory systems at the cellular level as well as in the renal tissue that result in a distinct inflammatory reaction of the kidney graft. Underlying factors of ischemia reperfusion include energy metabolism, cellular changes of the mitochondria and cellular membranes, initiation of different forms of cell death-like apoptosis and necrosis together with a recently discovered mixed form termed necroptosis. Chemokines and cytokines together with other factors promote the inflammatory response leading to activation of the innate immune system as well as the adaptive immune system. If the inflammatory reaction continues within the graft tissue, a progressive interstitial fibrosis develops that impacts long-term graft outcome. It is of particular importance in kidney transplantation to understand the underlying mechanisms and effects of ischemia/reperfusion on the graft as this knowledge also opens strategies to prevent or treat ischemia/reperfusion injury after transplantation in order to improve graft outcome.