Protective effect of renal ischemic postconditioning in renal ischemic-reperfusion injury

The Role of the JAK-STAT Signaling Pathway in the Protective Effects of Hepatic Ischemia Post-conditioning Against the Injury Induced by Ischemia/Reperfusion in the Rat Liver

Purpose

Hepatic ischemic post-conditioning (IPOC) is shown to protect the liver from injury induced by ischemia/reperfusion (IR). However, the mechanism underlying this protection has remained elusive. The present study aimed to investigate the role of the interleukin 6-Janus kinase-signal transducers and activators of transcription (IL-6-JAK-STAT) pathway in the protective effect of hepatic IPOC against the IR-induced injury in the liver.

Methods

Twenty-five rats were randomly divided into 5 groups of (1) sham-operated, (2) IR, (3) IR+hepatic IPOC, (4) IR+tofacitinib (TOFA), and (5) IR+TOFA+hepatic IPOC. The changes induced by IR and the effects of different treatments were assessed by enzyme release, histopathological observations, the serum level of IL-6, and the occurrence of apoptosis detected via the expression of the Bax/Bcl-2 ratio.

Results

The hepatic IPOC improved the liver injury induced by IR as shown by histological changes, reduction of IL-6 level, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) compared to the IR group (P<0.001, P<0.05, P<0.05, respectively). There was also downregulation of the Bax/Bcl2 ratio in the rats exposed to IR+hepatic IPOC compared with those in the IR group (P<0.05). However, TOFA, an inhibitor of JAK-STAT activity, inhibited the protective effect of hepatic IPOC.

Conclusion

It suggests that the protective effect of hepatic IPOC against IR-induced injury may be mediated by activating the IL-6-JAK-STAT pathway.

An update on the molecular mechanism and pharmacological interventions for Ischemia-reperfusion injury by regulating AMPK/mTOR signaling pathway in autophagy

AMP-activated protein kinase (5'-adenosine monophosphate-activated protein kinase, AMPK)/mammalian target of rapamycin (mTOR) is an important signaling pathway maintaining normal cell function and homeostasis in vivo. The AMPK/mTOR pathway regulates cellular proliferation, autophagy, and apoptosis. Ischemia-reperfusion injury (IRI) is secondary damage that frequently occurs clinically in various disease processes and treatments, and the exacerbated injury during tissue reperfusion increases disease-associated morbidity and mortality. IRI arises from multiple complex pathological mechanisms, among which cell autophagy is a focus of recent research and a new therapeutic target. The activation of AMPK/mTOR signaling in IRI can modulate cellular metabolism and regulate cell proliferation and immune cell differentiation by adjusting gene transcription and protein synthesis. Thus, the AMPK/mTOR signaling pathway has been intensively investigated in studies focused on IRI prevention and treatment. In recent years, AMPK/mTOR pathway-mediated autophagy has been found to play a crucial role in IRI treatment. This article aims to elaborate the action mechanisms of AMPK/mTOR signaling pathway activation in IRI and summarize the progress of AMPK/mTOR-mediated autophagy research in the field of IRI therapy.

GATA2 promotes oxidative stress to aggravate renal ischemia-reperfusion injury by up-regulating Redd1

Renal ischemia-reperfusion injury (RIRI) is a common pathophysiological process, and it is also an important cause of acute renal failure. Therefore, finding an effective therapeutic target for RIRI is extremely urgent. In our study, we constructed hypoxia-reoxygenation (HR) model in vitro and a renal ischemia-reperfusion (IR) model in vivo. Elevated levels of serum creatinine (Cr), blood urea nitrogen (BUN) tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and malondialdehyde (MDA) along with the decreased levels of superoxide dismutase (SOD) and glutathione (GSH) proved that kidney function was damaged after IR, and pathological changes of renal tissues were observed using HE staining and TUNEL staining. The protein of Redd1 expression level was detected to be upregulated after IR by western blot (WB). However, transfection of short hairpin RNA of Redd1 (sh-Redd1) alleviated the HR injury on LLC-PK1 cells, as evidenced by increased cell viability, proliferation and decreased cell apoptosis; additionally, the accumulation of ROS was inhibited. Sh-Redd1 also alleviated IR injury in the mouse model. Subsequently, GATA2 was proved to be upregulated in IR and HR models and was the transcription factor of Redd1. Knockdown of GATA2 efficiently mitigated the oxidative stress induced damages in vivo and in vitro, while these mitigations were reversed by transfection of Redd1 overexpression plasmid. In conclusion, our study clarified the possible underlying mechanism of protecting RIRI.

Sevoflurane participates in the protection of rat renal ischemia-reperfusion injury by down-regulating the expression of TRPM7

INTRODUCTION

To investigate the protective effect of sevoflurane preconditioning on renal ischemia-reperfusion injury (renalischemiareperfusionmodel, RIRI) and its related mechanism.

METHODS

Eighty healthy adult male SD rats were randomly divided into control group (Sham group), model group (RIRI group), sevoflurane pretreatment group (Sev group) and TRPM7 inhibitor combined with sevoflurane pretreatment group (T + Sev group), 20 animals in each group. Hematoxylin-eosin (HE) staining was used to observe the pathological changes of renal tissue, and the levels of creatinine and urea nitrogen in each group were detected. Deoxyribonucleic acid terminal transferase-mediated dUTP nick end labeling (TUNEL) assay was used to detect renal cell apoptosis, and Western blottingwas used to detect the expression of apoptotic proteins cleaved-caspase-3, bax, Bcl-2, and TRPM7 in renal tissue; Detection of oxidative stress-related index levels in renal tissue and levels of inflammatory factors in renal tissue and serum.

RESULTS

Compared with the Sham group, the renal tissue pathological damage was aggravated, the levels of creatinine and blood urea nitrogen were increased, and the apoptosis was increased in the RIR group and the Sev group. Death, malondialdehyde (MDA) levels and inflammatory factors were increased, and superoxide dismutase (SOD) levels were decreased (all p < .05); The scores, apoptosis rate, MDA level, and relative expression of inflammatory factor levels were decreased, and SOD levels were increased (all p < .05). Compared with the Sev group, the renal tissue pathological damage in the T + Sev group was aggravated, creatinine, blood urea nitrogen levels increased, apoptosis increased, apoptosis-related proteins cleaved-caspase-3, bax, Bcl-2 showed increased apoptosis, malondialdehyde (MDA) levels, inflammatory factor levels increased, ultrahigh The levels of oxide dismutase (SOD) were decreased (all p < .05).

CONCLUSIONS

Therefore, we believe that sevoflurane is involved in the protection of rat renal ischemia-reperfusion injury by downregulating the expression of TRPM7.

A molecular network-based pharmacological study on the protective effect of Panax notoginseng rhizomes against renal ischemia-reperfusion injury

Objective: We aimed to explore the protective effect of Panax notoginseng rhizomes (PNR) on renal ischemia and reperfusion injury (RIRI) and the underlying molecular network mechanism based on network pharmacology and combined systemic experimental validation. Methods: A bilateral RIRI model was established, and Cr, SCr, and BUN levels were detected. Then, the PNR was pretreated 1 week before the RIRI model was prepared. To determine the effects of the PNR in RIRI, histopathological damage and the effect of PNRs to the kidney was assessed, using TTC, HE, and TUNEL staining. Furthermore, the underlying network pharmacology mechanism was detected by screening drug-disease intersection targets from PPI protein interactions and GO and KEGG analysis, and the hub genes were screened for molecular docking based on the Degree value. Finally, the expression of hub genes in kidney tissues was verified by qPCR, and the protein expression of related genes was further detected by Western blot (WB). Results: PNR pretreatment could effectively increase Cr level, decrease SCr and BUN levels, reduce renal infarct areas and renal tubular cell injury areas, and inhibit renal cell apoptosis. By using network pharmacology combined with bioinformatics, we screened co-targets both Panax notoginseng (Sanchi) and RIRI, acquired ten hub genes, and successfully performed molecular docking. Of these, pretreatment with the PNR reduced the mRNA levels of IL6 and MMP9 at postoperative day 1 and TP53 at postoperative day 7, and the protein expression of MMP9 at postoperative day 1 in IRI rats. These results showed that the PNR could decrease kidney pathological injury in IRI rats and inhibit apoptotic reaction and cell inflammation so as to improve renal injury effectively, and the core network mechanism is involved in the inhibition of MMP9, TP53, and IL-6. Conclusion: The PNR has a marked protective effect for RIRI, and the underlying mechanism is involved in inhibiting the expression of MMP9, TP53, and IL-6. This striking discovery not only provides fruitful evidence for the protective effect of the PNR in RIRI rats but also provides a novel mechanic explanation.

A novel fluorescent probe for real-time imaging of thionitrous acid under inflammatory and oxidative conditions

Thionitrous acid (HSNO), a crosstalk intermediate of two crucial gasotransmitters nitric oxide and hydrogen sulfide, plays a critical role in redox regulation of cellular signaling and functions. However, real-time and facile detection of HSNO with high selectivity and sensitivity remains highly challenging. Herein we report a novel fluorescent probe (SNP-1) for HSNO detection. SNP-1 has a simple molecular structure, but showing strong fluorescence, a low detection limit, a broad linear detection range (from nanomolar to micromolar concentrations), ultrasensitivity, and high selectivity for HSNO in both aqueous media and cells. Benefiting from these unique features, SNP-1 could effectively visualize changes of HSNO levels in mouse models of acute ulcerative colitis and renal ischemia/reperfusion injury. Moreover, the good correlation between colonic HSNO levels and disease activity index demonstrated that HSNO is a promising new diagnostic agent for acute ulcerative colitis. Therefore, SNP-1 can serve as a useful fluorescent probe for precision detection of HSNO in various biological systems, thereby facilitating mechanistic studies, therapeutic assessment, and high-content drug screening for corresponding diseases.

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HSNO was the preferred intermediate to study crosstalk between H₂S and NO.

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HSNO displayed translational potential for diagnosis and assessment of diseases.

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SNP-1 displayed excellent fluorescence performance for HSNO detection.

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SNP-1 could effectively image HSNO in cells and mouse models.

Ischemic postconditioning ameliorates acute kidney injury induced by limb ischemia/reperfusion via transforming TLR4 and NF-κB signaling in rats

BACKGROUND

The present study investigated the influence of ischemic postconditioning (I-postC) on the adjustment of renal injury after limb ischemia-reperfusion (I/R) injury, to elucidate the mechanisms of the Toll-like receptor 4 (TLR 4)/NF-κB signaling pathway using histopathological and immunohistochemical methods.

METHODS

Male Sprague-Dawley rats were randomly assigned to five groups (numbered from 1 to 5): the sham group (Group 1, only the anesthesia procedure was conducted without limb I/R), the I/R group (Group 2, 4 h of reperfusion was conducted following 4 h limb ischemia under anesthesia), the I/R + I-postC group (Group 3, 4 h of ischemia and 4 h of reperfusion was conducted; before perfusion, 5 min of limb ischemia and 5 min of reperfusion were performed in the rats and repeated 3 times), the I/R + TAK group (Group 4, rats were injected with TLR4 antagonist TAK through the caudal vein before limb ischemia and reperfusion under anesthesia), the TAK group (Group 5, rats were injected with TAK, and the anesthesia procedure was conducted without limb I/R). Histological changes in the kidney in different groups were observed, and the extent of tubular injury was assessed. Changes in biochemical indexes and the expression of inflammatory factors, TLR4, and NF-κB were also evaluated.

RESULTS

Compared with rats in the I/R group, the secretion of inflammatory factors and the expression levels of TLR4 and NF-κB were decreased in rats in the I/R + I-postC group. Histological analysis revealed renal injury, including inflammatory cell infiltration, dilatation of the tubuli lumen, congestion in glomerular capillaries, degeneration of tubuli epithelial cells, and necrosis was ameliorated by I-postC. Immunohistochemical studies showed that I/R-induced elevation in TLR4 and NF-κB expression was reduced by I-postC treatment. Moreover, the expression levels of TLR4, NF-κB, and inflammatory factors in rats in the I/R + TAK group were also decreased, and the renal pathological lesion was alleviated, which was similar to that in rats in the I/R + I-postC group.

CONCLUSIONS

The present findings suggest that I-postC can reduce tissue injury and kidney inflammation induced by limb I/R injury, possibly via inhibition of the TLR4 and NF-κB pathways.

Propofol ameliorates renal ischemia/reperfusion injury by enhancing macrophage M2 polarization through PPARγ/STAT3 signaling

Propofol (Pro) confers protection against renal ischemia/reperfusion (rI/R) injury through incompletely characterized mechanisms. Since Pro has shown net anti-inflammatory properties as part of its beneficial effects, we examined the potential role of Pro in the modulation of macrophage polarization status during both rI/R injury in vivo and exposure of cultured peritoneal macrophages (PMs) to hypoxia/reoxygenation (H/R). Rats were subjected to 45-min r/IR surgery or a sham procedure and administered PBS (vehicle) or Pro during the ischemia stage. Pro administration attenuated rI/R-induced kidney damage and renal TNF-α, IL-6, and CXCL-10 expression. Enhanced macrophage M2 polarization, evidenced by reduced iNOS and increased Arg1 and Mrc1 mRNA levels, was further detected after Pro treatment both in the kidney, after rI/R in vivo, and in H/R-treated PMs. Pro administration also repressed phosphorylated signal transducer and activator of transcription 1 (p-STAT1) and increased p-STAT3, p-STAT6, and peroxisome proliferator-activated receptor-γ (PPARγ) mRNA levels in H/R-exposed PMs. Importantly, siRNA-mediated PPARγ silencing repressed Pro-mediated STAT3 activation in PMs and restored proinflammatory cytokine levels and prevented macrophage M2 marker expression in both rI/R-treated rats and cultured PMs. These findings suggest that Pro confers renoprotection against rI/R by stimulating PPARγ/STAT3-dependent macrophage conversion to the M2 phenotype.