Apoptosis and inflammation in renal reperfusion injury

Risk factors of delayed graft function following living donor kidney transplantation: A meta-analysis

INTRODUCTION

Delayed graft function (DGF) is a common condition that necessitates dialysis during the first week after transplantation. Although DGF rarely occurs following living-donor kidney transplantation (LDKT), it may eventually lead to acute or chronic graft rejection. This study aimed to assess the risk factors for DGF in patients who underwent LDKT.

METHODS

A systematic review and meta-analysis of studies published before August 2022 was conducted using the PubMed, Science Direct, Cochrane, and Directory of Open Access Journal (DOAJ) databases. The review included studies that assessed the incidence of DGF following LDKT, and examined its risk factors, while excluding studies involving deceased donors. Potential risk factors were analyzed using pooled mean differences or odds ratios with 95% confidence intervals (CIs). Review Manager 5.3 was used for the meta-analysis.

RESULTS

Among the 13 included studies, 3685 cases of DGF were identified in a total of 113,261 patients (3.25%). Potential risk factors for DGF following LDKT were examined across several aspects, including donor, recipient, donor/recipient relationship, and immunological and intraoperative factors. The identified risk factors included older donors (P = 0.07), male recipients (P < 0.0001), higher recipient body mass index (BMI) (P < 0.0001), non-white recipients (P < 0.0001), pre-existing diabetes (P < 0.0001), pre-existing hypertension (P = 0.01), history of dialysis (P < 0.0001), re-transplantation (P = 0.004), unrelated donor/recipient (P = 0.02), ABO incompatibility (P < 0.0001), higher panel reactive antibody (PRA) levels (P < 0.0001), utilization of right kidney (P < 0.0001), and longer cold ischemia time (CIT) (P = 0.004).

CONCLUSION

Several factors related to the donor, recipient, donor/recipient relationship, and immunological and intraoperative aspects were identified as potential risk factors for the development of DGF following LDKT. Addressing and optimizing these factors may improve the long-term outcomes of LDKT.

Kidney Injury in a Murine Hemorrhagic Shock/Resuscitation Model Is Alleviated by sulforaphane's Anti-Inflammatory and Antioxidant Action

Hemorrhagic shock/resuscitation (HS/R) can lead to acute kidney injury, mainly manifested as oxidative stress and inflammatory injury in the renal tubular epithelial cells, as well as abnormal autophagy and apoptosis. Sulforaphane (SFN), an agonist of the nuclear factor-erythroid factor 2-related factor 2 (Nrf2) signaling pathway, is involved in multiple biological activities, such as anti-inflammatory, antioxidant, autophagy, and apoptosis regulation. This study investigated the effect of SFN on acute kidney injury after HS/R in mice. Hemorrhagic shock was induced in mice by controlling the arterial blood pressure at a range of 35-45 mmHg for 90 min within arterial blood withdrawal. Fluid resuscitation was carried out by reintroducing withdrawn blood and 0.9% NaCl. We found that SFN suppressed the elevation of urea nitrogen and serum creatinine levels in the blood induced by HS/R. SFN mitigated pathological alterations including swollen renal tubules and renal casts in kidney tissue of HS/R mice. Inflammation levels and oxidative stress were significantly downregulated in mouse kidney tissue after SFN administration. In addition, the kidney tissue of HS/R mice showed high levels of autophagosomes as observed by electron microscopy. However, SFN can further enhance the formation of autophagosomes in the HS/R + SFN group. SFN also increased autophagy-related proteins Beclin1 expression and suppressed P62 expression, while increasing the ratio of microtubule-associated protein 1 light chain 3 (LC3)-II and LC3-I (LC3-II/LC3-I). SFN also effectively decreased cleaved caspase-3 level and enhanced the ratio of anti-apoptotic protein B cell lymphoma 2 and Bcl2-associated X protein (Bcl2/Bax). Collectively, SFN effectively inhibited inflammation and oxidative stress, enhanced autophagy, thereby reducing HS/R-induced kidney injury and apoptosis levels in mouse kidneys.

Cell death induced by acute renal injury: a perspective on the contributions of accidental and programmed cell death

The involvement of cell death in acute kidney injury (AKI) is linked to multiple factors including energy depletion, electrolyte imbalance, reactive oxygen species, inflammation, mitochondrial dysfunction, and activation of several cell death pathway components. Since our review in 2003, discussing the relative contributions of apoptosis and necrosis, several other forms of cell death have been identified and are shown to contribute to AKI. Currently, these various forms of cell death can be fundamentally divided into accidental cell death and regulated or programmed cell death based on functional aspects. Several death initiator and effector molecules switch molecules that may act as signaling components triggering either death or protective mechanisms or alternate cell death pathways have been identified as part of the machinery. Intriguingly, several of these cell death pathways share components and signaling pathways suggesting complementary or compensatory functions. Thus, defining the cross talk between distinct cell death pathways and identifying the unique molecular effectors for each type of cell death may be required to develop novel strategies to prevent cell death. Furthermore, depending on the multiple forms of cell death simultaneously induced in different AKI settings, strategies for combination therapies that block multiple cell death pathways need to be developed to completely prevent injury, cell death, and renal function. This review highlights the various cell death pathways, cross talk, and interactions between different cell death modalities in AKI.

Downregulation of IL-1β/p38 mitogen activated protein kinase pathway by diacerein protects against kidney ischemia/reperfusion injury in rats

Renal ischemia-reperfusion (I/R) can be precipitated by multiple clinical situations that lead to impaired renal function and associated mortality. The resulting tubular cell damage is the outcome of complex disorders including, an inflammatory process with an overproduction of cytokines. Here, diacerein (DIA), an inhibitor of proinflammatory cytokine interleukin-1 beta (IL-1β), was investigated against renal I/R in rats. DIA was orally administrated (50 mg/kg/day) for ten days before bilateral ischemia for 45 min with subsequent 2 hr. reperfusion. Interestingly, DIA alleviated the renal dysfunction and histopathological damage in the renal tissues. Pretreatment with DIA corrected the oxidative imbalance by prevented reduction in antioxidant levels of GSH and SOD, while it decreased the elevation of the oxidative marker, MDA. In addition, DIA downregulated IL-1β and TNF-α expression in the renal tissues. Consequent to inhibition of the oxidative stress and inflammatory cascades, DIA inhibited the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK). Therefore, downstream targets for p38 MAPK were also inhibited via DIA which prevented further increases of inflammatory cytokines and the apoptotic marker, caspase-3. Collectively, this study revealed the renoprotective role of DIA for renal I/R and highlighted the role of p38 MAPK encountered in its therapeutic application in renal disease.

Protective effect of small extracellular vesicles (EVs) derived from ACE2-modified human umbilical cord mesenchymal stem cells against renal ischemia-reperfusion injury

AIM

Acute kidney injury is a severe disease that is closely associated with substantial morbidity and mortality. The most common cause of AKI is renal ischemia-reperfusion injury. Mesenchymal stem cells (MSCs) have previously been shown to have renoprotective effects. However, extracellular vesicles secreted by MSCs are thought to be the key for the therapeutic effects of MSCs. This study investigated whether small EVs derived from ACE2-modified human umbilical cord MSCs could alleviate RIRI and explored their underlying molecular mechanisms METHODS: A lentivirus carrying an ACE2 overexpression vector was constructed and used to infect MSCs. The small EVs were isolated from MSC-conditioned medium by ultracentrifugation. HK-2 cells were cocultured with MSC-ACE2-EVs and subjected to hypoxia/reoxygenation injury. MSCs-ACE2-EVs were injected into RIRI mice. Biochemical and morphological characteristics were assessed, and the levels of inflammatory-related factors, oxidative stress products, and apoptosis in HK-2 cells and kidney tissues were assessed RESULTS: In vitro, MSC-ACE2-EVs had stronger anti-inflammatory, antioxidative stress, and antiapoptotic effects in HK-2 cells subjected to H/R than MSC-NC-EVs. In vivo, MSC-ACE2-EVs could target the injured kidney, reduce blood creatinine and urea nitrogen levels, and protect the kidney from I/R, and this effect may have been related to the activation of the Nrf2/HO-1 signalling pathway CONCLUSION: Taken together, our results demonstrated the anti-inflammatory, antioxidative stress, and antiapoptotic effects of MSC-ACE2-EVs, which protected against I/R injury in vitro and vivo. MSC-ACE2-EVs may be therapeutic agents for RIRI.

Reducing ischemic kidney injury through application of a synchronization modulation electric field to maintain Na+/K+-ATPase functions

Renal ischemia-reperfusion injury is an important contributor to the development of delayed graft function after transplantation, which is associated with higher rejection rates and poorer long-term outcomes. One of the earliest impairments during ischemia is Na⁺/K⁺-ATPase (Na/K pump) dysfunction due to insufficient ATP supply, resulting in subsequent cellular damage. Therefore, strategies that preserve ATP or maintain Na/K pump function may limit the extent of renal injury during ischemia-reperfusion. Here, we applied a synchronization modulation electric field to activate Na/K pumps, thereby maintaining cellular functions under ATP-insufficient conditions. We tested the effectiveness of this technique in two models of ischemic renal injury: an in situ renal ischemia-reperfusion injury model (predominantly warm ischemia) and a kidney transplantation model (predominantly cold ischemia). Application of the synchronization modulation electric field to a renal ischemia-reperfusion injury mouse model preserved Na/K pump activity, thereby reducing kidney injury, as reflected by 40% lower plasma creatinine (1.17 ± 0.03 mg/dl) in the electric field-treated group as compared to the untreated control group (1.89 ± 0.06 mg/dl). In a mouse kidney transplantation model, renal graft function was improved by more than 50% with the application of the synchronization modulation electric field according to glomerular filtration rate measurements (85.40 ± 12.18 μl/min in the untreated group versus 142.80 ± 11.65 μl/min in the electric field-treated group). This technique for preserving Na/K pump function may have therapeutic potential not only for ischemic kidney injury but also for other diseases associated with Na/K pump dysfunction due to inadequate ATP supply.

circ-AKT3 aggravates renal ischaemia-reperfusion injury via regulating miR-144-5p /Wnt/β-catenin pathway and oxidative stress

Renal ischaemia-reperfusion (RI/R) injury is one major pathological state of acute kidney injury (AKI) with a mortality rate ranking 50% to 80%. MiR-144-5p acts as a molecular trigger in various diseases. We presumed that miR-144-5p might be involved RI/R injury progression. We found that RI/R injury decreased miR-144-5p expression in rat models. MiR-144-5p downregulation promoted cell apoptosis rate and activated Wnt/β-catenin signal in RI/R injury rats. By performing bioinformatic analysis, RIP, RNA pull-down, luciferase reporter experiments, we found that circ-AKT3 sponged to miR-144-5p and decreased its expression in RI/R injury rats. Moreover, we found that circ-AKT3 promoted cell apoptosis rate and activated Wnt/β-catenin signal, and miR-144-5p mimic reversed the promotive effect of circ-AKT3 in rat models. We also found that circ-AKT3 increased the oxidative stress level in rat models. In conclusion, our study suggests that the circAKT3 is involved RI/R injury progression through regulating miR-144-5p/Wnt/β-catenin pathway and oxidative stress.

Gastrodin Pretreatment Alleviates Renal Ischemia-Reperfusion Injury

INTRODUCTION

This study aimed to investigate the possible effect of gastrodin in renal ischemia-reperfusion injury (IRI) and the mechanisms.

METHODS

Forty-eight male Sprague Dawley rats were randomly divided into 3 groups: sham-operated group, saline-treated IRI group, and gastrodin-treated IRI group. Gastrodin or 0.9% saline (300 mg/kg/day) was intragastrically administrated for 8 days before operation. We analyzed renal function and histological change. The malondialdehyde level, antioxidant enzymes' activities, and markers of inflammation and apoptosis were measured. Statistical analysis was performed using 1-way analysis of variance (ANOVA) or Kruskal-Wallis ANOVA on ranks.

RESULTS

Gastrodin pretreatment improved IRI-induced renal dysfunction and histologic injury. Mechanistically, gastrodin reversed the elevation of malondialdehyde level and the reduction of antioxidant enzymes' activities. Gastrodin also reduced the elevated myeloperoxidase activity, TNF-α and IL-1β levels, and the activation of p38 MAPK. Moreover, gastrodin-treated rats exhibited a dramatic reduction in renal tubular apoptosis, along with a decrease in caspase-3 activation and an increase in the Bcl-2/Bax ratio.

CONCLUSION

Gastrodin pretreatment may alleviate renal IRI via the amelioration of oxidative injury, inflammatory response, and renal tubular apoptosis.

Evaluation of the protective effects of gossypin for ischemia/reperfusion injury in ovary tissue

AIM

Ovarian ischemia-reperfusion (I/R) injury is a serious gynecological condition that affects women of reproductive age and reduces ovarian reserve. Management of I/R injury with detorsion causes reperfusion damage, in which oxidative stress plays a central role. This study aimed to investigate whether the gossypin (GOS) with antioxidant properties, a flavonoid, has beneficial effects on the biochemical, molecular, and histopathological aspects of ovarian I/R injury.

METHODS

Thirty-three female Balb/c mice were randomly divided into five groups as follows: Healthy (Sham-operated control group), I/R (IR group), I/R + GOS 5 (I/R with GOS 5 mg/kg), I/R + GOS 10 (I/R with GOS 10 mg/kg), and I/R + GOS 20 (I/R with GOS 20 mg/kg). This was followed by 3 h of ischemia and subsequent reperfusion for 3 h after detorsion was exposed. GOS was injected 2 h before reperfusion.

RESULTS

IL-1β, IL-6, TNF-α, NF-κB, and CASP-3 mRNA expressions, SOD (superoxide dismutase) activity, GSH (glutathione), and MDA (malondialdehyde) levels, and histopathological changes were evaluated in ovarian tissue. Histological examination indicated that treatment of ovarian I/R injury with GOS led to the improvement of ovarian tissue, which was accompanied by an increase in SOD activity and GSH level and a decrease in MDA level, NF-κB, TNF-α, IL-1β, and IL-6 expressions. GOS was also corrected by reducing the elevated expression of CASP-3 as apoptosis-change marker.

CONCLUSION

These findings indicate that the treatment of GOS may be useful as a conservative approach to reverse I/R injury via amelioration of oxidative stress parameters and histopathological scores, attenuation of inflammation, and the suppression of apoptosis.

Investigation of the effect of isolated mitochondria transplantation on renal ischemia-reperfusion injury in rats

Ischemia/Reperfusion (I/R) injury is clinically important in many surgical practice including kidney transplantation. It is known that mitochondria have a key role in the intracellular and extracellular signaling pathways of ischemia and reperfusion injury. In this respect, we pointed to explore the probable effects of isolated mitochondria transplantation from MSCs (mesenchymal stem cells), to alleviate ischemia/reperfusion-induced renal injury. Experiments were held on the 48 male Sprague Dawley rats. Groups were divided as Control (C1), I/R-Control (C2), Vehicle-1 (V1), Vehicle-2 (V2), Transplantation-1 (T1) and Transplantation-2 (T2) group. Unilaterally nephrectomy was performed in all groups. In the groups except the control, the left kidneys ischemized for 45 min and then reperfusion was carried out. According to the study groups, isolated mitochondria or vehicle infused into the renal cortex and rats were monitored for 48 h. Following that mentioned procedure, animals were sacrificed and biological samples were taken for physiological, histological and biochemical examinations. The results of present study show that mitochondrial transplantation promoted proliferation and regeneration of tubular cells after renal injury. Moreover, mitochondrial transplantation reduced mitochondrial dynamics-DRP-1 fission protein of tubular cells and reversed renal deficits. Mitochondrial transplantation diminished apoptotic markers including TUNEL and Caspase-3 levels in injured renal cells. Our results provide a direct link between mitochondria dysfunction and ischemia/reperfusion-induced renal injury and suggest a therapeutic effect of transplanting isolated mitochondria obtained from MSCs against renal injury.

Renoprotective effects of prazosin on ischemia-reperfusion injury in rats

BACKGROUND

Renal ischemia-reperfusion (IR) injury is one of the main leading causes of acute kidney injury associated with inflammation, oxidative stress and cell apoptosis. We studied the effects of prazosin, as a specific blocker of α1-AR, on renal IR injury.

METHODS

Rats were divided into normal control; untreated IR and prazosin-treated IR (1 mg/kg body weight). Prazosin was administered by intraperitoneal injection 30 min prior to IR induction. The level of urea/creatinine and oxidative factors were detected by colorimetric methods. Apoptosis-associated factors, inflammatory, and signaling proteins were analyzed in renal tissue. The abnormalities of renal histopathology were detected by immunohistochemistry.

RESULTS

Administration of prazosin to IR rats ameliorated serum urea and creatinine and IR-induced histopathological damages. Lipid peroxidation was significantly improved after treatment by prazosin in IR injury rats, however, antioxidant status was not affected. Rats subjected to IR injury activated Bax protein and NF-κB mediated inflammatory response. Moreover, treatment with prazosin inhibited renal NF-κB activation, resulting in a significant decline in pro-inflammatory cytokine of IL-6.

CONCLUSION

These findings suggest that prazosin could be a good candidate to attenuate renal IR injury due to its ability to modulate renal function, apoptosis and inflammation.

Comparative study of gavage and intraperitoneal administration of gamma-oryzanol in alleviation/attenuation in a rat animal model of renal ischemia/reperfusion-induced injury

OBJECTIVES

Ischemia/reperfusion (I/R) is the leading cause of acute kidney injury. This study aimed to elucidate the reno-protective effect of gamma-oryzanol (GO) by comparing gavage and intraperitoneal (IP) administration methods on renal I/R injury in a rat model.

MATERIALS AND METHODS

Rats were divided into four groups including (group 1) sham, (group 2) I/R-control, (group 3) I/R+GO gavage-treated, and (group 4) I/R+ GO IP-treated. A single dose of GO was administrated to groups 3 and 4 (100 mg/kg body weight), 60 min before induction of I/R. After anesthesia, I/R was created by 45 min of ischemia, followed by 6 hr of reperfusion. Then, blood and tissue samples were subjected to evaluation of renal function, anti-oxidant capacity, inflammation, apoptotic proteins, and IKB/NF-kB pathway.

RESULTS

The two GO administration methods showed improvement of renal function along with attenuation of histological abnormalities. An increase in antioxidant capacity along with a decrease in pro-inflammatory markers, decline in the expression levels of BAX, Bax/Bcl-2, and caspase-3, and up-regulation of Bcl-2 expression were recorded. Moreover, a significant decrease in NF-Kb, p-IKBα, and MMP-2/9 with an increase in IKBα levels were also observed. Overall, in a comparative evaluation between the two gavage and IP administration methods, we did not find any differences in all examined parameters, except IL-6 which had a better result via gavage.

CONCLUSION

A single dose of GO administration has a reno-protective effect against renal I/R injury. Gavage and IP administration exhibit similar efficiency in alleviation of I/R injury.

Autophagy Dynamics and Modulation in a Rat Model of Renal Ischemia-Reperfusion Injury

Renal ischemia-reperfusion (IR) injury leading to cell death is a major cause of acute kidney injury, contributing to morbidity and mortality. Autophagy counteracts cell death by removing damaged macromolecules and organelles, making it an interesting anchor point for treatment strategies. However, autophagy is also suggested to enhance cell death when the ischemic burden is too strong. To investigate whether the role of autophagy depends on the severity of ischemic stress, we analyzed the dynamics of autophagy and apoptosis in an IR rat model with mild (45 min) or severe (60 min) renal ischemia. Following mild IR, renal injury was associated with reduced autophagy, enhanced mammalian target of rapamycin (mTOR) activity, and apoptosis. Severe IR, on the other hand, was associated with a higher autophagic activity, independent of mTOR, and without affecting apoptosis. Autophagy stimulation by trehalose injected 24 and 48 h prior to onset of severe ischemia did not reduce renal injury markers nor function, but reduced apoptosis and restored tubular dilation 7 days post reperfusion. This suggests that trehalose-dependent autophagy stimulation enhances tissue repair following an IR injury. Our data show that autophagy dynamics are strongly dependent on the severity of IR and that trehalose shows the potential to trigger autophagy-dependent repair processes following renal IR injury.

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

Background

Renal ischemic postconditioning (RIPo) can protect the kidney from renal ischemia/reperfusion injury (RIRI). However, the underlying molecular mechanisms for RIPo in renal protection remained elusive. This study aimed to investigate the renoprotective effects of RIPo in an RIR rat model.

Method

The Sprague Dawley (SD) rats were randomly divided into three groups respectively: sham group, the RIRI group and the RIPo group. The levels of proteinuria, blood urea nitrogen (BUN), creatinine (Cr), malondialdehyde (MDA), superoxide dismutase (SOD), lactate dehydrogenase (LDH), reactive oxidative species (ROS), interleukins (IL)-6, IL-1β, and IL-18 were measured by ELISA. Apoptotic cells and caspase-3 positive cells were detected by TUNEL assay and immunohistochemistry, respectively. The protein expressive levels of caspase-3, caspase-9, ATG8, Beclin1, p62, LC3-II, P-P13K, P-AKT and P-mTOR were detected by western blot.

Results

Our results showed that pretreatment with RIPo significantly reduced ischemic pathological and morphological changes. The levels of proteinuria, BUN, and Cr were also significantly reduced by RIPo pretreatment. Besides, ATG8, LC3-II and Beclin-1 were upregulated in the RIPo group, but p62 was downregulated. Moreover, RIPo pretreatment resulted in higher levels of phosphorylated PI3K, Akt, and mTOR. These results showed that RIPo protects the kidneys of rats from IRI with suppressed apoptosis and activated autophagy. Mechanically, the activated PI3K/AKT/mTOR signaling pathway were activated.

Conclusions

Collectively, our data demonstrated that RIPo could suppress Inflammatory response, oxidative stress, apoptosis and induce autophagy as well as activate the PI3K/AKT/mTOR pathway, which may play an important role in renal protection against RIRI.

Organ-Protective Effects and the Underlying Mechanism of Dexmedetomidine

Dexmedetomidine (DEX) is a highly selective α2 adrenergic receptor (α2AR) agonist currently used in clinical settings. Because DEX has dose-dependent advantages of sedation, analgesia, antianxiety, inhibition of sympathetic nervous system activity, cardiovascular stabilization, and significant reduction of postoperative delirium and agitation, but does not produce respiratory depression and agitation, it is widely used in clinical anesthesia and ICU departments. In recent years, much clinical study and basic research has confirmed that DEX has a protective effect on a variety of organs, including the nervous system, heart, lungs, kidneys, liver, and small intestine. It acts by reducing the inflammatory response in these organs, activating antiapoptotic signaling pathways which protect cells from damage. Therefore, based on wide clinical application and safety, DEX may become a promising clinical multiorgan protection drug in the future. In this article, we review the physiological effects related to organ protection in α2AR agonists along with the organ-protective effects and mechanisms of DEX to understand their combined application value.

Protective effect of dapsone against renal ischemia-reperfusion injury in rat

Background: Ischemia/reperfusion can cause injury to tissues and compromise functionality of organs due to inflammatory processes. Significantly, development of these effects in kidney tissue has been a challenging issue that leads to acute renal injury. In this study, anti-inflammatory, anti-oxidative, and protective features of dapsone on kidney ischemia/reperfusion injury were investigated.Material and methods: Renal ischemia was induced in rats by bilateral renal arteries clamping for 45 min followed by 24 h reperfusion phase. The effects of different doses of dapsone (1, 3, 10 mg/kg) on ischemia/reperfusion injury in kidney tissue were investigated by targeting BUN, Creatinine, LDH, MDA, MPO, IL-1β, TNF-α, and NFκB. In addition histopathological examination was performed by H&E staining method.Results and discussion: Comparing the findings of this study showed significant reduction in BUN and LDH in 10 mg/kg dapsone received groups, and Cr, MDA, and MPO in 3 mg/kg dapsone received groups. The serum level of TNF-α was significantly decreased with both doses of 3 and 10 mg/kg dapsone. The same results were observed in the serum level of IL-1β and NFκB. Besides, remarkable improvement in histological damages was also observed with dapsone treatment.Conclusion: These results support the hypothesis that the positive effects of dapsone on the renal ischemia/reperfusion injury are mediated by modulating inflammatory cascades.

Dexmedetomidine Preconditioning Protects Rats from Renal Ischemia-Reperfusion Injury Accompanied with Biphasic Changes of Nuclear Factor-Kappa B Signaling

Acute kidney injury (AKI) is one of the most common and troublesome perioperative complications. Dexmedetomidine (DEX) is a potent α2-adrenoceptor (α2-AR) agonist with anti-inflammatory and renoprotective effects. In this study, a rat renal ischemia–reperfusion injury (IRI) model was induced. At 24 h after reperfusion, the IRI-induced damage and the renoprotection of DEX preconditioning were confirmed both biochemically and histologically. Changes in nuclear factor-kappa B (NF-κB), as well as its downstream anti-inflammatory factor A20 and proinflammatory factor tumor necrosis factor-α (TNF-α), were detected. Atipamezole, a nonselective antagonist, was then added 5 min before the administration of DEX to further analyze DEX's effects on NF-κB, and another anti-inflammatory medicine, methylprednisolone, was used in comparison with DEX, to further analyze DEX's effects on NF-κB. Different concentrations of DEX (0 nM, 0.1 nM, 1 nM, 10 nM, 100 nM, 1 μM, and 10 μM) were applied to preincubated human renal tubular epithelial cell line (HK-2) cells in vitro. After anoxia and reoxygenation, the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium assay and enzyme-linked immunosorbent assay (ELISA) were performed to evaluate the levels of NF-κB downstream anti-inflammatory cytokines. The results showed that, unlike methylprednisolone, DEX preconditioning led to a time-dependent biphasic change (first activation then inhibition) of NF-κB in the rat renal IRI models that were given 25 μg/kg i.p. It was accompanied by a similarly biphasic change of TNF-α and an early and persistent upregulation of A20. In vitro, DEX's cellular protection showed a concentration-dependent biphasic change which was protective within the range of 0 to 100 nM but became opposite when concentrations are greater than 1 μM. The changes in the A20 and NF-κB messenger RNA (mRNA) levels were consistent with the renoprotective ability of DEX. In other words, DEX preconditioning protected the rats from renal IRI via regulation biphasic change of NF-κB signaling.

P2X4 receptor exacerbates ischemic AKI and induces renal proximal tubular NLRP3 inflammasome signaling

We tested the hypothesis that the P2X4 purinergic receptor (P2X4) exacerbates ischemic acute kidney injury (AKI) by promoting renal tubular inflammation after ischemia and reperfusion (IR). Supporting this, P2X4-deficient (KO) mice were protected against ischemic AKI with significantly attenuated renal tubular necrosis, inflammation, and apoptosis when compared to P2X4 wild-type (WT) mice subjected to renal IR. Furthermore, WT mice treated with P2X4 allosteric agonist ivermectin had exacerbated renal IR injury whereas P2X4 WT mice treated with a selective P2X4 antagonist (5-BDBD) were protected against ischemic AKI. Mechanistically, induction of kidney NLRP3 inflammasome signaling after renal IR was significantly attenuated in P2X4 KO mice. A P2 agonist ATPγS increased NLRP3 inflammasome signaling (NLRP3 and caspase 1 induction and IL-1β processing) in isolated renal proximal tubule cells from WT mice whereas these increases were absent in renal proximal tubules isolated from P2X4 KO mice. Moreover, 5-BDBD attenuated ATPγS induced NLRP3 inflammasome induction in renal proximal tubules from WT mice. Finally, P2X4 agonist ivermectin induced NLRP3 inflammasome and pro-inflammatory cytokines in cultured human proximal tubule cells. Taken together, our studies suggest that renal proximal tubular P2X4 activation exacerbates ischemic AKI and promotes NLRP3 inflammasome signaling.

Isoquercitrin Attenuates Renal Ischemia/Reperfusion Injury Through Antioxidation, Anti-inflammation, and Antiapoptosis in Mice

Renal ischemia-reperfusion injury (RIRI) occurs after several surgical procedures such as kidney transplantation and partial nephrectomy. Isoquercitrin (IQ) exhibited protective effects in cerebral ischemia-reperfusion injury. In the present study, we aimed to evaluate the effects of IQ on the prevention of RIRI. The mouse model of RIRI was induced by 30-minute clamping of the left renal pedicle after excising of the right kidney, followed by 24-hour reperfusion. Thirty mice were randomly divided into the following 3 groups: sham operation, RIRI model group, and IQ pretreatment + RIRI. Serum creatinine and blood urea nitrogen (BUN) were used for evaluating renal function. Kidney cell apoptosis was measured by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. Moreover, the pro-inflammatory cytokines (TNF-α, IL-6), the oxidative stress associated factors (malondialdehyde, superoxide dismutase), and the apoptotic factors (Bcl-2, Bax) were assessed. After RIRI, BUN, creatinine, TNF-α, IL-6, malondialdehyde, and Bax were significantly increased, and levels of superoxide dismutase and Bcl-2/Bax ratio and Bcl-2 expression were decreased markedly. As expect, IQ reversed these changes. These data indicate that IQ plays a protective role during RIRI, which may be partially mediated through the actions of antioxidation, anti-inflammation, and antiapoptosis.

LncRNA np_5318 promotes renal ischemia-reperfusion injury through the TGF-β/Smad signaling pathway

Long noncoding (Lnc)RNA np_5318 has been proved to be involved in renal injury, while its functionality in renal ischemia-reperfusion (I/R) injury is unknown. Therefore, the present study aimed to investigate the role of lncRNA np_5318 in the development of renal I/R injury. Renal I/R injury model and I/R cell model were established in vitro. The expression of np_5318 in I/R cell was inhibited by small interfering (si)-np_5318 and increased by pc-np_5318. Renal function was detected and evaluated by automatic biochemical tests. Immunohistochemical staining was performed to detect the expression cluster of differentiation (CD)31, transforming growth factor (TGF)-β1 and (mothers against decapentaplegic homolog 3) Smad3 in renal tissue. The interaction between np_5318 and Smad3 was verified by chromatin immunoprecipitation (ChIP). Western blotting was performed to detect the expression levels of TGF-β1, Smad3 and phosphorylated (p)-Smad3 in renal tissue and renal cells. Expression of np_5318 in renal tissue and renal cells was detected by reverse transcription-quantitative PCR. Relative cell viability was confirmed by MTT assay. Renal function was impaired and pathological changes in renal tissue were observed in the renal I/R injury group, indicating the renal I/R injury model was successfully established. Compared with the sham group, the expression level of np_5318 significantly increased in the renal I/R injury group. ChIP data confirmed the interaction between np_5318 and Smad3. The expression of TGF-β1, Smad3 and p-Smad3 in renal tissue was also significantly increased in the renal I/R injury group. Furthermore, the I/R cell model in vitro was successfully constructed and np_5318 in I/R group was significantly increased compared with the control group. Cell growth was significantly suppressed in the I/R group compared with the control group. Additionally, transfection with pc-np_5318 significantly inhibited cell growth of I/R cells at 48 and 72 h. While inhibition of np_5318 by si-np_5318 significantly increased the cell growth of I/R cells at 48 and 72 h. Moreover, the level of TGF-β1, p-Smad3 and Smad3 was significantly increased in the I/R group compared with the control group, and transfection with pc-np_5318 significantly increased the level of TGF-β1, p-Smad3 and Smad3. While inhibition of np_5318 by si-np_5318 significantly suppressed the level of TGF-β1, p-Smad3 and Smad3.

LncRNA np_5318 may participate in the development of renal I/R injury through TGF-β/Smad signaling pathway.

Anti-inflammatory Property of AMP-activated Protein Kinase

BACKGROUND

One of the many debated topics in inflammation research is whether this scenario is really an accelerated form of human wound healing and immunityboosting or a push towards autoimmune diseases. The answer requires a better understanding of the normal inflammatory process, including the molecular pathology underlying the possible outcomes. Exciting recent investigations regarding severe human inflammatory disorders and autoimmune conditions have implicated molecular changes that are also linked to normal immunity, such as triggering factors, switching on and off, the influence of other diseases and faulty stem cell homeostasis, in disease progression and development.

METHODS

We gathered around and collected recent online researches on immunity, inflammation, inflammatory disorders and AMPK. We basically searched PubMed, Scopus and Google Scholar to assemble the studies which were published since 2010.

RESULTS

Our findings suggested that inflammation and related disorders are on the verge and interfere in the treatment of other diseases. AMPK serves as a key component that prevents various kinds of inflammatory signaling. In addition, our table and hypothetical figures may open a new door in inflammation research, which could be a greater therapeutic target for controlling diabetes, obesity, insulin resistance and preventing autoimmune diseases.

CONCLUSION

The relationship between immunity and inflammation becomes easily apparent. Yet, the essence of inflammation turns out to be so startling that the theory may not be instantly established and many possible arguments are raised for its clearance. However, this study might be able to reveal some possible approaches where AMPK can reduce or prevent inflammatory disorders.

An investigation of the effects of metformin on ovarian ischemia-reperfusion injury in rats

Damage to the ovaries or tissue torsion can significantly reduce the ovarian reserve and thus cause severe gynecological and hormonal deficiencies. The discovery of new agents is always needed in the treatment of this condition. Metformin (MET) has been shown to be beneficial in attenuating ovarian ischemia-reperfusion injury. Fifty-six female Sprague Dawley rats were divided into seven groups. Group 1 represented the control group (C), Group 2, the ischemia group (I), and Group 3, the ischemia/reperfusion group (I/R). Group 4, the ischemia (I)+250 group, and Group 5, the ischemia (I)+500 group, received 250 mg/kg and 500 mg/kg MET, respectively. Group 6, the ischemia/reperfusion (I/R)+250 group, and Group 7, the ischemia/reperfusion (I/R)+500 group, received 250 mg/kg and 500 mg/kg MET, respectively. Tissue malondialdehyde (MDA), glutathione (GSH), and tumor necrosis factor-alpha (TNF-α) levels in ovarian tissue increased following I/R, while estradiol (E₂) levels decreased. Moreover, infiltration and diffuse edematous areas were observed in addition to diffuse vascular congestion and hemorrhage findings. Caspase-3 and nuclear factor kappa B (NF-κβ) expression levels also increased. MDA and TNF-α concentrations decreased in the MET treatment groups, while GSH and E₂ levels increased. The findings showed that I/R causes ovarian damage through the induction of oxidative stress, inflammation, and apoptosis. However, MET application was effective in preventing damage in ovarian tissue by reducing levels of reactive oxygen species, proinflammatory cytokines, caspase-3 and NF-κβ.

Comparison of Intermittent Versus Continuous Ischemia During Laparoscopic Partial Nephrectomy in a Porcine Model

Renal ischemic time is one of the most variable risk factors in partial nephrectomy (PN). Our purpose was to investigate if intermittent ischemia could decrease renal impairment in the process of PN in porcine model and explore the feasibility of this surgical procedure in nephrectomy. A kidney ischemia-reperfusion injury model was successfully established in six pigs under laparoscopic surgery. One kidney of each pig was continuously ischemic, and intermittent ischemia was administered to the kidney of another side. Laparoscopic renal artery occlusion was applied to each kidney for 120 minutes. Intermittent ischemia was 15/3 minutes of cycles (ischemia for 15 minutes and reperfusion for 3 minutes). Microdialysis technique, immunohistochemistry, and histopathology were used to evaluate the extent of renal function injures. The concentration of glycerol in intermittently ischemic group was significantly lower than that in continuously ischemic group (F = 19.06, p = 0.001). NGAL and BCL-2 immunostaining of the renal tubular epithelial cell in the intermittent ischemia kidneys was significantly reduced compared with that in the continuously ischemic kidneys (F = 5.51, p = 0.041; F = 13.53, p = 0.004). Our study has shown that intermittent ischemia is a possibly effective and practicable surgical process for reducing renal ischemic damage in porcine model nephrectomy.

The renoprotective effects of naringin and trimetazidine on renal ischemia/reperfusion injury in rats through inhibition of apoptosis and downregulation of micoRNA-10a

Renal Ischemia-Reperfusion (IR) injury occurs due to circulatory shock and renal transplantation, leading to mortality and morbidity worldwide. The primary purpose of the current study was to evaluate the renoprotective effects of the naringin (NAR) and trimetazidine (TMZ) on IR injury, renal hemodynamics, antioxidant capacity, microRNA-10a, and expression of apoptosis factors. Forty rats were divided into five groups randomly: Sham, IR injury, (TMZ, 5 mg/kg), (NAR pretreatment, 100 mg/kg), and TMZ plus NAR. The sham group underwent the identical surgical procedure as the other groups, except for the application of clamps. After anesthesia, IR injury was induced by 45 min of ischemia, followed by reperfusion for 4 h. Tissue and blood samples were collected for evaluation of renal function, antioxidant activity and, biochemical and molecular parameters. Administration of the NAR, TMZ, and their combination decreased the plasma level of microRNA-10a, caspase-3, and Bcl-2 associated x protein (Bax) mRNA expression, but increased the B- cell lymphoma 2 (Bcl-2) mRNA expression in the kidney tissue. In addition, antioxidant activity, renal blood flow, creatinine clearance (C_Cr), and fractional excretion of sodium (FE_Na) were improved. The NAR, TMZ, and their combination can prevent renal I/R injury through promotion of the level of antioxidant enzymes, as well as decrease of microRNA-10a and anti-apoptosis properties. Our data also suggest that NAR, TMZ, or their combination might be beneficial as potent therapeutic factors against renal IR injury.

SCUBE1-enhanced bone morphogenetic protein signaling protects against renal ischemia-reperfusion injury

We previously reported that the membrane-bound SCUBE1 (signal peptide-CUB-epithelial growth factor domain-containing protein 1) forms a complex with bone morphogenetic protein 2 (BMP2) ligand and its receptors, thus acting as a BMP co-receptor to augment BMP signal activity. However, whether SCUBE1 can bind to and facilitate signaling activity of BMP7, a renal protective molecule for ischemia-reperfusion (I/R) insult, and contribute to the proliferation and repair of renal tubular cells after I/R remains largely unknown. In this study, we first showed that I/R-induced SCUBE1 was expressed in proximal tubular cells, which coincided with the expression of renoprotective BMP7. Molecular and biochemical analyses revealed that SCUBE1 directly binds to BMP7 and its receptors, functioning as a BMP co-receptor to promote BMP7 signaling. Furthermore, we used a new Scube1 deletion (Δ2) mouse strain to further elucidate the renal pathophysiological function of SCUBE1 after I/R injury. As compared with wild-type littermates, Δ2 mice showed severe renal histopathologic features (extensive loss of brush border, tubular necrosis, and tubular dilation) and increased inflammation (neutrophil infiltrate and induction of monocyte chemoattractant protein-1, tumor necrosis factor-α and interleukin-6) during the resolution of I/R damage. They also showed reduced BMP signaling (phosphorylated Smad1/5/8) along with decreased proliferation and increased apoptosis of renal tubular cells. Importantly, lentivirus-mediated overexpression of SCUBE1 enhanced BMP signaling and conferred a concomitant survival outcome for Δ2 proximal tubular epithelial cells after hypoxia-reoxygenation treatment. The protective BMP7 signaling may be facilitated by stress-inducible SCUBE1 after renal I/R, which suggests potential targeted approaches for acute kidney injury.

Schisantherin A protects renal tubular epithelial cells from hypoxia/reoxygenation injury through the activation of PI3K/Akt signaling pathway

Schisantherin A (SchA), a dibenzocyclooctadiene lignan isolated from the fruit of Schisandra sphenanthera, was reported to possess anti-inflammatory and antioxidant activities. However, its protective effect against renal ischemia-reperfusion (I/R) injury in human renal tubular epithelial cells subjected to hypoxia/reoxygenation (H/R) has never been studied. Thus, herein, we investigated the effect of SchA on renal I/R injury in vitro. Our results demonstrated that SchA pretreatment significantly improved HK-2 cell viability exposed to H/R. Pretreatment with SchA markedly inhibited the levels of reactive oxygen species and malondialdehyde, as well as suppressed the production of tumor necrosis factor-α (TNF-α), interleukin-1β, and interleukin-6 in H/R-stimulated HK-2 cells. In addition, SchA also suppressed H/R-induced HK-2 cell apoptosis. Furthermore, this protective effect of SchA was mediated through the PI3K/Akt signaling pathway in HK-2 cells. These findings showed that SchA may exert a protective effect on renal tubular epithelial cells against H/R injury through the activation of PI3K/Akt signaling pathway.

Knockdown of NLRC5 attenuates renal I/R injury in vitro through the activation of PI3K/Akt signaling pathway

NLRC5, as the largest member of nucleotide-binding domain and leucine-rich repeat (NLR) family, was involved in various physiological processes, such as inflammation, fibrosis, innate immunity and diabetic nephropathy. However, the role of NLRC5 in acute kidney injury remains unclear. The aim of this study was to investigate the role of NLRC5 in human renal proximal tubular epithelial cells (HK-2) exposed to hypoxia/reoxygenation (H/R). Our results demonstrated that the expression of NLRC5 was significantly up-regulated in HK-2 cells exposed to H/R. Knockdown of NLRC5 significantly improved the viability of HK-2 cells exposed to H/R. In addition, knockdown of NLRC5 efficiently inhibited H/R-induced oxidative stress and apoptosis in HK-2 cells. Mechanistically, knockdown of NLRC5 markedly enhanced the activation of PIK3/Akt signaling pathway in H/R-stimulated HK-2 cells. In summary, our findings indicate that knockdown of NLRC5 attenuates renal I/R injury in vitro through the activation of PI3K/Akt signaling pathway.

STIM1 deficiency protects the liver from ischemia/reperfusion injury in mice

Hepatic ischemia reperfusion (I/R) injury is unavoidable in various clinical conditions. Despite considerable investigation, the underlying molecular mechanism revealing liver I/R injury remains elusive. Stromal interaction molecule 1 (STIM1) plays essential role in regulating the induction of cellular responses to a number of stress conditions, including temperature changes, elevated ROS, and hypoxia. Here, to explore if STIM1 is involved in hepatic injury, wild type (WT) and STIM1-knockout (STIM1^-/-) mice were subjected to I/R. Our results indicated that the WT mice with hepatic I/R injury showed higher STIM1 expressions from gene and protein levels in liver tissue samples. Similar results were observed in hypoxia-exposed cells in vitro. Significantly, STIM1^-/- attenuated hepatic injury compared to the WT mice after I/R, as evidenced by the improved pathological alterations in liver sections. WT mice subjected to liver I/R showed higher serum alanine aminotransferase (ALT) and aminotransferase (AST) levels, as well as pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1β, which were significantly reduced by STIM1^-/-. In addition, STIM1^-/- also decreased the liver mRNA levels of pro-inflammatory cytokines in mice after I/R injury. Furthermore, significantly decreased oxidative stress was found in STIM1^-/- mice after I/R injury compared to the WT group of mice, evidenced by the enhanced superoxide dismutase (SOD) activity and the reduced malondialdehyde (MDA) and reactive oxygen species (ROS) levels in liver tissue samples. Moreover, STIM1^-/- mice with hepatic I/R injury displayed the down-regulated nuclear factor of activated T cell (NFAT1), Orai1 and cleaved Caspase-3 levels in liver, contributing to apoptosis suppression. The results above were confirmed in hypoxia-treated cells lacking of STIM1 expression. Together, the findings suggested that STIM1-deletion protects the liver from I/R injury in mice through inhibiting inflammation, oxidative stress and apoptosis. STIM1 could be considered as a potential therapeutic target to ameliorate I/R injury.

The inflammatory responses in Cu-mediated elemental imbalance is associated with mitochondrial fission and intrinsic apoptosis in Gallus gallus heart

Copper (Cu) is an essential trace element for organism of function properly. Overexposure to Cu causes chronic cardiac impairment. The aim of this study was to investigate the change of 28-trace element, inflammatory response, the possible mitochondrial dynamics and apoptosis under Cu exposure in the heart of chickens. Cupric sulfate (CuSO₄) (300 mg/kg) was administered in a basal diet to male Hy-line chickens (one-day-old) for 90 days. Results showed the concentrations of Cu in the Cu group were increased by 57.8%, 27.57% and 57.2% at 30, 60 and 90 days, respectively. The Cu supplement caused trace elements imbalance, including reduced concentrations of B, Al, Ni, Ba, Pb and increased Li, Na, Mg, Si, K, Ca, V, Mn, Fe, Co, Zn, As, Mo in the heart of chickens. Exposure to Cu induced the TUNEL positive nuclei, histopathological alterations and ultrastructural apoptotic features. Moreover, Cu exposure activated the NF-κB-mediated pro-inflammatory cytokines, decreased the mRNA levels of opa1, mfn1, mfn2, Bcl-2, increased the mRNA levels of drp1, Bax, caspase-3, caspase-9, P53, while not altered Fas and caspase-8 compared with the control group. Similarly, western blot results showed the same trend of mRNA. Correlation analysis indicated that mitochondrial fission and intrinsic apoptosis might function synergistic. Moreover, mitochondrial network seem to function as cytosolic sensors for the induction of NF-κB mediated inflammatory responses. In summary, we speculated that Cu-induced redistribution of trace elements contributed to inflammatory response and disrupted the mitochondrial network via fission and intrinsic apoptosis in the heart of chickens.

GPR4 knockout improves renal ischemia-reperfusion injury and inhibits apoptosis via suppressing the expression of CHOP

The aim of the present study was to investigate the effects and molecular mechanisms of GPR4 (G-protein-coupled receptor 4) in cell apoptosis and renal ischemia-reperfusion (IR) injury in vivo and in vitro GPR4^-/- mice and wild-type (WT) mice underwent renal IR or sham procedures. For hypoxia/reoxygenation (HR), human umbilical vein endothelial cells (HUVECs) were subjected to 4 h of hypoxia, followed by 6 h of reoxygenation. Renal histological changes were observed by periodic acid-Schiff staining and myeloperoxidase activity. Apoptosis was detected by TUNEL staining. GPR4, C/EBP-homologous protein (CHOP) and cleaved caspase-3 protein expressions were detected by western blot. Both GPR4 and CHOP were up-regulated after renal IR in mice. GPR4-knockout mice had significantly less renal damage and decreased TUNEL-positive cells than WT controls after IR. Bone marrow chimeras demonstrated that it was due to the GPR4 inactivation in renal parenchymal cells. Moreover, GPR4 was mainly expressed in endothelial cells after renal IR. GPR4 knockdown markedly inhibited CHOP expression and cell apoptosis in the HUVECs after HR treatment. GPR4 blockade attenuated renal injury after IR and reduced the cell apoptosis through the suppression of CHOP expression.

Luteolin Treatment Protects against Renal Ischemia-Reperfusion Injury in Rats

Renal ischemia-reperfusion (I/R) injury is a common but severe scientific problem. Luteolin has great anti-inflammatory and antioxidant effects. In this study, we studied the effect of luteolin on renal I/R injury in rats. Intragastric administration of luteolin or saline was performed in Sprague-Dawley rats before (40 mg/kg for three days) and after (one day) renal I/R modeling. Kidney and blood samples were harvested to detect the severity of renal injury 24 hours after operation. The results showed that luteolin-treated rats exhibited milder histomorphological changes with lower scores of renal histological lesions; lower blood urea nitrogen and creatinine levels; lower renal malondialdehyde (MDA), 8-oxo-deoxyguanosine (8-OHdG), and myeloperoxidase (MPO) levels; and higher superoxide dismutase (SOD) and catalase (CAT) activities in the kidney. Luteolin attenuated the increased levels of serum and renal tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, renal high mobility group box-1 (HMGB1), and nuclear factor kappa β (NF-κB) expression levels in I/R rats. Furthermore, luteolin treatment significantly reduced renal cell apoptosis and endoplasmic reticulum (ER) stress caused by renal I/R injury. In conclusion, luteolin improved renal function in I/R rats by reducing oxidative stress, neutrophil infiltration, inflammation, renal cell apoptosis, and expression of HMGB1 and NF-κB, and ER stress.

Spermidine is protective against kidney ischemia and reperfusion injury through inhibiting DNA nitration and PARP1 activation

Kidney ischemia and reperfusion injury (IRI) is associated with a high mortality rate, which is attributed to tubular oxidative and nitrative stresses; however, an effective approach to limit IRI remains elusive. Spermidine, a naturally occurring polyamine, protects yeast cells against aging through the inhibition of oxidative stress and necrosis. In the present study, spermidine supplementation markedly attenuated histological damage and kidney dysfunction during IRI. In addition, exogenous spermidine potently inhibited poly(ADP-ribose) polymerase 1 (PARP1) activation and DNA nitrative/oxidative stress following IRI. Conversely, inhibition of ornithine decarboxylase (ODC) via siRNA transfection in vivo significantly enhanced DNA nitration, PARP1 activation, and functional damage during IRI. Finally, in ODC knockdown kidneys, PARP1 inhibition attenuated histological and functional damage induced by IRI, but not DNA nitrative stress. In conclusion, these data suggest that spermidine protects kidneys against IRI through blocking DNA nitration and PARP1 activation and this finding provides a novel target for prevention of acute kidney injury including IRI.

Evaluation of potential changes in liver and lung tissue of rats in an ischemia-reperfusion injury model (modified pringle maneuver)

In surgical procedures involving the liver, such as transplantation, resection, and trauma, a temporary occlusion of hepatic vessels may be required. This study was designed to analyze the lesions promoted by ischemia and reperfusion injury of the hepatic pedicle, in the liver and lung, using histopathological and immunohistochemical techniques. In total, 39 Wistar rats were divided into four groups: control group (C n = 3) and ischemia groups subjected to 10, 20, and 30 minutes of hepatic pedicle clamping (I10, n = 12; I20, n = 12; I30, n = 12). Each ischemia group was subdivided into four subgroups of reperfusion (R15, n = 3; R30, n = 3; R60, n = 3; R120, n = 3), after 15, 30, 60, and 120 minutes of reperfusion, respectively. Significant differences were observed in the liver parenchyma (P < 0.05) between the values of microvesicles and hydropic degeneration at different times of ischemia and reperfusion. However, the values of vascular congestion, necrosis, and pyknotic nuclei showed no significant differences (P > 0.05). In the lung parenchyma, a significant difference was observed (P < 0.05) between the values of alveolar septal wall thickening and inflammatory infiltration at different times of ischemia and reperfusion. However, there was no significant difference (P < 0.05) between the values of vascular congestion, bronchial epithelial degeneration, interstitial edema, and hemorrhage. The positive immunoreactivity of caspase-3 protein in the liver parenchyma (indication of ongoing apoptosis), showed no significant differences (P > 0.05) at different times of ischemia and reperfusion. In the pulmonary parenchyma, the immunoreactivity was not specific, and was not quantified. This study demonstrated that the longer the duration of ischemia and reperfusion, the greater are the morphological lesions found in the hepatic and pulmonary parenchyma.

TAK1 as the mediator in the protective effect of propofol on renal interstitial fibrosis induced by ischemia/reperfusion injury

Ischemia-reperfusion injury (IRI), which is a major cause of acute and chronic renal dysfunction, induces both apoptosis and fibrotic processes. The mitogen-activated protein kinase kinase kinase transforming growth factor-β-activated kinase 1 (TAK1) was implicated in the processes of inflammation and fibrosis. The protective effect of propofol on renal functionality after acute kidney injury (AKI) in mice has been identified, whereas the mechanisms underlying fibrosis induced by kidney injury remain obscure. Herein, we investigated whether the protective effect of propofol on renal interstitial fibrosis induced by ischemia/reperfusion injury was modulated by TAK1 in renal ischemia /reperfusion (I/R) mouse models. The results of immunohistochemistry and western blotting revealed that TAK1 was significantly upregulated in IR group versus the control group, which was reversed by propofol administration. In addition, fibronectin (FN), α-smooth muscle actin (α-SMA) and type I collagen (COL1) were significantly downregulated and Tunnel staining revealed the number of tubular apoptotic cells was markedly reduced in IRP group versus IR group. Collectively, our results validated that propofol could ameliorate the IRI-induced renal interstitial fibrosis in mice by downregulation of TAK1 and inhibition of apoptosis at the early stage.

Innate Immune Response in Kidney Ischemia/Reperfusion Injury: Potential Target for Therapy

Acute kidney injury caused by ischemia and subsequent reperfusion is associated with a high rate of mortality and morbidity. Ischemia/reperfusion injury in kidney transplantation causes delayed graft function and is associated with more frequent episodes of acute rejection and progression to chronic allograft nephropathy. Alloantigen-independent inflammation is an important process, participating in pathogenesis of injurious response, caused by ischemia and reperfusion. This innate immune response is characterized by the activity of classical cells belonging to the immune system, such as neutrophils, macrophages, dendritic cells, lymphocytes, and also tubular epithelial cells and endothelial cells. These immune cells not only participate in inflammation after ischemia exerting detrimental influence but also play a protective role in the healing response from ischemia/reperfusion injury. Delineating of complex mechanisms of their actions could be fruitful in future prevention and treatment of ischemia/reperfusion injury. Among numerous so far conducted experiments, observed immunomodulatory role of adenosine and adenosine receptor agonists in complex interactions of dendritic cells, natural killer T cells, and T regulatory cells is emphasized as promising in the treatment of kidney ischemia/reperfusion injury. Potential pharmacological approaches which decrease NF-κB activity and antagonize mechanisms downstream of activated Toll-like receptors are discussed.

Glycine-nitronyl nitroxide conjugate protects human umbilical vein endothelial cells against hypoxia/reoxygenation injury via multiple mechanisms and ameliorates hind limb ischemia/reperfusion injury in rats

Oxidative stress and inflammation play important roles in the pathogenesis of ischemia/reperfusion (I/R)-injury. The administration of antioxidants and anti-inflammatory agents has been applied to prevent I/R-injury for several decades. Of the numerous compounds administrated therapeutically in anti-oxidative stress, nitronyl nitroxide has gained increasing attention due to its continuous ability to scavenge active oxygen radicals. However, its effect is not ideal in clinical therapy. In previous study, we linked the anti-inflammatory amino acid glycine to nitronyl nitroxide and developed a novel glycine-nitronyl nitroxide (GNN) conjugate, which showed a synergetic protection against renal ischemia/reperfusion injury. However, the underlying mechanism remains unclear. In this study, a hypoxia/reoxygenation (H/R) injury model was established in human umbilical vein endothelial cells (HUVECs) and we found that the GNN conjugate significantly elevated the cell viability via reducing the apoptosis rate in H/R-treated HUVECs. Meanwhile, GNN conjugate attenuated H/R induced mitochondrial fragmentation, mitochondrial membrane potential reduction, Cytochrome c release and autophagy. To determine the extensive applicability of GNN conjugate in different I/R models and its effect in remote organs, an in vivo hind limb I/R model was established. As expected, GNN conjugate ameliorated damages of muscle and remote organs. These results demonstrate that GNN conjugate may be an effective agent against ischemia/reperfusion injury in clinical therapy.

Intestinal fatty acid-binding protein and gut permeability responses to exercise

PURPOSE

Intestinal cell damage due to physiological stressors (e.g. heat, oxidative, hypoperfusion/ischaemic) may contribute to increased intestinal permeability. The aim of this study was to assess changes in plasma intestinal fatty acid-binding protein (I-FABP) in response to exercise (with bovine colostrum supplementation, Col, positive control) and compare this to intestinal barrier integrity/permeability (5 h urinary lactulose/rhamnose ratio, L/R).

METHODS

In a double-blind, placebo-controlled, crossover design, 18 males completed two experimental arms (14 days of 20 g/day supplementation with Col or placebo, Plac). For each arm participants performed two baseline (resting) intestinal permeability assessments (L/R) pre-supplementation and one post-exercise following supplementation. Blood samples were collected pre- and post-exercise to determine I-FABP concentration.

RESULTS

Two-way repeated measures ANOVA revealed an arm × time interaction for L/R and I-FABP (P < 0.001). Post hoc analyses showed urinary L/R increased post-exercise in Plac (273% of pre, P < 0.001) and Col (148% of pre, P < 0.001) with post-exercise values significantly lower with Col (P < 0.001). Plasma I-FABP increased post-exercise in Plac (191% of pre-exercise, P = 0.002) but not in the Col arm (107%, P = 0.862) with post-exercise values significantly lower with Col (P = 0.013). Correlations between the increase in I-FABP and L/R were evident for visit one (P = 0.044) but not visit two (P = 0.200) although overall plots/patterns do appear similar for each.

CONCLUSION

These findings suggest that exercise-induced intestinal cellular damage/injury is partly implicated in changes in permeability but other factors must also contribute.

Protective Effect of Polydeoxyribonucleotide Against Renal Ischemia-Reperfusion Injury in Mice

BACKGROUND

Polydeoxyribonucleotide (PDRN) is an A2A receptor agonist that induces vascular endothelial growth factor (VEGF) production during the pathological condition of low tissue perfusion. Ischemia-reperfusion injury (IRI) is a major problem after renal transplantation. In the present study, we investigated whether PDRN exhibits reno-protective effects against ischemia-reperfusion-induced acute kidney injury in mice.

METHODS

Renal ischemia-reperfusion injury was induced in male C57BL/6 mice by bilateral renal pedicle occlusion for 30 minutes, followed by reperfusion for 48 hours. PDRN (8 mg/kg body weight intraperitoneally) was administered 30 minutes before IRI.

RESULTS

Treatment with PDRN significantly decreased neutrophil gelatinase-associated lipocalin levels in the urine, blood urea nitrogen level, and serum creatinine levels as well as kidney tubular injury. Western blotting showed that PDRN significantly increased the levels of vascular endothelial growth factor and B-cell lymphoma protein and attenuated p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, inducible nitric oxide synthase, and Bcl-2-associated X protein levels 48 hours after IRI.

CONCLUSIONS

Our findings suggest that PDRN is a potential therapeutic agent for acute ischemia-induced renal damage.

Identification of potential candidate genes for hypertensive nephropathy based on gene expression profile

Background

This study was aimed to explore the molecular mechanisms of hypertensive nephropathy (HTN).

Methods

Gene expression profile of GSE37460, which based on 27 healthy living donor samples (HTN group) and 15 hypertensive nephropathy samples (control group), were downloaded from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between two groups were identified. STRING database was used to reveal protein-protein interaction (PPI) network of DEGs, followed by the functional enrichment analysis of the PPI network. Additionally, miRNA-DEG regulatory network was constructed to reveal the validated miRNAs targeting the DEGs.

Results

In total, 51 up-regulated genes and 140 down-regulated genes were obtained. In the PPI network, cytochrome P450 3A4 (CYP3A4) and angiotensin II receptor type 1 (AGTR1) had a higher degree, and CYP3A4 interacted with CYP4A11. The DEGs in the network were significantly enriched in drug metabolism, focal adhesion and arachidonic acid metabolism. Furthermore, in the miRNA-DEG regulatory network, hsa-miR-335-5p and hsa-miR-26b-5p were the two most outstanding miRNAs. AGTR1, CYP3A4 and CYP4A11 were predicted to be regulated by hsa-miR-26b-5p.

Conclusion

The DEGs, such as AGTR1, CYP3A4 and CYP4A11 may play critical roles in the development of HTN likely via the regulation by hsa-miR-26b-5p and taking part in some pathways.

Small interfering RNA targeting TNF-α gene significantly attenuates renal ischemia-reperfusion injury in mice

Tumor necrosis factor-alpha (TNF-α) has been found to be centrally involved in the development of ischemia-reperfusion injury (IRI)-induced inflammation and apoptosis. Knockdown of TNF-α gene using small interfering RNA (siRNA) may protect renal IRI. Renal IRI was induced in mice by clamping the left renal pedicle for 25 or 35 min. TNF-α siRNA was administered intravenously to silence the expression of TNF-α. The therapeutic effects of siRNA were evaluated in terms of renal function, histological examination, and overall survival following lethal IRI. A single systemic injection of TNF-α siRNA resulted in significant knockdown of TNF-α expression in ischemia-reperfusion injured kidney. In comparison with control mice, levels of BUN and serum creatinine were significantly reduced in mice treated with siRNA. Pathological examination demonstrated that tissue damage caused by IRI was markedly reduced as a result of TNF-α siRNA treatment. Furthermore, survival experiments showed that nearly 90% of control mice died from lethal IRI, whereas more than 50% of siRNApretreated mice survived until the end of the eight-day observation period. We have demonstrated for the first time that silencing TNF-α by specific siRNA can significantly reduce renal IRI and protect mice against lethal kidney ischemia, highlighting the potential for siRNA-based clinical therapy.

Prolonged Ischemic Time, Delayed Graft Function, and Graft and Patient Outcomes in Live Donor Kidney Transplant Recipients

The association between prolonged cold ischemic time (CIT) and graft and patient outcomes in live donor kidney transplant recipients remains unclear. The aims of this study were to examine the association of CIT with delayed graft function and graft loss in live donor kidney transplant recipients and those who participated in the Australian Paired Kidney Exchange program using data from the Australia and New Zealand Dialysis and Transplant (ANZDATA) registry. Of 3717 live donor transplant recipients between 1997 and 2012 who were followed for a median of 6.6 years (25 977 person-years), 224 (25%) experienced CIT >4-8 h. Donor age was an effect modifier between CIT and graft outcomes. In recipients who received kidneys from older donors aged >50 years, every hour of increase in CIT was associated with adjusted odds of 1.28 (95% confidence interval [CI] 1.07-1.53, p = 0.007) for delayed graft function, whereas CIT >4-8 h was associated with adjusted hazards of 1.93 (95% CI 1.21-3.09, p = 0.006) and 1.91 (95% CI 1.05-3.49, p = 0.035) for overall and death-censored graft loss, respectively, compared with CIT of 1-2 h. Attempts to reduce CIT in live donor kidney transplants involving older donor kidneys may lead to improvement of graft outcomes.

Gypenoside attenuates renal ischemia/reperfusion injury in mice by inhibition of ERK signaling

Gynostemma pentaphyllum is a traditional Chinese medicine reported to possess a wide range of health benefits. As the major component of G. pentaphyllum, gypenoside (GP) displays various anti-inflammatory and anti-oxidant properties. However, it is unclear whether GP can protect against ischemia/reperfusion (I/R)-induced renal injury, and the underlying molecular mechanisms associated with this process remain unknown. In the present study, a renal I/R injury model in C57BL/6 mice was established. It was observed that, following I/R, serum concentrations of creatinine (Cr) and blood urea nitrogen (BUN) were significantly increased (P<0.01), indicating renal injury. Pretreatment with GP (50 mg/kg) significantly inhibited I/R-induced upregulation of serum Cr and BUN (P<0.01). Furthermore, renal malondialdehyde levels were significantly reduced in the I/R+GP group, compared with the I/R group (P<0.01), whereas renal tissue superoxide dismutase activity was significantly higher in the I/R+GP group compared with the I/R group (P<0.01). Further investigation demonstrated that pretreatment with GP produced inhibitory effects on the I/R-induced production of pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6, tumor necrosis factor-α and interferon-γ (P<0.01). In addition, heme oxygenase 1 (HO-1) expression levels were significantly increased in the I/R group compared with the control (P<0.01), indicating the presence of oxidative damage. However, the I/R-induced upregulation of HO-1 was significantly attenuated by pretreatment with GP (P<0.01), which also suppressed I/R-induced apoptosis by inhibiting pro-apoptotic Bax and upregulating anti-apoptotic Bcl-2 in renal cells (P<0.01). Finally, the activity of ERK signaling was significantly increased in the I/R+GP group compared with the I/R group (P<0.05), which may be associated with the protective effect of GP against I/R-induced renal cell apoptosis. To conclude, the present results suggest that GP produces a protective effect against I/R-induced renal injury as a result of its anti-inflammatory and anti-apoptotic properties.

Protective role of silymarin in a mouse model of renal Ischemia-Reperfusion injury

BACKGROUND

We investigated the mechanism of action of silymarin in a mouse model of renal ischemia-reperfusion injury (I/R) to ascertain its role in the treatment of I/R injury.

METHODS

Twenty-four C57BL/6 male mice were divided randomly into three groups: control (sham); ischemia-reperfusion (I/R); silymarin + ischemia-reperfusion (silymarin + I/R). In sham mice, an abdominal incision was made, followed by dissection of the bilateral renal pedicle, with no further cross-clamping of arteries. Silymarin + I/R mice were administered 100 mg/kg silymarin daily for 7 consecutive days before surgery, whereas I/R mice were administered (i.g.) 0.9 % saline + 0.1 % (v/v) ethanol daily for 7 consecutive days before surgery. Silymarin + I/R and I/R mice were subjected to renal ischemia to induce acute kidney injury after 45-min clamping of bilateral renal arteries. Serum levels of creatinine and blood urea nitrogen levels were measured. Periodic acid-Schiff (PAS) staining was undertaken to detect damaged renal tissue. Myeloperoxidase (MPO) activity and immunofluorescent detection of CD68 expression was undertaken for each group. Levels of inflammatory cytokines secreted by renal tissue were monitored by ELISA. Apoptosis was detected by TUNEL staining. Expression of cleaved-caspase-3, Bcl-2 and Bax was detected by western blotting.

RESULTS

Serum creatinine and blood urea nitrogen levels were elevated in silymarin + I/R and I/R groups compared with sham mice (p < 0.05), whereas those in the I/R group were significantly higher than in the silymarin + I/R group (p < 0.05). Number of damaged renal tubule cells and apoptotic cells in sham and silymarin + I/R groups was significantly lower than in I/R mice. MPO activity and secretion of inflammatory cytokines in silymarin + I/R and I/R groups was reduced (p < 0.05), and CD68 expression in silymarin + I/R mice was lower than in I/R mice (p < 0.05). Expression of cleaved-caspase-3 and Bax in the I/R group was significantly higher than in sham mice, whereas Bcl-2 expression was lower than in silymarin + I/R mice (p < 0.05).

CONCLUSIONS

Silymarin can inhibit renal I/R injury by inhibiting release of inflammatory factors and regulating apoptosis.

Ischaemic conditioning reduces kidney injury in an experimental large-animal model of warm renal ischaemia

BACKGROUND

Ischaemic conditioning, using short repeated sequences of intermittent ischaemia, is a strategy that may ameliorate ischaemia-reperfusion injury. The aim of the study was to assess the effects of direct and remote ischaemic conditioning in a porcine model of renal warm ischaemia-reperfusion injury.

METHODS

Pigs (50 kg) underwent laparotomy and 60-min occlusion of the left renal pedicle followed by right nephrectomy. Animals were divided into three groups: untreated controls (n = 8); direct postconditioning involving six 15-s cycles of clamping then releasing of the left renal artery (n = 7); or remote periconditioning involving four 5-min cycles of clamping then releasing of the left common iliac artery (n = 8). After 7 days kidney tissue was harvested, and blood and urine samples were collected on postoperative days 1, 3 and 7.

RESULTS

The direct postconditioning group had a lower area under the serum creatinine curve (mean(s.d.) 1378(157) versus 2001(1022) µmol/l · day respectively; P = 0.036) and peak creatinine level (316(46) versus 501(253) µmol/l respectively; P = 0.033) compared with values in control animals. There was a significant increase in serum levels of tumour necrosis factor α on day 1 in control animals but not in the conditioning groups (P = 0.013). Urinary levels of neutrophil gelatinase-associated lipocalin increased over the study period in both the control and remote groups (P = 0.001 for both), but not in the direct group (P = 0.176). There was no mortality and no complications related to either conditioning technique.

CONCLUSION

In this in vivo large-animal model, direct renal artery ischaemic postconditioning protected kidneys against warm ischaemia injury. This straightforward technique could readily be translated into clinical practice. Surgical relevance Ischaemic conditioning has been shown to improve outcomes in both experimental studies and clinical trials in cardiac surgery. Evidence from small-animal and human studies assessing ischaemic conditioning techniques in renal transplantation have not yet established the optimal technique and timing of conditioning. In this study, a large-animal model of renal warm ischaemia was used to compare different conditioning techniques. Postconditioning applied directly to the renal artery was shown to reduce renal injury. Furthermore, new evidence is provided that shorter cycles of ischaemic postconditioning than previously described can protect against renal injury. Evidence from a large-animal model is provided for different conditioning techniques. The beneficial postconditioning technique described is straightforward to perform and provides an alternative method of conditioning following renal transplantation, with potential for application in clinical practice.