Initiation of the inflammatory response after renal ischemia/reperfusion injury during renal transplantation

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.

Puerarin protects renal ischemia-reperfusion injury in rats through NLRP3/Caspase-1/GSDMD pathway

PURPOSE

To observe the effect of puerarin on renal ischemia-reperfusion (I/R) injury in rats, and to explore its mechanism based on NLRP3/Caspase-1/GSDMD pathway.

METHODS

Twenty-one Sprague-Dawley rats were divided into three groups: sham-operated group (sham), model group (RIRI), and puerarin treatment group (RIRI + Pue). The model of acute renal I/R injury was established by cutting the right kidney and clamping the left renal pedicle for 45 min.

RESULTS

Renal function parameters were statistically significant in group comparisons. The renal tissue structure of rats in sham group was basically normal. Pathological changes were observed in the RIRI group. The renal pathological damage score and apoptosis rate in the RIRI group were higher than those in the sham group, and significantly lower in the RIRI + Pue group than in the RIRI group. Indicators of oxidative stress-superoxide dismutase, malondialdehyde, and glutathione peroxidase-were statistically significant in group comparisons. Compared with the sham group, the relative expressions of NLRP3, Caspase-1 and GSDMD proteins in the RIRI group were increased. Compared with the RIRI group, the RIRI + Pue group had significant reductions.

CONCLUSIONS

Puerarin can inhibit the activation of NLRP3/Caspase-1/GSDMD pathway, inhibit inflammatory response and pyroptosis, and enhance the antioxidant capacity of kidney, thereby protecting renal I/R injury in rats.

miRNA155-5P participated in DDX3X targeted regulation of pyroptosis to attenuate renal ischemia/reperfusion injury

BACKGROUND

Renal ischemia/reperfusion injury (IRI) induced pathological damage to renal microvessels and tubular epithelial cells through multiple factors. However, studies investigated whether miRNA155-5P targeted DDX3X to attenuate pyroptosis were scarce.

RESULTS

The expression of pyroptosis-related proteins (caspase-1, interleukin-1β (IL-1β), NOD-like receptor family pyrin domain containing 3 (NLRP3), and IL-18) were up-regulated in the IRI group. Additionally, miR-155-5p was higher in the IRI group comparing with the sham group. The DDX3X was inhibited by the miR-155-5p mimic more than in the other groups. DEAD-box Helicase 3 X-Linked (DDX3X), NLRP3, caspase-1, IL-1β, IL-18, LDH, and pyroptosis rates were higher in all H/R groups than in the control group. These indicators were higher in the miR-155-5p mimic group than in the H/R and the miR-155-5p mimic negative control (NC) group.

CONCLUSIONS

Current findings suggested that miR-155-5p decreased the inflammation involved in pyroptosis by downregulating the DDX3X/NLRP3/caspase-1 pathway.

METHODS

Using the models of IRI in mouse and the hypoxia-reoxygenation (H/R)-induced injury in human renal proximal tubular epithelial cells (HK-2 cells), we analyzed the changes in renal pathology and the expression of factors correlated with pyroptosis and DDX3X. Real-time reverse transcription polymerase chain reaction (RT-PCR) detected miRNAs and enzyme-linked immunosorbent assay (ELISA) was used to detect lactic dehydrogenase activity. The StarBase and luciferase assays examined the specific interplay of DDX3X and miRNA155-5P. In the IRI group, severe renal tissue damage, swelling, and inflammation were examined.

Dexmedetomidine attenuates renal ischemia-reperfusion injury through activating PI3K/Akt-eNOS signaling via α2 adrenoreceptors in renal microvascular endothelial cells

Renal microvascular endothelial cells (RMECs), which are closely related to regulation of vascular reactivity and modulation of inflammation, play a crucial role in the process of renal ischemia and reperfusion (I/R) injury. Previous studies have reported the protective effects of dexmedetomidine (DEX) against renal I/R injury, but little is known about the role of DEX on RMECs. This study aimed to investigate whether DEX alleviated renal I/R injury via acting on the RMECs. Mice underwent bilateral renal artery clamping for 45 min followed by reperfusion for 48 h, and the cultured neonatal mice RMECs were subjected to hypoxia for 1 h followed by reoxygenation (H/R) for 24 h. The results suggest that DEX alleviated renal I/R injury in vivo and improved cell viability of RMECs during H/R injury in vitro. Gene sequencing revealed that the PI3K/Akt was the top enriched signaling pathway and the endothelial cells were widely involved in renal I/R injury. DEX activated phosphorylation of PI3K and Akt, increased eNOS expression, and attenuated inflammatory responses. In addition, the results confirmed the distribution of α₂ adrenoreceptor (α₂ -AR) in RMECs. Furthermore, the protective effects of DEX against renal I/R injury were abolished by α₂ -AR antagonist (atipamezole), which was partly reversed by the PI3K agonist (740 Y-P). These findings indicated that DEX protects against renal I/R injury by activating the PI3K/Akt-eNOS pathway and inhibiting inflammation responses via α₂ -AR in RMECs.

NLRP3 inflammasome: A potential therapeutic target to minimize renal ischemia/reperfusion injury during transplantation

Renal transplantation is currently the best treatment option for patients with end-stage kidney disease. Ischemia/reperfusion injury (IRI), which is an inevitable event during renal transplantation, has a profound impact on the function of transplanted kidneys. It has been well demonstrated that innate immune system plays an important role in the process of renal IRI. As a critical component of innate immune system, Nod-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome has received great attention from scientific community over the past decade. The main function of NLRP3 inflammasome is mediating activation of caspase-1 and maturation of interleukin (IL)-1β and IL-18. In this review, we summarize the associated molecular signaling events about NLRP3 inflammasome in renal IRI, and highlight the possibility of targeting NLRP3 inflammasome to minimize renal IRI during transplantation.

MicroRNA as a Potential Biomarker and Treatment Strategy for Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is a progressive injury that aggravates the pathological state when the organ tissue restores blood supply after a certain period of ischemia, including the myocardial, brain, liver, kidney, and intestinal. With growing evidence that microRNAs (miRNAs) play an important role as posttranscription gene silencing mediators in many I/R injury, in this review, we highlight the microRNAs that are related to I/R injury and their regulatory molecular pathways. In addition, we discussed the potential role of miRNA as a biomarker and its role as a target in I/R injury treatment. Developing miRNAs are not without its challenges, but prudent design combined with existing clinical treatments will result in more effective therapies for I/R injury. This review is aimed at providing new research results obtained in this research field. It is hoped that new research on this topic will not only generate new insights into the pathophysiology of miRNA in I/R injury but also can provide a basis for the clinical application of miRNA in I/R.

Prospective comparative study of postoperative systemic inflammatory syndrome in robot-assisted vs. open kidney transplantation

PURPOSE

Robot-assisted kidney transplant (RAKT) recently proved to provide functional results similar to the preferred open kidney transplant (OKT), but with inferior wound morbidity. In a comparative prospective study, we explored the systemic inflammatory response syndrome (SIRS) after KT and compared OKT with RAKT.

METHODS

Forty-nine patients underwent pre-emptive ABO-compatible kidney transplantations (KT) between January 2017 and December 2018 in 2 centers: 25 RAKT, 24 OKT. Postoperative SIRS was biologically assessed by serum markers (NGAL, CRP and IL-6) measured at: T0 (preoperative/baseline), T1(H1), T2(H6), T3(H12), T4(H24), T5(D2), T6(D3) and T7(D5) after KT.

RESULTS

Inflammatory markers + eGFR were assessed in OKT vs. RAKT. IL-6 peak value occurred at H6 and reached ×9 from baseline. CRP peak occurred at H24 and reached ×28 from baseline (All P < 0.05). NGAL decreased after surgery with a plateau (divided by 2 from baseline) from H12 to D5. There was no significant difference in IL-6, CRP and NGAL kinetics and peak values between RAKT and OKT (All P > 0.05). Serum creatinine and eGFR on postoperative days 1, 3 and 7 were similar in RAKT and OKT (All P > 0.05). Delayed graft function was not observed.

CONCLUSION

In this exploratory study, the biological evaluation of postoperative SIRS after living-donor kidney transplant revealed no significant difference between OKT and RAKT and similar functional outcomes in the short term. These results highlight the safety of RAKT as an alternative to OKT in this setting.

Ganoderic Acids Prevent Renal Ischemia Reperfusion Injury by Inhibiting Inflammation and Apoptosis

Renal ischemia reperfusion injury (RIRI) is one of the main causes of acute kidney injury (AKI), which can lead to acute renal failure. The development of RIRI is so complicated that it involves many factors such as inflammatory response, oxidative stress and cell apoptosis. Ganoderic acids (GAs), as one of the main pharmacological components of Ganoderma lucidum, have been reported to possess anti-inflammatory, antioxidant, and other pharmacological effects. The study is aimed to investigate the protective effect of GAs on RIRI and explore related underlying mechanisms. The mechanisms involved were assessed by a mouse RIRI model and a hypoxia/reoxygenation model. Compared with sham-operated group, renal dysfunction and morphological damages were relieved markedly in GAs-pretreatment group. GAs pretreatment could reduce the production of pro-inflammatory factors such as IL-6, COX-2 and iNOS induced by RIRI through inhibiting TLR4/MyD88/NF-kB signaling pathway. Furthermore, GAs reduced cell apoptosis via the decrease of the ratios of cleaved caspase-8 and cleaved caspase-3. The experimental results suggest that GAs prevent RIRI by alleviating tissue inflammation and apoptosis and might be developed as a candidate drug for preventing RIRI-induced AKI.

Activation of Nrf2 Pathway by Dimethyl Fumarate Attenuates Renal Ischemia-Reperfusion Injury

BACKGROUND

Dimethyl fumarate (DMF) is a novel antioxidant that selectively reduces hydroxyl radicals. This study aimed to investigate the potential role of DMF in the pathogenesis of renal ischemia-reperfusion injury (IRI) and the mechanisms involved.

METHODS

C57BL/6 wild-type mice were treated with DMF or a vehicle. Subsequently, renal IRI was induced in mice by a model of right kidney nephrectomy and left renal ischemia for 30 minutes followed by reperfusion for 24 hours. Sham operation and phosphate-buffered saline were used as controls. Serum and renal tissues were collected at 24 hours after IRI to evaluate the influence of DMF on the recovery of renal function after IRI. Blood urea nitrogen and serum creatinine levels were measured. Kidney cell apoptosis was evaluated using terminal deoxynucleotidyl transferase dUTP nick end labeling-positive staining. Interleukin 6 and tumor necrosis factor α cytokines in the kidney tissues were measured. Indicators of oxidative stress in the kidneys were detected. Finally, Nrf2-deficient mice were used to determine the protective role of the nuclear factor erythroid 2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1) and NAD(P)H dehydrogenase quinone 1 (NQO1) signaling pathways induced by DMF using western blot assay.

RESULTS

DMF significantly attenuated renal dysfunction in mice and showed reductions in the severity of renal tubular injury, cell necrosis, and apoptosis. Moreover, DMF significantly reduced the amount of key inflammatory mediators. Additionally, DMF attenuated the malondialdehyde levels 24 hours after IRI but upregulated the superoxide dismutase activities. Western blot assay showed that DMF significantly increased the protein levels of Nrf2, HO-1, and NQO-1. Importantly, these DMF-mediated beneficial effects were not observed in Nrf2-deficient mice.

CONCLUSIONS

DMF attenuates renal IRI by reducing inflammation and upregulating the antioxidant capacity, which may be through Nrf2/HO-1and NQO1 signaling pathway.

Knockdown of ANGPTL2 Protects Renal Tubular Epithelial Cells Against Hypoxia/Reoxygenation-Induced Injury via Suppressing TLR4/NF-κB Signaling Pathway and Activating Nrf2/HO-1 Signaling Pathway

Renal ischemia/reperfusion (I/R) injury is a particular threat faced by clinicians in kidney transplantation. Previous studies have confirmed the importance of oxidative stress and inflammation in the pathogenesis of I/R injury. Angiopoietin-like protein 2 (ANGPTL2) belongs to the angiopoietin-like family and has been found to be involved in the regulation of kidney function as well as oxidative and inflammatory response. In the present study, we aimed to evaluate the role of ANGPTL2 in renal I/R injury in vitro. The human proximal tubular epithelial cell line (HK-2 cells) was subjected to hypoxia/ reoxygenation (H/R) to mimic I/R injury in vitro. We found that the expression level of ANGPTL2 was markedly increased in H/R-induced HK-2 cells. Knockdown of ANGPTL2 improved the decreased cell viability of HK-2 cells in response to H/R stimulation. Knockdown of ANGPTL2 significantly inhibited the H/R-caused increase in levels of reactive oxygen species, malondialdehyde, and proinflammatory cytokines, including interleukin (IL)-6, IL-1β, and tumor necrosis factor-alpha, as well as a decrease in superoxide dismutase activity in the HK-2 cells. Besides, the increased bax expression and caspase-3 activity and decreased bcl-2 expression in H/R-induced HK-2 cells were also attenuated by knockdown of ANGPTL2. Moreover, ANGPTL2 overexpression showed the opposite effects. Further mechanism investigations proved that the activation of Nrf2/HO-1 signaling pathway and the inhibition of toll-like receptor 4/nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway were both implicated in the renal-protective effects of ANGPTL2 knockdown on H/R-induced HK-2 cells. Collectively, these findings suggested that ANGPTL2 might be a new possible target for the treatment and prevention of renal I/R injury.

Exosome-based delivery of super-repressor IκBα ameliorates kidney ischemia-reperfusion injury

Ischemia-reperfusion injury is a major cause of acute kidney injury. Recent studies on the pathophysiology of ischemia-reperfusion-induced acute kidney injury showed that immunologic responses significantly affect kidney ischemia-reperfusion injury and repair. Nuclear factor (NF)-ĸB signaling, which controls cytokine production and cell survival, is significantly involved in ischemia-reperfusion-induced acute kidney injury, and its inhibition can ameliorate ischemic acute kidney injury. Using EXPLOR, a novel, optogenetically engineered exosome technology, we successfully delivered the exosomal super-repressor inhibitor of NF-ĸB (Exo-srIĸB) into B6 wild type mice before/after kidney ischemia-reperfusion surgery, and compared outcomes with those of a control exosome (Exo-Naïve)-injected group. Exo-srIĸB treatment resulted in lower levels of serum blood urea nitrogen, creatinine, and neutrophil gelatinase-associated lipocalin in post-ischemic mice than in the Exo-Naïve treatment group. Systemic delivery of Exo-srIĸB decreased NF-ĸB activity in post-ischemic kidneys and reduced apoptosis. Post-ischemic kidneys showed decreased gene expression of pro-inflammatory cytokines and adhesion molecules with Exo-srIĸB treatment as compared with the control. Intravital imaging confirmed the uptake of exosomes in neutrophils and macrophages. Exo-srIĸB treatment also significantly affected post-ischemic kidney immune cell populations, lowering neutrophil, monocyte/macrophage, and T cell frequencies than those in the control. Thus, modulation of NF-ĸB signaling through exosomal delivery can be used as a novel therapeutic method for ischemia-reperfusion-induced acute kidney injury.

Exploring the role of the complement system, endothelial injury, and microRNAs in thrombotic microangiopathy after kidney transplantation

Objective

We investigated whether the recipient’s complement system function, kidney graft endothelial ultrastructural injury, and microRNA (miRNA) expression before transplantation may be associated with the risk of posttransplant de novo thrombotic microangiopathy (TMA).

Methods

Complement system function assessment, histological and ultrastructural examination of preimplantation and kidney graft biopsies, and microRNA assessment were performed on kidney transplant recipients (KTRs) with de novo TMA.

Results

On the basis of the clinical course, histological findings, and miRNA patterns, the following two de novo TMA phenotypes were observed: a self-limiting disease that was localized to the kidney graft and a systemic disease that progressed to graft failure without timely treatment. Decreased alternative complement pathway activity and ultrastructural endothelial injury before transplantation were confirmed in all five KTRs and four of five KTRs, respectively, but they did not correlate with de novo TMA severity.

Conclusions

Alternative complement pathway abnormalities in KTRs and endothelial ultrastructural injury on preimplantation biopsy might be associated with de novo posttransplant TMA, although they did not predict posttransplant TMA severity (localized vs. systemic). The specific miRNA expression patterns in preimplantation kidney graft biopsies demonstrated a borderline statistically significant difference and might provide more accurate information on posttransplant TMA severity.

Linarin Protects the Kidney against Ischemia/Reperfusion Injury via the Inhibition of Bioactive ETS2/IL-12

Ischemia/reperfusion injury (IRI), a participant in acute kidney injury (AKI), can occur as a series of pathological processes such as inflammation. Linarin (LIN) has been widely used for different diseases. To confirm the anti-inflammatory value and relevant mechanism of LIN during IRI, in vivo and vitro models were established. LIN or dissolvent was given, and histologic analysis, quantitative (q)RT-PCR, serum creatinine and blood urea nitrogen testing were used to evaluate kidney injury. Microarray analysis, protein-protein interaction (PPI) analysis and molecular docking were used to identify the target protein of LIN, and small interfering RNA (siRNA) transfection was applied to explore the crucial role of identified protein. First, we found that LIN inhibited kidney injury in an in vivo IRI model and decreased the expression of interleukin-12 (IL-12) p40 in vivo and in vitro IRI models. To explore the mechanism of LIN, we collected raw data from a public microarray database and identified E26 oncogene homolog 2 (ETS2) as a crucial protein of LIN according to microarray analysis and PPI. Meanwhile, qRT-PCR indicated that IL-12 p40 showed no significant difference between ETS2 knock down group and LIN treated ETS2 knock down group after hypoxia reoxygenation treatment. In addition, according to molecular docking the contact area is highly conserved and located on a PPI domain of ETS2 which indicates that LIN may alter the interaction with synergistic proteins in the regulation of IL-12 p40 expression. Our study demonstrated the anti-inflammatory effect of LIN during IRI-AKI, broadening the medicinal value of LIN and the therapeutic options for IRI-AKI.

Total Glucosides of Paeony Alleviate Cell Apoptosis and Inflammation by Targeting the Long Noncoding RNA XIST/MicroRNA-124-3p/ITGB1 Axis in Renal Ischemia/Reperfusion Injury

OBJECTIVE

Renal ischemia/reperfusion injury (RI/RI) is the main cause of acute kidney injury. Total glucosides of paeony (TGP) are a traditional Chinese medicine. This study was aimed at exploring the role of TGP in RI/RI and its underlying mechanism of action.

METHODS

Rat RI/RI models were constructed by surgical operation. Serum creatinine (Scr) and blood urea nitrogen (BUN) were used to evaluate renal function. The levels of proinflammatory cytokines were detected by ELISA. RI/RI was simulated by hypoxia/reoxygenation (H/R) treatment in renal cells in vitro. The lncRNA XIST (XIST) expression was analyzed by qRT-PCR. Then, the viability and apoptosis of renal cells were detected by MTT and flow cytometry assay. Additionally, dual-luciferase reporter assay was used to determine the interactions among XIST, microRNA-124-3p (miR-124-3p), and ITGB1.

RESULTS

TGP improved renal function and inhibited inflammatory responses after RI/RI. XIST expression was highly expressed in rat RI/RI models and H/R-treated renal cells, whereas treatment with TGP downregulated the XIST expression. Additionally, TGP increased viability and attenuated apoptosis and inflammation of H/R-treated renal cells via inhibiting XIST. Moreover, XIST was competitively bound to miR-124-3p, and ITGB1 was a target of miR-124-3p. miR-124-3p overexpression or ITGB1 inhibition rescued the reduction effect on viability and mitigated the promoting effects on cell apoptosis and inflammation caused by XIST overexpression in H/R-treated renal cells.

CONCLUSIONS

In vivo, TGP attenuated renal dysfunction and inflammation in RI/RI rats. In vitro, TGP inhibited XIST expression to modulate the miR-124-3p/ITGB1 axis, alleviating the apoptosis and inflammation of H/R-treated renal cells.

TNF, IL-6, and IL-10 cytokines levels and their polymorphisms in renal function and time after transplantation

Cytokine polymorphisms can influence their plasma levels and thus affect the immune response in renal transplantation. A total of 146 renal transplant recipients (RTR) were classified into groups according to the estimated glomerular filtration rate (R1: < 60 and R2: ≥ 60 mL/min/1.73 m²) and time after transplantation (T1: 1 to 24, T2: 25 to 60, T3: 61 to 120, and T4: > 120 months after transplantation). The polymorphisms were genotyped by single specific primer-polymerase chain reaction. IL-10 was measured by ELISA and IL-6, and TNF levels were determined using Miliplex®. A higher frequency of the - 308G allele and the - 308G/G genotype, low-producer, was observed in the R1 group compared with R2. In addition, a higher frequency of the - 308A carriers, high-producer, was found in the R2 group. However, no significant difference was observed in cytokine levels when both groups were compared. Higher levels of IL-6 were observed in T1 compared with T2 and T4 groups. Lower IL-6 levels were found in T2 compared with T3 group. Lower levels of IL-10 were also found in T1 group in relation to T2, while higher levels of this cytokine were observed in T2 group compared with T3. The results suggest that the - 308G > A polymorphism in the TNF gene is associated with filtration function after renal transplantation, and IL-6 and IL-10 levels change according to the time after transplantation. Thus, the joint evaluation of - 308G > A polymorphism in TNF gene and IL-6 and IL-10 levels would provide a broader and effective view on the clinical monitoring of RTR.

Inhibition of myeloid differentiation protein 2 attenuates renal ischemia/reperfusion-induced oxidative stress and inflammation via suppressing TLR4/TRAF6/NF-kB pathway

As a major risk factor of acute kidney injury, renal ischemia/reperfusion (I/R) has a high mortality rate. Myeloid differentiation protein 2 (MD-2) is a secretory glycoprotein that plays an important role in inflammation. Our study aimed to explore the roles of MD-2 in I/R-induced inflammation and oxidative stress in vivo and in vitro. For the in vivo studies, male C57BL/6 mice were randomly divided into four groups: 1) sham, 2) I/R, 3) negative control for siRNA (siNC) and I/R treatment, or 4) MD-2 siRNA (siMD-2) and I/R. Levels of blood urea nitrogen and creatinine in the plasma were tested, and hematoxylin and eosin staining was performed at 24 h after I/R injury. The inflammatory cytokines TNF-α, IL-6, and MCP-1 were measured using ELISA and Real-time qPCR (RT-qPCR). Malondialdehyde (MDA) content and superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activity were estimated. For the in vitro studies, HK-2 cells were transfected with siMD-2 and then exposed to hypoxia/reoxygenation (H/R). Inflammatory cytokine expression and oxidative stress then were evaluated. We found decreased levels of blood urea nitrogen and creatinine levels after MD-2 silencing. MD-2 deficiency improved histological damage. MD-2 downregulation attenuated levels of inflammatory cytokines. Inhibition of MD-2 resulted in reduced MDA content and increased SOD, CAT, and GPx activity. Loss of function of MD-2 inhibited the H/R-induced production and expression of inflammatory cytokines. MD-2 silencing reduced MDA content after H/R, and MD-2 suppression enhanced SOD, CAT, and GPx activity. MD-2 deficiency also blocked H/R-mediated activation of the TLR4/TRAF6/NF-κB pathway, and pyrrolidinedithiocarbamate (PDTC) pretreatment strengthened the anti-inflammatory and antioxidant damage effects of MD-2 silencing. Taken together, our study revealed that MD-2 deficiency ameliorated renal I/R-induced inflammation and oxidative stress via inhibition of TLR4/TRAF6/NF-κB pathway.

Characteristics of Changes in Inflammatory Cytokines as a Function of Hepatic Ischemia-Reperfusion Injury Stage in Mice

Liver ischemia-reperfusion injury (IRI) can severely compromise the prognosis of patients receiving liver surgery. While inflammation contributes to the damage resulting from IRI, only a limited number of inflammation biomarkers have been identified as being associated with the different stages of hepatic IRI. As an approach to identify some of these inflammatory cytokines and the molecular mechanisms involved within different stages of hepatic IRI, we used an advanced antibody array assay to detect multiple proteins. With this technology, we observed specific differences in the content of inflammatory cytokines between ischemic and sham controls, as well as a function of the different reperfusion stages in a hepatic IRI mouse model. For example, while liver tissue content of IL-12p40/p70 was significantly increased in the ischemic stage, it was significantly decreased in the reperfusion stage as compared with that of the sham group. For other inflammatory cytokines, no changes were obtained between the ischemic and reperfusion stages with levels of IL-17, Eotaxin-2, Eotaxin, and sTNF RII all being consistently increased, while those of TIMP-1, TIMP-2, BLC, and MCSF consistently decreased as compared with that of the sham group at all reperfusion stages examined. Results from protein function annotation Gene Ontology and the KEGG pathway revealed that inflammatory cytokines are enriched in a network associated with activation of inflammatory response signaling pathways such as TLR, TNF, and IL-17 when comparing responses of the IR versus sham groups. The identification of cytokines along with their roles at specific stages of IRI may reveal important new biological markers for the diagnosis and prognosis of hepatic IRI.

Predictors of symptomatic lymphocele after kidney transplantation

Purpose

The development of a symptomatic lymphocele (SL) is a frequent postoperative surgical complication after kidney transplantation. It may lead to pain and discomfort and cause transplant malfunction or even secondary graft loss. A large cohort of renal recipients was investigated to identify the possible risk factors for SL.

Methods

All renal transplant patients of a single centre were retrospectively analysed for SL between January 2010 and December 2017. The SL group was compared to a control group from the same cohort.

Results

45 out of 1003 transplanted patients developed an SL (incidence 4.5%), on average 50 days after kidney transplantation. SLs developed more in older patients, in those with a PD catheter and in ADKDP as primary diagnosis. Surgical predictors for SLs were venous anastomosis on the external iliac vein, concomitant PD catheter removal, perfusion defects, shorter operating time, splint > 7 days, double J stenting, discharge with drain, low initial drain production and ureteral obstruction. Opening of the peritoneum, re-operation for postoperative bleeding and previous nephrectomy seem protective for developing SL.

Conclusion

We found multiple heterogeneous predictors for SL with a common denominator related to surgical management of the retroperitoneal space, peritoneum and the ureter. Future prospective studies are necessary to evaluate the influence of these variables on the development of SL.

Scintigraphic evaluation of remote pre-conditioning protection against unilateral renal ischemia/reperfusion injury in rats: a longitudinal study

PURPOSE

To determine the role of remote perconditioning (RPeC) on renal function and histology in an animal model of unilateral renal ischemia and reperfusion (IR) injury.

METHODS

Rats were subjected to 60 min unilateral renal ischemia. RPeC protocol was the application of four cycles of 5 min IR of left femoral artery during renal ischemia. Assessments of histological changes and renal function were made 24 h, 1 week, or 3 weeks later. 99mTc-DMSA scan was performed using a small-animals SPECT system.

RESULTS

24-h reperfusion decreased the 99mTc-DMSA uptake in the left kidney compared to the intact kidney of control animals. RPeC group has higher uptake compared to the IR group. After 1 week and 3 weeks, uptakes were gradually increased in both groups and no differences were observed. Severe morphological changes in the ischemic kidneys of both groups were observed after 24 h which attenuated after 1 week and 3 weeks. Moreover, no differences in creatinine and BUN levels between IR-treated and intact animals were observed.

CONCLUSION

These data suggest that RPeC exerts a partially transient improvement in the renal function in the first day after reperfusion. However, long-term follow-up study showed no beneficial effects of RPeC. Moreover, noninvasive 99mTc-DMSA scan revealed a suitable tool in the follow-up evaluation of recovery process in the unilateral renal IR injury models.

Cardiac arrhythmias after renal I/R depend on IL-1β

AIMS

Cardiac arrhythmias are one of the most important remote complications after kidney injury. Renal ischemia reperfusion (I/R) is a major cause of acute renal injury predisposing to several remote dysfunctions, including cardiac electrical disturbance. Since IL-1β production dependent on NLRP3 represents a link between tissue malfunctioning and cardiac arrhythmias, here we tested the hypothesis that longer ventricular repolarization and arrhythmias after renal I/R depend on this innate immunity sensor.

METHODS AND RESULTS

Nlrp3^-/- and Casp1^-/- mice reacted to renal I/R with no increase in plasma IL-1β, different from WT (wild-type) I/R. A prolonged QJ interval and an increased susceptibility to ventricular arrhythmias were found after I/R compared to Sham controls in wild-type mice at 15 days post-perfusion, but not in Nlrp3^-/- or CASP1^-/- I/R, indicating that the absence of NLRP3 or CASP1 totally prevented longer QJ interval after renal I/R. In contrast with WT mice, we found no renal atrophy and no renal dysfunction in Nlrp3^-/- and Casp1^-/- mice after renal I/R. Depletion of macrophages in vivo after I/R and a day before IL-1β peak (at 7 days post-perfusion) totally prevented prolongation of QJ interval, suggesting that macrophages might participate as sensors of tissue injury. Moreover, treatment of I/R-WT mice with IL-1r antagonist (IL-1ra) from 8 to 15 days post perfusion did not interfere with renal function, but reversed QJ prolongation, prevented the increase in susceptibility to ventricular arrhythmias and rescued a close to normal duration and amplitude of calcium transient.

CONCLUSION

Taken together, these results corroborate the hypothesis that IL-1β is produced after sensing renal injury through NRLP3-CASP1, and IL-1β on its turn triggers longer ventricular repolarization and increase susceptibility to cardiac arrhythmias. Still, they offer a therapeutic approach to treat cardiac arrhythmias that arise after renal I/R.

Identification of Candidate Genes Involved in Renal Ischemia/Reperfusion Injury

Renal ischemia/reperfusion injury (IRI) is a main risk factor for the occurrence of delayed graft function or primary graft nonfunction of kidney transplantation. However, it lacks ideal molecular markers for indicating IRI in kidney transplantation. The present study is to explore novel candidate genes involved in renal IRI. Experimental renal IRI mouse models were constructed, and the differentially expressed genes were screened using a microarray assay. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were performed. The expression of genes was detected using real-time qPCR assay. Western blotting and immunohistochemistry staining assays were performed for protein determination. We identified that renal IRI induced the upregulation of SPRR2F, SPRR1A, MMP-10, and long noncoding RNA (lncRNA) Malat1 in kidney tissues for 479.3-, 4.98-, 238.1-, and 3.79-fold, respectively. The expression of miR-139-5p in kidney tissues of IRI-treated mice was decreased to 40.4% compared with the sham-operated mice. These genes are associated with keratinocyte differentiation, regeneration and repair of kidney tissues, extracellular matrix degradation and remodeling, inflammation, and cell proliferation in renal IRI. Identification of novel biomarkers involved in renal IRI may provide evidences for the diagnosis and treatment of renal IRI.