Kappa-opioid receptor agonist U50448H protects against renal ischemia-reperfusion injury in rats via activating the PI3K/Akt signaling pathway

rhMYDGF Alleviates I/R-induced Kidney Injury by Inhibiting Inflammation and Apoptosis via the Akt Pathway

BACKGROUND

Renal ischemia/reperfusion (I/R) injury is one of the crucial factors affecting the outcome of renal transplantation. In recent years, myeloid-derived growth factor (MYDGF) has received a lot of attention for its extensive beneficial effects on cardiac repair and protection of cardiomyocytes from cell death. Therefore, we hypothesized that the recombinant human MYDGF (rhMYDGF) protein might play an essential role in safeguarding renal I/R injury.

METHODS

In vivo experiments were conducted using a mouse unilateral I/R model. Mice were pretreated with rhMYDGF by intraperitoneal injection to study the potential mechanism of renal protection. In vitro, we established hypoxia/reoxygenation and H 2 O 2 treatment models to pretreat cells with rhMYDGF. The expression levels of oxidative stress, inflammation, and apoptosis-related factors in tissues and cells were detected. Finally, we explored the role of the protein kinase B (Akt) pathway in the renal protective mechanism of rhMYDGF.

RESULTS

In this study, we found that intraperitoneal injection of 1.25 μg rhMYDGF could significantly improve renal function of I/R mice, and reduce oxidative stress, inflammation, and apoptosis. For the human proximal tubular epithelial cell line and human kidney cell line, pretreatment with 0.3 μg/mL rhMYDGF for 24 h significantly downregulated oxidative stress, inflammation, and apoptosis via the phosphorylation of Akt, which could be ameliorated by LY294002.

CONCLUSIONS

rhMYDGF protects kidney from I/R injury by attenuating oxidative stress, inflammation, and apoptosis through the activation of the Akt pathway.

Role of tRNA derived fragments in renal ischemia-reperfusion injury

Background

Ischemia–reperfusion injury (IRI) is one of the major causes of acute kidney injury (AKI). tRNA derived fragments (tRFs/tiRNAs) are groups of small noncoding RNAs derived from tRNAs. To date, the role of tRFs/tiRNAs in renal IRI has not been reported. Herein, we aimed to investigate the involvement of tRFs/tiRNAs in the occurrence and development of ischemia–reperfusion-induced AKI.

Methods

Moderate/severe renal IRI mouse models were established by bilateral renal pedicle clamping. The tRF/tiRNA profiles of healthy controls and moderate/severe IRI-stressed kidney tissues were sequenced by Illumina NextSeq 500. Candidate differentially expressed tiRNAs were further verified by RT-qPCR. Biological analysis was also performed.

Results

Overall, 152 tRFs/tiRNAs were differentially expressed in the moderate ischemic injury group compared with the normal control group (FC > 2, p < 0.05), of which 47 were upregulated and 105 were downregulated; in the severe ischemic injury group, 285 tRFs/tiRNAs were differentially expressed (FC > 2, p < 0.05), of which 157 were upregulated, and 128 were downregulated. RT-qPCR determination of eight abundantly expressed tiRNAs was consistent with the sequencing results. Gene Ontology analysis for target genes of the tRFs/tiRNAs showed that the most enriched cell components, molecular functions and biological processes were Golgi apparatus, cytoplasmic vesicles, protein binding, cellular protein localization and multicellular organism development. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that these target genes were mainly involved in the natural killer cell mediated cytotoxicity pathway, citrate cycle, and regulation of actin cytoskeleton signaling pathway.

Conclusion

Our results indicated that tRFs/tiRNAs were involved in renal IRI. These tRFs/tiRNAs may be effective partly via regulation of renal immunity, inflammation and metabolism processes. Candidate genes, including tiRNA-Gly-GCC-003, tiRNA-Lys-CTT-003, and tiRNA-His-GTG-002, might be potential biomarkers and therapeutic targets of ischemia–reperfusion injury-induced acute kidney injury.

Curcumin Protects against Renal Ischemia/Reperfusion Injury by Regulating Oxidative Stress and Inflammatory Response

Objective

The aim of this study was to explore the pharmacological effects of curcumin on oxidative stress and inflammatory response of renal dysfunction induced by renal ischemia/reperfusion (RIRI).

Methods

Fifty male SD rats (Sprague Dawley) were randomly divided into the sham group, RIRI group, and curcumin group (low, medium, and high). The RIRI model was established by clipping the left renal artery for 45 min and then reperfusion for 24 h and resection of the contralateral kidney. In the curcumin group, curcumin was intraperitoneally injected once a day for 3 consecutive days using different dosage regimens. The RIRI group was intraperitoneally administered with normal saline. Renal injury was evaluated by measuring the concentration of creatinine (Cr) and urea nitrogen (BUN) in serum. Oxidative stress was assessed by assessing the level of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH), and iron reduction/antioxidant capacity (FRAP) in tissues. In addition, the protective effect of RIRI was investigated by measuring Paller scores, the level of serum inflammatory factors and caspase-3, and the number of apoptotic cells.

Results

Ischemia/reperfusion resulted in increased levels of Cr and BUN in serum and MDA in tissues and decreased levels of SOD, CAT, GPx, GSH, and FRAP. Curcumin pretreatment strikingly increased the level of SOD, CAT, GPx, GSH, IL-10, IFN-γ, and FRAP and significantly decreased MDA, Cr, BUN, IL-8, TNF-α, IL-6, and myeloperoxidase (MPO) expressions in tissues.

Conclusion

Curcumin can relieve the degree of renal injury and improve renal function in ischemia-reperfusion, which may be related to the fact that curcumin can increase SOD content in serum and reduce MDA and FRAP levels in the rat model.

The expression of kappa-opioid receptor promotes the migration of breast cancer cells in vitro

Background

Opioid receptors are implicated in cell proliferation and cancer migration. However, the effects and underlying mechanisms of opioid receptor κ (OPRK1) in breast cancer remain unknown.

Methods

Small interfering RNA (siRNAs) was used to knockdown the expression of OPRK1. Western blot was used to determine the protein expression and reverse transcription-quantitative PCR (RT-qPCR) determined the genes transcription. Cell viability was detected by MTT assay and cell death rates were determined by Annexin V/PI and flow cytometry. Cell migration and invasion were detected by wound healing analysis and transwell assay, respectively.

Results

Our research demonstrated that OPRK1 was overexpressed in breast cancer cells compared with the normal human mammary epithelial cells. OPRK1 knockdown could inhibited cell viability and migration in cancer cells, accompanied with the decreased proteins and genes expression of N-cadherin, Snail, MMP2 and Vimentin, while the E-cadherin expression was increased. Additionally, OPRK1 knockdown also promoted PI3K/AKT signaling inactivation. Activation of AKT reversed the OPRK1 knockdown-induced cell viability inhibition and migration suppression, while inhibition of AKT reduced cell viability and promoted cell death.

Conclusions

Our findings illustrated the role of OPRK1 played on promoting migration in vitro, and we also provided the therapeutic research of OPRK1 knockdown combined with AKT inhibition.

Opioids and Acute Kidney Injury

Summary: Opioid use and misuse in the United States has been at epidemic proportions and is predicted to increase further in the setting of the Coronavirus disease 19 pandemic. Acute kidney injury is a condition associated with significant morbidity and increased mortality. We review the literature on the effect of opioids on kidney function and critically examine the association between opioid use and acute kidney injury and identify at-risk populations in whom opioids should be used with caution. We also discuss the role of biomarkers in elucidating this condition and propose preventive measures, novel therapeutic options, and research directions.

Akt1 is involved in tubular apoptosis and inflammatory response during renal ischemia-reperfusion injury

Renal ischemia-reperfusion injury (IRI) is one of the major causes of acute kidney injury (AKI). Although Akt is involved in renal IRI, it is unclear as to which Akt isoform plays an important role in renal IRI. In this study, we investigated the role of Akt1 in renal IRI. We subjected the C57BL/6 male mice to unilateral IRI with contralateral nephrectomy. Two days after IRI, IRI-kidneys were harvested. The mice were divided into four groups: wild type (WT) IRI, Akt1^-/- IRI, WT sham, and Akt1^-/- sham. We found that Akt1, not Akt2 or Akt3, was markedly activated in WT IRI than in WT sham mice. The histologic damage score and serum creatinine level significantly increased in WT IRI mice, the increase being the highest in Akt1^-/- IRI mice. The number of TdT-mediated dUTP nick-end labeling (TUNEL)-positive tubular cells and expression of cleaved caspase-3/Bax were higher in Akt1^-/- IRI mice than in WT IRI mice. The expression of Bcl-2 was lower in Akt1^-/- IRI mice than in WT IRI mice. The expression of tumor necrosis factor-α/interleukin-6/interleukin-1β and number of F4/80-positive macrophages were markedly higher in Akt1^-/- IRI than in WT IRI mice. The expression of phosphorylated nuclear factor-κB p65 was also higher in Akt1^-/- IRI mice than in WT IRI mice. Our results show that Akt1 deletion exacerbates kidney damage as it increases tubular apoptosis and inflammatory response during renal IRI. Akt1 could be a potential therapeutic target for developing treatments against IRI-induced AKI.

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.

Opioid Preconditioning Modulates Repair Responses to Prevent Renal Ischemia-Reperfusion Injury

Progression to renal damage by ischemia-reperfusion injury (IRI) is the result of the dysregulation of various tissue damage repair mechanisms. Anesthetic preconditioning with opioids has been shown to be beneficial in myocardial IRI models. Our main objective was to analyze the influence of pharmacological preconditioning with opioids in renal function and expression of molecules involved in tissue repair and angiogenesis. Experimental protocol includes male rats with 45 min ischemia occluding the left renal hilum followed by 24 h of reperfusion with or without 60 min preconditioning with morphine/fentanyl. We analyzed serum creatinine and renal KIM-1 expression. We measured circulating and intrarenal VEGF. Immunohistochemistry for HIF-1 and Cathepsin D (CTD) and real-time PCR for angiogenic genes HIF-1α, VEGF, VEGF Receptor 2 (VEGF-R2), CTD, CD31 and IL-6 were performed. These molecules are considered important effectors of tissue repair responses mediated by the development of new blood vessels. We observed a decrease in acute renal injury mediated by pharmacological preconditioning with opioids. Renal function in opioid preconditioning groups was like in the sham control group. Both anesthetics modulated the expression of HIF-1, VEGF, VEGF-R2 and CD31. Preconditioning negatively regulated CTD. Opioid preconditioning decreased injury through modulation of angiogenic molecule expression. These are factors to consider when establishing strategies in pathophysiological and surgical processes.

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

κ-opioid receptor agonists may alleviate intestinal damage in cardiopulmonary bypass rats by inhibiting the NF-κB/HIF-1α pathway

The aims of the present study were to investigate the protective effect of a κ-opioid receptor (KOR) agonist on intestinal barrier dysfunction in rats during cardiopulmonary bypass (CPB), as well as to examine the role of NF-κB and the transcription factor hypoxia-inducible factor-1α (HIF-1α) signaling pathway in the regulatory mechanism. A total of 50 rats were randomly divided into five groups, with 10 rats in each group: Sham surgery group (group Sham), CPB surgery group (group CPB), KOR agonist + CPB (group K), KOR agonist + specific KOR antagonist + CBP (group NK) and KOR agonist + NF-κB pathway specific inhibitor + CPB (group NF). Intestinal microcirculation was evaluated to determine intestinal barrier dysfunction in rats following CPB surgery. Hematoxylin and eosin (H&E) staining was used to observe intestinal tissue injury in the rats. ELISA was used to detect the inflammatory factors interleukin (IL)-1β, IL-6, IL10 and tumor necrosis factor-α, and the oxidative stress factors superoxidase dismutase, malondialdehyde and nitric oxide in serum. In addition, ELISA was used to investigate the serum levels of the intestinal damage markers D-lactic acid, diamine oxidase and intestinal fatty acid-binding protein. Western blotting was used to investigate the protein expression levels of tight junction proteins zonula occludens-1 and claudin-1. Furthermore, immunohistochemistry was used to examine intestinal injuries and western blotting was used to detect expression levels of NF-κB/HIF-1α signaling pathway-related proteins. H&E staining results suggested that the KOR agonist alleviated intestinal damage in the CPB model rats. This effect was reversed by the addition of a KOR antagonist. Further investigation of inflammatory and oxidative stress factors using ELISA revealed that the KOR agonist reduced the inflammatory and oxidative stress responses in the intestinal tissues of the CPB model rats. The ELISA results of intestinal damage markers and western blotting results of tight junction protein expression suggested that KOR agonist treatment may alleviate intestinal injury in CPB model rats. In addition, the western blotting and immunohistochemistry results suggested that KOR agonists may decrease the expression levels of NF-κB, p65 and HIF-1α in CPB. Collectively, the present results suggested that KOR agonists are able to ameliorate the intestinal barrier dysfunction in rats undergoing CPB by inhibiting the expression levels of NF-κB/HIF-1α signaling pathway-related proteins.

Opioids Preconditioning Upon Renal Function and Ischemia-Reperfusion Injury: A Narrative Review

Kidneys have an important role in regulating water volume, blood pressure, secretion of hormones and acid-base and electrolyte balance. Kidney dysfunction derived from acute injury can, under certain conditions, progress to chronic kidney disease. In the late stages of kidney disease, treatment is limited to replacement therapy: Dialysis and transplantation. After renal transplant, grafts suffer from activation of immune cells and generation of oxidant molecules. Anesthetic preconditioning has emerged as a promising strategy to ameliorate ischemia reperfusion injury. This review compiles some significant aspects of renal physiology and discusses current understanding of the effects of anesthetic preconditioning upon renal function and ischemia reperfusion injury, focusing on opioids and its properties ameliorating renal injury. According to the available evidence, opioid preconditioning appears to reduce inflammation and reactive oxygen species generation after ischemia reperfusion. Therefore, opioid preconditioning represents a promising strategy to reduce renal ischemia reperfusion injury and, its application on current clinical practice could be beneficial in events such as acute renal injury and kidney transplantation.

Prediction of putative small molecules for manipulation of enriched signalling pathways in hESC-derived early cardiovascular progenitors by bioinformatics analysis

Human pluripotent stem cell-derived cardiovascular progenitor cells (CPCs) are considered as powerful tools for cardiac regenerative medicine and developmental study. Mesoderm posterior1⁺ (MESP1⁺ ) cells are identified as the earliest CPCs from which almost all cardiac cell types are generated. Molecular insights to the transcriptional regulatory factors of early CPCs are required to control cell fate decisions. Herein, the microarray data set of human embryonic stem cells (hESCs)-derived MESP1⁺ cells was analysed and differentially expressed genes (DEGs) were identified in comparison to undifferentiated hESCs and MESP1-negative cells. Then, gene ontology and pathway enrichment analysis of DEGs were carried out with the subsequent prediction of putative regulatory small molecules for modulation of CPC fate. Some key signalling cascades of cardiogenesis including Hippo, Wnt, transforming growth factor-β, and PI3K/Akt were highlighted in MESP1⁺ cells. The transcriptional regulatory network of MESP1⁺ cells were visualised through interaction networks of DEGs. Additionally, 35 promising chemicals were predicted based on correlations with gene expression signature of MESP1⁺ cells for effective in vitro CPC manipulation. Studying the transcriptional profile of MESP1⁺ cells resulted into the identification of important signalling pathways and chemicals which could be introduced as powerful tools to manage proliferation and differentiation of hESC-derived CPCs more efficiently.

G protein-coupled estrogen receptor activation improves contractile and diastolic functions in rat renal interlobular artery to protect against renal ischemia reperfusion injury

OBJECTIVE

This work aimed to investigate whether G protein-coupled estrogen receptor (GPER) can improve the renal interlobular artery vascular function by increasing the NO content, thereby protecting against renal ischemia-reperfusion (IR) injury.

METHODS

This study classified ovariectomised (OVX) female Sprague-Dawley rats into OVX, OVX + IR, OVX + IR + G1 (the GPER agonist G1), OVX + IR + G1+G15 (GPER blocker) and OVX + IR + G1+L-NAME (eNOS blocker) groups. Enzyme-linked immunosorbent assay was performed to detect the estrogen levels in the body and eliminate interference from endogenous estrogens. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) and HE staining, renal function test and Paller scoring were performed to identify the successful model and detect the degree of renal and renal interlobular arteries injury. The in vitro microvascular pressure diameter measurement technique was used to detect the contraction and diastolic activities of the renal interlobular arteries in each group. Immunofluorescence technique was used to observe the localisation and expression levels of GPER and eNOS in renal interlobular arteries. The GPER and eNOS protein expression levels in each group were detected by Western blot. The NO content in the serum of each group was detected by the nitrate reductase method.

RESULT

After OVX, the estrogen level in the body decreased significantly (P < 0.01), and TUNEL staining showed a significant increase in the degree of renal tubular epithelial cell apoptosis in the IR group. Serum creatinine (SCr) and blood urea nitrogen (BUN) levels were significantly increased in the IR group (P < 0.01), and the Paller score showed significantly increased kidney damage. When performing drug treatment, the G1 intervention group significantly decreased serum BUN and SCr levels after IR injury (P < 0.01). The Paller score showed significantly decreased the degree of renal injury (P < 0.01). After IR, the renal interlobular artery contraction rate and systolic velocity of blood vessels were significantly decreased (P < 0.01). The G1 intervention group significantly restored contraction rate and systolic velocity of blood vessels (P < 0.01), and G15 and L-NAME partially reversed this effect (P < 0.01). Immunofluorescence technique showed that GPER was expressed in renal interlobular artery smooth muscle and endothelial cells. After IR injury, the GPER protein expression increased, and the eNOS protein expression decreased significantly (P < 0.01). Western blot showed that after IR injury, the GPER protein expression increased, and the eNOS protein expression decreased significantly. After G1 intervention, the GPER content did not change, and the eNOS content increased significantly (P < 0.01). After ischemia and reperfusion, the serum NO content decreased significantly, but it increased after G1 intervention. G15 and L-NAME reversed the effects of G1 to varying degrees (both at P < 0.01).

CONCLUSION

GPER may improve the renal interlobular artery vascular function by increasing the NO content, thereby protecting against renal IR injury.