Protective effects of salusin-α and salusin-β on renal ischemia/reperfusion damage and their levels in ischemic acute renal failure

The relationship of salusins with Parkinson's Disease, Alzheimer's Disease, and acute ischemic stroke: A preliminary study

Neuroinflammation, oxidative stress, and apoptosis play important roles in the pathophysiology of Alzheimer's Disease (AD), Parkinson's Disease (PD), and Acute Ischemic Stroke (AIS). Salusin-α and salusin-β peptides, which were shown to be present in many tissues, including the central nervous system, were also shown to be associated with apoptosis, inflammation, and oxidative stress. In the present study, the relationship between Salusin-α and salusin-β peptides and AD, PD, and AIS were investigated. A total of 179 people were included in the present study, including 46 AD, 44 PD, 42 AIS, and 47 controls. Plasma Salusin-α and salusin-β levels were measured with the ELISA Method. The plasma salusin-β levels of AD, PD, and AIS patients were lower than the control group at significant levels (p < 0.05). It was also found that there were correlations between salusin-α and salusin-β levels and age, triglyceride, LDL-c, total cholesterol, and hemoglobin levels. In this study, we found that salusin- β, an endogenous neuropeptide, was associated with AD, PD and AIS. The low level of salusin-β in these diseases in which neuronal damage occurs may be related to the neuroprotective properties of this endogenous peptide. Further studies are needed to fully understand the relationship between salusin-β and the pathophysiology of these diseases.

Downregulation of salusins alleviates hypertrophic cardiomyopathy via attenuating oxidative stress and autophagy

INTRODUCTION

Salusins, which are translated from the alternatively spliced mRNA of torsin family 2 member A (TOR2A), play a vital role in regulation of various cardiovascular diseases. However, it remains unclear precisely regarding their roles in hypertrophic cardiomyopathy (HCM). Therefore, this study was conducted to explore therapeutic effect and the underlying mechanisms of salusins on HCM.

MATERIAL AND METHODS

In vivo experiments, Sprague-Dawley rats were used to induce HCM model by angiotensin (Ang) II infusion for 4 weeks. The rats were randomly divided into four groups, namely, Saline + Control shRNA (n = 7), Ang II + Control shRNA (n = 8), Saline + TOR2A shRNA (n = 7), and Ang II + TOR2A shRNA groups (n = 8). After HCM induction, doppler echocardiography is recommended to evaluate heart function. In vitro experiments, primary neonatal rat cardiomyocytes (NRCMs) and cardiac fibroblasts (NRCFs) were obtained from newborn rats, and were treated with Ang II (10-6 M) for 24 h.

RESULTS

After treatment with Ang II, levels of salusin-α and salusin-β were elevated in serum and cardiac tissues of rats and in the neonatal rat cardiomyocytes and cardiac fibroblasts. Downregulation of salusins alleviated the Ang II-induced cardiac hypertrophy by suppressing the increased atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and beta-myosin heavy chain (β-MHC) and cardiac fibrosis by blocking collagen I, collagen III and transforming growth factor-beta (TGF-β), and it also attenuated oxidative stress by suppressing the increased reactive oxygen species (ROS) and malondialdehyde (MDA) levels and reversing the decreased superoxide dismutase (SOD) activity and autophagy by inhibiting the increased microtubule-associated protein light chain 3B (LC3B), Beclin1, autophagy related gene (Atg) 3 and Atg5 in the cardiac tissues of Ang II-infused rats and in the Ang II-treated NRCMs.

CONCLUSIONS

All these findings suggest that the levels of salusins were elevated in the HCM, and targeting of salusins contributes to alleviation of cardiac hypertrophy and fibrosis probably via attenuating oxidative stress and autophagy. Accordingly, targeting of salusins may be a strategy for HCM therapy.

Serum salusin-α and -β levels in patients with parkinson's disease

BACKGROUND

The etiology of Parkinson's disease (PD) is not well known and there is increasing evidence that oxidative stress also plays an important role in its pathogenesis. Salusins alpha (salusin-α) and beta (salusin-β) affect the central nervous system, vasculature, and kidneys to increase the inflammatory response in endothelial cells, stimulate oxidative stress, and increase monocyte-endothelial adhesion. Neuroinflammation and oxidative stress play roles in the etiopathogenesis of PD.

PURPOSE

To investigate whether salusin-α and -β are related to PD and whether they are correlated with the development of atherosclerosis, body mass index, disease duration, and the Parkinson's Hoehn and Yahr stage.

RESULTS

The low-density lipoprotein cholesterol (LDL-C), total cholesterol, and salusin-β levels were significantly lower and age was significantly higher in Parkinson patients compared to healthy controls (ρ < 0.005). We found a negative linear correlation between salusin-β and the Hoehn and Yahr stage (ρ < 0.001, r = -0.515) in the patients.

CONCLUSIONS

There was a relationship between salusin-β and PD and a correlation between the salusin-β levels and Parkinson's stage. A possible underlying disease mechanism is an increase in oxidative stress and decrease in neuroprotective effects due to low salusin-β levels. Therefore, the effects of salusin-β in treating Parkinson disease should be evaluated. Further studies are needed to understand the effects of salusin-β treatment on preventing or slowing the course of PD.

Protective effect of fatty acid amide hydrolase inhibitor URB597 and monoacylglycerol lipase inhibitor KML29 on renal ischemia-reperfusion injury via toll-like receptor 4/nuclear factor-kappa B pathway

BACKGROUND

Arachidonoyl ethanolamide (anandamide, AEA) and 2-arachidonoylglycerol (2-AG) are the most studies endocannabinoids. AEA and 2-AG are degraded by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) enzymes, respectively. FAAH and MAGL enzymes are widely expressed in many tissues, including kidney. Recent works have depicted that AEA and 2-AG levels are associated with ischemia-reperfusion (IR) injury. In this study, we investigated the effects of MAGL inhibitor KML29 and FAAH inhibitor URB597 against kidney IR injury.

METHODS

The kidneys of the rats underwent ischemia for 45 min and then reperfusion for 24 h. KML29 and URB597 were administered intraperitoneally with kidney IR to two different treatment groups.

RESULTS

IR application increased serum blood urea nitrogen (BUN), creatinine (Cre), interleukin-18 (IL-18), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) levels, while these parameters were decreased following KML29 and URB597 administration. KML29 and URB597 administration also reduced the increased toll-like receptor-4 (TRL-4), phosphorylated-NF-κB, phosphorylated-IκB-α, tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), interleukin-6 (IL-6), caspase-3 levels and histopathological damage in kidney tissue.

CONCLUSIONS

Our results reveal that MAGL inhibitor KML29 and FAAH inhibitor URB597 have a protective effect on kidney IR injury by preventing apoptosis and inflammation. Inhibition of MAGL and FAAH may be a new therapeutic strategy to prevent kidney IR injury.

A New Insight Into Pathophysiological Mechanism of Abdominal Aortic Aneurysm With Novel Parameters Salusin-β and Arterial Stiffness

BACKGROUND

Abdominal aortic aneurysm (AAA) has risk factors similar to those of atherosclerosis. Salusin-β and arterial stiffness are novel parameters that have been shown to predict atherosclerosis and related cardiovascular disorders. However, their predictive value for detecting AAA remains unclear.

METHODS

Forty-eight patients with AAA and 47 age- and sex-matched participants without AAA were enrolled in the study. Arterial stiffness parameters were obtained via an oscillometric Mobil-O-Graph PWA Monitor device (IEM GmbH) with integrated ARCSolver software (Australian Institute of Technology). Plasma salusin-β levels were analyzed using an enzyme-linked immunosorbent assay reagent kit (Abbkine, Inc). The measured salusin-β levels and arterial stiffness parameters of the AAA and control groups were compared.

RESULTS

Salusin-β levels were significantly lower in patients with AAA (P = .014). There was a significant negative correlation between salusin-β levels and abdominal aorta diameter. No significant difference was detected between AAA and control groups in terms of arterial stiffness parameters (P > .05). In backward multiple regression analysis, the presence of AAA, platelet count, and augmentation index were found to be independent predictors of salusin-β levels (P = .006 and P = .023, respectively).

CONCLUSION

Arterial stiffness parameters were not found to be associated with AAA. Contrary to previous results regarding atherosclerosis and related cardiovascular disorders, salusin-β levels were found to be lower in patients with AAA. Although AAA is thought to have similar risk factors as atherosclerosis, the exact pathophysiologic mechanism remains unclear.

Preventive effects of fraxin on ischemia/reperfusion-induced acute kidney injury in rats

AIM

Kidney ischemia reperfusion (IR) injury is an important health problem resulting in acute kidney failure. The oxidative stress and inflammatory process are the underlying mechanisms of IR injury. It has been purposed in this study to research the possible protective effects of fraxin on kidney injury induced by IR.

MATERIAL AND METHODS

32 Sprague Dawley male rats were divided into 4 groups. The groups were organized as follows; sham, IR, IR + fraxin 10 mg/kg, and IR + 50 mg/kg fraxin groups. Some oxidant, antioxidant and inflammatory parameters were evaluated in kidney tissues removed at the end of our experimental study.

KEY FINDINGS

It was detected that the oxidant and proinflammatory markers increased and antioxidant parameters decreased in IR group but the results significantly reversed in treatment groups compared to IR group. And also, 8-OHdG, NF-κB, HAVCR1 immunopositivities were at severe levels and these results attenuated in IR fraxin + 10 mg/kg, and IR + fraxin 50 mg/kg groups.

SIGNIFICANCE

These presented results have shown that fraxin performed protective effects against kidney injury induced by IR.

Salusin-β mediates tubular cell apoptosis in acute kidney injury: Involvement of the PKC/ROS signaling pathway

Salusin-β is abundantly expressed in many organs and tissues including heart, blood vessels, brain and kidneys. Recent studies have identified salusin-β as a bioactive peptide that contributes to various diseases, such as atherosclerosis, hypertension, diabetes and metabolic syndrome. However, the role of salusin-β in the pathogenesis of acute kidney injury (AKI) is largely unclear. In the present study, we investigated the roles of salusin-β in cisplatin or lipopolysaccharide (LPS)-induced renal injury. Herein, we found that salusin-β expression was upregulated in both renal tubular cells and kidney tissues induced by both cisplatin and LPS. In vitro, silencing of salusin-β diminished, whereas overexpression of salusin-β exaggerated the increased PKC phosphorylation, oxidative stress, histone γH2AX expression, p53 activation and apoptosis in either cisplatin or LPS-challenged renal tubular cells. More importantly, salusin-β overexpression-induced tubular cell apoptosis were abolished by using the PKC inhibitor Go 6976, reactive oxygen species (ROS) scavenger NAC, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin (Apo) or p53 inhibitor Pifithrin-α. In animals, blockade of salusin-β alleviated PKC phosphorylation, ROS accumulation, DNA damage, and p53 activation as well as renal dysfunction in mice after administration of cisplatin or LPS. Taken together, these results suggest that overexpressed salusin-β is deleterious in AKI by activation of the PKC/ROS signaling pathway, thereby priming renal tubular cells for apoptosis and death.

Salusin-α mitigates diabetic nephropathy via inhibition of the Akt/mTORC1/p70S6K signaling pathway in diabetic rats

Salusin-α is a bioactive peptide that protects against atherosclerosis and hepatosteatosis. Serum salusin-α level is declined in patients suffering with renal insufficiency. However, it is still undefined whether salusin-α plays a role in diabetic nephropathy. The present study was designed to investigate the potential roles of salusin-α in diabetic renal disease. Herein, we demonstrated that the salusin-α levels in both plasma and kidney tissues from diabetic rats were obviously downregulated. Exogenous administration of salusin-α eliminated the typical characteristics of diabetic nephropathy. Salusin-α treatment decreased renal fibrosis, which was related with reduced epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells. Injection of salusin-α suppressed the production of reactive oxygen species (ROS) via attenuation of NADPH oxidase subunits protein expressions and recovery of the antioxidant system. Mechanistically, the activated Akt/mTORC1/p70S6K signaling pathway in diabetic nephropathy was counteracted by salusin-α treatment. Our results demonstrated that salusin-α exerted protective effect against diabetic nephropathy via reduced oxidative stress and fibrosis, dependent on inactivation of the Akt/mTORC1/p70S6K signaling cascade. Salusin-α may be considered as a promising target for the treatment of diabetic nephropathy.

The protective effect of cannabinoid type 2 receptor activation on renal ischemia-reperfusion injury

Kidney ischemia reperfusion (IR) injury is an important health problem resulting in acute renal failure. After IR, the inflammatory and apoptotic process is triggered. The relation of Cannabinoid type 2 (CB2) receptor with inflammatory and apoptotic process has been determined. The CB2 receptor has been shown to be localized in glomeruli and tubules in human and rat kidney. Activation of CB2 receptor with JWH-133 has been shown to reduce apoptosis and inflammation. In this study, it was investigated whether CB2 activation with selective CB2 receptor agonist JWH-133 was protective against renal IR injury. Male Sprague-Dawley rats were divided into 5 groups (n = 45). Bilateral ischemia was treated to the IR group rat's kidneys for 45 min and then reperfusion was performed for 24 h. Three different doses of JWH-133 (0.2, 1 and 5 mg/kg) were administered to the treatment groups at the onset of ischemia. The JWH-133 application at three different doses decreased the glomerular and tubular damage. Additionally, in the renal tissue, nuclear factor-κB, tumour necrosis factor alpha, interleukin-1beta, and caspase-3 levels decreased immunohistochemically. Similarly, JWH-133 application decreased the serum tumour necrosis factor alpha, blood urea nitrogen, creatinine, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, Cystatin C, interleukin-18, interleukin-1beta, interleukin-6, and interleukin-10 levels. We found that JWH-133 and CB2 receptor activation had a curative effect against kidney IR damage. JWH-133 may be a new therapeutic agent in preventing kidney IR damage.

Protective effect of N-(p-amylcinnamoyl) anthranilic acid, phospholipase A2 enzyme inhibitor, and transient receptor potential melastatin-2 channel blocker against renal ischemia-reperfusion injury

The production of reactive oxygen species and inflammatory events are the underlying mechanisms of ischemia-reperfusion injury (IRI). It was determined that transient receptor potential melastatin-2 (TRPM2) channels and phospholipase A₂ (PLA ₂ ) enzymes were associated with inflammation and cell death. In this study, we investigated the effect of N-( p-amylcinnamoyl) anthranilic acid (ACA), a TRPM2 channel blocker, and PLA ₂ enzyme inhibitor on renal IRI. A total of 36 male Sprague-Dawley rats were divided into four groups: control, ischemia-reperfusion (I/R), I/R + ACA 5 mg, I/R + ACA 25 mg. In I/R applied groups, the ischemia for 45 minutes and reperfusion for 24 hours were applied bilaterally to the kidneys. In the I/R group, serum levels of the blood urea nitrogen (BUN), creatinine, cystatin C (CysC), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and interleukin-18 increased. On histopathological examination of renal tissue in the I/R group, the formation of glomerular and tubular damage was seen, and it was detected that there was an increase in the levels of malondialdehyde (MDA), caspase-3, total oxidant status (TOS), and oxidative stress index (OSI); and there was a decrease in total antioxidant capacity (TAC) and catalase enzyme activity. ACA administration reduced serum levels of BUN, creatinine, CysC, KIM-1, NGAL, interleukin-18. In the renal tissue, ACA administration reduced histopathological damage, levels of caspase-3, MDA, TOS, and OSI; and it increased the level of TAC and catalase enzyme activity. It has been shown with the histological and biochemical results in this study that ACA is protective against renal IRI.

8-Br-cADPR, a TRPM2 ion channel antagonist, inhibits renal ischemia-reperfusion injury

The transient receptor potential melastatin-2 (TRPM2) channel belongs to the transient receptor potential channel superfamily and is a cation channel permeable to Na⁺ and Ca ²⁺ . The TRPM2 ion channel is expressed in the kidney and can be activated by various molecules such as hydrogen peroxide, calcium, and cyclic adenosine diphosphate (ADP)-ribose (cADPR) that are produced during acute kidney injury. In this study, we investigated the role of 8-bromo-cyclic ADP-ribose (8-Br-cADPR; a cADPR antagonist) in renal ischemia-reperfusion injury using biochemical and histopathological parameters. CD38, cADPR, tumor necrosis factor-α, interleukin-1β, and myeloperoxidase (inflammatory markers), urea and creatinine, hydrogen peroxide (oxidant), and catalase (antioxidant enzyme) levels that increase with ischemia-reperfusion injury decreased in the groups treated with 8-Br-cADPR. In addition, renin levels were elevated in the groups treated with 8-Br-cADPR. Histopathological examination revealed that 8-Br-cADPR reduced renal damage and the expression of caspase-3 and TRPM2. Our results suggest that the inhibition of TRPM2 ion channel may be a new treatment modality for ischemic acute kidney injury.

Salusin-α attenuates hepatic steatosis and atherosclerosis in high fat diet-fed low density lipoprotein receptor deficient mice

Salusin-α is an endogenous bioactive peptide and likely to prevent atherosclerosis. But its protective effect against atherosclerosis in vivo remains poorly understood. The aim of the present study was to determine the potential effects of salusin-α on atherosclerosis and its associated metabolic disorders in high fat diet (HFD)-fed low density lipoprotein receptor deficient (LDLr^-/-) mice, and also explore the possible underlying mechanisms involved. Our data showed that after 12 weeks treatment, salusin-α ameliorated HFD-induced weight gain, hyperlipidemia, and serum levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Salusin-α suppressed HFD-induced hepatic steatosis and regulated gene expression of fatty acid synthase, acetyl coenzyme A carboxylase-α, peroxisome proliferator-activated receptor-α, camitine palmitoyltransferase-1α and CYP7A1 in liver. Salusin-α reduced atherosclerotic plaque area and macrophage foam cell formation. Salusin-α prevented hepatic and aortic inflammation as evidenced by the reduced macrophage recruitment and mRNA expression of IL-6 and TNF-α in both liver and aorta. Salusin-α also reduced hepatic and aortic oxidative stress by normalizing activities of antioxidant enzymes in liver and suppressing reactive oxygen species generation and protein expressions of NADPH-oxidase (NOX) 2 and NOX4 in both liver and aorta. Our present data suggest that salusin-α could reduce hepatic steatosis and atherosclerosis via its pleiotropic effects, including amelioration of lipid profiles, regulation of some key molecules involved in lipid metabolism in liver, anti-oxidative effect and anti-inflammatory action.

Nephroprotective Effect of Sonchus oleraceus Extract against Kidney Injury Induced by Ischemia-Reperfusion in Wistar Rats

Introduction

Kidney ischemia-reperfusion (I/R) injury is the main cause of delayed graft function in solid organ transplantation. Sonchus oleraceus is a plant with well-known antioxidant and anti-inflammatory activities; however, its effects on renal I/R are unknown.

Objective

To evaluate whether S. oleraceus extract (S.O.e.) has nephroprotective activity in an I/R model in Wistar rats.

Materials and Methods

Animal groups (n = 6): sham, I/R (45 min/15 h), S.O.e (300 mg/kg p.o.), and S.O.e + I/R (300 mg/kg, p.o.; 45 min/15 h). Renal function, proinflammatory cytokines, alanine aminotransferase, markers of oxidative stress, and histology were evaluated.

Results

None of the mediators evaluated differed significantly between the S.O.e and sham groups. Levels of blood urea nitrogen (BUN), creatinine, malondialdehyde (MDA), and proinflammatory cytokines were higher, and superoxide dismutase (SOD) was lower in the I/R group than in the sham group. Histology showed tubular epithelial necrosis in the medulla and cortex in the I/R group. In the S.O.e + I/R group, S.O.e pretreatment attenuated the I/R-induced increases in BUN, creatinine, MDA, and proinflammatory cytokines induced, SOD was maintained, and histology showed discontinuous necrosis in the medulla but no necrosis in the cortex.

Conclusions

S.O.e was neither hepatotoxic nor nephrotoxic. S.O.e. pretreatment showed a nephroprotective effect against I/R.

Protective effect of salusin-α and salusin-β against ethanol-induced gastric ulcer in rats

BACKGROUND

Alcohol consumption has been found to be associated with gastric ulcers, including gastric mucosal lesions. Salusin-α and salusin-β are bioactive peptides having 28 and 20 amino acids, respectively. Salusin-α and salusin-β immunoreactivity has been detected in the stomach and in the intestines. It has been reported that the salusins regulate the cytokine levels and decrease the infarct area in the heart tissue after ischemia. In this study, we investigated the effects of the salusins in the gastric injury formed with ethanol.

METHODS

Thirty-two sprague Dawley male rats were randomly divided into four groups, including eight rats in each group as follows: Group 1: control; Group 2: ethanol 5 mL/kg; Group 3: ethanol 5 mL/kg+5 nmol/kg salusin-α; Group 4: ethanol 5 mL/kg+5 nmol/kg salusin-β.

RESULTS

The salusin-α level increased at a significant level in the ulcer group formed with ethanol (p<0.001); the change in the salusin-β level is not significant. As for malondialdehyde (p<0.05) and myeloperoxidase (p<0.001), when compared with the control group, tumor necrosis factor-α (p<0.05) levels increased in the group to which ethanol was applied and decreased significantly with the application of salusins. Levels of GSH and IL-1β did not change at a significant level. In addition, histopathologic analysis demonstrated that, in salusin-administered groups, mucosal injury and caspase-3 expressions were reduced.

CONCLUSIONS

The suppression of salusin-α and salusin-β on caspase-3 expression by means of their effects on oxidative injury and TNF-α levels shows that these two hormones could serve as anti-ulcerative agents.