Caffeic Acid Phenethyl Ester Reduces Ischemia-Induced Kidney Mitochondrial Injury in Rats

Caffeic acid phenethyl ester restores mitochondrial homeostasis against peritoneal fibrosis induced by peritoneal dialysis through the AMPK/SIRT1 pathway

Increasing evidence suggests that peritoneal fibrosis induced by peritoneal dialysis (PD) is linked to oxidative stress. However, there are currently no effective interventions for peritoneal fibrosis. In the present study, we explored whether adding caffeic acid phenethyl ester (CAPE) to peritoneal dialysis fluid (PDF) improved peritoneal fibrosis caused by PD and explored the molecular mechanism. We established a peritoneal fibrosis model in Sprague-Dawley rats through intraperitoneal injection of PDF and lipopolysaccharide (LPS). Rats in the PD group showed increased peritoneal thickness, submesothelial collagen deposition, and the expression of TGFβ1 and α-SMA. Adding CAPE to PDF significantly inhibited PD-induced submesothelial thickening, reduced TGFβ1 and α-SMA expression, alleviated peritoneal fibrosis, and improved the peritoneal ultrafiltration function. In vitro, peritoneal mesothelial cells (PMCs) treated with PDF showed inhibition of the AMPK/SIRT1 pathway, mitochondrial membrane potential depolarization, overproduction of mitochondrial reactive oxygen species (ROS), decreased ATP synthesis, and induction of mesothelial-mesenchymal transition (MMT). CAPE activated the AMPK/SIRT1 pathway, thereby inhibiting mitochondrial membrane potential depolarization, reducing mitochondrial ROS generation, and maintaining ATP synthesis. However, the beneficial effects of CAPE were counteracted by an AMPK inhibitor and siSIRT1. Our results suggest that CAPE maintains mitochondrial homeostasis by upregulating the AMPK/SIRT1 pathway, which alleviates oxidative stress and MMT, thereby mitigating the damage to the peritoneal structure and function caused by PD. These findings suggest that adding CAPE to PDF may prevent and treat peritoneal fibrosis.

Calcium signaling crosstalk between the endoplasmic reticulum and mitochondria, a new drug development strategies of kidney diseases

Calcium (Ca2+) acts as a second messenger and constitutes a complex and large information exchange system between the endoplasmic reticulum (ER) and mitochondria; this process is involved in various life activities, such as energy metabolism, cell proliferation and apoptosis. Increasing evidence has suggested that alterations in Ca2+ crosstalk between the ER and mitochondria, including alterations in ER and mitochondrial Ca2+ channels and related Ca2+ regulatory proteins, such as sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), inositol 1,4,5-trisphosphate receptor (IP3R), and calnexin (CNX), are closely associated with the development of kidney disease. Therapies targeting intracellular Ca2+ signaling have emerged as an emerging field in the treatment of renal diseases. In this review, we focused on recent advances in Ca2+ signaling, ER and mitochondrial Ca2+ monitoring methods and Ca2+ homeostasis in the development of renal diseases and sought to identify new targets and insights for the treatment of renal diseases by targeting Ca2+ channels or related Ca2+ regulatory proteins.

Natural products for kidney disease treatment: Focus on targeting mitochondrial dysfunction

The patients with kidney diseases are increasing rapidly all over the world. With the rich abundance of mitochondria, kidney is an organ with a high consumption of energy. Hence, renal failure is highly correlated with the breakup of mitochondrial homeostasis. However, the potential drugs targeting mitochondrial dysfunction are still in mystery. The natural products have the superiorities to explore the potential drugs regulating energy metabolism. However, their roles in targeting mitochondrial dysfunction in kidney diseases have not been extensively reviewed. Herein, we reviewed a series of natural products targeting mitochondrial oxidative stress, mitochondrial biogenesis, mitophagy, and mitochondrial dynamics. We found lots of them with great medicinal values in kidney disease. Our review provides a wide prospect for seeking the effective drugs targeting kidney diseases.

The Effect of Polyphenols on Kidney Disease: Targeting Mitochondria

Mitochondrial function, including oxidative phosphorylation (OXPHOS), mitochondrial biogenesis, and mitochondria dynamics, are essential for the maintenance of renal health. Through modulation of mitochondrial function, the kidneys are able to sustain or recover acute kidney injury (AKI), chronic kidney disease (CKD), nephrotoxicity, nephropathy, and ischemia perfusion. Therapeutic improvement in mitochondrial function in the kidneys is related to the regulation of adenosine triphosphate (ATP) production, free radicals scavenging, decline in apoptosis, and inflammation. Dietary antioxidants, notably polyphenols present in fruits, vegetables, and plants, have attracted attention as effective dietary and pharmacological interventions. Considerable evidence shows that polyphenols protect against mitochondrial damage in different experimental models of kidney disease. Mechanistically, polyphenols regulate the mitochondrial redox status, apoptosis, and multiple intercellular signaling pathways. Therefore, this review attempts to focus on the role of polyphenols in the prevention or treatment of kidney disease and explore the molecular mechanisms associated with their pharmacological activity.

Caffeic Acid Phenethyl Ester (CAPE) Improves Boar Sperm Quality and Antioxidant Capacity in Liquid Preservation (17°C) Linked to AMPK Activity Maintenance

Liquid preservation of boar sperm is crucial for artificial insemination application in pig production. However, time-dependent oxidative damage to sperm is one of the major challenges during the liquid preservation period. Caffeic acid phenethyl ester (CAPE) possesses excellent antioxidant properties and has potential therapeutic use in reproductive organ injury linked to oxidative stress. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) involves in modulating the cellular redox state and exerts a beneficial effect on sperm preservation. In the present study, we firstly assessed different concentrations of CAPE that affect sperm quality during liquid storage to determine the appropriate addition. To further investigate whether CAPE exerts protective effects on boar sperm through modulation of AMPK activity, sperm quality parameters, antioxidant capacity, and marker protein expressions were evaluated under co-incubation with H₂O₂. The results showed that sperm treated with 210 μmol/L CAPE exhibited the highest motion parameters (total motility and progressive motility) and best functional integrity (mitochondrial activity, plasma membrane integrity, and acrosomal integrity). Even in the presence of H₂O₂, the addition of 210 μmol/L CAPE not only significantly improved sperm quality parameters, but also elevated CAT, SOD, and GSH-Px activities to enhance sperm antioxidant capacity. In addition, we found that CAPE could affect the protein activities of AMPK, phospho-AMPK α (p-AMPK), SOD, and Caspase-3 regardless of whether H₂O₂ is present or not. Our findings suggested that CAPE has potential application in liquid preservation of boar sperm and preliminary indicated that CAPE-induced improvement of sperm quality and antioxidant capacity should be mediated through conservation of AMPK activity. Further studies are required to illustrate the specific mechanism by which CAPE attenuates oxidative stress-mediated damages dependent on AMPK activity.

Thunbergia laurifolia leaf extract partially recovers lead-induced renotoxicity through modulating the cell signaling pathways

This research investigated the reno-protective effect of Thunbergia laurifolia Linn. (TL) in a lead-induced toxicity test through the modulation of cell signaling pathways. The study carried out to evaluate the effect of TL leaf extracts in Swiss Albino mice exposed to lead acetate (PbAc). Prior to in vivo study, a probable kidney-protective effect of the plant leaf extract was presumed through an activity-specific (PASS) molecular docking analysis. In animal model study, albino mice were divided in seven groups and co-treated with PbAc and TL (100, 200 mg/kgBW) or vitamin E (100 mg/kgBW) for 38 days, whereas the untreated control, TL control, and vehicle control groups received sodium acetate, PbAc, sodium acetate plus mineral oil, respectively. At the end of treatment, blood and kidney tissue were collected for investigating Pb concentration, estimating biochemical profile, evaluating oxidative stress and inflammatory parameters. The histopathological change of kidney along with apoptosis was assessed from kidney sections using H & E staining and TUNEL assay. Pb-exposed mice were found to be increased concentration of Pb in the blood and kidney sample, which further led to increased MDA levels in the plasma, blood, and tissue. Followed by kidney damage, increased expression of TNF-α, iNOS, and COX-2 in kidney tissues were noticed, which were related to elevated TNF-α in the systemic circulation of Pb-treated mice. Co-treatment with TL or vitamin E significantly reduced altered structure and apoptosis of kidney tissues. Downregulation of inflammatory markers especially TNF-α, iNOS, and COX-2 with simultaneous improvement of renal function through reduced plasma BUN and creatinine levels demonstrate that TL act as a potential dietary supplement to detoxify Pb in kidney showing an antioxidant and anti-inflammatory effect.

Metabolomics profiling reveals the mechanism of caffeic acid in extending lifespan in Drosophila melanogaster

Caffeic acid is a phenolic compound widely synthesized by plants, which has shown health benefits for multiple aging-related diseases. The aim of this study was to investigate the life-extending effect of caffeic acid and its underlying mechanisms. The effects of caffeic acid on lifespan, climbing behavior, starvation resistance, and heat sensitivity of Drosophila melanogaster (D. melanogaster) were evaluated. 1H-NMR-based metabolomics and biochemical detection were performed to explore the potential mechanisms. The results demonstrated that supplementation with caffeic acid extended the lifespan, and improved climbing behavior and stress resistance in D. melanogaster. Additionally, continuous supplementation with caffeic acid caused the metabolic profile of 30-day D. melanogaster closer to that of 3-day D. melanogaster, among which 17 differential metabolites were significantly regulated by caffeic acid, involved in amino acid metabolism and mitochondrial metabolism. Furthermore, caffeic acid significantly prevented oxidative damage and improved mitochondrial function. Correlation analysis indicated that the differential metabolites regulated by caffeic acid were correlated with its antioxidant effect and mitochondrial improvement function. In conclusion, our data support that caffeic acid could extend lifespan in D. melanogaster through regulation of metabolic abnormality and improvement of mitochondrial function.

Recent progresses in the pharmacological activities of caffeic acid phenethyl ester

The past decades have seen a growing interest in natural products. Caffeic acid phenethyl ester (CAPE), a flavonoid isolated from honeybee propolis, has shown multiple pharmacological potentials, including anti-cancer, anti-inflammatory, antioxidant, antibacterial, antifungal, and protective effects on nervous systems and multiple organs, since it was found as a potent nuclear factor κB (NF-κB) inhibitor. This review summarizes the advances in these beneficial effects of CAPE, as well as the underlying mechanisms, and proposes that CAPE offers an opportunity for developing therapeutics in multiple diseases. However, clinical trials on CAPE are necessary and encouraged to obtain certain clinically relevant conclusions.

Microvesicles derived from human umbilical cord mesenchyme promote M2 macrophage polarization and ameliorate renal fibrosis following partial nephrectomy via hepatocyte growth factor

The intraoperative ischemia in partial nephrectomy (PN) often leads to postoperative renal function impairment and fibrosis, which can be regulated by macrophage polarization. We have previously demonstrated that microvesicles derived from human Wharton's Jelly mesenchymal stromal cells (hWJMSC-MVs) attenuated renal ischemia-induced renal fibrosis and contained a substantial quantity of hepatocyte growth factor (HGF). Herein, we investigated whether MSC-MVs regulate macrophage polarization and ameliorate renal fibrosis following ischemia-PN via transferring HGF. A rat model of ischemia-PN was established by 45 min of left renal ischemia followed by removal of 1/3 upper left kidney. MSC-MVs were injected through the tail vein immediately after ischemia. Renal injury biomarkers were measured and histologic analysis was performed to analyze renal injury. A co-culture model of THP-1 macrophages and MSC-MVs was utilized. The expression of M1 markers and M2 markers were determined to evaluate macrophage polarization. MSC-MV administration significantly ameliorated renal inflammation, lesions, and fibrosis in ischemia-PN rats, and promoted M2 macrophage polarization both in rat remnant renal tissues and LPS-treated THP-1 cells. These effects of MSC-MVs were compromised when HGF expression was downregulated in MSC-MVs. Collectively, MSC-MVs promote M2 macrophage polarization and attenuate renal fibrosis following ischemia-PN via transferring HGF.

Caffeic Acid Phenethyl Ester Protects Kidney Mitochondria against Ischemia/Reperfusion Induced Injury in an In Vivo Rat Model

To improve ischemia/reperfusion tolerance, a lot of attention has been focused on natural antioxidants. Caffeic acid phenethyl ester (CAPE), an active component of the resinous exudates of the buds and young leaves of Populus nigra L., Baccharis sarothroides A., etc., and of propolis, possesses unique biological activities such as anti-inflammatory, antioxidant, immunomodulating, and cardioprotective effects, among others. There is a lack of studies showing a link between the antioxidant potential of CAPE and the mechanism of protective action of CAPE at the level of mitochondria, which produces the main energy for the basic functions of the cell. In the kidney, ischemia/reperfusion injury contributes to rapid kidney dysfunction and high mortality rates, and the search for biologically active protective compounds remains very actual. Therefore, the aim of this study was to identify the antioxidant potential of CAPE and to investigate whether CAPE can protect rat kidney mitochondria from in vivo kidney ischemia/reperfusion induced injury. We found that CAPE (1) possesses antioxidant activity (the reducing properties of CAPE are more pronounced than its antiradical properties); CAPE effectively reduces cytochrome c; (2) protects glutamate/malate oxidation and Complex I activity; (3) preserves the mitochondrial outer membrane from damage and from the release of cytochrome c; (4) inhibits reactive oxygen species (ROS) generation in the Complex II (SDH) F site; (5) diminishes ischemia/reperfusion-induced LDH release and protects from necrotic cell death; and (6) has no protective effects on succinate oxidation and on Complex II +III activity, but partially protects Complex II (SDH) from ischemia/reperfusion-induced damage. In summary, our study shows that caffeic acid phenethyl ester protects kidney mitochondrial oxidative phosphorylation and decreases ROS generation at Complex II in an in vivo ischemia/reperfusion model, and shows potential as a therapeutic agent for the development of pharmaceutical preparations against oxidative stress-related diseases.

Phenolic Compounds of Propolis Alleviate Lipid Metabolism Disorder

Lipid metabolism disorder is one of the significant risk factors for a multitude of human diseases and has become a serious threat to human health. The present study aimed to evaluate the effects of phenolics from poplar-type propolis on regulating lipid metabolism by using cell models of steatosis induced by palmitic acid (PA). Our study shows that phenolic esters have higher lipid-lowering activities than phenolic acids, especially for three caffeic acid esters, including caffeic acid phenethyl ester (CAPE), caffeic acid cinnamyl ester (CACE), and caffeic acid benzyl ester (CABE). Most notably, CACE presents prominent properties to prevent intracellular lipid accumulation and to amend extracellular adipokine secretion abnormalities. In addition, our results firstly reveal that CACE can alleviate lipid metabolism disorder through mediating protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor 6 (ATF6) signaling pathway-associated protein expression, suppressing endoplasmic reticulum (ER) stress, and activating peroxisome proliferator-activated receptors (PPARs) by distinct upregulation of PPARα and downregulation of PPARγ.

Increased Succinate Accumulation Induces ROS Generation in In Vivo Ischemia/Reperfusion-Affected Rat Kidney Mitochondria

Mitochondria are recognized as main reactive oxygen species (ROS) producers, involving ROS generation by mitochondrial complexes I and III. Lately, the focus has been shifting to the ROS generation by complex II. Contribution of complex II (SDH) to ROS generation still remains debatable, especially in in vivo settings. Moreover, it is not completely defined at what time of ischemia the first alterations in mitochondria and the cell begin, which is especially important with renal arterial clamping in vivo during kidney surgery, as it predicts the postischemic kidney function. The aim of this study on an in vivo rat kidney ischemia/reperfusion model was to determine if there is a connection among (a) duration of kidney ischemia and mitochondrial dysfunction and (b) succinate dehydrogenase activity, succinate accumulation, and ROS generation in mitochondria at low and saturating succinate concentrations. Our results point out that (1) mitochondrial disturbances can occur even after 30 min of kidney ischemia/reperfusion in vivo and increase progressively with the prolonged time of ischemia; (2) accumulation of succinate in cytosol after ischemia/reperfusion correlated with increased H₂O₂ generation mediated by complex II, which was most noticeable with physiological succinate concentrations; and (3) ischemia/reperfusion induced cell necrosis, indicated by the changes in LDH activity. In conclusion, our new findings on the accumulation of succinate in cytosol and changes in SDH activity during kidney ischemia/reperfusion may be important for energy production after reperfusion, when complex I activity is suppressed. On the other hand, an increased activity of succinate dehydrogenase is associated with the increased ROS generation, especially with physiological succinate concentrations. All these observations play an important role in understanding the mechanisms which occur in the early phase of ischemia/reperfusion injury in vivo and may provide new ideas for novel therapeutic approaches or injury prevention; therefore, more detailed studies are necessary in the future.

Evaluation of the Effect of Caffeic Acid Phenethyl Ester (CAPE) on Pharmacological Responses of Isolated Rat Trachea in vitro

BACKGROUND

Caffeic acid phenethyl ester (CAPE) is one of the major components of honeybee propolis and its structure is similar to flavonoids. CAPE has been shown to possess anti-inflammatory, immunomodulatory, and antioxidant properties. Despite a wide range of biological activities of CAPE, detailed biochemical mechanisms of its action are poorly described. The aim of the present study was to investigate the in vitro effect of CAPE on isolated rat trachea.

MATERIALS AND METHODS

A 20 mm long portion of rat tracheal spiral was submerged in 20 ml Krebs solution in an isolated organ bath at 37°C. Changes in tracheal contractility in response to the application of agonist agents were measured using an isometric transducer connected to a Harvard polygraph.

RESULTS

Acetylcholine (ACH), histamine (HIS), and CaCl2 caused the trachea to contract in a dose-dependent manner. Incubation of trachea with 10-7 M and 10-6M of CAPE induced a significant reduction in contraction induced by ACH and HIS. The degree of drug-induced tracheal contraction or relaxation was dose-dependent.

CONCLUSION

The CAPE potential to relax the trachea may antagonize cholinergic and histaminergic receptors of the trachea. The findings provide new insight into the effectiveness of CAPE in the control of asthma and the possible use of propolis for its treatment. The results highlight the anti-muscarinic, anti-histaminic, anti-inflammatory, and relaxant activities of CAPE and critically show its potential therapeutic effects.

Attenuating effects of caffeic acid phenethyl ester and betaine on abamectin-induced hepatotoxicity and nephrotoxicity

Abamectin (ABM) is a widely utilized potent anthelmintic and insecticidal agent. In this study, we investigated the protective effects of caffeic acid phenethyl ester (CAPE) and betaine (BET) against ABM-induced hepatotoxicity and nephrotoxicity in rats. Forty rats were divided into five groups, receiving either oral saline solution (normal control), oral ABM at a dose of 2 mg/kg BW (1/5 LD50), CAPE (10 μmol/kg BW intraperitoneally) followed by ABM, or BET supplementation at a dose of 250 mg/kg BW followed by ABM administration, while group V rats received a combination of i.p. CAPE and oral BET in the same doses before receiving ABM. Biochemical analysis showed that ABM administration significantly (p < 0.05) increased serum levels of aminotransferases, alkaline phosphatase, lactate dehydrogenase, and cholesterol, as well as serum creatinine and urea. Compared to the control group, ABM-intoxicated rats had significantly (p < 0.05) higher tissue concentrations of nitric oxide and malondialdehyde, as well as lower tissue glutathione concentration, total antioxidant capacity, and antioxidant enzymatic activity (glutathione peroxidase, superoxide dismutase, and catalase). Histopathological examination of hepatic and renal tissues of ABM-intoxicated rats showed acute inflammatory and necrotic changes. Pretreatment with CAPE and/or BET reversed the biochemical and histopathological alterations of ABM on the liver and kidneys. Therefore, CAPE and BET (alone or in combination) could be promising protective agents against ABM-induced hepatotoxicity and nephrotoxicity. Future studies should confirm our findings and evaluate the other molecular effects are involved in the combination chemoprotection of CAPE and BET.