L-carnitine attenuates the development of kidney fibrosis in hypertensive rats by upregulating PPAR-γ

Enhancing radioprotection: exploring the impact of L-carnitine supplementation on the oxidative stress in the liver

BACKGROUND

The adverse effects of radiotherapy (RT) primarily occur through oxidative stress, and attempts are being made to mitigate these effects. L-Carnitine (L-Car) involved in physiological functions, possesses antioxidant and tissue-protective properties. The goal of this investigation is to appraise the radioprotective efficacy of L-Car supplementation.

METHODS AND RESULTS

The groups were established by dividing thirty-two rats as: control, RT (10 Gy), RT + L-Car (200 mg/kg/d), L-Car. Upon completion of the experiment, the livers were harvested for histopathological, immunostaining [tumor necrosis factor-alpha (TNF-α), Caspase-3], spectrophotometric [total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI)], and mRNA expression [(Nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap-1), Heme Oxygenase (HO-1), Transforming growth factor beta 1 (TGF-β1)] analyses. In the damage group, decreased Keap-1, Nrf2, HO-1, and TAS values, along with increased histopathological findings, alanine transferase, aspartate transferase, TNF-α, Caspase-3, TOS, OSI, TGF-β1 levels were found. All findings were improved with L-Car treatment.

CONCLUSIONS

Considering these findings, it can be inferred that L-Car exhibits tissue-protective effects against organ damage predominantly induced by RT-related oxidative stress. Additionally, it has prevented the development of inflammation, apoptosis, and fibrosis. Therefore, L-Car may be considered as a supplement to reduce complications associated with RT.

Causal relationship between serum metabolites and idiopathic pulmonary fibrosis: Insights from a two-sample Mendelian randomization study

Background

Idiopathic pulmonary fibrosis (IPF) is an irreversible lung disease with unclear pathological mechanisms. In this study, we utilized bidirectional Mendelian randomization (MR) to analyze the relationship between serum metabolites and IPF, and conducted metabolic pathway analysis.

Aim

To determine the causal relationship between serum metabolites and IPF using MR analysis.

Methods

A two-sample MR analysis was conducted to evaluate the causal relationship between 824 serum metabolites and IPF. The inverse variance weighted (IVW) method was used to estimate the causal relationship between exposure and results. Sensitivity analysis was conducted using MR Egger, weighted median, and maximum likelihood to eliminate pleiotropy. Additionally, metabolic pathway analysis was conducted to identify potential metabolic pathways.

Results

We identified 12 serum metabolites (6 risks and 6 protective) associated with IPF from 824 metabolites. Among them, 11 were known and 1 was unknown. 1-Eicosatrienoylglycophorophospholine and 1-myristoylglycophorophospholine were bidirectional MR positive factors, with 1-myristoylglycophorophospholine being a risk factor (1.0013, 1.0097) and 1-eicosatrienoylglycophorine being a protective factor (0.9914, 0.9990). The four lipids (1-linoleoylglycerophoethanolamine*, total cholesterol in large high-density lipoprotein [HDL], cholesterol esters in very large HDL, and phospholipids in very large HDL) and one NA metabolite (degree of unsaturation) were included in the known hazardous metabolites. The known protective metabolites included three types of lipids (carnitine, 1-linoleoylglycerophoethanolamine*, and 1-eicosatrienoylglycerophophophorine), one amino acid (hypoxanthine), and two unknown metabolites (the ratio of omega-6 fatty acids to omega-3 fatty acids, and the ratio of photoshopids to total lipids ratio in chylomicrons and extremely large very low-density lipoprotein [VLDL]). Moreover, sn-Glycerol 3-phosphate and 1-Acyl-sn-glycero-3-phosphocline were found to be involved in the pathogenesis of IPF through metabolic pathways such as Glycerolide metabolism and Glycerophospholipid metabolism.

Conclusion

Our study identified 6 causal risks and 6 protective serum metabolites associated with IPF. Additionally, 2 metabolites were found to be involved in the pathogenesis of IPF through metabolic pathways, providing a new perspective for further understanding the metabolic pathway and the pathogenesis of IPF.

Biliary fibrosis is an important but neglected pathological feature in hepatobiliary disorders: from molecular mechanisms to clinical implications

Fibrosis resulting from pathological repair secondary to recurrent or persistent tissue damage often leads to organ failure and mortality. Biliary fibrosis is a crucial but easily neglected pathological feature in hepatobiliary disorders, which may promote the development and progression of benign and malignant biliary diseases through pathological healing mechanisms secondary to biliary tract injuries. Elucidating the etiology and pathogenesis of biliary fibrosis is beneficial to the prevention and treatment of biliary diseases. In this review, we emphasized the importance of biliary fibrosis in cholangiopathies and summarized the clinical manifestations, epidemiology, and aberrant cellular composition involving the biliary ductules, cholangiocytes, immune system, fibroblasts, and the microbiome. We also focused on pivotal signaling pathways and offered insights into ongoing clinical trials and proposing a strategic approach for managing biliary fibrosis-related cholangiopathies. This review will offer a comprehensive perspective on biliary fibrosis and provide an important reference for future mechanism research and innovative therapy to prevent or reverse fibrosis.

Redox-Reversible Near-Infrared Fluorescent Probe for Imaging of Acute Kidney Oxidative Injury and Remedy

Drug-induced acute kidney injury (DIAKI) is associated with high morbidity and mortality. It remains a diagnostic and therapeutic dilemma due to failure of providing unambiguous real-time feedback on nephrotoxicity, which is regarded as a serious problem in clinics. Herein, we report a reversible fluorescence probe, NRN, to monitor the ONOO^-/GSH in an acute kidney injury model. The NRN near-infrared fluorescent probe features a big Stokes shift (83 nm), which was oxidized by ONOO^- and reduced by succussive glutathione (GSH) with excellent selectivity and good sensitivity (detection limit: 418 nM and 0.28 mM, respectively). Taking the reversibility of NRN toward ONOO^- and GSH, real-time evaluations in vivo with cisplatin (CP) alone and CP combined with acetaminophen-stimulated acute kidney injury and the following remedy process with l-carnitine were realized for the first time. The experiments revealed that acute kidney injury caused by combined drugs might be more serious and irreversible under certain conditions. Therefore, NRN could act as a potential tool for understanding oxidative stress-related DIAKI disease processes.

l-carnitine: Nutrition, pathology, and health benefits

Carnitine is a medically needful nutrient that contributes in the production of energy and the metabolism of fatty acids. Bioavailability is higher in vegetarians than in people who eat meat. Deficits in carnitine transporters occur as a result of genetic mutations or in combination with other illnesses such like hepatic or renal disease. Carnitine deficit can arise in diseases such endocrine maladies, cardiomyopathy, diabetes, malnutrition, aging, sepsis, and cirrhosis due to abnormalities in carnitine regulation. The exogenously provided molecule is obviously useful in people with primary carnitine deficits, which can be life-threatening, and also some secondary deficiencies, including such organic acidurias: by eradicating hypotonia, muscle weakness, motor skills, and wasting are all improved l-carnitine (LC) have reported to improve myocardial functionality and metabolism in ischemic heart disease patients, as well as athletic performance in individuals with angina pectoris. Furthermore, although some intriguing data indicates that LC could be useful in a variety of conditions, including carnitine deficiency caused by long-term total parenteral supplementation or chronic hemodialysis, hyperlipidemias, and the prevention of anthracyclines and valproate-induced toxicity, such findings must be viewed with caution.

Parboiled Germinated Brown Rice Improves Cardiac Structure and Gene Expression in Hypertensive Rats

Hypertension leads to oxidative stress, inflammation, and fibrosis. The suppression of these indicators may be one treatment approach. Parboiled germinated brown rice (PGBR), obtained by steaming germinated Jasmine rice, reduces oxidative stress and inflammation in vivo. PGBR contains more bioactive compounds than brown rice (BR) and white rice (WR). Anti-hypertensive benefits of PGBR have been predicted, but research is lacking. The anti-hypertensive effects of PGBR were investigated in the downstream gene network of hypertension pathogenesis, including the renin-angiotensin system, fibrosis, oxidative stress production, and antioxidant enzymes in N-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats. To strengthen our findings, the cardiac structure was also studied. PGBR-exposed rats showed significant reductions in systolic blood pressure (SBP) compared to the hypertensive group. WR did not reduce SBP because of the loss of bioactive compounds during intensive milling. PGBR also reduced the expression of the angiotensin type 1 receptor (AT1R), transforming growth factor-β (TGF-β), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX4), which contribute to the renin-angiotensin system, fibrosis, and oxidative stress production, respectively. Losartan (Los, an anti-hypertensive drug)-treated rats also exhibited similar gene expression, implying that PGBR may reduce hypertension using the same downstream target as Los. Our data also indicated that PGBR reduced cardiac lesions, such as the cardiomyopathy induced by L-NAME. This is the first report on the anti-hypertensive effects of PGBR in vivo by the suppression of the renin response, fibrosis, and improved cardiac structure.

L-Carnitine reduces reactive oxygen species/endoplasmic reticulum stress and maintains mitochondrial function during autophagy-mediated cell apoptosis in perfluorooctanesulfonate-treated renal tubular cells

We previously reported that perfluorooctanesulfonate (PFOS) causes autophagy-induced apoptosis in renal tubular cells (RTCs) through a mechanism dependent on reactive oxygen species (ROS)/extracellular signal-regulated kinase. This study extended our findings and determined the therapeutic potency of l-Carnitine in PFOS-treated RTCs. l-Carnitine (10 mM) reversed the effects of PFOS (100 µM) on autophagy induction and impaired autophagy flux. Furthermore, it downregulated the protein level of p47Phox, which is partly related to PFOS-induced increased cytosolic ROS in RTCs. Moreover, l-Carnitine reduced ROS production in mitochondria and restored PFOS-impeded mitochondrial function, leading to sustained normal adenosine triphosphate synthesis and oxygen consumption and reduced proton leakage in a Seahorse XF stress test. The increased inositol-requiring enzyme 1α expression by PFOS, which indicated endoplasmic reticulum (ER) stress activation, was associated with PFOS-mediated autophagy activation that could be attenuated through 4-phenylbutyrate (5 mM, an ER stress inhibitor) and l-Carnitine pretreatment. Therefore, by reducing the level of IRE1α, l-Carnitine reduced the levels of Beclin and LC3BII, consequently reducing the level of apoptotic biomarkers including Bax and cleaving PARP and caspase 3. Collectively, these results indicate that through the elimination of oxidative stress, extracellular signal–regulated kinase activation, and ER stress, l-Carnitine reduced cell autophagy/apoptosis and concomitantly increased cell viability in RTCs. This study clarified the potential mechanism of PFOS-mediated RTC apoptosis and provided a new strategy for using l-Carnitine to prevent and treat PFOS-induced RTC apoptosis.

Effects of dietary L-carnitine on puberty indices in the young breeder rooster

The aim of current study was to investigate the effect of dietary L-Carnitine (LC) in immature roosters on reproductive hormones, lipid profile and testicular histology at the time of maturity. Eighteen 12-wk-old breeder roosters (Ross 308) of similar weights were randomly allocated into 3 dietary treatments (LC-0: basic diet, LC-250: basic diet + 250 mg LC/kg of diet, LC-500: basic diet + 500 mg of LC/kg of diet) in 6 replicates. The feeding program and photoperiod regimen were performed based on ROSS 308 management handbook. Dietary LC supplementation markedly improved testicle weight and testicle index (p < 0.05). Comb height was also affected by LC supplementation (p < 0.05). The testicle weight and index, comb height, and shank lengths improved linearly with increasing levels of dietary LC (p < 0.05). The LC-250 and LC-500 diets significantly improved the number of sertoli cells (NSC), height epithelium seminiferous tubules (HEST), seminiferous tubules diameter (STD), spermiogenesis index (SI) and tubular differentiation index (TDI) of rooster's testis tissue (p < 0.05). The number of seminiferous tubules (NST) was affected by of the amount of LC (p < 0.05). The roosters on the LC-250 mg/kg diet had longer HEST compared to roosters that received the LC-500 mg/kg diet (p < 0.05). Testicular histology parameters increased in a linear and quadratic manner in response to increasing levels of LC (p < 0.05). Dietary LC significantly increased (p < 0.05) plasma concentrations of testosterone, GnRH, LH, FSH and High-Density Lipoprotein (HDL), but reduced the plasma concentration of Low-Density Lipoprotein (LDL). However, no significant differences were observed between LC-250 and LC-500 groups in these parameters. Plasma testosterone, GnRH, LH, LDL and HDL were affected in a linear and quadratic manner in response to increasing levels of LC (p < 0.05). Similarly, FSH increased linearly with increasing dietary LC (p < 0.05). Thus, adding up to 250g of LC per kg of the rooster chicken can improve reproductive hormones, blood lipids and testicular histology parameters at the time of maturity.

Ameliorative effect of L-carnitine on chronic lead-induced reproductive toxicity in male rats

Lead toxicity is one of the causative agents of male infertility that raised concern from environmental contamination worldwide. L‐carnitine, a biologically active amino acid, present in high concentration in the reproductive organs such as the epididymis, is involved in sperm maturation. The possible protective effect of L‐carnitine in experimentally lead‐induced male reproductive toxicity in rats was evaluated in this study. Thirty adult male Wistar rats were divided into three groups. Group 1: the negative control group was treated with normal saline; Group 2: exposed to 50 mg/kg lead acetate (2% solution in saline); and Group 3: treated with lead acetate 50 mg/kg (2% solution in saline) + L‐carnitine 100 mg/kg. At the end of the experimental period, body and testicular weights were determined, blood samples were withdrawn for hormonal assays of FSH, LH and testosterone. Sperm parameters as sperm count, morphology, viability and motility were measured. Testicular tissue homogenates were prepared for enzymatic assays and for measuring oxidative stress parameters. Lead significantly increased both oxidative stress and the concentration of lactate dehydrogenase‐C in the testicular tissues with a decrease in sperm count, motility and viability. Lead acetate treatment, induced alteration in sperms with normal morphology together with reductions in the serum FSH, LH, testosterone, body and testicular weights. The concentration of 17β‐hydroxysteroid dehydrogenase was significantly reduced. Co‐administration of L‐carnitine significantly reduced testicular oxidative stress, improved sperm parameters, elevated serum FSH, LH and testosterone with an insignificant reduction in the testicular weight. The concentrations of 17β‐hydroxysteroid dehydrogenase and lactate dehydrogenase‐C were significantly improved by L‐carnitine. The overall results indicate that L‐carnitine is expected to improve the lead acetate‐induced male reproductive toxicity.

Active food ingredients production from cold pressed processing residues of Camellia oleifera and Camellia sinensis seeds for regulation of blood pressure and vascular function

Hypertension is one of the most common illnesses worldwide. Accurate control of blood pressure can help reduce the incidence of complications. Nω-nitro-l-arginine methyl ester (l-NAME) is a nitric oxide synthase inhibitor that increases oxidative stress and inflammatory responses, activating the expression of transforming growth factor-beta (TGF-β), which thickens the vessel wall and ultimately contributes to hypertension. Studies have shown that seeds of Camellia oleifera Abel and Camellia sinensis (L). O. Kuntze (Oolong tea) possesses antibacterial, antioxidant, and anti-inflammatory functions. Therefore, this study aimed was to investigate the functional components in the seed pomace ethanol extracts of C. oleifera Abel (CPE) and Oolong tea (OPE) and to evaluate the ameliorative effects of CPE and OPE on oxidative stress, inflammation, and vascular remodeling in l-NAME induced hypertensive C57BL/6J mice. After 8 weeks of treatment, all CPE and OPE dose groups significantly reduced systolic and diastolic blood pressure, by over 30 mmHg and 15 mmHg, respectively. Additionally, CPE and OPE decreased transforming growth factor-beta (TGF-β) expression in the thoracic aortic and thoracic aortic intima-media thickness. Moreover, CPE and OPE decreased the malondialdehyde concentration in the liver by over 33%, as well as levels of tumor necrosis factor-α, interleukin 6, and interleukin-1β in the kidney and heart. Collectively, CPE and OPE can reduce oxidative stress and vascular remodeling, lowering blood pressure, and reducing the risk of cardiovascular disease.

L-carnitine treatment attenuates renal tubulointerstitial fibrosis induced by unilateral ureteral obstruction

BACKGROUND/AIMS

Accumulating evidence indicates that L-carnitine (LC) protects against multiorgan damage through its antioxidant properties and preservation of the mitochondria. Little information is available about the effects of LC on renal fibrosis. This study examined whether LC treatment would provide renoprotection in a rat model of unilateral ureteral obstruction (UUO) and in vitro.

METHODS

Sprague-Dawley rats that underwent UUO were treated daily with LC for 7 or 14 days. The influence of LC on renal injury caused by UUO was evaluated by histopathology, and analysis of gene expression, oxidative stress, mitochondrial function, programmed cell death, and phosphatidylinositol 3-kinase (PI3K)/ AKT/forkhead box protein O 1a (FoxO1a) signaling. In addition, H2O2-exposed human kidney cells (HK-2) were treated with LC.

RESULTS

LC treatment inhibited expression of proinflammatory and profibrotic cytokines, and was followed by a significant attenuation of tubulointerstitial inflammation and fibrosis. The increased oxidative stress caused by UUO was associated with mitochondrial dysfunction and excessive apoptosis and autophagy via PI3K/AKT/FoxO1a-dependent signaling, and this was abrogated by administration of LC. In H2O2-exposed HK-2 cells, LC decreased intracellular production of reactive oxygen species, and suppressed expression of profibrotic cytokines and reduced the number of apoptotic cells.

CONCLUSION

LC protects against the progression of tubulointerstitial fibrosis in an obstructed kidney.

L-Carnitine protects against tacrolimus-induced renal injury by attenuating programmed cell death via PI3K/AKT/PTEN signaling

Reducing immunosuppressant-related complications using conventional drugs is an efficient therapeutic strategy. L-carnitine (LC) has been shown to protect against various types of renal injury. In this study, we investigated the renoprotective effects of LC in a rat model of chronic tacrolimus (TAC) nephropathy. SD rats were injected with TAC (1.5 mg · kg-1 · d-1, sc) for 4 weeks. Renoprotective effects of LC were assessed in terms of renal function, histopathology, oxidative stress, expression of inflammatory and fibrotic cytokines, programmed cell death (pyroptosis, apoptosis, and autophagy), mitochondrial function, and PI3K/AKT/PTEN signaling. Chronic TAC nephropathy was characterized by severe renal dysfunction and typical histological features of chronic nephropathy. At a molecular level, TAC markedly increased the expression of inflammatory and fibrotic cytokines in the kidney, induced oxidative stress, and led to mitochondrial dysfunction and programmed cell death through activation of PI3K/AKT and inhibition of PTEN. Coadministration of LC (200 mg · kg-1 · d-1, ip) caused a prominent improvement in renal function and ameliorated histological changes of kidneys in TAC-treated rats. Furthermore, LC exerted anti-inflammatory and antioxidant effects, prevented mitochondrial dysfunction, and modulated the expression of a series of apoptosis- and autophagy-controlling genes to promote cell survival. Human kidney proximal tubular epithelial cells (HK-2 cells) were treated with TAC (50 μg/mL) in vitro, which induced production of intracellular reactive oxygen species and expression of an array of genes controlling programmed cell death (pyroptosis, apoptosis, and autophagy) through interfering with PI3K/AKT/PTEN signaling. The harmful responses of HK-2 cells to TAC were significantly attenuated by cotreatment with LC and the PI3K inhibitor LY294002 (25 μM). In conclusion, LC treatment protects against chronic TAC nephropathy through interfering the PI3K/AKT/PTEN signaling.

Bixin attenuates carbon tetrachloride induced oxidative stress, inflammation and fibrosis in kidney by regulating the Nrf2/TLR4/MyD88 and PPAR-γ/TGF-β1/Smad3 pathway

Bixin, an natural carotenoid extracted from the seeds of the Bixa orellana has been shown to possess numerous important pharmacological activities. The present study was aimed to investigate the mechanisms of Bixin on carbon tetrachloride (CCl4)-induced kidney inflammation, fibrosis and oxidative stress in mice. Our results showed that Bixin improved renal damage by decreasing the serum levels of creatinine, urea, uric acid and alleviating kidney fibrosis. Bixin ameliorated CCl4-induced inflammation in kidneys by reducing the levels of TNF-α and IL-1β. Bixin suppressed oxidative stress by decreasing the MDA level and increasing the activation of SOD, CAT and GPx. Furthermore, Bixin increased the levels of PPAR-γ, NQO1, HO-1 and the nuclear translocation of Nrf2 in the kidneys of mice. Bixin supplementation inhibited the activation of TLR4, MyD88, NF-κB, TGF-β and Smad3. Thus, this study demonstrated that Bixin possesses anti-oxidant, anti-inflammatory and anti-fibrosis properties through regulating the Nrf2/TLR4/MyD88 and PPAR-γ/TGF-β1/Smad3 pathways.

PPAR γ/TLR4/TGF-β1 axis mediates the protection effect of erythropoietin on cyclosporin A-induced chronic nephropathy in rat

Objective: Nephrotoxicity is the main side effect of cyclosporine A and finding an effective combating method is urgent. The present study investigates the improving effect of erythropoietin (EPO) on cyclosporine A induce renal injury in rats and further explores its possible mechanism.Methods: Recombinant adenovirus for expression of EPO was constructed and injected into kidney with multipoint. Levels of blood urea nitrogen (BUN) and serum creatinine (SCr) were detected by kits. HE staining and Masson's trichrome staining were used to evaluate pathological changes. ELISA was performed to detect the levels of transforming growth factor (TGF)-β1, interleukin (IL)-1β, and IL-6 in serum. Levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in kidney were detected according to manufacturer's instruction. Western blotting was performed to observe the protein expression levels of peroxisome proliferator-activated receptor γ (PPAR γ), Toll-like receptor (TLR) 4, and TGF-β1.Results: Results showed that EPO overexpression in rat kidney could significantly improve renal injury and fibrosis, suppress the release of inflammatory factors and reduce oxidative stress induced by cyclosporine A. Western blotting results showed that EPO overexpression could up-regulate the expression of PPARγ and down-regulate the expression of TLR4 and TGF-β1. Interestingly, when PPARγ activity was inhibited by T0070907, an effective and specific PPARγ inhibitor, the therapeutic effect of EPO was significantly attenuated.Conclusion: Taken together, above results shown the protective effect of EPO on cyclosporine A-induced renal injury and confirmed that EPO's anti-inflammation and antioxidative stress involving the PPAR γ/TLR4/TGFβ1 axis.

Comparison of the Effects of Mesenchymal Stem Cells with Their Extracellular Vesicles on the Treatment of Kidney Damage Induced by Chronic Renal Artery Stenosis

Background

Chronic renal artery stenosis is considered one of the most common causes of renovascular hypertension (RH). Chronic hypoxia can lead to irreversible damage to renal tissue and to a progressive deterioration of renal function. We have previously shown that bone marrow-derived mesenchymal stem cells (BMSCs) improved renal parenchyma and function in a model of RH (2 kidneys, 1 clip model (2K-1C) in rats. Microvesicles (MVs) and exosomes (EXs) released by MSCs have been shown to induce effects similar to those induced by whole cells but with fewer side effects. In this study, we compared the effects of adipose-derived MSCs (ASCs) with those of the MVs and EXs released by ASCs on tissue inflammation and renal function in 2 K-1C rats.

Results

Flow cytometry analysis showed that even after 15 days, ASCs were still detected in both kidneys. The expression of a stem cell homing marker (SDF1-α) was increased in ASC-treated animals in both the stenotic and contralateral kidneys. Interestingly, SDF1-α expression was also increased in MV- and EX-treated animals. A hypoxia marker (HIF1-α) was upregulated in the stenotic kidney, and treatments with ASCs, MVs, and EXs were effective in reducing the expression of this marker. Stenotic animals showed a progressive increase in systolic blood pressure (SBP), while animals treated with ASCs, MVs, and EXs showed a stabilization of SBP, and this stabilization was similar among the different treatments. Stenotic animals developed significant proteinuria, which was reduced by ASCs and MVs but not by EXs. The increased expression of Col I and TGFβ in both kidneys was reduced by all the treatments, and these treatments also effectively increased the expression of the anti-inflammatory cytokine IL-10 in both kidneys; however, only ASCs were able to reduce the overexpression of the proinflammatory cytokine IL-1β in both kidneys of 2K-1C animals.

Conclusion

The results of this study demonstrated that the EVs released by ASCs produced beneficial results but with lower efficacy than whole cells. ASCs produced stronger effects in this model of renal chronic hypoxia, and the use of EVs instead of whole cells should be evaluated depending on the parameter to be corrected.

Targeting peroxisome proliferator-activated receptors: A new strategy for the treatment of cardiac fibrosis

Cardiac fibrosis is a pathogenic factor of many cardiovascular diseases (CVD), which seriously affects people's life, and health and causes huge economic losses. Increasing evidence has shown that peroxisome proliferator-activated receptors (PPARs) can regulate the progression of cardiac fibrosis. For the first time, this review systematically summarizes the literature on cardiac fibrosis from the perspective of PPARs from 2010 to 2020. Moreover, the role of each PPARs in cardiac fibrosis was clarified in this scientific revision from the perspectives of pharmacologically active substances, known agonists, natural extract compounds, and nucleic-acid-based drugs in different CVD models. Furthermore, the combination of multiple PPARs on the treatment of cardiac fibrosis is discussed. This scientific review provides new ideas for targeting PPARs in the treatment of cardiac fibrosis and provides strategies for the development of new, safe, and effective pharmacological antagonists against cardiac fibrosis based on PPAR activity.

Effect of Hibiscus sabdariffa and Zingiber officinale on the antihypertensive activity and pharmacokinetic of losartan in hypertensive rats

The present study aimed to determine the effect of Hibiscus sabdariffa and Zingiber officinale on antihypertensive activity and pharmacokinetic of losartan in hypertensive rats.Hypertension was induced in rats by oral administration of L-NAME (40 mg/kg per day). Pharmacodynamics and pharmacokinetics of losartan were evaluated without and with herbal treatment in hypertensive rats.Treatment of hypertensive rats with investigated herbs substantially reduced systolic blood pressure (SBP), and diastolic blood pressure (DBP) of rats. Treatment of rats (n = 5) with L-NAME plus H. sabdariffa plus losartan and L-NAME plus Z. officinale plus losartan reduced SBP by 16.20% and 14.88% and DBP by 14.82% and 17.52% respectively after 12 h, as compared to L-NAME alone treated rats. In a pharmacokinetic study, the Cmax and AUC0-t of losartan in L-NAME plus H. sabdariffa plus losartan and L-NAME plus Z. officinale plus losartan treated rats was increased by 0.7, 1.99 and 1.51, 3.00 fold respectively in comparison to the Cmax and AUC0-t obtained for L-NAME plus losartan treated group. In conclusion, both the investigated herbs significantly increased the antihypertensive effect and plasma concentration of losartan in L-NAME induced hypertensive rats. The current study predicted that the herb-drug interaction between H. sabdariffa-losartan and Z. officinale-losartan could occur; hence these results in rats may warrant further studies in humans, either in humans or in in vitro human liver microsomes.

Imaging of peroxynitrite in drug-induced acute kidney injury with a near-infrared fluorescence and photoacoustic dual-modal molecular probe

A FRET-based probe for mapping the fluctuation of OONO⁻ in cisplatin-induced acute kidney injury was constructed.

Time Course of the Effects of Buxin Yishen Decoction in Promoting Heart Function and Inhibiting the Progression of Renal Fibrosis in Myocardial Infarction Caused Type 2 Cardiorenal Syndrome Rats

This study aimed to investigate the therapeutic effect of traditional Chinese medicine-Buxin Yishen decoction (BXYS) on type 2 cardiorenal syndrome (CRS) caused by myocardial infarction and explore the possible mechanism BXYS works. A chronic heart failure (CHF) rat model induced by left anterior descending coronary artery ligation was used and five groups were created that included a sham group, a CHF model group, a fosinopril group, a BXYS (0.4 g/kg) group and a BXYS (0.8 g/kg) group. Heart function, renal hemodynamics, neuroendocrine factors, serum, and urine concentration of soluble form connective tissue growth factor (sCTGF), expression of CTGF mRNA, CTGF, α-smooth muscle actin (α-SMA), and low-density lipoprotein receptor-related protein (LRP) in renal tissues were evaluated after 28 days and 60 days of drug administration. Histological analysis of kidney tissues was also performed. In vitro experiments were designed to verify the results of in vivo experiments by detecting factors including CTGF, α-SMA, in NRK-52E cells. Rats with CHF showed obvious pathophysiological changes including: altered renal hemodynamic parameters; dysregulated heart function; changes to serum concentrations of angiotensin II (AngII), cyclic guanosine monophosphate (cGMP), serum creatinine (Scr), blood urea nitrogen (BUN), C-reactive protein (CRP), brain natriuretic peptide (BNP); high serum and urine sCTGF concentration; high CTGF mRNA, CTGF, α-SMA and LRP expression in renal tissues; increased extracellular matrix (ECM) deposition and fibrosis in renal tissues. Treatment of BXYS was correlated with a restoration of heart function and improvement of renal hemodynamics, lower serum and urine sCTGF, lower CTGF mRNA, CTGF, α-SMA and LRP expression in renal tissues and lower ECM deposition. In addition, in vitro experiments showed that treatment with BXYS reduced the α-SMA and LRP concentration in NRK-52E cells, which were similar in vivo experiments. In conclusion, the current study provided evidences that BXYS played a role in improving heart function and delaying the progress of renal fibrosis. Meanwhile, the CTGF-LRP pathway might be one of the therapeutic targets for myocardial infarction caused type 2 CRS which showed a positive change after BXYS treatment and is worthy of further exploration.

Antihypertensive effects of the hydro-ethanol extract of Senecio serratuloides DC in rats

BACKGROUND

Senecio serratuloides DC is used in folk medicine for treating hypertension, skin disorders, internal and external sores, rashes, burns and wounds. This study aimed at investigating the antihypertensive effects of the hydroethanol extract of S. serratuloides (HESS) in N-Nitro-L-arginine methyl ester (L-NAME) induced hypertension in rats.

METHODS

Acute toxicity of HESS was first determined to provide guidance on doses to be used in this study. Lorke's method was used to determine safety of the extract in mice. Female Wistar rats were treated orally once daily with L-NAME (40 mg/kg) for 4 weeks and then concomitantly with L-NAME (20 mg/kg) and plant extract (150 and 300 mg/kg), captopril (20 mg/kg) or saline as per assigned group for 2 weeks followed by a 2-week period of assigned treatments only. Blood pressure was monitored weekly. Lipid profile, nitric oxide, renin and angiotensin II concentrations were determined in serum while mineralocorticoid receptor concentration was quantified in the kidney homogenate. Nitric oxide (NO) concentration was determined in serum and cardiac histology performed.

RESULTS

HESS was found to be non-toxic, having a LD50 greater than 5000 mg/kg. Blood pressure increased progressively in all animals from the second week of L-NAME treatment. HESS treatment significantly and dose-dependently lowered systolic blood pressure (p < 0.001), diastolic blood pressure (p < 0.01), low density lipoprotein cholesterol (p < 0.01) and triglycerides (p < 0.01). It significantly prevented L-NAME induced decrease in serum angiotensin II (p < 0.01), high density lipoprotein cholesterol (p < 0.001) and serum nitric oxide concentrations (p < 0.001). HESS also significantly (p < 0.01) prevented collagen deposition in cardiac tissue.

CONCLUSION

The hydro-ethanol extract of Senecio serratuloides showed antihypertensive, antihyperlipidemic and cardioprotective effects in rats thus confirming its usefulness in traditional antihypertensive therapy and potential for antihypertensive drug development.

Neutral endopeptidase inhibitors blunt kidney fibrosis by reducing myofibroblast formation

Kidney fibrosis is the common pathophysiological mechanism in end-stage renal disease characterized by excessive accumulation of myofibroblast-derived extracellular matrix. Natriuretic peptides have been demonstrated to have cyclic guanosine monophosphate (cGMP)-dependent anti-fibrotic properties likely due to interference with pro-fibrotic tissue growth factor β (TGF-β) signaling. However, in vivo, natriuretic peptides are rapidly degraded by neutral endopeptidases (NEP). In a unilateral ureteral obstruction (UUO) mouse model for kidney fibrosis we assessed the anti-fibrotic effects of SOL1, an orally active compound that inhibits NEP and endothelin-converting enzyme (ECE). Mice (n=10 per group) subjected to UUO were treated for 1 week with either solvent, NEP-/ECE-inhibitor SOL1 (two doses), reference NEP-inhibitor candoxatril or the angiotensin II receptor type 1 (AT₁₎-antagonist losartan. While NEP-inhibitors had no significant effect on blood pressure, they did increase urinary cGMP levels as well as endothelin-1 (ET-1) levels. Immunohistochemical staining revealed a marked decrease in renal collagen (∼55% reduction, P<0.05) and α-smooth muscle actin (α-SMA; ∼40% reduction, P<0.05). Moreover, the number of α-SMA positive cells in the kidneys of SOL1-treated groups inversely correlated with cGMP levels consistent with a NEP-dependent anti-fibrotic effect. To dissect the molecular mechanisms associated with the anti-fibrotic effects of NEP inhibition, we performed a 'deep serial analysis of gene expression (Deep SAGE)' transcriptome and targeted metabolomics analysis of total kidneys of all treatment groups. Pathway analyses linked increased cGMP and ET-1 levels with decreased nuclear receptor signaling (peroxisome proliferator-activated receptor [PPAR] and liver X receptor/retinoid X receptor [LXR/RXR] signaling) and actin cytoskeleton organization. Taken together, although our transcriptome and metabolome data indicate metabolic dysregulation, our data support the therapeutic potential of NEP inhibition in the treatment of kidney fibrosis via cGMP elevation and reduced myofibroblast formation.

Visualization of oxidative injury in the mouse kidney using selective superoxide anion fluorescent probes

Drug-induced acute kidney injury (AKI), caused by renal drug metabolism, has been regarded as a main problem in clinical pharmacology and practice. However, due to the lack of effective biomarkers and noninvasive real-time tools, the early diagnosis of drug-induced AKI is still a crucial challenge. The superoxide anion (O2˙-), the preliminary reactive oxidative species, is closely related to drug-induced AKI. In this paper, we reported two new mitochondria-targeted fluorescent probes for investigating AKI via mapping the fluctuation of O2˙- with high sensitivity and selectivity by the combination of rational design and a probe-screening approach. Small-molecule fluorescent probes (Naph-O2˙- and NIR-O2˙- ) with high accuracy and excellent selectivity were successfully applied to detect endogenously produced O2˙- in living cells and tissues by dual-model confocal imaging, and to trap the fluctuation of the O2˙- level during the drug-induced nephrotoxicity. Moreover, probe NIR-O2˙- was also used to elucidate the protective effects of l-carnitine (LC) against drug-induced nephrotoxicity for the first time. Therefore, these probes may be potential chemical tools for exploring the roles of O2˙- in complex nephrotoxicity disease systems.

Effects of l-Carnitine on the Follicle-Stimulating Hormone, Luteinizing Hormone, Testosterone, and Testicular Tissue Oxidative Stress Levels in Streptozotocin-Induced Diabetic Rats

The present study was designed to investigate the antioxidant property of l-carnitine (LC) on serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (TH) and testis oxidative stress in streptozotocin (STZ)-induced diabetic rats. The rats were divided into the following groups: group I, control; group II, LC 100 mg/kg/d; group III, diabetic; and groups IV to VI, diabetic rats treated with 50, 100, and 200 mg/kg/d of LC, respectively. Daily injections were given intraperitoneally for 7 weeks. At the end of experimental period, after sacrificing the rats, FSH, LH, TH, total antioxidant capacity (TAC), malondialdehyde (MDA), glutathione (GSH), catalase (CAT), mitochondrial function (MTT), protein carbonyl (PC), and reactive oxygen species (ROS) levels were measured. STZ caused an elevation of MDA, ROS, and PC (P < .001) with reduction of GSH, CAT, TAC, and MTT (P < .001) in the serum levels. Group VI had significantly increased FSH, LH, and TH levels versus the untreated diabetic group (P < .001). Although groups V and VI significantly decreased MDA (P < .001), PC (P < .01), and ROS (P < .01) compared with the untreated diabetic group; only in group VI, the activity of GSH (P < .001), CAT (P < .01), TAC (P < .001), and MTT (P < .001) significantly increased. The results of the present study suggest that LC decreased diabetes-induced oxidative stress complications and also improved serum level of FSH, LH, and TH by reducing levels of lipid peroxidation and increasing antioxidant enzymes.

Oxidative Stress and Renal Fibrosis: Recent Insights for the Development of Novel Therapeutic Strategies

Chronic kidney disease (CKD) is a significant worldwide healthcare problem. Regardless of the initial injury, renal fibrosis is the common final pathway leading to end stage renal disease. Although the underlying mechanisms are not fully defined, evidence indicates that besides inflammation, oxidative stress plays a crucial role in the etiology of renal fibrosis. Oxidative stress results from an imbalance between the production of free radicals that are often increased by inflammation and mitochondrial dysfunction, and reduced anti-oxidant defenses. Several studies have demonstrated that oxidative stress may occur secondary to activation of transforming growth factor β1 (TGF-β1) activity, consistent with its role to increase nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) activity. A number of other oxidative stress-related signal pathways have also been identified, such as nuclear factor erythroid-2 related factor 2 (Nrf2), the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-cGMP-dependent protein kinase 1-phosphodiesterase (cGMP-cGK1-PDE) signaling pathway, and the peroxisome proliferator-activated receptor gamma (PPARγ) pathway. Several antioxidant and renoprotective agents, including cysteamine bitartrate, epoxyeicosatrienoic acids (EETs), and cytoglobin (Cygb) have demonstrated ameliorative effects on renal fibrosis in preclinical or clinical studies. The mechanism of action of many traditional Chinese medicines used to treat renal disorders is based on their antioxidant properties, which could form the basis for new therapeutic approaches. This review focuses on the signaling pathways triggered by oxidative stress that lead to renal fibrosis and provides an update on the development of novel anti-oxidant therapies for CKD.

Carnitine induces autophagy and restores high-fat diet-induced mitochondrial dysfunction

OBJECTIVE

Autophagy is suppressed in skeletal muscle and the liver with insulin resistance induced by a high-fat diet. Autophagy is essential for maintaining mitochondrial function, and dysfunctional mitochondria are associated with insulin resistance. As carnitine treatment is well known to improve insulin resistance by promoting mitochondrial function, we investigated if carnitine affects autophagy in the skeletal muscle of a high-fat diet-induced rodent model of obesity.

RESULTS

After 6weeks on a high-fat diet (48kcal% fat), mice developed glucose intolerance, and the gastrocnemius muscle showed a decrease in insulin signaling and mitochondrial function, which was reversed after carnitine (100mg/kg/day) treatment by oral gavage for 2weeks. Swollen mitochondria with destroyed cristae were observed in the skeletal muscle of high-fat diet-fed mice but were not there after carnitine treatment. High-fat diet decreased LC3B-II, a marker of autophagosome formation, and increased sequestosome 1 (SQSTM1), expression of which was reversed after carnitine treatment. In C2C12 myotubes, prolonged treatment with palmitate suppressed autophagy, which was relieved by carnitine treatment. However, the induction of autophagy by carnitine in C2C12 myotubes was not observed after knock-down of peroxisome proliferator-activated receptor γ (PPARγ), which is known to regulate autophagy.

CONCLUSION

We conclude that the removal of dysfunctional mitochondria by induction of autophagy through PPARγ may be a novel mechanism by which carnitine improves insulin resistance and mitochondrial dysfunction in obesity.

Angiotensin II Type 2 Receptor Inhibits Vascular Intimal Proliferation With Activation of PPARγ

BACKGROUND

Angiotensin II type 2 (AT2) receptor stimulation could exert beneficial effects on vascular remodeling. Previously, we reported that AT2 receptor stimulation ameliorated insulin resistance in diabetic mice accompanied by PPARγ activation which also plays a variety of crucial roles in the vasculature. Therefore, this study aimed to investigate the vascular protective effect of the AT2 receptor with activation of PPARγ involving AT2 receptor-interacting protein (ATIP).

METHODS AND RESULTS

Vascular injury was induced by polyethylene-cuff placement around the femoral artery in C57BL/6J mice. Treatment with compound 21 (C21), an AT2 receptor agonist, decreased neointimal formation, cell proliferation, and the mRNA levels of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor (TNF)-α, and interleukin-1β, and phosphorylation of nuclear factor-kappa B, and increased PPARγ DNA-binding activity in the injured artery, whereas these inhibitory effects of C21 were attenuated by co-treatment with a PPARγ antagonist, GW9662. Treatment of vascular smooth muscle cells (VSMC) with C21 prepared from smAT2 transgenic mice, which highly express the AT2 receptor in VSMC, increased both PPARγ activity and its DNA-binding activity determined by dual-luciferase assay and electrophoresis mobility shift assay (EMSA), respectively. We observed that ATIP was involved in PPARγ complex formation, and that transfection of siRNA of ATIP1 attenuated the AT2 receptor-mediated increase in PPARγ activity in VSMC. In response to AT2 receptor stimulation, ATIP was translocated from the plasma membrane to the nucleus.

CONCLUSIONS

Our results suggest a new mechanism by which AT2 receptor stimulation activates PPARγ, thereby resulting in amelioration of vascular intimal proliferation, and that ATIP plays an important role in AT2 receptor-mediated PPARγ activation.

Perfluorooctanesulfonate Mediates Renal Tubular Cell Apoptosis through PPARgamma Inactivation

Perfluorinated chemicals (PFCs) are ubiquitously distributed in the environments including stainless pan-coating, raincoat, fire extinguisher, and semiconductor products. The PPAR family has been shown to contribute to the toxic effects of PFCs in thymus, immune and excretory systems. Herein, we demonstrated that perfluorooctanesulfonate (PFOS) caused cell apoptosis through increasing ratio of Bcl-xS/xL, cytosolic cytochrome C, and caspase 3 activation in renal tubular cells (RTCs). In addition, PFOS increased transcription of inflammatory cytokines (i.e., TNFα, ICAM1, and MCP1) by NFκB activation. Conversely, PFOS reduced the mRNA levels of antioxidative enzymes, such as glutathione peroxidase, catalase, and superoxide dismutase, as a result of reduced PPARγ transactivational activity by using reporter and chromatin immuoprecipitation (ChIP) assays. PFOS reduced the protein interaction between PPARγ and PPARγ coactivator-1 alpha (PGC1α) by PPARγ deacetylation through Sirt1 upregulation, of which the binding of PPARγ and PGC1α to a peroxisome proliferator response element (PPRE) in the promoter regions of these antioxidative enzymes was alleviated in the ChIP assay. Furthermore, Sirt1 also deacetylated p53 and then increased the binding of p53 to Bax, resulting in increased cytosolic cytochrome C. The effect of PPARγ inactivation by PFOS was validated using the PPARγ antagonist GW9662, whereas the adverse effects of PFOS were prevented by PPARγ overexpression and activators, rosiglitozone and L-carnitine, in RTCs. The in vitro finding of protective effect of L-carnitine was substantiated in vivo using Balb/c mice model subjected to PFOS challenge. Altogether, we provide in vivo and in vitro evidence for the protective mechanism of L-carnitine in eliminating PFOS-mediated renal injury, at least partially, through PPARγ activation.

Leptin Induces Oxidative Stress Through Activation of NADPH Oxidase in Renal Tubular Cells: Antioxidant Effect of L-Carnitine

Leptin is a protein involved in the regulation of food intake and in the immune and inflammatory responses, among other functions. Evidences demonstrate that obesity is directly associated with high levels of leptin, suggesting that leptin may directly link obesity with the elevated cardiovascular and renal risk associated with increased body weight. Adverse effects of leptin include oxidative stress mediated by activation of NADPH oxidase. The aim of this study was to evaluate the effect of L-carnitine (LC) in rat renal epithelial cells (NRK-52E) exposed to leptin in order to generate a state of oxidative stress characteristic of obesity. Leptin increased superoxide anion (O2 (•) -) generation from NADPH oxidase (via PI3 K/Akt pathway), NOX2 expression and nitrotyrosine levels. On the other hand, NOX4 expression and hydrogen peroxide (H2 O2 ) levels diminished after leptin treatment. Furthermore, the expression of antioxidant enzymes, catalase, and superoxide dismutase, was altered by leptin, and an increase in the mRNA expression of pro-inflammatory factors was also found in leptin-treated cells. LC restored all changes induced by leptin to those levels found in untreated cells. In conclusion, stimulation of NRK-52E cells with leptin induced a state of oxidative stress and inflammation that could be reversed by preincubation with LC. Interestingly, LC induced an upregulation of NOX4 and restored the release of its product, hydrogen peroxide, which suggests a protective role of NOX4 against leptin-induced renal damage. J. Cell. Biochem. 117: 2281-2288, 2016. © 2016 Wiley Periodicals, Inc.

An integrated lipidomics and metabolomics reveal nephroprotective effect and biochemical mechanism of Rheum officinale in chronic renal failure

Chronic renal failure (CRF) is a major public health problem worldwide. Earlier studies have revealed salutary effects of rhubarb extracts in CRF. In this study, we employed lipidomic and metabolomic approaches to identify the plasma biomarkers and to determine the effect of treatment with petroleum ether, ethyl acetate and n-butanol extracts of rhubarb in a rat model of CRF with adenine-induced chronic tubulointerstitial nephropathy. In addition, clinical biochemistry, histological evaluation and pro-fibrotic protein expression were analyzed. Significant changes were found between the CRF and control groups representing characteristic phenotypes of rats with CRF. Treatment with the three rhubarb extracts improved renal injury and dysfunction, either fully or partially reversed the plasma metabolites abnormalities and attenuated upregulation of pro-fibrotic proteins including TGF-β1, α-SMA, PAI-1, CTGF, FN and collagen-1. The nephroprotective effect of ethyl acetate extract was better than other extracts. The differential metabolites were closely associated with glycerophospholipid, fatty acid and amino acid metabolisms. The results revealed a strong link between renal tubulointerstitial fibrosis and glycerophospholipid metabolism and L-carnitine metabolism in the development of CRF. Amelioration of CRF with the three rhubarb extracts was associated with the delayed development and/or reversal the disorders in key metabolites associated with adenine-induced CRF.

Inflammatory and fibrotic processes are involved in the cardiotoxic effect of sunitinib: Protective role of L-carnitine

Sunitinib (Su) is currently approved for treatment of several malignances. However, along with the benefits of disease stabilization, cardiovascular toxicities have also been increasingly recognized. The aim of this study was to analyze which mechanisms are involved in the cardiotoxicity caused by Su, as well as to explore the potential cardioprotective effects of l-carnitine (LC). To this end, four groups of Wistar rats were used: (1) control; (2) rats treated with 400mg LC/kg/day; (3) rats treated with 25mg Su/kg/day; and (4) rats treated with LC+Su simultaneously. In addition, cultured rat cardiomyocytes were treated with an inhibitor of nuclear factor kappa B (NF-κB), in order to examine the role of this transcription factor in this process. An elevation in the myocardial expression of pro-inflammatory cytokines, together with an increase in the mRNA expression of NF-κB, was observed in Su-treated rats. These results were accompanied by an increase in the expression of pro-fibrotic factors, nitrotyrosine and NOX 2 subunit of NADPH oxidase; and by a decrease in that of collagen degradation factor. Higher blood pressure and heart rate levels were also found in Su-treated rats. All these alterations were inhibited by co-administration of LC. Furthermore, cardiotoxic effects of Su were blocked by NF-κB inhibition. Our results suggest that: (i) inflammatory and fibrotic processes are involved in the cardiac toxicity observed following treatment with Su; (ii) these processes might be mediated by the transcription factor NF-κB; (iii) LC exerts a protective effect against arterial hypertension, cardiac inflammation and fibrosis, which are all observed after Su treatment.

The Role of PPAR Gamma in Systemic Sclerosis

Fibrosis is recognized as an important feature of many chronic diseases, such as systemic sclerosis (SSc), an autoimmune disease of unknown etiology, characterized by immune dysregulation and vascular injury, followed by progressive fibrosis affecting the skin and multiple internal organs. SSc has a poor prognosis because no therapy has been shown to reverse or arrest the progression of fibrosis, representing a major unmet medical need. Recently, antifibrotic effects of PPARγ ligands have been studied in vitro and in vivo and some theories have emerged leading to new insights. Aberrant PPARγ function seems to be implicated in pathological fibrosis in the skin and lungs. This antifibrotic effect is mainly related to the inhibition of TGF-β/Smad signal transduction but other pathways can be involved. This review focused on recent studies that identified PPARγ as an important novel pathway with critical roles in regulating connective tissue homeostasis, with emphasis on skin and lung fibrosis and its role on systemic sclerosis.

Peroxisome proliferator-activated receptor agonists in a battle against the aging kidney

As aging is a complex phenomenon characterized by intraindividual and interindividual diversities in the maintenance of the homeostatic condition of cells and tissues, changes in renal function are not uniform and depend on associated diseases and environmental factors. Multiple studies have investigated the possible underlying mechanisms of age-related decline in kidney function. Evolutionary, molecular, cellular and systemic theories have been postulated to explain the primary disease independent age-related changes and adaptive responses. As peroxisome proliferator-activated receptors (PPARs) are involved in a broad spectrum of biological processes, PPAR activation might have an effect on the prevention of cell senescence. In this review, we will focus on the experimental and clinical evidence of PPAR agonists in a battle against the aging kidney.