Polyphenolic Extract as an Antioxidant to Prevent Kidney Injury in Metabolic Syndrome Rats

The protective effect of Bergamot Polyphenolic Fraction on reno-cardiac damage induced by DOCA-salt and unilateral renal artery ligation in rats

To date, the complex pathological interactions between renal and cardiovascular systems represent a real global epidemic in both developed and developing countries. In this context, renovascular hypertension (RVH) remains among the most prevalent, but also potentially reversible, risk factor for numerous reno-cardiac diseases in humans and pets. Here, we investigated the anti-inflammatory and reno-cardiac protective effects of a polyphenol-rich fraction of bergamot (BPF) in an experimental model of hypertension induced by unilateral renal artery ligation. Adult male Wistar rats underwent unilateral renal artery ligation and treatment with deoxycorticosterone acetate (DOCA) (20 mg/kg, s.c.), twice a week for a period of 4 weeks, and 1% sodium chloride (NaCl) water (n = 10). A subgroup of hypertensive rats received BPF (100 mg/kg/day for 28 consecutive days, n = 10) by gavage. Another group of animals was treated with a sub-cutaneous injection of vehicle (that served as control, n = 8). Unilateral renal artery ligation followed by treatment with DOCA and 1% NaCl water resulted in a significant increase in mean arterial blood pressure (MAP; p< 0.05. vs CTRL) which strongly increased the resistive index (RI; p<0.05 vs CTRL) of contralateral renal artery flow and kidney volume after 4 weeks (p<0.001 vs CTRL). Renal dysfunction also led to a dysfunction of cardiac tissue strain associated with overt dyssynchrony in cardiac wall motion when compared to CTRL group, as shown by the increased time-to-peak (T2P; p<0.05) and the decreased whole peak capacity (Pk; p<0.01) in displacement and strain rate (p<0.05, respectively) in longitudinal motion. Consequently, the hearts of RAL DOCA-Salt rats showed a larger time delay between the fastest and the lowest region (Maximum Opposite Wall Delay-MOWD) when compared to CTRL group (p<0.05 in displacement and p <0.01 in strain rate). Furthermore, a significant increase in the levels of the circulating pro-inflammatory cytokines and chemokines (p< 0.05 for IL-12(40), p< 0.01 for GM-CSF, KC, IL-13, and TNF- α) and in the NGAL expression of the ligated kidney (p< 0.001) was observed compared to CTRL group. Interestingly, this pathological condition is prevented by BPF treatment. In particular, BPF treatment prevents the increase of blood pressure in RAL DOCA-Salt rats (p< 0.05) and exerts a protective effect on the volume of the contralateral kidney (p <0.01). Moreover, BPF ameliorates cardiac tissue strain dysfunction by increasing Pk in displacement (p <0.01) and reducing the T2P in strain rate motion (p<0.05). These latter effects significantly improve MOWD (p <0.05) preventing the overt dyssynchrony in cardiac wall motion. Finally, the reno-cardiac protective effect of BPF was associated with a significant reduction in serum level of some pro-inflammatory cytokines and chemokines (p<0.05 for KC and IL-12(40), p<0.01 for GM-CSF, IL-13, and TNF- α) restoring physiological levels of renal neutrophil gelatinase-associated lipocalin (NGAL, p<0.05) protein of the tethered kidney. In conclusion, the present results show, for the first time, that BPF promotes an efficient renovascular protection preventing the progression of inflammation and reno-cardiac damage. Overall, these data point to a potential clinical and veterinary role of dietary supplementation with the polyphenol-rich fraction of citrus bergamot in counteracting hypertension-induced reno-cardiac syndrome.

Mitoquinone Alleviates Donation after Cardiac Death Kidney Injury during Hypothermic Machine Perfusion in Rat Model

Transplanted organs are subjected to harmful conditions through stopping blood flow, hypothermic storage of the graft, and subsequent reperfusion. In particular, kidneys donated from patients after cardiac arrest (DCD) are classified as more vulnerable to ischemia-reperfusion injury (IRI). Hypothermic machine perfusion is proposed as a solution for better kidney storage before transplantation, and it is a good platform for additional graft treatment. Antioxidants have gained interest in regenerative medicine due to their ability to scavenge reactive oxygen species (ROS), which play a key role in IRI. We evaluated the effect of Mitoquinone (MitoQ), a strong mitochondria-targeted antioxidant, administered directly to the perfusing buffer. Rat kidneys were isolated, randomly classified into one of the following groups, donation after brainstem death (DBD), DCD, and DCD with MitoQ, and perfused for 22 hours with a hypothermic machine perfusion system. Subsequently, we detected levels of kidney injury (KIM-1) and oxidative stress (ROS/RNS, cytochrome C oxidase, and mitochondrial integrity) markers. We compared the activation of the apoptosis pathway (caspase 3 and 9), the concentration of phosphorylated Akt (pAkt), and the pAkt/total Akt ratio. MitoQ reduces KIM-1 concentration, total ROS/RNS, and the level of caspases. We observed a decrease in pAkt and the pAkt/total Akt ratio after drug administration. The length of warm ischemia time negatively impacts the graft condition. However, MitoQ added to the perfusing system as an 'on pump' therapy mitigates injury to the kidney before transplantation by inhibiting apoptosis and reducing ROS/RNS levels. We propose MitoQ as a potential drug for DCD graft preconditioning.

Insights into Repeated Renal Injury Using RNA-Seq with Two New RPTEC Cell Lines

Renal proximal tubule epithelial cells (RPTECs) are a primary site for kidney injury. We created two RPTEC lines from CD-1 mice immortalized with hTERT (human telomerase reverse transcriptase) or SV40 LgT antigen (Simian Virus 40 Large T antigen). Our hypothesis was that low-level, repeated exposure to subcytotoxic levels of 0.25-2.5 μM cisplatin (CisPt) or 12.5-100 μM aflatoxin B1 (AFB1) would activate distinctive genes and pathways in these two differently immortalized cell lines. RNA-seq showed only LgT cells responded to AFB1 with 1139 differentially expressed genes (DEGs) at 72 h. The data suggested that AFB1 had direct nephrotoxic properties on the LgT cells. However, both the cell lines responded to 2.5 μM CisPt from 3 to 96 h expressing 2000-5000 total DEGs. For CisPt, the findings indicated a coordinated transcriptional program of injury signals and repair from the expression of immune receptors with cytokine and chemokine secretion for leukocyte recruitment; robust expression of synaptic and substrate adhesion molecules (SAMs) facilitating the expression of neural and hormonal receptors, ion channels/transporters, and trophic factors; and the expression of nephrogenesis transcription factors. Pathway analysis supported the concept of a renal repair transcriptome. In summary, these cell lines provide in vitro models for the improved understanding of repeated renal injury and repair mechanisms. High-throughput screening against toxicant libraries should provide a wider perspective of their capabilities in nephrotoxicity.

Punicalagin relieves lipotoxic injuries on pancreatic β-cells via regulating the oxidative stress and endoplasmic reticulum stress-mediated apoptosis

Cellular toxicity of hyperlipidemia has been long considered a major cause of various intractable disease such as diabetes. Discovering lipotoxicity antagonist with high efficiency and low side effects is of importance to develop therapeutics for relevant diseases. In the current study, we evaluate the anti-lipotoxic potential of punicalagin (PU) on pancreatic cells and investigate its underpinning mechanism involved. The administration of PU effectively improved cell viability, quenched intracellular reactive oxygen species, alleviated lipid peroxidation, and enhanced cellular antioxidative capacity in RINm5F cells stimulated by sodium palmitate. Besides that, PU treatment significantly inhibited the overload of mitochondrial calcium ions; alleviated the activation of endoplasmic reticulum (ER) stress mediators including glucose-regulated protein 78, protein kinase RNA-like ER kinase, eukaryotic initiation factor 2α, activating transcription factor 6, caspase 12, and C/EBP homologous protein (CHOP); and attenuated the expression of cleaved caspase 3 and poly ADP-ribose polymerase in test cells. Further RNA interference experiment results and miR211-5p expression analysis revealed that PU may directly mitigate CHOP expression and upregulate the expression of miR211-5p to reduce ER stress-induced pancreatic cell death. The efficacy of PU in maintaining redox equilibrium and diminishing ER stress on pancreatic cells stressed by hyperlipidemia suggests that PU can be used as a promising dietary natural product to safeguard the pancreatic health against lipotoxicity.

Arsenic-Induced, Mitochondria-Mediated Apoptosis Is Associated with Decreased Peroxisome Proliferator-Activated Receptor γ Coactivator α in Rat Brains

Chronic exposure to arsenic in drinking water damages cognitive function, and nerve cell apoptosis is one of the primary characteristics. The damage to mitochondrial structure and/or function is one of the main characteristics of apoptosis. Peroxisome proliferator-activated receptor γ coactivator α (PGC-1α) is involved in the regulation of mitochondrial biogenesis, energy metabolism, and apoptosis. In this study, we aimed to study the role of PGC-1α in sodium arsenite (NaAsO₂)-induced mitochondrial apoptosis in rat hippocampal cells. We discovered that increased arsenic-induced apoptosis in rat hippocampus increased with NaAsO₂ (0, 2, 10, and 50 mg/L, orally via drinking water for 12 weeks) exposure by TUNEL assay, and the structure of mitochondria was incomplete and swollen and had increased lysosomes, lipofuscins, and nuclear membrane shrinkage observed via transmission electron microscopy. Furthermore, NaAsO₂ reduced the levels of Bcl-2 and PGC-1α and increased the levels of Bax and cytochrome C expression. Moreover, correlation analysis showed that brain arsenic content was negatively correlated with PGC-1α levels and brain ATP content; PGC-1α levels were negatively correlated with apoptosis rate; and brain ATP content was positively correlated with PGC-1α levels, but no significant correlation between ATP content and apoptosis has been observed in this study. Taken together, the results of this study indicate that NaAsO₂-induced mitochondrial pathway apoptosis is related to the reduction of PGC-1α, accompanied by ATP depletion.

Punica granatum L. Extract Shows Cardioprotective Effects Measured by Oxidative Stress Markers and Biomarkers of Heart Failure in an Animal Model of Metabolic Syndrome

Metabolic syndrome (MetS) significantly increases the risk of cardiovascular diseases (CVD), a leading cause of death globally. The presented study investigated the cardioprotective role of dietary polyphenols found in pomegranate peels in an animal model of metabolic syndrome. Zucker diabetic fatty rats (ZDF, MetS rats, fa/fa) were supplemented with polyphenol-rich pomegranate peel extract (EPP) at two dosages: 100 mg/kg BW and 200 mg/kg BW. The extract was administered for 8 weeks. The effect of ethanolic peel extract on the concentration of oxidative stress markers (CAT, SOD, MnSOD, GR, GST, GPx, TOS, SH, and MDA), biomarkers of heart failure (cTnI, GAL-3), and alternations in tissue architecture was assessed. The results showed a significant increase in SH concentration mediated via EPP supplementation (p < 0.001). Treatment with a 100 mg/kg BW dosage reduced the TOS level more efficiently than the higher dose. Interestingly, the CAT and GST activities were relevantly higher in the MetS 100 group (p < 0.001) compared to the MetS control. The rats administered EPP at a dose of 200 mg/kg BW did not follow a similar trend. No differences in the GR (p = 0.063), SOD (p = 0.455), MnSOD (p = 0.155), and MDA (p = 0.790) concentration were observed after exposure to the pomegranate peel extract. The administration of EPP did not influence the cTnI and GAL-3 levels. Histology analysis of the heart and aorta sections revealed no toxic changes in phenolic-treated rats. The findings of this study prove that the extract from pomegranate peels possesses free radical scavenging properties in the myocardium. The effect on alleviating ventricular remodeling and cardiomyocyte necrosis was not confirmed and requires further investigation.

A review of important heavy metals toxicity with special emphasis on nephrotoxicity and its management in cattle

Toxicity with heavy metals has proven to be a significant hazard with several health problems linked to it. Heavy metals bioaccumulate in living organisms, pollute the food chain, and possibly threaten the health of animals. Many industries, fertilizers, traffic, automobile, paint, groundwater, and animal feed are sources of contamination of heavy metals. Few metals, such as aluminum (Al), may be eliminated by the elimination processes, but other metals like lead (Pb), arsenic (As), and cadmium (Ca) accumulate in the body and food chain, leading to chronic toxicity in animals. Even if these metals have no biological purpose, their toxic effects are still present in some form that is damaging to the animal body and its appropriate functioning. Cadmium (Cd) and Pb have negative impacts on a number of physiological and biochemical processes when exposed to sub-lethal doses. The nephrotoxic effects of Pb, As, and Cd are well known, and high amounts of naturally occurring environmental metals as well as occupational populations with high exposures have an adverse relationship between kidney damage and toxic metal exposure. Metal toxicity is determined by the absorbed dosage, the route of exposure, and the duration of exposure, whether acute or chronic. This can lead to numerous disorders and can also result in excessive damage due to oxidative stress generated by free radical production. Heavy metals concentration can be decreased through various procedures including bioremediation, pyrolysis, phytoremediation, rhizofiltration, biochar, and thermal process. This review discusses few heavy metals, their toxicity mechanisms, and their health impacts on cattle with special emphasis on the kidneys.