Endothelin ETA receptor/lipid peroxides/COX-2/TGF-β1 signalling underlies aggravated nephrotoxicity caused by cyclosporine plus indomethacin in rats

Gestationally administered RAS modulators reprogram endotoxic cardiovascular and inflammatory profiles in adult male offspring of preeclamptic rats

Previous studies showed that preeclampsia (PE) amplifies cardiovascular dysfunction induced by endotoxemia in adult male, but not female, offspring. Here, we asked if such aggravated endotoxic insult could be nullified by modulators of the renin-angiotensin system (RAS). PE was induced by gestational administration of Nω-nitro-L-arginine methyl ester(L-NAME, a nitric oxide synthase inhibitor). Adult male offspring of PE mothers treated gestationally with angiotensin 1-7 (Ang1-7, angiotensin II-derived vasodilator), losartan (AT1 receptor antagonist), pioglitazone (peroxisome proliferator-activated receptor gamma, PPARγ, agonist), or combined losartan/pioglitazone were instrumented with femoral indwelling catheters and challenged intravenously with a 5-mg/kg dose of lipopolysaccharides (LPS, 5 mg/kg). LPS caused significant decreases in blood pressure (BP) and spectral index of overall heart rate variability and increases in heart rate and left ventricular contractility (dP/dtmax). These effects were mostly reduced to similar magnitudes by individual drug therapies. In offspring born to Ang1-7-treated dams, the spectral index of cardiac sympathovagal balance showed elevated sympathetic dominance in response to LPS. Immunohistochemistry revealed that Ang1-7, but not losartan/pioglitazone, abolished the exaggerated increases in toll-like receptor 4 (TLR-4) expression caused by PE/LPS in heart tissues and neuronal circuits of brainstem rostral ventrolateral medulla (RVLM). By contrast, the losartan/pioglitazone regimen, but not Ang1-7, decreased and increased angiotensin converting enzyme (ACE) and ACE2 expression, respectively. Together, gestational fetal reprogramming of Ang II (depression) and Ang1-7 (activation) arms of RAS effectively counterbalance worsened endotoxic cardiovascular and inflammatory profiles in adult male offspring of PE rats.

Suppression by central adenosine A3 receptors of the cholinergic defense against cardiovascular aberrations of sepsis: role of PI3K/MAPKs/NFκB signaling

Introduction: Despite the established role of peripheral adenosine receptors in sepsis-induced organ dysfunction, little or no data is available on the interaction of central adenosine receptors with sepsis. The current study tested the hypothesis that central adenosine A3 receptors (A3ARs) modulate the cardiovascular aberrations and neuroinflammation triggered by sepsis and their counteraction by the cholinergic antiinflammatory pathway. Methods: Sepsis was induced by cecal ligation and puncture (CLP) in rats pre-instrumented with femoral and intracisternal (i.c.) catheters for hemodynamic monitoring and central drug administration, respectively. Results: The CLP-induced hypotension, reduction in overall heart rate variability (HRV) and sympathovagal imbalance towards parasympathetic predominance were abolished by i.v. nicotine (100 μg/kg) or i.c. VUF5574 (A3AR antagonist, 2 µg/rat). In addition, the selective A3AR agonist, 3-iodobenzyl-5'-N-methylcarboxamidoadenosine IB-MECA, 4 µg/rat, i.c.) exaggerated the hypotension and cardiac autonomic dysfunction induced by sepsis and opposed the favorable nicotine actions against these septic manifestations. Immunohistochemically, IB-MECA abolished the nicotine-mediated downregulation of NFκB and NOX2 expression in rostral ventrolateral medullary areas (RVLM) of brainstem of septic rats. The inhibitory actions of IB-MECA on nicotine responses disappeared after i.c. administration of PD98059 (MAPK-ERK inhibitor), SP600125 (MAPK-JNK inhibitor) or wortmannin (PI3K inhibitor). Moreover, infliximab (TNFα inhibitor) eliminated the IB-MECA-induced rises in RVLM-NFκB expression and falls in HRV, but not blood pressure. Conclusion: Central PI3K/MAPKs pathway mediates the A3AR counteraction of cholinergic defenses against cardiovascular and neuroinflammatory aberrations in sepsis.

Adenosine A1 receptors of the medullary solitary tract arbitrate the nicotine counteraction of neuroinflammation and cardiovascular dysfunction in septic rats

The cholinergic pathway plays a crucial role in improving inflammatory end-organ damage. Given the interplay between cholinergic and adenosinergic neurotransmission, we tested the hypothesis that central adenosine A1 receptors (A1ARs) modulate the nicotine counteraction of cardiovascular and inflammatory insults induced by sepsis in rats. Sepsis was induced by cecal ligation and puncture (CLP) 24-h before cardiovascular measurements. Nicotine (25-100 µg/kg i.v.) dose-dependently reversed septic manifestations of hypotension and impaired heart rate variability (HRV) and cardiac sympathovagal balance. Like nicotine, intracisternal (i.c.) administration of N(6)-cyclopentyladenosine (CPA, A1AR agonist) to CLP rats increased indices of HRV and sympathovagal balance. Moreover, greater surges in these parameters were noted upon simultaneous nicotine/CPA administration. The favorable influences of nicotine on blood pressure and HRV in sepsis were diminished after central blockade of A1ARs by i.c. 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX). Molecular studies revealed that (i) septic rises in myocardial and brainstem nucleus of solitary tract (NTS) NFκB expression were abrogated by nicotine and largely reinstated after blockade of A1ARs, and (ii) A1AR expression in the same areas was reduced by DPCPX. It is concluded that myocardial and medullary A1ARs facilitate the cholinergic counteraction of cardiac and neuroinflammation induced by sepsis and interrelated cardiomyopathic and neuropathic hitches.

Short-lived sensitization of cardiovascular outcomes of postpartum endotoxemia in preeclamptic rats: Role of medullary solitary tract neuroinflammation

Preeclampsia (PE) is a pregnancy-related disorder with serious maternal complications. Considering the increased importance of postpartum infection in maternal morbidity and mortality, we investigated whether preeclamptic maternal programming alters cardiovascular consequences of endotoxemia in rats and the role of cardiac and brainstem neuroinflammation in this interaction. Preeclampsia was induced by oral administration of L-NAME (50 mg/kg/day) for 7 days starting from day 14 of conception. Changes in blood pressure, heart rate, and cardiac autonomic function caused by lipopolysaccharide (LPS, 5 mg/kg i.v.) were assessed in mothers at 3 weeks (weaning time) and 9 weeks postnatally. Compared with respective non-PE counterparts, LPS treatment of weaning PE mothers caused significantly greater (i) falls in blood pressure, (ii) rises in heart rate and left ventricular contractility (dP/dtmax), (iii) reductions in time and frequency domain indices of heart rate variability and shifts in cardiac sympathovagal balance (low-frequency/high-frequency ratio, LF/HF) towards parasympathetic dominance, and (iv) attenuation of reflex bradycardic responses measured by the vasoactive method. The intensified LPS effects in weaning PE rats subsided after 9 weeks of delivery. Immunohistochemical studies showed increased protein expression of nuclear factor kappa B (NF-κB) in brainstem neuronal pools of the nucleus of the solitary tract (NTS), but not rostral ventrolateral medulla (RVLM), in endotoxic PE weaning rats compared with non-PE rats. Cardiac NF-κB expression was increased by LPS but this was similarly noted in PE and non-PE rats. Together, preeclamptic maternal programming elicits short-term exacerbation of endotoxic cardiovascular and autonomic derangements due possibly to exaggerated NTS neuroinflammatory insult.

Montelukast potentiates the antiinflammatory effect of NSAIDs in the rat paw formalin model and simultaneously minimizes the risk of gastric damage

OBJECTIVE AND DESIGN

Montelukast, a cysteinyl leukotriene receptor antagonist, exhibits antiinflammatory action. We tested whether exposure to montelukast plus nonsteroidal antiinflammatory drugs (NSAIDs) elicits better control of paw inflammation in the rat formalin test and improves associated gastric damage.

MATERIALS

A total of 46 adult male rats were used in the study.

TREATMENTS

We evaluated separate and combined effects of montelukast (20 mg/kg), celecoxib (COX2 inhibitor, 10 mg/kg), and diclofenac (nonselective COX1/COX2 inhibitor, 10 mg/kg) on paw and gastric damage in the rat formalin test.

RESULTS

Individual pretreatments of rats with montelukast, diclofenac, or celecoxib partly reduced formalin-induced increases in (i) paw edema, fibrosis, and inflammatory cells, (iii) serum interleukin-6 (IL-6) and leukotrienes (LTB4 and LTD4), and (iv) paw expressions of inducible nitric oxide synthase (iNOS) and COX2. These effects were accentuated in rats treated with montelukast plus diclofenac or montelukast plus celecoxib. Alternatively, montelukast or celecoxib, but not diclofenac, alleviated formalin-evoked gastric damage and increments in tumor necrosis factor-α and decrements in prostaglandin-E₂. These advantageous gastric influences were potentiated in rats treated with montelukast plus celecoxib.

CONCLUSIONS

While montelukast equally enhances antiinflammatory action of diclofenac or celecoxib via downregulating iNOS/COX2/LTs/IL-6 signaling, its gastroprotective action is preferentially potentiated by celecoxib.

Nicotine Improves Survivability, Hypotension, and Impaired Adenosinergic Renal Vasodilations in Endotoxic Rats: Role of α7-nAChRs/HO-1 Pathway

The nicotinic/cholinergic antiinflammatory pathway protects against acute kidney injury and other end-organ damages induced by endotoxemia. In this study, we tested the hypothesis that functional α7-nAChRs/heme oxygenase-1 (HO-1) pathway is imperative for the nicotine counteraction of hemodynamic and renovascular dysfunction caused by acute endotoxemia in rats. Renal vasodilations were induced by cumulative bolus injections of acetylcholine (ACh, 0.01 nmol-7.29 nmol) or ethylcarboxamidoadenosine (NECA, adenosine receptor agonist, 1.6 nmol-100 nmol) in isolated phenylephrine-preconstricted perfused kidneys. The data showed that 6-h treatment with lipopolysaccharide (LPS, 5 mg/kg i.p.) decreased systolic blood pressure and renal vasodilations caused by NECA but not Ach. The endotoxic insult also increased the mortality rate and elevated serum urea and creatinine. These LPS effects were sex-unrelated, except hypotension, and enhanced mortality which were more evident in male rodents, and abrogated after co-administration of nicotine (0.5, 1 mg/kg and 2 mg/kg) in a dose-dependent fashion. The advantageous effects of nicotine on NECA vasodilations, survivability, and kidney biomarkers in endotoxic male rats disappeared upon concurrent exposure to methyllycaconitine citrate (α7-nAChR blocker) or zinc protoporphyrin (HO-1 inhibitor) and were reproduced after treatment with bilirubin, but not hemin (HO-1 inducer) or tricarbonyldichlororuthenium (II) dimer (carbon monoxide-releasing molecule). Together, current biochemical and pharmacological evidence suggests key roles for α7-nAChRs and the bilirubin byproduct of the HO-1 signaling in the nicotine counteraction of renal dysfunction and reduced adenosinergic renal vasodilator capacity in endotoxic rats.

Cardiac and Brainstem Neuroinflammatory Pathways Account for Androgenic Incitement of Cardiovascular and Autonomic Manifestations in Endotoxic Male Rats

ABSTRACT

Inconsistent reports are available on the role of testosterone in end-organ damage caused by endotoxemia. Here, pharmacologic, surgical, and molecular studies were employed to assess the testosterone modulation of cardiovascular, autonomic, and peripheral and central inflammatory derangements caused by endotoxemia. Studies were performed in conscious male rats preinstrumented with femoral indwelling catheters for the measurement of blood pressure and subjected to castration or pharmacologic interventions that interrupt the biosynthetic cascade of testosterone. Compared with the effects of lipopolysaccharide (10 mg/kg intravenously) in sham operated rats, 2-week castration reduced the lipopolysaccharide-evoked (1) falls in blood pressure, (2) decreases in time- and frequency-domain indices of heart rate variability, (3) shifts in spectral measures of cardiac sympathovagal balance toward parasympathetic dominance, and (4) increases in protein expressions of toll-like receptor-4 and monocyte chemoattractant protein-1 in heart and medullary neurons of the nucleus tractus solitarius and rostral ventrolateral medulla. While the ameliorating actions of castration on endotoxic cardiovascular manifestations were maintained after testosterone replacement, the concomitant inflammatory signals were restored to near-sham levels. The favorable influences of castration on inflammatory and cardiovascular abnormalities of endotoxemia were replicated in intact rats pretreated with degarelix (gonadotropin-releasing hormone receptor blocker) or finasteride (5α-reductase inhibitor) but not formestane (aromatase inhibitor). The data signifies the importance of androgens and its biosynthetic enzymes in cardiovascular and autonomic insults induced by the endotoxic inflammatory response. Clinically, the interruption of testosterone biosynthesis could offer a potential strategy for endotoxemia management.

Androgenic modulation of arterial baroreceptor dysfunction and neuroinflammation in endotoxic male rats

Autonomic neuropathy contributes to cardiovascular derangements induced by endotoxemia. In this communication, we tested the hypothesis that androgenic hormones improve arterial baroreflex dysfunction and predisposing neuroinflammatory response caused by endotoxemia in male rats. Baroreflex curves relating changes in heart rate to increases or decreases in blood pressure evoked by phenylephrine (PE) and sodium nitroprusside (SNP), respectively, were constructed in conscious sham-operated, castrated, and testosterone-replaced castrated rats treated with or without lipopolysaccharide (LPS, 10 mg/kg i.v.). Slopes of baroreflex curves were taken as measures of baroreflex sensitivity (BRS). In sham rats, LPS significantly reduced reflex bradycardia (BRSPE) and tachycardia (BRSSNP) and increased immunohistochemical expression of nuclear factor kappa B (NFκB) in heart and brainstem neurons of nucleus tractus solitarius (NTS) and rostral ventrolateral medulla (RVLM). The baroreflex depressant effect of LPS was maintained in castrated rats despite the remarkably attenuated inflammatory response. Testosterone replacement of castrated rats counteracted LPS-evoked BRSPE, but not BRSSNP, depression and increased cardiac, but not neuronal, NFκB expression. We also evaluated whether LPS responses could be affected following pharmacologic inhibition of androgenic biosynthetic pathways. Whereas none of LPS effects were altered in rats pretreated with formestane (aromatase inhibitor) or finasteride (5α-reductase inhibitor), the LPS-evoked BRSPE, but not BRSSNP, depression and cardiac and neuronal inflammation disappeared in rats pretreated with degarelix (gonadotropin-releasing hormone receptor blocker). Overall, despite the seemingly provocative role for the hypothalamic-pituitary-gonadal axis in the neuroinflammatory and baroreflex depressant effects of LPS, testosterone appears to distinctly modulate the two LPS effects.

Pre-eclamptic Fetal Programming Alters Neuroinflammatory and Cardiovascular Consequences of Endotoxemia in Sex-Specific Manners

Pre-eclampsia (PE)-induced fetal programming predisposes offspring to health hazards in adult life. Here, we tested the hypothesis that pre-eclamptic fetal programming elicits sexually dimorphic inflammatory and cardiovascular complications to endotoxemia in adult rat offspring. PE was induced by oral administration of L-NAME (50 mg/kg per day for seven consecutive days) starting from day 14 of conception. Cardiovascular studies were performed in conscious adult male and female offspring preinstrumented with femoral indwelling catheters. Compared with non-PE male counterparts, intravenous administration of lipopolysaccharide (LPS, 5 mg/kg) to PE male offspring caused significantly greater 1) falls in blood pressure, 2) increases in heart rate, 3) rises in arterial dP/dtmax, a correlate of left ventricular contractility, and 4) decreases in time- and frequency-domain indices of heart rate variability (HRV). By contrast, the hypotensive and tachycardic actions of LPS in female offspring were independent of the pre-eclamptic state and no clear changes in HRV or dP/dtmax were noted. Measurement of arterial baroreflex activity by vasoactive method revealed no sex specificity in baroreflex dysfunction induced by LPS. Immunohistochemical studies showed increased protein expression of toll-like receptor 4 in heart as well as in brainstem neuronal pools of the nucleus of solitary tract and rostral ventrolateral medulla in endotoxic PE male, but not female, offspring. Enhanced myocardial, but not neuronal, expression of monocyte chemoattractant protein-1 was also demonstrated in LPS-treated male offspring. Together, pre-eclamptic fetal programming aggravates endotoxic manifestations of hypotension and autonomic dysfunction in male offspring via exacerbating myocardial and neuromedullary inflammatory pathways. SIGNIFICANCE STATEMENT: Current molecular and neuroanatomical evidence highlights a key role for pre-eclamptic fetal programming in offspring predisposition to health hazards induced by endotoxemia in adult life. Pre-eclampsia accentuates endotoxic manifestations of hypotension, tachycardia, and cardiac autonomic dysfunction in male offspring via exacerbating myocardial and central inflammatory pathways. The absence of such detrimental effects in female littermates suggests sexual dimorphism in the interaction of pre-eclamptic fetal programming with endotoxemia.

Time and sex dependency of hemodynamic, renal, and survivability effects of endotoxemia in rats

Widely different exposure times to endotoxic insults have been employed in reported studies. The current experimental study systematically evaluated the time-course and sex influences of endotoxic insult on survivability and cardiovascular and renal functions. Rats received i.p. lipopolysaccharide (LPS, 5 mg/kg) once or twice (over 2 successive days). Systolic blood pressure (SBP), biomarkers of renal function and inflammation, and vasodilator responsiveness of isolated perfused kidneys to acetylcholine (ACh) or N-ethylcarboxamidoadenosine (NECA) were evaluated 6 hr after first LPS injection or 1, 2, or 6 days later. A single 6-hr LPS challenge caused (i) sex-unrelated elevations in serum urea and creatinine and reductions in NECA, but not ACh, vasodilations, (ii) more increases in renal NF-κB/iNOS expressions in male than in female rats, and (iii) hypotension and tachycardia only in male rats. These parameters, except for hemodynamic changes, were restored to near-control levels 1 day after single LPS dosing. The 2-days dosing with LPS had no effects on renal function biomarkers, but caused hypotension, tachycardia, and increases in renal NF-κB/iNOS expression and NECA and ACh vasodilations in both rat sexes. None of these parameters were different from control values when measured 6 days after the endotoxic insult. Alternatively, the rat mortality was observed during first 2 days of the study and was notably higher in male than in female rats. Our data suggest that the frequency and time elapsed after LPS exposure as well as rat sex are important determinants of the magnitude and direction of detrimental effects of endotoxemia.

Co-targeting of endothelin-A and vitamin D receptors: a novel strategy to ameliorate cisplatin-induced nephrotoxicity

BACKGROUND

Although modulation of the vitamin D receptor (VDR) and endothelin-A receptor (ETAR) has previously been reported to offer renoprotection against cisplatin-induced nephrotoxicity, the possible interaction between the ET-1 and vitamin D pathways remains obscure. Therefore, the present study addressed the possible interaction between these signalling pathways using BQ-123 (a selective ETAR blocker) and alfacalcidol (a vitamin D3 analogue) separately or in combination.

METHODS

Male Sprague-Dawley rats were divided into the following groups: control (DMSO orally), cisplatin (single dose of 6 mg/kg ip; nephrotoxicity model), cisplatin + BQ-123 (1 mg/kg BQ-123 ip 1 h before and 1 day after cisplatin), cisplatin + alfacalcidol (50 ng/kg alfacalcidol orally 5 days before and 14 days after cisplatin), and cisplatin + BQ-123+alfacalcidol. Nephrotoxicity was evaluated 96 h and 14 days following cisplatin administration.

RESULTS

Both BQ-123 and alfacalcidol counteracted cisplatin-induced nephrotoxic changes. Specifically, they reduced serum creatinine and urea levels; renal tumour necrosis factor-alpha (TNF-α), transforming growth factor-beta1 (TGF-β1), and phosphorylated nuclear factor-kappa B (pNF-κB) content; and caspase-3 activity. They downregulated ET-1 and ETAR expression and ameliorated cisplatin-induced acute tubular necrosis. In addition, the treatments have increased VDR and endothelin-B receptor (ETBR) expression; however, BQ-123 did not affect ETBR. The effect of the combination regimen surpassed that of each drug alone.

CONCLUSION

These findings highlight the potential cross-talk between vitamin D and ET-1 pathways and pave the way for future preclinical/clinical studies to explore further mechanisms involved in this cross-talk.

Nicotine reverses the enhanced renal vasodilator capacity in endotoxic rats: Role of α7/α4β2 nAChRs and HSP70

BACKGROUND

Nicotine alleviates renal inflammation and injury induced by endotoxemia. This study investigated (i) the nicotine modulation of hemodynamic and renal vasodilatory responses to endotoxemia in rats, and (ii) roles of α7 or α4β2-nAChRs and related HSP70/TNFα/iNOS signaling in the interaction.

METHODS

Endotoxemia was induced by ip lipopolysaccharide (5 mg/kg/day, for 2 days) and changes in systolic blood pressure and vasodilator responsiveness of isolated perfused kidney to acetylcholine or 5'-N-ethylcarboxamidoadenosine (NECA, adenosine receptor agonist) were evaluated.

RESULTS

Lipopolysaccharide had no effect on serum creatinine, reduced blood pressure, and increased renal vasodilations induced by acetylcholine or NECA in male and female preparations. Immunohistochemical analyses showed that lipopolysaccharide reduced renal HSP70 expression, but increased α7-nAChRs, α4β2-nAChRs and iNOS expressions. The co-administration of aminoguanidine (iNOS inhibitor), pentoxifylline (TNFα inhibitor), or nicotine attenuated lipopolysaccharide mediation of renal vasodilations and elevations in α7/α4β2-nAChR and iNOS expressions. Nicotine also reversed the downregulating effect of lipopolysaccharide on HSP70 expression. α7-nAChRs (methyllycaconitine citrate, MLA) or α4β2-nAChRs (dihydro-β-erythroidine, DHβE) blockade potentiated the lipopolysaccharide enhancement of renal vasodilations, and abolished the depressant effect of nicotine on lipopolysaccharide responses. A similar abolition of nicotine effects was seen after HSP70 inhibition by quercetin. Alternatively, lipopolysaccharide hypotension was eliminated in rats treated with DHβE/nicotine or quercetin/nicotine regimen in contrast to no effect for nicotine alone or combined with MLA.

CONCLUSIONS

These findings establish that nicotine offsets lipopolysaccharide facilitation of renal vasodilations possibly through a crosstalk between HSP70 and nAChRs of the α7 and α4β2 types.

Renal Oxidative Stress and Inflammatory Response in Perinatal Cyclosporine-A Exposed Rat Progeny and its Relation to Gender

Background and Aim of the Work:

The current study postulated that cyclosporine A (CSA) could induce gender-specific renal damage. Hence, the current study aims to investigate the nephrotoxic effect of perinatal exposure of male and female rat progeny to CSA. Moreover, it aims to evaluate the oxidative stress and inflammation as a possible pathophysiologic mechanism.

Materials and Methods:

Female rats were randomly allocated to two groups of four and assigned to undergo either CSA (15 mg/kg/day; the 6^th day after conception and continuing until the progeny were weaned) or vehicle treatment as control groups. At the age of 6 weeks, the progeny were divided into the following four groups: male progeny of control-group mothers (M-vehicle, 7); male progeny of CSA-treated mothers (M-CSA, 9); female progeny of control-group mothers (F-vehicle, 7); and female progeny of CSA-treated mothers (F-CSA, 6). Serum adiponectin, tumor necrosis factor-α (TNF-α) and creatinine, creatinine clearance, and urinary 8-isoprostane were measured. Histopathological examination by hematoxylin and eosin stain of Kidney was carried out.

Results:

Proteinuria and decreased creatinine clearance are significant in M-CSA than M-vehicle and F-CSA. 8-isoprostane is lower in F-CSA than F-vehicle. Increased TNF-α and decreased adiponectin levels in M-CSA than M-vehicle were observed. No significant differences were found in female rat groups.

Conclusion:

From the current study, it could be concluded that CSA could induce renal inflammation as well as oxidative stress that may explain the impaired renal function. The sex difference was a prominent finding in their vulnerability to CSA effects.

Renoprotective effects of ET(A) receptor antagonists therapy in experimental non-diabetic chronic kidney disease: Is there still hope for the future?

Chronic kidney disease (CKD) is a life-threatening disease arising as a frequent complication of diabetes, obesity and hypertension. Since it is typically undetected for long periods, it often progresses to end-stage renal disease. CKD is characterized by the development of progressive glomerulosclerosis, interstitial fibrosis and tubular atrophy along with a decreased glomerular filtration rate. This is associated with podocyte injury and a progressive rise in proteinuria. As endothelin-1 (ET-1) through the activation of endothelin receptor type A (ET(A)) promotes renal cell injury, inflammation, and fibrosis which finally lead to proteinuria, it is not surprising that ET(A) receptors antagonists have been proven to have beneficial renoprotective effects in both experimental and clinical studies in diabetic and non-diabetic CKD. Unfortunately, fluid retention encountered in large clinical trials in diabetic CKD led to the termination of these studies. Therefore, several advances, including the synthesis of new antagonists with enhanced pharmacological activity, the use of lower doses of ET antagonists, the addition of diuretics, plus simply searching for distinct pathological states to be treated, are promising targets for future experimental studies. In support of these approaches, our group demonstrated in adult subtotally nephrectomized Ren-2 transgenic rats that the addition of a diuretic on top of renin-angiotensin and ET(A) blockade led to a further decrease of proteinuria. This effect was independent of blood pressure which was normalized in all treated groups. Recent data in non-diabetic CKD, therefore, indicate a new potential for ET(A) antagonists, at least under certain pathological conditions.

Role of Wnt4/β-catenin, Ang II/TGFβ, ACE2, NF-κB, and IL-18 in attenuating renal ischemia/reperfusion-induced injury in rats treated with Vit D and pioglitazone

Renal ischemia-reperfusion injury (I/RI) remains a critical clinical situation. Several evidence revealed the potential reno-protective effects of Vitamin D and/or pioglitazone, on renal I/RI. This study addresses the possible involvement of the Wnt4/β-catenin signaling, p-S536NF-κBp65, PPARγ, Ang II/TGF-β, and ACE2 as potential effectors to vitamin D and pioglitazone-mediated renoprotective effects. Two sets of Sprague-Dawley rats (n = 30 rat each), were randomized into sham, I/R, Vit D "alfacalcidol" (5 ng/kg/day), pioglitazone (5 mg/kg/day), and Vit D + pioglitazone groups. In all groups renal biochemical parameters, as well as inflammatory and structural profiles were assessed, besides the expression/contents of Wnt4/β-catenin and pS536-NF-κBp65. All treatments started 7 days before I/RI and animals were killed 24 h after I/RI in the first set, while those in the 2nd set continued their treatments for 14 days. After 24 h, all pre-treatments impeded theI/R effect on neutrophils recruitment, p-S536NF-κBp65, IL-18, NGAL, caspase-3, AngII, ACE-2, PPARγ and TGF-β, besides the expression of Wnt4 and ACE-2 with notable reflection on histological changes. Two weeks after I/RI, except a marked up regulation in Wnt4 expression and a striking elevation in the β-catenin content, the magnitude of the injurious events was relatively less pronounced, an effect that was mostly augmented by the different treatments. The current study pledges a promising and novel reno-protective role of the administration of Vit D and pioglitazone entailing a potential involvement of ICAM-1, MPO, NF-κB, Ang II, ACE2, TGFβ, and a modulation of Wnt4/β-catenin pathway.

Enhanced lipoxygenase/LTD4 signaling accounts for the exaggerated hypertensive and nephrotoxic effects of cyclosporine plus indomethacin in rats

The combined use of cyclosporine (CSA) and nonsteroidal antiinflammatory drugs (NSAIDs) causes exaggerated rises in systolic blood pressure (SBP) and nephrotoxicity. We examined whether these influences relate to the arachidonate/5-lipoxygenase (LOX) pathway. Rats were treated with CSA (20 mg kg^-1 day^-1), indomethacin (5 mg kg^-1 day^-1), or their combination for 10 days. Changes in SBP and renal biochemical/histopathological characteristics along with leukotriene levels were determined in rats treated with or without LT receptor antagonists. CSA or indomethacin caused: (i) renal tubular atrophy and interstitial fibrosis, (ii) increases in serum creatinine, blood urea nitrogen (BUN), and renal LTD4, LTB4, TNF-α, TGF-β1, and caspase-3, and (iii) decreases in renal PGE2 and total antioxidant capacity (TAC). SBP measured by tail-cuff plethysmography was increased by CSA but not indomethacin. These effects were mostly intensified in rats treated with CSA plus indomethacin. The co-treatment with montelukast (cysteinyl LT receptor blocker), but not ONO-4057 (LTB4 receptor blocker), ameliorated CSA/indomethacin-evoked hypertension, renal structural/biochemical deterioration, and LTD4 levels. Moreover, montelukast exhibited a greater capacity in reversing inflammatory, oxidative, apoptotic, and fibrotic abnormalities induced by CSA/indomethacin. Overall, lipoxygenase/LTD4 upregulation contributes to the exaggerated hypertension and nephrotoxicity caused by CSA/indomethacin. The therapeutic potential of cysteinyl LT receptor antagonism in rectifying CSA/NSAIDs-evoked anomalies is warranted.

Possible protective effect of the algae spirulina against nephrotoxicity induced by cyclosporine A and/or gamma radiation in rats

The present study was conducted to evaluate the possible protective role of the algae spirulina (Sp) against nephrotoxicity and oxidative stress which are the main secondary effects induced by the immunosuppressant drug CSA and/or ionizing radiation. In this study, male rats were given Sp (1 g/kg) either for 15 days before irradiation (6.5 Gy) or 5 days before and 10 days concomitant with CSA (25 mg/kg). Markers used to assess renal injury included serum creatinine, urea, glucose, albumin, protein, and lipid profile as well as kidney content of reduced glutathione (GSH); lipid peroxidation (thiobarbituric acid reactive substances (TBARS)); nitrite and superoxide dismutase (SOD) activity. In addition, some trace elements (Zn and Mg) were estimated in kidney. Apoptosis was assessed by immunohistochemical estimation of caspase-3 expression in addition to histopathological examination. Results revealed that gamma radiation and/or CSA induced elevation in urea, creatinine, lipids, and glucose while decreasing albumin and protein levels. There was a noticeable increase in kidney content of GSH, TBARS, and nitrite. Meanwhile, profound decrease in kidney SOD activity was observed. Treatment with Sp significantly reversed the changes induced by CSA and/or gamma radiation in renal function tests. Spirulina also ameliorated kidney oxidative stress through decreasing GSH, TBARS, and nitrite kidney content while increasing SOD activity. Histopathological examination further confirmed Sp protective efficacy. Moreover, kidney caspase-3 expression that was triggered by CSA and/or gamma radiation was decreased. In conclusion, spirulina can be regarded as a promising renoprotective natural agent against renal injury induced by CSA and/or gamma radiation.

Cyclosporine A exhibits gender-specific nephrotoxicity in rats: Effect on renal tissue inflammation

Cyclosporine A (CSA) is a widely used immunosuppressant drug known to commonly cause cardio and nephrotoxicity. A study looking at the sex specificity of the cardiotoxicity of CSA revealed that sexual dimorphism existed when looking at the electrocardiographs and left ventricles of CSA-treated rats. We hypothesized that cyclosporine A exhibited gender-specific nephrotoxicity by testing various parameters of kidney function in male and female rats treated for 21 days with 15 mg/kg CSA versus control male and female rats that received a vehicle consisting of 18% kolliphore and 2% ethanol in sterile saline. It was found that male rats treated with CSA had significantly higher levels of serum creatinine and lower creatinine clearance than control males. However, serum creatinine and creatinine clearance were not affected by CSA treatment in females. Histopathological examination of kidney cross-sections revealed a heavy aggregation of inflammatory cells and significant vascular congestion in males treated with CSA, which was less prominent in female rats receiving CSA. In addition CSA treated male rats had higher levels of serum cholesterol compared with control while, CSA did not affect serum cholesterol in female rats. Kidney tumor necrosis factor alpha (TNF-α) levels were found to drop in female rats following CSA treatment, whereas no change was observed in male rats before and after treatment. These results suggest that CSA exhibits gender-related nephrotoxicity in rats that might be mediated by differences in the inflammatory response between males and females.

The inflammatory state provokes sexual dimorphism in left ventricular and electrocardiographic effects of chronic cyclosporine in rats

Although cardiotoxicity has been recognized as an adverse effect of cyclosporine A (CSA), no information exists regarding sex specificity of CSA cardiotoxicity. We tested the hypothesis that left ventricular (LV) and electrocardiographic (ECG) effects of CSA and related inflammatory/histopathological derangements are sex related. CSA reduced the LV slope of end-systolic pressure volume relationship and increased isovolumic relaxation constant. These effects were more pronounced in male compared to female rats, suggesting LV systolic and diastolic dysfunction. ECG recordings showed elevated ST segments and increased QTc and T peak trend intervals in CSA-treated male rats, markers of LV ischemia and arrhythmogenesis. In female rats, CSA delayed AV conduction, as reflected by prolonged PR interval. Other sex-related effects for CSA included (i) increased blood cholesterol, and reduced rates of rise and fall in LV pressure and nuclear factor kappa B and angiotensin receptors type 1 expressions in male rats, and (ii) increased LV adiponectin in females. Histopatholgically, CSA caused vascular congestion, blood extravasation, and pyknotic or even absent nuclei in both sexes. In conclusion, rats exhibit sex-independent susceptibility to negative LV and histopathological influences of CSA. These effects become more intensified in male rats, perhaps on account of aggravated ischemic and inflammatory milieus.

Additive Renoprotection by Pioglitazone and Fenofibrate against Inflammatory, Oxidative and Apoptotic Manifestations of Cisplatin Nephrotoxicity: Modulation by PPARs

Nephrotoxicity is a major side effect for the antineoplastic drug cisplatin. Here, we employed pharmacological, biochemical, and molecular studies to investigate the role of peroxisome proliferator-activated receptors (PPARs) in cisplatin nephrotoxicity. Rats were treated with a single i.p. dose of cisplatin (5 mg/kg) alone or combined with pioglitazone (PPARγ agonist), fenofibrate (PPARα agonist), pioglitazone plus fenofibrate, or thalidomide (Tumor necrosis factor-α inhibitor; TNF-α). Cisplatin nephrotoxicity was evidenced by rises in renal indices of functional (blood urea nitrogen, BUN, and creatinine), inflammatory (TNF-α, interleukin 6, IL-6), oxidative (increased malondialdehyde, MDA, and decreased superoxide dismutase, SOD and nitric oxide metabolites, NOx), apoptotic (caspase 3), and histological (glomerular atrophy, acute tubular necrosis and vacuolation) profiles. Cisplatin effects were partly abolished upon concurrent exposure to pioglitazone, fenofibrate, or thalidomide; more renoprotection was observed in rats treated with pioglitazaone plus fenofibrate. Immunostaining showed that renal expressions of PPARα and PPARγ were reduced by cisplatin and restored to vehicle-treated values after simultaneous treatment with pioglitazone or fenofibrate. Fenofibrate or pioglitazone renoprotection remained unaltered after concurrent blockade of PPARα (GW6471) and PPARγ (GW9662), respectively. To complement the rat studies, we also report that in human embryonic kidney cells (HEK293 cells), increases caused by cisplatin in inflammatory, apoptotic, and oxidative biomarkers were (i) partly improved after exposure to pioglitazone, fenofibrate, or thalidomide, and (ii) completely disappeared in cells treated with a combination of all three drugs. These data establish that the combined use of pioglitazone and fenofibrate additively improved manifestations of cisplatin nephrotoxicity through perhaps GW6471/GW9662-insensitive mechanisms.