Annexin A1 protein attenuates cyclosporine-induced renal hemodynamics changes and macrophage infiltration in rats

Resolution Pharmacology: Focus on Pro-Resolving Annexin A1 and Lipid Mediators for Therapeutic Innovation in Inflammation

Chronic diseases that affect our society are made more complex by comorbidities and are poorly managed by the current pharmacology. While all present inflammatory etiopathogeneses, there is an unmet need for better clinical management of these diseases and their multiple symptoms. We discuss here an innovative approach based on the biology of the resolution of inflammation. Studying endogenous pro-resolving peptide and lipid mediators, how they are formed, and which target they interact with, can offer innovative options through augmenting the expression or function of pro-resolving pathways or mimicking their actions with novel targeted molecules. In all cases, resolution offers innovation for the treatment of the primary cause of a given disease and/or for the management of its comorbidities, ultimately improving patient quality of life. By implementing resolution pharmacology, we harness the whole physiology of inflammation, with the potential to bring a marked change in the management of inflammatory conditions.

Annexin A1 exerts renoprotective effects in experimental crescentic glomerulonephritis

Non-resolving inflammation plays a critical role during the transition from renal injury towards end-stage renal disease. The glucocorticoid-inducible protein annexin A1 has been shown to function as key regulator in the resolution phase of inflammation, but its role in immune-mediated crescentic glomerulonephritis has not been studied so far.

Methods: Acute crescentic glomerulonephritis was induced in annexin A1-deficient and wildtype mice using a sheep serum against rat glomerular basement membrane constituents. Animals were sacrificed at d5 and d10 after nephritis induction. Renal leukocyte abundance was studied by immunofluorescence and flow cytometry. Alterations in gene expression were determined by RNA-Seq and gene ontology analysis. Renal levels of eicosanoids and related lipid products were measured using lipid mass spectrometry.

Results: Histological analysis revealed an increased number of sclerotic glomeruli and aggravated tubulointerstitial damage in the kidneys of annexin A1-deficient mice compared to the wildtype controls. Flow cytometry analysis confirmed an increased number of CD45⁺ leukocytes and neutrophil granulocytes in the absence of annexin A1. Lipid mass spectrometry showed elevated levels of prostaglandins PGE2 and PGD2 and reduced levels of antiinflammatory epoxydocosapentaenoic acid regioisomers. RNA-Seq with subsequent gene ontology analysis revealed induction of gene products related to leukocyte activation and chemotaxis as well as regulation of cytokine production and secretion.

Conclusion: Intrinsic annexin A1 reduces proinflammatory signals and infiltration of neutrophil granulocytes and thereby protects the kidney during crescentic glomerulonephritis. The annexin A1 signaling cascade may therefore provide novel targets for the treatment of inflammatory kidney disease.

Protective effects of annexin A1-derived peptide Ac2-26 on liver and kidney injuries induced by cisplatin in rats

AIMS

In this study we evaluated the effect of pharmacological treatment with annexin A1-derived peptide Ac_2-26 in an experimental model of toxicity induced by cisplatin.

MAIN METHODS

Male rats were divided into Sham (control), Cisplatin (received intraperitoneal injections of 10 mg/kg/day of cisplatin for 3 days) and Ac_2-26 (received intraperitoneal injections of 1 mg/kg/day of peptide, 15 min before cisplatin) groups.

KEY FINDINGS

After 6 h of the last dose of cisplatin, an acute inflammatory response was observed characterized by a marked increase in the number of neutrophils and GM-CSF, IL-1β, IL-6, IL-10 and TNF-α plasma levels. Treatment with Ac_2-26 produced higher levels of GM-CSF, corroborating the high numbers of neutrophils, and the anti-inflammatory cytokine IL-4. Ac_2-26 preserved the morphology of liver structures, preventing the damage caused by cisplatin, but did not reduce plasma levels of the hepatotoxicity biomarkers ARG1, GSTα and SDH. In the kidneys, the peptide maintained the markers of kidney damage CLU and KIM-1 at similar levels to the Sham group but did not avoid morphological changes caused by cisplatin. These effects of Ac_2-26 were associated with the reduction of Fpr1 and Fpr2 levels in the organs studied.

SIGNIFICANCE

Pharmacological treatment with peptide Ac_2-26 partially protects the liver and kidneys against the deleterious effects caused by cisplatin in this experimental model.

OUP accepted manuscript

Drug-induced nephrotoxicity is a common problem in clinical medicine and the frequency of drug-related acute and chronic kidney dysfunction worldwide. One of them is anti-tuberculosis (TB) drugs that cause renal function impairment during TB treatment. Medicinal plants contain bioactive compounds that are capable for treating drug or toxin-induced renal disorders. The aim of the present study was to assess the protective effect of the ethanolic extract of Nigella sativa seeds (NS) against anti-TB drugs (ATDs) induced nephrotoxicity in Wistar albino rats. Rats were treated with ATDs for 12weeks (3 alternative days in a week). Supplementation with 125mg NS/kg, p.o. was administered to the experimental rats for 12weeks (3 alternative days in a week considering next day of ATDs treatment). The results demonstrated that NS treatment protected against renal damage induced by ATDs, as evidenced by the reduction in serum urea, creatinine, uric acid, urea nitrogen levels, pro-inflammatory markers (TNF-α and IL-6), whereas improvement in histological tubular and glomerular damage. In addition, NS enhanced the antioxidant enzyme activity (superoxide dismutase and catalase) and decreased the lipid peroxidation and glutathione level in the kidney. In conclusion, NS could reduce chronic nephritis in ATDs treated group through suppressing inflammation and oxidative stress. It suggests that NS can be used as supplementary preventive and protective drug against kidney injury during anti-TB treatment.

Therapeutic Potential of Annexin A1 Modulation in Kidney and Cardiovascular Disorders

Renal and cardiovascular disorders are very prevalent and associated with significant morbidity and mortality. Among diverse pathogenic mechanisms, the dysregulation of immune and inflammatory responses plays an essential role in such disorders. Consequently, the discovery of Annexin A1, as a glucocorticoid-inducible anti-inflammatory protein, has fueled investigation of its role in renal and cardiovascular pathologies. Indeed, with respect to the kidney, its role has been examined in diverse renal pathologies, including acute kidney injury, diabetic nephropathy, immune-mediated nephropathy, drug-induced kidney injury, kidney stone formation, and renal cancer. Regarding the cardiovascular system, major areas of investigation include the role of Annexin A1 in vascular abnormalities, atherosclerosis, and myocardial infarction. Thus, this review briefly describes major structural and functional features of Annexin A1 followed by a review of its role in pathologies of the kidney and the cardiovascular system, as well as the therapeutic potential of its modulation for such disorders.

Investigating Helicobacter pylori-related pyloric hypomotility: functional, histological, and molecular alterations

Multiple theories have been proposed describing the pathogenic mechanisms of Helicobacter pylori (H. pylori)-associated gastric motility disorders. We assessed ex vivo pyloric activity in H. pylori-infected rats, and tried to explore the associated ghrelin hormone alteration and pyloric fibrogenesis. In addition, miR-1 was assessed in pyloric tissue samples, being recently accused of having a role in smooth muscle dysfunction. Ninety adult male Wistar albino rats were assigned into nine groups: 1) control group, 2) sterile broth (vehicle group), 3) amoxicillin control, 4) omeperazole control, 5) clarithromycin control, 6) triple therapy control, 7) H. pylori- group, 8) H. pylori-clarithromycin group, and 9) H. pylori-triple therapy group. Urease enzyme activity was applied as an indicator of H. pylori infection. Ex vivo pyloric contractility was evaluated. Serum ghrelin was assessed, and histological tissue evaluation was performed. Besides, pyloric muscle miR-1 expression was measured. The immunological epithelial to mesenchymal transition (EMT) markers; transforming growth factor β (TGFβ), α-smooth muscle actin (α-SMA), and E-cadherin-3 were also evaluated. By H. pylori infection, a significant (P < 0.001) reduced pyloric contractility index was recorded. The miR-1 expression was decreased (P < 0.001) in the H. pylori-infected group, associated with reduced serum ghrelin, elevated TGFβ, and α-SMA levels and reduced E-cadherin levels. Decreased miR-1 and disturbed molecular pattern were improved by treatment. In conclusion, H. pylori infection was associated with reduced miR-1, epithelial to mesenchymal transition, and pyloric hypomotility. The miR-1 may be a target for further studies to assess its possible involvement in H. pylori-associated pyloric dysfunction, which might help in the management of human H. pylori manifestations and complications.NEW & NOTEWORTHY This work is investigating functional, histopathological, and molecular changes underlying Helicobacter pylori hypomotility and is correlating these with miR-1, whose disturbance is supposed to be involved in smooth muscle dysfunction and cell proliferation according to literature. Epithelial to mesenchymal transition and reduced ghrelin hormone may contribute to H. pylori infection-associated hypomotility. H. pylori infection was associated with reduced pyloric miR-1 expression. Targeting miR-1 could be valuable in the clinical management of pyloric hypofunction.

Evaluation by different mechanisms of the protective effects of vitamin B12 on methotrexate nephrotoxicity

Methotrexate is used for cure of many cancer types. It has many side effects. For this reason, obtaining a nephroprotective agent is obligatory. In the study, our aim is to determine probable effects of Vitamin B12 on MTX caused kidney damages in rats. Rats were randomly divided into 4 groups, including 8 animals in each group. Control group, VitB12 group (3 μg-kg-ip B12 throughout 15 days), MTX group (at the 8th day of experiment, a single dose of 20 mg-kg-ip MTX), Vit B12 + MTX group (3 μg-kg-ip B12 throughout 15 days and at the 8th day of experiment, a single dose of 20 mg-kg-ip MTX) Animals were anesthetized and kidney tissues were removed to evaluate biochemically, immunohistochemically and histopathologycally. There were histopathological deteriorations, rises of apoptotic cells, expressions of heat shock proteins, endoplasmic reticulum stress and inflammation markers in the MTX group. In the MTX group, Superoxide Dismutase (SOD), Total Antioxidant Status (TAS) and Catalase (CAT) levels decreased, but Total Oxidant Status TOS, Malondialdehyde (MDA) and interleukin-6 (IL6) levels increased. In addition, there was amelioration in kidney tissue in Vit B12 + MTX group compared to the MTX group. We suggest that Vit B12 can be used to reduce the toxic effects of MTX.

Sodium-glucose cotransporter 2 inhibition prevents renal fibrosis in cyclosporine nephropathy

AIMS

Sodium-glucose cotransporter 2 (SGLT2) inhibitors, a new class of antidiabetic drugs, are nephroprotective in case of diabetes, but whether a similar beneficial effect may be detectable also in case of chronic non-diabetic kidney diseases remains still unknown. The aim of this study was to evaluate the effects of empagliflozin, a SGLT-2 inhibitor, on the progression of cyclosporine nephropathy, in the absence of diabetes.

METHODS

Sprague Dawley rats (n = 27) have been fed with low-salt diet starting 10 days before the beginning and finished at the end of the experimental period. Cyclosporine-A (CsA, 15 mg/kg/day, intraperitoneal injection, n = 8) and CsA plus empagliflozin (Empa, 10 mg/kg/day, per os, n = 7) were administered for 4 weeks. The control groups were treated with placebo (Control, n = 7) or empagliflozin (Control + Empa, n = 5). Blood pressure (plethysmographic method) was measured at the beginning and at the end of the experimental period. At the end of the experimental protocol, the kidneys were excised for histomorphometric analysis of renal fibrosis and for immunohistochemical evaluation of inflammatory infiltrates (monocytes/macrophages), type I and type IV collagen expression, and tyrosine hydroxylase expression, used as marker of sympathetic nerve activity.

RESULTS

CsA-treated rats showed a significant increase (p < 0.01) in blood pressure, which was reduced by administration of empagliflozin (p < 0.05). CsA administration caused an increase in glomerular and tubulo-interstitial fibrosis (p < 0.05), renal inflammatory infiltrates (p < 0.05), type I and type IV collagen expression (p < 0.01), and tyrosine hydroxylase expression (p < 0.01) as compared to the control rats and control + Empa-treated rats. Treatment with empagliflozin in CsA-treated rats reduced glomerular (p < 0.01) and tubulo-interstitial fibrosis (p < 0.05), type I and type IV collagen expression (p < 0.01), inflammatory cell infiltration (p < 0.01) and tyrosine hydroxylase expression (p < 0.05), as compared to rats treated with CsA.

CONCLUSION

Empagliflozin administration caused a reduction in blood pressure in CsA-treated rats and showed a protective effect on CsA nephropathy by decreasing renal fibrosis, type I and type IV collagen expression, macrophage infiltration and tyrosine hydroxylase expression. These data suggest that empagliflozin promotes nephroprotection also in non-diabetic kidney disease.

Ac2-26 mimetic peptide of annexin A1 to treat severe COVID-19: A hypothesis

The Coronavirus Diseases-2019 (COVID-19) pandemic leads many researchers around the world to study the SARS-CoV-s2 infection and pathology to find a treatment for it. This generates a massive production of papers including pre-clinical, clinical and revisions but till now no specific treatment were identified. Meanwhile, like other coronavirus infections, COVID-19 leads to the cytokine storm syndrome resulting in hyperinflammation, exacerbated immune response and multiple organ dysfunctions indicating that drugs that modulate this response, as glucocorticoids could be a treatment option. However glucocorticoids have several side effects or usage limitations. In this sense a drug with anti-inflammatory effects and capable to reduce inflammation but with less after-effects could be a powerful tool to combat COVID-19. Thus the Ac2-26 Mimetic Peptide of Annexin A1 emerges as a possible therapy. The peptide has many anti-inflammatory effects described including the reduction of interleukin (IL)-6, one of the main mediators of cytokine storm syndrome. Therefore the hypothesis to use the Ac2-26 peptide to treat severe COVID-19 will be highlighted in this paper.

Nicorandil prevents the nephrotoxic effect of cyclosporine-A in albino rats through modulation of HIF-1α/VEGF/eNOS signaling

Despite that cyclosporine-A (CsA) is a widely used immunosuppressive drug, its nephrotoxic effect limits its long-term administration. Herein we tried to investigate its renal effect on endothelial dysfunction targeting the hypoxia-inducible factor (HIF-1α) / vascular endothelial growth factor (VEGF) / endothelial nitric oxide synthase (eNOS) pathway and the possible modulation by nicorandil. Eight groups of adult male Wistar rats were included: (1) control; (2) vehicle group (received oil); (3) glibenclamide 5 mg·kg^-1·day^-1 administered orally; (4) nicorandil 10 mg·kg^-1·day^-1 administered orally; (5) CsA 25 mg·kg^-1·day^-1 administered orally; (6) combined administration of CsA and nicorandil; (7) glibenclamide was added to CsA; and (8) both CsA and nicorandil were combined with glibenclamide. The treatment continued for six weeks. Combined nicorandil with CsA improved renal function deterioration initiated by CsA. CsA decreased the renal expression levels (P < 0.001) of HIF-1α, eNOS, and VEGF, inducing endothelial dysfunction and triggering inflammation, and upregulated the profibrotic marker transforming growth factor (TGF-β). Nicorandil fixed the disturbed HIF-1α/VEGF/eNOS signaling. Nicorandil corrected the renal functions, confirmed by the improved histological glomerular tuft retraction that was obvious in the CsA group, without significant influence by glibenclamide. Proper protection from CsA-induced nephrotoxicity was achieved by nicorandil. Nicorandil reversed the disturbed HIF-1α/VEGF/eNOS pathway created by CsA.

Pharmacological treatment with galectin-1 protects against renal ischaemia-reperfusion injury

Galectin-1 protein (GAL-1) has important anti-inflammatory properties, but related pharmacologic approaches to effectively treat or prevent renal ischaemia and reperfusion injury are highly limited. Here, we investigated the effect of GAL-1 in a renal ischaemia-reperfusion injury rat model and an in vitro hypoxia-reoxygenation model with a proximal renal tubular epithelial cell line. In vivo, pretreatment with GAL-1 attenuated the renal parameters changed by ischaemia-reperfusion/hypoxia-reoxygenation, with recovery of renal function, protecting against influx of leukocytes, cell death and oxidative stress. Ischaemia-reperfusion/hypoxia-reoxygenation was also associated with increased renal endogenous expression of GAL-1 and intercellular adhesion molecule 1 (ICAM-1) plus augmented levels of proinflammatory cytokines IL-1β, TNF-α and MCP-1 and decreased anti-inflammatory IL-10 in urine, all of which were abrogated by GAL-1 treatment. In vitro studies demonstrated renal tubular epithelial cells as an important source of GAL-1 during hypoxia-reoxygenation and confirmed the protective effects of exogenous GAL-1 through downregulation of proinflammatory cytokine release by proximal renal tubular epithelial cells. Collectively, our findings confirm the important anti-inflammatory role of GAL-1 in kidney ischaemia and reperfusion injury and indicate its promising use as a therapeutic approach.

Molecular basis of the counteraction by calcium channel blockers of cyclosporine nephrotoxicity

Nephrotoxicity is a serious side effect for the immunosuppressant drug cyclosporine A(CSA). In this study, we tested the hypothesis that administration of calcium channel blockers such as verapamil or nifedipine ameliorates renal CSA-induced renal dysfunction. Furthermore, our study investigates the roles of inflammatory, oxidative, and fibrotic pathways in CSA-induced renal dysfunction. Six groups of male rats ( n = 6/group) were used and received one of the following treatments for seven consecutive days: vehicle (Cremophor EL ip), CSA (25 mg·kg^-1·day^-1 ip), verapamil (2 mg·kg^-1·day^-1 ip), nifedipine (3 mg·kg^-1·day^-1 ip), CSA in the presence or absence of either verapamil, or nifedipine. Biochemical and histomorphometric analyses showed that rats treated with CSA exhibited clear signs of nephrotoxicity that included 1) proteinuria and elevations in serum creatinine and blood urea nitrogen, 2) mesangial expansion, 3) increases in glomerular and tubular type IV collagen expression, and 4) increases in the glomerulosclerosis and tubulointerstitial fibrosis indices. Although the single administration of nifedipine or verapamil had no significant effect on renal pathology, or its biochemical and physiological function, the concurrent use of either calcium channel blockers significantly and equipotently ameliorated the biochemical, morphological, and functional derangements caused by CSA. More importantly, we report that the oxidative (reactive oxygen species production, NADPH-oxidase activity, and dual oxidase 1/2 levels), fibrotic (transforming growth factor-β1 expression), and inflammatory (NF-κB expression) manifestations of renal toxicity induced by CSA were significantly reversed upon administration of nifedipine or verapamil. Together, these results highlight the efficacy of calcium channel-blocking agents in attenuating CSA-induced nephrotoxicity and predisposing biochemical and molecular machineries.

Therapeutic Potential of Annexin A1 in Ischemia Reperfusion Injury

Cardiovascular disease (CVD) continues to be the leading cause of death in the world. Increased inflammation and an enhanced thrombotic milieu represent two major complications of CVD, which can culminate into an ischemic event. Treatment for these life-threatening complications remains reperfusion and restoration of blood flow. However, reperfusion strategies may result in ischemia-reperfusion injury (I/RI) secondary to various cardiovascular pathologies, including myocardial infarction and stroke, by furthering the inflammatory and thrombotic responses and delivering inflammatory mediators to the affected tissue. Annexin A1 (AnxA1) and its mimetic peptides are endogenous anti-inflammatory and pro-resolving mediators, known to have significant effects in resolving inflammation in a variety of disease models. Mounting evidence suggests that AnxA1, which interacts with the formyl peptide receptor (FPR) family, may have a significant role in mitigating I/RI associated complications. In this review article, we focus on how AnxA1 plays a protective role in the I/R based vascular pathologies.

Activation of annexin A1 signalling in renal fibroblasts exerts antifibrotic effects

AIM

The anti-inflammatory protein annexin A1 (AnxA1) and its formyl peptide receptor 2 (FPR2) have protective effects in organ fibrosis. Their role in chronic kidney disease (CKD) has not yet been elucidated. Our aim was to characterize the AnxA1/FPR2 system in models of renal fibrosis.

METHODS

Rats were treated with angiotensin receptor antagonist during the nephrogenic period (ARAnp) to induce late-onset hypertensive nephropathy and fibrosis. Localization and regulation of AnxA1 and FPR2 were studied by quantitative real-time PCR and double labelling immunofluorescence. Biological effects of AnxA1 were studied in cultured renal fibroblasts from AnxA1(-/-) and wild-type mice.

RESULTS

Angiotensin receptor antagonist during the nephrogenic period kidneys displayed matrix foci containing CD73(+) fibroblasts, alpha-smooth muscle actin (a-SMA)(+) myofibroblasts and CD68(+) macrophages. TGF-β and AnxA1 mRNAs were ~threefold higher than in controls. AnxA1 was localized to macrophages and fibroblasts; myofibroblasts were negative. FPR2 was localized to fibroblasts, myofibroblasts, macrophages and endothelial cells. AnxA1 and FPR2 immunoreactive signals were increased in the foci, with fibroblasts and macrophages expressing both proteins. AnxA1(-/-) fibroblasts revealed higher α-SMA (sevenfold) and collagen 1A1 (Col1A1; 144-fold) mRNA levels than controls. Treatment of murine WT fibroblasts with TGF-β (22.5 ng mL 24 h(-1)) increased mRNA levels of α-SMA (9.3-fold) and Col1A1 (fourfold). These increases were greatly attenuated upon overexpression of AnxA1 (1.5- and 1.7-fold, respectively; P < 0.05). Human fibroblasts reacted similarly when receiving the FPR2 inhibitor WRW4.

CONCLUSION

Our results demonstrate that AnxA1 and FPR2 are abundantly expressed in the renal interstitium and modulate fibroblast phenotype and extracellular matrix synthesis activity.

Ac2-26 Mimetic Peptide of Annexin A1 Inhibits Local and Systemic Inflammatory Processes Induced by Bothrops moojeni Venom and the Lys-49 Phospholipase A2 in a Rat Model

Annexin A1 (AnxA1) is an endogenous glucocorticoid regulated protein that modulates anti-inflammatory process and its therapeutic potential has recently been recognized in a range of systemic inflammatory disorders. The effect of the N-terminal peptide Ac2-26 of AnxA1 on the toxic activities of Bothrops moojeni crude venom (CV) and its myotoxin II (MjTX-II) were evaluated using a peritonitis rat model. Peritonitis was induced by the intraperitoneal injection of either CV or MjTX-II, a Lys-49 phospholipase A2. Fifteen minutes after the injection, the rats were treated with either Ac2-26 or PBS. Four hours later, the CV and MjTX-II-induced peritonitis were characterized by neutrophilia (in the peritoneal exudate, blood and mesentery) and increased number of mesenteric degranulated mast cells and macrophages. At 24 hours post-injection, the local inflammatory response was attenuated in the CV-induced peritonitis while the MjTX-II group exhibited neutrophilia (peritoneal exudates and blood). Ac2-26 treatment prevented the influx of neutrophils in MjTX-II-induced peritonitis and diminished the proportion of mesenteric degranulated mast cells and macrophages in CV-induced peritonitis. Additionally, CV and MjTX-II promoted increased levels of IL-1β and IL-6 in the peritoneal exudates which were significantly reduced after Ac2-26 treatment. At 4 and 24 hours, the endogenous expression of AnxA1 was upregulated in the mesenteric neutrophils (CV and MjTX-II groups) and mast cells (CV group). In the kidneys, CV and MjTX-II administrations were associated with an increased number of macrophages and morphological alterations in the juxtamedullary nephrons in proximal and distal tubules. Ac2-26 promoted significant recovery of the juxtamedullary structures, decreased the number of macrophages and diminished the AnxA1 in epithelial cells from distal tubules and renal capsules. Our results show that Ac2-26 treatment significantly attenuates local and systemic inflammatory processes and indicate this peptide as a potential target for the development of new therapeutic strategies for the snakebite envenomation treatment.

Hydrogen sulphide as a novel therapy to ameliorate cyclosporine nephrotoxicity

BACKGROUND

Calcineurin inhibitors have significant nephrotoxic side effects, which can exacerbate ischemia-reperfusion injury in renal transplantation. Novel therapeutic agents such as hydrogen sulphide (H₂S) may reduce these harmful effects. This study investigated the effects of H₂S on cyclosporine (CsA) induced nephrotoxicity.

MATERIALS AND METHODS

Porcine kidneys were subjected to 15 min of warm ischemia and 2 h of static cold storage. They were reperfused for 3 h with oxygenated normothermic autologous whole blood on an isolated organ reperfusion apparatus. Kidneys were treated with CsA during reperfusion (n = 6) or cyclosporine and 0.25 mmol/L of H₂S infused 10 min before and 20 min after reperfusion (n = 6). These were compared with untreated controls (n = 7).

RESULTS

CsA caused a significant reduction in renal blood flow during reperfusion, which was reversed by H₂S (area under the curve renal blood flow CsA 257 ± 93 versus control 477 ± 206 versus CsA + H₂S 478 ± 271 mL/min/100 g.h; P = 0.024). Urine output was higher after 2 h of reperfusion in the CsA + H₂S group (CsA + H₂S 305 ± 218 versus CsA 78 ± 180 versus control 210 ± 45 mL; P = 0.034). CsA treatment was associated with an increase in tubular injury, which was not reversed by H₂S (area under the curve fractional excretion of sodium, control 77 ± 53 versus CsA 100 ± 61 versus CsA + H2S 111 ± 57%.h; P = 0.003). Histologic evaluation showed significant vacuolation and glomerular shrinkage in the CsA group. These were significantly reduced by H₂S (P = 0.005, 0.002).

CONCLUSIONS

H₂S reversed the vasoconstriction changes associated with CsA treatment during reperfusion.

Hesperidin protects against cyclophosphamide-induced hepatotoxicity by upregulation of PPARγ and abrogation of oxidative stress and inflammation

The most important reason for the non-approval and withdrawal of drugs by the Food and Drug Administration is hepatotoxicity. Therefore, this study was undertaken to evaluate the protective effects of hesperidin against cyclophosphamide (CYP)-induced hepatotoxicity in Wistar rats. The rats received a single intraperitoneal dose of CYP of 200 mg/kg body mass, followed by treatment with hesperidin, orally, at doses of 25 and 50 mg/kg for 11 consecutive days. CYP induced hepatic damage, as evidenced by the significantly elevated levels of serum pro-inflammatory cytokines, serum transaminases, liver lipid peroxidation, and nitric oxide. As a consequence, there was reduced glutathione content, and the activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase, were markedly reduced. In addition, CYP administration induced a considerable downregulation of peroxisome proliferator activated receptor gamma (PPARγ) and upregulation of nuclear factor-kappa B (NF-κB) and inducible nitric oxide synthase (iNOS) mRNA expression. Hesperidin, in a dose-dependent manner, rejuvenated the altered markers to an almost normal state. In conclusion, hesperidin showed a potent protective effect against CYP-induced oxidative stress and inflammation leading to hepatotoxicity. The study suggests that hesperidin exerts its protective effect against CYP-induced hepatotoxicity through upregulation of hepatic PPARγ expression and abrogation of inflammation and oxidative stress.

A screen for apoptotic synergism between clinical relevant nephrotoxicant and the cytokine TNF-α

Nephrotoxicity remains one of the main reasons for post-market drug withdrawal. Tumour necrosis factor α (TNF-α) secretion has been shown to underlie the nephrotoxicity induced by some of these drugs. Yet, there is currently no reliable and sensitive in vitro assay available to screen for nephrotoxicants of which toxicity largely depends on TNF-α secretion. Therefore, we developed and applied a sensitive fluorescence-based in vitro assay for TNF-α-mediated nephrotoxicity screening using mouse immortalized proximal tubular epithelial cells (IM-PTECs). Our assay allows rapid evaluation of TNF-α-mediated toxicant-induced apoptosis and necrosis using fixed endpoint and live cell measurements. To evaluate our assay, sixteen nephrotoxicants and two control non-nephrotoxicants were used. Out of the sixteen nephrotoxicants, eight induced cell death, of which five induced apoptosis as well as necrosis. Moreover, TNF-α significantly enhanced apoptotic cell death induced by cisplatin, cyclosporine A, tacrolimus and azidothymidine. These nephrotoxicants are known to induce inflammation in vivo which has been linked to an enhancement of nephrotoxicity for cisplatin, cyclosporine A and tacrolimus, confirming the functionality of our assay. Overall, our assay allows rapid and sensitive measurement of apoptosis and necrosis induced by a combination of nephrotoxicants and inflammatory components such as TNF-α and can be used as an alternative assay for nephrotoxicity prediction in vitro.

The essential role of annexin A1 mimetic peptide in the skin allograft survival

Immunosuppressive drugs have a critical role in inhibiting tissue damage and allograft rejection. Studies have demonstrated the anti-inflammatory effects of the annexin A1 (AnxA1) in the regulation of transmigration and apoptosis of leucocytes. In the present study, an experimental skin allograft model was used to evaluate a potential protective effect of AnxA1 in transplantation survival. Mice were used for the skin allograft model and pharmacological treatments were carried out using either the AnxA1 mimetic peptide Ac2-26, with or without cyclosporine A (CsA), starting 3 days before surgery until rejection. Graft survival, skin histopathology, leucocyte transmigration and expression of AnxA1 and AnxA5 post-transplantation were analysed. Pharmacological treatment with Ac2-26 increased skin allograft survival related with inhibition of neutrophil transmigration and induction of apoptosis, thereby reducing the tissue damage compared with control animals. Moreover, AnxA1 and AnxA5 expression increased after Ac2-26 treatment in neutrophils. Interestingly, the combination of Ac2-26 and cyclosporine A showed similar survival of transplants when compared with the cyclosporine A group, which could be attributed to a synergistic effect of both drugs. Investigations in vitro revealed that cyclosporine A inhibited extracellular-signal-regulated kinase (ERK) phosphorylation induced by Ac2-26 in neutrophils. Overall, the results suggest that AnxA1 has an essential role in augmenting the survival of skin allograft, mainly owing to inhibition of neutrophil transmigration and enhancement of apoptosis. This effect may lead to the development of new therapeutic approaches relevant to transplant rejection.

Aldosterone signaling through transient receptor potential melastatin 7 cation channel (TRPM7) and its α-kinase domain

We demonstrated a role for the Mg(2+) transporter TRPM7, a bifunctional protein with channel and α-kinase domains, in aldosterone signaling. Molecular mechanisms underlying this are elusive. Here we investigated the function of TRPM7 and its α-kinase domain on Mg(2+) and pro-inflammatory signaling by aldosterone. Kidney cells (HEK-293) expressing wild-type human TRPM7 (WThTRPM7) or constructs in which the α-kinase domain was deleted (ΔKinase) or rendered inactive with a point mutation in the ATP binding site of the α-kinase domain (K1648R) were studied. Aldosterone rapidly increased [Mg(2+)]i and stimulated NADPH oxidase-derived generation of reactive oxygen species (ROS) in WT hTRPM7 and TRPM7 kinase dead mutant cells. Translocation of annexin-1 and calpain-II and spectrin cleavage (calpain target) were increased by aldosterone in WT hTRPM7 cells but not in α-kinase-deficient cells. Aldosterone stimulated phosphorylation of MAP kinases and increased expression of pro-inflammatory mediators ICAM-1, Cox-2 and PAI-1 in Δkinase and K1648R cells, effects that were inhibited by eplerenone (mineralocorticoid receptor (MR) blocker). 2-APB, a TRPM7 channel inhibitor, abrogated aldosterone-induced Mg(2+) responses in WT hTRPM7 and mutant cells. In 2-APB-treated ΔKinase and K1648R cells, aldosterone-stimulated inflammatory responses were unchanged. These data indicate that aldosterone stimulates Mg(2+) influx and ROS production in a TRPM7-sensitive, kinase-insensitive manner, whereas activation of annexin-1 requires the TRPM7 kinase domain. Moreover TRPM7 α-kinase modulates inflammatory signaling by aldosterone in a TRPM7 channel/Mg(2+)-independent manner. Our findings identify novel mechanisms for non-genomic actions of aldosterone involving differential signaling through MR-activated TRPM7 channel and α-kinase.