Activation of renal haeme oxygenase-1 alleviates gentamicin-induced acute nephrotoxicity in rats

Heme Oxygenase-1 as Therapeutic Target for Diabetic Foot Ulcers

A diabetic foot ulcer (DFU) is one of the major complications of diabetes. Wound healing under diabetic conditions is often impaired. This is in part due to the excessive oxidative stress, prolonged inflammation, immune cell dysfunction, delayed re-epithelialization, and decreased angiogenesis present at the wound site. As a result of these multifactorial impaired healing pathways, it has been difficult to develop effective therapeutic strategies for DFU. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme in heme degradation generating carbon monoxide (CO), biliverdin (BV) which is converted into bilirubin (BR), and iron. HO-1 is a potent antioxidant. It can act as an anti-inflammatory, proliferative, angiogenic and cytoprotective enzyme. Due to its biological functions, HO-1 plays a very important role in wound healing, in part mediated through the biologically active end products generated by its enzymatic activity, particularly CO, BV, and BR. Therapeutic strategies involving the activation of HO-1, or the topical application of its biologically active end products are important in diabetic wound healing. Therefore, HO-1 is an attractive therapeutic target for DFU treatment. This review will provide an overview and discussion of the importance of HO-1 as a therapeutic target for diabetic wound healing.

Angiotensin 1-7 mitigates rhabdomyolysis induced renal injury in rats via modulation of TLR-4/NF-kB/iNOS and Nrf-2/heme‑oxygenase-1 signaling pathways

AIMS

Rhabdomyolysis (RM) is a critical condition with a high mortality rate, but effective management is still deficient. Till date, there are no studies that have addressed the effect of angiotensin 1-7 in this condition, hence, the rationale of this study was to evaluate the potential protective effect of Angiotensin 1-7 (Ang1-7), on rhabdomyolysis (RM) induced kidney injury in rats and detecting the underlying mechanistic insights.

MAIN METHODS

Forty adult male albino rats were divided into groups; the control group, RM group, RM+Ang1-7 group, and RM+Ang1-7+ A779 group. Sera and urine samples were collected for analysis of renal and muscle injury markers. Kidney tissues were taken for estimation of oxidative, inflammatory, and apoptotic markers as well as angiotensin-II (Ang II) and Ang1-7. Renal histology and expression of inducible nitric oxide synthase-1 (iNOS), real-time PCR for angiotensin-converting enzyme-2 (ACE-2), nuclear erythroid factor-2 (Nrf-2), Toll like receptor 4 (TLR-4) and NF-kB in kidney tissues were also measured.

KEY FINDINGS

Induction of RM caused renal oxidative stress injury, inflammation, apoptosis and marked deterioration in kidney functions as well as reduction of Ang1-7 and raised Angiotensin-II level in kidney tissues. Administration of Ang1-7 to the RM group reversed all the affected parameters which were blocked by A779 administration (Mas receptor blocker).

SIGNIFICANCE

We concluded that Ang1-7 could be a potential therapeutic agent that could mitigate RM-induced renal injury. The underlying mechanisms may involve Stimulation of the ACE-2/Ang1-7/MasR axis and modulation of TLR-4/NF-kB/iNOS and Nrf-2/heme‑oxygenase -1 pathways.

Hydrogen sulfide renal protective effects: possible link between hydrogen sulfide and endogenous carbon monoxide in a rat model of renal injury

Hydrogen sulfide (H2S), along with nitric oxide (NO) and carbon monoxide (CO), proved to have renoprotective effects in various renal diseases. Therefore, this study investigated the renoprotective effect of H2S, in a renal injury model, and its crosstalk with other gasotransmitters such as CO. Thirty-two adult rats were divided into four groups: control, gentamicin (GEN)-treated, GEN + sodium hydrosulfide (NaHS), and GEN + NaHS + zinc protoporphyrin (ZnPP) groups. GEN was used to induce renal injury, NaHS is a water-soluble H2S, and ZnPP is a selective heme oxygenase-1 (HO-1) inhibitor used to inhibit CO synthesis in vivo. NaHS improved kidney functions in the GEN group as evidenced by significantly lower levels of renal injury markers: serum urea, creatinine, uric acid, urinary albumin excretion, and urinary albumin/creatinine. Moreover, NaHS administration to the GEN-treated group significantly lowered renal levels of NO and tumor necrosis factor-α with an increase in total antioxidant, HO-1, and interleukin-10 levels. Furthermore, NaHS administration downregulated the GEN-induced overexpression of the renal inducible nitric oxide synthase (iNOS) and upregulated the suppression of endothelial nitric oxide synthase (eNOS) with improvement in the histological examination and periodic acid Schiff (PAS) staining. However, this improvement in kidney function produced by NaHS was reduced by combination with ZnPP but still improved as compared with the GEN-treated group. The renoprotective effects of H2S can be through its effects on renal tissue antioxidants, pro-inflammatory and anti-inflammatory cytokines, and expression of eNOS and iNOS which can be partially dependent on CO pathway via induction of HO-1 enzyme.

Hemin attenuated oxidative stress and inflammation to improve wound healing in diabetic rats

Oxidative stress and persistent inflammation play crucial role in the progression of diabetic wound complications. Hemeoxgenase-1 (HO-1) by degrading hemin has been shown to display anti-oxidant and anti-inflammatory effects. Further, hemin is a potent HO-1 inducer. Thus, the current study was aimed to evaluate the effect of topical application of hemin on diabetic wound in rats. Four hundred square millimeter open excision wound were created 2 weeks after induction of diabetes with single intraperitoneal injection of streptozotocin (60 mg/kg), and the diabetic rats were divided into three groups namely diabetic control, hemin, and tin protoporphyrin (SnPPIX). Ointment base, hemin (0.5% in ointment base), and SnPPIX (0.5% in ointment base) were applied topically to wounded area in diabetic control, hemin, and SnPPIX group rats, respectively, twice daily for 19 days. Hemin significantly increased the wound contraction in comparison to control and SnPPIX-treated rats. Time-dependent analysis revealed significant increase in anti-oxidants with concomitant decrease in oxidants in hemin-treated rats as compared to diabetic control rats. Further, mRNA expression decreased for inflammatory cytokine and increased for anti-inflammatory cytokine in hemin group as compared to diabetic control rats. Expression of HO-1 also increased in hemin group as compared to diabetic control rats. However, SnPPIX group results were in disagreement with results of hemin which is clearly reflected in histopathology. Results indicate the ability of hemin to accelerate wound healing in diabetic rats by combating inflammation and oxidative stress probably via HO-1.

Curcumin Attenuates on Carbon Tetrachloride-Induced Acute Liver Injury in Mice via Modulation of the Nrf2/HO-1 and TGF-β1/Smad3 Pathway

This study aimed to investigate the protective effect of curcumin against carbon tetrachloride (CCl₄)-induced acute liver injury in a mouse model, and to explain the underlying mechanism. Curcumin at doses of 50, 100 and 200 mg/kg/day were administered orally once daily for seven days prior to CCl₄ exposure. At 24 h, curcumin-attenuated CCl₄ induced elevated serum transaminase activities and histopathological damage in the mouse's liver. Curcumin pre-treatment at 50, 100 and 200 mg/kg significantly ameliorated CCl₄-induced oxidative stress, characterized by decreased malondialdehyde (MDA) formations, and increased superoxide dismutase (SOD), catalase (CAT) activities and glutathione (GSH) content, followed by a decrease in caspase-9 and -3 activities. Curcumin pre-treatment significantly decreased CCl₄-induced inflammation. Furthermore, curcumin pre-treatment significantly down-regulated the expression of TGF-β1 and Smad3 mRNAs (both p < 0.01), and up-regulated the expression of nuclear-factor erythroid 2-related factor 2 (Nrf2) and HO-1 mRNA (both p < 0.01) in the liver. Inhibition of HO-1 attenuated the protective effect of curcumin on CCl₄-induced acute liver injury. Given these outcomes, curcumin could protect against CCl₄-induced acute liver injury by inhibiting oxidative stress and inflammation, which may partly involve the activation of Nrf2/HO-1 and inhibition of TGF-β1/Smad3 pathways.

Protein extracted from Porphyra yezoensis prevents cisplatin-induced nephrotoxicity by downregulating the MAPK and NF-κB pathways

Acute renal failure is a serious complication of treatment with the anticancer drug cisplatin. Cisplatin exerts a cytotoxic effect on renal cells by inducing apoptosis through activating the tumor suppressor p53, nuclear factor‑κB (NF‑κB) and mitogen‑activated protein kinase (MAPK)/p38 pathways. Effects of protein extracts of the brown seaweed Porphyra yezoensis (P. yezoensis) on cytotoxicity, inflammation and cell proliferation have been reported; however, the effects of P. yezoensis protein (PYP) extract on cisplatin‑induced renal injury have remained elusive. The present study investigated the effects of PYP on cisplatin‑induced nephrotoxicity in the HK2 human proximal tubular epithelial cell line. PYP treatment reduced cisplatin‑induced apoptosis and death of HK2 cells by restoring the B‑cell lymphoma‑2 (Bcl‑2)‑associated X protein (Bax)/Bcl‑2 imbalance, cytochrome c release and caspase‑3 activation. In addition, PYP activated the redox‑sensitive transcription factor NF‑κB via stimulating the nuclear translocation of p65 in HK2 cells. PYP also restored renal antioxidant levels and increased the total and nuclear accumulation of NF erythroid 2‑related factor 2 in HK2 cells. PYP markedly attenuated cisplatin‑induced p38, MAPK and c‑Jun N‑terminal kinase phosphorylation. Furthermore, treatment with PYP ameliorated cisplatin‑induced renal cell damage by upregulating antioxidant defense mechanisms and downregulating the MAPK and NF‑κB signaling pathways. In addition, mice were divided into three treatment groups (control, cisplatin and PYP + cisplatin) and the effects of PYP were evaluated in a mouse model of cisplatin‑induced acute kidney injury. The concentrations of blood urea nitrogen and serum creatinine in the PYP + cisplatin group were lower than those in the cisplatin group. The mRNA expression levels of inflammatory factors interleukin‑6 (IL‑6), IL‑1β, tumor necrosis factor‑α and monocyte chemoattractant protein‑1 in the kidney tissues of the PYP + cisplatin group were also lower than those in the cisplatin group. These results suggest that PYP treatment had a preventive effect on nephrotoxicity, specifically by downregulating the MAPK and NF‑κB signaling pathways and the mRNA levels of inflammatory genes.

Modulation of heme oxygenase-1 expression and activity affects streptozotocin-induced diabetic nephropathy in rats

Heme oxygenase (HO)-1 has exhibited nephro-protective actions in different animal models; however, its full mechanistic potential in diabetic nephropathy (DN) has not yet been elucidated. Hence, the present study has been undertaken by inducing DN in rats using streptozotocin (50 mg/kg i.p.), with or without either HO-1 inducer; hemin (HM; 40 μmol/kg, s.c.), or HO-1 blocker; zinc protoporphyrin-IX (ZnPP; 50 μmol/kg, i.p.), for one month. Compared to control, rats with DN suffered from hyperglycemia and hyperlipidemia, with signs of renal damage, as assessed by distortion in renal histopathologic architecture and kidney function. Renal oxidative/nitrosative stress was evident by increased malondialdehyde, nitric oxide, myeloperoxidase, with decreased reduced glutathione, superoxide dismutase, and catalase. DN group also exhibited high renal expression of the pro-inflammatory cytokine; tumor necrosis factor (TNF)-α, and the apoptotic marker; caspase 3, assessed by Western blot. Renal HO-1 protein expression and activity were increased in DN rats compared to control. Administration of HM, but not ZnPP, to DN rats improved kidney function, histopathologic features, lipid profile, TNF-α, and caspase 3 expressions, with no effect on blood glucose level. HM increased, while ZnPP decreased renal HO-1 activity in DN rats. It is noteworthy that neither intervention affected HO-1 activity or renal oxidative capacity in non-diabetic rats. Interestingly, the expression of HO-1 was upregulated by both HM and ZnPP in DN rats. In conclusion, activation of HO-1 via HM ameliorated renal damage in STZ-induced DN in rats, probably through antioxidant, anti-nitrosative, anti-inflammatory, and anti-apoptotic mechanisms.

Vascular function and arginine and dimethylarginines in gentamicin-induced renal failure: a possible effect of heme oxygenase 1 inducer hemin

Increased oxidative stress and disturbance in nitric oxide bioavailability lead to endothelial dysfunction and cardiovascular complication in renal disease. Gentamicin (GM), a commonly used antibiotic, exhibits a toxic effect on renal proximal tubules. Prevention of its nephrotoxicity is important. Therefore, we investigated whether heme oxygenase 1 HO-1) induction influenced kidney and vascular function in GM-administered rats. GM (100 mg·kg^-1·day^-1; i.p.) was given to rats alone or together with hemin (20 mg·kg^-1 on alternate days; i.p.) for 14 days. Plasma and kidney l-arginine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) as well as kidney 4-hydroxynonenal (HNE) levels and myeloperoxidase (MPO) activity were measured. Histopathological examinations of kidney and relaxation and contraction responses of aorta were also examined. GM increased serum SDMA, urea nitrogen (BUN), and creatinine levels and caused histopathological alterations in the kidney. GM elevated HO-1 protein and mRNA expressions, 4-HNE level, and MPO activity and decreased antioxidant enzyme activities and l-arginine levels in the kidney. Decreased relaxation and contraction were detected in the aorta. Hemin restored renal oxidative stress and inflammatory changes together with vascular dysfunction, but did not affect SDMA, BUN, or creatinine levels. We conclude that HO-1 induction may be effective in improving renal oxidative stress, inflammation, and vascular dysfunction mediated by GM.

Eff ects of hemin, a heme oxygenase-1 inducer in L-arginine-induced acute pancreatitis and associated lung injury in adult male albino rats

Objective. The aim of the current study was to assess the protective outcome of hemin, a heme oxygenase-1 (HO-1) inducer on L-arginine-induced acute pancreatitis in rats. Acute pancreatitis (AP) is considered to be a critical inflammatory disorder with a major impact on the patient health. Various theories have been recommended regarding the pathophysiology of AP and associated pulmonary complications.

Methods. Twenty-four adult male albino rats were randomly divided into four groups: control group, acute pancreatitis (AP), hemin pre-treated AP group, and hemin post-treated AP group.

Results. Administration of hemin before induction of AP significantly attenuated the L-arginine- induced pancreatitis and associated pulmonary complications characterized by the increasing serum levels of amylase, lipase, tumor necrosis factor-α, nitric oxide, and histo-architectural changes in pancreas and lungs as compared to control group. Additionally, pre-treatment with hemin significantly compensated the deficits in total antioxidant capacities and lowered the elevated malondialdehyde levels observed with AP. On the other hand, post-hemin administration did not show any protection against L-arginine-induced AP.

Conclusions. The current study indicates that the induction of HO-1 by hemin pre-treatment significantly ameliorated the L-arginine-induced pancreatitis and associated pulmonary complications may be due to its anti-inflammatory and antioxidant properties.

Heme Oxygenase-1 in Kidney Health and Disease

SIGNIFICANCE

Acute kidney injury (AKI) and chronic kidney disease (CKD) represent a considerable burden in healthcare. The heme oxygenase (HO) system plays an important role in regulating oxidative stress and is protective in a variety of human and animal models of kidney disease. Preclinical studies of the HO system have led to the development of several clinical trials targeting the enzyme or its products.

RECENT ADVANCES

Connection of HO, ferritin, and other proteins involved in iron regulation has provided important insight into mechanisms of damage in AKI. Also, HO-1 expression is important in the pathogenesis of hypertension, diabetic kidney disease, and progression to end-stage renal disease.

CRITICAL ISSUES

Despite intriguing discoveries, no drugs targeting the HO system have been translated to the clinic. Meanwhile, treatments for AKI and CKD are urgently needed. Many factors have likely contributed to challenges in clinical translation, including variation in animal models, difficulties in obtaining human tissue, and complexity of the disease processes being studied.

FUTURE DIRECTIONS

The HO system represents a promising avenue of investigation that may lead to targeted therapeutics. Tissue-specific gene modulation, widening the scope of animal studies, and continued clinical research will provide valuable insight into the role HO plays in kidney homeostasis and disease. Antioxid. Redox Signal. 25, 165-183.

Rapamycin protects against gentamicin-induced acute kidney injury via autophagy in mini-pig models

Gentamicin may cause acute kidney injury. The pathogenesis of gentamicin nephrotoxicity is unclear. Autophagy is a highly conserved physiological process involved in removing damaged or aged biological macromolecules and organelles from the cytoplasm. The role of autophagy in the pathogenesis of gentamicin nephrotoxicity is unclear. The miniature pigs are more similar to humans than are those of rodents, and thus they are more suitable as human disease models. Here we established the first gentamicin nephrotoxicity model in miniature pigs, investigated the role of autophagy in gentamicin-induced acute kidney injury, and determined the prevention potential of rapamycin against gentamicin-induced oxidative stress and renal dysfunction. At 0, 1, 3, 5, 7 and 10 days after gentamicin administration, changes in autophagy, oxidative damage, apoptosis and inflammation were assessed in the model group. Compared to the 0-day group, gentamicin administration caused marked nephrotoxicity in the 10-day group. In the kidneys of the 10-day group, the level of autophagy decreased, and oxidative damage and apoptosis were aggravated. After rapamycin intervention, autophagy activity was activated, renal damage in proximal tubules was markedly alleviated, and interstitium infiltration of inflammatory cells was decreased. These results suggest that rapamycin may ameliorate gentamicin-induced nephrotoxicity by enhancing autophagy.

Lycopene attenuates colistin-induced nephrotoxicity in mice via activation of the Nrf2/HO-1 pathway

Nephrotoxicity is the major dose-limiting factor for the clinical use of colistin against multidrug-resistant (MDR) Gram-negative bacteria. This study aimed to investigate the protective effect of lycopene on colistin-induced nephrotoxicity in a mouse model. Fifty mice were randomly divided into 5 groups: the control group (saline solution), the lycopene group (20 mg/kg of body weight/day administered orally), the colistin group (15 mg/kg/day administered intravenously), the colistin (15 mg/kg/day) plus lycopene (5 mg/kg/day) group, and the colistin (15 mg/kg/day) plus lycopene (20 mg/kg/day) group; all mice were treated for 7 days. At 12 h after the last dose, blood was collected for measurements of blood urea nitrogen (BUN) and serum creatinine levels. The kidney tissue samples were obtained for examination of biomarkers of oxidative stress and apoptosis, histopathological assessment, and quantitative reverse transcription-PCR (qRT-PCR) analysis. Colistin treatment significantly increased concentrations of BUN and serum creatinine, tubular apoptosis/necrosis, lipid peroxidation, and heme oxygenase 1 (HO-1) activity, while the treatment decreased the levels of endogenous antioxidant biomarkers glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD). Notably, the changes in the levels of all biomarkers were attenuated in the kidneys of mice treated with colistin by lycopene (5 or 20 mg/kg). Lycopene treatment, especially in the colistin plus lycopene (20 mg/kg) group, significantly downregulated the expression of NF-κB mRNA (P < 0.01) but upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and HO-1 mRNA (both P < 0.01) in the kidney compared with the results seen with the colistin group. Our data demonstrated that coadministration of 20 mg/kg/day lycopene can protect against colistin-induced nephrotoxicity in mice. This effect may be attributed to the antioxidative property of lycopene and its ability to activate the Nrf2/HO-1 pathway.

Hemin attenuates cisplatin-induced acute renal injury in male rats

Background. The aim of this study is to investigate the protective effects of hemin (the heme oxygenase-1 [OH-1] inducer) against nephrotoxic effects induced by cisplatin [cis-diamminedichloroplatinum II (CP)] in male rats. Methods. The evaluation was performed through monitoring renal redox parameters: lipid peroxidation (LPO), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione reductase (GR), and reduced glutathione (GSH). The work also examined renal function tests (urea and creatinine), tissue proinflammatory mediator like nitric oxide (NO), and kidney cytopathology. Results. A single intraperitoneal dose of CP (10 mg/kg b.w.) caused significant elevation of blood urea, serum creatinine, and renal LPO and NO, along with significant decline of the activities of GPx and GR, but renal SOD activity and GSH level were statistically insignificant as compared to control group. Subcutaneous injection of hemin (40 µmol/kg b.w.) partially ameliorated CP-induced renal damage, based on suppression of blood urea, serum creatinine, the renal MDA and NO levels, and increased antioxidant capacity in CP-treated rats. The results of histopathological and ultrastructural investigations supported the renoprotective effect of hemin against CP-induced acute toxicity. Conclusion. The induction of HO-1 by hemin is a promising approach in the treatment of CP-induced nephrotoxicity. However, further preclinical studies are warranted to test effectiveness of CP/hemin on the outcome of tumor chemotherapy.

Serum paraoxonase 1 status and its association with atherogenic indexes in gentamicin-induced nephrotoxicity in rats treated with coenzyme Q10

Coenzyme Q10 is a natural antioxidant and scavenger of free radicals. In the present study, we examined the effect of coenzyme Q10 on paraoxonase 1 (PON1) activity, lipid profile, atherogenic indexes and relationship of PON 1 activity by high-density lipoprotein (HDL) and atherogenic indexes in gentamicin (GM)-induced nephrotoxicity rats. Thirty Sprague-Dawley rats were divided into three groups to receive saline; GM, 100 mg/kg/d; and GM plus coenzyme Q10 by 15 mg/kg i.p daily, respectively. After 12 days, animals were anaesthetized, blood samples were also collected before killing to measure the levels of triglyceride (TG), cholesterol (C), low-density lipoprotein (LDL), very low density lipoprotein (VLDL), HDL, atherogenic indexes and the activities of PON1 of all groups were analyzed. Data were analyzed by non-parametric Mann-Whitney test (using SPSS 13 software). Coenzyme Q10 significantly decreased TG, C, LDL, VLDL, atherogenic index, atherogenic coefficient and cardiac risk ratio. HDL level and PON1 activity were significantly increased when treated with coenzyme Q10. Also, the activity of PON 1 correlated positively with HDL and negatively with atherogenic coefficient, cardiac risk ratio 1 and cardiac risk ratio 2. This study showed that coenzyme Q10 exerts beneficial effects on PON1 activity, lipid profile, atherogenic index and correlation of PON 1 activity with HDL and atherogenic index in GM -induced nephrotoxicity rats.