The potential antifibrotic impact of apocynin and alpha-lipoic acid in concanavalin A-induced liver fibrosis in rats: Role of NADPH oxidases 1 and 4

Apocynin and Hyperbaric Oxygen Therapy Improve Renal Function and Structure in an Animal Model of CKD

BACKGROUND/OBJECTIVES

Chronic kidney disease (CKD) is a progressive pathological condition which results in the severe fibrosis of the kidneys. However, the mechanisms of CKD progression and fibrogenesis remain unclear. We wanted to examine the effects that apocynin and hyperbaric oxygen therapy (HBOT) have on renal function and structure in animals with CKD induced through 5/6 nephrectomy (5/6 Nx-L).

METHODS

Male Wistar rats were divided in 5 groups (n = 8/group) as follows: control-sham-operated rats; Nx-L-rats with 5/6 Nx-L; APO-5/6 Nx-L + apocynin treatment; HBOT-5/6 Nx-L + hyperbaric oxygen treatment, and APO+HBOT-5/6 Nx-L, treated with both treatments. All treatments started 4 weeks after the final step of CKD induction and lasted for 4 weeks. At the end of the experiment, urine samples were collected for the proteinuria assessment and the mean arterial pressure (MAP) was measured. Kidneys were collected for histopathological, Western blot, and immunohistochemical analyses.

RESULTS

All treatments significantly decreased MAP compared to the Nx-L group (p < 0.001). In the APO and APO+HBOT groups, the level of proteinuria was decreased compared to the Nx-L group (p < 0.05 and p < 0.01, respectively). All examined treatments significantly decreased the intensity of lesions in the kidney compared to those observed in the Nx-L group (p < 0.001). Isolated treatments with apocynin and HBOT induced a significant decrease in desmin expression compared to the Nx-L group (p < 0.05); meanwhile, they did not affect the levels of fibronectin (FN) and hypoxia-inducible factor-1α (HIF-1α). Combined treatment did not affect desmin expression levels; however, it induced a significant increase in fibronectin expression compared to Nx-L (p < 0.001).

CONCLUSIONS

Apocynin treatment decreased BP and protein loss, and it improved renal morphology at least partly through the downregulation of desmin expression without changing FN and HIF-1α. Hyperbaric oxygen therapy improved hypertension but failed to significantly affect the level of proteinuria. Combined treatment (apocynin and HBOT) normalized blood pressure (BP) values, renal function, and improved kidney structure by modulating FN and HIF-1α, without affecting desmin protein expression. Further studies are needed to elucidate the mechanisms of slowing down the progression of CKD in this experimental model.

Protective effect of alpha‑lipoic acid against in utero cytarabine exposure-induced hepatotoxicity in rat female neonates

Cytarabine, an anti-metabolite drug, remains the mainstay of treatment for hematological malignancies. It causes various toxic effects including teratogenicity. Alpha lipoic acid (ALA) is a natural antioxidant reported to offer protection against hepatotoxicity induced by various pathological conditions, drugs, or chemicals. We investigated the protective effect of ALA against prenatal cytarabine exposure-induced hepatotoxicity in rat female neonates. A total of 30 dams were randomly assigned to five groups and received normal saline, ALA 200 mg/kg, cytarabine 12.5 mg/kg, cytarabine 25 mg/kg, and cytarabine 25 mg/kg + ALA 200 mg/kg, respectively, from gestational day (GD)8 to GD21. Cytarabine and ALA were administered via intraperitoneal and oral (gavage) routes, respectively. On postnatal day (PND)1, all the live female neonates (pups) were collected and weighed. The blood and liver from pups were carefully collected and used for histopathological, and biochemical evaluations. A significant and dose-dependent decrease in maternal food intake and weight gain was observed in the pregnant rats (dams) of the cytarabine groups as compared to the dams of the control group. The pups exposed to cytarabine showed a significant and dose-dependent (a) decrease in body weight, liver weight, hepatosomatic index, catalase, superoxide dismutase, glutathione, glutathione peroxidase, serum albumin levels and (b) increase in malondialdehyde, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, AST/ALT ratio, and histopathological anomalies. Maternal co-administration of ALA ameliorated these biochemical changes and histopathological abnormalities by combating oxidative stress. Future studies are warranted to explore the molecular mechanisms involved in the ALA's protective effects against prenatal cytarabine-induced hepatotoxicity.

In vitro-in vivo assessments of apocynin-hybrid nanoparticle-based gel as an effective nanophytomedicine for treatment of rheumatoid arthritis

Apocynin (APO), a well-known bioactive plant-based phenolic phytochemical with renowned anti-inflammatory and antioxidant pharmacological activities, has recently emerged as a specific nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) oxidase inhibitor. As far as we know, no information has been issued yet regarding its topical application as a nanostructured-based delivery system. Herein, APO-loaded Compritol® 888 ATO (lipid)/chitosan (polymer) hybrid nanoparticles (APO-loaded CPT/CS hybrid NPs) were successfully developed, characterized, and optimized, adopting a fully randomized design (32) with two independent active parameters (IAPs), namely, CPT amount (XA) and Pluronic® F-68 (PF-68) concentration (XB), at three levels. Further in vitro-ex vivo investigation of the optimized formulation was performed before its incorporation into a gel base matrix to prolong its residence time with consequent therapeutic efficacy enhancement. Subsequently, scrupulous ex vivo-in vivo evaluations of APO-hybrid NPs-based gel (containing the optimized formulation) to scout out its momentous activity as a topical nanostructured system for beneficial remedy of rheumatoid arthritis (RA) were performed. Imperatively, the results support an anticipated effectual therapeutic activity of the APO-hybrid NPs-based gel formulation against Complete Freund's Adjuvant-induced rheumatoid arthritis (CFA-induced RA) in rats. In conclusion, APO-hybrid NPs-based gel could be considered a promising topical nanostructured system to break new ground for phytopharmaceutical medical involvement in inflammatory-dependent ailments.

The Effects of Apocynin on Monosodium Glutamate Induced Liver Damage of Rats

Monosodium glutamate (MSG) is found in refined foods. Apocynin (APO) is a selective NADPH oxidase (NOX) inhibitor. The aim of this experimental study was to investigate possible effects of MSG and the curative effects of APO in rats. Twenty-eight male Sprague-Dawley rats were randomly divided into four groups (Normal control, APO, MSG and MSG + APO, n:7 for each group). The MSG and MSG + APO groups received 120 mg/kg MSG solution orally for 28 consecutive days. The APO and MSG + APO groups received 25 mg/kg APO solution orally for 5 days until the end of the experiment. At the end of the experiment, all rats were sacrificed and liver tissue and blood samples were taken for histological, ultrastructural, and biochemical analyses. In the MSG group, vacuolization and loss in glycogen content in the hepatocytes, leukocyte infiltration and fibrosis in the liver parenchyme and portal triads, were observed. Terminal deoxynucleotidyl transferase dUTP (TUNEL)-positivity and NADPH oxidase (NOX)-2-positivity were higher in the MSG group compared with the other experimental groups. The concentrations of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin, malondialdehyde (MDA), and myeloperoxidase (MPO) were higher, whereas albumin, glutathione (GSH), and superoxide (SOD) levels were lower in the MSG group. All these data has been reversed in MSG + APO group. The histological and biochemical criteria indicated the prominent ameliorating effect of APO on MSG -induced liver injury.

Does apocynin increase liver regeneration in the partial hepatectomy model?

BACKGROUND

Hepayocyte loss may develop secondary to liver surgery and at this point liver regeneration plays a significant act in terms of liver reserve. The purpose of this research was to investigate the efficacy of apocynin on liver regeneration and preservation after partial hepatectomy in rats.

METHODS

A total of 32 rats, have been divided into 4 groups (n: 8) for hepatectomy model. Inflammatory and antiinflammatory parameters were measured from blood and liver tissue samples. In addition, the effects of apocynin were examined immunohistochemically and histopathologically from liver tissue.

RESULTS

In liver tissue samples, a significant difference has been found in glutathione peroxidase, total nitrite, catalase, oxidative stress index, total antioxidant and total oxidant status between sham and hepatectomy groups. A significant difference has been achieved between hepatectomy and posthepatectomy-Apocynin in terms of glutathione peroxidase and oxidative stress index. Total antioxidant status, oxidative stress index, and total oxidant status were significantly different only between the sham and the hepatectomy groups. Statistical differences were found between sham and hepatectomy groups and between hepatectomy and pre+post-hepatectomy-Apocynin groups in terms of serum glutathione, malondialdehyde, total nitrite, and L-Arginine. There were significant differences between the sham and hepatectomy groups, between hepatectomy and posthepatectomy-apocynin groups, between posthepatctomy-apocynin and pre+posthepatectomy-apocynin groups in terms of sinusoidal dilatation, intracytoplasmic vacuolization and glycogen loss (p < 0.001), in all histopathologic parameters except sinusoidal dilatation (p < 0.05). However, significant Ki-67 increases have been elaborated in hepatectomy, posthepatectomy-apocynin, and pre+posthepatectomy-apocynin groups compared to sham group (p < 0.001), in pre+posthepatectomy apocynin group compared to hepatectomy and posthepatectomy-apocynin groups (p < 0.001).

DISCUSSION

Histopathology, immunohistochemistry, and biochemistry results of this study revealed that apocynin has a protective effect on enhancing liver regeneration in partial hepatectomy cases in rats.

A review of edible plant-derived natural compounds for the therapy of liver fibrosis

Liver fibrosis has a high incidence worldwide and is the common pathological basis of many chronic liver diseases. Liver fibrosis is caused by the excessive deposition of extracellular matrix and concomitant collagen accumulation in livers and can lead to the development of liver cirrhosis and even liver cancer. A large number of studies have provided evidence that liver fibrosis can be blocked or even reversed by appropriate medical interventions. However, the antifibrosis drugs with ideal clinical efficacy are still insufficient. The edible plant-derived natural compounds have been reported to exert effective antifibrotic effects with few side-effects, representing a kind of promising source for the treatment of liver fibrosis. In this article, we reviewed the current progress of the natural compounds derived from dietary plants in the treatment of liver fibrosis, including phenolic compounds (capsaicin, chlorogenic acid, curcumin, ellagic acid, epigallocatechin-3-gallate, resveratrol, sinapic acid, syringic acid, vanillic acid and vitamin E), flavonoid compounds (genistein, hesperidin, hesperetin, naringenin, naringin and quercetin), sulfur-containing compounds (S-allylcysteine, ergothioneine, lipoic acid and sulforaphane) and other compounds (betaine, caffeine, cucurbitacin B, lycopene, α-mangostin, γ-mangostin, ursolic acid, vitamin C and yangonin). The pharmacological effects and related mechanisms of these compounds in in-vivo and in-vitro models of liver fibrosis are focused.

NOX as a Therapeutic Target in Liver Disease

The nicotinamide adenine dinucleotide phosphate hydrogen oxidase (NADPH oxidase or NOX) plays a critical role in the inflammatory response and fibrosis in several organs such as the lungs, pancreas, kidney, liver, and heart. In the liver, NOXs contribute, through the generation of reactive oxygen species (ROS), to hepatic fibrosis by acting through multiple pathways, including hepatic stellate cell activation, proliferation, survival, and migration of hepatic stellate cells; hepatocyte apoptosis, enhancement of fibrogenic mediators, and mediation of an inflammatory cascade in both Kupffer cells and hepatic stellate cells. ROS are overwhelmingly produced during malignant transformation and hepatic carcinogenesis (HCC), creating an oxidative microenvironment that can cause different and various types of cellular stress, including DNA damage, ER stress, cell death of damaged hepatocytes, and oxidative stress. NOX1, NOX2, and NOX4, members of the NADPH oxidase family, have been linked to the production of ROS in the liver. This review will analyze some diseases related to an increase in oxidative stress and its relationship with the NOX family, as well as discuss some therapies proposed to slow down or control the disease's progression.

Propitious maneuvering for delivery of the phytopharmaceutical "apocynin" to induced fulminant hepatitis in BALB/c mice: In vitro and in vivo assessments

Apocynin (APO), a specific nicotinamide adenine dinucleotide phosphate-oxidase (NADPH-oxidase, NOX) inhibitor, has recently emerged as a bioactive phytochemical with eminent anti-inflammatory and anti-oxidant activities. To our knowledge, no research has been conducted to fabricate a mucoadhesive nanostructured delivery system of APO that targets the liver. Accordingly, chitosan (CS) surface decorated polymeric nanoparticulate delivery system (PNDS) was victoriously fabricated by double emulsion-solvent evaporation method. Herein, a randomized full 33 factorial design was employed to assess the impact of the independently processing parameters (IPPs) namely; (poly(d,l-lactide-co-glycolide) (PLGA) amount (A)), (polyvinyl alcohol (PVA) concentration (B)), and (CS concentration (C)), on different dependently measured attributes (DMAs). The optimal APO-loaded chitosan-coated poly(d,l-lactide-co-glycolide) nanoparticles (APO-loaded CS-coated PLGA NPs) formula (F19) would be extensively appraised through meticulous in vitro-in vivo studies. Crucially, the results revealed that oral pre-treatment with the optimal formula evoked a prodigious in vivo hepatoprotective efficacy against lipopolysaccharide (LPS)/D-(+)-galactosamine (D-GalN) induced fulminant hepatitis (FH) in BALB/c mice when compared with pure APO, uncoated F19, and plain NPs (P NPs) pretreated groups. In conclusion, APO-loaded CS-coated PLGA NPs could be considered as a promising oral mucoadhesive phytopharmaceutical PNDS to open new prospects for therapeutic intervention in inflammatory based liver diseases.

Protective effects of alpha-lipoic acid on bleomycin-induced skin fibrosis through the repression of NADPH Oxidase 4 and TGF-β1/Smad3 signaling pathways

The aim of this study was to determine the protective effects of alpha-lipoic acid (ALA), which is known as a powerful antioxidant, and the possible related molecular mechanisms that mediate its favorable action on skin fibrosis in the bleomycin (BLM)-induced scleroderma (SSc) model in mice. The experimental design was established with four groups of eight mice: Control, ALA (100 mg/kg), BLM (5 μg/kg), and BLM + ALA group. BLM was administered via subcutaneous (sc) once a day while ALA was injected intraperitoneally (ip) twice a week for 21 days. Histopathological and biochemical analyses showed that ALA significantly reduced BLM-induced dermal thickness, inflammation score, and mRNA expression of tumor necrosis factor-alpha (TNF-α) in the skin. Besides, the mRNA expressions of the subunits of NADPH oxidase, which are Nox4 and p22phox, were found to be significantly induced in the BLM group. However, ALA significantly reduced their mRNA expression, which were in parallel to its decreasing effect on serum total oxidant status (TOS) level. Moreover, it was found that ALA downregulated the mRNA expressions of alpha-smooth muscle actin (α-SMA), collagen type I and fibronectin in the skin tissue of the BLM group. Additionally, it was shown that ALA reduced significantly the TGF-β1 and p-Smad3 protein expressions in the BLM + ALA group. On the other hand, ALA did not exhibit any significant effect on the p38 mitogen-activated kinase (MAPK) activation induced by BLM. All these findings point out that ALA may be a promising treatment for the attenuation of skin fibrosis in SSc patients.

Associations among S100A4, Sphingosine-1-Phosphate, and Pulmonary Function in Patients with Chronic Obstructive Pulmonary Disease

Background. S100A4 is a member of the S100 calcium-binding protein family and is increased in patients with chronic obstructive pulmonary disease (COPD). Sphingosine-1-phosphate (S1P) is a naturally occurring bioactive sphingolipid, which regulates the adhesion between the cells and the extracellular matrix and affects cell migration and differentiation. The goal of this study was to analyze the correlations among S100A4, S1P, and pulmonary function among COPD patients. Methods. All 139 serum samples and 15 lung specimens were collected in COPD patients and control subjects. S100A4 and S1P were detected in two groups. The markers of fibrosis and epithelial-mesenchymal transition (EMT) were measured in the lungs of COPD patients and control subjects. Results. The protein expression of S100A4 was higher in the lungs and serum of COPD patients than control cases. Additionally, serum S100A4 was inversely associated with pulmonary function among COPD patients. Meanwhile, collagen deposition and EMT nuclear transcription factors were elevated in the lungs of COPD patients. Moreover, the protein expression of S1P was increased in the serum of COPD patients. Serum S1P was gradually increased along with pulmonary function decline in COPD patients. Further correlation analysis revealed that serum S1P was negatively associated with pulmonary function in COPD patients. Furthermore, there was a positive correlation between S1P and S100A4 in COPD patients. Conclusions. These results provide evidence that the elevation of S100A4 and S1P may be involved in the onset and progression of COPD.

Apocynin attenuates patulin-induced cytotoxicity through reduction of oxidation stress and apoptosis in HEK293cells

Patulin (PAT) is a natural mycotoxin that commonly contaminates fruits and their derivative products and has been proven to induce cytotoxicity and oxidative damage in renal cells. In the present study, we aimed to evaluate the effect of apocynin, a potent phenolic antioxidant isolated from plants, on PAT-induced cell injury in human embryonic kidney (HEK293) cells. Compared with 7.5 μM PAT treatment alone, 10 μM apocynin co-treatment elevated cell viability, alleviated lactate dehydrogenase release and reduced caspase activities. Furthermore, apocynin inhibited reactive oxygen species overproduction, re-established mitochondria membrane potential and elevated intracellular ATP content. In addition, the results showed that apocynin aggrandized reduced glutathione (GSH) content, reduced oxidized glutathione (GSSG) content, raised the GSH/GSSG ratio and elevated superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase activities. Collectively, results of the study clearly show that apocynin supplement may serve as an alternative intervention to protect HEK293 cells against cytotoxicity induced by PAT through reduction of oxidation stress and apoptosis.

NADPH Oxidase Inhibition in Fibrotic Pathologies

Significance: Fibrosis is a stereotypic, multicellular tissue response to diverse types of injuries that fundamentally result from a failure of cell/tissue regeneration. This complex tissue remodeling response disrupts cellular/matrix composition and homeostatic cell-cell interactions, leading to loss of normal tissue architecture and progressive loss of organ structure/function. Fibrosis is a common feature of chronic diseases that may affect the lung, kidney, liver, and heart. Recent Advances: There is emerging evidence to support a combination of genetic, environmental, and age-related risk factors contributing to susceptibility and/or progression of fibrosis in different organ systems. A core pathway in fibrogenesis involving these organs is the induction and activation of nicotinamide adenine dinucleotide phosphate oxidase (NOX) family enzymes. Critical Issues: We explore current pharmaceutical approaches to targeting NOX enzymes, including repurposing of currently U.S. Food and Drug Administration (FDA)-approved drugs. Specific inhibitors of various NOX homologs will aid establishing roles of NOXs in the various organ fibroses and potential efficacy to impede/halt disease progression. Future Directions: The discovery of novel and highly specific NOX inhibitors will provide opportunities to develop NOX inhibitors for treatment of fibrotic pathologies.

Lipoic acid alleviates schistosomiasis-induced liver fibrosis by upregulating Drp1 phosphorylation

Lipoic acid (LA) has been shown to possess protective effects against liver fibrosis mainly by induction of apoptosis of activated hepatic stellate cells, but the mechanism of LA activity in liver fibrosis has yet to be completely explained. LA occurs naturally in mitochondria as a coenzyme. In this study, we used mice with schistosomiasis-induced liver fibrosis and mouse hepatocarcinoma cell line 1C1C7 as models to investigate the mitochondrial mechanism of LA treatment for liver fibrosis. Western blot, real-time PCR and oxygen consumption rate (OCR) test were used. In the livers of mice with liver fibrosis, the mRNA levels of LA synthetic pathway enzymes, including MCAT, OXSM, MECR, and LIAS, were significantly reduced. Livers of mice with liver fibrosis showed degenerative signs, such as mitochondrial edema, a reduced mitochondrial crest and matrix density, or vacuolation; the activities of mitochondrial complexes I, II, IV, and V were also decreased in these livers. The expression of phosphorylation Drp1 (p-Drp1) was decreased in the livers of mice with liver fibrosis, indicating increased mitochondrial fission activity, whereas OPA1 and MFN1 expression was reduced, denoting decreased activity of mitochondrial fusion. To understand the mitochondrial mechanism of LA treatment for liver fibrosis, p-Drp1, OPA1, and MFN1 expression were detected at the protein level in mouse hepatocarcinoma cell line 1C1C7 stimulated by LA. OPA1 and MFN1 were not significantly altered, but p-Drp1 was significantly increased. The results suggest that LA may alleviate liver fibrosis through upregulating p-Drp1. This study provides a new insight into the mechanism of the protective effect of LA against schistosomiasis-induced liver fibrosis, which demonstrates that LA is required for the maintenance of mitochondrial function by upregulating p-Drp1 expression to inhibit mitochondrial fission.

Ellagic acid attenuates liver toxicity induced by valproic acid in rats

Valproic acid is a commonly used drug for many psychiatric disorders, particularly for epilepsy. However, it has been reported that its use is associated with possible side effects including hepatotoxicity. The present study investigated the hepatoprotective effect of ellagic acid against valproic acid-induced hepatotoxicity in rats. Ellagic acid (60 mg/kg/day; p.o) was treated for one week, followed by concomitant injection of valproic acid (250 mg/kg/day; i.p.) for another 14 consecutive days to induce hepatocellular damage in adult Sprague-Dawley rats. Valproic acid showed a marked increase in serum enzyme activities, AST, ALT, ALP and GGT. In addition, it significantly increased MDA and NO along with a marked decline in reduced GSH content. At the same time, valproic acid administration resulted in marked elevation in hydroxyproline, TNF-α production and NF-kB expression. These results were confirmed by histopathological examination. Treatment with ellagic acid markedly attenuated valproic acid-induced hepatic injury in rats.

Iron chelation by deferasirox confers protection against concanavalin A-induced liver fibrosis: A mechanistic approach

Hepatic iron overload is one of the causative factors for chronic liver injury and fibrosis. The present study aimed to investigate the potential antifibrotic effect of the iron chelator; deferasirox (DFX) in experimentally-induced liver fibrosis in rats. Male Sprague-Dawley rats were administered concanavalin A (Con A) and/or DFX for 6 consecutive weeks. Con A injection induced significant hepatotoxicity as was evident by the elevated transaminases activity, and decreased albumin level. Also, it disturbed the iron homeostasis through increasing C/EBP homologous protein (CHOP), decreasing phosphorylated cAMP responsive element binding protein(P-CREB) and hepcidin levels leading to significant serum and hepatic iron overload. In addition, it induced an imbalance in the oxidative status of the liver via upregulating NADPH oxidase 4 (NOX4), together with a marked decrease in anti-oxidant enzymes' activities. As a consequence, upregulation of nuclear factor-kappa b (NF-κB) and the downstream inflammatory mediators was observed. Those events all together precipitated in initiation of liver fibrosis as confirmed by the elevation of alpha-smooth muscle actin (α-SMA) and liver collagen content. Co-treatment with DFX protected against experimentally-induced liver fibrosis in rats via its iron chelating, anti-oxidant, and anti-inflammatory properties. These findings imply that DFX can attenuate the progression of liver fibrosis.