Naringin protects against HIV-1 protease inhibitors-induced pancreatic β-cell dysfunction and apoptosis

Effects of individual drug and combination antiretroviral therapy on trophoblast proliferation

BACKGROUND

Combination antiretroviral therapy (cART) has been reported to reduce perinatal transmission of human immunodeficiency virus (HIV) and improve maternal survival outcomes. Recent studies have associated in-utero exposure to cART drugs with adverse outcomes such as pre-eclampsia, preterm delivery, low birth weight and small-for-gestational-age births. However, the exact molecular mechanisms underlying cART-induced adverse pregnancy outcomes remain poorly defined.

OBJECTIVES

To investigate the effects of cART drugs on trophoblast proliferation in the HTR-8/SVneo cell line.

STUDY DESIGN

HTR-8/SVneo cells were exposed to tenofovir (0.983-9.83 µM), emtricitabine (0.809-8.09 µM) and efavirenz (0.19-1.09 µM), the individual drugs of the first-line single tablet cART regimen termed 'Atripla', and zidovudine (1.12-1.12 µM), lamivudine (0.65-6.5 µM), lopinavir (0.32-3.2 µM) and ritonavir (0.69-6.9 µM), the individual drugs of the second-line single tablet cART regimen termed 'Aluvia'. The cells were treated for 24, 48, 72 and 96 h, and trophoblast proliferation was assessed using a colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltretrazolium bromide assay.

RESULTS

Two-way analysis of variance showed a significant dose-dependent decrease (p < 0.05) in trophoblast proliferation in response to individual and combined drug components of first- and second-line antiretroviral therapy.

CONCLUSIONS

First- and second-line cART drugs inhibit trophoblast proliferation, and may contribute to placenta-mediated adverse pregnancy outcomes in patients with HIV.

Clinical applications and mechanism insights of natural flavonoids against type 2 diabetes mellitus

Diabetes is a complex disease that affects a large percentage of the world's population, and it is associated with several risk factors. Self-management poses a significant challenge, but natural sources have shown great potential in providing effective glucose reducing solutions. Flavonoids, a class of bioactive substances found in different natural sources including medicinal plants, have emerged as promising candidates in this regard. Indeed, several flavonoids, including apigenin, arbutin, catechins, and cyanidin, have demonstrated remarkable anti-diabetic properties. The clinical effectiveness of these flavonoids is linked to their potential to decrease blood glucose concentration and increase insulin concentration. Thus, the regulation of certain metabolic pathways such as glycolysis and neoglycogenesis has also been demonstrated. In vitro and in vivo investigations revealed different mechanisms of action related to flavonoid compounds at subcellular, cellular, and molecular levels. The main actions reside in the activation of glycolytic signaling pathways and the inhibition of signaling that promotes glucose synthesis and storage. In this review, we highlight the clinical efficiency of natural flavonoids as well as the molecular mechanisms underlying this effectiveness.

Mesenchymal Stem Cell in Pancreatic Islet Transplantation

Pancreatic islet transplantation is a therapeutic option for achieving physiologic regulation of plasma glucose in Type 1 diabetic patients. At the same time, mesenchymal stem cells (MSCs) have demonstrated their potential in controlling graft rejection, the most fearsome complication in organ/tissue transplantation. MSCs can interact with innate and adaptive immune system cells either through direct cell-cell contact or through their secretome including exosomes. In this review, we discuss current findings regarding the graft microenvironment of pancreatic islet recipient patients and the crucial role of MSCs operation as cell managers able to control the immune system to prevent rejection and promote endogenous repair. We also discuss how challenging stressors, such as oxidative stress and impaired vasculogenesis, may jeopardize graft outcomes. In order to face these adverse conditions, we consider either hypoxia-exposure preconditioning of MSCs or human stem cells with angiogenic potential in organoids to overcome islets' lack of vasculature. Along with the shepherding of carbon nanotubes-loaded MSCs to the transplantation site by a magnetic field, these studies look forward to exploiting MSCs stemness and their immunomodulatory properties in pancreatic islet transplantation.

Phytoestrogen β-Sitosterol Exhibits Potent In Vitro Antiviral Activity against Influenza A Viruses

Influenza is a contagious infection in humans that is caused frequently by low pathogenic seasonal influenza viruses and occasionally by pathogenic avian influenza viruses (AIV) of H5, H7, and H9 subtypes. Recently, the clinical sector in poultry and humans has been confronted with many challenges, including the limited number of antiviral drugs and the rapid evolution of drug-resistant variants. Herein, the anti-influenza activities of various plant-derived phytochemicals were investigated against highly pathogenic avian influenza A/H5N1 virus (HPAIV H5N1) and seasonal low pathogenic human influenza A/H1N1 virus (LPHIV H1N1). Out of the 22 tested phytochemicals, the steroid compounds β-sitosterol and β-sitosterol-O-glucoside have very potent activity against the predefined influenza A viruses (IAV). Both steroids could induce such activity by affecting multiple stages during IAV replication cycles, including viral adsorption and replication with a major and significant impact on the virus directly in a cell-free status "viricidal effect". On a molecular level, several molecular docking studies suggested that β-sitosterol and β-sitosterol-O-glucoside exhibited viricidal effects through blocking active binding sites of the hemagglutinin surface protein, as well as showing inhibitory effects against replication through the binding with influenza neuraminidase activity and blocking the active sites of the M2 proton channel activity. The phytoestrogen β-sitosterol has structural similarity with the active form of the female sex hormone estradiol, and this similarity is likely one of the molecular determinants that enables the phytoestrogen β-sitosterol and its derivative to control IAV infection in vitro. This promising anti-influenza activity of β-sitosterol and its O-glycoside derivative, according to both in vitro and cheminformatics studies, recommend both phytochemicals for further studies going through preclinical and clinical phases as efficient anti-influenza drug candidates.

Naringin Prevents Bone Damage in the Experimental Metabolic Syndrome Induced by a Fructose Rich Diet

We have analyzed the effect of naringin (NAR), a flavonoid from citric fruits, on bone quality and bone biomechanical properties as well as the redox state of bone marrow in rats fed a fructose rich diet (FRD), an experimental model to mimic human metabolic syndrome. NAR blocked the enhancement in the number of osteoclasts and adipocytes and the decrease in the number of osteocytes and osteocalcin (+) cells caused by FRD. The trabecular number was significantly higher in the FRD+NAR group. FRD induced a decrease in femoral trabecular and cortical bone mineral density, which was blocked by NAR. The fracture and ultimate loads were also decreased by the FRD and FRD+NAR groups. NAR increased the number of nodes to terminal trabecula, the number of nodes to node trabecula, the number of nodes, and the number of nodes with two terminals, and decreased the Dist (mean size of branches) value. Bone marrow catalase activity was decreased by the FRD, an effect prevented by NAR. In conclusion, FRD produces detrimental effects on long bones, which are associated with oxidative stress in bone marrow. Most of these changes are avoided by NAR through its antioxidant properties and promotion of bone formation. Novelty bullets: • Fructose rich diet produces detrimental effects on long bones, which are associated with oxidative stress in bone marrow. • Most of these changes are avoided by Naringin through its antioxidant properties and promotion of bone formation.

Metabolic complications affecting adipose tissue, lipid and glucose metabolism associated with HIV antiretroviral treatment

Introduction: Efficient antiretroviral-treatment (ART) generally allows control of HIV infection. However, persons-living-with-HIV (PLWH), when aging, present a high prevalence of metabolic diseases. Area covered: Altered adiposity, dyslipidemias, insulin resistance, diabetes, and their consequences are prevalent in PLWH and could be partly related to ART. Expert opinion: At first, personal and lifestyle factors are involved in the onset of these complications. The persistence of HIV in tissue reservoirs could synergize with some ART and enhance metabolic disorders. Altered fat repartition, diagnosed as lipodystrophy, has been related to first-generation nucleoside-reverse-transcriptase-inhibitors (NRTIs) (stavudine zidovudine) and some protease inhibitors (PIs). Recently, use of some integrase-inhibitors (INSTI) resulted in weight/fat gain, which represents a worrisome unresolved situation. Lipid parameters were affected by some first-generation NRTIs, non-NRTIs (efavirenz) but also PIs boosted by ritonavir, with increased total and LDL-cholesterol and triglycerides. Insulin resistance is common associated with abdominal obesity. Diabetes incidence, high with first-generation-ART (zidovudine, stavudine, didanosine, indinavir) has declined with contemporary ART close to that of the general population. Metabolic syndrome, a dysmetabolic situation with central obesity and insulin resistance, and liver steatosis are common in PLWH and could indirectly result from ART-associated fat gain and insulin resistance. All these dysmetabolic situations increase the atherogenic cardiovascular risk.

DNA polymerase-γ hypothesis in nucleoside reverse transcriptase-induced mitochondrial toxicity revisited: A potentially protective role for citrus fruit-derived naringenin?

Nucleoside reverse transcriptase inhibitors (NRTIs) form the backbone in combination antiretroviral therapy (cARVs). They halt chain elongation of the viral cDNA by acting as false substrates in counterfeit incorporation mechanism to viral RNA-dependent DNA polymerase. In the process genomic DNA polymerase as well as mitochondrial DNA (mtDNA) polymerase-γ (which has a much higher affinity for these drugs at therapeutic doses) are also impaired. This leads to mitochondrial toxicity that manifests clinically as mitochondrial myopathy, peripheral neuropathy, hyperlactatemia or lactic acidosis and lipoatrophy. This has led to the revision of clinical guidelines by World Health Organization to remove stavudine from first-line listing in the treatment of HIV infections. Recent reports have implicated oxidative stress besides mtDNA polymerase-γ hypothesis in NRTI-induced metabolic complications. Reduced plasma antioxidant concentrations have been reported in HIV positive patients on cARVs but clinical intervention with antioxidant supplements have not been successful either due to low efficacy or poor experimental designs. Citrus fruit-derived naringenin has previously been demonstrated to possess antioxidant and free radical scavenging properties which could prevent mitochondrial toxicity associated with these drugs. This review revisits the controversy surrounding mtDNA polymerase-γ hypothesis and evaluates the potential benefits of naringenin as a potent anti-oxidant and free radical scavenger which as a nutritional supplement or therapeutic adjunct could mitigate the development of mitochondrial toxicity associated with these drugs.

Naringin Protects Pancreatic β-Cells Against Oxidative Stress-Induced Apoptosis by Inhibiting Both Intrinsic and Extrinsic Pathways in Insulin-Deficient Diabetic Mice

SCOPE

Oxidative stress has been suggested to play a central role in the pathogenesis of diabetes, as well as other metabolic disorders. Naringin, a major flavanone glycoside in citrus species, has been shown to display strong antioxidant potential in in vitro and in vivo models of oxidative stress; however, the underlying protective mechanisms in diabetes are unclear.

METHODS AND RESULTS

To study the protective effects and molecular mechanisms of naringin in preventing islet dysfunction and diabetes, we examined glucose homeostasis, β-cell apoptosis, and inflammatory response in insulin-deficient diabetic mice exposed to acute oxidative stress with streptozotocin (STZ). Naringin dose-dependently ameliorated hyperglycemia and islet dysfunction in insulin-deficient diabetic mice. Naringin counteracted STZ-induced β-cell apoptosis by inhibiting both the intrinsic (mitochondria-mediated) and extrinsic (death receptor-mediated) pathways. Furthermore, these protective effects were associated with suppression of DNA damage response and nuclear factor-kappa B- and mitogen-activated protein kinase-mediated signaling pathways, as well as reduction of reactive oxygen species accumulation and pro-inflammatory cytokine production in the pancreas.

CONCLUSION

Taken together, our study provides insights into the underlying mechanisms through which naringin protects the pancreatic β-cells against oxidative stress-induced apoptosis.

Naringin (4',5,7-Trihydroxyflavanone 7-Rhamnoglucoside) Attenuates β-Cell Dysfunction in Diabetic Rats through Upregulation of PDX-1

BACKGROUND

Pancreatic duodenal homeobox-1 (PDX-1) is a key transcription factor which regulates Insulin gene expression and insulin secretion in adult β-cells and helps to maintain β-cells mass. Naringin, a flavanone, owing to its anti-oxidant property, is reported to have antidiabetic effects.

OBJECTIVES

The present study tries to evaluate the role of naringin on the β-cell-specific transcription factor PDX-1 in diabetic rats.

METHODS

Diabetes was induced in male rats using streptozotocin and treated with naringin (100 mg/kg) orally for 4 and 8 weeks. Serum insulin level, Pdx-1 and Insulin gene expression, and PDX-1 protein expression were assessed in the rat pancreas. Histopathological and ultrastructural changes in the islet and β-cells were observed.

RESULTS

Naringin prevented leukocytic infiltration in the pancreas of diabetic rats and recouped the β-cells with adequate secretory granules. Naringin-treated diabetic rats showed significantly increased mRNA expression of Pdx-1 and Insulin genes, increased expression of transcription factor PDX-1, and higher serum insulin levels than the diabetic control animals. These changes were more pronounced in the 8-week naringin-treated diabetic animals.

CONCLUSIONS

Naringin was found to be an effective antidiabetic agent which increased Insulin gene expression and insulin secretion by upregulating the PDX-1 gene and protein expression.

Naringin Ameliorates Streptozotocin-Induced Diabetes through Forkhead Box M1-Mediated Beta Cell Proliferation

BACKGROUND

Adult pancreatic beta cells, though quiescent, can proliferate in response to physiological need. This inherent character is used in exploring the possibilities of expanding the beta cell mass in the treatment of diabetes. Forkhead box M1 (FoxM1) transcription factor is an important regulator in the proliferation and survival of adult beta cell mass. Naringin, a flavanone glycoside, is reported to have antidiabetic activity and exhibited an increase in insulin levels in diabetic animals.

OBJECTIVES

The present study tried to evaluate the role of naringin in the regulation of FoxM1 in the pancreas of diabetic rats and to reascertain its antilipidemic and antioxidant properties.

METHODS

Diabetes was induced in male rats using streptozotocin and treated with naringin (100 mg/kg) orally for 4 and 8 weeks. Serum biochemical parameters, insulin, gene and protein expression of FoxM1, and antioxidant markers in rat pancreas were analyzed.

RESULTS

Naringin administration reduced the blood sugar, urea, creatinine, and cholesterol values and improved the pancreatic antioxidant status in diabetic rats. Naringin-treated diabetic rats showed a significant increase in mRNA and protein expression of FoxM1 compared to the diabetic control rats, indicating regeneration of cells. It also increased the insulin immunopositive cells, indicating functional beta cells.

CONCLUSION

Naringin was found to upregulate the FoxM1 transcription factor in diabetic animals, which influenced the proliferation and functional status of beta cells.

Naringin prevents HIV-1 protease inhibitors-induced metabolic complications in vivo

Background

Insulin resistance, glucose intolerance and overt diabetes are known metabolic complications associated with chronic use of HIV-Protease Inhibitors. Naringin is a grapefruit-derived flavonoid with anti-diabetic, anti-dyslipidemia, anti-inflammatory and anti-oxidant activities.

Objectives

The study investigated the protective effects of naringin on glucose intolerance and impaired insulin secretion and signaling in vivo.

Methods

Male Wistar rats were divided into six groups (n = 6) and were daily orally treated with distilled water {3.0 ml/kg body weight (BW)}, atazanavir (133 mg/kg BW), saquinavir (333 mg/kg BW) with or without naringin (50 mg/kg BW), respectively for 56 days. Body weights and water consumption were recorded daily. Glucose tolerance tests were carried out on day 55 of the treatment and thereafter, the rats were sacrificed by halothane overdose.

Results

Atazanavir (ATV)- or saquinavir (SQV)-treated rats exhibited significant weight loss, polydipsia, elevated Fasting blood glucose (FBG), reduced Fasting Plasma Insulin (FPI) and expression of phosphorylated, Insulin Receptor Substrate-1 (IRS-1) and Akt proteins, hepatic and pancreatic glucokinase levels, and also increasing pancreatic caspase-3 and -9 as well as UCP2 protein expressions compared to controls, respectively. These effects were completely reversed by naringin treatment.

Conclusion

Naringin prevents PI-induced glucose intolerance and impairment of insulin signaling and as nutritional supplement it could therefore alleviate metabolic complications associated with antiretroviral therapy.

Naringin prevents the inhibition of intestinal Ca2+ absorption induced by a fructose rich diet

This study tries to elucidate the mechanisms by which fructose rich diets (FRD) inhibit the rat intestinal Ca²⁺ absorption, and determine if any or all underlying alterations are prevented by naringin (NAR). Male rats were divided into: 1) controls, 2) treated with FRD, 3) treated with FRD and NAR. The intestinal Ca²⁺ absorption and proteins of the transcellular and paracellular Ca²⁺ pathways were measured. Oxidative/nitrosative stress and inflammation parameters were evaluated. FRD rats showed inhibition of the intestinal Ca²⁺ absorption and decrease in the protein expression of molecules of both Ca²⁺ pathways, which were blocked by NAR. FRD rats showed an increase in the superoxide anion, a decrease in the glutathione and in the enzymatic activities of the antioxidant system, as well as an increase in the NO content and in the nitrotyrosine content of proteins. They also exhibited an increase in both IL-6 and nuclear NF-κB. All these changes were prevented by NAR. In conclusion, FRD inhibit both pathways of the intestinal Ca²⁺ absorption due to the oxidative/nitrosative stress and inflammation. Since NAR prevents the oxidative/nitrosative stress and inflammation, it might be a drug to avoid alteration in the intestinal Ca²⁺ absorption caused by FRD.

Metformin-like antidiabetic, cardio-protective and non-glycemic effects of naringenin: Molecular and pharmacological insights

Metformin is a widely used drug for the treatment of type 2 diabetes (T2D). Its blood glucose-lowering effects are initially due to inhibition of hepatic glucose production and increased peripheral glucose utilization. Metformin has also been shown to have several beneficial effects on cardiovascular risk factors and it is the only oral antihyperglycaemic agent thus far associated with decreased macrovascular complications in patients with diabetes. Adenosine Monophosphate Activated-Protein Kinase (AMPK) is a major cellular regulator of lipid and glucose metabolism. Recent evidence shows that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profiles, blood pressure and insulin-resistance making it a novel therapeutic target in the treatment of T2D. Naringenin a flavonoid found in high concentrations as its glycone naringin in citrus fruits, has been reported to have antioxidant, antiatherogenic, anti- dyslipidemic and anti-diabetic effects. It has been shown that naringenin exerts its anti-diabetic effects by inhibition of gluconeogenesis through upregulations of AMPK hence metformin-like effects. Naringin has further been shown to have non-glycemic affects like metformin that mitigate inflammation and cell proliferation. This review evaluates the potential of naringenin as anti-diabetic, anti-dyslipidemic anti-inflammatory and antineoplastic agent similar to metformin and proposes its further development for therapeutic use in clinical practice.