Modulatory mechanisms of copperII-albumin complex toward N-nitrosodiethylamine-induced neurotoxicity in mice via regulating oxidative damage, inflammatory, and apoptotic signaling pathways

N-nitrosodiethylamine (ND) is an extremely toxic unavoidable environmental contaminant. CopperII-albumin (CuAB) complex, a newly developed Cu complex, showed antioxidant and anti-inflammatory potential. Hereby, we explored the plausible neuroprotective role of CuAB complex toward ND-evoked neurotoxicity in mice. Twenty-four male mice were sorted into 4 groups (6 mice each). Control group, mice were administered oral distilled water; and CuAB group, mice received CuAB complex at a dose of 817 µg/kg orally, three times weekly. In ND group, ND was given intraperitoneally (50 mg/kg body weight, once weekly for 6 w). CuAB+ND group, mice were administered a combination of CuAB and ND. The brain was quickly extracted upon completion of the experimental protocol for the evaluation of the oxidative/antioxidative markers, inflammatory cytokines, and histopathological examination. Oxidative stress was induced after ND exposure indicated by a reduction in GSH and SOD1 level, with increased MDA level. In addition, decreased expression of SOD1 proteins, Nrf2, and 5-HT mRNA expression levels were noticed. An apoptotic cascade has also been elicited, evidenced by overexpression of Cyt c, Cl. Casp 3. In addition, increased regulation of proinflammatory genes (TNF-α, IL-6, iNOS, Casp1, and NF-κB (p65/p50); besides, increment of protein expression of P-IKBα and reduced expression of IKBα. Pretreatment with CuAB complex significantly ameliorated ND neuronal damage. Our results recommend CuAB complex supplementation because it exerts neuroprotective effects against ND-induced toxicity.

Type 1 Diabetes Impairs Endothelium-Dependent Relaxation Via Increasing Endothelial Cell Glycolysis Through Advanced Glycation End Products, PFKFB3, and Nox1-Mediated Mechanisms

BACKGROUND

Type 1 diabetes (T1D) is a major cause of endothelial dysfunction. Although cellular bioenergetics has been identified as a new regulator of vascular function, whether glycolysis, the primary bioenergetic pathway in endothelial cells (EC), regulates vascular tone and contributes to impaired endothelium-dependent relaxation (EDR) in T1D remains unknown.

METHODS

Experiments were conducted in Akita mice with intact or selective deficiency in EC PFKFB3 (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3), the main regulator of glycolysis. Seahorse analyzer and myography were employed to measure glycolysis and mitochondrial respiration, and EDR, respectively, in aortic explants. EC PFKFB3 (Ad-PFKFB3) and glycolysis (Ad-GlycoHi) were increased in situ via adenoviral transduction.

RESULTS

T1D increased EC glycolysis and elevated EC expression of PFKFB3 and NADPH oxidase Nox1 (NADPH oxidase homolog 1). Functionally, pharmacological and genetic inhibition of PFKFB3 restored EDR in T1D, while in situ aorta EC transduction with Ad-PFKFB3 or Ad-GlycoHi reproduced the impaired EDR associated with T1D. Nox1 inhibition restored EDR in aortic rings from Akita mice, as well as in Ad-PFKFB3-transduced aorta EC and lactate-treated wild-type aortas. T1D increased the expression of the advanced glycation end product precursor methylglyoxal in the aortas. Exposure of the aortas to methylglyoxal impaired EDR, which was prevented by PFKFB3 inhibition. T1D and exposure to methylglyoxal increased EC expression of HIF1α (hypoxia-inducible factor 1α), whose inhibition blunted methylglyoxal-mediated EC PFKFB3 upregulation.

CONCLUSIONS

EC bioenergetics, namely glycolysis, is a new regulator of vasomotion and excess glycolysis, a novel mechanism of endothelial dysfunction in T1D. We introduce excess methylglyoxal, HIF1α, and PFKFB3 as major effectors in T1D-mediated increased EC glycolysis.

Nootkatone Mitigated Melamine-Evoked Hepatotoxicity by Featuring Oxidative Stress and Inflammation Interconnected Mechanisms: In Vivo and In Silico Approaches

Melamine (ML) is a common environmental contaminant, commonly used in food fraud, representing a serious health hazard and jeopardizing human and animal health. Recently, nootkatone (NK), a naturally occurring sesquiterpenoid, has garnered considerable attention due to its potential therapeutic advantages. We investigated the potential mechanisms underlying the protective effects of NK against ML-induced liver injury in rats. Five groups were utilized: control, ML, NK10, ML-NK5, and ML-NK10. ML induced substantial hepatotoxicity, including considerable alterations in biochemical parameters and histology. The oxidative distress triggered by ML increased the generation of malondialdehyde (MDA) and nitric oxide (NO) and decreased levels of reduced glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) activities. In addition, decreased expression of nuclear factor-erythroid 2-related factor 2 (Nrf2) and increased nuclear factor kappa beta (NF-κB) expression levels were observed in hepatocytes, which indicated the occurrence of inflammatory changes following ML exposure. These alterations were alleviated by NK supplementation in a dose-dependent manner. The data revealed that the favorable effects of NK were attributed, at least in part, to its antioxidant and anti-inflammatory properties. Moreover, our results were supported by molecular docking studies that revealed a good fit and interactions between NK and antioxidant enzymes. Thus, the current study demonstrated that NK is a potential new food additive for the prevention or treatment of ML-induced toxicity.

Radioprotective Effects of Carvacrol and/or Thymol against Gamma Irradiation-Induced Acute Nephropathy: In Silico and In Vivo Evidence of the Involvement of Insulin-like Growth Factor-1 (IGF-1) and Calcitonin Gene-Related Peptide

Radiotherapy (RT) is an effective curative cancer treatment. However, RT can seriously damage kidney tissues resulting in radiotherapy nephropathy (RN) where oxidative stress, inflammation, and apoptosis are among the common pathomechanisms. Carvacrol and thymol are known for their antioxidative, anti-inflammatory, and radioprotective activities. Therefore, this study investigated the nephroprotective potentials of carvacrol and/or thymol against gamma (γ) irradiation-induced nephrotoxicity in rats along with the nephroprotection mechanisms, particularly the involvement of insulin-like growth factor-1 (IGF-1) and calcitonin gene-related peptide (CGRP). Methods: Male rats were injected with carvacrol and/or thymol (80 and 50 mg/kg BW in the vehicle, respectively) for five days and exposed to a single dose of irradiation (6 Gy). Then, nephrotoxicity indices, oxidative stress, inflammatory, apoptotic biomarkers, and the histopathological examination were assessed. Also, IGF-1 and CGRP renal expressions were measured. Results: Carvacrol and/or thymol protected kidneys against γ-irradiation-induced acute RN which might be attributed to their antioxidative, anti-inflammatory, and antiapoptotic activities. Moreover, both reserved the γ -irradiation-induced downregulation of CGRP- TNF-α loop in acute RN that might be involved in the pathomechanisms of acute RN. Additionally, in Silico molecular docking simulation of carvacrol and thymol demonstrated promising fitting and binding with CGRP, IGF-1, TNF-α and NF-κB through the formation of hydrogen, hydrophobic and alkyl bonds with binding sites of target proteins which supports the reno-protective properties of carvacrol and thymol. Collectively, our findings open a new avenue for using carvacrol and/or thymol to improve the therapeutic index of γ-irradiation.

In vivo and In silico evidence of the protective properties of carvacrol against experimentally-induced gastric ulcer: Implication of antioxidant, anti-inflammatory, and antiapoptotic mechanisms

Gastric ulcer is a serious disease that affects millions of individuals worldwide. Alcohol consumption is a major contributor to the disease pathogenesis and ethanol-induced ulcer in rats closely recapitulates the clinical pathology of ulcer. In this study, rats were pretreated with carvacrol (CAR,50 and 100 mg/kg, orally) 1 h before absolute ethanol administration to induce gastric ulcer. CAR prevented ethanol-induced increases in gastric volume and acidity while restored mucin content. The gastro-protective activity of CAR, particularly the higher dose (100 mg/kg), was further supported by histopathological examination, as manifested by reduced gastric lesions. Interestingly, oxidative stress is linked to early stages of ulcer development and progression. In this study, ethanol administration upregulated the levels of ROS-producing enzymes, NADPH oxidase homologs 1 and 4 (Nox1 and Nox4) and lipid peroxides while depleting the antioxidant defense mechanisms, including GSH, Glutathione Peroxidase (GPX) and catalase. Interestingly, these alterations were significantly ameliorated by CAR pretreatment. Additionally, CAR possesses anti-inflammatory and anti-apoptotic activities. Pretreatment with CAR blunted ethanol-induced increases in inflammatory cytokines (NF-κB and TNF-α) and rectified the apoptosis regulator (Bax/Bcl2 ratio) in gastric tissue. Moreover, the docking simulation of CAR illustrated good fitting and interactions with GPX, Nox1 and TNF-α through the formation of hydrogen and hydrophobic (pi-H) bonds with conservative amino acids, thus, further supporting the anti-inflammatory and antioxidant effects underlying the gastroprotective effects of CAR. In conclusion, this study elucidates, using in silico and in vivo models, that the gastroprotective activity of CAR is attributed, at least in part, to its mucin-secretagogue, antioxidative, anti-inflammatory, and anti-apoptotic mechanisms.

The Long Non-coding RNA Carmn is a Critical Regulator of Gastrointestinal Smooth Muscle Contractile Function and Motility

BACKGROUND & AIMS

Visceral smooth muscle cells (SMCs) are an integral component of the gastrointestinal (GI) tract that regulate GI motility. SMC contraction is regulated by post-translational signaling and the state of differentiation. Impaired SMC contraction is associated with significant morbidity and mortality, but the mechanisms regulating SMC-specific contractile gene expression, including the role of long non-coding RNAs (lncRNAs), remain largely unexplored. Herein, we reveal a critical role of Carmn (Cardiac mesoderm enhancer-associated noncoding RNA), a SMC-specific lncRNA, in regulating visceral SMC phenotype and contractility of the GI tract.

METHODS

GTEx and publicly available single-cell RNA sequencing (scRNA-seq) datasets from embryonic, adult human and mouse GI tissues were interrogated to identify SMC-specific lncRNAs. The functional role of Carmn was investigated using novel GFP knock-in (KI) reporter/knockout (KO) mice. Bulk RNA sequencing (RNA-seq) and single nucleus RNA sequencing (snRNA-seq) of colonic muscularis were used to investigate underlying mechanisms.

RESULTS

Unbiased in silico analyses and GFP expression patterns in Carmn GFP KI mice revealed that Carmn is highly expressed in GI SMCs in human and mouse. Premature lethality was observed in global Carmn KO (gKO) and inducible SMC-specific KO (iKO) mice due to GI pseudo-obstruction, severe distension of the GI tract with dysmotility in cecum and colon segments. Histology, GI transit and muscle myography analysis revealed severe dilation, significantly delayed GI transit and impaired GI contractility in Carmn KO versus control mice. Bulk RNA-seq of GI muscularis revealed that loss of Carmn promotes SMC phenotypic switching as evidenced by up-regulation of extracellular matrix genes and down-regulation of SMC contractile genes, including Mylk, a key regulator of SMC contraction. snRNA-seq further revealed SMC Carmn KO not only compromised myogenic motility by reducing contractile gene expression but also impaired neurogenic motility by disrupting cell-cell connectivity in the colonic muscularis. These findings may have translational significance as silencing CARMN in human colonic SMCs significantly attenuated contractile gene expression, including MYLK, and decreased SMC contractility. Luciferase reporter assays showed that CARMN enhances the transactivation activity of the master regulator of SMC contractile phenotype, myocardin, thereby maintaining the GI SMC myogenic program.

CONCLUSIONS

Our data suggest that Carmn is indispensable for maintaining GI SMC contractile function in mice, and that loss of function of CARMN may contribute to human visceral myopathy. To our knowledge this is the first study showing an essential role of lncRNA in the regulation of visceral SMC phenotype.

Endothelial leptin receptor is dispensable for leptin-induced sympatho-activation and hypertension in male mice

Leptin plays a crucial role in blood pressure (BP) regulation, notably in the context of obesity through central sympatho-mediated pressor effects. Leptin also relaxes arteries via endothelial (EC) leptin receptor (LepREC)-mediated increases in nitric oxide (NO) bioavailability. Herein, we investigated whether leptin-mediated increases in NO bioavailability represent a buffering mechanism against leptin-induced sympatho-activation. We tested the direct contribution of LepREC to BP regulation in physiological conditions and in response to chronic leptin infusion using mice deficient in LepREC. LepREC deficiency did not alter baseline metabolic profile nor leptin-induced reduction in adiposity and increases in energy expenditure. LepREC-/- mice demonstrated no increase in baseline BP and heart rate (HR) (MAP: LepREC+/+:94.7 ± 1.6, LepREC-/-:95.1 ± 1.8 mmHg; HR:LepREC+/+:492.4 ± 11.7, LepREC-/-:509.5 ± 13.4 bpm) nor in response to leptin (MAP, LepREC+/+:101.1 ± 1.7, LepREC-/-:101.7 ± 1.8 mmHg; HR, LepREC+/+:535.6 ± 11.1, LepREC-/-:539.3 ± 14.2 bpm). Moreover, baseline neurogenic control of BP and HR was preserved in LepREC-/- mice as well as leptin-mediated increases in sympathetic control of BP and HR and decreases in vagal tone. Remarkably, LepREC deficiency did not alter endothelium-dependent relaxation in resistance vessels, nor NO contribution to vasodilatation. Lastly, leptin induced similar increases in adrenergic contractility in mesenteric arteries from both LepREC+/+ and LepREC-/- mice. Collectively, these results demonstrate that the NO buffering effects of leptin are absent in resistance arteries and do not contribute to BP regulation. We provide further evidence that leptin-mediated hypertension involves increased vascular sympatho-activation and extend these findings by demonstrating for the first time that increased cardiac sympatho-activation and reduced vagal tone also contribute to leptin-mediated hypertension.

Abstract P275: Deletion Of Endothelial Leptin Receptor Elevates Blood Pressure And Impairs Endothelial-dependent Relaxation Via Upregulation Of Endothelial Glycolytic Enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3)

The adipokine leptin plays a crucial role in blood pressure (BP) regulation notably by exerting pressor effects centrally via sympatho-activation and depressor effects via direct activation of its receptor (LepR) peripherally resulting in nitric oxide (NO)-mediated vasodilation. However, the predominant effects and cell type responsible for leptin-mediated NO production is not clearly understood. Herein, we examined the effect of selective deletion of LepR in endothelial cells (LepR EC-/- , KO) on BP and vascular function. BP recording via radiotelemetry in male KO and WT (LepR EC+/+ ) mice revealed significant increases in diastolic and mean arterial pressure in KO mice (DBP, WT: 90.2±2.1 vs. KO: 100.1±3.6; MAP, WT: 105.7±2.1 vs. KO: 113.7±2.6 mmHg, n=5, p<0.05). There was no difference in Systolic blood pressure or heart rate between KO and WT. Leptin infusion (0.9mg/kg/day,7 days) elicits a significant increase in BP of WT but not KO mice (DBP, WT: 89.2± 2.6 vs WT+Leptin 95.7±3.3; MAP, WT: 104 ±2.8 vs WT+Leptin: 110 ±2.7, n=5, p<0.05). We quantified sympathetic contribution to BP elevation by measuring BP response to glanglionic blockade (Hexamethonium). At baseline, KO mice exhibited a lower BP response than WT supporting a reduced neurogenic control of BP regulation in KO mice. Vascular contribution to high BP was investigated using wire myography in thoracic aorta. LepR deficiency impaired endothelial-dependent relaxation (EDR) to acetylcholine (n=7, p<0.05). L-NAME completely abolished EDR in KO and WT indicating that EC LepR deficiency reduced NO bioavailability. Recent evidence presents PFKFB3-mediated EC glycolysis as a new regulator of endothelial homeostasis. We found that aortic EC from KO exhibited increased PFKFB3 mRNA expression (p=0.065) and PFKFB3 inhibition restored EDR in KO. Remarkably, overexpression of PFKFB3 increased EC glycolysis in vitro and impaired EDR in WT aortic rings ex vivo . Collectively, our data suggest that impaired endothelial leptin receptor signaling induces a PFKFB3-dependent hyper-glycolytic phenotype resulting in NO deficiency and endothelial dysfunction that predisposes to higher BP regardless the reduced sympatho-activation which might prevent the increase in BP induced by exogenous leptin.

Abstract P242: Perivascular Adipose Tissue Regulates Endothelial Function And Glucose Disposal Via Leptin Control Of The 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 / NADPH Oxidase 1 Pathways

Our group has previously reported that lack of adipose tissue (lipodystrophy) leads to glucose intolerance and impaired endothelial-dependent vasorelaxation (EDR) via reduced signaling of the adipokine, leptin in the endothelium. However, the identity of the adipose depot responsible for endothelial leptin signaling activation and the underlying mechanism remains ill-defined. Our new data indicate that the perivascular adipose tissue (PVAT) is an important source of leptin. Thus, we hypothesized that leptin specifically derived from PVAT restores EDR and glucose tolerance in a mouse model with global deficiency in adipose tissue (lipodystrophic, BSCL2 -/- ). Restoration of PVAT in BSCL2 -/- mice corrected systemic glycemic status (GTT AUC, BSCL2 -/- + PVAT 635.3 ± 31.28 vs sham 741.6 ± 45.87, p<0.05). Moreover, PVAT transplantation restored EDR locally (abdominal aorta EDR AUC, BSCL2 -/- + PVAT 224.9 ± 23.97 vs 109 ± 19, P<0.05) but not systemically (thoracic aorta EDR AUC, BSCL2 -/- + PVAT 143.8 ± 22.29 vs sham 131.3 ± 11.54, P<0.05), indicating a distinctive paracrine role for PVAT-derived leptin in the vasculature. Concomitantly, we reported that inhibition of endothelial glycolysis, the main bioenergetic pathway of endothelial cells, via inhibition of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a major regulator of the glycolytic pathway, significantly improved endothelial function in both lipodystrophic mice and endothelial leptin receptor (LepR) deficient mice, as leptin does. Also, endothelial cells extracted from aortas of BSCL2 -/- mice showed a trend towards an increase in PFKFB3 mRNA expression compared to WT mice. Moreover, we found that overexpression of PFKFB3 in aortic rings and endothelial cells impaired EDR and increased the ROS generating enzyme, Nox1 expression, respectively. Collectively, our results showed the critical role of PVAT-driven leptin and endothelial leptin receptor signaling in regulating systemic glucose disposal as well as endothelial function via a mechanism that potentially regulates endothelial glycolysis and oxidative stress-mediated via PFKFB3/NOX1.

Mechanisms of obesity-induced metabolic and vascular dysfunctions

Obesity has reached epidemic proportions and its prevalence is climbing. Obesity is characterized by hypertrophied adipocytes with a dysregulated adipokine secretion profile, increased recruitment of inflammatory cells, and impaired metabolic homeostasis that eventually results in the development of systemic insulin resistance, a phenotype of type 2 diabetes. Nitric oxide synthase (NOS) is an enzyme that converts L-arginine to nitric oxide (NO), which functions to maintain vascular and adipocyte homeostasis. Arginase is a ureohydrolase enzyme that competes with NOS for L-arginine. Arginase activity/expression is upregulated in obesity, which results in diminished bioavailability of NO, impairing both adipocyte and vascular endothelial cell function. Given the emerging role of NO in the regulation of adipocyte physiology and metabolic capacity, this review explores the interplay between arginase and NO, and their effect on the development of metabolic disorders, cardiovascular diseases, and mitochondrial dysfunction in obesity. A comprehensive understanding of the mechanisms involved in the development of obesity-induced metabolic and vascular dysfunction is necessary for the identification of more effective and tailored therapeutic avenues for their prevention and treatment.

Obesity-induced vascular dysfunction and arterial stiffening requires endothelial cell arginase 1

AIMS

Elevation of arginase activity has been linked to vascular dysfunction in diabetes and hypertension by a mechanism involving decreased nitric oxide (NO) bioavailability due to L-arginine depletion. Excessive arginase activity also can drive L-arginine metabolism towards the production of ornithine, polyamines, and proline, promoting proliferation of vascular smooth muscle cells and collagen formation, leading to perivascular fibrosis. We hypothesized that there is a specific involvement of arginase 1 expression within the vascular endothelial cells in this pathology.

METHODS AND RESULTS

To test this proposition, we used models of type 2 diabetes and metabolic syndrome. Studies were performed using wild type (WT), endothelial-specific arginase 1 knockout (EC-A1-/-) and littermate controls(A1con) mice fed high fat-high sucrose (HFHS) or normal diet (ND) for 6 months and isolated vessels exposed to palmitate-high glucose (PA/HG) media. Some WT mice or isolated vessels were treated with an arginase inhibitor, ABH [2-(S)-amino-6-boronohexanoic acid. In WT mice, the HFHS diet promoted increases in body weight, fasting blood glucose, and post-prandial insulin levels along with arterial stiffening and fibrosis, elevated blood pressure, decreased plasma levels of L-arginine, and elevated L-ornithine. The HFHS diet or PA/HG treatment also induced increases in vascular arginase activity along with oxidative stress, reduced vascular NO levels, and impaired endothelial-dependent vasorelaxation. All of these effects except obesity and hypercholesterolemia were prevented or significantly reduced by endothelial-specific deletion of arginase 1 or ABH treatment.

CONCLUSION

Vascular dysfunctions in diet-induced obesity are prevented by deletion of arginase 1 in vascular endothelial cells or arginase inhibition. These findings indicate that upregulation of arginase 1 expression/activity in vascular endothelial cells has an integral role in diet-induced cardiovascular dysfunction and metabolic syndrome.

Modulatory effect of silymarin on inflammatory mediators in experimentally induced benign prostatic hyperplasia: emphasis on PTEN, HIF-1α, and NF-κB

The current study aimed to investigate the potential role of the anti-inflammatory effects of silymarin (SIL) in inhibiting experimentally induced benign prostatic hyperplasia (BPH) in rats. Rats were injected testosterone (3 mg/kg/day, subcutaneously (s.c.)) for 2 weeks. In the treatment group, SIL (50 mg/kg, per orally (p.o.)) was administered daily to rats concomitantly with testosterone. Rats were killed 72 h after the last testosterone injection. Then, prostate tissues were dissected out, weighed, and subjected to histological, immunohistochemical, and biochemical examinations. Rats treated with testosterone showed marked increase in prostate weight and prostate weight/body weight with histopathological picture of inflammation and hyperplasia as well as increased collagen deposition. Co-treatment with SIL significantly alleviated these pathological changes. Further, SIL attenuated testosterone-induced nuclear factor-kappa B (NF-κB), cyclooxygenase-II (COX-II), and inducible nitric oxide synthase (iNOS) upregulation, and blunted testosterone-mediated increase in nitric oxide level and messenger RNA (mRNA) expression of interleukin-6 (IL-6) and IL-8. Testosterone-induced downregulation of phosphatase and tensin homolog (PTEN) and upregulation of hypoxia-inducible factor 1α (HIF-1α) were alleviated by SIL. Our findings highlight the anti-inflammatory properties of SIL as a crucial mechanism of its preventive actions against experimental BPH. This can be attributed to, at least partly, attenuating the expression of NF-kB and the subsequent inflammatory cascade, ameliorating the expression of PTEN, and mitigating that of HIF-1α. These data warrant further investigations for the potential use of SIL in the management of BPH.