1
|
Sharma P, Brown S, Sokoya EM. Re-evaluation of dietary interventions in rheumatoid arthritis: can we improve patient conversations around food choices? Rheumatol Int 2024:10.1007/s00296-024-05541-4. [PMID: 38376558 DOI: 10.1007/s00296-024-05541-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 01/09/2024] [Indexed: 02/21/2024]
Abstract
Rheumatoid arthritis (RA) is one of over 100 different types of autoimmune conditions. In RA, the cells of the immune system attack the tissue lining the joints, triggering inflammation. A large body of research suggests that the underlying trigger(s) of RA are unique to an individual. For example, increased risk of RA can be driven by smoking tobacco in one individual and mercury exposure in another. Due to the development of next-generation sequencing technology, the critical role of the microbiota in shaping RA risk has been elucidated. Therefore, it is surprising that diet, arguably the most important lever in shaping the gut microbiota, is ineffective in the treatment of RA, even in a sub-set of patients. To attempt to rationalise this apparent paradox, we conducted an umbrella review to address the question as to whether diet can affect outcomes in RA.
Collapse
Affiliation(s)
- Prakriti Sharma
- College of Medicine and Public Health, Flinders University, Flinders Health and Medical Research Institute, Adelaide, SA, Australia
| | - Shannon Brown
- Flinders University Library, Adelaide, SA, Australia
| | - Elke M Sokoya
- College of Medicine and Public Health, Flinders University, Flinders Health and Medical Research Institute, Adelaide, SA, Australia.
| |
Collapse
|
2
|
Rustia AJ, Paterson JS, Best G, Sokoya EM. Microbial disruption in the gut promotes cerebral endothelial dysfunction. Physiol Rep 2021; 9:e15100. [PMID: 34755466 PMCID: PMC8578899 DOI: 10.14814/phy2.15100] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 09/02/2021] [Indexed: 12/24/2022] Open
Abstract
Cerebrovascular disease is a group of conditions characterized by disorders of the cerebral vessels. Endothelial dysfunction renders the vasculature at risk of impaired blood flow and increases the potential of developing cerebrovascular disease. The gut microbiota has been recently identified as a possible risk factor of cerebrovascular disease. However, a direct link between gut microbiota and cerebral vascular function has not been established. Therefore, the aim of this study was to determine the effect of gut bacterial disruption on cerebral endothelial function. Male inbred Sprague-Dawley rats were randomly assigned to receive either drinking water with (n = 4) or without (n = 4) a cocktail of nonabsorbable broad-spectrum antibiotics (streptomycin, neomycin, bacitracin, and polymyxin B). Three weeks of antibiotic treatment resulted in a significant reduction in bacterial load and shifts within the bacterial sub-populations as assessed using flow cytometry. Using pressure myography, we found that spontaneous tone significantly increased and L-NAME-induced vasoconstriction was significantly blunted in middle cerebral arteries (MCAs) harvested from antibiotic-treated rats. ATP-mediated dilations were significantly blunted in MCAs from antibiotic-treated rats compared to their control counterparts. Immunoblotting revealed that the eNOS-P/total eNOS ratio was significantly reduced in cerebral artery lysates from antibiotic-treated rats compared to controls. Our findings suggest that disruption of the gut microbiota leads to cerebral endothelial dysfunction through reduction of eNOS activity. This study highlights the potential of the microbiota as a target to reverse endothelial dysfunction and a preventative approach to reducing risk of stroke and aneurysms.
Collapse
Affiliation(s)
- April J. Rustia
- Chronic Disease Research LaboratoryFlinders Health and Medical InstituteCollege of Medicine and Public HealthFlinders UniversityBedford ParkSouth AustraliaAustralia
| | - James S. Paterson
- Microbial Systems LaboratoryCollege of Science and EngineeringFlinders UniversityBedford ParkSouth AustraliaAustralia
| | - Giles Best
- Flow Cytometry FacilityFlinders Health and Medical Research InstituteCollege of Medicine and Public HealthFlinders UniversityBedford ParkSouth AustraliaAustralia
| | - Elke M. Sokoya
- Chronic Disease Research LaboratoryFlinders Health and Medical InstituteCollege of Medicine and Public HealthFlinders UniversityBedford ParkSouth AustraliaAustralia
| |
Collapse
|
3
|
Afroz F, Jonkman E, Hua J, Kist A, Zhou Y, Sokoya EM, Padbury R, Nieuwenhuijs V, Barritt G. Evidence that decreased expression of sinusoidal bile acid transporters accounts for the inhibition by rapamycin of bile flow recovery following liver ischemia. Eur J Pharmacol 2018; 838:91-106. [PMID: 30179613 DOI: 10.1016/j.ejphar.2018.08.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/30/2018] [Accepted: 08/31/2018] [Indexed: 11/16/2022]
Abstract
Rapamycin is employed as an immunosuppressant following organ transplant and, in patients with hepatocellular carcinoma, to inhibit cancer cell regrowth following liver surgery. Preconditioning the liver with rapamycin to induce the expression of antioxidant enzymes is a potential strategy to reduce ischemia reperfusion (IR) injury. However, pre-treatment with rapamycin inhibits bile flow, especially following ischemia. The aim was to investigate the mechanisms involved in this inhibition. In a rat model of segmental hepatic ischemia and reperfusion, acute administration of rapamycin by intravenous injection did not inhibit the basal rate of bile flow. Pre-treatment of rats with rapamycin for 24 h by intraperitoneal injection inhibited the expression of mRNA encoding the sinusoidal influx transporters Ntcp, Oatp1 and 2 and the canalicular efflux transporter Bsep, and increased expression of canalicular Mrp2. Dose-response curves for the actions of rapamycin on the expression of Bsep and Ntcp in cultured rat hepatocytes were biphasic, and monophasic for effects on Oatp1. In cultured tumorigenic H4IIE liver cells, several bile acid transporters were not expressed, or were expressed at very low levels compared to hepatocytes. In H4IIE cells, rapamycin increased expression of Ntcp, Oatp1 and Mrp2, but decreased expression of Oatp2. It is concluded that the inhibition of bile flow recovery following ischemia observed in rapamycin-treated livers is principally due to inhibition of the expression of sinusoidal bile acid transporters. Moreover, in tumorigenic liver tissue the contribution of tumorigenic hepatocytes to total liver bile flow is likely to be small and is unlikely to be greatly affected by rapamycin.
Collapse
Affiliation(s)
- Farhana Afroz
- Department of Medical Biochemistry, Flinders Medical Centre and School of Medicine, Flinders University, Adelaide, South Australia, Australia
| | - Els Jonkman
- Department of Medical Biochemistry, Flinders Medical Centre and School of Medicine, Flinders University, Adelaide, South Australia, Australia
| | - Jin Hua
- Department of Medical Biochemistry, Flinders Medical Centre and School of Medicine, Flinders University, Adelaide, South Australia, Australia
| | - Alwyn Kist
- Department of Medical Biochemistry, Flinders Medical Centre and School of Medicine, Flinders University, Adelaide, South Australia, Australia
| | - Yabin Zhou
- Department of Medical Biochemistry, Flinders Medical Centre and School of Medicine, Flinders University, Adelaide, South Australia, Australia
| | - Elke M Sokoya
- Department of Human Physiology, Flinders Medical Centre and School of Medicine, Flinders University, Adelaide, South Australia, Australia
| | - Robert Padbury
- The HPB and Liver Transplant Unit, Flinders Medical Centre and School of Medicine, Flinders University, Adelaide, South Australia, Australia
| | | | - Greg Barritt
- Department of Medical Biochemistry, Flinders Medical Centre and School of Medicine, Flinders University, Adelaide, South Australia, Australia.
| |
Collapse
|
4
|
Afroz F, Kist A, Hua J, Zhou Y, Sokoya EM, Padbury R, Nieuwenhuijs V, Barritt G. Rapamycin induces the expression of heme oxygenase-1 and peroxyredoxin-1 in normal hepatocytes but not in tumorigenic liver cells. Exp Mol Pathol 2018; 105:334-344. [PMID: 30290159 DOI: 10.1016/j.yexmp.2018.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 08/27/2018] [Accepted: 09/28/2018] [Indexed: 12/14/2022]
Abstract
Rapamycin (sirolimus) is employed as an immunosuppressant following liver transplant, to inhibit the re-growth of cancer cells following liver resection for hepatocellular carcinoma (HCC), and for the treatment of advanced HCC. Rapamycin also induces the expression of antioxidant enzymes in the liver, suggesting that pretreatment with the drug could provide a potential strategy to reduce ischemia reperfusion injury following liver surgery. The aim of this study was to further investigate the actions of rapamycin in inducing expression of the antioxidant enzymes heme oxygenase-1 (HO-1) and peroxiredoxin-1 (Prx-1) in normal liver and in tumorigenic liver cells. A rat model of segmental hepatic ischemia and reperfusion, cultured freshly-isolated rat hepatocytes, and tumorigenic H4IIE rat liver cells in culture were employed. Expression of HO-1 and Prx-1 was measured using quantitative PCR and western blot. Rapamycin pre-treatment of normal liver in vivo or normal hepatocytes in vitro led to a substantial induction of mRNA encoding HO-1 and Prx-1. The dose-response curve for the action of rapamycin on mRNA expression was biphasic, showing an increase in expression at 0 - 0.1 μM rapamycin but a decrease from maximum at concentrations greater than 0.1 μM. By contrast, in H4IIE cells, rapamycin inhibited the expression of HO-1 and Prx-1 mRNA. Oltipraz, an established activator of transcription factor Nrf2, caused a large induction of HO-1 and Prx-1 mRNA. The dose response curve for the inhibition by rapamycin of HO-1 and Prx-4 mRNA expression, determined in the presence of oltipraz, was monophasic with half maximal inhibition at about 0.01 μM. It is concluded that, at concentrations comparable to those used clinically, pre-treatment of the liver with rapamycin induces the expression of HO-1 and Prx-1. However, the actions of rapamycin on the expression of these two antioxidant enzymes in normal hepatocytes are complex and, in tumorigenic liver cells, differ from those in normal hepatocytes. Further studies are warranted to evaluate preconditioning the livers of patients subject to liver resection or liver transplant with rapamycin as a viable strategy to reduce IR injury following liver surgery.
Collapse
Affiliation(s)
- Farhana Afroz
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Alwyn Kist
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Jin Hua
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Yabin Zhou
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Elke M Sokoya
- Discipline of Human Physiology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Robert Padbury
- The HPB and Liver Transplant Unit, Flinders Medical Centre and College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | | | - Greg Barritt
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.
| |
Collapse
|
5
|
Kontos A, Lushington K, Martin J, Schwarz Q, Green R, Wabnitz D, Xu X, M Sokoya E, Willoughby S, Baumert M, Ferrante A, La Forgia M, Kennedy D. Relationship between Vascular Resistance and Sympathetic Nerve Fiber Density in Arterial Vessels in Children With Sleep Disordered Breathing. J Am Heart Assoc 2017; 6:JAHA.117.006137. [PMID: 28716800 PMCID: PMC5586314 DOI: 10.1161/jaha.117.006137] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Background Sleep disordered breathing in children is associated with increased blood flow velocity and sympathetic overactivity. Sympathetic overactivity results in peripheral vasoconstriction and reduced systemic vascular compliance, which increases blood flow velocity during systole. Augmented blood flow velocity is recognized to promote vascular remodeling. Importantly, increased vascular sympathetic nerve fiber density and innervation in early life plays a key role in the development of early‐onset hypertension in animal models. Examination of sympathetic nerve fiber density of the tonsillar arteries in children undergoing adenotonsillectomy for Sleep disordered breathing will address this question in humans. Methods and Results Thirteen children scheduled for adenotonsillectomy to treat sleep disordered breathing underwent pupillometry, polysomnography, flow‐mediated dilation, resting brachial artery blood flow velocity (velocity time integral), and platelet aggregation. The dorsal lingual artery (tonsil) was stained and immunofluorescence techniques used to determine sympathetic nerve fiber density. Sympathetic nerve fiber density was correlated with increased resting velocity time integral (r=0.63; P<0.05) and a lower Neuronal Pupillary Index (r=−0.71, P<0.01), as well as a slower mean pupillary constriction velocity (mean, r=−0.64; P<0.05). A faster resting velocity time integral was associated with a slower peak pupillary constriction velocity (r=−0.77; P<0.01) and higher platelet aggregation to collagen antigen (r=0.64; P<0.05). Slower mean and peak pupillary constriction velocity were associated with higher platelet aggregation scores (P<0.05; P<0.01, respectively). Conclusions These results indicate that sympathetic activity is associated with change in both the function and structure of systemic vasculature in children with sleep disordered breathing.
Collapse
Affiliation(s)
- Anna Kontos
- Robinson's Research Institute, School of Medicine, Discipline of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, Australia
| | - Kurt Lushington
- School of Psychology, Social Work and Social Policy, University of South Australia, Adelaide, Australia
| | - James Martin
- Robinson's Research Institute, School of Medicine, Discipline of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, Australia.,Department of Respiratory and Sleep Medicine, Women's and Children's Hospital, Adelaide, Australia
| | - Quenten Schwarz
- Neurovascular Research Laboratory, Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Ryan Green
- Department of Information Technology, Engineering and the Environment, University of South Australia, Adelaide, Australia
| | - David Wabnitz
- Department of Otolaryngology-Head and Neck Surgery, Women's and Children's Hospital, Adelaide, Australia
| | - Xiangjun Xu
- Neurovascular Research Laboratory, Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Elke M Sokoya
- Department of Human Physiology, Flinders University, Adelaide, South Australia, Australia
| | - Scott Willoughby
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Mathias Baumert
- School of Electrical and Electronic Engineering, University of Adelaide, Adelaide, Australia
| | - Antonio Ferrante
- Robinson's Research Institute, School of Medicine, Discipline of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, Australia.,Department of Immunology SA Pathology, Schools of Medicine and Biological Science, University of Adelaide, Adelaide, Australia
| | - Melissa La Forgia
- Department of Medical Imaging, Women's and Children's Hospital, Adelaide, Australia
| | - Declan Kennedy
- Robinson's Research Institute, School of Medicine, Discipline of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, Australia.,Department of Respiratory and Sleep Medicine, Women's and Children's Hospital, Adelaide, Australia
| |
Collapse
|
6
|
Dwinovan J, Colella AD, Chegeni N, Chataway TK, Sokoya EM. Proteomic analysis reveals downregulation of housekeeping proteins in the diabetic vascular proteome. Acta Diabetol 2017; 54:171-190. [PMID: 27796656 DOI: 10.1007/s00592-016-0929-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/07/2016] [Indexed: 02/04/2023]
Abstract
AIMS Type 2 diabetes (T2D) increases the risk of death associated with cardiovascular complications. However, a complete understanding of protein changes within the diabetic vasculature is still lacking. METHODS Herein, we utilized mass spectrometry to perform vascular and urinary proteome analysis using a rat model of high-fat feeding and low-dose streptozotocin to simulate late-stage T2D. The purpose of this study was to identify aortic and urine proteins that are differentially expressed in normal and T2D rats. RESULTS High-fat feeding and low-dose streptozotocin resulted in hyperglycemia, hypoinsulinemia and high levels of circulating free fatty acids. Using a shotgun proteomic approach, high-mobility-group protein B1 and spondin-1 were significantly increased in T2D aorta compared to control aorta, suggesting vascular inflammation and smooth muscle proliferation, respectively. However, the majority of differentially expressed aortic proteins were downregulated in T2D, including proteins associated with coagulation, cell differentiation and redox homeostasis. Strikingly, we report a significant downregulation of commonly used cytoskeletal housekeeping proteins in T2D aorta. Urine from T2D rats displayed increased expression of proteins involved in inflammation and oxidative stress and decreased expression of proteins associated with lipid metabolism and cell adhesion. A number of differentially expressed proteins in urine of T2D rats have previously been reported in human T2D, thereby supporting this animal model as a good representation of human T2D. CONCLUSIONS Our data offer new information regarding key pathways that could be therapeutically targeted to combat the cardiovascular complications of T2D.
Collapse
Affiliation(s)
- Josua Dwinovan
- Discipline of Human Physiology, School of Medicine, Flinders University, Room 4E 432, Flinders Medical Centre, Flinders Drive, Bedford Park, SA, 5042, Australia
| | - Alexander D Colella
- Discipline of Human Physiology, School of Medicine, Flinders University, Room 4E 432, Flinders Medical Centre, Flinders Drive, Bedford Park, SA, 5042, Australia
| | - Nusha Chegeni
- Discipline of Human Physiology, School of Medicine, Flinders University, Room 4E 432, Flinders Medical Centre, Flinders Drive, Bedford Park, SA, 5042, Australia
| | - Timothy K Chataway
- Discipline of Human Physiology, School of Medicine, Flinders University, Room 4E 432, Flinders Medical Centre, Flinders Drive, Bedford Park, SA, 5042, Australia
| | - Elke M Sokoya
- Discipline of Human Physiology, School of Medicine, Flinders University, Room 4E 432, Flinders Medical Centre, Flinders Drive, Bedford Park, SA, 5042, Australia.
| |
Collapse
|
7
|
Tajbakhsh N, Sokoya EM. Compromised endothelium-dependent hyperpolarization-mediated dilations can be rescued by NS309 in obese Zucker rats. Microcirculation 2015; 21:747-53. [PMID: 25047389 DOI: 10.1111/micc.12157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/15/2014] [Accepted: 07/17/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVE NO and a non-NO/prostacyclin EDH mechanism are major contributors of vascular tone and cerebral blood flow. However, the effect of metabolic syndrome on EDH-mediated responses in cerebral vessels remains unknown and may offer another avenue for therapeutic targeting. The purpose of this study was to investigate EDH-dependent responses in cerebral arteries during metabolic syndrome. METHODS EDH-dependent dilations were assessed in MCAs isolated from nondiabetic obese and lean Zucker rats in the presence and absence of NS309, an activator of SKCa and IKCa channels. IKCa channel expression and activity were assessed by western blotting and pressure myography, respectively. RESULTS EDH-mediated dilations were significantly attenuated in the obese compared to the lean Zucker rat MCA. Luminal delivery of 1 μM NS309 enhanced EDH-mediated responses in lean and obese Zucker cerebral vessels. Both dose-dependent dilations to luminal NS309 and IKCa protein expression in pooled cerebral arteries were comparable between the two groups. CONCLUSIONS Our results suggest that pharmacological targeting of IKCa channels can rescue EDH-mediated dilations in obese Zucker rat MCAs. Compromised EDH-mediated dilations in obesity are not due to impaired IKCa channel expression or activity.
Collapse
Affiliation(s)
- Negara Tajbakhsh
- Discipline of Medical Biotechnology, School of Medicine, Flinders University, Bedford Park, South Australia, Australia
| | | |
Collapse
|
8
|
Tajbakhsh S, Aliakbari K, Hussey DJ, Lower KM, Donato AJ, Sokoya EM. Differential Telomere Shortening in Blood versus Arteries in an Animal Model of Type 2 Diabetes. J Diabetes Res 2015; 2015:153829. [PMID: 26346823 PMCID: PMC4545169 DOI: 10.1155/2015/153829] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 07/20/2015] [Accepted: 07/26/2015] [Indexed: 11/18/2022] Open
Abstract
Vascular dysfunction is an early feature of diabetic vascular disease, due to increased oxidative stress and reduced nitric oxide (NO) bioavailability. This can lead to endothelial cell senescence and clinical complications such as stroke. Cells can become senescent by shortened telomeres and oxidative stress is known to accelerate telomere attrition. Sirtuin 1 (SIRT1) has been linked to vascular health by upregulating endothelial nitric oxide synthase (eNOS), suppressing oxidative stress, and attenuating telomere shortening. Accelerated leukocyte telomere attrition appears to be a feature of clinical type 2 diabetes (T2D) and therefore the telomere system may be a potential therapeutic target in preventing vascular complications of T2D. However the effect of T2D on vascular telomere length is currently unknown. We hypothesized that T2D gives rise to shortened leukocyte and vascular telomeres alongside reduced vascular SIRT1 expression and increased oxidative stress. Accelerated telomere attrition was observed in circulating leukocytes, but not arteries, in T2D compared to control rats. T2D rats had blunted arterial SIRT1 and eNOS protein expression levels which were associated with reduced antioxidant defense capacity. Our findings suggest that hyperglycemia and a deficit in vascular SIRT1 per se are not sufficient to prematurely shorten vascular telomeres.
Collapse
Affiliation(s)
- Samira Tajbakhsh
- Discipline of Biotechnology, School of Medicine, Flinders University, Bedford Park, SA 5042, Australia
| | - Kamelya Aliakbari
- Discipline of Biotechnology, School of Medicine, Flinders University, Bedford Park, SA 5042, Australia
| | - Damian J. Hussey
- Discipline of Surgery, School of Medicine, Flinders University, Bedford Park, SA 5042, Australia
| | - Karen M. Lower
- Discipline of Haematology, School of Medicine, Flinders University, Bedford Park, SA 5042, Australia
| | - Anthony J. Donato
- Department of Internal Medicine, University of Utah, Salt Lake City, UT 84132, USA
| | - Elke M. Sokoya
- Discipline of Human Physiology, School of Medicine, Flinders University, Bedford Park, SA 5042, Australia
- *Elke M. Sokoya:
| |
Collapse
|
9
|
Tajbakhsh N, Sokoya EM. Sirtuin 1 is upregulated in young obese Zucker rat cerebral arteries. Eur J Pharmacol 2013; 721:43-8. [PMID: 24113524 DOI: 10.1016/j.ejphar.2013.09.057] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 09/20/2013] [Accepted: 09/26/2013] [Indexed: 12/11/2022]
Abstract
Many diseases, including metabolic syndrome, are characterised by endothelial dysfunction mediated by reduced nitric oxide bioavailability and oxidative stress. Sirtuin 1 is a protein deacetylase that targets endothelial nitric oxide synthase resulting in enhanced nitric oxide bioavailability. Although it has been highlighted as a potential therapeutic target, we still have no understanding of vascular SIRT1 changes during obesity. Therefore, the aim of the present study was to measure vascular function, SIRT1 protein levels of expression and markers of oxidative stress in obese Zucker rats. Middle cerebral arteries from nondiabetic obese and lean Zucker rats were mounted in a pressure myograph to assess nitric oxide-dependent dilations. Western blotting was used to measure protein levels of SIRT1, p53, acetylated p53, eNOS, phosphorylated eNOS and markers of oxidative stress (nitrotyrosine, Nox4 and SOD2) in cerebral vascular tissue. SIRT1 expression was two-fold greater in both cerebral arteries and aorta from obese compared to lean Zucker rats. Acetylation of p53 at the SIRT1-specific lysine 379 site was markedly decreased. At the same time, there was noted cerebral vascular impairment however markers of oxidative stress were not increased. In fact, Nox4 appeared to be downregulated in obesity. Thus, SIRT1 protein levels within the vasculature are greater in obese compared to lean Zucker rats and are associated with higher SIRT1 activity and lower Nox4 expression. We propose that the increased expression and activity of SIRT1 may be a vascular adaptive mechanism in obesity, aiming to prevent oxidative stress.
Collapse
Affiliation(s)
- Negara Tajbakhsh
- Disciplines of Medical Biotechnology, School of Medicine, Flinders University, Bedford Park, SA 5042, Australia
| | | |
Collapse
|
10
|
Burns AR, Phillips SC, Sokoya EM. Pannexin protein expression in the rat middle cerebral artery. J Vasc Res 2012; 49:101-10. [PMID: 22301733 DOI: 10.1159/000332329] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 08/19/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Connexin proteins are well known to participate in cell-to-cell communication within the cerebral vasculature. Pannexins are a recently discovered family of proteins that could potentially be involved in cell-to-cell communication. Herein, we sought to determine whether pannexins are expressed in rat middle cerebral artery (MCA). METHODS A combination of RT-PCR, immunoblotting and immunohistochemistry techniques was used to characterize the expression pattern of pannexins in rat MCA. A fluorescent dye uptake approach in cultured smooth muscle cells was used to determine whether these cells have functional hemichannels. RESULTS We report for the first time that pannexins are expressed in the cerebral vasculature. We reveal that pannexin 1 is expressed in smooth muscle but not in endothelium and pannexin 2 is expressed in both endothelium and smooth muscle. Fluorescent dye entered cultured smooth muscle cells in the absence of extracellular calcium or when the cells were depolarized, which was prevented by the putative hemichannel blocker carbenoxolone. CONCLUSIONS The identification of pannexins in rat MCA indicates that pannexin expression is not restricted to neuronal cells. Dye uptake in cultured smooth muscle cells exhibited properties similar to those of connexin and pannexin hemichannels, which may represent another form of cell-to-cell communication within the vasculature.
Collapse
Affiliation(s)
- Alan R Burns
- College of Optometry, University of Houston, Houston, Tex., USA
| | | | | |
Collapse
|
11
|
Chen J, Burns AR, Phillips SC, Sokoya EM. Pannexin protein expression in the rat middle cerebral artery. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1144.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jie Chen
- Department of AnesthesiologyBaylor College of MedicineHoustonTX
| | - Alan R. Burns
- Department of AnesthesiologyBaylor College of MedicineHoustonTX
| | | | - Elke M. Sokoya
- Department of AnesthesiologyBaylor College of MedicineHoustonTX
| |
Collapse
|
12
|
Sokoya EM, Burns AR, Marrelli SP, Chen J. Myoendothelial gap junction frequency does not account for sex differences in EDHF responses in rat MCA. Microvasc Res 2007; 74:39-44. [PMID: 17490692 PMCID: PMC1995456 DOI: 10.1016/j.mvr.2007.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 03/28/2007] [Accepted: 03/29/2007] [Indexed: 11/16/2022]
Abstract
Previous findings from our laboratory have shown that dilations to endothelium-derived hyperpolarizing factor (EDHF) in rat middle cerebral artery (MCA) are less in females compared to males. Myoendothelial gap junctions (MEGJs) appear to mediate the transfer of hyperpolarization between endothelium and smooth muscle in males. In the present study, we hypothesized that MEGJs are the site along the EDHF pathway which is compromised in female rat MCA. Membrane potential in endothelium was measured using the voltage-sensitive dye di-8-ANEPPS and in smooth muscle using intracellular glass microelectrodes in the presence of l-NAME (3x10(-5 )M) and indomethacin (10(-5 )M). Electron microscopy was used to assess MEGJ characteristics. In endothelial cells, the di-8-ANEPPS fluorescence ratio change to 10(-5 )M UTP was similar in males (-2.9+/-0.5%) and females (-3.2+/-0.2%), indicating comparable degrees of endothelial cell hyperpolarization. However, smooth muscle cell hyperpolarization to 10(-5 )M UTP was significantly attenuated in females (0 mV hyperpolarization; -31+/-1.5 mV resting) compared to males (8 mV hyperpolarization; -28+/-1.7 mV resting). Ultrastructural evidence suggested that MEGJ frequency and area of contact were comparable between males and females. Taken together, our data suggest that in rat MCA, MEGJ frequency does not account for the reduced EDHF responses observed in females compared to males. We conclude that reduced myoendothelial coupling and/or homocellular coupling within the media may account for these differences.
Collapse
Affiliation(s)
- Elke M Sokoya
- Department of Anesthesiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
| | | | | | | |
Collapse
|
13
|
Sokoya EM, You J, Chen J. DCEBIO-Mediated Dilations Are Attenuated in the Female Rat Middle Cerebral Artery. J Vasc Res 2007; 44:169-74. [PMID: 17308435 DOI: 10.1159/000099630] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 12/07/2006] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Unlike in peripheral vessels, the endothelium-derived hyperpolarizing factor (EDHF)-mediated component to P2Y(2) receptor-mediated dilations is significantly attenuated in the middle cerebral artery (MCA) of female rats compared to male rats. One aspect to the EDHF phenomenon is activation of the intermediate calcium-sensitive potassium (IK(Ca)) channels located on the endothelium. In an attempt to pinpoint the site along the EDHF pathway that is compromised in females, we tested the hypothesis that direct activation of IK(Ca) channels with DCEBIO would elicit attenuated hyperpolarization in the endothelium and smooth muscle of females compared to males. METHODS Inhibitors of nitric oxide synthase and cyclooxygenase were present throughout all experiments. Vessel diameter changes were assessed in pressurized and luminally perfused MCAs. Membrane potential changes in the endothelium and smooth muscle were measured using the perforated patch clamp method and sharp electrodes, respectively. RESULTS AND CONCLUSIONS The maximum vasodilation to 3 x 10(-4)M DCEBIO was significantly reduced in females (37 +/- 9%) compared to intact males (70 +/- 4%). Endothelial cell hyperpolarization to DCEBIO was similar in both males and females. Smooth muscle cell hyperpolarization was attenuated in females (2 +/- 1 mV) compared to males (15 +/- 3 mV). Taken together, our data suggest that the transfer of hyperpolarization from the endothelium to the smooth muscle is impeded in the female rat MCA.
Collapse
Affiliation(s)
- Elke M Sokoya
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX 77030, USA.
| | | | | |
Collapse
|
14
|
Sokoya EM, You J. Impaired cAMP signaling does not account for the attenuated EDHF-mediated dilations in female rat middle cerebral artery. Brain Res 2007; 1139:29-33. [PMID: 17270155 PMCID: PMC1850227 DOI: 10.1016/j.brainres.2007.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 12/11/2006] [Accepted: 01/02/2007] [Indexed: 10/23/2022]
Abstract
Dilations to endothelium-derived hyperpolarizing factor (EDHF) are significantly attenuated in the middle cerebral artery (MCA) isolated from female compared to male rats. Since gap junctions appear to be involved in the EDHF pathway and cAMP has been shown to enhance gap junction permeability, we tested the hypothesis that elevation of cAMP would enhance EDHF-mediated dilations in female rat MCA. Vascular diameter was measured in perfused MCA segments using videomicroscopy in the presence and absence of IBMX, an inhibitor of cAMP phosphodiesterase. In the presence of L-NAME and indomethacin, dilation to 10(-4) M ATP was significantly reduced in females (48+/-12%) compared to males (92+/-2%). IBMX, an inhibitor of cAMP phosphodiesterase, had no significant effect on ATP-mediated dilations in both males and females. Basal cAMP levels were comparable in male and female MCAs (1.7 pmol/mg protein). Incubation with IBMX (2 x 10(-4) M) significantly elevated cAMP in both male (12.8 pmol/mg protein) and female (11.2 pmol/mg protein) MCAs. Our results demonstrate that reduced EDHF dilations in female rat MCA cannot be solely attributed to impaired cAMP signaling. Future studies will target other potential sites along the EDHF pathway in order to identify why EDHF dilations are reduced in the female compared to the male rat MCA.
Collapse
Affiliation(s)
- Elke M Sokoya
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX 77030, USA.
| | | |
Collapse
|
15
|
Prisby RD, Wilkerson MK, Sokoya EM, Bryan RM, Wilson E, Delp MD. Endothelium-dependent vasodilation of cerebral arteries is altered with simulated microgravity through nitric oxide synthase and EDHF mechanisms. J Appl Physiol (1985) 2006; 101:348-53. [PMID: 16627679 DOI: 10.1152/japplphysiol.00941.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cephalic elevations in arterial pressure associated with microgravity and prolonged bed rest alter cerebrovascular autoregulation in humans. Using the head-down tail-suspended (HDT) rat to chronically induce headward fluid shifts and elevate cerebral artery pressure, previous work has likewise shown cerebral perfusion to be diminished. The purpose of this study was to test the hypothesis that 2 wk of HDT reduces cerebral artery vasodilation. To test this hypothesis, dose-response relations for endothelium-dependent (2-methylthioadenosine triphosphate and bradykinin) and endothelium-independent (nitroprusside) vasodilation were determined in vitro in middle cerebral arteries (MCAs) from HDT and control rats. All in vitro measurements were done in the presence and absence of the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (10(-5) M) and cyclooxygenase inhibitor indomethacin (10(-5) M). MCA caveolin-1 protein content was measured by immunoblot analysis. Endothelium-dependent vasodilation to 2-methylthioadenosine triphosphate and bradykinin were both lower in MCAs from HDT rats. These lower vasodilator responses were abolished with N(G)-nitro-L-arginine methyl ester but were unaffected by indomethacin. In addition, HDT was associated with lower levels of MCA caveolin-1 protein. Endothelium-independent vasodilation was not altered by HDT. These results indicate that chronic cephalic fluid shifts diminish endothelium-dependent vasodilation through alterations in the endothelial nitric oxide synthase signaling mechanism. Such decrements in endothelium-dependent vasodilation of cerebral arteries could contribute to the elevations in cerebral vascular resistance and reductions in cerebral perfusion that occur after conditions of simulated microgravity in HDT rats.
Collapse
Affiliation(s)
- Rhonda D Prisby
- Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, West Virginia 26506, USA.
| | | | | | | | | | | |
Collapse
|
16
|
Sokoya EM, Burns AR, Setiawan CT, Coleman HA, Parkington HC, Tare M. Evidence for the involvement of myoendothelial gap junctions in EDHF-mediated relaxation in the rat middle cerebral artery. Am J Physiol Heart Circ Physiol 2006; 291:H385-93. [PMID: 16443675 DOI: 10.1152/ajpheart.01047.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms underlying endothelium-dependent hyperpolarizing factor (EDHF) in the middle cerebral artery (MCA) remain largely unresolved. In particular, very little is known regarding the way in which the signal is transmitted from endothelium to smooth muscle. The present study tested the hypothesis that direct communication via myoendothelial gap junctions contributes to the EDHF response in the male rat MCA. EDHF-mediated dilations were elicited in rat MCAs by luminal application of ATP or UTP in the presence of Nomega-nitro-L-arginine methyl ester and indomethacin. Maximum dilation to luminal ATP (10(-4) M) was reduced significantly after incubation with a gap peptide cocktail (9 +/- 4%, n = 6) compared with a scrambled gap peptide cocktail (99 +/- 1%, n = 6, P < 0.05). A gap peptide cocktail had no effect on amplitude of endothelial cell hyperpolarization in response to 3 x 10(-5) M UTP (22 +/- 3 vs. 22 +/- 1 mV, n = 4), whereas smooth muscle cell hyperpolarization was significantly attenuated (17 +/- 1 vs. 6 +/- 1 mV, n = 4, P = 0.004). Connexin (Cx) 37 was localized to smooth muscle and Cx43 to endothelium, whereas Cx40 was found in endothelium and smooth muscle. Electron microscopy revealed the existence of frequent myoendothelial junctions. The total number of myoendothelial junctions per 5 microm of MCA sectioned was 2.5 +/- 0.5. Our results suggest that myoendothelial communication contributes to smooth muscle cell hyperpolarization and EDHF dilation in male rat MCA.
Collapse
Affiliation(s)
- Elke M Sokoya
- Department of Anesthesiology, Baylor College of Medicine, Houston, TX 77030, USA.
| | | | | | | | | | | |
Collapse
|