ORCID Profile
0000-0002-2128-1281
Current Organisation
Monash University
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Publisher: Proceedings of the National Academy of Sciences
Date: 23-04-2021
Abstract: Neutralizing antibodies are important for immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and as therapeutics for the prevention and treatment of COVID-19. We identified high-affinity nanobodies against SARS-CoV-2 receptor-binding domain and found that nanobody cocktails consisting of two noncompeting nanobodies were able to block ACE2 engagement with RBD variants present in human populations and potently neutralize both wild-type SARS-CoV-2 and the N501Y D614G variant at low concentrations. Prophylactic administration of nanobody cocktails reduced viral loads in mice infected with the N501Y D614G SARS-CoV-2 virus, showing that nanobody cocktails are useful as prophylactic agents against SARS-CoV-2.
Publisher: Portland Press Ltd.
Date: 17-06-2014
DOI: 10.1042/CS20140045
Abstract: RAGE (receptor for advanced glycation end-products) is expressed on multiple cell types implicated in the progression of atherosclerosis and plays a role in DAA (diabetes-associated atherosclerosis). The aim of the present study was to determine the relative role of either BM (bone marrow)- or non-BM-derived RAGE in the pathogenesis of STZ (streptozotocin)-induced DAA. Male ApoE (apolipoprotein E)-null (ApoE−/−:RAGE+/+) and ApoE:RAGE-null (ApoE−/−:RAGE−/−) mice at 7 weeks of age were rendered diabetic with STZ. At 8 weeks of age, ApoE−/− and ApoE−/−:RAGE−/− control and diabetic mice received BM from either RAGE-null or RAGE-bearing mice, generating various chimaeras. After 10 and 20 weeks of diabetes, mice were killed and gene expression and atherosclerotic lesion formation were evaluated respectively. Deletion of RAGE in either the BM cells or non-BM cells both resulted in a significant attenuation in DAA, which was associated with reduced VCAM-1 (vascular cell adhesion molecule-1) expression and translated into reduced adhesion in vitro. In conclusion, the results of the present study highlight the importance of both BM- and non-BM-derived RAGE in attenuating the development of DAA.
Publisher: American Diabetes Association
Date: 17-07-2012
DOI: 10.2337/DB11-1546
Abstract: Advanced glycation end products (AGEs) are important mediators of diabetic nephropathy that act through the receptor for AGEs (RAGE), as well as other mechanisms, to promote renal inflammation and glomerulosclerosis. The relative contribution of RAGE-dependent and RAGE-independent signaling pathways has not been previously studied in vivo. In this study, diabetic RAGE apoE double-knockout (KO) mice with streptozotocin-induced diabetes were treated with the AGE inhibitor, alagebrium (1 mg/kg/day), or the ACE inhibitor, quinapril (30 mg/kg/day), for 20 weeks, and renal parameters were assessed. RAGE deletion attenuated mesangial expansion, glomerular matrix accumulation, and renal oxidative stress associated with 20 weeks of diabetes. By contrast, inflammation and AGE accumulation associated with diabetes was not prevented. However, treatment with alagebrium in diabetic RAGE apoE KO mice reduced renal AGE levels and further reduced glomerular matrix accumulation. In addition, even in the absence of RAGE expression, alagebrium attenuated cortical inflammation, as denoted by the reduced expression of monocyte chemoattractant protein-1, intracellular adhesion molecule-1, and the macrophage marker cluster of differentiation molecule 11b. These novel findings confirm the presence of important RAGE-independent as well as RAGE-dependent signaling pathways that may be activated in the kidney by AGEs. This has important implications for the design of optimal therapeutic strategies for the prevention of diabetic nephropathy.
Publisher: Elsevier BV
Date: 12-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2017
DOI: 10.1097/CCM.0000000000002070
Abstract: To study the effect of a lack of antioxidant defenses during lethal pneumonia induced by Klebsiella pneumonia , compared to wild-type mice. Laboratory experiments. C57Bl6 and glutathione peroxidase 1 knockout mice. Murine acute pneumonia model induced by Klebsiella pneumonia . We show here that despite a lack of one of the major antioxidant defense enzymes, glutathione peroxidase 1 knockout mice are protected during lethal pneumonia induced by Klebsiella pneumonia , compared to wild-type mice. Furthermore, this protective effect was suppressed when antioxidant defenses were restored. Infected glutathione peroxidase 1 mice showed an early and significant, albeit transient, increase in the activity of the NOD-like receptor family, pyrin domain containing 3 inflammasome when compared with wild-type mice. The key role of the NOD-like receptor family, pyrin domain containing 3 inflammasome during acute pneumonia was confirmed in vivo when the protective effect was suppressed by treating glutathione peroxidase 1 mice with an interleukin-1 receptor antagonist. Additionally we report, in vitro, that increased concentrations of active caspase-1 and interleukin-1β are related to an increased concentration of hydrogen peroxide in bacterially infected glutathione peroxidase 1 macrophages and that restoring hydrogen peroxide antioxidant defenses suppressed this effect. Our findings demonstrate that, contrary to current thinking, an early intervention targeting NOD-like receptor family, pyrin domain containing 3 inflammasome activity induces a timely and efficient activation of the innate immune response during acute infection. Our findings also demonstrate a role for hydrogen peroxide in the mechanisms tightly regulating NOD-like receptor family, pyrin domain containing 3 activation.
Publisher: Public Library of Science (PLoS)
Date: 18-03-2015
Publisher: Proceedings of the National Academy of Sciences
Date: 31-07-2023
Abstract: The ersity of COVID-19 disease in otherwise healthy people, from seemingly asymptomatic infection to severe life-threatening disease, is not clearly understood. We passaged a naturally occurring near-ancestral SARS-CoV-2 variant, capable of infecting wild-type mice, and identified viral genomic mutations coinciding with the acquisition of severe disease in young adult mice and lethality in aged animals. Transcriptomic analysis of lung tissues from mice with severe disease elucidated a host antiviral response dominated mainly by interferon and IL-6 pathway activation in young mice, while in aged animals, a fatal outcome was dominated by TNF and TGF-β signaling. Congruent with our pathway analysis, we showed that young TNF-deficient mice had mild disease compared to controls and aged TNF-deficient animals were more likely to survive infection. Emerging clinical correlates of disease are consistent with our preclinical studies, and our model may provide value in defining aberrant host responses that are causative of severe COVID-19.
Publisher: Wiley
Date: 2018
DOI: 10.1002/CTI2.1016
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-09-2020
DOI: 10.1161/CIRCRESAHA.120.316653
Abstract: Treatment efficacy for diabetes mellitus is largely determined by assessment of HbA1c (glycated hemoglobin A1c) levels, which poorly reflects direct glucose variation. People with prediabetes and diabetes mellitus spend % of their time outside the optimal glucose range. These glucose variations, termed transient intermittent hyperglycemia (TIH), appear to be an independent risk factor for cardiovascular disease, but the pathological basis for this association is unclear. To determine whether TIH per se promotes myelopoiesis to produce more monocytes and consequently adversely affects atherosclerosis. To create a mouse model of TIH, we administered 4 bolus doses of glucose at 2-hour intervals intraperitoneally once to WT (wild type) or once weekly to atherosclerotic prone mice. TIH accelerated atherogenesis without an increase in plasma cholesterol, seen in traditional models of diabetes mellitus. TIH promoted myelopoiesis in the bone marrow, resulting in increased circulating monocytes, particularly the inflammatory Ly6-C hi subset, and neutrophils. Hematopoietic-restricted deletion of S100a9 , S100a8 , or its cognate receptor Rage prevented monocytosis. Mechanistically, glucose uptake via GLUT (glucose transporter)-1 and enhanced glycolysis in neutrophils promoted the production of S100A8/A9. Myeloid-restricted deletion of Slc2a1 (GLUT-1) or pharmacological inhibition of S100A8/A9 reduced TIH-induced myelopoiesis and atherosclerosis. Together, these data provide a mechanism as to how TIH, prevalent in people with impaired glucose metabolism, contributes to cardiovascular disease. These findings provide a rationale for continual glucose control in these patients and may also suggest that strategies aimed at targeting the S100A8/A9-RAGE (receptor for advanced glycation end products) axis could represent a viable approach to protect the vulnerable blood vessels in diabetes mellitus. A graphic abstract is available for this article.
Publisher: Informa UK Limited
Date: 03-10-2018
DOI: 10.1080/10715762.2018.1533636
Abstract: Inflammation is a protective immune response against invading pathogens, however, dysregulated inflammation is detrimental. As the complex inflammatory response involves multiple mediators, including the involvement of reactive oxygen species, concomitantly targeting proinflammatory and antioxidant check-points may be a more rational strategy. We report the synthesis and anti-inflammatory/antioxidant activity of a novel indanedione derivative DMFO. DMFO scavenged reactive oxygen species (ROS) in
Publisher: American Diabetes Association
Date: 15-02-2018
DOI: 10.2337/DB17-0538
Abstract: Signaling via the receptor of advanced glycation end products (RAGE)—though complex and not fully elucidated in the setting of diabetes—is considered a key injurious pathway in the development of diabetic nephropathy (DN). We report here that RAGE deletion resulted in increased expression of fibrotic markers (collagen I and IV, fibronectin) and the inflammatory marker MCP-1 in primary mouse mesangial cells (MCs) and in kidney cortex. RNA sequencing analysis in MCs from RAGE−/− and wild-type mice confirmed these observations. Nevertheless, despite these gene expression changes, decreased responsiveness to transforming growth factor-β was identified in RAGE−/− mice. Furthermore, RAGE deletion conferred a more proliferative phenotype in MCs and reduced susceptibility to staurosporine-induced apoptosis. RAGE restoration experiments in RAGE−/− MCs largely reversed these gene expression changes, resulting in reduced expression of fibrotic and inflammatory markers. This study highlights that protection against DN in RAGE knockout mice is likely to be due in part to the decreased responsiveness to growth factor stimulation and an antiapoptotic phenotype in MCs. Furthermore, it extends our understanding of the role of RAGE in the progression of DN, as RAGE seems to play a key role in modulating the sensitivity of the kidney to injurious stimuli such as prosclerotic cytokines.
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.METABOL.2014.11.004
Abstract: This study aimed at investigating the effects of genetic angiotensin-converting enzyme (ACE) 2 deficiency on glucose homeostasis in the pancreas and skeletal muscle and their reversibility following ACE inhibition. ACE2-knockout and C57bl6J mice were placed on a standard diet (SD) or a high-fat diet (HFD) for 12 weeks. An additional group of ACE2-knockout mice was fed a SD and treated with the ACE inhibitor, perindopril (2 mg kg(-1)day(-1)). Glucose and insulin tolerance tests, indirect calorimetry measurements and EchoMRI were performed. Non-esterfied 'free' fatty acid oxidation rate in skeletal muscle was calculated by measuring the palmitate oxidation rate. β-cell mass was determined by immunostaining. Insulin, collectrin, glucose transporter protein, and peroxisome proliferator-activated receptor-γ expression were analysed by RT-PCR. Markers of mithocondrial biogenesis/content were also evaluated. ACE2-knockout mice showed a β-cell defect associated with low insulin and collectrin levels and reduced compensatory hypertrophy in response to a HFD, which were not reversed by perindopril. On the other hand, ACE2 deficiency shifted energy metabolism towards glucose utilization, as it increased the respiratory exchange ratio, reduced palmitate oxidation and PCG-1α expression in the skeletal muscle, where it up-regulated glucose transport proteins. Treatment of ACE2-knockout mice with perindopril reversed the skeletal muscle changes, suggesting that these were dependent on Angiotensin II (Ang II). ACE2-knockout mice display a β-cell defect, which does not seem to be dependent on Ang II but may reflect the collectrin-like action of ACE2. This defect seemed to be compensated by the fact that ACE2-knockout mice shifted their energy consumption towards glucose utilisation via Ang II.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2012
DOI: 10.1161/HYPERTENSIONAHA.112.191767
Abstract: Dietary salt intake is a major determinant of the activation state of renin-angiotensin-aldosterone system. Given the important role of the renin-angiotensin-aldosterone system in plaque accumulation, we investigated its role in the development of atherogenesis associated with sodium intake in apolipoprotein E knockout mice. Six-weeks of a low-salt diet (containing 0.03% sodium) resulted in a 4-fold increase in plaque accumulation in apolipoprotein E knockout mice when compared with mice receiving normal chow (containing 0.30% sodium). This was associated with activation of the renin-angiotensin-aldosterone system, increased vascular expression of adhesion molecules and inflammatory cytokines, and increased adhesion of labeled leukocytes across the whole aorta on a dynamic flow assay. These changes were blocked with the angiotensin-converting enzyme inhibitor perindopril (2 mg/kg per day). A high-salt diet (containing 3% sodium) attenuated vascular inflammation and atherogenesis, associated with suppression of the renin-angiotensin-aldosterone system, although systolic blood pressure levels were modestly increased (5±1 mmHg). Constitutive activation of the renin-angiotensin-aldosterone system in angiotensin-converting enzyme 2 apolipoprotein E knockout mice was also associated with increased atherosclerosis and vascular adhesion, and this was attenuated by a high-salt diet associated with suppression of the renin-angiotensin-aldosterone system. By contrast, a low-salt diet failed to further activate the renin-angiotensin-aldosterone system or to increase atherosclerosis in angiotensin-converting enzyme 2 apolipoprotein E knockout mice. Together, these data validate a relationship between salt-mediated renin-angiotensin-aldosterone system activation and atherogenesis, which may partly explain the inconclusive or paradoxical findings of recent observational studies, despite clear effects on blood pressure.
Publisher: American Diabetes Association
Date: 07-08-2015
DOI: 10.2337/DC15-0925
Abstract: This study explored whether activation of the receptor for advanced glycation end products (RAGE) is implicated in the development of diabetes complications. A case-cohort study was performed in 3,763 participants with prevalent diabetes in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial. The hazard ratios (HRs) for death, major cardiovascular events, and new or worsening nephropathy were derived using Cox regression models, and the ability of sRAGE and AGE levels to reclassify the risk of nephropathy was assessed. After adjustment for a range of possible confounders and other risk factors, sRAGE levels were associated with all-cause mortality (HR 1.11 for a 1-SD increase of log sRAGE [95% CI 1.00–1.22] P = 0.045) and new or worsening nephropathy (HR 1.20 for a 1-SD increase of log sRAGE [95% CI 1.02–1.41] P = 0.032). Circulating AGE levels were also independently associated with new or worsening nephropathy (HR 1.21 for a 1-SD increase [95% CI 1.08–1.36] P = 0.001). Both markers also significantly improved the accuracy with which the 5-year risk of new or worsening nephropathy could be predicted (net reclassification index in continuous model, 0.25 for sRAGE and 0.24 for AGE levels). In adults with type 2 diabetes, increased levels of sRAGE are independently associated with new or worsening kidney disease and mortality over the next 5 years. Higher levels of AGE are also associated with an increased risk of adverse renal outcomes. The AGE/RAGE axis may be of importance in the prevention and management of diabetes complications.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2010
DOI: 10.1161/CIRCRESAHA.110.219279
Abstract: Angiotensin-converting enzyme (ACE)2 opposes the actions of angiotensin (Ang) II by degrading it to Ang 1-7. Given the important role of Ang II/Ang 1-7 in atherogenesis, we investigated the impact of ACE2 deficiency on the development of atherosclerosis. C57Bl6 , Ace2 knockout (KO), apolipoprotein E ( ApoE ) KO and ApoE/Ace2 double KO mice were followed until 30 weeks of age. Plaque accumulation was increased in ApoE/Ace2 double KO mice when compared to ApoE KO mice. This was associated with increased expression of adhesion molecules and inflammatory cytokines, including interleukin-6, monocyte chemoattractant protein-1, and vascular cell adhesion molecule-1, and an early increase in white cell adhesion across the whole aortae on dynamic flow assay. In the absence of a proatherosclerotic ( ApoE KO ) genotype, ACE2 deficiency was also associated with increased expression of these markers, suggesting that these differences were not an epiphenomenon. ACE inhibition prevented increases of these markers and atherogenesis in ApoE/ACE2 double KO mice. Bone marrow macrophages isolated from Ace2 KO mice showed increased proinflammatory responsiveness to lipopolysaccharide and Ang II when compared to macrophages isolated from C57Bl6 mice. Endothelial cells isolated from Ace2 KO mice also showed increased basal activation and elevated inflammatory responsiveness to TNF-α. Similarly, selective inhibition of ACE2 with MLN-4760 also resulted in a proinflammatory phenotype with a physiological response similar to that observed with exogenous Ang II (10 −7 mol/L). Genetic Ace2 deficiency is associated with upregulation of putative mediators of atherogenesis and enhances responsiveness to proinflammatory stimuli. In atherosclerosis-prone ApoE KO mice, these changes potentially contribute to increased plaque accumulation. These findings emphasize the potential utility of ACE2 repletion as a strategy to reduce atherosclerosis.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-07-2018
Abstract: 8‐Oxo‐2′‐deoxyguanosine (8‐oxo‐2′‐ dG ) is a biomarker of oxidative DNA damage that is associated with cardiovascular disease and premature mortality in the general population. Although oxidative stress has a proven role in cardiovascular complications in diabetes mellitus, evidence for a relationship between plasma 8‐oxo‐2′‐ dG and major cardiovascular outcomes in diabetes mellitus is weak. A case‐cohort study was performed in 3766 participants with prevalent diabetes mellitus in the ADVANCE (Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation) trial ( ClinicalTrials.gov number NCT 00145925). The hazard ratios for mortality and major acute cardiovascular events were derived using Cox regression models. During a median of 5 years of follow‐up, 695 (18.4%) participants in this enriched cohort died (including 354 deaths from cardiovascular disease). In iduals with higher levels of 8‐oxo‐2′‐ dG were more likely to die. After adjusting for cardiovascular disease risk factors, the hazard ratio for a 1‐SD increase in plasma 8‐oxo‐2′‐ dG was 1.10 (95% confidence interval, 1.01–1.20 P =0.03). This was driven by an independent association between plasma 8‐oxo‐2′‐ dG and cardiovascular death (hazard ratio, 1.23 95% confidence interval, 1.10–1.37 [ P .001]). By contrast, no association was seen between 8‐oxo‐2′‐ dG and noncardiovascular disease death (of which cancer was the major single cause). 8‐Oxo‐2′‐ dG was also not significantly associated with either nonfatal myocardial infarction or nonfatal stroke. In adults with type 2 diabetes mellitus, increased levels of 8‐oxo‐2′‐ dG are independently associated with all‐cause mortality and cardiovascular mortality in adults with longstanding type 2 diabetes mellitus who participated in the ADVANCE trial, consistent with the role of oxidative damage in the development and progression of cardiovascular decompensation in diabetes mellitus. URL : www.clinicaltrials.gov . Unique identifier: NCT 00145925.
Publisher: American Diabetes Association
Date: 13-09-2018
DOI: 10.2337/DB17-1317
Abstract: Increasing evidence points to the fact that defects in the resolution of inflammatory pathways predisposes in iduals to the development of chronic inflammatory diseases, including diabetic complications such as accelerated atherosclerosis. The resolution of inflammation is dynamically regulated by the production of endogenous modulators of inflammation, including lipoxin A4 (LXA
Publisher: American Diabetes Association
Date: 13-10-2014
DOI: 10.2337/DB13-0932
Abstract: The deleterious effects of high glucose levels and enhanced metabolic flux on the vasculature are thought to be mediated by the generation of toxic metabolites, including reactive dicarbonyls like methylglyoxal (MG). In this article, we demonstrate that increasing plasma MG to levels observed in diabetic mice either using an exogenous source (1% in drinking water) or generated following inhibition, its primary clearance enzyme, glyoxalase-1 (with 50 mg/kg IP bromobenzyl-glutathione cyclopentyl diester every second day), was able to increase vascular adhesion and augment atherogenesis in euglycemic apolipoprotein E knockout mice to a similar magnitude as that observed in hyperglycemic mice with diabetes. The effects of MG appear partly mediated by activation of the receptor for advanced glycation end products (RAGE), as deletion of RAGE was able to reduce inflammation and atherogenesis associated with MG exposure. However, RAGE deletion did not completely prevent inflammation or vascular damage, possibly because the induction of mitochondrial oxidative stress by dicarbonyls also contributes to inflammation and atherogenesis. Such data would suggest that a synergistic combination of RAGE antagonism and antioxidants may offer the greatest utility for the prevention and management of diabetic vascular complications.
Publisher: Springer Science and Business Media LLC
Date: 2011
Publisher: American Diabetes Association
Date: 17-09-2010
DOI: 10.2337/DB10-0552
Abstract: Advanced glycation end products (AGEs) and the renin-angiotensin system (RAS) are both implicated in the development of diabetic retinopathy. How these pathways interact to promote retinal vasculopathy is not fully understood. Glyoxalase-I (GLO-I) is an enzyme critical for the detoxification of AGEs and retinal vascular cell survival. We hypothesized that, in retina, angiotensin II (Ang II) downregulates GLO-I, which leads to an increase in methylglyoxal-AGE formation. The angiotensin type 1 receptor blocker, candesartan, rectifies this imbalance and protects against retinal vasculopathy. Cultured bovine retinal endothelial cells (BREC) and bovine retinal pericytes (BRP) were incubated with Ang II (100 nmol/l) or Ang II+candesartan (1 μmol/l). Transgenic Ren-2 rats that overexpress the RAS were randomized to be nondiabetic, diabetic, or diabetic+candesartan (5 mg/kg/day) and studied over 20 weeks. Comparisons were made with diabetic Sprague-Dawley rats. In BREC and BRP, Ang II induced apoptosis and reduced GLO-I activity and mRNA, with a concomitant increase in nitric oxide (NO•), the latter being a known negative regulator of GLO-I in BRP. In BREC and BRP, candesartan restored GLO-I and reduced NO•. Similar events occurred in vivo, with the elevated RAS of the diabetic Ren-2 rat, but not the diabetic Sprague-Dawley rat, reducing retinal GLO-I. In diabetic Ren-2 rats, candesartan reduced retinal acellular capillaries, inflammation, and inducible nitric oxide synthase and NO•, and restored GLO-I. We have identified a novel mechanism by which candesartan improves diabetic retinopathy through the restoration of GLO-I.
Publisher: Portland Press Ltd.
Date: 12-03-2012
DOI: 10.1042/CS20110403
Abstract: Deficiency of ACE2 (angiotensin-converting enzyme 2), which degrades Ang (angiotensin) II, promotes the development of glomerular lesions. However, the mechanisms explaining why the reduction in ACE2 is associated with the development of glomerular lesions have still to be fully clarified. We hypothesized that ACE2 may regulate the renoprotective actions of ANP (atrial natriuretic peptide). The aim of the present study was to investigate the effect of ACE2 deficiency on the renal production of ANP. We evaluated molecular and structural abnormalities, as well as the expression of ANP in the kidneys of ACE2-deficient mice and C57BL/6 mice. We also exposed renal tubular cells to AngII and Ang-(1–7) in the presence and absence of inhibitors and agonists of RAS (renin–angiotensin system) signalling. ACE2 deficiency resulted in increased oxidative stress, as well as pro-inflammatory and profibrotic changes. This was associated with a down-regulation of the gene and protein expression on the renal production of ANP. Consistent with a role for the ACE2 pathway in modulating ANP, exposing cells to either Ang-(1–7) or ACE2 or the Mas receptor agonist up-regulated ANP gene expression. This work demonstrates that ACE2 regulates renal ANP via the generation of Ang-(1–7). This is a new mechanism whereby ACE2 counterbalances the renal effects of AngII and which explains why targeting ACE2 may be a promising strategy against kidney diseases, including diabetic nephropathy.
Publisher: Elsevier BV
Date: 24-04-2006
Publisher: Portland Press Ltd.
Date: 03-07-2012
DOI: 10.1042/CS20110668
Abstract: Local and systemic AngII (angiotensin II) levels are regulated by ACE2 (angiotensin-converting enzyme 2), which is reduced in diabetic tissues. In the present study, we examine the effect of ACE2 deficiency on the early cardiac and vascular changes associated with experimental diabetes. Streptozotocin diabetes was induced in male C57BL6 mice and Ace2-KO (knockout) mice, and markers of RAS (renin–angiotensin system) activity, cardiac function and injury were assessed after 10 weeks. In a second protocol, diabetes was induced in male ApoE (apolipoprotein E)-KO mice and ApoE/Ace2-double-KO mice, and plaque accumulation and markers of atherogenesis assessed after 20 weeks. The induction of diabetes in wild-type mice led to reduced ACE2 expression and activity in the heart, elevated circulating AngII levels and reduced cardiac Ang-(1–7) [angiotensin-(1–7)] levels. This was associated structurally with thinning of the LV (left ventricular) wall and mild ventricular dilatation, and histologically with increased cardiomyocyte apoptosis on TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) staining and compensatory hypertrophy denoted by an increased cardiomyocyte cross-sectional area. By contrast Ace2-KO mice failed to increase circulating AngII concentration, experienced a paradoxical fall in cardiac AngII levels and no change in Ang-(1–7) following the onset of diabetes. At the same time the major phenotypic differences between Ace2-deficient and Ace2-replete mice with respect to BP (blood pressure) and cardiac hypertrophy were eliminated following the induction of diabetes. Consistent with findings in the heart, the accelerated atherosclerosis that was observed in diabetic ApoE-KO mice was not seen in diabetic ApoE/Ace2-KO mice, which experienced no further increase in plaque accumulation or expression in key adhesion molecules beyond that seen in ApoE/Ace2-KO mice. These results point to the potential role of ACE2 deficiency in regulating the tissue and circulating levels of AngII and their sequelae in the context of diabetes, as well as the preservation or augmentation of ACE2 expression or activity as a potential therapeutic target for the prevention of CVD (cardiovascular disease) in diabetes.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 28-02-2018
Abstract: Background The failure of spontaneous resolution underlies chronic inflammatory conditions, including microvascular complications of diabetes such as diabetic kidney disease. The identification of endogenously generated molecules that promote the physiologic resolution of inflammation suggests that these bioactions may have therapeutic potential in the context of chronic inflammation. Lipoxins (LXs) are lipid mediators that promote the resolution of inflammation. Methods We investigated the potential of LXA 4 and a synthetic LX analog (Benzo-LXA 4 ) as therapeutics in a murine model of diabetic kidney disease, ApoE −/− mice treated with streptozotocin. Results Intraperitoneal injection of LXs attenuated the development of diabetes-induced albuminuria, mesangial expansion, and collagen deposition. Notably, LXs administered 10 weeks after disease onset also attenuated established kidney disease, with evidence of preserved kidney function. Kidney transcriptome profiling defined a diabetic signature (725 genes false discovery rate P ≤0.05). Comparison of this murine gene signature with that of human diabetic kidney disease identified shared renal proinflammatory rofibrotic signals (TNF- α , IL-1 β , NF- κ B). In diabetic mice, we identified 20 and 51 transcripts regulated by LXA 4 and Benzo-LXA 4 , respectively, and pathway analysis identified established (TGF- β 1, PDGF, TNF- α , NF- κ B) and novel (early growth response–1 [EGR-1]) networks activated in diabetes and regulated by LXs. In cultured human renal epithelial cells, treatment with LXs attenuated TNF- α –driven Egr-1 activation, and Egr-1 depletion prevented cellular responses to TGF- β 1 and TNF- α . Conclusions These data demonstrate that LXs can reverse established diabetic complications and support a therapeutic paradigm to promote the resolution of inflammation.
Publisher: American Diabetes Association
Date: 09-05-2017
DOI: 10.2337/DB16-1405
Abstract: The let-7 miRNA family plays a key role in modulating inflammatory responses. Vascular smooth muscle cell (SMC) proliferation and endothelial cell (EC) dysfunction are critical in the pathogenesis of atherosclerosis, including in the setting of diabetes. Here we report that let-7 levels are decreased in diabetic human carotid plaques and in a model of diabetes-associated atherosclerosis, the diabetic ApoE−/− mouse. In vitro platelet-derived growth factor (PDGF)– and tumor necrosis factor-α (TNF-α)–induced vascular SMC and EC activation was associated with reduced let-7 miRNA expression via Lin28b, a negative regulator of let-7 biogenesis. Ectopic overexpression of let-7 in SMCs inhibited inflammatory responses including proliferation, migration, monocyte adhesion, and nuclear factor-κB activation. The therapeutic potential of restoring let-7 levels using a let-7 mimic was tested: in vitro in SMCs using an endogenous anti-inflammatory lipid (lipoxin A4), ex vivo in murine aortas, and in vivo via tail vein injection in a 24-h murine model. Furthermore, we delivered let-7 mimic to human carotid plaque ex vivo and observed significant changes to the secretome in response to let-7 therapy. Restoration of let-7 expression could provide a new target for an anti-inflammatory approach in diabetic vascular disease.
Publisher: Portland Press Ltd.
Date: 04-02-2013
DOI: 10.1042/CS20120352
Abstract: It is recommended that in iduals with diabetes restrict their dietary sodium intake. However, although salt intake is correlated with BP (blood pressure), it also partly determines the activation state of the RAAS (renin–angiotensin–aldosterone system), a key mediator of diabetes-associated atherosclerosis. apoE KO (apolipoprotein E knockout) mice were allocated for the induction of diabetes with streptozotocin or citrate buffer (controls) and further randomized to isocaloric diets containing 0.05%, 0.3% or 3.1% sodium with or without the ACEi [ACE (angiotensin-converting enzyme) inhibitor] perindopril. After 6 weeks of study, plaque accumulation was quantified and markers of atherogenesis were assessed using RT–PCR (reverse transcription–PCR) and ELISA. The association of sodium intake and adverse cardiovascular and mortality outcomes were explored in 2648 adults with Type 1 diabetes without prior CVD (cardiovascular disease) from the FinnDiane study. A 0.05% sodium diet was associated with increased plaque accumulation in diabetic apoE KO mice, associated with activation of the RAAS. By contrast, a diet containing 3.1% sodium suppressed atherogenesis associated with suppression of the RAAS, with an efficacy comparable with ACE inhibition. In adults with Type 1 diabetes, low sodium intake was also associated with an increased risk of all-cause mortality and new-onset cardiovascular events. However, high sodium intake was also associated with adverse outcomes, leading to a J-shaped relationship overall. Although BP lowering is an important goal for the management of diabetes, off-target actions to activate the RAAS may contribute to an observed lack of protection from cardiovascular complications in patients with Type 1 diabetes with low sodium intake.
Publisher: Elsevier BV
Date: 2006
DOI: 10.1016/J.VACCINE.2005.07.097
Abstract: Millions of people live in areas where infectious diseases, such as measles, are endemic and resources are scarce. Heat-stable vaccines that are delivered orally will greatly enhance vaccination programs in these areas. A stumbling block in the development of oral vaccines is the availability of safe and effective mucosal adjuvants, especially for use with subunit vaccines. The experiments presented here examine the ability of CTB/CT, LT(R192G) and crude Quillaja saponin extracts to stimulate MV-specific immune responses in mice, following oral immunisation with plant-made measles virus hemagglutinin (MV-H) protein. LT(R192G) and crude saponin extracts both functioned as potent mucosal adjuvants when ad-mixed with plant-made MV-H protein, and were more effective than CTB/CT. MV-H protein supplemented with saponin extract induced the strongest MV-specific responses, in the greatest number of mice. Crude saponins are routinely used by the food and beverage industry at concentrations greater than those required for adjuvanticity, and as such, they have a better safety profile than bacterial enterotoxins. This study demonstrates their potential as adjuvants for use with oral plant-made vaccines.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.VPH.2015.11.001
Abstract: A critical early event in the pathogenesis of atherosclerosis is vascular inflammation leading to endothelial dysfunction (ED). Reactive oxygen species and inflammation are inextricably linked and declining antioxidant defense is implicated in ED. We have previously shown that Glutathione peroxidase-1 (GPx1) is a crucial antioxidant enzyme in the protection against diabetes-associated atherosclerosis. In this study we aimed to investigate mechanisms by which lack of GPx1 affects pro-inflammatory mediators in primary aortic endothelial cells (PAECs) isolated from GPx1 knockout (GPx1 KO) mice. Herein, we demonstrate that lack of GPx1 prolonged TNF-α induced phosphorylation of P38, ERK and JNK, all of which was reversed upon treatment with the GPx1 mimetic, ebselen. In addition, Akt phosphorylation was reduced in GPx1 KO PAECs, which correlated with decreased nitric oxide (NO) bioavailability as compared to WT PAECs. Furthermore, IκB degradation was prolonged in GPx1 KO PAECS suggesting an augmentation of NF-κB activity. In addition, the expression of vascular cell adhesion molecule (VCAM-1) was significantly increased in GPx1 KO PAECs and aortas. Static and dynamic flow adhesion assays showed significantly increased adhesion of fluorescently labeled leukocytes to GPx1 KO PAECS and aortas respectively, which were significantly reduced by ebselen treatment. Our results suggest that GPx1 plays a critical role in regulating pro-inflammatory pathways, including MAPK and NF-κB, and down-stream mediators such as VCAM-1, in vascular endothelial cells. Lack of GPx1, via effects on p-AKT also affects signaling to eNOS-derived NO. We speculate based on these results that declining antioxidant defenses as seen in cardiovascular diseases, by failing to regulate these pro-inflammatory pathways, facilitates an inflammatory and activated endothelium leading to ED and atherogenesis.
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.EJPHAR.2017.04.026
Abstract: Endoplasmic reticulum (ER) stress contributes to progression of diabetic nephropathy, which promotes end-stage renal failure in diabetic patients. This study was undertaken to investigate the actions of tempol and ramipril, pharmacological agents that target the consequences of NADPH oxidase, on diabetic nephropathy in a rat model of type 1 diabetes, with an emphasis on markers of ER stress. Male Sprague-Dawley rats were injected intravenously with a single bolus of streptozotocin (55mg/kg) to induce type 1 diabetes. An additional age-matched group of rats was administered with citrate vehicle as controls. After 4 weeks of untreated diabetes, rats received tempol (1.5mM/kg/day subcutaneously, n=8), ramipril (1mg/kg/day in drinking water, n=8) or remained untreated for an additional 4 weeks (n=7). After 8 weeks of diabetes in total, kidneys were collected for histological analysis, gene expression and protein abundance. Tempol and ramipril blunted diabetes-induced upregulation of NADPH oxidase isoforms (Nox4, Nox2, p47
Publisher: Wiley
Date: 06-2005
DOI: 10.1111/J.1440-1711.2005.01341.X
Abstract: Although educational programs have had some impact, immunization against HIV will be necessary to control the AIDS pandemic. To be effective, vaccination will need to be accessible and affordable, directed against multiple antigens, and delivered in multiple doses. Plant-based vaccines that are heat-stable and easy to produce and administer are suited to this type of strategy. Pilot studies by a number of groups have demonstrated that plant viral expression systems can produce HIV antigens in quantities that are appropriate for use in vaccines. In addition, these plant-made HIV antigens have been shown to be immunogenic. However, given the need for potent cross-clade humoral and T-cell immunity for protection against HIV, and the uncertainty surrounding the efficacy of protein subunit vaccines, it is most likely that plant-made HIV vaccines will find their niche as booster immunizations in prime-boost vaccination schedules.
No related grants have been discovered for Raelene Pickering.