Department of Physiological Sciences

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Browsing Department of Physiological Sciences by Author "Adams, Buin"

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    Parkinson’s disease : a systemic inflammatory disease accompanied by bacterial inflammagens
    (Frontiers Media, 2019-08-27) Adams, Buin; Nunes, J. Massimo; Page, Martin J.; Roberts, Timothy; Carr, Jonathan; Nell, Theo A.; Kell, Douglas B.; Pretorius, Etheresia
    Parkinson’s disease (PD) is a well-known neurodegenerative disease with a strong association established with systemic inflammation. Recently, the role of the gingipain protease group from Porphyromonas gingivalis was implicated in Alzheimer’s disease and here we present evidence, using a fluorescent antibody to detect gingipain R1 (RgpA), of its presence in a PD population. To further elucidate the action of this gingipain, as well as the action of the lipopolysaccharide (LPS) from P. gingivalis, low concentrations of recombinant RgpA and LPS were added to purified fluorescent fibrinogen. We also substantiate previous findings regarding PD by emphasizing the presence of systemic inflammation via multiplex cytokine analysis, and demonstrate hypercoagulation using thromboelastography (TEG), confocal and electron microscopy. Biomarker analysis confirmed significantly increased levels of circulating proinflammatory cytokines. In our PD and control blood analysis, our results show increased hypercoagulation, the presence of amyloid formation in plasma, and profound ultrastructural changes to platelets. Our laboratory analysis of purified fibrinogen with added RgpA, and/or LPS, showed preliminary data with regards to the actions of the protease and the bacterial membrane inflammagen on plasma proteins, to better understand the nature of established PD.
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    Partial inhibition of the ubiquitin– proteasome system ameliorates cardiac dysfunction following ischemia–reperfusion in the presence of high glucose
    (Springer Verlag, 2015) Adams, Buin; Mapanga, Rudo F.; Essop, M. Faadiel; Physiological Sciences
    Abstract Background: Acute hyperglycemia co-presenting with myocardial infarction (in diabetic and non-diabetic individuals) is often associated with a poor prognosis. Although acute hyperglycemia induces oxidative stress that can lead to dysregulation of the ubiquitin–proteasome system (UPS), it is unclear whether increased/decreased UPS is detrimental with ischemia–reperfusion under such conditions. As our earlier data implicated the UPS in cardiac damage, we hypothesized that its inhibition results in cardioprotection with ischemia–reperfusion performed under conditions that simulate acute hyperglycemia. Methods: Ex vivo rat heart perfusions were performed with Krebs–Henseleit buffer containing 33 mM glucose vs. controls (11 mM glucose) for 60 min stabilization, followed by 20 min global ischemia and 60 min reperfusion ± 5 µM lactacystin and 10 µM MG-132, respectively. The UPS inhibitors were added during the first 20 min of the reperfusion phase and various cardiac functional parameters evaluated. In parallel experiments, infarct sizes were assessed following 20 min regional ischemia and 120 min reperfusion ± each of the respective UPS inhibitors (added during reperfusion). Heart tissues were collected and analyzed for markers of oxidative stress, UPS activation, inflammation and autophagy. Results: The proteasome inhibitor doses and treatment duration here employed resulted in partial UPS inhibition during the reperfusion phase. Both lactacystin and MG-132 administration resulted in cardioprotection in our experimental system, with MG-132 showing a greater effect. The proteasome inhibitors also enhanced cardiac superoxide dismutase protein levels (SOD1, SOD2), attenuated pro-inflammatory effects and caused an upregulation of autophagic markers. Conclusions: This study established that partial proteasome inhibition elicits cardioprotection in hearts exposed to ischemia–reperfusion with acute simulated hyperglycemia. These data reveal that protease inhibition triggered three major protective effects, i.e. (a) enhancing myocardial anti-oxidant defenses, (b) attenuating inflammation, and (c) increasing the autophagic response. Thus the UPS emerges as a unique therapeutic target for the treatment of ischemic heart disease under such conditions. Keywords: Ubiquitin–proteasome system, Ischemia–reperfusion, Cardiac dysfunction, Hyperglycemia, Inflammation, Oxidative stress, Autophagy
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    Proteasome Inhibitors : a novel therapy that blunt hyperglycemia-induced cardiac contractile dysfunction
    (Stellenbosch : Stellenbosch University, 2015-04) Adams, Buin; Essop, M. Faadiel; Mapanga, Rudo Fiona; Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences.
    ENGLISH ABSTRACT: Diabetes is considered a major threat to human health in both developed and developing nations. Cardiovascular disease which is common in diabetic patients has increased the overall disease affliction. Moreover, stress-induced hyperglycemia has led to increased mortality and morbidity in patients with an acute myocardial infarction (MI), whether the patient has diabetes or not. In addition, acute MI might stem from stress-induced hyperglycemia capability to increase inflammation and oxidative stress resulting in a worse functional cardiac outcome. Hyperglycemia-induced oxidative stress can similarly result in the formation of miss folded or damaged proteins that may be eliminated by the ubiquitin-proteasome system (UPS). Futhermore, hyperglycemia-induced oxidative stress can also result in dysregulation of the UPS that removes these misfolded proteins. Additionally, an increasing body of evidence implicates UPS dysfunction in cardiac diseases and hyperglycemia which has been associated with increased inflammation and blunted cardiac function in response to ischemia-reperfusion. Literature however is blurred whether a reduction or a rise in the UPS is damaging with hyperglycemia and in response to ischemia-reperfusion. In light of this, we hypothesized that UPS inhibitors such as Z-Leu-Leu-Leu-al (MG-132) and lactacystin, protects the rat heart against ischemia-reperfusion under hyperglycemic perfusion conditions. Isolated rat hearts were perfused ex vivo with Krebs-Henseleit buffer containing 33 mM glucose vs. controls (11 mM glucose) for 60 min, followed by 20 min global ischemia and 60 minutes reperfusion ± PI treatment (MG-132 and lactacystin), anti-inflammatory (Ibuprofen) and anti-oxidant (NAC). Infarct size was determined using Evans Blue dye and 1% 2,3,5-triphenyl tetrazolium chloride (TTC) staining with 20 minutes regional ischemia and 2 hours reperfusion ± PI’s treatments. Tissues were collected at the end of the global ischemia experiments and analyzed for UPS activity, oxidative stress, apoptosis and inflammation. Our data expressed a reduced cardiac contractile function in response to ischemia and reperfusion under hyperglycemic conditions as well as an increase in UPS activity. PI treatment resulted in cardio-protection for ex vivo rat heart model exposed to ischemia and reperfusion under hyperglycemic conditions as well as ibuprofen and NAC. In parallel lactacystin treatment significantly decreased myocardial oxidative stress, apoptosis, and inflammation which provided cardio-protection in response to ischemia and reperfusion under hyperglycemic conditions This study shows that acute hyperglycemia elicits myocardial oxidative stress, apoptosis and inflammation that in time results in an increase in contractile dysfunction following ischemia and reperfusion. However, we found that PI treatment with both MG-132 and lactacystin blunted high glucose-induced damaging effects which resulted in a robust cardio-protection in response to ischemia and reperfusion under hyperglycemic conditions, by reducing oxidative stress, decreasing apoptosis and limiting inflammation. A parallel outcome was observed at baseline although the underlying mechanisms driving this process still need to be clarified. Our findings indicate that the UPS may be a unique therapeutic target to treat ischemic heart disease in diabetic patients, and non-diabetic individuals that present with stress-induced hyperglycemia. In summary, this thesis established that PIs act as a novel cardio-protective intervention to treat acute hyperglycemia with associated cardiovascular complications.