The Effects of Dietary Fibres on Inflammatory Processes under Hyperglycaemic Conditions

Asif, Mohammed Subhan (2020) The Effects of Dietary Fibres on Inflammatory Processes under Hyperglycaemic Conditions. Masters by Research thesis (MSc), Manchester Metropolitan University.

Preview

Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (2MB) | Preview

Abstract

Diabetes Mellitus (DM) has been recognised as one of the most common chronic condition worldwide with a rise in number of young adults and children developing the condition. The common symptoms seen in DM are chronic inflammation and infections (e.g. diabetic foot ulcers (DFUs)). This is thought to be due to defects in the immune response. An alternative or possibly complementary strategy to treat infections is to develop novel therapies that stimulate the body’s own natural innate immune system. Dietary fibres such as MGN3 may help to increase the clearance of bacteria in DFUs whilst at the same time reducing inflammation. This study investigated the effect of MGN3 on the phagocytosis of MRSA by U937 macrophages and CD14 expression in U937 monocytes/macrophages under hyperglycaemic conditions. An in vitro host-pathogen assay (n=12) was carried out to test the effectiveness of MGN3 (2mg/ml) on bacterial (MRSA) clearance by U937 macrophages at different levels of glucose (11, 15, 20 and 30mM). CD14 protein expression in U937 monocytes/macrophages was visualised by confocal microscopy and determined by flow cytometry following exposure to glucose (11 or 30mM) with/without MGN3 (2mg/ml). The study showed MGN3 increases bacterial clearance with increasing periods (2 to 5 hours) of host-interaction. The phagocytosis of MRSA became increasingly impaired with rising glucose levels but this detrimental effect on U937 macrophages could be significantly (P < 0.05) reversed in the presence of MGN3. MGN3-treated macrophages increased overall bacterial clearance under hyperglycaemic conditions, even at high (30mM) glucose levels. Lipopolysaccharide (LPS) significantly stimulated CD14 protein expression in U937 monocytes/macrophages cultured in high (30mM) glucose. Moreover, CD14 analysis indicated there was competition taking place between LPS and MGN3, with a significant (P < 0.05) decrease in mean relative fluorescence (relative CD14 protein levels) after combined treatment of U937 monocytes/macrophages with both LPS and MGN3 compared to just LPS treatment alone. 13 In conclusion, this study indicated that MGN3 can reverse some detrimental effects of hyperglycaemia on monocyte/macrophage function, by inhibiting glucose-mediated elevation of CD14 and reversing glucose-mediated inhibition of MRSA clearance. These findings can have a major impact for diabetic patients since MGN3 may be a potential therapeutic strategy to dampen inflammation, stimulate healing and promote bacterial clearance in diabetic patients with infected wounds.