The Effects of Dietary Fibres on Inflammatory Processes under Hyperglycaemic Conditions

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

Biobran (MGN-3) concurrently reverses lipopolysaccharide-induced elevation of CD14 and impairment of macrophage-mediated bacterial clearance in a model of diabetic wound biofilms

Hyperglycaemia found in type 2 diabetic patients can lead to several complications including a type of chronic wound called a diabetic foot ulcer (DFU). Diabetic foot ulcers are associated with elevated inflammatory markers but defective immune responses that can lead to microbial infection, often characterised by biofilm formation. Cereal-derived fibres called arabinoxylans have shown increased immune function in both the adaptive and innate immune responses in animal models. A cereal-derived fibre called Biobran (MGN-3) has been shown to stimulate immune cells including macrophages, T cell and dendritic cells suggesting it may be of therapeutic benefit to fight infections. This study investigated whether MGN-3 can stimulate the clearance of wound-associated bacterial biofilms under hyperglycaemic conditions and modulate levels of the pattern recognition receptor CD14 on the cell surface of M1 macrophages. Host-pathogen biofilm investigations (n=12) were performed to assess the effect of MGN-3 (0.5, 1.0 and 2.0 mg/ml for 24 hours) on the phagocytosis of both Gram-positive Methicillin resistant Staphylococcus aureus (MRSA) and Gram-negative Pseudomonas aeruginosa (PA01) biofilms by U937-derived M1 macrophages cultured in glucose-supplemented (11, 15, 20, 30mM) medium. CD14 on the cell surface of M1 macrophages was assessed by confocal microscopy and flow cytometry (n=4). Findings showed glucose-supplementation significantly (P<0.05) inhibits the M1 macrophage-mediated phagocytosis of both MRSA and PA01 biofilms in a dose-dependent manner. Moreover, hyperglycaemia significantly (P<0.05) enhanced lipopolysaccharide (LPS)-induced M1 macrophage CD14 surface levels. Treatment of M1 macrophages with MGN-3 (0.5, 1.0 and 2.0 mg/ml) for 24 hours significantly (P<0.05; n=12) promoted the clearance of both MRSA and PA01 biofilms in a dose-dependent manner. Moreover, this is the first study to demonstrate MGN-3 reverses the detrimental effects of hyperglycaemia in a dose-dependent manner, significantly (P<0.05) increasing M1-mediated clearance of bacterial biofilms and reducing LPS-induced CD14 levels (n=4). CD14 levels significantly (P < 0.05; n=4) decreased after dual treatment with LPS and MGN-3 compared to just LPS treatment alone, suggesting competition was taking place between MGN-3 and LPS at the CD14 receptor on M1 macrophages. The findings of this project suggest MGN-3 may be of potential therapeutic benefit for the treatment of DFU patients with wound biofilm infections

Biobran (MGN-3) acts through toll-like receptor-4 (TRL-4) and reverses the detrimental effects of hyperglycaemia on phagocytosis

Diabetes Mellitus (DM) is a chronic condition caused by hyperglycaemia. DM has been linked to defective immune responses and increased infection risk. Innovative medicines that boost the body's innate immune system is an alternate or complementary approach to using antibiotics for treating infections. Dietary fibres such as Biobran (MGN-3) have been shown to modulate inflammation and immune responses. The aim of this study was to determine the effect of MGN-3 on the phagocytosis of Methicillin resistant Staphylococcus aureus (MRSA) by U937 macrophages under hyperglycaemic circumstances. Host-pathogen investigations (n=12) were performed under in vitro culturing conditions of increasing glucose concentration (11, 15, 20, 30mM) using U937-derived macrophages and Methicillin resistant Staphylococcus aureus (MRSA). The study showed that MGN-3 treated macrophages were significantly more effective (P<0.05) at clearing MRSA than untreated macrophages and that phagocytosis increased with increasing MGN-3 concentration (0.5, 1.0 and 2.0 mg/ml) in a dose-dependent manner. Moreover, MGN-3 significantly reversed (P<0.05) the detrimental dose-responsive effects of elevated glucose on macrophage-mediated phagocytosis. It is known that bacterial lipopolysaccharide (LPS) binds to the pattern recognition receptor CD14 on the cell surface of macrophages and activates toll-like receptor-4 (TLR-4) to stimulate phagocytosis, suggesting structural similarity between LPS and MGN-3 may account for the enhanced bacterial clearance of non-endotoxin producing MRSA observed following MGN-3 supplementation. Blocking TLR-4 significantly (P<0.05) reversed the beneficial effects of MGN-3 on MRSA clearance, confirming MGN-3 acts at least in part through activation of TLR-4 in U937-derived macrophages. In conclusion, MGN-3 appears to counteract the negative effects of hyperglycaemia on macrophage function by activating the TLR-4 pathway and reversing the inhibition of MRSA clearance caused by elevated glucose levels. These results may have significant impact for diabetic patients if MGN-3 can be developed as a therapy to promote bacterial clearance in diabetic patients with infected wounds

Charge Density Waves in Electron-Doped Molybdenum Disulfide

We present the discovery of a charge density wave (CDW) ground state in heavily electron-doped molybdenum disulfide (MoS$_2$). This is the first observation of a CDW in any d$^2$ (column 6) transition metal dichalcogenide (TMD). The band structure of MoS$_2$ is distinct from the d$^0$ and d$^1$ TMDs in which CDWs have been previously observed, facilitating new insight into CDW formation. We demonstrate a metal–insulator transition at 85 K, a 25 meV gap at the Fermi level, and two distinct CDW modulations, (2√3 × 2√3) R30° and 2 × 2, attributable to Fermi surface nesting (FSN) and electron–phonon coupling (EPC), respectively. This simultaneous exhibition of FSN and EPC CDW modulations is unique among observations of CDW ground states, and we discuss this in the context of band folding. Our observations provide a route toward the resolution of controversies surrounding the origin of CDW modulations in TMDs