The increasing prevalence of antibiotic resistant bacteria portends an impending post-antibiotic age, characterized by diminishing efficacy of common antibiotics and routine application of multifaceted, complementary therapeutic... more
The increasing prevalence of antibiotic resistant bacteria portends an impending post-antibiotic age, characterized by diminishing efficacy of common antibiotics and routine application of multifaceted, complementary therapeutic approaches to treat bacterial infections, particularly multidrug-resistant organisms. The first line of defense for most bacterial pathogens consists of a physical and immunological barrier known as the capsule, commonly composed of a viscous layer of carbohydrates that are covalently bound to the cell wall in Gram-positive bacteria or often to lipids of the outer membrane in many Gram-negative bacteria. Bacterial capsular polysaccharides are a diverse class of high molecular weight polysaccharides contributing to virulence of many human pathogens in the gut, respiratory tree, urinary tract, and other host tissues, by hiding cell-surface components that might otherwise elicit host immune response. This review highlights capsular polysaccharides that are structurally identical or similar to polysaccharides found in mammalian tissues, including polysialic acid and glycosaminoglycan capsules hyaluronan, heparosan, and chondroitin. Such non-immunogenic coatings render pathogens insensitive to certain immune responses, effectively increasing residence time in host tissues and enabling pathologically relevant population densities to be reached. Biosynthetic pathways and capsular involvement in immune system evasion are described providing a basis for potential therapies aimed at supplementing or replacing antibiotic treatment.This article is protected by copyright. All rights reserved.
Some dietary carbohydrates are quite healthy when consumed as part of a balanced diet, while others can be toxic, especially if overconsumed. They can be simple sugars, oligo- or polysachharides. Simple sugars like fructose, glucose and... more
Some dietary carbohydrates are quite healthy when consumed as part of a balanced diet, while others can be toxic, especially if overconsumed. They can be simple sugars, oligo- or polysachharides. Simple sugars like fructose, glucose and sucrose have a high glycemic index. Polysaccharides are compounds consisting of a large number of monosaccharides linked glycosidically and have a low glycemic index. Water-soluble polysaccharides and polysaccharide-protein complexes can enhance and/or activate immune responses in macrophages and the complement system. For example, six kinds of α-galactosylceramides (α-GalCers) from the marine sponge Agelas mauritianus have potent anti-tumor activities. Their discovery led to the development of a synthetic α -GalCer for treating autoimmune diseases and cancer. It activates invariant natural killer T-cells (iNKTs) by binding to CD1 receptors on antigen-presenting cells. There are also esters made from reactions between fatty acids and glucose, called fatty acid glycosides. Several of these have been isolated from the popular fruit called noni (Morinda citrifolia). They have been shown to inhibit inflammation and activate cannabinoid 2 (CB2), but inhibit cannabinoid 1 (CB1) receptors, while decreasing the production of IL-4 and increasing the production of IFN-γ. Many other fatty acid glycosides have been tentatively identified in ten out of ten other fruits that were analyzed. So, fatty acid glycosides could be an important, but underappreciated part of the nutritive value and health effects of many fruits.
The increasing prevalence of antibiotic resistant bacteria portends an impending post-antibiotic age, characterized by diminishing efficacy of common antibiotics and routine application of multifaceted, complementary therapeutic... more
The increasing prevalence of antibiotic resistant bacteria portends an impending post-antibiotic age, characterized by diminishing efficacy of common antibiotics and routine application of multifaceted, complementary therapeutic approaches to treat bacterial infections, particularly multidrug-resistant organisms. The first line of defense for most bacterial pathogens consists of a physical and immunological barrier known as the capsule, commonly composed of a viscous layer of carbohydrates that are covalently bound to the cell wall in Gram-positive bacteria or often to lipids of the outer membrane in many Gram-negative bacteria. Bacterial capsular polysaccharides are a diverse class of high molecular weight polysaccharides contributing to virulence of many human pathogens in the gut, respiratory tree, urinary tract, and other host tissues, by hiding cell-surface components that might otherwise elicit host immune response. This review highlights capsular polysaccharides that are stru...
