A Novel Exopolysaccharide from the Biofilm of Thermus aquaticus YT-1 Induces the Immune Response through Toll-like Receptor 2

Abstract

Bacterial polysaccharides are known to induce the immune response in macrophages. Here we isolated a novel extracellular polysaccharide from the biofilm of Thermus aquaticus YT-1 and evaluated its structure and immunomodulatory effects. The size of this polysaccharide, TA-1, was deduced by size-exclusion chromatography as 500 kDa. GC-MS, high performance anionexchange chromatography with pulsed amperometric detection, electrospray ionization-MS/MS, and NMR revealed the novel structure of TA-1. The polysaccharide is composed of tetrasaccharide-repeating units of galactofuranose, galactopyranose, and N-acetylgalactosamine (1:1:2) and lacked acidic sugars. TA-1 stimulated macrophage cells to produce the cytokines TNF-␣ and IL-6. Screening of Toll-like receptors and antibodyblocking experiments indicated that the natural receptor of TA-1 in its immunoactivity is TLR2. Recognition of TA-1 by TLR2 was confirmed by TA-1 induction of IL-6 production in peritoneal macrophages from wild-type mice but not from TLR2 ؊/؊ mice. TA-1, as a TLR2 agonist, could possibly be used as an adjuvant and could enhance cytokine release, which increases the immune response. Furthermore, TA-1 induced cytokine release is dependent on MyD88/TIRAP.The excessive use of antibiotics poses tremendous selection pressure on microorganisms to develop drug resistance, which eventually leads to incurable diseases. Recent alternatives to antibiotics are immunomodulators. Instead of combating pathological microbes directly, the immunomodulators act to enhance the host defense responses without the development of drug resistance.Natural products extracted from microorganisms, mushrooms, algae, lichens, and higher plants were known to induce positive immunological effects and have been frequently used in the ancient practice of Chinese medicine (1). The mechanisms of action of these substances are often unknown, but polysaccharides in these extracts have been found to be the primary factor for macrophage stimulation through induction of the immune system of Toll-like receptors (2, 3). These biopolymers often show advantages over the polysaccharides that are currently in use, especially in combating microbial infections (4). Consequently, modulation of the innate immune system significantly improves the host ability to respond to different pathogens and diseases.The innate immune system is the first line of host defense. It protects the host from a variety of pathogens based on a limited repertoire of germ line-encoded receptors called pattern recognition receptors (PRRs). 4 PRRs include members of the Toll-like receptor (TLR) family and nucleotide binding oligomerization domain-like receptors and retinoic acidinducible gene-I-like receptors, which recognize pathogenassociated molecules, such as microbial components, and then trigger the release of inflammatory cytokine and type I interferons for host defense (5-8). These PRRs are localized in distinct cellular compartments. TLR1, TLR2, TLR4, TLR5, and TLR6 are expressed on the cell surface, whereas TLR3, ...

A unique gene cluster for the utilization of the mucosal and human milk‐associated glycans galacto‐N‐biose and lacto‐N‐biose in Lactobacillus casei

“…Therefore, further analysis will be needed to determine the mechanisms by which GalNAc and GlcNAc are phosphorylated. GalNAc is a constituent of the cell wall, lipopolysaccharides and exopolysaccharides in bacteria (Tallon et al, 2003;Bernatchez et al, 2005;Freymond et al, 2006;Lin et al, 2011), and it connects glycan chains with the protein backbone of mucins in humans (Jensen et al, 2010). Even though GalNAc is an available source of carbon and nitrogen for bacteria, its catabolic pathway has only been characterized in Escherichia coli and Shewanella sp.…”

Exopolysaccharides: Sweet success with probiotic therapeutics

“…However in vitro studies using EPSs derived from other bacteria, even those which are not present in mammalian GITs, may offer insights into the receptors of and signaling pathways modulated by EPSs. For example, Lin et al [55] published an in vitro study using TA-1, an EPS from the Gram-negative, rod-shaped thermophile Thermus aquaticus and showed that incubation of high quantities of TA-1 with murine RAW 264.7 macrophages or peritoneal macrophages resulted in NF- activation and production of pro-inflammatory TNF- and IL-6 [55] . This inflammatory response was dependent on TLR2, suggesting that TA-1, which is comprised of tetrasaccharide-repeating units of galactofuranose, galactopyranose, and Nacetylgalactosamine (1:1:2) acts as a TLR2 ligand [55] , and mediates its response through NF- Although T. aquaticus is not a mammalian commensal, it functions via TLR2, similar to PSA from B. fragilis and EPS from B. subtilis.…”

Phosphoproteomic Analysis Reveals the Effects of PilF Phosphorylation on Type IV Pilus and Biofilm Formation in Thermus thermophilus HB27

“…One is biofilm formation, which confers protection against environmental stresses such as high temperature and the presence of antibiotics (8). In previous studies, a novel exopolysaccharide, TA-1, was isolated from a T. aquaticus YT-1 biofilm, and both its primary structure and its immunological activity were determined (13). In addition, we showed that the overexpression of uridine diphosphate (UDP)-galactose-4Ј-epimerase (GalE), which catalyzes the reversible interconversion of UDP-galactose and UDP-glucose, in T. thermophilus HB27 increases biofilm production because of the enzyme's involvement in an important step of exopolysaccharide (EPS) 1 biosynthesis (14).…”