Toll-like receptors (TLR2 and TLR4) recognize polysaccharides of Pseudallescheria boydii cell wall Rodrigo Tinoco Figueiredo a , Vera Carolina B. Bittencourt b , Lívia Cristina L. Lopes c , Guilherme Sassaki d , Eliana Barreto-Bergter c,⇑ a Instituto de Ciências Biomédicas/Pólo de Xerém, Universidade Federal do Rio de Janeiro, Brazil b Instituto Biomédico, UNIRIO, Brazil c Departamento de Microbiologia Geral, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Brazil d Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Brazil article info Article history: Received 20 January 2012 Received in revised form 24 February 2012 Accepted 25 February 2012 Available online 6 March 2012 Keywords: Pseudallescheria boydii Scedosporium apiospermum a-Glucans Rhamnomannans Innate immunity Toll-like receptors abstract Pseudallescheria boydii is an opportunistic fungus widespread in the environment, and has recently emerged as an agent of localized as well as disseminated infections in both immunocompromised and immunocompetent hosts. The host response to fungi is in part dependent on the activation of evolution- ary conserved receptors including Toll-like receptors and phagocytic receptors. This review will discuss the isolation and structural characterization of a-glucans and rhamnomannans from P. boydii cell wall and their roles in the induction of innate immune response. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The opportunistic pathogen Pseudallescheria boydii, present worldwide in plant and soil residues, can infect immunocompetent as well as immunocompromised patients. Scedosporium apiosper- mum has traditionally been thought of as the anamorph of P. boydii (Microascaceae, Ascomycota), but recent molecular studies have demonstrated that they are different species. 1 It is believed that infection with this fungus starts with exposure of the host to con- idia, which differentiate into mycelial forms, allowing tissue colonization. A large number of pseudallescheriosis/scedosporiosis cases have been reported in children with cystic fibrosis, patients with leukemia and organ transplant recipients. Despite the rising fre- quency and high mortality associated with invasive Scedosporium spp./P. boydii infections, the pathogenesis and mechanisms by which these fungi evade host pulmonary defenses and reach other organs are poorly understood. 2 2. Isolation and characterization of P. boydii polysaccharides The fungi are remarkable for the variety of polysaccharide struc- tures that they produce. The most basic components of the fungal cell wall are glucans (3-linked b-D-glucans, 6-linked b-D-glucans) and chitin which form an internal insoluble core of the fungal cell wall. However, glucans having a-(1?3) linkages, a-D-mannans, phosphonomannans, galactans, and heteropolysaccharides containing such diverse components as xylose, arabinose, fucose, glucuronic acid, and rhamnose are commonly encountered. 3–6 In its outer layer, the cell wall contains glycosylated molecules (glycoproteins and glycolipids) involved in important biological events related to virulence and pathogenicity, and represents a sig- nificant source of antigens. 4,5,7 Polysaccharides and peptidopolysaccharides are especially rele- vant for the architecture of the complex P. boydii/Scedosporium spp. cell wall and are specific targets for recognition and specific inter- action with the host immune cells. 6,8,9 These molecules have been isolated from its mycelial form and characterized by our group using spectrometric and spectroscopic methods. 10–12 The methodology described in Figure 1 shows the steps of puri- fication routinely used in our laboratory for peptidopolysaccharide and polysaccharide extraction and purification. Hot aqueous extraction, followed by treatment with Cetavlon in the presence 0008-6215/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.carres.2012.02.028 ⇑ Corresponding author. Tel.: +55 21 25626741; fax: +55 21 25608344. E-mail address: eliana.bergter@micro.ufrj.br (E. Barreto-Bergter). Carbohydrate Research 356 (2012) 260–264 Contents lists available at SciVerse ScienceDirect Carbohydrate Research journal homepage: www.elsevier.com/locate/carres