title: Toll like receptor 4 (TLR4) mediates the stimulating activities of chitosan oligosaccharide on macrophages.
abstract: The in vivo and in vitro immunostimulating properties of chitosan oligosaccharide (COS) prepared by enzymatic hydrolysis of chitosan and the mechanisms mediating the effects were investigated. Our data showed that the highly active chitosanase isolated could hydrolyze chitosan to the polymerization degree of 3-8. The resulting COS was an efficient immunostimulator. COS markedly enhanced the proliferation and neutral red phagocytosis by RAW 264.7 macrophages. The production of nitric oxide (NO) and tumor necrosis factor alpha (TNF-α) by macrophages was significantly increased after incubation with COS. Oral administration of COS in mice could increase spleen index and serum immunoglobin G (IgG) contents. COS was labeled with FITC to study the pinocytosis by macrophages. Results showed that FITC-COS was phagocyted by macrophages and anti-murine TLR4 antibody completely blocked FITC-COS pinocytosis. RT-PCR indicated that COS treatment of macrophages significantly increased TLR4 and inducible nitric oxide synthase (iNOS) mRNA levels. When cells were pretreated with anti-murine TLR4 antibody, the effect of COS on TLR4 and iNOS mRNA induction was decreased. COS-induced NO secretion by macrophages was also markedly decreased by anti-murine TLR4 antibody pretreatment. In conclusion, the present study revealed that COS possesses potent immune-stimulating properties by activating TLR4 on macrophages.
authors.affiliation: Biochemistry Laboratory, College of Marine Life Sciences, Ocean University of China, Yushan Road 5, Qingdao 266003, PR China. Electronic address: zhangxiaobei88@163.com.
authors.forename: Pei
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Biochemistry Laboratory, College of Marine Life Sciences, Ocean University of China, Yushan Road 5, Qingdao 266003, PR China. Electronic address: liuweizhi@ouc.edu.cn.
authors.forename: Weizhi
authors.initials: W
authors.lastname: Liu
authors.affiliation: Biochemistry Laboratory, College of Marine Life Sciences, Ocean University of China, Yushan Road 5, Qingdao 266003, PR China. Electronic address: yanfeipeng@ouc.edu.cn.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Biochemistry Laboratory, College of Marine Life Sciences, Ocean University of China, Yushan Road 5, Qingdao 266003, PR China. Electronic address: baoqinh@ouc.edu.cn.
authors.forename: Baoqin
authors.initials: B
authors.lastname: Han
authors.affiliation: Biochemistry Laboratory, College of Marine Life Sciences, Ocean University of China, Yushan Road 5, Qingdao 266003, PR China. Electronic address: yany@ouc.edu.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000276:immunology; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D048271:Chitosan / Q000031:analogs & derivatives / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006868:Hydrolysis; D007114:Immunization; D007074:Immunoglobulin G / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D051379:Mice; D008813:Mice, Inbred ICR; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D009844:Oligosaccharides / Q000737:chemistry / Q000494:pharmacology*; D010587:Phagocytosis / Q000187:drug effects; D010873:Pinocytosis / Q000187:drug effects; D058105:Polymerization; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D019138:Antibodies, Blocking; D007074:Immunoglobulin G; D009844:Oligosaccharides; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D048271:Chitosan; D052247:Nitric Oxide Synthase Type II
keywords: Chitosan oligosaccharide; Immune-stimulating; Macrophages; Toll like receptor 4