title: Chitosan oligosaccharides prevented retinal ischemia and reperfusion injury via reduced oxidative stress and inflammation in rats.
abstract: The purpose of the present study was to investigate the protective effect and mechanism of chitosan oligonucleotides (COS) on retinal ischemia and reperfusion (I/R) injury. Rats pretreated with PBS, low-dose COS (5 mg/kg), or high-dose COS (10 mg/kg) were subjected to retinal ischemia by increasing their intraocular pressure to 130 mm Hg for 60 min. The protective effect of COS was evaluated by determining the electroretinograms (ERGs), morphology of the retina, and survival of retinal ganglion cells (RGCs). The oxidative damage was determined by imuunohistochemistry and ELISA, respectively. The expressions of inflammatory mediators (TNF-α, IL-1β, MCP-1, iNOS, ICAM-1) and apoptotic-related proteins (p53, Bax, Bcl-2) were quantified by PCR and Western blots. The detection of NF-κB p65 in the retina was performed by immunofluorescence. The protein levels of IκB and phosphorylated mitogen-activated protein kinases [MAPK; viz. extracellular signal-regulated protein kinases (ERK), c-Jun N-terminal kinases (JNK) and p38] and the NF-κB/DNA binding ability were assessed by Western blot analysis and EMSA. We found that pretreatment with COS, especially a high dosage, effectively ameliorated the I/R-induced reduction of the b-wave ratio in ERGs and the retinal thickness and the survival of RGCs at 24 h. COS decreased the expression of inflammatory mediators, p53 and Bax, increasing Bcl-2 expression and thereby reducing retinal oxidative damage and the number of apoptotic cells. More importantly, COS attenuated IκB degradation and p65 presence in the retina, thus decreasing NF-κB/DNA binding activity after I/R. In addition, COS decreased the phosphorylation levels of JNK and ERK but increased the phosphorylation level of p38. Pretreatment with p38 inhibitor (SB203580) abolished the protective effect of COS on retinal oxidative damage, as indicated by increased retinal 8-OHdG stains, and significantly increased the expression of inflammatory mediators (TNF-α, MCP-1, iNOS, ICAM-1) in I/R-injured rats. In conclusion, COS prevented retinal I/R injury through its inhibition of oxidative stress and inflammation. These effects were achieved by blocking the activation of NF-κB, JNK, and ERK but promoting the activation of p38 activation.
authors.affiliation: Department of Ophthalmology, Taipei City Hospital Zhongxiao Branch, Taipei, Taiwan; Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: I-Mo
authors.initials: IM
authors.lastname: Fang
authors.affiliation: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chung-May
authors.initials: CM
authors.lastname: Yang
authors.affiliation: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. Electronic address: chyangoph@ntu.edu.tw.
authors.forename: Chang-Hao
authors.initials: CH
authors.lastname: Yang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002614:Chelating Agents / Q000008:administration & dosage / Q000494:pharmacology*; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D048271:Chitosan / Q000008:administration & dosage / Q000494:pharmacology*; D004596:Electroretinography; D004797:Enzyme-Linked Immunosorbent Assay; D020672:I-kappa B Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007249:Inflammation / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D012164:Retinal Diseases / Q000378:metabolism / Q000517:prevention & control*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C491766:Ccl2 protein, rat; D002614:Chelating Agents; D018932:Chemokine CCL2; D020672:I-kappa B Proteins; D053583:Interleukin-1beta; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D048271:Chitosan; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D048051:p38 Mitogen-Activated Protein Kinases
keywords: Chitosan oligosaccharides; Ischemia-reperfusion injury; Mitogen-activated protein kinases (MAPK); NF-κB; Oxidative damage