title: Increased expression of Interleukin-13 and connective tissue growth factor, and their potential roles during foreign body encapsulation of subcutaneous implants.
abstract: The purpose of this study was to better understand whether interleukin-13 (IL-13) and connective tissue growth factor (CTGF) are highly expressed during foreign body encapsulation of subcutaneous devices. Mock biosensors were implanted into rats for three lengths of time (7-, 21- and 48-55 days) to address different stages of the foreign body response. Using quantitative real-time PCR and immunofluorescence, the expression of IL13, CTGF, collagen 1, decorin and fibronectin were measured in this tissue. IL-13, a product of Th2 cells, was highly expressed at all time points, with greatest expression at day 21. The IL-13 expression was paralleled by increased presence of T-cells at all time points. CTGF was also found to be more highly expressed in foreign body tissue than in controls. Collagen and decorin were highly expressed at the middle and later stages. Given the increased expression of IL-13 and CTGF in foreign body tissue, and their roles in other fibrotic disorders, these cytokines may well contribute to the formation of the foreign body capsule. Since the peak gene expression of IL-13 occurred later than the previously-reported TGFbeta expression peak, IL-13 is probably not the major stimulus to TGFbeta expression during foreign body encapsulation and may contribute to fibrosis independently.
authors.affiliation: Legacy Health System, 1225 NE 2nd Avenue, Portland, OR 97232, USA. kward@legacyglucosesensor.org
authors.forename: W Kenneth
authors.initials: WK
authors.lastname: Ward
authors.forename: Allen G
authors.initials: AG
authors.lastname: Li
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Siddiqui
authors.forename: Isaac F
authors.initials: IF
authors.lastname: Federiuk
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Wang
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D015374:Biosensing Techniques; D003094:Collagen / Q000378:metabolism; D055513:Connective Tissue Growth Factor; D058575:Decorin; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005549:Foreign-Body Reaction; D005786:Gene Expression Regulation; D017874:Immediate-Early Proteins / Q000096:biosynthesis*; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D018793:Interleukin-13 / Q000096:biosynthesis* / Q000378:metabolism; D019736:Prostheses and Implants; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018418:Th2 Cells / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D001672:Biocompatible Materials; C526316:CCN2 protein, rat; C546880:Dcn protein, rat; D058575:Decorin; D016326:Extracellular Matrix Proteins; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D018793:Interleukin-13; D011509:Proteoglycans; D016212:Transforming Growth Factor beta; D055513:Connective Tissue Growth Factor; D003094:Collagen