title: Expression of Interleukin-1β and Matrix Metalloproteinase-8 in Cytolytic and Noncytolytic Enterococcus faecalis-induced Persistent Apical Periodontitis: A Comparative Study in the Rat.
abstract: BACKGROUND
  Cytolytic Enterococcus faecalis possesses a highly toxic and proinflammatory capacity. Cytokines and proteases play important roles in the host inflammatory response. The aim of this study was to compare the local expression of interleukin (IL)-1β and matrix metalloproteinase-8 (MMP-8) between persistent apical periodontitis (AP) infected by cytolytic and noncytolytic E. faecalis.
  
  
  METHODS
  Eighty-four left upper first rat molars were divided into 4 groups: chronic AP group (n = 6), disinfection group (n = 6), cytolytic E. faecalis-infected persistent AP group (n = 36), and noncytolytic E. faecalis-infected persistent AP group (n = 36). Periradicular lesions were established after pulp exposure. After 3 weeks, root canals were prepared, and disinfected. E. faecalis strains ATCC 29212 or ATCC 700802 suspensions were inoculated into root canals 2 weeks later. Six samples were collected at different time points (1, 2, 3, 4, 5, and 6 weeks). The expression levels of IL-1β and MMP-8 were detected by immunohistochemical staining.
  
  
  RESULTS
  IL-1β and MMP-8 expression trends in the cytolytic groups were similar to those of the noncytolytic group although at different time points the expression levels in the cytolytic group were significantly higher than those in the noncytolytic group (P < .01). IL-1β expression enhancement occurred during the early phase of infection, whereas increased MMP-8 expression lasted for a prolonged period.
  
  
  CONCLUSIONS
  Both E. faecalis strains could induce local IL-1β and MMP-8 expression in persistent AP. Compared with noncytolytic E. faecalis, cytolytic E. faecalis may cause more severe local inflammation and tissue destruction in persistent AP.
authors.affiliation: School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, China; Key Laboratory of Stomatology (FMU), Fujian Province University, Fuzhou, Fujian, China.
authors.forename: Bingling
authors.initials: B
authors.lastname: Lu
authors.affiliation: School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, China; Key Laboratory of Stomatology (FMU), Fujian Province University, Fuzhou, Fujian, China.
authors.forename: Jinxiu
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, China; Key Laboratory of Stomatology (FMU), Fujian Province University, Fuzhou, Fujian, China. Electronic address: hxiaoj@163.com.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Huang
authors.affiliation: School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, China; Key Laboratory of Stomatology (FMU), Fujian Province University, Fuzhou, Fujian, China.
authors.forename: Suli
authors.initials: S
authors.lastname: Xiao
authors.affiliation: School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, China; Key Laboratory of Stomatology (FMU), Fujian Province University, Fuzhou, Fujian, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.affiliation: School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, China; Key Laboratory of Stomatology (FMU), Fujian Province University, Fuzhou, Fujian, China; Department of Stomatology, Fujian Medical University Union Hospital, Fuzhou, Fujian, China.
authors.forename: Zhiyu
authors.initials: Z
authors.lastname: Cai
mesh_terms: D000818:Animals; D003786:Dental Pulp Cavity / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D004195:Disease Models, Animal; D013293:Enterococcus faecalis; D016908:Gram-Positive Bacterial Infections / Q000378:metabolism* / Q000473:pathology; D007150:Immunohistochemistry; D053583:Interleukin-1beta / Q000378:metabolism*; D008297:Male; D020784:Matrix Metalloproteinase 8 / Q000378:metabolism*; D008963:Molar / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D010485:Periapical Periodontitis / Q000378:metabolism* / Q000473:pathology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity
chemical_list: C000594089:IL1B protein, rat; D053583:Interleukin-1beta; D020784:Matrix Metalloproteinase 8; C000613587:Mmp8 protein, rat
keywords: Cytolytic Enterococcus faecalis; interleukin-1β; matrix metalloproteinase-8; persistent apical periodontitis; rat