Matrix metalloproteinases, tissue inhibitor of matrix metalloproteinase-1, and laminin-5 gamma2 chain immunolocalization in gingival tissue of endotoxin-induced periodontitis in rats: effects of low-dose doxycycline and alendronate.
BACKGROUND
Matrix metalloproteinases (MMPs) play important roles in tissue destruction mechanisms of periodontitis. MMP-8 and -13 are the major collagenases that act in extracellular matrix degradation in periodontal tissues. MMP-14 is a membrane-type MMP, and laminin (Ln)-5 is a basal membrane component. The aim of the present study was to evaluate the effects of doxycycline and alendronate on gingival tissue expression of MMP-8, -13, and -14; tissue inhibitors of MMP (TIMP)-1; and Ln-5 gamma2 chain in experimental periodontitis induced by Escherichia coli endotoxin (LPS) in rats.


METHODS
Experimental periodontitis was induced by repeated injection of LPS. Forty-four adult male Sprague-Dawley rats were divided into five study groups: saline control, LPS, LPS + doxycycline, LPS + alendronate, and LPS + doxycycline + alendronate. Doxycycline and alendronate were given as a single agent or as combination therapy during the 7 days of the experimental study period. On day 7, the rats were sacrificed, and the gingival tissues were analyzed immunohistochemically for expression of MMP-8, -13, and -14, Ln-5 gamma2 chain, and TIMP-1. Alveolar bone loss was evaluated morphometrically under a stereomicroscope. Data were tested statistically by Kruskal-Wallis and Mann-Whitney tests and Spearman correlation analysis.


RESULTS
Alveolar bone loss was significantly higher in the LPS, doxycycline, alendronate, and combination groups than in the saline control group (all P <0.01). MMP-8 expression was significantly higher in the LPS group than in the saline control group (P = 0.001). Individual administration of doxycycline or alendronate significantly decreased the expression of MMP-8 compared to LPS (P = 0.01). Combined drug administration reduced MMP-14 significantly compared to doxycycline (P = 0.004). No significant differences in Ln-5 gamma2 chain expression were found between the study groups (P >0.05). MMP-14 significantly correlated with the Ln-5 gamma2 chain in the LPS + alendronate group (P = 0.04) and with the amount of alveolar bone loss in the LPS + doxycycline + alendronate group (P = 0.03).


CONCLUSIONS
Our findings suggest that alendronate and/or doxycycline may inhibit MMP-8 expression significantly; particularly, their combined administration may provide beneficial effects in periodontal treatment. Moreover, individual administration of alendronate and doxycycline results in significant increases in TIMP-1 expression in gingiva. However, these effects of combined low-dose doxycycline and alendronate on MMPs and TIMP should be verified by clinical human trials before these agents are used in dental practice.
Buduneli
Eralp
E
Department of Periodontology, School of Dentistry, Ege University, Izmir, Turkey. eralp.buduneli@ege.edu.tr
Vardar-Sengül
Saynur
S
Buduneli
Nurcan
N
Atilla
Gül
G
Wahlgren
Jaana
J
Sorsa
Timo
T
D019386:Alendronate / Q000627:therapeutic use; D016301:Alveolar Bone Loss / Q000201:enzymology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000096:biosynthesis*; D004318:Doxycycline / Q000627:therapeutic use; D004338:Drug Combinations; D004926:Escherichia coli; D005881:Gingiva / Q000201:enzymology; D007124:Immunoenzyme Techniques; D008070:Lipopolysaccharides; D008297:Male; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000032:analysis / Q000096:biosynthesis*; D010518:Periodontitis / Q000188:drug therapy* / Q000201:enzymology*; D011480:Protease Inhibitors / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D018709:Statistics, Nonparametric; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000032:analysis / Q000096:biosynthesis*; D000097794:Kalinin
D019386:Alendronate; D000900:Anti-Bacterial Agents; D050071:Bone Density Conservation Agents; D015815:Cell Adhesion Molecules; D004318:Doxycycline; D004338:Drug Combinations; D008070:Lipopolysaccharides; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases; D011480:Protease Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D000097794:Kalinin