Induction of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs correlates with outcome of acute experimental pseudomonal keratitis.
This study aimed to investigate expressions and sources of matrix metalloproteinases (MMP)-2 and MMP-9, and of tissue inhibitors of MMP (TIMP)-1 and TIMP-2 in experimental Pseudomonas aeruginosa keratitis in rabbits. Pseudomonal keratitis was induced in New Zealand white rabbits, and macroscopic and microscopic examinations were performed at appropriate time points (3, 9, 12, 18, 24, 72 h). Expressions and sources of MMP-2, 9, and TIMP-1, 2 were determined using immunohistochemistry, gelatin zymography, ELISA, and RT-PCR. A typical corneal ulcer with a ring abscess was observed 12-72 h post-infection (p.i.) with P. aeruginosa. In microscopic examinations, massive inflammatory cell (mostly polymorphonuclear leukocytes, PMNs) infiltration and liquefactive necrosis were characteristic features. MMP-2 was constitutively expressed in keratocytes, and its expression was not apparently enhanced after pseudomonal infection as evidenced by zymography, immunostaining, and RT-PCR. However, MMP-9 and its activated form were induced, and were significantly enhanced 12-24 h p.i. MMP-9 appeared to derive from PMNs rather than from resident corneal cells. TIMP-1 was expressed in PMNs, macrophages, and keratocytes, and its expression was enhanced 72 h p.i. Although TIMP-2 was constitutively expressed as seen by immunostaining and RT-PCR, its concentration was below detection limits during the experiments. We demonstrated that MMP-9 was one of the important factors for corneal tissue destruction, because it was induced and significantly expressed in keratocytes and inflammatory cells after pseudomonal infection. Although TIMP-1 was expressed in later stages of infection, enhancement and activation of MMP-9 were much faster and stronger than those of TIMP-1, thereby facilitating tissue destruction leading to corneal ulceration.
Ikema
Kousuke
K
Department of Ophthalmology and Visual Science, Kumamoto University Graduate School of Medical Sciences, Honjo, Kumamoto, Japan.
Matsumoto
Koki
K
Inomata
Yasuya
Y
Komohara
Yoshihiro
Y
Miyajima
Seiya
S
Takeya
Motohiro
M
Tanihara
Hidenobu
H
D000208:Acute Disease; D000818:Animals; D003315:Cornea / Q000201:enzymology; D005260:Female; D015870:Gene Expression; D007634:Keratitis / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D011552:Pseudomonas Infections / Q000201:enzymology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D011817:Rabbits; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics / Q000378:metabolism; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics / Q000378:metabolism*
D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D019714:Tissue Inhibitor of Metalloproteinases; D019716:Tissue Inhibitor of Metalloproteinase-2; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9