Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious Keratitis
The cornea serves as a barrier to protect the eye against external insults including microbial pathogens and antigens. Bacterial infection of the cornea often results in corneal melting and scarring that can lead to severe visual impairment. Not only live bacteria but also their components such as l...
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doaj-4088018784e54367a0e4f383516a96032020-11-25T00:49:50ZengMDPI AGInternational Journal of Molecular Sciences1422-00672017-08-01189183110.3390/ijms18091831ijms18091831Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious KeratitisKen Fukuda0Waka Ishida1Atsuki Fukushima2Teruo Nishida3Department of Ophthalmology, Kochi Medical School, Nankoku City 783-8505, JapanDepartment of Ophthalmology, Kochi Medical School, Nankoku City 783-8505, JapanDepartment of Ophthalmology, Kochi Medical School, Nankoku City 783-8505, JapanDepartment of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi 755-8505, JapanThe cornea serves as a barrier to protect the eye against external insults including microbial pathogens and antigens. Bacterial infection of the cornea often results in corneal melting and scarring that can lead to severe visual impairment. Not only live bacteria but also their components such as lipopolysaccharide (LPS) of Gram-negative bacteria contribute to the development of inflammation and subsequent corneal damage in infectious keratitis. We describe the important role played by corneal stromal fibroblasts (activated keratocytes) as sentinel cells, immune modulators, and effector cells in infectious keratitis. Corneal fibroblasts sense bacterial infection through Toll-like receptor (TLR)–mediated detection of a complex of LPS with soluble cluster of differentiation 14 (CD14) and LPS binding protein present in tear fluid. The cells then initiate innate immune responses including the expression of chemokines and adhesion molecules that promote the recruitment of inflammatory cells necessary for elimination of the infecting bacteria. Infiltrated neutrophils are activated by corneal stromal collagen and release mediators that stimulate the production of pro–matrix metalloproteinases by corneal fibroblasts. Elastase produced by Pseudomonas aeruginosa (P. aeruginosa) activates these released metalloproteinases, resulting in the degradation of stromal collagen. The modulation of corneal fibroblast activation and of the interaction of these cells with inflammatory cells and bacteria is thus important to minimize corneal scarring during treatment of infectious keratitis. Pharmacological agents that are able to restrain such activities of corneal fibroblasts without allowing bacterial growth represent a potential novel treatment option for prevention of excessive scarring and tissue destruction in the cornea.https://www.mdpi.com/1422-0067/18/9/1831fibroblastkeratocytecornealipopolysaccharidebacteriachemokineadhesion moleculecollagentear fluid |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Ken Fukuda Waka Ishida Atsuki Fukushima Teruo Nishida |
spellingShingle |
Ken Fukuda Waka Ishida Atsuki Fukushima Teruo Nishida Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious Keratitis International Journal of Molecular Sciences fibroblast keratocyte cornea lipopolysaccharide bacteria chemokine adhesion molecule collagen tear fluid |
author_facet |
Ken Fukuda Waka Ishida Atsuki Fukushima Teruo Nishida |
author_sort |
Ken Fukuda |
title |
Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious Keratitis |
title_short |
Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious Keratitis |
title_full |
Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious Keratitis |
title_fullStr |
Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious Keratitis |
title_full_unstemmed |
Corneal Fibroblasts as Sentinel Cells and Local Immune Modulators in Infectious Keratitis |
title_sort |
corneal fibroblasts as sentinel cells and local immune modulators in infectious keratitis |
publisher |
MDPI AG |
series |
International Journal of Molecular Sciences |
issn |
1422-0067 |
publishDate |
2017-08-01 |
description |
The cornea serves as a barrier to protect the eye against external insults including microbial pathogens and antigens. Bacterial infection of the cornea often results in corneal melting and scarring that can lead to severe visual impairment. Not only live bacteria but also their components such as lipopolysaccharide (LPS) of Gram-negative bacteria contribute to the development of inflammation and subsequent corneal damage in infectious keratitis. We describe the important role played by corneal stromal fibroblasts (activated keratocytes) as sentinel cells, immune modulators, and effector cells in infectious keratitis. Corneal fibroblasts sense bacterial infection through Toll-like receptor (TLR)–mediated detection of a complex of LPS with soluble cluster of differentiation 14 (CD14) and LPS binding protein present in tear fluid. The cells then initiate innate immune responses including the expression of chemokines and adhesion molecules that promote the recruitment of inflammatory cells necessary for elimination of the infecting bacteria. Infiltrated neutrophils are activated by corneal stromal collagen and release mediators that stimulate the production of pro–matrix metalloproteinases by corneal fibroblasts. Elastase produced by Pseudomonas aeruginosa (P. aeruginosa) activates these released metalloproteinases, resulting in the degradation of stromal collagen. The modulation of corneal fibroblast activation and of the interaction of these cells with inflammatory cells and bacteria is thus important to minimize corneal scarring during treatment of infectious keratitis. Pharmacological agents that are able to restrain such activities of corneal fibroblasts without allowing bacterial growth represent a potential novel treatment option for prevention of excessive scarring and tissue destruction in the cornea. |
topic |
fibroblast keratocyte cornea lipopolysaccharide bacteria chemokine adhesion molecule collagen tear fluid |
url |
https://www.mdpi.com/1422-0067/18/9/1831 |
work_keys_str_mv |
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1725250912892485632 |