Expression of CRAMP via PGN-TLR-2 and of  -defensin-3 via CpG-ODN-TLR-9 in corneal fibroblasts

Abstract

Aims: To search for the induction of the expression of antimicrobial peptides in corneal fibroblasts treated with bacterial components. Methods: RT-PCR was performed to search for mRNAs expression of antimicrobial peptides and toll-like receptors (TLRs) in murine primary cultures of corneal fibroblast (PCCF) treated with lipopolysaccharide (LPS) from Escherichia coli, peptidoglycan from Staphylococcus aureus, and cytosine-phosphorousguanine oligonucleotide (CpG-ODN). Cellular activation was blocked with anti-TRL antibodies. Results: LPS did not induce expression of antimicrobial peptide in corneal fibroblasts. Cathelin related antimicrobial peptide (CRAMP) and a-defensin 3 were overexpressed in a time and dose dependent manner in corneal fibroblasts treated with peptidoglycan and with CpG-ODN, respectively. CRAMP expression was blocked when PCCF were treated with anti-TLR-2 antibodies. a-Defensin 3 was not expressed in NIH murine corneal fibroblasts (which do not express the TLR-9 molecule) treated with CpG-ODN. Conclusion: Results suggest that corneal fibroblasts, which are the second cellular barrier of the cornea, can play an important part in the innate immunity of the eye via TLR stimulation.

CXCL1/KC and CXCL5/LIX are selectively produced by corneal fibroblasts and mediate neutrophil infiltration to the corneal stroma in LPS keratitis

“…Whether resident keratocytes express TLR4 or respond to LPS is uncertain; however, keratocytes differentiate into fibroblasts under inflammatory conditions and can produce a number of cytokines in response to LPS [23][24][25][26][27][28]. Similarly, the MK/T-1 stromal fibroblast line used in the current study responds to highly purified LPS.…”

“…CXCL1/KC, CXCL2/MIP-2, and CXCL5/LIX are differentially expressed by corneal fibroblasts, macrophages, and neutrophils During wound-healing or inflammation, keratocytes are activated, differentiate into fibroblasts, and produce a number of cytokines in response to LPS [23][24][25][26][27][28]. In addition, resident macrophages and infiltrating neutrophils are a potential source of cytokines [29 -32].…”

NF-κB-Dependent Induction of Cathelicidin-Related Antimicrobial Peptide in Murine Mast Cells by Lipopolysaccharide

“…The proteins are translated as procathelicidin molecules comprised of a conserved cathelin domain and a C-terminal domain representing the more variable antibacterial peptide itself, and proteolytic processing is required for release of the active peptide. Cathelicidins have been identified in many cell types, including neutrophils, epithelial cells, keratinocytes, corneal fibroblasts, lymphocytes, monocytes and mast cells [14, 15]. The cathelicidins are cationic, amphipathic peptides and through interaction with bacterial membranes can disrupt and kill sensitive strains [11, 12].…”

The impact of Toll-like receptors on bacterial virulence strategies

“…Both of these activities increase the antimicrobial capacity of the phagosome, although some bacteria have actually co-opted these signals to regulate their virulence programs (discussed in greater detail below). Detection of microbial ligands by TLRs can also induce the expression and secretion of antimicrobial peptides (AMPs), such as beta-defensins, and cathelicidin, further supporting the role of TLR-mediated detection in cell-intrinsic antimicrobial activity (15–17). …”