title: Toll-like receptors involved in the pathogenesis of experimental Candida albicans keratitis.
abstract: Purpose. To investigate the expression and function of toll-like receptors (TLRs) during experimental keratomycosis. Methods. Scarified corneas of BALB/c mice were topically inoculated with Candida albicans and compared with control corneas by a murine gene microarray and immunostaining. Real-time reverse transcription polymerase chain reaction (RT-PCR) determined relative TLR gene expression in murine and human donor corneas. The scarified corneas of TLR2(-/-) mice, TLR4(-/-) mice, and C57BL/6J control mice were also inoculated with C. albicans, to determine relative severity, fungal load, and cytokine transcript levels. Results. TLR1, -2, -4, -6, and -13 were significantly upregulated (5- to 10-fold; P < 0.01) by microarray, and TLR1, -2, -4, and -13 were significantly increased (4- to 11-fold; P < 0.05) by real-time RT-PCR in BALB/c murine corneas. Similarly, TLR2, -6, and -13 were significantly upregulated (5- to 16-fold; P < or = 0.001) by real-time RT-PCR in C57BL/6J murine corneas the day after inoculation, and TLR2 and -13 remained significantly (P < 0.05) increased after 1 week. TLR2 transcript was also upregulated twofold (P = 0.04) in C. albicans-inoculated explanted human corneas. Although murine keratitis severity scores were similar, significantly more fungi were recovered from TLR2(-/-) mouse corneas (P = 0.04) than from TLR4(-/-) mouse corneas (P = 0.9). Tumor necrosis factor-alpha, interleukin 23, chemokine C-C ligands 3 and 4, and dectin-1 were significantly (P < 0.05) downregulated in C. albicans-infected corneas of TLR2(-/-) mice. Conclusions. TLR2 signals proinflammatory cytokines that control fungal growth during C. albicans keratitis. TLR13 may have an additional role in the innate immune response of murine corneal candidiasis.
authors.affiliation: Sid W. Richardson Ocular Microbiology Laboratory, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Xiaoyong
authors.initials: X
authors.lastname: Yuan
authors.forename: Kirk R
authors.initials: KR
authors.lastname: Wilhelmus
mesh_terms: D000818:Animals; D002176:Candida albicans / Q000302:isolation & purification; D002177:Candidiasis / Q000382:microbiology*; D003320:Corneal Ulcer / Q000378:metabolism*; D016207:Cytokines / Q000235:genetics; D015821:Eye Infections, Fungal / Q000382:microbiology*; D019084:Fluorescent Antibody Technique, Indirect; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D045726:Metalloproteases / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051193:Toll-Like Receptors / Q000235:genetics* / Q000378:metabolism
chemical_list: D016207:Cytokines; D051193:Toll-Like Receptors; D045726:Metalloproteases