Effectiveness of 16S ribosomal DNA real-time PCR and sequencing for diagnosing bacterial keratitis.

PURPOSE: To evaluate the efficacy of real-time PCR for 16S ribosomal DNA (16S r-DNA) and sequencing for diagnosing microbial keratitis. METHODS: We studied 272 eyes of 272 patients with keratitis. Eyes with keratitis were classified as "definite" (N = 118), "likely" (N = 71), or "non-bacterial" (N = 83) to have bacterial keratitis. The diagnostic efficacy of real-time PCR and conventional testing was determined by receiver operating characteristic analysis. The copy numbers of bacterial DNA and clinical characteristics were retrospectively analyzed for association with concordant culture results in the "definite" cases. RESULTS: The level of bacterial DNA was significantly associated with the diagnostic probability of the three diagnostic categories. The level of bacterial DNA had comparable diagnostic efficacy with the area under the curve (AUC) at 0.67, by culture at 0.65, and by smear testing at 0.73. The efficacy was significantly improved by combining the DNA level with the conventional culture testing with an AUC of 0.81. Analysis of the "definite" cases showed culture positivity in 51.8% (58 eyes), and of these, 41 eyes (70.7%) were higher than the cutoff PCR values and 40 eyes were identified by 16S r-DNA sequencing. In the culture-negative eyes, the level of bacterial DNA was significantly lower (P = 0.0008). Eyes with higher bacterial DNA levels had significantly concordant outcomes with sequencing and culture results (P = 0.006). Previous antibiotic treatments decreased the bacterial DNA amount by 0.09-fold, and it was a significant factor for discordance (P = 0.006). CONCLUSION: Quantification of the bacterial DNA level and conventional testing improves the diagnostic efficacy of infectious bacterial keratitis.

Pharmacologic inhibition of IκB kinase activates immediate hypersensitivity reactions in mice.

Pharmacologic inhibitors of IκB kinase (IKK), especially IKK-ß, have been developed to treat inflammatory diseases. However, their interactions with components of the NF-κB pathways are not fully known in allergic diseases. To examine whether IKK is involved in immediate hypersensitivity reactions and to determine whether counterregulatory mechanisms in the NF-κB activation system were active, we examined the role played by IKK components on mast cell degranulation using a murine ocular immediate hypersensitivity reaction model. Pharmacologic inhibition of IKK in mice caused paradoxical aggravation of the mast cell-mediated immediate hypersensitivity reaction and up-regulation in the expression of inflammatory cytokines. Downstream analyses showed that B-cell deficiency or treatment by IL-1 receptor antagonist corrected the aberrant activation of tissue-resident mast cells, which would indicate contribution by activated B cells. Analyses of co-cultures of tissue-resident mast cells showed the contribution of activated B cells to activation of mast cells and secretion of inflammatory cytokines. Aberrant activation of the NF-κB promoter in isolated B cells was induced exclusively by IKK-ß inhibition and was negated by ablating IKK-α. Aggravated mast cell degranulation by pharmacologic IKK inhibition in the murine immediate hypersensitivity reaction was corrected by B-cell-targeted inhibition of IKK-α. Thus, IKK-ß limits B-cell-mediated mast cell activation and inflammatory cytokine induction in immediate hypersensitivity by counterbalancing the activity of IKK-α.

[Efficacy of Gram-Fungiflora Y double staining in diagnosing infectious keratitis].

PURPOSE: To evaluate the efficacy of Gram-Fungiflora Y double staining for corneal scraping samples collected by impression in diagnosing infectious keratitis. SUBJECTS AND METHODS: Two hundred and thirteen eyes of 192 patients suspected of having infectious keratitis were retrospectively studied for the sensitivity and specificity of Gram-Fungiflora Y based on final diagnosis. RESULTS: Of 165 infectious keratitis eyes, 107 had bacterial keratitis, 54 had fungal keratitis, and 15 had Acanthamoeba keratitis. Of these, 147 eyes were positive for one or other of the pathogens by the double staining method (overall sensitivity/specificity was 89.1% (95% confidence interval 83.1%-93.2%)/ 79.1% (64.6%-89.0%)). Sensitivity/specificity of the double staining for each of the pathogens was 88.8% 82.1% for bacterial keratitis, 81.4%/98.1% for fungal keratitis and 80.0%/97.0% for Acanthamoeba keratitis. CONCLUSION: The double staining method for impression specimens was effective in diagnosing infectious keratitis with high sensitivity, and was especially useful for the diagnosis of fungal or Acanthamoeba keratitis.

Indoleamine 2,3-dioxygenase 1 in corneal endothelial cells limits herpes simplex virus type 1-induced acquired immune response.

BACKGROUND: Corneal endothelial cells are known to be targets of herpes simplex virus type 1 (HSV-1) infection; however, the pathogenesis of HSV infections of the endothelial cells has not been definitively determined. The purpose of this study was to examine an unrecognised strategy of corneal endothelial cells to protect themselves from HSV-1 infection. METHODS: Immortalised human corneal endothelial cells (HCEn) were infected with HSV-1. Based on the global transcriptional profile, the expression of indoleamine 2,3-dioxygenase 1 (IDO1) was determined using real-time PCR and western blots. To examine whether IDO1 has any antiviral role, we tested whether viral replication was affected by blocking the activity of IDO1. The immune modulatory role of IDO1 was analysed to determine whether IDO1 might contribute to modulating the recall responses of HSV-1-sensitised CD4(+) T cells. RESULTS: IDO1 was strongly expressed in HCEn cells after HSV-1 infection. IDO1 blockade did not significantly restrict viral transcription or replication, arguing against a previously recognised antiviral role for IDO1. When HCEn cells were examined for antigen-presenting function, HSV-1-primed HCEn cells stimulated the proliferation of allogeneic CD4(+) T cells and interleukin 10 (IL-10) secretion. When the recall response to HSV-1 was measured by the mixed lymphocyte reaction, the HCEn-stimulated CD4(+) T cells modulated and limited the recall response. When IDO1 was silenced in HCEn cells, the HCEn-mediated immune modulatory activity and regulatory T-cell activation were reduced. Overexpression of IDO1 promoted immune modulatory activity, which was partly conveyed by IL-10. CONCLUSIONS: IDO1 induced by HSV-1 infection limits and dampens excessive acquired immune responses in corneal endothelial cells.