Correlations between Right Eye Conjunctival Gene Transcript Levels Reveal Linked Cytokine Responses and the Relationship to Control of Pathogen Load

<div><p>Abundance of <i>IFN-γ, IL-10,</i> and <i>IDO</i> relative to <i>HPRT</i> expression after log₁₀ transformation. Correlation coefficients were calculated by Spearman's rank correlation and trend lines fitted by locally weighted polynomial regression.</p> <p>(A) Strong positive correlation between the conjunctival expression of <i>IDO</i> and <i>IFN-γ</i> in individuals with infection (<i>n =</i> 69) or without infection (<i>n =</i> 238).</p> <p>(B) Strong positive correlation between the expression of <i>IFN-γ</i> and counter inflammatory <i>IL-10</i> in infected (<i>n =</i> 69) and uninfected individuals (<i>n =</i> 238).</p> <p>(C) Relative abundance of <i>IDO</i> and the load of pathogen (chlamydial 16S rRNA) in the conjunctiva. A weak positive correlation was found between pathogen load and <i>IDO</i> expression in clinically normal individuals (<i>n =</i> 42) (mean pathogen loads are lower in this group; <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0030266#pmed-0030266-t002" target="_blank">Table 2</a>). In contrast, the relationship between <i>IDO</i> expression and pathogen load is weakly negative or absent in individuals with co-incident clinical signs of trachoma (<i>n</i> = 29) (pathogen loads are highest in this group; <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0030266#pmed-0030266-t002" target="_blank">Table 2</a>).</p> <p>CT, <i>C. trachomatis.</i></p></div

Age Modulation on Right Eye Conjunctival mRNA Expression: Analysis of Covariance

<p>Individuals were categorised using a combination of the presence of clinical signs of active trachoma (TF/TI) and the detection of chlamydial 16S rRNA. Regression models were fitted for the expression of each human mRNA assayed and age (years) within each category. The regression lines for individuals in each category are shown for each of the mRNAs, <i>IDO</i> (top left), <i>IFN-γ</i> (bottom left), <i>IL-10</i> (top right), and <i>FOXP3</i> (bottom right). Green line: clinically normal, uninfected individuals; blue line: clinically normal, infected individuals; red line: clinically diseased, infected individuals; and orange line: clinically diseased, uninfected individuals.</p

Conjunctival Cytokine mRNA Expression in the Right Conjunctivae of Study Participants

<p>RNA was extracted from conjunctival swabs and reverse transcribed, and specific cytokine transcripts were amplified by PCR. Cytokine mRNA expression was normalized against the housekeeping gene <i>HPRT</i>. The response of each individual is shown with the median value (red bar) and the 25th and 75th percentiles (blue bars) for each group. Data were tested for significance by ANOVA and adjusted for age. Individuals are categorised using a combination of the presence of clinical signs of active trachoma (TF/TI) and the detection of chlamydial 16S rRNA. <i>IFN-γ</i> (A) and <i>IDO</i> (B) mRNAs were increased in infected individuals, and they were further increased in those in whom clinical signs coincided with infection compared to clinically normal, uninfected individuals. <i>IL-10</i> mRNA (C) was increased only in those who had clinical infections, while <i>FOXP3</i> mRNA (D) was increased in both clinically infected and clinically diseased, uninfected individuals.</p