Table 1.
Summary of the two cohorts from which tear samples were collected.
Fig 1.
Mean integrated pixel density of each cytokine relative to negative control spots in each of eight pooled tear samples.
Clinical status of each pool is indicated on the x axis. Cytokines are clustered by euclidean distance. As arrays were semi-quantitative and performed using pooled samples without biological replicates, no formal hypothesis-testing was carried out.
Fig 2.
Protein concentration for participants in different infection and clinical categories in the Tanzanian Cohort study.
Comparisons with a p value < 0.1 for a mixed-effects logistic regression adjusting for age, sex and participant is shown. Comparisons with a p value < 0.05 are highlighted in bold. Each point represents a sample, coloured by cytokine/antimicrobial protein. Box plots indicate median and interquartile range (IQR), with whiskers extending to the most extreme values within 1.5 x IQR. Tear samples collected at both at 72 and 84 months post-recruitment were included.
Table 2.
Tear samples selected from the Gambian cohort study to investigate the kinetics of infection and scarring.
Fig 3.
Protein concentration for participants in different infection and clinical categories in the Gambian Cohort study, including samples from all time points.
Samples are categorised by whether they came from a) healthy controls, who did not develop any infection or disease over the course of the study or from b) participants at a time point at which they had infection/disease/scarring. P values for a mixed-effects logistic regression adjusting for age, sex and participant are indicated, with those < 0.05 highlighted in bold. Each point represents a sample, coloured by cytokine/antimicrobial protein. Box plots indicate median and IQR with whiskers extending to the most extreme values within 1.5 x IQR.
Fig 4.
Change in normalised protein concentration relative to the infected time point for each participant in the Gambian Cohort study.
Time points are separated by two weeks, and samples were limited to the first infection episode only. P values for a paired Wilcoxon signed-rank test comparing the normalised concentration at each time point relative to time of infection are shown, with p values < 0.05 highlighted in bold. Each point represents a sample, coloured by cytokine/antimicrobial protein. Grey lines show the log2(fold change) in concentration over time for each participant, while the black thick line shows the median log2(fold change).
Fig 5.
Normalised protein concentrations prior to infection, compared with healthy controls.
Protein concentrations normalised to total protein, in healthy control participants (individuals with no PCR positive infections or clinical signs throughout the entire study) compared with four weeks and two weeks prior to first detectable infection in individuals who did develop infection. Only the first episode of infection was analysed. P values for a logistic regression model comparing each timepoint with healthy controls, adjusting for age and sex, is shown. P values < 0.05 are highlighted in bold. Each point represents a sample, coloured by cytokine/antimicrobial protein. Box plots indicate median and IQR, with whiskers extending to the most extreme values within 1.5 x IQR.
Fig 6.
Concentration of proteins normalised to total tear protein at the first timepoint of each infection episode.
Healthy controls are shown for comparison. P values for a paired Wilcoxon signed-rank test comparing episodes 2 and 3 with episode 1 are shown, with p values < 0.05 highlighted in bold. Each point represents a sample, coloured by cytokine/antimicrobial protein. Box plots indicate median and IQR, with whiskers extending to the most extreme values within 1.5 x IQR.
Fig 7.
A model for trachoma pathogenesis based on study findings.
a. Infection results in activation of pattern recognition receptors and therefore an increase in CXC chemokines, resulting in recruitment of T cells, Neutrophils and Macrophages b. CD8+ T cells and neutrophils can mediate tissue damage, resulting in trachomatous scarring c. Inflammatory cytokines suppress lacrimal gland secretion, decreasing lysozyme tear concentration d. Immune cells recruited to the conjunctiva and/or immune memory result in enhanced inflammation in successive infection episodes e. At later stages of scarring lysozyme is raised, possibly due to secretion by recruited macrophages.