Research on the world’s most common cause of blindness, trachoma, has led to the identification of small molecules that are linked to severity of the disease, it has been announced.
Tamsyn Derrick and colleagues at the London School of Hygiene & Tropical Medicine, UK, investigated why only a proportion of infected patients experience inflammation and scarring.
They examined samples from infected children with and without inflammation. This process highlighted two microRNAs – miR-155 and miR-184 – that have a direct relationship with the degree of inflammation.
Details were published recently in BMC Infectious Diseases. Ms Derrick said: "We found that miR-155 is increased and miR-184 is decreased as the severity of clinical inflammation goes up. We think this pattern of microRNA expression reflects the activity of immune cells in the conjunctiva.
"MiR-155 in particular has wide-ranging and profound effects on immune cell development and function, while miR-184 is the only microRNA that is present in significantly different levels between people with inflammatory trachoma that has persisted post-infection, versus uninfected healthy controls."
Previous research has shown that two other microRNAs (miR-147b and miR-1285) are increased in adults with scarring and inflammatory trachoma.
Co-author, Dr Martin Holland, added: "Our results suggest that the presence of inflammatory cells is required to drive pathological responses in the conjunctiva. They also present in miR-184 a new target with significant therapeutic potential."
The prolonged low-levels of miR-184 in post-infection inflammatory trachoma could reflect prolonged wound healing and abnormal cell signalling, and may also contribute to thinning of the conjunctiva which could predispose people to repeat infection, he added.
Derrick, T. et al. Inverse relationship between microRNA-155 and -184 expression with increasing conjunctival inflammation during ocular Chlamydia trachomatis infection. BMC Infectious Diseases 3 February 2016 doi: 10.1186/s12879-016-1367-8
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