Pathogenesis of onchocercal keratitis (River blindness)

Area of Science:

• Ophthalmology
• Immunology
• Parasitology

Background:

• Onchocerciasis, caused by Onchocerca volvulus, affects 17 million people and is a major cause of blindness.
• Ocular pathology in onchocerciasis can affect any part of the eye, with anterior segment disease including keratitis.
• Onchocercal keratitis results from an inflammatory response in the anterior eye, often leading to corneal opacification and neovascularization.

Purpose of the Study:

• To review current knowledge on human onchocercal keratitis.
• To summarize immunological mechanisms underlying interstitial keratitis using experimental models.
• To explore potential avenues for immunologically based interventions.

Main Methods:

• Review of existing literature on human onchocercal keratitis.
• Analysis of studies using experimental models to investigate interstitial keratitis.
• Examination of the role of host inflammatory response, T helper cells, cytokines, and chemokines in pathogenesis.

Main Results:

• The pathogenesis of onchocercal keratitis is linked to the host inflammatory response to degenerating parasites.
• Soluble O. volvulus antigens induce corneal opacification and neovascularization, mimicking clinical symptoms.
• Experimental models highlight the critical role of sensitized T helper cells and cytokines in regulating corneal inflammation.

Conclusions:

• Onchocercal keratitis is driven by the host's immune response to parasite antigens.
• Cytokines and chemokines play significant roles in inflammatory cell recruitment to the cornea.
• Further research into the molecular basis of onchocercal keratitis could inform novel immunotherapeutic strategies.