Study of ocular manifestations and humoral immune response in eyes of dogs with leishmaniasis

Background: Ocular manifestations in dogs with leishmaniasis are frequent and complications in affected tissues can lead to blindness. Immune processes play a very important role in the pathogenesis of ocular inflammation. Therefore, the immunology of ocular manifestations in dogs with leishmaniasis remains complex and poorly understood. Objectives: Estimation and characterisation of ocular and periocular manifestations in dogs naturally infected with Leishmania infantum and investigation of the production site of specific anti-Leishmania infantum IgG. Methods: The present investigation used 53 confirmed dogs infected with Leishmania infantum, presenting ocular and periocular lesions, and 10 control non-infected dogs. Complete macroscopic ophthalmic examination of eyelids and globes was performed. Both total and anti-Leishmania infantum IgG antibodies were studied in sera and aqueous humour (AH) of all dogs by ELISA technique. A Goldmann-Witmer coefficient (C value) was calculated. Results: The main ophthalmological findings were keratoconjunctivitis (71.7%; 38/53), hyperplasia of conjunctival lymphoid follicles (54.7%; 29/53), blepharitis (50.9%; 27/53) and uveitis (20.7%; 11/53). Ocular production of anti-Leishmania infantum IgG was detected in 73.6% (39/53) of infected dogs. There was no correlation between the antibody levels in AH and sera of the same dog. The mean anti-Leishmania infantum IgG in AH was higher in uveitis, followed by lesions affecting only the adnexa (p < 0.0001). The highest mean C values were observed for uveitis, conjunctivitis and keratitis. Conclusions: Our findings suggest that production of anti-Leishmania IgG in dogs infected with Leishmania infantum with ocular manifestations begin in situ and follows by a transfer of antibodies from the bloodstream to the AH.

Automated summary

This study investigated the ocular manifestations in dogs naturally infected with Leishmania infantum and the production of specific anti-Leishmania infantum IgG. The main findings were keratoconjunctivitis, hyperplasia of conjunctival lymphoid follicles, blepharitis, and uveitis. Ocular production of anti-Leishmania infantum IgG was detected in 73.6% of infected dogs. The levels of antibodies varied depending on the type of ocular lesion.