Reduction in the inflammatory markers CD4, IL-1, IL-6 and TNFα in dogs with keratoconjunctivitis sicca treated topically with mesenchymal stem cells

Abstract

Keratoconjunctivitis sicca (KCS) is of predominantly immune-mediated origin. Dogs are an excellent model for understanding this disease, as the origin of KCS in dogs is like that in humans. The objective of this study was to localize and quantify immunological markers, such as CD4 lymphocytes, interleukin (IL)-1, IL-6 and tumor necrosis factor alpha (TNFα), before and after topical treatment with mesenchymal stem cells (MSCs). Twenty-two dogs positive for KCS were topically treated with 50 μL (1 × 10⁶ MSCs) in the conjunctival sac and were evaluated for 6 months. The levels of the markers CD4, IL-6, IL-1 and TNFα were analyzed in conjunctival biopsy and cytology of the third eyelid gland by immunohistochemistry and immunocytochemistry. The results showed that before treatment, there was marked expression of all the markers (CD4, IL-6, IL-1 and TNFα), and after 6 months, there were significant (p < .05) reductions in the expression levels of all the markers. These results demonstrated that topical MSC treatment promotes a significant decrease in the expression levels of these inflammatory markers and could be used as adjuvant therapy in the treatment of KCS in dogs and humans. In addition, these markers can be excellent tools for diagnosing and analyzing the progression of KCS.

Keywords: Dogs; Dry eye; Immunological markers; Keratoconjunctivitis sicca; Mesenchymal stem cells; Topical.