Tear cytokines as potential markers of inflammation in feline conjunctivitis

Introduction: Conjunctivitis is a prevalent feline ocular surface disorder, often accompanied by inflammation. Inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), play a crucial role in the pathogenesis of conjunctival inflammation. This study aimed to evaluate the levels of TNF-α and IL-6 in the tears of cats with conjunctivitis and compare them with healthy controls, thereby enhancing our understanding of the inflammatory processes in feline conjunctivitis.

Methods and materials: Tear samples were collected from cats of various breeds diagnosed with conjunctivitis (n = 15) and healthy control cats (n = 5) using Schirmer strips. The levels of TNF-α and IL-6 were measured using the enzyme-linked immunosorbent assay (ELISA) method. Protein concentration were measured using Bradford assay and data were expressed as pg/mg protein of tear sample.

Results: Our results revealed a statistically significant increase in the levels of both TNF-α and IL-6 in cats with conjunctivitis compared to the control group (p < .0001). Positive correlation were observed between tear IL-6 (p < .001, r = 0.902) and TNF-α (p < .001, r = 0.919) with clinical grades of conjunctivitis.

Conclusion: The results demonstrated a significant elevation in the levels of TNF-α and IL-6 in the tears of cats with conjunctivitis, suggesting that these cytokines are involved in the inflammatory response of feline conjunctivitis. These findings could pave the way for new diagnostic and therapeutic approaches, focusing on cytokine modulation, to manage feline conjunctivitis more effectively.