Secretion of proinflammatory cytokines by human conjunctival epithelial cells

TLDR

The study examined cytokine production by human conjunctival epithelial cells after stimulation and highlighted their potential as therapeutic targets. Primary human conjunctival epithelial cells were cultured, characterized, and stimulated with LPS, IL‑1β, calcium ionophore A23187, or PMA, with cytokine secretion measured over time. Stimulation induced dose‑ and time‑dependent secretion of TNF‑α, IL‑6, IL‑8, and GM‑CSF, while IL‑1ra was present basally and increased intracellularly; other cytokines were undetectable, indicating these cells may contribute to ocular inflammation.

Abstract

The production of cytokines by human conjunctival epithelial cells following stimulation was investigated. Primary cultures of human conjunctival epithelial cells were characterized by morphology and keratin expression. Cultured epithelial cells were treated with varying concentrations of lipopolysaccharide, interleukin (IL)-1β, calcium ionophore A23187' or phorbol myristate acetate, and cytokine secretion was determined over specified intervals. Culture supernatants and cell lysates were analyzed by ELISA for IL-1β, IL-3, IL-4, IL-5, IL-6, IL-8, IL-11, IL-1 receptor antagonist (IL-1ra), tumor necrosis factor-α (TNF-α), and granulocyte-macrophage colony stimulating factor (GM-CSF).With the exception of IL-1ra, unstimulated conjunctival epithelial cells produced cytokines at relatively low or undetectable levels. IL-1ra was detected in both culture supernatants and cell lysates under basal conditions. In response to stimuli, conjunctival epithelial cells secreted the proinflammatory cytokines TNF-α, IL-6, IL-8, and GM-CSF in a dose-and time-dependent fashion. After stimulation, the intracellular levels of IL-1ra increased in these cells but the supernatant-associated levels remained unchanged. None of the other cytokines evaluated (IL-1β IL-3, IL-4, IL-5, and IL-11) were detected in supernatants or lysates of resting or stimulated cells.These findings suggest that conjunctival epithelial cells may contribute to the pathogenesis of human ocular diseases by production of proinflammatory cytokines. Further evaluation of these cells as targets of therapy is warranted.