Altered cytokine balance in the tear fluid and conjunctiva of patients with Sjogren's syndrome keratoconjunctivitis sicca

Purpose. To compare epidermal growth factor (EGF) concentration in tear flu id and levels of inflammatory cytokines in the conjunctival epithelium of p atients with Sjogren's syndrome keratoconjunctivitis sicca with those of no rmal controls. Methods. Schirmer 1 tear testing, corneal fluorescein staining and conjunct ival impression cytology for quantitation of goblet cell density were perfo rmed in ten patients with Sjogren's syndrome-associated keratoconjunctiviti s sicca and ten asymptomatic normal controls. ELISA was used to detect the concentration of EGF in tear fluid and interleukin 6 in lysates of conjunct ival cytology specimens obtained from all subjects. The levels of RNA trans cripts encoding inflammatory cytokines [interleukin 1 alpha (IL-1 alpha), i nterleukin 6 (IL-6), interleukin 8 (IL-8), tumor necrosis factor alpha (TNF -alpha), and transforming growth factor beta 1 (TGF-beta 1)] as well as a h ousekeeping gene (G3PDH) were evaluated in conjunctival cytology specimens taken from all subjects by semiquantitative competitive reverse transcripta se polymerase chain reaction (RT-PCR). Results. Decreased tear fluid EGF concentration was noted in Sjogren's synd rome patients (mean 0.68 +/- 0.59 ng/ml) compared to controls (mean 1.66 +/ - 0.45 ng/ml, P = 0.004). Significantly increased levels of IL-1 alpha, IL- 6, IL-8, TNF-alpha and TGF-beta 1 RNA transcripts were found in the conjunc tival epithelium of Sjogren's syndrome patients compared to controls (P < 0 .05), while the level of G3PDH was similar in both groups. The concentratio n of IL-6 protein was significantly higher in Sjogren's syndrome conjunctiv a samples (P = 0.012). Tear EGF concentration correlated with Schirmer 1 sc ores (rho 0.767, P < 0.001), corneal fluorescein staining scores (rho -0.56 2, P = 0.01), conjunctival goblet cell density (rho 0.661, P = 0.001) and t he levels of IL-1 alpha and IL-8 RNA in the conjunctival epithelium (rho -0 .677 and -0.747, respectively, P = 0.001). Both IL-1 alpha and IL-8 RNA in the conjunctival epithelium increased as Schirmer 1 scores decreased (P les s than or equal to 0.001). IL-8 RNA level correlated with corneal fluoresce in staining (rho 0.690, P = 0.001) and conjunctival goblet cell density (rh o -0.767, P < 0.001). A significant decrease in IL-8 RNA level, correspondi ng to improvement in irritation symptoms and ocular surface disease, was ob served in six eyes after two weeks of topical corticosteroid therapy. Conclusions. The balance of cytokines in the tear fluid and conjunctival ep ithelium is altered in Sjogren's syndrome. The severity of keratoconjunctiv itis sicca in this condition increases as tear fluid EGF concentration decr eases and levels of inflammatory cytokines in the conjunctival epithelium i ncrease. These findings provide new insight into the pathogenesis of kerato conjunctivitis and provide potential targets for therapy.