Fig. 4: IL-9 overproduction was induced by epithelium-derived IL-33 in allergic inflammation.

In conjunctiva (Conj), cornea and/or CLN of PBS-treated mice and EAC mice, IL-33 (a) and ST2 (d) mRNA expressions were evaluated by RT-qPCR; IL-33 production was detected by ELISA (b). In PBS-treated mice and EAC mice, IL-33 expression in cornea and Conj was shown by IHC staining (c); ST2 and CD4 expression in Conj and CLN (e) were shown by IF double staining. Direct effects of rmIL-33 on IL-9 expression in isolated mice CD4⁺ T cells was detected at mRNA (f, up) and protein (f, down) levels. IL-9 signal pathway related proteins (including PU.1, NFATc1, and NFATc2) were evaluated in mice CD4⁺ T cells induced by rmIL-33 (g). Results shown are the mean ± SD (n = 5), *P < 0.05, **P < 0.01, compared with PBS controls. Bar: 20 μm.