Retinal pigment epithelium (RPE) constituting the outer blood-retina barrier plays an important role in ocular defense mechanism. Many studies reported that RPE participates in ongoing immune responses in the retina. However, the exact mechanism is still uncertain. Toll-like receptors (TLRs) participate in the recognition of pathogen-associated molecular patterns (PAMP), such as LPS, zymosan, lipoprotein, and dsRNA. The expression and function of TLRs in human RPE have not been established. In

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... his study, we investigated TLRs expression in human fetal RPE and their recognition of PAMP to determine how human RPE participates in ocular defense mechanism against microbial component. RT-PCR and real time PCR revealed that TLR1 through 5 were constitutively expressed in human fetal RPE, and their expressions were slightly increased by LPS. We determined the TNF-α, IL-6, and IL-8 expression in human fetal RPE after treatment with LPS, zymosan, petidoglycan, or poly I:C. RT-PCR demonstrated that LPS and poly I:C treatment increased the production of TNF-α, IL-6, and IL-8 in human fetal RPE. LPS showed more potent effects on TNF-α and IL-8 production. Peptidoglycan and zymosan did not induce the production of TNF-α. CD14, the co-receptor of LPS was weakly expressed and functioned in recognizing LPS in human fetal RPE. These results suggest that human RPE may participate in ocular defense mechanism against microbial component through toll-like receptors. 서 론 눈은 면역관용지역 (immune privileged region)으로 혈관-눈 장벽 (blood-ocular barrier)에 의해 주위조직과 분리되어 있다. 망막색소상피 (retinal pigment epithelium, RPE)는 혈관-눈 장 벽을 구성하는 한층의 세포이다. 망막색소상피층은 혈관이 없는 neurosensory retina에 산소와 영양분을 제공하고, 광수 용체층의 바깥분절에서 떨어져 나온 조직파편을 탐식하고 분해하며, 광수용체층을 지지하고 유지하는 역할을 한다 (27).