The Role of the IL-20 Subfamily in Glaucoma

Figure 2

(a) Schematic of the anterior chamber of the eye showing the location of the trabecular meshwork and the flow pattern of aqueous humor. Image was slightly modified from those freely provided by the National Eye Institute, National Institute of Health. (b) H&E stained radial section of a human trabecular meshwork. The TM is a triangular-shaped tissue comprised of a series of fenestrated beams around which the aqueous humor flows (red arrows) before draining into Schlemm’s canal. For orientation purposes, the cornea is to the right and the ciliary body is toward the left. (c) Schematic of IL-20 signaling in normal cells. IL-20 or IL-24 binds to the IL-20RB receptor, which phosphorylates Janus kinase (JAK). JAK then phosphorylates STAT3, which translocates to the nucleus to promote transcription of inflammation-related target genes. This in turn increases MMP activity and ECM remodeling. (d) In glaucoma cells harboring the IL-20RB T104M mutation, the cytokine is unable to bind to the receptor so the JAK/STAT3 pathway is not activated. Therefore, higher expression of proinflammatory genes remains and elevated IOP would be sustained since MMP activity and ECM remodeling are not affected.

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