Cmtm4 deficiency ameliorates Th1 cell infiltration and improves clinical signs in experimental dry eye

Abstract

Purpose : Dry eye disease (DED) is an inflammatory autoimmune disorder affecting the ocular surface. Transmembrane protein CMTM4 has been reported to be a subunit of the IL-17 receptor and mediates autoimmune pathology, however, its functions in DED are still unknown. In this study, we aimed to investigate the expression and the immunoregulatory effect of CMTM4 on DED.

Methods : We investigated the expression of Cmtm4 in healthy and DED-afflicted corneal and conjunctival tissues via the GEO database. In vivo analysis was conducted on wild-type (WT) and Cmtm4 knockout (Cmtm4^-/-) mice. DED was induced using scopolamine (SCOP). Tear secretion reduction was confirmed with the phenol red thread test. Ocular surface damage was verified with fluorescein sodium staining. Flow cytometric analysis was conducted to determine the proportion of Th1, Th17, and Treg cell subsets, as well as the mean fluorescence intensity (MFI) of IFN-γ, IL-17A, and Foxp3 within the draining lymph nodes (DLNs). Furthermore, the corneal and conjunctival expression profiles of IL-17-responsive genes, including Cxcl1, Ccl20, Il6, and Tnfa, were characterized via RT-PCR.

Results : In corneal and conjunctival tissues of dry eye (DE) mice, an upregulation of Cmtm4 expression was observed. Under normal conditions, there was no significant difference in tear secretion or fluorescein sodium staining scores between WT mice and Cmtm4^-/- mice. However, in SCOP-induced DED, while WT mice demonstrated decreased tear production and severe corneal epithelium defects, Cmtm4^-/- mice displayed less tear production reduction and improved dry eye clinical signs (Figure 1). Additionally, genetic deletion of Cmtm4 also attenuated the heightened infiltration of Th1 cells and inhibited IFN-γ production in DLNs, without significantly affecting Th17 and Treg cell percentages (Figure 2). In Cmtm4^-/- mice with DED, Cxcl1, Ccl20, Il6, and Tnfa expression was decreased in the corneal and conjunctival tissues.

Conclusions : Collectively, these findings suggest that CMTM4 plays a pathogenic role in DED. Further studies are needed to investigate this mechanism.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Figure 1: CMTM4 improves clinical signs in DE mice. (***P < 0.001, ****P < 0.0001; WT, wild type; KO, Cmtm4^-/-)

 

Figure 2: CMTM4 attenuated the heightened infiltration of Th1 cells and inhibited IFN-γ production in DLNs. (*P < 0.05, **P < 0.01, ns = non-significant; WT, wild type; KO, Cmtm4^-/-)