Altered morphology of mucosa-associated lymphoid tissues and epithelium in the nasal cavity and lacrimal apparatus in autoimmune disease-prone MRL/MpJ-Faslpr/lpr mice.

The mucosal epithelium and the mucosa-associated lymphoid tissues (MALTs) protect the mucosa, such as eye and nose, from constant exposure to foreign antigens. As autoimmune disorders can target both epithelium and MALTs, we morphologically investigated the head of MRL/MpJ-Fas^lpr/lpr, an autoimmune disease-prone mouse, to discuss the pathological crosstalk among autoimmune disorders, mucosal epithelium, and MALTs. Compared to healthy control MRL/MpJ mice, MRL/MpJ-Fas^lpr/lpr mice had more lymphoid tissues that were diffusely localized beneath the mucosa epithelium in their lacrimal tracts and nasal cavity. Particularly, lacrimal duct- and nasopharynx-associated lymphoid tissues (LDALT, NALT) were identified as the major MALTs in the mouse head. In the nasal mucosa, MRL/MpJ-Fas^lpr/lpr mice exhibited larger NALT, more frequent non-ciliated epithelial cells, and more goblet cells than in MRL/MpJ mice. NALT in MRL/MpJ-Fas^lpr/lpr mice contained more proliferating cells than in MRL/MpJ mice. Moreover, LDALT in some MRL/MpJ-Fas^lpr/lpr mice developed by being directly connected to the bone marrow surrounding the nasolacrimal duct. These data suggested systemic autoimmune disorders could alter the mucosal immunity of the head by affecting both mucosal epithelium and MALTs. These findings are crucial for understanding the pathology of the head mucosal immunity.