Systemic autoimmune abnormalities alter the morphology of mucosa-associated lymphoid tissues in the rectum of MRL/MpJ-Faslpr/lpr mice

• Published in: Experimental Animals Vol. 73; no. 3; pp. 270 - 285
• Main Authors: Rubel, Md. Zahir Uddin, Ichii, Osamu, Namba, Takashi, Masum, Md. Abdul, Chuluunbaatar, Tsolmon, Hiraishi, Masaya, Nakamura, Teppei, Kon, Yasuhiro
• Format: Journal Article
• Language: English
• Published: Japanese Association for Laboratory Animal Science 01.01.2024
• Subjects: autoimmune disease; chemokines; M cell; MRL/MpJ-Faslpr/lpr; Original; rectum mucosa-associated lymphoid tissue
• ISSN: 1341-1357; 1881-7122
• DOI: 10.1538/expanim.23-0129

Systemic autoimmune diseases (ADs) might affect the morphology and function of gut-associated lymphoid tissue (LTs) indirectly; however, their exact relationship remains unclear. Therefore, we investigated mouse LTs in the anorectal canal and morphologically compared them between MRL/MpJ-Fas+/+ and MRL/MpJ-Faslpr/lpr mice. LT aggregations, also known as rectal mucosa-associated lymphoid tissues (RMALTs), were exclusively seen in the lamina propria and submucosa of the rectum. The mean size and number of the LT aggregations both significantly increased in MRL/MpJ-Faslpr/lpr mice compared to those in MRL/MpJ-Fas+/+ mice. The distance from the anorectal junction to the first LT aggregate was significantly shorter in MRL/MpJ-Faslpr/lpr mice than that in MRL/MpJ-Fas+/+ mice. Immunostaining revealed that the RMALTs included CD3+, CD4+, and CD8+ T cells; B220+ B cells; IBA1+ macrophages; Ki67+ proliferative cells; and PNAd+ high-endothelial venules (HEVs). The numbers of macrophages, proliferative cells, CD4+ T cells, CD8+ T cells, and HEVs were significantly increased in MRL/MpJ-Faslpr/lpr mice compared to those in MRL/MpJ mice. Furthermore, the gene expression levels of chemokines (Cxcl9 and Cxcl13) and their corresponding receptors (Cxcr3 and Cxcr5) were significantly higher in MRL/MpJ-Faslpr/lpr mice than those in MRL/MpJ-Fas+/+ mice. Although the morphology of rectal epithelium was comparable between the strains, M cell number was significantly higher in MRL/MpJ-Faslpr/lpr mice than in MRL/MpJ-Fas+/+ mice. Thus, ADs could alter RMALT morphology, and quantitative changes in T-cell subsets, proliferative cells, macrophages, HEVs, chemokine expression, and M cells could affect their cell composition and development.