Involvement of Chemokines and a CD4-Positive T Cell Subset in the Development of Conjunctival Secondary Lymphoid Follicles in an Atopic Keratoconjunctivitis Mouse Model.

BACKGROUND: Massive B cell lymphoid hyperplasia and its associated factors may play a role in exacerbating inflammation in allergic disorders. We here investigated the chemokines and CD4-positive T cell subset involved in the development of secondary lymphoid follicles (iCALT) in conjunctival tissues in an atopic keratoconjunctivitis mouse model (AKC mouse).

METHODS: NC/Nga mice were divided into three groups: AKC (percutaneous sensitization and instillation of crude house dust mite antigen), AD (percutaneous sensitization only) and C (untreated control). Pathological changes in the conjunctival tissues of each group were investigated using histological and immunohistochemical detection of CD4 and CD20. Furthermore, tissue sections of iCALT (AKC-iCALT subgroup) and conjunctiva without iCALT (AKC-conjunctiva subgroup) were obtained from AKC mice using laser-assisted microdissection. mRNA expression of chemokine and T cell subset-related transcription factors were compared between the AKC-iCALT and AKC-conjunctiva subgroups using polymerase chain reaction (PCR) array and real-time reverse transcription-PCR (RT-PCR) methods.

RESULTS: iCALT with central aggregation of CD20-positive B cells and CD4-positive T cell infiltration surrounding B cells was observed in the palpebral conjunctival tissue of the AKC group, but not in that of the AD and C groups. Chemokine and T cell subset-related transcription factor expression was confirmed using real-time RT-PCR, with significant increases in Ccl5, Ccl17, Cxl20, Cxcl3, Ccr7, Foxp3 and T-bet mRNA expression in the AKC-iCALT subgroup compared with those in the AKC-conjunctiva subgroup.

CONCLUSIONS: We concluded that CCL5, CCL17 and CCL20, as well as T-bet- and Foxp3-positive lymphocytes may be iCALT-related factors and that iCALT-related chemokines are worth evaluating as biomarkers.