Immunohistochemical Analysis of Interleukin-17 Producing T Helper Cells and Regulatory T Cells Infiltration in Annular Erythema Associated with Sjögren's Syndrome

BACKGROUND: Peculiar erythema known as annular erythema associated with Sjögren's syndrome (AESS) can be differentiated from autoimmune annular erythema and subacute cutaneous lupus erythematosus, both clinically and histologically. However, there are no detailed investigations on immune competent cells infiltration. OBJECTIVE: Preferential infiltration of interleukin-17-producing T helper (Th17) cells and regulatory T (Treg) cells into the labial salivary gland is reported to play a role in maintaining mucoepithelitis in patients with Sjögren's syndrome. In this study, we evaluated Th17 and Treg cell infiltration into the lesional skin of AESS. METHODS: We analyzed the numbers and infiltration patterns of Th17 and FoxP3 (+) Treg cells in seven cases of AESS using immunohistochemistry. Seven patients with systemic lupus erythematosus (SLE), atopic dermatitis (AD) and psoriasis vulgaris (PV), which are representatives of Th17 cell-involved skin disorders, were enrolled as disease controls. RESULTS: Periappendageal and epidermal changes, such as follicular plugging and liquefaction, were evident in the annular erythema of SLE, not AESS, tissue samples. In AESS tissue samples, dense perivascular and periappendageal infiltration of lymph cells was observed in the middle-to-deep dermis, as previously described, in contrast to the superficial infiltration pattern observed in both AD and PV samples. While the total number of infiltrated lymphocytes was similar between AESS and SLE tissue samples, Th17 cells were found to be preferentially infiltrated in the middle-to-deep dermis in AESS samples. CONCLUSION: These results suggest that an increased number and distribution of infiltration of Th17 cells is a preferential feature of AESS, rather than a characteristic feature of annular erythema of SLE.