Characterization of CD45RO⁺ memory T lymphocytes in keloid disease.

Abstract

Memory T cells, a highly effective subset of T lymphocytes, have been reported to be involved in many inflammatory skin disorders. However, the potential role of memory T cells in keloid disease (KD) remains unclear. Due to their important role in regulating inflammation, we investigated the characteristics of CD45RO⁺ memory T cells in KD. Primary cutaneous cells were isolated from keloid scars and normal skin by enzymic digestion. Peripheral blood mononuclear cells were isolated from a related blood sample, and flow cytometry was applied to identify the phenotypic and functional abnormalities of memory T cells in KD. We observed that the majority of T lymphocytes in keloid scars had the memory phenotype, and a greater number of the CD8⁺ memory T cells in keloid scars produced lower levels of tumour necrosis factor (TNF)-α. This abnormal cytokine production was even more distinct in Forkhead box (FOX)P3^-  CD8^- memory T cells, with lower TNF-α production and enhanced interferon-γ production. Furthermore, FOXP3⁺  CD8^- memory T cells in keloid scars were abnormal, including showing reduced CD25 and cytotoxic T-lymphocyte-associated antigen 4 expression and interleukin-10 production. In addition, a significant decrease in the number of CD4⁺  CD25^high  FOXP3⁺ regulatory T cells was identified in patients with multiple keloid scars. We also found that there was significantly increased infiltration of CD103⁺  CD8⁺ memory T cells in keloid scars. Our findings preliminarily elucidate the abnormalities of CD45RO⁺ memory T cells in keloid scars and provide early evidence that a disrupted T-cell response contributes to the progression of KD.