Semaphorin 7A on keratinocytes induces interleukin-8 production by monocytes.
J Dermatol Sci 2011;
62:176-82. [PMID:
21524887 DOI:
10.1016/j.jdermsci.2011.02.004]
[Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 02/08/2011] [Accepted: 02/21/2011] [Indexed: 12/26/2022]
Abstract
BACKGROUND
Semaphorin 7A (Sema7A) expressed on activated T cells stimulates cytokine production in monocytes through its receptor, α1β1 integrin.
OBJECTIVE
To study the significance of Sema7A expressed on keratinocytes in skin inflammation where interaction between keratinocytes and β1-integrin expressing inflammatory cells, such as monocytes, takes place.
METHODS
The regulation of Sema7A expression on keratinocytes by various cytokines was studied by flow cytometry and immunoblot. β1-integrin expressing human monocyte cell line, THP-1 cells, were co-cultured with paraformaldehyde-fixed normal human epidermal keratinocytes (NHK) and IL-8 production by THP-1 cells was studied. The significance of β1-integrin or Sema7A within this cell interaction was examined by the experiments using β1-integrin blocking antibody or Sema7A siRNA.
RESULTS
IFN-γ and TNF-α slightly increased Sema7A expression, while IL-4 decreased it. Among cytokines tested, TGF-β1 most strikingly increased the Sema7A expression on NHK. When NHK was stimulated by TGF-β1, paraformaldehyde-fixed, and co-cultured with THP-1 cells, IL-8 production by THP-1 cells was increased compared to THP-1 cells only. When THP-1 cells were pretreated with β1-integrin blocking antibody, this increase in IL-8 production by THP-1 cells was inhibited. Likewise, when NHK were pretreated with Sema7A siRNA before fixation and co-cultured with THP-1 cells, increase in IL-8 production by THP-1 cells was inhibited.
CONCLUSION
Our results suggest that Sema7A on keratinocytes and β1-integrin on monocytes contribute to monocyte activation by keratinocytes within skin inflammation, such as psoriasis or wound.
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