Inflammatory cells play a crucial role in wound healing, but the role of adhesion molecules including L-selectin and intercellular adhesion molecule-1 (ICAM-1) is not known in this process. We examined skin wound repair of excisional wounds in mice lacking L-selectin, ICAM-1, or both. The loss of ICAM-1 inhibited wound healing, keratinocyte migration from the edges of the wound toward the center, and granulation tissue formation. By contrast, L-selectin deficiency alone did not affect any of these parameters. However, the loss of both L-selectin and ICAM-1 resulted in inhibition of keratinocyte migration and granulation tissue formation beyond those caused by loss of ICAM-1 alone. Treatment of platelet-derived growth factor to the wounds normalized delayed wound healing in ICAM-1(-/-) mice, but not in L-selectin/ICAM-1(-/-) mice. Therefore, although ICAM-1 contributes to wound repair to a greater extent than L-selectin, a role for L-selectin was revealed in the absence of ICAM-1. The impaired wound repair was associated with reduced infiltration of neutrophils and macrophages in ICAM-1(-/-) and L-selectin/ICAM-1(-/-) mice. These results demonstrate a distinct role of ICAM-1 and L-selectin in wound healing and that the delayed wound healing in the absence of these molecules is likely because of decreased leukocyte accumulation into the wound site.

CC-chemokines are potent molecules that direct the migration of leukocytes to inflammatory foci. To determine their role in inflammation associated with atopic dermatitis (AD), we determined serum levels and spontaneous production of CC-chemokines by peripheral blood mononuclear cells (PBMC) in AD patients using an ELISA. Serum levels of RANTES, MCP-1, MIP-1beta, and eotaxin were increased in AD patients (n = 52) compared with normal controls (n = 22). Serum levels of RANTES, MCP-1, and MIP-1beta were increased in AD patients with severe disease (n = 19) compared with normal controls (n = 22). Spontaneous production of RANTES, MCP-1, MIP-1alpha and MIP-1beta by PBMC was augmented in AD patients (n = 39) and in patients with severe AD (n = 14) compared with normal controls (n = 20). Serum RANTES levels correlated with total serum IgE levels, eosinophil numbers, and serum lactate dehydrogenase levels. Our results suggest that augmented production of CC-chemokines correlates with inflammation associated with AD.

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The tight-skin (TSK/+) mouse, a genetic model for human systemic sclerosis (SSc), develops cutaneous fibrosis and autoantibodies against SSc-specific target autoantigens. Although molecular mechanisms explaining the development of fibrosis and autoimmunity in SSc patients or TSK/+ mice remain unknown, we recently demonstrated that SSc patients overexpress CD19, an important regulatory molecule expressed by B lymphocytes. B cells from CD19-deficient mice are hyporesponsive to transmembrane signals, while B cells overexpressing CD19 are hyperresponsive and generate autoantibodies. In this study, TSK/+ B cells also exhibited a hyperresponsive phenotype with decreased surface IgM expression, enhanced serum Ig production, and spontaneous autoantibody production. Moreover, CD19 tyrosine phosphorylation was constitutively augmented in TSK/+ B cells. CD19-mediated [Ca 2+ ] i responses, Vav phosphorylation, and Lyn kinase activity were similarly enhanced. Studies of TSK/+ mice deficient in CD19 expression demonstrated that CD19 deficiency significantly decreased skin fibrosis in TSK/+ mice. Additionally, CD19 loss in TSK/+ mice upregulated surface IgM expression and completely abrogated hyper-γ-globulinemia and autoantibody production. CD19 deficiency also inhibited IL-6 production by TSK/+ B cells. Thus, chronic B cell activation resulting from augmented CD19 signaling in TSK/+ mice leads to skin sclerosis possibly through IL-6 overproduction as well as autoimmunity.

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