Degree Name

PhD (Doctor of Philosophy)

Program

Biomedical Sciences

Date of Award

August 1999

Abstract

This dissertation represents efforts to determine the functional consequences acquired by vascular smooth muscle cells (SMC) in response to CD40 ligation by activated CD154+ T cells, and to elucidate components of the signaling pathway(s) activated in response to CD40 signaling in both monocytes and SMC. To study the consequences of CD40 stimulation, primary human monocytes and aortic SMC were treated with plasma membranes purified from CD154 + , CD4+ T cells. The results presented in this dissertation demonstrate that SMC, like monocytes/macrophages, are capable of interacting with T cells in a manner that results in reciprocal activation events. SMC were shown to present antigen to, and activate T cells. In turn T cell stimulus resulted in the activation of proinflammatory function in SMC initiated through the CD154:CD40 interaction. CD40 stimulation of SMC resulted in the production of the chemokines interleukin 8 (IL-8) and macrophage chemotactic protein-1 (MCP-1), and the upregulation of intercellular adhesion molecule (ICAM). Examination of the intracellular signaling pathways activated through CD40 signaling revealed the involvement of MAPKs in the pathway leading to induction of proinflammatory activity. Evaluation of CD40 signaling in monocytes demonstrated the activation of the MAPK family members ERK1/2, but not the MAPK family members p38 or c-jun-N-terminal kinase (JNK). In contrast, CD40 signaling in SMC was shown to result in ERK1/2 and p38 activation, and both of these kinases were shown to play a critical role in the induction of chemokine synthesis. An examination of the ability of anti-inflammatory cytokines to modulate CD40 signaling in monocytes and SMC demonstrated that the anti-inflammatory cytokines IL-4 and IL-10 abrogate CD40-mediated induction of inflammatory cytokine production by monocytes. This inhibition was shown to be a result of a negative influence of IL-4 and IL-10 on CD40 mediated ERK1/2, activation in monocytes. However, IL-4 and IL-10 did not inhibit SMC proinflammatory responses indicating a difference in the intracellular responses to these cytokines by the two cell types. (Abstract shortened by UMI.)

Document Type

Dissertation - Open Access

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