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Macrophages in lymphoid organs are in close contact to nerve terminals of the sympathetic nervous system. Hence, these cells could be targets of neuronal modulation. We studied sympathetic neurotransmitters as chemoattractants enabling the aggregation of macrophages and nerve terminals. Norepinephrine (NE), neuropeptide Y (NPY), isoproterenol (␤-adrenergic), p-aminoclonidine (␣ 2 -adrenergic), methoxamine (␣ 1 -adrenergic), and adenosine triphosphate (ATP) were used to study human monocyte and macrophage migration in 48-well Boyden chambers. NE stimulated chemotaxis of monocytes and macrophages at an optimal concentration of 10 -10 M (P F 0.025). Isoproterenol, but not p-aminoclonidine or methoxamine, induced chemotaxis of monocytes (10 ؊10 M, P F 0.05). In these studies, elevation of cAMP is a critical step in NE-induced chemotaxis of monocytes. NPY (10 ؊11 M, P F 0.05) stimulated monocyte chemotaxis as well. ATP at 10 ؊4 and 10 ؊5 M stimulated undirected cell mobility (P F 0.05). All tested neurotransmitters of the sympathetic nerve terminal were potent chemoattractants. These findings may explain the close association of nerves and macrophages in tissue and lymphoid organs and may thus be of functional relevance in neuroimmunomodulation. J. Leukoc. Biol. 67: 553-558; 2000.

The growth factors PDGF-AB, IGF-I, EGF and TGF-beta1 stimulate the migration of CMF. However, factors secreted by CMF are essential for their ability to migrate in response to these growth factors. The identification of physiologically relevant migration inducing factors may help to elucidate the network of interactions and the complex mechanisms involved in intestinal wound healing or fibrosis.

Background: CD40 has been shown to be a functional activation antigen on a variety of cell types involved in immune responses. As intestinal fibroblasts and myofibroblasts may play a role during mucosal inflammation, we investigated the functional consequences of CD40 induction in primary cultures of human colonic fibroblasts. Methods: Primary colonic lamina propria fibroblasts (PCLF) were isolated from endoscopic biopsies and surgical specimens. Cultures were used between passages 3 and 9. CD40 surface display was determined by FACS analysis and mRNA expression by reverse transcription-polymerase chain reaction. Secretion of cytokines was determined by ELISA. Nuclear factor kB (NFkB) activation was shown by electrophoretic mobility shift assay (EMSA). Results: After priming with interferon c (IFN-c) (200 U/ml) for 72 hours, five of eight tested PCLF cultures showed induction of CD40 surface display (up to 10-fold). Induction of CD40 mRNA expression was demonstrated by semiquantitative polymerase chain reaction. In the responder-PCLF cultures, IFN-c alone caused a 1.5-5-fold increase in interleukin (IL)-8 secretion. Addition of 1 ng/ml CD40L was sufficient to achieve a further increase in IL-8, IL-6, or monocyte chemotactic protein 1 (MCP-1) secretion (2.5-18-fold of controls). Incubation with CD40L alone without priming with IFN-c had no effect. The proteasome inhibitor N-acetyl-leucinyl-leucinyl-norleucinal (ALLN 100 mM) reduced IFN-c/CD40L mediated cytokine induction, suggesting participation of NFkB, which was directly demonstrated by EMSA. CD4+ T cells induced MCP-1 secretion by PCLF, which was prevented by addition of an excess of CD40-IgG fusion protein. CD40 expression on PCLF could also be demonstrated in vivo by immunohistochemistry. Conclusion: The CD40-CD40L pathway augments mucosal inflammatory responses via mucosal PCLF. CD40-CD40L mediated T cell/PCLF interactions could play an important role during intestinal mucosal inflammation.

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