Role of soluble factors and three-dimensional culture in in vitro differentiation of intestinal macrophages.

Aim: To examine the factor(s) involved in differentiation of intestinal macrophages (IMACs) using a recently established in vitro model.

Methods: To test whether soluble or membrane bound factors induce IMAC-differentiation, freshly elutriated monocytes (MO) were incubated with conditioned media or cell membranes of intestinal epithelial cells (IEC) or cultured with IEC in transwell systems. To determine the importance of an active migration of MO, three-dimensional aggregates from a 1:1-mixture of MO and IEC were examined by immunohistochemistry and flow cytometry.

Serum soluble TNF receptor I and II levels correlate with disease activity in IBD patients.

Background: Tumor necrosis factor alpha (TNFalpha) is a proinflammatory cytokine and an important mediator in the pathophysiology of inflammatory bowel disease (IBD). The effects of TNFalpha are mediated by 2 specific receptors, a 55-kDa protein (TNF-RI) and a 75-kDa receptor (TNF-RII), which are usually bound to the cell surface. Soluble TNF receptors I and II (sTNF-RI + II) are released by proteolytic cleavage of the extracellular domains of these receptors.

Monocyte chemoattractant protein-1 (MCP-1) inhibits the intestinal-like differentiation of monocytes.

Monocytes (MO) migrating into normal, non-inflamed intestinal mucosa undergo a specific differentiation resulting in a non-reactive, tolerogenic intestinal macrophage (IMAC). Recently we demonstrated the differentiation of MO into an intestinal-like macrophage (MAC) phenotype in vitro in a three-dimensional cell culture model (multi-cellular spheroid or MCS model). In the mucosa of patients with inflammatory bowel disease (IBD) in addition to normal IMAC, a reactive MAC population as well as increased levels of monocyte chemoattractant protein 1 (MCP-1) is found.

(E)-metanicotine hemigalactarate (TC-2403-12) inhibits IL-8 production in cells of the inflamed mucosa.

Background: Nicotine is of therapeutic value in ulcerative colitis, but its administration is connected with adverse events. Nicotine derivatives are currently being tested to maintain the therapeutic effects and minimize adverse events. TC-2403-12 is a (E)-metanicotine hemigalactarate.

Physiological role of macrophage inflammatory protein-3 alpha induction during maturation of intestinal macrophages.

Intestinal macrophages (IMAC) are a central component in the defense of the intestinal mucosa against luminal microbes. In normal mucosa, monocytes differentiate to immunologically tolerant IMAC with a typical phenotype lacking activation markers such as CD14 and TLRs 2 and 4. CD33+ IMAC were isolated from normal intestinal mucosa by immunomagnetic beads.