Epithelium cytokine effects

J. C. Zech, I. Pouvreau, A. Cotinet, O. Goureau, B. Le Varlet, and Y. de Kozak. Effect of cytokines and nitric oxide on tight j unctions in cultured rat retinal pigment epithelium. Invest. Ophthalmol. Vis. Sci. 39 1600-1608 (1998). 

Once Salmonella invade the intestinal barrier, the bacteria encounter host immune cells such as neutrophils, lymphocytes and macrophages, which engulf the bacteria (Fields et al., 1986 McCormick et al., 1993) (Fig. 5.1). Salmonella serotypes capable of causing gastroenteritis are killed by host macrophages, and effectively cleared by the immune system. Invasion of M cells and intestinal epithelial cells induces a pro-inflammatory response in the intestinal mucosa (Fig. 5.1a). A combination of inflammatory cytokine production, neutrophil infiltration and fluid and electrolyte secretion by the epithelium results in the diarrhea associated with gastrointestinal enteritis (Fig. 5.1a). 

Cytokines may exert an important regulatory effect on the expression of adhesion molecules, both on endothelial cells of the bronchial circulation and on airway epithelial cells. Thus IL-4 increases the expression of VCAM-1 on endothelial cells and this may be important in eosinophil and lymphocyte trafficking (Schleimer etal., 1992), and II l and TNFa increase the expression of ICAM-1 in both vascular endothelium and airway epithelium (Tosi etal., 1992). 

There are several mechanisms that could explain the protective effect of o-adrenergic blockade against the shock-mediated cytokine-associated injury to the alveolar epithelium ... 

Bronchial biopsies in stable atopic asthmatics have observed these components (19,64). Several Th2-type cytokines, (IL-4, IL-5, IL-13, but not JFNy) and C-C chemokines are produced by multiple cells types, which regulate IgE synthesis and lead to the generation of eosinophilic airway inflammation (Fig. 9) (321). Allergic tissue damage results from the release of basic proteins, leukotrienes, and PAF secreted by activated eosinophils. It is clear that the mast cell plays an important role in the immediate response and that T cells play a key role in orchestrating the nature and severity of the inflammation by the secretion of cytokines. As stated earlier, the eosinophil is regarded as the primary effector cell due to the capacity to secrete major basic protein and eosinophil cationic protein, which have profound cytotoxic effects on the airway epithelium (316). 

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