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Background & Aims: Intestinal homeostasis is coordinated through the response of different cell types, including the interaction of immune with nonimmune cells. This study investigated the effect of immune cell-derived proinflammatory cytokines on mesenchymal cell proliferation and gene product expression., Methods: Primary cultures of human mucosal mesenchymal cells were activated with interleukin (IL)-1 beta, IL-6, and tumor necrosis factor alpha (TNF-alpha). Proliferation was measured by thymidine incorporation, messenger RNA (mRNA) expression was assessed by Northern blot analysis, and IL-1 receptor type was identified by reverse-transcription polymerase chain reaction., Results: Mesenchymal cells dose-dependently proliferated in response to IL-1 beta, IL-6, and TNF-alpha. Each cytokine differentially induced mRNA expression in a dose-dependent and selective fashion: IL-1 beta was the most potent inducer, TNF-alpha was weaker, and IL-6 induced little or no mRNA; in contrast, IL-6 mRNA was the most abundantly induced, followed by IL-1 beta mRNA, whereas TNF-alpha mRNA was weakly and infrequently expressed. The IL-1 receptor antagonist inhibited cytokine mRNA expression, and mesenchymal cells expressed the type II, but not the type I, IL-1 receptor., Conclusions: The ability of intestinal mesenchymal cells to express proinflammatory gene products implicates them as regulators of local immune cells through immune-nonimmune interactions. Thus, mesenchymal cells should be considered as active regulators of intestinal immunity under normal and inflammatory conditions.

Background & Aims: Proinflammatory cytokines such as interleukin (IL) 1, IL-8, and tumor necrosis factor (TNF) have been implicated as primary mediators of intestinal inflammation. The aim of the present study was to determine the effects of a novel cytokine antagonist (CGP 47969A) in a rabbit model of acute colitis., Methods: Colitis was induced using the formalin-immune complex technique. Animals were pretreated intrarectally with CGP 47969A (30, 10, or 3 mg/kg), hydrocortisone (0.8 mg/kg), or vehicle (4 mL saline) 2 hours before the induction of colitis and twice daily thereafter until death 48 hours after the induction of colitis. The severity of inflammation of colonic tissue was assessed using histological analysis and myeloperoxidase activity assay, and IL-1 alpha, IL-8, TNF-alpha, and IL-1 receptor antagonist levels were determined., Results: Compared with vehicle, CGP 47969A (10 mg/kg) significantly reduced the acute inflammatory index by 58%, edema by 67%, necrosis by 99%, and myeloperoxidase activity by 49% (all P < 0.02) with efficacy similar to that of steroids. These effects were associated with a significant inhibition of colonic IL-1 alpha and IL-8 by 56% and 90%, respectively (p < 0.01)., Conclusions: Administration of CGP 47969A reduces inflammation and tissue damage in rabbit immune complex colitis through mechanisms involving the inhibition of mucosal proinflammatory cytokines.

We have previously shown that administration of a combination low-dose cyclosporine (CsA) (1.0 mg/kg/day)/methotrexate (MTX) (450 micrograms/kg/wk) treatment significantly increases the survival of rat cardiac allografts, and may therefore potentially serve as an alternative immunosuppressive therapy designed to promote transplant survival while minimizing high-dose CsA side effects. In contrast to high-dose CsA, low-dose CsA/MTX treatment does not appear to alter IL-2 gene expression, since similar patterns of IL-2 gene transcripts were found in both low-dose CsA/MTX-treated and untreated control allografts on days 1 through 8 posttransplantation (post-tx). The mechanism(s) by which low dose CsA/MTX therapy increases the time of allograft survival remains to be elucidated. The aim of the present study was to determine the effects of low-dose CsA/MTX on the expression of the cytotoxic cytokines, TNF alpha, TNF beta, or lymphotoxin (LT), and the serine proteases HF and C11 (granzymes A and B, respectively) in rat cardiac allografts during rejection. RNA blot analysis showed significant suppression of TNF alpha, LT, HF, and C11 gene expression on days 1 through 8 post-tx in cardiac allografts from low-dose CsA/MTX-treated recipients compared with untreated allograft controls. TNF protein levels in cardiac allografts from low-dose CsA/MTX-treated recipients were also found to be significantly reduced on days 1 through 8 post-tx when compared with time-matched untreated allograft controls (P < or = 0.001). We conclude that low-dose CsA/MTX treatment, while effective in prolonging cardiac transplant survival, appears to act at the mRNA level to downregulate cytotoxic cytokine gene expression. Such trials aimed at evaluating low-dose combination therapy may afford new insight into mechanisms underlying improvement in immunosuppressive treatment.