We studied the effect of rHuKGF on acute, lethal graft- vs.-host disease (GVHD) in the C57BL/6-->(C57BL/6 X DBA/2)F(1)-hybrid model. rHuKGF-treated recipients did not develop intestinal GVHD despite elevated levels of intestinal NO and TNF alpha, did not develop endotoxemia, and did not die. LPS augmented serum TNF alpha release and intestinal NO production, but did not induce intestinal epithelial cell apoptosis, a phenomenon associated with acute GVHD. These data suggest that KGF prevents the development of acute lethal GVHD by protecting epithelial cell injury mediated by TNF-alpha, NO, and other potential cytotoxic factors. We noted a moderate reduction in intestinal KGFR mRNA expression in untreated GVH mice on day 8, when IFN-gamma mRNA levels were highest. This reduction in KGFR mRNA levels was not seen in recipients of IFN-gamma gene knockout grafts, suggesting that IFN-gamma may be involved in reducing KGFR mRNA expression in the intestine. A similar reduction in intestinal KGFR mRNA expression was also seen in rHuKGF-treated recipients, suggesting that rHuKGF does not mediate its protective effect by maintaining KGFR at control levels. KGF-treatment also redirected the cytokine response in acute GVH mice from Th1 to a mixed pattern of both Th1 and Th2 cytokines. This was associated with histopathologic changes resembling chronic GVHD.

SUMMARY(C57BL/6 Â DBA/2)F 1 -hybrid mice injected with lymphoid cells from wild-type, C57BL/6 donors develop acute, lethal graft-versus-host disease (GVHD) in which the intestine is a major target. In its destructive phase intestinal GVHD is characterized by apoptosis of intestinal crypt epithelial cells and the development of endotoxaemia. Injection of as little as 10 mg endotoxin is lethal in mice with acute GVHD, and associated with the release of large amounts of tumour necrosis factor-a (TNF-a) into the serum. To explore the role of interferon-g (IFN-g) in the pathogenesis of intestinal GVHD we used IFN-g gene knockout (gko) mice as donors. Recipients of grafts from these donors did not develop intestinal GVHD and, unlike recipients of wild-type grafts, did not die when injected with lipopolysaccharide (LPS). We also found that injection 10 mg LPS into recipients of wild-type grafts induced apoptosis of intestinal epithelial crypt cells and was associated with a burst of nitric oxide production in the intestine. Administration of N o nitro L-arginine methyl ester blocked this response. In contrast, LPS did not induce either intestinal epithelial cell apoptosis or increased nitric oxide production in recipients of IFN-g gko grafts. These ®ndings indicate that donor-derived IFN-g is instrumental for the development of intestinal GVHD. In a previous study we showed that recipients of IFN-g gko grafts develop high levels of LPS-induced TNF-a release. When our current data are viewed in the context of this observation, they suggest that intestinal epithelial cell apoptosis in the parent3F 1 -hybrid model of acute GVHD is mediated primarily by nitric oxide rather than TNF-a, and that this depends on donor-derived IFN-g.

These results suggest that NK1.1 depletion of the graft confers protection against mortality by interfering with an immunoregulatory mechanism that results in the development of a Th1 response in GVH mice, and does not result in abortion of the graft. Because macrophage priming is prevented, recipients are also protected from the exaggerated sensitivity to endotoxin seen in mice with acute GVHD.

Palifermin (recombinant human keratinocyte growth factor) prevents the development of acute, lethal graft-versus-host disease (GVHD). It does so, at least in part, by protecting cells from injury. Another property of Palifermin is immune regulation. How the latter influences the evolution of GVHD remains uncertain. We explored the effect of Palifermin on GVHD in the DBA/2 --> ((DBA/2)x(C57BL/6))F(1)-hybrid strain combination, a model associated with autoantibody production and glomerulonephritis. Untreated recipients survived until at least day 150 post-induction. Palifermin-treated recipients succumbed between days 50 and 90 with levels of proteinuria of up to 20 g/L, ascites, and rapidly progressive, crescentic glomerulonephritis that was most severe in mice with the greatest levels of proteinuria. Kidney sections from both Palifermin-treated and untreated recipients showed the presence of granular deposits of IgG, IgM, IgA, and C3 in the mesangium and the glomerular basement membrane. Electron microscopy confirmed the extensive glomerular immune complex deposition. Antinuclear and anti-dsDNA antibodies were present in sera from both treated and untreated recipients; however, those in the latter were only detectable if the serum was kept at 37 degrees C, indicating that they were cryoglobulins. IL-4 was detectable only in cultures from Palifermin-treated recipients and the levels of IL-5 and IL-13 were significantly higher in the Palifermin-treated group than in untreated GVHD mice. IFN-gamma was only detectable in untreated GVHD mice. These data suggest that although Palifermin can protect mice with acute GVHD, it exacerbates GVHD in a model associated with autoantibody production and a preponderance of Th2 cytokines.