Control Of Organ Transplant-Associated Graft-versus-Host Disease By Activated Host Lymphocyte Infusions
Background Prolonged persistence of donor-derived T cells after organ transplantation has been proposed to improve long-term allograft survival. However, surviving transplant-derived T cells are also able to mediate devastating graft-versus-host disease (GvHD). Currently, GvHD after organ transplantation is usually refractory to conventional therapy and the disease outcome fatal. Methods Graft-reactive host T cells were generated ex vivo from a patient suffering from a severe and refractory liver-transplant-associated GvHD. To control GvHD, activated alloreactive host T cells were repetitively retransferred into the patient (activated host lymphocyte infusion [aHLI]). Results Adoptive trans…
Hepatic over-expression of TGF-beta1 promotes LPS-induced inflammatory cytokine secretion by liver cells and endotoxemic shock.
Transforming growth factor-beta (TGF-beta) is an important suppressor of inflammation. However, TGF-beta has also been found to promote secretion of inflammatory cytokines, and transgenic mice, which constitutively express TGF-beta in liver, have been found to be more susceptible to endotoxemia. To approach this apparent paradox, we investigated the role of hepatic TGF-beta1 in endotoxemia by utilising inducible TGF-beta1-transgenic mice that express TGF-beta1 under control of the C-reactive protein promoter. In contrast to non-transgenic littermates, administration of lipopolysaccharide (LPS) induced strongly increased expression of TGF-beta and acute phase proteins in the TGF-beta1-transg…
Chronic inflammatory IFN-γ signaling suppresses hepatocarcinogenesis in mice by sensitizing hepatocytes for apoptosis.
Abstract Chronic liver inflammation is a critical component of hepatocarcinogenesis. Indeed, inflammatory mediators are believed to promote liver cancer by upholding compensatory proliferation of hepatocytes in response to tissue damage. However, inflammation can also mediate the depletion of malignant cells, but the difference between tumor-suppressive and tumor-promoting inflammation is not defined at the molecular level. Here, we analyzed the role of the major inflammatory mediator IFN-γ in chemical hepatocarcinogenesis of transgenic mice that overexpress IFN-γ in the liver; these mice manifest severe chronic inflammatory liver damage and lasting compensatory regeneration. We found that …
P38 MAP Kinase Signaling Is Required for the Conversion of CD4+CD25− T Cells into iTreg
CD4+CD25+ regulatory T cells (Treg) are important mediators of immune tolerance. A subset of Treg can be generated in the periphery by TGF-beta dependent conversion of conventional CD4+CD25− T cells into induced Treg (iTreg). In chronic viral infection or malignancy, such induced iTreg, which limit the depletion of aberrant or infected cells, may be of pathogenic relevance. To identify potential targets for therapeutic intervention, we investigated the TGF-beta signaling in Treg. In contrast to conventional CD4+ T cells, Treg exhibited marked activation of the p38 MAP kinase pathway. Inhibition of p38 MAP kinase activity prevented the TGF-beta-dependent conversion of CD4+CD25− T cells into …