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Despite considerable progress in allogeneic hematopoietic cell transplantation (allo-HCT) has been achieved over the past years, chronic Graft-versus-Host Disease (cGvHD) still contributes to high morbidity rates, thus remaining a major hurdle in allo-HCT patients. To understand the complex pathophysiology of cGvHD and to develop refined prophylaxis and treatment strategies, improved pre-clinical models are needed. In this study, we developed two murine cGvHD models, which display high long-term morbidity but low mortality and depict the heterogeneous clinical manifestations of cGvHD seen in patients. We established a haploidentical C57BL/6!B6D2F1 allo-HCT model that uses myeloablative radiation and GCSF-mobilized splenocytes as stem cell source and a sub-lethally irradiated Xenograft model, which utilizes the transfer of human peripheral blood mononuclear cells (PBMCs) into NOD scid gamma (NSG)-recipients. We characterized both mouse models to exhibit diverse clinical and histopathological signs of human cGvHD as extensive tissue damage, fibrosis/sclerosis, inflammation and B cell infiltration in cGvHD target organs skin, liver, lung and colon and found a decelerated immune cell reconstitution in the late phase after HCT. Our pre-clinical models can help to gain a deeper understanding of the target structures and mechanisms of cGvHD pathology and may enable a more reliable translation of experimental findings into the human setting of allo-HCT. [ABSTRACT FROM AUTHOR]

Differential gene expression between the metastatic human colon cancer cell line HT29p and its nonmetastatic counterpart HT29-MTX was revealed by suppression subtractive hybridization. Fifty-eight individual genes showed increased mRNA levels in HT29p cells. Only 15 of these genes had been related to transformation in previous studies; the majority of genes are new candidates encoding proteins relevant for the metastatic process. Cancer profiling arrays as well as in situ hybridization study revealed that at least some of the genes obtained in the SSH screen are also differentially expressed in human tumors. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Galectin-3 is an endogenous mammalian lectin that binds toABH carbohydrate antigens. Here we show that galectin-3 is stronglyup-regulated during mammary gland involution and that it is expressedvirtually exclusively on nonapoptotic cells. We demonstrate thatdexamethasone, an inhibitor of the second phase of mammary glandinvolution, potently suppresses up-regulation of galectin-3 as judgedimmunohistochemically and on western blots, suggesting that systemichormone levels regulate galectin-3 expression during involution.However, at the RNA level galectin-3 expression is rapidly up-regulatedon the onset of involution but remains consistantly high duringthe first and second phase of involution regardless of dexamethasonetreatment. These data suggest that the up-regulation of galectin-3in the involuting mammary gland is not only controlled transcriptionallybut also regulated posttranscriptionally under the control of systemicglucocorticoid hormones involved in coordinating the involutionprocess. [ABSTRACT FROM PUBLISHER]

Antibodies against the histo-blood group B–likeantigen M-N#1 efficiently block the growth invivo of rat mammary carcinoma cells that bear the antigen (Sleeman et al., 1999, Oncogene 18, 4485–4494).To try to understand the function of the M-N#1 antigen,we investigated when and where the antigen is expressed during thenormal function of the rat mammary gland. Expression was virtuallyonly seen during mammary gland involution. Here, strong expressionof the antigen was observed in mammary epithelial cells, beginning around2 days postweaning and lasting throughout the involution process.Dexamethasone treatment of animals postlactation inhibited alveolarcollapse and remodeling in the mammary gland but inhibited neitherthe apoptosis of mammary epithelial cells nor the expression ofthe M-N#1 antigen. We show that up-regulation of carbohydrateantigens is not a general phenomenon during mammary gland involution,and thus that M-N#1 antigen expression is specificallyregulated. Up-regulation of α(1,2)fucosyltransferaseA, an enzyme required for M-N#1 antigen synthesis, is atleast partly responsible for regulated M-N#1 antigen expressionpostlactation. Most significantly, we observed that the M-N#1antigen is virtually exclusively expressed on nonapoptosing epithelialcells in the involuting mammary gland. These data suggest that M-N#1antigen expression might either provide a survival function and/orbe expressed in epithelial cells that are destined to grow and remodelmammary duct structures. [ABSTRACT FROM PUBLISHER]

Clinical studies suggested that endothelial dysfunction and damage could be involved in the development and severity of acute graft-versus-host disease (aGVHD). Accordingly, we found increased percentage of apoptotic Casp3+ blood vessels in duodenal and colonic mucosa biopsies of patients with severe aGVHD. In murine experimental aGVHD, we detected severe microstructural endothelial damage and reduced endothelial pericyte coverage accompanied by reduced expression of endothelial tight junction proteins leading to increased endothelial leakage in aGVHD target organs. During intestinal aGVHD, colonic vasculature structurally changed, reflected by increased vessel branching and vessel diameter. Because recent data demonstrated an association of endothelium-related factors and steroid refractory aGVHD (SR-aGVHD), we analyzed human biopsies and murine tissues from SR-aGVHD. We found extensive tissue damage but low levels of alloreactive T cell infiltration in target organs, providing the rationale for T-cell independent SR-aGVHD treatment strategies. Consequently, we tested the endothelium-protective PDE5 inhibitor sildenafil, which reduced apoptosis and improved metabolic activity of endothelial cells in vitro. Accordingly, sildenafil treatment improved survival and reduced target organ damage during experimental SR-aGVHD. Our results demonstrate extensive damage, structural changes, and dysfunction of the vasculature during aGVHD. Therapeutic intervention by endothelium-protecting agents is an attractive approach for SR-aGVHD complementing current anti-inflammatory treatment options.