The hepatic stellate cell has surprised and engaged physiologists, pathologists, and hepatologists for over 130 years, yet clear evidence of its role in hepatic injury and fibrosis only emerged following the refinement of methods for its isolation and characterization. The paradigm in liver injury of activation of quiescent vitamin A-rich stellate cells into proliferative, contractile, and fibrogenic myofibroblasts has launched an era of astonishing progress in understanding the mechanistic basis of hepatic fibrosis progression and regression. But this simple paradigm has now yielded to a remarkably broad appreciation of the cell's functions not only in liver injury, but also in hepatic development, regeneration, xenobiotic responses, intermediary metabolism, and immunoregulation. Among the most exciting prospects is that stellate cells are essential for hepatic progenitor cell amplification and differentiation. Equally intriguing is the remarkable plasticity of stellate cells, not only in their variable intermediate filament phenotype, but also in their functions. Stellate cells can be viewed as the nexus in a complex sinusoidal milieu that requires tightly regulated autocrine and paracrine cross-talk, rapid responses to evolving extracellular matrix content, and exquisite responsiveness to the metabolic needs imposed by liver growth and repair. Moreover, roles vital to systemic homeostasis include their storage and mobilization of retinoids, their emerging capacity for antigen presentation and induction of tolerance, as well as their emerging relationship to bone marrow-derived cells. As interest in this cell type intensifies, more surprises and mysteries are sure to unfold that will ultimately benefit our understanding of liver physiology and the diagnosis and treatment of liver disease.

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Hepatic Stellate Cells: Protean, Multifunctional, and Enigmatic Cells of the Liver

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Pathology and genetics of tumours of the digestive system

Metastasis, the dissemination and growth of neoplastic cells in an organ distinct from that in which they originated, is the most common cause of death in cancer patients. This is particularly true for pancreatic cancers, where most patients are diagnosed with metastatic disease and few show a sustained response to chemotherapy or radiation therapy. Whether the dismal prognosis of patients with pancreatic cancer compared to patients with other types of cancer is a result of late diagnosis or early dissemination of disease to distant organs is not known. Here we rely on data generated by sequencing the genomes of seven pancreatic cancer metastases to evaluate the clonal relationships among primary and metastatic cancers. We find that clonal populations that give rise to distant metastases are represented within the primary carcinoma, but these clones are genetically evolved from the original parental, non-metastatic clone. Thus, genetic heterogeneity of metastases reflects that within the primary carcinoma. A quantitative analysis of the timing of the genetic evolution of pancreatic cancer was performed, indicating at least a decade between the occurrence of the initiating mutation and the birth of the parental, non-metastatic founder cell. At least five more years are required for the acquisition of metastatic ability and patients die an average of two years thereafter. These data provide novel insights into the genetic features underlying pancreatic cancer progression and define a broad time window of opportunity for early detection to prevent deaths from metastatic disease.

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Distant metastasis occurs late during the genetic evolution of pancreatic cancer

SF-010-4 Distant metastasis occurs late during the genetic evolution of pancreatic cancer

Chemokines are proinflammatory cytokines that function in leukocyte chemoattraction and activation and have recently been shown to block the HIV-1 infection of target cells through interactions with chemokine receptors. In addition to their function in viral disease, chemokines have been implicated in the pathogenesis of atherosclerosis. Expression of the CC chemokine monocyte chemoattractant protein-1 (MCP-1) is upregulated in human atherosclerotic plaques, in arteries of primates on a hypercholesterolaemic diet; and in vascular endothelial and smooth muscle cells exposed to minimally modified lipids. To determine whether MCP-1 is causally related to the development of atherosclerosis, we generated mice that lack CCR2, the receptor for MCP-1 (ref. 7), and crossed them with apolipoprotein (apo) E-null mice which develop severe atherosclerosis. Here we show that the selective absence of CCR2 decreases lesion formation markedly in apoE-/- mice but has no effect on plasma lipid or lipoprotein concentrations. These data reveal a role for MCP-1 in the development of early atherosclerotic lesions and suggest that upregulation of this chemokine by minimally oxidized lipids is an important link between hyperlipidaemia and fatty streak formation.

Decreased lesion formation in CCR2 −/− mice reveals a role for chemokines in the initiation of atherosclerosis

We performed a detailed histological and immunohistological study on both fresh-frozen and paraffin-embedded tissue from full-thickness jejunal biopsy specimens taken from three patients with immunoproliferative small-intestinal disease (IPSID). In all three patients, the mucosal infiltrate consisted of "centrocyte-like" (CCL) cells forming lymphoepithelial lesions and plasma cells. In one patient, the mucosal infiltrate was strikingly follicular. Immunohistochemistry showed alpha 1 heavy chain, but no light chain, in the perinuclear space and cytoplasm of the CCL cells and in the plasma cells. In two patients, the plasma cells (but not the CCL cells) also contained alpha 2 heavy chain. In the case showing a follicular pattern, the extrafollicular CCL cells and most of the cells within the mucosal follicles expressed alpha 1 heavy chain, but a minor and variable population of cells expressed polytypic IgM. The dendritic reticulum cells stained for alpha 1 (but not alpha 2) heavy chain, mu chain, and both light chains. In all cases, the CCL cells did not stain for common acute lymphoblastic leukaemia antigen (CALLA); in the follicles, CALLA negative cells displaced a residual CALLA-positive population to the periphery and merged with the CALLA negative cells outside the follicles. These findings confirm the homology between IPSID and low-grade B-cell "Western" lymphomas arising in mucosa-associated lymphoid tissue; they suggest that the follicular pattern sometimes seen in these lymphomas is caused by selective colonization of reactive follicles by CCL tumor cells.

Stephen K. Price

Papers

Immunoproliferative small-intestinal disease. An immunohistochemical study.