Following liver injury, hepatic stellate cells (HSC) undergo proliferation and migrate into damaged areas in response to chemotactic factors. HSC have been shown to regulate leukocyte trafficking by secreting monocyte chemotactic protein-1 (MCP-1), a chemokine that recruits monocytes and lymphocytes. In this study, we explored whether MCP-1 exerts biological actions on HSC. HSC were isolated from normal human livers, cultured on plastic, and studied in their myofibroblast-like phenotype, and three different cells lines were used. Chemotaxis was measured in modified Boyden chambers. The tissue response to injury involves the coordinated recruitment and activation of a number of cells in the attempt to repair the damage provoked by toxic, infectious, or immunological mechanisms. Inflammatory cells recruited at sites of damage are responsible for the scavenging of the necrotic cells, whereas myofibroblasts secrete extracellular matrix components and restore the integrity of the tissue. Within the liver, hepatic stellate cells (HSC) are responsible for this second part of the wound-healing response. 1,2 In normal liver, HSC fulfill the role of retinoid storage and metabolism, and their phenotype is referred to as quiescent. However, following injury, HSC undergo differentiation toward an activated phenotype characterized by proliferation and increased secretion of extracellular matrix components. This process is associated with enhanced or de novo expression of receptors for several soluble mediators, such as platelet-derived growth factor (PDGF), transforming growth factor-␤, or thrombin, which mediate the increase in cell proliferation and extracellular matrix production. [3][4][5] Therefore, HSC are the main cell type involved in the deposition of matrix that leads to fibrosis and cirrhosis. Another feature of cells involved in tissue repair is their ability to migrate into the damaged areas according to concentration gradients of chemotactic factors. 6 We have recently shown that HSC share this ability to respond to chemotactic factors such as PDGF. 7 Recent investigation has pointed out additional characteristics of the HSC that are relevant for the hepatic wound healing response. 2 HSC have been shown to express several molecules that are capable of regulating leukocyte trafficking, including chemokines. [8][9][10][11][12] These latter are a group of cytokines that exhibit chemoattractant properties for relatively specific groups of leukocytes. Four classes of chemokines have been recognized according to the position of conserved cysteine residues and differences in the spectrum of target cells. 13 The group of CXC chemokines includes a variety of factors, such as interleukin-8, which are mainly, but not exclusively, chemotactic for neutrophils. 13 Lymphotactin, a cytokine that specifically attracts lymphocytes, is the only known member of the C class of chemokines. 13 A novel cell-associated chemokine characterized by a CX3C motif and higher molecular weight has been recently identified. 14 Chemokines of the ...

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The serological hallmark of primary biliary cirrhosis (PBC) is the presence of pyruvate dehydrogenase complex E2 subunit (PDC-E2) antimitochondrial antibodies (AMAs). Anti-PDC-E2 antibodies cross-react specifically with mycobacterial hsp65, and we have demonstrated that the motif SxGDL[ILV]AE shared by PDC-E2 212-226 and hsp's is a cross-reactive target. Having found that this same motif is present only in ␤-galactosidase of Lactobacillus delbrueckii (BGAL LACDE), we hypothesized that this homology would also lead to crossreactivity. The mimics were tested via ELISA for reactivity and competitive cross-reactivity using sera from 100 AMA-positive and 23 AMA-negative PBC patients and 190 controls. An Escherichia coli (ECOLI) PDC-E2 mimic that has been pathogenetically linked to PBC but lacks this motif has been also tested. Anti-BGAL 266-280 LACDE antibodies were restricted to AMA-positive patients (54 of 95, 57%) and belonged to immunoglobulin (Ig) G3. Of the 190 controls, 22 (12%; P < .001) had anti-BGAL 266-280 antibodies, mainly of the IgG4 subclass. ECOLI PDC-E2 reactivity was virtually absent. BGAL 266-280 /PDC-E2 212-226 reactivity of the IgG3 isotype was found in 52 (52%) AMA-positive PBC patients but in only 1 of the controls (P < .001). LACDE BGAL 266-280 /PDC-E2 212-226 reactivity was due to crossreactivity as confirmed via competition ELISA. Antibody affinity for BGAL 266-280 was greater than for PDC-E2 mimics. Preincubation of a multireactive serum with BGAL 266-280 reduced the inhibition of enzymatic activity by 40%, while marginal effect (12%) or no effect (2%) was observed in human or ECOLI PDC-E2 mimics. In conclusion, IgG3 antibodies to BGAL LACDE cross-react with the major mitochondrial autoepitope and are characteristic of PBC.

The effectiveness of rituximab in hepatitis C virus (HCV)-related mixed cryoglobulinemia (MC) has been shown. However, the risk of an increase in viral replication limits its use in cirrhosis, a condition frequently observed in patients with MC. In this prospective study, 19 HCV-positive patients with MC and advanced liver disease, who were excluded from antiviral therapy, were treated with rituximab and followed for 6 months. MC symptoms included purpura, arthralgias, weakness, sensory-motor polyneuropathy, nephropathy, and leg ulcers.

1. Pentoxifylline (PTF) may act as a potential antifibrogenic agent by inhibiting cell proliferation and/or collagen deposition in cell type(s) responsible for the accumulation of extracellular matrix. The aim of the present study was to investigate at which level PTF may affect synthesis and degradation of type I collagen in human hepatic stellate cells (HSCs), a key source of connective tissue in fibrotic liver. 2. Procollagen type I synthesis and release were evaluated in cells maintained in serum free/insulin free medium for 48 h and then stimulated with transforming growth factor-beta 1 (TGF-beta 1) for different time periods in the presence or absence of PTF. TGF-beta 1 caused an upregulation of procollagen I mRNA levels with a peak increase after 3-6 h of stimulation. This effect was followed by an increase in both the cell associated and the extracellular levels of the corresponding protein, with a peak effect at 9-12 h after the addition of TGF-beta 1. Co-incubation with PTF slightly but consistently reduced basal as well as stimulated procollagen I mRNA levels, with negligible effects on the cell-associated expression of the corresponding protein. Conversely, PTF dose-dependently reduced procollagen type I levels detected in supernatants from unstimulated and stimulated cells. 3. Pulse-chase experiments employing L-[3H]-proline revealed that PTF was able to induce significantly the degradation of procollagen, mainly in the extracellular compartment. We next analysed the effect of PTF on the major pathway involved in type I collagen degradation. PTF did not affect the expression of metalloproteinase 1 (MMP-1) mRNA both in basal and stimulated conditions, whereas it markedly reduced the expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) mRNA. Accordingly incubation with PTF increased the levels of 'activated MMP-1' in cell supernatants in both basal and stimulated conditions. 4. These results suggest that the antifibrogenic action of PTF on human HSCs is mainly mediated by extracellular collagen degradation rather than by a reduction of collagen synthesis.

This evidence strongly suggests a critical role of dendritic cells and newly formed lymphatics in the pathogenesis and organization of the immune infiltrate that characterizes HCV-related chronic active hepatitis.