Diabetes worsening of hepatitis C cirrhosis: are alterations in monocytic tissue factor (CD 142) is the cause?

BACKGROUND & AIM. The mechanisms by which type 2 diabetes mellitus (T2DM) worsen liver function are not yet established. Tissue factor (TF) is a protein that participates in hemostatic, immune and inflammatory processes. To test the hypothesis that T2DM contributes to clinical outcome through changes of TF expression on monocytes and to investigate the association between antidiabetic therapies and monocytic TF expression in HCV-related cirrhotic patients with T2DM. MATERIAL AND METHODS. In HCV-related cirrhotic patients (139 diabetics and 130 non diabetics) compared with 100 matched diabetic patients and 100 Controls; the flowcytometric analysis of CD14, TF (CD142), costimulatory molecules; CD86 and HLA-DR on monocytes were determined. RESULTS. Cirrhotic patients with T2DM have increase in the expression of monocytic TF and CD86 in comparison with cirrhotic non-diabetic, diabetic and healthy control; which increase significantly with increase of the stage of the Child-Pugh score. The expression of HLA-DR is significantly lower in cirrhotic patients than controls. Albeit, there were no significant differences in the HbA1c levels between the three groups, the use of exogenous insulin were associated with significantly higher monocytic TF expression than those in sulphonylurea and insulin sensitizer group (P < 0.03 for both). CONCLUSIONS. The monocytic TF as a significant link connecting inflammatory and immunological phenomena can partially explain a lot of events in HCV- related cirrhotic patients with T2DM. The use of exogenous insulin was associated with significantly higher TF expression than sulphonylurea and insulin sensitizer. Future target therapy against TF may be beneficial for T2DM cirrhotic patients.

Transcriptional regulation of IL-6 in bile duct epithelia by extracellular ATP.

The inflammatory cytokine IL-6 is essential for cell survival after liver injury. Bile duct epithelia (BDE) markedly upregulate IL-6 release after liver injury, but the mechanisms regulating this have not been defined. Purinergic signals induce multiple potent downstream effects in BDE, so the goals of this study were to determine whether extracellular ATP regulates BDE IL-6 transcription and to identify the molecular mechanisms regulating this process. Effects of extracellular nucleotides on IL-6 transcription in primary rat bile duct epithelia were assessed. The relative effects of cAMP and cytosolic calcium were determined by use of agonists and antagonists. The role of the cAMP response element (CRE) was determined by site-directed mutagenesis. We found that ATP potently upregulated IL-6 mRNA, and that the pharmacological profile for IL-6 upregulation was most consistent with the newly identified P2Y11 receptor. This occurred in a cAMP-dependent and calcium-dependent fashion. The effect of cAMP and calcium agonists on IL-6 promoter activity was synergistic, and mutation of the IL-6 CRE blocked upregulation by ATP. Taken together, these data show that extracellular ATP acts through a mechanism involving a rat P2Y receptor functionally related to the P2Y11 receptor, cAMP, and calcium signals and that the IL-6 promoter CRE to upregulate transcription of IL-6 in BDE. Since IL-6 has such critical importance in the liver, it is likely that this pathway is of great relevance to the understanding of hepatic response to injury.

Intracellular calcium signals regulate growth of hepatic stellate cells via specific effects on cell cycle progression.

Hepatic stellate cells (HSC) are important mediators of liver fibrosis. Hormones linked to downstream intracellular Ca(2+) signals upregulate HSC proliferation, but the mechanisms by which this occurs are unknown. Nuclear and cytosolic Ca(2+) signals may have distinct effects on cell proliferation, so we expressed plasmid and adenoviral constructs containing the Ca(2+) chelator parvalbumin (PV) linked to either a nuclear localization sequence (NLS) or a nuclear export sequence (NES) to block Ca(2+) signals in distinct compartments within LX-2 immortalized human HSC and primary rat HSC. PV-NLS and PV-NES constructs each targeted to the appropriate intracellular compartment and blocked Ca(2+) signals only within that compartment. PV-NLS and PV-NES constructs inhibited HSC growth. Furthermore, blockade of nuclear or cytosolic Ca(2+) signals arrested growth at the G2/mitosis (G2/M) cell-cycle interface and prevented the onset of mitosis. Blockade of nuclear or cytosolic Ca(2+) signals downregulated phosphorylation of the G2/M checkpoint phosphatase Cdc25C. Inhibition of calmodulin kinase II (CaMK II) had identical effects on LX-2 growth and Cdc25C phosphorylation. We propose that nuclear and cytosolic Ca(2+) are critical signals that regulate HSC growth at the G2/M checkpoint via CaMK II-mediated regulation of Cdc25C phosphorylation. These data provide a new logical target for pharmacological therapy directed against progression of liver fibrosis.