Cyclosporine and liver regeneration studied by in vivo 31P nuclear magnetic resonance spectroscopy

The mitochondrial death pathway: a promising therapeutic target in diseases

The mitochondrial pathway to apoptosis is a major pathway of physiological cell death in vertebrates. The mitochondrial cell death pathway commences when apoptogenic molecules present between the outer and inner mitochondrial membranes are released into the cytosol by mitochondrial outer membrane permeabilization (MOMP). BCL-2 family members are the sentinels of MOMP in the mitochondrial apoptotic pathway; the pro-apoptotic B cell lymphoma (BCL)-2 proteins, BCL-2 associated x protein and BCL-2 antagonist killer 1 induce MOMP whereas the anti-apoptotic BCL-2 proteins, BCL-2, BCL-x_l and myeloid cell leukaemia 1 prevent MOMP from occurring. The release of pro-apoptotic factors such as cytochrome c from mitochondria leads to formation of a multimeric complex known as the apoptosome and initiates caspase activation cascades. These pathways are important for normal cellular homeostasis and play key roles in the pathogenesis of many diseases. In this review, we will provide a brief overview of the mitochondrial death pathway and focus on a selection of diseases whose pathogenesis involves the mitochondrial death pathway and we will examine the various pharmacological approaches that target this pathway.

Functional modification of CD11c+ liver dendritic cells during liver regeneration after partial hepatectomy in mice

Local immunosuppression within the liver and sex steroid changes, in both blood and tissue during liver regeneration, are well-recognized events. Dendritic cells (DC) play pivotal roles in the induction and regulation of immune responses. Their numbers are expanded markedly in vivo by fms-like tyrosine kinase 3 ligand (Flt3L) administration, without modification of their maturation state. Recent evidence suggests that estrogen can modulate DC function and promote a Th2-type immune response. Few data are available concerning the role of DC in liver regeneration. After 75% partial hepatectomy (PH) in male C57BL/6 mice, CD11c+ liver (L)DC increased significantly within 6 hours and maintained an immature phenotype. Numbers returned to pre-hepatectomy levels by 24 hours. The expanded LDC population showed increased IL-10 and reduced IFN-gamma gene transcription. Using these DC compared with control LDC as T cell stimulators in 72-hour mixed leukocyte cultures, IL-10 production was enhanced and IFN-gamma production reduced. LDC isolated 6 hours after 75% PH exhibited enhanced estrogen receptor (ER) expression, concomitant with increased serum estrogen levels. By contrast, spleen (S)DC isolated before and after PH showed no significant changes in their function (maturation state, T cell stimulatory activity, cytokine production, and ER expression). Increased liver regeneration (more than 50%) was observed 48 hours after 40% PH in the Flt3L-pretreated compared with the PBS group. In conclusion, interstitial LDC may play a key role in local immune regulation during liver regeneration, possibly linking estrogen-mediated immune modulation and hepatocyte proliferation.

Quantitative P-31 MR spectroscopy of the liver in alcoholic cirrhosis

To determine the cause of reduced urea synthesis in cirrhosis, absolute concentrations of phosphorus metabolites in the human liver have been measured in vivo with magnetic resonance (MR) spectroscopy. One-dimensional chemical shift imaging was used to obtain phosphorus-31 spectra from five healthy volunteers and five patients with alcoholic cirrhosis. A reference standard included in all studies enabled the calculation of absolute concentrations. In contrast to hepatic metabolite ratios, absolute concentrations reveal that in the cirrhotic patients, concentrations of adenosine triphosphate (ATP) were significantly reduced and concentrations of phosphomonoesters slightly reduced. Intracellular pH was unchanged. Histologic evidence suggests that the amount of ATP per cell was unchanged and could not account for the reduced urea production. Instead, urea synthesis depends on the functional liver cell mass, which was reduced by 31% in alcoholic cirrhosis. Quantitative in vivo P-31 MR spectroscopy of liver has potential clinical applications and can supplement the more generally used P-31 metabolite ratios.