Synthesis and regulation of acute phase plasma proteins in primary cultures of mouse hepatocytes.

Abstract

Adult mouse hepatocytes respond in vivo to experimentally induced acute inflammation by an increased synthesis and secretion of al-acid glycoprotein, haptoglobin, hemopexin, and serum amyloid A. Concurrently, the production of albumin and apolipoprotein A-1 is reduced. To define possible mediators of this response and to study their action in tissue culture, we established primary cultures of hepatocytes. Various hormones and factors that have been proposed to regulate the hepatic acute phase reaction were tested for their ability to modulate the expression of plasma proteins in these cells. Acute phase plasma and conditioned medium from activated monocytes influenced the production of most acute phase plasma proteins, and the regulation appears to occur at the level of functional mRNA. Purified hormones produced a significant anabolic response in only a few cases: dexamethasone was found to be effective in maintaining differentiated expression of the cells; and glucagon produced a specific inhibition of haptoglobin synthesis. When cells were treated with a combination of conditioned monocyte medium and dexamethasone, secretion of proteins was markedly reduced. The carbohydrate moieties of all plasma glycoproteins were incompletely modified, apparently as a result of decreased intracellular transport of newly synthesized plasma proteins. Although primary hepatocytes were not phenotypically stable in tissue culture, the cells nevertheless retained a broad response spectrum to exogenous signals. We propose this as a useful system to study the production of plasma proteins and thereby pinpoint the nature and activity of effectors mediating the hepatic acute phase reaction.

The occurrence of two types of hemopexin-like protein in medaka and differences in their affinity to heme

“…This result suggests that the goldfish response occurs through reactions with NF-IL6 and IL6-RE consensus sequences in the promoter region (Kikuchi et al, 1997). Human hemopexin plasma levels also increase during acute infections, suggesting that its biosynthesis is subject to control mechanisms responsible for the acute-phase reaction (Baumann et al, 1983;Poli and Cortese, 1989). Thus, goldfish Wap65 could be considered as an acute-phase protein, like hemopexins.…”

Modulation of hepatic acute phase gene expression by epidermal growth factor and src protein tyrosine kinases in murine and human hepatic cells

“…Mouse hepatocytes were prepared by in situ retrograde perfusion of the liver of 10-week-old C57BL/6J male mice with collagenase. 3,57 The parenchymal cells were collected by differential centrifugation and showed viability Ͼ90%. The cells were plated into culture dishes coated with collagen (Vitrogen 100; Collagen Biomaterials, Palo Alto, CA) (1 ϫ 10 5 cells/cm 2 ) in Dulbecco' s modified Eagle medium containing 10% fetal calf serum, 4.5 g/mL glucose, penicillin, streptomycin, and gentamicin.…”

“…1,2 However, the level of expression and cytokine regulation of individual APPs appears also to be additionally modulated by the action of endocrine hormones 3,4 and growth factors. [5][6][7] Few studies indicated a modest inhibitory effect of epidermal growth factor (EGF) on APPs in cultured hepatic cells.…”

When is Serum Albumin Worth Measuring?

“…Decreased albumin synthesis is an integral part of the acute phase response, probably resulting directly from the effect of macrorhage-derived mediators on albumin synthesis;" 26 Albumin, together with a number of other transport proteins, has thus been called a negative acute phase reactant. This aspect of decreased albumin synthesis occurring in inflammation together with transfer to the extravascular pool is a major factor in complicating the interpretation of albumin levels due to other mechanisms.…”