Activation of proteoglycan synthesis in injured liver--a brief review of molecular and cellular aspects

In the past years, considerable progress has been made with the molecular dissection of proteoglycans in normal and fibrotic human and rat liver. Three main types of glycosaminoglycans are found in liver, which, in order of decreasing concentration, are: heparan sulphate (more than 0.6 of total glycosaminoglycans), dermatan sulphate and chondroitin-4,6-sulphate isomers. Keratan sulphate has not been detected in rat and human liver. In fibrotic liver matrix, there is a more than 4-fold increase of the overall concentration of glycosaminoglycans, which is most pronounced for chondroitin sulphate and dermatan sulphate and less prominent for heparan sulphate. In fact, the latter glycosaminoglycan decreases fractionally. Stimulated synthesis rather than reduced breakdown in response to liver injury has been determined as the main mechanism of enhanced deposition. Fat-storing cells, a special type of nonparenchymal liver cells located in the subendothelial space of Disse, are the principal cellular source of hepatic preoteoglycans. In areas of necroinflammation, these cells transform into myofibroblasts, which express the genes for decorin, biglycan, syndecan and presumably other proteoglycans characterized by cloned core proteins. Proteoglycan synthesis in these cells is stimulated in a paracrine way mainly by TGF-beta, which is elaborated by activated Kupffer cells/macrophages and released from disintegrated thrombocytes. Furthermore, TGF-beta is also secreted by myofibroblasts, which are stimulated in an autocrine pathway by TGF-beta. Myofibroblasts can also activate resting (non-transformed) fat-storing cells in a paracrine way. In addition to TGF-beta, significant roles are also played by TNF-alpha, TGF-alpha/EGF, PDGF and FGF. Their effects depend on expression of the respective growth factor receptor that determines the stage of fat-storing cell transformation, on the interaction with other cytokines/growth factors, and on the extracellular matrix supporting these cells. Available data point to a potentially significant role which proteoglycans might fulfil in the regulation of cellular functions and in the maintenance of the supramolecular organization of the extracellular matrix in normal and diseased liver, in particular during the process of liver fibrogenesis.

[Fibronectin in human bile--a new parameter for diagnosis of malignant bile duct processes?--A pilot study]

In a pilot study it was investigated whether concentration of the glycoprotein fibronectin in the bile fluid can assist in differentiating between malignant and benign biliary tract obstructions. During endoscopic-retrograde cholangiography (ERC) and percutaneous transhepatic cholangiography (n = 3) native bile was aspirated in 29 patients. The concentration of fibronectin was determined by time resolved fluorescence immuno-assay. In 19 patients no biliary malignoma was present (choledocholithiasis: n = 9, normal finding: n = 10). Ten patients suffered from biliary or pancreatic cancer (infiltrating pancreatic cancer: n = 6; primary biliary tract cancer: n = 3, Klatskin tumor: n = 1). In the non malignant group a median fibronectin concentration of 12.0 ng/ml (lower-upper quartile 5-30 ng/ml) was found. A highly significantly elevated (p < 0.001, non parametric Kruskal-Wallis-test) median fibronectin concentration of 1675 ng/ml (lower-upper quartile 155-3430 ng/ml) could be determined in the malignant group. Our results show that in analogy to ascites, the concentration of biliary fibronectin is an important and easily determinable parameter in the differential diagnosis of benign und malignant diseases of the biliary tract.

The chemical morphology of extracellular matrix in experimental rat liver fibrosis resembles that of normal developing connective tissue

The time course of development of extracellular matrix (ECM) in experimentally induced fibrosis (thioacetamide administration followed for 12 weeks or bile duct ligation for 8 weeks) in adult rats was examined by light and electron microscopy, using Alcian blue or Cupromeronic blue staining for sulphated proteoglycans (PGs) in critical electrolyte concentration techniques. Proteodermatan sulphate (PDS) was regularly observed at the gap zone of the collagen fibrils. Morphometry of uranyl acetate-stained collagen fibrils, polarity of their banding patterns (a-e), statistics of d/e band occupancies by PDS, and lengths and thicknesses of PG filaments were quantified. Biochemical analyses showed that the ECM components collagen, hyaluronan, chondroitin and dermatan sulphates increased by 5-10 fold, roughly in parallel, as did heparan sulphate and DNA. Water and lipid contents also increased sharply. Thioacetamide treatment was much slower than bile duct ligation in producing fibrotic changes of equal severity. Sulphation of anionic glycosaminoglycans (AGAGs) decreased with increasing severity of fibrosis. Biochemical and ultrastructural methods correlated well. The large increase in dermatan sulphate was quantitatively as expected, given that it is collagen fibril surface-associated, and there was an increase of collagen content together with a decrease in fibril thicknesses. The increase in DNA reflected the marked increase in cell numbers in fibrotic livers. The chemical morphology of the new connective tissue closely resembled that in e.g. developing young tendon, in that fibrils were thinner, and AGAG levels were higher. The collagen fibrils were often disarranged, rather than ordered and parallel as in normal ECM. No other indication of abnormality in the new ECM was obtained.

Tumor necrosis factor alpha (TNF alpha) and transforming growth factor beta 1 (TGF beta 1) stimulate fibronectin synthesis and the transdifferentiation of fat-storing cells in the rat liver into myofibroblasts

Transforming growth factor-beta (TGF beta 1) and tumor necrosis factor alpha (TNF alpha) stimulate the transdifferentiation of fat-storing cells (FSC) in the rat liver into highly active and "synthetic" myofibroblast-like cells (MFBIC). This activation has been documented by differential-interference contrast and light microscopy using morphologic criteria (a reduction in the number and size of fat droplets, cell flattening and the development of long cytoplasmic extensions), by the loss of retinyl-palmitate (measured by HPLC) and by the enhanced expression of iso-alpha smooth muscle actin (demonstrated by immunofluorescence microscopy). Furthermore, while cell growth measured by the cell count and DNA content is slightly inhibited by TGF beta 1 (0.81 of the control), the combination of TGF beta 1 with TNF alpha stimulates cell proliferation to 1.44 times of the control. In addition the combination of TGF beta and TNF alpha potentiated the stimulatory effect on fibronectin synthesis (TGF beta alone: 1.4 times control; TNF alpha alone: 2.2 times control; TGF beta plus TNF alpha: 4.7 times control). The total protein synthesis was not altered by TGF beta or TNF alpha. In summary the results obtained identify TGF beta and TNF alpha as mediators stimulating key events in liver fibrogenesis (i.e. FSC proliferation, FSC transdifferentiation into MFBIC, and fibronectin synthesis).

Spatial and temporal patterns of gene expression for the proteoglycans biglycan and decorin and for transforming growth factor-beta 1 revealed by in situ hybridization during experimentally induced liver fibrosis in the rat

Expression of the proteoglycans biglycan and decorin and of transforming growth factor-beta 1 at various stages of liver fibrosis induced experimentally in rats by oral administration of thioacetamide was examined. Using in situ hybridization combined with immunocytochemical staining for cell-type characteristic markers, we demonstrate spatial and temporal expression patterns specific for each of the genes. Biglycan gene expression levels coincided tightly with the activity and extent of fibrosis, fat-storing cells and their transformed form, the myofibroblast-like cells, being the major contributors. Decorin messenger RNA was detectable only after the transition to the chronic inflammatory stage in nonparenchymal cells of periportal fields and, transiently, in the forming septa. In the cirrhotic stage, expression was detected solely in periportal fields with enhanced bile duct proliferation. Transforming growth factor-beta 1 expression was undetectable in normal liver. During the subacute inflammatory stage, a hepatocyte subpopulation expressing low levels of transforming growth factor-beta 1 occurred at the limiting plate. With the progression of fibrosis, transforming growth factor-beta 1 expression levels increased considerably but remained restricted to the mesenchymal cells of the fibrotic septa.

Synergism between hepatocytes and Kupffer cells in the activation of fat storing cells (perisinusoidal lipocytes)

This study concerns the cooperation of hepatocytes (PC) and Kupffer cells (KC) in the activation of rat liver fat storing cells (FSC) in culture. Various dilutions of conditioned media collected from early, serum-free cultures of both cell types were added separately and in combination, either simultaneously or sequentially, to early, non-confluent, primary cultures of FSC maintained under serum-reduced (0.5% fetal calf serum) conditions to determine the effects on proliferation (incorporations of [3H]thymidine and bromodeoxyuridine [BrdUrd], DNA-content, cell number), transformation and morphology (phase contrast microscopy, immunostainings of desmin and smooth muscle-alpha-actin), on the deposition of fibronectin and laminin and on the formation of 35S sulfated medium proteoglycans. Media of both cell types stimulated cell proliferation in a dose-dependent manner but combined PC- and KC-conditioned media was most potent and increased the incorporation of [3H]thymidine to 4-times above control values. The multiplication stimulatory effects visualized by labeling cell nuclei with BrdUrd and the increase of cell number per culture well were additive. The sequential addition of KC-conditioned medium to FSC preexposed to PC-conditioned medium increased the multiplication of FSC further and in an additive manner. The mitogenic activity of the PC-medium and the enhancing effect of KC-induced FSC proliferation was measured also when PC were damaged by incubation under anoxic conditions during generation of the conditioned medium. This observation indicates the release of the mitogen by membrane damage presumably from a cytoplasmic pool. The PC-medium did not induce either significant morphological changes or transformation of FSC towards myofibroblast-like cells. KC, however, generated transformation of FSC as indicated by more elongated cells with spindle-like cellular extensions and a reduction of retinoid droplets. Both these morphological effects were visible when PC and KC media were added simultaneously. Both media act synergistically on the deposition of fibronectin and laminin in FSC cultures and these components were found to be elevated 2.3 and 2.8-fold, respectively, if the cells were exposed to the combined media. Proteoglycan synthesis was also maximally enhanced if FSC were exposed to PC- and KC-media simultaneously. These findings suggest the involvement of (damaged) hepatocytes in the process of FSC activation. A model of sequential, spatial and time-dependent activation of FSC is suggested where cells in the immediate proximity of hepatocytes are primed to proliferate by a mitogenic signal released by membrane damage presumably from a cytoplasmic pool of injured hepatocytes into the pericellular environment. This non-inflammatory stimulation is followed by secretions of activated Kupffer cells and other inflammatory cell types which further enhance the activation of FSC.(ABSTRACT TRUNCATED AT 400 WORDS)

Laminin and aminoterminal propeptide of type III procollagen in seminal plasma from fertile and vasectomized men

The components of the extracellular matrix, laminin and aminoterminal propeptide of type III procollagen (PIIINP) were determined in seminal plasma of 50 patients with vasectomy and of 50 age-matched fertile patients. The concentration of laminin was highly significantly (P < 0.001) elevated in the fertile group as compared to the vasectomy group, whereas the concentrations of PIIINP were not significantly different between these two groups. Only weak correlations were observed between the concentrations of laminin and PIIINP. It is suggested that part of the laminin found in seminal plasma is derived from the ductus deferens, while the source of PIIINP is probably located at an upper part of the urogenital tract.

Hepatocyte-conditioned medium potentiates insulin-like growth factor (IGF) 1 and 2 stimulated DNA synthesis of cultured fat storing cells

IGF-1 and IGF-2 stimulate dose-dependently DNA synthesis of nonconfluent cultures of rat fat storing cells, a nonparenchymal type of liver cells pathogenetically involved in the generation of liver fibrosis. Maximum stimulation of [3H] thymidine incorporation of about 2.6-fold above control was reached with 100 ng/ml IGF-1 and 500 ng/ml IGF-2, respectively. The DNA synthesis promoting action of both IGF-1 and IGF-2 was most efficiently potentiated by hepatocyte-conditioned medium raising the stimulatory effect up to 21-fold above control cultures. Lysate of hepatocytes (up to 15 micrograms protein/ml) was not effective in potentiating the effect of IGF-1. IGF-1 is bound to free carrier protein(s) present in the medium of hepatocytes, but obviously absent in cell lysate. Three molecular weight fractions in the ranges of 67 kd, 35 kd, and 25 kd could be identified in the medium, which potentiate the growth-promoting effect of IGF-1. Applying Western ligand blot analysis, three molecular size classes of IGF-1 binding proteins in the conditioned media of rat hepatocytes were determined. The major binding protein had a M(r) of 28-34 kd, a minor portion was localized at M(r) 24 kd, whereas trace binding affinities were found at M(r) of about 95 kd. It is suggested that IGF-1, IGF-2 and the complex array of IGF-binding proteins secreted by hepatocytes might be involved in the paracrine regulation of growth of fat storing cells.

The response of rat liver perisinusoidal lipocytes to polypeptide growth regulator changes with their transdifferentiation into myofibroblast-like cells in culture

During culture on uncoated plastic wells rat liver perisinusoidal lipocytes change their differentiated phenotype (transdifferentiate) within 1-2 weeks and obtain a myofibroblast-like phenotype (myofibroblast-like cells). This transdifferentiation was documented by morphologic (loss of fat droplets, flat cell shape, cytoplasmic extensions, expression of iso-alpha smooth muscle actin) and biochemical criteria (loss of retinyl-palmitate, enhanced matrix synthesis). Whereas transforming growth factor alpha (TGF alpha) stimulated and transforming growth factor beta (TGF beta 1) inhibited the proliferation of perisinusoidal lipocytes (early culture) these cytokines did not effect the growth of the myofibroblast-like cells. Opposite effects were obtained with platelet-derived growth factor (PDGF) which stimulated the growth of myofibroblast-like cells only. Insulin-like growth factor (IGF1) was mitogenic in both perisinusoidal lipocytes and myofibroblast-like cells, respectively. Furthermore, whereas the expression of the mRNAs of decorin and biglycan was stimulated by TGF beta 1 in perisinusoidal lipocytes, the synthesis of these mRNAs was stimulated in myofibroblast-like cells predominantly by TGF alpha. Similar effects of TGF alpha and TGF beta 1 have been observed on the glycosaminoglycan-([35S]sulfate incorporation) and proteoglycan level ([3H]leucin incorporation into decorin and biglycan). Neither IGF1 and PDGF stimulated glycosaminoglycan synthesis in perisinusoidal lipocytes or in myofibroblast-like cells. The results demonstrate that the effects of the polypeptide growth regulators TGF alpha, TGF beta 1 and PDGF depend on the cell phenotype (stage of cell activation/transdifferentiation) and may be completely different in perisinusoidal lipocytes and its transformed counterpart the myofibroblast-like cells.

Differential expression of keratan sulphate proteoglycans fibromodulin, lumican and aggrecan in normal and fibrotic rat liver

In this study we investigated in rat liver the expression of genes coding for the core proteins of fibromodulin, lumican and aggrecan. By means of Northern analysis and in situ hybridization we present evidence for their differential transcription during liver fibrogenesis. Whereas no fibromodulin expression could been detected, both lumican and aggrecan transcripts were found displaying different time-courses of expression during the fibrogenic process. Based on studies performed in non-hepatic tissues, these proteoglycans are considered to have keratan sulphate glycosaminoglycan side chains. The expression of the respective core protein genes in liver is unexpected since published data have shown neither keratan sulphate nor its synthesis de novo in this tissue. The results also point to a putative role of aggrecan in the modulation of the inflammatory process in the liver.

Identification and partial characterization of a hepatocyte-derived factor promoting proliferation of cultured fat-storing cells (parasinusoidal lipocytes)

The molecular and cellular mechanisms of activation of fat-storing cells (Ito cells or parasinusoidal lipocytes), a prerequisite of the fibrogenic response of injured liver, were studied by analysis in vitro of some aspects of the intercellular communication between parenchymal liver cells and fat-storing cells. Conditioned medium harvested from early serum-free monolayer cultures of hepatocytes isolated from normal rat liver stimulated strongly, reproducibly and dose-dependently the proliferation of nonconfluent fat-storing cells maintained under serum-reduced conditions. During exposure of fat-storing cells for 48 hr to the conditioned medium, the incorporation of [3H]thymidine into DNA was stimulated four to six times over control values, the DNA content per culture well was elevated by 40% above control values and the immunocytochemical detection of bromodeoxyuridine-labeled cell nuclei was increased from 13% stained nuclei in controls to 70% stained nuclei in treated fat-storing cells. The mitogenic effects of hepatocyte-conditioned medium were similar to or even higher than those of 10% fetal calf serum. No mitoinhibitory activity could be detected in the hepatocyte-conditioned medium when arginase, as a potential inhibitor, was excluded. Rat skin fibroblasts could not be stimulated under conditions where the proliferation activity of fat-storing cells was greatly enhanced. The occurrence of the mitogenic activity in the medium is not dependent on de novo synthesis or secretion because the media of hepatocytes cultured under anoxic conditions in the presence of cycloheximide, brefeldin A or ethylenediaminetetraacetate were highly active in promoting fat-storing cell proliferation, although hepatocyte viability was greatly reduced under some of these conditions. A significant positive correlation (r = 0.95, p < 0.01) was found between lactate dehydrogenase activity and the mitogenic potency of the conditioned medium. The proliferation factor for fat-storing cells could also be demonstrated in the lysate of freshly isolated hepatocytes from normal liver. The stimulatory activity in the medium was partially enriched by a combination of gel permeation and anion exchange fast protein liquid chromatography and characterized as a protein with an apparent molecular weight of about 60 kD that is heat and pH sensitive but insensitive to reducing agents. It does not bind to immobilized heparin; nor does soluble heparin or proteinase inhibitor affect the mitogenic activity of the factor.(ABSTRACT TRUNCATED AT 400 WORDS)

Influence of reagent composition on atypical pseudocholinesterase activity measurement: comparison of a manual and an automated method and implications for routine

In determining activities of atypical pseudocholinesterase using a Hitachi 737 and a Cobas Bio analyser, respectively, we repeatedly found discrepancies between the enzyme activities measured by both instruments which were presumably due to differences in the reagent composition (Hitachi 737: Boehringer Mannheim Automated Analysis for BM/Hitachi Systems; Cobas Bio: Boehringer Mannheim Monotest). We consider the present results as a strong hint for manufacturers towards generally declaring all components of the chemical systems they produce and as a warning for users when interchanging apparently identically composed sets of reagents.

Biglycan and decorin gene expression in normal and fibrotic rat liver: cellular localization and regulatory factors

The expression of genes encoding the core proteins of the novel small chondroitin/dermatan sulfate proteoglycans decorin and biglycan was studied in the livers of normal rats and in liver tissue during fibrogenesis induced by prolonged bile-duct ligation and thioacetamide poisoning. The cell types responsible for the expression of these transcripts and some key regulatory factors were identified. Both biglycan and decorin messenger RNAs were detected in normal liver tissue. Their relative abundance increased strongly during liver fibrogenesis, reaching highest levels in cirrhotic tissue 8 wk after common bile-duct ligation and after 12 wk of peroral thioacetamide administration, respectively. Specific proteoglycan transcripts were almost absent in hepatocytes from normal and regenerating liver, and only trace amounts were observed in freshly isolated and cultured Kupffer cells. Fat-storing cells clearly expressed both biglycan and decorin transcripts. The steady-state levels of their messenger RNAs increased threefold (biglycan) and fourfold (decorin) during primary culture. Myofibroblastlike cells (transformed fat-storing cells after the second passage) contained dramatically reduced levels of decorin messenger RNA and also lower levels of biglycan messenger RNA compared with primary cultures. These changes of core protein messenger RNA expression were not reflected by the synthesis rates of medium proteoglycans labeled with 35S as Na2SO4, in particular that of medium chondroitin sulfate. Transiently acidified (but not native) conditioned media from Kupffer cells and myofibroblastlike cells and transforming growth factor-beta 1 enhanced the relative abundances of biglycan and decorin messenger RNAs up to five times in primary-cultured fat-storing cells. Biglycan and decorin in myofibroblastlike cells did not respond to these stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)

The concentration pattern of laminin, hyaluronan, and aminoterminal propeptide of type III procollagen in seminal fluid

The extracellular matrix components laminin, N-terminal propeptide of type III procollagen (PIIINP) and hyaluronan (HA) were determined in seminal fluids of 119 patients submitted for diagnosis of infertility. The concentrations of laminin and HA, but not those of PIIINP, were elevated in seminal fluid in comparison to their ranges of concentration in normal sera. Only weak correlations were observed between the concentrations of the three matrix components. The concentration of HA was negatively correlated with sperm count and ejaculate volume. Laminin was positively correlated with sperm count, the age of patients, and highly significantly with the concentrations of acrosin. A highly significant positive correlation was also found between PIIINP and fructose. By analysis of variance it could be shown that patients with azoospermia and oligozoospermia have significantly higher levels of HA than those with normospermia. Patients with terato- and asthenozoospermia showed no characteristic pattern of the matrix components.

Enhanced release of cytokines, interleukin-2 receptors, and neopterin after long-distance running

This study was designed to examine cytokine production in a group of 22 well-trained runners covering a distance of 20 km within 2 hr. After running, all participants displayed a marked granulocytosis for 7 hr. Plasma neopterin levels increased 1 hr after exercise for 24 hr. Except for interleukin-6 (IL-6), cytokines were not reliably detected in plasma but were present in urine. Already before exercise, cytokines were detected in the urine of runners when compared to sedentary controls. Directly after running, interferon-gamma and tumor necrosis factor-alpha were further elevated but rapidly declined to preexercise levels. Interleukin-1 beta and interleukin-6 increased at a slower rate after exercise but secretion into urine persisted longer until 12 and 7 hr, respectively. Interleukin-2 (IL-2) was not detected but soluble IL-2 receptors appeared in the urine directly after running. Enhanced cytokine levels were accompanied by an only low creatinin kinase increase, indicating little muscle damage. These data show that long-distance running elevates cytokine production which supports the concept that regular, but not excessive, physical exercise may be beneficial by maintaining a stimulated immune system.

Hepatic fibrogenesis: the puzzle of interacting cells, fibrogenic cytokines, regulatory loops, and extracellular matrix molecules

Fibrotic lesions affect a wide variety of organs but liver fibrosis is probably the most abundant form of organ fibrosis. Disturbances of the equilibrium between parenchyma and extracellular matrix (ECM) leading to a disproportionate increase and irregular deposition of newly formed connective tissue components (fibrosis) is a common and clinically most important sequelae of chronic active liver diseases. Significant progress has been made during the last years in the analysis of the structural composition of ECM in normal and fibrotic liver and in the dissection of the molecular and cellular mechanisms of exaggerated ECM-deposition in necroinflammatory areas using experimental models of hepatic fibrosis, isolated cells in mono- and coculture systems and the growing repertoire of molecular biological tools. Perisinusoidal, retinoid-storing cells (Ito cells, parasinusoidal lipocytes) transform under inflammatory stimuli to myofibroblast-like cells being qualitatively and quantitatively the most important connective tissue producing cell type in human and animal liver. Its activation and transformation is mediated by paracrine and autocrine loops involving transforming growth factor (TGF) beta as the main fibrogenic mediator secreted by activated liver macrophages, possibly also by endothelial cells and liberated by disintegrated thrombocytes. In advanced stages of retinoid-storing cell transformation additional growth factors like platelet derived growth factor (PDGF) become important indicating a sequential action of cytokines and fibrogenic mediators during the fibrogenic process. The molecular and cellular interactions in the course of liver fibrogenesis have gained model character for a number of other organ fibrotic processes, wound repair, and atherogenesis included.(ABSTRACT TRUNCATED AT 250 WORDS)

Higher levels of serum aminoterminal type III procollagen peptide, and laminin in alcoholic than in nonalcoholic cirrhosis of equal severity

In vitro models have shown that metabolites of ethanol (acetaldehyde and lactate) stimulate collagen synthesis, thereby, suggesting that they may be important as fibrogenic mediators. The relevance of these findings for fibrogenesis in the human liver in vivo, however, has not as yet been demonstrated. Serum markers for collagen (PIIINP, using radioimmunoassays employing polyclonal antibodies and Fab-fragments (PIIINP-Fab), respectively) and basement membrane (laminin) metabolism were therefore investigated in 25 alcoholic cirrhotics (Pugh-Score: 6.7 +/- 1.9 S.D.) and in 19 comparable nonalcoholic cirrhotics (Pugh-Score: 6.3 +/- 1.5, n.s.) with only slight evidence for inflammation: GOT 28 +/- 22 vs. 24 +/- 21 U/l; GPT 24 +/- 23 vs. 31 +/- 28 U/l; gamma-globulins 24 +/- 8 vs. 22 +/- 5%, respectively (all n.s.). Severity of the disease was assessed by quantitative liver function tests. Levels of PIIINP, PIIINP-Fab and laminin measured by RIA were 21 +/- 19 micrograms/l, 90 +/- 42 micrograms/l and 2.5 +/- 0.8 U/ml in alcoholic cirrhosis and 10 +/- 6 micrograms/l, 61 +/- 10 micrograms/l and 1.9 +/- 0.4 U/ml in nonalcoholic cirrhosis, respectively (all p less than 0.01). Differences on PIIINP and PIIINP-Fab remained significant even after accurate matching for galactose elimination capacity, aminopyrine breath test and hepatic sorbitol clearance. Laminin levels were higher in alcoholic cirrhosis only after matching for the hepatic sorbitol clearance (p less than 0.01). The higher levels of serum markers for collagen and basement membrane metabolism in alcoholic vs. nonalcoholic patients with cirrhosis at equal severity of the disease and with only minimal signs of inflammation may be the clinical reflection of a specific fibrogenic effect of ethanol metabolites.

Activation of rat liver perisinusoidal lipocytes by transforming growth factors derived from myofibroblastlike cells. A potential mechanism of self perpetuation in liver fibrogenesis

Rat liver perisinusoidal lipocytes (PL) cultured on uncoated plastic transform spontaneously within 6-10 d to myofibroblastlike cells (MFBlC). Parallel to the transformation the TGF alpha- and TGF beta 1-mRNA expression increased and was highest in MFBlC. Competitive radioligand binding assays demonstrated that in contrast to untransformed PL the MFBlC synthesize and secrete transforming growth factor (TGF)-alpha (15 fmol/cell per 24 h) and predominantly the latent form of TGF beta 1 (0.2 fmol/cell per 24 h). Medium conditioned by MFBlC (MFBcM) significantly stimulated PL proliferation with little effect on PL proteoglycan synthesis. By transient acidification of the MFBcM, known to activate the latent form of TGF beta 1, the stimulatory effect on PL proteoglycan synthesis was enhanced and furthermore PL transformation (measured by expression of iso-alpha smooth muscle actin and loss of retinylpalmitate) was accelerated. Preincubation of this medium with neutralizing antibodies to TGF beta resulted in (a) the growth inhibitory effect was converted to a growth stimulation and (b) the stimulatory effect on proteoglycan synthesis was abolished. In summary our data indicate that progressive activation of PL on plastic (transformation to MFBlC) leads to an enhanced expression of the TGF alpha- and TGF beta 1-mRNAs and secretion of the corresponding proteins. Medium conditioned by MFBIC stimulates proliferation, transformation, and PG synthesis of untransformed PL. These mechanisms are suggested to be relevant in self perpetuation of liver fibrogenesis.

The prognostic value of extracellular matrix component concentrations in serum during treatment of adult respiratory distress syndrome with extracorporeal CO2 removal

The time-dependent concentrations of hyaluronan, aminoterminal propeptide of type III procollagen, and laminin were determined in sera of 16 patients with severe adult respiratory distress syndrome during treatment with an extracorporeal CO2 removal device. Patients were classified according to lung parameters as responders (n = 10) and non-responders (n = 6) to extracorporeal CO2 removal. At the beginning of treatment strongly elevated serum concentrations of all studied extracellular matrix components were found. During the first 6-11 days of treatment the concentrations of aminoterminal propeptide of type III procollagen and hyaluronan increased further in non-responders but decreased in the majority of responders, while laminin decreased in both groups. No significant correlations were found between the serum concentrations of connective tissue components and the parameters of lung function. By non-parametric analysis of variance, significant differences between responders and non-responders according to treatment time could be established. By analysing the time course of the serum concentrations of hyaluronan and aminoterminal propeptide of type III procollagen, a total differentiation between responders and nonresponders was made possible by the trends of these analytes as early as three days after the start of treatment. The determination of aminoterminal propeptide of type III procollagen and hyaluronan in serum of patients with adult respiratory distress syndrome might therefore have prognostic significance in extracorporeal CO2 removal.

Questioning the reliability of p-nitrophenyl-beta-D-xyloside as probe to study the metabolic effects of abrogated proteoglycan synthesis in cultured cells

p-Nitrophenyl-beta-D-xylopyranoside (PNP-Xyl) and similar aglycone derivatives of xylosides are proposed selective inhibitors of proteoglycan synthesis which are used frequently to analyse the metabolic and cellular effects of abrogated proteoglycan formation and, hence, tentatively, the functions of these complex molecules. Using rat liver fat storing cell (FSC) cultures as a model, the possibility was tested that p-nitrophenol (PNP), which might be generated by the enzymatic hydrolysis of PNP-Xyl, could mediate some of those effects ascribed previously to PNP-Xyl induced inhibition of proteoglycan synthesis. PNP-Xyl and PNP inhibited dose-dependently the proliferation of FSC reaching 50% inhibition at about 1.9 and 0.6 mM, respectively. The inhibition of proliferation was not accompanied by signs of toxic cell damage and was fully reversible after withdrawal of the drugs. After an initial 4-fold stimulation of the formation of [35S]sulfate-labeled medium glycosaminoglycans (GAG) by PNP-Xyl at 0.1 mM, higher concentrations of this compound (about 0.5 mM) but also PNP decreased progressively the synthesis of sulfated medium GAG. A proliferation inhibiting concentration of PNP (0.75 mM) induced disorganization and reduced the expression of desmin- and smooth muscle iso-alpha-actin containing cytoskeletal filaments. These effects were similar to related effects reported previously for PNP-Xyl. Incubation of FSC with 5 mM PNP-Xyl resulted in a time-dependent increase of PNP in medium and cells; intracellular concentrations of PNP were reached sufficient to inhibit the mitotic activity of FSC. In lysates of FSC 0.65 nmol PNP/hr/micrograms DNA or 1 x 10(5) cells were generated from PNP-Xyl (5 mM) added as substrate. Exemplified with PNP-Xyl-treated FSC cultures, the results suggest for other cell and organ systems also that PNP, which is enzymatically cleaved from PNP-Xyl, might mediate at least some of the major effects attributed previously to the inhibition of proteoglycan synthesis. The aglycone may interfere with the effects of PNP-Xyl on proteoglycan metabolism and, therefore, could complicate in an unpredictable manner the interpretation of metabolic inhibitory studies using these compounds.

Practical implications of coexistent different technologies in clinical chemical laboratories. Solid phase chemistry and conventional analysis

If different analytical methods are alternatively used for the determination of the same analyte, basic differences in test methodology can give rise to an increased number of deviating results. Such coexistence of methods might be necessary, for example, during a transition phase while upgrading to new technologies. We have exemplarily investigated this topic for the comparison of solid phase chemistry ("dry chemistry") versus conventional methods ("wet chemistry"). The Kodak Ektachem 700XR clinical chemistry analyser was compared with the Hitachi 737 analyser from Boehringer Mannheim using 18 clinical chemical analytes and specimens submitted for routine analysis. Before the start of the evaluation, the Ektachem 700XR was adjusted ("calibrated") by the manufacturer for optimal agreement with the Hitachi 737. Satisfactory agreement was obtained for most investigated analytes as judged by correlation coefficients and three commonly applied regression methods (linear regression, principal components, and Passing/Bablok method). For some analytes, however, strongly deviating results were often obtained. Quality control-derived limits (maximum acceptable inaccuracy) and data from biological variation (critical differences) were used for the assessment of the inter-instrument bias for diagnosis and patient monitoring, respectively. For enzymes, 0% (amylase) to 22% (creatine kinase) of all pathologic results differed by more than the maximum acceptable analytical inaccuracy (21%-27%) of these analytes. If more stringent limits derived from biological variation were used, 24% (creatine kinase)--62% (aspartate aminotransferase) of all differences between paired measurements exceeded the critical difference for enzymes. Deviations greater than the critical differences were also marked for serum concentrations of sodium, calcium, and creatinine.(ABSTRACT TRUNCATED AT 250 WORDS)

Proliferation and transformation of cultured liver fat-storing cells (perisinusoidal lipocytes) under conditions of beta-D-xyloside-induced abrogation of proteoglycan synthesis

Fat-storing cells (perisinusoidal lipocytes, Ito cells) are the major connective tissue-producing cell type in liver. In areas of necroinflammation the cells proliferate and transform into desmin and smooth muscle alpha-actin-positive myofibroblast-like cells which synthesize a broad spectrum of significant amounts of collagens, proteoglycans, and matrix glycoproteins. Available data suggest a central role for these cells in the pathogenesis of fibrosis. Beta-D-Xyloside, an artificial initiation site for galactose-linked glycosaminoglycans, thereby uncoupling the synthesis of core protein and GAG, was used as a probe to study main cellular functions under conditions of abrogated proteoglycan synthesis. The exposure for 48 hr of fat-storing cells to p-nitrophenyl beta-D-xyloside (PNP-Xyl) increased dose-dependently the synthesis of [35S]sulfate-labeled medium GAG. Maximum stimulation of fivefold above normal was reached at 1.0 mM PNP-Xyl. Higher concentrations of PNP-Xyl progressively decreased the stimulatory effect on GAG synthesis. The relative composition of GAG in medium (60% chondroitin sulfate, 34% dermatan sulfate), at the cell surface, and intracellularly (mainly heparan sulfate) was not changed significantly by PNP-Xyl. The amounts of intracellular and cell surface-bound GAG were reduced by 40 and 30%, respectively, by PNP-Xyl leading to a depletion of heparan sulfate at the cell surface. Pulse-chase experiments revealed that xyloside-initiated GAG were secreted immediately after synthesis into the medium. GAG synthesized in the presence of 1 and 5 mM PNP-Xyl were free of core protein, and the molecular size of the GAG chains was smaller than that of GAG obtained from beta-eliminated proteoglycans synthesized in control cultures. At concentrations above 3 mM PNP-Xyl generated a dose-dependent inhibition of cell proliferation, which was at any stage of culture fully reversible upon removal of the drug. Viability and general protein synthesis were not reduced, but fat-storing cell transformation and deposition of matrix glycoproteins were retarded. Only a very small fraction of drug-treated cells (5 mM PNP-Xyl) did express on the 11th culture day smooth muscle iso-alpha-actin- and desmin-containing cytoskeletal filaments, which are important indicators of transformation into myofibroblast-like cells. Furthermore, the synthesis of hyaluronan and the expression of immunostained fibronectin, laminin, and tenascin were reduced in cultures exposed to 5 mM PNP-Xyl. The described cellular functions were not affected by exposure of fat-storing cells to p-nitrophenyl beta-D-galactoside.(ABSTRACT TRUNCATED AT 400 WORDS)