Mesenchymal stem cell-derived HGF attenuates radiation-induced senescence in salivary glands via compensatory proliferation.

BACKGROUND & AIM: Irradiation of the salivary glands during head and neck cancer treatment induces cellular senescence in response to DNA damage and contributes to radiation-induced hyposalivation by affecting the salivary gland stem/progenitor cell (SGSC) niche. Cellular senescence, such as that induced by radiation, is a state of cell-cycle arrest, accompanied by an altered pro-inflammatory secretome known as the senescence-associated secretory phenotype (SASP) with potential detrimental effects on the surrounding microenvironment. We hypothesized that the pro-regenerative properties of mesenchymal stem cells (MSCs) may attenuate cellular senescence post-irradiation. Therefore, here we evaluated the effects of adipose-derived MSCs (ADSCs) on the radiation-induced response of salivary gland organoids (SGOs). METHODS: Proteomic analyses to identify soluble mediators released by ADSCs co-cultured with SGOS revealed secretion of hepatocyte growth factor (HGF) in ADSCs, suggesting a possible role in the stem cell crosstalk. Next, the effect of recombinant HGF in the culture media of ex vivo grown salivary gland cells was tested in 2D monolayers and 3D organoid models. RESULTS: Treatment with HGF robustly increased salivary gland cell proliferation. Importantly, HGF supplementation post-irradiation enhanced proliferation at lower doses of radiation (0, 3, 7 Gy), but not at higher doses (10, 14 Gy) where most cells stained positive for senescence-associated beta-galactosidase. Furthermore, HGF had no effect on the senescence-associated secretory phenotype (SASP) of irradiated SGOs, suggesting there may be compensatory proliferation by cell-division competent cells instead of a reversal of cellular senescence after irradiation. CONCLUSION: ADSCs may positively influence radiation recovery through HGF secretion and can promote the ex vivo expansion of salivary gland stem/progenitor cells to enhance the effects of co-transplanted SGSC.

Comparative transcriptome analysis of inner blood-retinal barrier and blood-brain barrier in rats.

Although retinal microvessels (RMVs) and brain microvessels (BMVs) are closely related in their developmental and share similar blood-neural barriers, studies have reported markedly different responses to stressors such as diabetes. Therefore, we hypothesized that RMVs and BMVs will display substantial differences in gene expression levels even though they are of the same embryological origin. In this study, both RMVs and BMVs were mechanically isolated from rats. Full retinal and brain tissue samples (RT, BT) were collected for comparisons. Total RNA extracted from these four groups were processed on Affymetrix rat 2.0 microarray Chips. The transcriptional profiles of these tissues were then analyzed. In the present paper we looked at differentially expressed genes (DEGs) in RMVs (against RT) and BMVs (against BT) using a rather conservative threshold value of ≥ ± twofold change and a false discovery rate corrected for multiple comparisons (p < 0.05). In RMVs a total of 1559 DEGs were found, of which 1004 genes were higher expressed in RMVs than in RT. Moreover, 4244 DEGs between BMVs and BT were identified, of which 1956 genes were ≥ twofold enriched in BMVs. Using these DEGs, we comprehensively analyzed the actual expression levels and highlighted their involvement in critical functional structures in RMVs and BMVs, such as junctional complex, transporters and signaling pathways. Our work provides for the first time the transcriptional profiles of rat RMVs and BMVs. These results may help to understand why retina and brain microvasculature show different susceptibilities to stressors, and they might even provide new insight for pharmacological interventions.

Gender and gut microbiota composition determine hepatic bile acid, metabolic and inflammatory response to a single fast-food meal in healthy adults.

BACKGROUND & AIMS: Regular consumption of fast-food (FF) as a form of typical Western style diet is associated with obesity and the metabolic syndrome, including its hepatic manifestation nonalcoholic fatty liver disease. Currently, it remains unclear how intermittent excess FF consumption may influence liver metabolism. The study aimed to characterize the effects of a single FF binge on hepatic steatosis, inflammation, bile acid (BA), glucose and lipid metabolism. METHODS: Twenty-five healthy individuals received a FF meal and were asked to continue eating either for a two-hour period or until fully saturated. Serum levels of transaminases, fasting BA, lipid profile, glucose and cytokine levels as well as transient elastography and controlled attenuation parameter (CAP; to assess hepatic steatosis) were analyzed before (day 0) and the day after FF binge (day 1). Feces was collected prior and after the FF challenge for microbiota analysis. RESULTS: The FF meal induced a modest increase in CAP, which was accompanied by a robust increase of fasting serum BA levels. Surprisingly, levels of cholesterol and bilirubin were significantly lower after the FF meal. Differentiating individuals with a relevant delta BA (>1 µmol/l) increase vs. individuals without (delta BA ≤1 µmol/l), identified several gut microbiota, as well as gender to be associated with the BA increase and the observed alterations in liver function, metabolism and inflammation. CONCLUSION: A single binge FF meal leads to a robust increase in serum BA levels and alterations in parameters of liver injury and metabolism, indicating a novel metabolic aspect of the gut-liver axis.

[Hepatocyte oxidant stress and alcoholic liver disease]. / Estrés oxidativo hepatocitario y hepatopatía alcohólica.

Acute and chronic alcohol consumption increases the production of reactive oxygen species (ROS), and enhances lipid peroxidation of lipids, proteins, and DNA. The mechanism by which alcohol causes cell injury is still not clear but a major role for ROS and lipid peroxidation-end products is considered. Many pathways have been suggested to play a role on how ethanol induces a state of "oxidative stress", including redox-state changes, acetaldehyde production, damage to the mitochondria, membrane injury, apoptosis, ethanol-induced hypoxia, effects on the immune system and altered cytokine production, increased endotoxin levels and activation of Kupffer cells, mobilization of iron, changes in the antioxidant defense, particularly mitochondrial glutathione (GSH), one electron oxidation of ethanol to 1-hydroxy-ethyl radical, and induction of CYP2E1. These pathways are not exclusive of one another and it is likely that several, indeed many systems contribute to the ability of ethanol to induce a state of oxidative stress.

Estrés oxidativo hepatocitario y hepatopatía alcohólica / No disponible

El consumo agudo y crónico de alcohol aumenta la producciónde especies de oxígeno reactivas (EOR) y potencia la peroxidaciónde los lípidos, las proteínas y el ADN. El mecanismo por el que elalcohol produce lesión celular sigue sin estar claro, pero se piensaque las EOR y los productos de la peroxidación lipídica intervienende forma decisiva. Se ha señalado la intervención de muchasvías en la manera que tiene el etanol de inducir un estado de “estrésoxidativo”, incluidos los cambios de estado redox, la producciónde acetaldehído, el daño mitocondrial, las lesiones membranosas,la apoptosis, la hipoxia inducida por etanol, los efectossobre el sistema inmunitario y la producción alterada de citocinas,el aumento de los niveles de endotoxinas y de activación de las célulasde Kupffer, la movilización del hierro, la modulación de ladefensa antioxidante, especialmente del glutatión mitocondrial(GSH), la oxidación monoelectrónica del etanol a un radical 1-hidroxi-etilo y la inducción de la CYP2E1. Estas vías no son excluyentesentre sí y es probable que sean varios, ciertamente muchos,los sistemas que contribuyan a la capacidad que posee eletanol de inducir un estado de estrés oxidativo

Acute and chronic alcohol consumption increases the productionof reactive oxygen species (ROS), and enhances lipid peroxidationof lipids, proteins, and DNA. The mechanism by which alcoholcauses cell injury is still not clear but a major role for ROSand lipid peroxidation-end products is considered. Many pathwayshave been suggested to play a role on how ethanol induces a stateof “oxidative stress”, including redox-state changes, acetaldehydeproduction, damage to mitochondria, membrane injury, apoptosis,ethanol-induced hypoxia, effects on the immune system andaltered cytokine production, increased endotoxin levels and activationof Kupffer cells, mobilization of iron, modulation of the antioxidantdefense, particularly mitochondrial glutathione (GSH),one electron oxidation of ethanol to 1-hydroxy-ethyl radical, andinduction of CYP2E1. These pathways are not exclusive of oneanother and it is likely that several, indeed many, systems contributeto the ability of ethanol to induce a state of oxidative stress

Expression of apoptosis related proteins during malignant progression in chronic ulcerative colitis.

BACKGROUND: Chronic ulcerative colitis (CUC) is associated with increased risk of developing colon cancer through a dysplasia (intraepithelial neoplasia)-carcinoma sequence. AIMS: To investigate the expression of apoptosis and inflammatory related proteins in CUC. METHODS: The expression of proteins involved in apoptosis and inflammation (inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), Bcl-xl, Fas, and active caspase 3) was investigated and compared with that seen in sporadic colon carcinoma. RESULTS: COX-2 was negative in the epithelium of all samples. iNOS was clearly present in inflammatory areas in CUC epithelium, weakly expressed in dysplasia, and absent or weakly expressed in tumour cells. Bcl-xl was absent in CUC, increased in dysplasia, and highly expressed in most carcinomas. Fas expression was positive in the surface epithelium of CUC, dysplasia, and most tumour cells. Activated caspase 3 was weakly positive in all samples, indicating limited apoptosis. Compared with CUC associated carcinoma, iNOS was consistently expressed in sporadic colon carcinoma cells, whereas Bcl-xl was almost absent in these tumour cells and Fas was only weakly expressed. Activated caspase 3 was present in normal mucosal samples and some tumour cells. CONCLUSION: Apoptosis related proteins--particularly iNOS, Bcl-xl, and Fas-show a distinct pattern of expression in the CUC to carcinoma sequence, which differs from that seen in sporadic carcinoma, but bears a striking resemblance to that seen during neoplastic progression in Barrett's oesophagus. These results support a causal role for chronic inflammation in cancer development in CUC, and treatment of ulcerative colitis should aim to minimise inflammation.

Chronic inflammation, apoptosis and (pre-)malignant lesions in the gastro-intestinal tract.

Inflammatory conditions are characterized by activation of the transcription factor nuclear factor kappa B (NF-kappaB), resulting in the expression of NF-kappaB-regulated, inflammation-related genes, such as inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2). Expression of these genes contributes to the survival of cells. Indeed, exposure to pro-inflammatory cytokines in the absence of NF-kappaB activation leads to apoptosis.(1,2) Chronic inflammatory conditions are accompanied by constitutive activation of NF-kappaB and hence, to the continuous expression of pro-survival genes, as has been observed in chronic gastritis.(3) Although beneficial for the survival of cells during exposure to inflammatory stress, the continuous activation of NF-kappaB may also pose a risk: cells with a pro-survival phenotype may give rise to continuously proliferating cells and may thus be tumorigenic. Progression to a malignant phenotype of these cells will most likely involve additional changes in the expression of non-NF-kappaB regulated genes e.g. a shift in the balance of pro- and anti-apoptotic genes towards a more anti-apoptotic phenotype. Literature on inflammation-related genes and the apoptotic balance in pre-malignant and malignant conditions in the gastro-intestinal tract is still scarce and conflicting. In this review, we aim to give an overview of the existing literature and we will focus on inflammation- and apoptosis-related genes in the sequence of normal epithelium-inflamed epithelium-metaplasia-dysplasia-cancer in the gastrointestinal tract, in particular esophagus (Barrett's esophagus: BE), stomach (gastritis) and colon (inflammatory bowel disease: IBD).

Diffuse and intestinal type gastric carcinomas differ in their expression of apoptosis related proteins.

BACKGROUND: Gastric carcinomas can be divided into intestinal and diffuse types, with the last type having a worse prognosis. AIMS: To investigate whether specific patterns in the expression of apoptosis related proteins correlate with carcinoma type and/or prognosis METHODS: The expression of Fas, Bcl-2, Bax, Bcl-xl, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) was studied immunohistochemically and the extent of apoptosis and proliferation was investigated in 11 cases of intestinal type and in eight cases of diffuse type carcinoma. RESULTS: Fas was expressed in all intestinal type and in one diffuse type carcinoma. Bcl-xl was expressed in 10 of 11 intestinal type and in one of eight diffuse type carcinomas. Bcl-2 was expressed in lamina propria immune cells. iNOS was expressed in six of 11 intestinal type and in four of eight diffuse type carcinomas, and COX-2 was expressed in eight of 11 intestinal type and in six of eight diffuse type carcinomas. CONCLUSION: Fas and Bcl-xl expression can differentiate between intestinal type and diffuse type gastric carcinomas. No differences in apoptosis and proliferation between intestinal type and diffuse type gastric carcinomas were observed.

Blockade of NF-kappaB activation and donation of nitric oxide: new treatment options in inflammatory bowel disease?

BACKGROUND: Inhibition of NF-kappaB activation has been suggested as an anti-inflammatory treatment strategy in inflammatory bowel disease (IBD). However, NF-kappaB regulated genes like inducible nitric oxide synthase (iNOS) are also involved in cell survival mechanisms. METHODS: Review of the literature on NF-kappaB activation and iNOS induction in IBD. RESULTS: In patients with IBD the mucosal immune response is derailed. The nuclear transcription factor NF-kappaB is a key regulator of the inducible expression of many genes involved in immune and inflammatory responses in the gut. Stimuli like oxidative stress, cytokines (IL-1, IL-6, TNF-alpha), bacteria and viruses can release NF-kappaB from their inactive cytoplasmatic form to the nucleus. Drugs like corticosteroids, sulphasalazine, mesalazine and inhibitory cytokines (e.g. IL-10, IL-11) can prevent the activation of NF-kappaB. New, more potent and selective treatment strategies with anti-sense p65, proteasome inhibitors and viral IkappaBalpha expression vectors aim at the prevention of NF-kappaB activation in mucosal macrophages and T lymphocytes. However, NF-kappaB regulated genes are also involved in survival responses of epithelial cells. For example, inhibition of the NF-kappaB mediated induction of iNOS in epithelial cells could block important anti-apoptotic and anti-microbial survival mechanisms. Nitric oxide may also serve in a negative feedback loop to antagonize prolonged activation of NF-kappaB, thereby limiting chronic inflammation. CONCLUSION: Luminal donation of nitric oxide could block NF-kappaB activation. Selective inhibition of NF-kappaB activation in inflammatory cells could be a treatment option in IBD.

Expression of apoptosis-related proteins in Barrett's metaplasia-dysplasia-carcinoma sequence: a switch to a more resistant phenotype.

Barrett's esophagus, or columnar-lined esophagus (CLE), is a premalignant disorder in which the stratified squamous epithelium is replaced by metaplastic epithelium. To gain more insight into the process of carcinogenesis in CLE, we studied several factors involved in the apoptotic pathway in biopsies with gastric metaplasia (GM), intestinal metaplasia (IM), dysplasia, and/or adenocarcinoma. Immunohistochemistry was performed for Fas, Bcl-2, Bax, Bcl-xl, inducible nitric oxide synthase (iNOS), and cyclooxygenase 2 (COX-2). Fas staining was positive in the epithelium of all biopsies from patients with CLE but negative in normal gastric mucosa. Fas staining was positive in all tumor cells of the 8 cases containing adenocarcinoma. Bcl-2 was positive in lamina propria immune cells of all specimens. Bax staining was positive in the epithelium of all biopsies, including tumor cells. Bcl-xl was positive in dysplasia and tumor cells, but negative in 8 of 17 biopsies containing IM. iNOS was positive in 20 of 21 biopsies with IM and in 4 of 8 dysplasia biopsies. COX-2 was positive in 7 of 8 adenocarcinomas. We conclude that the apoptotic balance in the transformation from IM to adenocarcinoma switches to an antiapoptotic phenotype because of increased Bcl-xl expression and decreased Bax expression. Fas can be used as a marker for the differentiation of gastric mucosa and metaplasia in the esophagus. iNOS is highly positive in CLE-associated intestinal metaplasia. COX-2 is negative in nonmalignant CLE. Therefore, pharmacologic inhibition of COX-2 activity is unlikely to be effective in the preventing CLE-associated adenocarcinoma. There was no clear correlation between iNOS expression and activation of proapoptotic and antiapoptotic genes.

Increased expression of inducible nitric oxide synthase in circulating monocytes from patients with active inflammatory bowel disease.

BACKGROUND: Inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) synthesis are increased in epithelial cells and in tissue macrophages of the inflamed mucosa from patients with inflammatory bowel disease (IBD). Since tissue macrophages are derived from circulating monocytes, we studied iNOS expression in circulating monocytes and related this expression to disease activity. In view of the possible role of NO in monocyte function, we also studied iNOS expression in relation to markers of monocyte activation. METHODS: The expression of iNOS in circulating monocytes from 15 patients with active IBD, 6 patients who went into remission and 18 healthy controls was quantified by flow cytometry and correlated with surface markers (CD63, CD11b, HLA-DR) for monocyte activation. In addition, iNOS expression in circulating monocytes was assessed by Western blotting, immunocytochemistry and measurement of the NO metabolites nitrite and nitrate in plasma. RESULTS: The expression of iNOS in circulating monocytes and the percentage of iNOS-positive monocytes were increased in patients with active IBD compared to healthy controls (fluorescence index: 1.3 (0.1-6.3) versus 0.8 (0.0-1.8); P < 0.05: percentage of iNOS positive monocytes: 37.3 (1.0-77.0)% versus 5.3 (0.0-43.3)%; P<0.01). The six patients who went into remission all had a marked reduction of iNOS expression. iNOS expression was confirmed by Western blotting and immunocytochemistry. Plasma nitrite and nitrate levels were elevated in three patients with active 1BD. The surface markers for monocyte activation, CD63 and CD11b, were not elevated. HLA-DR expression was decreased on circulating monocytes from patients with active ulcerative colitis. CONCLUSIONS: iNOS is increased in circulating monocytes from patients with active IBD and this increased expression correlates with disease activity. Considering the decreased HLA-DR expression and absence of monocyte activation markers, NO produced by iNOS may have a function in suppressing systemic monocyte activation.

Nitric oxide inhibition enhances platelet aggregation in experimental anti-Thy-1 nephritis.

In the present paper we studied the role of nitric oxide radicals (NO) on platelet aggregation, fibrinogen deposition, superoxide formation, peroxynitrite formation, hemodynamics, and leukocyte migration in the Thy-1 model of glomerulonephritis. To first study the baseline kinetics of these parameters, groups of anti-Thy-1-treated rats were sacrificed at 1 h, 4 h, 24 h, 3 days, 7 days, and 14 days and compared to controls. Urinary protein excretion was significantly elevated in Thy-1 nephritis at 3 and 7 days. Glomerular macrophages, PMNs, and superoxide anion-positive cells were significantly increased in Thy-1 nephritis. Nitrotyrosine immunoreactivity was absent during the entire study period. Glomerular platelet aggregation was significantly increased in anti-Thy-1 injected rats at 1 h, 4 h, 24 h, and 3 days. Glomerular fibrinogen deposition was significantly elevated at all time points. To elucidate the role of NO in this process, additional groups of anti-Thy-1-injected rats were treated with the NOS inhibitor l-NAME and studied at 24 h. Urinary protein excretion was significantly higher in l-NAME treated Thy-1 rats compared to nontreated Thy-1 rats. Plasma and urine nitrite/nitrate levels were significantly lower in l-NAME-treated Thy-1 rats compared to nontreated Thy-1 rats. Compared to nontreated Thy-1 rats, there were no differences in intraglomerular leukocyte accumulation after treatment with l-NAME. In contrast, we observed a marked increase in platelet aggregation following l-NAME treatment. From these data we conclude that the inflammatory infiltrate in Thy-1 nephritis develops independent of NO radical production, whereas NO radicals prevent the accumulation of platelet aggregates.

Rat liver slices as a tool to study LPS-induced inflammatory response in the liver.

BACKGROUND/AIMS: Inflammation in the liver is a complex interaction between parenchymal and non-parenchymal cells, and therefore can not be studied in vitro in pure cultures of these cells. METHODS: We investigated whether Kupffer cells in the liver slice are still responsive to an inflammatory stimulus of lipopolysaccharide (LPS), and evoke an inflammatory response in the hepatocytes. RESULTS: TNFalpha, IL-1beta and IL-10 were significantly elevated in culture medium of LPS-stimulated rat liver slices. Nitric oxide (NO) production of LPS-treated slices gradually increased from 5 to 24 h (24 h: 81+/-5 microM vs. 14+/-2 microM in control P < 0.05), paralleled by inducible nitric oxide synthase (iNOS) in the hepatocytes, iNOS mRNA was induced after 3 h. NO production but not iNOS induction was significantly inhibited by NOS inhibitors S-methylisothiourea and N(G)-nitro-L-arginine methylester. Both pentoxifylline and dexamethasone inhibited TNFalpha and IL-1beta production, albeit to a different extent, iNOS induction and, as a result thereof, NO production. CONCLUSIONS: These results imply that non-parenchymal cells in liver slices are viable and can be activated by LPS. In addition, it is concluded that the upregulation of iNOS in hepatocytes by LPS is caused by cytokines produced by Kupffer cells because inhibition of TNFalpha and IL-1beta production attenuated iNOS induction.

Induction of Mdr1b expression by tumor necrosis factor-alpha in rat liver cells is independent of p53 but requires NF-kappaB signaling.

The multidrug resistance protein Mdr1b in rats is up-regulated during liver regeneration after partial hepatectomy or after endotoxin treatment. We hypothesize that up-regulation of Mdr1b in these models is TNF-alpha-dependent. The mechanism of Mdr1b activation by TNF-alpha is unknown as TNF-alpha can signal through various pathways, including NF-kappaB and p53, transcription factors for which binding sites in the Mdr1b promoter have been identified. We aimed to elucidate the mechanism of up-regulation of Mdr1b by TNF-alpha. We selectively used constructs expressing dominant negative Fas-associated death domain protein (FADD), TNF receptor associated factor-2 (TRAF2) or IkappaB to inhibit pathways downstream of the TNF receptor. Further, the proteasome inhibitor MG-132 was used, which prevents the breakdown of IkappaB. We show a critical role for NF-kappaB in activation of Mdr1b gene expression both in primary rat hepatocytes and in rat hepatoma H-4-II-E cells. Because p53 is up-regulated by TNF-alpha in an NF-kappaB-dependent manner and the Mdr1b promoter contains a p53 binding site, we used liver cells expressing a dominant negative p53 to show that TNF-alpha up-regulation of Mdr1b is independent of functional p53. Using transient transfection assays, we show that Mdr1b up-regulation correlates with activation of the promoter. Mutation of the NF-kappaB site in the Mdr1b promoter prevents its induction by TNF-alpha. In conclusion our results show that activation of the rat Mdr1b gene by TNF-alpha is a result of NF-kappaB signaling and independent of p53.

Renal expression of endothelial and inducible nitric oxide synthase, and formation of peroxynitrite-modified proteins and reactive oxygen species in Wegener's granulomatosis.

To investigate the role of nitric oxide (NO) in glomerular inflammation, the expression of endothelial NO synthase (eNOS) and inducible NOS (iNOS) was studied in conjunction with inflammatory cell influx, H2O2 production, and the formation of nitrotyrosines in renal biopsies from patients with Wegener's granulomatosis (WG). Renal cryostat sections from patients with WG (n=15) were stained by immunohistochemistry for eNOS, iNOS, endothelial cells (CD31), nitrotyrosines, polymorphonuclear cells (PMNs, CD15), and monocytes/macrophages (CD14, CD68). Production of H2O2 was identified by enzyme cytochemistry using diaminobenzidine. In control tissues, strong staining for eNOS was found in glomerular and interstitial tubular capillaries and cortical vessels. A significant reduction in eNOS expression was found in WG biopsies, which was associated with a reduction in CD31 expression. Expression of iNOS was found in infiltrating inflammatory cells, mainly located in the interstitium. H2O2-producing cells were detected in glomeruli and were abundantly present in the interstitium. Nitrotyrosine-positive cells, however, were almost exclusively found in the interstitium. It is concluded that renal inflammation in WG is associated with the induction of iNOS in inflammatory cells and the formation of nitrotyrosines. Expression of eNOS in glomerular capillaries is lost, most likely due to endothelial cell damage. These results suggest that decreased NO production by endothelial cells, in conjunction with increased NO production by iNOS-positive inflammatory cells, is involved in renal tissue injury in WG.

Involvement of reactive oxygen species and nitric oxide radicals in activation and proliferation of rat hepatic stellate cells.

BACKGROUND/AIMS: Reactive oxygen species (ROS) induce HSCs activation, proliferation and collagen gene expression in vitro. Nitric oxide (NO) represents a reactive molecule that reacts with ROS, yielding peroxynitrite. We thus verified the effect of NO on ROS-induced HSCs proliferation in vitro and correlated iNOS expression and ROS formation to HSCs activation in the early phase of liver injury leading to hepatic fibrosis in vivo. METHODS/RESULTS: HSCs were incubated with iron ascorbate (FeAsc) in vitro, which induced ROS production, ERK1/2 phosphorylation and increased cell proliferation. This effect was significantly reduced by the presence of the NO donor S-nitroso-N-acetylpenicillamine. Liver injury was induced in vivo in rats by dimethylnitrosamine administration. HSCs activation started 6 h after DMN administration and peaked at 1 week. ROS generation and neutrophil infiltration were evident for at least 48 h after DMN treatment, showing an identical distribution pattern. Only a few inflammatory cells expressed iNOS 6 h after DMN administration. CONCLUSIONS: we have shown that NO acts as a ROS scavenger in vitro, thus inhibiting HSCs proliferation. ROS production by infiltrating neutrophils occurs in the early phase of liver fibrosis and can represent a stimulus to HSCs activation in vivo. The reduced iNOS expression may account for the low NO levels and the inability to prevent the ROS-induced HSC activation in vivo.

Insulin-mediated increases in renal plasma flow are impaired in insulin-resistant normal subjects.

BACKGROUND: Impaired vasodilatation in skeletal muscle is a possible mechanism linking insulin resistance to blood pressure regulation. Increased renal vascular resistance has been demonstrated in the offspring of essential hypertensives. We assessed whether insulin-mediated renal vasodilatation is impaired in insulin-resistant normal subjects. DESIGN: In two groups of 10 insulin-resistant and 10 insulin-sensitive normal subjects, we compared the effects of sequential physiological and supraphysiological insulin dosages (50 and 150 mU kg(-1) h(-1)) on renal plasma flow (RPF) and leg blood flow using the euglycaemic clamp technique, 131I-labelled Hippuran clearances and venous occlusion plethysmography. Time-control experiments were performed in the same subjects. RESULTS: Whole-body glucose uptake amounted to 4.9 +/- 2.1 and 11.0 +/- 2.4 mg kg(-1) min(-1) in the insulin-resistant and to 12.7 +/- 2.3 and 17.4 +/- 2.6 mg kg(-1) min(-1) in the insulin-sensitive subjects during physiological and supraphysiological hyperinsulinaemia, respectively. RPF increased more in insulin-sensitive compared to insulin-resistant subjects during physiological hyperinsulinaemia (13.7 vs. 6.8%, P < 0.05). RPF increased to comparable levels during supraphysiological hyperinsulinaemia. Insulin-mediated changes in leg blood flow did not differ between groups. In the combined group, we found a positive correlation between insulin-mediated glucose uptake and changes in RPF during physiological hyperinsulinaemia (r = 0.57, P = 0.009), whereas insulin-mediated glucose uptake correlated with changes in leg blood flow during supraphysiological hyperinsulinaemia (r = 0.54. P = 0.017). CONCLUSIONS: Our results suggest that the sensitivities of the skeletal muscle and renal vascular bed differ for insulin's vasodilatory action. Insulin-mediated increases in RPF are impaired in insulin-resistant but otherwise normal subjects during physiological hyperinsulinaemia.

Negative inotropic effects of recombinant interleukin 2 in patients without left ventricular dysfunction.

UNLABELLED: Experimental data have shown that rIL2 has negative inotropic properties. This has not been investigated in humans with normal left ventricular function. Seventeen consecutive renal cell carcinoma patients who received rIL2 therapy because of dissemination were analyzed before and after treatment with a low dose of rIL2 subcutaneously. Left ventricular ejection fraction (echocardiography), heart rate variability parameters (24 h electrocardiography), and TNF alpha, IL1 beta and nitric oxide metabolites (NO(x)) were measured. LVEF decreased from 54+/-7 to 50+/-6% (mean+/-S.D.; P=0.012), with a concomitant increase in heart rate from 87+/-13 to 94+/-13 beats/min (P=0.031). All frequency domain HRV parameters decreased: the total power from 18.0+/-7.9 to 14.0+/-5.0 ms (P=0.001), the low frequency from 10.3+/-5.4 to 8. 3+/-3.4 ms (P=0.001), and the high frequency from 6.3+/-2.6 to 4. 5+/-1.1 ms (P=0.001). There was no measurable effect on TNF alpha, IL1 beta concentrations. Plasma levels of nitrate (NO(x)) increased from 22.8+/-14.4 to 41.8+/-26.6 micromol/l (P=0.007). CONCLUSIONS: A low dose of rIL2 has a negative inotropic effect that may be mediated by increased NO concentrations. It also reduces sympathetic activity as reflected in HRV parameters.

Procalcitonin behaves as a fast responding acute phase protein in vivo and in vitro.

OBJECTIVES: Procalcitonin (PCT) is a 13 kD protein of which plasma concentrations are strongly increased in inflammatory states. PCT concentrations are claimed to have a more powerful discriminatory value for bacterial infection than the acute phase proteins serum amyloid A (SAA) or C-reactive protein (CRP). The source of production and its mechanism of induction are unknown. We investigated the inducibility of PCT both in vivo and in vitro and compared the behavior of PCT with those of SAA and CRP. DESIGN: A prospective descriptive patient sample study and a controlled liver tissue culture study. SETTING: A university hospital. PATIENTS: Cancer patients who were treated with human tumor necrosis factor-alpha (rhTNF-alpha; 5 patients) or interleukin-6 (rhIL-6; 7 patients). MEASUREMENTS AND MAIN RESULTS: Serial serum samples were collected for analysis of concentrations of PCT, SAA, and CRP. In the TNF-alpha group, frequent sampling was performed on the first day to allow analysis of initial responses. In a human liver slice model, the release of PCT, SAA, and CRP was measured on induction with rhTNF-alpha and rhIL-6 for 24 hrs. We found that PCT displayed acute phase reactant behavior in vivo after administration of both rhTNF-alpha and rhIL-6. After rhTNF-alpha-administration, PCT reached half-maximal concentrations within 8 hrs, 12 hrs earlier than either SAA or CRP did. PCT, SAA, and CRP were produced in detectable quantities by liver tissue in vitro. PCT production by liver slices was enhanced after stimulation with rhTNF-alpha or rhIL-6; SAA and CRP concentrations were elevated after stimulation with rhTNF-alpha. CONCLUSIONS: We found that PCT and acute phase proteins such as CRP are induced by similar pathways. The liver appears to be a major source of PCT production. Thus, PCT may be considered an acute phase protein. The different kinetics of PCT, rather than a fundamentally different afferent pathway, may explain its putative diagnostic potential to discriminate bacterial infection from other causes of inflammation.