Endoplasmic reticulum stress induces inverse regulations of major functions in portal myofibroblasts during liver fibrosis progression.

Portal myofibroblasts (PMF) form a sub-population of highly proliferative and proangiogenic liver myofibroblasts that derive from portal mesenchymal progenitors. Endoplasmic reticulum (ER) stress was previously shown to modulate fibrogenesis, notably in the liver. Our aim was to determine if ER stress occurred in PMF and affected their functions. PMF were obtained after their expansion in vivo from bile duct-ligated (BDL) rats and referred to as BDL PMF. Compared to standard PMF obtained from normal rats, BDL PMF were more myofibroblastic, as assessed by higher alpha-smooth muscle actin expression and collagen 1 production. Their proangiogenic properties were also higher, whereas their proliferative and migratory capacities were lower. CHOP expression was detected in the liver of BDL rats, at the leading edge of portal fibrosis where PMF accumulate. BDL PMF displayed ER dilatation and an overexpression of the PERK pathway downstream targets, Chop, Gadd34 and Trb3, in comparison with standard PMF. In vitro, the induction of ER stress by tunicamycin in standard PMF, caused a decrease in their proliferative and migratory activity, and an increase in their proangiogenic activity, without affecting their myofibroblastic differentiation. Conversely, the treatment of BDL PMF with the PERK inhibitor GSK2656157 reduced ER stress, which caused a decrease in their angiogenic properties, and restored their proliferative and migratory capacity. In conclusion, PMF develop ER stress as they expand with the progression of fibrosis, which further increases their proangiogenic activity, but also inhibits their proliferation and migration. This phenotypic switch may restrict PMF expansion while they support angiogenesis.

Protective effects of hydrogen sulfide on portal hypertensive vasculopathy in rabbits by activating AKT-NF-κB pathway.

The role of hydrogen sulfide (H2S) in portal hypertension (PH)-induced esophagus-gastric junction vascular lesions in rabbits was observed. The rabbit PH models were established. The animals were randomly divided into the following groups: normal, PH, PH+sodium hydrosulfide (PH+S), PH+propargylglycine (PH+PPG). The plasma H2S levels, apoptosis of esophageal-gastric junction vascular smooth muscle cells, and the expression of nuclear transcription factor-κB (NF-κB), p-AKT, IκBa and Bcl-2 were detected. The cystathionine γ lyase (cystathionine-gamma-splitting enzyme, CSE) in the junction vascular tissue was measured. The results showed that the plasma H2S levels and the CSE expression levels had statistically significant difference among different groups (P<0.05). As compared with PH group, plasma H2S levels were declined obviously (11.9±4.2 vs. 20.6±4.5, P<0.05), and CSE expression levels in the junction vascular tissue were notably reduced (1.7±0.6 vs. 2.8±0.8, P<0.05), apoptosis rate of vascular smooth muscle cells per unit area was significantly decreased (0.10±0.15 vs. 0.24±0.07, P<0.05), and the expression levels of p-AKT and NF-κB were significantly decreased (2.31±0.33 vs. 3.04±0.38, P<0.05; 0.33±0.17 vs. 0.51±0.23, P<0.05), however, IκBa and Bcl-2 expression increased obviously (5.57±0.17 vs. 3.67±0.13, P<0.05; 0.79±0.29 vs. 0.44±0.36, P<0.05) in PH+PPG group. As compared with PH group, H2S levels were notably increased (32.7±7.3 vs. 20.6±4.5, P<0.05), the CSE levels in the junction vascular tissue were significantly increased (6.3±0.7 vs. 2.8±0.8, P<0.05), apoptosis rate of vascular smooth muscle cells per unit area was significantly increased (0.35±0.14 vs. 0.24±0.07, P<0.05), and the expression levels of p-AKT and NF-κB were significantly increased (4.29±0.49 vs. 3.04±0.38, P<0.05; 0.77±0.27 vs. 0.51±0.23, P<0.05), yet IκBa and Bcl-2 expression decreased significantly (3.23±0.24 vs. 3.67±0.13, P<0.05; 0.31±0.23 vs. 0.48±0.34, P<0.05) in PH+S group. It is concluded that esophagus-gastric junction vascular lesions happen under PH, and apoptosis of smooth muscle cells is declined. H2S can activate NF-κB by the p-AKT pathway, leading to the down-regulation of Bcl-2, eventually stimulating apoptosis of vascular smooth muscle cells, easing PH. H2S/CSE system may play an important role in remission of PH via the AKT-NF-κB pathway.

The portal-drained viscera release fibroblast growth factor 19 in humans.

Fibroblast growth factor 19 (FGF19) is an ileum-derived endrocrine factor that is produced in response to transepithelial bile salt flux. FGF19 represses bile salt synthesis in the liver. Despite the general assumption that FGF19 signals to the liver via portal blood, no human data are available to support this notion. The aim was to study portal FGF19 levels, and determined bile salt and FGF19 fluxes across visceral organs in humans. Bile salt and FGF19 levels were assessed in arterial, portal, and hepatic venous blood collected from fasted patients who underwent partial liver resection for colorectal liver metastases (n = 30). Fluxes across the portal-drained viscera (PDV), liver, and splanchnic area were calculated. Portal bile salt levels (7.8 [5.0-12.4] µmol/L) were higher than levels in arterial (2.7 [1.7-5.5] µmol/L, P < 0.0001) and hepatic venous blood (3.4 [2.5-6.5] µmol/L, P < 0.0001). Bile salts released by the PDV (+1.2 [+0.7-+2.0] mmol kg-1 h-1, P < 0.0001) were largely taken up by the liver (-1.0 [-1.8 to -0.4] mmol kg-1 h-1, P < 0.0001). Portal levels of FGF19 (161 ± 78 pg/mL) were higher than arterial levels (135 ± 65 pg/mL, P = 0.046). A net release of FGF19 by the PDV (+4.0 [+2.1 to +9.9] ng kg-1 h-1, P < 0.0001) was calculated. There was no significant flux of FGF19 across the liver (-0.2 [-3.7 to +7.4] ng kg-1 h-1, P = 0.93). In conclusion, FGF19 levels in human portal blood are higher than in arterial blood. FGF19 is released by the portal-drained viscera under fasted steady state conditions.

Circulating phospholipid profiling identifies portal contribution to NASH signature in obesity.

BACKGROUND & AIMS: Non-alcoholic steatohepatitis (NASH) is characterized by steatosis, lobular inflammation, hepatocyte ballooning with fibrosis in severe cases, and high prevalence in obesity. We aimed at defining NASH signature in morbid obesity by mass spectrometry-based lipidomic analysis. METHODS: We analyzed systemic blood before and 12 months after bariatric surgery, along with portal blood and adipose tissue lipid efflux collected from obese women at the time of surgery (9 structural classes, 150 species). RESULTS: Increased concentrations of several glycerophosphocholines (PC), glycerophosphoethanolamines (PE), glycerophosphoinositols (PI), glycerophosphoglycerols (PG), lyso-glycerophosphocholines (LPC), and ceramides (Cer) were detected in systemic circulation of NASH subjects. Post-surgery weight loss (12 months) improved the levels of liver enzymes, as well as several lipids, but most PG and Cer species remained elevated. Analysis of lipids from hepatic portal system at the time of surgery revealed limited lipid alterations compared to systemic circulation, but PG and PE classes were found significantly increased in NASH subjects. We evaluated the contribution of visceral adipose tissue to lipid alterations in portal circulation by measuring adipose tissue lipid efflux ex vivo, and observed only minor alterations in NASH subjects. Interestingly, integration of clinical and lipidomic data (portal and systemic) led us to define a NASH signature in which lipids and clinical parameters are equal contributors. CONCLUSIONS: Circulatory (portal and systemic) phospholipid profiling and clinical data defines NASH signature in morbid obesity. We report weak contribution of visceral adipose tissue to NASH-related portal lipid alterations, suggesting possible contribution from other organs draining into hepatic portal system.

Hepatic toll-like receptor 4 expression is associated with portal inflammation and fibrosis in patients with NAFLD.

BACKGROUND & AIMS: Notwithstanding evidences implicating the lipopolysaccharides (LPS)/toll-like receptor-4 (TLR4) axis in the pathogenesis of NAFLD, there are no studies aimed to characterize hepatic TLR4 expression in NAFLD patients. We aimed to analyse hepatic TLR4 expression and to verify its relationship with disease activity/evolution in NAFLD patients. METHODS: Liver tissue from 74 patients with NAFLD and 12 controls was analysed by immunohistochemistry (IHC) for TLR4, α-smooth muscle actin (α-SMA) and cytokeratin-7. IHC for α-SMA was used to evaluate activation of fibrogenic cells (hepatic stellate cells and portal/septal myofibroblasts), that for cytokeratin-7 to count hepatic progenitor cells and bile ducts/ductules, and that for CD68, in a subgroup of 27 patients, for detecting macrophages. Serum LPS-binding protein (LBP), a sensitive marker of LPS activity, was determined in 36 patients and 32 controls. RESULTS: As confirmed by double-labelling experiments, the highest level of TLR4 expression was observed in hepatic progenitor cells, biliary cells and portal/septal macrophages. TLR4-positive hepatic progenitor cells and bile ducts/ductules correlated with portal/interface inflammation, activity of fibrogenic cells and fibrosis (P < 0.001). Also the score of TLR4 positivity of porto-septal inflammatory infiltrate correlated with number of hepatic progenitor cells and bile ducts/ductules, activity of fibrogenic cells and fibrosis (P < 0.01). Serum LBP was increased in patients compared to controls (P < 0.001), and correlated with portal/interface inflammation, activity of portal/septal myofibroblasts and fibrosis (all P < 0.05). CONCLUSIONS: TLR4 expression by regenerating and inflammatory cells at the porto-septal and interface level, favoured by increased LPS activity, is associated with activation of fibrogenic cells and the degree of fibrosis.

Hepatoselectivity and the evolution of insulin.

In spite of major developments in insulin production, purification, pharmaceutical formulation and methods of delivery, problems remain both in the day to day management of insulin-treated diabetes and with regard to its long-term complications. The risks of hypoglycaemia and weight gain are major concerns particularly for the patient, and the persistence of microvascular and premature macrovascular complications as the main causes of morbidity and mortality in both type 1 and type 2 diabetes is a constant reminder that our therapeutic and management strategies are inadequate. One clear and striking difference between currently available insulin treatments and normal physiology is the relative difference in exposure to insulin of the liver versus peripheral tissues. Hepatoselective insulin analogues have the potential to restore the normal hepatic to peripheral gradient in insulin action. Here, we discuss the possible therapeutic potential that such analogues may have over currently available insulin preparations. These benefits could include a lower risk of hypoglycaemia, less weight gain and a potential reduction in microvascular and macrovascular complications. We explore the evolution of insulin with hepatoselectivity in mind and possible strategies to create hepatoselective insulins.

The portal inflammatory infiltrate and ductular reaction in human nonalcoholic fatty liver disease.

UNLABELLED: Although nonalcoholic fatty liver disease (NAFLD) is conventionally assessed histologically for lobular features of inflammation, development of portal fibrosis appears to be associated with disease progression. We investigated the composition of the portal inflammatory infiltrate and its relationship to the ductular reaction (DR), a second portal phenomenon implicated in fibrogenesis. The portal inflammatory infiltrate may contribute directly to fibrogenesis as well as influence the fate of the DR hepatic progenitor cells (HPCs), regulating the balance between liver repair and fibrosis. The presence of portal inflammation in NAFLD was strongly correlated with disease severity (fibrosis stage) and the DR. The portal infiltrate was characterized by immunostaining NAFLD liver biopsy sections (n = 33) for broad leukocyte subset markers (CD68, CD3, CD8, CD4, CD20, and neutrophil elastase) and selected inflammatory markers (matrix metalloproteinase 9 and interleukin [IL]-17). Cells expressing all markers examined were identified throughout the liver lobules and in portal tracts, although portal tracts were more densely populated (P < 0.01), and dominated by CD68(+) macrophages and CD8(+) lymphocytes, at all stages of disease. An increase in portal macrophages in NAFLD patients with steatosis alone (P < 0.01) was the earliest change detected, even before elevated expression of the proinflammatory cytokines, IL1B and TNF, in patients with early NASH (P < 0.05). Portal and periductal accumulation of all other cell types examined occurred in progressed NASH (all P < 0.05). CONCLUSION: Knowledge of the complex cellular composition of the portal inflammatory infiltrate and HPC/DR niche in NAFLD will shape future functional studies to elucidate the contribution of portal inflammation to HPC differentiation and NAFLD pathogenesis.

Comparison of intestinal metabolism of CYP3A substrates between rats and humans: application of portal-systemic concentration difference method.

1. Rats are frequently used in pharmacokinetic studies during drug discovery. However, there is limited information regarding species differences in intestinal availability (Fg) between rats and humans. 2. Here, we directly estimated the fraction of dose absorbed in the portal vein (FaFg) of rats for nine CYP3A substrates using portal-systemic concentration difference method and compared them with human FaFg. No distinct difference in FaFg between the two species was observed, and seven of the nine compounds were within a two-fold difference. Given that their net fraction of dose absorbed (Fa) are expected to be high, this result indicates a moderate correlation in Fg between the two species. 3. In contrast, the in vitro intrinsic clearance (CLint,u) in rat intestinal microsomes tended to be lower than that in humans, and the correlation between intestinal CLint,u and FaFg in rats was poor compared with that in humans. 4. Our finding indicates that rats are appropriate animals for evaluation of the intestinal absorption and metabolism of CYP3A substrates. However, a degree of caution is required when estimating rat Fg from rat intestinal microsomes due to the low metabolic activity and the poor correlation between in vitro and in vivo intestinal metabolism.

Mechanistic investigations of test article-induced pancreatic toxicity at the endocrine-exocrine interface in the rat.

Pancreatic toxicity commonly affects the endocrine or exocrine pancreas. However, it can also occur at the endocrine-exocrine interface (EEI), where the capillary network of the islet merges with the capillaries of the surrounding acinar tissue, that is, the insulo-acinar portal system. The goal of this article is to describe a novel, test article-induced pancreatic toxicity that originated at the EEI and to summarize investigations into the mechanistic basis of the injury. This injury was initially characterized by light microscopy in 7/14 day-toxicity studies in Sprague-Dawley (Crl: CD®[SD]) rats with undisclosed test articles. Microvascular injury at the interface resulted in peri-islet serum exudation, fibrin deposition, hemorrhage, inflammation, and secondary degeneration/necrosis of surrounding exocrine tissue. More chronic injury presented as islet fibrosis and lobular atrophy. Direct cytotoxicity affecting the capillary endothelium at the EEI was confirmed ultrastructurally on day 4. Endothelial microparticle and blood flow studies further confirmed endothelial involvement. Similar lesions occurred less frequently in 2 other rat strains and not in the mouse, dog, or cynomolgus macaque. In summary, in vivo and investigative study data confirmed primary endothelial cytotoxicity in the pathogenesis of this lesion and suggested that the lesion may be rat/rat strain-specific and of uncertain relevance for human safety risk assessment.

[The mechanisms of adaptation of the vascular bed to hemodynamic changes in portal hypertension].

The data of the literature on the mechanisms of restructuring of vascular bed in response to hemodynamic changes due to portal hypertension. Despite the fact that these changes are compensatory-adaptive reaction to the deteriorating conditions of blood circulation, they contribute to its progression, promoting the development of serious complications, one of which was bleeding from esophageal varices.

Propionic and butyric acids, formed in the caecum of rats fed highly fermentable dietary fibre, are reflected in portal and aortic serum.

SCFA are important end products formed during colonic fermentation of dietary fibre (DF). It has been suggested that propionic and butyric acids affect metabolic parameters, low-grade systemic inflammation, insulin resistance and obesity. The aim of the present study was to investigate whether the various SCFA profiles observed after fermentation in the caecum of rats fed pectin, guar gum and fructo-oligosaccharides (FOS) were also represented in hepatic portal and aortic serum. The SCFA in serum were extracted using hollow fibre-supported liquid membrane extraction before GLC analysis. The concentrations of acetic, propionic and butyric acids in caecal content correlated well with those in portal serum (P< 0·001) for all the three diets. A weaker correlation was found for propionic and butyric acids between the caecal content and aortic serum (P< 0·05). Butyric acid concentration in caecal content was also reflected in the aortic serum (P= 0·019) of rats fed FOS. FOS gave rather low amounts of the SCFA, especially butyric acid, but caecal tissue weight was higher with FOS than with the other two diets. This may be explained by rapid fermentation and quick utilisation/absorption of the SCFA. The present study also showed that propionic acid was metabolised/utilised to a higher extent than butyric acid by colonocytes before reaching the liver. We conclude that the formation of propionic and butyric acids in the caecum is reflected by increased concentrations in the aortic blood. This approach may therefore simplify the evaluation and study of SCFA from DF in human subjects.

Intestinal transport as a potential determinant of drug bioavailability.

Orally administered drugs are generally absorbed by the small intestine and transported either to the lymphatic system or to the hepatic portal system. In general, lipid soluble drugs and vitamins are transported by the small intestine to the lymphatics, and water-soluble drugs are transported to the hepatic portal system. By avoiding the early hepatic first pass effect, the lymphatic transport system may increase drug bioavailability. In addition to its transport systems, the small intestine may affect drug bioavailability through drug uptake, intestinal first pass effect, recruitment of drugs by chylomicrons, formation and secretion of chylomicrons, and enterohepatic circulation. All of these factors should be considered when formulating orally administered lipophilic drugs. Our data also suggest that Caco-2 cells may serve as a valuable in vitro model to study the intestinal transport of orally administered drugs.

Hedgehog pathway and pediatric nonalcoholic fatty liver disease.

UNLABELLED: It is unclear why the histology of pediatric and adult nonalcoholic fatty liver disease (NAFLD) sometimes differs. In adults, severity of portal inflammation and fibrosis correlate with Hedgehog pathway activity. Hedgehog (Hh) signaling regulates organogenesis, but is silent in adult livers until injury reinduces Hh ligand production. During adolescence, liver development is completed and children's livers normally lose cells that produce and/or respond to Hh ligands. We postulated that fatty liver injury interferes with this process by increasing Hh ligand production, and theorized that hepatic responses to Hh ligands might differ among children according to age, gender, and/or puberty status. Using unstained liver biopsy slides from 56 children with NAFLD, we performed immunohistochemistry to assess Hh pathway activation and correlated the results with clinical information obtained at biopsy. Fibrosis stage generally correlated with Hh pathway activity, as demonstrated by the numbers of Hh-ligand-producing cells (P < 0.0001) and Hh-responsive (glioma-associated oncogene 2-positive [Gli2]) cells (P = 0.0013). The numbers of Gli2(+) cells also correlated with portal inflammation grade (P = 0.0012). Two distinct zonal patterns of Hh-ligand production, portal/periportal versus lobular, were observed. Higher portal/periportal Hh-ligand production was associated with male gender. Male gender and prepuberty were also associated with ductular proliferation (P < 0.05), increased numbers of portal Gli2(+) cells (P < 0.017) and portal fibrosis. CONCLUSION: The portal/periportal (progenitor) compartment of prepubescent male livers exhibits high Hh pathway activity. This may explain the unique histologic features of pediatric NAFLD because Hh signaling promotes the fibroductular response.

Release of avian neurotensin in response to intraluminal contents in the duodenum of chickens.

Peripheral and hepatic-portal plasma levels of neurotensin (NT) in fed and fasted chickens were determined using RIA. Portal levels of NT(1-13) (fed = 61.3 ± 3.9 fmol/mL; fasted = 44.5 ± 3.9 fmol/mL) were significantly higher than peripheral levels (fed = 8.2 ± 3.3 fmol/mL; fasted = 7.8 ± 3.0 fmol/mL) collected from the wing vein, indicating that some NT is metabolized in the liver. Portal plasma levels of NT collected from fed birds were also significantly higher than portal plasma levels of NT collected from fasted birds. Neurotensin, as identified by HPLC, exhibited a 2-fold increase in plasma extracts following perfusion of the proximal ileum with a 10-mg sample of oleic acid, as compared with control samples of plasma collected before oleic acid perfusion. In whole-animal studies, the injection of a micellar solution of oleic acid into isolated segments of the duodenum resulted in elevated plasma immunoreactive NT in blood collected from the pancreaticoduodenal vein. Injection of a 1,000 mOsm sodium chloride solution had a slightly lesser and delayed effect compared with oleic acid, but a greater effect than 0.1 N hydrochloric acid in isotonic saline solution. Injection of an amino acid solution (10% Travasol), 300 mOsm glucose solution, or pure corn oil had no effect. These results demonstrate that intraduodenal oleic acid is a potent stimulus for the release of NT from the duodenum into the hepatic-portal circulation of chickens.

Inverse regulation of basal lipolysis in perigonadal and mesenteric fat depots in mice.

Given the strong link between visceral adiposity and (hepatic) insulin resistance as well as liver steatosis, it is crucial to characterize obesity-associated alterations in adipocyte function, particularly in fat depots drained to the liver. Yet these adipose tissues are not easily accessible in humans, and the most frequently studied depot in rodents is the perigonadal, which is drained systemically. In the present study, we aimed to study alterations in lipolysis between mesenteric and perigonadal adipocytes in mice. Basal free fatty acid and glycerol release was significantly lower in perigonadal compared with mesenteric adipocytes isolated from chow-fed C57BL/6J mice. However, this difference completely vanished in high-fat diet-fed mice. Consistently, protein levels of the G(0)/G(1) switch gene 2 (G0S2), which were previously found to be inversely related to basal lipolysis, were significantly lower in mesenteric compared with perigonadal fat of chow-fed mice. Similarly, perilipin was differently expressed between the two depots. In addition, adipocyte-specific overexpression of G0S2 led to significantly decreased basal lipolysis in mesenteric adipose tissue of chow-fed mice. In conclusion, lipolysis is differently regulated between perigonadal and mesenteric adipocytes, and these depot-specific differences might be explained by altered regulation of G0S2 and/or perilipin.

Bioavailability of vitamin B12 in cows' milk.

The natural source of vitamin B12 in human diets comes from animal products. For example, one glass (250 ml) of milk provides approximately 50 % of the RDA (2·4 µg/d). It was hypothesised that the provision of vitamin B12 from milk is more efficiently absorbed than the synthetic form used in vitamin supplements. Pigs (n 10) were used as a model for intestinal absorption of vitamin B12 in humans to compare the net fluxes of vitamin B12 across the portal-drained viscera (PDV; an indicator of intestinal absorption) after ingestion of meals complemented with conventional and vitamin B12-enriched (via injections to cows) milk (raw, pasteurised or microfiltrated) or with equivalent amounts of cyanocobalamin, the synthetic form used in supplements or unsupplemented. Net flux of vitamin B12 across PDV after the ingestion of milk was positive, though not influenced by milk enrichment (P>0·3) or technological processes (P = 0·8) and was greater than after ingestion of equivalent amounts of cyanocobalamin (cyanocobalamin v. all milk, P ≤ 0·003). In fact, net fluxes of this vitamin were not different from 0 after either cyanocobalamin or the meal devoid of vitamin B12 (unsupplemented v. cyanocobalamin, P = 0·7). The cumulative PDV fluxes during the 24 h following ingestion of meals complemented with milk varied from 5·5 to 6·8 µg. These values correspond to an efficiency of intestinal absorption of vitamin B12 from milk varying between 8 and 10 %. Therefore, vitamin B12, which is abundant in cows' milk, is also substantially more available than the most commonly used synthetic form of this vitamin.

Route and type of nutrition and surgical stress influence secretory phospholipase A2 secretion of the murine small intestine.

BACKGROUND: The function of secretory phospholipase A2 (sPLA2) is site dependent. In tissue, sPLA2 regulates eicosanoid production; in circulation, sPLA2 primes neutrophils; and in the intestinal lumen, sPLA2 provides innate bactericidal immunity as a defensin-related protein. Since parenteral nutrition (PN) primes leukocytes while suppressing intraluminal mucosal immunity, the authors hypothesized that (1) PN would diminish luminal sPLA2 activity but increase activity in intestinal tissue and serum and (2) stress would accentuate these changes. METHODS: Mice received chow, a complex enteral diet (CED), intragastric PN (IG-PN), or PN in experiment 1 and chow, chow+stress, PN, or PN+stress in experiment 2. RESULTS: In experiment 1, luminal sPLA2 activity was greatest in chow and decreased in CED, IG-PN, and PN, with PN lower than CED and IG-PN. Compared to that after chow, serum sPLA2 activity dropped after CED, IG-PN, and PN. Serum sPLA2 was higher in portal than systemic serum. In experiment 2, PN lowered luminal sPLA2 activity vs chow. Stress lowered luminal sPLA2 activity in chow, without change in PN. Following stress, luminal immunoglobulin A increased in chow but not PN. Serum sPLA2 activity increased in PN. CONCLUSIONS: PN attenuates sPLA2 activity in intestinal fluid, consistent with suppressed innate mucosal defense. Stress suppresses luminal fluid sPLA2 activity in chow but not the immunoglobulin A response; PN impairs both. Stress significantly elevates serum sPLA2 in PN-fed mice, consistent with known increased neutrophil priming with PN. PN reduces innate bactericidal immunity of the gut but upregulates serum proinflammatory products poststress.

Relation of net portal flux of nitrogen compounds with dietary characteristics in ruminants: a meta-analysis approach.

Decrease of N intake (NI) with the aim of increasing efficiency of N utilization and decreasing the negative environmental effects of animal production requires assessment of the forms in which N is absorbed. A meta-analysis was conducted on 68 publications (90 experiments and 215 treatments) to study the effect of NI on net portal appearance (NPA) of nitrogenous nutrients [amino acids (AA), ammonia, and urea] in ruminants. In addition, the effect of several dietary energy and protein factors on this relationship was investigated. These factors were: dry matter intake; proportion of concentrate; diet concentrations and intakes of nonfiber carbohydrates and neutral detergent fiber (NDF); diet concentrations of total digestible nutrients (TDN) and crude protein; rumen-degradable protein and rumen-undegradable protein, as percent dry matter or percent crude protein. The effect of species and physiological stage was also investigated. Within-experiment analyses revealed that the NPA of AA-N and ammonia-N increased linearly, whereas the NPA of urea-N decreased (or recycling of urea-N increased) linearly with NI. Besides NI, many significant covariates could be introduced in each NPA model. However, only TDN and neutral detergent fiber intake (NDFi) were common significant covariates of NI in each NPA model. In this database, ruminants converted 60% of incremental NI into NPA of AA-N with no species effect on that slope. However, at similar NI, TDN, and NDFi, sheep absorbed more AA-N than did cattle and dairy cows. On the other hand, species tended to affect the slope of the relationship between NPA of ammonia-N and NI, which varied from 0.19 for the sheep to 0.38 for dairy cows. On average, the equivalent of 11% of incremental NI was recycled as urea-N to the gut through the portal-drained viscera, which excludes salivary contribution, and no species difference was detected. Overall, at similar TDN and NDFi, sheep and cattle increased their NPA of AA-N relative to NI increment by a similar magnitude. The higher absorption of AA-N observed in sheep compared with cattle, at similar NI, TDN, and NDFi, might result from lower losses of AA through portal-drained viscera metabolism.

Metabolic effects of feeding ethanol or propanol to postpartum transition Holstein cows.

Eight lactating Holstein cows implanted with a ruminal cannula and permanent indwelling catheters in major splanchnic blood vessels were used to investigate metabolism of propanol and ethanol in the postpartum transition period. Cows were randomly allocated to 1 of 4 treatments in a randomized design with a 2 by 2 factorial arrangement of treatments. Factor 1 was 2.6g of calcium carbonate/kg of dry matter (DM) versus 1.5 g of 2-hydroxy-4-(methylthio)-butanoic acid isopropyl ester/kg of DM. Factor 2 was supplementation with 14 g of propanol/kg of DM (propanol treatment; PT) versus 14 g of ethanol/kg of DM (ethanol treatment; ET). Only factor 2 data are presented in the present paper. Treatments were administered in silage-based total mixed rations and cows were fed the experimental total mixed ration from the day of parturition. Daily rations were fed in 3 equally sized portions at 8-h intervals. Eight hourly sets of ruminal fluid, arterial, and hepatic portal and hepatic vein samples were collected at day -15 ± 5, 4, 15, and 29 relative to parturition. Dry matter intake and milk yield increased with days in milk (DIM), but were not affected by treatment. From prepartum to 4 DIM ruminal concentrations of propanol and ethanol increased with PT and ET, respectively. Postpartum, alcohol intake increased 49% in PT and 34% in ET from 4 to 29 d in milk, respectively. Ruminal concentrations of the alcohols remained unaffected by DIM. Treatments did not affect total ruminal volatile fatty acid concentrations, but the molar proportion of acetate increased in ET and the molar proportion of propionate increased in PT compared with the contrasting treatment. Propanol treatment decreased milk fat content at 15 to 29 DIM compared with ET. The net portal release of propanol and ethanol increased with increasing ruminal concentration of the respective alcohol. The portal release of alcohol accounted for 43 to 85% of ingested propanol and 36 to 57% of ingested ethanol. Hepatic uptake of propanol and ethanol equaled the net portal flux and no effect of treatment was detected for net splanchnic release of propanol and ethanol. In conclusion, ruminal metabolism is a major component of alcohol metabolism in dairy cows. The postpartum transition dairy cow has sufficient metabolic capacity to cope with high dietary concentrations of primary alcohols even when alcohol intake is abruptly increased at the day of calving. Alcohol intake affects milk fat content and alcohol composition of silage might be important to improve predictions of milk composition.

Iron levels in hepatocytes and portal tract cells predict progression and outcomes of patients with advanced chronic hepatitis C.

BACKGROUND & AIMS: Iron may influence severity and progression of non-hemochromatotic liver diseases. Our aim was to assess the relationship of iron and HFE genetic variations to progression and outcomes in the HALT-C Trial and whether PegIFN therapy influenced iron variables. METHODS: Participants were randomized to receive long-term PegIFN [n = 400] or no therapy [n = 413] for 3.5 y, with follow-up for up to 8.7 y [median 6.0 y]. Associations of patient characteristics with iron variables at baseline and over time were carried out using Kaplan-Meier analyses, Cox regression models, and repeated measures analysis of covariance. RESULTS: Participants who developed clinical outcomes [CTP > 7, ascites, encephalopathy, variceal bleeding, SBP, HCC, death] had significantly higher baseline scores for stainable iron in hepatocytes and in portal tract cells than those without. There were significant direct correlations between stainable iron in portal triads and lobular and total Ishak inflammatory and fibrosis scores [P < 0.0001]. Iron in triads at baseline increased risk of outcomes (HR = 1.35, P = 0.02). Stainable iron in hepatocytes decreased, whereas that in portal stromal cells increased significantly [P < 0.0001] over time. Serum iron and TIBC fell significantly over time [P < 0.0001], as did serum ferritin [P = 0.0003]. Chronic PegIFN treatment did not affect stainable iron. HFE genetic variations did not correlate with outcomes, including development of hepatocellular carcinoma. CONCLUSIONS: Stainable iron in hepatocytes and portal tract cells is a predictor of progression and clinical and histological outcomes in advanced chronic hepatitis C. Chronic low-dose PegIFN therapy did not improve outcomes, nor iron variables.