Antitumor necrosis factor antibodies reduce hepatic steatosis during total parenteral nutrition and bowel rest in the rat

Intestinal Barrier and Permeability in Health, Obesity and NAFLD

The largest surface of the human body exposed to the external environment is the gut. At this level, the intestinal barrier includes luminal microbes, the mucin layer, gastrointestinal motility and secretion, enterocytes, immune cells, gut vascular barrier, and liver barrier. A healthy intestinal barrier is characterized by the selective permeability of nutrients, metabolites, water, and bacterial products, and processes are governed by cellular, neural, immune, and hormonal factors. Disrupted gut permeability (leaky gut syndrome) can represent a predisposing or aggravating condition in obesity and the metabolically associated liver steatosis (nonalcoholic fatty liver disease, NAFLD). In what follows, we describe the morphological-functional features of the intestinal barrier, the role of major modifiers of the intestinal barrier, and discuss the recent evidence pointing to the key role of intestinal permeability in obesity/NAFLD.

Preoperative Elemental Diet before Laparoscopic Anterior Resection in Patients with Advanced Stenotic Rectal Cancer

Objectives:

To evaluate the feasibility of our new preoperative enteral nutrition protocol using Elental^Ⓡ without mechanical bowel preparation (MBP) before laparoscopic anterior resection (LAR) in patients with advanced stenotic rectal cancer.

Methods:

Among 74 patients with advanced rectal cancer (clinical stages T3 and T4) scheduled to undergo LAR, 42 patients with stenotic rectal cancer were administered Elental^Ⓡ (900 kcal/day) without MBP before LAR (group S). Thirty-two patients without stenosis (group NS) did not receive preoperative nutritional support but underwent MBP.

Results:

Group S patients were maintained in a fasting state and received an elemental diet approximately 10 days preoperatively without severe adverse effects. The incidence of postoperative complications (Clavien-Dindo classification ≥ grade 2) was significantly lower in group S than that in group NS (adjusted odds ratio [OR]: 6.046, P = 0.008). Logistic regression analysis revealed that group NS exhibited higher risks of developing postoperative complications than those exhibited by group S (OR: 4.32, 95% confidence interval [CI]: 1.28-17.28, P = 0.018). Among preoperative characteristics, the clinical tumor stage indicated a significant intergroup difference. Thus, the clinical stage was selected as a covariate and adjusted in the logistic regression model to calculate a covariate-adjusted OR. Group NS exhibited a higher incidence of postoperative complications than group S (adjusted OR: 6.05, 95% CI: 1.58-28.35, P = 0.008).

Conclusions:

Administration of an elemental diet using Elental^Ⓡ without MBP before LAR is a feasible strategy in patients with advanced stenotic rectal cancer. Application of this research may encourage use of Elental^Ⓡ in the clinical setting.

Liver Steatosis, Gut-Liver Axis, Microbiome and Environmental Factors. A Never-Ending Bidirectional Cross-Talk

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing worldwide and parallels comorbidities such as obesity, metabolic syndrome, dyslipidemia, and diabetes. Recent studies describe the presence of NAFLD in non-obese individuals, with mechanisms partially independent from excessive caloric intake. Increasing evidences, in particular, point towards a close interaction between dietary and environmental factors (including food contaminants), gut, blood flow, and liver metabolism, with pathways involving intestinal permeability, the composition of gut microbiota, bacterial products, immunity, local, and systemic inflammation. These factors play a critical role in the maintenance of intestinal, liver, and metabolic homeostasis. An anomalous or imbalanced gut microbial composition may favor an increased intestinal permeability, predisposing to portal translocation of microorganisms, microbial products, and cell wall components. These components form microbial-associated molecular patterns (MAMPs) or pathogen-associated molecular patterns (PAMPs), with potentials to interact in the intestine lamina propria enriched in immune cells, and in the liver at the level of the immune cells, i.e., Kupffer cells and stellate cells. The resulting inflammatory environment ultimately leads to liver fibrosis with potentials to progression towards necrotic and fibrotic changes, cirrhosis. and hepatocellular carcinoma. By contrast, measures able to modulate the composition of gut microbiota and to preserve gut vascular barrier might prevent or reverse NAFLD.

Liver disease symptoms in non-alcoholic fatty liver disease and small intestinal bacterial overgrowth

INTRODUCTION

It seems that there is a relationship between small intestinal bacterial overgrowth (SIBO) and non-alcoholic fatty liver disease (NAFLD). The main objective of this study was to evaluate the prevalence of SIBO among NAFLD patients.

METHODS

In this descriptive-analytical cross-sectional study, 98 eligible NAFLD patients were evaluated for SIBO using hydrogen breath test (HBT). They were divided into SIBO-positive and SIBO-negative groups. Demographic, clinical, and laboratory data were obtained.

RESULTS

Based on the HBT, 38 patients (39%) had bacteria overgrowth. There were no significant differences between SIBO-positive and SIBO-negative regarding demographic data and BMI classification (P > 0.05). Biochemical variables, the results of abdominal ultrasound, and liver elastography did not show any significant difference between SIBO-positive and SIBO-negative patients (P > 0.05). Patients with SIBO were found to have higher rates of bloating, while abdominal pain was more prevalent in SIBO-negative patients (P < 0.001).

CONCLUSIONS

SIBO is prevalent in NAFLD and associated with bloating in these patients. Further studies are necessary to elucidate if therapeutic manipulation of gut microbiota reduces the risk of NAFLD, fibrosis, and liver cirrhosis.

Loss of ileum decreases serum fibroblast growth factor 19 in relation to liver inflammation and fibrosis in pediatric onset intestinal failure

BACKGROUND & AIMS

The pathogenesis of intestinal failure (IF) associated liver disease (IFALD) is uncertain, we therefore investigated the role of FGF19 and pro-inflammatory cytokines has on this disease state.

METHODS

Serum FGF19, IL-6 and, TNF-α were measured in 52 IF patients at median age 6.0 years (IQR 2.2-13) after 10 months (4.1-39) on parenteral nutrition (PN). Thirty-nine patients underwent liver biopsies.

RESULTS

In IF patients, FGF19 concentrations were lower and those of IL-6 and TNF-α higher compared to healthy matched controls (p ⩽ 0.001 for all). FGF19 concentrations were further decreased in patients without a remaining ileum [37 pg/ml (IQR 30-68) vs. 74 (35-135) p=0.028], and correlated with remaining ileum length (r = 0.333, p = 0.018) and markers of cholesterol synthesis (r = -0.552 to -0.643, p < 0.001). Patients with histological portal inflammation [30 pg/ml (28-45) vs. 48 (33-100), p = 0.019] or fibrosis [35 pg/ml (30-66) vs. 99 (38-163), p = 0.013] had lower serum FGF19 concentrations than others. FGF19 negatively correlated with portal inflammation grade (r = -0.442, p = 0.005), serum TNF-α (r = -0.318, p = 0.025), METAVIR fibrosis stage (r = -0.441, p = 0.005) and APRI (r = -0.328, p = 0.028). IL-6 was higher during PN [6 pg/ml (2-31)] than after weaning off PN [2 pg/ml (1-5), p = 0.009], correlated weakly with cholestasis grade (r = 0.328, p = 0.044), and tended to associate with histological cholestasis [n = 5, 5 pg/ml (5-267) vs. n=34, 2 pg/ml (1-7), p = 0.058].

CONCLUSIONS

In pediatric onset of IF, total or partial loss of ileum decreases serum FGF19 concentration corresponding to hepatic inflammation and fibrosis, along with increased cholesterol synthesis. In contrast, serum IL-6 increases during PN and may associate with concurrent cholestasis. These data suggests that FGF19 may contribute to the pathogenesis of IFALD.

Severity of non-alcoholic fatty liver disease is associated with high systemic levels of tumor necrosis factor alpha and low serum interleukin 10 in morbidly obese patients

Morbid obesity has been shown to increase the risk to develop hepatic steatosis, also referred to as non-alcoholic fatty liver disease (NAFLD). Emerging evidence suggests that the severity of NAFLD may associate with increased serum levels of inflammatory markers as well as decreased concentration of mediators with anti-inflammatory actions, such as tumor necrosis factor alpha (TNF-α) and interleukin (IL) 10, respectively. We thus examined the serum levels of TNF-α and IL-10 in 102 morbidly obese women and men (body mass index > 40 kg/m(2)), exhibiting different grades of NAFLD. Blood glucose, glycated hemoglobin, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR), total cholesterol, triglycerides, high- and low-density lipoproteins, parameters of liver function, TNF-α, and IL-10 were measured in each subject. The stage of NAFLD was estimated by abdominal ultrasound imaging. In comparison with morbidly obese subjects without steatosis, morbidly obese patients with NAFLD showed increased age (39.23 ± 9.80 years), HOMA-IR (6.74 ± 1.62), total cholesterol (219.7 ± 9.58 mg/dl), aspartate aminotransferase (36.25 ± 3.24 UI/l), gamma-glutamyl transpeptidase (37.12 ± 3.41 UI/l), and TNF-α (37.41 ± 1.72 pg/ml) as well as decreased serum levels of IL-10 (61.05 ± 2.43 pg/ml). Interestingly, the systemic levels of TNF-α increased, while IL-10 decreased in accordance with the severity of NAFLD, which supports a role for systemic inflammatory mediators in promoting steatosis progression. Further clinical prospective studies need to be addressed to elucidate the role of TNF-α and IL-10 in the development of NAFLD while also establishing their clinical utility in the assessment of morbidly obese patients at higher risk to develop severe steatosis.

Early prediction of polymyxin-induced nephrotoxicity with next-generation urinary kidney injury biomarkers

Despite six decades of clinical experience with the polymyxin class of antibiotics, their dose-limiting nephrotoxicity remains difficult to predict due to a paucity of sensitive biomarkers. Here, we evaluate the performance of standard of care and next-generation biomarkers of renal injury in the detection and monitoring of polymyxin-induced acute kidney injury in male Han Wistar rats using colistin (polymyxin E) and a polymyxin B (PMB) derivative with reduced nephrotoxicity, PMB nonapeptide (PMBN). This study provides the first histopathological and biomarker analysis of PMBN, an important test of the hypothesis that fatty acid modifications and charge reductions in polymyxins can reduce their nephrotoxicity. The results indicate that alterations in a panel of urinary kidney injury biomarkers can be used to monitor histopathological injury, with Kim-1 and α-GST emerging as the most sensitive biomarkers outperforming clinical standards of care, serum or plasma creatinine and blood urea nitrogen. To enable the prediction of polymyxin-induced nephrotoxicity, an in vitro cytotoxicity assay was employed using human proximal tubule epithelial cells (HK-2). Cytotoxicity data in these HK-2 cells correlated with the renal toxicity detected via safety biomarker data and histopathological evaluation, suggesting that in vitro and in vivo methods can be incorporated within a screening cascade to prioritize polymyxin class analogs with more favorable renal toxicity profiles.

Toll-like receptors in liver disease

Activation of inflammatory signaling pathways is of central importance in the pathogenesis of alcoholic liver disease (ALD) and nonalcoholic steatohepatitis (NASH). Recent studies demonstrated that Toll-like receptors, the sensors of microbial and endogenous danger signals, are expressed and activated in innate immune cells as well as in parenchymal cells in the liver and thereby contribute to ALD and NASH. In this review, we emphasize the importance of gut-derived endotoxin and its recognition by TLR4 in the liver. The significance of TLR-induced intracellular signaling pathways and cytokine production as well as the contribution of individual cell types to the inflammation is evaluated. The contribution of TLR signaling to the induction of liver fibrosis and to the progression of liver pathology mediated by viral pathogens is reviewed in the context of ALD and NASH.

Anti-tumor necrosis factor-α monoclonal antibody alleviates parenteral nutrition-associated liver disease in mice

BACKGROUND

The authors aimed to investigate the role of anti-tumor necrosis factor (TNF)-α monoclonal antibody treatment in a mouse model of parenteral nutrition-associated liver disease (PNALD).

METHODS

C57BL/6J male mice (aged 6-8 weeks) were randomly assigned to 3 groups: parenteral nutrition (PN), PN with anti-TNF-α monoclonal antibody treatment (PN + mAb), and controls. A central venous catheter was inserted for intravenous infusion of a PN solution (PN and PN + mAb groups) or saline (controls) for 7 days. Liver pathology, hepatic biochemical indicators, and serum TNF-α concentrations were analyzed. Levels of hepatic bsep, mdr1a/mdr1b, mdr2, and mrp2 mRNA were also evaluated in each group.

RESULTS

The PN group showed significant increases in serum transaminase, direct bilirubin, and bile acids relative to the control group (P < .05). Histopathological changes in this group were consistent with early stage cholestasis. The pathological score and serum alanine aminotransferase, total bilirubin, and direct bilirubin levels were improved in the PN + mAb group relative to the PN group (P < .05). The PN group showed significantly lower hepatic bsep, mdr1a/mdr1b, mdr2, and mrp2 mRNA expression than the controls (P < .05), but these were significantly increased compared to the PN group (P < .05).

CONCLUSIONS

Infliximab administered at a single dose of 5 mg/kg body weight ameliorated the progression of PNALD and improved the expression of hepatic ABC transporter genes. Therefore, anti-TNF-α monoclonal antibody may be a beneficial therapy for patients with PNALD.

Probiotics as an emerging therapeutic strategy to treat NAFLD: focus on molecular and biochemical mechanisms

Nonalcoholic fatty liver disease (NAFLD) is currently the most common liver disease worldwide, both in adults and in children. NAFLD is characterized by aberrant lipid storage in hepatocytes (hepatic steatosis) and inflammatory progression to nonalcoholic steatohepatitis. Evidences so far suggest that intrahepatic lipid accumulation does not always derive from obesity. Gut microbiota has been considered as a regulator of energy homeostasis and ectopic fat deposition, suggesting its implications in metabolic diseases. Probiotics are live microbial that alter the enteric microflora and have beneficial effects on human health. Although the molecular mechanisms of probiotics have not been completely elucidated yet, many of their effects have proved to be beneficial in NAFLD, including the modulation of the intestinal microbiota, an antibacterial substance production, an improved epithelial barrier function and a reduced intestinal inflammation. Given the close anatomical and functional correlation between the bowel and the liver, and the immunoregulatory effects elicited by probiotics, the aim of this review is to summarize today's knowledge about probiotics in NAFLD, focusing in particular on their molecular and biochemical mechanisms, as well as highlighting their efficacy as an emerging therapeutic strategy to treat this condition.

Role of toll-like receptors and their downstream molecules in the development of nonalcoholic Fatty liver disease

Activation of innate immunity is associated with the development of liver disease, including non-alcoholic fatty liver disease (NAFLD). In the innate immune system, Toll-like receptors (TLRs) are sensors that recognize bacterial and viral components such as lipopolysaccharide, bacterial DNA, and peptidoglycan. Recent data have demonstrated that the liver is exposed to a high load of TLR ligands due to bacterial overgrowth and increased intestinal permeability in NAFLD. Upon stimulation by these TLR ligands, hepatic immune cells produce various mediators that are involved in host defense. On the other hand, these mediators alter lipid metabolism, insulin signaling, and cell survival. Indeed, some TLR-deficient mice demonstrate lesser degrees of NAFLD even though TLR ligands are increased. This paper will highlight the recent progress on the study of TLR signaling and their downstream molecules in the development of NAFLD.

Nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), the most common liver disorder in the Western world, is a clinico-histopathological entity in which excessive triglyceride accumulation in the liver occurs. Non-alcoholic steatohepatitis (NASH) represents the necroinflammatory form, which can lead to advanced liver fibrosis, cirrhosis, and hepatocellular carcinoma. The pathogenesis of NAFLD/NASH is complex but increased visceral adiposity plus insulin resistance with increased free fatty acids release play an initial key role for the onset and perpetuation of liver steatosis. Further events in the liver include oxidative stress and lipid peroxidation, decreased antioxidant defences, early mitochondrial dysfunction, iron accumulation, unbalance of adipose-derived adipokines with a chronic proinflammatory status, and gut-derived microbial adducts. New gene polymorphisms increasing the risk of fatty liver, namely APOC3 and PNPLA3, have been lately identified allowing further insights into the pathogenesis of this condition. In our review pathophysiological, genetic, and essential diagnostic and therapeutic aspects of NAFLD are examined with future trends in this field highlighted.

Bifidobacterium adolescentis supplementation ameliorates parenteral nutrition-induced liver injury in infant rabbits

BACKGROUND

Parenteral nutrition (PN)-induced liver injury is associated with gut atrophy, and probiotics have demonstrated the ability to stabilize the intestinal microecosystem and offer protection against bacterial translocation from the gut to the liver. Therefore, we hypothesized that enteral Bifidobacterium supplements could alleviate PN-associated liver injury.

METHODS

Three-week-old New Zealand rabbits were divided into three groups: control, PN, and PN + Bif group (PN plus enteral feeding 0.5 × 10(8) Bifidobacterium adolescentis per day). After 10 days, serum levels of liver enzyme and endotoxin were measured, and histology of liver and ileum were performed. Blood and homogenized samples of tissue from the mesenteric lymph nodes, lung, and spleen were cultured for detecting bacteria translocation. Intestinal permeability was determined by sugar absorption test.

RESULTS

Serum levels of total bilirubin and bile acid were found to be lower in the PN + Bif group, with considerably improved ileum and liver histology (vs. the PN group). The bacterial translocation rate (15.6%), serum endotoxin level (0.11 ± 0.03 EU/ml), and lactulose/mannitol ratio (0.02 ± 0.004) in the PN + Bif group were obviously lower than those of PN group (77.5%, 0.60 ± 0.09 EU/ml, and 0.038 ± 0.008, respectively) and similar to those of the control group (2.8%, 0.09 ± 0.03 EU/ml, and 0.019 ± 0.005, respectively).

CONCLUSIONS

Enteral probiotic supplementation could reduce gut permeability, bacterial translocation and endotoxemia, and thus attenuate PN-associated gut and liver injuries in infant rabbits.

Protective effects of Lactobacillus paracasei F19 in a rat model of oxidative and metabolic hepatic injury

The liver is susceptible to such oxidative and metabolic stresses as ischemia-reperfusion (I/R) and fatty acid accumulation. Probiotics are viable microorganisms that restore the gut microbiota and exert a beneficial effect on the liver by inhibiting bacterial enzymes, stimulating immunity, and protecting intestinal permeability. We evaluated Lactobacillus paracasei F19 (LP-F19), for its potential protective effect, in an experimental model of I/R (30 min ischemia and 60 min reperfusion) in rats fed a standard diet or a steatogen [methionine/choline-deficient (MCD)] diet. Both groups consisted of 7 sham-operated rats, 10 rats that underwent I/R, and 10 that underwent I/R plus 8 wk of probiotic dietary supplementation. In rats fed a standard diet, I/R induced a decrease in sinusoid perfusion (P < 0.001), severe liver inflammation, and necrosis besides an increase of tissue levels of malondialdehyde (P < 0.001), tumor necrosis factor-alpha (P < 0.001), interleukin (IL)-1beta (P < 0.001), and IL-6 (P < 0.001) and of serum levels of transaminase (P < 0.001) and lipopolysaccharides (P < 0.001) vs. sham-operated rats. I/R also induced a decrease in Bacterioides, Bifidobacterium, and Lactobacillus spps (P < 0.01, P < 0.001, and P < 0.001, respectively) and an increase in Enterococcus and Enterobacteriaceae (P < 0.01 and P < 0.001, respectively) on intestinal mucosa. The severity of liver and gut microbiota alterations induced by I/R was even greater in rats with liver inflammation and steatosis, i.e., MCD-fed animals. LP-F19 supplementation significantly reduced the harmful effects of I/R on the liver and on gut microbiota in both groups of rats, although the effect was slightly less in MCD-fed animals. In conclusion, LP-F19 supplementation, by restoring gut microbiota, attenuated I/R-related liver injury, particularly in the absence of steatosis.

Daily injection of tumor necrosis factor-{alpha} increases hepatic triglycerides and alters transcript abundance of metabolic genes in lactating dairy cattle

To determine whether inflammation can induce bovine fatty liver, we administered recombinant bovine tumor necrosis factor-alpha (rbTNF) to late-lactation Holstein cows. Cows (n = 5/treatment) were blocked by feed intake and parity and randomly assigned within block to control (CON; saline), rbTNF at 2 microg/(kg.d), or pair-fed control (saline, intake matched) treatments. Treatments were administered once daily by subcutaneous injection for 7 d. Plasma samples were collected daily for analysis of glucose and FFA and a liver biopsy was collected on d 7 for triglyceride (TG) and quantitative RT-PCR analyses. Data were analyzed using treatment contrasts to assess effects of tumor necrosis factor-alpha (TNFalpha) and decreased feed intake. By d 7, feed intake of both rbTNF and pair-fed cows was approximately 15% less than CON (P < 0.01). Administration of rbTNF resulted in greater hepatic TNFalpha mRNA and protein abundance and 103% higher liver TG content (P < 0.05) without affecting the plasma FFA concentration. Hepatic carnitine palmitoyltransferase 1 transcript abundance tended to be lower (P = 0.09) and transcript abundance of fatty acid translocase and 1-acyl-glycerol-3-phosphate acyltransferase was higher (both P < 0.05) after rbTNF treatment, consistent with increased FFA uptake and storage as TG. Transcript abundance of glucose-6-phosphatase (P < 0.05) and phosphoenolpyruvate carboxykinase 1 (P = 0.09), genes important for gluconeogenesis, was lower for rbTNF-treated cows. These findings indicate that TNFalpha promotes liver TG accumulation and suggest that inflammatory pathways may also be responsible for decreased glucose production in cows with fatty liver.

Probiotics and liver disease

Modulation of intestinal flora through the use of probiotics is an emerging therapeutic strategy in the management of chronic liver diseases. This article focuses on the pathophysiologic basis for using probiotics in liver disease and reviews the existing literature on the subject. The role of probiotics is examined in the following areas: a) prevention of infection, b) the hyperdynamic circulatory state of cirrhosis, c) hepatic encephalopathy, d) liver function, and e) nonalcoholic fatty liver disease.

Managing liver dysfunction in parenteral nutrition

Parenteral nutrition is life saving in patients with intestinal failure but liver dysfunction is commonly encountered, especially in neonates. Although abnormal liver function tests associated with short-term parenteral nutrition are usually benign and transient, liver dysfunction in both children and adults receiving long-term parenteral nutrition can progress to end-stage liver disease and liver failure. The aetiology of parenteral nutrition-associated liver disease is complex and multifactorial, with a range of patient, disease and nutrition-related factors implicated. Sepsis is of particular importance, as is the lack of enteral nutrition and overfeeding with intravenous glucose and/or lipid. Deficiencies of a number of amino acids including choline and taurine have also been implicated. Management of hepatic dysfunction in parenteral nutrition should initially focus on preventing its occurrence. Sepsis should be managed appropriately, enteral nutrition should be encouraged and maximised where possible and parenteral overfeeding should be avoided. Provision of parenteral lipid should be optimised to prevent the adverse effects of both deficiency and excess, and cyclical rather than continuous parenteral feeding should be administered. There is some evidence of benefit in neonates from oral antibiotics to prevent intestinal bacterial overgrowth and from oral ursodeoxycholic acid, but less to support their use in adults. Similarly, data to support widespread use of parenteral choline or taurine supplementation are lacking at present. Ultimately, severe parenteral nutrition-associated liver disease may necessitate referral for small intestine and/or liver transplantation.

Inhibition of matrix metalloproteinases increases PPAR-alpha and IL-6 and prevents dietary-induced hepatic steatosis and injury in a murine model

Steatosis is a prominent feature of nonalcoholic fatty liver disease and a potential promoter of inflammation. Injury leading to cirrhosis is partly mediated by dysregulation of matrix protein turnover. Matrix metalloproteinase (MMP) inhibitors protect mice from lethal TNF-alpha induced liver injury. We hypothesized that Marimastat, a broad-spectrum MMP and TNF-alpha converting enzyme (TACE) inhibitor, might modulate this injury through interruption of inflammatory pathways. Triglyceride and phospholipid levels (liver, serum) and fatty acid profiles were used to assess essential fatty acid status and de novo lipogenesis as mechanisms for hepatic steatosis. Mice receiving a fat-free, high-carbohydrate diet (HCD) for 19 days developed severe fatty liver infiltration, demonstrated by histology, magnetic resonance spectroscopy, and elevated liver function tests. Animals receiving HCD plus Marimastat (HCD+MAR) were comparable to control animals. Increased tissue levels of peroxisome proliferator activated receptor-alpha (PPAR-alpha), higher levels of serum IL-6, and decreased levels of serum TNF-alpha receptor II were also seen in the HCD+MAR group compared with HCD-only. In addition, there was increased phosphorylation, and likely activation, of PPAR-alpha in the HCD+MAR group. PPAR-alpha is a transcription factor involved in beta-oxidation of fatty acids, and IL-6 is a hepatoprotective cytokine. Liver triglyceride levels were higher and serum triglyceride and phospholipid levels lower with HCD-only but improved with Marimastat treatment. HCD-only and HCD+MAR groups were essential fatty acid deficient and had elevated rates of de novo lipogenesis. We therefore conclude that Marimastat reduces liver triglyceride accumulation by increasing fat oxidation and/or liver clearance of triglycerides. This may be related to increased expression and activation of PPAR-alpha or IL-6, respectively.

Total parenteral nutrition-related gastroenterological complications

Total parenteral nutrition is a life saving therapy for patients with chronic gastrointestinal failure, being an effective method for supplying energy and nutrients when oral or enteral feeding is impossible or contraindicated. Clinical epidemiological data indicate that total parenteral nutrition may be associated with a variety of problems. Herein we reviewed data on the gastroenterological tract regarding: (i) total parenteral nutrition-related hepatobiliary complications; and (ii) total parenteral nutrition-related intestinal complications. In the first group, complications may vary from mildly elevated liver enzyme values to steatosis, steatohepatitis, cholestasis, fibrosis and cirrhosis. In particular, total parenteral nutrition is considered to be an absolute risk factor for the development of biliary sludge and gallstones and is often associated with hepatic steatosis and intrahepatic cholestasis. In general, the incidence of total parenteral nutrition-related hepatobiliary complications has been reported to be very high, ranging from 20 to 75% in adults. All these hepatobiliary complications are more likely to occur after long-term total parenteral nutrition, but they seem to be less frequent, and/or less severe in patients who are also receiving oral feeding. In addition, end-stage liver disease has been described in approximately 15-20% of patients receiving prolonged total parenteral nutrition. Total parenteral nutrition-related intestinal complications have not yet been adequately defined and described. Epidemiological studies intended to define the incidence of these complications, are still ongoing. Recent papers confirm that in both animals and humans, total parenteral nutrition-related intestinal complications are induced by the lack of enteral stimulation and are characterised by changes in the structure and function of the gut. Preventive suggestions and therapies for both these gastroenterological complications are reviewed and reported in the present review.

Soybean oil fat emulsion to prevent TPN-induced liver damage: possible molecular mechanisms and clinical implications

Long-term total parenteral nutrition (TPN) is known to be associated with cholestasis and hepatic steatosis, which can be lethal in infants who cannot be fed orally. The present review focuses on the metabolic complications in the liver that may occur due to the excessive administration of fat-free TPN. We have recently developed an infant rat model of hepatic dysfunction and steatosis induced by overdose of fat-free TPN. In this model, plasma levels of liver enzymes in the fat-free TPN group were found to be significantly higher than in the other groups (i.e., the oral diet and fat-containing TPN groups). Pathological examination showed hepatomegaly and severe fatty changes without cholestasis in the liver of infant rats that received fat-free TPN. We clearly demonstrated that the addition of soybean oil emulsion to the TPN regimen prevented hepatic dysfunction and fatty changes. In the present review, we discuss the molecular mechanism of the hepatic dysfunction induced by fat-free TPN and the role of soybean oil fat emulsion in the TPN regimen. We also discuss the clinical implications of soybean oil-containing TPN solutions and point out the importance of including fat in the TPN regimen in order to prevent the hepatic abnormalities associated with the excessive administration of fat-free TPN.

Decrease in hepatic circulation induces hepatic fibrosis in a neonatal piglet model with short bowel syndrome

BACKGROUND

Regarding the complications associated with short bowel syndrome (SBS), progressive liver failure is one of the most severe complications known to occur: Although several studies have suggested that many factors interactively influence this clinical condition we investigated the relationship between hepatic circulation and hepatic fibrosis using a neonatal piglet SBS model.

MATERIALS AND METHODS

This study used the following 4 groups of neonatal piglets: a group with an 80% resection of the small bowel (SBS group), a group with a bypass operation of the small bowel (functional SBS group), a group with only a laparotomy as a sham operation (sham group), and a no operative treatment group (control group). We measured the hepatic circulation just before and after the reconstruction of the intestine, as well as on the 7th and 14th postoperative day. In addition, both blood and hepatic tissue samples were collected to investigate them both biochemically and morphologically.

RESULTS

Regarding the biochemical liver function and the tissue blood flow of liver, there were no significant differences among all groups on any investigated days. However, on both the 7th and 14th postoperative days, the portal venous flow in the SBS group was significantly lower than that in other groups. According to a histological analysis, only hepatic samples on the 14th postoperative day showed mild hepatic fibrosis in the SBS group. Regarding the alpha-smooth muscle actin staining findings that expresses active stellate cells, numerous positive cells were found to be distributed in the perisinusoidal space on the 14th postoperative day in the SBS group.

CONCLUSION

Based on our data, a decrease in the hepatic circulation, especially in the portal venous flow, after a massive resection of the intestine may cause progressive liver dysfunction because of the activation of hepatic stellate cells.

Probiotics: a potential target for the prevention and treatment of steatohepatitis

The accumulation of fat in hepatocytes with a necroinflammatory component-steatohepatitis-that may or may not have associated fibrosis is becoming a frequent lesion. Although steatohepatitis is currently recognized to be a leading cause of cryptogenic cirrhosis, the pathogenesis has not been fully elucidated. Among the various factors implicated, intestinal bacterial overgrowth may play a role. Indeed, various rat models of intestinal bacterial overgrowth have been associated with liver lesions similar to NASH, and bacterial overgrowth has been observed significantly more often in patients with NASH compared with control subjects. The authors discuss the relationship among intestinal bacterial overgrowth, steatohepatitis development, and probiotic treatment.

Postoperative jaundice and total parenteral nutrition-associated hepatic dysfunction

Postoperative jaundice and TPN-induced hepatic abnormalities represent clinical situations that stem from multiple and frequently overlapping insults to the liver. The pattern of LFT abnormalities and appropriate imaging studies provide clues to the diagnosis. Greater insight into the molecular basis of cholestasis has shed light on the possible common pathways for the hepatic derangements that are seen in diverse situations. TPN-related hepatic dysfunction most likely involves a combination of nutritional deficiencies, hormonal imbalances, excessive calories, and possibly bacterial overgrowth in the small bowel. Growing clinical evidence points to a high incidence of severe liver disease in chronic TPN-dependent patients. Careful monitoring of patients is warranted in these circumstances and combined transplantation of the liver and small bowel may be the only possibility for long-term survival for such patients with progressive liver disease.

Endotoxin-mediated hepatic lipid accumulation during parenteral nutrition in rats

OBJECTIVE

To assess the effect of endotoxemia on hepatic lipid content during parenteral nutrition (PN) in rats.

METHODS

Twenty male Sprague-Dawley rats (185-230 gm) were randomized to receive PN (n=9) or PN plus a continuous infusion of E. coli 026:B6 lipopolysaccharide (LPS; n= 11). All animals received isocaloric (170 kcal/kg/day), isonitrogenous (1.1 g N/kg/day), glucose-based PN for the next 78 hours. After 30 hours of adaptation to TPN, the animals were randomized to receive PN or PN plus LPS at 6 mg/kg/day for the remaining 48 hours of study. The animals were euthanized and the livers were harvested.

RESULTS

Liver weight increased significantly (by 60%) from 7.5+/-0.6 g to 12.1+/-2.4 g (p < or = 0.01) in the animals who received PN versus LPS, respectively. The proportion of liver water remained the same for PN and LPS groups (72.9+/-3.2% versus 72.3+/-3.8%, respectively, p = N.S.). However, liver fat increased disproportionately (by about 130%) from 0.20+/-0.05 g to 0.46+/-0.20 g (p < or = 0.01) total fat weight or from 9.6+/-1.8% to 13.6+/-4.1% (p < or = 0.02) lipid content (g/g) of the dry liver weight for the PN and LPS groups, respectively.

CONCLUSION

Endotoxin, when given concomitantly with parenteral nutrition, increases hepatic lipid accumulation and thus augments the development of parenteral nutrition-associated fatty liver in rats.

Improvement in cholestasis associated with total parenteral nutrition after treatment with an antibody against tumour necrosis factor alpha

BACKGROUND

Many patients receiving long-term total parenteral nutrition (TPN) develop liver disease; cholestasis is common and may be severe. Antitumour necrosis factor alpha (TNFalpha) antibodies have recently been used in order to treat Crohn's disease, but their effect on cholestasis in humans has not been previously described.

CASE REPORT

A 45-year-old woman had complicated Crohn's disease with multiple fistulae and only 1 m of residual small bowel. She had been receiving TPN for 2.5 years when she developed cholestasis which worsened despite adjustments to her TPN regimen. Infliximab, an anti-TNFalpha antibody, was given with the aim of treating an enterocutaneous fistula, but it also produced a marked biochemical and histological improvement in the TPN-related cholestasis.

CONCLUSIONS

Anti-TNFalpha antibodies appeared in this case to improve TPN-related cholestasis. This implies that TNFalpha may play an important role in the development of this condition.

Parenteral nutrition-associated liver complications in children

Parenteral nutrition is a life-saving therapy for patients with intestinal failure. It may be associated with transient elevations of liver enzyme concentrations, which return to normal after parenteral nutrition is discontinued. Prolonged parenteral nutrition is associated with complications affecting the hepatobiliary system, such as cholelithiasis, cholestasis, and steatosis. The most common of these is parenteral nutrition-associated cholestasis (PNAC), which may occur in children and may progress to liver failure. The pathophysiology of PNAC is poorly understood, and the etiology is multifactorial. Risk factors include prematurity, long duration of parenteral nutrition, sepsis, lack of bowel motility, and short bowel syndrome. Possible etiologies include excessive caloric administration, parenteral nutrition components, and nutritional deficiencies. Several measures can be undertaken to prevent PNAC, such as avoiding overfeeding, providing a balanced source of energy, weaning parenteral nutrition, starting enteral feeding, and avoiding sepsis.

Intralipid-based short-term total parenteral nutrition does not impair small intestinal mucosa-related cellular immune reactivity in the healthy rat

BACKGROUND

The lipid component of total parenteral nutrition (TPN) has reportedly been associated with trophic effects on the intestinal mucosa and suppressive effects on the immune system.

METHODS

We have challenged these hypotheses using a 7-day TPN rodent model comparing the effects of isocaloric, isonitrogenous lipid-based (TPN-lipid, 50% of calories as long-chain triacylglycerol) and carbohydrate-based TPN (TPN-CH, 100% of calories as carbohydrates) on mucosal morphology and immune function. Enterally fed animals were included to establish a baseline for immunologic read-outs. The study was performed in healthy, metabolically stable animals to avoid interference by septic or trauma-related stress factors.

RESULTS

Both TPN regimens resulted in a significantly smaller weight gain (TPN-lipid, 29.8 +/- 4.0 g; TPN-CH, 30.3 +/- 4.4 g) compared with enterally fed reference animals (49.2 +/- 3.2 g; p = .007), with no difference in nitrogen balance between the TPN groups. Mucosal sucrase activity was significantly lower in both TPN groups (TPN-lipid, 8.8 +/- 1.0 x 10(-7) katal per gram (kat/g) of protein; CH: 11.9 +/- 1.6 x 10(-7) kat/g of protein) compared with enteral feeding (17.4 +/- 0.9 x 10(-7) kat/g of protein; ANOVA: p = .0007). Morphometric analysis of the small intestine revealed no differences between the two TPN groups although a significantly depressed villus height in the TPN-lipid group could be observed in comparison to enterally fed reference rats (TPN-lipid, 0.47 +/- 0.02; TPN-CH, 0.50 +/- 0.01; enteral, 0.56 +/- 0.02 mm; ANOVA: p = .0298). Light and electron microscopy revealed a normal surface architecture in all three groups of rats. Cellular immune reactivity was evaluated using a novel specific immunization protocol: animals were immunized against OVA 4 weeks before TPN. OVA-induced lymphoproliferative responses and phenotypic data from draining popliteal and mesenteric lymph nodes were evaluated after the different regimens. Results did not differ among the three groups.

CONCLUSIONS

In healthy rodents, short-term lipid-based and carbohydrate-based TPN regimens lead to limited mucosal atrophy with preserved surface architecture compared with enteral feeding. However, peripheral and mesenteric cellular immune responsiveness after both TPN regimens remained comparable to enterally fed reference animals. Therefore, mesenteric and systemic cellular immune reactivity does not appear to be impaired by lipid-based or carbohydrate-based TPN.

Hepatocyte steatosis is a cytopathic effect of hepatitis C virus genotype 3

BACKGROUND/AIMS

Patients infected with the hepatitis C virus (HCV) often have liver steatosis, suggesting the possibility of a viral cytopathic effect. The aim of this study was to correlate the occurrence and severity of liver steatosis with HCV RNA type, level and sequence of the core-encoding region.

METHODS

We scored the liver steatosis in 101 HCV-infected individuals carefully selected to exclude other risk factors of a fatty liver. Results were compared with HCV RNA genotype and level in serum and liver. In selected patients, we assessed the effect of antiviral therapy on steatosis and the relationship between nucleocapsid sequence heterogeneity and fat infiltration.

RESULTS

Steatosis was found in 41 (40.6%) patients, irrespective of sex, age or route of infection. HCV genotype 3 was associated with higher steatosis scores than other genotypes. A significant correlation between steatosis score and titer of intrahepatic HCV RNA was found in patients infected with genotype 3, but not in those infected with genotype 1. In selected patients, response to alpha-interferon was associated with the disappearance of steatosis. Analysis of the nucleocapsid of 14 HCV isolates failed to identify a sequence specifically associated with the development of steatosis.

CONCLUSIONS

We provide virological and clinical evidence that the steatosis of the liver is the morphological expression of a viral cytopathic effect in patients infected with HCV genotype 3. At variance with published evidence from experimental models, the HCV nucleocapsid protein does not seem to fully explain the lipid accumulation in these patients.

Management of cholestasis in infants with very low birth weight

Infants with very low birth weight (VLBW) are at increased risk of cholestasis when compared with older infants and children. Factors associated with this increased risk of cholestasis include immaturity of the biliary excretory system, a diminished immune response to sepsis, an increased incidence of necrotizing enterocolitis and short bowel syndrome, as well as an increased exposure to parenteral nutrition (PN). The current literature on cholestasis in VLBW infants and the factors that mediate the initiation and progression of cholestatic liver damage is reviewed. A protocol for managing infants with cholestatic jaundice is presented, and a case report is included that shows use of the protocol to normalize the bilirubin in a VLBW infant with severe cholestatic jaundice.

Non-protein energy overloading induces bacterial translocation during total parenteral nutrition in newborn rabbits

The effect of energy intake provided by total parenteral nutrition (TPN) on the incidence of bacterial translocation and the relationship between TPN-induced cholestasis and bacterial translocation were investigated in newborn animals. Forty-six Japanese white newborn rabbits were divided into three groups: TPN-H group (high energy TPN; 280 kcal.kg-1.d-1), TPN-L group (low energy TPN; 180 kcal.kg-1.d-1), and a control group (breast fed). On day 8, they were all killed for investigation of the presence of bacterial translocation, for blood chemistry analysis, and for histological examination of the ileum. The incidence of translocation to any of mesenteric lymph nodes and liver and spleen was significantly higher in the TPN-H group (67%) than in both the TPN-L group (13%) and the control group (10%) (P < 0.01). No difference was seen in ileum morphology between the two TPN groups. Although the mean bilirubin level of the TPN-H group tended to be higher than the TPN-L group, whether or not bacterial translocation occurred was not found to be closely related to the degree of TPN-associated cholestasis. In conclusion, parenteral nonprotein energy overloadng increased the incidence of bacterial translocation in the newborn rabbit. However, bacterial translocation did not appear to be associated with the development of TPN-associated cholestasis.

Liver dysfunction and parenteral nutritional therapies

Hepatobiliary dysfunction associated with the use of total parenteral nutrition is a commonly recognized phenomenon occurring in up to 90% of patients on long-term therapy. Reasons for these abnormalities, both supported by research as well as theoretical possibilities are explored. Practical guidelines considered useful in documenting, preventing and treating serious hepatic consequences of total parenteral nutrition are discussed. The role of combined liver and small bowel transplantation as treatment for select patients is also reviewed.

Pentoxifylline and thalidomide fail to reduce hepatic steatosis during total parenteral nutrition and bowel rest in the rat

BACKGROUND

We suggested that the continuous translocation of endotoxin from Gram-negative bacterial overgrowth during bowel rest and total parenteral nutrition (TPN) causes the release of tumor necrosis factor (TNF), resulting in liver damage and hepatic dysfunction. Because TPN-induced hepatic steatosis was significantly reduced by the monoclonal antibodies against TNF, we attempted a more clinically applicable approach using pentoxifylline and thalidomide.

METHODS

A control group (group I) fed rat chow and four groups of rats receiving TPN were studied. Group II received TPN only; group III, TPN and 100 mg/kg/d pentoxifylline; group IV, TPN and 200 mg/kg/d pentoxifylline; and group V, TPN and 5 mg/kg/d thalidomide. On day 7, total liver fat was determined.

RESULTS

Bowel rest and TPN resulted in a significant (p < .0005) increase in liver fat content that was unaltered by either pentoxifylline or thalidomide.

CONCLUSIONS

Our results show no role for pentoxifylline or thalidomide in reducing TPN-associated hepatic steatosis.