Similar Insulin Regulation of Splanchnic FFA and VLDL-TG in Men with Nonalcoholic Hepatic Steatosis and Steatohepatitis.

This study aimed to determine whether obese men with nonalcoholic fatty liver disease (NAFLD) display differences between those with simple steatosis vs. steatohepatitis (NASH) in splanchnic and hepatic FFA and VLDL-triglycerides (VLDL-TG) balances. The study involved 17 obese men with biopsy-proven NAFLD (9 with NASH and 8 with simple steatosis). We used hepatic vein catheterization in combination with [3H]palmitate and [14C]VLDL-TG tracers to measure splanchnic palmitate and VLDL-TG uptake and release rates during basal and hyperinsulinemic conditions. Indocyanine green was used to measure splanchnic plasma flow. Splanchnic palmitate uptake was similar in the two groups and significantly reduced during hyperinsulinemia (NASH: 62 (48-77) vs. 38 (18-58) µmol/min; simple steatosis: 62 (46-78) vs. 45 (25-65) µmol/min, mean (95% CI), basal vs. clamp periods, respectively, p = 0.02 time-effect). Splanchnic palmitate release was also comparable between groups and non-significantly diminished during hyperinsulinemia. The percent palmitate delivered to the liver originating from visceral adipose tissue (VAT) lipolysis was similar and unchanged by hyperinsulinemia. Splanchnic uptake and release of VLDL-TG were similar between groups. Hyperinsulinemia suppressed VLDL-TG release (p <0.05 time-effect) in both groups. Insulin mediated glucose disposal was similar in the two groups (p = 0.54). IN CONCLUSIONS: Obese men with NASH and simple steatosis have similar splanchnic uptake and release of FFA and VLDL-TG and a similar proportion of FFA from VAT lipolysis delivered to the liver. These results suggest that FFA and VLDL-TG splanchnic balances are unaffected by NAFLD severity.

Impaired Glucagon-Mediated Suppression of VLDL-Triglyceride Secretion in Individuals With Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD).

Individuals with metabolic dysfunction-associated fatty liver disease (MAFLD) have elevated plasma lipids as well as glucagon, although glucagon suppresses hepatic VLDL-triglyceride (TG) secretion. We hypothesize that the sensitivity to glucagon in hepatic lipid metabolism is impaired in MAFLD. We recruited 11 subjects with severe MAFLD (MAFLD+), 10 with mild MAFLD (MAFLD-), and 7 overweight control (CON) subjects. We performed a pancreatic clamp with a somatostatin analog (octreotide) to suppress endogenous hormone production, combined with infusion of low-dose glucagon (0.65 ng/kg/min, t = 0-270 min, LowGlucagon), followed by high-dose glucagon (1.5 ng/kg/min, t = 270-450 min, HighGlucagon). VLDL-TG and glucose tracers were used to evaluate VLDL-TG kinetics and endogenous glucose production (EGP). HighGlucagon suppressed VLDL-TG secretion compared with LowGlucagon. This suppression was markedly attenuated in MAFLD subjects compared with CON subjects (MAFLD+: 13% ± [SEM] 5%; MAFLD-: 10% ± 3%; CON: 36% ± 7%, P < 0.01), with no difference between MAFLD groups. VLDL-TG concentration and VLDL-TG oxidation rate increased between LowGlucagon and HighGlucagon in MAFLD+ subjects compared with CON subjects. EGP transiently increased during HighGlucagon without any difference between the three groups. Individuals with MAFLD have a reduced sensitivity to glucagon in the hepatic TG metabolism, which could contribute to the dyslipidemia seen in MAFLD patients. ClinicalTrials.gov: NCT04042142.

Bis-choline tetrathiomolybdate prevents copper-induced blood-brain barrier damage.

In Wilson disease, excessive copper accumulates in patients' livers and may, upon serum leakage, severely affect the brain according to current viewpoints. Present remedies aim at avoiding copper toxicity by chelation, for example, by D-penicillamine (DPA) or bis-choline tetrathiomolybdate (ALXN1840), the latter with a very high copper affinity. Hence, ALXN1840 may potentially avoid neurological deterioration that frequently occurs upon DPA treatment. As the etiology of such worsening is unclear, we reasoned that copper loosely bound to albumin, that is, mimicking a potential liver copper leakage into blood, may damage cells that constitute the blood-brain barrier, which was found to be the case in an in vitro model using primary porcine brain capillary endothelial cells. Such blood-brain barrier damage was avoided by ALXN1840, plausibly due to firm protein embedding of the chelator bound copper, but not by DPA. Mitochondrial protection was observed, a prerequisite for blood-brain barrier integrity. Thus, high-affinity copper chelators may minimize such deterioration in the treatment of neurologic Wilson disease.

Metformin Stimulates Intestinal Glycolysis and Lactate Release: A single-Dose Study of Metformin in Patients With Intrahepatic Portosystemic Stent.

The pharmacodynamic effects of metformin remain elusive, but several lines of evidence suggest a critical role of direct effects in the gastrointestinal (GI) tract. We investigated if metformin stimulates intestinal glucose metabolism and lactate release in the prehepatic circulation. We included eight patients with transjugular intrahepatic portosytemic stent in an open label study. Portal and arterialized peripheral blood was obtained before and 90 minutes after ingestion of 1,000 mg metformin. Metformin increased lactate concentrations by 23% (95% confidence interval (CI): 6-40) after 90 minutes in the portal vein. The plasma concentration of glucose, insulin, and C-peptide was higher in the portal vein compared with arterialized blood (P < 0.05, all) and was lowered at both sampling sites following metformin ingestion (P < 0.01, all). Plasma concentration of GLP-1 was 20% (95% CI: 2-38) higher in the portal vein at baseline and metformin increased the concentration with 11% (1.5 pM, P = 0.05). The median concentration of growth differentiation factor 15 was 10% (95% CI: 1-19) higher in the portal vein compared with arterialized blood. Ninety minutes after metformin administration, the median portal vein concentration increased to around 3,000 ng/mL with a mean portal/arterial ratio of 1.5 (95% CI: 1.2-1.8). Non-targeted metabolomics showed that metformin acutely affected benzoate-hippurate metabolism. A single-dose of metformin directly affects substrate metabolism in the upper GI tract in humans with direct stimulation of nonoxidative glucose metabolism. These data suggest glucose lowering effects of metformin can be intrinsically linked with the GI tract without hepatic uptake of the drug.

Interferon lambda 4 genotype and pathway in alcoholic hepatitis.

OBJECTIVES: Single nucleotide polymorphisms within the interferon lambda 4 (IFNL4) gene influence liver inflammation and fibrosis in chronic liver disease. We investigated whether this is also the case during acute liver disease, alcoholic hepatitis. We, therefore, related variants within the IFNL4 gene to the clinical course of acute alcoholic hepatitis, and characterized the activation state of the IFN lambda system in these patients. METHODS: In this pilot study, 58 patients with alcoholic hepatitis were genotyped for the rs368234815IFNL4 single nucleotide polymorphism (deltaG, deltaG/TT: IFN lambda 4 positive, TT/TT: IFN lambda 4 negative). The genotypes were related to mortality, infection and inflammation and expression of the IFNL receptor 1 and IFN inducible genes were measured in liver and peripheral leukocytes. RESULTS: Amongst the alcoholic hepatitis patients who died, the IFN negative patients live longer after diagnosis, and also the IFN negative patients tended to have an overall short-term survival benefit compared to IFN lambda positive patients (p = .058). The IFN lambda 4 negative patients at diagnosis had fewer circulating monocytes and lower plasma soluble CD163. The patients with alcoholic hepatitis had reduced expression of the IFNL receptor 1in both liver and blood compared with healthy controls. In blood, the expression of IFN stimulated genes was lower than in healthy controls and most so in the patients, who died. CONCLUSIONS: The IFN lambda 4 pathway seems involved in the acute disease processes of alcoholic hepatitis and patients without IFN lambda expression seem to have a short-term survival benefit.

Liver-related effects of chronic hepatitis C antiviral treatment.

More than five years ago, the treatment of hepatitis C virus infection was revolutionized with the introduction of all-oral direct-acting antiviral (DAA) drugs. They proved highly efficient in curing patients with chronic hepatitis C (CHC), including patients with cirrhosis. The new DAA treatments were alleged to induce significant improvements in clinical outcome and prognosis, but the exact cause of the expected benefit was unclear. Further, little was known about how the underlying liver disease would be affected during and after viral clearance. In this review, we describe and discuss the liver-related effects of the new treatments in regards to both pathophysiological aspects, such as macrophage activation, and the time-dependent effects of therapy, with specific emphasis on inflammation, structural liver changes, and liver function, as these factors are all related to morbidity and mortality in CHC patients. It seems clear that antiviral therapy, especially the achievement of a sustained virologic response has several beneficial effects on liver-related parameters in CHC patients with advanced liver fibrosis or cirrhosis. There seems to be a time-dependent effect of DAA therapy with viral clearance and the resolution of liver inflammation followed by more discrete changes in structural liver lesions. These improvements lead to favorable effects on liver function, followed by an improvement in cognitive dysfunction and portal hypertension. Overall, the data provide knowledge on the several beneficial effects of DAA therapy on liver-related parameters in CHC patients suggesting short- and long-term improvements in the underlying disease with the promise of an improved long-term prognosis.

Computing the Pathogenicity of Wilson's Disease ATP7B Mutations: Implications for Disease Prevalence.

Genetic variations in the gene encoding the copper-transport protein ATP7B are the primary cause of Wilson's disease. Controversially, clinical prevalence seems much smaller than the prevalence estimated by genetic screening tools, causing fear that many people are undiagnosed, although early diagnosis and treatment is essential. To address this issue, we benchmarked 16 state-of-the-art computational disease-prediction methods against established data of missense ATP7B mutations. Our results show that the quality of the methods varies widely. We show the importance of optimizing the threshold of the methods used to distinguish pathogenic from nonpathogenic mutations against data of clinically confirmed pathogenic and nonpathogenic mutations. We find that most methods use thresholds that predict too many ATP7B mutations to be pathogenic. Thus, our findings explain the current controversy on Wilson's disease prevalence because meta-analysis and text search methods include many computational estimates that lead to higher disease prevalence than clinically observed. As proteins and diseases differ widely, a one-size-fits-all threshold cannot distinguish pathogenic and nonpathogenic mutations efficiently, as shown here. We also show that amino acid changes with small evolutionary substitution probability, mainly due to amino acid volume, are more associated with the disease, implying a pathological effect on the conformational state of the protein, which could affect copper transport or adenosine triphosphate recognition and hydrolysis. These findings may be a first step toward a more quantitative genotype-phenotype relationship of Wilson's disease.

Muscle metabolism and whole blood amino acid profile in patients with liver disease.

OBJECTIVE: Branched-chain amino acids (BCAA) are used in liver cirrhosis to promote protein synthesis, support ammonia detoxification, and treat hepatic encephalopathy. Cirrhosis leads to subnormal BCAA plasma concentrations and studies indicate that levels are decreased due to their role in muscle ammonia removal. Muscle contribution has not been fully elucidated. We studied muscle amino acid metabolism in six healthy subjects, 13 cirrhosis patients and six patients with an episode of alcoholic hepatitis. METHODS: Subjects had catheters inserted into the femoral artery and vein to obtain arterial (A) and venous (V) concentrations of amino acids (µmol/L blood). RESULTS: BCAA concentrations were lower in patients with cirrhosis compared to healthy subjects (p < 0.05) with no difference between patients with alcoholic hepatitis and the other groups. Muscle BCAA uptake was variable and on average higher in patients with alcoholic hepatitis and patients with stable cirrhosis compared to healthy subjects (mean A-V difference 0.5 and 32 vs. - 12 µmol/L blood) (p = 0.22). The release of aromatic amino acids (AAA) was comparable in the three groups (P > 0.30). The BCAA/AAA (Fischer's ratio) was lower in patients with cirrhosis and patients with alcoholic hepatitis compared to healthy subjects (mean 1.65, 1.17 and 2.73, both p < 0.05) and it was negatively correlated to the Child-Pugh score (p < 0.05). CONCLUSIONS: Patients with liver disease have lower BCAA and higher AAA blood concentrations compared to healthy subjects. The trend towards an increased muscle uptake of BCAA may have contributed but this was not significant.

Circulating mannan-binding lectin, M-, L-, H-ficolin and collectin-liver-1 levels in patients with acute liver failure.

BACKGROUND & AIMS: The complement system is activated in liver diseases including acute liver failure (ALF); however, the role of the lectin pathway of complement has scarcely been investigated in ALF. The pathway is initiated by soluble pattern recognition molecules: mannan-binding lectin (MBL), M-, L-, and H-ficolin and collectin-liver-1 (CL-L1), which are predominantly synthesized in the liver. We aimed to study lectin levels in ALF patients and associations with clinical outcome. METHODS: Serum samples from 75 patients enrolled by the US ALF Study Group were collected on days 1 and 3. We included 75 healthy blood donors and 20 cirrhosis patients as controls. Analyses were performed using sandwich-type immunoassays (ELISA, TRIFMA). RESULTS: At day 1, the MBL level in ALF patients was 40% lower compared with healthy controls {[median (interquartile range) 0.72 µg/ml(0.91) vs. 1.15 (1.92)(P = 0.02]}, and increased significantly by day 3 [0.83 µg/ml(0.94)(P = 0.01)]. The M-ficolin level was 60% lower [0.54 µg/ml(0.50) vs. 1.48(1.01)(P < 0.0001)]. The CL-L1 level at day 1 was slightly higher compared with healthy controls [3.20 µg/ml(2.37) vs. 2.64(0.72)(P = 0.11)]; this was significant at day 3 [3.35(1.84)(P = 0.006)]. H- and L-ficolin levels were similar to healthy controls. Spontaneous ALF survivors had higher levels of MBL at day 1 [0.96 µg/ml(1.15) vs. 0.60(0.60)(P = 0.02)] and lower levels of L-ficolin by day 3 compared with patients who died or were transplanted [1.61 µg/ml(1.19) vs. 2.17(2.19)(P = 0.02)]. CONCLUSION: We observed significant dynamics in lectin levels in ALF patients, which may suggest they play a role in ALF pathogenesis. High MBL and low L-ficolin levels are associated with survival.

Changes in the levels of mannan-binding lectin and ficolins during head-down tilted bed rest.

BACKGROUND: Spaceflight studies and ground-based analogues of microgravity indicate a weakening of human immunity. Mannan-binding lectin (MBL) and H-, L-, and M-ficolin together constitute the lectin pathway and mediate the clearance of pathogens through complement activation. We hypothesized that simulated microgravity may weaken human innate immune functions and studied the impact of 6° head-down tilted bed rest (HDT) for 21 d on MBL and ficolin levels. METHODS: Within a 6-mo period, seven men underwent two periods of HDT. Blood samples were analyzed for MBL, H-, L-, and M-ficolin, mannose-binding lectin-associated protein of 44 kDa (MAp44), and collectin liver 1 (CL-L1) by time-resolved immunofluorometric assays (TRIFMA). RESULTS: We observed well-defined individual preintervention levels of MBL and ficolins. Remarkably similar intraindividual changes occurred for MBL and MBL levels decreased (mean 282 ng · ml⁻¹) in the recovery phase. Conversely, CL-L1, a protein with MBL-like properties, increased (mean 102 ng · ml⁻¹) during the recovery phase. M-ficolin increased (mean 79 ng · ml⁻¹) within the first 2 d of HDT, followed by a decrease (mean 112 ng · ml⁻¹) during the recovery phase. L-ficolin increased (mean 304 ng · ml⁻¹) during HDT, while H-ficolin was essentially unaffected. MAp44, a down-regulator of the lectin pathway, decreased initially (mean 78 ng · ml⁻¹) in the recovery phase followed by an increase (mean 131 ng · ml⁻¹). DISCUSSION: Alterations in MBL and ficolin levels were modest and with our current knowledge do not lead to overt immunodeficiency. Pronounced changes occurred when the subjects resumed the upright position. In selected individuals, these changes appear to be a conserved response to HDT.

A soluble form of the macrophage-related mannose receptor (MR/CD206) is present in human serum and elevated in critical illness.

BACKGROUND: This study tests the hypothesis that the mannose receptor (MR/CD206), which is expressed primarily by macrophages and dendritic cells, can be found in a soluble form (sMR, sMR) in human serum. Furthermore, we wished to establish and validate an enzyme-linked immunosorbent assay (ELISA) for sMR and to perform initial studies exploring the potential of sMR as a biomarker. METHODS: Western blotting identified a single band of approximately 170 kDa in human serum, and MALDI MS/MS of the purified protein confirmed it to be sMR. An ELISA was established and validated with a measurement range of 1-256 µg/L. RESULTS: The 95% reference interval was 0.10-0.43 mg/L based on measurements of serum samples from healthy individuals (n=217). Samples from hospitalised patients (n=219) revealed that more than 50% of patients had concentrations above 0.43 mg/L. Very high concentrations (up to 6.2 mg/L) were observed in critically ill patients with sepsis and/or severe liver disease. CONCLUSIONS: This study documents, for the first time, the presence of sMR in human serum and describes an optimised ELISA suitable for quantitative measurements. Levels of sMR are strongly elevated in several disease states, including sepsis and liver disease, and the protein therefore shows promise as a new biomarker.

Increased levels of circulating Th17 cells in quiescent versus active Crohn's disease.

BACKGROUND AND AIMS: Th17 cells, a subset of CD4+ T cells that produce interleukin (IL)-17A, IL-17F, IL-21, IL-22, IL-26, and the chemokine CCL20 are critically involved in the mucosal inflammation observed in Crohn's disease (CD). However, their role as mediators of inflammation in CD has been questioned by a recent clinical trial in which anti-IL-17A (secukinumab) treatment was ineffective. Besides being pro-inflammatory, Th17-related cytokines mediate mucosal protective functions. We aimed to investigate the role of Th17 cells in CD inflammation. METHODS: Blood samples from 26 patients with active CD and 10 healthy controls (HC) were analyzed for levels of IL-17A-, IL-21- and IL-22-producing CD45RO+CD4+ T cells using multicolor flow cytometry. Samples were analyzed before and during adalimumab treatment to compare intra-individual changes during active and quiescent disease. RESULTS: CD patients had statistically significantly higher levels of IL-17-A-, IL-21- and IL-22-producing CD45RO+CD4+ T cells in both active and quiescent disease compared with HC. Baseline levels of IL-21 and IL-22 producing CD45RO+CD4+ T cells correlated inversely with mucosal inflammation estimated by fecal calprotectin. Patients who responded to adalimumab treatment demonstrated a 2- to 3-fold increase in levels of IL-17A- and IL-21-producing CD45RO+CD4+ T cells in quiescent disease compared with active disease. CONCLUSION: Our data support the involvement of Th17 cells and IL-21- and IL-22-producing CD45RO+CD4+ T cells in CD. Because patients had higher levels in quiescent disease compared with active CD, we question whether Th17 cells are promoters of inflammation. Instead, Th17 cells may counterbalance inflammation and maintain gut homeostasis.

Effects of insulin-like growth factor-I administration on in vivo regulation of urea synthesis in normal subjects and patients with cirrhosis.

BACKGROUND: The anabolic effects of insulin-like growth factor-I (IGF-I) may involve a decrease of hepatic nitrogen (N) clearance, but this has never been studied in humans. Patients with cirrhosis have low levels of IGF-I and might benefit from IGF-I therapy. Conversely, a possible decrease in hepatic N clearance by IGF-I could increase the risk of hepatic encephalopathy. AIMS: To examine the effects of 1-week IGF-I administration on the functional hepatic N clearance (FHNC), viz. the linear slope of the relationship between blood-α-amino-N concentration and urea-N synthesis rate as controlled by an infusion of alanine. METHODS: A randomized sequence-crossover placebo-controlled study. Eight healthy volunteers and eight patients with alcoholic cirrhosis received injections of saline or IGF-I twice daily (50 µg/kg) for 7 days. RESULTS: IGF-I levels at baseline were lower in the patients than those in the controls. The IGF-I treatment normalized patient levels and caused an increase in the controls to supra-physiological levels. FHNC was lower in patients compared with healthy subjects (23.0 vs 36.5 L/h, P=0.03). IGF-I treatment reduced FHNC by 30% in healthy subjects (from 36.5 to 25.7 L/h, P = 0.02), whereas no effect was found in the patients. CONCLUSION: IGF-I downregulates urea synthesis in normal subjects. This may be part of the explanation behind the anabolic effects of IGF-I. The normalization of IGF-I in cirrhosis patients without an effect on urea synthesis implies that the patients were resistant to IGF-I with regard to reduction of hepatic amino-N elimination. IGF-I treatment of cirrhosis patients evidently carries no risk of N accumulation.

Tumor necrosis factor-alpha acutely up-regulates urea synthesis in vivo in rats--a hepatic component of inflammatory catabolism?

BACKGROUND: Catabolism is a serious problem in patients with active inflammation. The tissue nitrogen (N) depletion is related to increased hepatic capacity for elimination of N via conversion of amino-N into urea-N. This is caused by the inflammatory process, but the mediators responsible are unknown. Tumor necrosis factor-alpha (TNF-alpha) plays a key role in inflammation, and we hypothesized that TNF-alpha up-regulates urea synthesis. METHODS: We examined the in vivo capacity of urea-N synthesis (CUNS) and mRNA levels of urea cycle enzyme genes 3 h after TNF-alpha injection in rats. Circulating concentrations of glucagon, corticosterone, insulin, glucose, cytokines and acute phase proteins and their liver tissue gene expressions were measured. RESULTS: TNF-alpha increased CUNS by 40% (p=0.03) despite decreased urea-cycle enzyme gene expression. TNF-alpha increased interleukin 6 (IL-6) (p < 0.001); circulating acute phase proteins were unchanged. CONCLUSION: TNF-alpha in rats caused an acute up-regulation of the in vivo capacity of urea synthesis which may promote loss of nitrogen from the body and catabolism. The results indicate that TNF-alpha has a post-transcriptional effect on regulation of urea synthesis that is independent of the acute phase protein synthesis. Effects of IL-6 may be involved.