Cognitive dysfunction in early experimental metabolic dysfunction-associated steatotic liver disease is associated with systemic inflammation and neuroinflammation.

Background & Aims: Cognitive dysfunction is an increasingly recognised manifestation of metabolic dysfunction-associated steatotic liver disease (MASLD), but the mechanistic link remains unclear. The aim of this study was to investigate the hypothesis that experimental MASLD leads to cognitive dysfunction via systemic inflammation and neuroinflammation. Methods: Twenty male Sprague Dawley rats were randomised to a high-fat high-cholesterol (HFHC) diet to induce MASLD, or a standard diet (n = 10/group), for 16 weeks. Assessments included: MASLD severity (histology), neurobehaviour, inflammation (liver, plasma and cerebrospinal fluid), brain microglia and astrocyte activation, and synaptic density. Results: The HFHC diet induced MASLD with extensive steatosis and lobular inflammation without fibrosis. Several plasma cytokines were elevated (CXCL1, IL-6, IL-17, MIP-1α, MCP-1, IL-10; all p <0.05) and correlated with increases in hepatic chemokine gene expression. Cerebrospinal fluid concentrations of CXCL1 were elevated (p = 0.04). In the prefrontal brain cortex, we observed a 19% increase in microglial activation confirmed by Iba1 immunohistochemistry (p = 0.03) and 3H-PK11195 autoradiography (p <0.01). In parallel, synaptic density was reduced to 92%, assessed by 3H-UCB-J autoradiography (p <0.01). MASLD animals exhibited impaired memory to previously encountered objects in the novel object recognition test (p = 0.047) and showed depression-like behaviour evidenced by increased immobility time (p <0.01) and reduced swimming time (p = 0.03) in the forced swim test. Conclusions: Experimental non-fibrotic MASLD, as a model to reflect the early stage of human disease, results in cognitive impairment and depression-like behaviour. This is associated with an inflammatory phenotype not only in the liver but also in the plasma and brain, which together with diminished synaptic density, provides a pathophysiological link between liver disease and cognitive dysfunction in MASLD. Impact and implications: Cognitive dysfunction is an increasingly recognised comorbidity in patients with metabolic dysfunction-associated steatotic liver disease (MASLD), yet the underlying mechanisms remain unclear. This study provides evidence of impaired memory and depression-like symptoms in early experimental MASLD and indicates that hepatic inflammation may drive a systemic inflammatory response, resulting in neuroinflammation and reduced brain synaptic density. The evidence of impaired memory in MASLD and establishing its underlying pathophysiological link provides insights that could guide the development of potential new treatments for this increasingly common condition in people of working age. The study also emphasises the need to develop better tools for clinical cognitive testing, which will enable physicians to assess and manage brain dysfunction early in MASLD.

Non-alcoholic Fatty Liver Disease: Also a Disease of the Brain? A Systematic Review of the Preclinical Evidence.

Non-alcoholic fatty liver disease (NAFLD) currently affects 25% of the global adult population. Cognitive impairment is a recently recognised comorbidity impeding memory, attention, and concentration, affecting the patients' activities of daily living and reducing their quality of life. This systematic review provides an overview of the evidence for, and potential pathophysiological mechanisms behind brain dysfunction at a neurobiological level, in preclinical NAFLD. We performed a systematic literature search for animal models of NAFLD studying intracerebral conditions using PubMed, Embase and Scopus. We included studies that reported data on neurobiology in rodent and pig models with evidence of steatosis or steatohepatitis assessed by liver histology. 534 unique studies were identified, and 30 studies met the selection criteria, and were included. Findings of neurobiological changes were divided into five key areas: (1) neuroinflammation, (2) neurodegeneration, (3) neurotransmitter alterations, (4) oxidative stress, and (5) changes in proteins and synaptic density. Despite significant heterogeneity in the study designs, all but one study of preclinical NAFLD reported changes in one or more of the above key areas when compared to control animals. In conclusion, this systematic review supports an association between all stages of NAFLD (from simple steatosis to non-alcoholic steatohepatitis (NASH)) and neurobiological changes in preclinical models.

Psychometric methods for diagnosing and monitoring minimal hepatic encephalopathy -current validation level and practical use.

Hepatic encephalopathy (HE) is cerebral dysfunction caused by liver failure and inflicts 30-40% of patients with liver cirrhosis during their disease course. Clinically manifest HE is often preceded by minimal HE (MHE) - a clinically undetectable cognitive disturbance closely associated with loss of quality of life. Accordingly, detecting and treating MHE improve the patients' daily functioning and prevent HE-related hospital admissions. The scope of this review article is to create an overview of the validation level and usage of psychometric tests used to detect MHE: Portosystemic hepatic encephalopathy test, continuous reaction time test, Stroop EncephalApp, animal naming test, critical flicker frequency test, and inhibitory control test. Our work is aimed at the clinician or scientist who is about to decide on which psychometric test would fit best in their clinic, cohort, or study. First, we outline psychometric test validation obstacles and requirements. Then, we systematically approach the literature on each test and select well-conducted studies to answer the following questions:• Which percentage of patients with cirrhosis does the test deem as having MHE?• Is the test able to predict clinically manifest HE?• Is there a well-known test-retest variation and inter-observer variation?• Is the test able to detect a treatment response?• Is the test result affected by age, educational level, gender, or comorbidities?

The pathophysiology of Wilson's disease visualized: A human 64 Cu PET study.

BACKGROUND AND AIMS: Wilson's disease (WD) is a genetic disease with systemic accumulation of copper that leads to symptoms from the liver and brain. However, the underlying defects in copper transport kinetics are only partly understood. We sought to quantify hepatic copper turnover in patients with WD compared with heterozygote and control subjects using PET with copper-64 (64 Cu) as a tracer. Furthermore, we assessed the diagnostic potential of the method. APPROACH AND RESULTS: Nine patients with WD, 5 healthy heterozygote subjects, and 8 healthy controls were injected with an i.v. bolus of 64 Cu followed by a 90-min dynamic PET scan of the liver and static whole-body PET/CT scans after 1.5, 6, and 20 h. Blood 64 Cu concentrations were measured in parallel. Hepatic copper retention and redistribution were evaluated by standardized uptake values (SUVs). At 90 min, hepatic SUVs were similar in the three groups. In contrast, at 20 h postinjection, the SUV in WD patients (mean ± SEM, 31 ± 4) was higher than in heterozygotes (24 ± 3) and controls (21 ± 4; p < 0.001). An SUV-ratio of hepatic 64 Cu concentration at 20 and 1.5 h completely discriminated between WD patients and control groups (p < 0.0001; ANOVA). By Patlak analysis of the initial 90 min of the PET scan, the steady-state hepatic clearance of 64 Cu was estimated to be slightly lower in patients with WD than in controls (p = 0.04). CONCLUSIONS: 64 Cu PET imaging enables visualization and quantification of the hepatic copper retention characteristic for WD patients. This method represents a valuable tool for future studies of WD pathophysiology, and may assist the development of therapies, and accurate diagnosis.

[Christmas article: Footwear fashion amongst medical doctors - are clogs fashion or history?]

INTRODUCTION The medical costume has long been subject to interest and debate. In particular, the scene in footwear fashion amongst medical doctors (MDs) has transformed in recent years. The aim of this study was to investigate footwear trends in a specialized hospital setting. We hypothesized, that the footwear differs between 1) medical specialities, 2) senior and junior MDs, and 3) male and female MDs. METHODS In this crosssectional study, we observed the footwear fashion at morning conferences for seven medical specialities at Aarhus University Hospital. Data on sex, seniority, footwear type, presence of socks, and abrasion of footwear were noted for individual MDs. RESULTS In total, data on 153 MDs was registered. 48% wore clogs, 42% sneakers, and 9% sandals. There was a significant difference between the investigated specialities (p = 0.02) with rheumatologists and anaesthesiologists being the least in favour of clogs (15% and 19%) as opposed to radiologists, surgeons and gynaecologists (63%, 58% and 56%). Further, senior MDs preferred clogs more than junior MDs (p = 0.004), and seniority was associated with having worn-out shoes (OR = 4.4; 95% CI: 1.2 16.9). Finally, the footwear differed between male and female MDs (p = 0.005), however, this difference seemed primarily driven by the female preference for sandals. CONCLUSION The fashion in footwear is changing amongst MDs. The traditional clog is less preferred by the younger generation and in certain specialities. FUNDING none. TRIAL REGISTRATION Clinicaltrials.gov (NCT04740281).

Hepatic blood flow in adult Göttingen minipigs and pre-pubertal Danish Landrace x Yorkshire pigs.

The liver receives dual blood supply from the hepatic artery and portal vein. The pig is often used as an animal model in positron emission tomography (PET) and pharmacokinetic studies because of the possibility for extensive and direct blood sampling. In this study, we compared measurements of hepatic blood flow in 10 female adult Göttingen minipigs and 10 female pre-pubertal Danish Landrace x Yorkshire (DLY) pigs. Ultrasound transit time flow meter probes were placed around the hepatic artery and portal vein through open surgery, hepatic blood flow measurements were performed, and the liver was weighed. Total hepatic blood flow was on average 363 ± 131 mL blood/min in Göttingen minipigs and 988 ± 180 mL blood/min in DLY pigs (p < 0.001). The mean hepatic blood perfusion was 623 mL blood/min/mL liver tissue and 950 mL blood/min/mL liver tissue (p = 0.005), and the liver weight was 0.58 kg and 1.04 kg, respectively. The mean arterial flow fraction in Göttingen minipigs was 12 ± 7% and lower than in DLY pigs, where it was 24 ± 7% (p = 0.001). Using the gold standard for blood flow measurements, we found that both total hepatic blood flow and blood perfusion were significantly lower in Göttingen minipigs than in DLY pigs. The hepatic blood perfusion and arterial flow fraction in DLY pigs were comparable to normative values from humans. Differences in hepatic blood flow between adult Göttingen minipigs and humans should be considered when performing physiological liver studies in this model.

Cognitive Dysfunction in Non-Alcoholic Fatty Liver Disease-Current Knowledge, Mechanisms and Perspectives.

Non-alcoholic fatty liver disease (NAFLD) has emerged as the hepatic component of the metabolic syndrome and now seemingly affects one-fourth of the world population. Features associated with NAFLD and the metabolic syndrome have frequently been linked to cognitive dysfunction, i.e. systemic inflammation, vascular dysfunction, and sleep apnoea. However, emerging evidence suggests that NAFLD may be a cause of cognitive dysfunction independent of these factors. NAFLD in addition exhibits dysbiosis of the gut microbiota and impaired urea cycle function, favouring systemic ammonia accumulation and further promotes systemic inflammation. Such disruption of the gut-liver-brain axis is essential in the pathogenesis of hepatic encephalopathy, the neuropsychiatric syndrome associated with progressive liver disease. Considering the growing burden of NAFLD, the morbidity from cognitive impairment is expected to have huge societal and economic impact. The present paper provides a review of the available evidence for cognitive dysfunction in NAFLD and outlines its possible mechanisms. Moreover, the clinical challenges of characterizing and diagnosing cognitive dysfunction in NAFLD are discussed.

Obeticholic acid improves hepatic bile acid excretion in patients with primary biliary cholangitis.

BACKGROUND & AIMS: Obeticholic acid (OCA) is an agonist of the nuclear bile acid receptor farnesoid X receptor, which regulates hepatic bile acid metabolism. We tested whether OCA treatment would influence hepatic transport of conjugated bile acids in patients with primary biliary cholangitis (PBC) who responded inadequately to treatment with ursodeoxycholic acid (UDCA). METHODS: Eight UDCA-treated patients with PBC with alkaline phosphatase ≥1.5 times the upper limit of normal range participated in a double-blind, placebo-controlled study. While continuing on UDCA, the patients were randomised to two 3-month crossover treatment periods with placebo and OCA, in random order, separated by a 1-month washout period without study treatment. After each of the two treatment periods, we determined rate constants for transport of conjugated bile acids between blood, hepatocytes, biliary canaliculi, and bile ducts by positron emission tomography of the liver using the conjugated bile acid tracer [N-methyl-11C]cholylsarcosine (11C-CSar). The hepatic blood perfusion was measured using infusion of indocyanine green and Fick's principle. RESULTS: Compared with placebo, OCA increased hepatic blood perfusion by a median of 11% (p = 0.045), the unidirectional uptake clearance of 11C-CSar from blood into hepatocytes by a median of 11% (p = 0.01), and the rate constant for secretion of 11C-CSar from hepatocytes into biliary canaliculi by a median of 73% (p = 0.03). This resulted in an OCA-induced decrease in the hepatocyte residence time of 11C-CSar by a median of 30% (p = 0.01), from group median 11 min to 8 min. CONCLUSIONS: This study of UDCA-treated patients with PBC showed that, compared with placebo, OCA increased the hepatic transport of the conjugated bile acid tracer 11C-CSar, and thus endogenous conjugated bile acids, from hepatocytes into biliary canaliculi. As a result, OCA reduced the time hepatocytes are exposed to potentially cytotoxic bile acids. LAY SUMMARY: Primary biliary cholangitis is a chronic liver disease in which the small bile ducts are progressively destroyed. We tested whether the treatment with obeticholic acid (OCA) would improve liver excretion of bile acids compared with placebo in 8 patients with primary biliary cholangitis. A special scanning technique (PET scan) showed that OCA increased the transport of bile acids from blood to bile. OCA thereby reduced the time that potentially toxic bile acids reside in the liver by approximately one-third.

Hepatic regeneration following radiation-induced liver injury is associated with increased hepatobiliary secretion measured by PET in Göttingen minipigs.

Normal liver tissue is highly vulnerable towards irradiation, which remains a challenge in radiotherapy of hepatic tumours. Here, we examined the effects of radiation-induced liver injury on two specific liver functions and hepatocellular regeneration in a minipig model. Five Göttingen minipigs were exposed to whole-liver stereotactic body radiation therapy (SBRT) in one fraction (14 Gy) and examined 4-5 weeks after; five pigs were used as controls. All pigs underwent in vivo positron emission tomography (PET) studies of the liver using the conjugated bile acid tracer [N-methyl-11C]cholylsarcosine ([11C]CSar) and the galactose-analogue tracer [18F]fluoro-2-deoxy-D-galactose ([18F]FDGal). Liver tissue samples were evaluated histopathologically and by immunohistochemical assessment of hepatocellular mitosis, proliferation and apoptosis. Compared with controls, both the rate constant for secretion of [11C]CSar from hepatocytes into intrahepatic bile ducts as well as back into blood were doubled in irradiated pigs, which resulted in reduced residence time of [11C]CSar inside the hepatocytes. Also, the hepatic systemic clearance of [18F]FDGal in irradiated pigs was slightly increased, and hepatocellular regeneration was increased by a threefold. In conclusion, parenchymal injury and increased regeneration after whole-liver irradiation was associated with enhanced hepatobiliary secretion of bile acids. Whole-liver SBRT in minipigs ultimately represents a potential large animal model of radiation-induced liver injury and for testing of normal tissue protection methods.

Intravenous and oral copper kinetics, biodistribution and dosimetry in healthy humans studied by [64Cu]copper PET/CT.

PURPOSE: Copper is essential for enzymatic processes throughout the body. [64Cu]copper (64Cu) positron emission tomography (PET) has been investigated as a diagnostic tool for certain malignancies, but has not yet been used to study copper homeostasis in humans. In this study, we determined the hepatic removal kinetics, biodistribution and radiation dosimetry of 64Cu in healthy humans by both intravenous and oral administration. METHODS: Six healthy participants underwent PET/CT studies with intravenous or oral administration of 64Cu. A 90 min dynamic PET/CT scan of the liver was followed by three whole-body PET/CT scans at 1.5, 6, and 20 h after tracer administration. PET data were used for estimation of hepatic kinetics, biodistribution, effective doses, and absorbed doses for critical organs. RESULTS: After intravenous administration, 64Cu uptake was highest in the liver, intestinal walls and pancreas; the gender-averaged effective dose was 62 ± 5 µSv/MBq (mean ± SD). After oral administration, 64Cu was almost exclusively taken up by the liver while leaving a significant amount of radiotracer in the gastrointestinal lumen, resulting in an effective dose of 113 ± 1 µSv/MBq. Excretion of 64Cu in urine and faeces after intravenous administration was negligible. Hepatic removal kinetics showed that the clearance of 64Cu from blood was 0.10 ± 0.02 mL blood/min/mL liver tissue, and the rate constant for excretion into bile or blood was 0.003 ± 0.002 min- 1. CONCLUSION: 64Cu biodistribution and radiation dosimetry are influenced by the manner of tracer administration with high uptake by the liver, intestinal walls, and pancreas after intravenous administration, while after oral administration, 64Cu is rapidly absorbed from the gastrointestinal tract and deposited primarily in the liver. Administration of 50 MBq 64Cu yielded images of high quality for both administration forms with radiation doses of approximately 3.1 and 5.7 mSv, respectively, allowing for sequential studies in humans. TRIAL REGISTRATION NUMBER: EudraCT no. 2016-001975-59. Registration date: 19/09/2016.

Human biodistribution, dosimetry, radiosynthesis and quality control of the bile acid PET tracer [N-methyl-11C]cholylsarcosine.

INTRODUCTION: [N-methyl-11C]cholylsarcosine ([11C]CSar) is a tracer for imaging and quantitative assessment of intrahepatic cholestatic liver diseases and drug-induced cholestasis by positron emission tomography (PET). The purpose of this study is to determine whole-body biodistribution and dosimetry of [11C]CSar in healthy humans. The results are compared with findings in a patient with primary sclerosing cholangitis (PSC) and a patient with primary biliary cholangitis (PBC) as well as with preclinical findings in pigs. Radiosynthesis and quality control for preparation of [11C]CSar for clinical use are also presented. METHODS: Radiosynthesis and quality control of [11C]CSar were set up in compliance with Danish/European regulations. Both healthy participants (3 females, 3 males) and patients underwent whole-body PET/CT to determine the biodistribution of [11C]CSar. The two patients were under treatment with ursodeoxycholic acid at the time of the study. Dosimetry was estimated from the PET data using the Olinda 2.0 software. RESULTS: The radiosynthesis provided [11C]CSar in a solution ready for injection. The biodistribution studies revealed that gallbladder wall, small intestine, and liver were critical organs in both healthy participants and patients with the gallbladder wall receiving the highest dose (up to 0.5 mGy/MBq). The gender-averaged (±SD) effective dose for the healthy participants was 6.2 ±â€¯1.4 µSv/MBq. The effective dose for the PSC and the PBC patient was 5.2 and 7.0 µSv/MBq, respectively. CONCLUSION: A radiosynthesis for preparation of [11C]CSar for clinical use was developed and approved by the Danish Medicines Agency. The most critical organ was the gallbladder wall although the amount of [11C]CSar in the gallbladder was found to vary significantly between individuals. The estimated effective dose for humans was comparable to that estimated in anesthetized pigs although the absorbed dose estimates to some organs, such as the stomach, was different. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: [11C]CSar PET/CT enables detailed quantitative assessment of patients with cholestatic liver disease by tracing the separate hepatobiliary transport steps of endogenous bile acids. The present work offers a radiosynthetic method and dosimetry data suitable for clinical implementation of [11C]CSar.