Chronotypology and melatonin alterations in minimal hepatic encephalopathy

The Glymphatic System May Play a Vital Role in the Pathogenesis of Hepatic Encephalopathy: A Narrative Review

Hepatic encephalopathy (HE) is a neurological complication of liver disease resulting in cognitive, psychiatric, and motor symptoms. Although hyperammonemia is a key factor in the pathogenesis of HE, several other factors have recently been discovered. Among these, the impairment of a highly organized perivascular network known as the glymphatic pathway seems to be involved in the progression of some neurological complications due to the accumulation of misfolded proteins and waste substances in the brain interstitial fluids (ISF). The glymphatic system plays an important role in the clearance of brain metabolic derivatives and prevents aggregation of neurotoxic agents in the brain ISF. Impairment of it will result in aggravated accumulation of neurotoxic agents in the brain ISF. This could also be the case in patients with liver failure complicated by HE. Indeed, accumulation of some metabolic by-products and agents such as ammonia, glutamine, glutamate, and aromatic amino acids has been reported in the human brain ISF using microdialysis technique is attributed to worsening of HE and correlates with brain edema. Furthermore, it has been reported that the glymphatic system is impaired in the olfactory bulb, prefrontal cortex, and hippocampus in an experimental model of HE. In this review, we discuss different factors that may affect the function of the glymphatic pathways and how these changes may be involved in HE.

Hepatic Encephalopathy and Melatonin

Hepatic encephalopathy (HE) is a severe metabolic syndrome linked with acute/chronic hepatic disorders. HE is also a pernicious neuropsychiatric complication associated with cognitive decline, coma, and death. Limited therapies are available to treat HE, which is formidable to oversee in the clinic. Thus, determining a novel therapeutic approach is essential. The pathogenesis of HE has not been well established. According to various scientific reports, neuropathological symptoms arise due to excessive accumulation of ammonia, which is transported to the brain via the blood–brain barrier (BBB), triggering oxidative stress and inflammation, and disturbing neuronal-glial functions. The treatment of HE involves eliminating hyperammonemia by enhancing the ammonia scavenging mechanism in systemic blood circulation. Melatonin is the sole endogenous hormone linked with HE. Melatonin as a neurohormone is a potent antioxidant that is primarily synthesized and released by the brain’s pineal gland. Several HE and liver cirrhosis clinical studies have demonstrated impaired synthesis, secretion of melatonin, and circadian patterns. Melatonin can cross the BBB and is involved in various neuroprotective actions on the HE brain. Hence, we aim to elucidate how HE impairs brain functions, and elucidate the precise molecular mechanism of melatonin that reverses the HE effects on the central nervous system.

Comprehensive Overview of Sleep Disorders in Patients with Chronic Liver Disease

The impact of sleep disorders (SDs) on patients with chronic liver diseases (CLD) is tremendous. SDs are frequently encountered among these patients and interfere with their quality of life. This review aims to present the data available so far about the prevalence, phenotypes, and proposed pathophysiological mechanisms of SDs in CLD. Moreover, we proposed to search the literature regarding the most reliable methods to assess SDs and the possible therapeutic options in patients with CLD. The main results of this review show that when it comes to prevalence, the percentages reported vary widely between studies performed among populations from the USA or Europe and those coming from Asian countries. Furthermore, it has been proven that SDs may also be present in the absence of neurocognitive disorders attributable to hepatic encephalopathy (HE), which contradicts traditional suppositions where SDs were considered part of the clinical scenario of HE. Currently, there are no specific recommendations or protocols to assess SDs in CLD patients and data about the therapeutic management are limited. Taking into consideration their impact, a protocol for diagnosing and managing SDs should be developed and included in the daily practice of hepatologists.

Sleep disorder in patients with chronic liver disease: a narrative review

Sleep disturbance is a common feature of chronic liver disease (CLD) with impact on health-related quality of life; 60-80% of patients with CLD report subjective poor sleep; frequent presentations of sleep disturbance include insomnia, reduced sleep efficiency, increased sleep latency, reduced time in rapid eye movement (REM) sleep, restless leg syndrome and excessive daytime sleepiness (EDS). Key contributors to sleep disturbance include hepatic encephalopathy (HE) and circadian rhythm imbalance due to altered melatonin metabolism. Specific conditions causing CLD, such as non-alcoholic fatty liver disease (NAFLD), chronic viral hepatitis and primary biliary cholangitis (PBC) result in different types of sleep disturbance, and the treatment of these conditions can often also lead to sleep disturbance. There are currently limited management options for sleep disturbance in CLD. Obstructive sleep apnoea (OSA) is a common condition that causes chronic intermittent hypoxia due to airway collapse during sleep. This chronic intermittent hypoxia appears to contribute to the development of NAFLD. The presence of reactive oxygen species and the overexpression of hypoxia inducible factor 1-alpha secondary to hypoxia may be responsible for the second 'hit' of the 'two-hit' hypothesis of NAFLD. Treatment of the intermittent hypoxia with continuous positive airway pressure therapy has limited efficacy against liver dysfunction. There remain many outstanding areas of investigation in the management of sleep disturbance in CLD, and of liver dysfunction in OSA.

Serum melatonin in dogs with congenital portosystemic shunting, with and without hepatic encephalopathy

BACKGROUND

Melatonin is a hormone produced and secreted primarily by the pineal gland and mainly metabolised in the liver. Increased melatonin concentrations have been reported in human cirrhosis and hepatic encephalopathy (HE), a syndrome of neurological dysfunction. The pathogenesis of canine HE is incompletely understood. Melatonin has been hypothesised as a contributor to the development of HE. The aim of this study was to investigate whether serum melatonin concentrations are increased in canine congenital portosystemic shunting (cPSS), with and without HE.

METHODS

Medical records were retrospectively reviewed, for which archived (-80°C) serum samples were available. A canine competitive ELISA was used to measure melatonin in two cohorts: dogs with a final diagnosis of cPSS (n=23) with and without clinical signs of HE, and healthy dogs (n=15).

RESULTS

Melatonin concentrations were not significantly different (P=0.81) between healthy controls (median 27.2 pg/mL, range 19.8-161.5 pg/mL) and dogs with cPSS (median 25.7 pg/mL, range 18.5-244.9 pg/mL). Serum melatonin did not differ between cPSS patients with and without clinical signs of HE (P>0.99). No correlation was found between serum melatonin and blood ammonia (Spearman rank correlation coefficient, r_s =-0.41, P=0.08).

CONCLUSION

Serum melatonin is not increased in canine cPSS with and without HE. We found no evidence that altered melatonin metabolism plays a role in the pathogenesis of cPSS-associated HE.

Treatment with Melatonin Improves Cognitive Behavior and Motor Skills in a Rat Model of Liver Fibrosis

INTRODUCTION AND AIM

Patients with liver cirrhosis (LC) and minimal hepatic encephalopaty have a higher accident rate. LC impairs the normal sleep-awake cycle and produces disturbances in behavior, cognition and motor skills. Abnormal melatonin (MT) levels have also been identified in LC. Administration of MT may regulate circadian rhythms and prevent the oxidative damage. We studied the effects of MT on spatial memory acquisition (SMA) and motor skills in a liver fibrosis model (LF)s.

MATERIALS AND METHODS

Forty-five rats, divided into 4 groups. [G1: LF; G2: LF + MT; G3: MT; G4: Healthy control (HC)]. LF was induced by carbon tetrachloride intraperitoneal injection (0.2 mL/kg) for 5 months. MT was administered during 5 weeks (0.4 mg/kg/day). SMA was evaluated by using the Morris Water Maze protocol where the escape latency (EL) and mean speed were measured. Data were registered by SMART®.

RESULTS

The EL measurement analyzed by two way ANOVA: cirrhosis presented a higher EL than controls or those treated with MT suggesting impaired memory acquisition which is rescued by MT treatment. The mean speed analysis revealed that LF presented higher speed than LF+MT or HC, suggesting that LF affects motor skills, which are improved by MT. To discard whether EL is affected by altered motor skills in LF treated with MT, we compared the average EL and speed between days 2 and 6 of the training protocol. Speed was not improved during the trials unlike EL, suggesting that memory acquisition is independent of motor skills.

CONCLUSION

These findings suggest that MT improves cognition and motor skills in the LF model.

Morning Bright Light Treatment for Sleep-Wake Disturbances in Primary Biliary Cholangitis: A Pilot Study

Patients with Primary Biliary Cholangitis (PBC) exhibit delayed sleep-wake habits, disturbed night sleep and daytime sleepiness/fatigue. Such combination of symptoms is reminiscent of delayed sleep-wake phase disorder (DSPD), which benefits from morning light treatment. The aim of the present pilot study was to test the effect of morning light treatment in a group of 13 well-characterized patients with PBC [all females; (mean ± SD) 53 ± 10 years]. Six healthy individuals (4 females, 57 ± 14 years) and 7 patients with cirrhosis (1 female, 57 ± 12 years) served as controls and diseased controls, respectively. At baseline, all participants underwent an assessment of quality of life, diurnal preference, sleep quality/timing (subjective plus actigraphy), daytime sleepiness, and urinary 6-sulphatoxymelatonin (aMT6s) rhythmicity. Then they underwent a 15-day course of morning bright light treatment, immediately after getting up (light box, 10,000 lux, 45 min) whilst monitoring sleep-wake patterns and aMT6s rhythmicity. At baseline, both patients with PBC and patients with cirrhosis had significantly worse subjective sleep quality compared to controls. In patients with PBC, light treatment resulted in an improvement in subjective sleep quality and a reduction in daytime sleepiness. In addition, both their sleep onset and get-up time were significantly advanced. Finally, the robustness of aMT6s rhythmicity (i.e., strength of the cosinor fit) increased after light administration but post-hoc comparisons were not significant in any of the groups. In conclusion, a brief course of morning bright light treatment had positive effects on subjective sleep quality, daytime sleepiness, and sleep timing in patients with PBC. This unobtrusive, side-effect free, non-pharmacological treatment is worthy of further study.

Melatonin secretion and metabolism in patients with hepatic encephalopathy

BACKGROUND AND AIM

The rhythm of melatonin secretion and its blood level changes in cirrhotic patients, but the causes of these alterations have not been sufficiently appreciated. The aim of study was to estimate the dependence between melatonin secretion and metabolism and the severity of hepatic encephalopathy.

METHODS

The study included 75 alcoholic cirrhotic patients (A, B, C) with hepatic insufficiency and 25 healthy subjects (group K). Three groups of patients were identified, 25 patients each, with grade 1, 2, and 3 hepatic encephalopathy according to West-Haven Scale. Immunoenzymatic method was used to measure serum melatonin (at 02:00 h and 09:00 h) level and 6-sulfatoxymelatonin (6-HMS) excretion in the urine (during night and day).

RESULTS

Nocturnal serum melatonin levels (pg/mL) in groups were: K-57.1 ± 11.4, A-38.5 ± 11.2, B-53.4 ± 17.9, C-79.5 ± 27.9 (P < 0.01); whereas diurnal levels were: K-10.9 ± 3.5, A-33.5 ± 12.0, B-53.8 ± 23.1, C-98.5 ± 34.6 (P < 0.01). Similar differences were found in the evaluation of 6-HMS excretion (μg/9 h) in urine at night: group K-23.4 ± 14.4, A-16.6 ± 5.4, B-14.3 ± 6.2 (P < 0.01), C-3.3 ± 1.5 (P < 0.001). Diurnal 6-HMS excretion (μg/15 h) was lower only in group C and it was respectively: K-6.9 ± 3.4, A-7.1 ± 1.7, B-7.6 ± 1.7, C-4.3 ± 2.2 (P < 0.001). Serum ammonia concentrations (μg/dL) were: group K-30.4 ± 8.9, A-51.8 ± 25.4 (P < 0.05), B-73.0 ± 29.8 (P < 0.001), C-107.5 ± 34.8 (P < 0.001). No correlation between melatonin and ammonia levels in all groups was found.

CONCLUSIONS

The elevated melatonin blood levels both at night and day may account for some of the clinical manifestations of hepatic encephalopathy (daytime sleepiness, fatigue).

Melatonin levels in serum and ascitic fluid of patients with hepatic encephalopathy

Cirrhotic patients exhibit disturbed melatonin homeostasis, which may lead to sleep disturbances, but an influence on the hepatic encephalopathy has not been elucidated. Aim. In the present study, the association of melatonin levels in serum and ascitic fluid and ammonia concentration related to the intensity of hepatic encephalopathy (HE) was investigated. Material and Methods. The study included 90 alcoholic patients with hepatic encephalopathy and 30 healthy volunteers (C). Patients were divided in three groups according to 0–4 West-Haven Score: HE₁ (n = 28), HE₂ (n = 30), and HE₃ (n = 32). Melatonin was measured by radioimmune assay. Results. In fasting patients with hepatic encephalopathy we noted higher melatonin serum levels [pg/mL] than in healthy subjects groups: C—11.3 ± 3.9, HE₁ – 34.3 ± 12.2 (P < 0.01), HE₂—54.8 ± 23.9, and HE₃—119.8 ± 96.4 (P < 0.001). No correlation between melatonin and ammonia levels was found. Melatonin was detected in ascetic fluid in 24 patients of group HE₂ and 27 patients of group HE₂ of hepatic encephalopathy. Conclusions. Our results suggest that high blood levels of melatonin in cirrhotic liver patients may account for some of the clinical manifestations of hepatic encephalopathy, for example, daytime sleepiness, fatigue.