Clinical characterization of patients with primary biliary cholangitis: A report from multiple Canadian centres.

Background: Primary biliary cholangitis (PBC) is a rare, chronic autoimmune, cholestatic liver disease affecting approximately 318 per million Canadians. There is limited information regarding the characterization of this patient population in Canada. Consequently, we aim to describe a cohort of PBC patients managed across liver centres serving this type of population. Methods: A cross-sectional examination of 1,125 PBC patient charts at 15 liver centres across Canada was conducted between January 2016 and September 2017. Results: Data from 1,125 eligible patients were collected from 7 Canadian provinces. The patient population was largely female (90.2%), had a median overall age of 61.3 years, and a median overall time since diagnosis of 6.4 years. Of the patients included in the study, 89% were on ursodeoxycholic acid (UDCA) therapy at a median dose of 14.0 mg/kg/day and 4.4% were previously treated with UDCA, whereas 6.6% were never treated with UDCA. Of the patients with available data (n = 1067), 289 (27.1%) presented with alkaline phosphatase (ALP) levels ≥200 IU/L and/or total bilirubin levels ≥21 µmol/L. Assessment of UDCA treatment response revealed that 26.6% and 38.3% of patients were inadequate responders according to the Toronto and Paris-II criteria, respectively. Mortality occurred in 1.2% (14) of patients, with liver-related adverse outcomes being more commonly observed in patients who discontinued UDCA compared to those who are currently on treatment (36.3% and 19.6%, respectively). Conclusion: This study showed that Canadian PBC patients present with demographics and features commonly reported in the literature for this disease. Over one third of PBC patients had inadequate response to UDCA treatment or were not currently being treated with UDCA. Consequently, there is a significant unmet therapeutic need in this Canadian PBC population.

The Antidepressant Mirtazapine Activates Hepatic Macrophages, Facilitating Pathogen Clearance While Limiting Tissue Damage in Mice.

Background and Aims: Mirtazapine is an atypical antidepressant with antagonist activity for serotonin and histamine receptors. Clinical and experimental evidence suggests that, in addition to treating depression, mirtazapine also alters liver innate immunity and suppresses immune-driven hepatic macrophage activation. Liver macrophages, Kupffer cells, represent the largest collection of fixed macrophages in the body and are critical in regulating hepatic immunity. In addition to their capacity to regulate inflammation, Kupffer cells are key sentinels for clearing blood-borne pathogens, preventing their dissemination within the body. This process involves pathogen capture, phagocytosis, and activation-induced killing via reactive oxygen species (ROS) production. Therefore, we speculated that mirtazapine might adversely alter Kupffer cell pathogen-associated activation and killing. Methods: Mice were treated with mirtazapine and time-dependent changes in Kupffer cells were characterized using intravital microscopy. Macrophage and neutrophil responses, bacterial dissemination, and liver damage were assessed following i.v. infection with a pathogenic strain of S. aureus. Results: Mirtazapine rapidly (within 1.5 h) activates Kupffer cells, indicated by a loss of elongated shape with cellular rounding. However, this shape change did not result in impaired pathogen capture function, and, in fact, generated enhanced ROS production in response to S. aureus-induced sepsis. Neutrophil dynamics were altered with reduced cellular recruitment to the liver following infection. Bacterial dissemination post-intravenous administration was not altered by mirtazapine treatment; however, hepatic abscess formation was significantly reduced. Conclusions: Mirtazapine rapidly activates Kupffer cells, associated with preserved bacterial capture functions and enhanced ROS generation capacity. Moreover, these changes in Kupffer cells were linked to a beneficial reduction in hepatic abscess size. In contrast to our initial speculation, mirtazapine may have beneficial effects in sepsis and warrants further exploration.

Interactions Between Platelets and Inflammatory Monocytes Affect Sickness Behavior in Mice With Liver Inflammation.

BACKGROUND & AIMS: Patients with inflammatory liver disease commonly develop debilitating symptoms, called sickness behaviors, which arise via changes in brain function. Monocytes that produce tumor necrosis factor interact with cerebral endothelial cells to activate microglial cells and promote sickness behavior. Platelets regulate inflammation, and aggregates of monocytes and platelets are increased in the circulation of patients with liver disease. We investigated the role of platelets in inducing inflammatory features of circulating monocytes and promoting sickness behaviors in mice with cholestatic liver injury. METHODS: We performed bile-duct ligations or sham surgeries on C57BL/6 or toll-like receptor 4 (TLR4)-knockout mice to induce liver inflammation. Liver inflammation was also induced in a separate group of mice by administration of concanavalin A. Circulating platelets, aggregates of monocytes and platelets, and activation of microglial cells were measured by flow cytometry. To deplete platelets, mice were given anti-thrombocyte serum or normal rabbit serum (control) 4 days after surgery. Interactions between monocytes and cerebral endothelial cells were analyzed by intravital microscopy. Sickness behaviors were quantified based on time spent by adult mice engaging in social behaviors toward a juvenile mouse, compared with time spent in nonsocial behavior or remaining immobile. RESULTS: Aggregates of monocytes and platelets in circulation of mice increased significantly following bile-duct ligation. Platelet-monocyte interactions were required for activation of inflammatory monocytes and production of tumor necrosis factor. Platelet depletion greatly reduced adhesive interactions between inflammatory monocytes and adhesive interactions with cerebral endothelial cells and activation of the microglia, as well as development of sickness behavior. Furthermore, TLR4 signaling was important for aggregation of monocytes and platelets, and development of sickness behavior following bile-duct ligation. These findings were confirmed in mice with concanavalin A-induced liver injury. CONCLUSIONS: In mice with liver inflammation, we found TLR4 and aggregates of monocytes and platelets to regulate microglial activation and development of sickness behavior. These findings might lead to new therapeutic strategies for liver disease-associated symptoms.