Comparison of the single-cell and single-nucleus hepatic myeloid landscape within decompensated cirrhosis patients.

Background and aims: A complete understanding of disease pathophysiology in advanced liver disease is hampered by the challenges posed by clinical specimen collection. Notably, in these patients, a transjugular liver biopsy (TJB) is the only safe way to obtain liver tissue. However, it remains unclear whether successful sequencing of this extremely small and fragile tissue can be achieved for downstream characterization of the hepatic landscape. Methods: Here we leveraged in-house available single-cell RNA-sequencing (scRNA-seq) and single-nucleus (snRNA-seq) technologies and accompanying tissue processing protocols and performed an in-patient comparison on TJB's from decompensated cirrhosis patients (n = 3). Results: We confirmed a high concordance between nuclear and whole cell transcriptomes and captured 31,410 single nuclei and 6,152 single cells, respectively. The two platforms revealed similar diversity since all 8 major cell types could be identified, albeit with different cellular proportions thereof. Most importantly, hepatocytes were most abundant in snRNA-seq, while lymphocyte frequencies were elevated in scRNA-seq. We next focused our attention on hepatic myeloid cells due to their key role in injury and repair during chronic liver disease. Comparison of their transcriptional signatures indicated that these were largely overlapping between the two platforms. However, the scRNA-seq platform failed to recover sufficient Kupffer cell numbers, and other monocytes/macrophages featured elevated expression of stress-related parameters. Conclusion: Our results indicate that single-nucleus transcriptome sequencing provides an effective means to overcome complications associated with clinical specimen collection and could sufficiently profile all major hepatic cell types including all myeloid cell subsets.

Adipose tissue macrophage dysfunction is associated with a breach of vascular integrity in NASH.

BACKGROUND & AIMS: In non-alcoholic fatty liver disease (NAFLD), monocytes infiltrate visceral adipose tissue promoting local and hepatic inflammation. However, it remains unclear what drives inflammation and how the immune landscape in adipose tissue differs across the NAFLD severity spectrum. We aimed to assess adipose tissue macrophage (ATM) heterogeneity in a NAFLD cohort. METHODS: Visceral adipose tissue macrophages from lean and obese patients, stratified by NAFLD phenotypes, underwent single-cell RNA sequencing. Adipose tissue vascular integrity and breaching was assessed on a protein level via immunohistochemistry and immunofluorescence to determine targets of interest. RESULTS: We discovered multiple ATM populations, including resident vasculature-associated macrophages (ResVAMs) and distinct metabolically active macrophages (MMacs). Using trajectory analysis, we show that ResVAMs and MMacs are replenished by a common transitional macrophage (TransMac) subtype and that, during NASH, MMacs are not effectively replenished by TransMac precursors. We postulate an accessory role for MMacs and ResVAMs in protecting the adipose tissue vascular barrier, since they both interact with endothelial cells and localize around the vasculature. However, across the NAFLD severity spectrum, alterations occur in these subsets that parallel an adipose tissue vasculature breach characterized by albumin extravasation into the perivascular tissue. CONCLUSIONS: NAFLD-related macrophage dysfunction coincides with a loss of adipose tissue vascular integrity, providing a plausible mechanism by which tissue inflammation is perpetuated in adipose tissue and downstream in the liver. IMPACT AND IMPLICATIONS: Our study describes for the first time the myeloid cell landscape in human visceral adipose tissue at single-cell level within a cohort of well-characterized patients with non-alcoholic fatty liver disease. We report unique non-alcoholic steatohepatitis-specific transcriptional changes within metabolically active macrophages (MMacs) and resident vasculature-associated macrophages (ResVAMs) and we demonstrate their spatial location surrounding the vasculature. These dysfunctional transcriptional macrophage states coincided with the loss of adipose tissue vascular integrity, providing a plausible mechanism by which tissue inflammation is perpetuated in adipose tissue and downstream in the liver. Our study provides a theoretical basis for new therapeutic strategies to be directed towards reinstating the endogenous metabolic, homeostatic and cytoprotective functions of ResVAMs and MMacs, including their role in protecting vascular integrity.

Combination of fibrates with obeticholic acid is able to normalise biochemical liver tests in patients with difficult-to-treat primary biliary cholangitis.

BACKGROUND: Obeticholic acid (OCA) and fibrates are second-line therapies for patients with primary biliary cholangitis (PBC) with an inadequate response to ursodeoxycholic acid (UDCA). AIM: To know whether OCA and fibrates, administered together in combination with UDCA, have additive beneficial effects in patients with difficult-to-treat PBC. METHODS: PBC patients treated for ≥3 months with UDCA, OCA and fibrates (bezafibrate or fenofibrate) due to failure of either second-line therapy were included in a multicentre, uncontrolled retrospective cohort study. Changes in biochemical liver tests and pruritus were analysed using a generalised linear mixed-effect model. RESULTS: Among 58 patients included, half received OCA as second-line and fibrates as third-line therapy (Group OCA-Fibrate), while the other half had the inverse therapeutic sequence (Group Fibrate-OCA). The mean duration of triple therapy was 11 months (range 3-26). Compared to dual therapy, triple therapy was associated with a significant gain in alkaline phosphatase (ALP) reduction: 22% per first year (95% CI 12%-31%), an effect that was stronger in OCA-Fibrate than in Fibrate-OCA group. Triple therapy was associated with a 3.4 (95% CI 1.4-8.2) odds ratio (OR) of reaching normal ALP and with a significant decrease in gamma-glutamyl transpeptidase (GGT), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin. The ORs of achieving the Paris-2 and Toronto criteria of adequate biochemical response were 6.8 (95% CI 2.8-16.7) and 9.2 (95% CI 3.4-25.1) respectively. Finally, triple therapy significantly improved pruritus in OCA-Fibrate but not in Fibrate-OCA group. CONCLUSIONS: Triple therapy with UDCA, OCA and fibrates is able to normalise biochemical liver tests and improve pruritus in patients with difficult-to-treat PBC.