Single cell landscape of functionally cured chronic hepatitis B patients reveals activation of innate and altered CD4-CTL-driven adaptive immunity.

BACKGROUND & AIMS: Hepatitis B surface antigen (HBsAg) loss or functional cure (FC), is considered the desirable therapeutic outcome for chronic hepatitis B (CHB) patients. However, the immune-pathological biomarkers and underlying mechanisms remain unclear. In this study we comprehensively interrogate disease-associated cell states (DACS) identified within intra-hepatic tissue and matched PBMCs from either CHB or FC patients, at the resolution of single cells, to provide novel insights into putative mechanisms underlying FC. METHODS: We combined single cell transcriptomics (scRNA-seq) with multiparametric flow cytometry-based immune phenotyping, and multiplexed immunofluorescence to elucidate the immunopathological cell states associated with CHB vs FC. RESULTS: We find that the intra-hepatic environment of CHB and FC patients displays specific cell identities and molecular signatures that are distinct from those found in matched PBMCs. FC is associated with emergence of an altered adaptive immune response marked by CD4 cytotoxic T lymphocytes (CD4-CTLs), and an activated innate response represented by liver-resident natural killer (LR-NK) cells, specific Kupffer cell (KC) subtypes and marginated neutrophils. Surprisingly, we find that FC patients are also characterized by the presence of MHC class II-expressing hepatocytes and low but persistent levels of cccDNA and pgRNA, which may play an important role in achieving functional cure in HBV patients. CONCLUSIONS: Our study provides conceptually novel insights into the immuno-pathological control of HBV cure, and opens exciting new avenues for clinical management, biomarker discovery and therapeutic interventions. We believe that the discoveries from this study, as it relates to the activation of an innate and altered immune response that may facilitate sustained, low-grade inflammation, may have broader implications in the resolution of chronic viral hepatitis.

Immunohistochemical scoring of CD38 in the tumor microenvironment predicts responsiveness to anti-PD-1/PD-L1 immunotherapy in hepatocellular carcinoma.

INTRODUCTION: Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-associated mortality globally. Immune-checkpoint blockade (ICB) is one of the systemic therapy options for HCC. However, response rates remain low, necessitating robust predictive biomarkers. In the present study, we examined the expression of CD38, a molecule involved in the immunosuppressive adenosinergic pathway, on immune cells present in the tumor microenvironment. We then investigated the association between CD38 and ICB treatment outcomes in advanced HCC. METHODS: Clinically annotated samples from 49 patients with advanced HCC treated with ICB were analyzed for CD38 expression using immunohistochemistry (IHC), multiplex immunohistochemistry/immunofluorescence (mIHC/IF) and multiplex cytokine analysis. RESULTS: IHC and mIHC/IF analyses revealed that higher intratumoral CD38+ cell proportion was strongly associated with improved response to ICB. The overall response rates to ICB was significantly higher among patients with high proportion of total CD38+cells compared with patients with low proportion (43.5% vs 3.9%, p=0.019). Higher responses seen among patients with a high intratumoral CD38+cell proportion translated to a longer median progression-free survival (mPFS, 8.21 months vs 1.64 months, p=0.0065) and median overall survival (mOS, 19.06 months vs 9.59 months, p=0.0295). Patients with high CD38+CD68+macrophage density had a better mOS of 34.43 months compared with 9.66 months in patients with low CD38+CD68+ macrophage density. CD38hi macrophages produce more interferon γ (IFN-γ) and related cytokines, which may explain its predictive value when treated with ICB. CONCLUSIONS: A high proportion of CD38+ cells, determined by IHC, predicts response to ICB and is associated with superior mPFS and OS in advanced HCC.

A Flow Cytometry-Based Assay for High-Throughput Detection and Quantification of Neutrophil Extracellular Traps in Mixed Cell Populations.

Neutrophil extracellular traps (NETs) are web-like structures composed of decondensed chromatin and antimicrobial proteins that are released into the extracellular space during microbial infections. This active cell death program is known as NETosis. To date, florescence microscopy is the widely accepted method for visualization and quantification of NETs. However, this method is subjective, time consuming and yields low numbers of analyzed polymorphonuclear cells (PMNs) per sample. Increasing interest has emerged on the identification of NETs using flow cytometry techniques. However, flow cytometry analysis of NETs requires particular precautions for sample preparation to obtain reproducible data. Herein, we describe a flow cytometry-based assay for high-throughput detection and quantification of NETosis in mixed cell populations. We used fluorescent-labeled antibodies against cell markers on PMNs together with a combination of nucleic acid stains to measure NETosis in whole blood (WB) and purified PMNs. Using plasma membrane-impermeable DNA-binding dye, SYTOX Orange (SO), we found that cell-appendant DNA of NETting PMNs were positive for SO and DAPI. The combination of optimally diluted antibody and nucleic acid dyes required no washing and yielded low background fluorescence. Significant correlations were found for NETosis from WB and purified PMNs. We then validated the assay by comparing with time-lapse live cell fluorescence microscopy and determined very good intraassay and interassay variances. The assay was then applied to a disease associated with NETosis, systemic lupus erythematosus (SLE). We examined PMA-induced NETosis in peripheral PMNs from SLE patients and controls and in bone marrow PMNs from multiple murine models. In summary, this assay is observer-independent and allows for rapid assessment of a large number of PMNs per sample. Use of this assay does not require sophisticated microscopic equipment like imaging flow cytometers and may be a starting point to analyze extracellular trap formation from immune cells other than PMNs. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

Generation of Immature, Mature and Tolerogenic Dendritic Cells with Differing Metabolic Phenotypes.

Immune response results from a complex interplay between the antigen non-specific innate immune system and the antigen specific adaptive immune system. The immune system is a constant balance in maintaining tolerance to self-molecules and reacting rapidly to pathogens. Dendritic cells (DCs) are powerful professional antigen presenting cells that link the innate immune system to the adaptive immune system and balance the adaptive response between self and non-self. Depending on the maturation signals, immature dendritic cells can be selectively stimulated to differentiate into immunogenic or tolerogenic DCs. Immunogenic dendritic cells provide proliferation signals to antigen-specific T cells for clonal expansion; while tolerogenic dendritic cells regulate tolerance by antigen-specific T-cell deletion or clonal expansion of regulatory T-cells. Due to this unique property, dendritic cells are highly sought after as therapeutic agents for cancer and autoimmune diseases. Dendritic cells can be loaded with specific antigens in vitro and injected into the human body to mount a specific immune response both immunogenic and tolerogenic. This work presents a means to generate in vitro from monocytes, immature monocyte derived dendritic cells (moDCs), tolerogenic and mature moDCs that differ in surface marker expression, function and metabolic phenotypes.

Metabolism Is Central to Tolerogenic Dendritic Cell Function.

Immunological tolerance is a fundamental tenant of immune homeostasis and overall health. Self-tolerance is a critical component of the immune system that allows for the recognition of self, resulting in hyporeactivity instead of immunogenicity. Dendritic cells are central to the establishment of dominant immune tolerance through the secretion of immunosuppressive cytokines and regulatory polarization of T cells. Cellular metabolism holds the key to determining DC immunogenic or tolerogenic cell fate. Recent studies have demonstrated that dendritic cell maturation leads to a shift toward a glycolytic metabolic state and preferred use of glucose as a carbon source. In contrast, tolerogenic dendritic cells favor oxidative phosphorylation and fatty acid oxidation. This dichotomous metabolic reprogramming of dendritic cells drives differential cellular function and plays a role in pathologies, such as autoimmune disease. Pharmacological alterations in metabolism have promising therapeutic potential.