bims-nastce 2021-11-21 papers

bims-nastce

Biomed News

on NASH and T cells

Issue of 2021–11–21
nine papers selected by
Petra Hirsova, Mayo Clinic College of Medicine

A new perspective on NAFLD: focusing on lipid droplets.
Emerging Roles of T Cells in the Pathogenesis of Nonalcoholic Steatohepatitis and Hepatocellular Carcinoma.
A protocol for isolation of primary human immune cells from the liver and mesenteric white adipose tissue biopsies.
Efferocytosis induces macrophage proliferation to help resolve tissue injury.
Dextran Sulfate Sodium Salt-Induced Colitis Aggravates Gut Microbiota Dysbiosis and Liver Injury in Mice With Non-alcoholic Steatohepatitis.
CD29 Enriches for Cytotoxic Human CD4+ T Cells.
Dynamic CD4+ T cell heterogeneity defines subset-specific suppression and PD-L1-blockade-driven functional restoration in chronic infection.
Mechanisms of Immune Checkpoint Inhibitor-Mediated Colitis.
Single-Cell, Single-Nucleus, and Spatial RNA Sequencing of the Human Liver Identifies Cholangiocyte and Mesenchymal Heterogeneity.

J Hepatol. 2021 Nov 15. pii: S0168-8278(21)02181-4. [Epub ahead of print]

A new perspective on NAFLD: focusing on lipid droplets.

Eleonora Scorletti, Rotonya M Carr.

  Lipid droplets (LDs) are complex and metabolically active organelles. They are composed of a neutral lipid core surrounded by a monolayer of phospholipids and proteins. LD accumulation in hepatocytes is the distinctive characteristic of non-alcoholic fatty liver disease (NAFLD). NAFLD is a chronic, heterogeneous liver condition that can progress to liver fibrosis and hepatocellular carcinoma. Though recent research has improved our understanding of the mechanisms linking LDs accumulation to NAFLD progression, numerous aspects of LD biology are either poorly understood or unknown. In this review, we provide a description of several key mechanisms that contribute to LDs accumulation in the hepatocytes, favouring NAFLD progression. First, we highlight the importance of LD architecture and describe how the dysregulation of LD biogenesis leads to endoplasmic reticulum stress and inflammation. This is followed by an analysis of the causal nexus that exists between LD proteome composition and LD degradation. Finally, we describe how the increase in size of LDs causes activation of hepatic stellate cells, leading to liver fibrosis and hepatocellular carcinoma. We conclude that acquiring a more sophisticated understanding of LD biology will provide crucial insights into the heterogeneity of NAFLD and assist in the development of therapeutic approaches for this liver disease.

Keywords:  Autophagy; Endoplasmic reticulum stress; Hypoxia; Lipid droplets (LDs); Non-alcoholic fatty liver disease (NAFLD); Non-alcoholic steatohepatitis (NASH)

DOI:  https://doi.org/10.1016/j.jhep.2021.11.009
Front Endocrinol (Lausanne). 2021 ;12 760860

Emerging Roles of T Cells in the Pathogenesis of Nonalcoholic Steatohepatitis and Hepatocellular Carcinoma.

Petra Hirsova, Adebowale O Bamidele, Haiguang Wang, Davide Povero, Xavier S Revelo.

  Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. A significant proportion of patients with NAFLD develop a progressive inflammatory condition termed nonalcoholic steatohepatitis (NASH), which may eventually advance to cirrhosis and hepatocellular carcinoma (HCC). NASH is characterized by steatosis, hepatocyte ballooning, and lobular inflammation. Heightened immune cell infiltration is a hallmark of NASH, yet the mechanisms whereby hepatic inflammation occurs in NASH and how it contributes to disease initiation and progression remain incompletely understood. Emerging evidence indicates that intrahepatic T cell immune mechanisms play an integral role in the pathogenesis of NASH and its transition to HCC. In this review, we summarize the current knowledge regarding the T cell-mediated mechanisms of inflammation in NASH. We highlight recent preclinical and human studies implicating various subsets of conventional and innate-like T cells in the onset and progression of NASH and HCC. Finally, we discuss the potential therapeutic strategies targeting T cell-mediated responses for the treatment of NASH.

Keywords:  CD4/CD8 lymphocytes; HCC; Inflammation; NASH; T cells

DOI:  https://doi.org/10.3389/fendo.2021.760860
STAR Protoc. 2021 Dec 17. 2(4): 100937

A protocol for isolation of primary human immune cells from the liver and mesenteric white adipose tissue biopsies.

Maria E Moreno-Fernandez, Michelle S M A Damen, Senad Divanovic.

  Isolation of viable immune cells from human tissues is critical for the characterization of cellular and molecular processes underlying disease pathogenesis. Here, we describe protocols for the isolation of highly viable immune cells from liver wedges and mesenteric white adipose tissue resections from obese persons. Notably, characterization of the isolated single-immune cell suspensions, via utility of basic immunological interrogations and genetic approaches, promises to generate an improved understanding of altered immunological pathways in obese individuals with or without metabolic diseases. For complete details on the use and execution of this protocol, please refer to Moreno-Fernandez et al. (2021).

Keywords:  Cell isolation; Flow Cytometry/Mass Cytometry; Health Sciences; Immunology; Metabolism; Single Cell

DOI:  https://doi.org/10.1016/j.xpro.2021.100937
Cell Metab. 2021 Nov 10. pii: S1550-4131(21)00527-1. [Epub ahead of print]

Efferocytosis induces macrophage proliferation to help resolve tissue injury.

Brennan D Gerlach, Patrick B Ampomah, Arif Yurdagul, Chuang Liu, Max C Lauring, Xiaobo Wang, Canan Kasikara, Na Kong, Jinjun Shi, Wei Tao, Ira Tabas.

  Apoptotic cell clearance by macrophages (efferocytosis) promotes resolution signaling pathways, which can be triggered by molecules derived from the phagolysosomal degradation of apoptotic cells. We show here that nucleotides derived from the hydrolysis of apoptotic cell DNA by phagolysosomal DNase2a activate a DNA-PKcs-mTORC2/Rictor pathway that increases Myc to promote non-inflammatory macrophage proliferation. Efferocytosis-induced proliferation expands the pool of resolving macrophages in vitro and in mice, including zymosan-induced peritonitis, dexamethasone-induced thymocyte apoptosis, and atherosclerosis regression. In the dexamethasone-thymus model, hematopoietic Rictor deletion blocked efferocytosing macrophage proliferation, apoptotic cell clearance, and tissue resolution. In atherosclerosis regression, silencing macrophage Rictor or DNase2a blocked efferocyte proliferation, apoptotic cell clearance, and plaque stabilization. In view of previous work showing that other types of apoptotic cell cargo can promote resolution in individual efferocytosing macrophages, the findings here suggest that signaling-triggered apoptotic cell-derived nucleotides can amplify this benefit by increasing the number of these macrophages.

Keywords:  DNase2a; Erk1/2 signaling; MerTK; Myc; atherosclerosis; efferocytosis; inflammation resolution; mTORC2/Rictor; macrophage; macrophage proliferation

DOI:  https://doi.org/10.1016/j.cmet.2021.10.015
Front Microbiol. 2021 ;12 756299

Dextran Sulfate Sodium Salt-Induced Colitis Aggravates Gut Microbiota Dysbiosis and Liver Injury in Mice With Non-alcoholic Steatohepatitis.

Bo Shen, Junjun Wang, Yuecheng Guo, Tianyi Gu, Zhenyang Shen, Cui Zhou, Binghang Li, Xianjun Xu, Fei Li, Qidi Zhang, Xiaobo Cai, Hui Dong, Lungen Lu.

  Objective: Inflammatory bowel disease (IBD) is characterized by gut microbiota dysbiosis, which is also frequently observed in patients with non-alcoholic fatty liver disease. Whether gut microbiota dysbiosis in IBD patients promotes the development of non-alcoholic steatohepatitis (NASH) remains unclear. We aimed to explore the role of gut microbiota dysbiosis in the development of NASH in mice with dextran sulfate sodium salt (DSS) induced colitis. Design: Dextran sulfate sodium salt was used to induce colitis, and high fat (HF), in combination with a high-fructose diet, was used to induce NASH in C57BL/6J male mice. Mice were treated with (1%) DSS to induce colitis in cycles, and each cycle consisted of 7 days of DSS administration followed by a 10-day interval. The cycles were repeated throughout the experimental period of 19 weeks. Pathological alterations in colitis and NASH were validated by hematoxylin and eosin (H&E), oil red O, Sirius red staining, and immunofluorescence. Gut microbiota was examined by 16S rRNA sequencing, and gene expression profiles of hepatic non-parenchymal cells (NPCs) were detected by RNA sequencing. Results: Dextran sulfate sodium salt administration enhanced the disruption of the gut-vascular barrier and aggravated hepatic inflammation and fibrosis in mice with NASH. DSS-induced colitis was accompanied by gut microbiota dysbiosis, characterized by alteration in the core microbiota composition. Compared with the HF group, the abundance of p_Proteobacteria and g_Bacteroides increased, while that of f_S24-7 decreased in the DSS + HF mice. Specifically, gut microbiota dysbiosis was characterized by enrichment of lipopolysaccharide producing bacteria and decreased abundance of short-chain fatty acid-producing bacteria. Gene expression analysis of liver NPCs indicated that compared with the HF group, genes related to both inflammatory response and angiocrine signaling were altered in the DSS + HF group. The expression levels of inflammation-related and vascular development genes correlated significantly with the abundance of p_Proteobacteria, g_Bacteroides, or f_S24-7 in the gut microbiota, implying that gut microbiota dysbiosis induced by DSS might aggravate hepatic inflammation and fibrosis by altering the gene expression in NPCs. Conclusion: Dextran sulfate sodium salt-induced colitis may promote the progression of liver inflammation and fibrosis by inducing microbiota dysbiosis, which triggers an inflammatory response and disrupts angiocrine signaling in liver NPCs. The abundance of gut microbiota was associated with expression levels of inflammation-related genes in liver NPCs and may serve as a potential marker for the progression of NASH.

Keywords:  NASH; colitis; inflammation; liver fibrosis; microbiota dysbiosis

DOI:  https://doi.org/10.3389/fmicb.2021.756299
J Immunol. 2021 Nov 15. pii: ji2100138. [Epub ahead of print]

CD29 Enriches for Cytotoxic Human CD4+ T Cells.

Benoît P Nicolet, Aurelie Guislain, Monika C Wolkers.

CD4+ T cells are key contributors in the induction of adaptive immune responses against pathogens. Even though CD4+ T cells are primarily classified as noncytotoxic helper T cells, it has become appreciated that a subset of CD4+ T cells is cytotoxic. However, tools to identify these cytotoxic CD4+ T cells are lacking. We recently showed that CD29 (integrin β1, ITGB1) expression on human CD8+ T cells enriches for the most potent cytotoxic T cells. In this study, we questioned whether CD29 expression also associates with cytotoxic CD4+ T cells. We show that human peripheral blood-derived CD29hiCD4+ T cells display a cytotoxic gene expression profile, which closely resembles that of CD29hi cytotoxic CD8+ T cells. This CD29hi cytotoxic phenotype was observed ex vivo and was maintained in in vitro cultures. CD29 expression enriched for CD4+ T cells, which effectively produced the proinflammatory cytokines IFN-γ, IL-2, and TNF-α, and cytotoxic molecules. Lastly, CD29-expressing CD4+ T cells transduced with a MART1-specific TCR showed target cell killing in vitro. In conclusion, we demonstrate in this study that CD29 can be employed to enrich for cytotoxic human CD4+ T cells.

DOI: https://doi.org/10.4049/jimmunol.2100138
Nat Immunol. 2021 Nov 18.

Dynamic CD4+ T cell heterogeneity defines subset-specific suppression and PD-L1-blockade-driven functional restoration in chronic infection.

Laura M Snell, Wenxi Xu, Diala Abd-Rabbo, Giselle Boukhaled, Mengdi Guo, Bethany L Macleod, Heidi J Elsaesser, Kebria Hezaveh, Nirmin Alsahafi, Sabelo Lukhele, Sara Nejat, Ramanandan Prabhakaran, Slava Epelman, Tracy L McGaha, David G Brooks.

Inhibiting PD-1:PD-L1 signaling has transformed therapeutic immune restoration. CD4+ T cells sustain immunity in chronic infections and cancer, yet little is known about how PD-1 signaling modulates CD4+ helper T (TH) cell responses or the ability to restore CD4+ TH-mediated immunity by checkpoint blockade. We demonstrate that PD-1:PD-L1 specifically suppressed CD4+ TH1 cell amplification, prevents CD4+ TH1 cytokine production and abolishes CD4+ cytotoxic killing capacity during chronic infection in mice. Inhibiting PD-L1 rapidly restored these functions, while simultaneously amplifying and activating TH1-like T regulatory cells, demonstrating a system-wide CD4-TH1 recalibration. This effect coincided with decreased T cell antigen receptor signaling, and re-directed type I interferon (IFN) signaling networks towards dominant IFN-γ-mediated responses. Mechanistically, PD-L1 blockade specifically targeted defined populations with pre-established, but actively suppressed proliferative potential, with limited impact on minimally cycling TCF-1+ follicular helper T cells, despite high PD-1 expression. Thus, CD4+ T cells require unique differentiation and functional states to be targets of PD-L1-directed suppression and therapeutic restoration.

DOI: https://doi.org/10.1038/s41590-021-01060-7
Front Immunol. 2021 ;12 768957

Mechanisms of Immune Checkpoint Inhibitor-Mediated Colitis.

Harm Westdorp, Mark W D Sweep, Mark A J Gorris, Frank Hoentjen, Marye J Boers-Sonderen, Rachel S van der Post, Michel M van den Heuvel, Berber Piet, Annemarie Boleij, Haiko J Bloemendal, I Jolanda M de Vries.

  Immune checkpoint inhibitors (ICIs) have provided tremendous clinical benefit in several cancer types. However, systemic activation of the immune system also leads to several immune-related adverse events. Of these, ICI-mediated colitis (IMC) occurs frequently and is the one with the highest absolute fatality. To improve current treatment strategies, it is important to understand the cellular mechanisms that induce this form of colitis. In this review, we discuss important pathways that are altered in IMC in mouse models and in human colon biopsy samples. This reveals a complex interplay between several types of immune cells and the gut microbiome. In addition to a mechanistic understanding, patients at risk should be identifiable before ICI therapy. Here we propose to focus on T-cell subsets that interact with bacteria after inducing epithelial damage. Especially, intestinal resident immune cells are of interest. This may lead to a better understanding of IMC and provides opportunities for prevention and management.

Keywords:  colitis; immune checkpoint inhibitor (ICI); immune-related adverse events; mechanisms; treatment

DOI:  https://doi.org/10.3389/fimmu.2021.768957
Hepatol Commun. 2021 Nov 18.

Single-Cell, Single-Nucleus, and Spatial RNA Sequencing of the Human Liver Identifies Cholangiocyte and Mesenchymal Heterogeneity.

Tallulah S Andrews, Jawairia Atif, Jeff C Liu, Catia T Perciani, Xue-Zhong Ma, Cornelia Thoeni, Michal Slyper, Gökcen Eraslan, Asa Segerstolpe, Justin Manuel, Sai Chung, Erin Winter, Iulia Cirlan, Nicholas Khuu, Sandra Fischer, Orit Rozenblatt-Rosen, Aviv Regev, Ian D McGilvray, Gary D Bader, Sonya A MacParland.

The critical functions of the human liver are coordinated through the interactions of hepatic parenchymal and non-parenchymal cells. Recent advances in single-cell transcriptional approaches have enabled an examination of the human liver with unprecedented resolution. However, dissociation-related cell perturbation can limit the ability to fully capture the human liver's parenchymal cell fraction, which limits the ability to comprehensively profile this organ. Here, we report the transcriptional landscape of 73,295 cells from the human liver using matched single-cell RNA sequencing (scRNA-seq) and single-nucleus RNA sequencing (snRNA-seq). The addition of snRNA-seq enabled the characterization of interzonal hepatocytes at a single-cell resolution, revealed the presence of rare subtypes of liver mesenchymal cells, and facilitated the detection of cholangiocyte progenitors that had only been observed during in vitro differentiation experiments. However, T and B lymphocytes and natural killer cells were only distinguishable using scRNA-seq, highlighting the importance of applying both technologies to obtain a complete map of tissue-resident cell types. We validated the distinct spatial distribution of the hepatocyte, cholangiocyte, and mesenchymal cell populations by an independent spatial transcriptomics data set and immunohistochemistry. Conclusion: Our study provides a systematic comparison of the transcriptomes captured by scRNA-seq and snRNA-seq and delivers a high-resolution map of the parenchymal cell populations in the healthy human liver.

DOI: https://doi.org/10.1002/hep4.1854