Changes in natural killer cells and exhausted memory regulatory T Cells with corticosteroid therapy in acute autoimmune hepatitis

Autoimmune hepatitis (AIH) is an immune-mediated liver disease currently treated by immunosuppressive medications with significant side effects. Thus, novel mechanistic treatments are greatly needed. We performed prospective deep immunophenotyping of blood immune cells in patients with acute AIH before and after corticosteroid therapy. Blood samples from 26 patients with acute AIH (United Kingdom-AIH Consortium) were phenotyped by flow cytometry at baseline and 4 months after starting corticosteroids. Pretreatment liver tissues were stained for forkhead box P3-positive (FOXP3POS) regulatory T cells (Tregs), clusters of differentiation (CD)56POS natural killer (NK) cells, and chemokine (C-X-C motif) ligand 10. Chemokine secretion by cultured primary hepatocyte and biliary epithelial cells was measured by enzyme-linked immunosorbent assay. Functional coculture assays with stimulated NK cells and Tregs were performed. CD161 ligand, lectin-like transcript-1 expression by intrahepatic immune cells was demonstrated with flow cytometry. Frequencies of NKbright cells declined with therapy (P < 0.001) and correlated with levels of alanine aminotransferase (P = 0.023). The Treg:NKbright ratio was lower pretreatment, and Tregs had an activated memory phenotype with high levels of CD39, cytotoxic T lymphocyte antigen 4, and FOXP3 but also high programmed death ligand 1, indicating exhaustion. Coculture experiments suggested the Tregs could not efficiently suppress interferon-γ secretion by NK cells. Both Tregs and NK cells had high expression of liver infiltration and T helper 17 plasticity-associated marker CD161 (P = 0.04). Pretreatment and CD161pos NK cells expressed high levels of perforin and granzyme B, consistent with an activated effector phenotype (P < 0.05). Lectin-like transcript 1, a ligand for CD161, is expressed on intrahepatic B cells, monocytes, and neutrophils. Conclusion: Activated effector NK cells, which correlate with biochemical measurements of hepatitis, and exhausted memory Tregs are increased in the blood of patients with treatment-naive AIH and decline with corticosteroid therapy. Inadequate regulation of NK cells by exhausted FOXP3pos Tregs may play a role in AIH pathogenesis and contribute to liver injury. (Hepatology Communications 2018;2:421-436)

Human intrahepatic ILC2 are IL-13^*positive Amphiregulin^*positive and their frequency correlates with Model of End stage Liver Disease score

Innate lymphoid cells (ILC) have been implicated in the initiation of inflammation and fibrosis in mice. However, ILC have not been characterized in inflamed human liver tissue.Human intrahepatic lymphocytes were isolated by mechanical digestion and phenotyped by flow cytometry. Conditioned medium from cultures of primary human biliary epithelial cells, stellate cells, fibroblasts and inflamed human liver tissue was used to model the effects of the inflammatory liver environment of ILC phenotype and function.All three ILC subsets were present in the human liver, with the ILC1 (CRTH2negCD117neg) subset constituting around 70% of intrahepatic ILCs. Both NCRpos (NKp44+) and NCRneg ILC3 (CRTH2negCD117pos) subsets were also detected. ILC2 (CRTH2pos) frequency correlated with disease severity measured by model of end stage liver disease (MELD) scoring leading us to study this subset in more detail. ILC2 displayed a tissue resident CD69+ CD161++ phenotype and expressed chemokine receptor CCR6 allowing them to respond to CCL20 secreted by cholangiocytes and stellate cells. ILC2 expressed integrins VLA-5 and VLA-6 and the IL-2 and IL-7 cytokine receptors CD25 and CD127 although IL-2 and IL-7 were barely detectable in inflamed liver tissue. Although biliary epithelial cells secrete IL-33, intrahepatic ILC2 had low expression of the ST2 receptor. Intrahepatic ILC2 secreted the immunoregulatory and repair cytokines IL-13 and amphiregulin.Intrahepatic ILC2 express receptors allowing them to be recruited to bile ducts in inflamed portal tracts. Their frequencies increased with worsening liver function. Their secretion of IL-13 and amphiregulin suggests they may be recruited to promote resolution and repair and thereby they may contribute to ongoing fibrogenesis in liver disease

Regulatory T Cell Metabolism in the Hepatic Microenvironment

Thymic-derived naturally occurring regulatory T cells (tTreg) are crucial for maintaining peripheral immune homeostasis. They play a crucial role in preventing autoimmunity and maintaining organ transplant without requiring immunosuppression. Cellular metabolism has recently emerged as an important regulator of adaptive immune cell balance between Treg and effector T cells. While the metabolic requirements of conventional T cells are increasingly understood, the role of Treg cellular metabolism is less clear. The continuous exposure of metabolites and nutrients to the human liver via the portal blood flow influences the lineage fitness, function, proliferation, migration, and survival of Treg cells. As cellular metabolism has an impact on its function, it is crucial to understand the metabolic pathways wiring in regulatory T cells. Currently, there are ongoing early phase clinical trials with polyclonal and antigen-specific good manufacturing practice (GMP) Treg therapy to treat autoimmune diseases and organ transplantation. Thus, enhancing immunometabolic pathways of Treg by translational approach with existing or new drugs would utilize Treg cells to their full potential for effective cellular therapy

SARS-CoV2 in public spaces in West London, UK during COVID-19 pandemic

Background Spread of SARS-CoV2 by aerosol is considered an important mode of transmission over distances >2 m, particularly indoors.Objectives We determined whether SARS-CoV2 could be detected in the air of enclosed/semi-enclosed public spaces.Methods and analysis Between March 2021 and December 2021 during the easing of COVID-19 pandemic restrictions after a period of lockdown, we used total suspended and size-segregated particulate matter (PM) samplers for the detection of SARS-CoV2 in hospitals wards and waiting areas, on public transport, in a university campus and in a primary school in West London.Results We collected 207 samples, of which 20 (9.7%) were positive for SARS-CoV2 using quantitative PCR. Positive samples were collected from hospital patient waiting areas, from hospital wards treating patients with COVID-19 using stationary samplers and from train carriages in London underground using personal samplers. Mean virus concentrations varied between 429 500 copies/m3 in the hospital emergency waiting area and the more frequent 164 000 copies/m3 found in other areas. There were more frequent positive samples from PM samplers in the PM2.5 fractions compared with PM10 and PM1. Culture on Vero cells of all collected samples gave negative results.Conclusion During a period of partial opening during the COVID-19 pandemic in London, we detected SARS-CoV2 RNA in the air of hospital waiting areas and wards and of London Underground train carriage. More research is needed to determine the transmission potential of SARS-CoV2 detected in the air

CD127^pos ILC2 express a high level of CD25, but inflamed human liver supernatant contains minimal IL-2 and IL-7.

<p>(A) The CD45^pos CD3^neg lineage^neg CD127^pos CRTH2^pos ILC2 subset was gated and expression of the IL-2 receptor α-chain, CD25, was analysed. CD25 representative overlay and summary data in normal and diseased livers is shown. (** = <i>p</i><0.01 by Mann Whitney test). In the histogram overlay the dotted line represents isotype staining and the shaded histogram reports CD25 staining. (B) Human inflamed liver supernatant was analysed for IL-2, IL-7, IL-9 and IFN-γ. The secretion of cytokines by normal and inflamed human liver tissue was analysed by luminex of 24-hour liver tissue supernatants prepared for 1g of tissue/1ml culture medium. (C) IL-33 production by human liver tissue (Normal and diseased) and (D) IL-33 production by Primary human biliary epithelial (BEC). IL-33 in 24-hour supernatants generated by 1g liver tissue/1ml medium or BEC cells unstimulated, stimulated with IFN-γ and TNF-α or with lipopolysaccharide (LPS) was analysed by ELISA. Summary data are median ± Interquartile range.</p

Biliary epithelial cells secrete IL-33 and intrahepatic ILC2 express IL-13 and amphiregulin.

<p><b>(</b>A) Intrahepatic ILC were freshly isolated and stimulated with PMA and Ionomycin for 4 hours and both CD45^pos CD3^neg lineage^neg CD127^pos CRTH2^pos ILC2 and CD45^pos CD3^neg lineage^neg CD127^pos CRTH2^neg populations were analysed for expressions of IL-4, IL-5, IL-13 and IFN-γ. Representative dot plots and summary data are shown. (B) Immunohistochemistry for amphiregulin in CD3 positive and negative intrahepatic immune cells in human liver. CD3 (Vector Red, red color); Amphiregulin (DAB, Brown color). (C) Amphiregulin expression by intrahepatic ILC2. Amphiregulin representative overlay and summary data in normal and diseased livers are shown. In the histogram overlay the dotted line represents isotype staining and the shaded histogram reports amphiregulin staining.</p

ILC2 subset correlates with MELD score.

<p>Correlation between MELD score and frequency of intrahepatic ILC subsets. Correlation of ILC subset frequency with MELD score was assessed by Spearman’s rank correlation test. End-stage livers of all types of inflammatory liver disease (autoimmune, and non-autoimmune) were included in this analysis. Model of End-stage Liver Disease (MELD).</p

Intrahepatic ILC2 highly express biliary tropic chemokine receptor CCR6 and integrins for fibronectin and laminin.

<p>(A) The CD45^pos CD3^neg lineage^neg CD127^posi CRTH2^pos ILC2 subset was gated and expressions of CXCR3, CCR6, Very Late Antigen-5 (VLA-5) and Very Late Antigen-6 (VLA-6) were analysed. Representative overlays and summary data in normal and diseased livers are shown (normal livers = open squares; diseased livers = filled squares). Summary data are median ± Interquartile range. In histogram overlays, dotted lines represent isotype staining and shaded histograms show the marker expression. (B) Primary human biliary epithelial cells (BEC), stellate cells and fibroblasts were isolated and stimulated with IFN-γ and TNF-α. Interferon gamma-induced Protein-10 (IP-10) secretion was analysed by ELISA. (* = p<0.05, ** = <0.01 by Paired <i>t-</i>test). Summary data are mean ± SEM. (C) Expressions of CXCR3 and CCR6 by the peripheral blood ILC subsets of normal donors and autoimmune liver disease patients with the condition autoimmune hepatitis (AIH). Summary data are median ± interquartile range. (* = p<0.05 by Mann-Whitney test).</p

Summary graphical diagram.

<p>Intrahepatic ILC2 are characterized by expression of CD127 and CRTH2, which binds PDG2. They express tissue residence maker CD69; CD161; the IL-2 cytokine receptor CD25; liver and tissue homing chemokine receptors CXCR3 and CCR6 and cytokine receptor ST2, which bind respectively to IP-10, CCL20 and IL-33 produced by biliary epithelial cells upon stimulation with inflammatory cytokines or bacteria. ILC2 secrete IL-13 and amphiregulin, which may contribute to bile duct regeneration. In addition, they express the integrins VLA-5 and VLA-6, which attach to the extracellular matrix proteins fibronectin and laminin found in the fibrous stroma.</p