Although infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has pleiotropic and systemic effects in some individuals
, many others experience milder symptoms. Here, to gain a ...more comprehensive understanding of the distinction between severe and mild phenotypes in the pathology of coronavirus disease 2019 (COVID-19) and its origins, we performed a whole-blood-preserving single-cell analysis protocol to integrate contributions from all major immune cell types of the blood-including neutrophils, monocytes, platelets, lymphocytes and the contents of the serum. Patients with mild COVID-19 exhibit a coordinated pattern of expression of interferon-stimulated genes (ISGs)
across every cell population, whereas these ISG-expressing cells are systemically absent in patients with severe disease. Paradoxically, individuals with severe COVID-19 produce very high titres of anti-SARS-CoV-2 antibodies and have a lower viral load compared to individuals with mild disease. Examination of the serum from patients with severe COVID-19 shows that these patients uniquely produce antibodies that functionally block the production of the ISG-expressing cells associated with mild disease, by activating conserved signalling circuits that dampen cellular responses to interferons. Overzealous antibody responses pit the immune system against itself in many patients with COVID-19, and perhaps also in individuals with other viral infections. Our findings reveal potential targets for immunotherapies in patients with severe COVID-19 to re-engage viral defence.
Proper activation of cytotoxic T cells via the T cell receptor and the costimulatory receptor CD28 is essential for adaptive immunity against viruses, intracellular bacteria, and cancers. Through ...biochemical analysis of RNA:protein interactions, we uncovered a non-coding RNA circuit regulating activation and differentiation of cytotoxic T cells composed of the long non-coding RNA
(Metastasis Associated Lung Adenocarcinoma Transcript 1) and the microRNA family miR-15/16. miR-15/16 is a widely and highly expressed tumor suppressor miRNA family important for cell proliferation and survival. miR-15/16 play important roles in T cell responses to viral infection, including the regulation of antigen-specific T cell expansion and memory. Comparative Argonaute-2 high-throughput sequencing of crosslinking immunoprecipitation (AHC) combined with gene expression profiling in normal and miR-15/16-deficient mouse T cells revealed a large network of hundreds of direct miR-15/16 target mRNAs, many with functional relevance for T cell activation, survival and memory formation. Among these targets,
contained the largest absolute magnitude miR-15/16-dependent AHC peak. This binding site was among the strongest lncRNA:miRNA interactions detected in the T cell transcriptome. We used CRISPR targeting with homology directed repair to generate mice with a 5-nucleotide mutation in the miR-15/16-binding site in
. This mutation interrupted
:miR-15/16 interaction, and enhanced the repression of other miR-15/16 target genes, including CD28. Interrupting
interaction with miR-15/16 decreased cytotoxic T cell activation, including the expression of interleukin 2 (IL-2) and a broader CD28-responsive gene program. Accordingly,
mutation diminished memory cell persistence in mice following LCMV Armstrong and
infection. This study marks a significant advance in the study of long non-coding RNAs in the immune system by ascribing cell-intrinsic, sequence-specific in vivo function to
. These findings have implications for T cell-mediated autoimmune diseases, antiviral and anti-tumor immunity, as well as lung adenocarcinoma and other malignancies where
is overexpressed.
Immune checkpoint blockade is revolutionizing therapy for advanced cancer, but many patients do not respond to treatment. The identification of robust biomarkers that predict clinical response to ...specific checkpoint inhibitors is critical in order to stratify patients and to rationally select combinations in the context of an expanding array of therapeutic options.
We performed multiparameter flow cytometry on freshly isolated metastatic melanoma samples from 2 cohorts of 20 patients each prior to treatment and correlated the subsequent clinical response with the tumor immune phenotype.
Increasing fractions of programmed cell death 1 high/cytotoxic T lymphocyte-associated protein 4 high (PD-1hiCTLA-4hi) cells within the tumor-infiltrating CD8+ T cell subset strongly correlated with response to therapy (RR) and progression-free survival (PFS). Functional analysis of these cells revealed a partially exhausted T cell phenotype. Assessment of metastatic lesions during anti-PD-1 therapy demonstrated a release of T cell exhaustion, as measured by an accumulation of highly activated CD8+ T cells within tumors, with no effect on Tregs.
Our data suggest that the relative abundance of partially exhausted tumor-infiltrating CD8+ T cells predicts response to anti-PD-1 therapy. This information can be used to appropriately select patients with a high likelihood of achieving a clinical response to PD-1 pathway inhibition.
This work was funded by a generous gift provided by Inga-Lill and David Amoroso as well as a generous gift provided by Stephen Juelsgaard and Lori Cook.
Background Evidence from adult psoriasis studies implicates an imbalance between regulatory and effector T cells, particularly TH -17–producing T cells, in the pathogenesis of psoriasis. Little is ...known about the immunopathology of psoriasis in children. Objective We sought to functionally characterize the inflammatory cell profiles of psoriatic plaques from pediatric patients and compare them with healthy, age-matched controls and adult psoriasis patients. Methods Skin samples from pediatric psoriasis patients and healthy controls were analyzed by multiparameter flow cytometry to determine the dominant immune cell subsets present and cytokines produced. Results Lesional tissue from pediatric psoriasis patients had significantly increased interleukin (IL) 22 derived from CD4+ and CD8+ cells compared with the tissues from healthy pediatric controls and adult psoriasis patients. Tissue from pediatric psoriasis patients had significantly less elevation of IL-17 derived from CD4+ and CD8+ cells compared with the tissue from adult psoriasis patients. In contrast with the lesions from adult patients, lesional skin in pediatric patients with psoriasis did not have increases in regulatory T cells. Limitations This is a pilot study, thus the sample size is small. Conclusion Significant differences in IL-17 and IL-22 expression were observed in the pediatric psoriasis patients compared with pediatric healthy controls and adult psoriasis patients. IL-22 might be relevant in the pathogenesis of pediatric psoriasis and represents a potential treatment target unique to pediatric psoriasis.
Distinct subsets of Tregs reside in nonlymphoid tissues where they mediate unique functions. To interrogate the biology of tissue Tregs in human health and disease, we phenotypically and functionally ...compared healthy skin Tregs with those in peripheral blood, inflamed psoriatic skin, and metastatic melanoma. The mitochondrial enzyme, arginase 2 (ARG2), was preferentially expressed in Tregs in healthy skin, increased in Tregs in metastatic melanoma, and reduced in Tregs from psoriatic skin. ARG2 enhanced Treg suppressive capacity in vitro and conferred a selective advantage for accumulation in inflamed tissues in vivo. CRISPR-mediated deletion of this gene in primary human Tregs was sufficient to skew away from a tissue Treg transcriptional signature. Notably, the inhibition of ARG2 increased mTOR signaling, whereas the overexpression of this enzyme suppressed it. Taken together, our results suggest that Tregs express ARG2 in human tissues to both regulate inflammation and enhance their metabolic fitness.
While studies have elucidated many pathophysiological elements of COVID-19, little is known about immunological changes during COVID-19 resolution. We analyzed immune cells and phosphorylated ...signaling states at single-cell resolution from longitudinal blood samples of patients hospitalized with COVID-19, pneumonia and/or sepsis, and healthy individuals by mass cytometry. COVID-19 patients showed distinct immune compositions and an early, coordinated, and elevated immune cell signaling profile associated with early hospital discharge. Intra-patient longitudinal analysis revealed changes in myeloid and T cell frequencies and a reduction in immune cell signaling across cell types that accompanied disease resolution and discharge. These changes, together with increases in regulatory T cells and reduced signaling in basophils, also accompanied recovery from respiratory failure and were associated with better outcomes at time of admission. Therefore, although patients have heterogeneous immunological baselines and highly variable disease courses, a core immunological trajectory exists that defines recovery from severe SARS-CoV-2 infection.
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•Early and elevated cell signaling is associated with early hospital discharge•Phenotypic and cell signaling changes accompany COVID-19 disease resolution•Elevation of Treg cells and basophils are unique to ventilation recovery•Immune resolution features define patients with better clinical outcomes at day 0
Immunological changes during COVID-19 resolution remain unknown. Burnett, Okholm, Tenvooren et al. analyze longitudinal blood samples from hospitalized COVID-19 patients by single-cell mass cytometry, identifying a conserved set of immunological processes and cell signaling states that uniquely accompany COVID-19 recovery and associate with better clinical outcomes at time of admission.
It has long been recognized that anatomic location is an important feature for defining distinct subtypes of plaque psoriasis. However, little is known about the molecular differences between scalp, ...palmoplantar, and conventional plaque psoriasis. To investigate the molecular heterogeneity of these psoriasis subtypes, we performed RNA-seq and flow cytometry on skin samples from individuals with scalp, palmoplantar, and conventional plaque psoriasis, along with samples from healthy control patients. We performed differential expression analysis and network analysis using weighted gene coexpression network analysis (WGCNA). Our analysis revealed a core set of 763 differentially expressed genes common to all sub-types of psoriasis. In contrast, we identified 605, 632, and 262 genes uniquely differentially expressed in conventional, scalp, and palmoplantar psoriasis, respectively. WGCNA and pathway analysis revealed biological processes for the core genes as well as subtype-specific genes. Flow cytometry analysis revealed a shared increase in the percentage of CD4+ T regulatory cells in all psoriasis subtypes relative to controls, whereas distinct psoriasis subtypes displayed differences in IL-17A, IFN-gamma, and IL-22 production. This work reveals the molecular heterogeneity of plaque psoriasis and identifies subtype-specific signaling pathways that will aid in the development of therapy that is appropriate for each subtype of plaque psoriasis.
Psoriasis is an inflammatory, IL-17–driven skin disease in which autoantigen-induced CD8+ T cells have been identified as pathogenic drivers.
Our study focused on comprehensively characterizing the ...phenotypic variation of CD8+ T cells in psoriatic lesions.
We used single-cell RNA sequencing to compare CD8+ T-cell transcriptomic heterogeneity between psoriatic and healthy skin.
We identified 11 transcriptionally diverse CD8+ T-cell subsets in psoriatic and healthy skin. Among several inflammatory subsets enriched in psoriatic skin, we observed 2 Tc17 cell subsets that were metabolically divergent, were developmentally related, and expressed CXCL13, which we found to be a biomarker of psoriasis severity and which achieved comparable or greater accuracy than IL17A in a support vector machine classifier of psoriasis and healthy transcriptomes. Despite high coinhibitory receptor expression in the Tc17 cell clusters, a comparison of these cells with melanoma-infiltrating CD8+ T cells revealed upregulated cytokine, cytolytic, and metabolic transcriptional activity in the psoriatic cells that differed from an exhaustion program.
Using high-resolution single-cell profiling in tissue, we have uncovered the diverse landscape of CD8+ T cells in psoriatic and healthy skin, including 2 nonexhausted Tc17 cell subsets associated with disease severity.
Our findings provide a high-resolution comparison of cutaneous CD8
+
T cells in psoriasis and healthy skin and elucidate the phenotypic distinctions between the chronic pathologies of autoimmunity ...and cancer.
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