scholarly journals Distinct SARS-CoV-2 sensing pathways in pDCs driving TLR7-antiviral vs. TLR2-immunopathological responses in COVID-19

2021 ◽  
Author(s):  
Renee M van der Sluis ◽  
Lamin B Cham ◽  
Alberg Gris Oliver ◽  
Kristine Raaby Gammelgaard ◽  
Jesper Geert Pedersen ◽  
...  
Keyword(s):  
Immune Response ◽  
Stem Cell ◽  
Disease Severity ◽  
De Novo ◽  
Molecular Pathways ◽  
Type I ◽  
Targeted Deletion ◽  
Neuropilin 1 ◽  
Myd88 Signaling

Understanding the molecular pathways driving the acute antiviral and inflammatory response to SARS-CoV-2 infection is critical for developing treatments for severe COVID-19. Here we show that in COVID-19 patients, circulating plasmacytoid dendritic cells (pDCs) decline early after symptom onset and this correlated with COVID-19 disease severity. This transient depletion coincides with decreased expression of antiviral type I IFNα and the systemic inflammatory cytokines CXCL10 and IL-6. Importantly, COVID-19 disease severity correlated with decreased pDC frequency in peripheral blood. Using an in vitro stem cell-based human pDC model, we demonstrate that pDCs directly sense SARS-CoV-2 and in response produce multiple antiviral (IFNα and IFNλ1) and inflammatory (IL-6, IL-8, CXCL10) cytokines. This immune response is sufficient to protect epithelial cells from de novo SARS-CoV-2 infection. Targeted deletion of specific sensing pathways identified TLR7-MyD88 signaling as being crucial for production of the antiviral IFNs, whereas TLR2 is responsible for the inflammatory IL-6 response. Surprisingly, we found that SARS-CoV-2 engages the neuropilin-1 receptor on pDCs to mitigate the antiviral IFNs but not the IL-6 response. These results demonstrate distinct sensing pathways used by pDCs to elicit antiviral vs. immunopathological responses to SARS-CoV-2 and suggest that targeting neuropilin-1 on pDCs may be clinically relevant for mounting TLR7-mediated antiviral protection.

High content screening and computational prediction reveal viral genes that suppress innate immune response

2021 ◽  
Author(s):  
Tai L Ng ◽  
Erika J Olson ◽  
Tae Yeon Yoo ◽  
H. Sloane Weiss ◽  
Yukiye Koide ◽  
...  
Keyword(s):  
Immune Response ◽  
Innate Immune Response ◽  
Nuclear Transport ◽  
Computational Prediction ◽  
Viral Proteins ◽  
Innate Immune ◽  
Type I ◽  
Viral Genes ◽  
Genes Encoding

Suppression of the host innate immune response is a critical aspect of viral replication. Upon infection, viruses may introduce one or more proteins that inhibit key immune pathways, such as the type I interferon pathway. However, the ability to predict and evaluate viral protein bioactivity on targeted pathways remains challenging and is typically done on a single virus/gene basis. Here, we present a medium-throughput high-content cell-based assay to reveal the immunosuppressive effects of viral proteins. To test the predictive power of our approach, we developed a library of 800 genes encoding known, predicted, and uncharacterized human viral genes. We find that previously known immune suppressors from numerous viral families such as Picornaviridae and Flaviviridae recorded positive responses. These include a number of viral proteases for which we further confirmed that innate immune suppression depends on protease activity. A class of predicted inhibitors encoded by Rhabdoviridae viruses was demonstrated to block nuclear transport, and several previously uncharacterized proteins from uncultivated viruses were shown to inhibit nuclear transport of the transcription factors NF-kB and IRF3. We propose that this pathway-based assay, together with early sequencing, gene synthesis, and viral infection studies, could partly serve as the basis for rapid in vitro characterization of novel viral proteins.

scholarly journals A Trifecta of New Insights into Ovine Footrot for Infection Drivers, Immune Response and Host Pathogen Interactions.

2021 ◽  
Author(s):  
Adam M. Blanchard ◽  
Ceri E. Staley ◽  
Laurence Shaw ◽  
Sean R Wattegedera ◽  
Christina-Marie Baumbach ◽  
...  
Keyword(s):  
Immune Response ◽  
Type I Collagen ◽  
Global Analysis ◽  
Bacterial Species ◽  
Skin Barrier ◽  
Control Measures ◽  
Skin Barrier Function ◽  
Type I ◽  
Bacterial Populations

Footrot is a polymicrobial infectious disease in sheep causing severe lameness, leading to one of the industry’s biggest welfare problems. The complex aetiology of footrot makes in-situ or in-vitro investigations difficult. Computational methods offer a solution to understanding the bacteria involved, how they may interact with the host and ultimately providing a way to identify targets for future hypotheses driven investigative work. Here we present the first combined global analysis of the bacterial community transcripts together with the host immune response in healthy and diseased ovine feet during a natural polymicrobial infection state using metatranscriptomics. The intra tissue and surface bacterial populations and the most abundant bacterial transcriptome were analysed, demonstrating footrot affected skin has a reduced diversity and increased abundances of, not only the causative bacteria Dichelobacter nodosus , but other species such as Mycoplasma fermentans and Porphyromonas asaccharolytica . Host transcriptomics reveals a suppression of biological processes relating to skin barrier function, vascular functions, and immunosurveillance in unhealthy interdigital skin, supported by histological findings that type I collagen (associated with scar tissue formation) is significantly increased in footrot affected interdigital skin comparted to outwardly healthy skin. Finally, we provide some interesting indications of host and pathogen interactions associated with virulence genes and the host spliceosome which could lead to the identification of future therapeutic targets. Impact Statement Lameness in sheep is a global welfare and economic concern and footrot is the leading cause of lameness, affecting up to 70% of flocks in the U.K. Current methods for control of this disease are labour intensive and account for approximately 65% of antibiotic use in sheep farming, whilst preventative vaccines suffer from poor efficacy due to antigen competition. Our limited understanding of cofounders, such as strain variation and polymicrobial nature of infection mean new efficacious, affordable and scalable control measures are not receiving much attention. Here we examine the surface and intracellular bacterial populations and propose potential interactions with the host. Identification of these key bacterial species involved in the initiation and progression of disease and the host immune mechanisms could help form the basis of new therapies.

scholarly journals Angiostatic activity of the antitumor cytokine interleukin-21

Blood ◽  
2008 ◽  
Vol 112 (13) ◽  
pp. 4940-4947 ◽  
Author(s):  
Karolien Castermans ◽  
Sebastien P. Tabruyn ◽  
Rong Zeng ◽  
Judy R. van Beijnum ◽  
Cheryl Eppolito ◽  
...  
Keyword(s):  
Immune Response ◽  
Tumor Angiogenesis ◽  
Chorioallantoic Membrane ◽  
Antitumor Immune Response ◽  
In Vivo Studies ◽  
Type I ◽  
Stat3 Phosphorylation ◽  
Interleukin 21

Abstract Interleukin-21 (IL-21) is a recently described immunoregulatory cytokine. It has been identified as a very potent immunotherapeutic agent in several cancer types in animal models, and clinical studies are ongoing. IL-21 belongs to the type I cytokine family of which other members, ie, IL-2, IL-15, and IL-4, have been shown to exert activities on vascular endothelial cells (ECs). We hypothesized that IL-21, in addition to inducing the antitumor immune response, also inhibits tumor angiogenesis. In vitro experiments showed a decrease of proliferation and sprouting of activated ECs after IL-21 treatment. We found that the IL-21 receptor is expressed on vascular ECs. Furthermore, in vivo studies in the chorioallantoic membrane of the chick embryo and in mouse tumors demonstrated that IL-21 treatment disturbs vessel architecture and negatively affects vessel outgrowth. Our results also confirm the earlier suggested angiostatic potential of IL-2 in vitro and in vivo. The angiostatic effect of IL-21 is confirmed by the decrease in expression of angiogenesis-related genes. Interestingly, IL-21 treatment of ECs leads to a decrease of Stat3 phosphorylation. Our research shows that IL-21 is a very powerful antitumor compound that combines the induction of an effective antitumor immune response with inhibition of tumor angiogenesis.

scholarly journals Towards consistent generation of pancreatic lineage progenitors from human pluripotent stem cells

2015 ◽  
Vol 370 (1680) ◽  
pp. 20140365 ◽  
Author(s):  
Maria Rostovskaya ◽  
Nicholas Bredenkamp ◽  
Austin Smith
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Lines ◽  
Pluripotent Stem Cells ◽  
Pluripotent Stem Cell ◽  
Human Pluripotent Stem Cells ◽  
Type I ◽  
Pancreatic Progenitors ◽  
Stem Cell Lines

Human pluripotent stem cells can in principle be used as a source of any differentiated cell type for disease modelling, drug screening, toxicology testing or cell replacement therapy. Type I diabetes is considered a major target for stem cell applications due to the shortage of primary human beta cells. Several protocols have been reported for generating pancreatic progenitors by in vitro differentiation of human pluripotent stem cells. Here we first assessed one of these protocols on a panel of pluripotent stem cell lines for capacity to engender glucose sensitive insulin-producing cells after engraftment in immunocompromised mice. We observed variable outcomes with only one cell line showing a low level of glucose response. We, therefore, undertook a systematic comparison of different methods for inducing definitive endoderm and subsequently pancreatic differentiation. Of several protocols tested, we identified a combined approach that robustly generated pancreatic progenitors in vitro from both embryo-derived and induced pluripotent stem cells. These findings suggest that, although there are intrinsic differences in lineage specification propensity between pluripotent stem cell lines, optimal differentiation procedures may consistently direct a substantial fraction of cells into pancreatic specification.

The Role of Nucleophosmin In Hematopoietic Stem Cells and the Pathogenesis of Myelodysplastic Syndrome

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 95-95 ◽  
Author(s):  
Keisuke Ito ◽  
Paolo Sportoletti ◽  
John G Clohessy ◽  
Grisendi Silvia ◽  
Pier Paolo Pandolfi
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Myelodysplastic Syndrome ◽  
Cell Biology ◽  
De Novo ◽  
Stem Cell Biology ◽  
Hematopoietic Stem

Abstract Abstract 95 Myelodysplastic syndrome (MDS) is an incurable stem cell disorder characterized by ineffective hematopoiesis and an increased risk of leukemia transformation. Nucleophosmin (NPM) is directly implicated in primitive hematopoiesis, the pathogenesis of hematopoietic malignancies and more recently of MDS. However, little is known regarding the molecular role and function of NPM in MDS pathogenesis and in stem cell biology. Here we present data demonstrating that NPM plays a critical role in the maintenance of hematopoietic stem cells (HSCs) and the transformation of MDS into leukemia. NPM is located on chromosome 5q and is frequently lost in therapy-related and de novo MDS. We have previously shown that Npm1 acts as a haploinsufficient tumor suppressor in the hematopoietic compartment and Npm1+/− mice develop a hematologic syndrome with features of human MDS, including increased susceptibility to leukemogenesis. As HSCs have been demonstrated to be the target of the primary neoplastic event in MDS, a functional analysis of the HSC compartment is essential to understand the molecular mechanisms in MDS pathogenesis. However, the role of NPM in adult hematopoiesis remains largely unknown as Npm1-deficiency leads to embryonic lethality. To investigate NPM function in adult hematopoiesis, we have generated conditional knockout mice of Npm1, using the Cre-loxP system. Analysis of Npm1 conditional mutants crossed with Mx1-Cre transgenic mice reveals that Npm1 plays a crucial role in adult hematopoiesis and ablation of Npm1 in adult HSCs leads to aberrant cycling and followed by apoptosis. Analysis of cell cycle status revealed that HSCs are impaired in their ability to maintain quiescence after Npm1-deletion and are rapidly depleted in vivo as well as in vitro. Competitive reconstitution assay revealed that Npm1 acts cell-autonomously to maintain HSCs. Conditional inactivation of Npm1 leads to an MDS phenotype including a profoundly impaired ability to differentiate into cells of the erythroid lineage, megakaryocyte dyspoiesis and centrosome amplification. Furthermore, Npm1 loss evokes a p53-dependent response and Npm1-deleted HSCs undergo apoptosis in vivo and in vitro. Strikingly, transfer of the Npm1 mutation into a p53-null background rescued the apoptosis of Npm1-ablated HSCs and resulted in accelerated transformation to an aggressive and lethal form of acute myeloid leukemia. Our findings highlight the crucial role of NPM in stem cell biology and identify a new mechanism by which MDS can progress to leukemia. This has important therapeutic implications for de novo MDS as well as therapy-related MDS, which is known to rapidly evolve to leukemia with frequent loss or mutation of TRP53. Disclosures: No relevant conflicts of interest to declare.

Plasmacytoid Dendritic Cells (PDC) and Th17 Immune Response Contribution in Gut Acute Graft-Versus-Host-Disease (GVHD)

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2968-2968
Author(s):  
Florent Malard ◽  
Céline Bossard ◽  
Jessy Arbez ◽  
Patrice Chevallier ◽  
Thierry Guillaume ◽  
...  
Keyword(s):  
Immune Response ◽  
Stem Cell ◽  
Autoimmune Diseases ◽  
Intestinal Mucosa ◽  
Th17 Cells ◽  
Acute Gvhd ◽  
Type I ◽  
Type I Ifn ◽  
Th17 Response

Abstract Abstract 2968 Background. Acute GVHD after allogeneic stem cell transplantation (allo-SCT) is an exaggerated immune response against alloantigens involving dysregulation of inflammatory cytokine cascades. Previous studies established an important role of Th1 cells in acute GVHD pathophysiology. However, the identification of proinflammatory Th17 cells which contribute to autoimmune diseases pathophysiology, raised the issue of the role of Th17 cells in human acute GVHD. Indeed, the contribution of Th17 cells in acute GVHD was assessed in GVHD mouse models with conflicting results. In addition, the role of the PDC subset (the professional type I IFN-secreting cells), which play an important role in triggering Th17-related cytokines and autoimmune diseases, is not yet established in the acute GVHD setting. This report investigated the role of Th17 cells and their interaction with PDC in gastrointestinal (GI) biopsies taken from patients with or without acute GVHD. Patients and Methods. Studies described in this report were performed in a single centre series of 21 patients who underwent allo-SCT for different hematological malignancies (n=19) and severe aplastic anemia (n=2). The median age of patients was 53 years (range, 16–69). The stem cell source was PBSCs in 19 cases (85%), CB in 2 cases and BM in one case. Ten patients received transplant from a matched-related donor, and 11 patients from a matched-unrelated donor. A reduced-intensity conditioning regimen was used in the majority of cases (n=19; 90%) Immunohistochemistry was performed on deparaffinized tissues sections using an indirect immunoperoxydase method. A quantitative evaluation of antigens expression was performed by counting the number of positive cells in the whole biopsy at 200 magnifications for each sample. Results. In this cohort, based on standard pathology criteria, 16 patients had a histologically proven gastrointestinal acute GVHD. In all cases, biopsies were taken before initiation of systemic corticosteroid therapy. The remaining 5 patients did not have histological signs of acute GVHD (and did not develop clinical signs of acute GVHD) and thus, were used as controls. In order to identify the Th17 cell population, biopsies were tested for expression of the CD161 and CCR6 markers, and ROR-gamma-t, the key transcription factor that orchestrates the differentiation of Th17 cells. Significantly higher numbers of ROR-gamma-t+ and CD161+ cells were counted in the intestinal mucosa of patients with acute GVHD compared with intestinal mucosa of patients without acute GVHD, mainly found in the lamina propria but also in the epithelium of altered glands (p=0.016 and p=0.009 for ROR-gamma-t and CD161 expression respectively). Given the role of PDCs in triggering Th17-related cytokines, we sought next to determine the proportion of PDCs in intestinal biopsies from these same patients. This analysis showed a significant increase of CD123+ PDCs in the intestinal mucosa of patients with acute GVHD compared with mucosa of patients without acute GVHD (p=0.017). Moreover, we observed a significant correlation between the number of CD123+ PDCs and ROR-gamma-t or CD161 expressing cells in the intestinal mucosa of acute GVHD patients, highlighting the link between PDC and Th17 cells. Conclusion. The current study shed some light on the role of Th17 cells in the context of gastro-intestinal acute GVHD. Using well-established specific markers, we show that Th17 cells infiltrate intestinal biopsies from patients with acute GVHD. In addition, Th17 infiltration was paralleled by the infiltration of PDCs, suggesting a potential new pathophysiological link between PDCs and Th17 response in the context of gastro-intestinal acute GVHD. This is consistent with studies showing that PDCs can drive the differentiation of Th17 cells. Functional analyses are currently ongoing. Although the exact mechanism that links type I IFN production to PDC-mediated Th17 responses is still unclear in acute GVHD, these data raise the prospect of future innovative approaches to optimize immunosuppression regimens for the treatment or prophylaxis of acute GVHD by targeting PDCs and the Th17 response. Disclosures: No relevant conflicts of interest to declare.

scholarly journals TLR7-dependent and FcγR-independent production of type I interferon in experimental mouse lupus

2008 ◽  
Vol 205 (13) ◽  
pp. 2995-3006 ◽  
Author(s):  
Pui Y. Lee ◽  
Yutaro Kumagai ◽  
Yi Li ◽  
Osamu Takeuchi ◽  
Hideo Yoshida ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Type I Interferon ◽  
Myeloid Differentiation ◽  
Type I ◽  
Autoantibody Production ◽  
Experimental Mouse ◽  
Myd88 Signaling ◽  
Myeloid Differentiation Factor ◽  
Dependent Pathway

Increased type I interferon (IFN-I) production and IFN-stimulated gene (ISG) expression are linked to the pathogenesis of systemic lupus erythematosus (SLE). Although the mechanisms responsible for dysregulated IFN-I production in SLE remain unclear, autoantibody-mediated uptake of endogenous nucleic acids is thought to play a role. 2,6,10,14-tetramethylpentadecane (TMPD; also known as pristane) induces a lupus-like disease in mice characterized by immune complex nephritis with autoantibodies to DNA and ribonucleoproteins. We recently reported that TMPD also causes increased ISG expression and that the development of the lupus is completely dependent on IFN-I signaling (Nacionales, D.C., K.M. Kelly-Scumpia, P.Y. Lee, J.S. Weinstein, R. Lyons, E. Sobel, M. Satoh, and W.H. Reeves. 2007. Arthritis Rheum. 56:3770–3783). We show that TMPD elicits IFN-I production, monocyte recruitment, and autoantibody production exclusively through a Toll-like receptor (TLR) 7– and myeloid differentiation factor 88 (MyD88)–dependent pathway. In vitro studies revealed that TMPD augments the effect of TLR7 ligands but does not directly activate TLR7 itself. The effects of TMPD were amplified by the Y-linked autoimmune acceleration cluster, which carries a duplication of the TLR7 gene. In contrast, deficiency of Fcγ receptors (FcγRs) did not affect the production of IFN-I. Collectively, the data demonstrate that TMPD-stimulated IFN-I production requires TLR7/MyD88 signaling and is independent of autoantibody-mediated uptake of ribonucleoproteins by FcγRs.

scholarly journals Identification and characterization of a fibroblast marker: FSP1.

1995 ◽  
Vol 130 (2) ◽  
pp. 393-405 ◽  
Author(s):  
F Strutz ◽  
H Okada ◽  
C W Lo ◽  
T Danoff ◽  
R L Carone ◽  
...  
Keyword(s):  
Cell Fate ◽  
Calcium Binding ◽  
Type I Collagen ◽  
De Novo ◽  
Mesangial Cells ◽  
In Vivo Studies ◽  
Type I ◽  
Tubular Epithelium ◽  
Collagen Gels

We performed subtractive and differential hybridization for transcript comparison between murine fibroblasts and isogenic epithelium, and observed only a few novel intracellular genes which were relatively specific for fibroblasts. One such gene encodes a filament-associated, calcium-binding protein, fibroblast-specific protein 1 (FSP1). The promoter/enhancer region driving this gene is active in fibroblasts but not in epithelium, mesangial cells or embryonic endoderm. During development, FSP1 is first detected by in situ hybridization after day 8.5 as a postgastrulation event, and is associated with cells of mesenchymal origin or of fibroblastic phenotype. Polyclonal antiserum raised to recombinant FSP1 protein stained the cytoplasm of fibroblasts, but not epithelium. Only occasional cells stain with specific anti-FSP1 antibodies in normal parenchymal tissue. However, in kidneys fibrosing from persistent inflammation, many fibroblasts could be identified in interstitial sites of collagen deposition and also in tubular epithelium adjacent to the inflammatory process. This pattern of anti-FSP1 staining during tissue fibrosis suggests, as a hypothesis, that fibroblasts in some cases arise, as needed, from the local conversion of epithelium. Consistent with this notion that FSP1 may be involved in the transition from epithelium to fibroblasts are experiments in which the in vitro overexpression of FSP1 cDNA in tubular epithelium is accompanied by conversion to a mesenchymal phenotype, as characterized by a more stellate and elongated fibroblast-like appearance, a reduction in cytokeratin, and new expression of vimentin. Similarly, tubular epithelium submerged in type I collagen gels exhibited the conversion to a fibroblast phenotype which includes de novo expression of FSP1 and vimentin. Use of the FSP1 marker, therefore, should further facilitate both the in vivo studies of fibrogenesis and the mapping of cell fate among fibroblasts.

scholarly journals The role of hormonal-cytokine interactions in the formation of humoral immune response

1995 ◽  
Vol 41 (1) ◽  
pp. 32-34
Author(s):  
S. V. Shirshev
Keyword(s):  
Immune Response ◽  
Chorionic Gonadotropin ◽  
Humoral Immune Response ◽  
Alpha Interferon ◽  
Type I ◽  
Humoral Immune ◽  
Beta Interferon ◽  
Cytokine Interactions

The functional activity of splenocytes of CBA mice was investigated in a syngeneic transfer system by the level of formation of antibody-producing cells (APC). Splenocytes were preincubated for 1 h in vitro with chorionic gonadotropin and type I recombinant interferons, as well as in hormonal-cytokine combinations. Chorionic gonadotropin in doses 10 and 50 MU/ml depressed APC formation, whereas alpha-interferon (250 MU/ml) stimulated it, and beta-interferon in the same concentration did not influence the level of humoral immune response. Chorionic gonadotropin, if added to splenocyte culture in combination with alpha-interferon, completely lost its immunodepressive properties. However, if together with alpha-interferon in a dose of 10 MU/ml it had a costimulating effect, in contrast to that, in combination with beta-interferon in the tested concentrations it was conducive to only a statistically reliable increase in the number of APC.

scholarly journals Development and Validation of Fluorescently Labeled, Functional Type I Collagen Molecules

2021 ◽  
Author(s):  
Seyed Mohammad Siadat ◽  
Monica E Susilo ◽  
Jeffrey A Paten ◽  
Alexandra A Silverman ◽  
Charles A DiMarzio ◽  
...  
Keyword(s):  
Type I Collagen ◽  
De Novo ◽  
Type I ◽  
Growth And Remodeling ◽  
Fibril Structure ◽  
Collagen Molecules ◽  
Vitro Model ◽  
Development And Validation ◽  
Network Morphology

While de novo collagen fibril formation is well-studied, there are few investigations into the growth and remodeling of extant fibrils, where molecular collagen incorporation into and erosion from the fibril surface must delicately balance during fibril growth and remodeling. Observing molecule/fibril interactions is difficult, requiring the tracking of molecular dynamics while, at the same time, minimizing the effect of the observation on fibril structure and assembly. To address the observation-interference problem, exogenous collagen molecules are tagged with small fluorophores and the fibrillogenesis kinetics of labeled collagen molecules as well as the structure and network morphology of assembled fibrils are quantified for the first time. While excessive labeling significantly disturbs fibrillogenesis kinetics and network morphology of assembled fibrils, adding less than ~1.2 labels preserves them. Applications of the functional, labeled collagen probe are demonstrated in both cellular and acellular systems. The functional, labelled collagen associates strongly with native fibrils and when added to an in vitro model of corneal stromal development, is endocytosed rapidly by cells and is translocated into synthesized matrix networks within 24 hours.

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