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1.
Int J Mol Sci ; 21(15)2020 Jul 22.
Article in English | MEDLINE | ID: covidwho-1934093

ABSTRACT

Tissue injury and inflammatory response trigger the development of fibrosis in various diseases. It has been recognized that both innate and adaptive immune cells are important players with multifaceted functions in fibrogenesis. The activated immune cells produce various cytokines, modulate the differentiation and functions of myofibroblasts via diverse molecular mechanisms, and regulate fibrotic development. The immune cells exhibit differential functions during different stages of fibrotic diseases. In this review, we summarized recent advances in understanding the roles of immune cells in regulating fibrotic development and immune-based therapies in different disorders and discuss the underlying molecular mechanisms with a focus on mTOR and JAK-STAT signaling pathways.


Subject(s)
Adaptive Immunity , Fibrosis/immunology , Immunity, Innate , Signal Transduction/immunology , Animals , B-Lymphocytes/immunology , Cytokines/metabolism , Dendritic Cells/immunology , Fibrosis/pathology , Fibrosis/therapy , Humans , Lymphopoiesis/immunology , Macrophages/immunology , Myofibroblasts/metabolism , Neutrophils/immunology , T-Lymphocytes/immunology
2.
PLoS One ; 17(7): e0271463, 2022.
Article in English | MEDLINE | ID: covidwho-1933390

ABSTRACT

γδ T cells are thought to contribute to immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the mechanisms by which they are activated by the virus are unknown. Using flow cytometry, we investigated if the two most abundant viral structural proteins, spike and nucleocapsid, can activate human γδ T cell subsets, directly or in the presence of dendritic cells (DC). Both proteins failed to induce interferon-γ production by Vδ1 or Vδ2 T cells within fresh mononuclear cells or lines of expanded γδ T cells generated from healthy donors, but the same proteins stimulated CD3+ cells from COVID-19 patients. The nucleocapsid protein stimulated interleukin-12 production by DC and downstream interferon-γ production by co-cultured Vδ1 and Vδ2 T cells, but protease digestion and use of an alternative nucleocapsid preparation indicated that this activity was due to contaminating non-protein material. Thus, SARS-CoV-2 spike and nucleocapsid proteins do not have stimulatory activity for DC or γδ T cells. We propose that γδ T cell activation in COVID-19 patients is mediated by immune recognition of viral RNA or other structural proteins by γδ T cells, or by other immune cells, such as DC, that produce γδ T cell-stimulatory ligands or cytokines.


Subject(s)
COVID-19 , Dendritic Cells , Nucleocapsid Proteins , Receptors, Antigen, T-Cell, gamma-delta , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , COVID-19/immunology , COVID-19/virology , Dendritic Cells/immunology , Humans , Interferon-gamma/immunology , Nucleocapsid Proteins/immunology , Receptors, Antigen, T-Cell, gamma-delta/immunology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology
3.
Cell Rep ; 40(4): 111148, 2022 Jul 26.
Article in English | MEDLINE | ID: covidwho-1926273

ABSTRACT

Plasmacytoid dendritic cells (pDCs) are specialized cells of the immune system that are thought to be the main cellular source of type I interferon alpha (IFNα) in response to viral infections. IFNs are powerful antivirals, whereas defects in their function or induction lead to impaired resistance to virus infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19. IFN production needs to be controlled, because sustained IFN production can also have detrimental effects on disease outcome. As such, pDCs are likely important for acute antiviral protection against SARS-CoV-2 infection but could potentially also contribute to chronic IFN levels. Here, we provide a historical overview of pDC biology and summarize existing literature addressing their involvement and importance during viral infections of the airways. Furthermore, we outline recent reports focused on the potential role of pDCs during SARS-CoV-2 infection, as well as the potential for this cellular subset to impact COVID-19 disease outcome.


Subject(s)
COVID-19 , Interferon Type I , Antiviral Agents/pharmacology , Dendritic Cells , Humans , SARS-CoV-2
4.
Front Immunol ; 13: 843342, 2022.
Article in English | MEDLINE | ID: covidwho-1903004

ABSTRACT

Uncontrolled severe acute respiratory syndrome-coronavirus (SARS-CoV)-2 infection is closely related to disorders of the innate immune and delayed adaptive immune systems. Dendritic cells (DCs) "bridge" innate immunity and adaptive immunity. DCs have important roles in defending against SARS-CoV-2 infection. In this review, we summarize the latest research concerning the role of DCs in SARS-CoV-2 infection. We focus on the complex interplay between DCs and SARS-CoV-2: pyroptosis-induced activation; activation of the renin-angiotensin-aldosterone system; and activation of dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin. We also discuss the decline in DC number, the impaired antigen-presentation capability, and the reduced production of type-I interferon of DCs in severe SARS-CoV-2 infection. In addition, we discuss the potential mechanisms for pathological activation of DCs to understand the pattern of SARS-CoV-2 infection. Lastly, we provide a brief overview of novel vaccination and immunotherapy strategies based on DC targeting to overcome SARS-CoV-2 infection.


Subject(s)
COVID-19/immunology , Dendritic Cells/immunology , SARS-CoV-2 , Animals , Humans
5.
Theranostics ; 12(10): 4606-4628, 2022.
Article in English | MEDLINE | ID: covidwho-1897098

ABSTRACT

Rationale: Evident immunosuppression has been commonly seen among septic patients, and it is demonstrated to be a major driver of morbidity. Nevertheless, a comprehensive view of the host immune response to sepsis is lacking as the majority of studies on immunosuppression have focused on a specific type of immune cells. Methods: We applied multi-compartment, single-cell RNA sequencing (scRNA-seq) to dissect heterogeneity within immune cell subsets during sepsis progression on cecal ligation and puncture (CLP) mouse model. Flow cytometry and multiplex immunofluorescence tissue staining were adopted to identify the presence of 'mature DCs enriched in immunoregulatory molecules' (mregDC) upon septic challenge. To explore the function of mregDC, sorted mregDC were co-cultured with naïve CD4+ T cells. Intracellular signaling pathways that drove mregDC program were determined by integrating scRNA-seq and bulk-seq data, combined with inhibitory experiments. Results: ScRNA-seq analysis revealed that sepsis induction was associated with substantial alterations and heterogeneity of canonical immune cell types, including T, B, natural killer (NK), and myeloid cells, across three immune-relevant tissue sites. We found a unique subcluster of conventional dendritic cells (cDCs) that was characterized by specific expression of maturation- and migration-related genes, along with upregulation of immunoregulatory molecules, corresponding to the previously described 'mregDCs' in cancer. Flow cytometry and in stiu immunofluorescence staining confirmed the presence of sepsis-induced mregDC at protein level. Functional experiments showed that sepsis-induced mregDCs potently activated naive CD4+ T cells, while promoted CD4+ T cell conversion to regulatory T cells. Further observations indicated that the mregDC program was initiated via TNFRSF-NF-κB- and IFNGR2-JAK-STAT3-dependent pathways within 24 h of septic challenge. Additionally, we confirmed the detection of mregDC in human sepsis using publicly available data from a recently published single-cell study of COVID-19 patients. Conclusions: Our study generates a comprehensive single-cell immune landscape for polymicrobial sepsis, in which we identify the significant alterations and heterogeneity in immune cell subsets that take place during sepsis. Moreover, we find a conserved and potentially targetable immunoregulatory program within DCs that associates with hyperinflammation and organ dysfunction early following sepsis induction.


Subject(s)
COVID-19 , Sepsis , Animals , Dendritic Cells , Gene Expression Profiling , Humans , Mice , T-Lymphocytes, Regulatory
6.
Nutrients ; 14(11)2022 May 27.
Article in English | MEDLINE | ID: covidwho-1869720

ABSTRACT

Fucoidan, a sulfated polysaccharide extracted from brown seaweed, has been proposed to effectively treat and prevent various viral infections. However, the mechanisms behind its antiviral activity are not completely understood. We investigate here the global transcriptional changes in bone marrow-derived dendritic cells (BMDCs) using RNA-Seq technology. Through both analysis of differentially expressed genes (DEG) and gene set enrichment analysis (GSEA), we found that fucoidan-treated BMDCs were enriched in virus-specific response pathways, including that of SARS-CoV-2, as well as pathways associated with nucleic acid-sensing receptors (RLR, TLR, NLR, STING), and type I interferon (IFN) production. We show that these transcriptome changes are driven by well-known regulators of the inflammatory response against viruses, including IRF, NF-κB, and STAT family transcription factors. Furthermore, 435 of the 950 upregulated DEGs are classified as type I IFN-stimulated genes (ISGs). Flow cytometric analysis additionally showed that fucoidan increased MHCII, CD80, and CD40 surface markers in BMDCs, indicative of greater antigen presentation and co-stimulation functionality. Our current study suggests that fucoidan transcriptionally activates PRR signaling, type I IFN production and signaling, ISGs production, and DC maturation, highlighting a potential mechanism of fucoidan-induced antiviral activity.


Subject(s)
COVID-19 , Dendritic Cells , Antiviral Agents/metabolism , Antiviral Agents/pharmacology , Humans , Polysaccharides/metabolism , Polysaccharides/pharmacology , SARS-CoV-2
7.
Immunohorizons ; 6(4): 275-282, 2022 04 27.
Article in English | MEDLINE | ID: covidwho-1818325

ABSTRACT

Putative subcomponent vaccines of severe acute respiratory syndrome coronavirus spike protein and ARNAX (TLR3-specific adjuvant for priming dendritic cells) were examined and compared with spike protein + Alum in a mouse BALB/c model. Survival, body weight, virus-neutralizing Ab titer in the blood, and viral titer in the lung were evaluated for prognosis markers. The infiltration degrees of eosinophils in the lung were histopathologically monitored at 10 d postinfection. The results were: (1) adjuvant was essential in vaccines to achieve a complete recovery from infection, (2) ARNAX displayed optimal body weight recovery compared with Alum, (3) ARNAX was optimal for the amelioration of eosinophilic pneumonia, and (4) the eosinophil infiltration score was not associated with the neutralizing Ab titer in the blood or viral titer in the lung. Although the pathological link between the TLR3 vaccine and lung eosinophil infiltration remains unclear, severe acute respiratory syndrome-mediated eosinophilic pneumonia can be blocked by the prior induction of dendritic cell priming by ARNAX.


Subject(s)
Pulmonary Eosinophilia , SARS Virus , Viral Vaccines , Adjuvants, Immunologic/pharmacology , Animals , Body Weight , Dendritic Cells , Disease Models, Animal , Mice , Pulmonary Eosinophilia/prevention & control , Toll-Like Receptor 3 , Viral Vaccines/pharmacology
8.
Annu Rev Immunol ; 40: 525-557, 2022 04 26.
Article in English | MEDLINE | ID: covidwho-1813277

ABSTRACT

Macrophages and conventional dendritic cells (cDCs) are distributed throughout the body, maintaining tissue homeostasis and tolerance to self and orchestrating innate and adaptive immunity against infection and cancer. As they complement each other, it is important to understand how they cooperate and the mechanisms that integrate their functions. Both are exposed to commensal microbes, pathogens, and other environmental challenges that differ widely among anatomical locations and over time. To adjust to these varying conditions, macrophages and cDCs acquire spatiotemporal adaptations (STAs) at different stages of their life cycle that determine how they respond to infection. The STAs acquired in response to previous infections can result in increased responsiveness to infection, termed training, or in reduced responses, termed paralysis, which in extreme cases can cause immunosuppression. Understanding the developmental stage and location where macrophages and cDCs acquire their STAs, and the molecular and cellular players involved in their induction, may afford opportunities to harness their beneficial outcomes and avoid or reverse their deleterious effects. Here we review our current understanding of macrophage and cDC development, life cycle, function, and STA acquisition before, during, and after infection.We propose a unified framework to explain how these two cell types adjust their activities to changing conditions over space and time to coordinate their immunosurveillance functions.


Subject(s)
Adaptive Immunity , Dendritic Cells , Animals , Cell Differentiation , Humans , Immune Tolerance , Macrophages
9.
EMBO J ; 41(10): e111208, 2022 May 16.
Article in English | MEDLINE | ID: covidwho-1811580

ABSTRACT

Plasmacytoid dendritic cells (pDC) have the unique ability to rapidly mount high-level antiviral type I interferon (IFN-I) responses during diverse virus infections. In COVID-19 patients, reduced pDC numbers correlate with diminished IFN-I serum levels and enhanced disease severity. However, the molecular mechanisms underlying SARS-CoV-2-mediated pDC stimulation to induce cytokine responses are still largely unclear. In this issue of the EMBO Journal, van der Sluis and colleagues tackled this question by using an innovative hematopoietic stem and progenitor cells (HSPC)-pDC system that allows gene editing and the detailed analysis of pDC sensing mechanisms.


Subject(s)
COVID-19 , Interferon Type I , Toll-Like Receptors , Dendritic Cells , Humans , SARS-CoV-2
10.
Scand J Immunol ; 95(4): e13153, 2022 Apr.
Article in English | MEDLINE | ID: covidwho-1784739

ABSTRACT

Infections with SARS-CoV-2 have been unduly severe in patients with haematological malignancies, in particular in those with chronic lymphocytic leukaemia (CLL). Based on a series of observations, we propose that an underlying mechanism for the aggressive clinical course of COVID-19 in CLL is a paucity of plasmacytoid dendritic cells (pDCs) in these patients. Indeed, pDCs express Toll-like receptor 7 (TLR7), which together with interferon-regulatory factor 7 (IRF7), enables pDCs to produce large amounts of type I interferons, essential for combating COVID-19. Treatment of CLL with Bruton's tyrosine kinase (BTK) inhibitors increased the number of pDCs, likely secondarily to the reduction in the tumour burden.


Subject(s)
COVID-19 , Leukemia, Lymphocytic, Chronic, B-Cell , COVID-19/complications , Dendritic Cells , Humans , Interferon Regulatory Factor-7 , Leukemia, Lymphocytic, Chronic, B-Cell/complications , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , SARS-CoV-2 , Toll-Like Receptor 7
12.
J Dermatol ; 49(7): 732-735, 2022 Jul.
Article in English | MEDLINE | ID: covidwho-1774698

ABSTRACT

Skin disorders are frequent adverse events after coronavirus disease 2019 (COVID-19) vaccination. However, the pathogenesis of these disorders is not fully understood. Here, we report a case series of cutaneous adverse events following COVID-19 vaccination, and the results of our investigation reveal the underlying mechanism. Case 1: a 47-year-old female developed a wheal, confined to the COVID-19 vaccination site, 2 days after her first injection. She was treated with topical steroids and oral antihistamines. Case 2: a 51-year-old female showed generalized petechial erythema accompanied by fever, genital bleeding, thrombocytopenia, liver dysfunction, and disseminated intravascular coagulation, 2 days after her second injection. She was diagnosed with vaccine-induced macrophage activation syndrome and treated with anti-inflammatory therapy. Immunohistological analysis of the skin eruption, in both these cases, showed infiltration of CD123+ BDCA2+ plasmacytoid dendritic cells (p-DC). Despite the distinctive clinical features in these two cases, this finding suggests that p-DC might be involved in different cutaneous adverse events after COVID-19 vaccination.


Subject(s)
COVID-19 Vaccines , COVID-19 , Dendritic Cells , Erythema , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , Erythema/chemically induced , Female , Humans , Middle Aged , Vaccination/adverse effects
13.
Proc Natl Acad Sci U S A ; 119(13): e2025607119, 2022 03 29.
Article in English | MEDLINE | ID: covidwho-1758459

ABSTRACT

SignificanceAlthough the need for a universal influenza vaccine has long been recognized, only a handful of candidates have been identified so far, with even fewer advancing in the clinical pipeline. The 24-amino acid ectodomain of M2 protein (M2e) has been developed over the past two decades. However, M2e-based vaccine candidates have shortcomings, including the need for several administrations and the lack of sustained antibody titers over time. We report here a vaccine targeting strategy that has the potential to confer sustained and strong protection upon a single shot of a small amount of M2e antigen. The current COVID-19 pandemic has highlighted the importance of developing versatile, powerful platforms for the rapid deployment of vaccines against any incoming threat.


Subject(s)
COVID-19 , Influenza A virus , Influenza Vaccines , Influenza, Human , Viral Matrix Proteins , Viroporin Proteins , Animals , Antibodies, Monoclonal/genetics , Antibodies, Viral/genetics , Antibodies, Viral/immunology , COVID-19/prevention & control , Dendritic Cells/immunology , Humans , Influenza A virus/immunology , Influenza Vaccines/administration & dosage , Influenza Vaccines/immunology , Influenza, Human/prevention & control , Mice , Mice, Inbred BALB C , Orthomyxoviridae Infections/prevention & control , Pandemics/prevention & control , Viral Matrix Proteins/chemistry , Viral Matrix Proteins/immunology , Viroporin Proteins/immunology
14.
EMBO J ; 41(10): e109622, 2022 May 16.
Article in English | MEDLINE | ID: covidwho-1700141

ABSTRACT

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 find decreasing number of circulating plasmacytoid dendritic cells (pDCs) in COVID-19 patients early after symptom onset, correlating with disease severity. pDC depletion is transient and coincides with decreased expression of antiviral type I IFNα and of systemic inflammatory cytokines CXCL10 and IL-6. Using an in vitro stem cell-based human pDC model, we further demonstrate that pDCs, while not supporting SARS-CoV-2 replication, directly sense the virus and in response produce multiple antiviral (interferons: IFNα and IFNλ1) and inflammatory (IL-6, IL-8, CXCL10) cytokines that protect epithelial cells from de novo SARS-CoV-2 infection. Via targeted deletion of virus-recognition innate immune pathways, we identify TLR7-MyD88 signaling as crucial for production of antiviral interferons (IFNs), whereas Toll-like receptor (TLR)2 is responsible for the inflammatory IL-6 response. We further show that SARS-CoV-2 engages the receptor neuropilin-1 on pDCs to selectively mitigate the antiviral interferon response, but not the IL-6 response, suggesting neuropilin-1 as potential therapeutic target for stimulation of TLR7-mediated antiviral protection.


Subject(s)
COVID-19 , Dendritic Cells , Toll-Like Receptor 2 , Toll-Like Receptor 7 , COVID-19/immunology , COVID-19/pathology , Cytokines/metabolism , Dendritic Cells/immunology , Dendritic Cells/pathology , Humans , Interferon Type I/immunology , Interferon-alpha/immunology , Interleukin-6/immunology , Neuropilin-1/immunology , SARS-CoV-2 , Toll-Like Receptor 2/immunology , Toll-Like Receptor 7/immunology
15.
Front Immunol ; 12: 797390, 2021.
Article in English | MEDLINE | ID: covidwho-1686476

ABSTRACT

Phosphodiesterase 4 (PDE4) inhibitors are immunomodulatory drugs approved to treat diseases associated with chronic inflammatory conditions, such as COPD, psoriasis and atopic dermatitis. Tanimilast (international non-proprietary name of CHF6001) is a novel, potent and selective inhaled PDE4 inhibitor in advanced clinical development for the treatment of COPD. To begin testing its potential in limiting hyperinflammation and immune dysregulation associated to SARS-CoV-2 infection, we took advantage of an in vitro model of dendritic cell (DC) activation by SARS-CoV-2 genomic ssRNA (SCV2-RNA). In this context, Tanimilast decreased the release of pro-inflammatory cytokines (TNF-α and IL-6), chemokines (CCL3, CXCL9, and CXCL10) and of Th1-polarizing cytokines (IL-12, type I IFNs). In contrast to ß-methasone, a reference steroid anti-inflammatory drug, Tanimilast did not impair the acquisition of the maturation markers CD83, CD86 and MHC-II, nor that of the lymph node homing receptor CCR7. Consistent with this, Tanimilast did not reduce the capability of SCV2-RNA-stimulated DCs to activate CD4+ T cells but skewed their polarization towards a Th2 phenotype. Both Tanimilast and ß-methasone blocked the increase of MHC-I molecules in SCV2-RNA-activated DCs and restrained the proliferation and activation of cytotoxic CD8+ T cells. Our results indicate that Tanimilast can modulate the SCV2-RNA-induced pro-inflammatory and Th1-polarizing potential of DCs, crucial regulators of both the inflammatory and immune response. Given also the remarkable safety demonstrated by Tanimilast, up to now, in clinical studies, we propose this inhaled PDE4 inhibitor as a promising immunomodulatory drug in the scenario of COVID-19.


Subject(s)
COVID-19/immunology , Dendritic Cells , Phosphodiesterase 4 Inhibitors/pharmacology , RNA/pharmacology , SARS-CoV-2/physiology , Virus Activation/drug effects , CD8-Positive T-Lymphocytes/immunology , COVID-19/drug therapy , Cytokines/immunology , Dendritic Cells/immunology , Dendritic Cells/virology , Humans , Th1 Cells/immunology , Th2 Cells/immunology , Virus Activation/immunology
16.
Eur J Immunol ; 52(4): 646-655, 2022 04.
Article in English | MEDLINE | ID: covidwho-1661608

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), an infectious disease characterized by strong induction of inflammatory cytokines, progressive lung inflammation, and potentially multiorgan dysfunction. It remains unclear how SARS-CoV-2 infection leads to immune activation. The Spike (S) protein of SARS-CoV-2 has been suggested to trigger TLR4 and thereby activate immunity. Here, we have investigated the role of TLR4 in SARS-CoV-2 infection and immunity. Neither exposure of isolated S protein, SARS-CoV-2 pseudovirus nor primary SARS-CoV-2 isolate induced TLR4 activation in a TLR4-expressing cell line. Human monocyte-derived DCs express TLR4 but not angiotensin converting enzyme 2 (ACE2), and DCs were not infected by SARS-CoV-2. Notably, neither S protein nor SARS-CoV-2 induced DC maturation or cytokines, indicating that both S protein and SARS-CoV-2 virus particles do not trigger extracellular TLRs including TLR4. Ectopic expression of ACE2 in DCs led to efficient infection by SARS-CoV-2 and, strikingly, efficient type I IFN and cytokine responses. These data strongly suggest that not extracellular TLRs but intracellular viral sensors are key players in sensing SARS-CoV-2. These data imply that SARS-CoV-2 escapes direct sensing by TLRs, which might underlie the lack of efficient immunity to SARS-CoV-2 early during infection.


Subject(s)
COVID-19 , Dendritic Cells , Spike Glycoprotein, Coronavirus , Toll-Like Receptor 4 , COVID-19/immunology , Cell Line , Dendritic Cells/immunology , Humans , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/immunology , Toll-Like Receptor 4/immunology
17.
Nature ; 603(7902): 587-598, 2022 03.
Article in English | MEDLINE | ID: covidwho-1655590

ABSTRACT

SARS-CoV-2 infection is benign in most individuals but, in around 10% of cases, it triggers hypoxaemic COVID-19 pneumonia, which leads to critical illness in around 3% of cases. The ensuing risk of death (approximately 1% across age and gender) doubles every five years from childhood onwards and is around 1.5 times greater in men than in women. Here we review the molecular and cellular determinants of critical COVID-19 pneumonia. Inborn errors of type I interferons (IFNs), including autosomal TLR3 and X-chromosome-linked TLR7 deficiencies, are found in around 1-5% of patients with critical pneumonia under 60 years old, and a lower proportion in older patients. Pre-existing auto-antibodies neutralizing IFNα, IFNß and/or IFNω, which are more common in men than in women, are found in approximately 15-20% of patients with critical pneumonia over 70 years old, and a lower proportion in younger patients. Thus, at least 15% of cases of critical COVID-19 pneumonia can be explained. The TLR3- and TLR7-dependent production of type I IFNs by respiratory epithelial cells and plasmacytoid dendritic cells, respectively, is essential for host defence against SARS-CoV-2. In ways that can depend on age and sex, insufficient type I IFN immunity in the respiratory tract during the first few days of infection may account for the spread of the virus, leading to pulmonary and systemic inflammation.


Subject(s)
COVID-19/genetics , COVID-19/immunology , Interferon Type I/immunology , Age Distribution , Autoantibodies/immunology , COVID-19/mortality , COVID-19/pathology , Critical Illness , Dendritic Cells/immunology , Genome-Wide Association Study , Humans , Interferon Type I/genetics , Sex Distribution , Toll-Like Receptor 3/deficiency , Toll-Like Receptor 7/deficiency , Toll-Like Receptor 7/genetics
18.
PLoS Pathog ; 18(1): e1010255, 2022 01.
Article in English | MEDLINE | ID: covidwho-1649753

ABSTRACT

Nucleoside modified mRNA combined with Acuitas Therapeutics' lipid nanoparticles (LNPs) has been shown to support robust humoral immune responses in many preclinical animal vaccine studies and later in humans with the SARS-CoV-2 vaccination. We recently showed that this platform is highly inflammatory due to the LNPs' ionizable lipid component. The inflammatory property is key to support the development of potent humoral immune responses. However, the mechanism by which this platform drives T follicular helper (Tfh) cells and humoral immune responses remains unknown. Here we show that lack of Langerhans cells or cDC1s neither significantly affected the induction of PR8 HA and SARS-CoV-2 RBD-specific Tfh cells and humoral immune responses, nor susceptibility towards the lethal challenge of influenza and SARS-CoV-2. However, the combined deletion of these two DC subsets led to a significant decrease in the induction of PR8 HA and SARS-CoV-2 RBD-specific Tfh cell and humoral immune responses. Despite these observed defects, these mice remained protected from lethal influenza and SARS-CoV-2 challenges. We further found that IL-6, unlike neutrophils, was required to generate normal Tfh cells and antibody responses, but not for protection from influenza challenge. In summary, here we bring evidence that the mRNA-LNP platform can support the induction of protective immune responses in the absence of certain innate immune cells and cytokines.


Subject(s)
COVID-19 Vaccines/immunology , Dendritic Cells/immunology , Influenza Vaccines/immunology , Langerhans Cells/immunology , Liposomes/immunology , Vaccines, Synthetic/immunology , /immunology , Animals , COVID-19/immunology , Mice , Nanoparticles , Orthomyxoviridae Infections/immunology , SARS-CoV-2/immunology
19.
Pharmacol Res ; 177: 106092, 2022 03.
Article in English | MEDLINE | ID: covidwho-1639171

ABSTRACT

Kinsenoside (KD) exhibits anti-inflammatory and immunosuppressive effects. Dendritic cells (DCs) are critical regulators of the pathologic inflammatory milieu in liver fibrosis (LF). Herein, we explored whether and how KD repressed development of LF via DC regulation and verified the pathway involved in the process. Given our analysis, both KD and adoptive transfer of KD-conditioned DCs conspicuously reduced hepatic histopathological damage, proinflammatory cytokine release and extracellular matrix deposition in CCl4-induced LF mice. Of note, KD restrained the LF-driven rise in CD86, MHC-II, and CCR7 levels and, simultaneously, upregulated PD-L1 expression on DCs specifically, which blocked CD8+T cell activation. Additionally, KD reduced DC glycolysis, maintained DCs immature, accompanied by IL-12 decrease in DCs. Inhibiting DC function by KD disturbed the communication of DCs and HSCs with the expression or secretion of α-SMA and Col-I declined in the liver. Mechanistically, KD suppressed the phosphorylation of PI3K-AKT driven by LF or PI3K agonist, followed by enhanced nuclear transport of FoxO1 and upregulated interaction of FoxO1 with the PD-L1 promoter in DCs. PI3K inhibitor or si-IL-12 acting on DC could relieve LF, HSC activation and diminish the effect of KD. In conclusion, KD suppressed DC maturation with promoted PD-L1 expression via PI3K-AKT-FoxO1 and decreased IL-12 secretion, which blocked activation of CD8+T cells and HSCs, thereby alleviating liver injury and fibro-inflammation in LF.


Subject(s)
Hepatitis , Phosphatidylinositol 3-Kinases , 4-Butyrolactone/analogs & derivatives , Animals , B7-H1 Antigen , Dendritic Cells/metabolism , Forkhead Box Protein O1 , Inflammation/drug therapy , Interleukin-12 , Mice , Monosaccharides , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism
20.
Front Immunol ; 12: 781432, 2021.
Article in English | MEDLINE | ID: covidwho-1634671

ABSTRACT

Despite many studies on the immune characteristics of Coronavirus disease 2019 (COVID-19) patients in the progression stage, a detailed understanding of pertinent immune cells in recovered patients is lacking. We performed single-cell RNA sequencing on samples from recovered COVID-19 patients and healthy controls. We created a comprehensive immune landscape with more than 260,000 peripheral blood mononuclear cells (PBMCs) from 41 samples by integrating our dataset with previously reported datasets, which included samples collected between 27 and 47 days after symptom onset. According to our large-scale single-cell analysis, recovered patients, who had severe symptoms (severe/critical recovered), still exhibited peripheral immune disorders 1-2 months after symptom onset. Specifically, in these severe/critical recovered patients, human leukocyte antigen (HLA) class II and antigen processing pathways were downregulated in both CD14 monocytes and dendritic cells compared to healthy controls, while the proportion of CD14 monocytes increased. These may lead to the downregulation of T-cell differentiation pathways in memory T cells. However, in the mild/moderate recovered patients, the proportion of plasmacytoid dendritic cells increased compared to healthy controls, accompanied by the upregulation of HLA-DRA and HLA-DRB1 in both CD14 monocytes and dendritic cells. In addition, T-cell differentiation regulation and memory T cell-related genes FOS, JUN, CD69, CXCR4, and CD83 were upregulated in the mild/moderate recovered patients. Further, the immunoglobulin heavy chain V3-21 (IGHV3-21) gene segment was preferred in B-cell immune repertoires in severe/critical recovered patients. Collectively, we provide a large-scale single-cell atlas of the peripheral immune response in recovered COVID-19 patients.


Subject(s)
COVID-19/immunology , Dendritic Cells/immunology , Monocytes/immunology , RNA-Seq , SARS-CoV-2/immunology , Single-Cell Analysis , COVID-19/genetics , Female , Humans , Male
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