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1.
J Clin Invest ; 131(20)2021 10 15.
Article in English | MEDLINE | ID: covidwho-1470547

ABSTRACT

BACKGROUNDMultisystem inflammatory syndrome in children (MIS-C) is a rare but potentially severe illness that follows exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Kawasaki disease (KD) shares several clinical features with MIS-C, which prompted the use of intravenous immunoglobulin (IVIG), a mainstay therapy for KD. Both diseases share a robust activation of the innate immune system, including the IL-1 signaling pathway, and IL-1 blockade has been used for the treatment of both MIS-C and KD. The mechanism of action of IVIG in these 2 diseases and the cellular source of IL-1ß have not been defined.METHODSThe effects of IVIG on peripheral blood leukocyte populations from patients with MIS-C and KD were examined using flow cytometry and mass cytometry (CyTOF) and live-cell imaging.RESULTSCirculating neutrophils were highly activated in patients with KD and MIS-C and were a major source of IL-1ß. Following IVIG treatment, activated IL-1ß+ neutrophils were reduced in the circulation. In vitro, IVIG was a potent activator of neutrophil cell death via PI3K and NADPH oxidase, but independently of caspase activation.CONCLUSIONSActivated neutrophils expressing IL-1ß can be targeted by IVIG, supporting its use in both KD and MIS-C to ameliorate inflammation.FUNDINGPatient Centered Outcomes Research Institute; NIH; American Asthma Foundation; American Heart Association; Novo Nordisk Foundation; NIGMS; American Academy of Allergy, Asthma and Immunology Foundation.


Subject(s)
COVID-19/complications , Immunoglobulins, Intravenous/therapeutic use , Mucocutaneous Lymph Node Syndrome/immunology , Mucocutaneous Lymph Node Syndrome/therapy , Systemic Inflammatory Response Syndrome/immunology , Systemic Inflammatory Response Syndrome/therapy , COVID-19/blood , COVID-19/immunology , COVID-19/therapy , Case-Control Studies , Cell Death/immunology , Cell Lineage/immunology , Child , Child, Preschool , Fas Ligand Protein/immunology , Female , Humans , Infant , Interleukin-1beta/antagonists & inhibitors , Interleukin-1beta/blood , Leukocyte Count , Male , Mucocutaneous Lymph Node Syndrome/blood , Neutrophil Activation , Neutrophils/classification , Neutrophils/immunology , Neutrophils/pathology , Systemic Inflammatory Response Syndrome/blood
2.
JCI Insight ; 6(9)2021 05 10.
Article in English | MEDLINE | ID: covidwho-1228934

ABSTRACT

SARS coronavirus 2 (SARS-CoV-2) is a novel viral pathogen that causes a clinical disease called coronavirus disease 2019 (COVID-19). Although most COVID-19 cases are asymptomatic or involve mild upper respiratory tract symptoms, a significant number of patients develop severe or critical disease. Patients with severe COVID-19 commonly present with viral pneumonia that may progress to life-threatening acute respiratory distress syndrome (ARDS). Patients with COVID-19 are also predisposed to venous and arterial thromboses that are associated with a poorer prognosis. The present study identified the emergence of a low-density inflammatory neutrophil (LDN) population expressing intermediate levels of CD16 (CD16Int) in patients with COVID-19. These cells demonstrated proinflammatory gene signatures, activated platelets, spontaneously formed neutrophil extracellular traps, and enhanced phagocytic capacity and cytokine production. Strikingly, CD16Int neutrophils were also the major immune cells within the bronchoalveolar lavage fluid, exhibiting increased CXCR3 but loss of CD44 and CD38 expression. The percentage of circulating CD16Int LDNs was associated with D-dimer, ferritin, and systemic IL-6 and TNF-α levels and changed over time with altered disease status. Our data suggest that the CD16Int LDN subset contributes to COVID-19-associated coagulopathy, systemic inflammation, and ARDS. The frequency of that LDN subset in the circulation could serve as an adjunct clinical marker to monitor disease status and progression.


Subject(s)
Blood Coagulation Disorders/blood , Blood Coagulation Disorders/etiology , COVID-19/blood , COVID-19/complications , Neutrophils/immunology , SARS-CoV-2 , Adult , Aged , Aged, 80 and over , Biomarkers/blood , Blood Coagulation Disorders/immunology , COVID-19/immunology , Cytokines/blood , Female , GPI-Linked Proteins/blood , Hospitalization , Humans , Inflammation Mediators/blood , Male , Middle Aged , Neutrophils/classification , Pandemics , Phagocytosis , Platelet Activation , Receptors, IgG/blood , Respiratory Distress Syndrome/blood , Respiratory Distress Syndrome/etiology , Respiratory Distress Syndrome/immunology , Severity of Illness Index
3.
Crit Care ; 25(1): 50, 2021 02 06.
Article in English | MEDLINE | ID: covidwho-1068599

ABSTRACT

BACKGROUND: Although the immune function of neutrophils in sepsis has been well described, the heterogeneity of neutrophils remains unclear during the process of sepsis. METHODS: In this study, we used a mouse CLP model to simulate the clinical scenario of patients with sepsis, neutrophil infiltration, abnormal distribution and dysfunction was analyzed. LPS was used to stimulate neutrophils in vitro to simulate sepsis; single-cell gene sequencing technology was used to explore the immunological typing. To explore the immunological function of immunosuppressive neutrophils, PD-L1 knockout neutrophils were cocultured with lymphocytes from wild-type mice. RESULTS: We found that neutrophils presented variant dysfunction at the late stage of sepsis, including inhibition of apoptosis, seriously damaged chemotaxis and extensive infiltration into the tissues. Single-cell RNA sequencing revealed that multiple subclusters of neutrophils were differentiated after LPS stimulation. The two-dimensional spatial distribution analysis showed that Foxp3+ T cells were much closer to Ly-6G than the CD4+ and CD8+ cells, indicating that infiltrated neutrophils may play immunomodulatory effect on surrounding T-regs. Further observations showed that LPS mediates PD-L1 over expression through p38α-MSK1/-MK2 pathway in neutrophils. The subsets of highly expressed PD-L1 exert immunosuppressive effect under direct contact mode, including inhibition of T cell activation and induction of T cell apoptosis and trans-differentiation. CONCLUSIONS: Taken together, our data identify a previously unknown immunosuppressive subset of neutrophils as inhibitory neutrophil in order to more accurately describe the phenotype and characteristics of these cells in sepsis.


Subject(s)
Genetic Heterogeneity , Neutrophils/classification , Sepsis/blood , Animals , Disease Models, Animal , Leukocyte Count/methods , Leukocyte Count/statistics & numerical data , Mice , Mice, Inbred C57BL , Neutrophils/physiology , Polymerase Chain Reaction/methods , Sepsis/genetics
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