scholarly journals Endothelial dysfunction determines severe COVID-19 in combination with dysregulated lymphocyte responses and cytokine networks

Author(s):  
Louisa Ruhl ◽  
Isabell Pink ◽  
Jenny F Kuehne ◽  
Kerstin Beushausen ◽  
Jana Keil ◽  
...  

The systemic processes involved in the manifestation of life-threatening COVID-19 and in disease recovery are still incompletely understood, despite investigations focusing on the dysregulation of immune responses after SARS-CoV-2 infection. To define hallmarks of severe COVID-19 and disease recovery in convalescent patients, we combined analyses of immune cells and cytokine/chemokine networks with endothelial activation and injury. ICU patients displayed an altered immune signature with prolonged lymphopenia but expansion of granulocytes and plasmablasts along with activated and terminally differentiated T and NK cells and high levels of SARS-CoV-2-specific antibodies. Core signature of seven plasma proteins revealed a highly inflammatory microenvironment in addition to endothelial injury in severe COVID-19. Changes within this signature were associated with either disease progression or recovery. In summary, our data suggest that besides a strong inflammatory response, severe COVID-19 is driven by endothelial activation and barrier disruption, whereby recovery depends on the regeneration of the endothelial integrity.

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Louisa Ruhl ◽  
Isabell Pink ◽  
Jenny F. Kühne ◽  
Kerstin Beushausen ◽  
Jana Keil ◽  
...  

AbstractThe systemic processes involved in the manifestation of life-threatening COVID-19 and in disease recovery are still incompletely understood, despite investigations focusing on the dysregulation of immune responses after SARS-CoV-2 infection. To define hallmarks of severe COVID-19 in acute disease (n = 58) and in disease recovery in convalescent patients (n = 28) from Hannover Medical School, we used flow cytometry and proteomics data with unsupervised clustering analyses. In our observational study, we combined analyses of immune cells and cytokine/chemokine networks with endothelial activation and injury. ICU patients displayed an altered immune signature with prolonged lymphopenia but the expansion of granulocytes and plasmablasts along with activated and terminally differentiated T and NK cells and high levels of SARS-CoV-2-specific antibodies. The core signature of seven plasma proteins revealed a highly inflammatory microenvironment in addition to endothelial injury in severe COVID-19. Changes within this signature were associated with either disease progression or recovery. In summary, our data suggest that besides a strong inflammatory response, severe COVID-19 is driven by endothelial activation and barrier disruption, whereby recovery depends on the regeneration of the endothelial integrity.


1995 ◽  
Vol 181 (1) ◽  
pp. 21-31 ◽  
Author(s):  
S Saadi ◽  
J L Platt

The barrier function of blood vessels is though to be regulated at least in part by endothelium. This concept is supported by the dramatic loss of barrier function occurring in the hyperacute rejection of vascularized grafts mediated by anti-endothelial cell (EC) antibodies and complement. In this process, the endothelium is not destroyed but instead loses the ability to retain blood cells and plasma proteins within capillaries. The noncytotoxic mechanism that allows this change in EC function has been unknown. Here we report that within 10 to 20 min of exposure to human xenoreactive natural antibodies and complement, porcine EC undergo alterations in cell shape and in the cytoskeleton that disrupt monolayer integrity and lead to formation of intercellular gaps. Gap formation is not associated with cell death but requires the complement complex C5b67. The gaps induced by anti-EC antibodies and complement are transient; gap closure requires formation of C5b-9 complexes on the cells and the rate of recovery depends on the release of cellular products into the medium. Preincubation of EC with dibutyryl cAMP (0.5 mM) prevents gap formation and disruption of the cytoskeleton caused by antibodies and complement. These results provide evidence that the integrity of endothelium is regulated by components of the complement system and suggest a mechanism that may explain the prominent loss of endothelial integrity seen in humoral immune responses.


2000 ◽  
Vol 113 (20) ◽  
pp. 3549-3550
Author(s):  
M.J. Townsend ◽  
A.N. McKenzie

The Cytokine Network edited by Fran Balkwill Frontiers in Molecular Biology Series (seried editors B. D. Hames and D. M. Glover) Oxford University Press (2000) pp. 199. ISBN 019–963-702-4. 29.95 Cytokines are small- to medium-sized proteins and glycoproteins that mediate highly potent biological effects on many cell types. They have critical roles in haematopoiesis, inflammatory responses and the development and maintenance of immune responses. Importantly, cytokines act in networks or cascades. Typical properties of cytokines in these networks are pleiotropy, redundancy, synergistic activity and antagonistic effects upon each other. Knowledge of how these networks are comprised and operate is important in understanding how cytokines mediate their diverse effects on biological systems. In The Cytokine Network, Fran Balkwill brings together some distinguished investigators to produce a survey, in eight independently written and concise chapters, of the complex cytokine and chemokine (chemotactic cytokine) networks present in mouse and man. The ever-increasing complexity of cytokine networks is introduced in the initial chapter with a summary of the bioinformatics approach for the high throughput discovery of novel cytokines and chemokines. The burgeoning number of newly identified chemokines, chemokine receptors and TNF family members reminds us that our understanding of the cytokine network is extremely dynamic and that our interpretation of some pathways will change with the characterisation of new factors. The following chapters address the interactions of the cytokines, both with reference to their signalling pathways (well summarised in chapter 2) and their biological roles. The point is made that cytokines should be studied as a network rather than individually and that in vivo models, including the generation of transgenic and gene knock-out mice, are powerful tools for doing so. Rheumatoid arthritis is presented as a well-studied example of how inappropriate regulation of pro- and anti-inflammatory cytokines mediates autoimmune disease, and examples of immunoregulatory cytokines that have both overlapping and independent regulatory effects on inflammation are demonstrated within this context. The important Th1/Th2 paradigm receives a dedicated chapter. T helper type 1 and T helper type 2 cells produce distinct and restricted patterns of cytokines that cross regulate each other and thus mediate different types of immune response. The development of these subsets of T helper cells from a common precursor, as part of a developing immune response, has important effects on the cytokine network. The mechanisms of Th1/Th2 development together with modulating factors and associated intracellular signalling are well described. The chapter summarises well the role of Th1/Th2 development in human diseases with reference to transplantation immunology, neonatal development, autoimmune diseases, and atopic diseases. A very interesting review of the relationships between cytokines and viruses is given. Cytokines are critically involved in mediating antiviral immune responses. However, homologues of cytokines, chemokines and their receptors, after being ‘hijacked’ from the host genome and undergoing evolution along with the viral genes, are utilised by viruses themselves to promote their replication and to suppress immune responses against them. The chapter describes several noteworthy examples of these virally encoded cytokines and receptors together with their roles in vivo. This is a well-written book that provides a good introduction to understanding how cytokines and chemokines interact as a network in the immune system. The volume links together diverse subjects that include cytokine signalling, genomic polymorphism, disease processes and immunotherapies. The book does not aim to describe comprehensively the biology of all the currently known cytokines and chemokines and therefore alternative texts should be considered for this. (ABSTRACT TRUNCATED)


Author(s):  
Thomas H. Sharp ◽  
Aimee L. Boyle ◽  
Christoph A. Diebolder ◽  
Alexander Kros ◽  
Abraham J. Koster ◽  
...  

Antigen binding by serum Ig-M (IgM) protects against microbial infections and helps to prevent autoimmunity, but causes life-threatening diseases when mistargeted. How antigen-bound IgM activates complement-immune responses remains unclear. We present cryoelectron tomography structures of IgM, C1, and C4b complexes formed on antigen-bearing lipid membranes by normal human serum at 4 °C. The IgM-C1-C4b complexes revealed C4b product release as the temperature-limiting step in complement activation. Both IgM hexamers and pentamers adopted hexagonal, dome-shaped structures with Fab pairs, dimerized by hinge domains, bound to surface antigens that support a platform of Fc regions. C1 binds IgM through widely spread C1q-collagen helices, with C1r proteases pointing outward and C1s bending downward and interacting with surface-attached C4b, which further interacts with the adjacent IgM-Fab2and globular C1q-recognition unit. Based on these data, we present mechanistic models for antibody-mediated, C1q-transmitted activation of C1 and for C4b deposition, while further conformational rearrangements are required to form C3 convertases.


2008 ◽  
Vol 15 (4) ◽  
pp. 691-696 ◽  
Author(s):  
Ralf Geiben-Lynn ◽  
John R. Greenland ◽  
Kwesi Frimpong-Boateng ◽  
Norman L. Letvin

ABSTRACT While a new generation of vaccine vectors has been developed for eliciting cellular immune responses, little is known about the optimal routes for their administration or about the ramifications of the kinetics of in vivo vaccine antigen expression for immunogenicity. We evaluated the kinetics of vaccine antigen expression by real-time in vivo photon imaging and showed dramatic differences in these kinetics using different vectors and different routes of administration. Further, using a gamma interferon enzyme-linked immunospot assay to measure T-lymphocyte immune responses, we observed an association between the kinetics of vaccine antigen expression in vivo and the magnitude of vaccine-elicited memory T-lymphocyte responses. These results highlight the utility of the real-time in vivo photon-imaging technology in evaluating novel immunization strategies and suggest an association between the kinetics of vaccine antigen clearance and the magnitude of vaccine-elicited T-lymphocyte memory immune responses.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Liis Haljasmägi ◽  
Ahto Salumets ◽  
Anna Pauliina Rumm ◽  
Meeri Jürgenson ◽  
Ekaterina Krassohhina ◽  
...  

AbstractSARS-CoV-2 infection has a risk to develop into life-threatening COVID-19 disease. Whereas age, hypertension, and chronic inflammatory conditions are risk factors, underlying host factors and markers for disease severity, e.g. requiring intensive care unit (ICU) treatment, remain poorly defined. To this end, we longitudinally profiled blood inflammation markers, antibodies, and 101 plasma proteins of hospitalized COVID-19 patients who did or did not require ICU admission. While essentially all patients displayed SARS-CoV-2-specific antibodies and virus-neutralization capacity within 12–15 days, a rapid, mostly transient upregulation of selective inflammatory markers including IL-6, CXCL10, CXCL11, IFNγ, IL-10, and monocyte-attracting CCL2, CCL7 and CCL8, was particularly evident in ICU patients. In addition, there was consistent and sustained upregulation of apoptosis-associated proteins CASP8, TNFSF14, HGF, and TGFB1, with HGF discriminating between ICU and non-ICU cohorts. Thus, COVID-19 is associated with a selective inflammatory milieu within which the apoptotic pathway is a cardinal feature with potential to aid risk-based patient stratification.


2002 ◽  
Vol 76 (6) ◽  
pp. 2817-2826 ◽  
Author(s):  
Georg M. Lauer ◽  
Tam N. Nguyen ◽  
Cheryl L. Day ◽  
Gregory K. Robbins ◽  
Theresa Flynn ◽  
...  

ABSTRACT Both human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) lead to chronic infection in a high percentage of persons, and an expanding epidemic of HIV-1-HCV coinfection has recently been identified. These individuals provide an opportunity for simultaneous assessment of immune responses to two viral infections associated with chronic plasma viremia. In this study we analyzed the breadth and magnitude of the CD8+- and CD4+-T-lymphocyte responses in 22 individuals infected with both HIV-1 and HCV. A CD8+-T-lymphocyte response against HIV-1 was readily detected in all subjects over a broad range of viral loads. In marked contrast, HCV-specific CD8+-T-lymphocyte responses were rarely detected, despite viral loads in plasma that were on average 1,000-fold higher. The few HCV-specific responses that were observed were relatively weak and limited in breadth. CD4-proliferative responses against HIV-1 were detected in about half of the coinfected subjects tested, but no proliferative response against any HCV protein was found in these coinfected persons. These data demonstrate a major discordance in immune responses to two persistent RNA viruses. In addition, they show a consistent and profound impairment in cellular immune responses to HCV compared to HIV-1 in HIV-1-HCV-coinfected persons.


2013 ◽  
Vol 208 (2) ◽  
pp. 260-270 ◽  
Author(s):  
James T. Frencher ◽  
Bridgett K. Ryan-Pasyeur ◽  
Dan Huang ◽  
Ri Cheng Wang ◽  
Phillip D. McMullen ◽  
...  

2008 ◽  
Vol 38 (6) ◽  
pp. 1689-1699 ◽  
Author(s):  
Anja K. Mayer ◽  
Holger Bartz ◽  
Fabian Fey ◽  
Lotte M. Schmidt ◽  
Alexander H. Dalpke

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