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Source: COVID-19 Immunology  Jul 20, 2021  2 years, 8 months, 4 weeks, 17 hours, 7 minutes ago

University Of California Study Shows That Exhausted T Cells Are Linked To Increased Risk Of COVID-19 Death

University Of California Study Shows That Exhausted T Cells Are Linked To Increased Risk Of COVID-19 Death
Source: COVID-19 Immunology  Jul 20, 2021  2 years, 8 months, 4 weeks, 17 hours, 7 minutes ago
A new study by researchers from the University of California-San Francisco and the Gladstone Institutes-California has shown that exhausted T cells are linked to increased risk of COVID-19 mortality.

Despite T cells being key players in SARS-CoV-2 immunity, little is known about the phenotypic features of SARS-CoV-2-specific T cells associated with recovery from the COVID-19 disease.
 
The study team analyzed T cells from 34 individuals with COVID-19 with severity ranging from mild (outpatient) to critical, culminating in death.
 
Interestingly it was found that relative to individuals who succumbed, individuals who recovered from severe COVID-19 harbor elevated and increasing numbers of SARS-CoV-2-specific T cells capable of homeostatic proliferation.
 
However in contrast, fatal COVID-19 cases display elevated numbers of SARS-CoV-2-specific regulatory T cells and a time-dependent escalation in activated bystander CXCR4+ T cells, as assessed by longitudinal sampling.
 
Along with the demonstration of increased proportions of inflammatory CXCR4+ T cells in the lungs of individuals with severe COVID-19, the study findings support a model where lung-homing T cells activated through bystander effects contribute to immunopathology, whereas a robust, non-suppressive SARS-CoV-2-specific T cell response limits pathogenesis and promotes recovery from severe COVID-19.
 
The key takeaways from the study are:
 
-1) Dysfunctional spike-specific T cells are characteristic of severe COVID-19
 
-2) Spike-specific CD127+ Th1 cells are increased in survivors of severe COVID-19
 
-3) Spike-specific Treg cells and IL6+ CD8+ T cells are increased in fatal COVID-19
 
-4) Escalation of activated lung-homing CXCR4+ T cells is associated with fatal COVID-19.
 
The study findings were published in the peer reviewed journal: Cell Reports
https://www.cell.com/cell-reports/fulltext/S2211-1247(21)00827-5
 
Typically T cells are an essential player in the immune system and have been integral to recovering from severe COVID-19 infection. However, some T cells may be more helpful than others.
 
The study team however found a correlation between high numbers of inflammatory CXCR4+ T cells and regulatory T cells specific to SARS-CoV-2 and dying from infection.
 
In contrast, individuals who recovered from severe COVID-19 illness were more likely to have many SARS-CoV-2-specific T cells that perform homeostatic proliferation.
 
Corresponding author Dr Kara L. Lynch from the department of Laboratory Medicine, University of California- San Francisco told Thailand Medical News,  “Our findings overall support a beneficial rather than immunopathologic role of effector SARS-CoV-2-specific T cells during severe acute infection.”
 
From the study findings, the study team suggest COVID-19 strategies should be geared tow