Study of Immune Response During SARS-CoV-2 Infection - (COVID-19)

Since March 2020, Europe has been facing the spread of Coronavirus disease 2019 (COVID-19), an emerging infectious disease of viral zoonosis type, caused by the coronavirus SARS-CoV-21. This virus is responsible for an epidemic in Wuhan in November 2019 and a pandemic in March 2020. The mode of transmission, both respiratory and by contact, carried by microdroplets emitted by an infected person and inhaled by a person nearby, induces a very high contagiousness rate2. In the majority of cases, CoV-2-SARS infection is not very symptomatic, but some evolve into severe forms, particularly in frail people: elderly subjects, those affected by chronic diseases (diabetes, obesity or cancer) or those undergoing immunosuppressive treatments. There is still little information on the reasons why some will develop a severe form while others will remain asymptomatic. The immune response is little studied in this context.

Functional study of the cellular immune response has shown its interest in predicting the risk of infection in different cohorts, particularly in renal insufficiency subjects awaiting transplantation with an over-risk of developing an infection within a year in patients with a low level of gamma interferon (INFγ: main anti-viral cytokine) after non-specific stimulation of T lymphocytes.

A study published the clinical characteristics of 41 patients infected with coronavirus at the Huanan seafood market (first contact cases). Despite a similar clinical symptomatology: cough (76%) and fever (98%), some patients required rapid ventilatory assistance. These patients had an increased production of inflammatory cytokines: IL2, IL7, IL10, GSCF, IP10, MCP1, MIP1A, and TNFα3.

Here, the objective is to identify cytokine profiles in subjects exposed to or infected with SARS-CoV-2 that can predict their risk of developing a severe pauci-symptomatic form at the time of exposure or during the development of a severe form. the team believes that the immune response to this infection is a major factor in the risk of developing an asymptomatic infection, a flu-like symptomatology or a respiratory failure syndrome (ARDS).3,4 The team believes that the immune response to this infection is a major factor in the risk of developing an asymptomatic infection, a flu-like symptomatology or a respiratory failure syndrome (ARDS). The team thus wishes to better direct patients to appropriate care structures to optimise the care pathway (ambulatory, infectiology, intensive care), respirators and number of beds so as not to overload the staff) and to enable treatments to be personalised and adapted as best as possible: corticosteroids, immunomodulators, antivirals.

The study will be based on 2 axes: a first clinical axis (i) and a cellular axis (ii).

In its clinical part (i), the intensity of the immune response in COVID19 subjects presenting different forms of the disease (asymptomatic, moderate and severe forms) will be measured. These subjects will be recruited from two different patient populations:

• Subjects at risk of infection with CoV-2-SARS. We will test the Th1 response of caregivers at the time of their entry into a COVID-19 service by measuring the level of INFγ released after non-specific T-cell stimulation. The hypothesis is that a high level of INFγ at the time of exposure prevents the risk of developing severe disease and directs the patient towards less symptomatic forms. Thus, thanks to serological tests, it will be possible to determine retrospectively in this group how many subjects presented an asymptomatic form and thus to determine with the help of a functional test mimicking a viral infection the level of IFNγ measured after stimulation.
• Patients with CoV-2-SARS infection hospitalized in the Infectious Diseases Department with a moderate form or in resuscitation with a severe form of COVID.19 The evaluation of these patients on admission using a functional test mimicking a viral infection the rate of IFNγ measured after stimulation will be carried out.

The levels of IFNγ measured after stimulation will be compared in these 3 groups of COVID19 patients if the evolution towards inflammatory cytokinic profiles at D0, D5 and D10 can predict the risk of developing ARDS...

Then, the impact of different therapeutic interventions on the secretion of INFγ will be tested in vitro in an ancillary study (ii): anti-inflammatory, corticosteroids, anti-IL6, IL2, IL7, chloroquine on their capacity to produce anti-viral cytokines of the type INFγ on different T cells while limiting the production of pro-inflammatory cytokines by cells of innate immunity, from healthy subjects, COVID-19 subjects with a mildly symptomatic form or COVID-19 subjects with ARDS.