Covid vaccine © Adobe Stock

Teams from the immunology department and internal medicine department 2 of the Pitié-Salpêtrière AP-HP hospital, Sorbonne University and Inserm, measured the antibody and cellular responses generated by a messenger RNA vaccine in patients with systemic lupus (LS). This work, coordinated by Professors Guy Gorochov (CIMI-Paris) and Zahir Amoura (National Lupus Reference Center) shows that vaccination is both well tolerated and effective, even against worrying variants. For the first time, the factors associated with a poor vaccine response in some of these patients have been identified in order to better anticipate who should benefit from reinforced protective measures and / or adapted vaccine protocols. This work was the subjectfrom an October 4 publication in the journal Annals of Rheumatic Diseases.

Systemic lupus (LS) is a chronic autoimmune disease preferentially affecting young women. The attacks are mainly articular, cutaneous, renal, cardio-respiratory, neurological and hematological. The disease is characterized by the production of autoantibodies directed against nuclear antigens. It typically evolves in spurts. For these patients, two hypotheses were considered concerning the effects of the messenger RNA vaccination: the occurrence of more frequent adverse effects, or even the exacerbation of the disease in patients with LS, or an ineffective response to vaccination for patients with LS. patients on immunosuppressants.

The teams compared the effects of vaccination in 136 patients with systemic lupus (LS). 126 of them, who received 2 doses of the BNT162b2 vaccine (Pfizer / BioNTech) and followed the entire clinical-biological surveillance course, were included in the final analysis. The two vaccine doses were separated by 21 to 28 days with a clinical-biological evaluation from the day of the first injection and up to 42 days after it (D42). The clinical activity of the disease was measured at each visit (D0, D7-14, D21-28, D42) using standardized indices. Some patients were vaccinated while their lupus disease was active.

During the 40-day follow-up, no significant change in disease activity was observed, either in patients active at the time of vaccination, or in those who showed no signs of the disease. The only notable side effects related to the vaccination were mild or moderate pain at the injection site.

A pseudo virus expressing the envelope (Spike) of the reference SARS-CoV-2 (D614G) or that of the variants B.1.1.7 (Alpha), B.1.617.1 (Kappa), B.1.617.2 (Delta ), B.1.617.3, B.1.1.28 (Gamma) and B.1.351 (Beta) was used to measure the neutralizing activity of the serum collected on D42. 82% of the patients tested were able to effectively neutralize the reference strain and the Alpha variant. As expected, a slight decrease in the neutralization efficiency of the other variants was noted, mainly for the Beta variant, neutralized by the serum of 60% of the patients tested, while the Delta variant was neutralized in 76% of cases.

At present, the vaccine response criteria are still poorly understood. Among the various treatments received against lupus, this work was able to combine methotrexate and mycophenolate mofetil, two immunosuppressive treatments, with lower rates of IgG responses to the human receptor binding domain (RBD) of SARS-CoV-2. (independently of immunosuppressive treatments). Long-term corticosteroid intake (median prednisone dose: 19 mg / day) was not, however, associated with a poor vaccine response.

This work evaluated certain therapeutic and biological criteria of vaccine response.

A decreased vaccine response, i.e. a lower level of protective antibodies, has been shown when the patient with LS is treated with methotrexate or mycophenolate mofetil (two immunosuppressive treatments). Conversely, taking corticosteroids, regularly prescribed in LS, was not associated with a poor vaccine response.

The study also looked at the immune status of patients at the start of the vaccination protocol. The level of circulating naive B lymphocytes (CD19 + CD27-IgD +) and the overall concentration of IgG antibodies on D0 were associated with a more intense vaccine response.

In conclusion, the vaccination of lupus patients with BNT162b2 is very well tolerated and its efficacy is reduced only in patients treated with methotrexate or mycophenolate mofetil. A pre-existing alteration in the adaptive humoral response is also associated with the poor vaccine response.

Electron microscopy of a cell infected with SARS-CoV-2 © Philippe Roingeard, Anne Bull-Maurer, Sonia Georgeault, unité Inserm U1259 MAVIVH & Université de Tours, France.

The severe form of Covid-19 is known to be associated with the excessive elevation of many cytokines, a condition termed “cytokine storm”. Therapy with biological agents intended to block these cytokines, for example anti-interleukin-6 or anti-interleukin-1 antibodies, was already tried, albeit with a limited success. However, a study recently published in the Journal of Allergy and Clinical Immunology  shows that there are at least two distinct types of cytokine storms induced by SARS-CoV-2 infection that are differentially associated with Covid-19 severity and mortality. As these distinct elevated cytokine profiles show up differently in different patients, this would imply the need for a personalized precision medicine approach to treat Covid-19. 

Apart from corticoid therapy, various treatments that were tested to reduce the COVID-19 associated cytokine storm seem to show disappointing results. The effectiveness of reducing mortality by blocking interleukins (for example, IL-6 and IL-1) has so far not been demonstrated. It has also been proposed that early-stage administration of type-I interferon therapy would slow SARS-CoV-2 replication, yet again with only limited reduction in mortality. It is possible that this apparent low effectiveness could be explained by the lack of stratification of patients to receive different treatments adapted to their individual cytokine profile.

© Guy Gorochov

To answer this question, Prof. Guy Gorochov’s team (CIMI Research Center, Sorbonne University / INSERM, Paris, France), in collaboration with Prof. Avidan Neumann’s bioinformatics group (Department of Environmental Medicine, University of Augsburg, Germany), studied the levels of a large number of cytokines in the blood of 115 COVID-19 patients at the day of hospitalization during the first wave of the pandemic. The results of this study were then confirmed by a second validation cohort comprising of 86 patients from the second wave of the SARS-CoV-2 pandemic in Paris¹.

Analysis of the results demonstrated that when looking at each cytokine separately, their blood levels showed great heterogeneity for each individual patient. “By looking at all cytokines together, using a non-supervised bioinformatics method called principle component analysis (PCA), we were able to reduce the large multi-dimensional variation into a two-dimensional perspective of cytokine combinations”, says Prof. Avidan Neumann. “Thus, we identified two distinct cytokine profiles that appear in different levels according to disease severity”.

Moderately severe patients, who initially do not have a severe respiratory illness, develop a response dominated by type-I interferons, in a context of high viral load, and relatively lower levels of pro-inflammatory cytokines. Conversely, patients with critical respiratory severity show elevated levels of pro-inflammatory cytokines (various levels of IL-6, IL-8, IL-10 and TNF-). Unexpectedly, SARS-CoV-2 antigen levels were lower in the critically severe patients, while the interferon anti-viral response is also less prominent in these patients. “These results go against the notion that high COVID-19 severity is always associated with excessive viral replication”, says Prof. Gorochov.

Nevertheless, having a strong type-I interferon response is not always good. An important observation was that the risk of death one month after hospital admission was related in each group to the intensity of the particular cytokine signature typical for that group. In particular, in the moderate severity group mortality was predicted by higher type-I interferon levels, while in the critical severity group mortality was associated with higher pro-inflammatory cytokine levels. Of note, mortality in the critical severity group was best predicted by higher levels of interlukin-10, rather than interlukin-6 or interlukin-1, thus possibly explaining the low effectiveness of therapy blocking the latter cytokines. Moreover, “our results suggest new therapeutic avenues”, says Prof. Gorochov, “as a higher risk of death in the most severe patients requiring ECMO is associated with lower levels of interleukin-17 and interleukin-18, cytokines that are associated with antibacterial response, treatment to increase their levels may improve patients’ survival”.

Overall these results suggest that COVID-19 severity and mortality are associated not with one cytokine storm, but rather with at least two distinct cytokine profiles.

Particularly not only an elevated pro-inflammatory response is dangerous but also, in some patients, an exacerbated anti-viral interferon response is associated with higher risk for mortality.

Furthermore, Prof. Neumann adds “generalization of these results to earlier timepoints, currently tested in our on-going Early-Opt project at the Uniklinikum Augsburg, will allow optimization of both public-health and clinical management of COVID-19”.

©AdobeStock

Drawing on epidemiological field studies and the FrenchCOVID hospital cohort coordinated by Inserm, teams from the Institut Pasteur, the CNRS and the Vaccine Research Institute (VRI, Inserm/University Paris-Est Créteil) studied the antibodies induced in individuals with asymptomatic or symptomatic SARS-CoV-2 infection. The scientists demonstrated that infection induces polyfunctional antibodies. Beyond neutralization, these antibodies can activate NK (natural killer) cells or the complement system, leading to the destruction of infected cells. Antibody levels are slightly lower in asymptomatic as opposed to symptomatic individuals, but polyfunctional antibodies were found in all individuals. These findings show that infection induces antibodies capable of killing infected cells regardless of the severity of the disease. The research was published in the journal Cell Reports Medicine on April 21^st, 2021.

Nearly half of those infected with SARS-CoV-2 do not develop symptoms. Yet, the immune response induced by asymptomatic forms of COVID-19 remains poorly characterized. The extent of the antiviral functions of SARS-CoV-2 antibodies is also poorly characterized. Antibodies are capable of both neutralizing the virus and activating “non-neutralizing” functions. The latter include antibody-dependent cellular cytotoxicity (ADCC) and complement activation, which are major components of the immune response and play a key role in the efficacy of some vaccines. ADCC is a two-stage process in which infected cells are first recognized by antibodies, then destroyed by NK cells. The complement system consists of a series of plasma proteins that also enable the elimination of cells targeted by antibodies. The ability of antibodies to activate these non-neutralizing functions has been little described for SARS-CoV-2 infection so far.

The teams from the Institut Pasteur, the CNRS and the VRI (Inserm/University Paris-Est Créteil) initially developed new assays to measure the various antibody functions. They produced assays to study cell death induced by NK cells or by complement in the presence of antibodies. By analyzing cultures in real time using video microscopy, the scientists showed that NK cells kill infected cells in the presence of antibodies, demonstrating new antiviral activity employed by SARS-CoV-2 antibodies.

The scientists then examined the serum of patients with symptomatic or asymptomatic forms of COVID-19 with their new assays. They also used methods previously developed at the Institut Pasteur, such as the S-Flow assay, to detect SARS-CoV-2 anti-spike antibodies, and the S-Fuse assay, to measure the neutralization capacity of these antibodies

“This study demonstrated that individuals infected with SARS-CoV-2 have antibodies that are capable of attacking the virus in different ways, by preventing it from entering cells (neutralization) or by activating NK cells to kill infected cells (via ADCC). We therefore use the term polyfunctional antibodies,” explains Timothée Bruel, co-last author of the study and a scientist in the Institut Pasteur’s Virus & Immunity Unit^[1] and at the VRI.

By comparing different groups of patients, the scientists then showed that asymptomatic individuals also have polyfunctional antibodies and that their response is slightly weaker than those of patients with moderate forms of COVID-19.

“The study reveals new mechanisms of action of SARS-CoV-2 antibodies and suggests that the protection induced by an asymptomatic infection is very close to that observed after a symptomatic infection,” concludes Olivier Schwartz, co-last author of the study, head of the Virus & Immunity Unit and at the VRI.

[1] Department of Virology (CNRS/Institut Pasteur)

SARS-CoV-2 infected cells (in green). The size scale corresponds to 10 µm. © Joe McKellar

Although the SARS-CoV-2 target cells in the respiratory tract produce antiviral molecules following infection, it is too late to prevent the virus from replicating. This is the conclusion drawn by researchers from Inserm, CNRS and Université de Montpellier at the Infectious Disease Research Institute of Montpellier. Their findings have been published in the Journal of Virology

Inserm researcher Caroline Goujon and her team have spent a long time studying viruses at the Infectious Disease Research Institute of Montpellier (CNRS/Université de Montpellier). When the COVID-19 epidemic emerged, Goujon and her colleague Olivier Moncorgé decided to focus on the novel coronavirus, initiating several projects – one of which fundamental, in an aim to understand how the target cells respond when infection strikes.

At a time when the scientific community still had questions about SARS-CoV-2, building knowledge on the early stages of infection to understand how the virus enters the body and how it can be blocked was essential.

In search of interferons

In their recent study, the scientists describe this response by the target cells in the respiratory epithelium. They began by exposing respiratory epithelial cells to the virus, analyzing its multiplication in the hours that followed. In parallel, they looked for the presence of interferons, which are antiviral molecules naturally produced by the cells in the event of infection.

What they found was a rapid increase in viral load after 48 hours and the high production of two types of interferons (type I and type III) 48 to 72 hours after infection. The production of these molecules is generally triggered by certain host cell proteins – known as sentinel proteins because their task is to detect the presence of viruses.

The researchers then used the CRISPR-Cas9 technique to delete the genes coding for the main sentinel proteins and found that the absence of one of the genes, MDA- 5, prevented the production of the interferons. However, this phenomenon had no impact on the replication of the virus. “With or without the production of these interferons, which are supposed to counteract the virus, replication took place in the same way in our epithelial cell model,” clarifies Goujon.

However, research by the team and many other groups shows that placing the target cells in contact with these same interferons in the hours preceding infection considerably reduces the ability of the virus to replicate, dividing the replication rate by at least ten.

“Therefore the antiviral activity of interferons is not to be called into question when it comes to SARS-CoV-2. Their inefficacy in our model is due to a problem of timing. Their release occurs too late to block viral replication,” she explains. In order to have a protective role and avoid viral replication, it appears important for their production to take place earlier.

Open up avenues of therapeutic research

This research also opens up new prospects when it comes to the severe forms of COVID. “We know from previous studies that natural interferon levels are low in patients with severe forms of COVID-19 compared to those with less severe forms. Stimulating the body’s production of interferons early on by activating the MDA-5 pathway could limit the risk of developing severe forms in some patients,” she adds.

Some research teams have already begun to study the early administration of interferons in a number of clinical trials. As for Goujon and her colleagues, they have already made a start on the next phase of the project: identify the genes in the target cells whose expression is stimulated by infection and which help to slow viral replication – thereby possibly opening up new therapeutic avenues.