Cytosolic Proliferating Cell Nuclear Antigen (PCNA) interacts with S100A8 and controls an inflammatory subset of neutrophils in COVID-19

Neutrophils are key players in the hyperinflammatory response upon SARS-CoV-2 infection. We have previously described that cytosolic proliferating cell nuclear antigen (PCNA) controls neutrophil survival and NADPH oxidase-dependent ROS production. We here show that both PCNA and S100A8 expression and interaction were elevated in neutrophils from patients with COVID-19 compared to healthy donors and this was correlated with disease severity. Increased PCNA expression was accompanied by a decreased apoptosis and increased NADPH-oxidase activity in neutrophils from COVID-19 patients compared to healthy donors. These effects, as well as the interaction between PCNA and S100A8, were potently counteracted by T2 amino alcohol (T2AA), a PCNA inhibitor, demonstrating that the PCNA scaffold orchestrated neutrophil activation. Notably, the interaction between PCNA-S100A8 was more intense in the CD16high-CD62Llow activated neutrophil subset. We propose that PCNA-S100A8 complex acts as potential driver for neutrophil dysregulation in COVID-19 and show for the first time that the PCNA scaffold is a decisive component of both neutrophil activation and heterogeneity.

Effectiveness of endurance training rehabilitation after hospitalisation in intensive care for COVID-19-related acute respiratory distress syndrome on dyspnoea (RECOVER): a randomised controlled, open-label multicentre trial

BackgroundCOVID-19-related Acute Respiratory Distress Syndrome (CARDS) is the severe evolution of the Sars-Cov-2 infection leading to an intensive care unit (ICU) stay. Its onset is associated with "long-covid" including persisting respiratory disorders up to one year. Rehabilitation is suggested by most guidelines in the treatment of "long-covid". As no randomised controlled trial did support its use in "long-covid" we aimed to evaluate the effects of endurance training rehabilitation (ETR) on dyspnoea in "long-covid" following CARDS. MethodsIn this multicentre, two-arm, parallel, open, assessor-blinded, randomised, controlled trial performed in three French ICU, we enrolled adults previously admitted for CARDS, discharged for at least three months and presenting an mMRC dyspnea scale score > 1. Eligible patients were randomly allocated (1:1) to receive either ETR or standard physiotherapy (SP), both for three months. Outcomes assessors were masked to treatment assignment. Primary outcome was dyspnoeas evolution, measured by Multidimensional Dyspnea Profile (MDP) at inclusion and after 90 days. ResultsBetween August 7, 2020 and January 26, 2022, 871 COVID-19 patients were screened, of whom 60 were randomly assigned to ETR (n=27) or SP (n=33). Mean MDP score after treatment was significantly lower in the ETR group than in the SP group (26.15 [SD 15.48] vs. 44.76 [SD 19.25]; mean difference -18.61 [95% CI -27.78 to -9.44]; p<0.0001). ConclusionCARDS patients suffering from breathlessness three months after discharge improved their dyspnoea significantly more when treated with ETR for three months rather than with SP.

Outcome of SARS-CoV-2 infection linked to MAIT cell activation and cytotoxicity: evidence for an IL-18 dependent mechanism

Immune system dysfunction is paramount in Coronavirus disease 2019 (COVID-19) severity and fatality rate. Mucosal-Associated Invariant T (MAIT) cells are innate-like T cells involved in mucosal immunity and protection against viral infections. Here, we studied the immune cell landscape, with emphasis on MAIT cells, in a cohort of 182 patients including patients at various stages of disease activity. A profound decrease of MAIT cell counts in blood of critically ill patients was observed. These cells showed a strongly activated and cytotoxic phenotype that positively correlated with circulating pro-inflammatory cytokines, notably IL-18. MAIT cell alterations markedly correlated with disease severity and patient mortality. SARS-CoV-2-infected macrophages activated MAIT cells in a cytokine-dependent manner involving an IFN-dependent early phase and an IL-18-induced later phase. Therefore, altered MAIT cell phenotypes represent valuable biomarkers of disease severity and their therapeutic manipulation might prevent the inflammatory phase involved in COVID-19 aggravation.

Single cell RNA sequencing of blood antigen-presenting cells in severe Covid-19 reveals multi-process defects in antiviral immunity

COVID-19 can lead to life-threatening acute respiratory failure, characterized by simultaneous increase in inflammatory mediators and viral load. The underlying cellular and molecular mechanisms remain unclear. We performed single-cell RNA-sequencing to establish an exhaustive high-resolution map of blood antigen-presenting cells (APC) in 7 COVID-19 patients with moderate or severe pneumonia, at day-1 and day-4 post-admission, and two healthy donors. We generated a unique dataset of 31,513 high quality APC, including monocytes and rare dendritic cell (DC) subsets. We uncovered multiprocess and previously unrecognized defects in anti-viral immune defense in specific APC compartments from severe patients: i) increase of pro-apoptotic genes exclusively in pDC, which are key effectors of antiviral immunity, ii) sharp decrease of innate sensing receptors, TLR7 and DHX9, in pDC and cDC1, respectively, iii) down-regulation of antiviral effector molecules, including Interferon stimulated genes (ISG) in all monocyte subsets, and iv) decrease of MHC class II-related genes, and MHC class II transactivator (CIITA) activity in cDC2, suggesting a viral inhibition of antigen presentation. These novel mechanisms may explain patient aggravation and suggest strategies to restore defective immune defense.

Impaired type I interferon activity and exacerbated inflammatory responses in severe Covid-19 patients

BackgroundCoronavirus disease 2019 (Covid-19) is a major global threat that has already caused more than 100,000 deaths worldwide. It is characterized by distinct patterns of disease progression implying a diverse host immune response. However, the immunological features and molecular mechanisms involved in Covid-19 severity remain so far poorly known. MethodsWe performed an integrated immune analysis that included in-depth phenotypical profiling of immune cells, whole-blood transcriptomic and cytokine quantification on a cohort of fifty Covid19 patients with a spectrum of disease severity. All patient were tested 8 to 12 days following first symptoms and in absence of anti-inflammatory therapy. ResultsA unique phenotype in severe and critically ill patients was identified. It consists in a profoundly impaired interferon (IFN) type I response characterized by a low interferon production and activity, with consequent downregulation of interferon-stimulated genes. This was associated with a persistent blood virus load and an exacerbated inflammatory response that was partially driven by the transcriptional factor NFB. It was also characterized by increased tumor necrosis factor (TNF)- and interleukin (IL)-6 production and signaling as well as increased innate immune chemokines. ConclusionWe propose that type-I IFN deficiency in the blood is a hallmark of severe Covid-19 and could identify and define a high-risk population. Our study provides a rationale for testing IFN administration combined with adapted anti-inflammatory therapy targeting IL-6 or TNF- in most severe patients. These data also raise concern for utilization of drugs that interfere with the IFN pathway.