Plasma Exchange in Covid-19 Patients With Anti-interferon Autoantibodies

As of 11/09/2020, 50,000,000 people have been infected with COVID-19 worldwide, and 1,200,000 people have died, mainly from acute respiratory distress syndrome (ARDS ). Only Dexamethasone has shown survival improvement in patients hospitalized with severe COVID-19 receiving oxygen or more invasive symptomatic treatment. Despite this therapeutic advance, invasive ventilation is necessary in 30% of hospitalized cases, and mortality remains high among ventilated patients (30-40%). This study suggests that it is necessary to continue searching for a treatment to reduce this mortality rate further while confirming that immunity modulation is a promising strategy. The severity of COVID-19 results from direct viral cytotoxicity, the accompanying inflammatory response associated with a state of hypercoagulability which contributes to lethal hypoxemic pneumonitis. During the SARS-CoV-2 replication phase, infected cells secrete chemokines and die by activating the immune system locally. A local inflammatory loop induces tissue destruction, which activates the immune system's circulating cells, leading to another amplifying loop called the cytokine storm. A high concentration of pro-inflammatory interleukins characterizes this cytokine storm. It induces an endothelial dysfunction that causes activation of the coagulation system and an increase in vascular permeability. These mechanisms lead to COVID-19 pneumopathy, and the pathologic examination reveals diffuse alveolar damage associated with a significant inflammatory infiltrate and microthrombi. These lesions cause pulmonary dysfunction and refractory hypoxia, which is the cause of mortality from COVID-19. In these phenomena, the integrity of the type 1 interferon pathway seems to play a major role and more particularly in COVID-19. Patients in whom the type I or III interferon pathway is dysfunctional are particularly susceptible to viral damage. It is now known that dysfunction of one of the interferon pathways exposes the host to a severe viral infection such as fulminant viral hepatitis or severe influenza pneumonia caused. In a study published in September in Science, Professor Jean-Laurent Casanova's team found in 10.2% (101/987) of patients with COVID-19 pneumonia neutralizing autoantibodies directed against IFN-ω (13 patients), one of 13 types of IFN-α (36), or both (52); In this study, the authors show that these autoantibodies neutralized the ability of IFN type I to block SARS-CoV-2 infection. When a patient presents one of these autoantibodies, he is exposed to an increased mortality risk compared to the healthy population. It is estimated at 40% in the affected population versus less than 10% in the rest. Plasma exchanges (PE) are a blood purification technique that eliminates auto-antibodies in the context of autoantibodies driven pathologies, particularly in intensive care such as autoimmune myasthenia gravis or Guillain Barré syndrome. This technique makes it possible to purify the plasma containing immunoglobulins, cytokines, chemokines, coagulation factors and replace it with plasma from healthy subjects or purified human albumin. The theoretical ability to remove some of the pro-inflammatory substances, toxins, and cellular components from the sick individual quickly identified plasma exchange as a potential therapy for COVID-19. The discovery of anti-interferon autoantibodies as a significant gravity factor leads us to hypothesize that PE would be even more beneficial in this subpopulation. To date, eight randomized clinical trials are in progress evaluating the interest of plasma exchanges in COVID-19 on clinicaltrials.gov. The inclusion criteria in these studies are broad. As plasma exchanges are an expensive therapy with limited availability, it makes their use in all patients with severe COVID-19 impossible. In this study, the investigators propose to demonstrate the efficacy of PE in the subpopulation of patients with anti-interferon autoantibodies and severe COVID-19 hospitalized in intensive care and on oxygen therapy, high flow or not, receiving invasive or non-invasive ventilation on survival to D28.