Lymphocyte subset (CD4+, CD8+) counts reflect the severity of infection and predict the clinical outcomes in patients with COVID-19

Abstract

As discussed in the Journal recently 1 the SARS-CoV-2, a new -Coronavirus, uses the Angiotensin Converting Enzyme-2 Receptor to enter airway cells. Viral endocytosis is mediated by several factors, including clathrin, the adaptor protein-2 complex (AP2) and the adaptor-associated kinase-1 (AAK1). 2 According to a recent report, 3 COVID-19, the disease caused by SARS-CoV-2, is characterized by three clinical patterns: no symptoms, mild to moderate disease, severe pneumonia requiring admission to Intensive Care Unit (ICU) in up to 31% of the patients. 3 Thus far, there is no specific therapy for COVID-19 infection. No benefit of lopinavir-ritonavir treatment resulted in a recent trial. 4 Hydroxychloroquine, currently used in view of its "in vitro" observed effect of reduction of viral replication, seems unsatisfactory. 5 Elevated proinflammatory cytokine/chemokine responses seem associated with respiratory failure. 3 Recently, tocilizumab, an interleukin-6 inhibitor, was reported as effective in patients with severe COVID-19 pneumonia. 6 Baricitinib, another inhibitor of cytokine-release, seems an interesting anti-inflammatory drug. It is a Janus kinase inhibitor (anti-JAK) licensed for the treatment of rheumatoid arthritis (RA) with good efficacy and safety records. 7 Moreover it seems to have anti-viral effects by its affinity for AP2-associated protein AAK1, reducing SARS-CoV-2 endocytosis. 8 On this basis, we assessed the safety of baricitinib therapy combined with lopinavir-ritonavir in moderate COVID-19 pneumonia patients and we evaluated its clinical impact.