Researchers from Beijing, China examined previous literature on immune changes in patients with severe acute respiratory syndrome coronavirus (SARS-CoV) infection, Middle East respiratory syndrome-related coronavirus, and influenza to identify common disease characteristics and outcomes and to identify a hypothetical pathogenesis for COVID-19 (SARS-CoV-2) infection. Histopathologic examinations have shown that characteristics shared by the examined diseases include diffuse alveolar damage, edematous lung lesions, and pneumonia.
The published literature and data from patients with COVID-19 were also used to develop proposed hypotheses about the infection’s pathogenesis as well as recommended treatments for severe disease. The most common hypothesis involves disease transmission from droplets or close physical contact, where the virus then enters through the mucous membranes and into the lungs. The virus could attack organs that express angiotensin-converting enzyme 2, which includes the heart, lungs, and gastrointestinal tract, after it enters the peripheral blood.
Although there is currently no available antiviral for COVID-19, the investigators suggest IV immunoglobulin and LMWH anticoagulant therapy should be initiated early on the basis of specific trends in T cells, B cells, inflammatory cytokines, and D-Dimer. These trends include significantly lower T lymphocytes and B lymphocytes in peripheral blood, significant increases in interleukin 6 and other inflammatory cytokines, abnormal increases in coagulation parameters (eg, D-Dimer), and lung lesion expansion based on chest computed tomography.
High-dose IV immunoglobulin 0.3-0.5 g/kg/d is recommended for 5 days, as it may disrupt the inflammatory storm in the infection’s early stage and subsequently enhance immune function. The investigators also wrote that that the recommended subcutaneous LMWH dose is 100 U/kg/12 h for ≥3 to 5 days.
“Clinicians should closely monitor the indicators of laboratory examination of patients to be alert for side effects after anticoagulant treatment,” the researchers added.
Lin L, Lu L, Cao W, Li T. Hypothesis for potential pathogenesis of SARS-CoV-2 infection-a review of immune changes in patients with viral pneumonia. Emerg Microbes Infect. 2020;9(1):727-732.