Glucocorticoid treatment of patients with SARS: implications for mechanisms of immunopathology

Transcriptomic characteristics of bronchoalveolar lavage fluid and peripheral blood mononuclear cells in COVID-19 patients

Circulating in China and 158 other countries and areas, the ongoing COVID-19 outbreak has caused devastating mortality and posed a great threat to public health. However, efforts to identify effectively supportive therapeutic drugs and treatments has been hampered by our limited understanding of host immune response for this fatal disease. To characterize the transcriptional signatures of host inflammatory response to SARS-CoV-2 (HCoV-19) infection, we carried out transcriptome sequencing of the RNAs isolated from the bronchoalveolar lavage fluid (BALF) and peripheral blood mononuclear cells (PBMC) specimens of COVID-19 patients. Our results reveal distinct host inflammatory cytokine profiles to SARS-CoV-2 infection in patients, and highlight the association between COVID-19 pathogenesis and excessive cytokine release such as CCL2/MCP-1, CXCL10/IP-10, CCL3/MIP-1A, and CCL4/MIP1B. Furthermore, SARS-CoV-2 induced activation of apoptosis and P53 signalling pathway in lymphocytes may be the cause of patients' lymphopenia. The transcriptome dataset of COVID-19 patients would be a valuable resource for clinical guidance on anti-inflammatory medication and understanding the molecular mechansims of host response.

What caused lymphopenia in SARS and how reliable is the lymphokine status in glucocorticoid-treated patients?

Severe Acute Respiratory Syndrome (SARS) outbreak in 2002–03 caused morbidity in over 8000 individuals and mortality in 744 in 29 countries. Lymphopenia along with neutrophilia was a feature of SARS, as it is in respiratory syncytial virus (RSV) and Ebola infections, to name a few. Direct infestation of lymphocytes, neutrophils and macrophages by SARS coronavirus (CoV) has been debated as a cause of lymphopenia, but there is no convincing data. Lymphopenia can be caused by glucocorticoids, and thus any debilitating condition has the potential to induce lymphopenia via stress mechanism involving the hypothalamic–pituitary–adrenal axis. Cortisol levels are elevated in patients with RSV and Ebola, and cortisol was higher in SARS patients with lymphopenia before any steroid therapy. Glucocorticoids also down-regulate the production of proinflammatory lymphokines. Because of the insidious presentation, SARS was treated with antibacterial, antiviral and supra-physiological doses of glucocorticoids. Treatment with glucocorticoids complicated the issue regarding lymphopenia, and certainly calls into question the status of lymphokines and their prognostic implications in SARS.