Figure 3.

Potential Role of the HPA Axis in the Immune Dysregulation of COVID-19

Cytokine and SARS-CoV-2 entry into the median eminence of the hypothalamus could lead to activation of the autonomic nervous system and release of adrenal catecholamines and steroids. In analogy with stroke, brain trauma, and myocardial infarction (Iadecola et al., 2020), these neurohumoral effectors could act on the bone marrow to release immunosuppressor neutrophils and myeloid cells (emergency myelopoiesis), as described in COVID-19 (Schulte-Schrepping et al., 2020), leading to immunosuppression and lymphopenia. In addition, release of calprotectin and cytokines from damaged lungs could also contribute to emergency myelopoiesis (Silvin et al., 2020).