COVID-19 in patients with Pulmonary Alveolar Proteinosis A European multicenter study

ABSTRACT

Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) signaling is essential in both alveolar macrophages (AMs) differentiation and activation of lung immune cells [1]. Differentiated AMs are crucial in both the elimination of alveolar microbes and surfactant clearance. The disruption of the GM-CSF axis in alveolar macrophages leads to the development of pulmonary alveolar proteinosis (PAP) [1]. In the majority of patients this relates to the presence of autoantibodies against GM-CSF autoimmune (a)PAP but there are multiple other causes [1, 2, 3]. GM-CSF deficient animals may have impaired lung inflammatory response to commensal microbes and humans with PAP may occasionally develop opportunistic lung infections [4]. The mainstay of pharmacological treatment in aPAP is inhaled GM-CSF which is off-label but increasingly used worldwide [5, 6, 7, 8, 9].