Lefrancais et al. (2018) showed that inhibiting NET formation could reduce lung injury and improve mice survival. Lung specimens were collected, and immunofluorescence studies were performed to determine whether peripheral 5-HT deficiency affected NET formation. Results showed that lung tissues from sham mice had no NET formation. However, lung tissues from WT CLP mice had significantly enhanced NET formation, as indicated by the staining of CitH3. Interestingly, we observed that in the lung tissues of Tph1−/− CLP mice, NET formation was significantly reduced (Figure 2). This evidence concerns the gene TPH1 and hyperinsulinemic hypoglycemia, familial, 4.