Here, we employed single-cell RNA-Seq (scRNA-Seq) technology to map immune cell populations in bronchoalveolar lavage fluid (BALF) (19–21), elucidating the alveolar immune landscape and deciphering the intricate signaling pathways activated following infection, showing that the absence of Padi2 and Padi4 alters immune responses in sepsis. The gene discussed is PADI4; the disease is infection.