Diurnal regulation of the lung transcriptome by neutrophils. (A) Experimental scheme for neutrophil depletion and collection of lungs at different diurnal times for RNA sequencing; n = 7 replicates per condition and time from two experiments. (B) Distribution of pulmonary transcripts: total genes (green; 100%) and genes that display diurnal changes in transcription (purple; 9.2%), a fraction of which loses diurnal oscillations when neutrophils are depleted (orange; representing 26.7% of diurnally oscillating or 2.5% of total transcripts). (C) Heat map of diurnally expressed genes that lose their diurnal variation in neutrophil-depleted lungs, with several representative genes indicated at right. Only genes with an adjusted P value <0.05 in a moderated t test in the non-depleted group were included; n = 7 mice per group. (D) Major biological functions affected by the neutrophil-regulated diurnal genes shown in C. The functions were identified from the pathways indicated by numbers (1–21) and listed in Fig. S5 C and Table S1. The total number of unique genes in the list was calculated for each biological function, and the color scale reflects the proportion of the genes in each pathway that contribute to the specific function.