Blimp-1 protects the transcriptional identity of group 2 innate lymphocytes in lung inflammation [RNA-seq]
Type 2 inflammation in the lung underlies allergic asthma and promotes tumor metastasis. Type 2 innate lymphoid cells (ILC2s) respond to tissue damage signals including IL-33 and IL-25 and are implicated in type 2 inflammatory diseases of the lung, but the factors that maintain ILC2s ability to produce type 2 cytokines are not known. We show Blimp-1 is a key transcriptional repressor of type 1 genes induced by the type 2 cytokine IL-9 in ILC2s in response to tissue damage signals. Loss of Blimp-1 in ILC2s altered inflammation in response to allergens, but also limited metastatic melanoma in the lung by limiting type 2 cytokines in favor of type I cytokines including IFNg and TNF. Thus, Blimp-1 protects the type 2 identity of ILC2s during lung inflammatory diseases. Overall design: For bulk RNA sequencing evaluating Blimp-1 deficiency (including library WT_1, WT_2, WT_3, KO_1, KO_2 and KO_3), 3 female Blimp-1IL7RaCre and 3 female ControlIL7RaCre mice match with age were used. Whole lung was harvested and ILC2s were sorted from these individual mice by the following markers: live, lineage-, CD90.2+, CD3-. After sorting, ~15,000 ILC2s cells from each sample were cultured in complete RPMI in 96-well plate with 20ng/mL IL-33 and 20ng/mL IL-25 for 72 hours. After 72 hours, ILC2s were collected and RNA was isolated with RNeasy Plus Micro Kit (74034, Qiagen). RNA quality was assessed by RIN score and passed down to library preparation.  For bulk RNA sequencing comparing unstimulated ILC2s ex vivo from lung with stimulated ILC2s (including library 1_unstim, 2_unstim, 3_unstim, 4_unstim, 1_stim, 2_stim, 3_stim and 4_stim), 8 female B6 mice were separated into two groups. Whole lung was harvested and ILC2s were sorted from these individual mice lung by the following markers: live, lineage-, CD90.2+, CD3-. After sorting, ~15,000 ILC2s cells from each sample were cultured in complete RPMI in 96-well plate with or without IL-33 (20ng/mL) according to their group for 24 hours. After 24 hours, ILC2s were collected and RNA was isolated with RNeasy Plus Micro Kit (74034, Qiagen). RNA quality was assessed by RIN score and passed down to library preparation.