SRA

The leukocyte NADPH oxidase 2 (NOX2) plays a key role in pathogen killing and immunoregulation. Genetic defects in NOX2 result in chronic granulomatous disease (CGD), associated with microbial infections and inflammatory disorders, often involving the lung. Alveolar macrophages (AM) are the predominant immune cell in the airways at steady state, and limiting their activation is important given constant exposure to inhaled materials, yet the importance of NOX2 in this process is not well-understood. Here, we show a previously undescribed role for NOX2 in maintaining lung homeostasis by suppressing AM activation, as studied using CGD mice or mice with selective loss of NOX2 primarily in macrophages. AM lacking NOX2 have increased cytokine responses to TLR2 and TLR4 stimulation ex vivo. Moreover, between 4 and 12 weeks of age, mice with global NOX2 deletion developed an activated CD11bhigh subset of AM with epigenetic and transcriptional profiles reflecting immune activation compared to WT AM. The presence of CD11bhigh AM in CGD mice correlated with increased numbers of alveolar neutrophils and proinflammatory cytokines at steady state as well as increased lung inflammation following insults. Moreover, deletion of NOX2 primarily in macrophages was sufficient for mice to develop an activated CD11bhigh AM subset and accompanying pro-inflammatory sequela. Additionally, we showed that the altered resident macrophage transcriptional profile in the absence of NOX2 is tissue-specific as these changes were not seen in resident peritoneal macrophages. Thus, these data demonstrate that absence of NOX2 in alveolar macrophages leads to their pro-inflammatory remodeling and dysregulates alveolar homeostasis. Overall design: BAL alveolar macrophages were studied from 4 week and 12 week old control and CybbKO mice. For each replicate, BAL AM from various groups of mice were sorted into RPMI+20%FBS on the basis of CD45+Ly6G-SiglecF+CD11c+ markers and CD11b expression (CD11b+or CD11b). To achieve a sufficient number of AM cells (~50,000) per each replicate sample, 2 to 3 mice from same group were pooled. Cells were centrifuged followed by resuspension in RLT-plus RNA Lysis buffer (Qiagen). RNA isolation was done using RNAeasy micro-plus columns (Qiagen). 3 independent replicates from each group were analyzed. RNA seq libraries were generated with Clontech SMARTer kits and sequencing were performed on a HiSeq3000 sequencer.