Due to the lack of inflammation elicited in the WT and Nrf2?/? mice instilled with PBS, we were unable to recover sufficient numbers of immune cells to perform flow cytometric analysis. compared with WT mice after NTHI challenge. Although the extent of NTHI-induced peribronchovascular inflammation did not significantly differ between the genotypes, plasma cell infiltration was significantly more abundant in Nrf2?/? mice. Most strikingly, Nrf2?/? mice generated significantly enhanced and persistent levels of serum antibodies against P6, a key outer membrane protein of NTHI. Lung dendritic cells from Nrf2?/? mice challenged with NTHI had increased activation markers compared with dendritic cells from similarly treated WT mice. Nrf2 regulates Lyn-IN-1 NTHI-induced airway inflammation characterized by lymphocytic and plasma cell infiltration and the activation of lung dendritic cells and B-cell responses in mice. Nrf2 may be a potential therapeutic target in limiting the bacterial Lyn-IN-1 infectionCinduced airway inflammation that drives exacerbations of chronic obstructive pulmonary disease. Keywords: Nrf2, nontypeable and raises the potential for Nrf2 as a therapeutic target in controlling the bacterial infectionCinduced bronchitis that characterizes COPD exacerbations. The lung is an interface where inhaled microbes and antigens interact with host defense cells. The inflammatory response must be calibrated to control inhaled microbes while avoiding excessive lung inflammation. Chronic obstructive pulmonary disease (COPD) is a spectrum of lung diseases that includes chronic bronchitis and emphysema. Infections by bacterial respiratory pathogens play a central role in the pathogenesis of COPD (1). Understanding mechanisms that regulate the development and persistence of chronic pulmonary inflammation Lyn-IN-1 and immune responses Lyn-IN-1 induced by respiratory pathogens may lead to better treatments for COPD. Morbidity and mortality among patients with COPD are related in large part to acute exacerbations, which Lyn-IN-1 on average occur one to three times per year. Exacerbations of COPD are associated with the acquisition of new strains of respiratory bacterial pathogens (2). Nontypeable (NTHI) is a major cause of acute sinopulmonary infections, with a particular propensity to cause exacerbations of COPD. NTHI strains are the most common pathogenic bacteria isolated from the airways of patients with COPD as colonizers and during episodes of exacerbation (3). Knowledge gained about how host innate and adaptive immune cells interact with these bacterial pathogens will be crucial to our understanding of COPD pathogenesis and also to developing novel therapeutics. Nuclear erythroid factor-2 (Nrf2) is a cap-n-collar basic leucine zipper transcription factor that protects against oxidant-induced injury. Nrf2 is induced by a number of stimuli, including reactive oxidants (4). Upon activation, Nrf2 detaches from Mobp its cytosolic inhibitor Keap1, translocates to the nucleus, and binds to the antioxidant response element in the promoter of target genes, leading to their transcriptional induction (5). In resting cells, Nrf2 resides in the cytosol bound to the inhibitor Keap1 (6). Typically, cullin3 directs the ubiquitination and subsequent proteasome-dependent degradation of Nrf2 (7C9). Oxidation or adduction of specific cysteine residues on the adapter protein Keap1 induces a conformational change that inhibits its ability to bind to cullin3, thereby abrogating Nrf2 ubiquitination and allowing accumulation of transcriptionally active Nrf2 in the nucleus (8, 10). Nrf2-deficient mice (Nrf2?/?) have increased inflammation and injury compared with wild-type (WT) mice in several experimental models (5), including LPS-induced shock (11), allergen-driven airway inflammation (12), and smoking-induced lung injury (13). The amplification of inflammatory processes in patients with COPD is recognized as a crucial feature of the disease. We asked whether Nrf2 would have a role in limiting lung inflammation induced by NTHI and in modulating innate and adaptive immunity. To elucidate the role of Nrf2 in modulating chronic lung inflammation, we evaluated airway and peribronchovascular inflammation induced by prolonged exposure to NTHI in WT and Nrf2?/? mice. We have established that chronic inflammation generated in lungs of mice with biweekly instillation of live NTHI replicates several aspects of histological lung inflammation observed.