Nesbitt, Lisa

The studies demonstrate the differential effects of the nicotinic acetylcholine receptors (nAChRs) regulating airway hyperreactivity (AHR) and remodeling in a mixed allergen model of asthma. We compared wild-type (WT) versus global α7nAChR knockout (Glα7KO) versus smooth muscle-specific α7nAChR KO (smα7KO) mice. We found that smα7KO improved lung function and AHR in mice challenged with MA and in the presence of nicotine, whereas MA-challenged Glα7KO in the presence of nicotine showed worsened AHR.

The pathogenesis of asthma in elderly is not well understood. Using a mouse model of asthma, we show that aging results in decreased lung function and less responsiveness to allergen exposure, impacted by locally produced brain-derived neurotrophic factor. Aging also decreases allergen-induced inflammation but increases airway remodeling and senescence. Our results suggest that senescence pathways may contribute to asthma pathogenesis in elderly.

AbstractSupplemental O2 (hyperoxia) is a critical intervention for premature infants (<34 weeks) but consequently is associated with development of bronchial airway hyperreactivity (AHR) and asthma. Clinical practice shifted toward the use of moderate hyperoxia (<60% O2), but risk for subsequent airway disease remains. In mouse models of moderate hyperoxia, neonatal mice have increased AHR with effects on airway smooth muscle (ASM), a cell type involved in airway tone, bronchodilation, and remodeling. Understanding mechanisms by which moderate O2 during the perinatal period initiates sustained airway changes is critical to drive therapeutic advancements toward treating airway diseases. We propose that cellular clock factor BMAL1 is functionally important in developing mouse airways. In adult mice, cellular clocks target pathways highly relevant to asthma pathophysiology and Bmal1 deletion increases inflammatory response, worsens lung function, and impacts survival outcomes. Our understanding of BMAL1 in the developing lung is limited, but our previous findings show functional relevance of clocks in human fetal ASM exposed to O2. Here, we characterize Bmal1 in our established mouse neonatal hyperoxia model. Our data show that Bmal1 KO deleteriously impacts the developing lung in the context of O2 and these data highlight the importance of neonatal sex in understanding airway disease.

Local production of growth factors within the airway with autocrine/paracrine effects can promote features of asthma. Here, we show that glial-derived neurotrophic factor (GDNF) is a procontractile and proremodeling factor that contributes to allergen-induced airway hyperreactivity and tissue remodeling in a mouse model of asthma. Blocking GDNF signaling attenuates allergen-induced airway hyperreactivity and remodeling, suggesting a novel approach to alleviating structural and functional changes in the asthmatic airway.

Chronic airway disease is a short- and long-term consequence of premature birth. Understanding effects of O2 exposure during the perinatal period is key to identify targetable mechanisms that initiate and sustain adverse airway changes. Our findings show a beneficial effect of exogenous H2S on developing mouse airway structure and function with notable sex differences. H2S donors alleviate effects of O2 on airway hyperreactivity, contractility, airway smooth muscle thickness, and extracellular matrix deposition.

Background: Atherosclerosis is an inflammatory disease with T cells and macrophages as the leading plaque cell populations. The immunoproteasome (IP) influences T cell survival and differentiation but its impact on macrophage survival and differentiation remains unknown, which was the objective of this study. Methods: Murine monocyte/macrophage Raw264.7 cells were stimulated by IFN-gamma (20 ng/mL) plus LPS (10pg/mL) or IL-4 (20 ng/mL) for 18 hours to induce M1 and M2 macrophages, and these differentiated macrophages were then re-exposed to IFN- gamma and IL-4 for another 24 hours, without and with IP subunit beta 5i inhibition by siRNA or Onx0914. Nitric oxide synthase and arginase activity served as differentiation markers (analyzed by enzymatic assays) as did the cytokine/chemokine profile (analyzed by antibody arrays). Cell viability was tested by an XTT assay and apoptosis by TUNEL FACS. Results: IP beta5i knockout/inhibition did not influence M1 and M2 macrophage differentiation. Also, no significant differences in apoptosis were observed between RAW264.7 cells treated with and without beta 5i inhibitor during macrophage differentiation. With re-exposure to IFN- gamma and IL-4, however, there was more apoptosis and less survival of differentiated M1 macrophages with beta5i inhibition. Conversely, beta 5i inhibition achieved less apoptosis and more survival of differentiated M2 macrophages when switching IL-4- to IFN-gamma-stimulating conditions. Conclusions: IP inhibition does not influence macrophage differentiation but survival of differentiated macrophages of potential significance for the atherosclerotic disease process.