Pim1 kinase protects airway epithelial cells from cigarette smoke-induced damage and airway inflammation.

Exposure to cigarette smoke (CS) is the main risk factor for developing chronic obstructive pulmonary disease and can induce airway epithelial cell damage, innate immune responses, and airway inflammation. We hypothesized that cell survival factors might decrease the sensitivity of airway epithelial cells to CS-induced damage, thereby protecting the airways against inflammation upon CS exposure. Here, we tested whether Pim survival kinases could protect from CS-induced inflammation. We determined expression of Pim kinases in lung tissue, airway inflammation, and levels of keratinocyte-derived cytokine (KC) and several damage-associated molecular patterns in bronchoalveolar lavage in mice exposed to CS or air. Human bronchial epithelial BEAS-2B cells were treated with CS extract (CSE) in the presence or absence of Pim1 inhibitor and assessed for loss of mitochondrial membrane potential, induction of cell death, and release of heat shock protein 70 (HSP70). We observed increased expression of Pim1, but not of Pim2 and Pim3, in lung tissue after exposure to CS. Pim1-deficient mice displayed a strongly enhanced neutrophilic airway inflammation upon CS exposure compared with wild-type controls. Inhibition of Pim1 activity in BEAS-2B cells increased the loss of mitochondrial membrane potential and reduced cell viability upon CSE treatment, whereas release of HSP70 was enhanced. Interestingly, we observed release of S100A8 but not of double-strand DNA or HSP70 in Pim1-deficient mice compared with wild-type controls upon CS exposure. In conclusion, we show that expression of Pim1 protects against CS-induced cell death in vitro and neutrophilic airway inflammation in vivo. Our data suggest that the underlying mechanism involves CS-induced release of S100A8 and KC.

Cytotoxic T lymphocyte antigen 4-immunoglobulin G is a potent adjuvant for experimental allergen immunotherapy.

Allergen-specific immunotherapy (SIT) is the only treatment for allergic diseases that targets allergen-specific T helper type 2 (Th2) cells, which are the cause of the disease. There is an unmet requirement for adjuvants that increase the clinical efficacy of SIT allowing application of lower doses of the allergen, thereby reducing the risk of anaphylactic reactions. Cytotoxic T lymphocyte antigen 4-immunoglobulin (CTLA-4-Ig) has been shown to induce immunological tolerance in autoimmunity and allograft transplantation by blocking T cell co-stimulation and induction of the immunoregulatory enzyme indoleamine 2,3 dioxygenase (IDO). Previously, we showed that CTLA-4-Ig treatment at the time of allergen inhalation induced tolerance to subsequent allergen exposure in a mouse model of asthma. In this study, we test the hypothesis that CTLA-4-Ig acts as an adjuvant for experimental SIT. We evaluated the adjuvant effects of CTLA-4-Ig on SIT in a mouse model of ovalbumin-driven asthma. We used both wild-type and IDO-deficient mice to assess the role of IDO in the adjuvant effects of CTLA-4-Ig. Co-administration of CTLA-4-Ig strongly increased SIT-induced suppression of airway hyperreactivity (AHR), specific IgE in serum, airway eosinophilia and Th2 cytokine levels. Moreover, we found that CTLA-4-Ig, as an adjuvant for SIT, is equally effective in IDO-deficient and wild-type mice, demonstrating that the effect of CTLA-4-Ig is independent of IDO expression. We show that CTLA-4-Ig acts as a potent adjuvant to augment the therapeutic effects of SIT. As the adjuvant activity of CTLA-4-Ig is independent of IDO, we conclude that it acts by blocking CD28-mediated T cell co-stimulation.