Hyaluronan Mediates Ozone-induced Airway Hyperresponsiveness in Mice
ABSTRACT Ozone is a common urban environmental air pollutant and significantly contributes to hospitalizations for respiratory illness. The mechanisms, which regulate ozone-induced bronchoconstriction, remain poorly understood. Hyaluronan was recently shown to play a central role in the response to noninfectious lung injury. Therefore, we hypothesized that hyaluronan contributes to airway hyperreactivity (AHR) after exposure to ambient ozone. Using an established model of ozone-induced airways disease, we characterized the role of hyaluronan in airway hyperresponsiveness. The role of hyaluronan in response to ozone was determined by using therapeutic blockade, genetically modified animals, and direct challenge to hyaluronan. Ozone-exposed mice demonstrate enhanced AHR associated with elevated hyaluronan levels in the lavage fluid. Mice deficient in either CD44 (the major receptor for hyaluronan) or inter-alpha-trypsin inhibitor (molecule that facilitates hyaluronan binding) show similar elevations in hyaluronan but are protected from ozone-induced AHR. Mice pretreated with hyaluronan-binding peptide are protected from the development of ozone-induced AHR. Overexpression of hyaluronan enhances the airway response to ozone. Intratracheal instillation of endotoxin-free low molecular weight hyaluronan induces AHR dependent on CD44, whereas instillation of high molecular weight hyaluronan protects against ozone-induced AHR. In conclusion, we demonstrate that hyaluronan mediates ozone-induced AHR, which is dependent on the fragment size and both CD44 and inter-alpha-trypsin inhibitor. These data support the conclusion that pulmonary matrix can contribute to the development of airway hyperresponsiveness.
- SourceAvailable from: David Kasahara
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- "Surprisingly, O 3 -induced increases in BAL TNFα were significantly reduced in obese versus lean mice (Figure 5C). O 3 induces fragmentation of the matrix glycoprotein, hyaluronan, leading to AHR (Garantziotis et al. 2009). Such hyal uronan fragments are thought to be induced via oxidative stress caused by O 3 . "
ABSTRACT: Background: Acute ozone (O3) exposure results in greater inflammation and airway hyperresponsiveness (AHR) in obese versus lean mice. Objectives: We examined the hypothesis that these augmented responses to O3 are the result of greater signaling through tumor necrosis factor receptor 2 (TNFR2) and/or interleukin (IL)-13. Methods: We exposed lean wild-type (WT) and TNFR2-deficient (TNFR2–/–) mice, and obese Cpefat and TNFR2-deficient Cpefat mice (Cpefat/TNFR2–/–), to O3 (2 ppm for 3 hr) either with or without treatment with anti–IL-13 or left them unexposed. Results: O3-induced increases in baseline pulmonary mechanics, airway responsiveness, and cellular inflammation were greater in Cpefat than in WT mice. In lean mice, TNFR2 deficiency ablated O3-induced AHR without affecting pulmonary inflammation; whereas in obese mice, TNFR2 deficiency augmented O3-induced AHR but reduced inflammatory cell recruitment. O3 increased pulmonary expression of IL-13 in Cpefat but not WT mice. Flow cytometry analysis of lung cells indicated greater IL-13–expressing CD4+ cells in Cpefat versus WT mice after O3 exposure. In Cpefat mice, anti–IL-13 treatment attenuated O3-induced increases in pulmonary mechanics and inflammatory cell recruitment, but did not affect AHR. These effects of anti–IL-13 treatment were not observed in Cpefat/TNFR2–/– mice. There was no effect of anti–IL-13 treatment in WT mice. Conclusions: Pulmonary responses to O3 are not just greater, but qualitatively different, in obese versus lean mice. In particular, in obese mice, O3 induces IL-13 and IL-13 synergizes with TNF via TNFR2 to exacerbate O3-induced changes in pulmonary mechanics and inflammatory cell recruitment but not AHR.Environmental Health Perspectives 02/2013; 121(5). DOI:10.1289/ehp.1205880 · 7.03 Impact Factor
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- "Development of ozone-induced AHR requires several components of the inflammasome complex including; ASC, caspase1, and Nlrp3. Ozone inhalation results in increased level of soluble hyaluronan, which we have previously reported to contribute to AHR (Garantziotis et al. 2009). We now report that hyaluronan-induced cleavage of alveolar macrophage-derived pro-IL-1β is dependent on the Nlrp3-inflammasome. "
ABSTRACT: Background: The role of the Nlrp3 inflammasome in nonallergic airway hyperresponsiveness (AHR) has not previously been reported. Recent evidence supports both interleukin (IL) 1β and short fragments of hyaluronan (HA) as contributors to the biological response to inhaled ozone. Objective: Because extracellular secretion of IL-1β requires activation of the inflammasome, we investigated the role of the inflammasome proteins ASC, caspase1, and Nlrp3 in the biological response to ozone and HA. Methods: C57BL/6J wild-type mice and mice deficient in ASC, caspase1, or Nlrp3 were exposed to ozone (1 ppm for 3 hr) or HA followed by analysis of airway resistance, cellular inflammation, and total protein and cytokines in bronchoalveolar lavage fluid (BALF). Transcription levels of IL-1β and IL-18 were determined in two populations of lung macrophages. In addition, we examined levels of cleaved caspase1 and cleaved IL-1β as markers of inflammasome activation in isolated alveolar macrophages harvested from BALF from HA-treated mice. Results: We observed that genes of the Nlrp3 inflammasome were required for development of AHR following exposure to either ozone or HA fragments. These genes are partially required for the cellular inflammatory response to ozone. The expression of IL-1β mRNA in alveolar macrophages was up-regulated after either ozone or HA challenge and was not dependent on the Nlrp3 inflammasome. However, soluble levels of IL-1β protein were dependent on the inflammasome after challenge with either ozone or HA. HA challenge resulted in cleavage of macrophage-derived caspase1 and IL-1β, suggesting a role for alveolar macrophages in Nlrp3-dependent AHR. Conclusions: The Nlrp3 inflammasome is required for the development of ozone-induced reactive airways disease.Environmental Health Perspectives 09/2012; 120(12). DOI:10.1289/ehp.1205188 · 7.03 Impact Factor
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- "We previously observed that direct instillation of hyaluronan fragments into the lung can induce AHR in a manner independent of cellu lar inflammation (Garantziotis et al. 2009). Therefore, we considered that because mindin binding to LPS can be blocked by simple sugars (He et al. 2004), mindin could be required for biological response to hyaluronan fragments, which contribute to Tlr4-dependent response to ozone (Garantziotis et al. 2009, 2010). However, we determined that the in vivo AHR response to hyaluronan fragments in the airspace is independent of mindin [see Supplemental Material, Figure 2 "
ABSTRACT: Our previous work demonstrated that the extracellular matrix protein mindin contributes to allergic airways disease. However, the role of mindin in nonallergic airways disease has not previously been explored. We hypothesized that mindin would contribute to airways disease after inhalation of either lipopolysaccharide (LPS) or ozone. We exposed C57BL/6J and mindin-deficient (-/-) mice to aerosolized LPS (0.9 μg/m3 for 2.5 hr), saline, ozone (1 ppm for 3 hr), or filtered air (FA). All mice were evaluated 4 hr after LPS/saline exposure or 24 hr after ozone/FA exposure. We characterized the physiological and biological responses by analysis of airway hyperresponsiveness (AHR) with a computer-controlled small-animal ventilator (FlexiVent), inflammatory cellular recruitment, total protein in bronchoalveolar lavage fluid (BALF), proinflammatory cytokine profiling, and ex vivo bronchial ring studies. After inhalation of LPS, mindin-/- mice demonstrated significantly reduced total cell and neutrophil recruitment into the airspace compared with their wild-type counterparts. Mindin-/- mice also exhibited reduced proinflammatory cytokine production and lower AHR to methacholine challenge by FlexiVent. After inhalation of ozone, mice had no detectible differences in cellular inflammation or total BALF protein dependent on mindin. However, mindin-/- mice were protected from increased proinflammatory cytokine production and AHR compared with their C57BL/6J counterparts. After ozone exposure, bronchial rings derived from mindin-/- mice demonstrated reduced constriction in response to carbachol. These data demonstrate that the extracellular matrix protein mindin modifies the airway response to both LPS and ozone. Our data support a conserved role of mindin in production of proinflammatory cytokines and the development of AHR in two divergent models of reactive airways disease, as well as a role of mindin in airway smooth muscle contractility after exposure to ozone.Environmental Health Perspectives 06/2011; 119(10):1403-8. DOI:10.1289/ehp.1003339 · 7.03 Impact Factor