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.
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- "Mice deficient in these genes show reduced response to challenge with ozone or hyaluronan (Li et al. 2011). Garantziotis et al. (2009; 2010) reported that ozone-induced airway hyperresponsivess is partly mediated by extracellular matrix hyaluronan and the TLR4 through increased production of pro-inflammatory cytokines and modifying the biological responses to hyaluronan. Bauer et al. (2011) examined the effector molecules downstream of the TLR4 complex and delineated heat-shock protein Hsp70 contributes to ozone-induced inflammation in the lungs. "
ABSTRACT: Emissions of laser printers and photocopiers (LP&P) may be associated with health problems. The aim of this review is to describe the clinical picture that is triggered by exposure to LP&P and the molecular mechanisms underpinning the symptoms. Exposure to LP&P to vulnerable subjects may cause a symptom complex consisting of 1) irritation and hyperresponsiveness of the upper and lower respiratory tract; and 2) chronic fatigue (syndrome, CFS). Symptoms occur within hours after L&P exposure and may last for some days or become chronic with exacerbations following LP&P exposure. Substances that can be found in toners or are generated during the printing process are Silica nanoparticles, Titanium Dioxide nanoparticles, Carbon Black, metals, ozone, volatile organic compounds (VOC), etc. The latter may generate oxidative and nitrosative stress (O&NS), damage-associated molecular patterns molecules, pulmonary and systemic inflammation, and modulate Toll Like Receptor 4 (TRL4)‑related mechanisms. It is concluded that LP&P emissions may cause activation of the TLR4 Radical Cycle and thus be associated with the onset of chronic inflammatory and O&NS illnesses, such as CFS, in some vulnerable individuals. Cinnamon, an antagonist of the TLR4 complex, and Hydrogen, a potent antiinflammatory and oxygen radical scavenger, may have efficacy treating LP&P-induced illness.Neuro endocrinology letters 12/2013; 34(8):723-37. · 0.80 Impact Factor
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- "Mice lacking CD44, a major receptor for HA, have impaired clearance of HA fragments, and increased bleomcyin injury . HA fragments instilled into the lung increases airway hyper-responsiveness in a CD44-dependent manner . HA fragments have been shown to mediate airway hyper-responsiveness seen with ozone exposure through both CD44 and TLR4 . "
ABSTRACT: Background The extracellular matrix plays a critical role in insuring tissue integrity and water homeostasis. However, breakdown products of the extracellular matrix have emerged as endogenous danger signals, designed to rapidly activate the immune system against a potential pathogen breach. Type I interferons play a critical role in the immune response against viral infections. In the lungs, hylauronan (HA) exists as a high molecular weight, biologically inert extracellular matrix component that is critical for maintaining lung function. When lung tissue is injured, HA is broken down into lower molecular weight fragments that alert the immune system to the breach in tissue integrity by activating innate immune responses. HA fragments are known to induce inflammatory gene expression via TLR-MyD88-dependent pathways. Methods Primary peritoneal macrophages from C57BL/6 wild type, TLR4 null, TLR3 null, MyD88 null, and TRIF null mice as well as alveolar and peritoneal macrophage cell lines were stimulated with HA fragments and cytokine production was assessed by rt-PCR and ELISA. Western blot analysis for IRF3 was preformed on cell lysates from macrophages stimulate with HA fragments Results We demonstrate for the first time that IFNβ is induced in murine macrophages by HA fragments. We also show that HA fragments induce IFNβ using a novel pathway independent of MyD88 but dependent on TLR4 via TRIF and IRF-3. Conclusions Overall our findings reveal a novel signaling pathway by which hyaluronan can modulate inflammation and demonstrate the ability of hyaluronan fragments to induce the expression of type I interferons in response to tissue injury even in the absence of viral infection. This is independent of the pathway of the TLR2-MyD88 used by these matrix fragments to induce inflammatory chemokines. Thus, LMW HA may be modifying the inflammatory milieu simultaneously via several pathways.Journal of Inflammation 05/2013; 10(1):23. DOI:10.1186/1476-9255-10-23 · 2.02 Impact Factor
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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 · 7.98 Impact Factor