Gabriele Grunig

Interleukin-10 is a central regulator of the response to LPS in murine models of endotoxic shock and the Shwartzman reaction but not endotoxin tolerance.

Previous studies in vivo have shown that IL-10 infusion can prevent lethal endotoxic shock. Mice deficient in the production of IL-10 (IL10T) were used to investigate the regulatory role of IL-10 in the responses to LPS in three experimental systems. In a model of acute endotoxic shock, it was found that the lethal dose of LPS for IL10T mice was 20-fold lower than that for wild type (wt) mice suggesting that endogenous IL-10 determines the amount of LPS which can be tolerated without death. The high mortality rate of IL10T mice challenged with modest doses of LPS was correlated to the uncontrolled production of TNF as treatment with anti-TNF antibody (Ab) resulted in 70% survival. Additional studies suggested that IL-10 mediates protection by controlling the early effectors of endotoxic shock (e.g., TNF alpha) and that it is incapable of directly antagonizing the production and/or actions of late appearing effector molecules (e.g., nitric oxide). We also found that IL10T mice were extremely vulnerable to a generalized Shwartzman reaction where prior exposure to a small amount of LPS primes the host for a lethal response to a subsequent sublethal dose. The priming LPS dose for IL10T mice was 100-fold lower than that required to prime wt mice implying that IL-10 is important for suppressing sensitization. In agreement with this assumption, IL-10 infusion was found to block the sensitization step. Interestingly, IL-10 was not the main effector of endotoxin tolerance as IL10T mice could be tolerized to LPS. Furthermore, IL-10 infusion could not substitute for the desensitizing dose of LPS. These results show that IL-10 is a critical component of the hosts natural defense against the development of pathologic responses to LPS although it is not responsible for LPS-induced tolerance.

Blimp-1 attenuates Th1 differentiation by repression of ifng, tbx21, and bcl6 gene expression.

T cell-specific deletion of Blimp-1 causes abnormal T cell homeostasis and function, leading to spontaneous, fatal colitis in mice. Herein we explore the role of Blimp-1 in Th1/Th2 differentiation. Blimp-1 mRNA and protein are more highly expressed in Th2 cells compared with Th1 cells, and Blimp-1 attenuates IFN-γ production in CD4 cells activated under nonpolarizing conditions. Although Blimp-1-deficient T cells differentiate normally to Th2 cytokines in vitro, Blimp-1 is required in vivo for normal Th2 humoral responses to NP-KLH (4-hydroxy-3-nitrophenylacetyl/keyhole lymphocyte hemocyanin) immunization. Lack of Blimp-1 in CD4 T cells causes increased IFN-γ, T-bet, and Bcl-6 mRNA. By chromatin immunoprecipitation we show that Blimp-1 binds directly to a distal regulatory region in the ifng gene and at multiple sites in tbx21 and bcl6 genes. Our data provide evidence that Blimp-1 functions in Th2 cells to reinforce Th2 differentiation by repressing critical Th1 genes.

MicroRNA-375 Regulation of Thymic Stromal Lymphopoietin by Diesel Exhaust Particles and Ambient Particulate Matter in Human Bronchial Epithelial Cells

Air pollution contributes to acute exacerbations of asthma and the development of asthma in children and adults. Airway epithelial cells interface innate and adaptive immune responses, and have been proposed to regulate much of the response to pollutants. Thymic stromal lymphopoietin (TSLP) is a pivotal cytokine linking innate and Th2 adaptive immune disorders, and is upregulated by environmental pollutants, including ambient particulate matter (PM) and diesel exhaust particles (DEP). We show that DEP and ambient fine PM upregulate TSLP mRNA and human microRNA (hsa-miR)-375 in primary human bronchial epithelial cells (pHBEC). Moreover, transfection of pHBEC with anti–hsa-miR-375 reduced TSLP mRNA in DEP but not TNF-α–treated cells. In silico pathway evaluation suggested the aryl hydrocarbon receptor (AhR) as one possible target of miR-375. DEP and ambient fine PM (3 μg/cm2) downregulated AhR mRNA. Transfection of mimic-hsa-miR-375 resulted in a small downregulation of AhR mRNA compared with resting AhR mRNA. AhR mRNA was increased in pHBEC treated with DEP after transfection with anti–hsa-miR-375. Our data show that two pollutants, DEP and ambient PM, upregulate TSLP in human bronchial epithelial cells by a mechanism that includes hsa-miR-375 with complex regulatory effects on AhR mRNA. The absence of this pathway in TNF-α–treated cells suggests multiple regulatory pathways for TSLP expression in these cells.

T cell-derived IL-17 mediates epithelial changes in the airway and drives pulmonary neutrophilia.

Th17 cells are a proinflammatory subset of effector T cells that have been implicated in the pathogenesis of asthma. Their production of the cytokine IL-17 is known to induce local recruitment of neutrophils, but the direct impact of IL-17 on the lung epithelium is poorly understood. In this study, we describe a novel mouse model of spontaneous IL-17–driven lung inflammation that exhibits many similarities to asthma in humans. We have found that STAT3 hyperactivity in T lymphocytes causes an expansion of Th17 cells, which home preferentially to the lungs. IL-17 secretion then leads to neutrophil infiltration and lung epithelial changes, in turn leading to a chronic inflammatory state with increased mucus production and decreased lung function. We used this model to investigate the effects of IL-17 activity on airway epithelium and identified CXCL5 and MIP-2 as important factors in neutrophil recruitment. The neutralization of IL-17 greatly reduces pulmonary neutrophilia, underscoring a key role for IL-17 in promoting chronic airway inflammation. These findings emphasize the role of IL-17 in mediating neutrophil-driven pulmonary inflammation and highlight a new mouse model that may be used for the development of novel therapies targeting Th17 cells in asthma and other chronic pulmonary diseases.

Perspective: Ambient Air Pollution: Inflammatory Response and Effects on the Lung's Vasculature

Particulates from air pollution are implicated in causing or exacerbating respiratory and systemic cardiovascular diseases and are thought to be among the leading causes of morbidity and mortality. However, the contribution of ambient particulate matter to diseases affecting the pulmonary circulation, the right heart, and especially pulmonary hypertension is much less documented. Our own work and that of other groups has demonstrated that prolonged exposure to antigens via the airways can cause severe pulmonary arterial remodeling. In addition, vascular changes have been well documented in a typical disease of the airways, asthma. These experimental and clinical findings link responses in the airways with responses in the lungs vasculature. It follows that particulate air pollution could cause, or exacerbate, diseases in the pulmonary circulation and associated pulmonary hypertension. This perspective details the literature for support of this concept. Data regarding the health effects of particulate matter from air pollution on the lungs vasculature, with emphasis on the lungs inflammatory responses to particulate matter deposition and pulmonary hypertension, are discussed. A deeper understanding of the health implications of exposure to ambient particulate matter will improve our knowledge of how to improve the management of lung diseases, including diseases of the pulmonary circulation. As man-made ambient particulate air pollution is typically linked to economic growth, a better understanding of the health effects of exposure to particulate air pollution is expected to integrate the global goal of achieving healthy living for all.

Short-term inhalation of cadmium oxide nanoparticles alters pulmonary dynamics associated with lung injury, inflammation, and repair in a mouse model

Abstract Context: Cadmium oxide nanoparticles (CdO NPs) are employed in optoelectronic devices and as a starting material for generating quantum dots as well as for medical imaging and targeting of pharmaceutical agents to disease sites. However, there are lack of data concerning short- and long-term effects of CdO NPs on the lungs. Objective: To determine the effects of inhaled CdO NPs at an occupationally relevant concentration on pulmonary injury and repair, and on systemic immunity in adult male mice. Methods: Mice were exposed to 240 μg CdO NPs/m3 for seven days (3 h/d) and lavage levels of pulmonary injury/inflammatory markers, bacterial uptake by circulating phagocytes, and lung histology examined either one or seven days following the final exposure. Results: Levels of total protein, lactate dehydrogenase activity, cytokine markers of inflammation (i.e. interleukin-1β, tumor necrosis factor-α, and interferon-γ), tissue remodeling matrix metalloproteinases (MMP)-2 and -9 activity, and phagocytic activity of circulating phagocytes were significantly increased one day after the final exposure. By seven days post-exposure, MMP-2 activity decreased to control levels, while MMP-9 activity remained significantly above control values, although dropping by about half from day one. Conclusions: This study demonstrates that short-term inhalation exposure to CdO NPs can stimulate pathways in the lungs associated with inflammation, cell injury, and tissue remodeling as well as alter immune function. Findings here demonstrate that even short-term inhalation exposure to CdO NPs in the workplace could lead to deleterious pulmonary effects in exposed workers.

Exposure to inhaled nickel nanoparticles causes a reduction in number and function of bone marrow endothelial progenitor cells

Introduction: Particulate matter (PM), specifically nickel (Ni) found on or in PM, has been associated with an increased risk of mortality in human population studies and significant increases in vascular inflammation, generation of reactive oxygen species, altered vasomotor tone, and potentiated atherosclerosis in murine exposures. Recently, murine inhalation of Ni nanoparticles have been shown to cause pulmonary inflammation that affects cardiovascular tissue and potentiates atherosclerosis. These adverse cardiovascular outcomes may be due to the effects of Ni on endothelial progenitor cells (EPCs), endogenous semi-pluripotent stem cells that aid in endothelial repair. Thus, we hypothesize that Ni nanoparticle exposures decrease cell count and cause impairments in function that may ultimately have significant effects on various cardiovascular diseases, such as, atherosclerosis. Methods: Experiments involving inhaled Ni nanoparticle exposures (2 days/5 h/day at ∼1200 µg/m3, 3 days/5 h/day at ∼700 µg/m3, and 5 days/5 h/day at ∼100 µg/m3), were performed in order to quantify bone marrow resident EPCs using flow cytometry in C57BL/6 mice. Plasma levels of human stromal cell-derived factor 1α (SDF-1α) and vascular endothelial growth factor (VEGF) were assessed by enzyme-linked immunosorbent assay and in vitro functional assessments of cultured EPCs were conducted. Results and conclusions: Significant EPC count differences between exposure and control groups for Ni nanoparticle exposures were observed. Differences in EPC tube formation and chemotaxis were also observed for the Ni nanoparticle exposed group. Plasma VEGF and SDF-1α differences were not statistically significant. In conclusion, this study shows that inhalation of Ni nanoparticles results in functionally impaired EPCs and reduced number in the bone marrow, which may lead to enhanced progression of atherosclerosis.

Prenatal exposure to allergen, DNA methylation, and allergy in grandoffspring mice

Prenatal allergen exposure has been linked to both induction and protection of allergic sensitization in offspring. We hypothesized that prenatal exposure of mice (F0) to Aspergillus fumigatus (A. fumigatus) would be associated with decreased immunoglobulin (Ig) E and airway eosinophilia and alterations in CpG methylation of T‐helper genes in third‐generation mice (F2).

Prenatal allergen and diesel exhaust exposure and their effects on allergy in adult offspring mice

BackgroundMultiple studies have suggested that prenatal exposure to either allergens or air pollution may increase the risk for the development of allergic immune responses in young offspring. However, the effects of prenatal environmental exposures on adult offspring have not been well-studied. We hypothesized that combined prenatal exposure to Aspergillus fumigatus (A. fumigatus) allergen and diesel exhaust particles will be associated with altered IgE production, airway inflammation, airway hyperreactivity (AHR), and airway remodeling of adult offspring.MethodsFollowing sensitization via the airway route to A. fumigatus and mating, pregnant BALB/c mice were exposed to additional A. fumigatus and/or diesel exhaust particles. At age 9-10 weeks, their offspring were sensitized and challenged with A. fumigatus.ResultsWe found that adult offspring from mice that were exposed to A. fumigatus or diesel exhaust particles during pregnancy experienced decreases in IgE production. Adult offspring of mice that were exposed to both A. fumigatus and diesel exhaust particles during pregnancy experienced decreases in airway eosinophilia.ConclusionThese results suggest that, in this model, allergen and/or diesel administration during pregnancy may be associated with protection from developing systemic and airway allergic immune responses in the adult offspring.

Progranulin Recruits HSP70 to β-Glucocerebrosidase and Is Therapeutic Against Gaucher Disease

Gaucher disease (GD), the most common lysosomal storage disease, is caused by mutations in GBA1 encoding of β-glucocerebrosidase (GCase). Recently it was reported that progranulin (PGRN) insufficiency and deficiency associated with GD in human and mice, respectively. However the underlying mechanisms remain unknown. Here we report that PGRN binds directly to GCase and its deficiency results in aggregation of GCase and its receptor LIMP2. Mass spectrometry approaches identified HSP70 as a GCase/LIMP2 complex-associated protein upon stress, with PGRN as an indispensable adaptor. Additionally, 98 amino acids of C-terminal PGRN, referred to as Pcgin, are required and sufficient for the binding to GCase and HSP70. Pcgin effectively ameliorates the disease phenotype in GD patient fibroblasts and animal models. These findings not only demonstrate that PGRN is a co-chaperone of HSP70 and plays an important role in GCase lysosomal localization, but may also provide new therapeutic interventions for lysosomal storage diseases, in particular GD.