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Pulmonary, Critical Care, Sleep and Allergy Section, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Neb 68198-5300, USA.
The Journal of allergy and clinical immunology (Impact Factor: 11.48). 06/2008; 122(2):375-82, 382.e1-4. DOI: 10.1016/j.jaci.2008.05.023
Source: PubMed


Organic dust exposure in the agricultural industry results in significant airway disease and lung function decrease. Mononuclear phagocytes are key cells that mediate the inflammatory and innate immune response after dust exposure.
We sought to investigate the effect of organic dust extract (ODE) from modern swine operations on monocyte-derived macrophage (MDM) phenotype and function.
Peripheral blood monocytes were obtained by means of elutriation methodology (>99% CD14(+)) and differentiated into macrophages in the presence of GM-CSF (1 week) with and without ODE (0.1%). At 1 week, cells were analyzed by means of flow cytometry for cell-surface marker expression (HLA-DR, CD80, CD86, Toll-like receptor 2, Toll-like receptor 4, mCD14, and CD16), phagocytosis (IgG-opsonized zymosan particles), and intracellular killing of Streptococcus pneumoniae. At 1 week, MDMs were rechallenged with high-dose ODE (1%), LPS, and peptidoglycan (PGN), and cytokine levels (TNF-alpha, IL-6, IL-10, and CXCL8/IL-8) were measured. Comparisons were made to MDMs conditioned with heat-inactivated dust, endotoxin-depleted dust, LPS, and PGN to elucidate ODE-associated factors.
Expression of HLA-DR, CD80, and CD86; phagocytosis; and intracellular bacterial killing were significantly decreased with ODE-challenged versus control MDMs. Responses were retained after marked depletion of endotoxin. PGN, LPS, and PGN plus LPS significantly reduced MDM surface marker expression and, except for LPS alone, also reduced phagocytosis. ODE-challenged MDMs had significantly diminished cytokine responses (TNF-alpha, IL-6, and IL-10) after repeat challenge with high-dose ODE. Cross-tolerant cytokine responses were also observed.
Repetitive organic dust exposure significantly decreases markers of antigen presentation and host defense function in MDMs. Bacterial cell components appear to be driving these impaired responses.

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Available from: Diane Allen-Gipson, Oct 05, 2015
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    • "Although not yet studied in the lung environment, MaR1 has shown utility in reducing neutrophil infiltration while increasing macrophage phagocytic capacities in a murine model of peritonitis [18]. Previously published data from our group suggest the recruitment and subsequent actions of macrophages in organic dust exposures are highly important in determining the outcomes of the pro-inflammatory insult, and pro-inflammatory cytokine production by BECs exposed to injurious stimuli such as organic dusts is key to the recruitment of these macrophages as well as neutrophils into the lung [19-23]. However, MaR1’s effects on BECs, along with other cells in the lung are currently unknown. "
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    ABSTRACT: Background Exposure to organic dust causes detrimental airway inflammation. Current preventative and therapeutic measures do not adequately treat resulting disease, necessitating novel therapeutic interventions. Recently identified mediators derived from polyunsaturated fatty acids exhibit anti-inflammatory and pro-resolving actions. We tested the potential of one of these mediators, maresin-1 (MaR1), in reducing organic dust-associated airway inflammation. Methods As bronchial epithelial cells (BECs) are pivotal in initiating organic dust-induced inflammation, we investigated the in vitro effects of MaR1 on a human BEC cell line (BEAS-2B). Cells were pretreated for 1 hour with 0–200 nM MaR1, followed by 1–24 hour treatment with 5% hog confinement facility-derived organic dust extract (HDE). Alternatively, a mouse lung slice model was utilized in supportive cytokine studies. Supernatants were harvested and cytokine levels determined via enzyme-linked immunosorbent assays. Epithelial cell protein kinase C (PKC) isoforms α and ϵ, and PKA activities were assessed via radioactivity assays, and NFκB and MAPK-related signaling mechanisms were investigated using luciferase vector reporters. Results MaR1 dose-dependently reduced IL-6 and IL-8 production following HDE treatment of BECs. MaR1 also reduced HDE-stimulated cytokine release including TNF-α in a mouse lung slice model when given before or following HDE treatment. Previous studies have established that HDE sequentially activates epithelial PKCα and PKCϵ at 1 and 6 hours, respectively that regulated TNF-α, IL-6, and IL-8 release. MaR1 pretreatment abrogated these HDE-induced PKC activities. Furthermore, HDE treatment over a 24-hour period revealed temporal increases in NFκB, AP-1, SP-1, and SRE DNA binding activities, using luciferase reporter assays. MaR1 pretreatment did not alter the activation of NFκB, AP-1, or SP-1, but did reduce the activation of DNA binding at SRE. Conclusions These observations indicate a role for MaR1 in attenuating the pro-inflammatory responses of BECs to organic dust extract, through a mechanism that does not appear to rely on reduced NFκB, AP-1, or SP-1-related signaling, but may be mediated partly through SRE-related signaling. These data offer insights for a novel mechanistic action of MaR1 in bronchial epithelial cells, and support future in vivo studies to test MaR1’s utility in reducing the deleterious inflammatory effects of environmental dust exposures.
    Respiratory research 05/2013; 14(1):51. DOI:10.1186/1465-9921-14-51 · 3.09 Impact Factor
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    • "Advances into understanding specific causative factors determined that PM size is important, with coarse PM inducing enhanced inflammation (Vogel et al., 2012). Endotoxin, signaling through TLR4 (Charavaryamath et al., 2008), remains an important causative agent, but recent studies show important roles for gram-positive bacteria (Nehme et al., 2009; Poole et al., 2008, 2010) and for targeting the TLR2 pathway. "
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    ABSTRACT: With increases in large animal-feeding operations to meet consumer demand, adverse upper and lower respiratory health effects in exposed agriculture workers are a concern. The aim of this study was to review large animal confinement feeding operational exposures associated with respiratory disease with a focus on recent advances in the knowledge of causative factors and cellular and immunological mechanisms. A PubMed search was conducted with the keywords airway, farm, swine, dairy, horse, cattle inflammation, organic dust, endotoxin, and peptidoglycan, among items were published between 1980 and now. Articles were selected based on their relevance to environmental exposure and reference to airway diseases. Airway diseases included rhinitis, sinusitis, mucus membrane inflammation syndrome, asthma, chronic bronchitis, chronic obstructive pulmonary disease, hypersensitivity pneumonitis, and organic dust toxic syndrome. There is lower prevalence of immunoglobulin (Ig) E-mediated asthma and atopy in farmers and their children, but organic dust worsens existing asthma. Multiple etiologic factors are linked to disease, including allergens, organic dusts, endotoxins, peptidoglycans, and gases. Large animal confinement feeding operations contain a wide diversity of microbes with increasing focus on gram-positive bacteria and archaebacteria as opposed to gram-negative bacteria in mediating disease. Toll-like receptors (TLR) and nucleotide oligomerization domain (NOD)-like innate immune pathways respond to these exposures. Finally, a chronic inflammatory adaptation, tolerance-like response in chronically exposed workers occurs. Large animal confinement farming exposures produce a wide spectrum of upper and lower respiratory tract diseases due to the complex diversity of organic dust, particulates, microbial cell wall components, and gases and resultant activation of various innate immune receptor signaling pathways.
    Journal of Toxicology and Environmental Health Part B 11/2012; 15(8):524-41. DOI:10.1080/10937404.2012.744288 · 4.97 Impact Factor
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    • "Human monocytes, neutrophils (PMNs) and red blood cells (RBCs) were isolated as previously described [32]. To prepare monocyte-derived macrophages (MDMs), isolated monocytes were cultured in DMEM/10% FCS supplemented with macrophage colony-stimulating factor (M-CSF) for 6 days [33]. Mature macrophages (3×105/well) were then plated in 24-well tissue culture plates and allowed to adhere for 2 h. "
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    ABSTRACT: Platelet depletion is a key feature of hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC) infection. The mechanism underlying STEC-induced platelet depletion, however, is not completely understood. Here we demonstrated for the first time that platelet surface expression of CD47 was significantly decreased in C57BL6 mice treated with concentrated culture filtrates (CCF) from STEC O157:H7. STEC O157:H7 CCF treatment also led to a sharp drop of platelet counts. The reduction of cell surface CD47 was specific for platelets but not for neutrophil, monocytes and red blood cells. Down-regulation of platelet surface CD47 was also observed in isolated human platelets treated with O157:H7 CCF. Platelet surface CD47 reduction by O157:H7 CCF could be blocked by anti-TLR4 antibody but not anti-CD62 antibody. Down-regulation of platelet surface CD47 was positively correlated with platelet activation and phagocytosis by human monocyte-derived macrophages. Furthermore, the enhanced phagocytosis process of O157:H7 CCF-treated platelets was abolished by addition of soluble CD47 recombinants. Our results suggest that platelet CD47 down-regulation may be a novel mechanism underneath STEC-induced platelet depletion, and that the interactions between CD47 and its receptor, signal regulatory protein alpha (SIRPalpha), play an essential role in modulating platelet homeostasis.
    PLoS ONE 09/2009; 4(9):e7131. DOI:10.1371/journal.pone.0007131 · 3.23 Impact Factor
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