title: TLR2 regulates neutrophil recruitment and cytokine production with minor contributions from TLR9 during hypersensitivity pneumonitis.
abstract: Hypersensitivity pneumonitis (HP) is an interstitial lung disease that develops following repeated exposure to environmental antigens. The disease results in alveolitis, granuloma formation and may progress to a fibrotic chronic form, which is associated with significant morbidity and mortality. The severity of the disease correlates with a neutrophil rich influx and an IL-17 response. We used the Saccharopolysporarectivirgula (SR) model of HP to determine whether Toll-like receptors (TLR) 2 and 9 cooperate in neutrophil recruitment and IL-17-associated cytokine production during the development of HP. Stimulation of bone marrow derived macrophages (BMDMs) from C57BL/6, MyD88(-/-) and TLR2/9(-/-) mice with SR demonstrate that SR is a strong inducer of neutrophil chemokines and growth factors. The cytokines induced by SR were MyD88-dependent and, of those, most were partially or completely dependent on TLRs 2 and 9. Following in vivo exposure to SR, CXCL2 production and neutrophil recruitment were reduced in TLR2(-/-) and TLR2/9(-/-) mice suggesting that the response was largely dependent on TLR2; however the reduction was greatest in the TLR2/9(-/-) double knockout mice indicating TLR9 may also contribute to the response. There was a reduction in the levels of pro-inflammatory cytokines TNFα and IL-6 as well as CCL3 and CCL4 in the BALF from TLR2/9(-/-) mice compared to WT and single knockout (SKO) mice exposed one time to SR. The decrease in neutrophil recruitment and TNFα production in the TLR2/9(-/-) mice was maintained throughout 3 weeks of SR exposures in comparison to WT and SKO mice. Both TLRs 2 and 9 contributed to the Th17 response; there was a decrease in Th17 cells and IL-17 mRNA in the TLR2/9(-/-) mice in comparison to the WT and SKO mice. Despite the effects on neutrophil recruitment and the IL-17 response, TLR2/9(-/-) mice developed granuloma formation similarly to WT and SKO mice suggesting that there are additional mediators and pattern recognition receptors involved in the disease.
authors.affiliation: Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
authors.forename: Kelly
authors.initials: K
authors.lastname: Andrews
authors.forename: Hossam
authors.initials: H
authors.lastname: Abdelsamed
authors.forename: Ae-Kyung
authors.initials: AK
authors.lastname: Yi
authors.forename: Mark A
authors.initials: MA
authors.lastname: Miller
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Fitzpatrick
mesh_terms: D000542:Alveolitis, Extrinsic Allergic / Q000150:complications / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D000818:Animals; D018925:Chemokines / Q000096:biosynthesis; D016207:Cytokines / Q000096:biosynthesis*; D005260:Female; D006099:Granuloma / Q000150:complications / Q000473:pathology; D007249:Inflammation / Q000150:complications / Q000473:pathology; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008214:Lymphocytes / Q000276:immunology; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation / Q000235:genetics; D020556:Neutrophil Infiltration / Q000276:immunology*; D016930:Saccharopolyspora / Q000502:physiology; D018417:Th1 Cells / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology; D051195:Toll-Like Receptor 2 / Q000172:deficiency / Q000378:metabolism*; D051217:Toll-Like Receptor 9 / Q000172:deficiency / Q000378:metabolism*
chemical_list: D018925:Chemokines; D016207:Cytokines; C493486:Tlr2 protein, mouse; C495370:Tlr9 protein, mouse; D051195:Toll-Like Receptor 2; D051217:Toll-Like Receptor 9
references.citation: Am J Respir Cell Mol Biol. 1991 Nov;5(5):477-83
references.pmid: 1931076
references.citation: J Exp Med. 2010 Sep 27;207(10):2239-53
references.pmid: 20855496
references.citation: Annu Rev Immunol. 2002;20:197-216
references.pmid: 11861602
references.citation: Respirology. 2006 May;11(3):262-8
references.pmid: 16635083
references.citation: Eur J Immunol. 2005 Jun;35(6):1928-38
references.pmid: 15884056
references.citation: Transl Res. 2009 Nov;154(5):222-7
references.pmid: 19840763
references.citation: J Immunol. 2002 Oct 1;169(7):3700-9
references.pmid: 12244163
references.citation: Am J Respir Crit Care Med. 2007 Nov 15;176(10):1015-25
references.pmid: 17717199
references.citation: Am J Respir Crit Care Med. 2000 May;161(5):1698-704
references.pmid: 10806177
references.citation: Am J Respir Cell Mol Biol. 1991 Aug;5(2):198-203
references.pmid: 1892650
references.citation: Eur Respir J. 2009 Sep;34(3):749-56
references.pmid: 19282343
references.citation: Immunity. 2009 Aug 21;31(2):321-30
references.pmid: 19682928
references.citation: Curr Opin Pulm Med. 2004 Sep;10(5):378-82
references.pmid: 15316436
references.citation: J Clin Invest. 2010 May;120(5):1645-62
references.pmid: 20389019
references.citation: Am J Respir Crit Care Med. 1998 Aug;158(2):662-5
references.pmid: 9700147
references.citation: Immunol Allergy Clin North Am. 2011 Nov;31(4):769-86, vii
references.pmid: 21978856
references.citation: Indian J Chest Dis Allied Sci. 1989 Jul-Sep;31(3):187-96
references.pmid: 2638654
references.citation: J Allergy Clin Immunol. 2001 Nov;108(5):661-70
references.pmid: 11692086
references.citation: Infect Immun. 2010 Dec;78(12):5107-15
references.pmid: 20921147
references.citation: Chest. 1986 Mar;89(3 Suppl):190S-193S
references.pmid: 3948579
references.citation: Am J Respir Crit Care Med. 2009 Apr 15;179(8):705-16
references.pmid: 19151189
references.citation: J Immunol. 1998 Jul 15;161(2):991-9
references.pmid: 9670980
references.citation: Allergy. 2009 Mar;64(3):322-34
references.pmid: 19210361
references.citation: Curr Opin Pulm Med. 1997 Sep;3(5):391-5
references.pmid: 9331543
references.citation: Immunology. 2010 May;130(1):125-36
references.pmid: 20070409
references.citation: Am Rev Respir Dis. 1987 Jan;135(1):35-47
references.pmid: 2432812
references.citation: J Physiol Pharmacol. 2008 Dec;59 Suppl 6:499-505
references.pmid: 19218674
references.citation: Semin Respir Infect. 1995 Jun;10(2):96-106
references.pmid: 7569404
references.citation: J Immunol. 2009 May 15;182(10):6540-9
references.pmid: 19414809
references.citation: J Immunol. 2009 Jan 1;182(1):657-65
references.pmid: 19109199
references.citation: Scand J Immunol. 2009 Mar;69(3):268-74
references.pmid: 19281539
references.citation: Am J Respir Crit Care Med. 2006 Jan 15;173(2):188-98
references.pmid: 16166619
references.citation: J Inflamm (Lond). 2011 Jun 23;8(1):15
references.pmid: 21699708
references.citation: Radiol Clin North Am. 1992 Nov;30(6):1219-30
references.pmid: 1410310
references.citation: J Leukoc Biol. 2008 May;83(5):1207-17
references.pmid: 18285403
references.citation: Radiology. 1993 Oct;189(1):111-8
references.pmid: 8372179