1202. Tissue destruction and cavitation:  Neutrophils wield a double-edged sword in human pulmonary tuberculosis
Session: Oral Abstract Session: Biomarkers of Infectious Diseases
Saturday, October 5, 2013: 8:54 AM
Room: The Moscone Center: 300

Background: Neutrophil influx and tissue destruction are characteristic of TB which remains a leading cause of worldwide mortality.  A matrix degrading phenotype develops, in which the activity of matrix metalloproteinases (MMPs) is unopposed by their specific inhibitors (TIMPs) thus driving tissue damage in TB.  We hypothesized that neutrophils have a key role in such MMP-dependent tissue destruction in human TB.

Methods: Primary human neutrophils were infected with Mycobacterium tuberculosis (Mtb) or stimulated with conditioned media from Mtb-infected monocytes (CoMTB). MMP-8/-9 and TIMP-1/-2 secretion were analysed by Luminex array and zymography. Gene expression was studied by real-time PCR.  Neutrophil extracellular traps (NETS) were examined by immunofluorescence. DQ collagen degradation was examined by confocal microscopy and quantitative fluorescence assay. Induced sputum samples from 108 TB patients and controls were analyzed. Immunohistochemical analysis of human TB lung biopsies was performed. 

Results: Neutrophil MMP-8/-9 secretion are up-regulated 3 and 5 fold respectively by Mtb while CoMTB stimulation caused 2 and 3 fold increase in MMP-8/-9 (all p < 0.001). Mtb-infected neutrophils degrade collagen, which is abolished by the MMP inhibitor doxycycline. Mtb-driven NET formation is associated with MMP-8/-9.  MMP-8/-9 concentrations are elevated in induced sputum of TB patients compared to controls (both p <0.001) and strongly and significantly correlate with neutrophil markers myeloperoxidase and neutrophil gelatinase associated lipocalin.  MMP-8 concentration correlated with clinical TB severity score (r=0.55, p < 0.0001) and CXR score (r=0.52, p < 0.0001). Induced sputum from TB patients have increased collagenase activity (median 460 mU/ml, range 136.6-991.5mU/ml) which is suppressed by MMP-8 neutralization (median 216 mU/ml, range 99.2-526.8 mU/ml) (p=0.01). Immunohistochemistry of human TB lung specimens showed MMP-8/-9 neutrophils around the inner wall of the cavity.

Conclusion: Mtb drives neutrophil MMP-8/-9 gene expression and secretion following direct infection and in monocyte-dependent networks.  Targeting immunopathogenic neutrophils may reduce tissue destruction in TB patients.

Catherine Ong, MBBS, MRCP1,2, Paul Elkington, BA, BM, BCh, MRCP, PhD1,3, Cesar Ugarte-Gil, MD4, Liku Tezera, MD, PhD3, Robert Gilman, MD, DTMH5, Joanna Porter, BA, MB BCh, MA, PhD, FRCP6 and Jon S. Friedland, MA, PhD, FRCP, FRCPI, FMedSci1, (1)Imperial College London, London, United Kingdom, (2)National University Health System, Singapore, Singapore, (3)University of Southampton, Southampton, United Kingdom, (4)Instituto De Medicina Tropical Alexander Von Humboldt, Lima, Peru, (5)Johns Hopkins Bloomberg School of Public Health, Asociación Benéfica PRISMA, Universidad Peruana Cayetano Heredia, Lima, Peru, (6)University College London, London, United Kingdom

Disclosures:

C. Ong, None

P. Elkington, None

C. Ugarte-Gil, None

L. Tezera, None

R. Gilman, None

J. Porter, None

J. S. Friedland, None

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