How to cite this article: Vet. Res. (2008) 39:35
DOI: 10.1051/vetres:2008012

An experimentally induced Chlamydia suis infection in pigs results in severe lung function disorders and pulmonary inflammation

Petra Reinhold¹, Nathalie Kirschvink², Dirk Theegarten³ and Angela Berndt<sup>1

1</sup>  Institute of Molecular Pathogenesis at the Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Naumburger Str. 96a, 07743 Jena, Germany
²  Animal Physiology, Department of Veterinary Medicine, Faculty of Sciences, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium
³  Institute of Pathology and Neuropathology, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany

(Received 31 October 2007; accepted 22 February 2008; published online 26 February 2008)

Abstract - This study was aimed at evaluating the pathophysiology of pulmonary dysfunctions and inflammatory consequences of an acute respiratory chlamydial infection induced experimentally in conventionally raised pigs (aged 39-44 days). Eight animals were exposed to Chlamydia suis (C. suis) and four non-infected animals served as controls. The total observation period was from seven days before challenge to seven days post exposure. While non-infected control pigs did not exhibit any clinical symptoms, animals exposed to C. suis developed fever and were severely respiratory distressed within the first week after exposure. After C. suis infection, pulmonary dysfunctions were characterised by a significant decrease in the diffusion capacity of the lung (i.e. transfer factor of the lung for carbon monoxide; TL CO), a significant increase in the functional residual capacity (FRC), and significant changes in the pattern of ventilation (respiratory rate increased while the tidal volume decreased). In exhaled breath condensate (EBC), leukotriene B₄ (LTB₄) and interleukin 6 (IL-6) showed a tendency to increase after infection. In the broncho-alveolar lavage fluid (BALF) of C. suis infected pigs, the activity of matrix metalloprotease 9 (MMP-9) was found to be increased compared to controls. BALF cytology was characterised by increased numbers of granulocytes and activated lymphocytes. Pulmonary inflammation in infected pigs was confirmed by post mortem histology. A prominent dissemination of chlamydial bodies in the lung was accompanied by an influx of macrophages, granulocytes and activated T-cells. Data obtained in this study provide new insight into the pathogenesis of acute respiratory chlamydial infections in pigs.

Key words: Chlamydia suis model / pulmonary inflammation / lung functions / exhaled breath condensate (EBC) / BALF

Corresponding author: petra.reinhold@fli.bund.de

© INRA, EDP Sciences 2008