A clinically silent respiratory infection withChlamydophilaspp. in calves is associated with airway obstruction and pulmonary inflammation

Abstract

-This study was aimed at evaluating functional and inflammatory consequences of persistent chlamydial infections on the respiratory system in clinically inconspicuous calves aged 2-7 months. Thirteen calves persistently infected with Chlamydophila (C.) abortus and/or C. pecorum (Chl+) were compared to 12 calves without chlamydial infections (Chl-). In order to evaluate lung function, 36 non-invasive impulse oscillometry tests were performed per animal within 6 months. The group of chronically infected animals was distinguished by significantly higher peripheral airway resistance (indicating peripheral airway obstruction), significantly higher respiratory rates, and significantly higher minute volumes of ventilation. At the age of seven months, all calves were necropsied, broncho-alveolar lavage fluid (BALF) was obtained ex vivo, and lungs were examined histologically. Significantly higher concentrations of total protein and 8-iso-prostane (8-IP), as well as higher activities of matrix metalloprotease 2 were measured in BALF samples of Chl+ calves. Histologically, markedly activated bronchus-associated lymphoid tissue (BALT) causing partial obstruction of bronchiolar lumina was found in the apical pulmonary lobes of Chl+ calves. Chlamydial DNA was detected in the lung tissue of 7 out of 13 Chl+ calves by real-time PCR. In conclusion, respiratory chlamydial infection appeared to be associated with chronic inflammation of the lungs and airways. Despite the lack of clinical symptoms, pulmonary dysfunctions persisted in calves until the age of seven months. Data obtained in this study provide new insight illustrating the impact of nearly ubiquitous subclinical infections on the respiratory system. Chlamydia / Chlamydophila infection / airway obstruction / pulmonary inflammation / calves

An experimentally inducedChlamydiasuis infection in pigs results in severe lung function disorders and pulmonary inflammation

“…The absence of a systemic effect parallels findings made in calves with chronic chlamydial infections [14]. Interestingly, chlamydia-infected calves showed a significant increase of MMP-2 activity in BALF, which paralleled subclinical and chronic inflammatory obstructive changes of airways [14]. In the present model of acute pulmonary infection, however, BALF MMP-2 activity remained unchanged in comparison to the control animals, whilst MMP-9 activity increased significantly.…”

“…Systemic repercussions on serum MMP-2 and MMP-9 activity were not detected. The absence of a systemic effect parallels findings made in calves with chronic chlamydial infections [14]. Interestingly, chlamydia-infected calves showed a significant increase of MMP-2 activity in BALF, which paralleled subclinical and chronic inflammatory obstructive changes of airways [14].…”

“…The activity of MMP-2 and MMP-9 was determined in serum and in the supernatant of BALF samples using zymography as previously described [14]. Electrophoretic migration and an incubation time of 18 h (serum) or 72 h (BALF) at 37 • C after migration were used.…”

The Bovine Lung in Biomedical Research: Visually Guided Bronchoscopy, Intrabronchial Inoculation and <em>In Vivo</em> Sampling Techniques

“…The BALF-supernatant contains various markers that change during inflammatory processes in the lung and can be studied under experimental conditions. Examples are total protein and eicosanoids 29,34 .…”

“…Typical examples are bovine tuberculosis 25 , respiratory syncytial virus (RSV) infections in calves [26][27][28] , or naturally acquired Chlamydia infections 29 . Thus, large animal models do closely resemble the situation in the natural host.…”