Diagnostic value of inflammatory markers in chronic respiratory disease of the horse – a review

Abstract

Summary: Over the last years local and systemic inflammatory markers of chronic pneumopathies have gained increasing interest in research, as the pathogenesis of Recurrent airway obstruction (RAO) and Inflammatory airway disease (IAD) remains not fully elucidated in several details. In human medicine, Asthma bronchiale and Chronic obstructive pulmonary disease (COPD) have been found to be influenced by systemic inflammatory processes and the other way around. Inflammation, coagulation and fibrinolysis as well as extracellular remodeling show close interactions. Cytology of bronchoalveolar lavage fluid and tracheal wash is commonly used to evaluate the severity of local inflammation in the lung. Interleukins involved in the chemotaxis of neutrophils like Interleukin 8, 17 and 23 have been studied. Chronic obstructive pneumopathies lead to remodeling of bronchial walls and lung parenchyma, ultimately causing fibrosis. Matrix-metalloproteinases (MMPs) are discussed as the most important proteolytic enzymes during remodeling in human medicine. In the horse, MMP 9 seems to be a central player in chronic respiratory disease as well. A systemic involvement has been shown for RAO by increased acute-phaseproteins like serumamyloid A and haptoglobin in peripheral blood during exacerbation. Studies focusing on these and further possible inflammatory markers for chronic respiratory disease in the horse are discussed in this review of literature.Keywords: Inflammatory markers / horse / respiratory disease / recurrent airway obstruction / RAO / Diagnostischer Wert verschiedener Entzündungsmarker bei chronischen Atemwegserkrankungen des Pferdes -eine ÜbersichtIn den letzten Jahren häufen sich Untersuchungen zu verschiedenen lokalen und systemischen Entzündungsmarkern bei chronischen Pneumopathien des Pferdes, da das Verständnis der Pathogenese von Recurrent airway obstruction (RAO) und Inflammatory airway disease (IAD) weiterhin nicht vollständig geklärt ist. Ein Blick in die Humanmedizin zeigt, dass das Asthma bronchiale und die Chronic obstructive pulmonary disease (COPD) durchaus in Zusammenhang stehen mit systemischen inflammatorischen Prozessen, so dass sich die lokalen Prozesse in der Lunge und systemische Entzündungsreaktionen gegenseitig beinflussen. Entzündung, Koagulation und Fibrinolyse sowie das extrazelluläre Remodelling sind eng miteinander verknüft. Zytologische Untersuchungen der bronchoalveolären Lavageflüssigkeit und des Tracheobronchialsekrets stellen die gebräuchlichste Methode dar, den Schweregrad der lokalen Entzündung zu beurteilen. Hierbei ergeben sich Zusammenhänge zu Interleukinen, die an der Chemotaxis neutrophiler Granulozyten beteiligt sind, wie beispielsweise Interleukin 8, 17 und 23. Chronisch obstruktive Pneumopathien führen langfristig zu chronischen Umbauprozessen der Bronchienwände und des Lungenparenchyms (Remodelling), die mit der Bildung von Fibrosen einhergehen. Matrix-Metalloproteinasen (MMPs) gelten in der Humanmedizin als wichtigste proteolytische Enzyme bei diesem Remodelling und auch...

Metalloproteinases and their inhibitors are influenced by inhalative glucocorticoid therapy in combination with environmental dust reduction in equine recurrent airway obstruction

“…Compared to these controls, all horses of the presented study showed increased levels of MMP 2, 8 and 9 prior to therapy. Increased TIMP levels have also been found in humans suffering from asthma [23, 24, 28, 29] and the same was found for equine RAO in this study and previous [26, 27]. This may allow the suspicion that fibrosis formation as a long-term consequence of human asthma and equine RAO may be the ultimate result of continuous activation of tissue repair mechanisms or over-repair processes [30].…”

“…Elastinolytic and collagenolytic activity was found in several studies on human asthma, in particular increased levels of MMP-9 [22, 23], but also MMP-2 [24, 25]. Former studies of our group showed that this is also true for several equine pneumopathies including RAO, inflammatory airway disease (IAD) and chronic interstitial pneumopathy compared to healthy controls [26, 27]. Compared to these controls, all horses of the presented study showed increased levels of MMP 2, 8 and 9 prior to therapy.…”