Localization and Functional Characterization of Pulmonary Bovine Odorant-Binding Protein

Abstract

Bovine odorant-binding protein (OBP) may function in olfaction and defense against oxidative injury, but its role in inflammation and defense against bacterial infection has not been investigated. Expression of OBP was discovered in the bovine lung and found to undergo changes in abundance during glucocorticoid administration and stress. OBP was localized to nasal, tracheal, and bronchial mucosal glands with immunohistochemistry, with faint expression in airway surface epithelium and none in bronchioles or alveoli. Two isoforms of OBP were identified, appearing to be differentially regulated during lipopolysaccharide-induced pulmonary inflammation, but differences between these isoforms were not revealed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Functional studies showed no effect of OBP on in vitro growth of Escherichia coli or Mannheimia haemolytica under iron-replete or iron-depleted conditions, nor did OBP opsonize bacteria for an enhanced neutrophil oxidative burst. However, OBP did reduce the ability of supernatants from lipopolysaccharide-stimulated macrophages to induce neutrophil chemotaxis. These findings indicate that OBP may inhibit neutrophil recruitment by inflammatory mediators, and they suggest an ability to bind macrophage-derived inflammatory mediators within the airways.

Changes in the Saliva Proteome of Pigs with Diarrhoea Caused by Escherichia coli

“…In addition, this protein has been related to inflammation, showing a decrease in lungs in bovine after LPS administration. This decrease in OBP levels may be an additional mechanism to allow inflammatory mediators to stimulate neutrophil recruitment and oxidative burst in the lung and possibly in other tissues [ 17 ].…”

Inflammation interferes with chemoreception in pigs by altering the neuronal layout of the vomeronasal sensory epithelium

“…The present study showed that, when inflammation was detected in VNSE, regardless of the intensity, the expression of OBP in the surrounding areas was increased. This observation could be explained by the modulatory role of OBP in the inflammatory response proposed by Mitchell et al (62), as this protein seems to inhibit neutrophil recruitment by inflammatory mediators in the respiratory system (62). Some studies on other species demonstrated OBP compensatory properties on olfactory systems, where different OBP subtypes have been reported to occur simultaneously (63)(64)(65).…”

Modulation of olfactory signal detection in the olfactory epithelium: focus on the internal and external environment, and the emerging role of the immune system

“…Additionally, recent data suggest that OBPs may also act as antimicrobial components against pathogenic microorganisms (Bianchi et al 2019). The dual role of OBPs in olfaction and immunity is also highlighted by a study indicating that OBPs may modulate neutrophil recruitment through binding to macrophage-derived inflammatory mediators in the upper airway (Mitchell et al 2011).…”