Serum Surfactant Protein D and Haptoglobin as Potential Biomarkers for Inflammatory Airway Disease in Horses.

Abstract

BACKGROUND: The identification of serum biomarkers of lung inflammation would facilitate the diagnosis of inflammatory airway disease (IAD) in horses. HYPOTHESIS: Horses with IAD have higher serum concentrations of markers of inflammation compared to controls. ANIMALS: Twelve horses with IAD and 10 control horses. METHODS: This was a prospective case-control study. Blood and BALF were collected from horses with IAD and controls. Serum concentration of surfactant protein D (SP-D), haptoglobin, serum amyloid A (SAA) and of the soluble form of triggering receptor expressed on myeloid cells 1 (sTREM-1) was measured using commercial ELISA tests. RESULTS: Horses with IAD had higher serum concentration (log-transformed values) of SP-D (mean&#xa0;&#xb1;&#xa0;SD: 1.773&#xa0;&#xb1;&#xa0;0.51), haptoglobin (6.657&#xa0;&#xb1;&#xa0;0.202) and SAA (0.128&#xa0;&#xb1;&#xa0;0.396) compared to controls (0.942&#xa0;&#xb1;&#xa0;0.226, 6.38&#xa0;&#xb1;&#xa0;0.22, -0.398&#xa0;&#xb1;&#xa0;0.319, respectively; P&#xa0;<&#xa0;.01 for all). Furthermore, the concentrations of SP-D and haptoglobin combined allowed differentiating the 2 groups (IAD: 8.43&#xa0;&#xb1;&#xa0;0.564, controls: 7.322&#xa0;&#xb1;&#xa0;0.249, P&#xa0;<&#xa0;.0001) with a sensitivity and specificity of 100% when a cut-off of 7.70 (log value) was employed. CONCLUSIONS AND CLINICAL IMPORTANCE: Surfactant protein D and haptoglobin serum concentrations could be a diagnostic aid in IAD. Further studies are necessary to establish the specificity of our findings before they can be applied in everyday practice.