Objective—To examine the effects of in vitro exposure to solutions of autologous horse blood (AHB) and autologous horse serum (AHS) on expressions of selected cytokine genes in equine primary bronchial epithelial cell (BEC) cultures and to contrast these responses to those induced in BEC cultures by endotoxin and hay dust.
Sample—BEC cultures established from bronchi of 6 healthy horses.
Procedures—5-day-old BEC cultures were treated with PBS solution, AHB (2 concentrations), AHS, hay dust solution, and lipopolysaccharide solution for 24 hours. Gene expressions of interleukin (IL)-8, IL-1β, chemokine (C-X-C motif) ligand 2 (CXCL2), and glyceralde-hyde-3-phosphate dehydrogenase were subsequently measured with a kinetic PCR assay.
Results—With the exception of AHS, all treatments of the BECs resulted in upregulation of each target gene expression relative to its expression in cultures exposed to PBS solution. Treatment with AHB induced a dose-dependent increase of each target gene, with IL-1β expression increasing the most (> 1,200-fold increase). Lipopolysaccharide and hay dust solution treatments each resulted in 20-fold increases in IL-8 and IL-1β gene expressions. Lipopolysaccharide and hay dust solution treatments also resulted in a 7- and 8-fold increase in CXCL2 gene expression, respectively. The increases in IL-8 and CXCL2 gene expressions following treatment with the higher concentration of blood were equivalent to those associated with hay dust solution or lipopolysaccharide.
Conclusions and Clinical Relevance—Results suggested that chemokine expression by cultured equine BECs following exposure to pulmonary hemorrhage conditions may contribute to the development of inflammatory airway disease in horses.
Objective—To examine gene expression of selected cytokines in pulmonary mononuclear cells isolated from healthy horses and horses susceptible to recurrent airway obstruction (RAO), and to determine whether interleukin (IL)-17 and IL-23 were associated with pulmonary inflammation.
Animals—6 RAO-susceptible and 5 healthy horses.
Procedures—Bronchoalveolar lavage cells were retrieved from horses that were stabled and fed dusty hay for 24 hours. Lavage cells devoid of neutrophils were incubated for 24 hours with solutions of PBS, hay dust, lipopolysaccharide, or β-glucan. Gene expression of IL-17, IL-23 (p19 and p40 subunits), IL-8, IL-1β, chemokine (C-X-C motif) ligand 2 (CXCL2), and β-actin was measured by use of real-time reverse transcription PCR assays.
Results—The degree of inherent expression of target genes in bronchoalveolar lavage cells treated with PBSS was not different between the 2 groups of horses. Relative to exposure to PBSS, exposure to the hay dust solution increased gene expression of all cytokines more than 2-fold in cells from both groups of horses, but the magnitudes of these increases were not different between the groups. Exposure to lipopolysaccharide solution increased gene expression of IL-8, CXCL2, and IL-1β in cells from RAO-susceptible horses, but this increase was not significantly different from that in cells from control horses. Exposure to β-glucan solution failed to increase gene expression in cells from either horse group, compared with gene expression when cells were exposed to PBSS.
Conclusions and Clinical Relevance—The acute pulmonary neutrophilia characteristic of RAO was not associated with an increase in upregulation of gene expression of chemokines in pulmonary mononuclear cells from disease-susceptible horses.
Objective—To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or β-glucan on chemokine and cell-surface receptor (CSR) gene expression in primary bronchial epithelial cell cultures (BECCs) established from healthy horses and horses with recurrent airway obstruction (RAO).
Sample Population—BECCs established from bronchial biopsy specimens of 6 RAO-affected horses and 6 healthy horses.
Procedures—5-day-old BECCs were treated with PBS solution, hay dust solutions, LPS, or β-glucan for 6 or 24 hours. Gene expression of interleukin (IL)-8, chemokine (C-X-C motif) ligand 2 (CXCL2), IL-1β, toll-like receptor 2, toll-like receptor 4, IL-1 receptor 1, and glyceraldehyde 3–phosphate dehydrogenase was measured with a kinetic PCR assay.
Results—Treatment with PBS solution for 6 or 24 hours was not associated with a significant difference in chemokine or CSR expression between BECCs from either group of horses. In all BECCs, treatment with hay dust or LPS for 6 hours increased IL-8, CXCL2, and IL-1β gene expression > 3-fold; at 24 hours, only IL-1β expression was upregulated by > 3-fold. In all BECCs, CSR gene expression was not increased following any treatment. With the exception of a 3.7-fold upregulation of CXCL2 in BECCs from RAO-affected horses (following 6-hour hay dust treatment), no differences in chemokine or CSR gene expression were detected between the 2 groups. At 24 hours, CXCL2 gene expression in all BECCs was downregulated.
Conclusions and Clinical Relevance—Epithelial CXCL2 upregulation in response to hay dust particulates may incite early airway neutrophilia in horses with RAO.
Objective—To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or β-glucan on cytokine expression in pulmonary mononuclear cells isolated from healthy horses and horses with recurrent airway obstruction (RAO).
Animals—8 RAO-affected and 7 control horses (experiment 1) and 6 of the RAO-affected and 5 of the control horses (experiment 2).
Procedures—Bronchoalveolar lavage cells were isolated from horses that had been stabled and fed dusty hay for 14 days. Pulmonary mononuclear cells were incubated for 24 (experiment 1) or 6 (experiment 2) hours with PBS solution or solutions of hay dust, β-glucan, or LPS. Gene expression of interleukin (IL)-17, IL-23(p19 and p40 subunits), IL-8, IL-1β, and chemokine (C-X-C motif) ligand 2 (CXCL2) was measured with a kinetic PCR assay.
Results—Treatment with the highest concentration of hay dust solution for 6 or 24 hours increased expression of IL-23(p19 and p40), IL-8, and IL-1β in cells from both groups of horses and increased early expression of IL-17 and CXCL2 in RAO-affected horses. Lipopolysaccharide upregulated early expression of IL-23(p40) and IL-8 in cells from both groups of horses but only late expression of these cytokines in cells from RAO-affected horses. Treatment with β-glucan failed to increase cytokine expression at 6 or 24 hours.
Conclusions and Clinical Relevance—Cells from RAO-affected horses were not more responsive to the ligands tested than were cells from control horses, which suggests a minimal role of mononuclear cells in propagation of airway neutrophilia in horses with chronic RAO.
Objective—To evaluate time-dependent alterations in gene expression of chemokines in bronchial epithelium of recurrent airway obstruction (RAO)-affected horses and whether alterations resulted from increases in gene expression of interleukin (IL)-17 in cells isolated from bronchoalveolar lavage fluid (BALF).
Animals—8 RAO-susceptible horses and 9 control horses.
Procedure—In 2 experiments, both groups of horses were evaluated after being maintained on pasture and after being stabled and fed dusty hay for 1, 14, 35, and 49 days (experiment 1) or 14 and 28 days (experiment 2). In experiment 1, gene expression of IL-8, chemokine (C-X-C motif) ligand 1 (CXCL1), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and Toll-like receptor 4 (TLR4) in epithelium and IL-8, IL-17, and TLR4 in BALF cells was measured. In experiment 2, bronchial biopsy specimens were evaluated for IL-8 immunoreactivity.
Results—In RAO-susceptible horses after 14 days of challenge exposure, there was a 3- and 10-fold increase in gene expression of IL-8 for epithelial and BALF cells and an increase in IL-8 immunoreactivity in epithelial cells. Challenge exposure failed to alter gene expression of CXCL1, GM-CSF, G-CSF, and TLR4 in epithelial cells of any horses at any time point. During challenge exposure, gene expression of BALF cell IL-17 was downregulated in control horses (day 1) and upregulated in RAO-affected horses (day 35).
Conclusions and Clinical Relevance—Epithelial-derived IL-8 may promote airway neutrophilia, but the inciting stimulus is unlikely to be IL-17 because upregulation of this gene is subsequent to that of IL-8 in epithelial cells.
Objective—To determine whether results of physical
or radiographic examination or biochemical analyses
in adult racehorses with primary lung abscesses were
associated with ability to race following treatment.
Design—Multiple-center retrospective study.
Animals—25 Standardbreds and 20 Thoroughbreds.
Procedure—Medical records of horses with a primary
lung abscess that were admitted to any of 4 veterinary
teaching hospitals were reviewed. Results of
physical examination, laboratory testing, and thoracic
radiography were reviewed. Racing performance after
treatment was compared with performance before illness
and with performance of the general population
of racehorses of similar age, sex, and breed.
Results—23 of 25 Standardbreds and 13 of 20
Thoroughbreds raced after diagnosis and treatment of
a lung abscess. Most horses had a solitary abscess in
the dorsal to caudodorsal lung fields. Results of initial
physical examination, biochemical analyses, and culture
and identification of the microbial isolate were
not associated with whether a horse returned to racing.
For horses that had raced prior to the illness, race
performance after treatment of the lung abscess was
not significantly different from performance before
Conclusions and Clinical Relevance—On the basis
of racing performance in those horses that resumed
racing after treatment, long-term residual lung damage
did not develop in horses with primary lung
abscesses that were treated appropriately. It is not
known whether horses that recovered would be more
likely to bleed from the site of a prior infection when
resuming strenuous exercise and whether lung
abscesses contributed to a failure to resume racing.
(J Am Vet Med Assoc 2000;216:1282–1287)