title: Streptolysin-O/antibiotics adjunct therapy modulates site-specific expression of extracellular matrix and inflammatory genes in lungs of Rhodococcus equi infected foals.
abstract: The addition of streptolysin-O (SLO) to the standard antibiotics regimen was shown to be superior to antibiotics alone after experimental infection of foals with Rhodoccocus equi (R. equi). The objective of this study is to investigate this response by determining the site-specific expression of extracellular matrix (ECM) and inflammatory response genes in biopsy samples taken from three distinct lung regions of the infected foals. Twenty-four foals were challenged by intrabronchial instillation of R. equi and assigned to four treatment groups: SLO/antibiotics adjunct therapy, antibiotics-only therapy (7.5 mg/kg clarithromycin and 5 mg/kg rifampin), SLO-only, and saline-only treatments. Treatments were administered twice daily for 16 days unless symptoms progressed to the point where the foals needed to be euthanized. Gene expressions were determined using custom-designed equine real-time qPCR arrays containing forty-eight genes from ECM remodeling and inflammation pathways. A non-parametric Wilcoxon signed-rank test for independent samples was applied to two pairs of time-matched comparison groups, SLO/antibiotics vs. antibiotics-only and SLO-only vs. saline-only, to document the significant differences in gene expressions within these groups. Several genes, MMP9, MMP2, TIMP2, COL1A1, COL12A1, ITGAL, ITGB1, FN1, CCL2, CCL3, CXCL9, TNFα, SMAD7, CD40, IL10, TGFB1, and TLR2, were significantly regulated compared to the unchallenged/untreated control foals. The results of this study demonstrate that enhancement of clinical responses by SLO is consistent with the changes in expression of critical genes in ECM remodeling and inflammatory response pathways.
authors.affiliation: Beech Tree Labs Inc, 117 Chapman St, Providence, RI 02905, USA. Volkan_gurel@beechtreelabs.com
authors.forename: Volkan
authors.initials: V
authors.lastname: Gurel
authors.forename: Kristyn
authors.initials: K
authors.lastname: Lambert
authors.forename: Allen E
authors.initials: AE
authors.lastname: Page
authors.forename: Alan T
authors.initials: AT
authors.lastname: Loynachan
authors.forename: Katherine
authors.initials: K
authors.lastname: Huges
authors.forename: John F
authors.initials: JF
authors.lastname: Timoney
authors.forename: Michael
authors.initials: M
authors.lastname: Fettinger
authors.forename: David W
authors.initials: DW
authors.lastname: Horohov
authors.forename: John
authors.initials: J
authors.lastname: McMichael
mesh_terms: D000193:Actinomycetales Infections / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology; D001706:Biopsy / Q000662:veterinary; D005109:Extracellular Matrix / Q000235:genetics / Q000276:immunology; D006734:Horse Diseases / Q000188:drug therapy* / Q000235:genetics / Q000382:microbiology; D006736:Horses; D008171:Lung Diseases / Q000188:drug therapy / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction; D016929:Rhodococcus equi / Q000302:isolation & purification*; D018709:Statistics, Nonparametric; D013301:Streptolysins / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D013301:Streptolysins; C025964:streptolysin O