2021 journal article

Differential gene expression and Ingenuity Pathway Analysis of bronchoalveolar lavage cells from horses with mild/moderate neutrophilic or mastocytic inflammation on BAL cytology

Veterinary Immunology and Immunopathology.

By: K. Davis n & M. Sheats n

co-author countries: United States of America 🇺🇸
author keywords: Equine asthma syndrome; Heaves; Inflammatory airway disease; Recurrent airway obstruction; Asthma phenotype; Gene expression; RNA-seq; BAL
MeSH headings : Animals; Bronchoalveolar Lavage / veterinary; Bronchoalveolar Lavage Fluid / cytology; Bronchoalveolar Lavage Fluid / immunology; Cytokines / genetics; Cytokines / immunology; Cytological Techniques; Female; Gene Expression; Horses / genetics; Inflammation / pathology; Inflammation / veterinary; Male; Mast Cells / immunology; Mast Cells / pathology; Metabolic Networks and Pathways / genetics; Metabolic Networks and Pathways / immunology; Neutrophils / immunology; Qualitative Research
Source: ORCID
Added: February 5, 2021

Mild to moderate equine asthma syndrome (mEAS) affects horses of all ages and breeds. To date, the etiology and pathophysiology of mEAS are active areas of research, and it remains incompletely understood whether mEAS horses with different immune cell 'signatures' on BAL cytology represent different phenotypes, distinct pathobiological mechanisms (endotypes), varied environmental conditions, disease severity, genetic predispositions, or all of the above. In this descriptive study, we compared gene expression data from BAL cells isolated from horses with normal BALF cytology (n = 5), to those isolated from horses with mild/moderate neutrophilic inflammation (n = 5), or mild/moderate mastocytic inflammation (n = 5). BAL cell protein lysates were analyzed for cytokine/chemokine levels using Multiplex Bead Immunoassay, and for select proteins using immunoblot. The transcriptome, determined by RNA-seq and analyzed with DEseq2, contained 20, 63, and 102 significantly differentially expressed genes in horses with normal vs. neutrophilic, normal vs. mastocytic, and neutrophilic vs. mastocytic BALF cytology, respectively. Pathway analyses revealed that BAL-isolated cells from horses with neutrophilic vs. normal cytology showed enrichment in inflammation pathways, and horses with mastocytic vs. normal cytology showed enrichment in pathways involved in fibrosis and allergic reaction. BAL cells from horses with mastocytic mEAS, compared to neutrophilic mEAS, showed enrichment in pathways involved in alteration of tissue structures. Cytokine analysis determined that IL-1β was significantly different in the lysates from horses with neutrophilic inflammation compared to those with normal or mastocytic BAL cytology. Immunoblot revealed significant difference in the relative level of MMP2 in horses with neutrophilic vs. mastocytic mEAS. Upregulation of mRNA transcripts involved in the IL-1 family cytokine signaling axis (IL1a, IL1b, and IL1R2) in neutrophilic mEAS, as well as KIT mRNA in mastocytic mEAS, are novel, potentially clinically relevant, findings of this study. These findings further inform our understanding of inflammatory cell subtypes in mEAS.