A comparison of pro-inflammatory cytokine mRNA expression in equine bronchoalveolar lavage (BAL) and peripheral blood

Regulatory T lymphocytes and selected cytokines in horses with mild to severe equine asthma and different inflammatory cytology profiles

This study determined Tregs and inflammatory cytokines in BALF and peripheral blood (PB) of adult horses with mild and severe asthma and different BALF cytological inflammation profiles. Horses of diverse breeds with asthma (age range: 2-20 years, n = 24) were divided into groups according to the number of points obtained in a standardized clinical scoring system (mild-moderate equine asthma - MEA, severe equine asthma - SEA) and according to the inflammation type based on cytological finding. Plasma levels of IFN-γ, IL-4, IL-10, IL-17 and MMP-9 in the BALF were determined by ELISA. Tregs in the BALF and PB were detected by flow cytometry. Horses with SEA were older than horses with MEA and had higher concentrations of MMP-9 in the BALF (P < 0.05). The neutrophilic inflammation group was characterised by higher age, grade of clinical score, percentage of Tregs and MMP-9 concentration in the BALF compared to the mastocytic inflammation group (P < 0.05). Age positively correlated with neutrophils, grade of score, Tregs in the BALF and in the PB. The grade of score positively correlated with MMP-9. The percentage of Tregs in the BALF positively correlated with Tregs in the PB. Tregs in the BALF and PB positively correlated with neutrophils and MMP-9 in the BALF and with IFN-γ, IL-4 and IL-10 in the plasma. IFN-γ and IL-10 in the plasma positively correlated with the age. The results indicate that the evaluation of selected parameters in PB, the collection of which is less invasive than the collection of BALF, is of potential importance.

Effectiveness of immunization with multi-component bacterial immunomodulator in foals at 35th day of life

The aim of the study was to investigate the mechanisms leading to immunization through the use of a multicomponent bacterial immunomodulator and to find out the relationship between the TLR 4 receptor with selected parameters of innate immunity and to acquire immunity. The study was conducted on 18 Polish Pony Horses foals divided into two study groups: control (n = 9) and experimental (n = 9). Foals from the experimental group received intramuscular duplicate injection of 5 ml of multi-component bacterial immunomodular at 35 and 40 days of age. RNA isolated from venous blood was used to evaluate the expression of TLR4 genes using RT-PCR. Concentration of Il-6, IL-10, IgM and IgG2 was determined by the ELISA method in blood plasma. Immunostimulation had a significant impact on the level of genes expression for TLR4 expression and IL-6 concentration. No effect of stimulation on IgM and IgG2 concentrations was found. The expression of TLR4 genes as well as the levels of interleukins could be modulated by stimulation with a pharmacological agent multi-component bacterial immunomodulator. The experiment demonstrated a strong positive correlation between TLR4 gene expression and IL-6 concentration and between TLR4 gene expression and IgM concentration.

Effect of aging on monocyte phagocytic and inflammatory functions, and on the ex vivo inflammatory responses to lipopolysaccharide, in horses

Studies investigating age-related changes in the function of monocytes are currently limited for horses. Thus, the main goal of this study was to determine the effect of aging on monocyte phagocytic capacity and pro-inflammatory cytokine responses to bacterial lipopolysaccharide (LPS). A second goal of this work was to examine the effect of aging on the inflammatory cytokine responses to LPS in a whole blood ex vivo model. Seven healthy young adult (4-6 years of age) and seven healthy senior horses (>20 years of age) were enrolled. Phagocytosis of E. coli, and pro-inflammatory cytokine (TNFα) responses to LPS, were measured in monocytes by flow cytometry. Gene expressions of pro-inflammatory cytokines (TNFα, IL-1β, IL-6, IL-8, IL-18, CCL-5, CCL-2) were measured in peripheral blood mononuclear cells (PBMCs) and whole blood by RT-qPCR post incubation for 2 h or 6 h with a low (0.01 µg/mL) or a high (1 µg/mL) dose of LPS. Two sets of statistical models were applied to compare the age groups, one adjusted, and one unadjusted for the horses' body condition scores (BCS). The percentage of monocytes that phagocytosed E. coli after 2 h of incubation was significantly lower in senior compared to young adult horses in the BCS-adjusted model. In the senior group, the expression of IL-1β in 2 h-0.01 µg/mL LPS-stimulated PBMCs was significantly higher than in the young adult group (BCS-adjusted and unadjusted models). In senior horses, expressions of IL-8 and IL-6 in whole blood samples stimulated for 6 h with 0.01 µg/mL LPS and for 2 h with 1 µg/mL LPS, respectively, were significantly lower than in young adult horses (BCS-adjusted models). The results of this study suggest that the phagocytic function of monocytes, as well as their IL-1β response to LPS may be altered in senior horses. In addition, the whole blood IL-8 and IL-6 gene expression responses to LPS may be insufficient in senior horses. While investigation of the effect of BCS on monocyte functions and whole blood pro-inflammatory LPS-responses was not a major goal of this work, it appears that adiposity may play a role in innate immune cell function, as significant differences between the age groups were often not apparent until the models were adjusted for BCS.

Immunohistochemical Expression of Neurokinin-A and Interleukin-8 in the Bronchial Epithelium of Horses with Severe Equine Asthma Syndrome during Asymptomatic, Exacerbation, and Remission Phase

Severe equine asthma (EA) syndrome is a chronic obstructive disease characterized by exaggerated contraction, inflammation, and structural alteration of the airways in adult horses, when exposed to airborne molds and particulate material. However, little is known about the relationship between the degree and type of inflammation on one hand, and the severity of the disease and the response to treatment on the other. Furthermore, to date, very few studies evaluate the diagnostic value of histology and immunohistochemical features of endoscopic biopsies on subjects with severe equine asthma. To investigate the expression of two inflammatory markers (NKA and IL-8) before, during, and after the exacerbation of severe EA, a histological and immunohistochemical study was carried out on a series of biopsy samples collected by bronchoscopy from six EA-affected horses subjected to process exacerbation through environmental stimuli and then to pharmacological treatment. The application of a histological biopsy scoring system revealed a significant difference between control cases and the EA-affected horses in all experimental phases (asymptomatic, early exacerbation phase, late exacerbation phase, and remission phase). For immunohistochemistry (IHC), only the intensity of NKA positivity increases significantly between control horses and the EA horses at late exacerbation and remission phases. In EA-affected horses, a difference was detected by comparing histology between asymptomatic and remission phase, meanwhile, NKA and IL-8 showed no differences between the experimental phases. Based on these results we can assert that: (1) The endoscopic biopsies generate reliable and homogeneous samples in the entire bronchial tree; (2) the clinical improvement associated with treatment is characterized by a significant worsening of the histological findings; and (3) the NKA immunopositivity seems to increase significantly rather than decrease, as one would have expected, after pharmacological treatment. Further studies are necessary both to implement the number of samples and to use other markers of inflammation to characterize the potential role of cytokines in the diagnosis and therapeutic approach of severe equine asthma.

Evaluation of Treatment With Respiratory Gene Technology and Serum in a Group of Standard Bred Racehorses With Cytological Evidence of Mild Equine Asthma

Alternative treatment options to glucocorticoids for equine asthma is desirable due to withdrawal time. The objective was to evaluate if serum and Respiratory Gene Technology (RGT), a commercial kit to produce autologous conditioned serum, was effective in reducing bronchoalveolar lavage (BAL) neutrophils and mast cells in racehorses with cytological evidence of mild equine asthma . Thirty-six Standardbred trotters in active training were enrolled in this randomized clinical trial; a healthy control group (n=11), a RGT group (n=12) and a serum group (n=13). Endoscopy including tracheal wash (TW) and BAL was performed before (T0), after a 6-week treatment period including 12 intramuscular injections of RGT or serum (T6) and as a follow-up 10 weeks after treatment (T16). A significant decrease in BAL neutrophils for the RGT group was found between T0 and T6 (P = .002, d=-1.51, CI: -2.43;-0.59) and for the serum group between T0-T6 (P = .002, d=-1.36, CI: -2.26;-0.46). Further, a significant decrease in BAL mast cells between T0-T6 for the both the RGT group (P = .019, d=-1.23, CI: -1.22;-0.34) and the serum group (P= .004, d=-0.81, CI: -1.65;0.04), and further between T0-T16 (RGT P= .011, d=-1.55, CI: -2.62;-0.48; serum P= .044, d=-0.65, CI: -1.68;-0.37). No significant difference in TW cytology was found for any of the time-points. Pro- and anti-inflammatory cytokines were regulated according to treatment. The control group showed no cytological differences between any time-point. Study results showed that intramuscular treatment with both RGT and serum was effective associated with reduction of BAL neutrophils and mast cells in horses with cytological evidence of mild equine asthma. Further large-scale studies are necessary.

Influence of Age and Immunostimulation on the Level of Toll-Like Receptor Gene (TLR3, 4, and 7) Expression in Foals

Simple Summary

Detailed knowledge of the molecular mechanisms of immunoglobulin synthesis appears necessary for a better understanding of foal immunity maturity and its influencing factors. At the same time, it encourages studies regarding the influence of the signaling cascade’s proteins on the primary immunological response, which provides an opportunity to develop extremely precise methods of regulating acquired immunity. The results revealed that the expression of theTLR3 and TLR4 genes, as well as the levels of immunoglobulins and interleukins, can be modulated by stimulation with the pharmacological agent, and that the expression of the TLR3 and TLR4genes in peripheral blood cells is dependent on age.

Abstract

The aim of this study was to investigate the molecular mechanisms leading to the identification of pathogens by congenital immune receptors in foals up to 60 days of age. The study was conducted on 16 foal Polish Pony Horses (Polish Konik) divided into two study groups: control (n = 9) and experimental (n = 7). Foals from the experimental group received an intramuscular duplicate injection of 5 mL of Biotropina (Biowet) at 35 and 40 days of age. The RNA isolated from venous blood was used to evaluate the expression of theTLR3, TLR4, and TLR7 genes using RT-PCR. The results of the experiment demonstrated a statistically significant increase in the level of TLR3 gene expression and a decrease in the level ofTLR4 gene expression with foal aging. The level of TLR7 gene expression did not show age dependence. Immunostimulation with Biotropina had a significant impact on the level of the genes’ expression for Toll-like receptors. It increased the level of TLR4 expression and decreased TLR3 expression. Thus, it was concluded that the expression of theTLR3 and TLR4genes in peripheral blood cells is dependent on age. This experiment demonstrated a strong negative correlation between TLR3 and TLR4 gene expression.

Age-related dynamics of pro-inflammatory cytokines in equine bronchoalveolar lavage (BAL) fluid and peripheral blood from horses managed on pasture

The objectives of this study were to evaluate the natural age-related variation and compare the level of pro-inflammatory cytokines in the peripheral blood and lower airways of horses. The mRNA expression of IL-1β, IL-6, IL-8 TNF-α TLR-4 in bronchoalveolar lavage (BAL) fluid and peripheral blood mononuclear cells (PBMC) were studied by quantitative real time polymerase chain reaction (PCR) and differential cell count cytology from 44 horses of different ages. A significant age-related increase was found for the mRNA expression of IL-6, IL-8, TLR-4 and TNF-α in stimulated BAL cells and for TNF-α in stimulated PBMC. Furthermore, a significant decrease was found in the mRNA expression of IL-1β and TNF-α in stimulated BAL cells compared to stimulated PBMC. In conclusion, continued low antigen exposure of horses in the pasture environment could lead to a tight regulation of mRNA gene expression in the airway space compared to the peripheral blood and favour an age-related accumulation of mRNA genes.

Tumor necrosis factor-alpha protein concentrations in bronchoalveolar lavage fluid from healthy horses and horses with severe equine asthma

The objective of this study was to determine if TNF-α protein concentration differs in bronchoalveolar lavage fluid (BALF) obtained from healthy horses, horses with naturally occurring exacerbations of severe equine asthma and horses in remission from severe equine asthma. Tumor necrosis factor-alpha (TNF- α) protein concentrations were determined in BALF by commercial equine ELISA. Horses with naturally occurring exacerbation of severe equine asthma were found to have significantly lower BALF TNF-α protein concentrations than healthy horses (p = 0.0026). There was no significant difference in BALF TNF-α concentration between horses in exacerbation and remission from disease, but there was a decrease in median TNF-α concentration between healthy horses and horses with clinical exacerbation of severe equine asthma. These findings suggest, that similar to human asthma, the role of TNF-α in chronic lower airway inflammation of horses may differ between disease phenotypes and disease state. Furthermore, the method with which TNF-α is measured (mRNA expression vs. protein concentration) may affect results when studying the role of TNF-α in horses with severe equine asthma.

Impaired Cell Cycle Regulation in a Natural Equine Model of Asthma

Recurrent airway obstruction (RAO) is a common and potentially debilitating lower airway disease in horses, which shares many similarities with human asthma. In susceptible horses RAO exacerbation is caused by environmental allergens and irritants present in hay dust. The objective of this study was the identification of genes and pathways involved in the pathology of RAO by global transcriptome analyses in stimulated peripheral blood mononuclear cells (PBMCs). We performed RNA-seq on PBMCs derived from 40 RAO affected and 45 control horses belonging to three cohorts of Warmblood horses: two half-sib families and one group of unrelated horses. PBMCs were stimulated with hay dust extract, lipopolysaccharides, a recombinant parasite antigen, or left unstimulated. The total dataset consisted of 561 individual samples. We detected significant differences in the expression profiles between RAO and control horses. Differential expression (DE) was most marked upon stimulation with hay dust extract. An important novel finding was a strong upregulation of CXCL13 together with many genes involved in cell cycle regulation in stimulated samples from RAO affected horses, in addition to changes in the expression of several HIF-1 transcription factor target genes. The RAO condition alters systemic changes observed as differential expression profiles of PBMCs. Those changes also depended on the cohort and stimulation of the samples and were dominated by genes involved in immune cell trafficking, development, and cell cycle regulation. Our findings indicate an important role of CXCL13, likely macrophage or Th17 derived, and the cell cycle regulator CDC20 in the immune response in RAO.

A review of the equine age-related changes in the immune system: comparisons between human and equine aging, with focus on lung-specific immune-aging

The equine aging process involves many changes to the immune system that may be related to genetics, the level of nutrition, the environment and/or an underlying subclinical disease. Geriatric horses defined as horses above the age of 20, exhibit a decline in body condition, muscle tone and general well-being. It is not known whether these changes contribute to decreased immune function or are the result of declining immune function. Geriatric years are characterized by increased susceptibility to infections and a reduced antibody response to vaccination as a result of changes in the immune system. Humans and horses share many of these age-related changes, with only a few differences. Thus, inflamm-aging and immunosenescence are well-described phenomena in both human and equine research, particularly in relation to the peripheral blood and especially the T-cell compartment. However, the lung is faced with unique challenges because of its constant interaction with the external environment and thus may not share similarities to peripheral blood when considering age-related changes in immune function. Indeed, recent studies have shown discrepancies in cytokine mRNA and protein expression between the peripheral blood and bronchoalveolar lavage immune cells. These results provide important evidence that age-related immune changes or 'dys-functions' are organ-specific.

Asthma "of horses and men"--how can equine heaves help us better understand human asthma immunopathology and its functional consequences?

Animal models have been studied to unravel etiological, immunopathological, and genetic attributes leading to asthma. However, while experiments in which the disease is artificially induced have helped discovering biological and molecular pathways leading to allergic airway inflammation, their contribution to the understanding of the causality of the disease has been more limited. Horses naturally suffer from an asthma-like condition called "heaves" which presents sticking similarities with human asthma. It is characterized by reversible airway obstruction, airway neutrophilic inflammation, and a predominant Th2 immune response. This model allows one to investigate the role of neutrophils in asthma, which remains contentious, the regulation of chronic neutrophilic inflammation, and their possible implication in pulmonary allergic responses. Furthermore, the pulmonary remodeling features in heaves closely resemble those of human asthma, which makes this model unique to investigate the kinetics, reversibility, as well as the physiological consequences of tissue remodeling. In conclusion, heaves and asthma share common clinical presentation and also important immunological and tissue remodeling features. This makes heaves an ideal model for the discovery of novel pathways implicated in the asthmatic inflammation and associated tissue remodeling.