Humoral and cell-mediated immune responses to influenza vaccination in equine metabolic syndrome (EMS) horses.

This research investigates the impact of equine metabolic syndrome (EMS) on horses’ immune responses to influenza vaccination. The study suggests that while EMS doesn’t affect horses’ humoral (antibody-mediated) immune responses to the vaccine, it appears to reduce their cell-mediated immune responses.

Overview of the Research

• The focus of the research was on the immune responses of horses to influenza vaccinations, specifically in those having equine metabolic syndrome (EMS), a condition characterized by insulin dysregulation and obesity.
• The researchers postulated that horses with EMS may have altered responses to vaccines, mirroring observations in obese humans and mice that show decreased immune responses to vaccinations.
• If this holds true, it implies that EMS horses might be more prone to diseases, therefore acting as potential unknown disease reservoirs that can unwittingly propagate pathogens.

Methodology

• The research involved a total of 25 adult horses of mixed-gender and mixed-breed, aged between 8 to 21 years, with 13 of them having EMS and the remaining 12 non-EMS.
• Each group had 4 horses which served as non-vaccinated saline controls. The rest were given a commercially available equine influenza vaccine.
• Vaccination (influenza or saline) was administered at the start (week 0) and week 3. Blood samples were collected prior to the vaccination and on weeks 1, 2, 3, 4, and 5 post-vaccination.
• Blood samples were inspected to measure hemagglutination inhibition (HI) titers and influenza-specific antibody levels. The collected blood samples were also used to separate peripheral blood mononuclear cells for cell-mediated immune (CMI) responses analysis.

Findings

• All horses that received the influenza vaccination showed significant increases in HI titers, and IgGa and IgGb equine influenza specific antibodies compared to the saline controls, irrespective of whether they had EMS.
• Equine metabolic syndrome did not significantly influence the humoral immune responses as evaluated via HI titers or the levels of IgG antibody isotypes post-influenza vaccination.
• However, it was observed that the metabolic status did impact the cell-mediated immune responses. EMS horses that had been vaccinated with influenza showed reduced gene expression for IFN-γ and IL-2 compared to the vaccinated non-EMS control horses.
• From these results, it was concluded that while metabolic status does not affect humoral immune responses to influenza vaccination in horses, EMS does appear to hinder their cell-mediated immune responses.