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environments or exposed to dust and allergens. It is characterised by airway inflammation (primarily driven by neutrophils) leading to symptoms such as coughing, nasal discharge, and laboured breathing. Inflammatory flare-ups can significantly impair lung function and reduce performance.
At the same time, equine obesity is becoming increasingly prevalent among domestic horses, largely due to overfeeding, limited exercise, and modern management practices. Obesity is already known to affect metabolic health and immune function in other species, including humans. This raises an important question: Could excess body fat make equine asthma worse by altering how the immune system responds to inflammation?
A research team led by Alejandro Albornoz at the Universidad Austral de Chile set out to investigate whether obesity influences the inflammatory profile of horses with equine asthma. Their study, published in the open-access journal Animals, focused specifically on neutrophils - the white blood cells central to the airway inflammation seen in asthmatic horses.
The researchers compared two groups of asthmatic horses that were in clinical remission (i.e. not experiencing active symptoms). The horses were divided into obese and non-obese groups, based on their body condition scores (BCS). Blood samples were taken to assess systemic inflammatory markers and to analyse how the horses’ neutrophils responded to immune challenges in the lab.
The results showed clear differences between the two groups:
- · Obese horses had significantly higher blood levels of interleukin-1β (IL-1β), a potent inflammatory cytokine involved in many immune responses.
- · They also had increased peripheral neutrophil counts, indicating a more active systemic inflammatory state.
When stimulated in the lab, neutrophils from obese horses:
- · Produced more reactive oxygen species, a marker of a strong oxidative response.
- · Showed greater expression of IL-1β genes after exposure to inflammatory triggers (such as lipopolysaccharide).
These responses point to a hyperinflammatory neutrophil phenotype - meaning these immune cells were more reactive and potentially more damaging to lung tissue if activated in the horse’s airways.
To better understand these changes, the team also conducted metabolomic profiling of the neutrophils - essentially examining the small molecules and biochemical pathways active within the cells.
They identified 139 different metabolites, and found key differences in:
- · Fatty acid biosynthesis
- · Branched-chain amino acid metabolism
- · Glutathione-related antioxidant pathways
- · Tricarboxylic acid (TCA) cycle intermediates
In particular, levels of itaconate, citraconic acid, and citrate were significantly elevated in the obese group. These molecules are known to regulate immune cell activity, and their presence suggests a state of metabolic reprogramming that primes neutrophils for a heightened inflammatory response.
The researchers conclude that obesity alters neutrophil metabolism and function in horses with asthma, making these immune cells more reactive to inflammatory stimuli. This may contribute to more persistent or severe airway inflammation, potentially making the disease harder to control.
The findings highlight the importance of addressing obesity as part of asthma management. Controlling body condition may reduce systemic inflammation and help prevent disease flare-ups. The study also opens the door to future therapies that target neutrophil metabolism as a way to modulate inflammation in chronic equine diseases.
For more details, see:
Albornoz, Alejandro, Beatriz Morales, Valentina Bernal Fernandez, Claudio Henriquez, John Quiroga, Pablo Alarcón, Gabriel Moran, and Rafael A. Burgos.
Obesity-associated metabolomic and functional reprogramming in neutrophils from horses with asthma
Animals (2025) 15, no. 13: 1992.
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