Asthma leaves traces in the horse’s blood – could this simplify future diagnostics?

Background

Asthma is one of the most common respiratory diseases in horses and can cause coughing, reduced performance and, in more severe cases, obvious breathing difficulties. Diagnosis currently relies largely on medical history, examination of the airways and analysis of cells collected through lung lavage. This type of sampling provides valuable information, but it is relatively invasive and requires both specialised equipment and expertise.

There is therefore considerable interest in developing simpler and less invasive methods that can provide information about the disease processes involved – for example through an ordinary blood sample. In the future, such methods could make it easier both to diagnose and to monitor horses with respiratory disease.

Searching for disease signals in the blood

In a new study, researchers at Uppsala University and the Swedish University of Agricultural Sciences have investigated so-called cell-free RNA (cfRNA) in blood plasma from both healthy horses and horses with asthma. By analysing these molecules, researchers can gain information about processes taking place in different parts of the body without having to collect samples directly from the affected tissue in the horse.

Results: Clear differences between healthy horses and horses with asthma

The researchers found clear differences in plasma cfRNA between horses with asthma and healthy horses. These differences were linked, among other things, to immune responses, tissue remodelling and cellular stress. One example was IL-33, a signalling molecule already strongly associated with asthma, which was markedly elevated in horses with the disease.

The results suggest that the method may capture other aspects of the disease process than RNA from circulating blood cells or immune cells collected through lung lavage – the latter being the more invasive method. This is particularly interesting because plasma can be obtained through a simple blood sample and could therefore offer a less invasive way of monitoring molecular changes in horses with respiratory problems.

The goal: Simpler diagnostics through an ordinary blood sample – with potential benefits for both horses and humans

In the longer term, the aim is to develop biomarkers that can be measured using an ordinary blood sample. This could reduce the need for more extensive sampling from the airways and make it easier to diagnose and monitor the disease over time, for example to assess disease progression or response to treatment.

This study is a first step, and larger studies are needed before plasma cfRNA can be used to diagnose individual horses. The next steps include investigating whether specific combinations of RNA molecules can distinguish healthy horses from horses with asthma and whether they can identify different forms of the disease.

Because equine asthma shares several biological and clinical features with asthma in humans, the research may also contribute to a better understanding of asthma in people.

Link to the study: