Researchers have found that a particular protein found in the intestine is upregulated in chronic cases of laminitis, strengthening that case that chronic inflammation of the laminae in the hoof might be associated with changes in the endocrine and immune systems.
Texas A&M University researchers Samantha Steelman and Bhanu Chowdhary, writing in the journal BMC Veterinary Research, used Difference Gel Electrophoresis (DIGE) to assess global differences in the plasma proteome between horses with chronic laminitis and controls.
DIGE is a gel‐based technique for relative protein quantification in complex protein samples.
They found that a number of proteins involved in immune regulation were differentially expressed in horses with chronic equine laminitis.
In particular, the anti-inflammatory protein APOA-IV was elevated around two-fold in foundered horses.
APOA-IV is produced by the small intestine, particularly in response to the ingestion of triglycerides.
In this way, it functions to tell the animal when its appetite has been satisfied, but is also known to have anti-oxidant and anti-inflammatory properties.
“The tissue sources and physiological functions of APOA-IV have yet to be explored in horses,” the pair noted.
“Evidence exists, however, that serum APOA-IV levels are influenced by the gastrointestinal microflora in mice, which, like horses, are hindgut fermenters.
“Preliminary data from our laboratory suggest that the composition of fecal microflora is altered in horses with chronic laminitis as compared with controls, thus providing a possible explanation for the elevation of APOA-IV seen in the present study.
“The underlying mechanism is currently unknown, although the composition of the hindgut microflora play an important role in the development of acute laminitis and could possibly contribute to exacerbation of symptoms in chronic laminitis as well,” they said.
“Our results suggest that chronic inflammation of the laminae of the hoof might be associated with system-wide changes in immune function, particularly in the gastrointestinal system, and that this hypothesis warrants further investigation.
“Gastrointestinal inflammation has been implicated in the development of acute laminitis but has not previously been associated with chronic laminitis,” they noted.
Chronic equine laminitis, they report, is linked with specific changes in the plasma proteome of horses, which might be reflective of alterations in the immune system that are not confined to the foot.
“Specifically, the altered abundance of complement proteins and acute phase reactants suggests a chronic activation of the innate immune response.”
They said their results provided a base upon which to build future studies with the goal of reducing inflammation and easing the pain associated with laminitis.
Plasma proteomics shows an elevation of the anti-inflammatory protein APOA-IV in chronic equine laminitis
Samantha M Steelman and Bhanu P Chowdhary
BMC Veterinary Research 2012 8:179 https://doi.org/10.1186/1746-6148-8-179