Circulating immune complexes and markers of systemic inflammation in RAO-affected horses

Abstract

The aim of this study was to investigate the levels of circulating immune complexes (CICs) and concentration of haptoglobin, fibrinogen and C-reactive protein in the serum of horses with recurrent airway obstruction and healthy controls. The study was conducted on a group of 14 adult Polish Konik horses, kept in uniform environmental and living conditions. Horses were divided into two groups: 7 horses were not affected by any respiratory problem (control group) and 7 horses had a history of recurrent airway obstruction (RAO) (study group). A clinical and laboratory evaluation, endoscopic examination and bronchoalveolar lavage (BAL) were performed in all horses. Levels of circulating immune complexes were significantly (p=0.0057) increased in heaves-affected horses compared to healthy controls (median [25 th -75 th percentiles]) (3.96 [3.96 -4.43] vs. 7.46 [5.13 -11.9]). No significant difference was observed in the levels of the examined acute phase proteins between the groups. Moreover, all results were within the reference range established for horses. The results of this study indicate that heaves in horses is associated with the formation and high level of CICs. Haptoglobin, fibrinogen and C-reactive protein failed as markers of early stage systemic inflammation in the course of RAO.

The Dynamics of Circulating Immune Complexes in Horses with Severe Equine Asthma

“…In 64% of patients, the value of CIC was elevated in both serum and synovial fluid [18]. In studies of severe equine asthma in Polish horses, a statistically higher concentration of circulating immune complexes was found in an asthma group compared to a healthy control group [20]. The lack of statistically significant differences between the groups in the present study may result from the diversity of the animals used.…”

“…Some studies concerned horse orthopaedics and foal diseases [18,19]. A preliminary study on the concentration of these complexes in horses with asthma was also published, and showed statistically higher values of CIC concentrations in sick horses compared to healthy ones [20]. These preliminary studies were carried out on a very homogeneous and normogenic group of horses, with uniform environmental conditions and in the permanent habitat of these animals.…”

Equine Asthma: Current Understanding and Future Directions

“…In humans, circulating immune complexes are detectable in a variety of systemic disorders such as autoimmune diseases, allergies and infectious diseases (169). High levels of circulating immune complexes have been reported in horses with severe EA (165). Another study found circulating immune complexes useful for differentiating healthy vs. severe EA, and monitoring corticosteroids therapy (170).…”

“…Inflammatory markers such as acute phase proteins and cytokines have been studied as markers of systemic inflammation. However, the available literature on markers of systemic inflammation in horses with severe EA is not well-characterized and controversial ( 116 , 163 – 165 ). Apart from reports on differential expression of cytokines during the course of severe EA, only a few acute phase proteins have been investigated.…”

Impact of Recurrent Airway Obstruction (RAO) on Selected Antioxidants in Horses

“…RAO occurs in horses aged seven years and over, and the incidence increases with age. Some authors considered the genetic background as a predisposing factor, which results from the fact that in some breeding lines RAO is frequently observed (2,3).…”