Orally administered β-glucan improves the hemolytic activity of the complement system in horses

Abstract

Background and Aim: Immune-modulating molecules mainly act on innate immune cells, which are central to early defense against invading pathogens and contribute to developing adaptive immunity. Yeast-extracted β-glucan, a model immune-modulating molecule, is widely used in several animal species; however, its effect on horse immune parameters has not been thoroughly investigated yet. This study aimed to evaluate the effects of orally administered β-glucan on selected innate immune parameters in horses. Materials and Methods: Eighteen thoroughbred horses were assigned equally into three groups as follows: One control group (no β-glucan) and two β-glucan experimental groups (one received 125 mg and the other 2 g of β-glucan per day for 28 days). Blood samples were collected before and at the end of the experiment for hematological analysis, whole blood phagocytosis, respiratory burst assays, and to assess the serum lysozyme and complement hemolytic activities. Results: At the end of the experiment, significant decreases (p<0.05) in monocyte numbers were observed in the control horses (258.8±45.9 vs. 115.3±41.5) and in those fed 125 mg/day of β-glucan (208.8±72.3 vs. 99.2±60.7), whereas a significant increase in numbers was noted in the horses that were fed 2 g/day of β-glucan (303.5±45.8 vs. 429.8±86.0; p<0.05). The natural hemolytic activity of the complement was higher only in horses fed 2 g/day of β-glucan (p=0.018) compared to the other groups. The hemolytic activity in the classical pathway was higher in those fed 125 mg/day (p=0.0035) and 2 g/day of β-glucan (p=0.0001). Conclusion: β-glucan improves important innate immune parameters and might be fed to horses before stressful events.

Primäre Immunschwächeerkrankungen des Pferdes mit Schwerpunkt auf der Common Variable Immunodeficiency (CVID) beim adulten Pferd

“…pattern recognition receptors (PRRs) die PAMPs (pathogen-associated molecular patterns), wie z. B. unmethylierte CpG-Motive bei Propionibacterium-acnes-Extrakt [18] oder aus Hefe gewonnenes β-Glucan [19,20], wobei es nach Aktivierung der antigen-präsentierenden Zellen in der Folge zur Zytokinexpression, z. B. IL-2 kommt [18].…”

“…B. IL-2 kommt [18]. Aber auch positive Effekte auf die Phagozytosekapazität, sowohl für neutrophile Granulozyten als auch Makophagen und positive Auswirkungen auf die Antikörperproduktion durch B-Zellen werden dem β-Glucan nachgesagt [19]. Inaktiviertes Parapoxvirus ovis (Zylexis) induziert immunmodulatorische Proteine, so werden GM-CSF, IL-2 exprimiert, aber auch antigen-präsentierende Zellen aktiviert und so inflammatorische Zytokine hochreguliert [18].…”