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Dietary yeast beta 1,3/1,6 glucan supplemented to adult Labrador Retrievers alters peripheral blood immune cell responses to vaccination challenge without affecting protective immunity

2023; Oxford University Press; Volume: 101; Linguagem: Inglês

10.1093/jas/skad029

1544-7847

K. Fries-Craft, Logan R. Kilburn-Kappeler, Charles G Aldrich, Elizabeth Bobeck,

Veterinary Oncology Research

Yeast-derived 1,3/1,6 β-glucans may alter host immunity to produce robust and quickly resolved responses that align with companion animal health goals. In adult dogs, immunomodulation by yeast 1,3/1,6 β-glucans in extruded kibble diet have not been well documented. The study objective was to evaluate systemic immune responses in dogs fed kibble diets with two yeast 1,3/1,6 β-glucans doses before and after vaccine challenge. Twenty-four adult Labrador Retrievers were assigned to three dietary treatments consisting of a basal diet (control) supplemented with 0.012% or 0.023% (0.5 or 1×, respectively) yeast 1,3/1,6 β-glucan with equal sex representation within each treatment (8 dogs/diet). Animals were fed experimental diets for a 29-d acclimation period, after which baseline blood samples were collected before administration of a combination canine distemper virus, parvovirus, and adenovirus-2 vaccine. Blood samples were collected weekly for 21 d following vaccination with whole blood for CBC analysis, serum for titer and cytokine assays, and peripheral blood mononuclear cells (PBMC) isolated for flow cytometric immune cell profiling. Data were analyzed using the MIXED procedure with diet and timepoint fixed effects. Serum titer was analyzed by Kruskal-Wallis test (SAS 9.4; P ≤ 0.05). Prior to vaccination, β-glucan diets did not affect serum cytokines, antibody titer, or immune cell populations. In the first 7 d post-vaccination (dpv), PBMC CD21low B cells increased 36.5% to 58.1% in all groups but the magnitude of change was lesser in the 0.5× β-glucan diet resulting in 25.6% lower CD21low populations compared to control-fed dogs (P = 0.007). By 21 dpv, B-cell populations recovered to baseline levels in dogs fed 1× β-glucan, but CD21high cells remained elevated 50.5% in dogs fed 0.5× β-glucan diets compared with baseline (P < 0.0001). While no differences in serum titer or cytokines were observed, feeding both β-glucan diets maintained stable blood monocytes, whereas a 53.0% decrease between baseline and 14 dpv was observed in control-fed dogs (P = 0.01). Collectively, these outcomes suggest that a 1× dose of 1,3/1,6 yeast β-glucan in extruded kibble diets altered monocytes associated with trained immunity, did not reduce PBMC CD21low B-cell responsiveness, and simultaneously contributed to B-cell population resolution by 21 dpv in adult dogs. Additional research to assess the functionality of these changes is needed.Companion animal food trends reflect the growing demand for healthy, functional foods. Yeast-derived β-glucans have been shown to train the human immune system to respond and resolve inflammation quickly, which aligns with companion animal health goals of providing disease protection without excessive inflammation. In this work, 24 healthy adult Labrador Retrievers were fed diets without or with yeast β-glucans at two doses (0.5 and 1×). After feeding experimental diets for 4 wk, blood samples were collected to establish baseline immunity before dogs were challenged with a commercially available vaccine. Blood samples were collected weekly for 3 wk post-vaccination to determine changes, if any, to serum antibody, cytokine production, and blood counts. All dogs achieved protective antibody titers within 1 wk post-vaccination. Dogs fed the 1× β-glucans inclusion showed potentially reduced reliance on cells associated with early immune responses without prolonging responses by antibody-producing cells. These outcomes suggest beneficial responses to dietary yeast β-glucans in vaccinated adult Labrador Retrievers, but further research and refinement of immunological assessment in companion animals are needed.