The effect of selenium supplementation on vaccination response and immune function in adult horses1

Abstract

Selenium status has been reported to affect immune function across many different species. Yet few studies have focused on the effect of Se status on the equine immune system. This study examined the effect of Se supplementation on vaccination response and immune function in mature horses. Twenty-eight horses were blocked by age and sex and were randomly allocated to 1 of 4 dietary treatment groups: low Se (LS), adequate Se (AS), Se-yeast (SP), and sodium selenite (SS). For 35 wk, horses allocated to LS, SP, and SS received a low-Se diet (0.06 mg/kg DM) with the intention to lower Se stores, whereas AS received an adequate Se diet (0.12 mg/kg DM). A 29-wk repletion phase was as follows: LS and AS were kept on the diets fed during the depletion period, whereas SP and SS received the depletion diet plus their respective Se supplements to achieve a dietary Se concentration of 0.3 mg/kg DM. The Se status of the horses was monitored using whole blood Se and glutathione peroxidase (GSH-Px) activity as indicators. At wk 22 and 25 of the repletion phase, horses were vaccinated intramuscularly with 10 mg ovalbumin (OVA). Horses were also vaccinated against equine influenza at wk 25. Blood samples were collected for 7 wk after initial vaccination for serum separation and at 0, 3, and 5 wk postvaccination for peripheral blood mononuclear cell (PBMC) isolation and whole blood cytokine mRNA evaluation. At wk 22 of the repletion phase, both Se and GSH-Px were greater for SP and SS compared with AS and LS (P < 0.001). Serum vitamin E was similar between treatments. Response to OVA vaccination, evaluated as OVA-specific IgG production, cytokine mRNA expression of PBMC stimulated with OVA in vitro, and lymphocyte proliferation, was unaffected by Se status. Similarly, memory response to the influenza vaccine was not affected by Se status. However, decreased mRNA expression of selected cytokines was observed in PBMC stimulated with phorbol 12-myristate 13-acetate for LS compared with AS, SP, and SS (P < 0.05). Whole blood mRNA expression of IL-10 was greater for SS compared with LS, AS, and SP (P = 0.043). Although the OVA and influenza vaccination responses were unaffected by Se status, other measures of immune function did indicate that low Se status could adversely affect cell-mediated immunity.

Influence of specific management practices on blood selenium, vitamin E, and beta‐carotene concentrations in horses and risk of nutritional deficiency

“…Selenium deficiency consistently has been associated with skeletal and cardiac muscle damage, and inadequate alpha‐tocopherol status has been linked to degenerative myeloencephalopathy and neuroaxonal dystrophy, motor neuron disease, and vitamin E‐deficient myopathy in horses 1‐3 . In addition, supplementation of horses with these antioxidants has been correlated with attenuation of oxidative stress markers and positive effects on fertility and immune function 4‐7 …”

Relationship between selenium status, selenoproteins and COVID-19 and other inflammatory diseases: A critical review

“… in vitro Aziz; Klesius [80] Horses - Suppressed cell-mediated immunity, associated with lowered GPX activity. in vitro / in vivo Brummer et al [81] Pigs - Decreases the levels of selenoenzymes, selenoproteins, IL-2 and INF-γ. in vitro Yang et al [82] Humans - Decreases phagocytic function and cytotoxicity of immune system cells.…”

“…In contrast, Se-deficiency has been linked with decreased production of leukotriene B4, which is an important chemoattractant involved in leucocyte activation [79] , [80] , [95] . In various mammalian species (goats, cows, horses, and mice), Se-deficiency has been associated with impaired synthesis or release of migration factors by leukocytes, neutrophils, and macrophages [73] , [79] , [80] , [81] , [82] , [96] . Consequently, Se-deficiency can impair leukocyte activation, differentiation, migration and adhesion to infected tissues; however, whether this represents an indirect response to redox unbalance caused by disruption of antioxidant selenoproteins synthesis is presently unclear.…”

Antibody response to Influenza booster vaccination in Franches‐Montagnes stallions supplemented with Equi‐Strath®: a randomized trial

“…Knight & Tyznik (1990) observed a higher antibody response in vitamin E supplemented ponies challenged with packed sheep red blood cells intramuscularly compared to ponies supplemented with low levels of vitamin E. However, there are also reports with dietary supplements that show unaffected influenza vaccination responses (Brummer et al . 2013) or decreasing immunoglobulin concentrations in response to vaccination (Koke et al . 2015).…”