Effects of a bacteria-based probiotic on subpopulations of peripheral leukocytes and their cytokine mRNA expression in calves

Abstract

Eight Holstein calves (10 ± 3 weeks) were used to examine the interaction between a bacteria-based probiotic agent (probiotic) and the function of peripheral blood mononuclear cells (PBMCs). The probiotic, consisting of Lactobacillus plantarum, Enterococcus faecium and Clostridium butyricum, was administered orally at 3.0 g/100 kg body weight to calves once daily for 5 consecutive days. Calves given the vehicle alone with no probiotic served as the control. In the treatment group, increases in numbers of CD282(+) (TLR2) monocytes, CD3(+) T cells and CD4(+), CD8(+) and WC1(+) γδ T cell subsets were noted on day 7 post-placement compared to predose day and the control group. Expression of interleukin (IL)-6, interferon-gamma (INF-γ) and tumor necrosis factor-alpha (TNF-α) was elevated in peripheral leukocytes on days 7 and 14. These results suggest that peripheral blood leukocytes in healthy calves may be stimulated via the gastrointestinal microbiota, which was increased by the oral probiotic treatment, with overall stability of the rumen bacterial flora. The 5-day repeated administration of a bacteria-based probiotic may enhance cellular immune function in weaned calves.

Fig.1.

Number of CD3, CD4, CD8, CD14, CD21 and WC1⁺ cells in the peripheral blood of calves given 3.0 g/100 kg BW of probiotic once daily for 5 consecutive days (black columns). Calves receiving the vehicle alone served as a control (white columns). Numbers were counted at predose (Pre) and on days 7 and 14. Values represent means ± SE (n=8). * Values in the treatment group compared to the predose day in the same group (P<0.05). # Values compared to the control on the same day (P<0.05). The first administration day of the probiotic was deemed day 1.

Fig. 2.

Number of TLR2⁺ (CD282) cells in the peripheral blood of calves given 3.0 g/100 kg BW of probiotic once daily for 5 consecutive days (black columns). Calves receiving the vehicle alone served as a control (white columns). Numbers were counted at predose (Pre) and on days 7 and 14. Values represent means ± SE (n=8). * Values in the treatment group compared to the predose day in the same group (P<0.05). # Values compared to the control on the same day (P<0.05). The first administration day of the probiotic was deemed day 1.

Fig. 3.

Relative mRNA expression of IL-6, IL-8, IFN-γ and TNF-α in peripheral leukocytes of calves given 3.0 g/100 kg BW of probiotic once daily for 5 consecutive days (black columns). Calves receiving the vehicle alone served as a control (white columns). Expression was measured at predose (Pre) and on days 7 and 14. Values represent means ± SE (n=8). * Values in the treatment group compared to the predose day in the same group (P<0.05). The first administration day of the probiotic was deemed day 1.