Lactobacillus acidophilus and L. reuteri modulate cytokine responses in gnotobiotic pigs infected with human rotavirus

Probiotic lactic acid bacteria (LAB) have been shown to alleviate inflammation, enhance the immunogenicity of rotavirus vaccines, or reduce the severity of rotavirus diarrhoea. Although the mechanisms are not clear, the differential Th1/Th2/Th3-driving capacities and modulating effects on cytokine production of different LAB strains may be the key. Our goal was to delineate the influence of combining two probiotic strains L. acidophilus and L. reuteri on the development of cytokine responses in neonatal gnotobiotic pigs infected with human rotavirus (HRV). We demonstrated that HRV alone, or HRV plus LAB, but not LAB alone, initiated serum cytokine responses, as indicated by significantly higher concentrations of IFN-α, IFN-γ, IL-12, and IL-10 at post-inoculation day (PID) 2 in the HRV only and LAB+HRV+ pigs compared to LAB only and LAB-HRVpigs. Peak cytokine responses coincided with the peak of HRV replication. LAB further enhanced the Th1 and Th2 cytokine responses to HRV infection as indicated by significantly higher concentrations of IL-12, IFN-γ, IL-4 and IL-10 in the LAB+HRV+ pigs compared to the LAB-HRV+ pigs. The LAB+HRV+ pigs maintained relatively constant concentrations of TGF-β compared to the HRV only group which had a significant increase at PID 2 and decrease at PID 7, suggesting a regulatory role of LAB in maintaining gut homeostasis. At PID 28, cytokine secreting cell (CSC) responses, measured by ELISpot, showed increased Th1 (IL-12, IFN-γ) CSC numbers in the LAB+HRV+ and LAB-HRV+ groups compared to LAB only and LAB-HRVpigs, with significantly increased IL-12 CSCs in spleen and PBMCs and IFN-γ CSCs in spleen of the LAB+HRV+ group. Thus, HRV infection alone, but not LAB alone was effective in inducing cytokine responses but LAB significantly enhanced both Th1 and Th2 cytokines in HRV-infected pigs. LAB may also help to maintain immunological homeostasis during HRV infection by regulating TGF-β production. *Corresponding author: Lijuan Yuan. Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 Phone: (540)-231-9053. Fax: (540)-231-3426. lyuan@vt.edu. 1Current address: Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079. 2Current address: Department of Entomology, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, 44691. 3Current address: Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 4Current address: Division of Viral Pathogenesis, Beth Israel Deaconess Medical Center Viral Pathogenesis, Harvard Medical School, Boston MA 02215 5Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio, 44691 6Department of Food Science and Technology, College of Food, Agricultural and Environmental Sciences, The Ohio State University, Columbus, Ohio, 43210. NIH Public Access