Toll-like Receptor-Mediated Immunomodulation of Th1-Type Response Stimulated by Recombinant Antigen of Type 2 Porcine Reproductive and Respiratory Syndrome Virus (PRRSV-2)

Rika Wahyuningtyas; Mei-Li Wu; Wen-Bin Chung; Hso-Chi Chaung; Ko-Tung Chang

doi:10.3390/v15030775

Toll-like Receptor-Mediated Immunomodulation of Th1-Type Response Stimulated by Recombinant Antigen of Type 2 Porcine Reproductive and Respiratory Syndrome Virus (PRRSV-2)

Viruses. 2023 Mar 17;15(3):775. doi: 10.3390/v15030775.

Authors

Rika Wahyuningtyas^{1

2}, Mei-Li Wu^{1

3}, Wen-Bin Chung^{1

2}, Hso-Chi Chaung^{1

2

4}, Ko-Tung Chang^{1

4

5}

Affiliations

¹ Research Centre for Animal Biologics, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
² Department of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
³ Department of Food Science, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
⁴ Flow Cytometry Center, Precision Instruments Center, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
⁵ Department of Biological Science and Technology, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.

Abstract

PRRSV infects CD163-positive macrophages and skews their polarization toward an M2 phenotype, followed by T-cell inactivation. In our previous study, we found that recombinant protein A1 antigen derived from PRRSV-2 was a potential vaccine or adjuvant for immunization against PRRSV-2 infection due to its ability to repolarize macrophages into M1 subtype, thereby reducing CD163 expression for viral entry and promoting immunomodulation for Th1-type responses, except for stimulating Toll-like receptor (TLR) activation. The aim of our current study was to evaluate the effects of another two recombinant antigens, A3 (ORF6L5) and A4 (NLNsp10L11), for their ability to trigger innate immune responses including TLR activation. We isolated pulmonary alveolar macrophages (PAMs) from 8- to 12-week-old specific pathogen free (SPF) piglets and stimulated them with PRRSV (0.01 MOI and 0.05 MOI) or antigens. We also investigated the T-cell differentiation by immunological synapse activation of PAMs and CD4⁺ T-cells in the cocultured system. To confirm the infection of PRRSV in PAMs, we checked the expression of TLR3, 7, 8, and 9. Our results showed that the expression of TLR3, 7, and 9 were significantly upregulated in PAMs by A3 antigen induction, similar to the extent of PRRSV infection. Gene profile results showed that A3 repolarizes macrophages into the M1 subtype potently, in parallel with A1, as indicated by significant upregulation of proinflammatory genes (TNF-α, IL-6, IL-1β and IL-12). Upon immunological synapse activation, A3 potentially differentiated CD4 T cells into Th1 cells, determined by the expression of IL-12 and IFN-γ secretion. On the contrary, antigen A4 promoted regulatory T cell (T-reg) differentiation by significant upregulation of IL-10 expression. Finally, we concluded that the PRRSV-2 recombinant protein A3 provided better protection against PRRSV infection, suggested by its capability to reeducate immunosuppressive M2 macrophages into proinflammatory M1 cells. As M1 macrophages are prone to be functional antigen-presenting cells (APCs), they can call for TLR activation and Th1-type immune response within the immunological synapse.

Keywords: M1; M2; Toll-like receptors; porcine alveolar macrophages; porcine reproductive and respiratory syndrome virus.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Immunity, Innate
Immunomodulation
Interleukin-12
Porcine Reproductive and Respiratory Syndrome*
Porcine respiratory and reproductive syndrome virus* / genetics
Recombinant Proteins / genetics
Swine
Toll-Like Receptor 3
Toll-Like Receptors

Substances

Toll-Like Receptor 3
Toll-Like Receptors
Interleukin-12
Recombinant Proteins

Grants and funding

This study was financially supported by the Research Center for Animal Biologics, from the Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education and the Ministry of Science and Technology (MOST 107-3017-F-020-001-, MOST 108-3017-F-020-001-, MOST 109-2634-F-020-001-, MOST 110-2634-F-020-001-, MOST 109-2314-B-020-002, MOST 110-2314-B-020-003), Taiwan.