Precise immunological evaluation rationalizes the design of a self-adjuvanting vaccine composed of glycan antigen, TLR1/2 ligand, and T-helper cell epitope

Tsung-Che Chang; Yoshiyuki Manabe; Keita Ito; Ryuku Yamamoto; Kazuya Kabayama; Shino Ohshima; Yoshie Kametani; Yukari Fujimoto; Chun-Cheng Lin; Koichi Fukase

doi:10.1039/d2ra03286d

Precise immunological evaluation rationalizes the design of a self-adjuvanting vaccine composed of glycan antigen, TLR1/2 ligand, and T-helper cell epitope

RSC Adv. 2022 Jun 29;12(29):18985-18993. doi: 10.1039/d2ra03286d. eCollection 2022 Jun 22.

Authors

Tsung-Che Chang¹, Yoshiyuki Manabe^{1

2}, Keita Ito¹, Ryuku Yamamoto¹, Kazuya Kabayama^{1

2}, Shino Ohshima³, Yoshie Kametani³, Yukari Fujimoto⁴, Chun-Cheng Lin⁵, Koichi Fukase^{1

2}

Affiliations

¹ Department of Chemistry, Graduate School of Science, Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan Koichi@chem.sci.osaka-u.ac.jp.
² Forefront Research Center, Osaka University 1-1 Machikaneyama Toyonaka Osaka 560-0043 Japan.
³ Faculty of Medicine, School of Medicine, Tokai University 143 Shimokasuya Isehara-shi Kanagawa 259-1193 Japan.
⁴ Department of Chemistry, Faculty of Science and Technology, Keio University 3-14-1 Hiyoshi, Kohoku-ku Yokohama Kanagawa 223-8522 Japan.
⁵ Department of Chemistry, National Tsing Hua University 101 Sec. 2, Kuang Fu Rd. Hsinchu 30013 Taiwan.

Abstract

Sialyl-Tn (STn), overexpressed on various tumors, has been investigated for its application in anti-cancer vaccine therapy. However, Theratope, an STn-based vaccine, failed in the phase III clinical trial due to poor immunogenicity and epitope suppression by the foreign carrier protein. We therefore developed a self-adjuvanting STn based-vaccine, a conjugate of clustered STn (triSTn) antigen, TLR1/2 ligand (Pam₃CSK₄), and T-helper (Th) cell epitope, and found that this three-component self-adjuvanting vaccine effectively resulted in the production of anti-triSTn IgG antibodies. We herein analyzed immune responses induced by this self-adjuvanting vaccine in detail. We newly synthesized two-component vaccines, i.e., Pam₃CSK₄- or Th epitope-conjugated triSTn, as references to evaluate the immune-stimulating functions of Pam₃CSK₄ and Th epitope. Immunological evaluation of the synthesized vaccine candidates revealed that Pam₃CSK₄ was essential for antibody production, indicating that the uptake of triSTn antigen by antigen-presenting cells (APCs) was promoted by the recognition of Pam₃CSK₄ by TLR1/2. The function of the Th epitope was also confirmed. Th cell activation was important for boosting antibody production and IgG subclass switching. Furthermore, flow cytometric analyses of immune cells, including T cells, B cells, dendritic cells, and other monocytes, were first employed in the evaluation of self-adjuvanting vaccines and revealed that the three-component vaccine was able to induce antigen-specific immune responses for efficient antibody production without excessive inflammatory responses. Importantly, the co-administration of Freund's adjuvants was suggested to cause excessive myeloid cell accumulation and decreased plasma cell differentiation. These results demonstrate that vaccines can be designed to achieve the desired immune responses via the bottom-up construction of each immune element.