Akhtar Marjahan, Nizam Nuder Nower, Basher Salima Raiyan, Hossain Lazina, Akter Sarmin, Bhuiyan Taufiqur Rahman, Qadri Firdausi, Lundgren Anna
Infectious Diseases Division, icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh.
Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.
Front Immunol. 2021 May 14;12:654872. doi: 10.3389/fimmu.2021.654872. eCollection 2021.
Enhancement of mucosal immune responses in children and infants using novel adjuvants such as double mutant heat labile toxin (dmLT) is an important goal in the enteric vaccine field. dmLT has been shown to enhance mucosal IgA responses to the oral inactivated enterotoxigenic (ETEC) vaccine ETVAX. dmLT can enhance IL-17A production from adult T cells, which may increase the production and secretion of mucosal IgA antibodies. However, the adjuvant mechanism remains to be fully elucidated and might differ between infants and adults due to age-related differences in the development of the immune system. The main objective of this study was to determine how dmLT influences antigen presenting cells and T cells from infants compared to adults, and the role of IL-1β for mediating the adjuvant activity. Peripheral blood mononuclear cells (PBMCs) from Bangladeshi infants (6-11 months) and adults (18-40 years) were stimulated with the mitogen phytohaemagglutinin (PHA), the superantigen Staphylococcal enterotoxin B (SEB), ETVAX whole cell component (WCC) or lipopolysaccharide (LPS) ± dmLT, and cytokine production was measured using ELISA and electrochemiluminescence assays. The adjuvant dmLT significantly enhanced SEB- and PHA-induced IL-17A, but not IFN-γ responses, in PBMCs from both infants and adults. Blocking experiments using an IL-1 receptor antagonist demonstrated the importance of IL-1 signaling for the adjuvant effect. dmLT, ETVAX WCC and LPS induced dose-dependent IL-1β responses of comparable magnitudes in infant and adult cells. Depletion experiments suggested that IL-1β was mainly produced by monocytes. dmLT enhanced IL-1β responses to low doses of WCC and LPS, and the adjuvant effect appeared over a wider dose-range of WCC in infants. dmLT and WCC also induced IL-6, IL-23 and IL-12p70 production in both age groups and dmLT tended to particularly enhance IL-23 responses to WCC. Our results show that dmLT can induce IL-1β as well as other cytokines, which in turn may enhance IL-17A and potentially modulate other immunological responses in both infants and adults. Thus, dmLT may have an important function in promoting immune responses to the ETVAX vaccine, as well as other whole cell- or LPS-based vaccines in infants in low- and middle-income countries.
使用新型佐剂如双突变热不稳定毒素（dmLT）增强儿童和婴儿的粘膜免疫反应是肠道疫苗领域的一个重要目标。已证明dmLT可增强对口服灭活产肠毒素大肠杆菌（ETEC）疫苗ETVAX的粘膜IgA反应。dmLT可增强成年T细胞产生IL-17A，这可能会增加粘膜IgA抗体的产生和分泌。然而，佐剂机制仍有待充分阐明，并且由于免疫系统发育的年龄相关差异，婴儿和成人之间可能有所不同。本研究的主要目的是确定与成人相比，dmLT如何影响婴儿的抗原呈递细胞和T细胞，以及IL-1β在介导佐剂活性中的作用。用丝裂原植物血凝素（PHA）、超抗原葡萄球菌肠毒素B（SEB）、ETVAX全细胞成分（WCC）或脂多糖（LPS）±dmLT刺激孟加拉国婴儿（6 - 11个月）和成人（18 - 40岁）的外周血单核细胞（PBMC），并使用ELISA和电化学发光测定法测量细胞因子的产生。佐剂dmLT显著增强了婴儿和成人PBMC中SEB和PHA诱导的IL-17A，但未增强IFN-γ反应。使用IL-1受体拮抗剂的阻断实验证明了IL-1信号传导对佐剂效应的重要性。dmLT、ETVAX WCC和LPS在婴儿和成人细胞中诱导了剂量依赖性的IL-1β反应，其幅度相当。耗竭实验表明IL-1β主要由单核细胞产生。dmLT增强了对低剂量WCC和LPS的IL-1β反应，并且在婴儿中，佐剂效应在更宽的WCC剂量范围内出现。dmLT和WCC还在两个年龄组中诱导了IL-6、IL-23和IL-12p70的产生，并且dmLT倾向于特别增强对WCC的IL-23反应。我们的结果表明，dmLT可诱导IL-1β以及其他细胞因子，这反过来可能增强IL-17A并潜在地调节婴儿和成人的其他免疫反应。因此，dmLT在促进对ETVAX疫苗以及低收入和中等收入国家婴儿中其他基于全细胞或LPS的疫苗的免疫反应方面可能具有重要作用。
