Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany.
Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, FI-20520 Turku, Finland.
Toxins (Basel). 2021 Jul 11;13(7):480. doi: 10.3390/toxins13070480.
causes the severe childhood disease whooping cough, by releasing several toxins, including pertussis toxin (PT) as a major virulence factor. PT is an AB-type toxin, and consists of the enzymatic A-subunit PTS1 and five B-subunits, which facilitate binding to cells and transport of PTS1 into the cytosol. PTS1 ADP-ribosylates α-subunits of inhibitory G-proteins (Gαi) in the cytosol, which leads to disturbed cAMP signaling. Since PT is crucial for causing severe courses of disease, our aim is to identify new inhibitors against PT, to provide starting points for novel therapeutic approaches. Here, we investigated the effect of human antimicrobial peptides of the defensin family on PT. We demonstrated that PTS1 enzyme activity in vitro was inhibited by α-defensin-1 and -5, but not β-defensin-1. The amount of ADP-ribosylated Gαi was significantly reduced in PT-treated cells, in the presence of α-defensin-1 and -5. Moreover, both α-defensins decreased PT-mediated effects on cAMP signaling in the living cell-based interference in the Gαi-mediated signal transduction (iGIST) assay. Taken together, we identified the human peptides α-defensin-1 and -5 as inhibitors of PT activity, suggesting that these human peptides bear potential for developing novel therapeutic strategies against whooping cough.
百日咳博德特氏菌通过释放包括百日咳毒素（PT）在内的多种毒素引起严重的儿童疾病，PT 是一种 AB 型毒素，由酶 A 亚单位 PTS1 和五个 B 亚单位组成，有助于与细胞结合并将 PTS1 转运到细胞质中。PTS1 在细胞质中 ADP-ribosylates 抑制性 G 蛋白（Gαi）的α亚单位，导致 cAMP 信号转导紊乱。由于 PT 对于引起严重的疾病过程至关重要，我们的目标是确定针对 PT 的新型抑制剂，为新的治疗方法提供起点。在这里，我们研究了人防御素家族的抗菌肽对 PT 的影响。我们证明了 α-防御素-1 和 -5 在体外可抑制 PTS1 酶活性，但 β-防御素-1 则不行。在存在 α-防御素-1 和 -5 的情况下，PT 处理的细胞中 ADP-ribosylated Gαi 的量明显减少。此外，两种 α-防御素都降低了 PT 在活细胞基于干扰 Gαi 介导的信号转导（iGIST）测定中的 cAMP 信号转导中的介导作用。总之，我们鉴定出人肽α-防御素-1 和 -5 为 PT 活性的抑制剂，这表明这些人肽具有开发针对百日咳的新型治疗策略的潜力。
