Institute of Biophysics of the Czech Academy of Sciences, Brno 612 65, Czech Republic; International Clinical Research Center, St. Anne's University Hospital, Brno 656 91, Czech Republic.
Institute of Biophysics of the Czech Academy of Sciences, Brno 612 65, Czech Republic; Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno 625 00, Czech Republic.
Phytomedicine. 2020 Apr;69:153194. doi: 10.1016/j.phymed.2020.153194. Epub 2020 Feb 22.
The frequency of allergic diseases is constantly rising. Dysregulated production of isotype E immunoglobulins is one of the key factors behind allergic reactions and its modulation is therefore an important target for pharmacological intervention. Natural products of the pseurotin family were reported to be inhibitors of IgE production in B-cells. Mechanistic details underlying these effects are however not well understood.
In the present study, we synthesized new analogs of natural pseurotins and extensively investigated their inhibitory effects on activation, proliferation and differentiation of B-cells, as well as on the production of IgE.
Effects of two natural pseurotins (pseurotins A and D) and a collection of fully synthetic pseurotin analogs were studied on mouse B-cells stimulated by the combination of IL-4 and E. coli lipopolysaccharide. The IgE production was determined along with cell viability and cell proliferation. The phosphorylation of selected members of the STAT transcription factor family was subsequently investigated. Finally, the in vivo effect of pseurotin D on the ovalbumin-induced delayed type hypersensitivity response was tested in mice.
We discovered that several fully synthetic pseurotin analogs were able to decrease the production of IgE in stimulated B-cells with potency comparable to that of pseurotins A and D. We found that the two natural pseurotins and the active synthetic analogs inhibited the phosphorylation of STAT3, STAT5 and STAT6 proteins in stimulated B-cells, resulting in the inhibition of B-cell proliferation and differentiation into the plasma cells. In vivo, pseurotin D decreased ovalbumin-induced foot pad edema.
Our results advance the current mechanistic understanding of the pseurotin-induced inhibition of IgE production in B-cells by linking the effect to STAT signaling, and associated modulation of B-cell proliferation and differentiation. Together with our finding that structurally simpler pseurotin analogs were able to reproduce the effects of natural pseurotins, the presented work has implications for the future research on these secondary metabolites in the context of allergic diseases.
过敏性疾病的发病率不断上升。免疫球蛋白 E 同种型的失调产生是过敏反应的关键因素之一，因此其调节是药物干预的重要目标。报道称， pseurotin 家族的天然产物是 B 细胞中 IgE 产生的抑制剂。然而，这些作用的机制细节尚不清楚。
在本研究中，我们合成了天然 pseurotin 的新类似物，并广泛研究了它们对 B 细胞激活、增殖和分化以及 IgE 产生的抑制作用。
研究了两种天然 pseurotin（pseurotin A 和 D）和一系列完全合成的 pseurotin 类似物对 IL-4 和大肠杆菌脂多糖刺激的小鼠 B 细胞的影响。同时测定 IgE 产生、细胞活力和细胞增殖。随后研究了选择的 STAT 转录因子家族成员的磷酸化情况。最后，在小鼠中测试了 pseurotin D 对卵清蛋白诱导的迟发型超敏反应的体内作用。
我们发现，几种完全合成的 pseurotin 类似物能够降低刺激的 B 细胞中 IgE 的产生，其效力与 pseurotin A 和 D 相当。我们发现，两种天然 pseurotin 和活性合成类似物抑制了刺激的 B 细胞中 STAT3、STAT5 和 STAT6 蛋白的磷酸化，从而抑制了 B 细胞的增殖和向浆细胞的分化。体内，pseurotin D 可降低卵清蛋白诱导的足垫水肿。
我们的结果通过将效应与 STAT 信号转导相关联，以及与 B 细胞增殖和分化的相关调节，推进了 pseurotin 诱导的 B 细胞 IgE 产生抑制的机制理解。同时，我们发现结构更简单的 pseurotin 类似物能够再现天然 pseurotin 的作用，这为今后在过敏性疾病背景下对这些次生代谢物的研究提供了依据。
