Wooding Madelien, Dodgen Tyren, Rohwer Egmont R, Naudé Yvette
Department of Chemistry, University of Pretoria, Pretoria, South Africa.
Waters Corporation, Rydalmere, NSW, Australia.
J Mass Spectrom. 2021 Feb;56(2):e4686. doi: 10.1002/jms.4686.
Human skin surface chemical cues comprise a complex mixture of compounds that mosquitoes use to locate and select their human host, based on inter- and intra-human variation in chemical profiles. The complexity of the skin surface matrix calls for advanced analytical techniques to enable separation and identification of biomarkers, which may be used as topical attractants and repellants in future mosquito vector control programmes. The perceived mosquito attractiveness between 20 volunteers and the preference of mosquitoes to bite certain regions, namely, ankle versus wrist, of the human host were investigated in this study, by comparing skin surface chemical profiles. Ion mobility was combined with high resolution mass spectrometry to provide additional confidence in biological marker discovery and identification of human skin surface compounds. This study employed a non-intrusive sampling scheme using a polydimethylsiloxane (PDMS) sampler and solvent desorption analysed with ultra-performance liquid chromatography with ion mobility high-resolution mass spectrometry (UPLC-IMS-HRMS). Statistical approaches guided the identification of 14 biological markers discerning difference in perceived mosquito attractiveness and 20 biomarkers associated with the different skin regions sampled. A broad range (m/z 96.0437 to 788.6095) of chemical compounds was detected from a variety of classes (including sugars, steroids, fatty acids, peptides and peptide derivatives, and compounds of food origin). Ten compounds were unequivocally identified on the human skin surface, and caffeine was reported on the human skin surface for the first time. Furthermore, 77 compounds, of which 64 to the authors' knowledge have not previously been reported, were detected on the human skin surface using accurate mass, collision cross section (CCS) values and fragmentation patterns. This approach enabled comprehensive human skin surface chemical profiling and provides an extensive list of tentatively identified skin surface compounds together with accurate mass values and adducts with their corresponding CCS values.
人类皮肤表面的化学线索是由多种化合物组成的复杂混合物，蚊子会根据人类个体间和个体内化学特征的差异，利用这些化合物来定位和选择人类宿主。皮肤表面基质的复杂性需要先进的分析技术来分离和鉴定生物标志物，这些生物标志物未来可能会用作蚊虫媒介控制计划中的局部引诱剂和驱避剂。本研究通过比较皮肤表面化学特征，调查了20名志愿者对蚊子的吸引力以及蚊子叮咬人类宿主特定部位（即脚踝与手腕）的偏好。离子淌度与高分辨率质谱联用，为生物标志物的发现和人类皮肤表面化合物的鉴定提供了更高的可信度。本研究采用了一种非侵入性采样方案，使用聚二甲基硅氧烷（PDMS）采样器，并通过超高效液相色谱与离子淌度高分辨率质谱联用（UPLC-IMS-HRMS）对溶剂解吸进行分析。统计方法指导鉴定出14种区分感知蚊子吸引力差异的生物标志物，以及20种与所采样的不同皮肤区域相关的生物标志物。从多种类别（包括糖类、类固醇、脂肪酸、肽类和肽衍生物以及食物来源的化合物）中检测到了范围广泛（m/z 96.0437至788.6095）的化合物。在人类皮肤表面明确鉴定出了10种化合物，并且首次在人类皮肤表面报道了咖啡因。此外，利用精确质量、碰撞截面（CCS）值和碎片模式，在人类皮肤表面检测到了77种化合物，据作者所知，其中64种此前未曾报道过。这种方法实现了对人类皮肤表面化学特征的全面分析，并提供了一份初步鉴定的皮肤表面化合物的详细清单，以及它们的精确质量值、加合物及其相应的CCS值。
