Comparative Lipidomics of Azole Sensitive and Resistant Clinical Isolates of Candida albicans Reveals Unexpected Diversity in Molecular Lipid Imprints

Although transcriptome and proteome approaches have been applied to determine the regulatory circuitry behind multidrug resistance (MDR) in Candida, its lipidome remains poorly characterized. Lipids do acclimatize to the development of MDR in Candida, but exactly how the acclimatization is achieved is poorly understood. In the present study, we have used a high-throughput mass spectrometry-based shotgun approach and analyzed the lipidome of genetically matched clinical azole-sensitive (AS) and -resistant (AR) isolates of C. albicans. By comparing the lipid profiling of matched isolates, we have identified major classes of lipids and determined more than 200 individual molecular lipid species among these major classes. The lipidome analysis has been statistically validated by principal component analysis. Although each AR isolate was similar with regard to displaying a high MIC to drugs, they had a distinct lipid imprint. There were some significant commonalities in the lipid profiles of these pairs, including molecular lipid species ranging from monounsaturated to polyunsaturated fatty acid-containing phosphoglycerides. Consistent fluctuation in phosphatidyl serine, mannosylinositolphosphorylceramides, and sterol esters levels indicated their compensatory role in maintaining lipid homeostasis among most AR isolates. Notably, overexpression of either CaCdr1p or CaMdr1p efflux pump proteins led to a different lipidomic response among AR isolates. This study clearly establishes the versatility of lipid metabolism in handling azole stress among various matched AR isolates. This comprehensive lipidomic approach will serve as a resource for assessing strategies aimed at disrupting the functions of Candida lipids, particularly the functional interactions between lipids and MDR determinants.

尽管转录组（transcriptome）与蛋白质组（proteome）方法已被用于解析念珠菌属多药耐药（multidrug resistance, MDR）背后的调控网络，但该菌的脂质组（lipidome）仍未得到充分表征。脂质确实会随着念珠菌多药耐药的形成而发生适应性改变，但这种适应性改变的具体机制仍不甚明晰。本研究采用基于高通量质谱的鸟枪法（shotgun）脂质组学分析策略，对遗传背景匹配的临床白色念珠菌（Candida albicans, C. albicans）唑类敏感（azole-sensitive, AS）与唑类耐药（azole-resistant, AR）分离株的脂质组进行了分析。通过比对这些匹配分离株的脂质谱，我们鉴定出了主要的脂质类别，并在这些类别中检测到200余种不同的分子脂质物种。本脂质组学分析已通过主成分分析（principal component analysis）完成统计学验证。尽管每一株AR分离株均表现出对唑类药物极高的最低抑菌浓度（minimum inhibitory concentration, MIC），但它们各自拥有独特的脂质特征谱。这些配对分离株的脂质谱存在部分显著共性，包括涵盖单不饱和脂肪酸至多不饱和脂肪酸的磷酸甘油酯（phosphoglycerides）类分子脂质物种。磷脂酰丝氨酸（phosphatidyl serine）、甘露糖基肌醇磷酸神经酰胺（mannosylinositolphosphorylceramides）以及甾醇酯（sterol esters）的水平呈现一致性波动，这表明它们在多数AR分离株中发挥着维持脂质稳态的代偿作用。值得注意的是，过表达CaCdr1p或CaMdr1p外排泵（efflux pump）蛋白，会在AR分离株中引发不同的脂质组学响应。本研究明确证实了脂质代谢在不同匹配AR分离株应对唑类药物胁迫时的多功能性。这种全面的脂质组学研究方法，将为靶向破坏念珠菌脂质功能、尤其是解析脂质与多药耐药决定因子之间功能互作的策略研究提供重要资源。