Chen Ying-Lien, Brand Alexandra, Morrison Emma L, Silao Fitz Gerald S, Bigol Ursela G, Malbas Fedelino F, Nett Jeniel E, Andes David R, Solis Norma V, Filler Scott G, Averette Anna, Heitman Joseph
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
Eukaryot Cell. 2011 Jun;10(6):803-19. doi: 10.1128/EC.00310-10. Epub 2011 Apr 29.
Candida dubliniensis is an emerging pathogenic yeast species closely related to Candida albicans and frequently found colonizing or infecting the oral cavities of HIV/AIDS patients. Drug resistance during C. dubliniensis infection is common and constitutes a significant therapeutic challenge. The calcineurin inhibitor FK506 exhibits synergistic fungicidal activity with azoles or echinocandins in the fungal pathogens C. albicans, Cryptococcus neoformans, and Aspergillus fumigatus. In this study, we show that calcineurin is required for cell wall integrity and wild-type tolerance of C. dubliniensis to azoles and echinocandins; hence, these drugs are candidates for combination therapy with calcineurin inhibitors. In contrast to C. albicans, in which the roles of calcineurin and Crz1 in hyphal growth are unclear, here we show that calcineurin and Crz1 play a clearly demonstrable role in hyphal growth in response to nutrient limitation in C. dubliniensis. We further demonstrate that thigmotropism is controlled by Crz1, but not calcineurin, in C. dubliniensis. Similar to C. albicans, C. dubliniensis calcineurin enhances survival in serum. C. dubliniensis calcineurin and crz1/crz1 mutants exhibit attenuated virulence in a murine systemic infection model, likely attributable to defects in cell wall integrity, hyphal growth, and serum survival. Furthermore, we show that C. dubliniensis calcineurin mutants are unable to establish murine ocular infection or form biofilms in a rat denture model. That calcineurin is required for drug tolerance and virulence makes fungus-specific calcineurin inhibitors attractive candidates for combination therapy with azoles or echinocandins against emerging C. dubliniensis infections.
都柏林念珠菌是一种新出现的致病酵母菌种，与白色念珠菌密切相关，经常在HIV/AIDS患者的口腔中定殖或感染。都柏林念珠菌感染期间的耐药性很常见，构成了重大的治疗挑战。钙调神经磷酸酶抑制剂FK506在白色念珠菌、新型隐球菌和烟曲霉等真菌病原体中与唑类或棘白菌素表现出协同杀真菌活性。在本研究中，我们表明钙调神经磷酸酶是都柏林念珠菌细胞壁完整性以及对唑类和棘白菌素的野生型耐受性所必需的；因此，这些药物是与钙调神经磷酸酶抑制剂联合治疗的候选药物。与白色念珠菌不同，在白色念珠菌中钙调神经磷酸酶和Crz1在菌丝生长中的作用尚不清楚，而在这里我们表明钙调神经磷酸酶和Crz1在都柏林念珠菌对营养限制的菌丝生长中发挥着明显可证的作用。我们进一步证明，在都柏林念珠菌中，向触性受Crz1而非钙调神经磷酸酶控制。与白色念珠菌类似，都柏林念珠菌钙调神经磷酸酶可提高在血清中的存活率。都柏林念珠菌钙调神经磷酸酶和crz1/crz1突变体在小鼠全身感染模型中表现出毒力减弱，这可能归因于细胞壁完整性、菌丝生长和血清存活方面的缺陷。此外，我们表明都柏林念珠菌钙调神经磷酸酶突变体无法在大鼠假牙模型中建立小鼠眼部感染或形成生物膜。钙调神经磷酸酶是药物耐受性和毒力所必需的，这使得真菌特异性钙调神经磷酸酶抑制剂成为与唑类或棘白菌素联合治疗新出现的都柏林念珠菌感染的有吸引力的候选药物。
