More than 70% of women will experience candida infections once or more in their lifetime. About 5% to 10% of patients may experience recurrent vulvovaginal candidiasis (RVVC). Candida albicans is the main pathogen of candidiasis. It is a unicellular eukaryote with two major morphological forms during infection: yeast and hypha. The morphological form of pseudohyphae only occurs when it is gemmating. Usually, the yeast form exists in oral mucosa, gastrointestinal tract, anus, skin and vagina in healthy individuals, as a commensal organism without pathogenicity. When the individuals are in pathological condition such as suffering from cancer, diabetes and hematologic diseases or local and systemic hypoimmunity, the fungus behaves as a powerful pathogen to cause a disease. Previous studies have shown that the yeast-to-hypha transformation of C. albicans was the critical step of infection, but the pathogenic mechanism had not yet been clearly elucidated.
The genomic sequence of C. albicans has been completely annotated, it is helpful for us to study the pathogenic mechanism of C. albicans at the gene level. The vagina is the most common infection site of this microorganism, however, no studies have ever simulated the infection of C. albicans in female genital tract, thus, we still don’t clearly understand the pathogenesis of candidiasis in this site. In order to explore the pathogenic mechanism of infection, we co-cultured HeLa cells (The Henrietta Lacks cervical cancer cell line) with C. albicans to simulate the infection of genital tract epithelial cells. Then we used a combination of microscopic observation, gene chips, and a series of biological and bioinformatics analyses to study the pathogenic process and the relevant C. albicans genes. We found that in the course of infection, significant morphological changes of fungus happened, and the HeLa cells were gradually destroyed. We screened a number of genes that may play an important role in the pathogenesis of infection. However, this study was conducted in vitro, and the expression of C. albicans genes in an infected host may be different due to immune response to infection, and needs further in vivo investigations. In the present studies, some gene products that may be important to the ability of this fungus to invade the organism have not received sufficient attention, hence, additional studies need to be performed to unravel the pathogenic mechanism of candidiasis and to find better ways to treat it.
Yi Bing Lan, Fan Qu, Juan-Qing Li, Lin-Juan Ma, Jie Yan, Jian-Hong Zhou. Time course of global gene expression alterations in Candida albicans during infection of HeLa cells. Bosn J Basic Med Sci 2017; [ahead of print]. DOI: http://dx.doi.org/10.17305/bjbms.2017.1667 PMID: 28397609