Impact of high SAP2 expression on the invasion and adhesion abilities of Candida albicans in vaginal epithelial cells

Background

The link between SAP2 and Candida albicans' capacity to adhere to and invade host cells is notable, although the precise molecular mechanisms remain unclear. The purpose of this study was to examine how elevated SAP2 expression influences the invasion and adhesion capabilities of C. albicans in A431 cells using in vitro experiments and transcriptomic sequencing.

Methods

The effect of high SAP2 expression on the invasion of A431 cells by C. albicans was evaluated using lactate dehydrogenase (LDH) release assay. Morphological changes in hyphae were observed under a microscope during co-culture with A431 cells. The ability of C. albicans to adhere to A431 cells was assessed using an adhesion assay. Transcriptomic sequencing and qRT-PCR were used to examine changes in gene expression and associated signaling pathways in C. albicans after co-culture with A431 cells.

Results

After 1.5–2 h of co-culture, the number of A431 cell colonies adhered by the SC5314 strain was significantly higher than adhered by the SAP2-overexpressing SC5314 strain (pRB895-SAP2-SC5314). After 8 h, the SC5314 strain induced the formation of dense, elongated hyphae, whereas the pRB895-SAP2-SC5314 strain formed clustered, snowflake-like yeast forms. After 24 h, the LDH release assay revealed a significantly higher death rate of A431 cells in the SC5314 group. Differential expression analysis identified 50 upregulated and 10 downregulated genes in the pRB895-SC5314 strain relative to the SC5314 strain. A total of 1142 genes were upregulated and 1219 genes were downregulated in the pRB895-SAP2-SC5314 strain relative to the SC5314 strain. In addition, 1159 genes were upregulated and 1228 genes were downregulated in the pRB895-SAP2-SC5314 strain relative to the pRB895-SC5314 strain. KEGG enrichment analysis indicated the MAPK signaling pathway associated with these genes, and qRT-PCR showed significant downregulation of genes such as TEC1.

Conclusion

Co-culture with A431 cells significantly inhibited hyphal growth and attenuated the invasion and adhesion abilities of the pRB895-SAP2-SC5314 strain. Several genes related to SAP2 were upregulated or downregulated, suggesting that the role of SAP2 in the pathogenic mechanisms of C. albicans is influenced by complex regulatory factors, with the MAPK signaling pathway serving as a key factor.