Elucidating Host-Pathogen Interaction in Acute Systemic Candidiasis in a Mouse Model Using Genomic Approach. Mus musculus

Candida species is a common fungus that had evolved as both commensal and opportunistic pathogen in humans. The rise in human morbidity and mortality caused by Candida species sparked an alarming concern. However, the thin line between commensalism and infection as well as the analysis of Candida host-pathogen interactions has not been completely elucidated prior to the birth of global gene expression technologies. Gene expression analysis of host response upon systemic candidiasis had been carried out using Beadarray and validated by using GenomeLab™ GeXP multiplex PCR. Whole blood from infected mouse was isolated, globin mRNA depleted through subtractive hybridization and its RNA purified. Results from microarray data demonstrated increased expression of genes involved in the pathogen recognition, signal transduction, inflammation, microbial killing and in antigen processing. Interestingly, we also discovered possible increment of erythropoiesis in our animal model and this lead us to believe that Candida tropicalis might possess potent haemolytic factors to sequester iron from the host erythrocytes. Taken together, our data also suggest novel genes such as syndecans and dendritic cell immunoreceptor which might be exploited by Candida tropicalis in its pathogenesis in the host. Nevertheless, the challenge ahead is to understand the specific roles of these genes that underlies in Candida tropicalis pathogenesis. Overall design: For gene expression analysis, BALB/c mice (six-week-old female weighing 20-25g) were used and the animals were randomized, assigned to the control, sublethal infection and lethal infection groups. At the time of killing, mice were anesthetized and exsanguinated by cardiac puncture. Approximately 200 µl of whole blood was collected and added into 2 ml tubes preloaded with RNAlater (Sigma-Aldrich CO, USA) and stored in -80 °C.