Adherence and invasion studies of Candida albicans strains, using in vitromodels of esophageal candidiasis

The adherence of clinical and commensal isolates and reference collection s trains of Candida albicans to a human esophageal cell monolayer (HET1-A) an d reconstituted human esophageal tissue was compared. Isolates from patient s with a severe form of esophageal candidiasis or candidemia adhered to HET 1-A cells to a significantly greater extent than did isolates from patients with mild esophageal candidiasis or commensal and reference collection str ains. In addition, C. albicans strain SSK21, which lacks the ssk1 response regulator gene of a 2-component signal transduction pathway, adhered less r eadily to the HET1-A cells than did parental cells or a gene-reconstituted strain. In a reconstituted esophageal tissue model, all clinical strains bu t not commensal or reference collection strains penetrated the epithelium, albeit at different rates. Hyphal formation following yeast cell adherence to the esophageal tissue was a requirement for invasion. Scanning electron microscopy was also used to confirm the colonization of the esophageal tiss ues by various strains. These studies indicate that both the HET1-A and the reconstituted esophageal tissue models can be used as in vitro targets to evaluate the adherence phenotype and invasiveness of C. albicans strains.