Related Experiment Video
Updated: Jul 4, 2026
Th17 Inflammation Model of Oropharyngeal Candidiasis in Immunodeficient Mice
Published on: February 18, 2015
Differential expression of Toll-like receptors in chronic hyperplastic candidosis
1Department of Anatomy/Biomedicum, University of Helsinki, Helsinki, Finland. ahmed.ali@helsinki.fi
Introduction:
The first step in the host defense against oral candidosis is the recognition of Candida albicans through a set of germ-encoded pathogen recognition receptors, e.g. Toll-like receptors (TLRs). In man, 10 types of such receptors have been identified so far, of which only TLR2, TLR4, and TLR6 have been linked to mediating candidal ligands, e.g. zymosan.
Methods:
Biopsies from patients with chronic hyperplastic candidosis (n = 5), leukoplakia (n = 5), and healthy mucosa (n = 5) were immunohistochemically stained with antibodies to the TLRs (TLR1 to TLR9) to distinguish and compare the staining patterns of the epithelial layer in the three categories of tissues.
Results:
On analysis, the epithelium of all tissues was divided into three layers: basal, middle, and superficial. Two of the five chronic hyperplastic candidosis sections showed high numbers of hyphae compared to yeasts, which paralleled a decrease in the expression of TLR2 and an increase in the staining intensity of TLR4. Leukoplakia and healthy tissue sections demonstrated stronger immunostaining of TLRs, except TLR9 which showed weaker staining in some sections of the former, and in the basal layers of some sections of the latter.
Discussion:
This study supports the concept of negative regulation of TLRs that are either ligand-bound (e.g. in chronic hyperplastic candidosis), or not stimulated (in healthy tissue). It also augments the opinion that C. albicans, through its hyphae rather than blastospore, may utilize TLRs, i.e. TLR2, to evade the immune system of the host. Leukoplakia seems to be more immunologically alert, which reduces the chances of worsening the already-diseased tissue.
Insights
Host defense against Candida albicans involves Toll-like receptors (TLRs). This study found TLR expression varies in oral candidosis, with hyphae potentially evading immune responses via TLR2.
Area of Science:
- Immunology
- Oral Medicine
- Microbiology
Background:
- Host defense against *Candida albicans* relies on pathogen recognition receptors like Toll-like receptors (TLRs).
- Specific TLRs (TLR2, TLR4, TLR6) are known to bind *Candida* ligands such as zymosan.
Purpose of the Study:
- To investigate and compare the expression patterns of Toll-like receptors (TLRs 1-9) in the epithelial layers of healthy oral mucosa, leukoplakia, and chronic hyperplastic candidosis.
- To elucidate the role of TLRs in the host immune response to *Candida albicans* infection.
Main Methods:
- Immunohistochemical staining of oral tissue biopsies (n=5 each for chronic hyperplastic candidosis, leukoplakia, and healthy mucosa) using antibodies against TLR1 to TLR9.
- Analysis of TLR staining patterns in the basal, middle, and superficial epithelial layers.
Main Results:
- Chronic hyperplastic candidosis sections with high *Candida* hyphae showed decreased TLR2 and increased TLR4 expression.
- Leukoplakia and healthy tissues exhibited stronger TLR immunostaining compared to some sections of leukoplakia and basal layers of healthy tissue for TLR9.
- Differential TLR expression was observed across epithelial layers in all tissue types.
Conclusions:
- TLR expression is negatively regulated in ligand-bound states (chronic hyperplastic candidosis) or when unstimulated (healthy tissue).
- *Candida albicans* hyphae may use TLR2 to evade the host immune system.
- Leukoplakia demonstrates heightened immunological alertness, potentially preventing disease exacerbation.
Related Concept Videos
01:20Candidiasis
01:25Inflammatory Bowel Disease III: Crohn's Disease