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Adherence of dermatophyte microconidia and arthroconidia to human keratinocytes in vitro
1Department of Medical Microbiology, London School of Hygiene and Tropical Medicine, U.K.
Abstract:
The early interaction, adherence, between dermatophyte conidia and human keratinocytes has been studied in vitro. Two spore forms were used: microconidia and arthroconidia produced in vitro. The adherence of spores from three dermatophyte species, Trichophyton rubrum, T interdigitale, and T quinckeanum, was investigated using keratinocyte suspensions from different skin sites. Time-dependent adherence was demonstrated for all fungi studied with maximum adherence occurring between 3 and 4 h. There were no significant differences in adherence rates between the organisms studied. An order of affinity was established between keratinocytes from different sites and significant differences were demonstrated in adherence of microconidia to skin cells derived from sole versus knee. No differences in adherence rates were demonstrated in atopics versus patients with chronic dermatophytosis and normals. Adherence was inhibited, but not abolished, by subinhibitory concentrations of ketoconazole, itraconazole, and griseofulvin. The interaction between microconidia, arthroconidia, and keratinocytes was verified with scanning and transmission electron microscopy.
Insights
Dermatophyte fungal spores adhere to human skin cells within 3-4 hours. This fungal adherence varies by skin site but is not affected by atopic status and is only partially inhibited by common antifungal medications.
Area of Science:
- Mycology
- Dermatology
- Cell Biology
Background:
- Dermatophytes are fungi that cause skin infections.
- Understanding fungal spore adherence to human keratinocytes is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the in vitro adherence of dermatophyte conidia to human keratinocytes.
- To determine the influence of spore type, fungal species, skin site, and patient status on adherence.
- To assess the effect of subinhibitory antifungal concentrations on adherence.
Main Methods:
- In vitro study using microconidia and arthroconidia from Trichophyton rubrum, T. interdigitale, and T. quinckeanum.
- Keratinocyte suspensions from different skin sites (sole, knee) were used.
- Time-course adherence assays were performed.
- Scanning and transmission electron microscopy visualized fungal-keratinocyte interactions.
- Adherence was tested in normal, atopic, and chronically infected patient samples.
Main Results:
- Time-dependent adherence was observed, peaking between 3 and 4 hours for all species.
- Significant differences in microconidia adherence were found between keratinocytes from the sole and knee.
- No significant differences in adherence rates were observed between the three dermatophyte species studied.
- Adherence rates did not differ between atopics, patients with chronic dermatophytosis, and normal individuals.
- Subinhibitory concentrations of ketoconazole, itraconazole, and griseofulvin partially inhibited adherence.
Conclusions:
- Dermatophyte conidia exhibit time-dependent adherence to human keratinocytes, with variations based on skin site.
- Fungal adherence is not influenced by host atopic status or chronic infection.
- Antifungal agents show partial inhibition of adherence, suggesting complex interactions.
- Electron microscopy confirmed the interaction between fungal spores and keratinocytes.