Perspective on animal models of dermatophytosis caused by Trichophyton rubrum

Evaluation of an Explanted Porcine Skin Model to Investigate Infection with the Dermatophyte Trichophyton rubrum

Dermatophytosis is a fungal infection of skin, hair and nails, and the most frequently found causative agent is Trichophyton rubrum. The disease is very common and often recurring, and it is therefore difficult to eradicate. To develop and test novel treatments, infection models that are representative of the infection process are desirable. Several infection models have been developed, including the use of cultured cells, isolated corneocytes, explanted human skin or reconstituted human epidermis. However, these have various disadvantages, ranging from not being an accurate reflection of the site of infection, as is the case with, for example, cultured cells, to being difficult to scale up or having ethical issues (e.g., explanted human skin). We therefore sought to develop an infection model using explanted porcine skin, which is low cost and ethically neutral. We show that in our model, fungal growth is dependent on the presence of skin, and adherence of conidia is time-dependent with maximum adherence observed after ~ 2 h. Scanning electron microscopy suggested the production of fibril-like material that links conidia to each other and to skin. Prolonged incubation of infected skin leads to luxurious growth and invasion of the dermis, which is not surprising as the skin is not maintained in conditions to keep the tissue alive, and therefore is likely to lack an active immune system that would limit fungal growth. Therefore, the model developed seems useful to study the early stages of infection. Furthermore, we demonstrate that the model can be used to test novel treatment regimens for tinea infections.

The Immunomodulatory Effect of Trichophyton Rubrum Exoantigens in the Treatment of Experimental Septic Arthritis

Background:

Understanding the nature and function of fungal exoantigens might lead to novel approaches in the treatment and prophylaxis of some infectious diseases. Septic arthritis represents a serious problem for medicine due to the high incidence rate and severe complications.

Objective:

The present study aimed at assessing the immunomodulatory effects of Trichophyton rubrum culture filtrate as a novel compound in experimental septic arthritis.

Method:

The septic arthritis was haematogenously induced in Sprague-Dawley rats by a single intravenous injection of 10⁹ colony forming units of the human clinical isolate Staphylococcus aureus producing toxic shock syndrome toxin-1. Trichophyton rubrum culture filtrate at two different doses 20 and 40 mg/kg was administered intraperituneally two days after bacterial inoculation in the treatment groups and concurrently with the appearance of clinical signs in the patient groups. The administration of Trichophyton rubrum solution was continued every other day for 10 injections.

Results:

The clinical evaluation showed that Trichophyton rubrum-treated rats were significantly protected from disease development compared with untreated controls. This finding was correlated with results of radiological evaluation of the involved joints. Although, the inflammatory cell infiltration, cartilage/bone destruction and synovial hypertrophy had been decreased in the treatment groups in comparison with arthritic controls however, the histological changes were not significant in these two groups.

Conclusion:

It is possible that Trichophyton rubrum antigens may play a role in modulating the immune responses and would be efficient in septic arthritis treatment.