Trichophyton rubrum manipulates the innate immune functions of human keratinocytes

Extracellular Vesicles From the Dermatophyte Trichophyton interdigitale Modulate Macrophage and Keratinocyte Functions

The release of biomolecules critically affects all pathogens and their establishment of diseases. For the export of several biomolecules in diverse species, the use of extracellular vesicles (EVs) is considered to represent an alternative transport mechanism, but no study to date has investigated EVs from dermatophytes. Here, we describe biologically active EVs from the dermatophyte Trichophyton interdigitale, a causative agent of mycoses worldwide. EV preparations from T. interdigitale were examined using nanoparticle-tracking analysis, which revealed vesicular structures 20–380 nm in diameter. These vesicles induced the production of proinflammatory mediators by bone marrow-derived macrophages (BMDMs) and keratinocytes in a dose-dependent manner, and an addition of the EVs to BMDMs also stimulated the transcription of the M1-polarization marker iNOS (inducible nitric oxide synthase) and diminished the expression of the M2 markers arginase-1 and Ym-1. The observed M1 macrophages' polarization triggered by EVs was abolished in cells obtained from knockout Toll-like receptor-2 mice. Also, the EVs-induced productions of pro-inflammatory mediators were blocked too. Furthermore, the EVs from T. interdigitale enhanced the fungicidal activity of BMDMs. These results suggest that EVs from T. interdigitale can modulate the innate immune response of the host and influence the interaction between T. interdigitale and host immune cells. Our findings thus open new areas of investigation into the host-parasite relationship in dermatophytosis.

The Immunologic Response to Trichophyton Rubrum in Lower Extremity Fungal Infections

Manifestations of Trichophyton rubrum infestations, such as tinea pedis, tinea cruris, and tinea corporis, are among the most common human skin diseases seen throughout the world. About 80% of patients presenting with acute dermatophytosis respond well to topical antifungal treatment. However, the remaining 20% of patients progress into a chronic state of dermatophytosis, which is resistant to antifungal treatment. Therefore, it is necessary to have a better understanding and appreciation for the diverse immune responses to Trichophyton as this is critical for the development of therapeutic strategies for those individuals who suffer from a chronic manifestation of Trichophyton rubrum (T. rubrum) infection. As a result, a comprehensive literature review was conducted to review and discuss previous studies that evaluated the human body’s defense to T. rubrum infections and to understand why and how these fungal infections invade the host defense system. Our research revealed that a cell-mediated immune response is critical in defending the body against T. rubrum. However, this organism has mechanisms that enable it to evade the immune system. Therefore, a more successful treatment for chronic T. rubrum infection would involve targeting the mechanisms of T. rubrum that diminish the immune response, while restoring the cell-mediated immune response.