Toll-like receptors (TLR) 2 and 4 expression of keratinocytes from patients with localized and disseminated dermatophytosis

In Situ Expression of TNF-α and IL-10 in Human Dermatophytosis Lesions due to Trichophyton rubrum

Dermatophytosis is a very common superficial mycosis, but there are few studies about the human immune response to dermatophytes. We aim to analyze the in situ expression of TNF-α and IL-10 in human dermatophytosis. Expression of TNF-α and IL-10 were evaluated in skin samples from 10 patients with dermatophytosis and 12 healthy subjects using an immunohistochemistry assay. TNF-α and IL-10 were significantly elevated in lesions from patients with dermatophytosis compared to healthy controls. These data illustrate the balance of pro- and anti-inflammatory cytokines suggesting Trichophyton rubrum infection could control the local immune response.

Dermatophyte infection: from fungal pathogenicity to host immune responses

Dermatophytosis is a common superficial infection caused by dermatophytes, a group of pathogenic keratinophilic fungi. Apart from invasion against skin barrier, host immune responses to dermatophytes could also lead to pathologic inflammation and tissue damage to some extent. Therefore, it is of great help to understand the pathogenesis of dermatophytes, including fungal virulence factors and anti-pathogen immune responses. This review aims to summarize the recent advances in host-fungal interactions, focusing on the mechanisms of anti-fungal immunity and the relationship between immune deficiency and chronic dermatophytosis, in order to facilitate novel diagnostic and therapeutic approaches to improve the outcomes of these patients.

Molecular study of feline dermatophytosis and Toll-like receptor 2 and 4 gene expression in their lesions

BACKGROUND

Pattern recognition receptors (PRRs) as the recognition of pathogenic fungal structures induce the secretion of cytokines by immune systems. Toll-like receptors (TLRs) 2 and 4 are the main PRRs that recognize fungal components.

AIM

The present study aimed to assess the presence of dermatophyte species in symptomatic cats in a region of Iran and to investigate the expression of TLR-2 and 4 in cat lesions with dermatophytosis.

METHODS

A total of 105 cats suspected of dermatophytosis with skin lesions were examined. Samples were analysed by direct microscopy using potassium hydroxide (20%) and culture on Mycobiotic agar. Dermatophytes strains were confirmed by the polymerase chain reaction (PCR) amplification and then sequencing of the Internal Transcribed Spacer rDNA region. Also, for pathology and real-time PCR studies, skin biopsies were taken by sterile single-use biopsy punch from active ringworm lesions.

RESULTS

Dermatophytes were found in 41 felines. Based on the sequencing of all strains, Microsporum canis (80.48%, p < 0.05), Microsporum gypseum (17.07%) and Trichophyton mentagrophytes (2.43%) were the dermatophytes isolated from cultures. Cats under 1 year (78.04%) revealed a statistically significantly higher prevalence of infection (p < 0.05). Gene expression by real-time PCR revealed the increased TLR-2 and 4 mRNA levels in skin biopsies of cats with dermatophytosis.

CONCLUSIONS

M. canis is the most prevalent dermatophyte species isolated from feline dermatophytosis lesions. Increased expression of TLR-2 and TLR-4 mRNAs in cat skin biopsies suggests that these receptors are involved in the immune response by recognizing dermatophytosis.

Advances in the Phytochemical Characterisation and Bioactivities of Salvia aurea L. Essential Oil

The Salvia L. genus (Lamiaceae) is largely used in the pharmaceutical and food industry. Several species of biological relevance are extensively employed in traditional medicine, including Salvia aurea L. (syn. S. africana-lutea L.), which is used as a traditional skin disinfectant and in wounds as a healing remedy; nevertheless, these properties have not been validated yet. The aim of the present study is to characterise S. aurea essential oil (EO), unveiling its chemical composition and validating its biological properties. The EO was obtained by hydrodistillation and subsequently analysed by GC-FID and GC-MS. Different biological activities were assessed: the antifungal effect on dermatophytes and yeasts and the anti-inflammatory potential by evaluating nitric oxide (NO) production and COX-2 and iNOS protein levels. Wound-healing properties were assessed using the scratch-healing test, and the anti-aging capacity was estimated through the senescence-associated beta-galactosidase activity. S. aurea EO is mainly characterised by 1,8-cineole (16.7%), β-pinene (11.9%), cis-thujone (10.5%), camphor (9.5%), and (E)-caryophyllene (9.3%). The results showed an effective inhibition of the growth of dermatophytes. Furthermore, it significantly reduced protein levels of iNOS/COX-2 and simultaneously NO release. Additionally, the EO exhibited anti-senescence potential and enhanced wound healing. Overall, this study highlights the remarkable pharmacological properties of Salvia aurea EO, which should be further explored in order to develop innovative, sustainable, and environmentally friendly skin products.

Unveiling the Chemical Composition and Biological Properties of Salvia cacaliifolia Benth. Essential Oil

Salvia is widely recognized for its therapeutic potential. However, the biological relevance of some species remains unknown, namely Salvia cacaliifolia Benth. Therefore, the aim of this study is to unveil the chemical composition and relevant properties to its essential oil (EO). The EO was characterized by GC and GC-MS and its antifungal effect was evaluated according to the CLSI guidelines on dermatophytes and yeasts. The anti-inflammatory potential was assessed on lipopolysaccharide-stimulated macrophages, by assessing the production of nitric oxide (NO) and the effect on the protein levels of two key pro-inflammatory enzymes, iNOS and COX-2 by western blot analysis. Wound healing capacity was determined using the scratch wound healing assay, and the anti-aging potential was assessed by evaluating the senescence marker β-galactosidase. The EO was mainly characterized by γ-curcumene, β-bisabolene, bicyclogermacrene and curzerenone. It is effective in inhibiting the growth of dermatophytes and C. neoformans. The EO significantly decreased iNOS and COX-2 protein levels and concomitantly reduced NO release. Additionally, it demonstrated anti-senescence potential and promoted wound healing. Overall, this study highlights relevant pharmacological properties of the EO of Salvia cacaliifolia, which should be further explored envisaging the development of sustainable, innovative, and environmentally friendly skin products.

Investigation of serum beta-defensin-1 levels in bovine trichophytosis cases

Background and Aim:

Antimicrobial peptides are polypeptides that are a component of innate immunity and exhibit antifungal activity. This study aimed to investigate serum beta-defensin-1 levels in cattle diagnosed with trichophytosis, which is a zoonotic skin disease that affects several animal species.

Materials and Methods:

A total of 23 young cattle, aged 2-4 months, of different breeds and sexes were selected. Of these, 16 cattle were clinically diagnosed with trichophytosis and seven were healthy.

Results:

The mean serum beta-defensin-1 levels of the infected animals were lower than those of control animals, yet the difference between the two groups was not significant (p>0.05).

Conclusion:

No significant alterations occurred in serum beta-defensin-1 levels of cattle with trichophytosis.

Epidemiological, clinical and mycological study of dermatomycosis in diabetic patients

BACKGROUND

Dermatomycosis are fungal infections of the skin and/or phanera, which are often benign but can have an impact on the vital and functional prognosis in diabetic patients.

AIM

The aim of our work was to study the epidemiological, clinical and mycological profile of dermatomycosis in diabetic patients.

METHODS

This was a retrospective descriptive study carried out in the Parasitology-Mycology Laboratory of Charles-Nicolle Hospital over a three-year period (2016-2018). We collected diabetic patients who were referred for suspected dermatomycosis.

RESULTS

Dermatomycosis was confirmed in 799 of the 1007 diabetic patients referred to our laboratory (79.34%) and in 1055 lesions among the 1344 sites sampled (78.50%). Among patients with dermatomycosis, a female predominance was observed with a sex- ratio=0.83. The mean age of the patients was 57.11 [2-82]. The patients with type 2 diabetes were the most affected (86.35%) (p=0.038). The mean duration of lesion progression was 5.0±5.5 years. The most common dermatomycoses were toenail onychomycoses (59.62%), followed by fingernail onychomycoses (15.26%), plantar keratoderma (10.24%), and intertrigo in small skin folds (5.59%). Dermatophytes were the most frequently isolated fungi (80.1%; p<0.001), with predominance of Trichophyton rubrum (78.8%). Candida albicans was the most frequently isolated yeast (11.8%).

CONCLUSIONS

Dermatomycosis are common in diabetic patients. Although they are often benign, these fungal infections can engage the functional prognosis or even become life-threatening in case of diabetes. Mycological diagnosis is necessary in case of clinical suspicion in order to confirm the diagnosis, guide the treatment and avoid complications.

Host immune responses in dermatophytes infection

Dermatophytosis is a skin infection caused by keratinophilic, filamentous fungi. These are highly prevalent, common mycoses, affecting approximately 20% of the population. These fungi invade the stratum corneum, and other keratinised tissues, like nails and hair, where they grow by secreting enzymes and degrading keratin to obtain nutrients. Clinical presentation is variable and may depend on many factors, such as the infection site, the host's immunity and the dermatophyte's virulence. Generally, patients with acute superficial dermatophytosis mount cell-mediated immune responses. However, those suffering from chronic or recurrent infections are unable to develop this response, for reasons yet unknown. Several reports have described severe and occasionally life-threatening invasive diseases (deep dermatophytosis) associated with genetic mutations in the innate immunity-associated molecule CARD9, displaying the need to better understand its immune response. These dermatoses have substantial clinical consequences, producing chronic and difficult to treat skin lesions. They also lead to a decline in the patient's quality of life and impact their self-esteem. This review summarises findings on the immune response against dermatophytes.

Human primary epidermal organoids enable modeling of dermatophyte infections

Technology of generating human epidermal derivatives with physiological relevance to in vivo epidermis is continuously investigated for improving their effects on modeling of human natural dermatological status in basic and clinical studies. Here, we report a method of robust establishment and expansion of human primary epidermal organoids (hPEOs) under a chemically defined condition. hPEOs reconstruct morphological, molecular, and functional features of human epidermis and can expand for 6 weeks. Remarkably, hPEOs are permissive for dermatophyte infections caused by Trichophyton Rubrum (T. rubrum). The T. rubrum infections on hPEOs reflect many aspects of known clinical pathological reactions and reveal that the repression on IL-1 signaling may contribute to chronic and recurrent infections with the slight inflammation caused by T. rubrum in human skin. Thus, our present study provides a new insight into the pathogenesis of T. rubrum infections and indicates that hPEOs are a potential ex vivo model for both basic studies of skin diseases and clinical studies of testing potential antifungal drugs.

Trichophyton rubrum Elicits Phagocytic and Pro-inflammatory Responses in Human Monocytes Through Toll-Like Receptor 2

Dermatophytosis is a superficial fungal infection mostly restricted to keratinized tissues such as skin, hair, and nails but with potential to cause invasive or even systemic disease in immunocompromised patients. Trichophyton rubrum is the main etiologic agent, accounting for approximately 80% of the cases. Mononuclear phagocytes respond to pathogens through phagocytosis followed by production of several antimicrobial molecules, such as reactive oxygen and nitrogen species, and failure in doing so may contribute to development of chronic fungal infections. Toll-like receptors (TLRs) located on the surface of phagocytic cells bind either directly to target particles or through opsonizing ligands and trigger an actin-mediated ingestion. Even though the mechanisms involved in TLR-mediated cytokine responses are well established, the contribution of TLR in the recognition of T. rubrum by adherent monocytes remains unclear. Here, we report that phagocytosis of T. rubrum conidia by adherent monocytes is mediated by TLR2. Blockade of TLR2 by neutralizing antibodies impaired the fungicidal activity of monocytes as well their secretion of tumor necrosis factor (TNF)-α, but neither nitric oxide (NO) production nor interleukin (IL)-10 secretion was disturbed. So far, our data suggest that TLR2 is required for efficient conidial phagocytosis, and the absence of TLR2 signaling in human monocytes may impair the subsequent inflammatory response. These findings expand our understanding of phagocyte modulation by this important fungal pathogen and may represent a potential target for interventions aiming at enhancing antifungal immune responses.

Host- and pathogen-dependent susceptibility and predisposition to dermatophytosis

Dermatophytes are a highly specialized group of keratinophilic and keratinolytic filamentous fungi causing a ringworm disease called dermatophytosis or superficial mycoses. Although dermatophyte infections do not threaten the host's life, they lower its quality in humans by causing discomfort related to cosmetic problems and through their epidemiological significance, whereas in farm animals they are responsible for economic losses and constitute a source of the spread of spores. Evidence from countless observational studies that have been conducted over the last 90 years indicates that dermatophytes infect humans of every age, race, gender and socioeconomic status with strikingly high rates, as well as both farmed and wild animals in various health conditions and with various epidemiological statuses. However, the prevalence of superficial fungal infections is highly variable, since it depends on several parameters associated with the infected individual and the dermatophyte, their mutual interactions, and epidemiological and geographical factors. The curious disparity in dermatophyte infection patterns has prompted many investigators to search for a link between the host, the host's predispositions and susceptibility to the disease, and the dermatophyte species and virulence. Thus, the question arises as to whether, in addition to the generally recognized factors predisposing hosts to diseases, there are some other predispositions to dermatophyte infections in a species-specific host. In this review, we describe recent findings about the mechanism of dermatophyte infections, focusing on the adaptation of the fungi to the host and conditions predisposing each side to the disease.

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.

Recurrent and disseminated pityriasis versicolor: A novel clinical form consequent to Malassezia-host interaction?

Pityriasis versicolor is a superficial fungal infection caused by Malassezia spp. The aim of this study is to propose the definition of a new clinical entity: the recurrent and disseminated pityriasis versicolor (RDPV). All patients with RDPV were enrolled over an eight-month period. Clinical and epidemiological data were obtained, Malassezia (M.) species were isolated in cultures and identified by phenotypic and molecular characterization, skin biopsies were taken from active lesions, serum levels of immunoglobulin E were obtained and therapeutic schemes were evaluated. A total of 16 patients were included (11 male, 5 female). The most frequently isolated species were M. japonica (n = 3) and M. furfur (n = 3). This is the first study that isolates M. japonica in patients with pityriasis versicolor; interestingly, those were recalcitrant patients. Seven patients (43.8%) had no cure with any of the proposed treatments; among those, 5 (71.4%) had increased serum IgE levels. The most effective treatment was itraconazole 200 mg daily for 28 days. The RDPV has very different features from the classic form, including a poor response to treatment, and the isolation of different Malassezia species; therefore, we propose a hypothesis for the definition of a new clinical condition (RDPV), which could be a result of the interaction Malassezia-host.

TLR4 as a negative regulator of keratinocyte proliferation

TLR4 is an innate immune receptor with expression in human skin, keratinocytes as well as squamous cell carcinoma (SCC) of the skin. In the present study we investigate the role of TLR4 as a negative regulator of keratinocyte proliferation. We present here that the expression of TLR4 increased with the differentiation of cultured keratinocytes in a passage-dependent manner or under calcium-rich conditions. Moreover, the down-regulation of TLR4 by specific knockdown increased the proliferation of HaCaT keratinocytes in vitro. In addition, subcutaneously injected HaCaT keratinocytes with shTLR4 formed growing tumors in nude mice. In contrast, we observed lower proliferation and increased migration in vitro of the SCC13 cell line stably overexpressing TLR4 in comparison to SCC13 TLR4 negative cells. In vivo, SCC13 TLR4-overexpressing tumors showed delayed growth in comparison to TLR4 negative tumors. The overexpression of TLR4 in SCC13 tumor cells was followed by phosphorylation of ERK1/2 and JNK and increased expression of ATF3. In gene expression arrays, the overexpression of TLR4 in tumor cells correlated with gene expression of ATF-3, IL-6, CDH13, CXCL-1 and TFPI. In summary, TLR4 negatively regulates the proliferation of keratinocytes and its overexpression reduces tumor growth of SCC cells.

The Role of Phagocytes and NETs in Dermatophytosis

Innate immunity is the host first line of defense against pathogens. However, only in recent years, we are beginning to better understand the ways it operates. A key player is this branch of the immune response that are the phagocytes, as macrophages, dendritic cells and neutrophils. These cells act as sentinels, employing specialized receptors in the sensing of invaders and host injury, and readily responding to them by production of inflammatory mediators. They afford protection not only by ingesting and destroying pathogens, but also by providing a suitable biochemical environment that shapes the adaptive response. In this review, we aim to present a broad perspective about the role of phagocytes in dermatophytosis, focusing on the mechanisms possibly involved in protective and non-protective responses. A full understanding of how phagocytes fit in the pathogenesis of these infections may open the venue for the development of new and more effective therapeutic approaches.

Management of tinea corporis, tinea cruris, and tinea pedis: A comprehensive review

The prevalence of superficial mycotic infection worldwide is 20–25% of which dermatophytes are the most common agents. Recent developments in understanding the pathophysiology of dermatophytosis have confirmed the central role of cell-mediated immunity in countering these infections. Hence, a lack of delayed hypersensitivity reaction in presence of a positive immediate hypersensitivity (IH) response to trichophytin antigen points toward the chronicity of disease. Diagnosis, though essentially clinical should be confirmed by laboratory-based investigations. Several new techniques such as polymerase chain reaction (PCR) and mass spectroscopy can help to identify the different dermatophyte strains. Management involves the use of topical antifungals in limited disease, and oral therapy is usually reserved for more extensive cases. The last few years have seen a significant rise in the incidence of chronic dermatophyte infections of skin which have proven difficult to treat. However, due to the lack of updated national or international guidelines on the management of tinea corporis, cruris, and pedis, treatment with systemic antifungals is often empirical. The present review aims to revisit this important topic and will detail the recent advances in the pathophysiology and management of tinea corporis, tinea cruris, and tinea pedia while highlighting the lack of clarity of certain management issues.

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.