Increased circulating Th17 cell in a patient with tinea capitis caused by Microsporum canis

Exploring the potential link between vegetable oil supplementation and adverse food reactions in dogs: a preliminary study

BACKGROUND

Adverse food reactions (AFR) are a common cause of skin diseases in dogs, with a prevalence of up to 24%. Research in humans and mice has shown that a high intake of vegetable oils rich in omega-6 polyunsaturated fatty acids (n-6 PUFA) can increase the risk and severity of allergic diseases. This study aimed to investigate the association between AFR and the supplementation of vegetable oils in the canine diet.

RESULTS

A total of 459 dogs were analyzed, with atopic dermatitis (22.66%) and adverse food reactions (AFR) (8.06%) being the most common diagnoses. Oil supplementation was recorded in 14.16% of dogs, with extra-virgin olive oil being the most common (70.77%). Dogs with AFR and concurrent AFR and CAD showed significantly higher oil supplementation rates compared to other conditions (P < 0.05; P < 0.001). No significant association was found between oil type and diagnosis (P = 0.563). After excluding EFA-supplemented dogs and those on prescription dermo diets, oil supplementation was still more prevalent in dogs with AFR compared to other conditions (29.31% vs. 10.10%, P < 0.001).

CONCLUSIONS

Vegetable oil supplementation was more frequent in dogs with AFR than in those with other dermatological conditions. This is the first study to evaluate the relationship between vegetable oil supplementation and AFR in dogs. While vegetable oil supplementation is associated with AFR, further studies are needed to establish causality and better understand the role of n-6 PUFA in the development of food allergies in dogs.

Revisiting the pathogenesis of dermatophytosis: A cross-sectional analytic study of serum levels of interleukins-2, 8, 10 and 17

BACKGROUND

Given the current epidemic-like scenario of dermatophyte infections, it is prudent to revisit the immunopathogenesis of dermatophytosis. Comprehending the intricate interactions among interleukins can aid in understanding the recent trends in infection. There is a paucity of literature on the various cytokine levels observed in the serum of patients suffering from various dermatophytoses.

AIM

To study serum cytokine levels of interleukins 2, 8, 10 and 17 in patients with dermatophytosis.

METHODS

A cross-sectional analytic study was conducted on 64 cases of clinical dermatophyte infections (KOH confirmed) and 64 controls. The clinico-epidemiological profile of the cases was studied. By using a solid phase sandwich ELISA (enzyme-linked immunosorbent assay), the serum levels of interleukins 2, 8, 10 and 17 were measured and compared between cases and controls. Serum interleukin-2, 8, 10 and 17 levels were studied among cases based on mode of onset, duration of illness, treatment history, site of infection and multiple other morphological characteristics of the infection.

RESULTS

The cases had statistically higher levels of interleukins-8, 10 and 17 in comparison with controls. The levels of interleukin-8 were significantly lower (p < .05) among those who had received oral antifungals. In cases where the lesion had scaling, the serum levels of interleukin-10 were significantly higher (p < .05). The lesional hyperpigmentation was significantly (p < .05) associated with low levels of interleukin-17. Also, interleukin-17 was significantly (p < .05) elevated in patients with lesions in the abdomen.

CONCLUSION

It is the first time that serum interleukin levels are studied in dermatophytosis. There is an immunological dysfunction specific to dermatophytoses initiated by their infection. Key factor in this dysfunction is the elevation of IL-10, contributing to persistent infection. In turn, causing an increase in IL-17, promoting inflammation and tissue damage. This cycle of elevated IL-10 and IL-17 can further exacerbate the infection and lead to chronicity. The activity of IL-2 and the Th1 immune pathway is reduced by two opposing immune pathways: the Th17 and Th2 axes.

The Role of IL-17-Producing Cells in Cutaneous Fungal Infections

The skin is the outermost layer of the body and is exposed to many environmental stimuli, which cause various inflammatory immune responses in the skin. Among them, fungi are common microorganisms that colonize the skin and cause cutaneous fungal diseases such as candidiasis and dermatophytosis. The skin exerts inflammatory responses to eliminate these fungi through the cooperation of skin-component immune cells. IL-17 producing cells are representative immune cells that play a vital role in anti-fungal action in the skin by producing antimicrobial peptides and facilitating neutrophil infiltration. However, the actual impact of IL-17-producing cells in cutaneous fungal infections remains unclear. In this review, we focused on the role of IL-17-producing cells in a series of cutaneous fungal infections, the characteristics of skin infectious fungi, and the recognition of cell components that drive cutaneous immune cells.

Immunological response and clinical profile in patients with recurrent dermatophytosis

BACKGROUND

An alarming increase in the number of patients with chronic and recurrent dermatophytosis has invoked the need to study the immunological parameters of the host.

OBJECTIVES

To evaluate delayed type of hypersensitivity (DTH) response and immediate hypersensitivity (IH) response by flow cytometry evaluation of immune cells from peripheral blood and intradermal trichophyton skin test in patients with recurrent dermatophytosis.

METHODS

A hundred patients with recurrent dermatophytosis and 50 controls (healthy controls and acute dermatophytosis controls) were included. Relevant risk factors for recurrence were analysed, and serum IgE levels were estimated. Flow cytometry evaluation of immune cells in peripheral blood and intradermal trichophyton skin test was done. Dermatophyte pathogens were isolated, and antifungal susceptibility was performed.

RESULTS

Trichophyton mentagrophytes complex (95.84%) and T. rubrum (4.16%) were isolated in culture. Serum IgE was elevated in 83.15% cases (p = .01). IFN-γ⁺ cells (p = .0501, p = .0001, p = .0014), Th1 cells (p = .1197, p = .0024, p = .0169), IL-17⁺ cells (p = .0127, p = .0006, p = .0007) and Th17 cells (p = .0634, p = .0001, p = .0054) were reduced, and IL-4⁺ cells (p = .0108, p = .0175, p = .0018) were increased in cases. Intradermal test demonstrated negative DTH response in all cases (p < .001, p < .001, p < .001), strongly positive IH response in 6%, and borderline positive IH response in 85% cases (p = .018, p < .001, p < .001). Topical corticosteroids application, undergarment types (tight fit), poor frequency of washing clothes, family history of tinea, sharing of towels were significant risk factors for recurrent dermatophytosis.

CONCLUSIONS

Reduced IFN-γ⁺ , Th1, IL-17⁺ and Th17 cells population along with impaired DTH response by the intradermal test was observed in patients with recurrent dermatophytosis.

Dermatophytosis in companion animals: A review

Dermatophytosis, a zoonotic disease, is caused by fungi of three main genera, namely, Micropsorum, Trichophyton, and Epidermophyton. Specific lesions of dermatophyte infections are localized in the face, legs, and/or tail. Skin lesions in infected animals demonstrate localized alopecia, erythema, and crust, which are more commonly known as ringworm. Factors that affect dermatophytosis include the dermatophyte species; virulence factors of the agent; and the immune status, age, and sex of the host. High levels of cortisol and pro-inflammatory cytokines have also been reported to play an important role in dermatophyte infection. This review aims to explore and understand factors that affect dermatophyte infection with an emphasis on the prevalence, clinical signs, pathogenesis, immune response, and the roles of cortisol and cytokines in companion animals infected by a dermatophyte.

Interleukin-17 in Antifungal Immunity

The field of IL-17 biology has received much attention over the last decade owing to the pathogenic role of this cytokine in psoriasis and other autoinflammatory disorders and the successful implementation of IL-17-targeting therapies in patients suffering from these diseases. IL-17-mediated pathologies are contrasted by the important host beneficial effects of this cytokine. IL-17 is essential for regulating microbial colonization in barrier tissues. Rare congenital defects in the IL-17 pathway exemplify the relevance of IL-17 in protective immunity against the opportunistic fungal pathogen C. albicans. However, more recently, evidence is accumulating that IL-17 can also provide protection against fungi other than C. albicans. Importantly, protective IL-17 responses directed against commensal fungi can, under certain conditions, promote inflammation with detrimental consequences for the host, thereby assigning fungi a new role as disease-promoting factors apart from their role as potential infectious agents.

IL-17 Takes Center Stage in Dermatophytosis

The cytokine IL-17 plays a critical role in host defense against fungal infections. So far, clinical relevance for IL-17 antifungal activity focused on mucocutaneous candidiasis. Burstein and colleagues now provide evidence that type 17 immunity is also essential for defense against dermatophytosis.

IL-17-Mediated Immunity Controls Skin Infection and T Helper 1 Response during Experimental Microsporum canis Dermatophytosis

Despite worldwide prevalence of superficial mycoses, the immune response in dermatophytosis has scarcely been investigated. In this study, we developed a model of superficial skin infection in C57BL/6 mice with Microsporum canis, a highly prevalent human pathogen. This model mimics mild inflammatory human dermatophytosis, characterized by neutrophil recruitment and fungal invasion limited to the epidermis and exhibits the establishment of a specific T helper type 17 immune response during infection. By using IL-17RA- or IL-17A/F-deficient mice we showed that, in the absence of a functional IL-17 pathway, M. canis extensively colonizes the epidermis and promotes an exaggerated skin inflammation and a shift to an IFN-γ-mediated (T helper type 1) response. IL-17 signaling was not involved in neutrophil influx to skin or fungal invasion to deeper tissues. Finally, this study shows that skin langerin-expressing cells contribute to the antifungal T helper type 17 response in vivo. In conclusion, these data directly show a dual function of IL-17 cytokines in dermatophytosis by controlling superficial infection and down-modulating a T helper type 1 antifungal response.

Are Th17 Cells Playing a Role in Immunity to Dermatophytosis?

Despite their superficial localization in the skin, pathogenic dermatophytes can induce a complex but still misunderstood immune response in their hosts. The cell-mediated immunity (CMI) is correlated with both clinical recovery and protection against reinfection, and CD4+ T lymphocytes have been recognized as a crucial component of the immune defense against dermatophytes. Before the discovery of the Th17 pathway, CMI was considered to be only dependent of Th1 cells, and thus most studies on the immunology of dermatophytosis have focused on the Th1 pathway. Nevertheless, the fine comparative analysis of available scientific data on immunology of dermatophytosis in one hand and on the Th17 pathway mechanisms involved in opportunistic mucosal fungal infections in the other hand reveals that some key elements of the Th17 pathway can be activated by dermatophytes. Stimulation of the Th17 pathway could occur through the activation of some C-type lectin-like receptors and inflammasome in antigen-presenting cells. The Th17 cells could go back to the affected skin and by the production of signature cytokines could induce the effector mechanisms like the recruitment of polymorphonuclear neutrophils and the synthesis of antimicrobial peptides. In conclusion, besides the Th1 pathway, which is important to the immune response against dermatophytes, there are also growing evidences for the involvement of the Th17 pathway.