Immune response and host resistance of humans to dermatophyte infection

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.

Inherited ichthyosis and fungal infection: an update on pathogenesis and treatment strategies

Inherited ichthyoses are a group of genodermatoses classified as either nonsyndromic or syndromic. Nonsyndromic ichthyoses and keratitis, ichthyosis and deafness (KID) syndrome predispose to fungal infection. The diagnosis and treatment of fungal infections underlying ichthyoses are challenging. In this review, we summarize reported cases of ichthyosis with fungal infection over the past 50 years. Atypical manifestations such as alopecia, papules and brittle nails occurred in patients with ichthyosis combined with fungal infection. Various pathogenic mechanisms have been implicated, including mutations of ichthyosis-related genes leading to disruption of the skin barrier via multiple pathways. Host immune disorders, including atopy and abnormal innate immunity also contribute to susceptibility. Specific fungi may escape the immune response. Extensive and recurrent fungal infections are not uncommon in patients with ichthyosis, making a cure more difficult and increasing the need for systemic antifungal therapy. Traditional and new ichthyosis treatments aiming to improve skin barrier function could help prevent fungal infection. In conclusion, the close relationship between ichthyosis and fungal infection is of vital importance in clinical practice and requires more attention from physicians. More studies are required to investigate the mechanisms and explore useful treatment strategies.

Congenital ichthyosis associated with Trichophyton rubrum tinea, imitating drug hypersensitivity reaction

Tinea corporis and congenital ichthyoses are common dermatological diseases. The association of the two disorders is plausible due to the immunological and barrier defects of ichthyoses; however, relatively limited literature is available in this field. Since superficial fungal infections possess atypical morphology in keratinization disorders, and could imitate other dermatological conditions, the correct diagnosis can be challenging. We present the case of a 54-year-old woman with ichthyosis, who was initially treated for drug-hypersensitivity reaction.

The interplay among Th17 and T regulatory cells in the immune dysregulation of chronic dermatophytic infection

The delineation of the pathogenic interaction between the host skin immune responses and dermatophytes has remained indigent. The obscure enigma in host-dermatophyte immunopathogenic interactions is the T regulatory (Treg) and T-helper (Th) 17  cell role in maintaining immune homeostasis. We attempted to understand the regulation and recognition of lineage-specific response in chronic dermatophytic skin infection patients. The percentages of Th17 (CD4⁺CD161⁺IL23R⁺) and Treg (CD4⁺CD25⁺FoxP3⁺) cell subpopulations in the peripheral circulation of thirty chronic dermatophytic skin infection patients and twenty healthy individuals was determined. The serum cytokine levels were estimated for disease correlation. The mean duration of the disease was 10.68 ± 8.72 months, with Trichophyton mentagrophytes complex as the major pathogen. Total serum IgE level of patients was significantly higher compared to healthy controls (305 ± 117 vs 98.53 ± 54.55 IU/ml; p < 0.01). Expression of Th17 and Treg cell markers on CD4⁺ T cells was significantly elevated in patients than controls (p < 0.05). Comparatively, serum interleukin (IL)-4 and interferon (IFN)-γ levels were increased, with low IL-10 levels in patients. Our data envisages a complex immune dysfunction in chronic dermatophytosis, arising either as a result of dermatophyte exposure or paradoxical precedence of disease establishment. Designing new treatment strategies and preventing recurrences are challenges for future research.

Persian cats under first opinion veterinary care in the UK: demography, mortality and disorders

Persian cats are a popular cat breed worldwide, and especially in the US, Europe and Asia. This study aimed to describe the demography, common disorders and mortality in Persians under general practice veterinary care in 2013 in the UK. The study population of 285,547 cats overall included 3235 (1.1%) Persians. Mean adult Persian bodyweight was 3.9 kg (SD 0.9) and median age was 7.0 years (IQR 3.3–11.6). At least one disorder was recorded in 2099 (64.9%) Persians. The most common specific disorders were haircoat disorders (411, 12.7%), periodontal disease (365, 11.3%), overgrown nails (234, 7.2%), and ocular discharge (188, 5.8%). The most common disorder groups were dermatological (578, 17.9%), ophthalmological (496, 15.3%) and dental (397, 12.3%). Median longevity was 13.5 years (IQR 9.9–16.0). The most common grouped causes of death were renal disease (102, 23.4%), neoplasia (37, 8.5%) and mass-associated disorder (35, 8.0%). This is the first study to use general practice data to examine the overall health of Persian cats. With haircoat, ocular and dental disorders being the predominant disorders identified, this study highlights the need for increased owner awareness to manage and prevent the typical health problems associated with this breed’s phenotype.

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.

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.

Majocchi granuloma in a pregnant woman

BACKGROUND

Majocchi granuloma is a cutaneous dermatophyte infection of the dermal and subcutaneous tissues characterized by chronic erythematous and indurated plaques, which are almost always the result of immunodeficiency and trauma.

CASE

Disseminated dermatophyte Majocchi granuloma was diagnosed in a 19-year-old woman at 32 weeks of gestation and had no history of trauma or chronic illness. She was treated with topical antifungal medications until delivery, at which time systemic medications were started. The skin lesions resolved by the time of her 6-week postpartum visit.

CONCLUSION

The altered immune state of pregnancy suggests that Majocchi granuloma should occur with some regularity in pregnancy. That this case is the second one described in the literature suggests that it may be underdiagnosed. Punch biopsy should be considered for diagnosis of unusual skin lesions during pregnancy.

Refractory Trichophyton rubrum infection in lamellar ichthyosis

A 10-month-old boy with congenital lamellar ichthyosis presented with a chronic Trichophyton rubrum infection. There was no history of atopy or immunosuppression, and examination revealed high total immunoglobulin E (IgE) with a positive specific IgE for T. rubrum. Multiple treatments with fluconazole were necessary to control the infection. T. rubrum is present worldwide and is responsible for the vast majority of chronic dermatophytosis. Lamellar ichthyosis is a risk factor for chronic dermatophytosis because of excessive keratin and the barrier defect. A delayed-type hypersensitivity reaction to T. rubrum is associated with cure, whereas immediate hypersensitivity and IgE are not protective and may lead to chronic infection. Atopy and the Th2 profile therefore seem to be associated with chronic dermatophytosis. The association between ichthyosis and atopy is well documented. T. rubrum also has an interesting ability to evade immunity, which helps explain the chronic infection. Finally, in ichthyosis, it is likely that fluconazole has difficulty penetrating the acanthotic stratum corneum, which explains treatment failure. We report this case to alert clinicians to the possible association between lamellar ichthyosis and chronic dermatophytosis and to report the difficulties of management.

Association between onychodystrophy and human T-lymphotropic virus type 1 infection

OBJECTIVE

To assess the association between human T-lymphotropic virus type 1 (HTLV-1) infection and onychodystrophy.

METHODS

This was a cross-sectional study. At our institute, we provide HTLV-1 testing to relatives of HTLV-1-infected people and patients with suspected HTLV-1-associated diseases. The diagnosis of onychodystrophy was made clinically before testing for HTLV-1; the number and distribution of affected nails was registered. We assessed the association between onychodystrophy and HTLV-1 through bi- and multivariable analyses. Logistic regression was used to adjust for age, sex, and indication for HTLV-1 testing, using six affected nails (90(th) percentile) as the cut-off point.

RESULTS

Between April 2006 and March 2008, we included 893 subjects; their mean age was 38 years (standard deviation 19 years), and 527 (59%) were women. Onychodystrophy of one or more nails was observed in 323 participants (36%), and 236 subjects (26%) were HTLV-1-positive. The median number of affected nails was higher in HTLV-1-positive than in HTLV-1-negative subjects (Mann-Whitney test, p < 0.001). Thirty-eight of 97 subjects with six or more affected nails (39%) were HTLV-1-infected, compared to 198 of 796 subjects with fewer than six affected nails (25%) (crude OR 1.9, 95% confidence interval (CI) 1.2-3.1; p = 0.003). This association remained significant in the multiple logistic regression model (adjusted OR 2.0, 95% CI 1.2-3.3; p = 0.005).

CONCLUSIONS

There is an independent association between HTLV-1 infection and onychodystrophy. Patients with an HTLV-1 infection might have a higher risk for onychomycosis given the abnormal nail plate and a decreased T-cell-mediated immunologic response.

Characterization of the cellular immunity in patients presenting extensive dermatophytoses due to Trichophyton rubrum

Dermatophytes invade the stratum corneum of the skin and other keratinized tissues such as hair and nails, and Trichophyton rubrum causes approximately 80% of cutaneous mycoses in humans. To evaluate the cellular immune response of patients with extensive dermatophytosis caused by T. rubrum, we evaluated lymphocyte populations, the lymphoproliferative response to: phytohaemagglutinin (PHA); anti-CD3 (OKT3); and pokeweed mitogen (PWM), Candida sp. (CMA), an extract of T. rubrum, and the main fungal epitope TriR2 (T). We also evaluated interleukin (IL)-4, IL-10, IL-12 and IFN-γ after stimulation by PHA, CMA and TriR2. The immunophenotyping showed no differences between patients and controls. The lymphoproliferation test showed significant differences between the groups stimulated by PWM and CMA, as well as against TriR2, being significantly higher for the control group. Conversely, there were similar results for the groups after stimulation by the extract. The cytokines' quantification showed a significant difference between the groups only for IFN-γ stimulated by PHA and TriR2. We can conclude that the fungal extract can stimulate lymphoproliferation by both groups' lymphocytes. However, the response to Tri r2 was more specific. We showed that some patients with extensive dermatophytosis have normal cellular response, recognising both the extract and TriR2.

Antifungal activities of Astragalus verus Olivier. against Trichophyton verrucosum on in vitro and in vivo guinea pig model of dermatophytosis

Astragalus verus Olivier, Fabaceae has been used against ringworm in Kurdish ethnomedicine throughout millennia. The objective of this study was to evaluate the effects of A. verus extracts against Trichophyton verrucosum on in vitro and in vivo guinea pig model of dermatophytosis. The skin of albino guinea pigs was infected with T. verrucosum (1.0×10(7) conidia) and animals were divided into five groups (n=5 for each): negative control (NC), received a vehicle; positive control (PC), received topical terbinafine 1.0% and three other groups: AE10%, AE20% and AE40% which received topical 10%, 20% and 40% aqueous extract of A. verus, respectively. Evaluation of clinical efficacy was performed 72h after completion of a 7-day treatment regimen. Higher significant antifungal activities were observed in aqueous extract in the concentration 320 mg ml(-1) compared with acetone and methanol extracts. The aqueous extract showed minimum inhibitory concentration at 160 mg ml(-1) . Lower clinical scores indicate improved efficacy compared with NC. The lesion scores significantly declined in AE20%, AE40% and PC groups in comparison with NC group. The lesion scores in AE10% and AE20% groups were significantly higher than that of PC group. The AE10% group (18.3%) and AE20% group (39.43%) and AE40% group (66.19%) showed clinical efficacies compared with PC group (76.05%). In conclusion, aqueous extract showed promising antidermatophytic activity.

Pathogenesis of dermatophytoses

Dermatophytes can survive solely on outer cornified layers of the skin. The ability of certain fungi to adhere to particular host arises from numerous mechanisms and host factors, including the ability to adapt to the human body. Natural infection is acquired by the deposition of viable arthrospores or hyphae on the surface of the susceptible individual. After the inoculation in the host skin, suitable conditions favor the infection to progress through the stages of adherence and penetration. Development of host response is mostly by a T-cell mediated response of delayed-type hypersensitivity. Antibody formation does not seem to be protective. Natural defenses against dermatophytes depend on both immunological and nonimmunological mechanisms.

Pathogenesis of dermatophytosis and tinea versicolor

Dermatophytoses are infections caused by keratinophilic fungi known as dermatophytes. Several steps are required for infection to take place: contact, adherence, and invasion of keratin layers. The severity of the infection depends on the type of agent, environmental factors, and the host immunologic status. Tinea versicolor is caused by the Malassezia spp yeasts, which are microorganisms that belong to normal biota in seborrheic areas, but some contributing factors, such as the application of oily preparations, creams, an increase in ambient humidity, corticosteroid abuse, or genetic predisposition can induce its overgrowth in both filamentous and yeast structures. Exposure to sunlight stimulates the production of azelaic acid, which causes the appearance of hypopigmented spots. Currently, there is no scientific explanation for hyperpigmented lesions.

Molecular defects in the mannose binding lectin pathway in dermatological disease: Case report and literature review

Mannose-binding lectin (MBL) and the Mannose-binding lectin-associated serine proteases (MASPs) are an essential aspect of innate immune responses that probably play an important but understudied role in cutaneous function. The MBL-MASP pathway appears to exert its primary role by assisting in the clearance of apoptotic skin cells (thus preventing accumulation and a subsequent autoimmune response) and promoting opsonophagocytosis of invading pathogens, limiting their dissemination. Deficiencies of the pathway have been described and are associated with infectious, autoimmune and vascular complications. However, the role of this pathway in dermatological disease is essentially unexplored. We describe 6 patients presenting with recurrent inflammatory and/or infectious skin conditions who also demonstrated severely low MBL levels. One patient also had a defect in the MASP2 gene. Genotype analysis revealed specific point mutations in the MBL2 promoter in all 6 patients and a variant MASP-2 gene in one patient. Five patients presented recurrent pustular skin infections (cellulitis, folliculitis and cutaneous abscess). A case of Grover's disease and one forme fruste of Behcet's syndrome (orogenital ulcers) were also observed. The patients responded to antimicrobial therapy, although in some, recurrence of infection was the rule. It appears that MBL deficiency may contribute to recurrent skin infections and to certain forms of inflammatory skin disease. The mechanisms may relate to the role of this pathway in innate immunity, removal of apoptotic cells and in immune complexes. Further study of MBL pathway defects in dermatological disease is required.

CD4+ and CD8+ T cells mediated direct cytotoxic effect against Trichophyton rubrum and Trichophyton mentagrophytes

BACKGROUND

The cellular immune system is the most dominant factor in curing acute dermatophytosis. However, the exact immune mechanisms involved in generating this defense are complex and still obscure. The aim of this study was to investigate the fungicidal mechanism of T cells in the normal population versus patients with chronic fungal infections.

METHODS

Thirty patients were included in the study: 15 patients with chronic dermatophytosis and 15 normal healthy patients with a history of acute dermatophytosis. The procedures were performed as follows. 1) Proliferation and cytotoxic activity of lymphocytes cultured with various dermatophytes homogenate such as, Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum gypseum. 2) CD4(+) and CD8(+) T cells were separated by magnetic beads before culture with fresh spores of either T. mentagrophytes or T. rubrum. 3) Routine histology and ultrastructural study were performed to illustrate the mode of activity of the T cells against the dermatophytes.

RESULTS

The study showed that both CD4 and CD8 possess cytotoxic activity against dermatophytes. However, the results demonstrated a suppression of lymphocyte proliferation response and a significant lower cytotoxic effect in chronic patients. Ultra structure and histological evaluation of the culture of hyphae with CD4(+) or CD8(+) T cells showed more prominently destructive effects in the culture of cells that had been obtained from normal population than those of patients with long-lasting fungal infections.

CONCLUSION

The study suggests a selective impairment of lymphocyte function against dermatophytes, in patients with chronic dermatophytoses.

[Multicentric and localized tineas in immunocompromised patients]

From the dermatological point of view, multifocal or multicentric tineas are widespread dermatophytic infections affecting two or more anatomical areas. In the immunosuppressed patient, these lesions are frequently atypical and the risk factors are not well established. The aims of this study were: to determine the risk factors associated to multicentric tinea in immunocompromised patients; to evaluate the immune response by trichophytin and candidin skin test, to determine the etiological agent and to quantify some serum interleukines. Thirty-six multicentric tinea and 37 localized tinea patients, both with immunocompromised factors, were included. By means of a questionnaire several risk factors were identified; the trichophytin and candidin skin test was evaluated after 48 hours. Mycological direct examination and culture were performed. The interleukins IL-2, IL-4, IL-10 and interferon gamma were quantified by ELISA. Statistical analysis was made by Chi-square, U Mann Whitney and logistic regression. In disseminated tinea patients a predominance of females (69%) versus localized tinea patients (30%) was observed. Prednisone, azathioprine and cyclophosphamide treatment was associated to multicentric tinea. Trichophytin was negative in all disseminated tinea patients and positive in only three localized tinea cases, candidin was positive in six and eight cases of multicentric and localized tinea respectively. Trichophyton rubrum was the most frequent etiological agent. No differences in interleukin concentrations were found. Female gender and some immunosuppressor treatments were associated with a high probability to develop multicentric tinea. In this study a defect in the cellular immune response was the possible explanation for the extensive reactions.

Effective treatment for dermatophytoses of the foot: effect on restoration of depressed cell-mediated immunity

Superficial infections caused by dermatophyte fungi are highly prevalent throughout the world. Modern antimycotic agents like the azole itraconazole or the synthetic allylamine terbinafine greatly improved treatment outcomes in comparison with former therapeutic options with griseofulvin or older azole preparations like ketoconazole or fluconazole. In randomized trials involving patients with dermotophytoses, a great effectiveness has been shown especially for terbinafine. Oral terbinafine in general is well tolerated, has a low potential for drug interactions and, therefore, may be the most often used therapeutic agent for dermatophyte onychomycosis. However, there is a group of patients suffering from chronic dermatophytoses or early reinfections after antifungal therapy. For these patients, a depression of the delayed-type hypersensitivity reactivity was postulated. Just recently, effective antimycotic treatment, in particular with terbinafine, was shown to enhance and restore cell-mediated immunity, which potentially improves the therapeutic outcome even for this group of patients.

Topical therapy for dermatophytoses: should corticosteroids be included?

Dermatophytoses, commonly known as ringworm or tinea, represent superficial fungal infections caused by dermatophytes, which are among the most common infections encountered in medicine. The use of corticosteroid-containing combinations in dermatophyte infections that are usually treated with topical medications is still a much-debated issue. The addition of a corticosteroid to local antifungal therapy may be of value in reducing local inflammatory reaction and thus carries the theoretical advantage of rapid symptom relief in acute dermatophyte infections associated with heavy inflammation. However, the use of such combinations requires caution as they have some potential risks, especially with long-term use under occlusive conditions. Corticosteroid-induced cutaneous adverse effects have been reported primarily in pediatric patients due to inappropriate application of these preparations on diaper areas. Additionally, the corticosteroid component may interfere with the therapeutic actions of the antifungal agent, or fungal growth may accelerate because of decreased local immunologic host reaction, such that underlying infection may persist, and dermatophytes may even acquire the ability to invade deeper tissues. Analysis of the literature documenting clinical study data and adverse reactions related to combination therapy, drew the following conclusions: (i) combination products containing a low potency nonfluorinated corticosteroid may initially be used for symptomatic inflamed lesions of tinea pedis, tinea corporis, and tinea cruris, in otherwise healthy adults with good compliance; (ii) therapy should be substituted by a pure antifungal agent once symptoms are relieved, and should never exceed 2 weeks for tinea cruris and 4 weeks for tinea pedis/corporis; and (iii) contraindications for the use of these combinations include application on diaper or other occluded areas and facial lesions, as well as in children <12 years of age and in immunosuppressed patients for any reason.

Tinea imbricata or Tokelau

Tinea imbricata (TI) or Tokelau is a superficial mycosis caused by Trichophyton concentricum, an anthropophilic dermatophyte. It is endemic in some islands of the South Pacific (Polynesia), South-East Asia, Central and South America, and Mexico, and is most often seen in individuals living in primitive and isolated conditions. The skin lesions are characteristically concentric and lamellar (imbricata: in Latin, tiled) plaques of scale. Predisposing conditions include humidity, inheritance, and immunologic factors. The diagnosis is usually made on clinical grounds, supported by skin scrapings and culture. Tokelau is a chronic and highly relapsing disease and, although no first-line treatment exists, best results are obtained with oral griseofulvin and terbinafine and a topical combination of keratolytic ointments, such as Whitfield's. TI is a disease model that allows the correlation of a series of environmental, genetic, immunologic, and therapeutic conditions.

Fungal diseases in small mammals: therapeutic trends and zoonotic considerations

As medical knowledge continues to expand, the division between animal and human diseases continues to decrease. The popularity of small mammals in lieu of the increased numbers of immunocompromised individuals will require increasingly broader understandings of zoonotic disease. The vast amount of animal research in areas of human disease requires diligent study to stay abreast of emerging diagnostics and therapeutics. The core requirements of skin scrapings, fungal culture, and microscopy for the diagnosis of small mammal fungal disease, however, are unchanged.

Onychomycosis: strategies to improve efficacy and reduce recurrence

Fungal infections may be difficult to treat for several reasons. It is important to obtain the correct diagnosis, and select the appropriate antifungal agent and route. General considerations that may be associated with recurrent infections are, a genetic predisposition and suboptimal bioavailability of drug, resulting in insufficient concentration at the target site. The aetiologic organism, the severity of disease, other coexisting diseases, concomitant drug intake, and the presence of fungal infection at other sites are some factors that determine the choice of antifungal therapy and its route of administration, oral vs. topical lacquer. Local factors such as the thickness of the nail, presence of lateral onychomycosis, longitudinal spike, dermatophytoma and severe onycholysis are some factors that may determine the choice of secondary measures such as mechanical or topical treatment. Booster or supplemental therapy may be of benefit when the response to initial treatment is poorer than expected and unlikely to result in complete response. Steps should be taken to reduce the possibility of recurrence once cure has been achieved.

Effect of lactoferrin feeding on the host antifungal response in guinea-pigs infected or immunised with Trichophyton mentagrophytes

Earlier studies revealed that oral administration of lactoferrin (LF), a multi-functional milk protein, facilitated curing of dermatophytosis in guinea-pigs and man by an unknown mechanism. The present study aimed to assess the effect of feeding bovine LF on the host antifungal defence systems in guinea-pigs infected or immunised with Trichophyton mentagrophytes, a dermatophytosis-causing fungus. The unbound iron-binding capacity (UIBC) of the plasma of individual animals varied, and plasma with higher UIBC inhibited growth of T. mentagrophytes in vitro. However, LF administration did not enhance plasma UIBC or the anti-T. mentagrophytes activity of plasma in infected or uninfected animals. Phagocytic activity and reactive oxygen (RO) production of blood neutrophil polymorphonuclear leucocytes (PMNLs) were estimated by flow cytometry. LF administration caused no significant effects on phagocytic activity or RO production of neutrophil PMNLs in infected or uninfected animals. The functions of mononuclear cells (MNC) from the spleen were investigated in guinea-pigs immunised with heat-killed T. mentagrophytes conidia. The MNC were cultured with concanavalin A or inactivated T. mentagrophytes. In the bromo-deoxyuridine incorporation assay, the stimulation index was higher for MNC derived from LF-treated animals than for those from control animals. The culture supernates of MNC enhanced the ability of macrophages to kill T. mentagrophytes conidia. Furthermore, stronger augmentation was observed with the culture supernate from LF-treated animals than with that from control animals. In conclusion, LF feeding may potentiate the host antifungal defence systems by modulating MNC function rather than plasma antifungal activity or peripheral blood neutrophil PMNL activity.

Reactivity to trichophytin antigen in patients with onychomycosis: effect of terbinafine

BACKGROUND

Many patients with chronic dermatophytosis and onychomycosis have depressed cell-mediated immunity (CMI) to trichophytin.

OBJECTIVE

The fungicidal properties of oral terbinafine provide a unique opportunity to explore whether elimination of antigen could restore CMI response in these patients.

METHODS

A double-blind, placebo-controlled study evaluated the effect of terbinafine (250 mg/d for 12 weeks) on skin immunoreactivity to intradermal trichophytin antigen (TRIPA), mycologic status of the nail, and nail growth in patients with toenail onychomycosis.

RESULTS

Skin reactivity, in an optimized, dose response challenge series to TRIPA was inversely related to disease chronicity. Mycologic/clinical response rates were 72%/84% for terbinafine and 0%/7% for placebo. Terbinafine increased the number of TRIPA reactors 2-fold and the mean TRIPA reaction area 4-fold; responses in placebo-treated patients were relatively unchanged. Of the 7 (of 25) patients receiving terbinafine who still had positive mycology 6 months after treatment, all were anergic to TRIPA at baseline and all but one remained so after treatment.

CONCLUSION

Terbinafine treatment enhances and restores CMI to TRIPA in patients with Trichophyton rubrum onychomycosis and may thereby reduce susceptibility to reinfection. Terbinafine reversal of immunologic anergy may be an important model of microbial tolerance in chronic dermatophyte infections.

Immunohistochemical analysis of the infiltrated cells in tinea capitis patients

Tinea capitis is a fungal infection of the skin and the hair with involvement of the hair shaft and the pilosebaceous unit. It may be the most common of all cutaneous mycoses in children. Tinea capitis can be inflammatory or noninflammatory. It is thought that humoral and cell-mediated immunities play a role in the formation of the clinical types of the disease. We studied twelve patients with acute inflammatory disease, four patients with chronic non-inflammatory disease, and one patient with a black-dot variant of tinea capitis. The composition of inflammatory infiltrates present in lesional skin was analyzed by antibodies to T cells (CD3) and B cells (CD20). Anti-CD3 revealed large numbers of T cells in twelve patients with acute, inflammatory dermatophytosis, whereas anti-CD20 revealed marked infiltrates of both B and T cells in all patients with chronic, non-inflammatory dermatophytosis. As a result, we thought that cell-mediated immunity might play a role in the acute, inflammatory type of tinea capitis and that humoral immunity might do so in the chronic, non-inflammatory type of tinea capitis.

Evaluation of lymphocytes subpopulations and natural killer cells in peripheral blood of patients treated for dermatophyte onychomycosis

Thirty-five patients with dermatophyte onychomycosis caused by Trichophyton rubrum, T. mentagrophytes var. granulosum, T. tonsurans and Epidermophyton floccosum were examined before treatment and 27 of these patients were examined again when they came to the control check up 3 months after completion of treatment. The immunological investigations, including evaluation of immunological competence, were performed in vivo through the determination of lymphoid cell immunophenotype by a flow cytometry technique. The quantitative composition of basic lymphocyte subpopulations and natural killer cells in the peripheral blood of 35 patients before the treatment was compared with a control group of 20 individuals. Statistically significant differences in the percentages of CD3+ T lymphocytes (P<0.05), T helper lymphocytes (CD4+) (P<0.05) and activated T lymphocytes (CD3+/HLA-DR+) (P<0.05) were obtained. In the control check-up examinations of 27 patients 3 months after completion of treatment, in comparison with the control group of 20 healthy individuals, highly statistically significant differences in percehtages of T lymphocytes (CD3+) (P<0.001) and T helper lymphocytes (CD4+) (P<0.01) were obtained. In five of these 27 patients the treatment resulted in failure. Comparing the group of 22 recovered patients with these five patients in whom the treatment result was failure, the only statistically significant difference obtained before as well as after the treatment was in B lymphocytes (CD19+) percentage (P<0.05). The results obtained confirm that impairments of the patients' cellular immunity are crucial factors influencing the course and results of treatment in dermatophyte onychomycosis.

Immunoglobulin-E-bearing cells in skin biopsies of horses with insect bite hypersensitivity

The aim of the present study was to investigate, with immunohistochemistry and in situ hybridisation, if immunoglobulin-E (IgE) and mast cells are involved in the pathogenesis of insect bite hypersensitivity (IBH), an allergic dermatitis of horses. In tissue sections fixed in paraformaldehyde (PFA) for <24 h, significantly more IgE protein-bearing cells were found in the dermis and epidermis of acute and chronic IBH lesions than in skin biopsies from healthy horses (medians = 466, 236 and 110 cells/mm2, respectively; P < or = 0.01). More IgE-mRNA positive (+) cells were observed in the dermis of acute IBH lesions than in the dermis of healthy skin (median = 2.8 vs. 0.0 cells/mm2; P < or = 0.01). Significantly, more mast cells were detected with metachromatic (median = 160 vs. 62 cells/mm2; P < or = 0.001) and tryptase-specific stainings (median = 120 vs. 69 cells/mm2; P < or = 0.001) in the dermis of acute IBH biopsies compared to healthy skin. No chymase+ mast cells were found in any skin biopsy. IBH lesions fixed in PFA for >24 h were compared to dermatomycosis (DM) lesions; IBH biopsies contained a similar number of IgE-protein+ cells to DM biopsies (median = 249 vs. 192 cells/mm2; P = 0.08) but had significantly more IgE-mRNA+, metachromatic and tryptase+ mast cells than DM biopsies. This study suggests an involvement of IgE-mediated immune reactions in the pathogenesis of IBH as well as, sometimes, in dermatomycosis. Using double labelling, cells which expressed IgE protein and contained mast cell enzymes were detected.

Interferon-gamma production in peripheral lymphocytes of patients with tinea pedis: comparison of patients with and without tinea unguium

The precise mechanism of the host defense that protects the nail from dermatophyte invasion is not known. Recent immunological findings in dermatophytosis suggest the hypothesis that the T helper 1 (Th1) response may play a role in protecting the nail from dermatophyte invasion. Our present study focused on interferon-gamma (IFN-gamma) release in patients with tinea pedis with or without tinea unguium, and pathogenesis of tinea unguium is discussed in relation to the association with a possible deficiency of Th1 response in the host defense mechanism. The production of IFN-gamma by peripheral blood mononuclear cells from the patients with tinea unguium in response to stimulation with trichophytin was not impaired in contrast to that from the patients without tinea unguium. Comparable lymphocyte proliferation to trichophytin was observed in both groups. Normal healthy persons with no clinical evidence of tinea could be divided into two groups based on lymphocyte proliferation and IFN-gamma production in response to trichophytin: high responder and low responder, with high responders being correlated with a clinical history of previous tinea pedis. In this study, a lack of a Th1 response to dermatophyte antigen was not shown in patients with tinea unguium by measuring the release of IFN-gamma, which plays a role in the effector phase of the delayed-type hypersensitivity reaction. A deficiency in the Th1 response to dermatophyte antigen, therefore, does not appear to play an important role in the establishment of tinea unguium.

Experimental dermatophytosis in hamsters inoculated with Trichophyton mentagrophytes in the cheek pouch

This study presents the results of T. mentagrophytes inoculation in the cheek pouch of the hamster, an immunologically privileged site. Forty two animals were used: 21 inoculated with 10(6) fungi in the cheek pouch (group 1) and 21 inoculated initially with 10(6) fungi in the foot pad and 15 days later in the cheek pouch, with the same amount of fungi (group 2). Animals were sacrificed at 20 hours, 3, 7, 14, 30, 60, and 120 days; samples from inoculated cheek pouch, and foot pads submitted to the foot pad test (FPT), were collected. Independent of group and time of evolution of infection, animals did not develop delayed hypersensitivity evaluated through the FPT. The pre-inoculation of fungi in the foot pad did not change the morphology of lesions induced in the cheek pouch. Therefore, in animals of group 1 and 2, the introduction of the fungus in the cheek pouch resulted in focal lesion composed of a sterile acute inflammatory infiltrate, with abscess formation that evolved to a macrophagic reaction, and later to resolution even in the absence of immune response detectable by FPT. Our results indicate that in spite of the important role of the immune response in the spontaneous regression of dermatophytosis, other factors are also an integral part in the defense against this fungal infection.

Lactoferrin given in food facilitates dermatophytosis cure in guinea pig models

Dermatophytosis is the most common skin infection caused by dermatophytic fungi, such as Trichophyton spp. We studied the in vitro and in vivo antifungal effects of lactoferrin against Trichophyton. Human and bovine lactoferrin, and a bovine lactoferrin-derived peptide, lactoferricin B, showed in vitro antifungal activity that was dependent on the test strain and medium used. In guinea pigs infected on the back with Trichophyton mentagrophytes (i.e. those with tinea corporis), consecutive daily po administration of bovine lactoferrin did not prevent development of symptoms during the early phase of infection, but facilitated clinical improvement of skin lesions after the peak of the symptoms. The fungal burden in lesions was less in guinea pigs that had been given lactoferrin than in untreated controls 21 days after infection. In guinea pigs infected on the foot with T. mentagrophytes (i.e. those with tinea pedis), the fungal burden of the skin on the heel portion of the infected foot 35 days after infection was lower in animals fed lactoferrin than in controls. These results suggest the potential usefulness of lactoferrin as a food component for promoting dermatophytosis cure.

Detection by ELISA of the humoral immune response in rabbits naturally infected with Trichophyton mentagrophytes

An indirect enzyme linked immunosorbent assay (ELISA) was developed and its diagnostic potential evaluated for rabbits infected by Trichophyton mentagrophytes. Within-run and between-run coefficient of variance varied from 2.3 to 7.7% and from 5.9 to 8.5%, respectively, indicating satisfactory reproducibility of the ELISA. There was no significant cross-reaction with antigens of Microsporum canis, Malassezia pachydermatis and Aspergillus fumigatus. The level of specific IgG to Trichophyton mentagrophytes was measured in sera of 25 11-week-old and 12 younger infected rabbits. There was no significant difference in the IgG level between 12 5-week-old infected rabbits and controls (p = 0.38). The antibody response was higher in 12 7-week-old rabbits compared with controls (p = 0.001). The IgG level in 25 11-week-old rabbits differed from the controls very significantly (p < 0.0001). Increased specific IgG in 11-week-old rabbits exhibited 96% sensitivity and 94% specificity. Predictive values of a positive and a negative test were 96 and 94%, respectively. Western immunoblotting associated three protein bands (21.5, 31, 44 kDa) with Trichophyton mentagrophytes infection.

Unique inflammatory features noted in intraorally transferred skin flaps: correlation with Candida albicans infection

OBJECTIVE

The purpose of this study was to evaluate how well intraorally transferred skin flaps endure their new surroundings.

STUDY DESIGN

Biopsy specimens were taken from 20 patients who had undergone microsurgical reconstruction and as pretransferred skin from 5 of these patients at the time of surgery. The study used immunohistochemistry for immunocompetent cells, differentiation markers for the epidermis and desmosomal proteins, and immunoelectron microscopy for desmosomal protein, in addition to routine histologic examination, including Sudan IV, periodic acid Schiff, and Grocott stains. We also measured the thickness of the epidermis and stratum corneum. Oral swabs from the skin flaps were examined for the presence of yeasts, particularly Candida albicans, by means of a culture method.

RESULTS

According to the results of periodic acid-Schiff and Grocott staining, 20 cases were divided into 2 groups: fungal element-positive cases (n = 15) and fungal element-negative cases (n = 5). All swabs from the former were positive for Candida albicans. In these fungus-positive cases, histopathologic evaluation revealed marked diminution of stratum corneum and pronounced epidermal hyperplasia. Immunohistochemistry demonstrated the dermal infiltration of numerous immunocompetent cells-CD4+, CD8+, CD20+, CD68+, neutrophil elastase+, and HLA-DR+ cells-and the scarce infiltration of IgA+ and IgG+ cells. There were scattered CD1a+, CD4+, CD8+, and HLA-DR+ cells and elastase+ neutrophils in the epidermis. Expression of cytokeratin subtypes (10, 14, 16, and 19), involucrin, and tenascin showed the characteristic features of epidermal proliferation. Enumeration of Ki-67+ keratinocytes showed an increase, indicating epidermal proliferation. Expression of desmoglein 1 and desmocollin 1 in the epidermal keratinocytes was decreased in comparison with that in the pretransferred skin. Immunoelectron microscopy for desmoglein 1 confirmed the reduced immunoreactive deposits along the desmosomal plaques. In the fungus-negative cases, all such changes were a great deal milder.

CONCLUSIONS

Taken together, our results demonstrate that most intraorally transferred flaps are affected by an inflammatory process that is induced by the influence of the wet oral environment. They present psoriasiform tissue reactions characterized by epidermal hyperproliferation that are mostly due to Candida albicans infection.

Factors that may affect the response of onychomycosis to oral antifungal therapy

With the advent of the newer oral antifungals available to treat onychomycosis, the majority of patients respond to therapy. However, there may be subsets of patients who exhibit poor response or failure. Possible explanations for this may be grouped into categories, including: (i) patient characteristics; (ii) organisms causing or associated with the nail infection; (iii) nail characteristics; and (iv) local diseases involving the nail.

Imbalance of immune responses in patients with chronic and widespread fungal skin infection

Fungal infections of the skin are caused by dermatophyte fungi. Infections can be acute and inflammatory or chronic and non-inflammatory; it is believed that cell-mediated immunity is the cornerstone of host defence and is instrumental in the eradication of the infection. We describe here parameters of the immune response of a group of patients who although not immunocompromised, suffered from widespread and chronic infections. All patients lacked a specific delayed-type hypersensitivity (DTH) response; however, their in vitro lymphocyte proliferation in response to Trichophyton rubrum extract and to other fungal antigens was normal. The patients were not atopic by clinical history, and yet had high levels of non-specific IgE and of T. rubrum-specific IgG4. Taken together, the results of this study suggest that the group of patients studied suffered from an immune imbalance which has characteristics of a Th2-type response.