HLA-A29 and genetic susceptibility to chromoblastomycosis

Chromoblastomycosis in Latin America and the Caribbean: epidemiology over the past 50 years

Chromoblastomycosis is a chronic disease caused by melanized fungi that mainly affect individuals performing soil-related labour. The objective of this study was to analyse the epidemiological and clinical characteristics of chromoblastomycosis in Latin America and the Caribbean by an extensive literature review. An integrative review was performed of English, French, Portuguese, and Spanish publications in LILACS, SciELO, PubMed, SCOPUS and Web of Science databases covering the period 1969-2019. A total of 1,211 articles were identified, of which 132 were included in the review, covering 2,081 patients, 80.3% were male, the mean age was 56.1 years. The mean duration of the disease was 10.8 years. The lesions were mainly described in the lower limbs (60%). The most frequent clinical forms were verrucous (46.4%) and tumorous (21.7%). Major disease symptoms and signs consisted of itching and pain. Bacterial infection and functional limitation were important complications. Immunosuppression post-kidney transplantation was the most frequent comorbidity while leprosy was the main concomitant infectious disease. Fonsecaea pedrosoi and Cladophialophora carrionii were the predominant etiological agents. Majority of the cured cases were treated with itraconazole as monotherapy or in combination with other antifungals, surgery or cryosurgery. Chromoblastomycosis affects hundreds of rural workers in Latin America and the Caribbean, causing disability and personal, family and economic losses. It is important to prioritize epidemiological surveillance and early diagnosis of this disease in order to reveal its real prevalence and direct resources to preventive actions, diagnosis and early treatment.

LAY SUMMARY

Chromoblastomycosis is a slowly progressing chronic disease caused by melanized fungi. We collected data from South America and the Caribbean covering 1969-2019, the 132 articles included 2 081 patients, mean disease duration was 10.8 years. Fonsecaea pedrosoi and Cladophialophora carrionii predominated.

Host genetic susceptibility to mycetoma

Mycetoma is one of the badly neglected tropical diseases, characterised by subcutaneous painless swelling, multiple sinuses, and discharge containing aggregates of the infecting organism known as grains. Risk factors conferring susceptibility to mycetoma include environmental factors and pathogen factors such as virulence and the infecting dose, in addition to host factors such as immunological and genetic predisposition. Epidemiological evidence suggests that host genetic factors may regulate susceptibility to mycetoma and other fungal infections, but they are likely to be complex genetic traits in which multiple genes interact with each other and environmental factors, as well as the pathogen, to cause disease. This paper reviews what is known about genetic predisposition to fungal infections that might be relevant to mycetoma, as well as all studies carried out to explore host genetic susceptibility to mycetoma. Most studies were investigating polymorphisms in candidate genes related to the host immune response. A total of 13 genes had allelic variants found to be associated with mycetoma, and these genes lie in different pathways and systems such as innate and adaptive immune systems, sex hormone biosynthesis, and some genes coding for host enzymes. None of these studies have been replicated. Advances in genomic science and the supporting technology have paved the way for large-scale genome-wide association and next generation sequencing (NGS) studies, underpinning a new strategy to systematically interrogate the genome for variants associated with mycetoma. Dissecting the contribution of host genetic variation to susceptibility to mycetoma will enable the identification of pathways that are potential targets for new treatments for mycetoma and will also enhance the ability to stratify ‘at-risk’ individuals, allowing the possibility of developing preventive and personalised clinical care strategies in the future.

Molecular identification of chromoblastomycosis clinical isolates in Guangdong

Chromoblastomycosis is a chronic fungal infection of the skin and subcutaneous tissue. The most common etiologic agent encountered in Southern China is from the genus Fonsecaea. Fonsecaea species are often misidentified due to indistinct morphology features; furthermore, recent taxonomy revision was done on the fungi genus. Herein, a comprehensive evaluation with molecular sequencing data based on internal transcribed spacer (ITS) ribosomal DNA regions as molecular targets were implemented to 37 clinical isolates from chromoblastomycosis patients. Twenty strains that were formerly identified as Fonsecaea pedrosoi through morphological characteristic were verified to be either Fonsecaea nubica or Fonsecaea monophora, while 17 strains were appropriately identified as F. monophora. A phylogenetic method was further performed to establish the species delimitation. Our investigations validate that the clinical isolates from Guangdong consist of F. monophora and the recently found new species, F. nubica. In this study, F. pedrosoi has not been isolated from chromoblastomycosis patients in Guangdong, Southern China. Reevaluation of previous reports regarding F. pedrosoi as chromoblastomycosis etiologic agent in China is necessary for a comprehensive assessment of geographic distribution pattern of Fonsecaea species. This study is the first reported study presenting large samples of F. nubica domestic or abroad.

Chromoblastomycosis

Chromoblastomycosis (CBM), also known as chromomycosis, is one of the most prevalent implantation fungal infections, being the most common of the gamut of mycoses caused by melanized or brown-pigmented fungi. CBM is mainly a tropical or subtropical disease that may affect individuals with certain risk factors around the world. The following characteristics are associated with this disease: (i) traumatic inoculation by implantation from an environmental source, leading to an initial cutaneous lesion at the inoculation site; (ii) chronic and progressive cutaneous and subcutaneous tissular involvement associated with fibrotic and granulomatous reactions associated with microabscesses and often with tissue proliferation; (iii) a nonprotective T helper type 2 (Th2) immune response with ineffective humoral involvement; and (iv) the presence of muriform (sclerotic) cells embedded in the affected tissue. CBM lesions are clinically polymorphic and are commonly misdiagnosed as various other infectious and noninfectious diseases. In its more severe clinical forms, CBM may cause an incapacity for labor due to fibrotic sequelae and also due to a series of clinical complications, and if not recognized at an early stage, this disease can be refractory to antifungal therapy.

Mycetoma-like chromoblastomycosis: a diagnostic dilemma

OBJECTIVES

Mycetoma and chromoblastomycosis are subcutaneous fungal infections caused by pigmented fungi, common in the tropics and subtropics. Here we report a pregnant woman who presented with a swelling around the ankle joint which was clinically diagnosed as a case of mycetoma; however, further investigations revealed it to be a case of chromoblastomycosis.

METHODS

24 year old primigravida presented with an indurated swelling around the ankle joint with multiple nodules and sinuses draining serosanguinous discharge. There was no improvement with antibiotic therapy or surgical debridement. Patient was investigated in detail including radiographs, KOH smear, pus culture and biopsy for histopathology and fungal culture.

RESULTS

o grains were identified from the discharge and KOH smear was negative for fungal elements. Pus culture revealed no bacterial growth. On the other hand, histopathology and fungal culture confirmed it to be a case of chromoblastomycosis caused by Fonsecaea pedrosoi. Treatment was initiated with terbinafine 250 mg daily, and patient showed excellent response within 6 months of therapy.

CONCLUSION

This unusual mycetoma-like presentation of chromoblastomycosis has not been previously reported in literature and may be attributed to the altered immune status in pregnancy. This should alert the clinician about the need to be vigilant of the atypical presentations of well-known dermatological conditions, especially in special situations like pregnancy.

Chromoblastomycosis

Chromoblastomycosis is a chronic fungal infection of the skin and subcutaneous tissue. The infection usually results from a traumatic injury and inoculation of microorganism from a specific group of dematiaceous fungi (usually Fonsecaea pedrosoi, Phialophora verrucosa, Cladophialophora carrionii). In the tissues fungi produce characteristic sclerotic cells or muriform cells. Dermal lesions can range from small nodules to large papillary-like eruptions. The disease has been described worldwide but the prevalence is higher in rural populations in countries with a tropical or subtropical climate, such as Madagascar in Africa and Brazil in South America. Diagnostic techniques are based on direct examination, culture and histopathology. Despite a variety of treatment modalities, which include long courses of antifungals, surgical excision and destructive physical therapies, the disease remains one of the most difficult deep mycotic infections to eradicate.

Genetic risk factors for human susceptibility to infections of relevance in dermatology

BACKGROUND

In the pre-microbiological era, it was widely accepted that diseases, today known to be infectious, were hereditary. With the discovery of microorganisms and their role in the pathogenesis of several diseases, it was suggested that exposure to the pathogen was enough to explain infection. Nowadays, it is clear that infection is the result of a complex interplay between pathogen and host, therefore dependant on the genetic make-up of the two organisms. Dermatology offers several examples of infectious diseases in different stages of understanding of their molecular basis. In this review, we summarize the main advances towards dissecting the genetic component controlling human susceptibility to infectious diseases of interest in dermatology. Widely investigated diseases such as leprosy and leishmaniasis are discussed from the genetic perspective of both host and pathogen. Others, such as rare mycobacterioses, fungal infections and syphilis, are presented as good opportunities for research in the field of genetics of infection.

Fungal x host interactions in Chromoblastomycosis: what we have learned from animal models and what is yet to be solved

Animal studies with chromoblastomycosis were initiated together with the first descriptions of the disease. In this editorial commentary, animal models are briefly reviewed, and the available data based on new immunology tools are discussed.

Biology and pathogenesis of Fonsecaea pedrosoi, the major etiologic agent of chromoblastomycosis

Fonsecaea pedrosoi is the principal etiologic agent of chromoblastomycosis, a fungal disease whose pathogenic events are poorly understood. Treatment of the disease presents poor effectiveness and serious side effects. The disease is epidemiologically important in several regions, which has stimulated studies focused on the biology and pathogenic potential of its major causative agent. In this review, we summarize the current knowledge on the biological aspects of F. pedrosoi, including cell differentiation and pathogenic mechanisms during the interaction of fungi with different hosts' elements.

Chromoblastomycosis

Chromoblastomycosis is a chronic subcutaneous mycotic infection caused by pigmented or dematiaceous saprophytic moulds ubiquitous in the environment. The most common etiologic agents are Fonsecaea pedrosoi and Cladophialophora carrionii, both of which can be isolated from plant debris. The infection usually follows traumatic inoculation through penetrating thorn or splinter wounds. The fungal agents develop as small clusters of cells known as muriform bodies. Several months after the injury, painless papules or nodules appear in the affected area progressing to scaly and verrucose plaques. Direct examinations of skin scrapings or histopathologic study demonstrates the typical muriform bodies. Microbiologic culture is necessary for the correct determination of the etiologic agent. Itraconazole is the treatment of choice, often in combination with surgery. Even so, results are often unsatisfactory as patients present late to medical services because of lack of funds and the fact that the disease usually affects the main family earner.

Generic human leukocyte antigen class II (DRB1 and DQB1) alleles in patients with paracoccidioidomycosis

Human leukocyte antigen (HLA) class II alleles are involved in antigen processing and in the presentation of antigens to T lymphocytes. Few studies have investigated HLA genes in paracoccidioidomycosis. In the present investigation, we analyzed the distribution of the HLA class II alleles DRB1 and DQB1 in 45 healthy volunteers and in 80 patients with paracoccidioidomycosis. The patients presented with various clinical forms of the disease, and allele distribution was evaluated individually in each presentation type. In patients with the unifocal chronic form of the disease, a mild clinical presentation in which lesions are restricted or localized, the HLA allele most commonly seen was DRB1*11 (p<0.039). This suggests that the participation of HLA antigens may influence the outcome of the host-parasite interaction in paracoccidioidomycosis, regulating the immune response to Paracoccidioides brasiliensis antigens.

Human leukocyte antigen class I and MICA haplotypes in a multicase family with Cladophialophora carrionii chromoblastomycosis

Previous studies carried out in an endemic semiarid region northwest of Venezuela at Falcon State have shown a prevalence of 15.4/1000 of chromoblastomycosis following traumatisms with xenophile vegetation infected with Cladophialophora carrionii. We performed high-resolution DNA typing of human leukocyte antigen (HLA)-A, -B and -C and major histocompatibility complex class I chain related gene A (MICA) alleles and segregation analysis in 49 members of one extended family with 12 affected individuals, who have lived for approximately 70 years in this endemic zone. None of the alleles, haplotypes or genotypes is shared by all the patients. No deviation from the expected HLA haplotype distribution or association of chromoblastomycosis with HLA-A, -B and -C haplotypes was observed. Further, a haplotype-sharing transmission/disequilibria testing of 11 nuclear families did not give enough evidence to claim linkage (P = 0.398), suggesting that genes located in the short arm of chromosome 6 may not be relevant in the immune response toward infection with C. carrionii in this Venezuelan endemic zone. Deleted MICA alleles on HLA-B*4802 haplotypes were present among several members of the extended family, but only two of them were affected.

Management of chromoblastomycosis: novel perspectives

PURPOSE OF REVIEW

Significant advances in knowledge of chromoblastomycosis and its etiologic agents have been made in the past 5 years. New explanations and approaches that could resolve persisting medical challenges for this orphan disease are reviewed here.

RECENT FINDINGS

In recent years advances have been made regarding the taxonomy and ecoepidemiology of the etiologic agents, basic knowledge of the pathogenesis of the lesions, especially the fibrotic process, and the immunologic response to chromoblastomycosis. Conversely there have been no recent significant advances in knowledge of the genetic polymorphism of the wild isolates or in development of experimental models, impairing the possibility of in-depth clinicopathologic investigations. As a result medical management is dependent on the development of diagnostic and therapeutic tools developed for other fungal diseases.

SUMMARY

Recent findings are applicable in laboratory and medical practice. Benefits can accrue to basic knowledge from data collected on other cutaneous diseases of parasitic or bacterial origin.

Chromoblastomycosis in children and adolescents in the endemic area of the Falcón State, Venezuela

The present paper describes 22 cases of chromoblastomycosis (CBM) caused by Cladophialophora carrionii in children and adolescents (2-19 years old). The patients were seen between 1992 and 2004 and all resided in a CBM endemic area in the semi-arid zone of the Falcón state, Venezuela. Twelve of the 22 patients (54.55%) had close relatives who also had CBM and 19 (86.36%) were male. Lesions consisted of erythematous papules with desquamation or squamous plaques (0.12-14.19 cm in diameter), located primarily on the upper limbs (77.27% of patients). Thirteen of the patients were treated with topical 5-fluorouracil (5-FU; 1% cream), seven with topical ajoene (0.5% gel) and two had electrodesiccation and/or fulguration. Two patients who did not respond to 5-FU were treated with oral itraconazole (100 mg/day for 1 month). Complete clinical and mycological remission was achieved in 17/20 (85%) of the patients treated with 5-FC, ajoene and electrodesiccation and/or fulguration. In addition, similar results were obtained with the two patients who received itraconazole therapy. These cases emphasize the importance of early diagnosis in difficult-to-treat mycotic diseases such as CBM. By early intervention we were able to employ topical treatment with a minimum of adverse effects to achieve a high percentage of favorable therapeutic responses. The patients were thus able to avoid the evolution of the chronic, deforming and incapacitation clinical manifestations associated with CBM.

Subcutaneous mycoses

Subcutaneous mycoses include a heterogeneous group of fungal infections that develop at the site of transcutaneous trauma. Infection slowly evolves as the etiologic agent survives and adapts to the adverse host tissue environment. Diagnosis rests on clinical presentation, histopathology, and culture of the etiologic agents. This article considers sporotrichosis, chromoblastomycosis, and mycetoma.

Lack of association between parenchymal neurocysticercosis and HLA Class I and Class II antigens

Neurocysticercosis, caused by encysted larvae of the tapeworm Taenia solium, is the most common infection of the central nervous system and a major public health problem in many countries. Prevalence in the region of Curitiba, located in the southern Brazilian State of Paraná, is one of the highest in the world. The genetics of host susceptibility to neurocysticercosis (NCC) is still obscure. To investigate if major histocompatibility complex (MHC) genes influence individual susceptibility to NCC, we performed a case-control association analysis. Fifty-two Caucasoid patients and 149 matched controls were typed for antigens of the HLA-A, B, C, DR and DQ loci. All patients had computerized tomography and clinical features compatible with parenchymal NCC. Indirect immunofluorescence of cerebrospinal fluid showed that 19 (37%) of the patients presented anti-cysticercus antibodies at titers <FONT FACE="Symbol">³</font> 1:10. Frequencies of HLA specificities in the whole group of patients and in the subgroup with antibodies in cerebrospinal fluid were compared to those of the control group. No significant difference was found. These results do not support the hypothesis of HLA gene participation in susceptibility to parenchymal neurocysticercosis.

Risk assessment of fungi reported from humans and animals

A classification of fungi into biosafety categories is proposed, and the criteria for attribution to biosafety levels (BSL) are briefly discussed. The list differs from previous publications on this topic mainly by stressing (ecological) criteria derived from the fungi rather than host factors, and in including all species accepted in the recent medical literature.

The syndrome of presumed ocular histoplasmosis in Mexico: a preliminary study

A study to screen for the syndrome of presumed ocular histoplasmosis (SPOH) among native populations from three Mexican states was performed. Two of these states, Guerrero and Querétaro, were selected as histoplasmosis is endemic there, whereas Tlaxcala was considered a control, due to the absence of reported cases. A total of 253 individuals were submitted to ocular fundus examination to obtain evidence of SPOH. A high percentage of positive reactors to histoplasmin skin test (ST) was observed in Guerrero (83%) and Querétaro (53%), whereas in Tlaxcala positive ST were almost absent (2.04%). Only five individuals had retinal lesions, although these lesions were not characteristic of the syndrome. Stimulation of these individual's cells showed different patterns in the histoplasmin-induced lymphocyte transformation response, and two out of five individuals with retinal lesions presented a stimulated response, as well as three controls without lesions. Histocompatibility antigens (HLA) were determined in a sample of each population and no particular allele, including HLA-B7, was found to be related to SPOH as reported in the USA; however, HLA-B22 was found in three individuals who developed pulmonary histoplasmosis. Results do not provide clinical evidence or data on specific HLA risk factors, for the presence of SPOH in the population studied.