Lymphocyte subsets, macrophages and Langerhans cells in actinomycetoma and eumycetoma tissue reaction

Nitric oxide determines the development of actinomycetoma by Nocardia brasiliensis in eNOS knockout C57BL/6 mice

Mycetoma is a chronic human infectious disease that produces severe deformation frequently in the lower extremities. Etiological agents include fungi (eumycetoma) and bacteria (actinomycetoma) that produce similar clinical and microscopic changes. The clinical appearance includes swelling, abscesses, ulcers, scars and sinuses that drain purulent material with microbe microcolonies. The pathogenesis of actinomycetoma has been studied mainly in rodents. Using this approach, it was found that Nocardia brasiliensis produces proteases that may play a role in tissue damage, as well as immunosuppressive molecules, such as brasilicardin A. Nitric oxide (NO) is a molecule with biological activities depending on its local concentration. Its effect on killing intracellular bacteria such as Mycobacterium tuberculosis has been known for decades. NO plays an important role in innate and adaptive immunity. It can promote or suppress some biological activities despite its short half-ife. NO is produced by three different nitric oxide synthases (NOS). We used the genetic blockade of eNOS in C57BL/6 mice to demonstrate the role of NO in actinomycetoma development. Inflammation and actinomycetoma were prevented in genetically modified mice infected with N. brasiliensis. T cell proliferation was increased in these rodents, and antibody production, IL-6 and IL-10 expression were similar and TNF-α was lower.

Mycetoma and Chromoblastomycosis: Perspective for Diagnosis Improvement Using Biomarkers

Background: Mycetoma and chromoblastomycosis are both chronic subcutaneous infectious diseases that pose an obstacle to socioeconomic development. Besides the therapeutic issue, the diagnosis of most neglected tropical diseases (NTD) is challenging. Confirmation using direct microscopy and culture, recognized as WHO essential diagnostic tests, are limited to specialized facilities. In this context, there is a need for simple user-friendly diagnostic tests to be used in endemic villages. Methods: This review discuss the available biomarkers that could help to improve the diagnostic capacity for mycetoma and chromoblastomycosis in a theoretical and practical perspective. Results: A lack of research in this area has to be deplored, mainly for mycetoma. Biomarkers based on the immune response (pattern of leucocytes, antibody detection), the dermal involvement (extracellular matrix monitoring, protein expression), and the presence of the infectious agent (protein detection) are potential candidates for the detection or follow-up of infection. Conclusion: Confirmatory diagnosis based on specific diagnostic biomarkers will be the basis for the optimal treatment of mycetoma and chromoblastomycosis. It will be part of the global management of NTDs under the umbrella of stewardship activities.

Interleukin-17 and matrix metalloprotease-9 expression in the mycetoma granuloma

Mycetoma is a persistent, progressive granulomatous inflammatory disease caused either by fungi or by bacteria. Characteristic of this disease is that the causative agents organise themselves in macroscopic structures called grains. These grains are surrounded by a massive inflammatory reaction. The processes leading to this host tissue reaction and the immunophenotypic characteristics of the mycetoma granuloma are not known. Due to the massive immune reaction and the tissue remodeling involved, we hypothesised that the expression levels of interleukin-17 (IL-17) and matrix metalloprotease-9 (MMP-9) in the mycetoma granuloma formation were correlated to the severity of the disease and that this correlation was independent of the causative agent responsible for the granuloma reaction. To determine the expression of IL-17 and MMP-9 in mycetoma lesions, the present study was conducted at the Mycetoma Research Centre, Sudan. Surgical biopsies from 100 patients with confirmed mycetoma were obtained, and IL-17 and MMP-9 expression in the mycetoma granuloma were evaluated immunohistochemically. IL-17 was mainly expressed in Zones I and II, and far less in Zone III. MMP-9 was detected mainly in Zones II and III, and the least expression was in Zone I. MMP-9 was more highly expressed in Actinomadura pelletierii and Streptomyces somaliensis biopsies compared to Madurella mycetomatis biopsies. MMP-9 levels were directly proportional to the levels of IL-17 (p = 0.001). The only significant association between MMP9 and the patients' characteristics was the disease duration (p<0.001). There was an insignificant correlation between the IL-17 levels and the patients' demographic characteristics.

Activation and IL-1β secretion of human peripheral phagocytes infected with Actinomadura madurae, Nocardia asteroides and Candida albicans

OBJECTIVE

To evaluate the ability of Actinomadura madurae (A. madurae) and Nocardia asteroides (N. asteroides), using Candida albicans (C. albicans) as prototypic control, to elicit the activation and IL-1β secretion of blood phagocytic cells from healthy donors.

METHODS

Microscopic evaluation of phagocytosis/activation, cell viability and spectrophotometric quantitation of endocytosis/activation, were assessed by using formazan blue test in human blood phagocytes infected with C. albicans, A. madurae or N. asteroides treated with either normal human serum (NHS) or with decomplemented NHS. Interlukin-1β from culture supernatants of infected polymorphonuclear was tested by ELISA kit assay.

RESULTS

Microscopic assay showed that phagocytosis and activation of adherent mononuclear phagocytes were greater with C. albicans followed by A. madurae and then by N. asteroides. Spectrophotometric assay in polymorphonuclear phagocytes infected with NHS-treated pathogens indicated that activation was similarly higher by C. albicans and A. madurae and lower by N. asteroides. Kinetic assays in infected polymorphonuclear cells showed that viability was decreased by C. albicans and N. asteroides or unaffected with A. madurae. Levels of IL-1β at 8 h of incubation were higher with C. albicans followed by A. madurae whereas lower levels were found with N. asteroides.

CONCLUSIONS

The extent of cell-viability and activation as well IL-1β secretion may be related with the virulence of C. albicans and N. asteroides and other parameters remain to be explored for assessing the virulence of A. madurae.

Lower percentage of CD8+ T cells in peripheral blood of patients with sporotrichosis

PURPOSE

To characterize the peripheral immunity and immunity response of patients with sporotrichosis, in this study we determined the lymphocyte subsets in the peripheral blood of Chinese patients with sporotrichosis.

METHODS

In this retrospective study, peripheral blood was collected from 69 sporotrichosis patients (37, fixed cutaneous form; 32 lymphocutaneous) and 66 healthy controls. Lymphocyte subsets were analyzed using flow cytometry.

RESULTS

Compared to controls, the percentage of CD8+ T cells was lower in sporotrichosis patients. The percentage of CD8+ T cells in peripheral blood tended to become lower with disease duration and disease severity, although the difference was not statistically significant for either acute, subacute and chronic patients or fixed cutaneous and lymphocutaneous patients.

CONCLUSION

Our data indicate that the decrease of CD8+ T cells in peripheral blood of patients with sporotrichosis is associated with disease severity, although the difference was not statistically significant for either duration or clinical forms of the disease. Combining antifungal agents and immunomodulators in patients with long disease duration and lymphocutaneous may be more beneficial than antifungal monotherapy.

Decrease of virulence for BALB/c mice produced by continuous subculturing of Nocardia brasiliensis

Background

Subculturing has been extensively used to attenuate human pathogens. In this work we studied the effect of continuous subculturing of Nocardia brasiliensis HUJEG-1 on virulence in a murine model.

Methods

Nocardia brasiliensis HUJEG-1 was subcultured up to 130 times on brain heart infusion over four years. BALB/c mice were inoculated in the right foot pad with the bacteria subcultured 0, 40, 80, 100 and 130 times (T₀, T₄₀, T₈₀ T₁₀₀ and T₁₃₀). The induction of resistance was tested by using T₁₃₀ to inoculate a group of mice followed by challenge with T0 12 weeks later. Biopsies were taken from the newly infected foot-pad and immunostained with antibodies against CD4, CD8 and CD14 in order to analyze the in situ immunological changes.

Results

When using T₄₀, T₈₀ T₁₀₀ and T₁₃₀ as inoculums we observed lesions in 10, 5, 0 and 0 percent of the animals, respectively, at the end of 12 weeks. In contrast, their controls produced mycetoma in 80, 80, 70 and 60% of the inoculated animals. When studying the protection of T₁₃₀, we observed a partial resistance to the infection. Immunostaining revealed an intense CD4+ lymphocytic and macrophage infiltrate in healing lesions.

Conclusions

After 130 in vitro passages of N. brasiliensis HUJEG-1 a severe decrease in its virulence was observed. Immunization of BALB/c mice, with these attenuated cells, produced a state of partial resistance to infection with the non-subcultured isolate.

Mycetoma in South India: retrospective analysis of 13 cases and description of two cases caused by unusual pathogens: Neoscytalidium dimidiatum and Aspergillus flavus

BACKGROUND

Mycetoma is a chronic suppurative and/or granulomatous inflammatory lesion of skin, subcutaneous tissue, fascia, and tendons caused by the traumatic inoculation of either fungal (eumycotic) or bacterial (actinomycotic) organisms present in the soil. The disease is characterized by triad of tumefaction, discharging sinuses, and grains.

MATERIAL AND METHODS

Thirteen new cases of biopsy proven mycetomas were analyzed, retrospectively, from January 2000 to October 2009. Clinical parameters, bone involvement, microbiological properties, and histopathological features were evaluated. Categorization into eumycotic or actinomycotic was based upon features on hematoxylin and eosin stained sections with special stains. Therapeutic outcome was presented wherever available.

RESULTS

There were eight actinomycetomas and five eumycetoma cases including 11 men and two women. Foot and lower extremities were the most common site of involvement (9 of 13, 69%). Culture results were available in 8 of 13 cases (61.5%). Madurella mycetomatis, Neoscytalidium dimidiatum, and Aspergillus flavus were the isolates among eumycetomas whereas Acinomadura madurae, Actinomadura pelletieri, and Nocardia species were the isolates among actinomycetomas. Two cases had underlying bone involvement. On follow-up, four of five eumycetoma cases showed partial improvement following surgery and antifungal therapy, one had amputation of the lower leg. Of the actinomycetomas, six of eight had dramatic improvement following sulfamethoxazole-trimethoprim based therapy, one had complete cure, and one was lost to follow-up.

CONCLUSION

Strong clinical suspicion, exact categorization of lesion into eumycotic or actinomycotic along with culture correlation, is essential for prognosis and effective therapy.

In situ TLR2 and TLR4 expression in a murine model of mycetoma caused by Nocardia brasiliensis

Actinomycetoma caused by Nocardia brasiliensis is a common disease in tropical regions. This ailment is characterized by a localized chronic inflammation that mainly affects the lower limbs. Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns, inducing the production of proinflammatory mediators. The role of TLRs in the immune response against N. brasiliensis is unknown. The aim of this work was to locate and quantify in a murine model the expression of TLR2 and TLR4 in the infection site using reverse transcription-PCR and immunohistochemistry. The results showed that TLR2 expression increased in the infected tissue, whereas TLR4 expression decreased. The presence of TLR2 and TLR4 was demonstrated in different cell populations throughout the chronic infectious process. In the early stages of this process, TLR2 was expressed in neutrophils and macrophages in direct contact with the inoculum, whereas TLR4 was observed in mast cells. In the advanced stages of the infection, TLR2 was expressed in foam cells and fibroblasts and was likely associated with bacterial containment, while TLR4 was downregulated, probably resulting in an imbalance between the host immune response and the bacterial load that favoured chronic disease.

Mycetoma in children: experience with 15 cases

BACKGROUND

Mycetoma is a chronic infection caused by aerobic actinomycetes and filamentous fungi. It is an occupational disease frequent in tropical countries and is uncommon in children.

METHODS

A retrospective (25 years) report of mycetomas was conducted in children less than 15 years of age. Each of the cases was studied clinically and proven with microbiologic tests: direct examinations (to identify and classify the grains), cultures and identification based on morphology and biochemical tests. The therapeutic experience of the cases was also reviewed.

RESULTS

In a 25-year period, a total of 334 mycetomas were seen at our institution, 15 of which (4.5%) were in patients 15 years of age and younger (mean age: 11.2 years, age range: 6-15 years). Twelve cases were males and 3 females. The main clinical location was the foot in 10 of 15 (66.6%). Etiologies included 13 actinomycetomas and 2 eumycetomas. Etiologic agents were Nocardia brasiliensis in 12 cases, Nocardia asteroides in one and Madurella mycetomatis in 2. Eleven of the13 cases of actinomycetomas treated with trimethoprim-sulfamethoxazole plus diaminodiphenylsulfone were cured. The 2 failures were successfully treated with amoxicillin/clavulanate. One of the eumycetomas was cured with itraconazole therapy, whereas the other failed various treatments eventuating in surgical amputation.

CONCLUSIONS

Mycetomas are exceptional in children; in our setting, actinomycetomas are more frequent than eumycetomas. The clinical and microbiologic diagnosis is simple. Overall, treatment response is better for actinomycetomas than for eumycetomas.