Vasculitis cutánea e identificación de células y mediadores inflamatorios (TNF-α) en lesiones de micetoma provocadas por inoculación de Nocardia brasiliensis en ratones Balb/c.

Background: Mycetoma is an inflammatory syndrome frequently in Mexico. Affects skin and subcutaneous tissue, muscle, bone and internal organs. It is caused by actinomycetes or true fungus. In histopathological studies of this pathology, the epidermic alteration has been shown as irregular acanthosis and pseudoepitheliomatose hyperplasia near the fistulose tract. Objective: To determine the presence of leukocytoclastic vasculitis in mycetoma lesions induced by Nocardia brasiliensis and the presence of inflammatory subpopulation cells that participate in the establishment and development of this syndrome by histological techniques and the detection of tumor necrosis factor alpha (TNF-α) by immunohistochemical methods. Material and methods: Nocardia brasiliensis was isolated from a mycetoma patient diagnosed in General Hospital Dr. Manuel Gea González in Dermatology and Mycology Service. A suspension was prepared to reach 100 mg/mL. Sixty two Balb/c female mice with 45-60 days old and 20-25 g weight were used. 0.02 mL of the suspension was administrated by subcutaneous route in right foothpad and 0.02 mL of sterile physiologic saline solution in left foothpad (control). The animals were sacrificed by cervical dislocation according the calendar: 24 hours, 15 days, 1 month (m), 2m, 2.5m, 3m, 3.5m, 4m, 5m, 5.5m, 6m and 6.5m). The feet were removed and fixed in formol at 10% and histologically processed to hematoxylin-eosin and Ziehl-Neelsen stain. To immunohistochemical stain R&D system HRP-AEC was used (catalog CTS009) avidine-antibodies: anti-mouse TNF-α (R-19) (goat polyclonal IgG, Santa Cruz Biotechnology). Results: The presence of leukocytoclastic vasculitis in mycetoma by Nocardia brasiliensis in mice was 23%. Conclusions: Acute process was established with neutrophils present at 24h and 15d post-inoculation, after a month the infiltrate changed and the epithelioid as vacuolated histiocytes, lymphocytes and some plasmatic cells were mainly observed. Finally after the third month the presence of neutrophils around the grain and abundant histiocytes were evident. The presence of TNF-α adhered to the grain after two months post inoculation right up until the end of the study was observed. [ABSTRACT FROM AUTHOR]