Cutaneous nocardiosis and cutaneous tuberculosis induce similar expression of inflammation-related markers in human skin granulomatous infections

Abstract

Background: It has been previously suggested that both Nocardia and Mycobacteria, belonging to the Actinomycetota phylum, share mechanisms in granuloma formation. This may be due to their phylogenetic closeness, their intracellular nature, and the similarities in cell wall components, including mycolic acids. The objective is to compare the tissue distribution of cytokines interleukin-6 (IL-6) and transforming-growth factor-β (TGF-β), along with the markers vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS), in biopsy samples of human cutaneous nocardiosis and cutaneous tuberculosis by immunohistochemistry. Methods: We performed immunohistochemistry on tissue markers IL-6, TGF-β, VEGF, and eNOS in biopsied samples of cutaneous nocardiosis and cutaneous tuberculosis. Next, we took microphotographs and performed a digital analysis of the images to assess the tissue distribution of inflammatory markers. Results: We found similar expressions of IL-6 and VEGF in all studied samples of cutaneous nocardiosis and cutaneous tuberculosis. On the other hand, TGF-β and eNOS were absent in all studied samples. Conclusions: Our findings suggest that, given the similarities in granulomatous disease caused by actinomycetes, the cutaneous lesion induced by Nocardia spp. can be used as a surrogate model for the histopathological study of cutaneous tuberculosis.

Keywords

• Nocardia infections. Skin tuberculosis. Immunohistochemistry. Interleukin-6.