Comparative analysis of the tissue inflammatory response in human cutaneous and disseminated leishmaniasis

Abstract

Cutaneous leishmaniasis (CL) is the most frequent clinical form of tegumentary leishmaniasis and is characterised by a single or a few ulcerated skin lesions that may disseminate into multiple ulcers and papules, which characterise disseminated leishmaniasis (DL). In this study, cells were quantified using immunohistochemistry and haematoxylin and eosin staining (CD4+, CD68+, CD20+, plasma cells and neutrophils) and histopathology was used to determine the level of inflammation in biopsies from patients with early CL, late CL and DL (ulcers and papules). The histopathology showed differences in the epidermis between the papules and ulcers from DL. An analysis of the cells present in the tissues showed similarities between the ulcers from localised CL (LCL) and DL. The papules had fewer CD4+ T cells than the DL ulcers. Although both CD4+ cells and macrophages contribute to inflammation in early CL, macrophages are the primary cell type associated with inflammation intensity in late ulcers. The higher frequency of CD20+ cells and plasma cells in lesions demonstrates the importance of B cells in the pathogenesis of leishmaniasis. The number of neutrophils was the same in all of the analysed groups. A comparison between the ulcers from LCL and DL and the early ulcers and papules shows that few differences between these two clinical forms can be distinguished by observing only the tissue.

Fig. 1A. : inflammation percentage in lesions from localised cutaneous leishmaniasis (LCL) and disseminated leishmaniasis (DL). Mean ± standard deviation (SD) are indicated; B: number of CD4⁺ T lymphocytes in lesions from LCL and DL. Mean ± SD are indicated; C: linear correlations of Spearman (p = 0.003; R = 0.92) between inflammation (%) and CD4⁺ T lymphocytes in recent (LCL-E) group; D: linear correlations of Spearman between inflammation (%) and CD4⁺ T lymphocytes in DL with papule (DL-P) group (p = 0.03; R = 0.44) (10 patients per group). Significance levels are indicated. DL-U: DL with ulcers; LCL-L: late LCL.

Fig. 2A. : immunostained CD4⁺ T cells (400X) (arrows); B: immunostained CD68⁺ cells (400X) (arrows); C: immunostained CD20⁺ cells (400X) (arrows); D: in haematoxylin and eosin, the presence of plasma cells in the inflammatory infiltrate (arrowheads) (400X).

Fig. 3A. : number of CD68⁺ macrophages in lesions from localised cutaneous leishmaniasis (LCL) and disseminated leishmaniasis (DL). Mean ± standard deviation are indicated; B: linear correlations of Spearman between inflammation (%) (p = 0.0005; R = 0.89) and CD68⁺ macrophages recent LCL (LCL-E) group; C: linear correlations of Spearman (p = 0.01; R = 0.59) between inflammation (%) and CD68⁺ macrophages in late LCL (LCL-L) group (10 patients per group). DL-P: DL with papules; DL-U: DL with ulcers.

Fig. 4A. : number of CD20⁺ B lymphocytes in lesions from localised cutaneous leishmaniasis (LCL) and disseminated leishmaniasis (DL). Mean ± standard deviation (SD) are indicated; B: number of plasma cells in lesions from LCL and DL. Mean ± SD are indicated (10 patients per group). Significance levels are indicated. DL-P: DL with papules; DL-U: DL with ulcers.

Fig. 5A. : in haematoxylin and eosin, the presence of neutrophils in the inflammatory infiltrate (arrows) (400X); B: number of neutrophils in lesions from localised cutaneous leishmaniasis (LCL) and disseminated leishmaniasis (DL); C: linear correlations of Pearson between inflammation (%) and neutrophils in recent LCL (LCL-E) group (10 patients per group). DL-P: DL with papules; DL-U: DL with ulcers.