Inhibition of angiogenesis as a new therapeutic target in the treatment of lepromatous leprosy

Analysis of interleukin 7 and platelet-derived growth factor-BB mRNA expression as potential markers in erythema nodosum leprosum

Erythema nodosum leprosum (ENL) is an immunological complication of leprosy characterized by acute inflammation of the skin, nerves, and other organs. Identifying laboratory parameters is important for early diagnosis of leprosy reactions. Various cytokine biomarkers have been examined and only a few studies have reported on angiogenesis in leprosy. This study aims to understand the pathomechanism of ENL by examining IL-7 and platelet-derived growth factor (PDGF)-BB mRNA expression that can be the development and consideration of new effective therapies to prevent reactions, recurrences, and defects in leprosy. The study used a cross-sectional analytic design. Sampling was done by peripheral blood from the patient and measuring mRNA expression with specific primers RT-PCR. The expression of mRNA IL-7 and PDGF-BB was significantly different between multibasilar patients without reaction and with ENL reaction, where there was an increased expression in ENL patients. This could be used as the development of potential biomarkers in ENL and development of new therapeutic intervention pathways in ENL.

Involvement of TNF-Producing CD8+ Effector Memory T Cells with Immunopathogenesis of Erythema Nodosum Leprosum in Leprosy Patients

Type 2 reaction (T2R) or erythema nodosum leprosum (ENL), a sudden episode of acute inflammation predominantly affecting lepromatous leprosy patients (LL), characterized by a reduced cellular immune response. This possibly indicates a close relationship between the onset of T2R and the altered frequency, and functional activity of T lymphocytes, particularly of memory subsets. This study performed ex vivo and in vitro characterizations of T cell blood subpopulations from LL patients with or without T2R. In addition, the evaluation of activity of these subpopulations was performed by analyzing the frequency of these cells producing IFN-γ, TNF, and IL-10 by flow cytometry. Furthermore, the expression of transcription factors, for the differentiation of T cells, were analyzed by quantitative real-time polymerase chain reaction. Our results showed an increased frequency of CD8⁺/TNF⁺ effector memory T cells (T_EM) among T2Rs. Moreover, there was evidence of a reduced frequency of CD4 and CD8⁺ IFN-γ-producing cells in T2R, and a reduced expression of STAT4 and TBX21. Finally, a significant and positive correlation between bacteriological index (BI) of T2R patients and CD4⁺/TNF⁺ and CD4⁺/IFN-γ⁺ T cells was observed. Thus, negative correlation between BI and the frequency of CD4⁺/IL-10⁺ T cells was noted. These results suggest that CD8⁺/TNF⁺ T_EM are primarily responsible for the transient alteration in the immune response to Mycobacterium leprae in ENL patients. Thus, our study improves our understanding of pathogenic mechanisms and might suggest new therapeutic approaches for leprosy.

Angiogenesis and lymphangiogenesis in the spectrum of leprosy and its reactional forms

Background

Angiogenesis and lymphangiogenesis are the processes of neovascularization that evolve from preexisting blood and lymphatic vessels. There are few studies on angiogenesis and none on lymphangiogenesis in leprosy. Thus, the role of neovascularization in the pathophysiological mechanisms of the disease was studied across the spectrum of leprosy, its reactional states and its residual lesions.

Methodology/Principal Findings

Seventy-six biopsies of leprosy skin lesions and seven healthy controls were selected. Fifty-five serum samples were used for the detection of CD105 by ELISA. Histological sections were stained with antibodies against CD31 (blood and lymphatic vessels), D2-40/podoplanin (lymphatic vessels), and CD105/endoglin (neovessels). Microvessels were counted in 100 high-power fields (400x) and the number of vessels was evaluated in relation to the extension of the inflammatory infiltrate (0-3), to the bacillary index (0-6) and to the clinical forms. Angiogenesis, as marked by CD31 and CD105, was observed across the leprosy spectrum, compared with the controls. Additionally, there was a positive correlation between these markers with extension of the infiltrate (p <0.0001). For D2/40, lymphangiogenesis was observed in the tuberculoid form (p <0.0001). There was no statistical significance for values of CD105 detected in plasma by ELISA.

Conclusions/Significance

Angiogenesis is present across the spectrum of leprosy and in its reactional forms. The increase in the number of vessels, as detected by CD31 and CD105 staining, is related to the extension of the inflammatory infiltrate. Samples from reactional lesions have a higher number of CD31+ and CD105+ stained vessels, which indicates their involvement in the pathophysiological mechanisms of the reactional states. The regression of lesions is accompanied by the regression of neovascularization. Drugs inhibiting angiogenesis may be relevant in the treatment of leprosy, in addition to multidrugtherapy, and in the prevention of the development of reactions.