CD3+CD4negCD8neg (double negative) T lymphocytes and NKT cells as the main cytotoxic-related-CD107a+ cells in lesions of cutaneous leishmaniasis caused by Leishmania (Viannia) braziliensis

Abstract

BackgroundCutaneous leishmaniasis (CL) is caused by Leishmania (Viannia) braziliensis, which infects dermal macrophages and dendritic cells, causing an intense immune-mediated-tissue inflammation and a skin ulcer with elevated borders that can heal spontaneously or after antimonial therapy. The resolution of lesions depends on an adaptive immune response, and cytotoxic cells seem to have a fundamental role in this process. The aim of this study is to better understand the role of cytotoxicity mediated mechanisms that occur during the immune response in the CL lesion milieu, considering distinct cytotoxic-related CD107a+ cells, such as CD8+, CD4+, CD4neg CD8neg (double-negative, DN) and CD4+CD8+ (double-positive, DP) T lymphocytes, as well as NK and NKT cells.MethodsLesion derived cells were assessed for T cell subpopulations and NK cells, as well as CD107a expression by flow cytometry. In addition, cytometric bead array (CBA) was used to quantify cytokines and granzyme B concentrations in supernatants from macerated lesions.ResultsFlow cytometry analyses revealed that NKT cells are the major CD107a-expressing cell population committed to cytotoxicity in CL lesion, although we also observed high frequencies of CD4+ and DN T cells expressing CD107a. Analysing the pool of CD107a+-cell populations, we found a higher distribution of DN T cells (44%), followed by approximately 25% of NKT cells. Interestingly, NK and CD8+ T cells represented only 3 and 4% of the total-CD107a+-cell pool, respectively.ConclusionsThe cytotoxicity activity that occurs in the lesion milieu of CL patients seems to be dominated by DN T and NKT cells. These findings suggest the need for a reevaluation of the role of classical-cytotoxic NK and CD8+ T cells in the pathogenesis of CL, implicating an important role for other T cell subpopulations.

Contribution of Leishmania braziliensis antigen-specific CD4+ T, CD8+ T, NK and CD3+CD56+NKT cells in the immunopathogenesis of cutaneous leishmaniasis patients: Cytotoxic, activation and exhaustion profiles

“…In the current investigation we observed that LbAg induces CD3 + CD56 + NKT cell activation, leading to an expansion of cytotoxic-CD107a + CD3 + CD56 + NKT in all CL patient groups. Previous report of our group showed high percentages of total and cytotoxic-CD107a + NKT cells in the lesions of CL patients, reinforcing the involvement of NKT cells with cytotoxic activity in CL [20]. These findings together strengthen the important role CD3 + CD56 + NKT cells in the immune response established by the host during antimonial therapy, contributing to the resolution of disease [19,20].…”

“…Recently, our group investigated the contributions of cytotoxic CD4 + T, CD8 + T, NK and NKT cells in the immune response in blood from CL patients before, during and after antimonial treatment, highlighting an important cytotoxic activity by CD4 + T and NKT cells, differently from classical-cytotoxic cells, as CD8 + T and NK cells [19]. Corroborating this statement, we also reported the greatest contribution of CD4 neg CD8 neg T cells and NKT in the cytotoxic events in the CL lesion's milieu [20].…”

“…It is important to state that these studies have been focused only in classical-cytotoxic-CD8 + T cells, however other cell populations as NK, NKT, and even CD4 + T cells, with cytotoxic profiles, contribute importantly in the immune response in the CL patients, highlighting the important cytotoxic role performed by CD4 + T and NKT cells [19]. Corroborating this statement, we also reported the greatest contribution of CD4 neg CD8 neg T cells and NKT in the cytotoxic events in the CL lesion's milieu [20]. Due this pluri-cell-populations immune response, it is fundamental to investigate the contributions of these cell populations presenting antigenspecific cytotoxicity (CD107a + ) [18,[21][22][23], activation (CD38 + ) [24] and exhaustion (CD279 + ) [25][26][27][28] profiles.…”

Cytotoxic activity in cutaneous leishmaniasis

“…Recent work has shown that cytotoxicity is one of the main mechanisms underlying disease induced by L. braziliensis infection ( Faria et al 2009 , Dantas et al 2013 , Novais et al 2013 , 2015 , Santos et al 2013 , 2015 , Cardoso et al 2015 , Ferraz et al 2015 , 2017 ) ( Table ). In a recent study performed by our group, we compared gene expression in lesions of patients with CL with that in normal skin from healthy individuals.…”

Compartmentalized cytotoxic immune response leads to distinct pathogenic roles of natural killer and senescent CD8+ T cells in human cutaneous leishmaniasis

“…9 Furthermore, higher numbers of CD56 + cells are found in the peripheral blood of patients with CL before and after treatment, 10 as well as in lesions of patients with diffuse CL who have a positive response to immunotherapy. 11 Conversely, increased NK cell activity is linked to susceptibility and severity of human visceral leishmaniasis, 12 CL 13,14 and mucocutaneous leishmaniasis. 15 The pivotal balance that regulates either the functional activity of senescent CD8 + T cells or NK cytotoxic cells in blood and lesions of patients with CL is poorly understood.…”