Regulatory T cells: Friends or foe in human Mycobacterium leprae infection?

Regulatory T cells (Tregs) are known to control immune responses by suppressing the antigen-presenting and effector T cells. Some mechanisms adopted by Tregs in combating Mycobacterium infections have been proposed. Nevertheless, in M. leprae infection, also known as leprosy or Hansen's disease, the role of Tregs has not been completely elucidated. Using multicolor flow cytometry, we evaluated the expression of different cell surface and intracellular molecules present in Tregs from peripheral blood samples of leprosy patients. Before initiating treatment, thirteen new cases of leprosy were grouped according to the Ridley-Jopling classification in to the paucibacilary (PB) or multibacilary (MB) group. Fifteen non-infected individuals (NI) were included as control subjects. Tregs were higher in the MB group than in the NI group. Tregs also co-expressed high amounts of PD1 and PDL-1, indicating that these cells could induce apoptosis of effector cells and simultaneously prevent their own apoptosis. Our data showed that compared to the NI group, Tregs from the PB group expressed higher levels of CD95L, which may be associated with other apoptotic pathways that may decrease Tregs in these patients. Correlation analysis reinforced that PD1 and CD95L are efficient apoptosis' pathway that decreased levels of Tregs in the NI and PB groups. We also observed significant differences in cytokine expression of Tregs from the PB and MB groups. Compared to the NI group, Tregs from the MB group showed higher IL-17 expression; however, compared to the PB group, the expression of IL-10 in Tregs from the MB group was lower, suggesting inefficient control of inflammation. Therefore, we concluded that different pathways were involved in Treg-induced suppression of leprosy. Moreover, Treg-mediated regulation of inflammation via IL-10 and IL-17 expression in leprosy patients was inefficient. Thus, we propose that during M. leprae infection, Tregs may impair the immune responses elicited against this bacillus, favor bacterial replication, and aid in persistence of a disseminated multibacillary disease.

Cytokines as biomarkers to monitoring the impact of multidrug therapy in immune response of leprosy patients.

Leprosy or Hansen's disease is a chronic infectious disease of the skin and nerves, caused by the intracellular bacilli Mycobacterium leprae. It is characterized by a spectrum of clinical forms depending on the host's immune response to M. leprae. Patients with tuberculoid (TT) leprosy have strong cell-mediated immunity (CMI) with elimination of the bacilli, whereas patients with lepromatous (LL) leprosy exhibit defective CMI to M. leprae. Despite advances in the understanding of the pathogenesis of leprosy and the development of new therapeutic strategies, there is a need for the identification of biomarkers which be used for early diagnosis and to discrimination between different forms of the disease, as prognostic markers. Here, we analyzed the serum levels of IL-1ß, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-17A, IFN-γ and TNF in order to address the contribution of these cytokines in late phase of M. leprae infection, and the impact of multidrug therapy (MDT). Our results demonstrated that patients of LL group presented higher expression of serum levels of inflammatory cytokines before MDT, while TT patients presented a balance between inflammatory and regulatory cytokines. MDT changes the profile of serum cytokines in M. leprae infected patients, as evidenced by the cytokine network, especially in TT patients. LL patients displayed a multifaceted cytokine system characterized by strong connecting axes involving inflammatory/regulatory molecules, while TT patients showed low involvement of regulatory cytokines in network overall. Cytokines can be identified as good biomarkers of the impact of MDT on the immune system and the effectiveness of treatment.

Comparación de la técnica serológica ML flow y frotis cutáneas para evaluar la carga bacteriana en pacientes nuevos diagnosticados de Lepra / No disponible

Introducción: La técnica ML Flow es un ensayo inmunocromatográfico que detecta anticuerpos de tipo IgM glicolípido fenólico-I (PGL-1) M. leprae específico. Además de los frotis cutáneos teñidos mediante Ziehl-Neelsen puede ser útil en la clasificación de los pacientes de lepra para administrar el correspondiente tratamiento farmacológico. Objetivo: Este estudio revisa la relación entre los niveles de anticuerpos detectables mediante la técnica serológica semi-cuantitativa ML Flow y la carga bacteriana cuantificada mediante frotis cutáneo. Pacientes y métodos: Se obtuvieron frotis cutáneos de 135 pacientes nuevos diagnosticados de lepra en un servicio dermatológico de referencia en Brasil (registrados como índice bacteriológico – IB) y un resultado con el ML Flow (registrado cuantitativa y semi-cuantitativamente) en el momento de ser admitidos al estudio. Se calcularon la regresión logística y concordancia (índice kappa). Resultados: Los frotis cutáneos resultaron positivos en el 35.9% de los pacientes y el 57% de los pacientes eran seropositivos para el PGL-1. De entre los seropositivos, el 41.6% presentaban 5 o menos de 5 lesiones y el 65.8% presentaba la implicación de más de un nervio periférico. Los frotis resultaron positivos en sólo tres casos seronegativos (5.6%) y negativos en el 41.9% de pacientes seropositivos. Los pacientes con un IB+4 presentaban un OR de 3.3 de ser seropositivos en comparación con los de IB más bajo. Conclusiones: Hay una correlación entre el test serológico y los frotis cutáneos. Por tanto, un test ML Flow puede resultar útil para la clasificación clínica de la lepra, además de los frotis cutáneos que requieren una infraestructura de laboratorio y personal con experiencia (AU)

Introduction. The ML Flow test is an immunochromatographic assay that detects IgM antibodies against M. leprae-specific anti-phenolic glycolipid I (PGL-I). In addition to slit skin smears stained by the Ziehl-Neelsen technique, it can be helpful in the operational classification of leprosy patients for treatment purposes. Objective. This work studied the relationship between antibody levels as detected by semi-quantitative ML Flow serologic test and bacterial load as quantified by slit skin smear. Patients and methods. 135 patients with newly detected leprosy at the reference service in Sanitary Dermatology in Brazil had slit skin smears (registered as bacillary index – BI) and an ML Flow test (registered qualitatively and semi-quantitatively) performed at admission. A logistic regression and agreement measures (kappa index) were calculated. Results. Slit skin smears were positive in 35.9% of patients and 57% of patients were seropositive for PGL-1 antibodies. Among the seropositive patients, 41.6% had five or fewer skin lesions, and 65.8% had more than one peripheral nerve involved. Slit skin smears were positive in only three seronegative patients (5.6%), and negative in 41.9% of seropositive patients. Patients with a BI of 4had an OR of 3.3 for being seropositive in comparison to those with a low BI. Conclusions. There is a correlation between serologic test and slit skin smear results. Therefore, an ML Flow test may become a useful tool in the clinical classification of leprosy, besides slit skin smears, which require a proper laboratory infrastructure and experienced personnel (AU)

A comparison of ML Flow serology and slit skin smears to assess the bacterial load in newly diagnosed leprosy patients in Brazil.

INTRODUCTION: The ML Flow test is an immunochromatographic assay that detects IgM antibodies against M. leprae-specific anti-phenolic glycolipid I (PGL-I). In addition to slit skin smears stained by the Ziehl-Neelsen technique, it can be helpful in the operational classification of leprosy patients for treatment purposes. OBJECTIVE: This work studied the relationship between antibody levels as detected by semi-quantitative ML Flow serologic test and bacterial load as quantified by slit skin smear. PATIENTS AND METHODS: 135 patients with newly detected leprosy at the reference service in Sanitary Dermatology in Brazil had slit skin smears (registered as bacillary index - BI) and an ML Flow test (registered qualitatively and semi-quantitatively) performed at admission. A logistic regression and agreement measures (kappa index) were calculated. RESULTS: Slit skin smears were positive in 35.9% of patients and 57% of patients were seropositive for PGL-1 antibodies. Among the seropositive patients, 416% had five or fewer skin lesions, and 65.8% had more than one peripheral nerve involved. Slit skin smears were positive in only three seronegative patients (5.6%), and negative in 41.9% of seropositive patients. Patients with a BI of 4 + had an OR of 33 for being seropositive in comparison to those with a low BI. CONCLUSIONS: There is a correlation between serologic test and slit skin smear results. Therefore, an ML Flow test may become a useful tool in the clinical classification of leprosy, besides slit skin smears, which require a proper laboratory infrastructure and experienced personnel.