Prediction of the occurrence of leprosy reactions based on Bayesian networks.

Introduction: Leprosy reactions (LR) are severe episodes of intense activation of the host inflammatory response of uncertain etiology, today the leading cause of permanent nerve damage in leprosy patients. Several genetic and non-genetic risk factors for LR have been described; however, there are limited attempts to combine this information to estimate the risk of a leprosy patient developing LR. Here we present an artificial intelligence (AI)-based system that can assess LR risk using clinical, demographic, and genetic data. Methods: The study includes four datasets from different regions of Brazil, totalizing 1,450 leprosy patients followed prospectively for at least 2 years to assess the occurrence of LR. Data mining using WEKA software was performed following a two-step protocol to select the variables included in the AI system, based on Bayesian Networks, and developed using the NETICA software. Results: Analysis of the complete database resulted in a system able to estimate LR risk with 82.7% accuracy, 79.3% sensitivity, and 86.2% specificity. When using only databases for which host genetic information associated with LR was included, the performance increased to 87.7% accuracy, 85.7% sensitivity, and 89.4% specificity. Conclusion: We produced an easy-to-use, online, free-access system that identifies leprosy patients at risk of developing LR. Risk assessment of LR for individual patients may detect candidates for close monitoring, with a potentially positive impact on the prevention of permanent disabilities, the quality of life of the patients, and upon leprosy control programs.

Patologia da hanseníase e a importância do diagnóstico histopatológico: uma entrevista com Dr. Cleverson Teixeira Soares / Pathology of leprosy and the importance of histopathological diagnosis: an interview with Dr. Cleverson Teixeira Soares

A revista Hansenologia Internationalis tem a honra de entrevistar o Dr. Cleverson Teixeira Soares, médico patologista, responsável pelo Laboratório de Anatomia Patológica do Instituto Lauro de Souza Lima, Bauru, São Paulo, Brasil. Dr. Cleverson é autor do livro Histopathological Diagnosis of Leprosy, publicado em 2021 pela editora Bentham Books, além de relevante publicação de artigos, em periódicos científicos nacionais e internacionais, com impacto nas áreas de patologia e hansenologia. Ele descreve sobre sua trajetória profissional, os desafios para o entendimento da hanseníase em suas múltiplas formas clínicas e como a patologia clássica e molecular tem contribuído para a construção do conhecimento sobre esta doença tão complexa.

Association of CD209 (DC-SIGN) rs735240 SNV with paucibacillary leprosy in the Brazilian population and its functional effects.

BACKGROUND: Leprosy, caused by Mycobacterium leprae, is a public health problem in Brazil that affects peripheral nerves, resulting in physical disabilities. During host-pathogen interactions, the immune response determines leprosy outcomes from a localised (paucibacillary) form to a disseminated (multibacillary) form. The recognition of M. leprae involves the DC-SIGN receptor, which is present on the dendritic cells (DCs) and participates in immune activation. OBJECTIVES: To evaluate the association of polymorphisms in the promoter region of the gene encoding DC-SIGN (CD209) and the clinical form of leprosy, and to investigate its functional effects. METHODS: The study population included 406 leprosy patients from an endemic area in Brazil [310 multibacillary (MB); 96 paucibacillary (PB)]. A functional evaluation based on the effects of the single nucleotide variant (SNV) associated with PB leprosy on the specific immune response was also performed. RESULTS: The GA genotype and the presence of the A allele of rs735240 (-939G>A) were associated with PB leprosy [OR: 2.09 (1.18-3.69) and 1.84 (1.07-3.14), respectively]. Carriers of the A allele showed reduced expression of CD209 and TGF-ß1 in leprosy lesions in comparison with individuals with GG genotype, in addition to a higher response to the Mitsuda test. CONCLUSION: These data suggest that rs735240 influences the immune response against M. leprae and clinical presentation of leprosy.

Association of CD209 (DC-SIGN) rs735240 SNV with paucibacillary leprosy in the Brazilian population and its functional effects

BACKGROUND Leprosy, caused by Mycobacterium leprae, is a public health problem in Brazil that affects peripheral nerves, resulting in physical disabilities. During host-pathogen interactions, the immune response determines leprosy outcomes from a localised (paucibacillary) form to a disseminated (multibacillary) form. The recognition of M. leprae involves the DC-SIGN receptor, which is present on the dendritic cells (DCs) and participates in immune activation. OBJECTIVES To evaluate the association of polymorphisms in the promoter region of the gene encoding DC-SIGN (CD209) and the clinical form of leprosy, and to investigate its functional effects. METHODS The study population included 406 leprosy patients from an endemic area in Brazil [310 multibacillary (MB); 96 paucibacillary (PB)]. A functional evaluation based on the effects of the single nucleotide variant (SNV) associated with PB leprosy on the specific immune response was also performed. RESULTS The GA genotype and the presence of the A allele of rs735240 (-939G>A) were associated with PB leprosy [OR: 2.09 (1.18-3.69) and 1.84 (1.07-3.14), respectively]. Carriers of the A allele showed reduced expression of CD209 and TGF-β1 in leprosy lesions in comparison with individuals with GG genotype, in addition to a higher response to the Mitsuda test. CONCLUSION These data suggest that rs735240 influences the immune response against M. leprae and clinical presentation of leprosy.

Classification and general aspects of leprosy

Leprosy is a chronic infectious disease whose etiological agent is Mycobacterium leprae. Recently, Mycobacterium lepromatosis is also implicated as a causative agent and has been identified in different forms of the disesase. Leprosy is a comples disease from a clinical histopathological, and molecular point of view. The wide complex disease from a clinical, histopathological characteristics observed throughout the disease spectrum and reactions render it a challenging disease in clinical and pathological practice. This chapter discusses the main aspects of the disease and its hispathological classification. An important approach to the bacilloscopic examination, which is fundamental for the histopathological classification of the disease, showing its quantitative and qualitative aspects, is discussed. the various photographic panels demonstrate the bacillus' ability to parasitize different types of tissues and cells of the skin and other organs of the human body...

Indeterminate leprosy

Leprosy in its determinate from (I) is a clinical presentation of the disease preceding the forms described in the Ridley and Jopling (R & J) classification and any other special forms of leprosy or the reactions. In this chapter, the histopathological and bacilloscopic characteristics of the I form of leprosy are described, and the main differential diagnoses are discussed. The histopathological criteria that distinguish the I form from the other forms of leprosy and the reaction processes that may occur during the disease course are also discussed. The identification of the histopathological characteristics of I leprosy is of great importance with respect to the selection of the treatment. I leprosy should not be confused with other forms of leprosy, especially the multibacillary forms, wich require more prolonged treatment and wich can develop reaction phenomena, causing permanent sequelae.

Polar forms (TT and LL)

Leprosy is a spectral disease. Its two polar forms, tuberculoid (TT) and lepromatous (LL), are distinct presentations of the disease, both from a clinical and histopathological/bacilloscopic point of view. In this chapter, the histopathological characteristics that define the two polar forms (TT and LL), are presented, and their main differential diagnoses are discussed. These two forms also have significant differences in their treatment protocol. Histopathological recognition of both forms of the disease is important for choosing the correct treatment. Also, there are a large numbre of disease that can have a clinical presentation similar to the TT and LL forms of leprosy. In this context, histopathological examination is essential for defining the diagnosis of leprosy.

Intermediate or Borderline forms (BT, BB, and BL)

Leprosy is a long-term spectrum disease and can present various clinical and histopathological aspects. Between the two poles of leprosy, there is a wide range of types, consisting of intermediate or borderline forms. In this chapter, the clinical, histopathological, and bacilloscopic characteristics of the intermediate forms (borderlibe-tuberculoid [BT], borderline-borderline [BB], and borderline lepromatous [BL]) are presented and discussed. The main clinical and pathological characteristics that allow the diagnosis and classification of leprosy among the different borderline forms are described and illustrated in panel form, as well as their most significant clinical and histopathological differential diagnoses are also discussed. The clinical-pathological classification of this disease has important implications in the choice of the correct treatment, the understanding of the pathophysiology, and the development of the reaction phenomena typical of leprosy,.

Type 1 reaction (T1R)

A type 1 reaction (T1R) is also known as a reversal reaction. This phenomenon involves exarcebation of the immune system or delayed-type hypersensitivity in response to the antigens of Mycobacterium leprae present in parasitized tissues. It occurs in mnost patients of the tuberculoid and borderline forms of the Ridley & Jopling classification for leprosy. It is an important phenomenon that can occur before, during, or after leprosy treatment and can be destructive, causing tissue damage mainly in the nerves, as well as irreversible sequelae. The recognition of T1R in histological sections may be notified prior to clinical presentation. Histopathological recognition is vital in defining or confirming the presence of T1R, guiding the treatment of the reaction process, avoiding or reducing the possibiliy of serious sequelae, correcting possible mistakes in the classification of patients within the spectrum of leprosy, and ruling out other diseases that can clinically simulate a T1R. In this chapter, the histopathological characteristics that allow the recognition of T1R, various histopathological aspects of the common forms of leprosy, and histopathological differential diagnoses are discussed.

Type 2 reaction (T2R)

Type 2 reaction (t2R), also called erythema nodosum leprosum (ENL), is a reactional phenomenon that occurs in response to Mycobacterium leprae antigens in patients with borderline lepromatous our lepromatous forms of leprosy. T2R usually occurs after starting treatment and can affect any parasitic tissue in the body, causing neuritis, arthritis, painful lymphadenitis, buccopharyngeal lesions, laryngitis, hepatomegaly, splenomegaly, bone injuries, iridocyclitis, uveitis, orchitis, glomerulitis with proteinuria, and hematuria. Recognition of the histopathological characteristics of T2R is important for guiding early treatmen tof the reaction process, decreasing the likelihood of developing serious sequelae, especially when T2R affects the nerves, and to exclude different diseases that can simulate T2R over leprosy lesions during the T2R diagnosis are described, and some of its differential clinicopathological diagnoses and their possible pathophysiological mechanisms are discussed.

Regression and relapse

Immediately after leprosy treatment initiation, changes in leprosy lesions also commence. The histopathological and bacilloscopic characeristics of the regressing lesions undergo continuous changes over years of decades. It is important to recognize these changes as they allow for the assessment od whether a particular lesion is in regression or if there are signs of disease reactivation. Interpretation of the findings will depend on a close correlation among histopathological patterns, bacilloscopic characteristics, and clinical data. This chapter discusses the main factors that allow the recognition of the histopathological characteristics of regressive phenomena from initial phases to late or residual phases, the changes typical in effectiveness, the reaction phenomena triggered after treatment initiation on regressing lesions, and the evaluation of leprosy recurrence. Further, this chapter includes a discussion on the main differential diagnoses of leprosy regression and relapse.

Lucio's leprosy and Lucio's phenomenom, histoid leprosy, nodular leprosy of childhood, primary neural leprosy, and diagnosis using fine needle aspiration cytology

In this chapter, some special forms of the clinical and histopathological presentation of leprosy are discussed: Lucio's leprosy and Lucio's phenomenon, histoid leprosy, nodular leprosy or childhood, and primary neural leprosy. The main clinical and histopathological characteristics of these forms and the condition under which they appear within the entire spectrum of leprosy and its reaction phenomena are presented. in addition, the main differential clinical and pathological diagnoses of each of these lesions are discussed. The use of fine-needle aspiration cytology for the diagnosis os leprosy, including its reaction phenomena, has also been addressed. The identication of the histopathological features of these special forms of leprosy is important to confirm the clinical diagnosis for guiding treatment and preventing the possible misinterpretation of clinical and histopathological findings.

Altered composition and functional profile of high-density lipoprotein in leprosy patients

The changes in host lipid metabolism during leprosy have been correlated to fatty acid alterations in serum and with high-density lipoprotein (HDL) dysfunctionality. This is most evident in multibacillary leprosy patients (Mb), who present an accumulation of host lipids in Schwann cells and macrophages. This accumulation in host peripheral tissues should be withdrawn by HDL, but it is unclear why this lipoprotein from Mb patients loses this function. To investigate HDL metabolism changes during the course of leprosy, HDL composition and functionality of Mb, Pb patients (paucibacillary) pre- or post-multidrug therapy (MDT) and HC (healthy controls) were analyzed. Mb pre-MDT patients presented lower levels of HDL-cholesterol compared to HC. Moreover, Ultra Performance Liquid Chromatography-Mass Spectrometry lipidomics of HDL showed an altered lipid profile of Mb pre-MDT compared to HC and Pb patients. In functional tests, HDL from Mb pre-MDT patients showed impaired anti-inflammatory and anti-oxidative stress activities and a lower cholesterol acceptor capacity compared to other groups. Mb pre-MDT showed lower concentrations of ApoA-I (apolipoprotein A-I), the major HDL protein, when compared to HC, with a post-MDT recovery. Changes in ApoA-I expression could also be observed in M. leprae-infected hepatic cells. The presence of bacilli in the liver of a Mb patient, along with cell damage, indicated hepatic involvement during leprosy, which may reflect on ApoA-I expression. Together, altered compositional and functional profiles observed on HDL of Mb patients can explain metabolic and physiological changes observed in Mb leprosy, contributing to a better understanding of its pathogenesis. AUTHOR SUMMARY: Leprosy is a chronic disease caused by Mycobacterium leprae, which causes lesions on the skin and peripheral nerves. Some patients do not present an efficient immune response and have a disseminated infection (multibacillary, Mb). Mb patients have lipid accumulation in infected tissues that is important for microorganism survival. High-density lipoprotein (HDL) is composed of proteins and lipids and is produced in the liver. It removes excess of lipids from peripheral tissues and presents anti-inflammatory activity; however, these activities are not being properly performed in leprosy. To understand more about HDL metabolism on leprosy, the chemical composition and functionality of HDL from leprosy patients were analyzed before and after treatment with antibiotics (multidrug therapy, MDT). It was observed that HDL has an altered lipid composition in Mb patients before MDT, which may lead to an impairment of its functions. Apolipoprotein A-I (ApoA-I), the main HDL protein, seems to be highly affected during infection. These functions can be slightly recovered after MDT, but not in the levels of healthy individuals. Our data open new perspectives to elucidate the modulation of lipid metabolism in leprosy and consequently to prevent disease complications.

Emergence and transmission of drug-/multidrug-resistant Mycobacterium leprae in a former leprosy colony in the Brazilian Amazon

BACKGROUND: Leprosy has been treated with multidrug therapy (MDT) distributed for free across the globe and regarded as highly efficient. However, the impossibility to grow M. leprae in axenic media has historically impaired assessment of M. leprae resistance, a parameter only recently detectable through molecular methods. METHODS: A systematic, population-based search for M. leprae resistance in suspected leprosy relapse cases and contacts was performed in Prata Village, an isolated, hyper-endemic former leprosy colony located in the Brazilian Amazon. Results led to an extended active search involving the entire Prata population. Confirmed leprosy cases were investigated for bacterial resistance using a combination of in vivo testing and direct sequencing of resistance genes folP1, rpoB and gyrA. Molecular epidemiology analysis was performed using data from 17 variable number tandem repeats (VNTR). RESULTS: M. leprae was obtained from biopsies of 37 leprosy cases (18 relapses and 19 new); 16 (43.24%) displayed drug-resistance variants. Multi-drug resistance to rifampicin and dapsone was observed in 8 relapses and 4 new cases. Single resistance to rifampicin was detected in one new case. Resistance to dapsone was present in two relapses and one new case. Combined molecular resistance and VNTR data revealed evidence of intra-familial primary transmission of resistant M. leprae. CONCLUSIONS: A comprehensive, population-based systematic approach to investigate M. leprae resistance in a unique population revealed an alarming scenario of emergence and transmission of resistant strains. These findings may be used for the development of new strategies for surveillance of drug resistance in other populations.

Murine experimental leprosy: Evaluation of immune response by analysis of peritoneal lavage cells and footpad histopathology.

This study evaluated the immune response of nude and BALB/c mice inoculated in the footpads (FP) with Mycobacterium leprae after 3, 5 and 8 months. At each timepoint peritoneal cells, peripheral blood, FP and popliteal lymph nodes (PLN) were collected. Peritoneal cell cultures were performed to measure the H2 O2 , O2- , NO, IL-2, IL-4, IL-10, IL-12, IFN-γ and TNF levels. Serum levels of anti-PGL-I antibodies were also quantified. The results showed that the infection was progressive in nude mice with bacterial multiplication, development of macroscopic lesions in the FP and presence of bacilli in the PLN at 8 months. In BALB/c mice, the infection reached a plateau of bacillary multiplication at 5 months and regressed at 8 months. Histopathological analysis of FP revealed a mononuclear inflammatory infiltrate with a large number of neutrophils at 5 months, with a higher number in nude mice. At 8 months, the number of neutrophils decreased and the infiltrate was predominantly mononuclear in both mouse strains. There was no H2 O2, O2- , IL-2, IL-4, IL-10 and IFN-γ production in the course of infection in nude mice; however, in BALB/c, O2- and IL-12 production was higher at 5 months and NO, IFN-γ and TNF production was higher at 8 months when there was a decrease in the number of bacilli. The level of anti-PGL-I antibodies was higher in BALB/c mice. Thus, nude and BALB/c mice can be used as experimental models for the study of various aspects of leprosy.