Pathogenesis and Host Immune Response in Leprosy

Serodiagnosis of paucibacillary and multibacillary leprosy using a recombinant chimeric protein composed of specific B-cell epitopes derived from Mycobacterium leprae proteins

Leprosy diagnosis is difficult due to the clinical similarity with other infectious diseases, and laboratory tests presents problems related to sensitivity and/or specificity. In this study, we used bioinformatics to assess Mycobacterium leprae proteins and formulated a chimeric protein that was tested as a diagnostic marker for the disease. The amino acid sequences from ML0008, ML0126, ML0308, ML1057, ML2028, ML2038, ML2498 proteins were evaluated, and the B-cell epitopes QASVAYPATSYADFRAHNHWWNGP, SLQRSISPNSYNTARVDP and QLLGQTADVAGAAKSGPVQPMGDRGSVSPVGQ were considered M. leprae-specific and used to construct the gene encoding the recombinant antigen. The gene was constructed, the recombinant protein was expressed, purified and tested in ELISA using 252 sera, which contained samples from multibacillary (MB) or paucibacillary (PB) leprosy patients, from their household contacts and healthy individuals, as well as from patients with Chagas disease, visceral and tegumentary leishmaniases (VL/TL), malaria, tuberculosis, and HIV. Sensitivity (Se) and specificity (Sp) for MB and PB samples compared to sera from both healthy subjects and individuals with cross-reactive diseases were 100%. The Se value for MB and PB samples compared to sera from household contacts was 100%, but Sp was 64%. In conclusion, data suggest that this protein could be considered in future studies for leprosy diagnosis.

Leprosy Classification, Clinical Features, Epidemiology, and Host Immunological Responses: Failure of Eradication in 2023

Leprosy is of big concern in the medical fraternity. Leprosy is also known as Hansen's disease. It is a curable communicable disease that remains prevalent in most countries all over the globe. It is a chronic granulomatous infection commonly caused by Mycobacterium leprae and Mycobacterium lepromatosis, which mainly show an effect on the skin and peripheral nerves. To control the disease and minimize the impact of the disease, much effort has been put into it for decades. Nearly 0.2 million fresh cases were documented in 2017 worldwide in spite of being declared "eradicated" by the WHO in the year 2000. However, impressive achievements have been made in several countries, including India; still, we are lagging behind the ultimate goal of the final disappearance of leprosy. Extensive migration is a crucial element that may transmit leprosy to unaffected areas. Additionally, there are several areas in the USA where person-to-person leprosy transmission has been reported without a prior history of exposure. Recently, WHO instigated a new Global Leprosy Strategy 2021-2030, termed "Towards Zero Leprosy." In this article, we review the clinical features, leprosy epidemiology, transmission, classification, host immunological response, and diagnostic challenges.

Interplay among differential exposure to Mycobacterium leprae and TLR4 polymorphism impacts the immune response in household contacts of leprosy patients

Introduction

The aim of the present study was to investigate the association between the single nucleotide polymorphism (SNP) rs1927914 A/G in TLR4 gene and the immunological profile of household contacts (HHC) of leprosy patients. Leprosy classification is usually complex and requires the assessment of several clinical and laboratorial features.

Methods

Herein, we have applied distinct models of descriptive analysis to explore qualitative/quantitative changes in chemokine and cytokine production in HHC further categorized according to operational classification [HHC(PB) and HHC(MB)] and according to TLR4SNP.

Results and discussion

Our results showed that M. leprae stimuli induced an outstanding production of chemokines (CXCL8;CCL2; CXCL9; CXCL10) by HHC(PB), while increase levels of pro-inflammatory cytokines (IL-6; TNF; IFN-γ; IL-17) were observed for HHC(MB). Moreover, the analysis of chemokine and cytokine signatures demonstrated that A allele was associated with a prominent soluble mediator secretion (CXCL8; CXCL9; IL-6; TNF; IFN-γ). Data analysis according to TLR4 SNP genotypes further demonstrated that AA and AG were associated with a more prominent secretion of soluble mediators as compared to GG, supporting the clustering of AA and AG genotypes into dominant genetic model. CXCL8, IL-6, TNF and IL-17 displayed distinct profiles in HHC(PB) vs HHC(MB) or AA+AG vs GG genotype. In general, chemokine/cytokine networks analysis showed an overall profile of AA+GA-selective (CXCL9-CXCL10) and GG-selective (CXCL10-IL-6) axis regardless of the operational classification. However, mirrored inverted CCL2-IL-10 axis and a (IFN-γ-IL-2)-selective axis were identified in HHC(MB). CXCL8 presented outstanding performance to classify AA+AG from GG genotypes and HHC(PB) from HHC(MB). TNF and IL-17 presented elevated accuracy to classify AA+AG from GG genotypes and HHC(PB) (low levels) from HHC(MB) (high levels), respectively. Our results highlighted that both factors: i) differential exposure to M. leprae and ii) TLR4 rs1927914 genetic background impact the immune response of HHC. Our main results reinforce the relevance of integrated studies of immunological and genetic biomarkers that may have implications to improve the classification and monitoring of HHC in future studies.

A review of nutrition in neuropathic pain of leprosy

Leprosy is a neglected tropical disease (NTD) that continues to burden low- and middle-income countries (LMICs), despite being eliminated as a public health concern by the World Health Organization (WHO) in 2000. The causative agents, Mycobacterium leprae and Mycobacterium lepromatosis, affect nearly 200,000 individuals globally each year, with over 19,000 new cases detected in the Americas in 2020 alone. Canada has experienced an increasing incidence of leprosy, due to rising levels of travel and migration from endemic areas, reaching over 37,000 individuals with leprosy by the end of 2020. Patients experience a spectrum of signs and symptoms including hypopigmented cutaneous macules alongside peripheral neuropathy including peripheral neuropathic pain (PNP) and disabling sensory neuropathies. Despite the development of effective and curative therapeutics via multidrug therapy (MDT), many barriers to treatment adherence and effective immunological control of the pathogen challenge the care of patients with leprosy. Socioeconomic barriers, such as disability-related social stigma and often undiagnosed nutritional deficiencies, have resulted in heightened disease severity. PNP therapeutics are associated with significant side effects and remain ineffective as the majority of individuals will not experience a greater than 30% reduction of symptoms. Nutrient supplementation is known to be instrumental in reducing host oxidative stress, strengthening the immune system and mitigating comorbidities. Likewise, dietary lifestyle interventions known to be physiologically beneficial have recently emerged as powerful tools conferring neuroprotective effects, potentially mitigating PNP severity. However, a significant knowledge gap concerning the effect of adequate nutrition on host immunological control of leprosy and PNP severity exists. Further evaluation of this relationship will provide key insight into the pathogenesis of leprosy, strengthening the current body of literature.