The influence of innate and adaptative immune responses on the differential clinical outcomes of leprosy

Influence of Cytokine-Related genetic variants in TNF, IL6, IL1β, and IFNγ genes in the thalidomide treatment for Erythema nodosum leprosum in a Brazilian population sample

Erythema nodosum leprosum (ENL), an inflammatory reaction in leprosy, causes painful nodules, fever, and malaise due to immune system activation. Thalidomide is an effective treatment, although associated with important adverse effects. We aimed to evaluate the association of genetic variants in genes encoding tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) with the response to treatment of ENL with thalidomide. 148 patients from the South and Northeast regions of Brazil were included. Genomic DNA was isolated from blood and/or saliva samples using commercial kits, and genetic variants in TNF, IL6, IL1β, and IFNγ genes were genotyped by TaqMan system. We identified an association between polymorphisms in TNF (rs1799964C, rs1800630A, rs1799724T and rs1800629A) IL1β (rs4848306G, rs1143623G, rs16944A, and rs1143627A), IL6 (rs2069840C and rs2069845G) and IFNγ (rs2430561T) with thalidomide dose variation in a time-dependent manner. Associations of IL6 and TNF haplotypes with thalidomide dosage variation over the time of treatment were also observed. Polymorphisms in TNF, IL6, IL1β, and IFNγ genes may modulate their expression levels, potentially impacting the required dosage of thalidomide in the treatment of ENL. Our findings should be confirmed in further studies to estimate the size effect of these polymorphisms on ENL treatment with thalidomide.

A TLR7 Agonist Conjugated to a Nanofibrous Peptide Hydrogel as a Potent Vaccine Adjuvant

Toll-like receptors (TLRs) recognize pathogen- and damage-associated molecular patterns and, in turn, trigger the release of cytokines and other immunostimulatory molecules. As a result, TLR agonists are increasingly being investigated as vaccine adjuvants. Many of these agonists are small molecules that quickly diffuse away from the vaccination site, limiting their co-localization with antigens and, thus, their effect. Here, the small-molecule TLR7 agonist 1V209 is conjugated to a positively-charged multidomain peptide (MDP) hydrogel, K2, which was previously shown to act as an adjuvant promoting humoral immunity. Mixing the 1V209-conjugated K2 50:50 with the unfunctionalized K2 produces hydrogels that retain the shear-thinning and self-healing physical properties of the original MDP while improving the solubility of 1V209 more than 200-fold compared to the unconjugated molecule. When co-delivered with ovalbumin as a model antigen, 1V209-functionalized K2 produces a robust Th2 immune response and an antigen-specific Th1 immune response superior to alum, a widely used vaccine adjuvant. Together, these results suggest that K2 MDP hydrogels functionalized with 1V209 are a promising adjuvant for vaccines against infectious diseases, especially those benefiting from a combined Th1 and Th2 immune response.

Multimodal AI/ML for discovering novel biomarkers and predicting disease using multi-omics profiles of patients with cardiovascular diseases

Cardiovascular diseases (CVDs) are complex, multifactorial conditions that require personalized assessment and treatment. Advancements in multi-omics technologies, namely RNA sequencing and whole-genome sequencing, have provided translational researchers with a comprehensive view of the human genome. The efficient synthesis and analysis of this data through integrated approach that characterizes genetic variants alongside expression patterns linked to emerging phenotypes, can reveal novel biomarkers and enable the segmentation of patient populations based on personalized risk factors. In this study, we present a cutting-edge methodology rooted in the integration of traditional bioinformatics, classical statistics, and multimodal machine learning techniques. Our approach has the potential to uncover the intricate mechanisms underlying CVD, enabling patient-specific risk and response profiling. We sourced transcriptomic expression data and single nucleotide polymorphisms (SNPs) from both CVD patients and healthy controls. By integrating these multi-omics datasets with clinical demographic information, we generated patient-specific profiles. Utilizing a robust feature selection approach, we identified a signature of 27 transcriptomic features and SNPs that are effective predictors of CVD. Differential expression analysis, combined with minimum redundancy maximum relevance feature selection, highlighted biomarkers that explain the disease phenotype. This approach prioritizes both biological relevance and efficiency in machine learning. We employed Combination Annotation Dependent Depletion scores and allele frequencies to identify variants with pathogenic characteristics in CVD patients. Classification models trained on this signature demonstrated high-accuracy predictions for CVD. The best performing of these models was an XGBoost classifier optimized via Bayesian hyperparameter tuning, which was able to correctly classify all patients in our test dataset. Using SHapley Additive exPlanations, we created risk assessments for patients, offering further contextualization of these predictions in a clinical setting. Across the cohort, RPL36AP37 and HBA1 were scored as the most important biomarkers for predicting CVDs. A comprehensive literature review revealed that a substantial portion of the diagnostic biomarkers identified have previously been associated with CVD. The framework we propose in this study is unbiased and generalizable to other diseases and disorders.

Leprosy in Brazil: an analysis of the Global Burden of Disease estimates between 1990 and 2019

OBJECTIVE

To analyze the occurrence of leprosy in Brazil and its states between 1990 and 2019, according to Global Burden of Disease (GBD) estimates, and its correlation with development status.

STUDY DESIGN

A descriptive and analytical ecological epidemiological study.

METHODS

Rates of incidence, prevalence, and years lived with disability (YLD) due to leprosy, standardized by age, per 100,000 inhabitants, were analyzed. The trend analysis consisted of the joinpoint regression model and the average annual percentage change. The correlation between the incidence rate and the sociodemographic index (SDI) was investigated (Spearman test) at a 5% significance level. Incidence, prevalence and YLD rates were presented by country's states, sex, and age.

RESULTS

There was an average percentage decrease of -1.1% per year (P < 0.001) in the incidence rate in the country and, between 1990 and 2019, a decline from 4.8 to 3.5 per 100,000 inhabitants; prevalence from 26.1 to 22.2, and YLD from 1.1 to 1.0. The incidence rate was higher among men and the elderly. Maranhão (7.0 in 1990; 4.2 in 2019), Alagoas (6.6 in 1990; 4.1 in 2019), Acre (6.1 in 1990; 4.0 in 2019), Mato Grosso (5.2 in 1990 and 3.7 in 2019), and Mato Grosso do Sul (4.8 in 1990 and 3.7 in 2019) presented the highest incidence rates. A negative correlation was observed between SDI levels and leprosy incidence rates in 1990 (R = -0.71; P < 0.0001) and 2019 (R = -0.81; P < 0.0001).

CONCLUSIONS

Despite the decrease in the rates of leprosy incidence, prevalence, and YLDs over the analyzed period, Brazil has a long way towards achieving its eradication. The greater burden of the disease in males stands out. The estimated risk of the disease was higher in the states with the lowest SDI levels. Therefore, interventions must consider the heterogeneity of the disease burden geographically and between sociodemographic groups.

Shared challenges to the control of complex intracellular neglected pathogens

The complex intracellular pathogens Mycobacterium tuberculosis, Mycobacterium leprae, Leishmania spp., and Burkholderia pseudomallei, which cause tuberculosis, leprosy, leishmaniasis, and melioidosis respectively, represent major health threats with a significant global burden concentrated in low- and middle-income countries. While these diseases vary in their aetiology, pathology and epidemiology, they share key similarities in the biological and sociodemographic factors influencing their incidence and impact worldwide. In particular, their occurrence in resource-limited settings has important implications for research and development, disease prevalence and associated risk factors, as well as access to diagnostics and therapeutics. In accordance with the vision of the VALIDATE (VAccine deveLopment for complex Intracellular neglecteD pAThogeEns) Network, we consider shared challenges to the effective prevention, diagnosis and treatment of these diseases as shaped by both biological and social factors, illustrating the importance of taking an interdisciplinary approach. We further highlight how a cross-pathogen perspective may provide valuable insights for understanding and addressing challenges to the control of all four pathogens.

Case Report: Nonalcoholic Hepatic Steatosis Associated with Type-2 Leprosy Reaction

Leprosy reactions are complex immune events, generating disabling consequences and threatening the lives of those who experience them. This case report addresses the episode of a 28-year-old female patient who suffered a severe type-2 leprosy reaction, characterized by significant hepatic involvement, specifically, nonalcoholic hepatic steatosis. This case report underscores the importance of maintaining a high level of clinical suspicion, early recognition, accurate diagnosis, and immediate addressing of these types of reactions that may arise in the context of leprosy.

An update of the diagnosis, treatment, and prevention of leprosy: A narrative review

Leprosy is an infectious disease that remains a public health concern. It is caused by acid-fast Bacillus leprae, which primarily affects the skin and peripheral nerves, potentially leading to long-term disability and stigma. However, current and previous efforts have focused on developing better diagnostic and therapeutic interventions for leprosy, and its prevention needs to be addressed. In this review, we organize the currently published papers and provide updates on the global epidemiology, diagnosis, treatment, and prevention of leprosy. Several online databases, including MEDLINE (National Library of Medicine, Bethesda, MD), PubMed, EMBASE, Web of Science, and Google Scholar, were searched to collect relevant published papers. As a public health issue, the World Health Organization set the goal of leprosy elimination with a prevalence of <1 case per 10,000 people, which was achieved in 2000 and in most countries by 2010, mainly owing to the treatment of leprosy using drugs starting in 1980 and no-cost access for patients since 1995. Although diagnostic and therapeutic techniques have improved, the new occurrence of leprosy remains a critical global disease burden. With continuous technological improvements in diagnosing and treating leprosy, obtaining more relevant healthcare knowledge and preventing leprosy disability are crucial.

Identification of potential biomarkers of leprosy: A study based on GEO datasets

Leprosy has a high rate of cripplehood and lacks available early effective diagnosis methods for prevention and treatment, thus novel effective molecule markers are urgently required. In this study, we conducted bioinformatics analysis with leprosy and normal samples acquired from the GEO database(GSE84893, GSE74481, GSE17763, GSE16844 and GSE443). Through WGCNA analysis, 85 hub genes were screened(GS > 0.7 and MM > 0.8). Through DEG analysis, 82 up-regulated and 3 down-regulated genes were screened(|Log2FC| > 3 and FDR < 0.05). Then 49 intersection genes were considered as crucial and subjected to GO annotation, KEGG pathway and PPI analysis to determine the biological significance in the pathogenesis of leprosy. Finally, we identified a gene-pathway network, suggesting ITK, CD48, IL2RG, CCR5, FGR, JAK3, STAT1, LCK, PTPRC, CXCR4 can be used as biomarkers and these genes are active in 6 immune system pathways, including Chemokine signaling pathway, Th1 and Th2 cell differentiation, Th17 cell differentiation, T cell receptor signaling pathway, Natural killer cell mediated cytotoxicity and Leukocyte transendothelial migration. We identified 10 crucial gene markers and related important pathways that acted as essential components in the etiology of leprosy. Our study provides potential targets for diagnostic biomarkers and therapy of leprosy.

Association of CC-chemokine ligand-2 gene polymorphisms with leprosy reactions

BACKGROUND

C-C motif chemokine ligand 2, a gene that codes for a protein involved in inflammation. Certain SNPs in the CCL2 gene have been studied for their potential associations with susceptibility to various diseases. These SNPs may affect the production and function of the CCL2 protein, which is involved in the recruitment of immune cells to the site of inflammation. Variations in CCL2 may influence the immune response to Mycobacterium leprae infection.

OBJECTIVE

To investigate the association of the C-C motif chemokine ligand-2 single nucleotide polymorphisms with leprosy.

METHODS

CCL2 single nucleotide polymorphisms were analyzed in a total of 975 leprosy patients and 357 healthy controls. Of those, 577 leprosy and 288 healthy controls were analyzed by PCR-RFLP for CCL2 -2518 A>G, 535 leprosy and 290 controls for CCL2 -362 G>C, 295 leprosy and 240 controls for CCL2 -2134 T>G, 325 leprosy and 288 controls for CCL2 -1549 A>T SNPs by melting curve analysis using hybridization probe chemistry and detection by fluorescence resonance energy transfer (FRET) technique in Realtime PCR. The levels of CCL2, IL-12p70, IFN-γ, TNF-α, and TGF-β were estimated in sera samples and correlated with CCL2 genotypes.

RESULTS

The frequency of the GCT (-2518 A>G, -362 G>C, -2134 T>G) haplotype is observed to be higher in leprosy patients compared to healthy controls (P = 0.04). There was no significant difference observed in genotypic frequencies between leprosy patients and healthy controls {(-2518A>G, p = 0.53), (-362 G>C, p = 0.01), (-2134 T>G, p = 0.10)}. G allele at the -2134 site is predominant in leprosy (borderline) without any reaction (8 %) compared to borderline patients with RR reactions (2.1 %) (P = 0.03). GG genotype (p = 0.008) and G allele at -2518 (p = 0.030) of the CCL 2 gene were found to be associated with patients with ENL reaction. An elevated level of serum CCL2 was observed in leprosy patients with the -2518 AA and AG genotypes (p = 0.0001).

CONCLUSIONS

G allele and GG genotype at the CCL2 -2518 site are associated with a risk of ENL reactions.

A comparative study on the detection of Mycobacterium leprae DNA in urine samples of leprosy patients using Rlep-PCR with other conventional samples

BACKGROUND

Mycobacterium leprae causes leprosy that is highly stigmatized and chronic infectious skin disease. Only some diagnostic tools are being used for the identification M. leprae in clinical samples, such as bacillary detection, and histopathological tests. These methods are invasive and often have low sensitivity. Currently, the PCR technique has been used as an effective tool fordetecting M. leprae DNA across different clinical samples. The current study aims to detect M. leprae DNA in urine samples of untreated and treated leprosy patients using the Rlep gene (129 bp) and compared the detection among Ridley-Jopling Classification.

METHODS

Clinical samples (Blood, Urine, and Slit Skin Smears (SSS)) were collected from leprosy and Non-leprosy patients. DNA extraction was performed using standard laboratory protocol and Conventional PCR was carried out for all samples using Rlep gene target and the amplicons of urine samples were sequenced by Sanger sequencing to confirm the Rlep gene target.

RESULTS

The M. leprae DNA was successfully detected in all clinical samples across all types of leprosy among all the study groups using RLEP-PCR. Rlep gene target was able to detect the presence of M. leprae DNA in 79.17% of urine, 58.33% of blood, and 50% of SSS samples of untreated Smear-Negative leprosy patients. The statistical significant difference (p = 0.004) was observed between BI Negative (Slit Skin Smear test) and RLEP PCR positivity in urine samples of untreated leprosy group.

CONCLUSION

The PCR positivity using Rlep gene target (129 bp) was highest in all clinical samples among the study groups, across all types of leprosy. Untreated tuberculoid and PNL leprosy patients showed the highest PCR positivity in urine samples, indicating its potential as a non-invasive diagnostic tool for leprosy and even for contact screening.

A TLR7 Agonist Conjugated to a Nanofibrous Peptide Hydrogel as a Potent Vaccine Adjuvant

Toll-like receptors (TLRs) recognize pathogen- and damage-associated molecular patterns and, in turn, trigger the release of cytokines and other immunostimulatory molecules. As a result, TLR agonists are increasingly being investigated as vaccine adjuvants, though many of these agonists are small molecules that quickly diffuse away from the vaccination site, limiting their co-localization with antigens and, thus, their effect. Here, the small-molecule TLR7 agonist 1V209 is conjugated to a positively-charged multidomain peptide (MDP) hydrogel, K 2 , which was previously shown to act as an adjuvant promoting humoral immunity. Mixing the 1V209-conjugated K 2 50:50 with the unfunctionalized K 2 produces hydrogels that retain the shear-thinning and self-healing physical properties of the original MDP, while improving the solubility of 1V209 more than 200-fold compared to the unconjugated molecule. When co-delivered with ovalbumin as a model antigen, 1V209-functionalized K 2 produces antigen-specific IgG titers that were statistically similar to alum, the gold standard adjuvant, and a significantly lower ratio of Th2-associated IgG1 to Th1-associated IgG2a than alum, suggesting a more balanced Th1 and Th2 response. Together, these results suggest that K 2 MDP hydrogels functionalized with 1V209 are a promising adjuvant for vaccines against infectious diseases, especially those benefiting from a combined Th1 and Th2 immune response.

Table of Contents

Activation of toll-like receptors (TLRs) stimulates a signaling cascade to induce an immune response. A TLR7 agonist was conjugated to an injectable peptide hydrogel, which was then used to deliver a model vaccine antigen. This platform produced antibody titers similar to the gold standard adjuvant alum and demonstrated an improved balance between Th1- and Th2-mediated immunity over alum.

Leprosy reactions: Unraveling immunological mechanisms underlying tissue damage in leprosy patients

Leprosy is a chronic granulomatous infectious and disabling disease caused by two mycobacteria, Mycobacterium leprae and Mycobacterium lepromatosis. Acute inflammatory responses, known as leprosy reactions, are significant contributors to disabilities. Three types of leprosy reactions have been identified based on excessive cytokine release (e.g. type 1) or the accumulation of immune complexes in tissues inducing multiorgan damage (e.g. types 2 and 3). The type of leprosy reaction has implications on treatment and management strategies, yet are not well understood by health workers caring for leprosy patients. We attempt to describe the immunologic mechanisms behind the different leprosy reactions and the rationale for tailoring clinical treatment and management to the particular type of leprosy reaction based on the underlying immunologic situation.

A cost-effectiveness analysis of a novel algorithm to sequentially diagnose leprosy based on manufactured tests under the SUS perspective

Brazil has the second largest number of leprosy cases (a disease with a significant burden) in the world. Despite global and local efforts to eliminate this public health problem, inadequate or late diagnosis contribute to perpetuate its transmission, especially among household contacts. Tests such as the rapid IgM antibody detection (RT) and real-time polymerase chain reaction (RT-PCR) were developed to overcome the challenges of early diagnosis of leprosy. This study aimed to analyze the cost-effectiveness of a new diagnostic algorithm recommended by the Brazilian government to diagnose leprosy in household contacts of confirmed leprosy cases, which includes the RT and RT-PCR tests. A decision tree model was constructed and the perspective of the Brazilian Unified National Health System (SUS) and a 1-year time horizon were adopted. Only direct medical costs related to diagnostic tests were included. Effectiveness was measured as the number of avoided undiagnosed leprosy cases. Different scenarios were analyzed. The sequential use of RT, slit-skin smear (SSS) microscopy, and RT-PCR as recommended by the Brazilian Ministry of Health was compared to a base case (isolated SSS microscopy), yielding an incremental cost-effectiveness ratio of USD 616.46 per avoided undiagnosed leprosy case. Univariate sensitivity analysis showed that the prevalence of leprosy among household contacts was the variable that influenced the model the most. This is the first economic model to analyze a diagnostic algorithm of leprosy. Results may aid managers to define policies and strategies to eradicate leprosy in Brazil.

Association between asthma, rhinitis and atopic dermatitis with leprosy: A case-control study

Background Considering the cross-regulation of Th1 and Th2 responses, we hypothesised that atopic diseases (Th2) inhibit the protective Th1 immune response to Mycobacterium leprae and exacerbates leprosy. Objective In this study, we aimed to evaluate the association between leprosy and atopic diseases. Methods To evaluate the association of atopic diseases with leprosy, we conducted a case-control study that included leprosy patients (n = 333) and their household contacts (n = 93). The questionnaire from the International Study of Asthma and Allergies in Childhood, which is validated in several countries for epidemiological diagnosis of atopic diseases, was applied to determine the occurrence of atopic diseases, allergic rhinitis, asthma, and atopic dermatitis among leprosy patients and the household contacts. Results Considering clinical and epidemiological data, among the leprosy group 51.6% (n = 172) were determined to have at least one atopic disease, while atopy was observed less frequently at 40.86% among household contacts (n = 38). When two or more atopic diseases were assessed, the frequency was significantly higher among the leprosy patients than in the household contacts (21.9% vs. 11.8%; P-value = 0.03). Likewise, the frequency of asthma was significantly higher among leprosy patients (21%) than in the household contacts (10.8%; P-value = 0.02). Thus, our analyses revealed an association of atopic diseases with leprosy, with a significant linear increase in the occurrence of leprosy with an increase in the number of atopic diseases (P-value = 0.01). Limitation Due to the difficulties in recruiting household contacts that have prolonged contact with patients, but are not genetically related to the patient, the household contacts group is smaller than the leprosy patient group. Conclusion The data reveal an association between atopic diseases and leprosy outcomes. This knowledge could improve the treatment of leprosy patients with co-incident atopic diseases.

Th17 Cells and Cytokines in Leprosy: Understanding the Immune Response and Polarization

While there are conflicting data concerning interleukin (IL)-17 levels in the serum of patients with leprosy compared with those in healthy controls, higher levels have been more evident in the tuberculoid clinical form of leprosy and type 1 reactions. This review aimed to highlight the role of Th17 cells and their cytokines in leprosy. Cytokines such as IL-1β and IL-23 induce Th17, while transforming growth factor beta and IL-10 inhibit Th17, indicating that the balance between Th17 and regulatory T cells is crucial for leprosy polarization. However, more comprehensive paired studies are required to better elucidate the role of Th17 cells in leprosy.

Immunohistochemical Characterization of M1, M2, and M4 Macrophages in Leprosy Skin Lesions

Mycobacterium leprae is the etiological agent of leprosy. Macrophages (Mφs) are key players involved in the pathogenesis of leprosy. In this study, immunohistochemical analysis was performed to examine the phenotype of Mφ subpopulations, namely M1, M2, and M4, in the skin lesions of patients diagnosed with leprosy. Based on the database of treatment-naïve patients treated between 2015 and 2019 at the Department of Dermatology of the University of the State of Pará, Belém, routine clinical screening samples were identified. The monolabeling protocol was used for M1 macrophages (iNOS, IL-6, TNF-α) and M2 macrophages (IL-10, IL-13, CD163, Arginase 1, TGF-β, FGFb), and the double-labeling protocol was used for M4 macrophages (IL-6, MMP7, MRP8, TNF-α e CD68). To confirm the M4 macrophage lineage, double labeling of the monoclonal antibodies CD68 and MRP8 was also performed. Our results demonstrated a statistically significant difference for the M1 phenotype among the Virchowian (VV) (4.5 ± 1.3, p < 0.0001), Borderline (1.6 ± 0.4, p < 0.0001), and tuberculoid (TT) (12.5 ± 1.8, p < 0.0001) clinical forms of leprosy. Additionally, the M2 phenotype showed a statistically significant difference among the VV (12.5 ± 2.3, p < 0.0001), Borderline (1.3 ± 0.2, p < 0.0001), and TT (3.2 ± 0.7, p < 0.0001) forms. For the M4 phenotype, a statistically significant difference was observed in the VV (9.8 ± 1.7, p < 0.0001), Borderline (1.2 ± 0.2, p < 0.0001), and TT (2.6 ± 0.7, p < 0.0001) forms. A significant correlation was observed between the VV M1 and M4 (r = 0.8712; p = 0.0000) and between the VV M2 × TT M1 (r = 0.834; p = 0.0002) phenotypes. The M1 Mφs constituted the predominant Mφ subpopulation in the TT and Borderline forms of leprosy, whereas the M2 Mφs showed increased immunoexpression and M4 was the predominant Mφ phenotype in VV leprosy. These results confirm the relationship of the Mφ profile with chronic pathological processes of the inflammatory response in leprosy.

Case Report: Necrotizing Erythema Nodosum as a Manifestation of Lepromatous Leprosy Relapse 50 Years after the Initial Infection

Leprosy is a chronic infection caused by Mycobacterium leprae and Mycobacterium lepromatosis that preferentially compromises peripheral nerve, skin, and mucous membranes. Colombia achieved the goal of leprosy elimination in 1997. However, in Urabá (Colombia), there has been an increase in leprosy cases beginning in 2020. This case report shows a leprosy relapse 5 decades after the initial infection debuted as a necrotizing erythema nodosum leprosum. Therefore, long-term follow-up of patients with risk factors for relapse is emphasized, especially those treated before the standard of multidrug therapy (dapsone, clofazimine, and rifampin). This case report stresses the importance the importance of clinical follow-up and surveillance of patients with these events of interest for the public health.

sTREM-1 and TNF-α levels are associated with the clinical outcome of leprosy patients

Leprosy reaction (LR) and physical disability (PD) are the most significant clinical complications of leprosy. Herein, we assessed the circulating serum-sTREM-1 and TNF-α levels and their genetic polymorphisms in leprosy. Serum-sTREM-1 and TNF-α levels were measured in leprosy patients (LP) before treatment (n = 51) and from their household contacts (HHCs; n = 25). DNA samples were genotyped using TREM-1 rs2234246 and TNF-α rs1800629-SNP in 210 LPs and 168 endemic controls. The circulating sTREM-1 and TNF-α levels are higher in the multibacillary form. The ROC curve of the serum-sTREM-1 levels was able to differentiate LR from non-LR and PD from non-PD. Similarly, LPs with serum-sTREM-1 levels >210 pg/ml have 3-fold and 6-fold higher chances of presenting with LR and PD, respectively. Genotypes CC+CT of the TREM-1 were associated with leprosy. Taken together, our analyses indicated that sTREM-1 and TNF-α play an important role in the pathogenesis of leprosy and provide promising biomarkers to assist in the diagnosis of leprosy complications.

Leptin Deficiency May Influence the Divergence of Cell-Mediated Immunity Between Lepromatous and Tuberculoid Leprosy Patients

Leprosy is a disease caused by an intracellular bacillus bacterium called Mycobacterium leprae which lives and multiplies in the hosts' macrophages and Schwann cells. Depending on the degree of the host's cell-mediated immunity (CMI) response to the bacilli, the disease manifests itself in five clinical spectra ranging from polar tuberculoid (TT) to polar lepromatous leprosy (LL). A very high level of T helper 1 (Th1) driven bacilli-specific CMI is seen in the TT form, whereas this response is essentially nonexistent in the LL form. As a result, there is very low or absent bacillary load and localized nodular lesions in TT patients. On the contrary, LL patients presented with high bacillary load and generalized lesions due to low CMI response. The mechanism underlying this divergence of CMI response is not clearly elucidated yet. However, mounting evidence links it to an elevated number of Th1 and Th17 suppressing CD4+ CD25+ FOXP3+ T regulatory cells (Treg cells) which are abundantly found in LL than in TT patients. The predominance of these cells in LL patients is partly attributed to a deficiency of leptin, the cytokine-like peptide hormone, in these patients. Becausea normal level of leptin promotes the proliferation and preferential differentiation of effector T cells (Th1 and Th17) while inhibiting the growth and functional responsiveness of the Treg cells. In contrast, leptin deficiency or neutralization was reported to exert the opposite effect on Treg cells and effector T cells. Other smaller subsets of lymphocytes such as gamma delta (γδ) T cells and B regulatory cells are also modulated by leptin level in the pathogenesis of leprosy. Leptin may therefore regulate the divergence of CMI between TT and LL patients by regulating the homeostasis of effector T cells and Treg cells, and this review will examine the underlying mechanism for this.

Pathogenicity and virulence of Mycobacterium leprae

Leprosy is caused by Mycobacterium leprae (M. leprae) and M. lepromatosis, an obligate intracellular organism, and over 200,000 new cases occur every year. M. leprae parasitizes histiocytes (skin macrophages) and Schwann cells in the peripheral nerves. Although leprosy can be treated by multidrug therapy, some patients relapse or have a prolonged clinical course and/or experience leprosy reaction. These varying outcomes depend on host factors such as immune responses against bacterial components that determine a range of symptoms. To understand these host responses, knowledge of the mechanisms by which M. leprae parasitizes host cells is important. This article describes the characteristics of leprosy through bacteriology, genetics, epidemiology, immunology, animal models, routes of infection, and clinical findings. It also discusses recent diagnostic methods, treatment, and measures according to the World Health Organization (WHO), including prevention. Recently, the antibacterial activities of anti-hyperlipidaemia agents against other pathogens, such as M. tuberculosis and Staphylococcus aureus have been investigated. Our laboratory has been focused on the metabolism of lipids which constitute the cell wall of M. leprae. Our findings may be useful for the development of future treatments.

The impact of single-cell genomics on the field of mycobacterial infection

Genome sequencing projects of humans and other organisms reinforced that the complexity of biological systems is largely attributed to the tight regulation of gene expression at the epigenome and RNA levels. As a consequence, plenty of technological developments arose to increase the sequencing resolution to the cell dimension creating the single-cell genomics research field. Single-cell RNA sequencing (scRNA-seq) is leading the advances in this topic and comprises a vast array of different methodologies. scRNA-seq and its variants are more and more used in life science and biomedical research since they provide unbiased transcriptomic sequencing of large populations of individual cells. These methods go beyond the previous “bulk” methodologies and sculpt the biological understanding of cellular heterogeneity and dynamic transcriptomic states of cellular populations in immunology, oncology, and developmental biology fields. Despite the large burden caused by mycobacterial infections, advances in this field obtained via single-cell genomics had been comparatively modest. Nonetheless, seminal research publications using single-cell transcriptomics to study host cells infected by mycobacteria have become recently available. Here, we review these works summarizing the most impactful findings and emphasizing the different and recent single-cell methodologies used, potential issues, and problems. In addition, we aim at providing insights into current research gaps and potential future developments related to the use of single-cell genomics to study mycobacterial infection.

In silico designing of a recombinant multi-epitope antigen for leprosy diagnosis

BACKGROUND

Leprosy is caused by Mycobacterium leprae and Mycobacterium lepromatosis. Most of the affected population lives in low-income countries and may take up to 10 years to show any clinical signs, which is how physicians diagnose it. However, due to progressive cell damage, early diagnosis is very important. The best way to confirm leprosy is through bacilloscopic, which only confirms the diagnosis and has low accuracy or PCR, that requires specialized operators and is expensive. Since the bacteria are fastidious and do not grow in any culture media, therefore, diagnosing leprosy in the lab is still a challenge. In this concern, a recombinant multi-epitope protein can be a beneficial strategy in the management of the diagnosis, as diverse immunogenic epitopes are precisely selected to detect specific antibodies. Therefore, the purposes of the present study were to select immunogenic epitopes from different relevant proteins, with immunogenic properties, and then to construct a recombinant multi-epitope protein that accuses the presence of the antibodies in the early stages of the disease, making it more than appropriate to be applied as a diagnostic tool.

RESULTS

We selected 22 common proteins from both species and, using bioinformatics tools, predicted B and T cell epitopes. After multiple filtering and analyzing, we ended up with 29 epitopes {MHC-I (total 18) and MHC-II (total 11)} from 10 proteins, which were then merged into one construct. Its secondary and tertiary structures were also predicted and refined to comprise the amino acid residues in the best conformation possible. The multi-epitope protein construct was stable, non-host homologous, non-allergic, non-toxic, and elicit humoral and cellular responses. It has conformational B cell epitopes and potential to elicit IFN-γ, IL-4, and IL-10 secretion.

CONCLUSIONS

This novel recombinant multi-epitope protein constructed using the common epitopes from M. leprae and M. lepromatosis has a huge immunological potential, is stable, and can be lyophilized to be used in ELISA plates or even in biosensors, which are user-friendly diagnosis tools, facilitating translation into human sample tests.

Leprosy: A Review of Epidemiology, Clinical Diagnosis, and Management

Leprosy is a neglected infectious disease caused by acid-fast bacillus Mycobacterium leprae. It primarily affects the skin and then progresses to a secondary stage, causing peripheral neuropathy with potential long-term disability along with stigma. Leprosy patients account for a significant proportion of the global disease burden. Previous efforts to improve diagnostic and therapeutic techniques have focused on leprosy in adults, whereas childhood leprosy has been relatively neglected. This review aims to update the diagnostic and therapeutic recommendations for adult and childhood leprosy. This review summarizes the clinical, bacteriological, and immunological approaches used in the diagnosis of leprosy. As strategies for the diagnosis and management of leprosy continue to develop better and more advanced knowledge, control and prevention of leprosy are crucial.

Serum Levels of Ficolin-3 and Mannose-Binding Lectin in Patients with Leprosy and Their Family Contacts in a Hyperendemic Region in Northeastern Brazil

The present study aimed at analyzing the serum levels of mannose-binding lectin (MBL) and ficolin-3 (FCN3) in leprosy patients and their healthy family contacts in a hyperendemic region in northeastern Brazil. A cross-sectional study was carried out with 90 patients who had been diagnosed with leprosy and 79 healthy family contacts. Serum levels of the MBL and FCN3 proteins were measured using the immunofluorometric assay (ELISA). Clinical information was determined from the patients’ charts. It was observed that the leprosy patients were more likely to be male (OR = 2.17; p = 0.01) and younger than fifteen years of age (OR = 2.01; p = 0.03) when compared to the family contacts. Those under 15 years of age had higher levels of MBL (4455 ng/mL) than those over 15 years of age (2342 ng/mL; p = 0.018). Higher FCN3 levels were identified in patients with indeterminate leprosy (41.9 µg/mL) compared to those with the lepromatous form (34.3 µg/mL; p = 0.033) and in those with no physical disabilities (38.1 µg/mL) compared to those with some disability (p = 0.031). Higher FCN3 levels were also observed in the group of patients without leprosy reactions (37.4 µg/mL) compared to those with type 1 (33.7 µg/mL) and type 2 (36.1 µg/mL) reactions. The MBL levels were higher in children under 15 years of age than they were in adults. It was evidenced that higher FCN3 serum levels were associated with early and transient clinical forms and lower expression in severe forms of leprosy.

Impact of the COVID-19 pandemic on the diagnosis of leprosy in Brazil: An ecological and population-based study

BACKGROUND

The pandemic caused by COVID-19 has seriously affected global health, resulting in the suspension of many regular health services, making the diagnosis of other infections difficult. Therefore, this study aimed to assess the impact of the COVID-19 pandemic on the diagnosis of leprosy in Brazil during the year 2020.

METHODS

We evaluated the monthly incidence of leprosy and calculated the percentage change to verify whether there was an increase or decrease in the number of leprosy cases in 2020, considering the monthly average of cases over the previous 5 years. We used interrupted time series analysis to assess the trend in the diagnosis of leprosy before and after the start of COVID-19 in Brazil and prepared spatial distribution maps, considering the percentage variation in each state.

FINDINGS

We verified a reduction of 41.4% of leprosy cases in Brazil in 2020. Likewise, there was a reduction of leprosy notifications in children under 15 years-old (-56.82%). Conversely, the diagnosis of multibacillary leprosy increased (8.1%). There was a decreasing trend in the leprosy incidence in the general population between 2015 and 2020 in Brazil. Spatial distribution maps depicted a reduction of up to 100% in new cases of leprosy in some states.

INTERPRETATION

Along with COVID-19 spread there was a reduction in leprosy diagnosis in the general population and children under 15 years-old, and also an increase in multibacillary cases diagnosed, signalling a serious impact of the pandemic on leprosy control strategies in Brazil.

FUNDING

This research received no specific grants.

Evaluation of Polymorphisms in Toll-Like Receptor Genes as Biomarkers of the Response to Treatment of Erythema Nodosum Leprosum

Erythema nodosum leprosum (ENL) is an inflammatory complication caused by a dysregulated immune response to Mycobacterium leprae. Some Toll-like receptors (TLRs) have been identified as capable of recognizing antigens from M. leprae, triggering a wide antimicrobial and inflammatory response. Genetic polymorphisms in these receptors could influence in the appearance of ENL as well as in its treatment. Thus, the objective of this work was to evaluate the association of genetic variants of TLRs genes with the response to treatment of ENL with thalidomide and prednisone. A total of 162 ENL patients were recruited from different regions of Brazil and clinical information was collected from their medical records. Genomic DNA was isolated from blood and saliva samples and genetic variants in TLR1 (rs4833095), TLR2 (rs3804099), TLR4 (rs1927914), and TLR6 (rs5743810) genes were genotyped by TaqMan real-time PCR system. In order to evaluate the variants' association with the dose of the medications used during the treatment, we applied the Generalized Estimating Equations (GEE) analysis. In the present sample, 123 (75.9%) patients were men and 86 (53.1%) were in treatment for leprosy during the ENL episode. We found an association between polymorphisms in TLR1/rs4833095, TLR2/rs3804099, TLR4/rs1927914, and TLR6/rs5783810 with the dose variation of thalidomide in a time-dependent manner, i.e., the association with the genetic variant and the dose of the drug was different depending on the moment of the treatment evaluated. In addition, we identified that the association of polymorphisms in TLR1/rs4833095, TLR2/rs3804099, and TLR6/rs5783810 with the dose variation of prednisone also were time-dependent. Despite these associations, in all the interactions found, the influence of genetic variants on dose variation was not clinically relevant for therapeutic changes. The results obtained in this study show that TLRs polymorphism might play a role in the response to ENL treatment, however, in this context, they could not be considered as useful biomarkers in the clinical setting due small differences in medication doses. A larger sample size with patients with a more genetic profile is fundamental in order to estimate the association of genetic variants with the treatment of ENL and their clinical significance.

The Interplay Between Neuroinfections, the Immune System and Neurological Disorders: A Focus on Africa

Neurological disorders related to neuroinfections are highly prevalent in Sub-Saharan Africa (SSA), constituting a major cause of disability and economic burden for patients and society. These include epilepsy, dementia, motor neuron diseases, headache disorders, sleep disorders, and peripheral neuropathy. The highest prevalence of human immunodeficiency virus (HIV) is in SSA. Consequently, there is a high prevalence of neurological disorders associated with HIV infection such as HIV-associated neurocognitive disorders, motor disorders, chronic headaches, and peripheral neuropathy in the region. The pathogenesis of these neurological disorders involves the direct role of the virus, some antiretroviral treatments, and the dysregulated immune system. Furthermore, the high prevalence of epilepsy in SSA (mainly due to perinatal causes) is exacerbated by infections such as toxoplasmosis, neurocysticercosis, onchocerciasis, malaria, bacterial meningitis, tuberculosis, and the immune reactions they elicit. Sleep disorders are another common problem in the region and have been associated with infectious diseases such as human African trypanosomiasis and HIV and involve the activation of the immune system. While most headache disorders are due to benign primary headaches, some secondary headaches are caused by infections (meningitis, encephalitis, brain abscess). HIV and neurosyphilis, both common in SSA, can trigger long-standing immune activation in the central nervous system (CNS) potentially resulting in dementia. Despite the progress achieved in preventing diseases from the poliovirus and retroviruses, these microbes may cause motor neuron diseases in SSA. The immune mechanisms involved in these neurological disorders include increased cytokine levels, immune cells infiltration into the CNS, and autoantibodies. This review focuses on the major neurological disorders relevant to Africa and neuroinfections highly prevalent in SSA, describes the interplay between neuroinfections, immune system, neuroinflammation, and neurological disorders, and how understanding this can be exploited for the development of novel diagnostics and therapeutics for improved patient care.

The immune-suppressive landscape in lepromatous leprosy revealed by single-cell RNA sequencing

Lepromatous leprosy (L-LEP), caused by the massive proliferation of Mycobacterium leprae primarily in macrophages, is an ideal disease model for investigating the molecular mechanism of intracellular bacteria evading or modulating host immune response. Here, we performed single-cell RNA sequencing of both skin biopsies and peripheral blood mononuclear cells (PBMCs) of L-LEP patients and healthy controls. In L-LEP lesions, we revealed remarkable upregulation of APOE expression that showed a negative correlation with the major histocompatibility complex II gene HLA-DQB2 and MIF, which encodes a pro-inflammatory and anti-microbial cytokine, in the subset of macrophages exhibiting a high expression level of LIPA. The exhaustion of CD8⁺ T cells featured by the high expression of TIGIT and LAG3 in L-LEP lesions was demonstrated. Moreover, remarkable enhancement of inhibitory immune receptors mediated crosstalk between skin immune cells was observed in L-LEP lesions. For PBMCs, a high expression level of APOE in the HLA-DR^highFBP1^high monocyte subset and the expansion of regulatory T cells were found to be associated with L-LEP. These findings revealed the primary suppressive landscape in the L-LEP patients, providing potential targets for the intervention of intracellular bacteria caused persistent infections.

The genetic determinants of Mycobacterium leprae resistance to antimicrobial drugs

The review is devoted to the appearance of resistance of a slowly developing disease leprosy to antimicrobial therapy (AMP), primarily recommended by the World Health Organization. The main danger of drug resistant leprosy is in the difficulty of identifying, since the causative agent of the disease is not cultivated on artificial media, and the methods for diagnosing drug resistance that are currently used take a long time. The drug resistance of the Mycobacterium leprae strain even to individual components of combination drug therapy result to the development of symptoms of the disease despite undergo anti-leprosy therapy, which in turn can cause the patient to become disabled. Currently, in the Russian Federation, there is no approved test for detecting Mycobacterium leprae DNA, and the determination of genetic determinants of resistance is carried out by sequencing genome regions determined by WHO recommendations: small gyrA, folP and rpoB genes loci. At the same time, modern studies in endemic regions reveal an increased level of Mycobacterium leprae strains resistant to individual components of combined drug therapy. The use of next generation sequencing (NGS) has made it possible to identify additional genetic determinants of leprosy resistance to the components of combination drug therapy. The current situation is relevant to antimicrobal drug resistance surveillance by using of quick identification systems for most frequent genetic resistance determinants of Mycobacterium leprae. The literature search was carried out using keywords in the Scopus, PubMed and RSCI databases.

Analysis of the myeloid-derived suppressor cells and annexin A1 in multibacillary leprosy and reactional episodes

Background

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. Patients have distinct clinical forms, and the host´s immunological response regulate those manifestations. In this work, the presence of the myeloid-derived suppressor cell and the regulatory protein annexin A1 is described in patients with multibacillary leprosy and with type 1 and 2 reactions.

Methods

Patients were submitted to skin biopsy for histopathological analysis to obtain a bacilloscopic index. Immunofluorescence was used to detect myeloid-derived suppressor cells and annexin A1.

Results

The data demonstrated that the presence of granulocytic and monocytic myeloid-derived suppressor cells in leprosy patients. A high number of monocytic myeloid-derived suppressor cells were observed in lepromatous leprosy and type 2 reactional patients. The presence of annexin A1 was observed in all myeloid-derived suppressor cells. In particular, the monocytic myeloid-derived suppressor cell in the lepromatous patients has higher levels of this protein when compared to the reactional patients. This data suggest that the higher expression of this protein may be related to regulatory response against a severe infection, contributing to anergic response. In type 1 reactional patients, the expression of annexin A1 was reduced.

Conclusions

Myeloid-derived suppressor cell are present in leprosy patients and annexin A1 might be regulated the host response against Mycobacterium leprae.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06744-x.

Intramuscular Boosting with hIFN-Alpha 2b Enhances BCGphipps-Induced Protection in a Murine Model of Leprosy

Host immunity to Mycobacterium leprae encompasses a spectrum of mechanisms that range from cellular immunity-driven protection to damage associated with humoral immunity as in type-2 leprosy reactions. Although type I interferons (IFNs) participate in eliminating intracellular pathogens, their contribution to the production of antibodies and CD3+ FOXP3+ regulatory T cells (Tregs) in BCG vaccine-mediated protection in leprosy is unknown. BCGphipps (BCGph) priming followed by intramuscular hIFN-α 2b boost significantly reduced lesion size and Mycobacterium lepraemurium growth in the skin. T follicular regulatory cells (TFR), a subset of Tregs induced by immunization or infection, reside in the germinal centers (GCs) and modulate antibody production. We found impaired Treg induction and improved GCs in draining lymph nodes of BCGph primed and hIFN-α 2b boosted mice. Moreover, these mice elicited significant amounts of IL-4 and IL-10 in serum. Thus, our results support the adjuvant properties of hIFN-α 2b in the context of BCGph priming to enhance protective immunity against skin leprosy.

Serum IgA Antibodies Specific to M. leprae Antigens as Biomarkers for Leprosy Detection and Household Contact Tracking

Leprosy remains endemic in several developing countries, such as India and Brazil, in part due to delayed diagnosis that facilitates ongoing transmission. Although immunoglobulins against several Mycobacterium leprae antigens have been indicated for the early diagnosis, and IgA participates in the early stages of leprosy and in subclinical infection, relatively little research has examined anti-M. leprae IgA responses. Here, we investigated serum IgA reactivity against NDO-HSA, LID-1 and NDO-LID, in paucibacillary (PB) and multibacillary (MB) patients and their household contacts, using enzyme-linked immunosorbent assay (ELISA). Diagnostic accuracy of each ELISA was evaluated by receiver operating characteristic (ROC) curve analysis. Our data reveal elevated IgA serum levels against the three M. leprae specific antigens in MB patients, whereas IgA reactivity in PB patients was increased only to NDO-HSA. Further, MB and PB household contacts displayed higher IgA reactivity to NDO-HSA than non-endemic controls. Our data suggest measurement of serum IgA against NDO-HSA as an additional tool in the diagnosis and classification of the disease, with potential utility for household contact follow-up.

The Role of Lipid and the Benefit of Statin in Augmenting Rifampicin Effectivity for a Better Leprosy Treatment

Although leprosy remains as a serious disease of the skin and nervous system, the current treatment is still lacking in its effectiveness. This literature review will explore the association of lipid and leprosy, as well as the potential of statin and other lipid-lowering agents as adjunctive drugs to combat leprosy. Articles were searched through the PubMed, EBSCOhost, and Google Scholar with the keywords: immunomodulation, lipid-body, lipids, leprosy, Mycobacterium leprae, pathogenesis, rifampin or rifampicin, and statins. A manual searching is also carried out to find an additional relevant information to make this literature review more comprehensive. The literatures showed that lipids are highly correlated with leprosy through alterations in serum lipid profile, metabolism, pathogenesis, and producing oxidative stress. Statins can diminish lipid utilization in the pathogenesis of leprosy and show a mycobactericidal effect by increasing the effectiveness of rifampicin and recover the function of macrophages. In addition, Statins have anti-inflammatory properties which may aid in preventing type I and II reactions in leprosy. Standard multidrug therapy might reduce the efficacy of statins, but the effect is not clinically significant. The statin dose-response curve also allows therapeutic response to be achieved with minimal dose. The various pleiotropic effects of statins make it a potential adjunct to standard treatment for leprosy in the future.

High-risk transmission clusters of leprosy in an endemic area in the Northeastern Brazil: A retrospective spatiotemporal modelling (2001-2019)

OBJECTIVES

To analyse and map the leprosy risk areas in the state of Alagoas, an endemic region in the Northeastern Brazil, between 2001 and 2019.

METHODS

Ecological and time series study, using spatial analysis techniques. First, we analyse the epidemiological aspects of leprosy cases, using the data available in the Notifiable Diseases Information System; then, we used the segmented log-linear regression model to assess time trends. Spatial distribution was analysed by the Local Empirical Bayesian Estimator and by calculating the Global and Local Moran Index. Finally, spatiotemporal clusters were identified through scanning statistics, using the Kulldorf method of retrospective analysis.

RESULTS

We observed that Alagoas showed an average new case detection rate of 14.43/100,000 inhabitants between 2001 and 2019, being classified as highly endemic. The area of highest risk was the 9th health region (state hinterland), with increasing time trend (Annual Percentage Change/APC = 7.2; p-value < 0.05). Several clusters of high risk of leprosy transmission were verified in Alagoas, including the state capital and hinterland municipalities.

CONCLUSIONS

Our data indicate that active M. leprae transmission persists in Alagoas; that diagnosis is delayed and that there are high-risk areas, especially in inland municipalities.

Uveitic Glaucoma and Hansen's disease, A case report

Background

The number of Hansen's disease cases in Latin America and the Caribbean has decreased in the last decade; nevertheless, the region is still struggling with infections caused by Mycobacterium leprae. This is a case report that portrays the diagnostic and management challenges associated with atypical uveitic glaucoma that is due to Hansen's disease.

Case presentation

A 62-year-old female was referred with a 2-year history of anterior uveitis of unknown etiology and ocular hypertension. Past medical history and general physical examination were unremarkable. Upon ocular examination, her best-corrected visual acuity (BCVA) was 20/25 in the OD and 20/60 in the OS. Tonometry showed intraocular pressures (IOPs) of 29 mmHg and 22 mmHg in her right and left eyes, respectively. The slit-lamp examination showed clinical signs of bilateral granulomatous anterior uveitis and cataracts; gonioscopy revealed open angles with some peripheral anterior synechiae for both eyes. Fundus examination and glaucoma tests revealed mild glaucomatous damage in the right eye. Given the presentation of uveitis, the respective questionnaire was completed by internal medicine and rheumatology. Four months later, after bilateral cataract surgery, the patient developed skin plaques on the face, neck, upper back, and extremities, which were biopsied and identified as positive for tuberculoid leprosy.

Conclusion

This is the first case report in Ecuador of atypical glaucoma triggered by infectious uveitis produced by Mycobacterium leprae. We describe a female patient's clinical presentation with several ocular signs of leprosy and other nonspecific and rarely seen symptoms. Uveitis is a condition that often requires a multidisciplinary team of ophthalmologists and clinicians because of the possible manifestation of an underlying systemic disease, creating a challenge for all the medical personnel involved in the management of the case.

Hansen's disease in the era of COVID-19: An observation on a series of six patients with co-infection

Since the onset of the present pandemic, effect of the novel corona virus on other infectious conditions continues to be investigated. Although the immunological responses to SARS‐Cov‐2 infection have been elaborated extensively, they fail to explain, variations in its clinical manifestations and its interaction with other diseases. Hansen's disease is known to present as a complex immunological response to the lepra bacilli, resulting in its varied spectral manifestations. An interaction between these two infectious agents, hence, may affect Hansen's disease. We came across six cases of Hansen's disease who developed COVID19 co‐infection. This series presents their clinical course and outcome, during the period of co‐infection. All cases were followed up for a minimum eight‐week period thereafter. In all these cases the active phase of coronavirus infection had no effect on Hansen's disease and those on prednisolone for their lepra reaction had a more favorable outcome, with two cases manifesting exacerbation of their lepra reactions in the follow period.

CCL2 and IFN-γ serum levels as biomarkers for subclinical infection in household contacts of leprosy patients

Leprosy, also known as Hansen's disease, is a long-term infection by the bacteria Mycobacterium leprae, and actually still persists as a serious public health problem. The clinical parameters are used for diagnosis, however, some studies have indicated the selection of a set of biomarkers of subclinical infection, both serological and cellular, that allow the early diagnosis. Some cytokines and chemokines have been differentially expressed in index cases (paucibacillary and multibacillary patients) and household contacts (HHC), and may present a potential biomarker of M. leprae subclinical infection. Thus, the aim of this study was to analyze the variations in the profile of cytokines and chemokines, longitudinally, between index cases and their household contacts with a view to identifying possible biomarkers with differential expression, which may guide the early subclinical infection in household contacts. A longitudinal study was carried out between 2014 and 2015. The serum levels of the cytokines and chemokines were measured in all patient samples by CBA (Cytometric Bead Array). We observed a reduction of IL-4 and IL-17 expression of HHC group in the second evaluation (T1), as also a reduction of IL-17 in MB. We observed increased expression of IL-2 in PB patients as well. HHC, PB and MB showed a similar reduction profile of the chemokines CXCL8, CXCL9 and CXCL10 from T0 to T1. Interestingly, only serological levels of CCL2 are increased after a follow-up of HHC group, and this group, but not PB and MB patients, showed a significant association and a negative correlation between CCL2 and IFN-γ. The present study showed for the first time a similarity in the immunological scenario between HHC, PB and MB patients. In addition, this work highlights CCL2 chemokine in association with IFN-γ as possible biomarkers of subclinical infection of HHC, as also a parameter of early infection monitoring.

Neuropathies of leprosy

Neuropathies form an integral part of the symptomatology of leprosy. Neuropathies of leprosy take various forms and shapes. At one end is the cutaneous nerve involvement adjacent to the anaesthetic skin patch and the other is of symmetrical pansensory neuropathy and the devastating sensory ataxia of leprous ganglionits. Lepra reactions add to the spectrum. Hosts immunological status largely decides the clinical manifestations seen in nerves and skin. A wide array of diagnostic techniques like ultrasonography, magnetic resonance neurography, serological markers, molecular tests, skin biopsy and in selected cases, the nerve biopsy with special stains and electron microscopy are obtainable to help the clinical diagnosis. The unsuspecting clinician, lack of community awareness and limited availability of diagnostic tests are important adverse factors in the total outcome. Multi drug therapy is efficacious and corticosteroids reduce the impact of nerve damage in leprosy. The efficacy, dose and duration of corticosteroid therapy are presently inexact and other immune suppressants like azathioprine are being evaluated. Chronic disabilities and residual deficits require attention of multiple specialties. In the coming time, focus on prevention could lead to favourable results. This review will discuss the classification systems, common and uncommon clinical features, diagnostic armamentarium and therapeutic and preventive aspects of neuropathies of leprosy.

Higher Treg FoxP3 and TGF-β mRNA Expression in Type 2 Reaction ENL (Erythema Nodosum Leprosum) Patients in Mycobacterium leprae Infection

Background and Aim:

The pathology of leprosy is determined by the host immune response to Mycobacterium leprae. Almost 40% of patients with leprosy undergo immune-mediated inflammatory episodes such as type 1 reactions and Erythema Nodosum Leprosum (ENL or type 2 reactions). Regulatory T (Treg) is a subset of T cells that are involved in the immune response. Treg cells express Forkhead Box P3 (FoxP3), which plays a role in suppressing the immune response. FoxP3 may work alongside Transforming Growth Factor Beta (TGF-β) to down-regulate T cells responses, leading to the antigen-specific anergy associated with leprosy, whereas ENL occurrs mostly in multibacillary leprosy patients. Based on that, the aim of our study was to analyze Treg FoxP3 and TGF-β mRNA expression in type 2 reactions ENL with Mycobacterium leprae infection.

Methods:

Forty-nine newly diagnosed multibacillary (MB) leprosy patients attending the Dermatovenereology Clinic of Leprosy Subdivision, Sanglah General Hospital, Denpasar, Indonesia, were included in the study. The study group consists of 25 leprosy patients with ENL and 24 non-ENL leprosy patients. Twenty-five patients were included in the study as healthy controls. In this study, Treg FoxP3 and TGF-β mRNA expressions were identified with the Real-time PCR method. Analysis of Variant (ANOVA), Chi-square test and odds ratio (OR) calculation were used; p<0.05 was considered statistically significant.

Results:

The result of this study showed that the mean of Treg FoxP3 mRNA expression was 13.3 ± 2.9 on ENL leprosy patients, 11.6 ± 4.1 on non-ENL, and 9.3 ± 1.2 on healthy controls. The mean of TGF-β mRNA expression was 11.7 ± 2.7 on ENL leprosy patients, 9.5 ± 3.6 on non-ENL, and 9.3 ± 1.2 in healthy patients. Statistical analysis for Treg FoxP3 and TGF-β mRNA level between ENL, non-ENL patients and healthy control group showed significance at p<0.05.

Conclusion:

From this study, it was concluded that higher Treg FoxP3 and TGF-β mRNA expressions were found in type 2 reaction ENL patients with Mycobacterium leprae infection. The role played by Treg FoxP3 and TGF-β in type 2 reaction episodes can possibly provide a new target for the treatment of this still-challenging complication of leprosy. Further studies are required to determine the involvement of other cytokines in type 2 reaction ENL patients.

Functional Impairment of Skin Appendages Due to Peripheral Nerve Involvement by Mycobacterium leprae

In the earliest stage of Mycobacterium leprae infection, bacteria parasitize fine fiber twigs of autonomic peripheral nerves supplying efferent impulses to appendages of the skin. This obligate intracellular pathogen invades Schwann cells, the glial cells of peripheral nerves. Intracellular events inhibit Schwann cell physiology in complex ways, which include demyelination and dedifferentiation. Ultimately, axons embraced by their surrounding dysfunctional glia are damaged by poorly understood mechanisms. Loss of nerve conduction impairs the functions of skin appendages including hair growth, sebaceous gland secretion, sweating, and skin pigmentation. At the clinical level, these changes may be subtle and may precede the more obvious anesthetic skin lesions associated with Hansen’s disease. Recognizing the early signs of skin appendage malfunction may aid in diagnosis leading to initiation of antimycobacterial treatment. Effective therapy administered early during infection may prevent irreversible peripheral nerve destruction, the presage for morbid complications of leprosy.

Oct-6 transcriptional factor a possible biomarker for leprosy diagnosis

Leprosy is an infectious disease caused by Mycobacterium leprae that affects the skin and nerves. The nerve damage in leprosy may be related to alterations in transcriptional factors, such as Krox-20, Oct-6, Sox-10. Thirty skin biopsies in leprosy patients and 15 non-leprosy skin biopsies were evaluated using RT-qPCR to assess Krox-20, Oct-6, and Sox-10 and these data was related with S-100 immunohistochemistry. Changes in gene expression were observed in the skin and dermal nerves of leprosy patients in Oct-6 and Sox-10. When comparing Oct-6 with S-100 IHC as diagnostic tests for leprosy, Oct-6 showed a sensitivity of 73.3%, and specificity of 100%, while S-100 IHC showed a sensitivity of 96.6% and specificity of 100%. Our data suggest Oct-6 could be an auxiliary biomarker specific to detecting changes in dermal nerves in leprosy and thus useful to health workers and pathologists with no expertise to observe nerve injuries in leprosy.

Macrophage Polarization in Leprosy-HIV Co-infected Patients

In HIV-infected individuals, a paradoxical clinical deterioration may occur in preexisting leprosy when highly active antiretroviral therapy (HAART)-associated reversal reaction (RR) develops. Leprosy–HIV co-infected patients during HAART may present a more severe form of the disease (RR/HIV), but the immune mechanisms related to the pathogenesis of leprosy–HIV co-infection remain unknown. Although the adaptive immune responses have been extensively studied in leprosy–HIV co-infected individuals, recent studies have described that innate immune cells may drive the overall immune responses to mycobacterial antigens. Monocytes are critical to the innate immune system and play an important role in several inflammatory conditions associated with chronic infections. In leprosy, different tissue macrophage phenotypes have been associated with the different clinical forms of the disease, but it is not clear how HIV infection modulates the phenotype of innate immune cells (monocytes or macrophages) during leprosy. In the present study, we investigated the phenotype of monocytes and macrophages in leprosy–HIV co-infected individuals, with or without RR. We did not observe differences between the monocyte profiles in the studied groups; however, analysis of gene expression within the skin lesion cells revealed that the RR/HIV group presents a higher expression of macrophage scavenger receptor 1 (MRS1), CD209 molecule (CD209), vascular endothelial growth factor (VEGF), arginase 2 (ARG2), and peroxisome proliferator-activated receptor gamma (PPARG) when compared with the RR group. Our data suggest that different phenotypes of tissue macrophages found in the skin from RR and RR/HIV patients could differentially contribute to the progression of leprosy.

Leprosy surveillance study in a highly endemic Brazilian area using leprosy specific serologic tests and IFNγ whole blood assay

This surveillance study evaluated leprosy-serologic tests and the IFNγ whole-blood-assay/WBA as adjunct diagnostic tools. Previously diagnosed leprosy index cases, intradomiciliary, peridomiciliary contacts from a Brazilian endemic area were enrolled during domiciliary visits. Physical evaluation was performed by trained nurses and leprosy diagnosis confirmed by expert dermatologist. ELISA detected IgM anti-PGL-I, IgG anti-LID-1, and IgM/IgG anti-ND-O-LID antibodies. Heparinized WBA plasma stimulated with LID-1, 46f + LID-1, ML0276 + LID-1 (24 h, 37 °C, 5% CO₂₎ was tested for human IFNγ (QuantiFERON®-TB Gold/QFT-G; Qiagen). The survey included 1731 participants: 44 leprosy index cases, 64 intradomiciliary, 1623 peridomiciliary contacts. Women represented 57.7%, median age was 32 years, 72.2% had BCG scar. Leprosy prevalence was higher in intradomiciliary (8.57%) versus peridomiciliary contacts (0.67%), p < 0.001. Among 23 suspects, five leprosy cases were confirmed: 4 multibacillary/MB and 1 paucibacillary/PB. Leprosy incidence was 0.30%: 1.56% in intradomiciliary versus 0.25% in peridomiciliary (p = 0.028). Seropositivity rates were 1.9% to PGL-I, 4.9% to LID-1, and 1.0% to ND-O-LID. LID-1 positivity was higher in all groups; incident cases were LID-1 seropositive. ND-O-LID positivity was higher in intra- versus peridomiciliary contacts (p = 0.022). IFNγ WBA (40 index cases, 19 suspects, 35 intradomiciliary, 74 peridomiciliary contacts) showed higher LID-1/WBA positivity in peridomiciliary contacts (p > 0.05); significant differences among groups were seen with 46f + LID-1 but 0276 + LID-1 induced higher IFNγ levels. Incident cases were LID-1 seropositive, while IFNγ-WBA had marginal diagnostic application. As seropositivity indicates exposed individuals at higher risk of disease development, the utility of serologic screening for surveillance and prophylactic measures remains to be demonstrated.

The immunology of other mycobacteria: M. ulcerans, M. leprae

Mycobacterial pathogens can be categorized into three broad groups: Mycobacterium tuberculosis complex causing tuberculosis, M. leprae and M. lepromatosis causing leprosy, and atypical mycobacteria, or non-tuberculous mycobacteria (NTM), responsible for a wide range of diseases. Among the NTMs, M. ulcerans is responsible for the neglected tropical skin disease Buruli ulcer (BU). Most pathogenic mycobacteria, including M. leprae, evade effector mechanisms of the humoral immune system by hiding and replicating inside host cells and are furthermore excellent modulators of host immune responses. In contrast, M. ulcerans replicates predominantly extracellularly, sheltered from host immune responses through the cytotoxic and immunosuppressive effects of mycolactone, a macrolide produced by the bacteria. In the year 2018, 208,613 new cases of leprosy and 2713 new cases of BU were reported to WHO, figures which are notoriously skewed by vast underreporting of these diseases.

Leprosy: Clinical aspects and diagnostic techniques

Leprosy, also known as Hansen's disease, is a curable infectious disease that remains endemic in >140 countries around the world. Despite being declared "eliminated" as a global public health problem by the World Health Organization in the year 2000, approximately 200,000 new cases were reported worldwide in 2017. Widespread migration may bring leprosy to nonendemic areas, such as North America. In addition, there are areas in the United States where autochthonous (person-to-person) transmission of leprosy is being reported among Americans without a history of foreign exposure. In the first article in this continuing medical education series, we review leprosy epidemiology, transmission, classification, clinical features, and diagnostic challenges.