The red flags of ulnar neuropathy in leprosy

The diagnosis of pure neural leprosy is more challenging because patients share characteristics with other common pathologies, such as ulnar compression, which should be taken into consideration for differential diagnosis. In this study, we identify ulnar nerve conduction characteristics to aid in the differential diagnosis of ulnar neuropathy (UN) in leprosy and that of non-leprosy etiology. In addition, we include putative markers to better understand the inflammatory process that may occur in the nerve. Data were extracted from a database of people affected by leprosy (leprosy group) diagnosed with UN at leprosy diagnosis. A non-leprosy group of patients diagnosed with mechanical neuropathy (compressive, traumatic) was also included. Both groups were submitted to clinical, neurological, neurophysiological and immunological studies. Nerve enlargement and sensory impairment were significantly higher in leprosy patients than in patients with compressive UN. Bilateral impairment was significantly higher in the leprosy group than in the non-leprosy group. Leprosy reactions were associated to focal demyelinating lesions at the elbow and to temporal dispersion (TD). Clinical signs such as sensory impairment, nerve enlargement and bilateral ulnar nerve injury associated with eletrodiagnostic criteria such as demyelinating finds, specifically temporal dispersion, could be tools to help us decided on the best conduct in patients with elbow ulnar neuropathy and specifically decide if we should perform a nerve biopsy for diagnosis of pure neural leprosy.

The function of peroxisome proliferator-activated receptors PPAR-γ and PPAR-δ in Mycobacterium leprae-induced foam cell formation in host macrophages

Leprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae). In lepromatous leprosy (LL), skin macrophages, harboring extensive bacterial multiplication, gain a distinctive foamy appearance due to increased intracellular lipid load. To determine the mechanism by which M. leprae modifies the lipid homeostasis in host cells, an in vitro M. leprae infection system, using human macrophage precursor THP-1 cells and M. leprae prepared from the footpads of nude mice, was employed. RNA extracted from skin smear samples of patients was used to investigate host gene expressions before and after multidrug therapy (MDT). We found that a cluster of peroxisome proliferator-activated receptor (PPAR) target genes associated with adipocyte differentiation were strongly induced in M. leprae-infected THP-1 cells, with increased intracellular lipid accumulation. PPAR-δ and PPAR-γ expressions were induced by M. leprae infection in a bacterial load-dependent manner, and their proteins underwent nuclear translocalization after infection, indicating activation of PPAR signaling in host cells. Either PPAR-δ or PPAR-γ antagonist abolished the effect of M. leprae to modify host gene expressions and inhibited intracellular lipid accumulation in host cells. M. leprae-specific gene expressions were detected in the skin smear samples both before and after MDT, whereas PPAR target gene expressions were dramatically diminished after MDT. These results suggest that M. leprae infection activates host PPAR signaling to induce an array of adipocyte differentiation-associated genes, leading to accumulation of intracellular lipids to accommodate M. leprae parasitization. Certain PPAR target genes in skin lesions may serve as biomarkers for monitoring treatment efficacy.

Leprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae). Lipid-enriched intracellular environment is important for the parasitization of M. leprae. During anti-leprosy treatment, chemotherapy-killed bacilli can remain in host tissues for a long time, making it difficult to determine the treatment efficacy by Zeihl-Nelson’s staining-based bacterial index (BI) test. In this study, we found that host peroxisome proliferator-activated receptor (PPAR) signaling is responsible for modification of intracellular lipid homeostasis to accommodate M. leprae parasitization in host macrophages. In skin smear samples of patients, M. leprae-derived gene expressions were detected both before and after anti-leprosy treatment, whereas human PPAR target gene expressions were dramatically diminished after the treatment. These results further our understanding of M. leprae intracellular parasitization, and suggest that PPAR signaling may be a novel therapeutic target for treating M. leprae infection and monitoring the expressions of certain PPAR target genes in skin lesions may be helpful to evaluate the treatment efficacy and recurrent infection.

Identification of a systemic interferon-γ inducible antimicrobial gene signature in leprosy patients undergoing reversal reaction

Reversal reactions (RRs) in leprosy are characterized by a reduction in the number of bacilli in lesions associated with an increase in cell-mediated immunity against the intracellular bacterium Mycobacterium leprae, the causative pathogen of leprosy. To identify the mechanisms that contribute to cell-mediated immunity in leprosy, we measured changes in the whole blood-derived transcriptome of patients with leprosy before, during and after RR. We identified an ‘RR signature’ of 1017 genes that were upregulated at the time of the clinical diagnosis of RR. Using weighted gene correlated network analysis (WGCNA), we detected a module of 794 genes, bisque4, that was significantly correlated with RR, of which 434 genes were part of the RR signature. An enrichment for both IFN-γ and IFN-β downstream gene pathways was present in the RR signature as well as the RR upregulated genes in the bisque4 module, including those encoding proteins of the guanylate binding protein (GBP) family that contributes to antimicrobial responses against mycobacteria. Specifically, GBP1, GBP2, GBP3 and GBP5 mRNAs were upregulated in the RR peripheral blood transcriptome, with GBP1, GBP2 and GBP5 mRNAs also upregulated in the RR disease lesion transcriptome. These data indicate that RRs involve a systemic upregulation of IFN-γ downstream genes including GBP family members as part of the host antimicrobial response against mycobacteria.

Reversal reaction (RR) is a major cause of tissue injury and disabilities in leprosy, resulting from the rapid onset of cell-mediated immune responses to the intracellular bacterium Mycobacterium leprae. To identify the mechanisms related to the increase in cell-mediated immunity in RR, we measured changes in the whole blood-derived transcriptome of patients with leprosy before, during and after RR. We identified that RRs are associated with an IFN-γ induced inflammatory response including an antimicrobial gene network containing the GBP1, GBP2, GBP3 and GBP5 mRNAs in the peripheral blood. Furthermore, we show that GBP1, GBP2 and GBP5 mRNAs are also upregulated at the site of disease in RR patients. In summary, our study suggests that RR involves a systemic induction of IFN-γ regulated genes that contributes to an antimicrobial response against the pathogen, releasing ligands and antigens that can further amplify the inflammatory response.

Myelination key factor krox-20 is downregulated in Schwann cells and murine sciatic nerves infected by Mycobacterium leprae

Schwann cells (SCs) critically maintain the plasticity of the peripheral nervous system. Peripheral nerve injuries and infections stimulate SCs in order to retrieve homeostasis in neural tissues. Previous studies indicate that Mycobacterium leprae (ML) regulates the expression of key factors related to SC identity, suggesting that alterations in cell phenotype may be involved in the pathogenesis of neural damage in leprosy. To better understand whether ML restricts the plasticity of peripheral nerves, the present study sought to determine the expression of Krox-20, Sox-10, c-Jun and p75NTR in SC culture and mice sciatic nerves, both infected by ML Thai-53 strain. Primary SC cultures were stimulated with two different multiplicities of infection (MOI 100:1; MOI 50:1) and assessed after 7 and 14 days. Sciatic nerves of nude mice (NU-Foxn1nu ) infected with ML were evaluated after 6 and 9 months. In vitro results demonstrate downregulation of Krox-20 and Sox-10 along with the increase in p75NTR-immunolabelled cells. Concurrently, sciatic nerves of infected mice showed a significant decrease in Krox-20 and increase in p75NTR. Our results corroborate previous findings on the interference of ML in the expression of factors involved in cell maturation, favouring the maintenance of a non-myelinating phenotype in SCs, with possible implications for the repair of adult peripheral nerves.

PGL I expression in live bacteria allows activation of a CD206/PPARγ cross-talk that may contribute to successful Mycobacterium leprae colonization of peripheral nerves

Mycobacterium leprae, an obligate intracellular bacillus, infects Schwann cells (SCs), leading to peripheral nerve damage, the most severe leprosy symptom. In the present study, we revisited the involvement of phenolic glycolipid I (PGL I), an abundant, private, surface M. leprae molecule, in M. leprae-SC interaction by using a recombinant strain of M. bovis BCG engineered to express this glycolipid. We demonstrate that PGL I is essential for bacterial adhesion and SC internalization. We also show that live mycobacterium-producing PGL I induces the expression of the endocytic mannose receptor (MR/CD206) in infected cells in a peroxisome proliferator-activated receptor gamma (PPARγ)-dependent manner. Of note, blocking mannose recognition decreased bacterial entry and survival, pointing to a role for this alternative recognition pathway in bacterial pathogenesis in the nerve. Moreover, an active crosstalk between CD206 and the nuclear receptor PPARγ was detected that led to the induction of lipid droplets (LDs) formation and prostaglandin E2 (PGE2), previously described as fundamental players in bacterial pathogenesis. Finally, this pathway was shown to induce IL-8 secretion. Altogether, our study provides evidence that the entry of live M. leprae through PGL I recognition modulates the SC phenotype, favoring intracellular bacterial persistence with the concomitant secretion of inflammatory mediators that may ultimately be involved in neuroinflammation.

Nerve damage is the most severe symptom of leprosy, an ancient disease that continues to be a major health problem in several countries. Nerve damage is due to the ability of Mycobacterium leprae, the etiologic agent, to invade SCs, the glial cells of the peripheral nervous system. Understanding the molecular basis of M. leprae–SC interaction is essential for the creation of new tools aiming to treat and, above all, prevent leprosy neuropathy. This study demonstrates the critical role of PGL I, an M. leprae-abundant specific cell wall lipid, in establishing infection. PGL I is not only a prerequisite in initiating bacterial adhesion to and subsequent invasion of SCs, but also for changing the repertoire of cell surface proteins to allow for the entrance of bacteria via alternative pathways. These new invasive pathways induced by PGL I involve recognition of other bacterial cell surface glycolipids that, in turn, evoke functional changes in the infected cell, including the accumulation of host cell-derived lipids, which favor bacterial survival. These pathways also promote the secretion of inflammatory mediators that may contribute to nerve damage. In an era of translational-oriented research, exploring these receptors in depth could lead to the development of attractive strategies to ensure the targeted intracellular delivery of therapeutics aiming to prevent neuropathy.

Response of iNOS and its relationship with IL-22 and STAT3 in macrophage activity in the polar forms of leprosy

Leprosy is a chronic granulomatous infection that manifests as different clinical forms related to the immunological response. The aim of the study was to evaluated the response of IL-22, STAT3, CD68 and iNOS in leprosy skin lesions. The mean number IL-22 positive cells was 12.12±1.90cells/field in the TT form and 31.31±2.91cells/field in the LL form. STAT3 positive cells was 5.29±1.96 cells/field in the TT form, while this number was 11.13±3.48cells/field in the LL form. The mean number of CD68 positive cells was 25.18±6.21cells/field in the TT form and 62.81±8.13cells/field in the LL form. Quantitative analysis of iNOS revealed a significant difference, with the mean number of cells expressing the enzyme being 30.24±2.88cells/field in the TT form compared to 35.44±4.69cells/field in the LL form. Linear correlations in lesions of TT patients showed a moderate positive correlations between CD68 and iNOS, STAT3 and Inos, IL-22 and STAT3, and IL-22 and iNOS. Our results demonstrate that these factors can act synergistically to induce a microbicidal activity in the population of macrophages in the leprosy lesions.

Correlation between therapy and lipid profile of leprosy patients: is there a higher risk for developing cardiovascular diseases after treatment?

BACKGROUND

The impact of leprosy reduces health-related quality of life of affected patients, interfering with different factors such as nutrition. This study investigated the lipid profile, nutritional status, and risk for cardiovascular disease (CVD) in patients who underwent leprosy treatment in Brazil.

METHODS

Eighty-four adult patients of both genders ranging in age from 20 to 60 years and diagnosed with paucibacillary (PB) or multibacillary (MB) leprosy were selected after undergoing multidrug treatment. The following data were collected: sociodemographic and clinical data; food intake; anthropometric measures (weight, height, and waist circumference); and lipid profile components (total cholesterol, high-density lipoprotein cholesterol [HDL-c], low-density lipoprotein cholesterol [LDL-c], and triglycerides).

RESULTS

Among the study population, there was a predominance of males (65.48%) aged 50 to 60 years, patients with an income of 248-496 American dollars (63.10%), patients who completed elementary school (65.48%), inactive patients (76.19%), non-smokers (46.43%), and non-drinking patients (69.05%). The levels (mean ± standard deviation) of total cholesterol were 193.8 ± 29.4 mg/dL in the PB form and 203.5 ± 41.7 mg/dL in the MB form. The mean LDL-c was 116.9 ± 22.7 mg/dL in PB patients and 121 ± 31.3 mg/dL in MB patients. Mean triglyceride levels were 123.4 ± 45.2 mg/dL in the PB form and 147.4 ± 88.9 mg/dL in the MB form. The evaluation of nutritional status showed that 41.67% of the patients were eutrophic, while 55.96% had excess weight. Food intake was significantly associated with HDL-c in male patients (P = 0.0264) and with triglycerides in patients above the ideal weight (P = 0.0049).

CONCLUSIONS

The risk of acquiring CVDs was observed to be high due to patients' excess weight and increased waist circumference. This study will guide clinicians in the adequate treatment of patients with leprosy in order to avoid adverse cardiovascular events.

Role of TEFFECTOR/MEMORY Cells, TBX21 Gene Expression and T-Cell Homing Receptor on Type 1 Reaction in Borderline Lepromatous Leprosy Patients

In spite of hyporesponsivity to Mycobacterium leprae, borderline lepromatous (BL) patients show clinical and immunological instability, and undergo frequent acute inflammatory episodes such as type 1 reaction (T1R), which may cause nerve damages. This work focused on the participation of T cell subsets from blood and skin at T1R onset. We observed a significantly increased ex vivo frequency of both effector and memory CD4+ and CD8+ T cells in T1R group. Besides, ex vivo frequency of T cell homing receptor, the Cutaneous Leukocyte-associated Antigen (CLA) was significantly increased in T cells from T1R patients. M. leprae induced a higher frequency of CD4+ T_EM and CD8+ T_EF cells, as well as of CD8+/TEMRA (terminally differentiated effector T cells) subset, which expressed high CD69+. The presence of IFN-γ‒producing-CD4+ T_EF and naïve and effector CD8+ T lymphocytes was significant in T1R. TBX21 expression was significantly higher in T1R, while BL showed increased GATA3 and FOXP3 expression. In T1R, TBX21 expression was strongly correlated with CD8+/IFN-γ‒ T cells frequency. The number of double positive CD8+/CLA+ and CD45RA+/CLA+ cells was significantly higher in skin lesions from T1R, in comparison with non-reactional BL group. The observed increase of ex vivo T cells at T1R onset suggests intravascular activation at the beginning of reactional episodes. The antigen-specific response in T1R group confirmed the higher number of CD8+/CLA+ and CD45RA+/CLA+ cells in T1R lesions suggests possible migration of these cells activated by M. leprae components inside the vascular compartment to skin and participation in T1R physiopathology.

[EXPERIMENTAL STUDY OF SPECIFIC ACTIVITY OF 1.3-DIAZINON-4 COM- POUND PYaTd1 DERIVATIVE IN VIVO]

AIM

Study anti-leprosy activity of.a 1.3-diazinon-4 compound derivative under the labora- tory code PYaTd1 on the model of intra-plantar infection of mice and evaluate the character of its antibacterial effect.

MATERIALS AND METHODS

Study of specific activity was carried out in vivo on the experimental model of leprosy, proposed by Shepard C.C., that assumes execution of intraplantar infection of mice with a suspension of mycobacteria, produced from lepromas or autopsy tissue of a non-treated leprosy infected, or from tissues of experimental mice, previously infected with Mycobacterium leprae from non-treated patients. The study was carried out on 120 CBA line-mice infected with M.leprae (VIII passage) from patient M; Dapsone and PYaTdl compound were administered to animals next day after the infection with forage at a dose of 25 mg/kg for 4.5, 6, 9 and 11 months. The mice were split into 3 groups: control (infected.without treatment), com- parison (infected, receiving.dapsone), experimental (infected, receiving PYaTdl). After.the control term the mice were euthanized under chloroform anesthesia. Suspensions for quantification of mycobacteria were prepared from paw pads. Smears were stained by Ziehl-Nilsson.

RESULTS

After 4.5 months the intensity of infect reproduction under, the effect of dapsone and PYaTd1 was reduced compared with control by 18 - 25 times. After a 6-mont course - by 50 - 75% and after 9 months - by 85 - 90%. After 11 months in mice that had received PYaTd1, an intensive suppression of microorganism reproduction as observed: the yield in paws was 70 times lower than in control. In the group that had received dapsone, a reduction of the number of mycobacteria by 20 - 25 times was detected, it was significantly less effective than under the conditions of PYaTd1 admnistration.

CONCLUSION

A novel 1.3-diazinon- 4 derivative under the code PYaTd1 can actively supress reproduction of-M. leprae, that gives evidence regarding its specific anti-mycobacterial activity and determines perspectives of its further studies.

Evaluation of Myelin Sheath Marker Krox-20 for Detection of Early Disability in Leprosy

Early diagnosis of nerve damage in leprosy is quite important for preventing the deformities. With an aim to find a good marker we have investigated Krox-20 as early peripheral nerve damage indicator in leprosy. Ambulatory patients of Kediri Leprosy Hospital, Malang, Indonesia have been studied. Degree of disability was measured based on WHO's criteria. Immunohistochemistry was.used to study the expression of Krox-20 on Schwann cells on nerve twigs in skin biopsies from leprosy cases. Receiver Operating Characteristic (ROC) curve was used to determine cut off value. Of all 79 leprosy patients studied, 36 patiens had degree of disability 0, and 43 patients had degree of disability 1. Analysis of ROC curve shown that cut off value for Krox- 20, was 8 and the cases in whom degree of disability was 0 (zero) had significantly higher mean values than those with degree of disability 1 (mean: 12.56 vs 4.24 (p<0.05)). Krox-20 appears to be a potentially good biomarker to identify early peripheral nerve damage in leprosy.

Is CXCL10/CXCR3 axis overexpression a better indicator of leprosy type 1 reaction than inducible nitric oxide synthase?

BACKGROUND & OBJECTIVES

Leprosy type 1 reactions (T1R) are acute episodes of immune exacerbation that are a major cause of inflammation and nerve damage. T1R are diagnosed clinically and supported by histopathology. No laboratory marker is currently available that can accurately predict a T1R. Increased plasma and tissue expression of inducible nitric oxide synthase (i-NOS) and chemokine CXCL10 have been demonstrated in T1R. We studied the gene expression and immunoexpression of i-NOS, CXCL10 and its receptor CXCR3 in clinically and histopathologically confirmed patients with T1R and compared with non-reactional leprosy patients to understand which biomarker has better potential in distinguishing reaction from non-reaction.

METHODS

Gene expression of i-NOS, CXCL10 and CXCR3 was studied in 30 skin biopsies obtained from patients with borderline tuberculoid (BT), mid-borderline (BB) and borderline lepromatous (BL) leprosy with and without T1R by real-time PCR. Further validation was done by immunohistochemical expression on 60 borderline leprosy biopsies with and without T1R.

RESULTS

Of the 120 patients histopathological evaluation confirmed T1R in 65 (54.2%) patients. CXCR3 gene expression was significantly (P<0.05) higher in BT- and BB-T1R patients compared to those without T1R. The CXCL10 gene expression was significantly higher (P<0.05) in BB leprosy with T1R but the difference was not significant in patients with BT with or without T1R. Immunoexpression for CXCR3 was significant in both BB-T1R and BB (P<0.001) and BT and BT-T1R (P<0.001). Immunoexpression of CXL10 was significant only in differentiating BB from BB-T1R leprosy (P<0.01) and not the BT cases. i-NOS immunoexpression was not useful in differentiating reactional from non-reactional leprosy.

INTERPRETATION & CONCLUSIONS

Both CXCL10 and CXCR3 appeared to be useful in differentiating T1R reaction in borderline leprosy while CXCR3 alone differentiated BT from BT-T1R. CXCR3 may be a potentially useful immunohistochemical marker to predict an impending T1R.

M. leprae components induce nerve damage by complement activation: identification of lipoarabinomannan as the dominant complement activator

Peripheral nerve damage is the hallmark of leprosy pathology but its etiology is unclear. We previously identified the membrane attack complex (MAC) of the complement system as a key determinant of post-traumatic nerve damage and demonstrated that its inhibition is neuroprotective. Here, we determined the contribution of the MAC to nerve damage caused by Mycobacterium leprae and its components in mouse. Furthermore, we studied the association between MAC and the key M. leprae component lipoarabinomannan (LAM) in nerve biopsies of leprosy patients. Intraneural injections of M. leprae sonicate induced MAC deposition and pathological changes in the mouse nerve, whereas MAC inhibition preserved myelin and axons. Complement activation occurred mainly via the lectin pathway and the principal activator was LAM. In leprosy nerves, the extent of LAM and MAC immunoreactivity was robust and significantly higher in multibacillary compared to paucibacillary donors (p = 0.01 and p = 0.001, respectively), with a highly significant association between LAM and MAC in the diseased samples (r = 0.9601, p = 0.0001). Further, MAC co-localized with LAM on axons, pointing to a role for this M. leprae antigen in complement activation and nerve damage in leprosy. Our findings demonstrate that MAC contributes to nerve damage in a model of M. leprae-induced nerve injury and its inhibition is neuroprotective. In addition, our data identified LAM as the key pathogen associated molecule that activates complement and causes nerve damage. Taken together our data imply an important role of complement in nerve damage in leprosy and may inform the development of novel therapeutics for patients.

Profile of oxidative stress in response to treatment for type 1 leprosy reaction

OBJECTIVE

To measure oxidative stress in Type 1 leprosy reaction, and to document the effect of anti-leprosy multidrug therapy (MDT) and anti-reaction drugs on measures of oxidative stress.

MATERIALS AND METHODS

A prospective study was carried out at a teaching hospital involving consecutive patients with Type 1 reaction. MDA (malondialdehyde), FRAP (ferric reducing ability of plasma) and GSH (reduced glutathione) were measured in venous blood samples as measures of oxidative stress and compared at inclusion, after 4 weeks of initial therapy (following standard guidelines including MDT, NSAIDS, and systemic steroids), and 4 weeks after clinical remission.

RESULTS

The final study cohort included 40 patients with Type 1 reaction (different treatment arms) after excluding for confounding factors such as prior treatment, smoking, NSAID use or concurrent illness requiring therapy. Measures of lipid derived oxidative stress assessed by MDA showed a significant rise with 4 weeks of therapy and a trend towards decline after clinical resolution. In contrast, the other two measures of anti-oxidants namely GSH and FRAP, showed a significant decrease (P < 0.05) at 4 weeks of treatment followed by a significant increase after 4 weeks of clinical remission of reaction.

CONCLUSION

MDT and anti-reactional treatment is associated with significant increases in FRAP and GSH levels, reflecting a reduction in the oxidative stress in patients treated for Type 1 reaction. However, lipid peroxidation as measured by MDA is only partially controlled with treatment.

Saliva as a Diagnostic Tool for Measurement of Total Antioxidant Capacity in Children with Leprosy and Born to Leprosy Parent

The aim of the study is to assess the role of saliva as a diagnostic tool for measurement of total antioxidant capacity in children with leprosy and children born to leprosy parent. One hundred fifty children in the age group of 4-15 years were split into three equal groups: children with leprosy (CL) and children born to leprotic parents (CLP) and healthy children. Vitamin C level was measured in saliva of children spectrophotometrically at 695nm by Phosphomolybdenum method. Data were determined with student's unpaired t test and one way ANOVA. The result of the study showed that children with leprosy exhibited significantly decreased salivary total antioxidant capacity as compared to healthy controls. Antioxidant Vitamin C was higher in the Paucibacillary leprosy (PB) than those of Multibacillary type (MB) (P < 0.001). As age advanced, there was a gradual increase in total antioxidant capacity in both the control and study groups and the results were highly significant statistically. Saliva is an easy medium.

Leprosy association with low MASP-2 levels generated by MASP2 haplotypes and polymorphisms flanking MAp19 exon 5

Background

The gene MASP2 (mannan-binding lectin (MBL)-associated serine protease 2) encodes two proteins, MASP-2 and MAp19 (MBL-associated protein of 19 kDa), bound in plasma to MBL and ficolins. The binding of MBL/MASP-2 and ficolin/MASP-2 complexes to microorganisms activates the lectin pathway of complement and may increase the ingestion of intracellular pathogens such as Mycobacterium leprae.

Methods

We haplotyped 11 MASP2 polymorphisms with multiplex sequence-specific PCR in 219 Brazilian leprosy patients (131 lepromatous, 29 borderline, 21 tuberculoid, 14 undetermined, 24 unspecified), 405 healthy Brazilians and 291 Danish blood donors with previously determined MASP-2 and MAp19 levels. We also evaluated MASP-2 levels in further 46 leprosy patients and 69 Brazilian controls.

Results

Two polymorphisms flanking exon 5 of MASP2 were associated with a dominant effect on high MASP-2 levels and an additive effect on low MAp19 levels. Patients presented lower MASP-2 levels (P = 0.0012) than controls. The frequency of the p.126L variant, associated with low MASP-2 levels (below 200 ng/mL), was higher in the patients (P = 0.0002, OR = 4.92), as was the frequency of genotypes with p.126L (P = 0.00006, OR = 5.96). The *1C2-l [AG] haplotype, which harbors p.126L and the deficiency-causing p.439H variant, has a dominant effect on the susceptibility to the disease (P = 0.007, OR = 4.15). Genotypes composed of the *2B1-i and/or *2B2A-i haplotypes, both associated with intermediate MASP-2 levels (200–600 ng/mL), were found to be protective against the disease (P = 0.0014, OR = 0.6). Low MASP-2 levels (P = 0.022), as well as corresponding genotypes with *1C2-l and/or *2A2-l but without *1B1-h or *1B2-h, were more frequent in the lepromatous than in other patients (P = 0.008, OR = 8.8).

Conclusions

In contrast with MBL, low MASP-2 levels increase the susceptibility to leprosy in general and to lepromatous leprosy in particular. MASP2 genotypes and MASP-2 levels might thus be of prognostic value for leprosy progression.

Gene expression profiling specifies chemokine, mitochondrial and lipid metabolism signatures in leprosy

Herein, we performed microarray experiments in Schwann cells infected with live M. leprae and identified novel differentially expressed genes (DEG) in M. leprae infected cells. Also, we selected candidate genes associated or implicated with leprosy in genetic studies and biological experiments. Forty-seven genes were selected for validation in two independent types of samples by multiplex qPCR. First, an in vitro model using THP-1 cells was infected with live Mycobacterium leprae and M. bovis bacillus Calmette-Guérin (BCG). In a second situation, mRNA obtained from nerve biopsies from patients with leprosy or other peripheral neuropathies was tested. We detected DEGs that discriminate M. bovis BCG from M. leprae infection. Specific signatures of susceptible responses after M. leprae infection when compared to BCG lead to repression of genes, including CCL2, CCL3, IL8 and SOD2. The same 47-gene set was screened in nerve biopsies, which corroborated the down-regulation of CCL2 and CCL3 in leprosy, but also evidenced the down-regulation of genes involved in mitochondrial metabolism, and the up-regulation of genes involved in lipid metabolism and ubiquitination. Finally, a gene expression signature from DEG was identified in patients confirmed of having leprosy. A classification tree was able to ascertain 80% of the cases as leprosy or non-leprous peripheral neuropathy based on the expression of only LDLR and CCL4. A general immune and mitochondrial hypo-responsive state occurs in response to M. leprae infection. Also, the most important genes and pathways have been highlighted providing new tools for early diagnosis and treatment of leprosy.

Deciphering the function of leucine-rich repeat kinase 2 and targeting its dysfunction in disease

LRRK2 (leucine-rich repeat kinase 2) is a gene of unknown function that has been linked to a number a human diseases, including PD (Parkinson's disease), IBD (inflammatory bowel disease), leprosy and cancer. The papers from the LRRK2: Function and Dysfunction meeting in this issue of Biochemical Society Transactions explore our growing knowledge of LRRK2's normal function, the role that it plays in disease and emerging strategies to exploit LRRK2 as a therapeutic target.

Isolation of a distinct Mycobacterium tuberculosis mannose-capped lipoarabinomannan isoform responsible for recognition by CD1b-restricted T cells

Mannose-capped lipoarabinomannan (ManLAM) is a complex lipoglycan abundantly present in the Mycobacterium tuberculosis cell envelope. Many biological properties have been ascribed to ManLAM, from directly interacting with the host and participating in the intracellular survival of M. tuberculosis, to triggering innate and adaptive immune responses, including the activation of CD1b-restricted T cells. Due to its structural complexity, ManLAM is considered a heterogeneous population of molecules which may explain its different biological properties. The presence of various modifications such as fatty acids, succinates, lactates, phosphoinositides and methylthioxylose in ManLAM have proven to correlate directly with its biological activity and may potentially be involved in the interactions between CD1b and the T cell population. To further delineate the specific ManLAM epitopes involved in CD1b-restricted T cell recognition, and their potential roles in mediating immune responses in M. tuberculosis infection, we established a method to resolve ManLAM into eight different isoforms based on their different isoelectric values. Our results show that a ManLAM isoform with an isoelectric value of 5.8 was the most potent in stimulating the production of interferon-γ in different CD1b-restricted T-cell lines. Compositional analyses of these isoforms of ManLAM revealed a direct relationship between the overall charge of the ManLAM molecule and its capacity to be presented to T cells via the CD1 compartment.

Cytokine and protein markers of leprosy reactions in skin and nerves: baseline results for the North Indian INFIR cohort

Background

Previous studies investigating the role of cytokines in the pathogenesis of leprosy have either been on only small numbers of patients or have not combined clinical and histological data. The INFIR Cohort study is a prospective study of 303 new multibacillary leprosy patients to identify risk factors for reaction and nerve damage. This study characterised the cellular infiltrate in skin and nerve biopsies using light microscopic and immunohistochemical techniques to identify any association of cytokine markers, nerve and cell markers with leprosy reactions.

Methodology/Principal Findings

TNF-α, TGF-β and iNOS protein in skin and nerve biopsies were detected using monoclonal antibody detection immunohistochemistry techniques in 299 skin biopsies and 68 nerve biopsies taken from patients at recruitment. The tissues were stained with hematoxylin and eosin, modified Fite Faraco, CD68 macrophage cell marker and S100.

Conclusions/Significance

Histological analysis of the biopsies showed that 43% had borderline tuberculoid (BT) leprosy, 27% borderline lepromatous leprosy, 9% lepromatous leprosy, 13% indeterminate leprosy types and 7% had no inflammation. Forty-six percent had histological evidence of a Type 1 Reaction (T1R) and 10% of Erythema Nodosum Leprosum. TNF-α was detected in 78% of skin biopsies (181/232), iNOS in 78% and TGF-β in 94%. All three molecules were detected at higher levels in patients with BT leprosy. TNF-α was localised within macrophages and epithelioid cells in the granuloma, in the epidermis and in dermal nerves in a few cases. TNF-α, iNOS and TGF-β were all significantly associated with T1R (p<0.001). Sixty-eight nerve biopsies were analysed. CD68, TNF-α and iNOS staining were detectable in 88%, 38% and 28% of the biopsies respectively. The three cytokines TNF-α, iNOS and TGF-β detected by immunohistochemistry showed a significant association with the presence of skin reaction. This study is the first to demonstrate an association of iNOS and TGF-β with T1R.

Leprosy affects skin and peripheral nerves. Although we have effective antibiotics to treat the mycobacterial infection, a key part of the disease process is the accompanying inflammation. This can worsen after starting antibacterial treatment with episodes of immune mediated inflammation, so called ‘reactions’. These reactions are associated with worsening of the nerve damage. We recruited a cohort of 303 newly diagnosed leprosy patients in North India with the aim of understanding and defining the pathological processes better. We took skin and nerve biopsies from patients and examined them to define which molecules and mediators of inflammation were present. We found high levels of the cytokines Tumour Necrosis Factor alpha, Transforming Growth Factor beta and inducible Nitric Oxide Synthase in biopsies from patients with reactions. We also found high levels of bacteria and inflammation in the nerves. These experiments tell us that we need to determine which other molecules are present and to explore ways of switching off the production of these pro-inflammatory molecules.

Role of PGL-I of M. leprae in TNF-alpha production by in vitro whole blood assay

Phenolic glycolipid-I (PGL-I) is known to be a major antigen of Mycobacterium leprae. We have studied the influence of PGL-I on the production of Tumour Necrosis Factor alpha (TNF-alpha) using the in vitro whole blood assay. Armadillo-derived M. leprae (ADML) are thought to be depleted of PGL-I during the purification process. M. leprae obtained from mouse foot pad material (MFPML) has been subjected to a less rigorous purification process; their PGL-I coating is therefore believed to be more intact than that of ADML. PGL-I or ADML alone induced the secretion of minimal levels of TNF-alpha in whole blood assay; when added in combination, higher levels of this cytokine were observed. The highest TNF-alpha response was seen following stimulation with MFPML. MFP material not infected with ML did not elicit any response. The difference in TNF-alpha response shown by ADML and MFPML was postulated to be largely due to the presence of higher levels of PGL-I in MFPML. This increase in TNF-alpha production suggests that PGL-I may play a significant role in the induction of TNF-alpha during natural infection.

Expression of metalloproteinases (MMP-2, MMP-9, and TACE) and TNF-alpha in the nerves of leprosy patients

Matrix metalloproteinases (MMPs) and tumor necrosis factor alpha (TNF-alpha) play important and related roles in the pathogenesis of nerve injury. MMP-dependent and TNF-alpha-dependent processes of neurodegeneration, such as blood-nerve breakdown and immune cell recruitment, are characteristic of leprosy nerve damage. Our work has contributed to the understanding of the role of cytokines in the process, but the role of MMPs in the pathogenesis of neuritic leprosy has not been investigated. This study analyzed the changes in mRNA expression and immunodistribution of MMP-2, MMP-9, TNF-alpha-converting enzyme (TACE), TNF-alpha in nerves of 27 pure neuritic leprosy (PNL) patients, both acid-fast bacilli positive (AFB(+)) and acid-fast bacilli negative (AFB(-)), and 8 non-leprosy patients with control peripheral neuropathic conditions. MMP-2, MMP-9, and TNF-alpha mRNA expression was significantly induced in the AFB(-) relative to the AFB(+) neuritic leprosy group and nonlepritic controls; TACE levels were also elevated in the AFB(-) group, but this change was not statistically significant. Immunoreactive profiles for TNF-alpha and MMPs demonstrated strong reactivity of myelinated axons, infiltrating macrophages, Schwann cells, endothelial cells, and perineurial cells in neuritic leprosy biopsies. This study provides the evidence of the involvement of MMPs in the pathogenesis of PNL neuropathy.

Expression analysis of proteases of Mycobacterium leprae in human skin lesions

Proteases are commonly involved in bacterial pathogenesis and their inhibition has represented a successful therapeutic approach to treat infectious diseases. However, there is little information on the role of proteases in the pathogenesis of Mycobacteria. Five of these genes, three coding for putative secreted proteases, were selected in the present study to investigate their expression in Mycobacterium leprae isolated from skin biopsies of multibacillary leprosy patients. Via nested-PCR, it was demonstrated that mycP1 or ML0041, htrA2 or ML0176, htrA4 or ML2659, gcp or ML0379 and clpC or ML0235 are transcribed in vivo during the course of human infection. Moreover, the expression of Gcp in leprosy lesions was further confirmed by immunohistochemistry using a specific hyperimmune serum. This observation reinforces the potential role of mycobacterial proteases in the context of leprosy pathogenesis.

Aspects of genetic susceptibility to human infectious diseases

Host genetic factors play a major role in determining differential susceptibility to major infectious diseases of humans, such as malaria, HIV/AIDS, tuberculosis, and invasive pneumococcal disease. Progress in identifying the relevant genetic loci has come from a variety of approaches. Most convincing associations have been identified by case-control studies assessing biologically plausible candidate genes. All six of the genes that have a major effect on infectious disease susceptibility in humans have been identified in this way. However, recently genome-wide linkage analysis of affected sibling pairs has identified susceptibility loci for chronic infections such as leprosy and chronic hepatitis B virus persistence. Other approaches used successfully have included assessment in humans of the homologues of susceptibility genes mapped and identified in murine models. However, the great majority of susceptibility loci remain to be identified and the advent of large-scale genome-wide association scans offers a new approach to defining many of these.

Treating leprosy: an Erb-al remedy?

The leprosy pathogen Mycobacterium leprae attacks Schwann cells in the peripheral nervous system, causing them to demyelinate. Recent work by Tapinos et al. shows that a direct mechanism of demyelination induced by M. leprae depends on the binding of the bacterium to the receptor tyrosine kinase ErbB2 on Schwann cells and the resulting activation of the Ras-Raf-MEK-ERK pathway. These findings have relevance for the potential treatment of leprosy and they highlight parallels between the dedifferentiation signal in leprosy and that in nerve injury and cancer.

Recombinant Mycobacterium leprae protein associated with entry into mammalian cells of respiratory and skin components

BACKGROUND

The transmission of Mycobacterium leprae, the causative pathogen of leprosy, has been postulated to occur mainly through upper respiratory route rather than skin-to-skin contact via minor injuries. The M. leprae genome contains mce1A gene, which encodes a putative mammalian cell entry protein. However, to date, there have been no functional analyses of the M. leprae mce1A gene product.

OBJECTIVE

The aim of this study was to elucidate a possible relationship between this transmission mechanism and the mce1A gene product.

METHODS

We analyzed the cell uptake activity in vitro of polystyrene latex beads coated with a purified recombinant (r-) protein expressed by a 849-bp locus within the mce1A gene.

RESULTS

The r-protein promoted uptake of the beads into human nasal epithelial cells derived from nasal polyps, human bronchial epithelial cell line, normal human dermal fibroblasts, normal human microvascular endothelial cells and normal human keratinocytes cultured at 0.01 mM extracellular calcium concentration [Ca]; no uptake occurred with keratinocytes cultured at 1.2mM [Ca].

CONCLUSION

These results suggest that the mce1A gene product can mediate M. leprae entry into respiratory epithelial cells as their natural target cells, which may be the main mode of transmission. Endothelial cells, on the other hand, may serve as the reservoir of the bacilli for long-term infection. The M. leprae Mce1A protein has potential important implications for mode of transmission and pathogenesis of leprosy.

Expression of cyclooxygenase-2, alpha 1-acid-glycoprotein and inducible nitric oxide synthase in the developing lesions of murine leprosy

Murine leprosy is a chronic disease of the mouse, the most popular animal model used in biomedical investigation, which is caused by Mycobacterium lepraemurium (MLM) whose characteristic lesion is the macrophage-made granuloma. From onset to the end of the disease, the granuloma undergoes changes that gradually transform the environment into a more appropriate milieu for the growth of M. lepraemurium. The mechanisms that participate in the formation and maturation of the murine leprosy granulomas are not completely understood; however, microbial and host-factors are believed to participate in their formation. In this study, we analysed the role of various pro-inflammatory and anti-inflammatory proteins in granulomas of murine leprosy after 21 weeks of infection. We assessed the expression of cyclooxygenase-2 (COX-2), alpha acid-glycoprotein (AGP), and inducible nitric oxide synthase (iNOS) at sequential stages of infection. We also looked for the nitric-oxide nitrosylation product, nitrotyrosine (NT) in the granulomatous lesions of murine leprosy. We found that a pro-inflammatory environment predominates in the early granulomas while an anti-inflammatory environment predominates in late granulomas. No obvious signs of bacillary destruction were observed during the entire period of infection, but nitrosylation products and cell alterations were observed in granulomas in the advanced stages of disease. The change from a pro-inflammatory to an anti-inflammatory environment, which is probably driven by the bacillus itself, results in a more conducive environment for both bacillus replication and the disease progression.

The expression of RAGE and EN-RAGE in leprosy

BACKGROUND

Extracellular newly identified RAGE-binding protein (EN-RAGE) is a ligand of the receptor for advanced glycation endproducts (RAGE) and has been termed S100A12. The ligation of EN-RAGE with RAGE on the endothelium, mononuclear phagocytes and lymphocytes triggers cellular activation with the generation of the key proinflammatory mediators interleukin (IL)-1beta and tumour necrosis factor (TNF)-alpha.

OBJECTIVES

The aim of this study was to investigate the presence of RAGE and EN-RAGE, their spatial localization and their coexpression in leprosy lesions.

METHODS

Immunohistochemistry and confocal laser scanning microscopy were used to evaluate the expression of RAGE and EN-RAGE in leprosy. By enzyme-linked immunosorbent assay, RAGE and EN-RAGE were detected in the serum.

RESULTS

(1) In the multibacillary (MB) and paucibacillary (PB) groups, the level of RAGE production was significantly higher than in patients with atypical mycobacterial infection or sarcoidosis (P < 0.01). In the MB group, the production of RAGE was higher than in the PB group (P < 0.01), and it was higher in patients without the lepra reaction than in patients with the lepra reaction (P < 0.05). (2) In MB, PB and atypical mycobacterial infection, the level of EN-RAGE production was significantly higher than in sarcoidosis (P < 0.01). (3) In the confocal laser scanning microscopic examination, the RAGE and EN-RAGE proteins were detected in lepromatous leprosy. These proteins are spatially colocalized along the cell surface, which is in agreement with their receptor-ligand interaction. (4) A comparable amount of EN-RAGE was detected in the serum of the MB and PB groups. Patients with the reaction showed a higher level of EN-RAGE than patients without the reaction in leprosy.

CONCLUSIONS

Our data suggest that in leprosy, RAGE and EN-RAGE may be involved in the proinflammatory process rather than the antimycobacterial activity, especially during the lepra reaction. The blockade of the interaction of RAGE and EN-RAGE at the early stage of the inflammatory process may minimize the inflammatory response and consequent tissue damage or the sequelae of leprosy.

ErbB2 receptor tyrosine kinase signaling mediates early demyelination induced by leprosy bacilli

Demyelination is a common pathologic feature in many neurodegenerative diseases including infection with leprosy-causing Mycobacterium leprae. Because of the long incubation time and highly complex disease pathogenesis, the management of nerve damage in leprosy, as in other demyelinating diseases, is extremely difficult. Therefore, an important challenge in therapeutic interventions is to identify the molecular events that occur in the early phase before the progression of the disease. Here we provide evidence that M. leprae-induced demyelination is a result of direct bacterial ligation to and activation of ErbB2 receptor tyrosine kinase (RTK) signaling without ErbB2-ErbB3 heterodimerization, a previously unknown mechanism that bypasses the neuregulin-ErbB3-mediated ErbB2 phosphorylation. MEK-dependent Erk1 and Erk2 (hereafter referred to as Erk1/2) signaling is identified as a downstream target of M. leprae-induced ErbB2 activation that mediates demyelination. Herceptin (trastuzumab), a therapeutic humanized ErbB2-specific antibody, inhibits M. leprae binding to and activation of ErbB2 and Erk1/2 in human primary Schwann cells, and the blockade of ErbB2 activity by the small molecule dual ErbB1-ErbB2 kinase inhibitor PKI-166 (ref. 11) effectively abrogates M. leprae-induced myelin damage in in vitro and in vivo models. These results may have implications for the design of ErbB2 RTK-based therapies for both leprosy nerve damage and other demyelinating neurodegenerative diseases.

Antigen discovery: a postgenomic approach to leprosy diagnosis

Leprosy is an infectious, neurodegenerative disease of humans caused by Mycobacterium leprae. Despite effective control programs, the incidence of leprosy remains stubbornly high, suggesting that transmission may be more common than expected. The rationale of this work was to use bioinformatics and comparative genomics to identify potentially antigenic proteins for diagnostic purposes. This approach defined three classes of proteins: those restricted to M. leprae (class I), those present in M. leprae with orthologues in other organisms besides mycobacteria (class II), and exported or surface-exposed proteins (class III). Twelve genes (two class I, four class II, and six class III proteins) were cloned in Escherichia coli, and their protein products were purified. Six of these proteins were detected in cell extracts of M. leprae by immunoblotting. The immunogenicity of each recombinant protein was then investigated in leprosy patients by measuring the reactivity of circulating antibody and gamma interferon (IFN-gamma) responses in T-cell restimulation assays. Several class II and class III proteins were recognized by circulating antibodies. Importantly, most class II proteins elicited IFN-gamma responses that were significantly stronger than those produced by previously identified antigens. Among them, two class II proteins, ML0308 and ML2498, showed marked humoral and cellular immunogenicity, therefore providing promising candidates for the diagnosis of both tuberculoid and lepromatous forms of leprosy.

Leprosy: contribution of mast cells to epineurial collagenization

BACKGROUND

Leprosy, a disease caused by Mycobacterium leprae, is an important health problem worldwide. It is responsible for an irreversible nerve damage in which fibrosis plays an important role. The existence of an interaction between mast cells and different fibrotic conditions has long been observed. Tryptase, the most abundant protein product of human mast cells, has been shown to be mitogenic for fibroblasts and to increase type I collagen production.

PATIENTS AND METHODS

In order to explore the possible relationship between tryptase-rich mast cells and nerve fibrosis in leprosy, we studied 24 sural nerve biopsies of patients with leprous neuropathy. Mast cells stained with mouse antihuman mast cell antitryptase clone AA1 as well as fibrosis, were quantitatively estimated in both epi- and endoneurial compartments.

RESULTS

There was a remarkable association between collagen increase and tryptase-rich mast cell density in the epineurium but not in the endoneurium of leprous nerves.

CONCLUSION

Since the epineurium in leprosy is type I collagen rich, the present findings support a tryptase-rich mast cell contribution to epineurial collagenization in leprosy through their tryptase secretion.

Protective role of vitamin E on the oxidative stress in Hansen's disease (Leprosy) patients

BACKGROUND

A constellation of reactive oxygen species (ROS) capable of damaging cellular constituents generated in excess during the chronic, inflammatory, neurodegenerative disease process of leprosy. The consequences of this leads to enhanced oxidative stress and lower antioxidant status. Enzymatic antioxidants provide first line defense against ROS. We have measured the levels of oxidative stress indices like lipid peroxidation (LPO), protein carbonyls together with enzymatic antioxidants in the blood samples of control and leprosy patients. Nutritional rehabilitation by way of exogenous supplementation of functionally efficient antioxidants like vitamin E reactivates the enzymatic antioxidant system and guards against the insult caused by ROS during the pathogenesis of the disease and antileprosy chemotherapy.

DESIGN

Untreated leprosy patients were selected on the basis of clinical examination and skin smear. All diagnosed untreated leprosy patients received multi drug therapy (MDT) consisting of rifampicin, dapsone and clofazimine as recommended by World Health Organization. A small number of untreated cases were selected for co-supplementation of vitamin E along with MDT. Oxidative stress indices, enzymatic and nonenzymatic antioxidant status were assayed in untreated, MDT treated and those supplemented vitamin E along with MDT.

STATISTICAL METHODS

We have compared the significance in the mean+/-s.d. values of the oxidative stress indices and the levels of antioxidants using one way analysis of variance (ANOVA) between control, untreated, MDT treated and those supplemented vitamin E with MDT and the results were significant at P < 0.05. Statistical analysis of the results suggests that oral administration of vitamin E lowers oxidative stress and augments antioxidant status in affected individuals.

RESULTS

Enhanced oxidative stress as evidenced by increased LPO and protein carbonyl in leprosy cases lowers the antioxidant status. Treatment with MDT has a limited impact on increased oxidative stress and decreased antioxidant status. Coadministration of vitamin E along with MDT decreases oxidative stress and activate the antioxidant status.

DISCUSSION

The excess production of ROS as seen in leprosy cases could lead to degeneration of tissues and derangement of internal organs. The possible reason for the decreased antioxidant status in leprosy cases may be increased production of ROS, deranged liver function, and the free radical producing ability of drugs used in MDT of leprosy. Intervention with antioxidant supplementation like vitamin E prevents oxidative stress mediated through ROS and activates the net antioxidant status during the chronic course of the disease and antileprosy chemotherapy.

Laminins and their receptors in Schwann cells and hereditary neuropathies

This review focuses on the influence of laminins, mediated through laminin receptors present on Schwann cells, on peripheral nerve development and pathology. Laminins influence multiple aspects of cell differentiation and tissue morphogenesis, including cell survival, proliferation, cytoskeletal rearrangements, and polarity. Peripheral nerves are no exception, as shown by the discovery that defective laminin signals contribute to the pathogenesis of diverse neuropathies such as merosin-deficient congenital muscular dystrophy and Charcot-Marie-Tooth 4F, neurofibromatosis, and leprosy. In the last 5 years, advanced molecular and cell biological techniques and conditional mutagenesis in mice began revealing the role of different laminins and receptors in developing nerves. In this way, we are starting to explain morphological and pathological observations beginning at the start of the last century. Here, we review these recent advances and show how the roles of laminins and their receptors are surprisingly varied in both time and place.

DNA damage studies in untreated and treated leprosy patients

The alkaline single cell gel electrophoresis assay was performed on peripheral blood lymphocytes of lepromatous and tubercloid leprosy patients (untreated and those undergoing treatment) in order to ascertain whether differential damage to DNA occurs. The study group included 28 male and 2 female patients and 15 healthy males who were matched for age and socio-economic status. The results revealed DNA damage in all patients, with a mean DNA migration length of 29.88 +/- 3.39 microm and 38% of their cells damaged when compared with the respective values obtained in healthy controls (1.28 +/- 0.40 microm, 5%). Multiple regression analysis for effects of confounding factors revealed antibiotic treatment in patients and alcohol consumption in controls as the only variables influencing DNA damage. In lepromatous and tubercloid patients, both untreated and those undergoing treatment, DNA damage increased significantly from that observed in control individuals, with greater increased damage in lepromatous patients. An increase in treatment time increased DNA damage linearly. Furthermore, an arbitrary classification of damaged cells (categories I-IV) was made based on observed tail lengths in leprosy patients (5.00-225.00 microm). The number of damaged cells in untreated patients was lower than in those undergoing treatment; the latter also had more cells with greater DNA migration lengths. There were no category III or IV cells in the control group. The results of the study therefore reveal that patients undergoing therapy had significantly greater DNA damage than untreated patients, indicating bacterial infection and drug therapy as the causal factors, since lepromatous-type disease is the more severe form with the patients having lower resistance to Mycobacterium leprae and requiring heavier and prolonged dosage of antibiotics. The study also corroborates that the assay offers an opportunity for correlating levels of therapy-induced DNA damage with administered dose and for modulating the dose-schedule so as to achieve lower levels of genotoxic damage.

Biological implications of Mycobacterium leprae gene expression during infection

The genome of Mycobacterium leprae, the etiologic agent of leprosy, has been sequenced and annotated revealing a genome in apparent disarray and in stark contrast to the genome of the related human pathogen, M. tuberculosis. With less than 50% coding capacity of a 3.3-Mb genome and 1,116 pseudogenes, the remaining genes help define the minimal gene set necessary for in vivo survival of this mycobacterial pathogen as well as genes potentially required for infection and pathogenesis seen in leprosy. To identify genes transcribed during infection, we surveyed gene transcripts from M. leprae growing in athymic nude mice using reverse transcriptase-polymerase chain reaction (RT-PCR) and cross-species DNA microarray technologies. Transcripts were detected for 221 open reading frames, which included genes involved in DNA replication, cell division, SecA-dependent protein secretion, energy production, intermediary metabolism, iron transport and storage and genes associated with virulence. These results suggest that M. leprae actively catabolizes fatty acids for energy, produces a large number of secretory proteins, utilizes the full array of sigma factors available, produces several proteins involved in iron transport, storage and regulation in the absence of recognizable genes encoding iron scavengers and transcribes several genes associated with virulence in M. tuberculosis. When transcript levels of 9 of these genes were compared from M. leprae derived from lesions of multibacillary leprosy patients and infected nude mouse foot pad tissue using quantitative real-time RT-PCR, gene transcript levels were comparable for all but one of these genes, supporting the continued use of the foot pad infection model for M. leprae gene expression profiling. Identifying genes associated with growth and survival during infection should lead to a more comprehensive understanding of the ability of M. leprae to cause disease.

Alterations in neurofilament protein(s) in human leprous nerves: morphology, immunohistochemistry and Western immunoblot correlative study

Using a specific antibody (SMI 31), the state of phosphorylation of high and medium molecular weight neurofilaments (NF-H and NF-M) was studied in 22 leprous and four nonleprous human peripheral nerves by means of immunohistochemistry, sodium dodecyl sulfate-poly acrylamide gel electrophoresis (SDS-PAGE) and Western immunoblot (WB). The results thus obtained were compared with morphological changes in the respective nerves studied through light and electron microscopy. Many of the leprous nerves showing minimal pathology revealed lack of or weak staining with SMI 31, denoting dephosphorylation. Remyelinated fibres stained intensely with SMI 31 antibody. The WB analysis of Triton X-100 insoluble cytoskeletal preparation showed absence of regular SMI 31 reactive bands corresponding to 200 and 150 kDa molecular weight (NF-H and NF-M, respectively) in 10 nerves. Three of the 10 nerves revealed presence of NF protein bands in SDS-PAGE but not in WB. Presence of additional protein band (following NF-M) was seen in four nerves. Two nerves revealed NF-H band but not NF-M band and one nerve showed trace positivity. In the remaining five nerves presence of all the three NF bands was seen. Thus, 77.3% (17/22) of human leprous nerves studied showed abnormal phosphorylation of NF protein(s). The ultrastructural study showed abnormal compaction and arraying of NF at the periphery of the axons in the fibres with altered axon to myelin thickness ratio (atrophied fibres) as well as at the Schmidt-Lantermann (S-L) cleft region. Such NF changes were more pronounced in the severely atrophied axons suggesting a direct correlation. The observed well-spaced NF in the remyelinated fibres under ultrastructural study was in keeping with both intense SMI 31 staining and presence of NF triplet bands seen in WBs in four of leprous nerves that showed a large number of regenerating fibres suggesting reversal of changes with regeneration. Findings in the present study suggest that atrophy, that is, the reduction in axonal calibre and paranodal demyelination, seen in leprous nerves may result from dephosphorylation of NF-H and NF-M proteins.

Activation of Signaling Lymphocytic Activation Molecule Triggers a Signaling Cascade That Enhances Th1 Responses in Human Intracellular Infection

T cell production of IFN-gamma contributes to host defense against infection by intracellular pathogens, including mycobacteria. Lepromatous leprosy, the disseminated form of infection caused by Mycobacterium leprae, is characterized by loss of cellular response against the pathogen and diminished Th1 cytokine production. Relieving bacterial burden in Ag-unresponsive patients might be achieved through alternative receptors that stimulate IFN-gamma production. We have previously shown that ligation of signaling lymphocytic activation molecule (SLAM) enhances IFN-gamma in mycobacterial infection; therefore, we investigated molecular pathways leading from SLAM activation to IFN-gamma production in human leprosy. The expression of the SLAM-associated protein (an inhibitory factor for IFN-gamma induction) on M. leprae-stimulated cells from leprosy patients was inversely correlated to IFN-gamma production. However, SLAM ligation or exposure of cells from lepromatous patients to a proinflammatory microenvironment down-regulated SLAM-associated protein expression. Moreover, SLAM activation induced a sequence of signaling proteins, including activation of the NF-kappaB complex, phosphorylation of Stat1, and induction of T-bet expression, resulting in the promotion of IFN-gamma production, a pathway that remains quiescent in response to Ag in lepromatous patients. Therefore, our findings reveal a cascade of molecular events during signaling through SLAM in leprosy that cooperate to induce IFN-gamma production and strongly suggest that SLAM might be a focal point for therapeutic modulation of T cell cytokine responses in diseases characterized by dysfunctional Th2 responses.

Nitrotyrosine localization to dermal nerves in borderline leprosy

BACKGROUND

Nerve damage is a common and disabling feature of leprosy, with unclear aetiology. It has been reported that the peroxidizing agents of myelin lipids-nitric oxide (NO) and peroxynitrite-are produced in leprosy skin lesions.

OBJECTIVES

To investigate the localization of nitrotyrosine (NT)-a local end-product of peroxynitrite-in leprosy lesions where dermal nerves are affected by a granulomatous reaction.

METHODS

We investigated by immunohistochemistry and immunoelectron microscopy the localization of the inducible NO synthase (iNOS) and NT in biopsies exhibiting dermal nerves from patients with untreated leprosy.

RESULTS

There were abundant NT-positive and iNOS-positive macrophages in the borderline leprosy granulomas infiltrating peripheral nerves identified by light microscopy, S-100 and neurofilament immunostaining. Immunoelectron microscopy showed NT reactivity in neurofilament aggregates and in the cell wall of Mycobacterium leprae.

CONCLUSIONS

Our results suggest that NO and peroxynitrite could be involved in the nerve damage following borderline leprosy.

Comparative proteomics of the Mycobacterium leprae binding protein myelin P0: its implication in leprosy and other neurodegenerative diseases

Mycobacterium leprae, the causative agent of leprosy invades Schwann cells of the peripheral nerves leading to nerve damage and disfigurement, which is the hallmark of the disease. Wet experiments have shown that M. leprae binds to a major peripheral nerve protein, the myelin P zero (P0). This protein is specific to peripheral nerve and may be important in the initial step of M. leprae binding and invasion of Schwann cells which is the feature of leprosy. Though the receptors on Schawann cells, cytokines, chemokines and antibodies to M. leprae have been identified the molecular mechanism of nerve damage and neurodegeneration is not clearly defined. Recently pathogen and host protein/nucleotide sequence similarities (molecular mimicry) have been implicated in neurodegenerative diseases. The approach of the present study is to utilise bioinformatic tools to understand leprosy nerve damage by carrying out sequence and structural similarity searches of myelin P0 with leproma and other genomic database. Since myelin P0 is unique to peripheral nerve, its sequence and structural similarities in other neuropathogens have also been noted. Comparison of myelin P0 with the M. leprae proteins revealed two characterised proteins, Ferrodoxin NADP reductase and a conserved membrane protein, which showed similarity to the query sequence. Comparison with the entire genomic database (www.ncbi.nlm.nih.gov) by basic local alignment search tool for proteins (BLASTP) and fold classification of structure-structure alignment of proteins (FSSP) searches revealed that myelin P0 had sequence/structural similarities to the poliovirus receptor, coxsackie-adenovirus receptor, anthrax protective antigen, diphtheria toxin, herpes simplex virus, HIV gag-1 peptide, and gp120 among others. These proteins are known to be associated directly or indirectly with neruodegeneration. Sequence and structural similarities to the immunoglobin regions of myelin P0 could have implications in host-pathogen interactions, as it has homophilic adhesive properties. Although these observed similarities are not highly significant in their percentage identity, they could be functionally important in molecular mimicry, receptor binding and cell signaling events involved in neurodegeneration.

Determination of Clofazimine in Leprosy Patients by High-Performance Liquid Chromatography

An original, simple, specific, and rapid high-performance liquid chromatography assay for the determination of clofazimine in human plasma is presented. The procedure consists of extracting the drug and the internal standard (medazepam) from 0.5 mL plasma with dichloromethane/diisopropyl ether (1:1, v/v) at pH 3.0, after precipitating the proteins with methanol. The drugs were then quantitated on a reversed-phase C8 using a mobile phase consisting of a mixture of methanol/0.25 N sodium acetate buffer at pH 3.0 (74:26, v/v). The flow-rate and wavelength were set at 1 mL/min and 286 nm, respectively. The precision, linearity, and limit of quantitation of the method were within acceptable limits. The method was considered adequate and could be applied in studies involving blood level monitoring and pharmacokinetics in leprosy patients.

Differential TNFalpha mRNA regulation detected in the epidermis of leprosy patients

The epidermis is an important site of the immunoinflammatory response in the skin. In the present study, the expression of cytokine and ICAM-1 (intercellular adhesion molecule-1) genes was evaluated by RT-PCR in the epidermis isolated from biopsies from 25 reactional leprosy patients. TNFalpha and IL-6 mRNAs were detected in all individuals during the reactional state (reversal reaction or erythema nodosum leprosum), IL-8 message was detected in 66.6% and 62.5% of the patients, IL-12 mRNA was present in 91.6% and 62.5% and ICAM-1 in 100% and 71.4%, respectively. In addition, when skin biopsies were obtained from the same patients before and during the reactional episode, an enhancement in cytokine mRNA, but not in ICAM-1 mRNA, was observed. Seven patients were also evaluated at the onset of reaction and during antiinflammatory treatment. In contrast to a preferential decrease in the TNFalpha gene detected in the dermis, during the treatment phase, persistent/enhanced TNFalpha mRNA expression was detected in the epidermis in six out of the seven patients assessed. This peculiar pattern of expression might reflect a differential impact that in vivo antiinflammatory therapy has on the epidermis. The present findings indicate that the epidermis plays an important role in the local inflammatory response in leprosy and that the profile of response detected in the epidermis during the reactions may be regulated differently from that in the dermis.

Local nerve damage in leprosy does not lead to an impaired cellular immune response or decreased wound healing in the skin

This study investigated whether peripheral nerve damage in patients with leprosy impairs local cellular immune responses, thereby reducing wound healing and leading to chronic skin ulceration. Anesthetic and contralateral sensitive skin sites in 42 patients with leprosy were compared for delayed-type hypersensitivity responses to purified protein derivative (PPD) of tuberculin. Leukocyte recruitment, epidermal activation, keratinocyte proliferation, and rates of wound healing after skin biopsy were compared. No significant differences in PPD-induced induration, epidermal activation and thickening or numbers of total T cells, CD8+ T cells, CD1a+ Langerhans cells, and proliferating Ki67+ keratinocytes were observed between anesthetic and sensitive skin sites. Similarly, rates of wound healing over 5 days after skin biopsy did not differ significantly. Thus, local leprosy-associated anesthesia does not appear to contribute to local immune compromise or impaired wound healing. Rather, chronic cutaneous ulceration in leprosy most likely results from repeated trauma associated with loss of sensation.

Osteoporosis, bone turnover and hypogonadism in elderly men with treated leprosy

In male hypogonadism associated with bone loss, it is important to determine whether bone loss continues with ageing and an increased risk of fracture. We studied bone metabolism in 86 male leprosy patients, who were classified according to the presence or absence of osteoporosis. Osteoporosis was present when men had lumbar compression fractures or a mean BMD-2SD that of normal Japanese men in each age decade. Four men had fractures. Serum concentrations of 1,25-dihydroxyvitamin D and high-sensitivity parathyroid hormone were almost normal in both groups, whereas free testosterone and oestradiol were significantly lower in the osteoporosis group than in the non-osteoporosis group (free testosterone: P < 0.01, oestradiol: P < 0.05). The urinary concentrations of pyridinoline and deoxypyridinoline, as a marker of bone absorption, were significantly higher in the osteoporosis group than in the non-osteoporosis group (pyridinoline: P < 0.01, deoxypyridinoline: P < 0.01). The serum concentration of osteocalcin, a marker of bone formation, was significantly higher in the osteoporosis group than in the non-osteoporosis group (P < 0.01). Elevated concentration means that bone repair is increased possibly because of compensation mechanisms for increased bone loss. In the osteoporosis group, hypogonadism occurred, and high bone turnover continued even in older men. We recommend clinical studies of treatment such as replacement therapy to prevent bone loss and increasing risk of fractures in older men with leprosy.