Temperature dependency for survival of Mycobacterium leprae in macrophages

Evaluation of Clinical, Hormonal and Ultrasound Parameters of Male Reproductive System in Leprosy: A Cross-Sectional Study

Background and Objectives

Testicular involvement in leprosy is neglected as it is insidious and silent, although it can have an impact on quality of life. Our study aimed at evaluating and estimating the frequency of the hormonal, radiological and clinical parameters in these patients.

Materials and Methods

A cross-sectional study was conducted including 31 male leprosy patients attending our OPD. After detailed clinical assessment, patients were subjected to ultrasonological with Doppler examination of the scrotum and hormonal evaluation by ELISA technique for serum follicle-stimulating hormone (FSH), luteinising hormone (LH) and total testosterone.

Results

Thirty-one patients were included with ages ranging from 19 to 54 with a mean of 34 years. Decreased libido (19.3%) was significantly observed in the abnormal FSH (P < 0.01) and testosterone (P < 0.01) groups. The majority of the clinical findings such as erectile dysfunction, infertility and altered pubic hair pattern were seen in the lepromatous spectrum. Six (19.6%) patients had increased LH and FSH. Twenty-three (74%) had testicular atrophy (<12 ml) as assessed by USG. There was a significant association between the bilateral decreased testicular volumes (TVs) and FSH (P = 0.016 on the left and P < 0.01 on the right). Four of 31 patients had altered testicular echo texture of which two belong to the BL spectrum. The increase in the resistive index (RI) corresponded significantly to the decreased TV (P < 0.01) albeit on the left side only.

Conclusion

A sizeable proportion (74%) of the study sample had testicular atrophy. The significant association between increased RI and testicular atrophy, especially in patients with infertility, emphasises the ancillary role of Doppler indices in methodical diagnosis. Risk factors noted in the study include increased bacillary index, delayed initiation of treatment and recurrent ENL. Early detection, early initiation of MDT and specific therapies such as testosterone replacement can help improve the quality of life.

Existence of viable Mycobacterium leprae in natural environment and its genetic profiling in a leprosy endemic region

Introduction

Molecular epidemiology of leprosy is very important to study leprosy transmission dynamics and to enhance our understanding of leprosy in endemic areas by utilizing the molecular typing method. Nowadays our understanding of leprosy transmission dynamics has been refined by SNP typing and VNTR marker analysis of M. leprae strains.

Objective

This study was carried out to find out the presence of viable M. leprae in the soil and water samples from residing areas of leprosy patients staying in different blocks of Purulia district of West Bengal, understanding their genotypes and compared with that of M. leprae present in patients.

Material and methods

Slit-skin smear (SSS) samples (n=112) were collected from the active multibacillary leprosy patients from different blocks of leprosy endemic area. Soil samples (n=1060) and water samples (n=620) were collected from residing areas of leprosy patients. SNP subtyping was performed by PCR followed by sequencing. Multiplex PCR was performed using fifteen ML-VNTR loci and results were analysed.

Results

We observed high PCR positivity in soil samples (344 out of 1060; 32%) and water samples (140 out of 620; 23%). These PCR positive samples when further screened for viability, it was observed that 150 soil samples (44%) and 56 water samples (40%) showed presence of 16S rRNA. SNP typing of M. leprae revealed presence of predominantly type 1. SNP subtype 1D (83%) was most prevalent in all the blocks of Purulia followed by subtype 1C (15%) and subtype 1A (2%). SNP subtype 2F was noted in only one sample. SNP and VNTR combination showed presence of similar strain type in certain pockets of Purulia region which was responsible for transmission.

Conclusion

Presence of viable M. leprae in the environment, and presence of SNP Type 1 M. leprae in patients and environment suggests both environment and patients play a role in disease transmission.

DNA gyrase could be a crucial regulatory factor for growth and survival of Mycobacterium leprae

Leprosy, an important infectious disease in humans caused by Mycobacterium leprae (Mle), remains endemic in many countries. Notably, the pathogen cannot be cultured in vitro, except in mouse footpads in vivo. The molecular basis of these characteristics and the mechanisms remain unknown. Consequently, analysis of Mle growth and survival is urgently needed to develop novel therapies against leprosy, including rapid, simple, and specific methods to detect infection. Here, we demonstrated the functional role and contribution of Mle-DNA gyrase, which regulates DNA topology, DNA replication, and chromosome segregation to promote bacterial growth and survival, in Mle growth and survival in vitro and in vivo. The optimum temperature for Mle-DNA gyrase activity was 30 °C. When the DNA gyrB-gyrA genes in Mycobacterium smegmatis were replaced with the Mle gyrase genes by allelic exchange, the recombinants could not grow at 37 °C. Moreover, using radiorespirometry analysis for viability of Mle bacilli, we found that Mle growth was more vigorous at 25–30 °C than at 37 °C, but was inhibited above 40 °C. These results propose that DNA gyrase is a crucial factor for Mle growth and survival and its sensitivity to temperature may be exploited in heat-based treatment of leprosy.

Clinical electrophysiology of axonal polyneuropathies

Axonal neuropathies encompass a wide range of acquired and inherited disorders with electrophysiologic characteristics that arise from the unique neurophysiology of the axon. Accurate interpretation of nerve conduction studies and electromyography requires an in-depth understanding of the pathophysiology of the axon. Here we review the unique neurophysiologic properties of the axon and how they relate to clinical electrodiagnostic features. We review the length-dependent Wallerian or "dying-back" processes as well as the emerging body of literature from acquired axonal neuropathies that highlights the importance of axonal disease at the nodes of Ranvier. Neurophysiologic features of individual inherited and acquired axonal diseases, including primary nerve disease as well as systemic immune mediated, metabolic, and toxic diseases involving the peripheral nerve, are reviewed. This comprehensive review of electrodiagnostic findings coupled with the current understanding of pathophysiology will aid the clinician in the evaluation of axonal polyneuropathies.

IL-10 and NOS2 modulate antigen-specific reactivity and nerve infiltration by T cells in experimental leprosy

Background

Although immunopathology dictates clinical outcome in leprosy, the dynamics of early and chronic infection are poorly defined. In the tuberculoid region of the spectrum, Mycobacterium leprae growth is restricted yet a severe granulomatous lesion can occur. The evolution and maintenance of chronic inflammatory processes like those observed in the leprosy granuloma involve an ongoing network of communications via cytokines. IL-10 has immunosuppressive properties and IL-10 genetic variants have been associated with leprosy development and reactions.

Methodology/Principal Findings

The role of IL-10 in resistance and inflammation in leprosy was investigated using Mycobacterium leprae infection of mice deficient in IL-10 (IL-10−/−), as well as mice deficient in both inducible nitric oxide synthase (NOS2−/−) and IL-10 (10NOS2−/−). Although a lack of IL-10 did not affect M. leprae multiplication in the footpads (FP), inflammation increased from C57Bl/6 (B6)<IL-10−/−<NOS2−/−<10NOS2−/−. While IL-10−/− mice exhibited modest FP induration compared to B6, NOS2−/− and 10NOS2−/− mice developed markedly enlarged FP marking distinct phases: early (1 month), peak (3–4 months), and chronic (8 months). IFN-γ-producing CD4+CD44+ cells responding to M. leprae cell wall, membrane, and cytosol antigens and ML2028 (Ag85B) were significantly increased in the evolved granuloma in NOS2−/− FP compared to B6 and IL-10−/− during early and peak phases. In 10NOS2−/− FP, CD4+CD44+ and especially CD8+CD44+ responses were augmented even further to these antigens as well as to ML0380 (GroES), ML2038 (bacterioferritin), and ML1877 (EF-Tu). Moreover, fragmented nerves containing CD4+ cells were present in 10NOS2−/− FP.

Conclusions/Significance

The 10NOS2−/− strain offers insight on the regulation of granuloma formation and maintenance by immune modulators in the resistant forms of leprosy and presents a new model for investigating the pathogenesis of neurological involvement.

Despite effective antimicrobial therapy, 30–50% of leprosy patients develop immunological complications called leprosy reactions before, during or even years after being cured. Leprosy reactions are a major risk for neuritis that leads to peripheral nerve damage, disfigurement and disability. Unfortunately, why and how leprosy reactions occur is not well understood. Based on the latest human genetic leprosy susceptibility research and mouse infection models, we generated a double knockout mouse strain (10NOS2−/−) which has deficiencies in two key immune factors, interleukin-10 (IL-10) and inducible nitric oxide synthase (NOS2). We investigated the dynamics of the immune response to Mycobacterium leprae infection and chronicled the types of immune cells recruited to the site of infection. 10NOS2−/− mice developed a substantial induration in response to infection, as well as an increased interferon-gamma response to components of the leprosy bacillus. Interestingly, these animals also exhibited CD4+ T cell infiltration into the nerves, a phenomenon which has not been previously reported in leprosy mouse models. This new model provides insight into potential mechanisms whereby immune modulators may regulate leprosy reactions and neuritis and could aid the development of tests for monitoring and treatment of leprosy patients.

Cohort study of the seasonal effect on nasal carriage and the presence of Mycobacterium leprae in an endemic area in the general population

Leprosy continues to be a significant health problem in certain pockets in developing countries. Better understanding of the transmission and source of the infection would help to decipher the transmission link, leading to control of the spread of the disease. The nose is considered to be a portal of entry, suggesting an aerial route for transmission through droplet infection. The evidence suggests that many individuals from endemic countries carry Mycobacterium leprae in their nasal cavities without having obvious symptoms of leprosy. The objective of the present study was to assess the presence of M. leprae on the nasal mucosa in the general population from a leprosy-endemic pocket. M. leprae detection was carried out using PCR targeting RLEP. Four hundred subjects from an area highly endemic for leprosy were included in the study and followed up during three different seasons--winter, summer, and monsoon--for evidence of nasal exposure to M. leprae. PCR positivity for M. leprae was observed in 29%, 21% and 31% of the samples collected in winter, summer and the monsoon season, respectively. Twenty-six individuals from the cohort showed amplification for M. leprae for all seasons. Our results are consistent with reports in the literature showing widespread exposure to M. leprae in the endemic community. The results also suggest possible association of the environmental conditions (climate) with the transmission pattern and levels of exposure to M. leprae. However, the present study indicated that the population from highly endemic pockets will have exposure to M. leprae irrespective of season.

Identification and characterization of a spore-like morphotype in chronically starved Mycobacterium avium subsp. paratuberculosis cultures

Mycobacteria are able to enter into a state of non-replication or dormancy, which may result in their chronic persistence in soil, aquatic environments, and permissive hosts. Stresses such as nutrient deprivation and hypoxia provide environmental cues to enter a persistent state; however, a clear definition of the mechanism that mycobacteria employ to achieve this remains elusive. While the concept of sporulation in mycobacteria is not novel, it continues to spark controversy and challenges our perceptions of a non-replication. We investigated the potential role of sporulation in one-year old broth cultures of Mycobacterium subsp. paratuberculosis (MAP).

We show that dormant cultures of MAP contain a mix of vegetative cells and a previously unknown morphotype resembling a spore. These spore-like structures can be enriched for using sporulating media. Furthermore, purified MAP spore forms survive exposure to heat, lysozyme and proteinase K. Heat-treated spores are positive for MAP 16SrRNA and IS900. MAP spores display enhanced infectivity as well as maintain acid-fast characteristics upon germination in a well-established bovine macrophage model. This is the first study to demonstrate a new MAP morphotype possessing spore-like qualities. Data suggest that sporulation may be a viable mechanism by which MAP accomplishes persistence in the host and/or environment. Thus, our current understanding of mycobacterial persistence, pathogenesis, epidemiology and rational drug and vaccine design may need to be reevaluated.