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Mycobacterium leprae infection of peripheral nerves and the subsequent nerve function impairment (NFI), especially in response to reactional episodes, are hallmarks of leprosy. Improved treatments for M. leprae-induced nerve injury are needed, as most if not all of the disability and stigma associated with leprosy arises from the direct or indirect effects of NFI. Nine-banded armadillos (Dasypus novemcinctus), like humans, exhibit the full clinical spectrum of leprosy and extensive involvement of the peripheral nerves. In this study, state-of-the-art technology was used to compare nerve function between uninfected and M. leprae-infected armadillos. Motor nerve conduction velocity (MNCV) and compound muscle action potential (cMAP), which measure changes in the rate of impulse conduction velocity and amplitude, revealed a progression of impairment that was directly correlated with the duration of M. leprae infection and enabled development of an objective nerve impairment scoring system. Ultrasonography accompanied by color Doppler imaging detected enlargement of the M. leprae-infected nerves and increased vascularity, possibly due to inflammation. Assessment of epidermal nerve fiber density (ENFD), which shows a length-dependent innervation in armadillos that is similar to humans, identified small fiber degeneration early after M. leprae infection. Staining for neuromuscular junction (NMJ) integrity, which is an indicator of signal transduction efficiency into skeletal muscle, discerned a markedly lower number and structural integrity of NMJ in M. leprae-infected armadillo footpads. These tools for assessing nerve injury were used to monitor the effects of intervention therapy. Two potential neuro-protective drugs, ethoxyquin (EQ) and 4-aminopyridine (4-AP), were tested for their ability to ameliorate peripheral nerve injury in M. leprae-infected armadillos. 4-AP treatment improved MNCV, cMAP, and EFND compared to untreated animals, while EQ had less effect. These results support the armadillo as a model for M. leprae-induced peripheral nerve injury that can provide insights toward the understanding of NFI progression and contribute to the preclinical investigation of the safety and efficacy of neuro-preventive and neuro-therapeutic interventions for leprosy.

Neuropathy and related disabilities are the major medical consequences of leprosy, which remains a global medical concern. Despite major advances in understanding the mechanisms of M. leprae entry into peripheral nerves, most aspects of the pathogenesis of leprosy neuropathy remain poorly understood. Sensory loss is characteristic of leprosy, but neuropathic pain is sometimes observed. Effective anti-microbial therapy is available, but neuropathy remains a problem especially if diagnosis and treatment are delayed. Currently there is intense interest in post-exposure prophylaxis with single-dose rifampin in endemic areas, as well as with enhanced prophylactic regimens in some situations. Some degree of nerve involvement is seen in all cases and neuritis may occur in the absence of leprosy reactions, but acute neuritis commonly accompanies both Type 1 and Type 2 leprosy reactions and may be difficult to manage. A variety of established as well as new methods for the early diagnosis and assessment of leprosy neuropathy are reviewed. Corticosteroids offer the primary treatment for neuritis and for subclinical neuropathy in leprosy, but success is limited if nerve function impairment is present at the time of diagnosis. A candidate vaccine has shown apparent benefit in preventing nerve injury in the armadillo model. The development of new therapeutics for leprosy neuropathy is greatly needed. [ABSTRACT FROM AUTHOR]

Abstract Background Glutamate excitotoxicity is thought to be involved in the pathogenesis of neurodegenerative disease. One potential source of glutamate is N-acetyl-aspartyl-glutamate (NAAG) which is hydrolyzed to glutamate and N-acetyl-aspartate (NAA) in a reaction catalyzed by glutamate carboxypeptidase (GCP). As a result, GCP inhibition is thought to be beneficial for the treatment of neurodegenerative diseases where excess glutamate is presumed pathogenic. Both pharmacological and genetic inhibition of GCP has shown therapeutic utility in preclinical models and this has led to GCP inhibitors being pursued for the treatment of nervous system disorders in human clinical trials. Specifically, GCP inhibitors are currently being developed for peripheral neuropathy and neuropathic pain. The purpose of this study was to develop a pharmacodynamic (PD) marker assay to use in clinical development. The PD marker will determine the effect of GCP inhibitors on GCP enzymatic activity in human skin as measure of inhibition in peripheral nerve and help predict drug doses required to elicit pharmacologic responses. Methods GCP activity was first characterized in both human skin and rat paw pads. GCP activity was then monitored in both rodent paw pads and sciatic nerve from the same animals following peripheral administration of various doses of GCP inhibitor. Significant differences among measurements were determined using two-tailed distribution, equal variance student's t test. Results We describe for the first time, a direct and quantifiable assay to evaluate GCP enzymatic activity in human skin biopsy samples. In addition, we show that GCP activity in skin is responsive to pharmacological manipulation; GCP activity in rodent paws was inhibited in a dose response manner following peripheral administration of a potent and selective GCP inhibitor. Inhibition of GCP activity in rat paw pads was shown to correlate to inhibition of GCP activity in peripheral nerve. Conclusion Monitoring GCP activity in human skin after administration of GCP inhibitors could be readily used as PD marker in the clinical development of GCP inhibitors. Enzymatic activity provides a simple and direct measurement of GCP activity from tissue samples easily assessable in human subjects.

Objective: To determine the utility of skin biopsies as a biomarker of disease severity in subjects with amyloid neuropathy.Methods: Five groups of patients were studied: (1) transthyretin (TTR) familial amyloidotic polyneuropathy (FAP; n = 20), (2) TTR mutation carriers without peripheral neuropathy (TTR-noPN; n = 10), (3) healthy controls (n = 20), (4) diabetic neuropathy disease controls (n = 20), and (5) patients with light-chain (AL) amyloid (n = 2). All subjects underwent neurological examination and 3mm skin biopsies. Sections were stained with anti-PGP9.5, anti-TTR, and Congo red. Intraepidermal (IENFD), sweat gland (SGNFD), and pilomotor nerve fiber densities (PMNFD) were measured. Correlations between the amount of amyloid present (amyloid burden), fiber subtype, and Neuropathy Impairment Score in the Lower Limbs (NIS-LL) were evaluated.Results: IENFD, SGNFD, and PMNFD were all significantly reduced in TTR-FAP patients versus healthy controls, whereas TTR-noPN subjects had intermediate reductions. Lower nerve fiber densities were associated with NIS-LL (p < 0.001). Congo red staining revealed brilliant red amyloid deposits confirmed by apple-green birefringence within dermal collagen, sweat glands, and arrector pili that engulfed axons. The diagnostic sensitivity and specificity to detect amyloid in skin were 70% and 100%. Both AL amyloidosis and 2 of 10 TTR-noPN subjects were Congo red-positive. Amyloid burden correlated with IENFD (r = -0.63), SGNFD (r = -0.67), PMNFD (r = -0.50), and NIS-LL (r = -0.57). Wild-type TTR staining was less prominent in TTR-FAP patients.Interpretation: Cutaneous amyloid was detected in 70% of TTR-FAP and 20% of TTR-noPN subjects. Amyloid burden correlated strongly with reductions in IENFD, SGNFD, PMNFD, and NIS-LL. Skin is an attractive tissue to establish an amyloid diagnosis, and amyloid burden has potential as a biomarker to detect treatment effect in TTR-FAP drug trials. Ann Neurol 2017;82:44-56. [ABSTRACT FROM AUTHOR]

Quantitative assessment of epidermal nerve fibers (ENFs) has become a widely used clinical tool for the diagnosis of small fiber neuropathies such as diabetic neuropathy and human immunodeficiency virus–associated sensory neuropathy (HIV-SN). To model and investigate the pathogenesis of HIV-SN using simian immunodeficiency virus (SIV)-infected Asian macaques, we adapted the skin biopsy and immunostaining techniques currently employed in human patients and then developed two unbiased image analysis techniques for quantifying ENF in macaque footpad skin. This report provides detailed descriptions of these tools and techniques for ENF assessment in macaques and outlines important experimental considerations that we have identified in the course of our long-term studies. Although initially developed for studies of HIV-SN in the SIV-infected macaque model, these methods could be readily translated to a range of studies involving peripheral nerve degeneration and neurotoxicity in nonhuman primates as well as preclinical investigations of agents aimed at neuroprotection and regeneration. [ABSTRACT FROM AUTHOR]

Nine–banded armadillos develop peripheral neuropathy after experimental Mycobacterium leprae infection that recapitulates human disease. We used an intracutaneous excision axotomy model to assess the effect of infection duration by M. leprae on axonal sprouting and Schwan cell density. 34 armadillos (17 naïve and 17 M. leprae -infected) underwent 3 mm skin biopsies to create an intracutaneous excision axotomy followed by a concentric 4-mm overlapping biopsy 3 and 12-months post M. leprae inoculation. A traditional distal leg biopsy was obtained at 15mo for intraepidermal nerve fiber (IENF) density. Serial skin sections were immunostained against a axons (PGP9.5, GAP43), and Schwann cells (p75, s100) to visualize regenerating nerves. Regenerative axons and proliferation of Schwann cells was measured and the rate of growth at each time point was assessed. Increasing anti-PGL antibody titers and intraneural M. leprae confirmed infection. 15mo following infection, there was evidence of axon loss with reduced distal leg IENF versus naïve armadillos, p < 0.05. This was associated with an increase in Schwann cell density (11,062 ± 2905 vs. 7561 ± 2715 cells/mm3, p < 0.01). Following excisional biopsy epidermal reinnervation increased monotonically at 30, 60 and 90 days; the regeneration rate was highest at 30 days, and decreased at 60 and 90 days. The reinnervation rate was highest among animals infected for 3mo vs those infected for 12mo or naïve animals (mean ± SD, 27.8 ± 7.2 vs.16.2 ± 5.8vs. 15.3 ± 6.5 mm/mm3, p < 0.05). The infected armadillos displayed a sustained Schwann cell proliferation across axotomy time points and duration of infection (3mo:182 ± 26, 12mo: 256 ± 126, naive: 139 ± 49 cells/day, p < 0.05). M. leprae infection is associated with sustained Schwann cell proliferation and distal limb nerve fiber loss. Rates of epidermal reinnervation were highest 3mo after infection and normalized by 12 mo of infection. We postulate that excess Schwann cell proliferation is the main pathogenic process and is deleterious to sensory axons. There is a compensatory initial increase in regeneration rates that may be an attempt to compensate for the injury, but it is not sustained and eventually followed by axon loss. Aberrant Schwann cell proliferation may be a novel therapeutic target to interrupt the pathogenic cascade of M. leprae. [Display omitted] • Long term Mycobacterium leprae infection produces axonal degeneration at the distal leg. • Axonal regeneration is initially increased but diminishes with longer term M. leprae infection. • M.leprae induces persistent Schwann cell proliferation that leads to axon loss. • Schwann cells may be a novel therapeutic target to interrupt M. leprae infection. [ABSTRACT FROM AUTHOR]

Background We sought to define the clinical and ultrastructure effects of ixabepilone (Ix), a microtubule-stabilizing chemotherapy agent on cutaneous sensory nerves and to investigate a potential mitochondrial toxicity mechanism. Methods Ten breast cancer patients receiving Ix underwent total neuropathy score clinical ( TNSc) assessment, distal leg skin biopsies at cycle (Cy) 3 (80-90 mg/m2), Cy5 (160-190 mg/m2), and Cy7 (>200 mg/m2) and were compared to 5 controls. Skin blocks were processed for EM and ultrastructural morphometry of Remak axons done. Results At baseline, Ix-treated subjects had higher TNSc values (4.5 ± 0.8 vs. 0.0 ± 0.0), greater percentage of empty (denervated) Schwann cells (29% vs. 12%), altered axonal diameter (422.9 ± 17 vs. 354.9 ± 14.8 nm, P = 0.01), and axon profiles without mitochondria tended to increase compared to control subjects (71% vs. 70%). With increasing cumulative Ix exposure, an increase in TNSc values (Cy3: 5.4 ± 1.2, Cy7: 10 ± 4, P < 0.001), empty Schwann cells (39% by Cy7), and dilated axons (in nm, Cy3: 506.3 ± 22.1, Cy5: 534.8 ± 33, Cy7: 527.8 ± 24.4; P < 0.001) was observed. In addition, axon profiles without mitochondria (Cy3:74%, Cy7:78%) and mitochondria with abnormal morphology (grade 3 or 4) increased from 24% to 79%. Schwann cells with atypical mitochondria and perineuronal macrophage infiltration in dermis were noted. Interpretation This study provides functional and structural evidence that Ix exposure induces a dose-dependent toxicity on small sensory fibers with an increase in TNSc scores and progressive axonal loss. Mitochondria appear to bear the cumulative toxic effect and chemotherapy-induced toxicity can be monitored through serial skin biopsy-based analysis. [ABSTRACT FROM AUTHOR]

Background: Glutamate excitotoxicity is thought to be involved in the pathogenesis of neurodegenerative disease. One potential source of glutamate is N-acetyl-aspartyl-glutamate (NAAG) which is hydrolyzed to glutamate and N-acetyl-aspartate (NAA) in a reaction catalyzed by glutamate carboxypeptidase (GCP). As a result, GCP inhibition is thought to be beneficial for the treatment of neurodegenerative diseases where excess glutamate is presumed pathogenic. Both pharmacological and genetic inhibition of GCP has shown therapeutic utility in preclinical models and this has led to GCP inhibitors being pursued for the treatment of nervous system disorders in human clinical trials. Specifically, GCP inhibitors are currently being developed for peripheral neuropathy and neuropathic pain. The purpose of this study was to develop a pharmacodynamic (PD) marker assay to use in clinical development. The PD marker will determine the effect of GCP inhibitors on GCP enzymatic activity in human skin as measure of inhibition in peripheral nerve and help predict drug doses required to elicit pharmacologic responses.Methods: GCP activity was first characterized in both human skin and rat paw pads. GCP activity was then monitored in both rodent paw pads and sciatic nerve from the same animals following peripheral administration of various doses of GCP inhibitor. Significant differences among measurements were determined using two-tailed distribution, equal variance student's t test.Results: We describe for the first time, a direct and quantifiable assay to evaluate GCP enzymatic activity in human skin biopsy samples. In addition, we show that GCP activity in skin is responsive to pharmacological manipulation; GCP activity in rodent paws was inhibited in a dose response manner following peripheral administration of a potent and selective GCP inhibitor. Inhibition of GCP activity in rat paw pads was shown to correlate to inhibition of GCP activity in peripheral nerve.Conclusion: Monitoring GCP activity in human skin after administration of GCP inhibitors could be readily used as PD marker in the clinical development of GCP inhibitors. Enzymatic activity provides a simple and direct measurement of GCP activity from tissue samples easily assessable in human subjects. [ABSTRACT FROM AUTHOR]

Summary: Nebulisers are a potential source of bacterial contamination in cystic fibrosis (CF) patients. The aims of the study were to survey patient practice regarding maintenance of home nebulisers and to assess the impact of standardised guidelines derived from a previous in-vitro study. In total, 42 CF patients were studied. During two consecutive home visits, a questionnaire regarding routine patient practice was completed by a nurse while sputum and equipment samples were taken for bacteriological analyses. The first visit took place at baseline, and the second followed the implementation of detailed instructions for cleaning and disinfecting the nebulisers using a 0.5% hypochlorite solution. The first visit identified a great diversity in routine patient practices. Commensal bacteria, environmental bacteria and potential CF pathogens contaminated 78.5%, 57.1% and 14.3% of nebulisers respectively. After hypochlorite disinfection, rate and degree of global contamination decreased significantly, but the number of CF pathogens was not affected. There was no concordance between CF pathogens isolated from patients'' sputum and their equipment. We conclude that in this sample of patients, initial routine practices were varied. With regard to CF pathogens, the superiority of a hypochlorite solution over a mix of other disinfection methods was not demonstrated. [Copyright &y& Elsevier]

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A total of 38 strains of Corynebacterium Group D2 isolated from clinical specimens in Belgian laboratories were characterized by pronounced urease activity, inability to acidify sugars and to reduce nitrates and multiresistance to antibiotics. Two strains were involved in clinical diseases. The organisms were found to have a more opportunistic than pathogenic behaviour. [ABSTRACT FROM AUTHOR]

All patients with leprosy have some degree of nerve involvement. Perineural inflammation is the histopathologic hallmark of leprosy, and this localization may reflect a vascular route of entry of Mycobacterium leprae into nerves. Once inside nerves, M leprae are ingested by Schwann cells, with a wide array of consequences. Axonal atrophy may occur early in this process; ultimately, affected nerves undergo segmental demyelination. Knowledge of the mechanisms of nerve injury in leprosy has been greatly limited by the minimal opportunities to study affected nerves in man. The nine-banded armadillo provides the only animal model of the pathogenesis of M leprae infection. New tools available for this model enable the study and correlation of events occurring in epidermal nerve fibers, dermal nerves, and nerve trunks, including neurophysiologic parameters, bacterial load, and changes in gene transcription in both neural and inflammatory cells. The armadillo model is likely to enhance understanding of the mechanisms of nerve injury in leprosy and offers a means of testing proposed interventions. [ABSTRACT FROM AUTHOR]