Phenotypes Associated With the Val122Ile, Leu58His, and Late-Onset Val30Met Variants in Patients With Hereditary Transthyretin Amyloidosis.

BACKGROUND AND OBJECTIVES: Hereditary transthyretin amyloidosis (hATTR) is a rare autosomal dominant systemic disease with variable penetrance and heterogeneous clinical presentation. Several effective treatments can reduce mortality and disability, though diagnosis remains challenging, especially in the United States where disease is nonendemic. Our aim is to describe the neurologic and cardiac characteristics of common US ATTR variants V122I, L58H, and late-onset V30M at presentation. METHODS: We conducted a retrospective case series of patients with a new diagnosis of ATTRv between January 2008 and January 2020 to characterize features of prominent US variants. The neurologic (examination, EMG, and skin biopsy), cardiac (echo), and laboratory assessments (pro b-type natriuretic peptide [proBNP] and reversible neuropathy screens) are described. RESULTS: A total of 56 patients with treatment-naïve ATTRv with symptoms/signs of peripheral neuropathy (PN) or cardiomyopathy and confirmatory genetic testing presenting with Val122Ile (N = 31), late-onset Val30Met (N = 12), and Leu58His ATTRv (N = 13) were included. The age at onset and sex distributions were similar (V122I: 71.5 ± 8.0, V30M: 64.8 ± 2.6, and L58H: 62.4 ± 9.8 years; 26, 25, 31% female). Only 10% of patients with V122I and 17% of patients with V30M were aware of an ATTRv family history, while 69% of patients with L58H were aware. PN was present in all 3 variants at diagnosis (90%, 100%, and 100%), though neurologic impairment scores differed: V122I: 22 ± 16, V30M: 61 ± 31, and L58H: 57 ± 25. Most points (deficits) were attributed to loss of strength. Carpal tunnel syndrome (CTS) and a positive Romberg sign were common across all groups (V122I: 97%, 39%; V30M: 58%, 58%; and L58H: 77%, 77%). ProBNP levels and interventricular septum thickness were highest among patients with V122I (5,939 ± 962 pg/mL, 1.70 ± 0.29 cm), followed by V30M (796 ± 970 pg/mL, 1.42 ± 0.38 cm) and L58H (404 ± 677 pg/mL, 1.23 ± 0.36 cm). Atrial fibrillation was present among 39% of cases with V122I and only 8% of cases with V30M and L58H. Gastrointestinal symptoms were rare (6%) among patients with V122I and common in patients with V30M (42%) and L58H (54%). DISCUSSION: Important clinical differences exist between ATTRv genotypes. While V122I is perceived to be a cardiac disease, PN is common and clinically relevant. Most patients with V30M and V122I were diagnosed de novo and therefore require clinical suspicion for diagnosis. A history of CTS and a positive Romberg sign are helpful diagnostic clues.

The Armadillo as a Model for Leprosy Nerve Function Impairment: Preventative and Therapeutic Interventions.

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.

Mycobacterium leprae induces Schwann cell proliferation and migration in a denervated milieu following intracutaneous excision axotomy in nine-banded armadillos.

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.

Treatment and Evaluation Advances in Leprosy Neuropathy.

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.

Intraepidermal Nerve Fiber Analysis in Human Patients and Animal Models of Peripheral Neuropathy: A Comparative Review.

Analysis of intraepidermal nerve fibers (IENFs) in skin biopsy samples has become a standard clinical tool for diagnosing peripheral neuropathies in human patients. Compared to sural nerve biopsy, skin biopsy is safer, less invasive, and can be performed repeatedly to facilitate longitudinal assessment. Intraepidermal nerve fiber analysis is also more sensitive than conventional nerve histology or electrophysiological tests for detecting damage to small-diameter sensory nerve fibers. The techniques used for IENF analysis in humans have been adapted for large and small animal models and successfully used in studies of diabetic neuropathy, chemotherapy-induced peripheral neuropathy, HIV-associated sensory neuropathy, among others. Although IENF analysis has yet to become a routine end point in nonclinical safety testing, it has the potential to serve as a highly relevant indicator of sensory nerve fiber status in neurotoxicity studies, as well as development of neuroprotective and neuroregenerative therapies. Recently, there is also interest in the evaluation of IENF via skin biopsy as a biomarker of small fiber neuropathy in the regulatory setting. This article provides an overview of the anatomic and pathophysiologic principles behind IENF analysis, its use as a diagnostic tool in humans, and applications in animal models with focus on comparative methodology and considerations for study design.

Erratum: Author Correction: LepVax, a defined subunit vaccine that provides effective pre-exposure and post-exposure prophylaxis of M. leprae infection.

[This corrects the article DOI: 10.1038/s41541-018-0050-z.].

LepVax, a defined subunit vaccine that provides effective pre-exposure and post-exposure prophylaxis of M. leprae infection.

Sustained elimination of leprosy as a global health concern likely requires a vaccine. The current standard, BCG, confers only partial protection and precipitates paucibacillary (PB) disease in some instances. When injected into mice with the T helper 1 (Th1)-biasing adjuvant formulation Glucopyranosyl Lipid Adjuvant in stable emulsion (GLA-SE), a cocktail of three prioritized antigens (ML2055, ML2380 and ML2028) reduced M. leprae infection levels. Recognition and protective efficacy of a single chimeric fusion protein incorporating these antigens, LEP-F1, was confirmed in similar experiments. The impact of post-exposure immunization was then assessed in nine-banded armadillos that demonstrate a functional recapitulation of leprosy. Armadillos were infected with M. leprae 1 month before the initiation of post-exposure prophylaxis. While BCG precipitated motor nerve conduction abnormalities more rapidly and severely than observed for control infected armadillos, motor nerve injury in armadillos treated three times, at monthly intervals with LepVax was appreciably delayed. Biopsy of cutaneous nerves indicated that epidermal nerve fiber density was not significantly altered in M. leprae-infected animals although Remak Schwann cells of the cutaneous nerves in the distal leg were denser in the infected armadillos. Importantly, LepVax immunization did not exacerbate cutaneous nerve involvement due to M. leprae infection, indicating its safe use. There was no intraneural inflammation but a reduction of intra axonal edema suggested that LepVax treatment might restore some early sensory axonal function. These data indicate that post-exposure prophylaxis with LepVax not only appears safe but, unlike BCG, alleviates and delays the neurologic disruptions caused by M. leprae infection.

Cutaneous nerve biomarkers in transthyretin familial amyloid polyneuropathy.

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.

Tracking Epidermal Nerve Fiber Changes in Asian Macaques: Tools and Techniques for Quantitative Assessment.

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.

Persistent Peripheral Nervous System Damage in Simian Immunodeficiency Virus-Infected Macaques Receiving Antiretroviral Therapy.

Human immunodeficiency virus (HIV)-induced peripheral neuropathy is the most common neurologic complication associated with HIV infection. In addition to virus-mediated injury of the peripheral nervous system (PNS), treatment of HIV infection with combination antiretroviral therapy (cART) may induce toxic neuropathy as a side effect. Antiretroviral toxic neuropathy is clinically indistinguishable from the sensory neuropathy induced by HIV; in some patients, these 2 processes are likely superimposed. To study these intercurrent PNS disease processes, we first established a simian immunodeficiency virus (SIV)/pigtailed macaque model in which more than 90% of animals developed PNS changes closely resembling those seen in HIV-infected individuals with distal sensory neuropathy. To determine whether cART alters the progression of SIV-induced PNS damage, dorsal root ganglia and epidermal nerve fibers were evaluated in SIV-infected macaques after long-term suppressive cART. Although cART effectively suppressed SIV replication and reduced macrophage activation in the dorsal root ganglia, PGP 9.5 immunostaining and measurements of epidermal nerve fibers in the plantar surface of the feet of treated SIV-infected macaques clearly showed that cART did not normalize epidermal nerve fiber density. These findings illustrate that significant PNS damage persists in SIV-infected macaques on suppressive cART.

Distal leg epidermal nerve fiber density as a surrogate marker of HIV-associated sensory neuropathy risk: risk factors and change following initial antiretroviral therapy.

Distal leg epidermal nerve fiber density (ENFD) is a validated predictor of HIV sensory neuropathy (SN) risk. We assessed how ENFD is impacted by initiation of first-time antiretroviral therapy (ART) in subjects free of neuropathy and how it is altered when mitochondrial toxic nucleoside medications are used as part of ART. Serial changes in proximal thigh and distal leg ENFD were examined over 72 weeks in 150 Thai subjects randomized to a regimen of stavudine (d4T) switching to zidovudine (ZDV) at 24 weeks vs ZDV vs tenofovir (TDF) for the entire duration of study, all given in combination with nevirapine. We found individual variations in ENFD change, with almost equal number of subjects who decreased or increased their distal leg ENFD over 72 weeks and no relationship to nucleoside backbone or to development of neuropathic signs or symptoms. Lower baseline distal leg ENFD and greater increases in mitochondrial oxidative phosphorylation complex I (CI) activity were associated with larger increases in distal leg ENFD over 72 weeks. Distal leg ENFD correlated with body composition parameters (body surface area, body mass index, height) as well as with blood pressure measurements. Assessed together with a companion cross-sectional study, we found that mean distal leg ENFD in all HIV+ subjects was lower than in HIV- subjects but similar among HIV+ groups whether ART-naïve or on d4T with/without neuropathy/neuropathic symptoms. The utility of ENFD as a useful predictor of small unmyelinated nerve fiber damage and neuropathy risk in HIV may be limited in certain populations.

Factors influencing sweat gland innervation in diabetes.

BACKGROUND: Using a stereologic approach, the density of nerve fibers innervating sweat gland (SG) fragments in patients with diabetes mellitus (DM) and healthy controls using protein gene product (PGP), tyrosine hydroxylase (TH), and vasoactive intestinal peptide (VIP) was measured to determine which marker best detected differences between the groups. Factors associated with SG nerve fiber (SGNF) innervation were assessed and the change in SG innervation over a 1-year time period was determined. METHODS: Ninety-two control subjects and 2 groups of subjects with DM totaling 97 were assessed in this cross-sectional study. Intraepidermal nerve fiber density and SG innervation were determined from leg skin biopsies that were immunohistochemically stained for ubiquitin hydrolase, VIP, and TH. Factors associated with SG innervation were assessed and 15 subjects were longitudinally followed for 1 year. RESULTS: SGNF innervation was reduced in subjects with DM compared with controls. Lower SG innervation values were associated with increasing glycated hemoglobin A1c, body mass index (BMI), men compared with women, and tobacco use, but not diabetes type or age. Sex, A1c, and BMI remained significant in multivariate modeling. SG innervation measured by VIP+ fibers is a more sensitive marker for neuropathy than either PGP or TH. Fifteen subjects with DM followed for 1 year showed a significant decrease in SGNF innervation but not intraepidermal nerve fiber density. CONCLUSIONS: Stereologic measurement of SG innervation is feasible to assess postganglionic autonomic nerve fiber densities. SG innervation was reduced in subjects with DM compared with control subjects and was associated with sex, A1c, and BMI in multivariate modeling. VIP+ SGNF is more severely reduced in DM than TH+ or PGP9.5+-based assessments. Progression of diabetic polyneuropathy was detected by SGNF over a 1-year time period.

Mechanisms of nerve injury in leprosy.

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.

Mechanisms of nerve injury in leprosy

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.

Ixabepilone-induced mitochondria and sensory axon loss in breast cancer patients.

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/m(2)), Cy5 (160-190 mg/m(2)), and Cy7 (>200 mg/m(2)) 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.

Epidermal innervation in diabetes.

The skin is innervated by small sensory and autonomic fibers. In the epidermis, sensory fibers are present as unmyelinated C fibers that terminate as free nerve endings. The determination of epidermal nerve fiber (ENF) density using the immunohistochemical method is a powerful tool that provides insight into a population of nerve fibers that is prominently altered in small fiber neuropathy. The superficial location of epidermal nerve fibers allows repeated sampling of these nerves in a relatively noninvasive fashion, and in sites that cannot be assessed through conventional electrodiagnostic techniques. These features have allowed investigators to diagnose diabetic neuropathy earlier in the course of disease. ENF density holds promise as a biomarker for neuropathic pain and is a sensitive indicator of neuropathic progression. Finally, the ability to injure these fibers in a standardized fashion has led to novel measures of human axonal regeneration that may provide a more sensitive ruler by which to assess promising regenerative compounds in clinical trials.

Epidermal nerve fiber density, oxidative stress, and mitochondrial haplogroups in HIV-infected Thais initiating therapy.

OBJECTIVE: We explored associations between mitochondrial DNA (mtDNA) haplogroups, epidermal nerve fiber density (ENFD), and HIV-associated sensory neuropathy (HIV-SN) in a randomized trial of Thai patients initiating antiretroviral therapy (ART). DESIGN: The South East Asia Research Collaboration with Hawaii 003 study evaluated toxicity of nucleoside reverse transcriptase inhibitors (stavudine vs. zidovudine vs. tenofovir). We present secondary analyses of mtDNA haplogroups and ENFD changes. METHODS: ENFD, peripheral blood mononuclear cell mitochondrial complex I and IV, and 8-oxo-deoxyguanine (8-oxo-dG) were quantified. Peripheral blood mononuclear cell mtDNA sequences were obtained for haplogroup determination. Multivariate regression of ENFD change was performed. RESULTS: Paired ENFD was available from 118 patients. Median age, CD4 cell count, and height at entry were 34 years, 172 cells/µl, and 162 cm, respectively. Major haplogroups included M (42%), F (21%), and B (16%). Baseline ENFD, CD4 cell count, randomized ART, and biomarkers did not differ by haplogroup. Haplogroup B patients were older (P=0.02) at baseline, and had an increase in median ENFD (+1.5 vs. -2.9 fibers/mm; P=0.03) and 8-oxo-dG break frequency (+0.05 vs. 0.00; P=0.05) compared to other haplogroups. In a multivariate model, haplogroup B was associated with increased ENFD (ß=3.5, P=0.009) at week 24, whereas older age (P=0.02), higher baseline CD4 cell count, (P=0.03), higher complex I level (P=0.03), and higher ENFD (P<0.001) at baseline were all associated with decreased ENFD. Three of the six HIV-SN cases were haplogroup B (P=0.05). CONCLUSIONS: Thai persons belonging to mtDNA haplogroup B had increased ENFD and 8-oxo-dG on ART, and were more likely to develop HIV-SN. These results suggest that mtDNA variation influences early oxidative damage and ENFD changes.

The armadillo as a model for peripheral neuropathy in leprosy.

Leprosy (also known as Hansen's Disease) is a chronic infectious disease caused by Mycobacterium leprae that primarily targets the peripheral nervous system; skin, muscle, and other tissues are also affected. Other than humans, nine-banded armadillos (Dasypus novemcinctus) are the only natural hosts of M. leprae, and they are the only laboratory animals that develop extensive neurological involvement with this bacterium. Infection in the armadillo closely recapitulates many of the structural, physiological, and functional aspects of leprosy seen in humans. Armadillos can be useful models of leprosy for basic scientific investigations into the pathogenesis of leprosy neuropathy and its associated myopathies, as well as for translational research studies in piloting new diagnostic methods or therapeutic interventions. Practical and ethical constraints often limit investigation into human neuropathies, but armadillos are an abundant source of leprotic neurologic fibers. Studies with these animals may provide new insights into the mechanisms involved in leprosy that also might benefit the understanding of other demyelinating neuropathies. Although there is only a limited supply of armadillo-specific reagents, the armadillo whole genomic sequence has been completed, and gene expression studies can be employed. Clinical procedures, such as electrophysiological nerve conduction testing, provide a functional assessment of armadillo nerves. A variety of standard histopathological and immunopathological procedures including Epidermal Nerve Fiber Density (ENFD) analysis, Schwann Cell Density, and analysis for other conserved cellular markers can be used effectively with armadillos and will be briefly reviewed in this text.