Leprosy patients: neurotrophic factors and axonal markers in skin lesions

The role of neurotrophin polymorphisms and susceptibility to neural damage in leprosy

OBJECTIVES

Mycobacterium leprae is able to infect Schwann cells leading to neural damage. Neurotrophins are involved in nervous system plasticity and impact neural integrity during diseases. Investigate the association between single nucleotide polymorphisms in neurotrophin genes and leprosy phenotypes, especially neural damage.

DESIGN

We selected single nucleotide polymorphisms in neurotrophins or their receptors genes associated with neural disorders: rs6265 and rs11030099 of brain-derived neurotrophic factor (BDNF), rs6330 of BDNF, rs6332 in NT3 and rs2072446 of P75NTR. The association of genetic frequencies with leprosy phenotypes was investigated in a case-control study.

RESULTS

An association of the BDNF single nucleotide polymorphism rs11030099 with the number of affected nerves was demonstrated. The "AA+AC" genotypes were demonstrated to be protective against nerve impairment. However, this variation does not affect BDNF serum levels. BDNF is an important factor for myelination of Schwann cells and polymorphisms in this gene can be associated with leprosy outcome. Moreover, rs11030099 is located in the binding region for micro-RNA (miRNA) 26a that could be involved in control of BDNF expression. We demonstrated different expression levels of this miRNA in polar forms of leprosy.

CONCLUSION

Our findings demonstrate for the first time an association between the polymorphism rs11030099 in the BDNF gene and neural commitment in leprosy and may indicate a possible role of miRNA-26a acting synergistically to these genetic variants in neural damage development.

Cyclosporin A as an Alternative Neuroimmune Strategy to Control Neurites and Recover Neuronal Tissues in Leprosy

Leprosy, also known as Hansen's disease, continues to have a substantial impact on infectious diseases throughout the world. Leprosy is a chronic granulomatous infection caused by Mycobacterium leprae and shows a wide clinical and immunopathological spectrum related to the immune response of the host. This disease affects the skin and other internal organs with a predilection to infect Schwann cells, which play an active role during axonal degeneration, affecting peripheral nerves and promoting neurological damage. This chronic inflammation influences immune function, leading to neuroimmune disorders. Leprosy is also associated with neuroimmune reactions, including type 1 (reverse) and type 2 (erythema nodosum leprosum) reactions, which are immune-mediated inflammatory complications that can occur during the disease and appear to worsen dramatically; these complications are the main concerns of patients. The reactions may induce neuritis and neuropathic pain that progressively worsen with irreversible deformity and disabilities responsible for the immunopathological damage and glial/neuronal death. However, the neuronal damage is not always associated with the reactional episode. Also, the efficacy in the treatment of reactions remains low because of the nonexistence of a specific treatment and missing informations about the immunopathogenesis of the reactional episode. There is increasing evidence that peripheral neuron dysfunction strongly depends on the activity of neurotrophins. The most important neurotrophin in leprosy is nerve growth factor (NGF), which is decreased in the course of leprosy, as well as the presence of autoantibodies against NGF in all clinical forms of leprosy and neuroimmune reactions. The levels of autoantibodies against NGF are decreased by the immunomodulatory activity of cyclosporin A, which mainly controls pain and improves motor function and sensitivity. Therefore, the suppression of anti-NGF and the regulation of NGF levels can be attractive targets for immunomodulatory treatment and for controlling the neuroimmune reactions of leprosy, although further studies are needed to clarify this point.

Evaluation of nerve growth factor serum level for early detection of leprosy disability

Introduction

this research aimed to analyze nerve growth factor (NGF) contents as diagnostic tools for early disability in leprosy patients and the cut-off point value.

Methods

research samples consisted of 79 leprosy patients with disability grade 0 or 1 who met the clinically approved inclusion criteria. The age of patients ranged from 14 to 50 years. For both sample groups, blood serum was collected to determine NGF concentration. NGF level was analyzed by enzyme-linked immunosorbent assay (ELISA) according to the manual guide of the kit insert from Cussabio®. Statistical analysis used SPSS 17 software for Windows. A comparison was performed with the Student's t-test and the NGF concentration cut-off point was determined using a receiver operating characteristic (ROC) curve.

Results

the research result demonstrated that NGF concentration in multibacillary leprosy with disability grade 0 was higher than in grade 1. Leprosy with disability grade 0 had an NGF content reaching 100.46 pg/mL, while those with grade 1 had a lower concentration of NGF at 30.56 pg/mL. The higher disability grade indicated a lower NGF concentration in the blood serum. Based on the ROC analysis result, the NGF cut-off was shown to be 81.43 pg/mL. This result indicated that low NGF in nerve and skin lesions of leprosy patients contributes to early peripheral nerve malfunction due to Mycobacterium leprae infection.

Conclusion

these results prove that NGF can be used as a marker of early disability in leprosy, with the cut-off value at 81.43 pg/mL.

The Correlation of Semmes-Weinstein Monofilament Test with the Level of P-75 Neurotrophin as Marker of Nerve Damage in Leprosy

Introduction

Leprosy is a chronic infectious disease caused by Mycobacterium leprae that causes damage to the peripheral nerve, particularly Schwann cells. Treatment is useful only to kill bacteria but not to recover peripheral nerve damage. However, early detection of peripheral nerve damage is necessary. We examine P-75 neurotrophin (P75^NTR) as an indicator of peripheral nerve damage in leprosy with the Semmes–Weinstein monofilament (SWM) test as the comparison.

Methods

This study uses a quantitative analytic observational study approach with cross-sectional design, conducted at Kediri Leprosy Hospital, Malang, East Java, Indonesia. All leprosy patients had a clinical examination and bacterial index to classify leprosy and then the SWM test to examine the presence of neuropathy in the palms and feet. P75^NTR examination uses venous blood samples. An independent t-test was used to compare the SWM and P75^NTR scores based on the type of leprosy, and then the Spearman correlation test was used to determine the correlation between SWM scores and P75^NTR levels.

Results

In this study, SWM scores on the soles of the foot and palms and the P75^NTR levels were higher in the PB group compared with MB (p<0.05). Also, a significant positive correlation was found between P75^NTR and the SWM scores on the palms of the hand (r=0.864; p=0.000) and the soles of the foot (r=0.864; p=0.000).

Conclusion

There is a strong positive correlation between P75^NTR levels and SWM scores, so P75^NTR levels are very likely to be a marker of neuropathy in leprosy, but further studies are still needed to examine the specific role of these biomarkers.

An inducible Cre mouse line to sparsely target nervous system cells, including Remak Schwann cells

Nerves of the peripheral nervous system contain two classes of Schwann cells: myelinating Schwann cells that ensheath large caliber axons and generate the myelin sheath, and Remak Schwann cells that surround smaller axons and do not myelinate. While tools exist for genetic targeting of Schwann cell precursors and myelinating Schwann cells, such reagents have been challenging to generate specifically for the Remak population, in part because many of the genes that mark this population in maturity are also robustly expressed in Schwann cell precursors. To circumvent this challenge, we utilized BAC transgenesis to generate a mouse line expressing a tamoxifen-inducible Cre under the control of a Remak-expressed gene promoter (Egr1). However, as Egr1 is also an activity dependent gene expressed by some neurons, we flanked this Cre by flippase (Flpe) recognition sites, and coinjected a BAC expressing Flpe under control of a pan-neuronal Snap25 promoter to excise the Cre transgene from these neuronal cells. Genotyping and inheritance demonstrate that the two BACs co-integrated into a single locus, facilitating maintenance of the line. Anatomical studies following a cross to a reporter line show sparse tamoxifen-dependent recombination in Remak Schwann cells within the mature sciatic nerve. However, depletion of neuronal Cre activity by Flpe is partial, with some neurons and astrocytes also showing evidence of Cre reporter activity in the central nervous system. Thus, this mouse line will be useful in mosaic loss-of-function studies, lineage tracing studies following injury, live cell imaging studies, or other experiments benefiting from sparse labeling.

Botulinum toxin type A in chronic neuropathic pain in refractory leprosy

OBJECTIVE

Neuropathic pain is a chronic syndrome that is difficult to treat and often affects patients with leprosy. Recommended treatment includes the the use of analgesic drugs, codeine, tricyclic antidepressants, neuroleptics, anticonvulsants and thalidomide, but without consensus on uniform dose and fully satisfactory results. To analyze botulinum toxin type A (BoNT-A) effectiveness in treatment of chronic neuropathic pain in refractory leprous patients, as well as evaluate and compare the quality of life of patients before and after using the medication.

METHODS

We used a specific protocol including clinical, demographic, DN4 protocol, analogue scale (VAS), sensory evaluation and evaluation of the WHOQOL-BREF. Therapeutic intervention was performed with BOTOX® BTX-A 100U administered subcutaneously. Fifteen patients were evaluated on days 0, 10 and 60.

RESULTS

Patients on VAS showed pain between 5 and 10, in one case there was complete pain relief in 60 days, while others showed improvement in the first week with the return of symptoms with less intensity after this period. WHOQOL-BREF's domains Quality of Life and Physical to have a significant increase in QOL.

CONCLUSION

BoNT-A proved to be a good therapeutic option in relieving pain with improved quality of life for these patients.

Mycobacterium leprae-induced nerve damage: direct and indirect mechanisms

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. This disease is characterized by skin and peripheral nerve trunk damage. The mechanisms responsible for the observed nerve damage in leprosy could be directly related to the ability of M. leprae to infect Schwann cells, leading to triggering of signaling events. Therefore, we hypothesize that in response to M. leprae infection, activation of the Notch signaling pathway in Schwann cells could play a crucial role in glial cell dedifferentiation. On the other hand, nerve damage evidenced in this disease may be additionally explained by indirect mechanisms such as the immune response and genetic susceptibility of the host. The understanding of the mechanisms leading to nerve damage induced by M. leprae infection will allow us to generate valuable tools for the early detection of leprosy as well as for the mitigation of the effects of this disabling disease.

Correlation between nerve growth factor and tissue expression of IL-17 in leprosy

Leprosy is a serious public health problem in peripheral and developing countries. Leprosy is a chronic infectious-contagious disease caused by the intracellular, bacillus Mycobacterium leprae, which causes tissue damage and demyelination of peripheral nerves. Recent studies have demonstrated the participation of new subtype's cytokines profile in the inflammatory response of leprosy. Since nerve functions are affected by inflammatory response during the course of leprosy, changes in the production of NGF and its receptor (NGF R) may be directly associated with disability and sensory loss. Skin biopsies were collected and submitted to immunohistochemistry using specific antibodies to IL-17, NGF and NGF R. Quantitative analysis of NGF, NGFR and IL-17 immunostaining showed a significant difference between the clinical forms, with higher expression of NGF and NGFR in lepromatous leprosy and IL-17 in tuberculoid leprosy. The present study showed that IL-17, in addition to stimulating an inflammatory response, negatively regulates the action of NGF and NGF R in the polar forms of the disease.