Study of the profile of the neurotrophin BDNF in new leprosy cases before, during and after multidrug therapy

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.

The International Classification of Functioning, Disability and Health to map leprosy-related disability in rural and remote areas in Indonesia

The International Classification of Function, Disability, and Health (ICF-WHO, 2001) recognizes several dimensions of disability, such as body structure and function (and impairment thereof), activity (and activity restrictions) and participation (and participation restriction) and their interactions with contextual factor (personal and environmental). In this study, we map and analyse the relationship between the components of ICF in leprosy patients from two rural areas in Indonesia: Lewoleba (East Nusa Tenggara) and Likupang (North Minahasa). This study was part of a community outreach program by the KATAMATAKU team from Universitas Indonesia. The body structure was graded using the WHO hand and feet disability grade and the number of enlarged nerves, while the body function was measured by the Jebsen Taylor Hand Function Test (JTT) and Timed-up and Go (TUG). Activity limitation and participation restriction were measured using the Screening Activity Limitation Safety Awareness (SALSA) Scale and Participation Scale (P-scale), respectively. There were 177 leprosy patients from the two regions and 150 patients with complete data were included in the analysis. We found 82% (95% CI: 75.08%-87.32%) of subjects with multibacillary leprosy, 10.67% (95% CI: 6.67%-16.62%) of subjects with grade 2 WHO hand disability, and 9.33% (95% CI: 5.64%-15.06%) of subjects with grade 2 WHO foot disability. Assessment using the SALSA Scale showed 29.33% of subjects with limitation activity and 11.33% with participation restriction. Age was shown to have positive correlations with SALSA, JTT, and TUG. Inter-dimensional analysis showed that the SALSA scale had significant positive correlations with the number of nerve enlargements, P-scale, JTT, and TUG. SALSA scores of grade 2 WHO hand and foot disability were also significantly higher than grades 1 and 0. The participation scale also had a positive correlation with JTT but not TUG. Hand disability seemed to affect societal participation while foot did not. We used the ICF to describe and analyse dimensions of leprosy-related disability in Indonesia.

Effect of Mycobacterium leprae on neurotrophins expression in human Schwann cells and mouse sciatic nerves

BACKGROUND

Although Mycobacterium leprae (ML) is well characterised as the causative agent of leprosy, the pathophysiological mechanisms underlying peripheral nerve damage still need further understanding. In vitro and in vivo studies have yielded insights into molecular mechanisms of ML interaction with Schwann cells (SC), indicating the regulation of genes and proteins crucial to neural plasticity.

OBJECTIVES

We aimed to investigate the effect of ML on neurotrophins expression in human SC (hSC) and mice sciatic nerves to better understand their role in leprosy neuropathy, and aiming to contribute to future therapeutic approaches.

METHODS

We evaluated mRNA and protein expression of BDNF, NGF, NT-3, NT-4 in hSC from amputation nerve fragments, as well as in athymic nude mice, infected by ML for eight months.

FINDINGS AND MAIN CONCLUSIONS

Our in vitro results showed a trend to decline in NGF and BDNF mRNA in ML-treated hSC, compared to controls. The immunodetection of BDNF and NT-4 was significantly downregulated in ML-treated hSC. Conversely, ML-infected mice demonstrated upregulation of NT-3, compared to non-infected animals. Our findings indicate that ML may be involved in neurotrophins regulation, suggesting that a pathogen-related imbalance of these growth factors may have a role in the neural impairment of leprosy.

Limitation of activity and restriction of social participation in relation to age range, gender, and education in people with leprosy

Background

In Brazil, 38,000 new cases of leprosy are discovered each year, making it a public health problem.

Objective

To identify whether or not there is an association between activity limitations and the restriction of social participation with some demographic data (age range, gender, and education) of the patients in a Basic Health Unit (BHU), diagnosed with leprosy.

Methods

The SALSA scale was used to assess activity limitations, whereas the Participation scale was used to assess the restriction of social participation.

Results

The assessments were conducted with 31 BHU patients diagnosed with leprosy. Males were the most affected by leprosy, the multibacillary was the most prevalent, and education proved to be an important factor when related to the disease injuries among the evaluated individuals. Regarding activity limitations and the restriction of social participation, the percentage of individuals without limitations and without restrictions was greater in both scales.

Study limitations

The main limitation is the small study sample.

Conclusion

It can be concluded that, for the studied sample, no association was observed between the activity limitations, evaluated by the Salsa scale, nor the restriction of social participation, evaluated by the Participation Scale, with the analyzed demographic data.

Leprosy patients: neurotrophic factors and axonal markers in skin lesions

Neurotrophins are growth factors with crucial roles in neural pathophysiology. These mediators functionally modulate nociceptive fibers, and changes in neurotrophins expression have been correlated with early loss of nociception in leprosy. This study investigated the expression of NGF, BDNF, and NT3 in dermal nerves of leprosy patients. Characterization of Remak bundles was achieved by p75(NTR), and axonal markers NF-L and PGP 9.5 immunostaining. Clinical parameters of neural impairment have been evaluated by Semmes-Wenstein monofilaments. Our findings demonstrated decrease of NGF in borderline leprosy, when compared to control specimens. Similar results were observed in PGP 9.5 expression (borderline: p<0.001 and lepromatous: p<0.05) and NF-L (lepromatous: p<0.05), suggesting advanced Remak bundles degeneration in multibacillary leprosy. It has also been observed positive correlation between p75(NTR) and PGP 9.5, indicating association between Schwann cells and axons in Remak bundles. Present data indicate that neurotrophins imbalance may participate in the establishment of peripheral nerve damage.