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Introduction: Leprosy is an infectious disease caused by Mycobacterium leprae , a debilitating disease that affects the skin and peripheral nerves. It is possible that tissue changes during infection with leprosy are related to alterations in the activity of the Notch signaling pathway, an innate signaling pathway in the physiology of the skin and peripheral nerves. Methods: This is a descriptive observational study. Thirty skin biopsies from leprosy patients and 15 from individuals with no history of this disease were evaluated. In these samples, gene expressions of cellular components associated with the Notch signaling pathway, Hes-1, Hey-1, Runx-1 Jagged-1, Notch-1 , and Numb , were evaluated using q-PCR, and protein expression was evaluated using immunohistochemistry of Runx-1 and Hes-1. Results: Changes were observed in the transcription of Notch signaling pathway components; Hes-1 was downregulated and Runx-1 upregulated in the skin of infected patients. These results were confirmed by immunohistochemistry, where reduction of Hes-1 expression was found in the epidermis, eccrine glands, and hair follicles. Increased expression of Runx-1 was found in inflammatory cells in the dermis of infected patients; however, it is not related to tissue changes. With these results, a multivariate analysis was performed to determine the causes of transcription factor Hes-1 reduction. It was concluded that tissue inflammation was the main cause. Conclusions: The tissue changes found in the skin of infected patients could be associated with a reduction in the expression of Hes-1, a situation that would promote the survival and proliferation of M. leprae in this tissue., (Copyright © 2020 Serrano-Coll, Ospina, Salazar-Peláez and Cardona-Castro.)

Background: Since macrophages are one of the major cell types involved in the Mycobacterium leprae immune response, roles of the M1 and M2 macrophage subpopulations have been well defined. However, the role of M4 macrophages in leprosy or other infectious diseases caused by mycobacteria has not yet been clearly characterized. This study aimed to investigate the presence and potential role of M4 macrophages in the immunopathology of leprosy., Methods: We analyzed the presence of M4 macrophage markers (CD68, MRP8, MMP7, IL-6, and TNF-α) in 33 leprosy skin lesion samples from 18 patients with tuberculoid leprosy and 15 with lepromatous leprosy by immunohistochemistry., Results: The M4 phenotype was more strongly expressed in patients with the lepromatous form of the disease, indicating that this subpopulation is less effective in the elimination of the bacillus and consequently is associated with the evolution to one of the multibacillary clinical forms of infection., Conclusion: M4 macrophages are one of the cell types involved in the microbial response to M. leprae and probably are less effective in controlling bacillus replication, contributing to the evolution to the lepromatous form of the disease.

Leprosy is a chronic infectious disease that requires better understanding since it continues to be a significant health problem in many parts of the world. Leprosy reactions are acute inflammatory episodes regarded as the central etiology of nerve damage in the disease. The activation of endothelium is a relevant phenomenon to be investigated in leprosy reactions. The present study evaluated the expression of endothelial factors in skin lesions and serum samples of leprosy patients. Immunohistochemical analysis of skin samples and serum measurements of VCAM-1, VEGF, tissue factor and thrombomodulin were performed in 77 leprosy patients and 12 controls. We observed significant increase of VCAM-1 circulating levels in non-reactional leprosy (p = 0.0009). The immunostaining of VEGF and tissue factor was higher in endothelium of non-reactional leprosy (p = 0.02 for both) than healthy controls. Patients with type 1 reaction presented increased thrombomodulin serum levels, compared with non-reactional leprosy (p = 0.02). In type 2 reaction, no significant modifications were observed for the endothelial factors investigated. The anti-inflammatory and antimicrobial activities of the endotfhelial factors may play key-roles in the pathogenesis of leprosy and should be enrolled in studies focusing on alternative targets to improve the management of leprosy and its reactions.

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.

Background: Oxidative stress (OS) results from an imbalance between free radical generating and scavenging systems. The end product of lipid peroxidation, malondialdehyde (MDA) serves as a marker of cellular damage. Superoxide dismutase (SOD) traps free radicals and acts as a free radical scavenging system., Objective: To study OS indices in paucibacillary (PB) and multibacillary (MB) leprosy in tissues and blood., Materials and Methods: The study group comprised untreated PB patients (n = 14), untreated MB patients (n = 18) and normal human volunteers (n = 20). SOD activity, MDA level and MDA/SOD ratio were estimated in both blood and tissue., Results: Compared with controls, SOD activity in tissues decreased significantly in both PB and MB patients, while SOD activity in erythrocytes decreased significantly only in MB. In addition, MDA levels increased significantly in tissues of both PB and MB patients. Moreover, the mean level of MDA in plasma of MB patients was significantly higher, whereas there was no significant difference in that of PB patients. This study showed significant increase in OS index (MDA/SOD ratio) in tissue of PB and MB patients and in blood of MB patients only, whereas there was no significant difference in OS index in blood of PB patients compared with that in the controls., Conclusion: Oxidative stress was observed in both tissues and blood of MB patients and in tissues of PB patients, denoting its crucial involvement in the pathogenesis of leprosy. This can constitute an important tool in prognosis, treatment and control of leprosy.

Background and Objectives: Leprosy involves both the skin and peripheral nervous system. Leprosy patients display an increased incidence of xerosis and altered sensory thresholds, which persist in previously active skin sites. We assessed here whether alterations in stratum corneum (SC) function persist in cured leprosy, and the relationship of epidermal functional abnormalities to each clinical subtype of leprosy., Methods: A total of 43 cured leprosy subjects and 29 normal control subjects were enrolled in this study. Basal skin surface pH, SC hydration, permeability barrier function as well as barrier recovery rates were measured over previously involved skin sites with a skin physiology monitor. One-way ANOVA and two-tailed Student's t test were used to determine the significance between 2 groups and 3 or more groups, respectively., Results: Competent barrier function was observed in all subtypes of cured leprosy subjects. All cured leprosy subjects except those with the borderline tuberculoid type exhibited a significantly lower SC hydration in comparison with normal subjects. Skin surface pH was significantly elevated in all cured leprosy subjects in comparison with normal subjects., Conclusions: A varied spectrum of alterations in SC function remains in all subjects who have recovered from leprosy, but the spectrum of SC functional abnormalities varies with disease subtype., (Copyright 2009 S. Karger AG, Basel.)

Background: The study and assessment of oxidative stress plays a significant role in the arena of leprosy treatment. Once the presence of oxidative stress is proved, antioxidant supplements can be provided to reduce tissue injury and deformity., Aim: To study oxidative stress in paucibacillary (PB) and multibacillary (MB) leprosy and to compare it with that in a control group., Methods: Fifty-eight untreated leprosy patients (23 PB and 35 MB cases) were studied and compared with 58 healthy controls. Superoxide dismutase (SOD) level as a measure of antioxidant status; malondialdehyde (MDA)level, an indicator of lipid peroxidation; and MDA/SOD ratio, an index of oxidative stress were estimated in the serum., Results: The SOD level was decreased in leprosy patients, especially in MB leprosy. The MDA level was increased in PB and MB leprosy. The MDA/SOD ratio was significantly elevated in MB patients. There was a steady increase in this ratio along the spectrum from tuberculoid to lepromatous leprosy (LL)., Conclusion: There is increased oxidative stress in MB leprosy, especially in LL. This warrants antioxidant supplements to prevent tissue injury.

Background: The transmission of Mycobacterium leprae, the causative pathogen of leprosy, has been postulated to occur mainly through upper respiratory route rather than skin-to-skin contact via minor injuries. The M. leprae genome contains mce1A gene, which encodes a putative mammalian cell entry protein. However, to date, there have been no functional analyses of the M. leprae mce1A gene product., Objective: The aim of this study was to elucidate a possible relationship between this transmission mechanism and the mce1A gene product., Methods: We analyzed the cell uptake activity in vitro of polystyrene latex beads coated with a purified recombinant (r-) protein expressed by a 849-bp locus within the mce1A gene., Results: The r-protein promoted uptake of the beads into human nasal epithelial cells derived from nasal polyps, human bronchial epithelial cell line, normal human dermal fibroblasts, normal human microvascular endothelial cells and normal human keratinocytes cultured at 0.01 mM extracellular calcium concentration [Ca]; no uptake occurred with keratinocytes cultured at 1.2mM [Ca]., Conclusion: These results suggest that the mce1A gene product can mediate M. leprae entry into respiratory epithelial cells as their natural target cells, which may be the main mode of transmission. Endothelial cells, on the other hand, may serve as the reservoir of the bacilli for long-term infection. The M. leprae Mce1A protein has potential important implications for mode of transmission and pathogenesis of leprosy.

Background: Nerve damage is a common and disabling feature of leprosy, with unclear aetiology. It has been reported that the peroxidizing agents of myelin lipids-nitric oxide (NO) and peroxynitrite-are produced in leprosy skin lesions., Objectives: To investigate the localization of nitrotyrosine (NT)-a local end-product of peroxynitrite-in leprosy lesions where dermal nerves are affected by a granulomatous reaction., Methods: We investigated by immunohistochemistry and immunoelectron microscopy the localization of the inducible NO synthase (iNOS) and NT in biopsies exhibiting dermal nerves from patients with untreated leprosy., Results: There were abundant NT-positive and iNOS-positive macrophages in the borderline leprosy granulomas infiltrating peripheral nerves identified by light microscopy, S-100 and neurofilament immunostaining. Immunoelectron microscopy showed NT reactivity in neurofilament aggregates and in the cell wall of Mycobacterium leprae., Conclusions: Our results suggest that NO and peroxynitrite could be involved in the nerve damage following borderline leprosy.

Loss of nociception and hypohidrosis in skin are hallmarks of leprosy, attributed to early invasion by Mycobacterium leprae of Schwann cells related to unmyelinated nerve fibres. We have studied skin lesions and contralateral clinically unaffected skin in 28 patients across the leprosy spectrum with a range of selective quantitative sensory and autonomic tests, prior to biopsy of both sites. Unaffected sites showed normal skin innervation, when antibodies to the pan-neuronal marker PGP (protein gene product) 9.5 were used, with the exception of intraepidermal fibres which were not detected in the majority of cases. Elevation of thermal thresholds and reduced sensory axon-reflex flare responses in affected skin correlated with decreased nerve fibres in the subepidermis, e.g. axon-reflex flux units (means+/-SEM) for no detectable innervation; decreased innervation; and clinically unaffected skin, were 23+/-3.1; 41.2+/-7.3; and 84.5+/-4.0, respectively. Reduced nicotine-induced axon-reflex sweating was correlated with decreased innervation of sweat glands. Where methacholine-induced direct activation of sweat glands was affected, there was inflammatory infiltrate and loss of sweat gland structure. This study demonstrates a correlation between selective nerve dysfunction on clinical tests and morphological changes in skin, irrespective of the type of leprosy, and is the first to show that loss of sweating in leprosy may result either from decreased innervation and/or involvement of the sweat glands. The findings have implications for the selection and monitoring of patients with leprosy in clinical trials which aim to restore cutaneous function.

Intracellular localization of antileprosy drugs dapsone (DDS) and rifampicin (RFP) was carried out on skin and nerve lesions obtained from multidrug treated, multi (BL-LL)- and pauci (BT-TT) bacillary cases of leprosy using immunocytochemical techniques. Intracellular localization of the above drugs especially in macrophages and Schwann cells was aimed by using rabbit raised anti DDS and RFP polyclonal antibody in an indirect peroxidase assay. Our study records both intra and extracellular staining with anti DDS and RFP antibodies in the skin as well as nerve lesions of MB and PB cases treated with MDT. All the nerves under investigation had moderate to severe pathology and hence free diffusion of the drug could be attributed to the broken barrier. Basal lamina around the Schwann cell did not seem to form a barrier. It was also noted that the drug (metabolite) persisted over a long period of time).

The present study has provided information on the biometal contents of killed and dried Mycobacterium leprae as well as dermal granulomas induced by the invading mycobacteria in various histological types of leprosy patients. For comparison, the biometal contents of the contralateral leprosy-unaffected skin of the same patients also were measured. The study also reports changes of serum levels of the biometals in these patients which were compared with those in healthy control subjects and patients with skin tuberculosis. These data show that M. leprae is rich in zinc. During the course of the evolution of the disease there is gross alteration of the dynamics of the inflammatory cell population that infiltrates into leprosy granulomas, resulting in the alterations of trace element contents of the disease-affected skin lesions. Interestingly, the changes of the biometal contents in the granulomas of the patients with skin tuberculosis are similar to those in leprosy patients. It is postulated that the significant decrease of the contents of copper, zinc, iron, calcium and magnesium in the disease-affected skin in comparison to that of the contralateral healthy skin is a local effect, perhaps due to erosion or influx of biometal-deficient inflammatory cells into the affected skin with eventual loss of connective tissue of skin and mobilization of tissue-bound microelements into the vascular compartment. On the contrary, the changes in biometal levels in the sera of leprosy patients appear to be a general effect perhaps due to the release of interleukin-1, a product of inflammatory cells, causing hypercupremic, hypozincemic and hypoferremic responses in the hosts. Moreover, growth and multiplication of M. leprae, especially in polar lepromatous leprosy patients with a high bacillary load, demand essential biometals which may be mobilized into the bacterial bodies from the hosts. This perhaps results in the change in the homeostasis of the essential biometals in the hosts.

The aim of this study was to determine cytokines in human leprosy lesions by means of immunohistologic examination. Cryostat sections of skin biopsies from 57 patients with various forms of leprosy were immunostained according to the APAAP method, using monoclonal antibodies against interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), and, in addition, against CD 1 antigen. Granulomas in biopsies of untreated patients with tuberculoid leprosy showed large amounts of cells positive for IL-1 beta, TNF-alpha, IFN-gamma, and CD 1, whereas no positive signals could be detected in untreated patients with lepromatous leprosy. However, in those biopsies obtained from lepromatous leprosy patients undergoing chemotherapy, positive staining for cytokines as well as subepidermal Langerhans cells increased to a detectable amount. Remarkably, in tuberculoid leprosy patients, the number of IL-1 beta--positive cells did not vary under therapy, while the number of TNF-alpha and IFN-gamma reactive cells decreased. These results suggest that immunohistologic determination of cytokines in combination with the assessment of subepidermal Langerhans cells in human leprosy lesions may be used as a parameter for the patient's status of cell-mediated immunity under chemotherapeutic treatment.

The skin of leprous patients at various stages of the disease was investigated by diagnostic x-ray spectrometry, In the active stage raised iron and slightly raised zinc levels were found. The usefulness of the method in skin investigation is foreseen.

The study of hydration power of stratum corneum of lesions show highly significant poor water-uptake at low temperatures (p less than 0.001), a defect not recorded after removal of water soluble fractions. Secondly, the lesions show significant poor water-diffusive power (p less than 0.001). The findings suggest a qualitative alteration in the stratum corneum of leprosy patients, probably in its water-soluble protein fraction.

The cutaneous innervation is now known to contain neuropeptides including substance P (SP) and calcitonin gene-related peptide (CGRP) in sensory nerves, and vasoactive intestinal polypeptide (VIP) and neuropeptide Y (NPY), principally in autonomic nerves. Skin biopsies from 100 leprosy patients and equivalent areas from 50 non-leprosy controls were fixed in p-benzoquinone solution for immunofluorescence staining and in Bouin's fluid for classification of leprosy type. Antisera to the neural markers, neurofilaments, and protein gene product 9.5 (PGP 9.5), and to neuropeptides were used. Cutaneous nerves and nerve endings immunoreactive for neuropeptides, neurofilaments, and PGP 9.5 were seen in all non-leprous control cases. In leprosy, PGP 9.5- and neurofilament-immunoreactive nerve fibres were seen in all 14 cases of the indeterminate (early) type and in the majority (33/43) of lepromatous cases, but in a smaller proportion (15/43) of tuberculoid cases. Neuropeptide immunoreactivity was seen in only 2/14 of the indeterminate leprosy specimens and was completely absent in other types. This early disappearance may be of diagnostic significance. Thus, cutaneous sensory and autonomic dysfunctions in leprosy are well reflected by changes in nerve fibres and neuropeptides.

Croystat sections of dermal lesions from 33 untreated patients with leprosy were studied by indirect immunofluorescence using monoclonal antibodies to human fibronectin. Macrophages in borderline (BL) and lepromatous (LL) leprosy showed intense staining with antifibronectin antibodies. In the tuberculoid lesions cells of the mononuclear phagocyte series in an epithelioid cell granuloma stained for fibronectin. The lymphocytes surrounding these granulomas also showed the presence of fibronectin. These results suggest that the granuloma of leprosy consists of macrophages expressing fibronectin and the lymphocytes in the lesion also appear to express this protein. In six borderline cases, the sub epidermal collagen band showed intense staining with antifibronectin antibodies. In addition, the distribution of Ia-like antigens and fibronectin was studied on the plastic adherent cells obtained from peripheral blood of 11 untreated patients with leprosy. Results indicate that higher percentage of adherent cells from lepromatous patients express fibronectin in comparison to adherent cells from tuberculoid patients or controls. However, no difference was observed in the expression of the Ia-like antigens by the adherent cells, from these patients.

Skin and serum zinc measurements have been made in patients with leprosy with and without trophic skin ulceration and in several other groups. Serum zinc concentrations were decreased in leprosy irrespective of the presence or absence of skin ulceration. Serum zinc concentrations in leprosy were also unrelated to smears positive for Mycobacterium leprae and to the clinical type of leprosy. Since a decrease of the serum zinc was also found in patients with dermatitis herpetiformis and pulmonary tuberculosis it seems likely that the decreased serum zinc in leprosy is a nonspecific metabolic consequence of chronic skin and internal disease. The mean skin zinc concentration in leprosy did not differ significantly from the corresponding value in control subjects, the lack of agreement between serum and skin concentrations being possibly related to the presence of nonexchangeable keratin-bound zinc in skin. Though the clinical significance of lowered serum zinc concentrations in leprosy is uncertain therapeutic trials of zinc treatment in leprosy with trophic skin ulceration seem justifiable.

Phenolic glycolipid-I, a marker lipid of Mycobacterium leprae, was isolated from skin biopsies obtained from untreated lepromatous leprosy patients by silicic acid and florisil column chromatography and purified by thin layer chromatography. Tissues with varying bacillary loads were analysed for their phenolic glycolipid content. A good correlation was observed between the bacillary population of the tissues and the phenolic glycolipid content.

Thin-layer chromatography was used to compare lipid extracts from lepromatous skin biopsies with those from normal skin and from Mycobacterium leprae purified from armadillo spleen. Several lipids were found in infected skin which were absent from normal skin but corresponded to lipids present in the purified M. leprae. These included mycolic acids, a 6-deoxyhexose-containing lipid (glycolipid I) and a wax ester (possibly related to the Mycobacterium tuberculosis wax, phthiocerol dimycocerosate). Unlike Mycobacterium lepraemurium, M. leprae contained no C-type mycosides. In terms of lipid profile, M. leprae from armadillo spleen showed the same characteristics as bacilli from human skin samples. Quantitative analysis of mycobacterial lipids in lepromatous skin biopsies indicated that their concentrations were much higher than would be predicted from the number of acid-fast bacilli present. Accumulation of lipid debris from dead M. leprae could provide a protective environment in infected cells for remaining viable bacilli.

A total of 30 cases of leprosy (15 lepromatous and 15 tuberculoid) were studied by histochemical procedures for lipids in the morbid skin. The possible origin and relation of lipids to the presence of lepra bacilli in the lepra cells is discussed.