Development of leprosy and type 1 leprosy reactions after treatment with infliximab: a report of 2 cases.

Humanized monoclonal antibodies to tumor necrosis factor- alpha are valuable for the treatment of rheumatologic conditions, but they have been associated with the development of serious infections. We report the first 2 cases of leprosy developing after treatment with infliximab. After discontinuation of infliximab, both patients developed type 1 ("reversal") leprosy reactions.

The continuing challenges of leprosy.

Leprosy is best understood as two conjoined diseases. The first is a chronic mycobacterial infection that elicits an extraordinary range of cellular immune responses in humans. The second is a peripheral neuropathy that is initiated by the infection and the accompanying immunological events. The infection is curable but not preventable, and leprosy remains a major global health problem, especially in the developing world, publicity to the contrary notwithstanding. Mycobacterium leprae remains noncultivable, and for over a century leprosy has presented major challenges in the fields of microbiology, pathology, immunology, and genetics; it continues to do so today. This review focuses on recent advances in our understanding of M. leprae and the host response to it, especially concerning molecular identification of M. leprae, knowledge of its genome, transcriptome, and proteome, its mechanisms of microbial resistance, and recognition of strains by variable-number tandem repeat analysis. Advances in experimental models include studies in gene knockout mice and the development of molecular techniques to explore the armadillo model. In clinical studies, notable progress has been made concerning the immunology and immunopathology of leprosy, the genetics of human resistance, mechanisms of nerve injury, and chemotherapy. In nearly all of these areas, however, leprosy remains poorly understood compared to other major bacterial diseases.

Development of leprosy and type 1 leprosy reactions after treatment with infliximab: a report of 2 cases

Humanized monoclonal antibodies to tumor necrosis factor- alpha are valuable for the treatment of rheumatologic conditions, but they have been associated with the development of serious infections. We report the first 2 cases of leprosy developing after treatment with infliximab. After discontinuation of infliximab, both patients developed type 1 ([quot ]reversal[quot ]) leprosy reactions.

The continuing challenges of leprosy

Leprosy is best understood as two conjoined diseases. The first is a chronic mycobacterial infection that elicits an extraordinary range of cellular immune responses in humans. The second is a peripheral neuropathy that is initiated by the infection and the accompanying immunological events. The infection is curable but not preventable, and leprosy remains a major global health problem, especially in the developing world, publicity to the contrary notwithstanding. Mycobacterium leprae remains noncultivable, and for over a century leprosy has presented major challenges in the fields of microbiology, pathology, immunology, and genetics; it continues to do so today. This review focuses on recent advances in our understanding of M. leprae and the host response to it, especially concerning molecular identification of M. leprae, knowledge of its genome, transcriptome, and proteome, its mechanisms of microbial resistance, and recognition of strains by variable-number tandem repeat analysis. Advances in experimental models include studies in gene knockout mice and the development of molecular techniques to explore the armadillo model. In clinical studies, notable progress has been made concerning the immunology and immunopathology of leprosy, the genetics of human resistance, mechanisms of nerve injury, and chemotherapy. In nearly all of these areas, however, leprosy remains poorly understood compared to other major bacterial diseases.

Distinct histopathological patterns in single lesion leprosy patients treated with single dose therapy (ROM) in the Brazilian Multicentric Study.

This paper aims to describe the histomorphologic features of skin biopsies of single lesion leprosy patients recruited at outpatient clinics in four Brazilian states in the Northeast (Amazonas and Rondonia), Southeast (Rio de Janeiro) and Center-West (Goiás) between October 1997 and December 1998. Patients clinically diagnosed as single skin lesion paucibacillary (SSL-PB) leprosy had a standard 4-mm punch biopsy taken from the lesion before rifampin, ofloxacin, minocycline (ROM) therapy. The features of the cellular inflammatory infiltrates, the presence of nerve involvement and acid-fast bacilli (AFB) were used to categorize SSL-PB biopsies into different histopathological groups. Two-hundred-seventy-eight (93.0%) out of 299 patients had a skin biopsy available. Seven single lesion patients were diagnosed as BL or LL leprosy types (MB) by the histopathological exams and 12 cases were excluded due to other skin diseases. Therefore, 259 patients had skin lesions with histomorphological features compatible with PB leprosy categorized as follows: 33.6% (N = 87) of the biopsies represented well-circumscribed epithelioid cell granuloma (Group 1); 21.6% (N = 56) less-circumscribed epithelioid cell granuloma (Group 2); 12.0% (N = 31) were described as mononuclear inflammatory infiltrate permeated with epithelioid cells (Group 3), and 29.7% (N = 77) had perivascular/periadnexal mononuclear inflammatory infiltrate (Group 4). Minimal/no morphological alteration in the skin was detected in only 8 (3.1%) SSL-PB patients categorized as Group 5, who were considered to have leprosy by clinical parameters. SSL-PB leprosy patients recruited in a multicentric study presented histomorphology readings comprising the whole PB leprosy spectrum but also a few MB cases. These results indicate heterogeneity among SSL-PB patients, with a predominance of well-circumscribed and less-circumscribed epithelioid cell granulomas (Groups 1 and 2) in the sites studied and the heterogeneity of local cellular immune response.

Association of Mycobacterium leprae with human endothelial cells in vitro.

Endothelial cell infection by Mycobacterium leprae has long been described histologically in all types of leprosy and in some of the acute reactions occurring in this disease. Recent evidence from experimental lepromatous neuritis indicates that M. leprae colonizes endothelial cells of epineural blood vessels even in sites of minimal infection, suggesting that interaction between these cells and M. leprae may play an important role in the selective localization of this organism to peripheral nerve. To begin to study the mechanisms involved, we have examined the interaction between M. leprae and human umbilical vein endothelial cells (HUVEC) in vitro using light microscopy, scanning and transmission electron microscopy, and confocal laser scanning microscopy. When M. leprae were added to confluent monolayers of HUVEC, uptake increased slowly to a maximum at 24 hours. Maximal percentages of infected cells were similar at ratios of organisms:cell over a range of 25:1 to 100:1. The bacilli appeared to lie within membrane-bound vacuoles at all time points. The kinetics of association of M. leprae with HUVEC are much slower than has previously been observed with macrophages, possibly due to differences in the binding of M. leprae. Compared with other pathogens that infect endothelial cells, M. leprae also appear to be ingested more slowly, and to a more limited degree. The receptors involved in M. leprae binding to endothelial cells and the impact of intracellular infection by M. leprae on these cells remain to be determined.

Endothelial cells and the pathogenesis of lepromatous neuritis:insights from the armadillo model.

Selective infection of peripheral nerves is a unique property of Mycobacterium leprae that results in serious injury, but its basis is unexplained. Recent evidence from infected armadillos suggests that endothelial cells of peripheral nerve vasculature may be the gatekeepers by which M. leprae infects nerves. The pathogenesis of neuropathy in leprosy may thus entail a dynamic sequence of adhesion, immunologic, and inflammatory processes involving peripheral nerve endothelial cells.

Hansen's disease in a patient with a history of sarcoidosis.

We report a rare case of concomitant Hansen's disease (HD) and sarcoidosis. Reticulin staining may be a helpful diagnostic tool in establishing the diagnosis of sarcoidosis in skin lesions. The diagnosis of HD can be established despite negative polymerase chain reaction results for the detection of Mycobacterium leprae DNA. Finally, a well-established diagnosis of sarcoidosis does not preclude the development of another granulomatous disorder. Hence, when new lesions developed in a patient with sarcoidosis despite appropriate therapy, other concurrent diagnoses should be pursued.

Oropharyngeal leprosy in art, history, and medicine.

Advanced lesions of the face, nasopharynx, and oropharynx have played an important role in the medical and social history of Hansen's disease. Renaissance artists included detailed portrayals of these lesions in some of their paintings, a testimony not only to their artistic skill and powers of observation but also to the common presence of these patients in European cities and towns of the period. The disease is now understood as a broad immunologic spectrum of host responses to Mycobacterium leprae, with a variety of clinical and pathologic manifestations in nerve, soft tissues, and bone. This review incorporates the findings of 2 extraordinary studies (one from Europe and the other from Japan) of pharyngeal and facial lesions. In the 1950s, studies of skeletal remains from the churchyard of a Danish leprosarium revealed a triad of maxillofacial lesions unique to leprosy and designated facies leprosa. In pre-World War II Japan, before effective treatment had been discovered, a prominent otorhinolaryngologist studying oropharyngeal and nasopharyngeal lesions prepared watercolor illustrations of the natural progression of untreated Hansen's disease. As a result of effective antimicrobial therapy, such advanced lesions are now rarely seen, but the presenting signs and symptoms of leprosy still occasionally arise in the nasal and oral mucosa. The nasopharynx and oropharynx may be important early sites of inoculation and infection by M leprae, and they require additional emphasis in worldwide efforts toward early diagnosis and treatment of Hansen's disease.

Localization of Mycobacterium leprae to endothelial cells of epineurial and perineurial blood vessels and lymphatics.

Infection of peripheral nerve by Mycobacterium leprae, the histopathological hallmark of leprosy, is a major factor in this disease, but the route and mechanisms by which bacilli localize to peripheral nerve are unknown. Experimentally infected armadillos have recently been recognized as a model of lepromatous neuritis; the major site of early accumulation of M. leprae is epineurial. To determine the epineurial cells involved, 1-cm segments of 44 nerves from armadillos were screened for acid-fast bacilli and thin sections were examined ultrastructurally. Of 596 blocks containing nerve, 36% contained acid-fast bacilli. Overall, M. leprae were found in endothelial cells in 40% of epineurial blood vessels and 75% of lymphatics, and in 25% of vessels intraneurally. Comparison of epineurial and endoneurial findings suggested that colonization of epineurial vessels preceded endoneurial infection. Such colonization of epineurial nutrient vessels may greatly increase the risk of endoneurial M. leprae bacteremia, and also enhance the risk of ischemia following even mild increases in inflammation or mechanical stress. These findings also raise the possibility that early, specific mechanisms in the localization of M. leprae to peripheral nerve may involve adhesion events between M. leprae (or M. leprae-parasitized macrophages) and the endothelial cells of the vasa nervorum.

M. leprae infection of vascular and lymphatic endothelial cells of the epineurium and perineurium in experimental lepromatous neuritis.

Infection of peripheral nerve by M. leprae, the histopathologic hallmark of leprosy, is a major factor in this disease, but the route and mechanisms by which bacilli localize to peripheral nerve are unknown. Experimentally infected armadillos have recently been recognized as a model of lepromatous neuritis; the major site of early accumulation of M. leprae is epineurial. To determine the epineurial cells involved, 1 cm. segments of 44 nerves from armadillos were screened for acid-fast bacilli (AFB), and thin sections were examined ultrastructurally. Of 596 blocks containing nerve, 36% contained AFB. Overall, M. leprae were found in endothelial cells in 40% of epineurial blood vessels and 75% of lymphatics, and in 25% of endoneurial vessels. Comparison of epineurial and endoneurial findings suggested that colonization of epineurial vessels preceded endoneurial infection. Such colonization of epineurial nutrient vessels may greatly increase the risk of endoneurial M. leprae bacteremia, and also enhance the risk of ischemia following even mild increases in inflammation or mechanical stress. These findings also raise the possibility that early, specific mechanisms in the localization of M. leprae to peripheral nerve may involve adhesion events between M. leprae (or M. leprae-parasitized macrophages) and the endothelial cells of the vasa nervorum.

Impaired responses to Mycobacterium leprae antigens in rhesus monkeys experimentally inoculated with simian immunodeficiency virus and M. leprae.

Seven of eight rhesus monkeys (RM) coinfected with simian immunodeficiency virus (SIV) and Mycobacterium leprae harboured acid-fast bacilli (AFB) at sites of dermal inoculation and/or at disseminated sites at times of humane sacrifice (up to 270 days post-M. leprae inoculation) due to SIV-induced debilitation or, in one long term survivor's case, to date over 3 years post-M. leprae inoculation. Detectable AFB were cleared in biopsies of inoculation sites of RM inoculated with M. leprae alone after 63 days postinoculation; these sites have, so far, remained AFB-negative, thereafter. Compared to animals infected with M. leprae alone, RM coinfected with SIV plus M. leprae showed: 1, completely suppressed serum antibody responses to M. leprae-specific PGL-I antigen, but strong anti-SIV Gp120 antibody responses; 2, impaired sensitization of blood mononuclear cells (MNC) to in vitro recognition of M. leprae-specific antigens in blastogenic stimulation assays; 3, impaired in vitro responses of blood MNC to nonspecific (ConA) blastogenic stimuli; and 4, early post-M. leprae inoculation, there was a significant incremental diminution of percentages of blood CD4+CD29+ T-cells in addition to the existing SIV-induced diminished percentages of CD4+CD29+ T-cells. The results indicate that humoral and cellular immune responses to M. leprae antigens are compromised in M. leprae-inoculated RM previously infected with SIV. These results provide an immunologic basis for the demonstration of enhanced M. leprae persistence or leprosy susceptibility in SIV-M. leprae coinfected RM.

Polymerase chain reaction assay for the detection and identification of Mycobacterium leprae in patients in the United States.

The differentiation of leprosy from other cutaneous granulomatous diseases is routinely based on characteristic histopathologic features and the demonstration of Mycobacterium leprae by acid-fast staining. Increased ascertainment of other mycobacterial infections in the skin has made this task more difficult, but the distinction remains fundamental for the selection of appropriate treatment. Experience with formalin-fixed, paraffin-embedded tissues, frozen tissues, and tissue lysates referred for detection of M. leprae DNA by a polymerase chain reaction (PCR) assay during the past 4 years was reviewed. This assay was done by using primers and probes previously developed in our laboratory to amplify a 360-base-pair fragment of the gene for an 18-kD protein of M. leprae. Among biopsy samples obtained from 37 patients, PCR results were positive for 10 of 20 samples diagnosed as leprosy by histopathologic criteria and in 0 of 17 not diagnosed as leprosy. The specificity of the assay was 100% in this clinical referral material; sensitivity ranged from 50% to 83%. The PCR assay also identified M. leprae in one third of samples in which acid-fast organisms were seen and the histopathologic features were consistent with but not definitive of leprosy. In a nonendemic population, the sensitivity and specificity of PCR assay recommend its use primarily to identify M. leprae when acid-fast organisms are discernible but atypical clinical or histopathologic features obscure the diagnosis. The assay is not highly informative when acid-fast bacilli are not detectable by light microscopy.

Reactivity of a population of armadillo lymphocytes with an antibody to human gamma,delta T-cells.

Reactivity of lymphocytes from the nine-banded armadillo (Dasypus novemcinctus) was examined by flow cytometry using a panel of 16 commercially available fluorochrome-conjugated monoclonal antibodies raised against human or murine leukocyte antigens. The only reactivity observed was with antibody TCRdelta1, directed against a common determinant on the delta chain of the human gamma,delta T-cell receptor. Using this antibody, a distinct, bright population of lymphocytes was seen in the peripheral blood in all of 47 animals examined, accounting for 2.0-47.1% of lymphocytes (median, 10.6%). The gamma,delta-reactive lymphocyte population comprised a greater percentage of intraepithelial lymphocytes in the small intestine than in the blood; variable percentages of gamma,delta-reactive cells were also observed in the spleen, thymus, lymph nodes, and bone marrow, and in cutaneous lepromas. In armadillos with disseminated Mycobacterium leprae infection, a significantly greater percentage of circulating lymphocytes reacted with the anti-gamma,delta antibody. This is the first described reactivity of armadillo lymphocytes with a monoclonal antibody to a lymphocyte antigen, and it may offer a useful tool in disease models involving the armadillo.

Infection of distal peripheral nerves by M. leprae in infected armadillos; an experimental model of nerve involvement in leprosy.

Mechanisms of localization of Mycobacterium leprae to the peripheral nerves and of subsequent nerve injury are not understood. No experimental animal model has been available for use in examining the pathogenesis of M. leprae-induced nerve injury. A detailed dissection was, therefore, done of the major peripheral nerves in the extremities of six M. leprae-inoculated armadillos, three of which had developed characteristic disseminated infection. All of the animals with disseminated infection had extensive involvement of the peripheral nerves, increasing in intensity as the nerve was followed distally. No M. leprae were found in the animals without disseminated infection. The degree of infection was greater in epineural tissues than in the intraneural compartment (i.e., Schwann cells) at all levels. The infection of nerves by M. leprae was associated with focal interstitial, mononuclear cell infiltration of involved nerves. These results suggest that: 1) armadillos offer a model for the study of neural involvement in leprosy, since the pattern of neural distribution in susceptible armadillos is comparable to the pattern of nerve involvement in man; 2) early localization of M. leprae may be to the epineural tissues, including lymphatic and vascular structures and extracellular matrix; 3) Schwann cell involvement may be a late event; and 4) mechanisms involving the endothelium of epineural and perineural tissues may be important in the selective localization of M. leprae to peripheral nerves.

Epidemiologic characteristics of leprosy reactions.

An 8-year prospective study of a cohort of 176 newly diagnosed leprosy patients was conducted to examine the possible influence of age, sex, multidrug therapy (MDT), and duration of illness on the risk of either type 1 or type 2 reactions. Patients were enrolled over a 5-year period (1984-1989) and followed for a minimum of 3 years. All reactions studied were severe enough to warrant hospital admission. Overall, 45% of this cohort developed a reaction; 32% of patients considered at risk developed type 1 reactions, and 37% of patients considered at risk developed type 2 reactions. Despite the predominance of men among the leprosy patients, type 1 reactions occurred with significantly greater frequency in women, and did not appear to be influenced by age of onset of leprosy. Individuals experiencing one type 1 reaction were not likely to experience a recurrence, suggesting that the immunologic mechanisms of this reaction may be limited or regulated by genetic or immunologic factors. Type 2 reactions, on the other hand, occurred with equal frequency in both males and females, but were highly associated with onset of leprosy in the second decade of life. Individuals who experienced type 2 reactions often had one or more recurrence of the reaction. No increased risk was seen for either reaction with longer duration of leprosy or longer duration of treatment. The mechanisms by which these differences relate to the pathogenesis of leprosy reactions remains unclear, but future studies of clinical and immunological parameters of leprosy reactions may benefit from stratification of data by gender and age of onset of leprosy in addition to the routine grouping of results by leprosy classification.

Localization of a novel pathway for the liberation of GABA in the human CNS.

Serum carnosinase is a dipeptidase, which is synthesized in human brain, where it hydrolyzes homocarnosine to release free GABA. Immunohistochemical procedures were used to demonstrate the presence of this enzyme in several layers of the retina and in certain neuronal tracts of the cerebral cortex, cerebellar cortex, olfactory bulb, hippocampus, and in disseminated tracts presumably from the internal capsule, interspersed among the basal ganglia. The enzyme was also present in the epithelial cells of the choroid plexus and in corpora amylacea, which were seen in many regions of the CNS. Homocarnosine was localized either in the same tracts or in nearby neurons. For example, the Purkinje cells of the cerebellar cortex contained homocarnosine, whereas serum carnosinase was localized in adjacent neuronal projections apparently originating from outside the cerebellar cortex and having probable synaptic contact with the Purkinje cells. These findings suggest that in addition to glutamate decarboxylation, a second metabolic reaction for the formation of free GABA exists in specific neuronal tracts of the human CNS where GABA is released from homocarnosine by the action of serum carnosinase.