High levels of inflammatory cytokines are associated with poor clinical response to steroid treatment and recurrent episodes of type 1 reactions in leprosy

Susceptibility and resistance in leprosy: Studies in the mouse model

Leprosy is a chronic granulomatous infectious disease caused by the pathogen, Mycobacterium leprae, and the more recently discovered, M. lepromatosis. Described in 1873, M. leprae was among the first microorganisms to be proposed as a cause of a human infectious disease. As an obligate intracellular bacterium, it has still not thus far been reproducibly cultivated in axenic medium or cell cultures. Shepard's mouse footpad assay, therefore, was truly a breakthrough in leprosy research. The generation of immunosuppressed and genetically engineered mice, along with advances in molecular and cellular techniques, has since offered more tools for the study of the M. leprae–induced granuloma. While far from perfect, these new mouse models have provided insights into the immunoregulatory mechanisms responsible for the spectrum of this complex disease.

A Study on the Impact of Genetic Polymorphisms of Cytokines TNFα, IFNγ and IL10 in South Indian Leprosy Patients

Background:

Leprosy (Hansen's disease) is a chronic, debilitating disease predominantly of the peripheral nervous system characterized by the impairment of peripheral nerves and subsequent sensory loss caused by Mycobacterium leprae. The pro- and antiinflammatory cytokine genes play a major role in nerve damage in leprosy.

Aims and Objectives:

The objective of the present study is to ascertain the association of cytokine gene polymorphisms TNFα - 308G/A (rs 1800629), IFNγ +874A/T (rs 2430561), and IL10 - 1082G/A rs 1800896 in causation with leprosy.

Materials and Methods:

The present study comprised 365 leprosy patients and 185 control subjects. The polymorphisms in TNFα-308, IFNγ+874, and IL10-1082 genes were typed using the amplification refractory mutation system polymerase chain reaction method (ARMS PCR).

Results:

The present study found significant association between IL10-1082 GA heterozygote (P < 0.02) and IFNγ+874 AA (P < 0.001) genotype and leprosy. TNFα-308GA could not establish any association with the disease.

Conclusion:

The identification of genetic variations in pro- and antiinflammatory cytokines that are susceptible to leprosy would assist in better understanding of the pathogenesis of leprosy and perhaps lead to new approaches for diagnosis and treatment.

Severe type 2 leprosy reaction with COVID-19 with a favourable outcome despite continued use of corticosteroids and methotrexate and a hypothesis on the possible immunological consequences

Type 2 leprosy reaction (T2LR), or Erythema Nodosum Leprosum (ENL), often poses a therapeutic challenge to clinicians and commonly requires long courses of steroids for control. While immunosuppressants are known to achieve control and lower steroid dependence in T2LR, the prospect of managing a severe T2LR in conjunction with COVID-19, with the concern of worsening COVID-19 with long-term immunosuppression has not previously been encountered. We report a case of severe T2LR treated with oral steroids and methotrexate, with COVID-19 infection acquired during hospital stay, and a favourable outcome achieved despite the continued use of immunosuppressants. We discuss the possible reasons for this both in terms of the drug pharmacodynamics and the immunological profile of T2LR.

Serum Th1/Th2 and macrophage lineage cytokines in leprosy; correlation with circulating CD4(+) CD25(high) FoxP3(+) T-regs cells

Not only macrophages, T-helper (Th)1 and Th2, but also CD4(+) CD25(high) FoxP3(+) regulatory T cells (T-regs) are involved in immune response to Mycobacterium leprae. We aimed to evaluate serum interleukin (IL)-1β and IL-12p70 (macrophage cytokines), interferon-γ (IFN-γ) (Th1 cytokine), IL-4 (Th2 cytokine) and circulating CD4(+) CD25(high) FoxP3(+) T-regs, in untreated leprosy patients. Forty three patients and 40 controls were assessed for the mentioned cytokines using ELISA. Patients were assessed for circulating T-regs using flow cytometry. Patients were subgrouped into tuberculoid (TT), pure neural leprosy (PNL), borderline cases, lepromatous (LL), type 1 reactional leprosy (RL1) and erythema nodosum leprosum (ENL). Serum IL-12p70, IFN-γ and IL-4 were significantly higher in patients versus controls (P < 0.05). Serum IL-4 was highest in LL and lowest in RL1 (P = 0.003). Serum IL-1β levels was significantly higher in multibacillary versus paucibacillary patients (P = 0.006). Significantly higher T-regs levels was detected in TT, RL1 and PNL, while the lowest levels in ENL(P < 0.001), with significant differences versus controls (P < 0.05). FoxP3 expression% was significantly lower in PNL than other patients and controls (P < 0.05). T-regs/T-effs was lowest in ENL(P < 0.05). IFN-γ correlated positively with T-regs but negatively with IL-1β (P = 0.041&0.046 respectively), which correlated positively with T-effs%( P = 0.05). IL-4 correlated positively with T-regs FoxP3 expression% (P = 0.009). We concluded that: Circulating T-regs were increased in TT, RL1 and PNL patients, known of relatively high cell-mediated immunity. This finding was supported by low FoxP3 expression (in PNL) and correlation between T-regs count and IFN-γ level. Overproduction of IL-4 in LL may infer liability to develop ENL, with disease progression and immune hyperactivation, marked by deficient T-regs and increased T-regs FoxP3 expression%. IL-1β probably has a pro-inflammatory role in multibacillary patients as correlated with T-effs%.

Longitudinal immune profiles in type 1 leprosy reactions in Bangladesh, Brazil, Ethiopia and Nepal

Background

Acute inflammatory reactions are a frequently occurring, tissue destructing phenomenon in infectious- as well as autoimmune diseases, providing clinical challenges for early diagnosis. In leprosy, an infectious disease initiated by Mycobacterium leprae (M. leprae), these reactions represent the major cause of permanent neuropathy. However, laboratory tests for early diagnosis of reactional episodes which would significantly contribute to prevention of tissue damage are not yet available.

Although classical diagnostics involve a variety of tests, current research utilizes limited approaches for biomarker identification. In this study, we therefore studied leprosy as a model to identify biomarkers specific for inflammatory reactional episodes.

Methods

To identify host biomarker profiles associated with early onset of type 1 leprosy reactions, prospective cohorts including leprosy patients with and without reactions were recruited in Bangladesh, Brazil, Ethiopia and Nepal. The presence of multiple cyto-/chemokines induced by M. leprae antigen stimulation of peripheral blood mononuclear cells as well as the levels of antibodies directed against M. leprae-specific antigens in sera, were measured longitudinally in patients.

Results

At all sites, longitudinal analyses showed that IFN-γ-, IP-10-, IL-17- and VEGF-production by M. leprae (antigen)-stimulated PBMC peaked at diagnosis of type 1 reactions, compared to when reactions were absent. In contrast, IL-10 production decreased during type 1 reaction while increasing after treatment. Thus, ratios of these pro-inflammatory cytokines versus IL-10 provide useful tools for early diagnosing type 1 reactions and evaluating treatment. Of further importance for rapid diagnosis, circulating IP-10 in sera were significantly increased during type 1 reactions. On the other hand, humoral immunity, characterized by M. leprae-specific antibody detection, did not identify onset of type 1 reactions, but allowed treatment monitoring instead.

Conclusions

This study identifies immune-profiles as promising host biomarkers for detecting intra-individual changes during acute inflammation in leprosy, also providing an approach for other chronic (infectious) diseases to help early diagnose these episodes and contribute to timely treatment and prevention of tissue damage.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1128-0) contains supplementary material, which is available to authorized users.

IL-10 and NOS2 modulate antigen-specific reactivity and nerve infiltration by T cells in experimental leprosy

Background

Although immunopathology dictates clinical outcome in leprosy, the dynamics of early and chronic infection are poorly defined. In the tuberculoid region of the spectrum, Mycobacterium leprae growth is restricted yet a severe granulomatous lesion can occur. The evolution and maintenance of chronic inflammatory processes like those observed in the leprosy granuloma involve an ongoing network of communications via cytokines. IL-10 has immunosuppressive properties and IL-10 genetic variants have been associated with leprosy development and reactions.

Methodology/Principal Findings

The role of IL-10 in resistance and inflammation in leprosy was investigated using Mycobacterium leprae infection of mice deficient in IL-10 (IL-10−/−), as well as mice deficient in both inducible nitric oxide synthase (NOS2−/−) and IL-10 (10NOS2−/−). Although a lack of IL-10 did not affect M. leprae multiplication in the footpads (FP), inflammation increased from C57Bl/6 (B6)<IL-10−/−<NOS2−/−<10NOS2−/−. While IL-10−/− mice exhibited modest FP induration compared to B6, NOS2−/− and 10NOS2−/− mice developed markedly enlarged FP marking distinct phases: early (1 month), peak (3–4 months), and chronic (8 months). IFN-γ-producing CD4+CD44+ cells responding to M. leprae cell wall, membrane, and cytosol antigens and ML2028 (Ag85B) were significantly increased in the evolved granuloma in NOS2−/− FP compared to B6 and IL-10−/− during early and peak phases. In 10NOS2−/− FP, CD4+CD44+ and especially CD8+CD44+ responses were augmented even further to these antigens as well as to ML0380 (GroES), ML2038 (bacterioferritin), and ML1877 (EF-Tu). Moreover, fragmented nerves containing CD4+ cells were present in 10NOS2−/− FP.

Conclusions/Significance

The 10NOS2−/− strain offers insight on the regulation of granuloma formation and maintenance by immune modulators in the resistant forms of leprosy and presents a new model for investigating the pathogenesis of neurological involvement.

Despite effective antimicrobial therapy, 30–50% of leprosy patients develop immunological complications called leprosy reactions before, during or even years after being cured. Leprosy reactions are a major risk for neuritis that leads to peripheral nerve damage, disfigurement and disability. Unfortunately, why and how leprosy reactions occur is not well understood. Based on the latest human genetic leprosy susceptibility research and mouse infection models, we generated a double knockout mouse strain (10NOS2−/−) which has deficiencies in two key immune factors, interleukin-10 (IL-10) and inducible nitric oxide synthase (NOS2). We investigated the dynamics of the immune response to Mycobacterium leprae infection and chronicled the types of immune cells recruited to the site of infection. 10NOS2−/− mice developed a substantial induration in response to infection, as well as an increased interferon-gamma response to components of the leprosy bacillus. Interestingly, these animals also exhibited CD4+ T cell infiltration into the nerves, a phenomenon which has not been previously reported in leprosy mouse models. This new model provides insight into potential mechanisms whereby immune modulators may regulate leprosy reactions and neuritis and could aid the development of tests for monitoring and treatment of leprosy patients.

Tuberculosis in a renal allograft recipient presenting with intussusception

Extra-pulmonary tuberculosis (TB) is more common in renal allograft recipients and may present with dissemination or an atypical features. We report a renal allograft recipient with intestinal TB presenting 3 years after transplantation with persistent fever, weight loss, diarrhea, abdominal pain and mass in the abdomen with intestinal obstruction. He was diagnosed to be having an ileocolic intussusception which on resection showed a granulomatous inflammation with presence of acid-fast bacilli (AFB) typical of Mycobacterium tuberculosis. In addition, AFB was detected in the tracheal aspirate, indicating dissemination. He received anti-TB therapy (ATT) from the fourth postoperative day. However, he developed a probable immune reconstitution inflammatory syndrome (IRIS) with multiorgan failure and died on 11(th) postoperative day. This is the first report of intestinal TB presenting as intussusception in a renal allograft recipient. The development of IRIS after starting ATT is rare in renal allograft recipients. This report highlights the need for a high index of suspicion for diagnosing TB early among renal transplant recipients and the therapeutic dilemma with overwhelming infection and development of IRIS upon reduction of immunosuppression and starting ATT.

Leprosy reactions: coinfections as a possible risk factor

OBJECTIVE

This study aimed to determine the frequency of coinfections in leprosy patients and whether there is a relationship between the presence of coinfections and the development of leprosy reactional episodes.

METHOD

A cross-sectional study based on an analysis of the medical records of the patients who were treated at the Leprosy Clinics of the Ribeirão Preto Medical School, University of São Paulo, was conducted from 2000 to 2010. Information was recorded regarding the age, sex, clinical status, WHO classification, treatment, presence of reactions and coinfections. Focal and systemic infections were diagnosed based on the history, physical examination, and laboratory tests. Multinomial logistic regression was used to evaluate the associations between the leprosy reactions and the patients' gender, age, WHO classification and coinfections.

RESULTS

Two hundred twenty-five patients were studied. Most of these patients were males (155/225 = 68.8%) of an average age of 49.31±15.92 years, and the most prevalent clinical manifestation was the multibacillary (MB) form (n = 146), followed by the paucibacillary (PB) form (n = 79). Erythema nodosum leprosum (ENL) was more prevalent (78/122 = 63.9%) than the reversal reaction (RR) (44/122 = 36.1%), especially in the MB patients (OR 5.07; CI 2.86-8.99; p<0.0001) who exhibited coinfections (OR 2.26; CI 1.56-3.27; p<0.0001). Eighty-eight (88/225 = 39.1%) patients exhibited coinfections. Oral coinfections were the most prevalent (40/88 = 45.5%), followed by urinary tract infections (17/88 = 19.3%), sinusopathy (6/88 = 6.8%), hepatitis C (6/88 = 6.8%), and hepatitis B (6/88 = 6.8%).

CONCLUSIONS

Coinfections may be involved in the development and maintenance of leprosy reactions.

Immune Reconstitution Inflammatory Syndrome

Immune reconstitution inflammatory syndrome (IRIS) is a phenomenon observed in patients recovering from immunodeficiency. The clinical presentation of IRIS involves the unmasking of covert infections or the worsening of overt conditions. Several causes and pathways have been suggested, most recognizing an inflammatory flare component occurring in the context of rapid immune reconstitution. In HIV-infected patients, IRIS inadvertently occurs as the consequence of successful antiretroviral therapy, and it is affiliated with improvement of the immune function, complicating the course of the disease and presenting treatment challenges to clinicians. The pathogenesis of IRIS is poorly understood, but in recovering HIV patients, its initiation and progression seem to be primarily linked to an increase in CD4+ T-helper and CD8+ T-suppressor cell count and a reduction in T-regulatory cells, all endorsed by exaggerated cytokine release and activity. The clinical presentation of IRIS is usually atypical. The manifestations depend on the trigger antigen, which can be an infective agent (viable or nonviable), a host antigen, or a tumor antigen. Most IRIS cases are self-limiting, but a few cases can be overwhelming and life-threatening; hence, early recognition is important. In most cases, there is no need to discontinue the antiretroviral therapy, although in the more severe cases, other clinical intervention may be necessary.

Reactions following completion of 1 and 2 year multidrug therapy (MDT)

We evaluated the incidence, severity, and duration of reactional states in 139 multibacillary (MB) leprosy patients in the first 2 years after the completion of the 1 year regimen of multidrug therapy (MDT) currently recommended by the World Health Organization (WHO) and compared those findings with 295 MB leprosy patients treated with the same regimen previously recommended for 2 years. During the first year after the completion of 1 year MDT, patients experienced 1 or more reactional states 27% of the time, the vast majority being lepra type 1 reactions (reversal reactions, RR), whereas patients who received 2 year MDT experienced a reactional state during that time period only 8% of the time (P < 0.001). Furthermore, during the first year after the completion of therapy, and during the first 2 years, both the number of reactional states and reversal reactions were significantly (P < or = 0.004) more frequent, severe, of longer duration, and more commonly associated with neuritis.

Pulmonary complications of immune reconstitution inflammatory syndromes in HIV-infected patients

Immune reconstitution inflammatory syndrome (IRIS) describes a paradoxical worsening of clinical status related to recovery of the immune system, as can occur after the initiation of highly active antiretroviral therapy (HAART) in HIV-infected patients. Most commonly, IRIS results from opportunistic infections that can unmask or develop paradoxical worsening following HAART. Cancers, autoimmune conditions and sarcoidosis have also been associated with IRIS. Pulmonary complications may be frequently encountered. This article reviews the types and clinical presentation of IRIS, with a focus on the pulmonary manifestations. Management and outcome of IRIS are considered.

[Human immunodeficiency virus and AIDS-associated immune reconstitution syndrome. State of the art]

Since the arrival of highly active antiretroviral therapy (HAART), immune reconstitution syndrome (IRS) has become an increasingly more frequent complication in patients with human immunodeficiency virus (HIV) infection. This article presents a review of the available evidence on this subject, indexed in MEDLINE-PUBMED, BVS-BIREME, and BioMed Central. The review covers the definition, epidemiology, classification, and diagnostic criteria related to IRS. In addition, the clinical particularities of the most frequent etiologies are described, and a proposal for a therapeutic approach is formulated. The prognosis and future implications of this syndrome in the epidemiology of some infectious illnesses in the HIV-positive population are included. Several unresolved aspects are mentioned, such as those related to the pathophysiology of the condition, use of biomarkers for the diagnosis, and the need for evidence-based therapeutic algorithms to enable standardization of treatment for these patients.

Association of tumor necrosis factor alpha, interferon gamma and interleukin 10 gene polymorphisms with peripheral neuropathy in South Indian patients with type 2 diabetes

Diabetic peripheral neuropathy (DPN) is a major global health threat and a common complication of diabetes. Peripheral nerve complications due to irregular cytokine production are eminent factors in many inflammatory diseases. The present study focused on gene polymorphisms of pro and anti-inflammatory cytokines that may be responsible for nerve damage in diabetic neuropathy. We examined three common functional SNPs primarily at the positions on genes of tumor necrosis alpha (TNFalpha) -308G/A, interferon gamma (IFNgamma) +874A/T and interleukin (IL) 10 -1082G/A in order to establish their association with peripheral neuropathy in type 2 diabetes.

RESULTS

Genotypic frequencies obtained from TNFalpha -308G/A gene analysis in DPN group comprised 86.4% of G/A, 10.6% of G/G and 3% of A/A genotype, where as the control group had 94% of G/A, 2% of G/G and 4% of A/A which could not reach the statistical significance with the disease after Bonferroni correction. The IFNgamma +874 A/T polymorphism in patient group revealed 33.3% of A/A, 47.5% of A/T and 19.2% of T/T genotype. The A/A genotype had attained statistical significance of P=0.04 (P corrected); OR 2; 95% CI 1.14-3.64 when compared to controls. The IL10 -1082 G/A polymorphism in the patient group has showed 62.6% of A/A, 21.2% of G/A, 16.2% of G/G genotype, revealing significant association with G/G genotype (P<0.01, OR 2.9; 95% CI 1.47-5.84) when compared to controls.

CONCLUSION

Our findings indicate that the tested markers within the IFNgamma and IL-10 genes, but not the TNFalpha gene, are significantly associated with peripheral neuropathy in South Indian type 2 diabetic patients. The study shows that the 'high-producer' IL-10 -1082 G/G genotype and the 'low-producer' IFNgamma +874 A/A genotype may be responsible for the down regulation of immune response leading to inflammation in this setting.

Single lesion multibacillary leprosy, a treatment enigma: a case report

Introduction

Leprosy exhibits a wide spectrum of presentation, varying from the tuberculoid to the lepromatous pole, with immunologically unstable borderline forms in-between, depending upon the immune status of the individual. The clinical system of classification for the purpose of treatment includes the number of skin lesions and nerves involved as the basis for classifying the patients into multibacillary and paucibacillary.

Case presentation

A 20-year-old man belonging to a moderately endemic leprosy area in the Terai region of Nepal reported a large single, hypopigmented, well defined anaesthetic lesion on his left thigh extending to his knee which had been present for 2 years. There was no other nerve involvement. Clinical diagnosis was tuberculoid leprosy and immunological lateral flow test for anti-Phenolic glycolipid-I antibody was positive. Six months of paucibacillary multidrug treatment was advised immediately. However, the patient was reclassified as multibacillary on the basis of a positive skin smear and appropriate treatment of 24 months multibacillary multidrug regimen was commenced after only 1 week. Slit skin smear examination for Mycobacterium leprae from the lesion revealed a bacterial index of 4+ while it was negative from the routine sites. Histopathological examination from skin biopsy of the lesion further supported the bacterial index of the lesion granuloma which was 2+ and the patient was diagnosed as borderline tuberculoid. Bacteriological, histological, and immunological findings of this patient were borderline tuberculoid leprosy and he should have been treated with multibacillary regimen from the beginning. Five months after commencement of treatment, the patient developed a leprae reaction of Type 1 or reversal reaction with some nerve function impairment and enlargement of the lateral popliteal nerve of the left leg. This reversal reaction was managed by standard oral prednisolone whilst continuing the multibacillary multidrug regimen.

Conclusion

This case illustrates and emphasizes the importance of slit-skin smear and biopsy as routine in all new cases to help differentiate multibacillary from paucibacillary for correct treatment. It further suggests that there are factors yet undetermined which play a significant role in determining the host response to M. leprae which is a remaining challenge in this disease.

A randomized clinical trial of oral steroids for ulnar neuropathy in type 1 and type 2 leprosy reactions

BACKGROUND: Steroids regimens in leprosy neuropathies are still controversial in botth types of reactions. METHOD: For this trial, 21 patients with ulnar neuropathy were selected from 163 leprosy patients, 12 with type 1 reaction (T1R) and nine with type 2 (T2R). One experimental group started with prednisone 2 mg/kg/day and the control group with 1 mg/kg/day. A clinical score based on tests for spontaneous pain, nerve palpation, sensory and muscle function was used. Neurophysiological evaluation consisted on the motor nerve conduction of the ulnar nerve in three segments. Student "t" test for statistical analysis was applied on the results: before treatment, first week, first month and sixth month, between each regimen and types of reaction. CONCLUSION: In both reactions during the first month higher doses of steroids produced better results but, earlier treatment with lower dose was as effective. Short periods of steroid, 1 mg/Kg/day at the beginning and,tapering to 0,5 mg/Kg/day or less in one month turned out to be efficient in T2R.

[Immune reconstitution inflammatory syndrome (IRIS)]

Overwhelming immune reaction resulting in granulomatous inflammation after infection with opportunistic pathogens has been termed immune reconstitution inflammatory syndrome (IRIS). IRIS has mainly been described in patients with human immunodeficiency virus (HIV). However, IRIS is not restricted to HIV-patients and may occur in other infections and immunodeficiencies. In our clinic, we experienced a Whipple's disease patient with IRIS. IRIS occurs mainly after initiation of the highly active anti-retroviral therapy (HAART). Soon after HAART initiation, a marked inflammatory reaction can occur, triggered by restoration of pathogen-specific immunity. IRIS may be targeted by various infective antigens, dead or dying infective antigens, host antigens, tumor antigens and other antigens, giving rise to a heterogenous range of clinical manifestations. Treatment should be optimized for the associated condition and initiated immediately. Glucocorticoids should be used in patients who are severely affected by IRIS.

Serum levels of interferon-gamma, tumour necrosis factor-alpha, soluble interleukin-6R and soluble cell activation markers for monitoring response to treatment of leprosy reactions

Identifying pathogen and host-related laboratory parameters are essential for the early diagnosis of leprosy reactions. The present study aimed to clarify the validity of measuring the profiles of serum cytokines [interleukin (IL)-4, IL-6, IL-10, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha], the soluble IL-6 receptor (sIL-6R), soluble T cell (sCD27) and macrophage (neopterin) activation markers and Mycobacterium leprae-specific anti-PGL-I IgM antibodies in relation to the leprosy spectrum and reactions. Serum samples from 131 Indonesian leprosy patients (82 non-reactional leprosy patients and 49 reactional) and 112 healthy controls (HC) from the same endemic region were investigated. Forty-four (89.8%) of the reactional patients had erythema nodosum leprosum (ENL) while only five (10.2%) had reversal reaction (RR). Follow-up serum samples after corticosteroid treatment were also obtained from 17 of the patients with ENL and one with RR. A wide variability in cytokine levels was observed in the patient groups. However, IFN-gamma and sIL-6R were elevated significantly in ENL compared to non-ENL patients. Levels of IFN-gamma, TNF-alpha and sIL-6R declined significantly upon corticosteroid treatment of ENL. Thus, although the present study suggests limited applicability of serial measurement of IFN-gamma, TNF-alpha and sIL-6R in monitoring treatment efficacy of ENL, reactions it recommends a search for a wider panel of more disease-specific markers in future studies.

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.

Immune reconstitution inflammatory syndrome: more answers, more questions

The institution of highly active antiretroviral therapy (HAART) in HIV-infected patients restores protective immune responses against a wide variety of pathogens and dramatically decreases mortality. In a subset of patients receiving HAART, immune reconstitution is associated with a pathological inflammatory response leading to substantial short-term morbidity and even mortality. The past several years have seen marked advances in our clinical understanding of the immune reconstitution inflammatory syndrome (IRIS), but many questions remain. This article summarizes recent data on clinical risk factors for the development of IRIS. A consistent finding from multiple groups is that IRIS develops in a substantial percentage of HIV-infected patients who have an underlying opportunistic infection and receive HAART. As the use of HAART stands to markedly increase over the next several years, optimal care of patients receiving HAART will need to incorporate monitoring for and treating complications of IRIS.

Effects of prednisolone treatment on cytokine expression in patients with leprosy type 1 reactions

Leprosy type 1 reactions (T1R) are due to increased cell-mediated immunity and result in localized tissue damage. The anti-inflammatory drug prednisolone is used for treatment, but there is little good in vivo data on the molecular actions of prednisolone. We investigated the effect of prednisolone treatment on tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-10, and transforming growth factor beta1 (TGF-beta1) mRNA and protein expression in blood and skin biopsies from 30 patients with T1R in India. After 1 month of prednisolone treatment the sizes of the skin granulomas were reduced, as were the grades of cells positive for TNF-alpha and IL-10 in skin lesions. Increased production of TGF-beta1 was seen in skin lesions after 6 months of prednisolone treatment. Expression of mRNA for TNF-alpha, IL-1beta, and TGF-beta1 was reduced, whereas no change in IL-10 mRNA expression was detected during treatment. The circulating cytokine profiles were similar in patients with and without T1R, and prednisolone treatment had no detectable effects on cytokine expression in the blood. The data emphasize the compartmentalization of pathology in T1R and the importance of the immune response in the skin. Clinical improvement and cytokine expression were compared. Surprisingly, patients with improved skin and nerve function and patients with nonimproved skin and nerve function had similar cytokine profiles, suggesting that clinical improvement is not directly mediated by the cytokines studied here. This in vivo well-controlled study of the immunosuppressive effects of prednisolone showed that the drug does not switch off cytokine responses effectively.

Leprosy

Leprosy remains an important health problem worldwide. The disease is caused by a chronic granulomatous infection of the skin and peripheral nerves with Mycobacterium leprae. The clinical range from tuberculoid to lepromatous leprosy is a result of variation in the cellular immune response to the mycobacterium. The resulting impairment of nerve function causes the disabilities associated with leprosy. This review summarises recent advances in understanding of the biology of leprosy, clinical features of the disease, the current diagnostic criteria, and the new approaches to treatment of the infection and the immune-mediated complications. Supervised multi-drug therapy (MDT) for fixed durations is highly effective for all forms of the disease. The widespread implementation of MDT has been associated with a fall in the prevalence of the leprosy but as yet no reduction in the case-detection rate globally. Thus, leprosy control activities must be maintained for decades to interrupt transmission of infection.

Leprosy: current diagnostic and treatment approaches

PURPOSE OF REVIEW

Leprosy remains an important problem globally and leprosy patients may present to physicians outside leprosy endemic areas. We review the recent biological and clinical advances in leprosy.

RECENT FINDINGS

Sequencing the genome has been a major biological advance and will open up new possibilities for research. The three cardinal criteria (anaesthetic skin patches, thickened nerves and acid-fast bacilli in skin smears) have not yet been bettered. Multidrug therapy for leprosy is highly effective with low relapse rates though the optimal duration of therapy for multibacillary patients is unclear. Nerve damage remains a significant problem (in some series only 50% responding to steroid therapy). New treatments for leprosy reactions are needed. Stigma remains a problem but is being combated by patient groups.

SUMMARY

Far from being eliminated as a public health problem, leprosy still causes a considerable long-term morbidity in both the developing and developed world. New treatments for leprosy reactions are needed and the optimal length of multidrug therapy required further research.