Leprosy pathogenetic background: a review and lessons from other mycobacterial diseases

High-resolution ultrasonography for early diagnosis of neural impairment in seropositive leprosy household contacts

Leprosy household contacts (HC) represent a high-risk group for the development of the disease. Anti-PGL-I IgM seropositivity also increases the risk of illness. Despite significant advances in leprosy control, it remains a public health problem; and early diagnosis of this peripheral neuropathy represents one of the main goals of leprosy programs. The present study was performed to identify neural impairment in leprosy HC by analyzing differences in high-resolution ultrasonographic (US) measurements of peripheral nerves between leprosy HC and healthy volunteers (HV). Seventy-nine seropositive household contacts (SPHC) and 30 seronegative household contacts (SNHC) underwent dermato-neurological examination and molecular analysis, followed by high-resolution US evaluation of cross-sectional areas (CSAs) of the median, ulnar, common fibular and tibial nerves. In addition, 53 HV underwent similar US measurements. The US evaluation detected neural thickening in 26.5% (13/49) of the SPHC and only in 3.3% (1/30) among the SNHC (p = 0.0038). The CSA values of the common fibular and tibial nerves were significantly higher in SPHC. This group also had significantly greater asymmetry in the common fibular and tibial nerves (proximal to the tunnel). SPHC presented a 10.5-fold higher chance of neural impairment (p = 0.0311). On the contrary, the presence of at least one scar from the BCG vaccine conferred 5.2-fold greater protection against neural involvement detected by US (p = 0.0184). Our findings demonstrated a higher prevalence of neural thickening in SPHC and support the role of high-resolution US in the early diagnosis of leprosy neuropathy. The combination of positive anti-PGL-I serology and absence of a BCG scar can identify individuals with greater chances of developing leprosy neuropathy, who should be referred for US examination, reinforcing the importance of including serological and imaging methods in the epidemiological surveillance of leprosy HC.

Silent peripheral neuropathy determined by high-resolution ultrasound among contacts of patients with Hansen's disease

Introduction

Hansen's disease (HD) primarily infects peripheral nerves, with patients without HD being free of peripheral nerve damage. Household contacts (HHCs) of patients with HD are at a 5-10 times higher risk of HD than the general population. Neural thickening is one of the three cardinal signs that define a case of HD according to WHO guidelines, exclusively considering palpation examination that is subjective and may not detect the condition in the earliest cases even when performed by well-trained professionals. High-resolution ultrasound (HRUS) can evaluate most peripheral nerves, a validated technique with good reproducibility allowing detailed and accurate examination.

Objective

This study aimed to use the peripheral nerve HRUS test according to the HD protocol as a diagnostic method for neuropathy comparing HHCs with healthy volunteers (HVs) and patients with HD.

Methods

In municipalities from 14 different areas of Brazil we selected at random 83 HHC of MB-patients to be submitted to peripheral nerve ultrasound and compared to 49 HVs and 176 HD-patients.

Results

Household contacts assessed by HRUS showed higher median and mean absolute peripheral nerve cross-sectional area (CSA) values and greater asymmetries (ΔCSA) compared to HVs at the same points. Median and mean absolute peripheral nerve CSA values were higher in patients with HD compared to HCCs at almost all points, while ΔCSA values were equal at all points. Mean ± SD focality (ΔTpT) values for HHCs and patients with HD, respectively, were 2.7 ± 2.2/2.6 ± 2.2 for the median nerve, 2.9 ± 2.7/3.3 ± 2.9 for the common fibular nerve (p > 0.05), and 1.3 ± 1.3/2.2 ± 3.9 for the ulnar nerve (p < 0.0001).

Discussion

Considering HRUS findings for HHCs, asymmetric multiple mononeuropathy signs (thickening or asymmetry) in at least 20% of the nerves evaluated could already indicates evidence of HD neuropathy. Thus, if more nerve points are assessed in HHCs (14 instead of 10), the contacts become more like patients with HD according to nerve thickening determined by HRUS, which should be a cutting-edge tool for an early diagnosis of leprosy cases.

Prolonged delays in leprosy case detection in a leprosy hot spot setting in Eastern Ethiopia

Background

Leprosy or Hansen’s disease is known to cause disability and disfigurement. A delay in case detection of leprosy patients can lead to severe outcomes. In Ethiopia, the disability rates caused by leprosy among new cases are relatively high compared to other endemic countries. This suggests the existence of hidden leprosy cases in the community and a delay in timely detection. To reduce disability rates, it is crucial to identify the factors associated with this delay. This study aimed to determine the extent of delay in case detection among leprosy cases in Eastern Ethiopia.

Methods

This cross-sectional explorative study was conducted in January and February 2019 among 100 leprosy patients diagnosed ≤6 months prior to inclusion. A structured questionnaire was used to collect data, including the initial onset of symptoms, and the reasons for delayed diagnosis. Descriptive statistics, including percentages and medians, were used to describe the case detection delay. Logistic regression analysis was carried out to evaluate the predictors of delay in case detection of >12 months.

Findings

The median age of patients was 35 years, with a range of 7 to 72 years. The majority were male (80%) and rural residents (90%). The median delay in case detection was 12 months (interquartile range 10–36 months) among the included patients. The mean delay in case detection was 22 months, with a maximum delay of 96 months. The overall prevalence of disability among the study population was 42% (12% grade I and 30% grade II). Fear of stigma (p = 0.018) and experiencing painless symptoms (p = 0.018) were highly associated with a delay in case detection of >12 months.

Conclusions

Being afraid of stigma and having painless symptoms, which are often misinterpreted as non-alarming at the onset of the disease, were associated with a delay in case detection. This study showed the need to increase knowledge on early symptoms of leprosy among affected communities. Furthermore, it is important to support initiatives that reduce leprosy related stigma and promote health worker training in leprosy control activities.

Leprosy, also called Hansen’s disease, is a chronic infectious disease that may result in devastating disabilities. The disability rate among new leprosy patients in Ethiopia is high compared to other countries. A delay in case detection is a major factor contributing to the development of disability. Late diagnosis also fosters ongoing transmission, increasing the incidence of the disease. We aimed to determine the extent of the detection delay and find the reasons for this delay in eastern Ethiopian districts, endemic for leprosy. One hundred leprosy patients who recently started multi-drug therapy were included in the study. The median detection delay was one year among all patients. About half of the patients had sought treatment from health institutions within one year after the onset of their first symptoms. Longer delays among leprosy patients were associated with a fear of stigma and painless symptoms at an early stage of the disease. This indicates that it is vital to improve community knowledge of leprosy symptoms and to take initiatives that reduce stigma. This should improve health-seeking behaviour and may prevent the development of disability as well as halt transmission.

Association of the polymorphism of the vitamin D receptor gene (VDR) with the risk of leprosy in the Brazilian Amazon

The transmission and evolution of leprosy depends on several aspects, including immunological and genetic factors of the host, as well as genetic factors of Mycobacterium leprae. The present study evaluated the association of single nucleotide polymorphisms (SNPs) on the FokI (rs2228570), TaqI (rs731236), ApaI (rs7975232) regions of the vitamin D receptor (VDR) gene with leprosy. A total of 405 individuals were evaluated, composed by groups of 100 multibacillary (MB) and 57 paucibacillary (PB) patients, and 248 healthy contacts. Blood samples were collected from patients and contacts. The genotyping was performed by sequencing of the interest regions. The alleles of the studied SNPs, and SNP FokI genotypes, were not associated with leprosy. For the SNP on TaqI region, the relationship between the tt genotype, and for the SNP ApaI, the AA genotype, revealed an association with susceptibility to MB form, while Aa genotype with protection. The extended genotypes AaTT and AaTt of ApaI and TaqI were associated with protection against MB form. Further studies analyzing the expression of the VDR gene and the correlation with its SNPs might help to clarify the role of polymorphisms on the immune response in leprosy.

Correlation of Plasma Level of Insulin-Like Growth Factor-1 (IGF-1) with Bacterial Index on Leprosy Patients in Bali

Background

Leprosy is an infection by Mycobacterium leprae, which influenced by cellular immunity. Leprosy tends to occur in low socio-economic and nutrition groups. Researchers try to prove the role of nutrition in the pathogenesis of leprosy. Insulin-like growth factor-1 (IGF-1) as a marker of nutritional status shown to play a role in cellular immunity.

Objective

To evaluate the correlation between IGF-1 with bacterial index (BI) on leprosy patients in Bali.

Methods

Cross-sectional study in Sanglah Public General Hospital, Denpasar of patients with paucibacillary (PB) and multibacillary (MB) leprosy were assessed for BI using slit-skin smear. All patients were tested for plasma IGF-1 using chemiluminescent immunometric assay Immulite. All data were analyzed using IBM SPSS ver. 24.0. The study has been approved by local Institutional Review Board with ethical clearance number 2017.02.1.0356.

Results

Our study involved 44 MB and 2 PB leprosy. The common age group affected was between 31~40 years old (23.9%), male (60.9%), and normal body mass index (BMI) (65.2%). Mean plasma IGF-1 level in PB leprosy was higher (91.07±0.74 ng/ml) than MB (82.74±6.44 ng/ml). The mean IGF-1 level decreases as BI increases in both groups (CI 95%=81.16~85.04; p<0.001). Pearson correlation test shows strong negative correlation (Pearson r=−0.976; p<0.001) with determinant coefficient (R₂) showing 95.2% (p<0.001).

Conclusion

In Balinese leprosy patients, severity of disease status measured by BI were found to be strongly correlated with the plasma IGF-1 level which may help preventing transmission in household contacts by improving nutritional status.

Biomarkers for Detecting Resilience against Mycobacterial Disease in Animals

Paratuberculosis and bovine tuberculosis are two mycobacterial diseases of ruminants which have a considerable impact on livestock health, welfare, and production. These are chronic "iceberg" diseases which take years to manifest and in which many subclinical cases remain undetected. Suggested biomarkers to detect infected or diseased animals are numerous and include cytokines, peptides, and expression of specific genes; however, these do not provide a strong correlation to disease. Despite these advances, disease detection still relies heavily on dated methods such as detection of pathogen shedding, skin tests, or serology. Here we review the evidence for suitable biomarkers and their mechanisms of action, with a focus on identifying animals that are resilient to disease. A better understanding of these factors will help establish new strategies to control the spread of these diseases.

Quantitative PCR for leprosy diagnosis and monitoring in household contacts: A follow-up study, 2011-2018

Household contacts (HHC) of leprosy patients exhibit high-risk of developing leprosy and contact tracing is helpful for early diagnosis. From 2011 to 2018,2,437 HHC were examined in a clinic in Rio de Janeiro, Brazil and 16S qPCR was used for diagnosis and monitoring of contacts. Fifty-four HHCs were clinically diagnosed with leprosy at intake. Another 25 exhibited leprosy-like skin lesions at intake, 8 of which were confirmed as having leprosy (50% of which were qPCR positive) and 17 of which were diagnosed with other skin diseases (6% qPCR positive). In skin biopsies, qPCR presented a sensitivity of 0.50 and specificity of 0.94. Furthermore, 955 healthy HHCs were followed-up for at least 3 years and skin scrapings were collected from earlobes for qPCR detection. Positive qPCR indicated a non-significant relative risk of 2.52 of developing the disease. During follow-up, those who progressed towards leprosy exhibited 20% qPCR positivity, compared to 9% of those who remained healthy. Disease-free survival rates indicated that age had a significant impact on disease progression, where patients over 60 had a greater chance of developing leprosy [HR = 32.4 (3.6-290.3)]. Contact tracing combined with qPCR may assist in early diagnosis and age is a risk factor for leprosy progression.

Evaluation of the cutaneous sensation of the face in patients with different clinical forms of leprosy

Background

Leprosy can be considered to be the most common peripheral neuropathy of infectious etiology and constitutes a public health problem. The standard routine examination for assessing sensory impairment in leprosy neuropathy basically evaluates hands, feet and eyes. However, evaluation of facial cutaneous sensation is not routinely performed.

Objectives

The aim of this study was to evaluate facial cutaneous sensation in patients with different clinical forms of leprosy and compare the findings with those from healthy individuals.

Methodology

19 healthy controls and 71 leprosy patients who were being treated at a national reference center for leprosy in Brazil underwent facial sensation assessment using the Semmes-Weinstein monofilament test. This test was applied over the facial areas corresponding to the ophthalmic, maxillary and mandibular distal branches of the trigeminal nerve.

Results

The predominant clinical form in terms of changes to facial cutaneous sensation was lepromatous leprosy (LL), followed by the borderline-borderline (BB), and borderline-lepromatous (BL) forms, in comparison with healthy individuals. The distal branches most affected were the zygomatic (28.2%; 20/71), buccal (23.9%; 17/71) and nasal (22.5%; 16/71). There was asymmetrical sensory impairment of the face in 62.5% (20/32) of the cases.

Conclusion

The face is just as impaired in leprosy as are the feet, hands and eyes, but facial impairment is underdiagnosed. Our evaluation on the different sensory branches and evidence of asymmetrical impairment of the face confirm the classically described pattern of leprosy neuropathy, i.e. consisting of asymmetrical and predominantly sensory peripheral neuropathy.

Molecular, immunological and neurophysiological evaluations for early diagnosis of neural impairment in seropositive leprosy household contacts

Background

Household contacts constitute the highest risk group for leprosy development, and despite significant progress in the disease control, early diagnosis remains the primary goals for leprosy management programs.

Methods

We have recruited 175 seropositive and 35 seronegative household contacts from 2014 to 2016, who were subjected to an extensive protocol that included clinical, molecular (peripheral blood qPCR, slit-skin smear qPCR, skin biopsy qPCR) and electroneuromyographic evaluations.

Results/Principal findings

The positivity of peripheral blood qPCR of seropositive contacts was 40.6% (71/175) whereas only 8.6% (3/35) were qPCR positive in seronegative contacts (p = 0.0003). For the slit-skin smear, only 4% (7/175) of seropositive contacts presented positive bacilloscopy, whereas the qPCR detected 47.4% (83/175) positivity in this group compared with only 17.1% (6/35) in seronegative contacts (p = 0.0009). In the ENMG evaluation of contacts, 31.4% (55/175) of seropositives presented some neural impairment, and 13.3% (4/35) in seronegatives (p = 0.0163). The presence of neural thickening conferred a 2.94-fold higher chance of ENMG abnormality (p = 0.0031). Seropositive contacts presented a 4.04-fold higher chance of neural impairment (p = 0.0206). The peripheral blood qPCR positivity presented odds 2.08-fold higher towards neural impairment (OR, 2.08; p = 0.028). Contrarily, the presence of at least one BCG vaccine scar demonstrated 2.44-fold greater protection against neural impairment (OR = 0.41; p = 0.044).

Conclusions/Significance

ELISA anti-PGL-I is the most important test in determining the increased chance of neural impairment in asymptomatic leprosy household contacts. The combination of the two assays (ELISA anti-PGL-I and peripheral blood qPCR) and the presence of BCG scar may identify individuals with higher chances of developing leprosy neuropathy, corroborating with the early diagnosis and treatment.

Despite the apparent progress observed in recent years in leprosy control, early identification of cases remains one of the primary objectives of control programs. In addition, the failure of the current therapeutic scheme on the incidence of leprosy demonstrates that the disease elimination as a public health program promoted by the World Health Organization (WHO) depends on an incisive action to interrupt its transmission chain. The long incubation period of leprosy, its insidious symptoms and signs may difficult its diagnosis. Several studies have recently demonstrated that IgM anti-PGL-I seropositive contacts present higher chances to become ill than seronegative ones. Therefore, our question was: do seropositive contacts at greater risk of becoming sick already present subclinical neural damage? Therefore, our approach was to analyse anti-PGL-I seropositive contacts through electroneuromyography. The development and implementation of more specific and sensitive methods for the detection of M. leprae and its neural impairment, using immunological, molecular and neurophysiological tools are mandatory to increase the knowledge of leprosy epidemiology, to break its chain of transmission, thereby enabling effective control of this disease. This report demonstrated that seropositive contacts is the population group with higher chances of neural impairment.

Response of iNOS and its relationship with IL-22 and STAT3 in macrophage activity in the polar forms of leprosy

Leprosy is a chronic granulomatous infection that manifests as different clinical forms related to the immunological response. The aim of the study was to evaluated the response of IL-22, STAT3, CD68 and iNOS in leprosy skin lesions. The mean number IL-22 positive cells was 12.12±1.90cells/field in the TT form and 31.31±2.91cells/field in the LL form. STAT3 positive cells was 5.29±1.96 cells/field in the TT form, while this number was 11.13±3.48cells/field in the LL form. The mean number of CD68 positive cells was 25.18±6.21cells/field in the TT form and 62.81±8.13cells/field in the LL form. Quantitative analysis of iNOS revealed a significant difference, with the mean number of cells expressing the enzyme being 30.24±2.88cells/field in the TT form compared to 35.44±4.69cells/field in the LL form. Linear correlations in lesions of TT patients showed a moderate positive correlations between CD68 and iNOS, STAT3 and Inos, IL-22 and STAT3, and IL-22 and iNOS. Our results demonstrate that these factors can act synergistically to induce a microbicidal activity in the population of macrophages in the leprosy lesions.

Risk-benefit assessment of Bacillus Calmette-Guérin vaccination, anti-phenolic glycolipid I serology, and Mitsuda test response: 10-year follow-up of household contacts of leprosy patients

INTRODUCTION

Despite multidrug therapy, leprosy remains a public health issue. The intradermal Bacillus Calmette-Guérin (BCG) vaccine, Mitsuda test (lepromin skin test), and anti-phenolic glycolipid I (PGL-I) serology are widely used in leprosy studies and have shown great epidemiological value.

METHODS

This longitudinal study evaluated the relative risks and benefits of these three tools by comparing results observed in household contacts (HHCs) of leprosy patients who developed leprosy with those of HHCs who did not in a population of 2,992 individuals monitored during a 10-year period.

RESULTS

Seventy-five (2.5%) new leprosy cases were diagnosed, including 28 (0.9%) co-prevalent cases. Therefore, for the risk-benefit assessment, 47 (1.6%) HHCs were considered as truly diagnosed during follow-up. The comparison between healthy and affected contacts demonstrated that not only did BCG vaccination increase protection, but boosters also increased to 95% relative risk (RR) reduction when results for having two or more scars were compared with having no scars [RR, 0.0459; 95% confidence interval (CI), 0.006-0.338]. Similarly, Mitsuda reactions >7mm in induration presented 7-fold greater protection against disease development compared to reactions of 0-3mm (RR, 0.1446; 95% CI, 0.0566-0.3696). In contrast, anti-PGL-I ELISA seropositivity indicated a 5-fold RR increase for disease outcome (RR, 5.688; 95% CI, 3.2412-9.9824). The combined effect of no BCG scars, Mitsuda reaction of <7mm, and seropositivity to anti-PGL-I increased the risk for leprosy onset 8-fold (RR, 8.109; 95% CI, 5.1167-12.8511).

CONCLUSIONS

The adoption of these combined assays may impose measures for leprosy control strategies.

T regulatory cells (TREG)(TCD4+CD25+FOXP3+) distribution in the different clinical forms of leprosy and reactional states

BACKGROUND

Leprosy is characterized histologically by a spectrum of different granulomatous skin lesions, reflecting patients' immune responses to Mycobacterium leprae. Although CD4+CD25+ FoxP3+ T regulatory cells are pivotal in the immuneregulation, presence, frequency, and distribution of Tregs in leprosy, its reactional states have been investigated in few studies.

OBJECTIVES

This study aimed to verify the frequency and distribution of regulatory T cells in different clinical forms and reactional states of leprosy.

METHODS

We performed an immunohistochemical study on 96 leprosy cases [Indeterminate (I): 9 patients; tuberculoid tuberculoid: 13 patients; borderline tuberculoid: 26 patients; borderline borderline: 3 patients; borderline lepromatous: 8 patients; lepromatous lepromatous: 27 patients; reversal reaction: 8 patients; and erythema nodosum leprosum: 2 patients].

RESULTS

FoxP3-positive cells were present in 100% of the cases with an average density of 2.82% of the infiltrate. Their distribution was not related to granulomatous structures or special locations. There was a statistically significant increment of FoxP3 expression in patients with leprosy reversal reactions when compared with patients presenting with type I leprosy (P= 0.0228); borderline tuberculoid leprosy (P = 0.0351) and lepromatous leprosy (P = 0.0344).

CONCLUSIONS

These findings suggest that Tregs play a relevant role in the etiopathogenesis of leprosy, mainly in type I leprosy reaction.

Use of Approximate Bayesian Computation to Assess and Fit Models of Mycobacterium leprae to Predict Outcomes of the Brazilian Control Program

Hansen's disease (leprosy) elimination has proven difficult in several countries, including Brazil, and there is a need for a mathematical model that can predict control program efficacy. This study applied the Approximate Bayesian Computation algorithm to fit 6 different proposed models to each of the 5 regions of Brazil, then fitted hierarchical models based on the best-fit regional models to the entire country. The best model proposed for most regions was a simple model. Posterior checks found that the model results were more similar to the observed incidence after fitting than before, and that parameters varied slightly by region. Current control programs were predicted to require additional measures to eliminate Hansen's Disease as a public health problem in Brazil.

Unveiling healthy carriers and subclinical infections among household contacts of leprosy patients who play potential roles in the disease chain of transmission

Leprosy transmission still occurs despite the availability of highly effective treatment. The next step towards successfully eliminating leprosy is interrupting the chain of transmission of the aetiological agent, Mycobacterium leprae. In this investigation, we provide evidence that household contacts (HHCs) of leprosy patients might not only have subclinical infections, but may also be actively involved in bacilli transmission. We studied 444 patients and 1,352 contacts using anti-phenolic glycolipid-I (PGL-I) serology and quantitative polymerase chain reaction (qPCR) to test for M. leprae DNA in nasal swabs. We classified the patients according to the clinical form of their disease and the contacts according to the characteristics of their index case. Overall, 63.3% and 34.2% of patients tested positive by ELISA and PCR, respectively. For HHCs, 13.3% had a positive ELISA test result and 4.7% had a positive PCR test result. The presence of circulating anti-PGL-I among healthy contacts (with or without a positive PCR test result from nasal swabs) was considered to indicate a subclinical infection. DNA detected in nasal swabs also indicates the presence of bacilli at the site of transmission and bacterial entrance. We suggest that the concomitant use of both assays may allow us to detect subclinical infection in HHCs and to identify possible bacilli carriers who may transmit and disseminate disease in endemic regions. Chemoprophylaxis of these contacts is suggested.

Active surveillance of Hansen's Disease (leprosy): importance for case finding among extra-domiciliary contacts

Hansen's disease (leprosy) remains an important health problem in Brazil, where 34,894 new cases were diagnosed in 2010, corresponding to 15.3% of the world's new cases detected in that year. The purpose of this study was to use home visits as a tool for surveillance of Hansen's disease in a hyperendemic area in Brazil. A total of 258 residences were visited with 719 individuals examined. Of these, 82 individuals had had a previous history of Hansen's disease, 209 were their household contacts and 428 lived in neighboring residences. Fifteen new Hansen's disease cases were confirmed, yielding a detection rate of 2.0% of people examined. There was no difference in the detection rate between household and neighbor contacts (p = 0.615). The two groups had the same background in relation to education (p = 0.510), household income (p = 0.582), and the number of people living in the residence (p = 0.188). Spatial analysis showed clustering of newly diagnosed cases and association with residential coordinates of previously diagnosed multibacillary cases. Active case finding is an important tool for Hansen's disease control in hyperendemic areas, enabling earlier diagnosis, treatment, decrease in disability from Hansen's disease and potentially less spread of Mycobacterium leprae.

Transforming growth factor β and apoptosis in leprosy skin lesions: possible relationship with the control of the tissue immune response in the Mycobacterium leprae infection

The course of leprosy depends of the host immune response which ranges from the lepromatous pole (LL) to the tuberculoid pole (TT). A comparative study was conducted in 60 patients with the LL and TT. The results showed a mean expression of TGF-β of 339 ± 99.4 cells/field for TT and of 519.2 ± 68.2 cells/field for LL. Frequency of apoptosis was 6.3 ± 1.8 in TT and 14.0 ± 6.1 in LL. A correlation (p = 0.0251) between TGF-β and caspase-3 in the LL was found. This finding indicates a role of TGF-β and apoptosis in the immune response in leprosy.

Tumour necrosis factor gene polymorphism and disease prevalence

Tumour necrosis factor (TNF), an important proinflammatory cytokine, plays a role in the regulation of cell differentiation, proliferation and death, as well as in inflammation, innate and adaptive immune responses, and also implicated in a wide variety of human diseases. The presence of DNA sequence variations in regulatory region might interfere with transcription of TNF gene, influencing the circulating level of TNF and thus increases the susceptibility to human diseases (infectious, cancer, autoimmune, neurodegenerative and other diseases). In this review, we have comprehensively analysed various published case-control studies of different types of human diseases, in which TNF gene polymorphism played a role, and computationally predicted several single nucleotide polymorphisms (SNPs) lie in transcription factor-binding sites (TFBS) of transcription factors (TFs). It has been observed that TNF enhancer polymorphism is implicated in several diseases, and TNF rs1800629 and rs361525 SNPs are the most important in human disease susceptibility as these might influence the transcription of TNF gene. Thirty-two SNPs lies in TFBS of 20 TFs have been detected in the TNF upstream region. It has been found that TNF enhancer polymorphism influences the serum level of TNF in different human diseases and thus affects the susceptibility to diseases. The presence of DNA sequence variation in TNF gene causes the modification of transcriptional regulation and thus responsible for association of susceptibility/resistance with human diseases.

Mannose-binding lectin serum levels in patients with leprosy are influenced by age and MBL2 genotypes

BACKGROUND

Mannose-binding lectin (MBL) activates the complement system promoting opsonophagocytosis, which could represent an advantage for Mycobacterium leprae, an intracellular pathogen. Therefore, a single nucleotide polymorphism (SNP) in the MBL2 gene associated with low levels of MBL could confer protection against the development of leprosy disease.

METHODS

In this study, we investigated SNPs of the MBL2 gene and MBL levels in 228 Brazilian leprosy patients and 232 controls.

RESULTS

There were no differences in the frequencies of variant genotypes and haplotypes of MBL2 between patients and controls, or between the different clinical forms of leprosy. In the group of patients with a genotype for high expression of MBL2, those aged>40 years had decreased MBL levels compared to patients aged ≤ 40 years (p = 0.037).

CONCLUSION

Our results demonstrate that age could influence the phenotype of MBL2, but no evidence was found for an association of MBL2 polymorphism with susceptibility to leprosy or its clinical forms.

Indoleamine 2,3-dioxygenase-expressing myeloid dendritic cells and macrophages in infectious and noninfectious cutaneous granulomas

BACKGROUND

The enzyme indoleamine 2,3-dioxygenase (IDO) degrades the essential amino acid tryptophan, and this degradation is an immunosuppressive mechanism that is mainly used by antigen-presenting cells. IDO-expressing dendritic cells and macrophages have previously been identified as components of lymph node granulomas after Listeria monocytogenes infection. In this study we undertook an analysis of IDO expression in granulomas of infectious and noninfectious origin in the human skin.

METHODS

Lesional skin biopsy specimens (n = 22) from different granulomatous skin disorders (lupus vulgaris, sarcoidosis, granuloma annulare, leprosy) were analyzed. Immunohistochemistry was performed to identify and locate the enzyme IDO within the inflammatory granulomatous infiltrate (IDO, CD11c, CD68, S100, CD3, Foxp3). Two-color immunofluorescence of IDO in combination with multiple markers was applied to characterize the IDO-expressing cells.

RESULTS

Cutaneous granulomas of different origin strongly express IDO, mainly in the center and in the ring wall of the granulomas. We demonstrate that in infectious, but also in noninfectious human cutaneous granulomas the large myeloid CD11c(+)S100(+)CD68(-) dendritic cells and the CD68(+) macrophages express IDO.

LIMITATIONS

This study was limited by the lack of details about the exact stage or maturity of granuloma formation in the specimens investigated.

CONCLUSION

These findings reveal that IDO expression in myeloid dendritic cells and macrophages is part of an integrated response of granuloma formation, which may be a unifying feature of granulomatous reactions in the skin.

Comparative immunological and microbiological aspects of paratuberculosis as a model mycobacterial infection

Paratuberculosis or Johne's disease of livestock, which is caused by Mycobacterium avium subsp. paratuberculosis (MAP), has increased in prevalence and expanded in geographic and host ranges over about 100 years. The slow and progressive spread of MAP reflects its substantial adaptation to its hosts, the technical limitations of diagnosis, the lack of practical therapeutic approaches, the lack of a vaccine that prevents transmission and the complexity and difficulty of the on-farm control strategies needed to prevent infection. More recently evidence has accumulated for an association of MAP with Crohn's disease in humans, adding to the pressure on animal health authorities to take precautions by controlling paratuberculosis. Mycobacterial infections invoke complex immune responses but the essential determinants of virulence and pathogenesis are far from clear. In this review we compare the features of major diseases in humans and animals that are caused by the pathogenic mycobacteria M. ulcerans, M. avium subsp. avium, M. leprae, M. tuberculosis and MAP. We seek to answer key questions: are the common mycobacterial infections of humans and animals useful "models" for each other, or are the differences between them too great to enable meaningful extrapolation? To simplify this, the immunopathogenesis of mycobacterial infections will be defined at cellular, tissue, animal and population levels and the key events at each level will be discussed. Many pathogenic processes are similar between divergent mycobacterial diseases, and at variance between virulent and avirulent isolates of mycobacteria, suggesting that the research on the pathogenesis of one mycobacterial disease will be informative for the others.