Potential Role of M. tuberculosis Specific IFN-γ and IL-2 ELISPOT Assays in Discriminating Children with Active or Latent Tuberculosis

Background

Although currently available IGRA have been reported to be promising markers for TB infection, they cannot distinguish active tuberculosis (TB) from latent infection (LTBI).

Objective

Children with LTBI, active TB disease or uninfected were prospectively evaluated by an in-house ELISPOT assay in order to investigate possible immunological markers for a differential diagnosis between LTBI and active TB.

Methods

Children at risk for TB infection prospectively enrolled in our infectious disease unit were evaluated by in-house IFN-γ and IL-2 based ELISPOT assays using a panel of Mycobacterium tuberculosis antigens.

Results

Twenty-nine children were classified as uninfected, 21 as LTBI and 25 as active TB cases (including 5 definite and 20 probable cases). Significantly higher IFN-γ ELISPOT responses were observed in infected vs. uninfected children for ESAT-6 (p<0.0001), CFP-10 (p<0.0001), TB 10.3 (p = 0.003), and AlaDH (p = 0.001), while differences were not significant considering Ag85B (p = 0.063), PstS1 (p = 0.512), and HspX (16 kDa) (p = 0.139). IL-2 ELISPOT assay responses were different for ESAT-6 (p<0.0001), CFP-10 (p<0.0001), TB 10.3 (p<0.0001), HspX (16 kDa) (p<0.0001), PstS1 (p<0.0001) and AlaDH (p = 0.001); but not for Ag85B (p = 0.063). Comparing results between children with LTBI and those with TB disease differences were significant for IFN-γ ELISPOT only for AlaDH antigen (p = 0.021) and for IL-2 ELISPOT assay for AlaDH (p<0.0001) and TB 10.3 antigen (p = 0.043). ROC analyses demonstrated sensitivity of 100% and specificity of 81% of AlaDH-IL-2 ELISPOT assay in discriminating between latent and active TB using a cut off of 12.5 SCF per million PBMCs.

Conclusion

Our data suggest that IL-2 based ELISPOT with AlaDH antigen may be of help in discriminating children with active from those with latent TB.     

Sensitivity of IFN-γ Release Assay to Detect Latent Tuberculosis Infection Is Retained in HIV-Infected Patients but Dependent on HIV/AIDS Progression

Background

Detection and treatment of latent TB infection (LTBI) in HIV infected individuals is strongly recommended to decrease morbidity and mortality in countries with high levels of HIV.

Objective

To assess the validity of a newly developed in-house ELISPOT interferon-γ release assay (IGRA) for the detection of LTBI amongst HIV infected individuals, in comparison with the Tuberculin Skin Test (TST).

Methodology/Principal Findings

ESAT6/CFP10 (EC) ELISPOT assays were performed, together with a TST, in 285 HIV infected individuals recruited in HIV clinics in Dakar, Senegal, who had no signs of active TB at time of enrolment. Thirty eight of the subjects (13.3%) failed to respond to PHA stimulation and were excluded from the analysis. In the 247 remaining patients, response to PHA did not vary according to CD4 cell count categories (p = 0.51). EC ELISPOT was positive in 125 (50.6%) subjects, while 53 (21.5%) had a positive TST. Concordance between EC ELISPOT and TST was observed in 151 patients (61.1%) (kappa = 0.23). The proportion of subjects with a positive response to the EC ELISPOT assay decreased with declining CD4 counts (p trend = 0.001), but were consistently higher than the proportion of TST responders. In multivariate analysis, the risk of being EC-ELISPOT positive in HIV infected individuals was associated with age, CD4 count and HIV-1 strain.

Conclusion

Our study indicates that IGRAs using M. tuberculosis specific antigens are likely to retain their validity for the diagnosis of LTBI among HIV positive individuals, but may be impaired by T-cell anergy in severely immuno-suppressed individuals.     

Soluble Markers of the Toll-Like Receptor 4 Pathway Differentiate between Active and Latent Tuberculosis and Are Associated with Treatment Responses

Background

Biomarkers to differentiate between active tuberculosis (TB) and latent TB infection (LTBI) and to monitor treatment responses are requested to complement TB diagnostics and control, particularly in patients with multi-drug resistant TB. We have studied soluble markers of the Toll-like-receptor 4 (TLR-4) pathway in various stages of TB disease and during anti-TB treatment.

Methods

Plasma samples from patients with culture confirmed drug-sensitive TB (n = 19) were collected before and after 2, 8 and 24 weeks of efficient anti-TB treatment and in a LTBI group (n = 6). Soluble (s) CD14 and myeloid differentiation-2 (MD-2) were analyzed by the Enzyme-linked immunosorbent assay (ELISA). Lipopolysaccharide (LPS) was analyzed by the Limulus Amebocyte Lysate colorimetric assay. Nonparametric statistics were applied.

Results

Plasma levels of sCD14 (p<0.001), MD-2 (p = 0.036) and LPS (p = 0.069) were elevated at baseline in patients with untreated active TB compared to the LTBI group. MD-2 concentrations decreased after 2 weeks of treatment (p = 0.011), while LPS levels decreased after 8 weeks (p = 0.005). In contrast, sCD14 levels increased after 2 weeks (p = 0.047) with a subsequent modest decrease throughout the treatment period. There was no significant difference in concentrations of any of these markers between patients with pulmonary and extrapulmonary TB or between patients with or without symptoms.

Conclusion

Our data suggest that plasma levels of LPS, MD-2 and sCD14 can discriminate between active TB and LTBI. A decline in LPS and MD-2 concentrations was associated with response to anti-TB treatment. The clinical potential of these soluble TLR-4 pathway proteins needs to be further explored.     

IFNγ Response to Mycobacterium tuberculosis,Risk of Infection and Disease in Household Contacts of Tuberculosis Patients in Colombia

Objectives

Household contacts (HHCs) of pulmonary tuberculosis patients are at high risk of Mycobacterium tuberculosis infection and early disease development. Identification of individuals at risk of tuberculosis disease is a desirable goal for tuberculosis control. Interferon-gamma release assays (IGRAs) using specific M. tuberculosis antigens provide an alternative to tuberculin skin testing (TST) for infection detection. Additionally, the levels of IFNγ produced in response to these antigens may have prognostic value. We estimated the prevalence of M. tuberculosis infection by IGRA and TST in HHCs and their source population (SP), and assessed whether IFNγ levels in HHCs correlate with tuberculosis development.

Methods

A cohort of 2060 HHCs was followed for 2–3 years after exposure to a tuberculosis case. Besides TST, IFNγ responses to mycobacterial antigens: CFP, CFP-10, HspX and Ag85A were assessed in 7-days whole blood cultures and compared to 766 individuals from the SP in Medellín, Colombia. Isoniazid prophylaxis was not offered to child contacts because Colombian tuberculosis regulations consider it only in children under 5 years, TST positive without BCG vaccination.

Results

Using TST 65.9% of HHCs and 42.7% subjects from the SP were positive (OR 2.60, p<0.0001). IFNγ response to CFP-10, a biomarker of M. tuberculosis infection, tested positive in 66.3% HHCs and 24.3% from the SP (OR = 6.07, p<0.0001). Tuberculosis incidence rate was 7.0/1000 person years. Children <5 years accounted for 21.6% of incident cases. No significant difference was found between positive and negative IFNγ responders to CFP-10 (HR 1.82 95% CI 0.79–4.20 p = 0.16). However, a significant trend for tuberculosis development amongst high HHC IFNγ producers was observed (trend Log rank p = 0.007).

Discussion

CFP-10-induced IFNγ production is useful to establish tuberculosis infection prevalence amongst HHC and identify those at highest risk of disease. The high tuberculosis incidence amongst children supports administration of chemoprohylaxis to child contacts regardless of BCG vaccination.     

Longitudinal analysis of QuantiFERON-TB Gold In-Tube in children with adult household tuberculosis contact in South Africa: a prospective cohort study

Background

QuantiFERON-TB Gold In Tube (QFT-GIT) is a tool for detecting M. tuberculosis infection. However, interpretation and utility of serial QFT-GIT testing of pediatric tuberculosis (TB) contacts is not well understood. We compared TB prevalence between baseline and 6 months follow-up using QFT-GIT and tuberculin skin testing (TST) in children who were household contacts of adults with pulmonary TB in South Africa, and explored factors associated with QFT-GIT conversions and reversions.

Method

Prospective study with six month longitudinal follow-up.

Results

Among 270 enrolled pediatric contacts, 196 (73%) underwent 6-month follow-up testing. The 6-month prevalence estimate of MTB infection in pediatric contacts increased significantly from a baseline of 29% (79/270, 95%CI [24–35]) to 38% (103/270, 95% CI [32–44], p<0.001) using QFT-GIT; prevalence increased from a baseline of 28% (71/254, 95%CI [23–34]) to 33% (88/263, 95%CI [21–32], p = 0.002) using TST. Prevalence estimates were influenced by thresholds for positivity for TST, but not for QFT-GIT. Among 134 children with a negative or indeterminate baseline QFT-GIT, 24 (18%) converted to positive at follow-up; conversion rates did not differ significantly when using more stringent thresholds to define QFT-GIT conversion. Older age >10 years (AOR 8.9 95%CI [1.1–72]) and baseline TST positivity ≥5 mm (AOR 5.2 95%CI [1.2–23]) were associated with QFT-GIT conversion. Among 62 children with a positive baseline QFT-GIT, 9 (15%) reverted to negative; female gender (AOR 18.5 95%CI [1.1–321]; p = 0.04] was associated with reversion, while children with baseline positive TST were less likely to have QFT-GIT reversion (AOR 0.01 95%CI [0.001–0.24]).

Conclusion

Among pediatric contacts of adult household TB cases in South Africa, prevalence estimates of TB infection increased significantly from baseline to 6 months. Conversions and reversions occurred among pediatric TB contacts using QFT-GIT, but QFT-GIT conversion rates were less influenced by thresholds used for conversions than were TST conversion rates.     

Iron Status and Helicobacter pylori Infection in Symptomatic Children: An International Multi-Centered Study

Objective

Iron deficiency (ID) and iron deficiency anaemia (IDA) are global major public health problems, particularly in developing countries. Whilst an association between H. pylori infection and ID/IDA has been proposed in the literature, currently there is no consensus. We studied the effects of H. pylori infection on ID/IDA in a cohort of children undergoing upper gastrointestinal endoscopy for upper abdominal pain in two developing and one developed country.

Methods

In total 311 children (mean age 10.7±3.2 years) from Latin America - Belo Horizonte/Brazil (n = 125), Santiago/Chile (n = 105) - and London/UK (n = 81), were studied. Gastric and duodenal biopsies were obtained for evaluation of histology and H. pylori status and blood samples for parameters of ID/IDA.

Results

The prevalence of H. pylori infection was 27.7% being significantly higher (p<0.001) in Latin America (35%) than in UK (7%). Multiple linear regression models revealed H. pylori infection as a significant predictor of low ferritin and haemoglobin concentrations in children from Latin-America. A negative correlation was observed between MCV (r = −0.26; p = 0.01) and MCH (r = −0.27; p = 0.01) values and the degree of antral chronic inflammation, and between MCH and the degree of corpus chronic (r = −0.29, p = 0.008) and active (r = −0.27, p = 0.002) inflammation.

Conclusions

This study demonstrates that H. pylori infection in children influences the serum ferritin and haemoglobin concentrations, markers of early depletion of iron stores and anaemia respectively.     

Eradication of Helicobacter pylori Infection Improves Levodopa Action,Clinical Symptoms and Quality of Life in Patients with Parkinson's Disease

Background

Previous studies have demonstrated a higher prevalence of Helicobacter pylori (H. pylori) infection in patients with Parkinson''s disease (PD) compared to controls. H. pylori infection affects levodopa absorption and its eradication significantly improves clinical response to levodopa. Here, we studied the prevalence of H. pylori infection and its eradication effects among our PD patients.

Methods

A prospective study involving idiopathic PD patients on levodopa therapy. ¹³C-urea breath test (UBT) was used to detect H. pylori. UBT-positive patients were given standard eradication therapy and followed up at 6 and 12 weeks in an open label single arm design. Repeat UBT was performed at 12 weeks. The UPDRS, PD NMQ, PD NMSS and PDQ-39 were administered at baseline and post-eradication (6 and 12 weeks). Levodopa ‘onset’ time and ON-duration were recorded.

Results

Of 82 patients recruited, 27 (32.9%) had positive UBT. H. pylori-positive patients had significantly poorer total UPDRS (p = 0.005) and PDQ39 (p<0.0001) scores compared to H. pylori-negative patients. At 12 weeks post-eradication, the mean levodopa onset time shortened by 14 minutes (p = 0.011). The mean ON duration time increased by 56 minutes at week 6 (p = 0.041) and 38 minutes at week 12 (p = 0.035). The total UPDRS scores (p<0.0001), scores for parts II (p = 0.001), III (p<0.0001) and IV (p = 0.009) were significantly better. The total PDQ-39 scores (p = 0.001) and subdomains mobility (p = 0.002), ADL (p = 0.001), emotional well being (p = 0.026) and stigma (p = 0.034) significantly improved. The PD NMSQ did not show significant improvement.

Conclusions

H. pylori eradication improved levodopa onset time, ON duration, motor severity and quality of life parameters. Screening and eradication of H. pylori is inexpensive and should be recommended in PD patients, particularly those with erratic response to levodopa.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT02112812","term_id":"NCT02112812"}}NCT02112812     

Biomarker Changes Associated with Tuberculin Skin Test (TST) Conversion: A Two-Year Longitudinal Follow-Up Study in Exposed Household Contacts

Background

A high prevalence (50–80%) of Tuberculin Skin Test Positivity (TST+ ≥10 mm indurations) has been reported in TB endemic countries. This pool forms a huge reservoir for new incident TB cases. However, immune biomarkers associated with TST conversion are largely unknown. The objective of this study was to identify immune biomarkers associated with TST conversion after acute Mycobacterium tuberculosis (MTB) exposure.

Methodology/Principal Findings

A 24 month longitudinal study was carried out in a recently MTB exposed cohort of household contacts (HC = 93; 75% TST+). Control group consisted of unexposed community controls (EC = 59; 46%TST+). Cytokine secretion was assessed in whole blood cultures in response to either mycobacterial culture filtrate (CF) antigens or mitogens (PHA or LPS) using Elisa methodology. Compared to the EC group, the HC group at recruitment (Kruskal-Wallis Test) showed significantly suppressed IFN γ (p = 0.0001), raised IL-10 (p = 0.0005) and raised TNF α (p = 0.001) in response to CF irrespective of their TST status. Seventeen TST-HC, showed TST conversion when retested at 6 months. Post TST conversion (paired t tests) significant increases were observed for CF induced IFN γ (p = 0.038), IL-10 (p = 0.001) and IL-6 (p = 0.006). Cytokine responses were also compared in the exposed HC group with either recent infection [(TST converters (N = 17)] or previous infection [TST+ HC (N = 54)] at 0, 6, 12 and 24 months using ANOVA on repeated measures. Significant differences between the exposed HC groups were noted only at 6 months. CF induced IFN γ was higher in previously infected HC group (p = 0.038) while IL-10 was higher in recently infected HC group (p = 0.041). Mitogen induced cytokine secretion showed similar differences for different group.

Conclusions/Significance

Our results suggest that TST conversion is associated with early increases in IFN γ and IL-10 responses and precedes latency by several months post exposure.     

Clinical Utility of a Commercial LAM-ELISA Assay for TB Diagnosis in HIV-Infected Patients Using Urine and Sputum Samples

Background

The accurate diagnosis of TB in HIV-infected patients, particularly with advanced immunosuppression, is difficult. Recent studies indicate that a lipoarabinomannan (LAM) assay (Clearview-TB®-ELISA) may have some utility for the diagnosis of TB in HIV-infected patients; however, the precise subgroup that may benefit from this technology requires clarification. The utility of LAM in sputum samples has, hitherto, not been evaluated.

Methods

LAM was measured in sputum and urine samples obtained from 500 consecutively recruited ambulant patients, with suspected TB, from 2 primary care clinics in South Africa. Culture positivity for M. tuberculosis was used as the reference standard for TB diagnosis.

Results

Of 440 evaluable patients 120/387 (31%) were HIV-infected. Urine-LAM positivity was associated with HIV positivity (p = 0.007) and test sensitivity, although low, was significantly higher in HIV-infected compared to uninfected patients (21% versus 6%; p<0.001), and also in HIV-infected participants with a CD4 <200 versus >200 cells/mm³ (37% versus 0%; p = 0.003). Urine-LAM remained highly specific in all 3 subgroups (95%–100%). 25% of smear-negative but culture-positive HIV-infected patients with a CD4 <200 cells/mm³ were positive for urine-LAM. Sputum-LAM had good sensitivity (86%) but poor specificity (15%) likely due to test cross-reactivity with several mouth-residing organisms including actinomycetes and nocardia species.

Conclusions

These preliminary data indicate that in a high burden primary care setting the diagnostic usefulness of urine-LAM is limited, as a rule-in test, to a specific patient subgroup i.e. smear-negative HIV-infected TB patients with a CD4 count <200 cells/mm³, who would otherwise have required further investigation. However, even in this group sensitivity was modest. Future and adequately powered studies in a primary care setting should now specifically target patients with suspected TB who have advanced HIV infection.     

Tuberculin Skin Testing and Treatment Modulates Interferon-Gamma Release Assay Results for Latent Tuberculosis in Migrants

Background

Identifying latent tuberculosis infection (LTBI) in people migrating from TB endemic regions to low incidence countries is an important control measure. However, no prospective longitudinal comparisons between diagnostic tests used in such migrant populations are available.

Objectives

To compare commercial interferon (IFN)-gamma release assays (IGRAs) and the tuberculin skin test (TST) for diagnosing LTBI in a migrant population, and the influence of antecedent TST and LTBI treatment on IGRA performance.

Materials and Methods

This cohort study, performed from February to September 2012, assessed longitudinal IGRA and TST responses in Nepalese military recruits recently arrived in the UK. Concomitant T-SPOT.TB, QFT-GIT and TST were performed on day 0, with IGRAs repeated 7 and 200 days later, following treatment for LTBI if necessary.

Results

166 Nepalese recruits were prospectively assessed. At entry, 21 individuals were positive by T-SPOT.TB and 8 individuals by QFT-GIT. There was substantial agreement between TST and T-SPOT.TB positives at baseline (71.4% agreement; κ = 0.62; 95% CI:0.44–0.79), but only moderate concordance between positive IGRAs (38.1% agreement; κ = 0.46; 95% CI:0.25–0.67). When reassessed 7 days following TST, numbers of IGRA-positive individuals changed from 8 to 23 for QFT-GIT (p = 0.0074) and from 21 to 23 for T-SPOT.TB (p = 0.87). This resulted in an increase in IGRA concordance to substantial (64.3% agreement; κ = 0.73; 95% CI:0.58-0.88). Thus, in total on day 0 and day 7 after testing, 29 out of 166 participants (17.5%) provided a positive IGRA and of these 13 were TST negative. Two hundred days after the study commenced and three months after treatment for LTBI was completed by those who were given chemoprophylaxis, 23 and 21 participants were positive by T-SPOT.TB or QFT-GIT respectively. When individual responses were examined longitudinally within this population 35% of the day 7 QFT-GIT-positive, and 19% T-SPOT.TB-positive individuals, were negative by IGRA. When the change in the levels of secreted IFN-γ was examined after chemoprophylaxis the median levels were found to have fallen dramatically by 77.3% from a pre-treatment median concentration of IFN-γ 2.73 IU/ml to a post-treatment median concentration IFN-γ 0.62 (p = 0.0002).

Conclusions

This study suggests differences in the capacity of commercially available IGRAs to identify LTBI in the absence of antecedent TST and that IGRAs, in the time periods examined, may not be the optimal tests to determine the success of chemoprophylaxis for LTBI.     

Prevalence and Incidence of Latent Tuberculosis Infection in Georgian Healthcare Workers

Background

Tuberculosis is a major occupational hazard in low and middle-income countries. Limited data exist on serial testing of healthcare workers (HCWs) with interferon-γ release assays (IGRAs) for latent tuberculosis infection (LTBI), especially in low and middle-income countries. We sought to evaluate the rates of and risk factors for LTBI prevalence and LTBI test conversion among HCWs using the tuberculin skin test (TST) and QuantiFERON-TB Gold In-tube assay (QFT-GIT).

Methods

A prospective longitudinal study was conducted among HCWs in the country of Georgia. Subjects completed a questionnaire, and TST and QFT-GIT tests were performed. LTBI testing was repeated 6-26 months after baseline testing.

Results

Among 319 HCWs enrolled, 89% reported prior BCG vaccination, and 60% worked in TB healthcare facilities (HCFs). HCWs from TB HCFs had higher prevalence of positive QFT-GIT and TST than those from non-TB HCFs: 107/194 (55%) vs. 30/125 (31%) QFT-GIT positive (p<0.0001) and 128/189 (69%) vs. 64/119 (54%) TST positive (p = 0.01). There was fair agreement between TST and QFT-GIT (kappa = 0.42, 95% CI 0.31–0.52). In multivariate analysis, frequent contact with TB patients was associated with increased risk of positive QFT-GIT (aOR 3.04, 95% CI 1.79–5.14) but not positive TST. Increasing age was associated with increased risk of positive QFT-GIT (aOR 1.05, 95% CI 1.01–1.09) and TST (aOR 1.05, 95% CI 1.01–1.10). High rates of HCW conversion were seen: the QFT-GIT conversion rate was 22.8/100 person-years, and TST conversion rate was 17.1/100 person-years. In multivariate analysis, female HCWs had decreased risk of TST conversion (aOR 0.05, 95% CI 0.01–0.43), and older HCWs had increased risk of QFT-GIT conversion (aOR 1.07 per year, 95% CI 1.01–1.13).

Conclusion

LTBI prevalence and LTBI test conversion rates were high among Georgian HCWs, especially among those working at TB HCFs. These data highlight the need for increased implementation of TB infection control measures.     

Immune Responses to ESAT-6 and CFP-10 by FASCIA and Multiplex Technology for Diagnosis of M. tuberculosis Infection; IP-10 Is a Promising Marker

Background

There is a need for reliable markers to diagnose active and latent tuberculosis (TB). The interferon gamma release assays (IGRAs) are compared to the tuberculin skin test (TST) more specific, but cannot discriminate between recent or remote TB infection. Here the Flow-cytometric Assay for Specific Cell-mediated Immune-response in Activated whole blood (FASCIA), which quantifies expanded T-lymphoblasts by flow-cytometric analysis after long-term antigen stimulation of whole blood, is combined with cytokine/chemokine analysis in the supernatant by multiplex technology for diagnosis of Mycobacterium tuberculosis (Mtb) infection.

Methods and Findings

Consecutive patients with suspected TB (n = 85), with microbiologically verified active pulmonary TB (n = 33), extra pulmonary TB (n = 21), clinical TB (n = 11), presumed latent TB infection (LTBI) (n = 23), patients negative for TB (n = 8) and 21 healthy controls were studied. Blood samples were analyzed with FASCIA and multiplex technology to determine and correlate proliferative responses and the value of 14 cytokines for diagnosis of Mtb infection: IFN- γ, IL-2, TNF-α, IP-10, IL-12, IL-6, IL-4, IL-5, IL-13, IL-17, MIP-1β, GM-CSF, IFN-α2 and IL-10. Cytokine levels for IFN-γ, IP-10, MIP-1β, IL-2, TNF-α, IL-6, IL-10, IL-13 and GM-CSF were significantly higher after stimulation with the Mtb specific antigens ESAT-6 and CFP-10 in patients with active TB compared to healthy controls (p<0.05) and correlated with proliferative responses. IP-10 was positive in all patients with verified TB, if using a combination of ESAT-6 and CFP-10 and was the only marker significantly more sensitive in detecting active TB then IFN-γ (p = 0.012). Cytokine responses in patients with active TB were more frequent and detected at higher levels than in patients with LTBI.

Conclusions

IP-10 seems to be an important marker for diagnosis of active and latent TB. Patients with active TB and LTBI responded with similar cytokine profiles against TB antigens but proliferative and cytokine responses were generally higher in patients with active TB.     

Identification of T-Cell Antigens Specific for Latent Mycobacterium Tuberculosis Infection

Background

T-cell responses against dormancy-, resuscitation-, and reactivation-associated antigens of Mycobacterium tuberculosis are candidate biomarkers of latent infection in humans.

Methodology/Principal Findings

We established an assay based on two rounds of in vitro restimulation and intracellular cytokine analysis that detects T-cell responses to antigens expressed during latent M. tuberculosis infection. Comparison between active pulmonary tuberculosis (TB) patients and healthy latently M. tuberculosis-infected donors (LTBI) revealed significantly higher T-cell responses against 7 of 35 tested M. tuberculosis latency-associated antigens in LTBI. Notably, T cells specific for Rv3407 were exclusively detected in LTBI but not in TB patients. The T-cell IFNγ response against Rv3407 in individual donors was the most influential factor in discrimination analysis that classified TB patients and LTBI with 83% accuracy using cross-validation. Rv3407 peptide pool stimulations revealed distinct candidate epitopes in four LTBI.

Conclusions

Our findings further support the hypothesis that the latency-associated antigens can be exploited as biomarkers for LTBI.     

Is IP-10 a Better Biomarker for Active and Latent Tuberculosis in Children than IFNγ?

Background

The blood based interferon-gamma release assays (IGRA) for the diagnosis of tuberculosis do not discriminate between active TB disease and latent TB infection (LTBI). The search for distinguishing biomarkers therefore continues, as the accurate diagnosis of tuberculosis is particularly challenging in children. IFN-γ-inducible protein 10 (IP-10/CXCL10) has recently been evaluated as a marker for active TB in adults with promising results.

Aim

To investigate this new biomarker for active TB and LTBI in paediatrics.

Method

We measured IP-10 levels using ELISA in supernatants of whole blood samples stimulated with TB-specific-antigens and negative control antigen.

Results

IP-10 is produced in high levels following mycobacterial antigen stimulation in active TB (n = 17) and LTBI (n = 16) compared to controls (n = 16) and to IFN-γ. The baseline levels of IP-10 are increased in active TB and in LTBI, but there is no significant difference of stimulated levels of IP-10 between active TB and LTBI.

Conclusions

IP-10 is a biomarker for tuberculosis in children. However like IFNγ, IP-10 also does not distinguish between active TB and LTBI.     

CpG Island Methylator Phenotype,Helicobacter pylori,Epstein-Barr Virus,and Microsatellite Instability and Prognosis in Gastric Cancer: A Systematic Review and Meta-Analysis

Background

The controversy of CpG island methylator phenotype (CIMP) in gastric cancer persists, despite the fact that many studies have been conducted on its relation with helicobacter pylori (H. pylori), Epstein-Barr virus (EBV), and microsatellite instability (MSI) and prognosis. To drive a more precise estimate of this postulated relationship, a meta-analysis was performed based on existing relevant studies.

Methods

We combined individual patient data from 12 studies which involved 1000 patients with gastric cancer, which met the criteria. We tabulated and analyzed parameters from each study, including H. pylori, EBV, MSI, and clinical information of patients.

Results

The overall OR for H. pylori infection in CIMP positive group vs. negative group revealed that significantly elevated risks of positive H. pylori infection in the former were achieved (OR 2.23 95% CI, 1.25–4.00; P = 0.007, P_{heterogeneity} = 0.05). Similarly, strong relation between EBV infection and CIMP was achieved by OR 51.27 (95% CI, 9.39–279.86; P<0.00001, P_{heterogeneity} = 0.39). The overall OR for MSI in CIMP positive group vs. negative group was 4.44 (95% CI, 1.17–16.88; P = 0.03, P_{heterogeneity} = 0.01). However, there did not appear to be any correlations with clinical parameters such as tumor site, pathological type, cell differentiation, TNM stage, distant metastasis, lymph node metastasis, and 5-year survival.

Conclusions

The meta-analysis highlights the strong relation of CIMP with H. pylori, EBV, and MSI, but CIMP can not be used as a prognostic marker for gastric cancer.     

Asthma Is Inversely Associated with Helicobacter pylori Status in an Urban Population

Background

Microbial exposures have been suggested to confer protection from allergic disorders and reduced exposures to gastrointestinal microbiota have been proposed as an explanation for the increase in asthma prevalence. Since the general prevalence of Helicobacter pylori has been decreasing, we hypothesized that H. pylori serostatus would be inversely related to the presence of asthma.

Methods

Adults were recruited to participate in the New York University (NYU)/Bellevue Asthma Registry in New York City. Adult asthma cases (N = 318) and controls (N = 208) were identified and serum IgG antibodies to H. pylori whole cell antigens or the immunodominant CagA antigen were measured.

Results

As expected, the asthma cases and controls differed with respect to atopy and lung function. Seropositivity to H. pylori or CagA antigen was present in 47.1% of the total case and control study population. Asthma was inversely associated with CagA seropositivity (OR = 0.57, 95% CI = 0.36–0.89). Median age of onset of asthma (doctor''s diagnosis) was older (21 years) among individuals with CagA+ strains than among H. pylori- individuals (11 years) (p = 0.006).

Conclusion

These data are consistent with the hypothesis that colonization with CagA+ H. pylori strains is inversely associated with asthma and is associated with an older age of asthma onset in an urban population. The data suggest H. pylori as a marker for protection.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00212537","term_id":"NCT00212537"}}NCT00212537     

The Knowledge of Colorectal Cancer Symptoms and Risk Factors among 10,078 Screening Participants: Are High Risk Individuals More Knowledgeable?

Objectives

We tested the a priori hypothesis that self-perceived and real presences of risks for colorectal cancer (CRC) are associated with better knowledge of the symptoms and risk factors for CRC, respectively.

Methods

One territory-wide invitation for free CRC screening between 2008 to 2012 recruited asymptomatic screening participants aged 50–70 years in Hong Kong. They completed survey items on self-perceived and real presences of risks for CRC (advanced age, male gender, positive family history and smoking) as predictors, and knowledge of CRC symptoms and risk factors as outcome measures, respectively. Their associations were evaluated by binary logistic regression analyses.

Results

From 10,078 eligible participants (average age 59 years), the mean knowledge scores for symptoms and risk factors were 3.23 and 4.06, respectively (both score range 0–9). Male gender (adjusted odds ratio [AOR] = 1.34, 95% C.I. 1.20–1.50, p<0.01), self-perception as not having any risks for CRC (AOR = 1.12, 95% C.I. 1.01–1.24, p = 0.033) or uncertainty about having risks (AOR = 1.94, 95% C.I. 1.55–2.43, p<0.001), smoking (AOR 1.38, 95% C.I. 1.11–1.72, p = 0.004), and the absence of family history (AOR 0.61 to 0.78 for those with positive family history, p<0.001) were associated with poorer knowledge scores (≤4) of CRC symptoms. These factors remained significant for knowledge of risk factors.

Conclusions

Male and smokers were more likely to have poorer knowledge but family history of CRC was associated with better knowledge. Since screening of these higher risk individuals could lead to greater yield of colorectal neoplasm, educational interventions targeted to male smokers were recommended.     

TLR9 Promoter Polymorphism Is Associated with Both an Increased Susceptibility to Gastric Carcinoma and Poor Prognosis

Objective

Genetic polymorphisms of Toll-like receptors (TLRs) may influence the effects of H. pylori infection and play important roles in gastric carcinogenesis. The aim of this study was to determine whether the polymorphisms of TLR4 and TLR9 are associated with susceptibility to gastric carcinoma and its prognosis.

Methods

This study consisted of 314 patients with gastric cancer and 314 healthy controls. The polymorphisms were assessed using polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) analysis. Survival was analyzed by Kaplan–Meier survival curves.

Results

No variant genotypes of TLR4+896A/G, TLR4+1196C/T, or TLR9 -1237T/C were detected. For TLR9 -1486 T/C, multiple logistic regression analyses revealed that compared with the TT homozygote, patients with both the TC variant (adjusted odds ratio (OR) = 1.47, 95% confidence interval (CI) = 1.04–2.10) and the CC variant (adjusted OR = 1.63, 95% CI = 1.01–2.64) had higher risks of gastric cancer. Further stratification analyses revealed that an increased risk of gastric cancer associated with C carriers was evident among females (adjusted OR = 1.84, 95%CI = 1.02–3.33), in younger subjects aged less than 60 years old (adjusted OR = 1.86, 95%CI = 1.15–3.00), and subjects with H. pylori infection (adjusted OR = 1.53, 95% CI = 1.03–2.27). We also observed a significant association between C carriers and noncardia gastric cancer (adjusted OR = 1.51, 95% CI = 1.03–2.20). In addition, we demonstrated that the C carrier genotype and H. pylori infection may have a synergistic effect and conferred an OR of 2.44 for developing gastric cancer. TLR9 -1486C was also identified as an independent marker of poor survival of carcinoma.

Conclusions

Our results suggest that TLR9 -1486C carriers are associated with an increased risk and poor prognosis of gastric carcinoma in the Chinese population.     

First Insights into the Phylogenetic Diversity of Mycobacterium tuberculosis in Nepal

Background

Tuberculosis (TB) is a major public health problem in Nepal. Strain variation in Mycobacterium tuberculosis may influence the outcome of TB infection and disease. To date, the phylogenetic diversity of M. tuberculosis in Nepal is unknown.

Methods and Findings

We analyzed 261 M. tuberculosis isolates recovered from pulmonary TB patients recruited between August 2009 and August 2010 in Nepal. M. tuberculosis lineages were determined by single nucleotide polymorphisms (SNP) typing and spoligotyping. Drug resistance was determined by sequencing the hot spot regions of the relevant target genes. Overall, 164 (62.8%) TB patients were new, and 97 (37.2%) were previously treated. Any drug resistance was detected in 50 (19.2%) isolates, and 16 (6.1%) were multidrug-resistant. The most frequent M. tuberculosis lineage was Lineage 3 (CAS/Delhi) with 106 isolates (40.6%), followed by Lineage 2 (East-Asian lineage, includes Beijing genotype) with 84 isolates (32.2%), Lineage 4 (Euro-American lineage) with 41 (15.7%) isolates, and Lineage 1 (Indo-Oceanic lineage) with 30 isolates (11.5%). Based on spoligotyping, we found 45 different spoligotyping patterns that were previously described. The Beijing (83 isolates, 31.8%) and CAS spoligotype (52, 19.9%) were the dominant spoligotypes. A total of 36 (13.8%) isolates could not be assigned to any known spoligotyping pattern. Lineage 2 was associated with female sex (adjusted odds ratio [aOR] 2.58, 95% confidence interval [95% CI] 1.42–4.67, p = 0.002), and any drug resistance (aOR 2.79; 95% CI 1.43–5.45; p = 0.002). We found no evidence for an association of Lineage 2 with age or BCG vaccination status.

Conclusions

We found a large genetic diversity of M. tuberculosis in Nepal with representation of all four major lineages. Lineages 3 and 2 were dominating. Lineage 2 was associated with clinical characteristics. This study fills an important gap on the map of the M. tuberculosis genetic diversity in the Asian region.