Innate activation of human primary epithelial cells broadens the host response to Mycobacterium tuberculosis in the airways.

Early events in the human airways determining whether exposure to Mycobacterium tuberculosis (Mtb) results in acquisition of infection are poorly understood. Epithelial cells are the dominant cell type in the lungs, but little is known about their role in tuberculosis. We hypothesised that human primary airway epithelial cells are part of the first line of defense against Mtb-infection and contribute to the protective host response in the human respiratory tract. We modelled these early airway-interactions with human primary bronchial epithelial cells (PBECs) and alveolar macrophages. By combining in vitro infection and transwell co-culture models with a global transcriptomic approach, we identified PBECs to be inert to direct Mtb-infection, yet to be potent responders within an Mtb-activated immune network, mediated by IL1ß and type I interferon (IFN). Activation of PBECs by Mtb-infected alveolar macrophages and monocytes increased expression of known and novel antimycobacterial peptides, defensins and S100-family members and epithelial-myeloid interactions further shaped the immunological environment during Mtb-infection by promoting neutrophil influx. This is the first in depth analysis of the primary epithelial response to infection and offers new insights into their emerging role in tuberculosis through complementing and amplifying responses to Mtb.

Viral hepatitis prevalence in patients with active and latent tuberculosis.

AIM: To assess the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection and association with drug induced liver injury (DILI) in patients undergoing anti-tuberculosis (TB) therapy. METHODS: Four hundred and twenty nine patients with newly diagnosed TB - either active disease or latent infection - who were due to commence anti-TB therapy between September 2008 and May 2011 were included. These patients were prospectively tested for serological markers of HBV, HCV and human immunodeficiency virus (HIV) infections - hepatitis B core antigen (HBcAg), hepatitis B surface antigen (HBsAg), hepatitis B e antigen, IgG and IgM antibody to HBcAg (anti-HBc), HCV IgG antibody and HIV antibody using a combination of enzyme-linked immunosorbent assay, Western blot assay and polymerase chain reaction techniques. Patients were reviewed at least monthly during the TB treatment initiation phase. Liver function tests were measured prior to commencement of anti-TB therapy and 2-4 wk later. Liver function tests were also performed at any time the patient had significant nausea, vomiting, rash, or felt non-specifically unwell. Fisher's exact test was used to measure significance in comparisons of proportions between groups. A P value of less than 0.05 was considered statistically significant. RESULTS: Of the 429 patients, 270 (62.9%) had active TB disease and 159 (37.1%) had latent TB infection. 61 (14.2%) patients had isolated anti-HBc positivity, 11 (2.6%) were also HBsAg positive and 7 (1.6%) were HCV-antibody positive. 16/270 patients with active TB disease compared to 2/159 patients with latent TB infection had markers of chronic viral hepatitis (HBsAg or HCV antibody positive; P = 0.023). Similarly the proportion of HBsAg positive patients were significantly greater in the active vs latent TB infection group (10/43 vs 1/29, P = 0.04). The prevalence of chronic HBV or HCV was significantly higher than the estimated United Kingdom prevalence of 0.3% for each. We found no association between DILI and presence of serological markers of HBV or HCV. Three (5.3%) patients with serological markers of HBV or HCV infection had DILI compared to 25 (9.5%) patients without; P = 0.04. CONCLUSION: Viral hepatitis screening should be considered in TB patients. DILI risk was not increased in patients with HBV/HCV.

Increased risk of Mycobacterium tuberculosis infection in household child contacts exposed to passive tobacco smoke.

Risk factors associated with Mycobacterium tuberculosis infection were investigated in a prospective cohort of household child tuberculosis contacts. A significantly increased risk of acquiring infection was associated with exposure to passive cigarette smoke, higher number of index cases, younger age and reduced household monthly income.

Performance of Xpert MTB/RIF in the diagnosis of tuberculous mediastinal lymphadenopathy by endobronchial ultrasound.

RATIONALE: The Xpert (GeneXpert) MTB/RIF, an integrated polymerase chain reaction assay, has not been systematically studied in extrapulmonary and in particular mediastinal tuberculosis (TB). OBJECTIVES: To investigate the performance of Xpert MTB/RIF in the diagnosis of intrathoracic nodal TB in a large tertiary urban medical center in the UK. METHODS: We collected clinical, cytological, and microbiological data from two cohorts: 116 consecutive patients referred with mediastinal lymphadenopathy with detailed diagnostic information obtained, and an immediately subsequent second cohort of 52 consecutive patients with microbiologically confirmed mediastinal TB lymphadenopathy. All data were derived between January 2010 and October 2012. All patients underwent endobronchial ultrasound and transbronchial needle aspiration (TBNA). The performance of a single Xpert MTB/RIF assay alongside standard investigations, cytology, and microscopy/culture was evaluated against culture-confirmed TB. MEASUREMENTS AND MAIN RESULTS: Microbiologically confirmed TB mediastinal lymphadenopathy was diagnosed in a total of 88 patients from both cohorts. Three culture-negative cases with associated caseating granulomatous inflammation on TBNA were given a probable diagnosis. A single Xpert MTB/RIF assay demonstrated overall sensitivity for culture-positive TB of 72.6% (62.3-81.0%). Xpert specificity from cohort 1 was 96.3% (89.1-99.1%). The positive predictive value was 88.9% (69.7-97.1%), negative predictive value was 86.5% (76.9-92.1%), and odds ratio was 51.3 (24.0-98.0) for correctly identifying culture-positive disease. Xpert captured all microscopy-positive cases (14 of 14) and the majority of microscopy-negative cases (48 of 71, 67.6%). Among the cases that were culture positive by TBNA, Xpert identified two-thirds of the multiple drug-resistant TB cases, leading to immediate regimen change up to 5 weeks ahead of positive cultures. The use of Xpert combined with cytology increased the sensitivity to 96.6%. CONCLUSIONS: Xpert MTB/RIF provides a rapid, useful, and accurate test to diagnose mediastinal nodal TB in intermediate-incidence settings. The additional use of TBNA cytology further enhances the sensitivity of Xpert. This combination can facilitate rapid risk assessment and prompt TB treatment.

Evaluation of screening methods for identification of patients with chronic rheumatological disease requiring tuberculosis chemoprophylaxis prior to commencement of TNF-α antagonist therapy.

BACKGROUND: Patients undergoing tumour necrosis factor (TNF)-α antagonist therapy are at increased risk of latent tuberculosis infection (LTBI) reactivation. The aim of this study was to determine the optimum available screening strategy for identifying patients for tuberculosis (TB) chemoprophylaxis. METHODS: We conducted a prospective observational study of consecutive adults with chronic rheumatological disease referred for LTBI screening prior to commencement of TNF-α antagonist therapy. All patients included had calculation of TB risk according to age, ethnicity and year of UK entry, as described in the 2005 British Thoracic Society (BTS) guidelines and measurement of tuberculin skin test (TST) and T.Spot.TB. RESULTS: There were 187 patients included in the study, with 157 patients (84%) taking immunosuppressants. 137 patients would require further risk stratification according to the BTS algorithm, with 110 (80.3%) classified as being at low risk of having LTBI. There were 39 patients (35.5%) who were categorised as low risk but were either TST and/or T.Spot positive and would not have received chemoprophylaxis according to the BTS algorithm. Combination of all three methods (risk stratification and/or positive T.Spot and/or positive TST) identified 66 patients out of 137 who would potentially be offered chemoprophylaxis, which was greater than any single test or two-test combination. CONCLUSION: Performing both a TST and T.Spot in patients on immunosuppressants prior to commencement of TNF-α antagonist therapy gives an additional yield of potential LTBI compared with use of risk stratification tables alone. Our results suggest that use of all three screening modalities gives the highest yield of patients potentially requiring chemoprophylaxis.

Post-bronchoscopy sputum: improving the diagnostic yield in smear negative pulmonary TB.

INTRODUCTION: Patients with suspected active Pulmonary Tuberculosis (PTB) who are Acid-Fast Bacilli (AFB) smear negative or non-productive of sputum may undergo bronchoalveolar lavage. However, post-bronchoscopy sputum (PBS) sampling is not routine. The aim of this study was to establish the potential diagnostic value of PBS sampling. METHODS: A retrospective study of patients attending a London University hospital with microbiologically confirmed PTB between January 2004 and December 2010. Patients who were AFB smear negative or non-productive of sputum were eligible if sputum sampling was performed within 7 days of bronchoscopy. RESULTS: Over the study period, 236 patients had microbiologically confirmed smear negative PTB of which 57 patients were eligible for the study. 15 patients (26.3%) were infected with HIV. 19 patients (33.3%) converted to AFB sputum smear positivity post-bronchoscopy and 5 patients (8.8%) were exclusively AFB sputum smear positive on PBS microscopy. Mycobacterium tuberculosis was cultured from the PBS of 43 patients (75.4%) and of these, 4 (7.0%) were exclusively PBS culture positive. CONCLUSION: PBS analysis can provide a simple method of rapidly diagnosing pulmonary tuberculosis. In this cohort, M. tuberculosis culture yield was increased by 7% through PBS sampling. This study has important infection control implications with nearly one third of patients becoming more infectious after bronchoscopy.

Utility of endobronchial ultrasound-guided transbronchial needle aspiration in patients with tuberculous intrathoracic lymphadenopathy: a multicentre study.

BACKGROUND: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has emerged as an important tool for the diagnosis and staging of lung cancer but its role in the diagnosis of tuberculous intrathoracic lymphadenopathy has not been established. The aim of this study was to describe the diagnostic utility of EBUS-TBNA in patients with intrathoracic lymphadenopathy due to tuberculosis (TB). METHODS: 156 consecutive patients with isolated intrathoracic TB lymphadenitis were studied across four centres over a 2-year period. Only patients with a confirmed diagnosis or unequivocal clinical and radiological response to antituberculous treatment during follow-up for a minimum of 6 months were included. All patients underwent routine clinical assessment and a CT scan prior to EBUS-TBNA. Demographic data, HIV status, pathological findings and microbiological results were recorded. RESULTS: EBUS-TBNA was diagnostic of TB in 146 patients (94%; 95% CI 88% to 97%). Pathological findings were consistent with TB in 134 patients (86%). Microbiological investigations yielded a positive culture of TB in 74 patients (47%) with a median time to positive culture of 16 days (range 3-84) and identified eight drug-resistant cases (5%). Ten patients (6%) did not have a specific diagnosis following EBUS; four underwent mediastinoscopy which confirmed the diagnosis of TB while six responded to empirical antituberculous therapy. There was one complication requiring an inpatient admission. CONCLUSIONS: EBUS-TBNA is a safe and effective first-line investigation in patients with tuberculous intrathoracic lymphadenopathy.

The rat arcuate nucleus integrates peripheral signals provided by leptin, insulin, and a ghrelin mimetic.

The hypothalamic circuits controlling food intake and body weight receive and integrate information from circulating satiety signals such as leptin and insulin and also from ghrelin, the only known circulating hormone that stimulates appetite following systemic injection. Activation of arcuate neurons by ghrelin and ghrelin mimetics (the growth hormone secretagogues) is augmented in 48-h-fasted rats compared with fed rats, as reflected by a greater number of cells expressing Fos protein in response to administration of the same maximally effective dose. Here we sought to determine whether this increased responsiveness in fasting might reflect or be influenced by low levels of circulating satiety factors such as leptin or insulin. Chronic central infusion of insulin or leptin during a 48-h fast suppressed the threefold increase in the Fos response to intravenous injection of a maximally effective dose of growth hormone-releasing peptide (GHRP)-6, a synthetic growth hormone secretagogue. This appears to be a direct central action of insulin and leptin because the marked decrease in plasma levels of insulin, leptin, and glucose during fasting were unaffected by central administration of either hormone. Furthermore, the GHRP-6-induced Fos response was twofold greater in obese leptin- and insulin-resistant Zucker rats compared with lean controls. These data provide evidence that the ghrelin-sensitive circuits in the hypothalamus are dynamically regulated by central insulin and leptin action.