[Fight against tuberculosis in the world]

Local Ancestry Adjusted Allelic Association Analysis Robustly Captures Tuberculosis Susceptibility Loci

Pulmonary tuberculosis (TB), caused by Mycobacterium tuberculosis, is a complex disease. The risk of developing active TB is in part determined by host genetic factors. Most genetic studies investigating TB susceptibility fail to replicate association signals particularly across diverse populations. South African populations arose because of multi-wave genetic admixture from the indigenous KhoeSan, Bantu-speaking Africans, Europeans, Southeast Asian-and East Asian populations. This has led to complex genetic admixture with heterogenous patterns of linkage disequilibrium and associated traits. As a result, precise estimation of both global and local ancestry is required to prevent both false positive and false-negative associations. Here, 820 individuals from South Africa were genotyped on the SNP-dense Illumina Multi-Ethnic Genotyping Array (∼1.7M SNPs) followed by local and global ancestry inference using RFMix. Local ancestry adjusted allelic association (LAAA) models were utilized owing to the extensive genetic heterogeneity present in this population. Hence, an interaction term, comprising the identification of the minor allele that corresponds to the ancestry present at the specific locus under investigation, was included as a covariate. One SNP (rs28647531) located on chromosome 4q22 was significantly associated with TB susceptibility and displayed a SNP minor allelic effect (G allele, frequency = 0.204) whilst correcting for local ancestry for Bantu-speaking African ancestry (p-value = 5.518 × 10^-7; OR = 3.065; SE = 0.224). Although no other variants passed the significant threshold, clear differences were observed between the lead variants identified for each ancestry. Furthermore, the LAAA model robustly captured the source of association signals in multi-way admixed individuals from South Africa and allowed the identification of ancestry-specific disease risk alleles associated with TB susceptibility that have previously been missed.

Modelling early events in Mycobacterium bovis infection using a co-culture model of the bovine alveolus

Bovine tuberculosis (bTB), a zoonosis mainly caused by Mycobacterium bovis has severe socio-economic consequences and impact on animal health. Host-pathogen interactions during M. bovis infection are poorly understood, especially early events which are difficult to follow in vivo. This study describes the utilisation of an in vitro co-culture model, comprising immortalised bovine alveolar type II (BATII) epithelial cells and bovine pulmonary arterial endothelial cells (BPAECs). When cultured at air-liquid interface, it was possible to follow the migration of live M. bovis Bacille Calmette-Guérin (BCG) and to observe interactions with each cell type, alongside cytokine release. Infection with BCG was shown to exert a detrimental effect primarily upon epithelial cells, with corresponding increases in IL8, TNFα, IL22 and IL17a cytokine release, quantified by ELISA. BCG infection increased expression of CD54, MHC Class I and II molecules in endothelial but not epithelial cells, which exhibited constitutive expression. The effect of peripheral blood mononuclear cell conditioned medium from vaccinated cattle upon apical-basolateral migration of BCG was examined by quantifying recovered BCG from the apical, membrane and basolateral fractions over time. The numbers of recovered BCG in each fraction were unaffected by the presence of PBMC conditioned medium, with no observable differences between vaccinated and naïve animals.

[Multidrug-resistant tuberculosis: A management problem that weighs heavily on the University Hospitals of Strasbourg]

INTRODUCTION

Multidrug-resistant tuberculosis (MDR-TB) is a major public health problem with great regional disparities. The aim of this study was to describe the epidemiological, clinical, and therapeutics aspects of MDR-TB in Alsace, France.

PATIENTS AND METHODS

A 10 years retrospective study, conducted for the years 2006 to 2016, of all MDR-TB cases diagnosed in Alsace and particularly in Strasbourg University Hospitals.

RESULTS

We included 22 patients with MDR-TB of whom 90% originated from Eastern Europe, 13.6% had extensively-resistant strains, and 41% reported previously treated tuberculosis. Clinically, 86,4% had a pulmonary form of tuberculosis. The mean length of antibiotic treatment was 21 months with several changes of drugs because of severe side effects. The mean follow-up was 48 months, during which time 2 patients were lost from contact and the 20 remaining patients were cured.

CONCLUSIONS

Management of MDR-TB is a real social and medical challenge. Our study shows that the therapeutic protocols used in the management of these patients lead to an unusually high rate of success despite the occurrence of several, sometimes severe, side effects.

l-Histidine, arachidonic acid, biliverdin, and l-cysteine-glutathione disulfide as potential biomarkers for cured pulmonary tuberculosis

Lack of laboratory standards for cured tuberculosis (TB) can lead to early discharge of untreated TB patients from the hospital, resulting in increased risk of TB spread and of developing drug resistant Mycobacterium tuberculosis (Mtb). We used ultra-high performance liquid chromatography coupled with mass spectrometry (LC-MS) to detect heparin anticoagulant in plasma of untreated TB patients, two-month treated TB patients, cured TB subjects, and healthy controls. Screening of differentially expressed metabolites resulted in identification of four differentially expressed metabolites such as, l-Histidine, Arachidonic acid (AA), Biliverdin, and l-Cysteine-glutathione disulfide after 6 months of TB treatment. Among them, l-Cysteine-glutathione disulfide and AA could be identified after 2 months of TB treatment. We established a cured TB model with an area under the curve (AUC) of 0.909 (95% CI, 0.802-0.970), 86.2% sensitivity, and 85.2% specificity. The diagnostic model fitted from the four differential metabolites in combination (l-Histidine, AA, Biliverdin, and l-Cysteine-glutathione disulfide) can be used as potential biomarkers for cured TB. Our study provided laboratory standards for hospital discharge of TB patients, as well as experimental basis for evaluating the efficacy of anti-TB drugs.

[HIV co-infection in patients followed up for tuberculosis in the Division of Infectious Diseases at the Ibn Rochd University Hospital in Casablanca]

This study aims to determine the prevalence of HIV infection among patients hospitalized for tuberculosis in the Division of Infectious Diseases at the Ibn Rochd University Hospital in Casablanca and factors associated with TB-HIV co-infection. We conducted a cross-sectional retrospective study in November 2016. The database of the Division of Infectious Diseases, Laboratory of Microbiology and Immunology at the Ibn Rochd University Hospital was examined. All the patients with tuberculosis confirmed using Lowenstein Jensen culture medium and HIV Infection confirmed using Western Blot test between January 2013 and December 2015 were included. During the study period, 117 cases of tuberculosis were confirmed by culture. Fourty six (39.3%) patients had confirmed HIV infection. Thirty-four co-infected patients (73.9%) had extrapulmonary tuberculosis (this form was associated with co-infection (p=0.04)). All patients underwent TB treatment and anti-retroviral treatment according to the indication. The Evolution was favorable in 32 patients (69.6%) and 10 deaths were recorded (21.7%). Mortality rate was higher in co-infected patients than in TB patients without HIV (8.4%), (p=0.04). This study highlights a relatively high prevalence of HIV infection among tuberculosis patients. TB-HIV co-infection is associated with severe forms of tuberculosis and with an increase in mortality rate among TB patients; hence the importance of strengthening anti-co-infection joint activities.

The Distribution Frequency of Interferon-Gamma Receptor 1 Gene Polymorphisms in Interferon-γ Release Assay-Positive Patients

Tuberculosis is caused by mycobacterium, a potentially fatal infectious bacterium. In recent years, TB cases increased in the whole world. WHO statistics data shows that the world's annual tuberculosis incidence was 8~10 million with about 3 million deaths. Several studies have shown that susceptibility to tuberculosis may be associated with IFNGR1 gene polymorphisms. Here, we report the distribution frequency of IFNGR1 gene polymorphisms in 103 cases of IGA-negative patients and 100 cases of IGA-positive patients from China by sequencing the IFNGR1 proximal ~750 bp promoter region. We found a total of 5 types of site mutations: -611 (G/A), -56 (T/C), -255 (C/T), -359 (T/C), and -72 (C/T). The two main types of gene polymorphisms among the IGA-negative and IGA-positive groups were -611 (G/A), with mutation rates of 88.3% and 78.4%, respectively, and -56 (T/C), with mutation rates of 84.5% and 83.8%, respectively, which had no statistical significance, and there was no correlation with the incidence of tuberculosis.