Chloe Wyndham-Thomas

Key Role of Effector Memory CD4+ T Lymphocytes in a Short-Incubation Heparin-Binding Hemagglutinin Gamma Interferon Release Assay for the Detection of Latent Tuberculosis

ABSTRACT The treatment of latent tuberculosis infection (LTBI) in target populations is one of the current WHO strategies for preventing active tuberculosis (TB) infection and reducing the Mycobacterium tuberculosis reservoir. Therefore, powerful LTBI screening tools are indispensable. A gamma interferon release assay (IGRA) in response to the stimulation of peripheral blood mononuclear cells by the latency antigen native heparin-binding hemagglutinin (nHBHA-IGRA) has proven its potential for this purpose. We have evaluated its possible optimization through a reduction of incubation time from 96 to 24 h, while compensating for this by adding interleukin 7 (IL-7) to the medium. We have also investigated the phenotypes of the gamma interferon (IFN-γ)-producing cells after both short and long incubation times. One hundred thirty-one nonimmunocompromised patients were recruited from 3 Brussels-based university hospitals. They were divided into 1 of 4 subgroups according to their M. tuberculosis infection status (LTBI, TB infection, undetermined M. tuberculosis infection status, and noninfected controls). The novel 24-h nHBHA-IGRA was performed for all subjects, and a simultaneous 96-h classical HBHA-IGRA was performed for 79 individuals. The results showed a good correlation between the two tests, and the novel 24-h nHBHA-IGRA maintained the principal advantages of the classical test, namely, a high specificity for LTBI diagnosis, an absence of interference of Mycobacterium bovis BCG vaccination during infancy, and a relative discrimination between LTBI and TB infection. Whereas the commercialized IGRAs show a greater sensitivity for recent than for remote M. tuberculosis infections, the 24-h nHBHA-IGRA appears to have comparable diagnostic powers for recent and remote LTBI. The IFN-γ detected by the 24-h nHBHA-IGRA was mainly secreted by effector memory CD4+ T lymphocytes, a finding suggestive of continuous HBHA presentation during latency.

Immunological Signatures Identifying Different Stages of Latent Mycobacterium tuberculosis Infection and Discriminating Latent from Active Tuberculosis in Humans

Objectives: One third of the world population is considered latently infected with Mycobacterium tuberculosis (LTBI) and sterilizing this reservoir of bacteria that may reactivate is required for tuberculosis (TB) elimination. The group of individuals with LTBI is heterogeneous with some of them being more at risk to develop TB disease than others. Improved diagnosis of subjects with LTBI is needed, allowing to differentiate subjects with LTBI from those with active TB, and to select among LTBI subjects those who are more at risk to develop active TB. We have characterized at the cellular level both the quantitative and qualitative T cell responses to different mycobacterial antigens in selected populations of infected subjects in order to identify new biomarkers that could help to identify M. tuberculosis-infected subjects and to stratify them in risk groups for reactivation of the infection. Methods: lymphoblast frequencies and cytokine production (IFN-γ, TNF-α, IL-2) among CD4+ and CD8+ T cells were analyzed by flow cytometry after in vitro stimulation with the latency antigen heparin-binding haemagglutinin (HBHA) or early-secreted antigen Target-6 (ESAT-6) of peripheral blood mononuclear cells from clinically well characterized M. tuberculosis-infected humans (28 LTBI, 22 TB disease,12 controls). The LTBI group defined according to the Center for Disease Control guidelines was subdivided into QuantiFERON-TB Gold in-Tube (QFT) positive and negative subgroups. Results: similar to TB patients, QFT+ LTBI subjects had higher proportions of HBHA-induced TNF-αsingle+ CD4+ lymphocytes than QFT- LTBI subjects (p<0.05). Compared to LTBI subjects, TB patients had higher frequencies of ESAT-6-induced CD8+ lymphoblasts (p<0.001), higher proportions of ESAT-6-induced IFN-γ+TNF-α+ CD4+ T lymphocytes (p<0.05), and lower proportions of HBHA-induced IFN-γ+TNF-α+IL-2+ (p<0.05) CD4+ T lymphocytes. Conclusions: these data provide new biomarkers to discriminate active TB from LTBI, and more interestingly, help to identify LTBI subjects with increased likelihood to develop TB disease.

Implementation of latent tuberculosis screening in HIV care centres: evaluation in a low tuberculosis incidence setting.

The screening and treatment of latent tuberculosis infection (LTBI) to prevent active tuberculosis (TB) is recommended by the WHO in all HIV-infected patients. The aim of this study was to evaluate its implementation within Belgiums HIV care. A multiple-choice questionnaire was sent to 55 physicians working in the countrys AIDS reference centres. Response rate reached 62%. Only 20% screened all their HIV-infected patients for LTBI. Screening methods used and their interpretation vary from one physician to another. The main barriers to the implementation of LTBI screening and treatment, as perceived by the participants, are lack of sensitivity of screening tools, risks associated with polypharmacy and toxicity of treatment. The poor coverage of LTBI screening reported here and the inconsistency in methods used raises concern. However, this was not unexpected as, in low-TB incidence countries, who, when and how to screen for LTBI remains unclear and published guidelines show important disparities. Recently, a targeted approach in which only HIV-infected patients at highest risk of TB are screened has been suggested. Such a strategy would limit unnecessary exposure to LTBI treatment. This methodology was approved by 80% of the participants and could therefore achieve greater coverage. Its clinical validation is still pending.

Immune Activation by Mycobacterium tuberculosis in HIV-Infected and -Uninfected Subjects.

Introduction: This study investigates the influence of Mycobacterium tuberculosis infection on immune activation biomarkers, both in HIV-infected and -uninfected subjects. Methods: Forty-eight treatment-naive HIV-infected patients and 74 HIV-uninfected subjects were recruited and divided into groups according to their M. tuberculosis infection status: latent tuberculosis infection (LTBI), active tuberculosis (TB), and no evidence of M. tuberculosis infection. The expression of cellular markers CD38 and HLA-DR on circulating CD8+ T lymphocytes and the plasmatic levels of soluble markers interleukin-6, sCD14, and D-Dimer were measured and compared between groups. The HIV-infected patients with no evidence of M. tuberculosis or with LTBI who initiated antiretroviral treatment were tested again for these biomarkers once viral suppression was reached. Results: In both HIV-infected and -uninfected groups, patients with TB had higher levels of immune activation markers than subjects with LTBI and with no evidence of M. tuberculosis. Among the HIV-uninfected subjects, no significant difference in biomarker level was found between those presenting LTBI and those with no evidence of M. tuberculosis. The effect of LTBI on activation biomarkers in the HIV-infected groups was inconclusive because of the small number of individuals in the HIV+/LTBI group. sCD14 and D-Dimer levels were significantly higher in the TB-only group than in the HIV-only group. Discussion: Although TB is associated with an increase in biomarkers of immune activation, the effect of LTBI is less evident. Further investigation is warranted, and according to our results, soluble markers may offer greater sensitivity for the evaluation of M. tuberculosis–associated immune activation than cellular markers.

Response of Human Immunodeficiency Virus-Associated Cerebral Angiitis to the Combined Antiretroviral Therapy

When secondary causes are excluded, mechanisms underlying central nervous system angiitis (ACNS) in human immunodeficiency virus (HIV)-infected patients are still not understood and optimal treatment remains undefined. We report here a patient with an untreated HIV infection who presented multiple ischemic strokes probably due to HIV-ACNS. ACNS signs on vessel-wall imaging magnetic resonance monitoring retracted with combined antiretroviral therapy without adjunct immunosuppressive drugs.

Blood tolerogenic monocytes and low proportions of dendritic cell subpopulations are hallmarks of human tuberculosis

The immune mechanisms underlying the pathogenesis of tuberculosis (TB) need better understanding to improve TB management, as the disease still causes more than 1.5 million deaths annually. This study tested the hypothesis that a modulation of the proportions or activation status of APC during Mycobacterium tuberculosis infection may impact on the course of the disease.

Prevalence of non-infectious comorbidities in the HIV-positive population in Belgium: a multicenter, retrospective study

Abstract Objectives: In Belgium, eleven AIDS Reference Centers (ARCs) and seven AIDS Reference Laboratories diagnose and treat HIV-positive individuals and track patients under care. As AIDS-related deaths are avoided and the HIV-positive population ages, non-infectious comorbidities (NICMs), such as cardiovascular disease, renal disease and certain cancers, play a larger role in the quality and length of patients’ lives. This study aims to characterize the HIV-positive population in Belgium in terms of the prevalence of key NICMs. Methods: We performed a retrospective study of 5787 HIV-positive patients under follow-up at four ARCs across Belgium between 1st of June 2014 and 1st of July 2016. Results: The mean age of patients under follow-up was 46.7 (SD = 11.6) years, and the mean nadir CD4 count was 268.8 cells/mm3 (SD = 189.5). The prevalence of diabetes mellitus, arterial hypertension and chronic kidney disease (CKD) were 5.9, 31 and 7.8%, respectively. Cardiovascular events, defined as the occurrence of myocardial infarction, stroke or an invasive coronary procedure, occurred in 2.9% of patients. The highest age-adjusted mortality rates were observed among patients 51–55 years of age. Mortality rates were also higher among patients with CKD and patients with viremic hepatitis C virus (p < 0.05). Conclusions: Helping the aging HIV-positive population avoids premature morbidity and mortality from NICMs represents a key challenge to further improve patient outcomes. Belgium has an advanced system of HIV care and patient management; however, standardized data collection across ARCs is needed to improve knowledge sharing and to support future countrywide analyses.

2018 Belgian guidelines for the screening for latent tuberculosis in HIV-infected patients

ABSTRACT Objectives: To review the current knowledge on screening for latent tuberculosis infection (LTBI) in HIV-infected adults and provide specific guidelines for Belgium. Focus is given to who to test, which testing method to use, timing of screening and choice of LTBI treatment. Methods: Expert review by the members of the Belgian LTBI group, in consultancy with the ARC College. Results: Target population, timing of screening, testing method, active TB exclusion, treatment of LTBI and guideline implementation are all reviewed. Conclusions: The principal changes include a selective approach to screen for LTBI (screening only of the HIV-infected patients at highest risk of active TB) as well as the timing of screening (testing for LTBI performed only after immune-restauration by antiretroviral therapy).

Screening for Chlamydia trachomatis and Neisseria gonorrhoeae infections in MSM: Diagnostic accuracy of NAAT on pooled urine, anorectal and pharyngeal specimens

Abstract Neisseria gonorrhoeae and Chlamydia trachomatis screening was performed in a cohort of 100 men who have sex with men. A nucleic acid amplification test on a pooled sample of first-pass urine, pharyngeal, and anorectal specimens was compared with results on nonpooled samples. Despite an excellent agreement (Cohen &kgr;, 0.932), pooling specimens reduced test sensitivity to 89.5%.

BARRIERS TO LIVER TRANSPLANTATION IN HIV INFECTED PATIENTS

Abstract Objectives: Liver disease is one of the most frequent causes of non AIDS related deaths in HIV patients and transplantation has become a therapeutic option. In spite of this progress, no liver transplantation has ever been recorded for the patients of the Brussels Saint-Pierre HIV Cohort. The aim of this study is to identify the barriers to liver transplantation in HIV patients that arise in our practice. Methods: All patients enrolled in the Brussels Saint-Pierre HIV Cohort presenting a theoretical indication for liver transplantation, as recommended by the AASLD, between 01/01/2002 and 01/07/2010 were considered. The reasons for not retaining these patients as candidates for liver transplantation were classified as HIV or non-HIV related. Results: Nineteen patients were identified. All patients presented an HBV and/or HCV co-infection. Indication for liver transplantation was based on first severe complication of cirrhosis for 15 patients, hepatocellular carcinoma fulfilling the Milan criteria for 2 and chronic liver failure for 2 others. Three patients could have been transplantation candidates but only one was enlisted and died prior to transplantation whilst alternative treatments were chosen for the remaining two. Among the non candidates, 5 couldn’t be enlisted for HIV-related reasons, 3 for non HIV related reasons and 8 on multi-factorial grounds; non adherence to treatment, alcohol abuse, psychiatric disease and hepatotoxicities playing key roles. Eleven patients died, all within 12 months of their first major complication of cirrhosis. Conclusions: The undeniable medical progress that liver transplantation represents for HIV-infected individuals is, in practise, limited; only a minority of patients with an indication of liver transplant will fulfill the necessary criteria for enlistment. General awareness of this issue and early referral are essential to optimize pre-transplant management and increase the number of HIV patients developing ESLD that will be able to benefit from this cure.