Tolu Oni

An interferon-inducible neutrophil-driven blood transcriptional signature in human tuberculosis

Tuberculosis (TB), caused by infection with Mycobacterium tuberculosis, is a major cause of morbidity and mortality worldwide. Efforts to control it are hampered by difficulties with diagnosis, prevention and treatment. Most people infected with M. tuberculosis remain asymptomatic, termed latent TB, with a 10% lifetime risk of developing active TB disease. Current tests, however, cannot identify which individuals will develop disease. The immune response to M. tuberculosis is complex and incompletely characterized, hindering development of new diagnostics, therapies and vaccines. Here we identify a whole-blood 393 transcript signature for active TB in intermediate and high-burden settings, correlating with radiological extent of disease and reverting to that of healthy controls after treatment. A subset of patients with latent TB had signatures similar to those in patients with active TB. We also identify a specific 86-transcript signature that discriminates active TB from other inflammatory and infectious diseases. Modular and pathway analysis revealed that the TB signature was dominated by a neutrophil-driven interferon (IFN)-inducible gene profile, consisting of both IFN-γ and type I IFN-αβ signalling. Comparison with transcriptional signatures in purified cells and flow cytometric analysis suggest that this TB signature reflects changes in cellular composition and altered gene expression. Although an IFN-inducible signature was also observed in whole blood of patients with systemic lupus erythematosus (SLE), their complete modular signature differed from TB, with increased abundance of plasma cell transcripts. Our studies demonstrate a hitherto underappreciated role of type I IFN-αβ signalling in the pathogenesis of TB, which has implications for vaccine and therapeutic development. Our study also provides a broad range of transcriptional biomarkers with potential as diagnostic and prognostic tools to combat the TB epidemic.

Randomized placebo-controlled trial of prednisone for paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome

Objective:Paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a frequent complication of antiretroviral therapy in resource-limited countries. We aimed to assess whether a 4-week course of prednisone would reduce morbidity in patients with paradoxical TB-IRIS without excess adverse events. Design:A randomized, double-blind, placebo-controlled trial of prednisone (1.5 mg/kg per day for 2 weeks then 0.75 mg/kg per day for 2 weeks). Patients with immediately life-threatening TB-IRIS manifestations were excluded. Methods:The primary combined endpoint was days of hospitalization and outpatient therapeutic procedures, which were counted as one hospital day. Results:One hundred and ten participants were enrolled (55 to each arm). The primary combined endpoint was more frequent in the placebo than the prednisone arm {median hospital days 3 [interquartile range (IQR) 0–9] and 0 (IQR 0–3), respectively; P = 0.04}. There were significantly greater improvements in symptoms, Karnofsky score, and quality of life (MOS-HIV) in the prednisone vs. the placebo arm at 2 and 4 weeks, but not at later time points. Chest radiographs improved significantly more in the prednisone arm at weeks 2 (P = 0.002) and 4 (P = 0.02). Infections on study medication occurred in more participants in prednisone than in placebo arm (27 vs. 17, respectively; P = 0.05), but there was no difference in severe infections (2 vs. 4, respectively; P = 0.40). Isolates from 10 participants were found to be resistant to rifampicin after enrolment. Conclusion:Prednisone reduced the need for hospitalization and therapeutic procedures and hastened improvements in symptoms, performance, and quality of life. It is important to investigate for drug-resistant tuberculosis and other causes for deterioration before administering glucocorticoids.

Reciprocal seasonal variation in vitamin D status and tuberculosis notifications in Cape Town, South Africa

Vitamin D deficiency is associated with susceptibility to tuberculosis (TB) in HIV-uninfected people in Europe, but it is not known whether such an association exists among HIV-infected people in subtropical Africa. We conducted a cross-sectional study to determine whether vitamin D deficiency was associated with susceptibility to active TB in HIV-uninfected (n = 196) and HIV-infected (n = 174) black Africans in Cape Town, South Africa. We also investigated whether there was evidence of seasonal variation in vitamin D status and TB notifications in this setting over an 8-y period. Vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D] <50 nmol/L) was present in 232 (62.7%) of 370 participants and was associated with active TB in both HIV-uninfected (odds ratio = 5.2, 95% confidence interval: 2.8–9.7; P < 0.001) and HIV-infected (odds ratio = 5.6, 95% confidence interval: 2.7–11.6; P < 0.001) people. Vitamin D status varied according to season: The mean serum 25(OH)D concentration was highest in January through March and lowest in July through September (56.8 vs. 30.7 nmol/L, respectively; P < 0.001). Reciprocal seasonal variation in TB notifications was observed: The mean number of TB notifications per quarter for Cape Town in 2003 to 2010 was lowest in April through June and highest in October through December (4,222 vs. 5,080; P < 0.001). Vitamin D deficiency is highly prevalent among black Africans in Cape Town and is associated with susceptibility to active TB both in the presence and absence of HIV infection. Reciprocal seasonal variation in serum 25(OH)D concentration and TB notifications suggests that seasonal variations in vitamin D status and TB incidence in this setting are causally related.

Neurologic Manifestations of Paradoxical Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome: A Case Series

BACKGROUND Paradoxical neurologic tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a potentially life-threatening condition that occurs within 3 months after starting combination antiretroviral therapy (ART). The reports in the published literature are anecdotal, and the prevalence and outcomes of neurologic TB-IRIS are unknown. METHODS We prospectively assessed patients with suspected TB-IRIS from June 2005 through October 2007 at our hospital in Cape Town, South Africa. We defined paradoxical TB-IRIS and paradoxical neurologic TB-IRIS with use of consensus clinical case definitions. We collected data on tuberculosis diagnosis, ART, details of TB-IRIS diagnosis, other opportunistic infections, corticosteroid use, and outcome. RESULTS We reviewed 279 patients with suspected TB-IRIS, 54 (19%) of whom had suspected neurologic TB-IRIS, and 225 (81%) of whom had suspected non-neurologic TB-IRIS. Paradoxical TB-IRIS was diagnosed in 190 patients; 23 (12%) of these 190 patients had neurologic TB-IRIS (95% confidence interval, 7%-17%). Eight had meningitis, 7 had tuberculoma, 5 had both tuberculoma and meningitis, and 3 had radiculomyelopathy. Twenty (87%) of the 23 patients with neurologic TB-IRIS required hospital admission (median duration, 12 days; interquartile range, 6-24 days), and 21 (91%) received corticosteroids (median duration, 58 days; interquartile range, 29-86 days). Outcomes 6 months after the initial assessment for neurologic deterioration were as follows: 16 (70%) of the patients were alive (10 of these patients had documented full physical and mental recovery), 3 (13%) were dead, and 4 (17%) were lost to follow-up. CONCLUSIONS Paradoxical neurologic TB-IRIS accounts for 12% of paradoxical TB-IRIS cases. Neurologic TB-IRIS causes considerable short-term morbidity but has reasonable long-term outcomes. Further research is needed to devise optimal diagnostic and management strategies for patients with tuberculosis who experience neurologic deterioration after starting ART.

Detectable Changes in The Blood Transcriptome Are Present after Two Weeks of Antituberculosis Therapy

Rationale Globally there are approximately 9 million new active tuberculosis cases and 1.4 million deaths annually. Effective antituberculosis treatment monitoring is difficult as there are no existing biomarkers of poor adherence or inadequate treatment earlier than 2 months after treatment initiation. Inadequate treatment leads to worsening disease, disease transmission and drug resistance. Objectives To determine if blood transcriptional signatures change in response to antituberculosis treatment and could act as early biomarkers of a successful response. Methods Blood transcriptional profiles of untreated active tuberculosis patients in South Africa were analysed before, during (2 weeks and 2 months), at the end of (6 months) and after (12 months) antituberculosis treatment, and compared to individuals with latent tuberculosis. An active-tuberculosis transcriptional signature and a specific treatment-response transcriptional signature were derived. The specific treatment response transcriptional signature was tested in two independent cohorts. Two quantitative scoring algorithms were applied to measure the changes in the transcriptional response. The most significantly represented pathways were determined using Ingenuity Pathway Analysis. Results An active tuberculosis 664-transcript signature and a treatment specific 320-transcript signature significantly diminished after 2 weeks of treatment in all cohorts, and continued to diminish until 6 months. The transcriptional response to treatment could be individually measured in each patient. Conclusions Significant changes in the transcriptional signatures measured by blood tests were readily detectable just 2 weeks after treatment initiation. These findings suggest that blood transcriptional signatures could be used as early surrogate biomarkers of successful treatment response.

Programmed death ligand 1 is over-expressed by neutrophils in the blood of patients with active tuberculosis

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains one of the worlds largest infectious disease problems. Despite decades of intensive study, the immune response to Mtb is incompletely characterised, reflecting the extremely complex interaction between pathogen and host. Pathways that may alter the balance between host protection and pathogenesis are therefore of great interest. One pathway shown to play a role in the pathogenesis of chronic infections, including TB, is the programmed death‐1 (PD‐1) pathway. We show here that the expression of the programmed death ligand 1 (PD‐L1), which interacts with PD‐1, is increased in whole blood from active TB patients compared with whole blood from healthy controls or Mtb‐exposed individuals, and that expression by neutrophils is largely responsible for this increase.

Doxycycline and HIV infection suppress tuberculosis-induced matrix metalloproteinases.

RATIONALE Tuberculosis kills more than 1.5 million people per year, and standard treatment has remained unchanged for more than 30 years. Tuberculosis (TB) drives matrix metalloproteinase (MMP) activity to cause immunopathology. In advanced HIV infection, tissue destruction is reduced, but underlying mechanisms are poorly defined and no current antituberculous therapy reduces host tissue damage. OBJECTIVES To investigate MMP activity in patients with TB with and without HIV coinfection and to determine the potential of doxycycline to inhibit MMPs and decrease pathology. METHODS Concentrations of MMPs and cytokines were analyzed by Luminex array in a prospectively recruited cohort of patients. Modulation of MMP secretion and Mycobacterium tuberculosis growth by doxycycline was studied in primary human cells and TB-infected guinea pigs. MEASUREMENTS AND MAIN RESULTS HIV coinfection decreased MMP concentrations in induced sputum of patients with TB. MMPs correlated with clinical markers of tissue damage, further implicating dysregulated protease activity in TB-driven pathology. In contrast, cytokine concentrations were no different. Doxycycline, a licensed MMP inhibitor, suppressed TB-dependent MMP-1 and -9 secretion from primary human macrophages and epithelial cells by inhibiting promoter activation. In the guinea pig model, doxycycline reduced lung TB colony forming units after 8 weeks in a dose-dependent manner compared with untreated animals, and in vitro doxycycline inhibited mycobacterial proliferation. CONCLUSIONS HIV coinfection in patients with TB reduces concentrations of immunopathogenic MMPs. Doxycycline decreases MMP activity in a cellular model and suppresses mycobacterial growth in vitro and in guinea pigs. Adjunctive doxycycline therapy may reduce morbidity and mortality in TB.

Safety, immunogenicity, and efficacy of the candidate tuberculosis vaccine MVA85A in healthy adults infected with HIV-1: a randomised, placebo-controlled, phase 2 trial

Summary Background HIV-1 infection is associated with increased risk of tuberculosis and a safe and effective vaccine would assist control measures. We assessed the safety, immunogenicity, and efficacy of a candidate tuberculosis vaccine, modified vaccinia virus Ankara expressing antigen 85A (MVA85A), in adults infected with HIV-1. Methods We did a randomised, double-blind, placebo-controlled, phase 2 trial of MVA85A in adults infected with HIV-1, at two clinical sites, in Cape Town, South Africa and Dakar, Senegal. Eligible participants were aged 18–50 years, had no evidence of active tuberculosis, and had baseline CD4 counts greater than 350 cells per μL if they had never received antiretroviral therapy or greater than 300 cells per μL (and with undetectable viral load before randomisation) if they were receiving antiretroviral therapy; participants with latent tuberculosis infection were eligible if they had completed at least 5 months of isoniazid preventive therapy, unless they had completed treatment for tuberculosis disease within 3 years before randomisation. Participants were randomly assigned (1:1) in blocks of four by randomly generated sequence to receive two intradermal injections of either MVA85A or placebo. Randomisation was stratified by antiretroviral therapy status and study site. Participants, nurses, investigators, and laboratory staff were masked to group allocation. The second (booster) injection of MVA85A or placebo was given 6–12 months after the first vaccination. The primary study outcome was safety in all vaccinated participants (the safety analysis population). Safety was assessed throughout the trial as defined in the protocol. Secondary outcomes were immunogenicity and vaccine efficacy against Mycobacterium tuberculosis infection and disease, assessed in the per-protocol population. Immunogenicity was assessed in a subset of participants at day 7 and day 28 after the first and second vaccination, and M tuberculosis infection and disease were assessed at the end of the study. The trial is registered with ClinicalTrials.gov, number NCT01151189. Findings Between Aug 4, 2011, and April 24, 2013, 650 participants were enrolled and randomly assigned; 649 were included in the safety analysis (324 in the MVA85A group and 325 in the placebo group) and 645 in the per-protocol analysis (320 and 325). 513 (71%) participants had CD4 counts greater than 300 cells per μL and were receiving antiretroviral therapy; 136 (21%) had CD4 counts above 350 cells per μL and had never received antiretroviral therapy. 277 (43%) had received isoniazid prophylaxis before enrolment. Solicited adverse events were more frequent in participants who received MVA85A (288 [89%]) than in those given placebo (235 [72%]). 34 serious adverse events were reported, 17 (5%) in each group. MVA85A induced a significant increase in antigen 85A-specific T-cell response, which peaked 7 days after both vaccinations and was primarily monofunctional. The number of participants with negative QuantiFERON-TB Gold In-Tube findings at baseline who converted to positive by the end of the study was 38 (20%) of 186 in the MVA85A group and 40 (23%) of 173 in the placebo group, for a vaccine efficacy of 11·7% (95% CI −41·3 to 44·9). In the per-protocol population, six (2%) cases of tuberculosis disease occurred in the MVA85A group and nine (3%) occurred in the placebo group, for a vaccine efficacy of 32·8% (95% CI −111·5 to 80·3). Interpretation MVA85A was well tolerated and immunogenic in adults infected with HIV-1. However, we detected no efficacy against M tuberculosis infection or disease, although the study was underpowered to detect an effect against disease. Potential reasons for the absence of detectable efficacy in this trial include insufficient induction of a vaccine-induced immune response or the wrong type of vaccine-induced immune response, or both. Funding European & Developing Countries Clinical Trials Partnership (IP.2007.32080.002), Aeras, Bill & Melinda Gates Foundation, Wellcome Trust, and Oxford-Emergent Tuberculosis Consortium.

High prevalence of subclinical tuberculosis in HIV-1-infected persons without advanced immunodeficiency: implications for TB screening

Background The prevalence of asymptomatic tuberculosis (TB) in recently diagnosed HIV-1-infected persons attending pre-antiretroviral therapy (ART) clinics is not well described. In addition, it is unclear if the detection of Mycobacterium tuberculosis in these patients clearly represents an early asymptomatic phase leading to progressive disease or transient excretion of bacilli. Objective To describe the prevalence and outcome of subclinical TB disease in HIV-1-infected persons not eligible for ART. Methods The study was conducted in 274 asymptomatic ART-naïve HIV-1-infected persons in Khayelitsha Day Hospital, Cape Town, South Africa. All participants were screened for TB using a symptom screen and spoligotyping was performed to determine genotypes. Results The prevalence of subclinical TB disease was 8.5% (95% CI 5.1% to 13.0%) (n=18; median days to culture positivity 17 days), with 22% of patients being smear-positive. Spoligotyping showed a diverse variety of genotypes with all paired isolates being of the same spoligotype, effectively excluding cross-contamination. 56% of patients followed up developed symptoms 3 days to 2 months later. All were well and still in care 6–12 months after TB diagnosis; 60% were started on ART. A positive tuberculin skin test (OR 4.96, p=0.064), low CD4 count (OR 0.996, p=0.06) and number of years since HIV diagnosis (OR 1.006, p=0.056) showed trends towards predicting TB disease. Conclusion This study found a high prevalence but good outcome (retained in care) of subclinical TB disease in HIV-1-infected persons. The results suggest that, in high HIV/TB endemic settings, a positive HIV-1 test should prompt TB screening by sputum culture irrespective of symptoms, particularly in those with a positive tuberculin skin test, longer history of HIV infection and low CD4 count. Operational difficulties in resource-constrained settings with respect to screening with TB culture highlight the need for rapid and affordable point-of-care tests to identify persons with clinical and subclinical TB disease.

Chronic diseases and multi-morbidity - a conceptual modification to the WHO ICCC model for countries in health transition

BackgroundThe burden of non-communicable diseases is rising, particularly in low and middle-income countries undergoing rapid epidemiological transition. In sub-Saharan Africa, this is occurring against a background of infectious chronic disease epidemics, particularly HIV and tuberculosis. Consequently, multi-morbidity, the co-existence of more than one chronic condition in one person, is increasing; in particular multimorbidity due to comorbid non-communicable and infectious chronic diseases (CNCICD). Such complex multimorbidity is a major challenge to existing models of healthcare delivery and there is a need to ensure integrated care across disease pathways and across primary and secondary care.DiscussionThe Innovative Care for Chronic Conditions (ICCC) Framework developed by the World Health Organization provides a health systems roadmap to meet the increasing needs of chronic disease care. This framework incorporates community, patient, healthcare and policy environment perspectives, and forms the cornerstone of South Africa’s primary health care re-engineering and strategic plan for chronic disease management integration. However, it does not significantly incorporate complexity associated with multimorbidity and CNCICD.Using South Africa as a case study for a country in transition, we identify gaps in the ICCC framework at the micro-, meso-, and macro-levels. We apply the lens of CNCICD and propose modification of the ICCC and the South African Integrated Chronic Disease Management plan. Our framework incorporates the increased complexity of treating CNCICD patients, and highlights the importance of biomedicine (biological interaction). We highlight the patient perspective using a patient experience model that proposes that treatment adherence, healthcare utilization, and health outcomes are influenced by the relationship between the workload that is delegated to patients by healthcare providers, and patients’ capacity to meet the demands of this workload. We link these issues to provider perspectives that interact with healthcare delivery and utilization.SummaryOur proposed modification to the ICCC Framework makes clear that healthcare systems must work to make sense of the complex collision between biological phenomena, clinical interpretation, beliefs and behaviours that follow from these. We emphasize the integration of these issues with the socio-economic environment to address issues of complexity, access and equity in the integrated management of chronic diseases previously considered in isolation.