[Show abstract][Hide abstract] ABSTRACT: Background:
Cryptococcal meningitis remains a significant cause of death among HIV-infected persons in Africa. We aimed to better understand the pathogenesis and identify immune correlates of mortality, particularly the role of monocyte activation.
A prospective cohort study was conducted in Cape Town, South Africa. Patients with first episode of cryptococcal meningitis were enrolled and immune responses assessed in unstimulated and stimulated blood using flow cytometry and cytokine analysis.
Sixty participants were enrolled (median CD4, 34 cells/μL). Mortality was 23% (14/60) at 14 days and 39% (22/57) at 12 weeks. Non-survivors were more likely to have an altered consciousness and higher CSF fungal burden at presentation. Principal component analysis identified an immune signature associated with early mortality characterized by monocyte deactivation (reduced HLA-DR expression and TNF-α response to LPS), raised serum IL-6, CXCL10 and IL-10, increased neutrophils, and decreased Th1 responses. This immune signature remained an independent predictor of early mortality after adjustment for conscious level and fungal burden, and was associated with higher serum titres of cryptococcal glucuronoxylomannan.
Cryptococcal-related mortality is associated with monocyte deactivation and an anti-inflammatory blood immune signature, possibly due to Cryptococcus modulation of host immune response. Validation in other cohorts is required.
Full-text · Article · Jan 2016 · The Journal of Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: Fungal burden in the cerebrospinal fluid is an important determinant of mortality in cryptococcal meningitis but its use to
aid clinical decision-making is hampered by the time involved to perform quantitative cultures. Here we demonstrate the potential
of flow cytometry as a novel and rapid technique to address this.
Full-text · Article · Dec 2015 · Journal of clinical microbiology
[Show abstract][Hide abstract] ABSTRACT: Objectives:
Blood-based Interferon-Gamma Release Assays (IGRA) identify Mycobacterium tuberculosis (MTB) sensitisation with increased specificity, but sensitivity remains impaired in human immunodeficiency virus (HIV) infected persons. The QuantiFERON-TB Gold In-Tube test contains peptide 38-55 of Rv2654c, based on data indicating differential recognition between tuberculosis patients and BCG vaccinated controls in Europe. We aimed to fine map the T cell response to Rv2654c with the view of improving sensitivity.
Interferon-gamma ELISpot assay was used in HIV uninfected persons with latent and active tuberculosis to map peptide epitopes of Rv2654c. A modified IGRA was tested in two further groups of 55 HIV uninfected and 44 HIV infected persons, recruited in South Africa.
The most prominently recognised peptide was between amino acids 51-65. Using p51-65 to boost the QuantiFERON-TB Gold In-Tube assay, the quantitative performance of the modified IGRA increased from 1.83 IU/ml (IQR 0.30-7.35) to 2.83 (IQR 0.28-12.2; p = 0.002) in the HIV uninfected group. In the HIV infected cohort the percentage of positive responders increased from 57% to 64% but only after 3 months of ART (p=ns).
Our data shows the potential to population tailor detection of MTB sensitization using specific synthetic peptides and interferon-gamma release in vitro.
Preview · Article · Nov 2015 · Journal of Infection
[Show abstract][Hide abstract] ABSTRACT: Background
Identifying those at increased risk of death during TB treatment is a priority in resource-constrained settings. We performed this study to determine predictors of mortality during TB treatment.
We performed a retrospective analysis of a TB surveillance population in a high HIV prevalence area that was recorded in ETR.net (Electronic Tuberculosis Register). Adult TB cases initiated TB treatment from 2007 through 2009 in Khayelitsha, South Africa. Cox proportional hazards models were used to identify risk factors for death (after multiple imputations for missing data). Model selection was performed using Akaike’s Information Criterion to obtain the most relevant predictors of death.
Of 16,209 adult TB cases, 851 (5.3 %) died during TB treatment. In all TB cases, advancing age, co-infection with HIV, a prior history of TB and the presence of both pulmonary and extra-pulmonary TB were independently associated with an increasing hazard of death. In HIV-infected TB cases, advancing age and female gender were independently associated with an increasing hazard of death. Increasing CD4 counts and antiretroviral treatment during TB treatment were protective against death. In HIV-uninfected TB cases, advancing age was independently associated with death, whereas smear-positive disease was protective.
We identified several independent predictors of death during TB treatment in resource-constrained settings. Our findings inform resource-constrained settings about certain subgroups of TB patients that should be targeted to improve mortality during TB treatment.
Full-text · Article · Oct 2015 · AIDS Research and Therapy
[Show abstract][Hide abstract] ABSTRACT: Objective:
Mycobacterium tuberculosis and Cryptococcus neoformans are major causes of meningitis in HIV-1-infected patients. Identifying differences in the inflammatory profiles of HIV-1-associated tuberculous meningitis (TBM) and cryptococcal meningitis may inform differences in immunopathogenic mechanisms in these diseases. In this study we compared the clinical and inflammatory features of HIV-1-associated TBM, and cryptococcal meningitis.
A prospective study of HIV-1-infected adults who presented with either TBM [antiretroviral therapy (ART)-naive] or cryptococcal meningitis (regardless of ART prescription). Clinical and laboratory findings and concentrations of 40 inflammatory mediators measured in cerebrospinal fluid (CSF, 33 paired with blood) were compared between TBM and cryptococcal meningitis patients regardless of ART prescription and between TBM and cryptococcal meningitis patients not receiving ART.
Clinical and laboratory findings were similar in TBM (n=34) and cryptococcal meningitis (n = 19; ART prescribed: n = 10, no ART prescribed: n = 9). Exceptions included a higher median CD4 cell count [interquartile: 113 (69-199) vs. 25 (8-49) cells/μl, P = 0.0001] and higher HIV-1 median viral load [plasma: 5.46 (4.82-5.89) vs. 4.87 (4.36-5.17) log10copies/ml, P = 0.037; CSF: 6.05 (5.43-6.56) vs. 5.56 (4.52-5.80) log10copies/ml, P = 0.03] in TBM vs. cryptococcal meningitis patients not receiving ART. CSF interleukin (IL)-17A was lower in TBM compared with cryptococcal meningitis [1.00 (0.25-2.35) vs. 9.31 (1.24-23.36) pg/ml, P-adjusted = 0.03].
Despite presenting with higher peripheral CD4 cell counts, TBM patients also presented with higher HIV-1 viral loads compared with cryptococcal meningitis patients, suggesting a greater propensity of M. tuberculosis compared with C. neoformans to increase HIV-1 replication in vivo. CSF IL-17A was lower in TBM; its role in the immunopathogenesis of TBM and cryptococcal meningitis deserves further research.
[Show abstract][Hide abstract] ABSTRACT: Patients co-infected with HIV-1 and tuberculosis (TB) are at risk of developing TB-associated immune reconstitution inflammatory syndrome (TB-IRIS) following commencement of antiretroviral therapy (ART). TB-IRIS is characterized by transient but severe localized or systemic inflammatory reactions against Mycobacterium tuberculosis antigens. Here, we review the risk factors and clinical management of TB-IRIS, as well as the roles played by different aspects of the immune response in contributing to TB-IRIS pathogenesis.
Preview · Article · Oct 2015 · Seminars in Immunopathology
[Show abstract][Hide abstract] ABSTRACT: Studies looking at acquired drug resistance (ADR) are diverse with respect to geographical distribution, HIV co-infection rates, retreatment status and programmatic factors such as regimens administered and directly observed therapy. Our objective was to examine and consolidate evidence from clinical studies of the multifactorial aetiology of acquired rifamycin and/or isoniazid resistance within the scope of a single systematic review. This is important to inform policy and identify key areas for further studies.
[Show abstract][Hide abstract] ABSTRACT: Latent tuberculosis infection (LTBI) is characterised by the presence of immune responses to previously acquired Mycobacterium tuberculosis infection without clinical evidence of active tuberculosis (TB). Here we report evidence-based guidelines from the World Health Organization for a public health approach to the management of LTBI in high risk individuals in countries with high or middle upper income and TB incidence of <100 per 100 000 per year. The guidelines strongly recommend systematic testing and treatment of LTBI in people living with HIV, adult and child contacts of pulmonary TB cases, patients initiating anti-tumour necrosis factor treatment, patients receiving dialysis, patients preparing for organ or haematological transplantation, and patients with silicosis. In prisoners, healthcare workers, immigrants from high TB burden countries, homeless persons and illicit drug users, systematic testing and treatment of LTBI is conditionally recommended, according to TB epidemiology and resource availability. Either commercial interferon-gamma release assays or Mantoux tuberculin skin testing could be used to test for LTBI. Chest radiography should be performed before LTBI treatment to rule out active TB disease. Recommended treatment regimens for LTBI include: 6 or 9 month isoniazid; 12 week rifapentine plus isoniazid; 3-4 month isoniazid plus rifampicin; or 3-4 month rifampicin alone.
Full-text · Article · Sep 2015 · European Respiratory Journal
[Show abstract][Hide abstract] ABSTRACT: Patients with HIV-associated tuberculosis (TB) initiating antiretroviral therapy (ART) may develop immune reconstitution inflammatory syndrome (TB-IRIS). No biomarkers for TB-IRIS have been identified and the underlying mechanisms are unclear. Here we perform transcriptomic profiling of the blood samples of patients with HIV-associated TB. We identify differentially abundant transcripts as early as week 0.5 post ART initiation that predict downstream activation of proinflammatory cytokines in patients who progress to TB-IRIS. At the characteristic time of TB-IRIS onset (week 2), the signature is characterized by over-representation of innate immune mediators including TLR signalling and TREM-1 activation of the inflammasome. In keeping with the transcriptional data, concentrations of plasma cytokines and caspase-1/5 are elevated in TB-IRIS. Inhibition of MyD88 adaptor and group 1 caspases reduces secretion of cytokines including IL-1 in TB-IRIS patients. These data provide insight on the pathogenesis of TB-IRIS and may assist the development of specific therapies.
[Show abstract][Hide abstract] ABSTRACT: Rationale:
Experimental and epidemiological evidence suggests that neutrophils are important in the host response to tuberculosis. HIV infection, which increases the risk of tuberculosis, adversely affects neutrophil function.
To determine the impact of HIV and antiretroviral therapy on neutrophil antimycobacterial activity.
We performed a cross-sectional comparison of neutrophil functions in 20 antiretroviral-naïve HIV-infected and 20 HIV-uninfected individuals utilising luminescence-, flow cytometry- and ELISA-based assays. We then conducted a prospective study in the HIV-infected individuals investigating these parameters during the first 6 months of antiretroviral therapy. Surface markers of neutrophil activation were investigated in a separate cohort using flow cytometry.
Measurements and main results:
HIV infection impaired control of M.tuberculosis by neutrophils (mean ratio of mycobacterial luminescence in neutrophil samples vs. serum controls at one hour in HIV-infected participants 0.88 ±0.13 versus HIV-uninfected participants 0.76 ±0.14, p=0.01; at 24 hours 0.82 ±0.13 vs. 0.71 ±0.13, p=0.01). The extent of impairment correlated with log[HIV viral load]. Neutrophil cell death after 24 hours' incubation with M.tuberculosis was higher in the HIV-infected cohort (85.3 ±11.8% vs. 57.9 ±22.4% necrotic cells, p<0.0001). Neutrophils from HIV-infected participants demonstrated significantly more CD62L-negative cells (median 23.0% vs. 8.5%, p=0.008) and CD16-negative cells (3.2% vs. 1.3%, p=0.03). Antiretroviral therapy restored mycobacterial restriction and pattern of neutrophil death towards levels seen in HIV-uninfected persons.
Neutrophils in antiretroviral-naïve HIV-infected persons are hyperactivated, eliminate M.tuberculosis less effectively than in HIV-uninfected individuals and progress rapidly to necrotic cell death. These factors are ameliorated by antiretroviral therapy.
No preview · Article · Sep 2015 · Annals of the American Thoracic Society
[Show abstract][Hide abstract] ABSTRACT: The treatment of tuberculosis is based on combinations of drugs that directly target Mycobacterium tuberculosis. A new global initiative is now focusing on a complementary approach of developing adjunct host-directed therapies.
[Show abstract][Hide abstract] ABSTRACT: Case fatality among inpatients with HIV-associated tuberculosis (HIV-TB) in Africa is high. We investigated the factors associated with mortality in a rural South African hospital.
This was a prospective observational study of HIV-TB inpatients, with death by eight weeks the endpoint.
Of ninety-nine patients (median CD4 count 72 cells/mm), thirty-two (32%) died, after median 8 days TB treatment. TB was diagnosed microbiologically in 75/99 and clinico-radiologically in 24, with no mortality difference between these groups (31% vs. 38% (p=0.53)). Median venous lactate was 5.5 mmol/l (IQR 3.9, 6.2) in those who died, 3.1 mmol/l (IQR 2.2, 4.1) in survivors (p<0.001). In multivariable analysis lactate ≥4 mmol/L (adjusted odds ratio [aOR] 9.8, 95% confidence interval [CI] 3.0-32.2), Glasgow Coma Score <15 (aOR 6.6, 95% CI 1.5-29.6), CD4 count <50 cells/mm (aOR 5.5, 95% CI 1.6-18.5) and age ≥50 (aOR 7.7, 95% CI 1.2-46.9) independently predicted death. In a nested case-control study, comparing those who died versus CD4-matched survivors, median plasma lipopolysaccharide concentrations were 93 and 57 pg/mL (p=0.026) and intestinal fatty acid binding protein 132 and 0 pg/mL (p=0.002).
Mortality was high and predicted by elevated lactate, likely reflecting a sepsis-syndrome secondary to TB or bacterial co-infection with intestinal barrier dysfunction appearing to contribute.
[Show abstract][Hide abstract] ABSTRACT: Host-range restricted poxviruses make promising vaccine vectors due to their safety profile and immunogenicity. An understanding of the host innate immune responses produced by different poxvirus vectors would aid in the assessment, selection and rational design of improved vaccines for human and veterinary applications. Novel avipoxviruses are being assessed to determine if they are different from other poxvirus vectors. Analysis of the transcriptome induced in a mouse model would aid in determining if there were significant differences between different poxvirus vectors which may reflect different adjuvant potential as well as establish if they should be further evaluated as vaccine vectors.
We compared host transcript abundance in the spleens of BALB/c mice twenty four hours after intravenous infection (10(5) pfu/mouse) with six host-restricted poxvirus species from three genera, namely Lumpy Skin Disease virus (LSDV), Canarypox virus (CNPV), Fowlpox virus (FWPV), modified vaccinia Ankara (MVA) and two novel South African avipoxviruses, Feral Pigeonpox virus (FeP2) and Penguinpox virus (PEPV). These six viruses produced qualitatively and quantitatively distinct host responses with LSDV, followed by MVA, inducing the greatest interferon (IFN) response. FeP2 and PEPV caused very little change to host transcript abundance compared to the other 4 viruses tested. CNPV and FWPV induced the up regulation of two immunoglobulin genes (Ighg and Ighg3 (IgG3)) with CNPV inducing a third, Ighm (IgM). HIV-1-specific IgG3 antibodies have been correlated with decreased risk of HIV-1 infection in the RV144 trial, which included a CNPV-based vector (Yates et al. (Sci Transl Med, 6(228) p228, 2014). Up regulation of IgG3 by CNPV and FWPV but not the other poxviruses tested in vivo, implies that these two avipoxvirus-vector backbones may be involved in stimulation of the clinically important IgG3 antibody subclass. Differential transcript abundance associated with the different poxviruses is further discussed with particular emphasis on responses related to immune responses.
Six, genetically diverse host-restricted poxviruses produce different responses in a mouse model early after infection. These differences may affect the immune response induced to vaccine antigen in vectors based on these viruses. The two novel avipoxviruses were clearly distinguishable from the other viruses.
[Show abstract][Hide abstract] ABSTRACT: Adjunctive vitamin D treatment for pulmonary tuberculosis enhances resolution of inflammation but has modest effects on bacterial clearance. Sodium 4-phenylbutyrate (PBA) is in clinical use for a range of conditions and has been shown to synergise with vitamin D metabolites to upregulate cathelicidin antimicrobial peptide (CAMP) expression. We investigated whether clinically attainable plasma concentrations of PBA (0.4-4mM) directly affect Mycobacterium tuberculosis (Mtb) growth and human macrophage and PBMC response to infection. We also tested the ability of PBA to enhance the immunomodulatory actions of the vitamin D metabolite 25(OH)D3 during infection and synergistically inhibit intracellular Mtb growth. PBA inhibited Mtb growth in broth with an MIC99 of 1mM, which was reduced to 0.25mM by lowering pH. During human macrophage infection, PBA treatment restricted Mtb uptake, phagocytic receptor expression and intracellular growth in a dose-dependent manner. PBA independently regulated CCL chemokine secretion and induced expression of the antimicrobial LTF (lactoferrin), the anti-inflammatory PROC (protein C) and multiple genes within the NLRP3 inflammasome pathway. PBA co-treatment with 25(OH)D3 synergistically modulated expression of numerous vitamin D-response genes, including CAMP, CYP24A1, CXCL10 and IL-37. This synergistic effect was dependent on MAPK signalling, while the effect of PBA on LTF, PROC and NLRP3 was MAPK-independent. During PBA and 25(OH)D3 co-treatment of human macrophages, in the absence of exogenous proteinase 3 (PR3) to activate cathelicidin, Mtb growth restriction was dominated by the effect of PBA, while the addition of PR3 enhanced growth restriction by 25(OH)D3 and PBA co-treatment. This suggests that PBA augments vitamin D-mediated cathelicidin-dependent Mtb growth restriction by human macrophages and independently induces antimicrobial and anti-inflammatory action. Therefore through both host-directed and bacterial-directed mechanisms PBA and vitamin D may prove an effective combinatorial adjunct therapy for tuberculosis to both resolve immunopathology and enhance bacterial clearance.