[show abstract][hide abstract] ABSTRACT: In patients infected with human immunodeficiency virus 1 (HIV-1) neuropathic symptoms may develop within weeks of starting combination antiretroviral therapy (cART). This timing coincides with the occurrence of immune reconstitution inflammatory syndrome. Our objective was to investigate the longitudinal association of plasma cytokine and soluble receptor concentrations with incident neuropathic symptoms within 12 weeks of starting programme-based cART in a nested case-control study.
One hundred and twenty adults without neuropathic symptoms and about to initiate cART were followed longitudinally for 24 weeks after cART initiation. Subjects were examined for peripheral neuropathy at baseline (pre-cART) and 2-, 4-, 12- and 24 weeks thereafter. Individuals developing neuropathic symptoms within 12 weeks of starting cART were matched in a nested case-control design with those remaining symptom-free for at least 24 weeks. Plasma was collected at each visit. Cytokines and soluble receptors were quantified using multiplex immunometric assays.
Incident neuropathic symptoms occurred in 32 (27%) individuals within 12 weeks of starting cART for the first time. Cytokine concentrations increased at 2 weeks, irrespective of symptom-status, returning to baseline concentrations at 12 weeks. Compared to the control group, the symptomatic group had higher baseline levels of interleukin-1 receptor (IL-1R)-antagonist. The symptomatic group also showed greater increases in soluble interleukin-2 receptor-alpha and tumour necrosis factor (TNF) receptor-II levels at week 2 and soluble interleukin-6 receptor levels at week 12. Ratios of pro-inflammatory- vs anti-inflammatory cytokines were higher for TNF-alpha/IL-4 (p = 0.022) and interferon-gamma/IL-10 (p = 0.044) in those developing symptoms. After 24 weeks of cART, the symptomatic group showed higher CD4+ counts (p = 0.002).
The initiation of cART in previously treatment naive individuals was associated with a cytokine 'burst' between 2- and 4 weeks compared with pre-cART levels. Individuals developing neuropathic symptoms within 12 weeks of starting cART showed evidence of altered cytokine concentrations even prior to initiating cART, most notably higher circulating IL-1R-antagonist levels, and altered ratios of "pain-associated" cytokine and soluble receptors shortly after cART initiation.
[show abstract][hide abstract] ABSTRACT: Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS) develops in 9 %-47 % of persons with HIV infection and a CNS opportunistic infection who start antiretroviral therapy and is associated with a mortality rate of 13 %-75 %. These rates vary according to the causative pathogen. Common CNS-IRIS events occur in relation to Cryptococcus, tuberculosis (TB), and JC virus, but several other mycobacteria, fungi, and viruses have been associated with IRIS. IRIS symptoms often mimic the original infection, and diagnosis necessitates consideration of treatment failure, microbial resistance, and an additional neurological infection. These diagnostic challenges often delay IRIS diagnosis and treatment. Corticosteroids have been used to treat CNS-IRIS, with variable responses; the best supportive evidence exists for the treatment of TB-IRIS. Pathogenic mechanisms vary: Cryptococcal IRIS is characterized by a paucity of cerebrospinal inflammation prior to antiretroviral therapy, whereas higher levels of inflammatory markers at baseline predispose to TB meningitis IRIS. This review focuses on advances in the understanding of CNS-IRIS over the past 2 years.
[show abstract][hide abstract] ABSTRACT: The HIV-TB associated immune reconstitution inflammatory syndrome (TB-IRIS) can complicate combined treatments for HIV-1 and TB. Little is known about tissue damage in TB-IRIS. Matrix metalloproteinases (MMPs) degrade components of the extracellular matrix and consequently may play a role in such immunopathology. Here we investigated the involvement of MMPs in TB-IRIS. We determined MMP transcript abundance and secreted protein in M. tuberculosis-stimulated PBMCs from 22 TB-IRIS patients and 22 non-IRIS controls. We also measured MMP protein levels in corresponding serum and the effect of prednisone - which reduces the duration of symptoms in IRIS patients - or placebo treatment on MMP transcript and circulating MMP protein levels. PBMCs from TB-IRIS had increased MMP-1, -3, -7, and -10 transcript levels when compared with those of controls at either 6 or 24 hours. Similarly, MMP-1, -3, -7, and -10 protein secretion in stimulated cultures was higher in TB-IRIS than in controls. Serum MMP-7 concentration was elevated in TB-IRIS and 2 weeks of corticosteroid therapy decreased this level, although not significantly. TB-IRIS is associated with a distinct pattern of MMP gene and protein activation. Modulation of dysregulated MMP activity may represent a novel therapeutic approach to alleviate TB-IRIS in HIV-TB patients undergoing treatment. This article is protected by copyright. All rights reserved.
European Journal of Immunology 10/2013; · 4.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: A major impediment to tuberculosis control in Africa is the difficulty in diagnosing active tuberculosis (TB), particularly in the context of HIV infection. We hypothesized that a unique host blood RNA transcriptional signature would distinguish TB from other diseases (OD) in HIV-infected and -uninfected patients, and that this could be the basis of a simple diagnostic test.
Adult case-control cohorts were established in South Africa and Malawi of HIV-infected or -uninfected individuals consisting of 584 patients with either TB (confirmed by culture of Mycobacterium tuberculosis [M.TB] from sputum or tissue sample in a patient under investigation for TB), OD (i.e., TB was considered in the differential diagnosis but then excluded), or healthy individuals with latent TB infection (LTBI). Individuals were randomized into training (80%) and test (20%) cohorts. Blood transcriptional profiles were assessed and minimal sets of significantly differentially expressed transcripts distinguishing TB from LTBI and OD were identified in the training cohort. A 27 transcript signature distinguished TB from LTBI and a 44 transcript signature distinguished TB from OD. To evaluate our signatures, we used a novel computational method to calculate a disease risk score (DRS) for each patient. The classification based on this score was first evaluated in the test cohort, and then validated in an independent publically available dataset (GSE19491). In our test cohort, the DRS classified TB from LTBI (sensitivity 95%, 95% CI [87-100]; specificity 90%, 95% CI [80-97]) and TB from OD (sensitivity 93%, 95% CI [83-100]; specificity 88%, 95% CI [74-97]). In the independent validation cohort, TB patients were distinguished both from LTBI individuals (sensitivity 95%, 95% CI [85-100]; specificity 94%, 95% CI [84-100]) and OD patients (sensitivity 100%, 95% CI [100-100]; specificity 96%, 95% CI [93-100]). Limitations of our study include the use of only culture confirmed TB patients, and the potential that TB may have been misdiagnosed in a small proportion of OD patients despite the extensive clinical investigation used to assign each patient to their diagnostic group.
In our study, blood transcriptional signatures distinguished TB from other conditions prevalent in HIV-infected and -uninfected African adults. Our DRS, based on these signatures, could be developed as a test for TB suitable for use in HIV endemic countries. Further evaluation of the performance of the signatures and DRS in prospective populations of patients with symptoms consistent with TB will be needed to define their clinical value under operational conditions. Please see later in the article for the Editors' Summary.
PLoS Medicine 10/2013; 10(10):e1001538. · 15.25 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background. Tuberculosis (TB) is transmitted by patients with pulmonary disease. Matrix metalloproteinases (MMPs) drive lung destruction in TB but the resulting matrix degradation products (MDPs) have not been studied. We investigate the hypothesis that MMP activity generates matrix turnover products as correlates of lung pathology.Methods. Induced sputum and plasma were collected prospectively from HIV positive and negative patients with pulmonary TB and controls. Concentrations of MDPs and MMPs were analyzed by ELISA and Luminex array in two patient cohorts.Results. Procollagen III N-terminal propeptide (PIIINP) was 3.8-fold higher in induced sputum of HIV-uninfected TB patients compared to controls and desmosine, released during elastin degradation, was 2.4-fold higher. PIIINP was elevated in plasma of TB patients. Plasma PIIINP correlated with induced sputum MMP-1 concentrations and radiological scores, demonstrating that circulating MDPs reflect lung destruction. In a second patient cohort of mixed HIV seroprevalence, plasma PIIINP concentration was increased 3.0-fold above controls (p<0.001). Plasma matrix metalloproteinase-8 concentrations were also higher in TB patients (p=0.001). Receiver operating characteristic analysis utilising these two variables demonstrated an area under the curve of 0.832 (p <0.001).Conclusions. In pulmonary TB, MMP-driven immunopathology generates matrix degradation products.
The Journal of Infectious Diseases 08/2013; · 5.85 Impact Factor
[show abstract][hide abstract] ABSTRACT: HIV-1 patients co-infected with some pathogens are at risk of developing the immune reconstitution inflammatory syndrome (IRIS) when initiating antiretroviral therapy (ART). IRIS is characterized by inflammation leading to the clinical worsening of a treated infection or the unmasking of a previously undiagnosed condition or infection. It is commonly associated with tuberculosis (TB), 8-43% of the HIV-TB co-infected patients prescribed with antitubercular treatment and ART develop TB-IRIS. Although IRIS has been recognized for over 20 years, relatively little was known until recently about its pathogenesis. Despite these advances in understanding IRIS, there remains no immune biomarker for diagnostic or prognostic purposes. Here, we review the risk factors associated with TB-IRIS, the challenges in studying this syndrome, and how T lymphocytes, dysregulated cytokine responses, and innate immunity may contribute to the development of TB-IRIS.
European Journal of Immunology 08/2013; 43(8):1995-2002. · 4.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: Tuberculosis is a devastating disease that accounts for a high proportion of infectious disease morbidity and mortality worldwide. HIV-1 co-infection exacerbates tuberculosis. Enhanced understanding of the host-pathogen relationship in HIV-1 and M. tuberculosis co-infection is required. While reductionist approaches have yielded many valuable insights into disease pathogenesis, systems approaches are required that develop data-driven models able to predict emergent properties of this complex co-infection system in order to develop novel therapeutic approaches and to improve diagnostics. Here we provide a pathogenesis-focused overview of HIV-TB coinfection followed by an introduction to systems approaches and concrete examples of how such approaches are useful. This article is protected by copyright. All rights reserved.
[show abstract][hide abstract] ABSTRACT: Distinct phylogenetic lineages of Mycobacterium tuberculosis (MTB) cause disease in patients of particular genetic ancestry, and elicit different patterns of cytokine and chemokine secretion when cultured with human macrophages in vitro. Circulating and antigen-stimulated concentrations of these inflammatory mediators might therefore be expected to vary significantly between tuberculosis patients of different ethnic origin. Studies to characterise such variation, and to determine whether it relates to host or bacillary factors, have not been conducted. We therefore compared circulating and antigen-stimulated concentrations of 43 inflammatory mediators and 14 haematological parameters (inflammatory profile) in 45 pulmonary tuberculosis patients of African ancestry vs. 83 patients of Eurasian ancestry in London, UK, and investigated the influence of bacillary and host genotype on these profiles. Despite having similar demographic and clinical characteristics, patients of differing ancestry exhibited distinct inflammatory profiles at presentation: those of African ancestry had lower neutrophil counts, lower serum concentrations of CCL2, CCL11 and vitamin D binding protein (DBP) but higher serum CCL5 concentrations and higher antigen-stimulated IL-1 receptor antagonist and IL-12 secretion. These differences associated with ethnic variation in host DBP genotype, but not with ethnic variation in MTB strain. Ethnic differences in inflammatory profile became more marked following initiation of antimicrobial therapy, and immunological correlates of speed of elimination of MTB from the sputum differed between patients of African vs. Eurasian ancestry. Our study demonstrates a hitherto unappreciated degree of ethnic heterogeneity in inflammatory profile in tuberculosis patients that associates primarily with ethnic variation in host, rather than bacillary, genotype. Candidate immunodiagnostics and immunological biomarkers of response to antimicrobial therapy should be derived and validated in tuberculosis patients of different ethnic origin.
[show abstract][hide abstract] ABSTRACT: There are 9 million cases of active tuberculosis reported annually; however, an estimated one-third of the world's population is infected with Mycobacterium tuberculosis and remains asymptomatic. Of these latent individuals, only 5-10% will develop active tuberculosis disease in their lifetime. CD4(+) T cells, as well as the cytokines IL-12, IFN-γ, and TNF, are critical in the control of Mycobacterium tuberculosis infection, but the host factors that determine why some individuals are protected from infection while others go on to develop disease are unclear. Genetic factors of the host and of the pathogen itself may be associated with an increased risk of patients developing active tuberculosis. This review aims to summarize what we know about the immune response in tuberculosis, in human disease, and in a range of experimental models, all of which are essential to advancing our mechanistic knowledge base of the host-pathogen interactions that influence disease outcome.
Annual Review of Immunology 03/2013; 31:475-527. · 36.56 Impact Factor
[show abstract][hide abstract] ABSTRACT: Isoniazid preventive therapy (IPT) is recommended in patients on antiretroviral treatment. Isoniazid (INH) inhibits CYP3A4, which metabolises nevirapine (NVP). Administration of INH may cause higher NVP concentrations and toxicity. We studied the effect of INH on NVP concentrations in 21 patients randomised to either placebo (n = 13) or INH (n = 8) in an ongoing trial of IPT in patients on ART. INH was associated with a 24% increase in median NVP area under the plasma concentration-time curve for the 12 h dosing interval, which was not statistically significant (P = 0.66).
The international journal of tuberculosis and lung disease: the official journal of the International Union against Tuberculosis and Lung Disease 03/2013; 17(3):333-5. · 2.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: Despite abundant evidence that neutrophils arrive early at sites of mycobacterial disease and phagocytose organisms, techniques to assay phagocytosis or killing of mycobacteria by these cells are lacking. Existing assays for measuring the antimycobacterial activity of human leukocytes require cell lysis which introduces new bioactive substances and may be incomplete. They are also time-consuming and carry multiple risks of inaccuracy due to serial dilution and organism clumping. Flow cytometric techniques for measuring phagocytosis of mycobacteria by human cells have failed to adequately address the effects of organism clumping, quenching agents and culture conditions on readouts. Here we present a novel in-tube bioluminescence-based assay of antimycobacterial activity by human neutrophils. The assay yields intuitive results, with improving restriction of mycobacterial bioluminescence as the ratio of cells to organisms increases. We show that lysis of human cells is not required to measure luminescence accurately. We also present a phagocytosis assay in which we have minimised the impact of mycobacterial clumping, investigated the effect of various opsonisation techniques and established the correct usage of trypan blue to identify surface-bound organisms without counting dead cells. The same multiplicity of infection and serum conditions are optimal to demonstrate both internalisation and restriction of mycobacterial growth.
[show abstract][hide abstract] ABSTRACT: OBJECTIVES:: To study whether in vivo recruitment of dendritic cells (DCs) in response to antigen administration in the skin is altered during HIV-1 infection. DESIGN:: Skin punch biopsies were collected from HIV-1+ as well as seronegative individuals at 48 hours post intradermal injection of inactivated antigens of mumps virus, Candida albicans or purified protein derivate (PPD) from Mycobacterium tuberculosis. METHODS:: Cryosections were analyzed by in situ staining and computerized imaging. RESULTS:: Control skin biopsies showed that there was no difference in the number of skin-resident DCs between seronegative and HIV-1+ individuals. Antigen injection resulted in substantial infiltration of DCs compared to the frequencies found in donor-matched control skin. In HIV-1+ individuals, CD123+/CD303+ plasmacytoid DCs and CD11c+ myeloid DCs, including the CD141+ cross-presenting subset, were recruited at lower levels compared to healthy controls in response to PPD and mumps but not C. albicans. The level of DC recruitment correlated with the frequencies of T cells infiltrating the respective antigen sites. Ki67+ cycling T cells at the injection sites were much more frequent in response to each of the antigens in the HIV-1+ individuals, including those with AIDS, compared to healthy controls. CONCLUSIONS:: Multiple DC subsets infiltrate the dermis in response to antigen exposure. There was no obvious depletion or deficiency in mobilization of DCs in response to antigen skin tests during chronic HIV-1 infection. Instead, the levels of antigen-specific memory T cells that accumulate at the antigen site may determine the level of DC infiltration.
AIDS (London, England) 01/2013; · 4.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background. The IL-10 family comprises cytokines structurally related to IL-10 sharing signalling receptors that have conserved signalling cascades. The immunopathogenesis of HIV-TB-associated IRIS remains incompletely understood. We hypothesized that a deficiency of IL-10 and its homologs may contribute to the immunopathology in HIV-TB associated IRIS.Methods. A case-control analysis of TB-IRIS patients at clinical presentation compared to similar control HIV-TB patients who did not develop TB-IRIS. PBMC were cultured in the presence or absence of heat killed M. tuberculosis (MTB) for 6 and 24 hours. mRNA was analysed by qRT-PCR. Cytokine concentrations in serum were also determined.Results. IL-10 and IL-22 transcript levels were significantly increased by MTB stimulation in TB-IRIS cultures compared to non-IRIS patients at 24 hours. Analysis of corresponding serum samples showed significantly higher concentrations of IL-10 and IL-22 in TB-IRIS compared to non-IRIS patients.Conclusions. IL-10 and IL-22 are differentially induced in PBMC of TB-IRIS patients after in vitro stimulation and higher concentrations of their corresponding proteins were detected in serum (in vivo). The higher levels of IL-10 observed in this study may represent a compensatory anti-inflammatory response in TB-IRIS. The elevated levels of IL-22 suggest an association between this cytokine and immunopathology in this condition.
The Journal of Infectious Diseases 01/2013; · 5.85 Impact Factor
[show abstract][hide abstract] ABSTRACT: HIV-associated tuberculosis is a common coinfection in Sub-Saharan Africa, which causes high morbidity and mortality. A sub-set of HIV-associated tuberculosis patients require prolonged hospital admission, during which antiretroviral therapy initiation may be required. The aim of this study was to document the causes of clinical deterioration of hospitalised patients with HIV-associated tuberculosis starting antiretroviral therapy in order to inform healthcare practice in low- to middle-income countries.
Prospective, observational cohort study of adult inpatients with HIV-associated tuberculosis starting antiretroviral therapy in a dedicated tuberculosis hospital in Cape Town, South Africa. Causes of clinical deterioration and outcome were recorded in the first 12 weeks of antiretroviral therapy. Patients with rifampicin-resistant tuberculosis were excluded.
Between May 2009 and November 2010, 112 patients (60% female), with a median age of 32 years were enrolled. At baseline the median CD4 count was 55 cells/mm(3) (IQR 31-106) and HIV viral load 5.6 log copies/mL. All patients had significant comorbidity: 82% were bed-bound, 65% had disseminated tuberculosis and 27% had central nervous system tuberculosis. Seventy six patients (68%) developed 144 clinical events after starting antiretroviral therapy. TB-IRIS, hospital-acquired infections and significant drug toxicities occurred in 42%, 20.5% and 15% of patients respectively. A new opportunistic disease occurred in 15% of patients and a thromboembolic event in 8%. Mortality during the 12 week period was 10.6%.
High rates of TB-IRIS, hospital-acquired infections and drug toxicities complicate the course of patients with HIV-associated tuberculosis starting antiretroviral therapy in hospital. Despite the high morbidity, mortality was relatively low. Careful clinical management and adequate resources are needed in hospitalised HIV-TB patients in the 1(st) three months following ART initiation.
PLoS ONE 01/2013; 8(2):e54145. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background. The interleukin 10 (IL-10) family comprises cytokines structurally related to IL-10 that share signaling receptors that have conserved signaling cascades. The immunopathogenesis of immune reconstitution inflammatory syndrome (IRIS) in patients with human immunodeficiency virus (HIV) infection and tuberculosis remains incompletely understood. We hypothesized that a deficiency of IL-10 and its homologs may contribute to the immunopathology of IRIS in these patients. Methods. We performed a case-control analysis involving patients with HIV infection and tuberculosis who had IRIS at clinical presentation (tuberculosis-IRIS) and similar patients with HIV infection and tuberculosis who did not develop tuberculosis-IRIS (non-IRIS). Peripheral blood mononuclear cells (PBMCs) were cultured in the presence or absence of heat-killed Mycobacterium tuberculosis for 6 and 24 hours. Messenger RNA was analyzed by quantitative reverse transcription polymerase chain reaction analysis. Cytokine concentrations in serum were also determined. Results. Cultures of PBMCs stimulated with M. tuberculosis for 24 hours yielded higher IL-10 and interleukin 22 (IL-22) transcript levels for tuberculosis-IRIS patients, compared with non-IRIS patients. Analysis of corresponding serum samples showed significantly higher concentrations of IL-10 and IL-22 in tuberculosis-IRIS patients, compared with non-IRIS patients. Conclusions. IL-10 and IL-22 were differentially induced in PBMCs from tuberculosis-IRIS patients after in vitro stimulation, and higher concentrations of their corresponding proteins were detected in serum (in vivo). The higher levels of IL-10 observed in this study may represent a compensatory antiinflammatory response during tuberculosis-IRIS. The elevated levels of IL-22 suggest an association between this cytokine and immunopathology during tuberculosis-IRIS.
The Journal of Infectious Diseases 01/2013; 207(7):1148-1156. · 5.85 Impact Factor
[show abstract][hide abstract] ABSTRACT: Studies on Mycobacterium tuberculosis (MTB) antigens are of interest in order to improve vaccine efficacy and to define biomarkers for diagnosis and treatment monitoring. The methodologies used for these investigations differ greatly between laboratories and discordant results are common. The IFN-gamma response to two well characterized MTB antigens ESAT-6 and CFP-10, in the form of recombinant proteins and synthetic peptides, was evaluated in HIV-1 uninfected persons in both long-term (7 day) and 24 hour, commercially available QuantiFERON TB Gold in Tube (QFT-GIT), whole blood assays. Our findings showed differences in the IFN-gamma response between 24 hour and 7 day cultures, with recombinant proteins inducing a significantly higher response than the peptide pools in 7 day whole blood assays. The activity of peptides and recombinant proteins did not differ in 24 hour whole blood or peripheral blood mononuclear cell (PBMC) based assays, nor in the ELISpot assay. Further analysis by SELDI-TOF mass spectrometry showed that the peptides are degraded over the course of 7 days of incubation in whole blood whilst the recombinant proteins remain intact. This study therefore demonstrates that screening antigenic candidates as synthetic peptides in long-term whole blood assays may underestimate immunogenicity.
PLoS ONE 01/2013; 8(8):e71351. · 3.73 Impact Factor