Multi-center evaluation of a user-friendly lateral flow assay to determine IP-10 and CCL4 levels in blood of TB and non-TB cases in Africa

OBJECTIVE

Multi-center evaluation of a user-friendly lateral flow test for detection of IP-10 and CCL4 levels in Mycobacterium tuberculosis (Mtb) antigen-stimulated whole blood samples from tuberculosis (TB) suspects.

DESIGN AND METHODS

A quantitative lateral flow (LF)-based assay platform was applied to detect chemokines IP-10 and CCL4. Chemokine quantitation was achieved using interference-free, fluorescent up-converting phosphor (UCP) labels. The new assays allowed worldwide shipping and storage without requiring a cold chain and were tested at seven institutes (including Ethiopia, Malawi, The Gambia, South Africa, Uganda and Namibia) employing portable lightweight readers for detection of the UCP label. At each site, clinical samples, confirmed TB and non-TB (i.e. other respiratory diseases (ORD)) cases, were collected and analyzed simultaneously with quality control (QC) human IP-10 or CCL4 standards.

RESULTS

Performance of the UCP-LF assay in Africa using QC standards indicated high robustness allowing quantitative detection between 100 and 100,000pg/mL. The optimized assays allowed successful determination of chemokine levels using 1μL whole blood sample from the locally recruited subjects with TB or ORD.

CONCLUSION

This African multi-center trial further demonstrated the applicability of the low-tech and robust UCP-LF platform as a convenient quantitative assay for chemokine detection in whole blood. Ambient shipping and storage of all assay reagents and the availability of lightweight standalone readers were acknowledged as essential requirement for test implementation in particular in remote and resource-limited settings.

Analytic laboratory performance of a point of care urine culture kit for diagnosis and antibiotic susceptibility testing

Currently available point-of-care (POC) diagnostic tests for managing urinary tract infections (UTIs) in general practice are limited by poor performance characteristics, and laboratory culture generally provides results only after a few days. This laboratory evaluation compared the analytic performance of the POC UK Flexicult(™) (Statens Serum Institut) (SSI) urinary kit for quantification, identification and antibiotic susceptibility testing and routine UK National Health Service (NHS) urine processing to an advanced urine culture method. Two hundred urine samples routinely submitted to the Public Health Wales Microbiology Laboratory were divided and: (1) analysed by routine NHS microbiological tests as per local laboratory standard operating procedures, (2) inoculated onto the UK Flexicult(™) SSI urinary kit and (3) spiral plated onto Colorex Orientation UTI medium (E&O Laboratories Ltd). The results were evaluated between the NHS and Flexicult(™ )methods, and discordant results were compared to the spiral plating method. The UK Flexicult(™) SSI urinary kit was compared to routine NHS culture for identification of a pure or predominant uropathogen at ≥ 10(5) cfu/mL, with a positive discordancy rate of 13.5% and a negative discordancy rate of 3%. The sensitivity and specificity were 86.7% [95% confidence interval (CI) 73.8-93.7] and 82.6% (95% CI 75.8-87.7), respectively. The UK Flexicult(™) SSI urinary kit was comparable to routine NHS urine processing in identifying microbiologically positive UTIs in this laboratory evaluation. However, the number of false-positive samples could lead to over-prescribing of antibiotics in clinical practice. The Flexicult(™) SSI kit could be useful as a POC test for UTIs in primary care but further pragmatic evaluations are necessary.

Impaired Phenotype and Function of T Follicular Helper Cells in HIV-1-Infected Children Receiving ART

T follicular helper (Tfh) cells are important components in development of specific humoral immune responses; whether the number and biology of Tfh cells is impaired in HIV-1-infected children is not yet studied.The frequency, phenotype, and function of Tfh cells and B cells were determined in blood of HIV-1-infected children receiving antiretroviral therapy (ART) and age-matched controls. Flow cytometry was used to characterize the frequency of Tfh cells and B cell subsets. Cytokine expression was measured after in vitro activation of Tfh cells.A reduced frequency of memory Tfh cells (P < 0.001) was identified in HIV-1-infected children and, on these cells, a reduced expression of programmed death-1 (PD-1) and inducible T cell costimulator (ICOS) (P < 0.001 and P < 0.01). Upon activation, the capacity of Tfh cells to express IL-4, an important cytokine for B cell function, was impaired in HIV-1-infected children.B cell subpopulations in HIV-1-infected children displayed significant differences from the control group: the frequency of resting memory (RM) B cells was reduced (P < 0.01) whereas the frequency of exhausted memory B cells increased (P < 0.001). Interestingly, the decline of RM cells correlated with the reduction of memory Tfh cells (P = 0.02).Our study shows that function and phenotype of Tfh cells, pivotal cells for establishment of adaptive B cell responses, are impaired during HIV-1 infection in children. A consistent reduction of memory Tfh cells is associated with declined frequencies of RM B cells, creating a novel link between dysfunctional features of these cell types, major players in establishment of humoral immunity.

Documentation and treatment outcomes of smear-negative and extra-pulmonary tuberculosis in Ethiopia

BACKGROUND

Smear-negative and extra-pulmonary tuberculosis (TB) comprise two thirds of TB cases reported in Ethiopia. Neither treatment outcomes nor underlying associated factors are routinely reported for these cases.

OBJECTIVE

To assess treatment outcomes and associated risk factors of smear-negative and extra-pulmonary TB in comparison with smear-positive cases.

DESIGN

Record review of all TB cases registered in 14 randomly selected public and private health facilities in Addis Ababa, Ethiopia, over a 1-year period.

RESULTS

Percentages of smear-negative and extra-pulmonary TB were independent of human immunodeficiency virus (HIV) status, and were not evenly distributed among health facilities. Extra-pulmonary TB was overrepresented in the private sector, and smear-negative TB was more frequent in health clinics than in hospitals. Outcomes reported by clinics were more favourable than those of the hospitals; no differences were observed when comparing public and private health facilities. Only 54% of the TB registers were complete; missing information correlated with unfavourable outcomes. Younger age, but not sex or HIV status, was associated with favourable outcomes.

CONCLUSION

The uneven distribution of smear-negative and extra-pulmonary TB among different health facilities requires further study and may provide important insight into diagnosis and care of these patients. Incomplete TB register information may be an underappreciated factor contributing to unfavourable outcomes.

Combination of gene expression patterns in whole blood discriminate between tuberculosis infection states

Background

Genetic factors are involved in susceptibility or protection to tuberculosis (TB). Apart from gene polymorphisms and mutations, changes in levels of gene expression, induced by non-genetic factors, may also determine whether individuals progress to active TB.

Methods

We analysed the expression level of 45 genes in a total of 47 individuals (23 healthy household contacts and 24 new smear-positive pulmonary TB patients) in Addis Ababa using a dual colour multiplex ligation-dependent probe amplification (dcRT-MLPA) technique to assess gene expression profiles that may be used to distinguish TB cases and their contacts and also latently infected (LTBI) and uninfected household contacts.

Results

The gene expression level of BLR1, Bcl2, IL4d2, IL7R, FCGR1A, MARCO, MMP9, CCL19, and LTF had significant discriminatory power between sputum smear-positive TB cases and household contacts, with AUCs of 0.84, 0.81, 0.79, 0.79, 0.78, 0.76, 0.75, 0.75 and 0.68 respectively. The combination of Bcl2, BLR1, FCGR1A, IL4d2 and MARCO identified 91.66% of active TB cases and 95.65% of household contacts without active TB. The expression of CCL19, TGFB1, and Foxp3 showed significant difference between LTBI and uninfected contacts, with AUCs of 0.85, 0.82, and 0.75, respectively, whereas the combination of BPI, CCL19, FoxP3, FPR1 and TGFB1 identified 90.9% of QFT^- and 91.6% of QFT⁺ household contacts.

Conclusions

Expression of single and especially combinations of host genes can accurately differentiate between active TB cases and healthy individuals as well as between LTBI and uninfected contacts.

The effect of maternal helminth infection on maternal and neonatal immune function and immunity to tuberculosis

BACKGROUND

M. tuberculosis and helminth infection each affects one third of the world population. Helminth infections down regulate cell mediated immune responses and this may contribute to lower efficacy of BCG vaccination and higher prevalence of tuberculosis.

OBJECTIVE

To determine the effect of maternal helminth infection on maternal and neonatal immune function and immunity to TB.

METHODS

In this cross sectional study, eighty five pregnant women were screened for parasitic and latent TB infections using Kato-Katz and QFT-GIT tests, respectively. IFN-γ and IL-4 ELISpot on Cord blood Mononuclear Cells, and total IgE and TB specific IgG ELISA on cord blood plasma was performed to investigate the possible effect of maternal helminth and/or latent TB co-infection on maternal and neonatal immune function and immunity to TB.

RESULT

The prevalence of helminth infections in pregnant women was 27% (n = 23), with Schistosoma mansoni the most common helminth species observed (20% of women were infected). Among the total of 85 study participants 25.8% were QFT-GIT positive and 17% had an indeterminate result. The mean total IgE value of cord blood was significantly higher in helminth positive than negative women (0.76 vs 0.47, p = 0.042). Cross placental transfer of TB specific IgG was significantly higher in helminth positive (21.9 ± 7.9) than negative (12.3 ± 5.1), p = 0.002) Latent TB Infection positive participants. The IFN-γ response of CBMCs to ESAT-6/CFP-10 cocktail (50 vs 116, p = 0.018) and PPD (58 vs 123, p = 0.02) was significantly lower in helminth positive than negative participants. There was no significant difference in IL-4 response of CBMCs between helminth negative and positive participants.

CONCLUSIONS

Maternal helminth infection had a significant association with the IFN-γ response of CBMCs, total IgE and cross placental transfer of TB specific IgG. Therefore, further studies should be conducted to determine the effect of these factors on neonatal immune response to BCG vaccination.

Impact of HIV co-infection on plasma level of cytokines and chemokines of pulmonary tuberculosis patients

BACKGROUND

The immunologic environment during HIV/M. tuberculosis co-infection is characterized by cytokine and chemokine irregularities that have been shown to increase immune activation, viral replication, and T cell dysfunction.

METHODS

We analysed ex vivo plasma samples from 17 HIV negative and 16 HIV pulmonary tuberculosis co infected cases using Luminex assay to see impact of HIV co-infection on plasma level of cytokines and chemokines of pulmonary tuberculosis patients before and after anti Tuberculosis treatment.

RESULTS

The median plasma level of IFN-γ, IL-4, MCP-3, MIP-1β and IP-10 was significantly different (P < 0.05) before and after treatment in HIV negative TB patients but not in HIV positive TB patients. There was no significant difference between HIV positive and HIV negative TB patients (P > 0.05) in the plasma level of any of the cytokines or chemokines before treatment and anti TB treatment did not change the level of any of the measured cytokines in HIV positive tuberculosis patients. The ratio of IFN-γ/IL-10 and IFN-γ/IL-4 showed a significant increase after treatment in HIV negative TB cases but not in HIV positive TB cases which might indicate prolonged impairment of immune response to TB in HIV positive TB patients as compared to HIV negative tuberculosis patients.

CONCLUSIONS

HIV positive and HIV negative Tuberculosis patients display similar plasma cytokine and chemokine pattern. However, anti TB treatment significantly improves the Th1 cytokines and level of chemokines but does not restore the immune response in HIV positive individuals.

Helminth infection increases the probability of indeterminate QuantiFERON gold in tube results in pregnant women

BACKGROUND

Approximately one-third of the world population is infected with M. tuberculosis and helminths (Kariminia et al. (2009), Walson et al. (2010)). Pregnancy and Helminth infection are known to suppress the TH1 response (Kariminia et al. (2009), Elias et al. (2006)) on which the QuantiFERON Gold in Tube (QFT-GIT) assay, that measures the released IFN-γ upon in vitro stimulation with mycobacterial antigens, relies on (Thomas et al. (2010)).

OBJECTIVE

To determine whether QFT-GIT indeterminate result is significantly associated with helminth infection or not.

METHODS

In this cross-sectional study, eighty-five pregnant mothers were screened for parasitic and LTBI using Kato-Katz and QFT-GIT test-respectively,

RESULT

The prevalence of helminth infection in pregnant mothers was 23 (27%) of this 17 (20%) was due to Schistosoma mansoni. Among the total of 85 study participants 26.8% were QFT-GIT positive and 14 (17%) had indeterminate results. Three samples (21.4%) were randomly selected from the indeterminate QFT-GIT results and retested to check the reproducibility of the assay and remained indeterminate. QFT-GIT indeterminate result showed significant association with helminth infection.

CONCLUSION

Helminth infections were significantly associated with indeterminate QFT-GIT results in pregnant mothers. Therefore further study is important to evaluate the possible effect of helminth infection by excluding the effect of pregnancy, as pregnancy also downregulates cellular immunity.

Human immunodeficiency virus infection among new smear positive pulmonary tuberculosis patients in Addis Ababa, Ethiopia

BACKGROUND

It has been few years since the launching of provider-initiated HIV counselling and testing (PICT) for all tuberculosis (TB) suspected patients and patients presenting with signs and symptoms of TB. However, little is known about the prevalence of HIV in new smear positive confirmed TB cases in Addis Ababa.

OBJECTIVE

To determine the proportion of HIV among newly diagnosed smear positive TB cases, who were screened between February 2007 and July 2010 in Addis Ababa.

METHODS

A total of 418 pulmonary TB patients and 188 HIV positive non-TB cases were recruited from different health centres in Addis Ababa. All TB patients were tested for HIV.

RESULTS

Of the total 418 new smear positive TB patients tested for HIV, 97 (23.2%) were HIV positive. The occurrence of HIV among TB patients was significantly higher in females, 50/182 (27.7%) compared to males, 47/236 (19.7%) (P < 0.05). The mean CD4 lymphocyte count among HIV positive active TB cases was significantly lower (P < 0.05) (210 +/- 23.9 cells/microL) compared to the counts among non-TB HIV positive cases (407.01 +/- 31.3 cells/microL). The proportion of HIV was significantly higher in the age group 31-40 (46.3%) and > 41 (42.2%) year (p < 0.001) compared to younger, 18-20 (3.75%) and 21-30 (17.8%) years of age groups.

CONCLUSION

The occurrence of HIV in smear positive TB cases is high, with a higher proportion seen among females compared to males.

Differential gene expression of activating Fcγ receptor classifies active tuberculosis regardless of human immunodeficiency virus status or ethnicity

New diagnostics and vaccines for tuberculosis (TB) are urgently needed, but require an understanding of the requirements for protection from/susceptibility to TB. Previous studies have used unbiased approaches to determine gene signatures in single-site populations. The present study utilized a targeted approach, reverse transcriptase multiplex ligation-dependent probe amplification (RT-MLPA), to validate these genes in a multisite study. We analysed ex vivo whole blood RNA from a total of 523 participants across four sub-Saharan countries (Ethiopia, Malawi, South Africa, and The Gambia) with differences in TB and human immunodeficiency virus (HIV) status. We found a number of genes that were expressed at significantly lower levels in participants with active disease than in those with latent TB infection (LTBI), with restoration following successful TB treatment. The most consistent classifier of active disease was FCGR1A (high-affinity IgG Fc receptor 1 (CD64)), which was the only marker expressed at significantly higher levels in participants with active TB than in those with LTBI before treatment regardless of HIV status or genetic background. This is the first study to identify a biomarker for TB that is not affected by HIV status or geo-genetic differences. These data provide valuable clues for understanding TB pathogenesis, and also provide a proof-of-concept for the use of RT-MLPA in rapid and inexpensive validation of unbiased gene expression findings.

Abstract P4-11-03: Single nucleotide polymorphism testing for breast cancer risk assessment: patient trust and willingness to pay

Background: The field of breast cancer risk assessment is advancing rapidly with recent discoveries about risk conferring single nucleotide polymorphisms (SNPs). While these discoveries can promote personalized medicine, they are often brought to the market with direct to consumer (DTC) testing before data can support their widespread use and before reliable options for dealing with testing outcomes can be offered. In this context, and knowing that patients often misunderstand risk information, it is unclear how patients will respond to these options.

Methods: We surveyed high risk women's interest in SNP testing. Participants were recruited from the Cancer Genetics Network (CGN), a national network of cancer centers that maintains a database of individuals with a family history of cancer. Participants were asked to answer questions regarding their interest in SNP testing including: whether they trust it, how much they would be willing to pay for testing, how they prefer to be tested, and how they would proceed with information identifying them as below or above average risk.

Results: 189 women without a history of breast cancer or SNP testing completed the questionnaire. The average age of the participants was 49, ranging from 30 to 65. All participants had at least one relative with breast or ovarian cancer. 13% had previously tested positive for a BRCA mutation, and 33% had received BRCA testing. Most women (90%) did not know what SNP testing was prior to the survey. Once SNP testing was described, 68% of women were interested in DTC SNP testing; at the same time, only 38% of the participants reported that they trusted DTC SNP testing.

Plasma cytokines and chemokines differentiate between active disease and non-active tuberculosis infection

OBJECTIVES

To analyse cytokines and chemokines from unstimulated plasma samples for detection of active TB disease, latent TB, discriminating active TB cases from latently infected contacts and for monitoring anti TB treatment.

METHOD

We analysed ex vivo plasma samples from 33 TB patients (17 HIV negative and 16 HIV positive) and 30 healthy household contacts with Luminex.

RESULT

We found statistically significant differences (p < 0.05) in median plasma concentrations of EGF, fractalkine, IFN-γ, IL-4, MCP-3 and IP-10 between contacts and TB patients. Single cytokines or chemokines predict with an area under the Receiver Operating Characteristic (ROC) curve of 0.59 for VEGF to 0.98 for IP 10 while a combination of fractalkine, IFN-g, IL-4, IP-10 and TNF identified 96.87% of TB cases and 100% of household contacts. However, none of the cytokines were significantly different in QFT positive and QFT negative contacts (p > 0.05). HIV does not affect the median plasma level of any of the cytokines or chemokines and there was not significant difference between HIV positive and HIV negative TB patients (p > 0.05) in any of the cytokines or chemokines. The median plasma concentrations of IFN-γ, IL-4, MCP-3, MIP-1β and IP-10 were significantly different (p < 0.05) before treatment and after treatment.

CONCLUSION

Plasma cytokines and chemokines could be used as immunological markers for diagnosing active TB disease and for monitoring effective antituberculosis therapy.

Modern lineages of Mycobacterium tuberculosis in Addis Ababa, Ethiopia: implications for the tuberculosis control programe

BACKGROUND

The genotyping of Mycobacterium tuberculosis strains is important to have unique insights into the dissemination dynamics and evolutionary genetics of this pathogen and for TB control as it allows the detection of suspected outbreaks and the tracing of transmission chains.

OBJECTIVE

To characterize M. tuberculois isolates collected from newly diagnosed pulmonary TB patients in Addis Ababa

METHODS

One hundred and ninety two sputum samples were cultured on Löwenstein-Jensen (LJ) slants and isolates were heat killed for molecular genotyping. The isolates were characterized using spoligotyping and were compared with the International SpoIDB4 database.

RESULT

T genotype constitutes the most predominant in our study (95, 49.5%) followed by the CAS genotype (42, 21.9%). Other genotypes found were Haarlem (H) (24, 12.5%), the LAM (3, 1.5%), the Beijing genotype (1, 0.5%); four (2.1%) isolates were designated as Unknown.

CONCLUSION

All the isolates belong to the modern lineage and there is high clustering in the genotype of isolates which indicated the presence of recent TB transmission. Therefore, the Tuberculosis Control Programme needs to do more in advocating and strengthening the health system for early detection and treatment of active TB cases as delay in treatment is the key factor in disease transmission.

Human intestinal lamina propria CD1c+ dendritic cells display an activated phenotype at steady state and produce IL-23 in response to TLR7/8 stimulation

Intestinal dendritic cells (DCs) play key roles in mediating tolerance to commensal flora and inflammatory responses against mucosal pathogens. The mechanisms by which intestinal "conditioning" influences human DC responses to microbial stimuli remain poorly understood. Infections with viruses, such as HIV-1, that target mucosal tissue result in intestinal epithelial barrier breakdown and increased translocation of commensal bacteria into the lamina propria (LP). It is unclear whether innate LP DC responses to concurrent viral and bacterial stimuli influence mucosal HIV-1 pathogenesis. In this study, direct ex vivo phenotype and in vitro constitutive cytokine production of CD1c+ DCs in human intestinal LP were compared with those in peripheral blood (PB). To evaluate innate responses to viral and bacterial stimuli, intracellular cytokine production by LP and PB DCs following stimulation with ligands for TLRs 2, 4, 5, and 7/8 was evaluated. At steady state, LP CD1c+ DCs expressed higher levels of activation markers (CD40, CD83, CD86, HLA-DR, and CCR7) than did PB CD1c+ DCs, and higher frequencies of LP CD1c+ DCs constitutively produced IL-6 and -10 and TNF-alpha. LP DCs had blunted cytokine responses to TLR4 ligand and TLR5 ligand stimulation relative to PB DCs, yet similarly produced IL-10 in response to TLR2 ligand. Only synthetic TLR7/8 ligand, a mimic of viral ssRNA, induced IL-23 production by LP CD1c+ DCs, and this proinflammatory cytokine response was synergistically enhanced following combined TLR7/8 and TLR4 stimulation. These findings highlight a potential mechanism by which viruses like HIV-1 may subvert homeostatic mechanisms and induce inflammation in the intestinal mucosa.

Evidence for dendritic cell-dependent CD4(+) T helper-1 type responses to commensal bacteria in normal human intestinal lamina propria

Reactivity of lamina propria (LP) T cells to commensal bacteria has been demonstrated in animal models of inflammatory bowel disease (IBD) and in humans with IBD, but few studies have evaluated the function of such cells in normal individuals. LP mononuclear cells (LPMC) were disaggregated from healthy human intestinal tissue and cultured with heat-killed commensal and pathogenic bacteria. CD3(+)CD4(+) IFN-gamma-producing (Th1) cells reactive to commensal bacteria were demonstrated at frequencies ranging from 0.05 to 2.28% in LPMC. Bacteria-specific Th1 responses were inhibited by anti-HLA-DR antibodies and chloroquine exposure, were enriched in LP relative to peripheral blood, and expressed effector memory cell markers. Bacteria-specific CD4(+) T cell proliferation in vitro was dependent on the presence of LP dendritic cells (DCs), which produced pro-inflammatory cytokines upon bacterial exposure. These results suggest that bacteria-reactive DCs and CD4(+) T cells in normal LP have substantial pro-inflammatory potential that is revealed upon disaggregation in vitro.

Growth and development of children of mothers with leprosy and healthy controls

INTRODUCTION

In the pre-sulphone and early sulphone years children of leprous parents had been followed in a few prospective studies to observe the development of leprosy. No studies were made of the growth and development of these children.

METHODS

A prospective, open-ended, cohort study began in 1975 with follow-up of both mothers and their children until 2003. 156 pregnancies were studied consisting of 36 non-leprous (NL), 25 tuberculoid and borderline tuberculoid leprosy (TT&BT) (released-from-treatment), 18 with TT&BT (active), 42 borderline lepromatous leprosy (BL) and 35 lepromatous leprosy (LL).

RESULTS

Babies of mothers with leprosy had lower birth weight, smaller placentae, grew more slowly, had more infections and higher infant mortality than those of non-leprous mothers. The findings were most marked in babies of LL mothers. Growth in childhood was uneventful, infants of LL mothers catching up by age 3.6 years. Childhood infections were common in all groups but more serious for children of lepromatous mothers. The puberty skeletal growth spurt, and, for the girls, menarche was delayed for children studied compared with a new healthy control group, with catch-up by late teens. These findings were most marked in children of lepromatous, especially LL, mothers.

CONCLUSION

Impaired growth in utero and infancy is probably due to immunological factors but we could find no explanation for the delayed growth in adolescent children of LL mothers.