Therapeutic host-directed strategies to improve outcome in tuberculosis.

Bacille Calmette-Guérin (BCG) is the only licenced tuberculosis (TB) vaccine, but has limited efficacy against pulmonary TB disease development and modest protection against extrapulmonary TB. Preventative antibiotic treatment for Mycobacterium tuberculosis (Mtb) infections in high-prevalence settings is unfeasible due to unclear treatment durability, drug toxicity, logistical constraints related to directly observed treatment strategy (DOTS) and the lengthy treatment protocols. Together, these factors promote non-adherence, contributing to relapse and establishment of drug-resistant Mtb strains. Although antibiotic treatment of drug-susceptible Mtb is generally effective, drug-resistant TB has a treatment efficacy below 50% and can, in a proportion, develop into progressive, untreatable disease. Other immune compromising co-infections and/or co-morbidities require more complex prevention/treatment approaches, posing huge financial burdens to national health services. Novel TB treatment strategies, such as host-directed therapeutics, are required to complement pathogen-targeted approaches. Pre-clinical studies have highlighted promising candidates that enhance endogenous pathways and/or limit destructive host responses. This review discusses promising pre-clinical candidates and forerunning compounds at advanced stages of clinical investigation in TB host-directed therapeutic (HDT) efficacy trials. Such approaches are rationalized to improve outcome in TB and shorten treatment strategies.

The impact of health programmes to prevent vertical transmission of HIV. Advances, emerging health challenges and research priorities for children exposed to or living with HIV: Perspectives from South Africa.

Over the past three decades, tremendous global progress in preventing and treating paediatric HIV infection has been achieved. This paper highlights the emerging health challenges of HIV-exposed uninfected (HEU) children and the ageing population of children living with HIV (CLHIV), summarises programmatic opportunities for care, and highlights currently conducted research and remaining research priorities in high HIV-prevalence settings such as South Africa. Emerging health challenges amongst HEU children and CLHIV include preterm delivery, suboptimal growth, neurodevelopmental delay, mental health challenges, infectious disease morbidity and mortality, and acute and chronic respiratory illnesses including tuberculosis, pneumonia, bronchiectasis and lymphocytic interstitial pneumonitis. CLHIV and HEU children require three different categories of care: (i) optimal routine child health services applicable to all children; (ii) routine care currently provided to all HEU children and CLHIV, such as HIV testing or viral load monitoring, respectively, and (iii) additional care for CLHIV and HEU children who may have growth, neurodevelopmental, behavioural, cognitive or other deficits such as chronic lung disease, and require varying degrees of specialised care. However, the translation thereof into practice has been hampered by various systemic challenges, including shortages of trained healthcare staff, suboptimal use of the patient-held child's Road to Health book for screening and referral purposes, inadequate numbers and distribution of therapeutic staff, and shortages of assistive/diagnostic devices, where required. Additionally, in low-middle-income high HIV-prevalence settings, there is a lack of evidence-based solutions/models of care to optimise health amongst HEU and CLHIV. Current research priorities include understanding the mechanisms of preterm birth in women living with HIV to optimise preventive interventions; establishing pregnancy pharmacovigilance systems to understand the short-, medium- and long-term impact of in utero ART and HIV exposure; understanding the role of preconception maternal ART on HEU child infectious morbidity and long-term growth and neurodevelopmental trajectories in HEU children and CLHIV, understanding mental health outcomes and support required in HEU children and CLHIV through childhood and adolescence; monitoring HEU child morbidity and mortality compared with HIV-unexposed children; monitoring outcomes of CLHIV who initiated ART very early in life, sometimes with suboptimal ART regimens owing to medication formulation and registration issues; and testing sustainable models of care for HEU children and CLHIV including later reproductive care and support.

Strategies for screening cord blood for a public cord blood bank in high HIV prevalence regions.

The probability of a Black African finding a matched unrelated donor for a hematopoietic stem cell transplant is minimal due to the high degree of genetic diversity amongst individuals of African origin. This problem could be resolved in part by the establishment of a public cord blood (CB) stem cell bank. The high prevalence of human immunodeficiency virus (HIV) amongst women attending antenatal clinics in sub-Saharan Africa together with the risk of mother-to-child transmission increases the risk of transplant transmissible infection. In addition to screening the mother in a period inclusive of 7 days prior to the following delivery, we propose that all CB units considered for storage undergo rigorous and reliable screening for HIV. The Ultrio-plus® assay is a highly specific and sensitive test for detecting HIV, hepatitis-B and hepatitis-C viruses in peripheral blood. We validated the Ultrio-plus® assay for analytical sensitivity in detecting HIV in CB at the level of detection of the assay. Until more comprehensive and sensitive methods are developed, the sensitivity and reliability of the Ultrio-plus® assay suggest that it could be used for the routine screening of CB units in conjunction with currently recommended maternal screening to reduce the risk of transplant transmissible infection.

Decreased neutrophil-associated miRNA and increased B-cell associated miRNA expression during tuberculosis.

MicroRNAs are short non-coding RNAs that regulate gene expression by binding to, and suppressing the expression of genes. Research show that microRNAs have potential to be used as biomarkers for diagnosis, treatment response and can be used for therapeutic interventions. Furthermore, microRNA expression has effects on immune cell functions, which may lead to disease. Considering the important protective role of neutrophils and B-cells during M.tb infection, we evaluated the expression of microRNAs, known to alter function of these cells, in the context of human TB. We utilised real-time PCR to evaluate the levels of microRNA transcripts in the peripheral blood of TB cases and healthy controls. We found that neutrophil-associated miR-197-3p, miR-99b-5p and miR-191-5p transcript levels were significantly lower in TB cases. Additionally, B-cell-associated miR-320a, miR-204-5p, miR331-3p and other transcript levels were higher in TB cases. The miRNAs differentially expressed in neutrophils are predominantly implicated in signalling pathways leading to cytokine productions. Here, the decreased expression in TB cases may imply a lack of suppression on signalling pathways, which may lead to increased production of pro-inflammatory cytokines such as interferon-gamma. Furthermore, the miRNAs differentially expressed in B-cells are mostly involved in the induction/suppression of apoptosis. Further functional studies are however required to elucidate the significance and functional effects of changes in the expression of these microRNAs.

Risk factors for pertussis among hospitalized children in a high HIV prevalence setting, South Africa.

BACKGROUND: In low- and middle-income countries, including South Africa, the epidemiology of pertussis in relation to immunization, nutritional, and HIV status is poorly described. This article reports on risk factors in South African children hospitalized with pertussis. METHODS: A prospective, hospital-based, sentinel surveillance programme for pertussis was conducted in Gauteng Province, South Africa. Hospitalized children (≤10 years) meeting the surveillance criteria for clinically suspected pertussis were screened and enrolled. Nasopharyngeal specimens were collected for real-time multiplex PCR and culture of Bordetella species. RESULTS: Bordetella pertussis was detected in 6.2% (61/992) of children. Pertussis was significantly more prevalent in infants younger than 3 months (9.8%; 38/392) and in young children between the ages of 5 and 9 years (12%; 4/34) (p=0.0013). Of the 61 confirmed pertussis cases, 17 were too young for vaccination. Of the remaining 44 infants, vaccination DTP1 was administered in 73% (32/44) of pertussis-confirmed patients who were eligible, DTP2 in 50% (16/32), DTP3 in 54% (14/26), and DTP4 in 56% (5/9) of vaccine-eligible cases at 18 months of age. B. pertussis infection was less likely in children immunized at least once (5%, 32/692) than in unvaccinated children (10%, 24/230) (p=0.0001). HIV exposure and infection status were determined in 978 (99%) patients: 69% (678/978) were HIV-unexposed and uninfected and 31% (300/978) were HIV-exposed. Of these HIV-exposed patients, 218 (22%) were proven HIV-exposed and uninfected and 82 patients were HIV-infected (8.4%, 82/978). HIV prevalence was similar in pertussis-positive (6%, 5/82) and pertussis-negative (6%, 55/896) children (p=0.90). B. pertussis infection was unrelated to poor nutritional status. CONCLUSIONS: In South Africa, B. pertussis poses a greater risk to infants who are too young for the first vaccine dose, those who are not vaccinated in a timely manner, and those who do not receive all three primary doses. HIV infection and HIV exposure were not associated with pertussis infection.

Acute helminth infection enhances early macrophage mediated control of mycobacterial infection.

Co-infection with mycobacteria and helminths is widespread in developing countries, but how this alters host immunological control of each pathogen is not comprehensively understood. In this study, we demonstrate that acute Nippostrongylus brasiliensis (Nb) murine infection reduce early pulmonary mycobacterial colonization. This Nb-associated reduction in pulmonary Mycobacterium tuberculosis colony-forming units was associated with early and increased activation of pulmonary CD4 T cells and increased T helper type 1 (Th1) and Th2 cytokine secretion. An accelerated and transient augmentation of neutrophils and alveolar macrophages (AMs) was also observed in co-infected animals. AMs displayed markers of both classical and alternative activation. Intranasal transfer of pulmonary macrophages obtained from donor mice 5 days after Nb infection significantly reduced pulmonary Mycobacterium bovis Bacille Calmette-Guérin clearance in recipient mice. These data demonstrate that early stage Nb infection elicits a macrophage response, which is protective during the early stages of subsequent mycobacterial infection.

Functional analysis of the 5' regulatory region of the 5-aminolevulinate synthase (ALAS1) gene in response to estrogen.

Genetic defects in the heme synthesis enzymes lead to a group of heterogeneous disorders termed the porphyrias. Numerous factors influence the clinical expression of porphyrias, primarily by altering the rate of heme synthesis. To date, no genotype-phenotype correlation has been made to explain the variable penetrance observed in variegate porphyria (VP) and other acute hepatic porphyrias. As first and rate determining gene in the heme pathway, 5-aminolevulinate synthase-1 (ALAS1), appears to be an ideal candidate modifier. Previous studies established critical mechanisms for ALAS1 regulation and a direct transcriptional response to drugs by defined drug-responsive enhancer sequences (ADRES). To identify possible functional variants within the 5' region of ALAS1, selected regulatory regions, including the ADRES elements, were screened by DNA sequencing analysis in 26 VP patients heterozygous for the causative R59W mutation in the protoporphyrinogen oxidase (PPOX) gene. Two novel variants, -853C>T and -1253T>A were identified. In silico analyses indicated that the -853C>T transition is located immediately 5' to a half-palindromic putative estrogen receptor binding site. Co-transfection experiments with an estrogen receptor-alpha (ERalpha) expression vector in HepG2 cells, suggest that this region mediates an increased transcriptional response in the presence of estrogen (E2) and ERalpha. The wild-type -853C/-1253T allele induced a 47% increase in transcription, while the -853T/-1253A double mutant allele showed a 35% increase in transcription compared to expression in the absence of E2. The highest induction was observed for the mutant -853T/1253T allele that generated an increase of 66%. We conclude that the -853T variant functions as an enhancer in the presence of estrogen and speculates that the -1253A variant reduces transcription activity.

Short-term reproducibility of a commercial interferon gamma release assay.

Interferon gamma release assays (IGRAs) have been shown to be sensitive and highly specific for the detection of immune memory against Mycobacterium tuberculosis. Little is known about the reproducibility and within-person variability of these assays. Various aspects of short-term reproducibility of a commercial IGRA, the QuantiFERON-TB Gold In-Tube (QFT-IT) assay, were assessed. The QFT-IT assay was performed twice within 3 days in 27 health care workers in Cape Town, South Africa. Two sets of tests were performed by different operators on day 1, and one set was performed on day 3. Aspects such as interoperator, intraoperator, day-to-day variability, and test-retest variability as well as different the storage methods of plasma were investigated. Seventeen of 27 (63%) of participants had at least one positive QFT-IT text; six had discordant results. The agreement of all aspects studied was high, with kappa values between 0.82 and 1.00 for dichotomous measures, and interclass correlations (ICC) of 0.809 to 0.965 were observed for continuous gamma interferon (IFN-gamma) measures. The variability of the magnitude of response was highest comparing measures obtained from individuals on different days (ICC of 0.809). The magnitude of the IFN-gamma responses between assays performed for individual participants was variable, with ranges from 0.03 to 11 IU/ml, resulting is discordant results for five participants. The results indicate that the QFT-IT assay is a robust and highly reproducible assay. Considerable intraindividual variability occurs in the magnitude of IFN-gamma responses, which may influence the interpretation of serial measures.

Escalation in the relative prevalence of ciprofloxacin-resistant gonorrhoea among men with urethral discharge in two South African cities: association with HIV seropositivity.

OBJECTIVES: The objectives of this study were to assess the prevalence of ciprofloxacin-resistant gonorrhoea in two South African cities and to investigate the association between the isolation of ciprofloxacin-resistant Neisseria gonorrhoeae and the HIV serostatus of patients. METHODS: Gonococci were cultured from endourethral swabs taken from consecutive men with urethritis attending clinics in Johannesburg and Cape Town. Minimum inhibitory concentrations (MIC) for ciprofloxacin and ceftriaxone were determined with E-tests. Isolates with a ciprofloxacin MIC of 1 mg/l or greater were defined as resistant and isolates with a ceftriaxone MIC of 0.25 mg/l or less were defined as susceptible. Rapid tests were used to screen and confirm the presence of HIV antibodies. Survey data from 2004 were used as a baseline to assess trends in gonococcal resistance to ciprofloxacin. RESULTS: In 2004, the prevalence of ciprofloxacin resistance was 7% in Cape Town and 11% in Johannesburg. In 2007, 37/139 (27%) Cape Town isolates and 47/149 (32%) Johannesburg isolates were resistant to ciprofloxacin; in comparison with 2004 data, this represents 2.9-fold and 1.9-fold increases, respectively. All isolates were fully susceptible to ceftriaxone. There was a significant association between HIV seropositivity and the presence of ciprofloxacin-resistant gonorrhoea among patients (p = 0.034). CONCLUSIONS: Johannesburg and Cape Town have witnessed significant rises in the prevalence of ciprofloxacin-resistant gonorrhoea among men with urethritis. The resistant phenotype is linked to HIV seropositivity. There is now an urgent need to change national first-line therapy for presumptive gonococcal infections within South Africa.