Factors affecting haemoglobin dynamics in African children with acute uncomplicated Plasmodium falciparum malaria treated with single low-dose primaquine or placebo.

BACKGROUND: Single low-dose primaquine (SLDPQ) effectively blocks the transmission of Plasmodium falciparum malaria, but anxiety remains regarding its haemolytic potential in patients with glucose-6-phopshate dehydrogenase (G6PD) deficiency. We, therefore, examined the independent effects of several factors on haemoglobin (Hb) dynamics in falciparum-infected children with a particular interest in SLDPQ and G6PD status. METHODS: This randomised, double-blind, placebo-controlled, safety trial was conducted in Congolese and Ugandan children aged 6 months-11 years with acute uncomplicated P. falciparum and day (D) 0 Hbs ≥ 6 g/dL who were treated with age-dosed SLDPQ/placebo and weight-dosed artemether lumefantrine (AL) or dihydroartemisinin piperaquine (DHAPP). Genotyping defined G6PD (G6PD c.202T allele), haemoglobin S (HbS), and α-thalassaemia status. Multivariable linear and logistic regression assessed factor independence for continuous Hb parameters and Hb recovery (D42 Hb > D0 Hb), respectively. RESULTS: One thousand one hundred thirty-seven children, whose median age was 5 years, were randomised to receive: AL + SLDPQ (n = 286), AL + placebo (286), DHAPP + SLDPQ (283), and DHAPP + placebo (282). By G6PD status, 284 were G6PD deficient (239 hemizygous males, 45 homozygous females), 119 were heterozygous females, 418 and 299 were normal males and females, respectively, and 17 were of unknown status. The mean D0 Hb was 10.6 (SD 1.6) g/dL and was lower in younger children with longer illnesses, lower mid-upper arm circumferences, splenomegaly, and α-thalassaemia trait, who were either G6PDd or heterozygous females. The initial fractional fall in Hb was greater in younger children with higher D0 Hbs and D0 parasitaemias and longer illnesses but less in sickle cell trait. Older G6PDd children with lower starting Hbs and greater factional falls were more likely to achieve Hb recovery, whilst lower D42 Hb concentrations were associated with younger G6PD normal children with lower fractional falls, sickle cell disease, α-thalassaemia silent carrier and trait, and late treatment failures. Ten blood transfusions were given in the first week (5 SLDPQ, 5 placebo). CONCLUSIONS: In these falciparum-infected African children, posttreatment Hb changes were unaffected by SLDPQ, and G6PDd patients had favourable posttreatment Hb changes and a higher probability of Hb recovery. These reassuring findings support SLDPQ deployment without G6PD screening in Africa. TRIAL REGISTRATION: The trial is registered at ISRCTN 11594437.

Reduced and highly diverse peripheral HIV-1 reservoir in virally suppressed patients infected with non-B HIV-1 strains in Uganda.

BACKGROUND: Our understanding of the peripheral human immunodeficiency virus type 1 (HIV-1) reservoir is strongly biased towards subtype B HIV-1 strains, with only limited information available from patients infected with non-B HIV-1 subtypes, which are the predominant viruses seen in low- and middle-income countries (LMIC) in Africa and Asia. RESULTS: In this study, blood samples were obtained from well-suppressed ART-experienced HIV-1 patients monitored in Uganda (n = 62) or the U.S. (n = 50), with plasma HIV-1 loads < 50 copies/ml and CD4+ T-cell counts > 300 cells/ml. The peripheral HIV-1 reservoir, i.e., cell-associated HIV-1 RNA and proviral DNA, was characterized using our novel deep sequencing-based EDITS assay. Ugandan patients were slightly younger (median age 43 vs 49 years) and had slightly lower CD4+ counts (508 vs 772 cells/ml) than U.S. individuals. All Ugandan patients were infected with non-B HIV-1 subtypes (31% A1, 64% D, or 5% C), while all U.S. individuals were infected with subtype B viruses. Unexpectedly, we observed a significantly larger peripheral inducible HIV-1 reservoir in U.S. patients compared to Ugandan individuals (48 vs. 11 cell equivalents/million cells, p < 0.0001). This divergence in reservoir size was verified measuring proviral DNA (206 vs. 88 cell equivalents/million cells, p < 0.0001). However, the peripheral HIV-1 reservoir was more diverse in Ugandan than in U.S. individuals (8.6 vs. 4.7 p-distance, p < 0.0001). CONCLUSIONS: The smaller, but more diverse, peripheral HIV-1 reservoir in Ugandan patients might be associated with viral (e.g., non-B subtype with higher cytopathicity) and/or host (e.g., higher incidence of co-infections or co-morbidities leading to less clonal expansion) factors. This highlights the need to understand reservoir dynamics in diverse populations as part of ongoing efforts to find a functional cure for HIV-1 infection in LMICs.

Productive HIV-1 infection is enriched in CD4(-)CD8(-) double negative (DN) T cells at pleural sites of dual infection with HIV and Mycobacterium tuberculosis.

A higher human immunodeficiency virus 1 (HIV-1) viral load at pleural sites infected with Mycobacterium tuberculosis (MTB) than in peripheral blood has been documented. However, the cellular source of productive HIV infection in HIV-1/MTB-coinfected pleural fluid mononuclear cells (PFMCs) remains unclear. In this study, we observed significant quantities of HIV-1 p24(+) lymphocytes in PFMCs, but not in peripheral blood mononuclear cells (PBMCs). HIV-1 p24(+) lymphocytes were mostly enriched in DN T cells. Intracellular CD4 expression was detectable in HIV-1 p24(+) DN T cells. HIV-1 p24(+) DN T cells showed lower surface expression of human leukocyte antigen (HLA)-ABC and tetherin than did HIV-1 p24(+) CD4 T cells. Upon in vitro infection of PFMC CD4 T cells from TB mono-infected subjects, Nef- and/or Vpu-deleted HIV mutants showed lower generation of HIV-1 p24(+) DN T cells than the wild-type virus. These data indicate that productively HIV-1-infected DN T cells, generated through down-modulation of surface CD4, likely by HIV-1 Nef and Vpu, are the predominant source of HIV-1 at pleural sites of HIV/MTB coinfection.

CD8+ T cells provide an immunologic signature of tuberculosis in young children.

RATIONALE: The immunologic events surrounding primary Mycobacterium tuberculosis infection and development of tuberculosis remain controversial. Young children who develop tuberculosis do so quickly after first exposure, thus permitting study of immune response to primary infection and disease. We hypothesized that M. tuberculosis-specific CD8(+) T cells are generated in response to high bacillary loads occurring during tuberculosis. OBJECTIVES: To determine if M. tuberculosis-specific T cells are generated among healthy children exposed to M. tuberculosis and children with tuberculosis. METHODS: Enzyme-linked immunosorbent spot assays were used to measure IFN-γ production in response to M. tuberculosis-specific proteins ESAT-6/CFP-10 by peripheral blood mononuclear cells and CD8(+) T cells isolated from Ugandan children hospitalized with tuberculosis (n = 96) or healthy tuberculosis contacts (n = 62). MEASUREMENTS AND MAIN RESULTS: The proportion of positive CD8(+) T-cell assays and magnitude of CD8(+) T-cell responses were significantly greater among young (<5 yr) tuberculosis cases compared with young contacts (P = 0.02, Fisher exact test, P = 0.01, Wilcoxon rank-sum, respectively). M. tuberculosis-specific T-cell responses measured in peripheral blood mononuclear cells were equivalent between groups. CONCLUSIONS: Among young children, M. tuberculosis-specific CD8(+) T cells develop in response to high bacillary loads, as occurs during tuberculosis, and are unlikely to be found after M. tuberculosis exposure. T-cell responses measured in peripheral blood mononuclear cells are generated after M. tuberculosis exposure alone, and thus cannot distinguish exposure from disease. In young children, IFN-γ-producing M. tuberculosis-specific CD8(+) T cells provide an immunologic signature of primary M. tuberculosis infection resulting in disease.

Safety of age-dosed, single low-dose primaquine in children with glucose-6-phosphate dehydrogenase deficiency who are infected with Plasmodium falciparum in Uganda and the Democratic Republic of the Congo: a randomised, double-blind, placebo-controlled, non-inferiority trial.

BACKGROUND: WHO recommends gametocytocidal, single low-dose primaquine for blocking the transmission of Plasmodium falciparum; however, safety concerns have hampered the implementation of this strategy in sub-Saharan Africa. We aimed to investigate the safety of age-dosed, single low-dose primaquine in children from Uganda and the Democratic Republic of the Congo. METHODS: We conducted this randomised, double-blind, placebo-controlled, non-inferiority trial at the Mbale Regional Referral Hospital, Mbale, Uganda, and the Kinshasa Mahidol Oxford Research Unit, Kinshasa, Democratic Republic of the Congo. Children aged between 6 months and 11 years with acute uncomplicated P falciparum infection and haemoglobin concentrations of at least 6 g/dL were enrolled. Patients were excluded if they had a comorbid illness requiring inpatient treatment, were taking haemolysing drugs for glucose-6-phosphate dehydrogenase (G6PD) deficiency, were allergic to the study drugs, or were enrolled in another clinical trial. G6PD status was defined by genotyping for the G6PD c.202T allele, the cause of the G6PD-deficient A- variant. Participants were randomly assigned (1:1) to receive single low-dose primaquine combined with either artemether-lumefantrine or dihydroartemisinin-piperaquine, dosed by bodyweight. Randomisation was stratified by age and G6PD status. The primary endpoint was the development of profound (haemoglobin <4 g/dL) or severe (haemoglobin <5 g/dL) anaemia with severity features, within 21 days of treatment. Analysis was by intention to treat. The sample size assumed an incidence of 1·5% in the placebo group and a 3% non-inferiority margin. The trial is registered at ISRCTN, 11594437, and is closed to new participants. FINDINGS: Participants were recruited at the Mbale Regional Referral Hospital between Dec 18, 2017, and Oct 7, 2019, and at the Kinshasa Mahidol Oxford Research Unit between July 17, 2017, and Oct 5, 2019. 4620 patients were assessed for eligibility. 3483 participants were excluded, most owing to negative rapid diagnostic test or negative malaria slide (n=2982). 1137 children with a median age of 5 years were enrolled and randomly assigned (286 to the artemether-lumefantrine plus single low-dose primaquine group, 286 to the artemether-lumefantrine plus placebo group, 283 to the dihydroartemisinin-piperaquine plus single low-dose primaquine group, and 282 to the dihydroartemisinin-piperaquine plus placebo group). Genotyping of G6PD identified 239 G6PD-c.202T hemizygous males and 45 G6PD-c.202T homozygous females (defining the G6PD-deficient group), 119 heterozygous females, 418 G6PD-c.202C normal males and 299 G6PD-c.202C normal females (defining the non-G6PD-deficient group), and 17 children of unknown status. 67 patients were lost to follow-up and four patients withdrew during the study-these numbers were similar between groups. No participants developed profound anaemia and three developed severe anaemia: from the G6PD-deficient group, none (0%) of 133 patients who received placebo and one (0·66%) of 151 patients who received primaquine (difference -0·66%, 95% CI -1·96 to 0·63; p=0·35); and from the non-G6PD-deficient group, one (0·23%) of 430 patients who received placebo and one (0·25%) of 407 patients who received primaquine (-0·014%, -0·68 to 0·65; p=0·97). INTERPRETATION: Gametocytocidal, age-dosed, single low-dose primaquine was well tolerated in children from Uganda and the Democratic Republic of the Congo who were infected with P falciparum, and the safety profile of this treatment was similar to that of the placebo. These data support the wider implementation of single low-dose primaquine in Africa. FUNDING: UK Government Department for International Development, UK Medical Research Council, UK National Institute for Health Research, and the Wellcome Trust Joint Global Health Trials Scheme.

Pharmacokinetics of single low dose primaquine in Ugandan and Congolese children with falciparum malaria.

BACKGROUND: There are no pharmacokinetic data of single low dose primaquine (SLDPQ) as transmission blocking in African children with acute Plasmodium falciparum and glucose-6-phosphate dehydrogenase deficiency (G6PDd). METHODS: Primaquine pharmacokinetics of age-dosed SLDPQ (shown previously to be gametocytocidal with similar tolerability as placebo) were characterised in falciparum-infected Ugandan and Congolese children aged 6 months to 11 years, treated on admission with standard 3-day dihydroartemisinin-piperaquine or artemether-lumefantrine plus SLDPQ: 6 m-<1 y: 1.25 mg, 1-5 y: 2.5 mg, 6-9 y: 5 mg, 10-11 y: 7.5 mg. LC-MS/MS-measured plasma primaquine and carboxyprimaquine (baseline, 1, 1.5, 2, 4, 8, 12, 24 h) were analysed by noncompartmental analysis. Multivariable linear regression modelled associations between covariates, including cytochrome-P450 2D6 metaboliser status, and outcomes. FINDINGS: 258 children (median age 5 [interquartile range (IQR) 3-7]) were sampled; 8 (3.1%) with early vomiting were excluded. Primaquine doses of 0.10-0.40 (median 0.21, IQR 0.16-0.25) mg base/kg resulted in primaquine maximum plasma concentrations (Cmax) of 2.3-447 (median 103.0, IQR 72.1-140.0) ng/mL between 1.0 and 8.0 (median 2) hours (Tmax) and median areas under the drug concentration curves (AUC0-last) 730.2 (6 m-<1 y, n = 12), 582.8 (1-5 y, n = 126), 871.1 (6-9 y, n = 80), and 931.0 (10-11 y, n = 32) ng∗h/mL. Median elimination half-live (T½) was 4.7 (IQR 3.8-5.6) hours. Primaquine clearance/kg peaked at 18 months, plateauing at 4 y. Increasing CYP2D6 metaboliser activity score [poor (3/250), intermediate (52/250), normal (150/250), ultrarapid (5/250), indeterminate (40/250)] and baseline haemoglobin were significantly associated with a lower primaquine AUC0-last,which increased with increasing mg/kg dose and age but was independent of the artemisinin treatment used. INTERPRETATION: Age-dosed SLDPQ resulted in variable primaquine exposure that depended on bodyweight-adjusted dose, age, baseline haemoglobin and CYP2D6 metaboliser status, but not on dihydroartemisinin-piperaquine or artemether-lumefantrine. These data support age-dosed SLDPQ for transmission blocking in sub-Saharan Africa. FUNDING: This work was cofunded by the UK Medical Research Council, Wellcome Trust, and UK Aid through the Global Health Trials (grant reference MR/P006973/1). The funders had no role in the study design, execution, and analysis and decisions regarding publication.

Response to M. tuberculosis selected RD1 peptides in Ugandan HIV-infected patients with smear positive pulmonary tuberculosis: a pilot study.

BACKGROUND: Tuberculosis (TB) is the most frequent co-infection in HIV-infected individuals still presenting diagnostic difficulties particularly in developing countries. Recently an assay based on IFN-gamma response to M. tuberculosis RD1 peptides selected by computational analysis was developed whose presence is detected during active TB disease. Objective of this study was to investigate the response to selected RD1 peptides in HIV-1-infected subjects with or without active TB in a country endemic for TB and to evaluate the change of this response over time. METHODS: 30 HIV-infected individuals were prospectively enrolled, 20 with active TB and 10 without. Among those with TB, 12 were followed over time. IFN-gamma response to selected RD1 peptides was evaluated by enzyme-linked immunospot (ELISPOT) assay. As control, response to RD1 proteins was included. Results were correlated with immune, microbiological and virological data. RESULTS: Among patients with active TB, 2/20 were excluded from the analysis, one due to cell artifacts and the other to unresponsiveness to M. tuberculosis antigens. Among those analyzable, response to selected RD1 peptides evaluated as spot-forming cells was significantly higher in subjects with active TB compared to those without (p = 0.02). Among the 12 TB patients studied over time a significant decrease (p =< 0.007) of IFN-gamma response was found at completion of therapy when all the sputum cultures for M. tuberculosis were negative. A ratio of RD1 peptides ELISPOT counts over CD4+ T-cell counts greater than 0.21 yielded 100% sensitivity and 80% specificity for active TB. Conversely, response to RD1 intact proteins was not statistically different between subjects with or without TB at the time of recruitment; however a ratio of RD1 proteins ELISPOT counts over CD4+ T-cell counts greater than 0.22 yielded 89% sensitivity and 70% specificity for active TB. CONCLUSION: In this pilot study the response to selected RD1 peptides is associated with TB disease in HIV-infected individuals in a high TB endemic country. This response decreases after successful therapy. The potential of the novel approach of relating ELISPOT spot-forming cell number and CD4+ T-cell count may improve the possibility of diagnosing active TB and deserves further evaluation.

Comprehensive definition of human immunodominant CD8 antigens in tuberculosis.

Despite widespread use of the Bacillus Calmette-Guerin vaccine, tuberculosis, caused by infection with Mycobacterium tuberculosis, remains a leading cause of morbidity and mortality worldwide. As CD8+ T cells are critical to tuberculosis host defense and a phase 2b vaccine trial of modified vaccinia Ankara expressing Ag85a that failed to demonstrate efficacy, also failed to induce a CD8+ T cell response, an effective tuberculosis vaccine may need to induce CD8+ T cells. However, little is known about CD8, as compared to CD4, antigens in tuberculosis. Herein, we report the results of the first ever HLA allele independent genome-wide CD8 antigen discovery program. Using CD8+ T cells derived from humans with latent tuberculosis infection or tuberculosis and an interferon-γ ELISPOT assay, we screened a synthetic peptide library representing 10% of the Mycobacterium tuberculosis proteome, selected to be enriched for Mycobacterium tuberculosis antigens. We defined a set of immunodominant CD8 antigens including part or all of 74 Mycobacterium tuberculosis proteins, only 16 of which are previously known CD8 antigens. Immunogenicity was associated with the degree of expression of mRNA and protein. Immunodominant antigens were enriched in cell wall proteins with preferential recognition of Esx protein family members, and within proteins comprising the Mycobacterium tuberculosis secretome. A validation study of immunodominant antigens demonstrated that these antigens were strongly recognized in Mycobacterium tuberculosis-infected individuals from a tuberculosis endemic region in Africa. The tuberculosis vaccine field will likely benefit from this greatly increased known repertoire of CD8 immunodominant antigens and definition of properties of Mycobacterium tuberculosis proteins important for CD8 antigenicity.

Immune Activation at Sites of HIV/TB Co-Infection Contributes to the Pathogenesis of HIV-1 Disease.

Systemic immune activation is critical to the pathogenesis of HIV-1 disease, and is accentuated in HIV/TB co-infected patients. The contribution of immune activation at sites of HIV/TB co-infection to viral activity, CD4 T cell count, and productive HIV-1 infection remain unclear. In this study, we measured markers of immune activation both in pleural fluid and plasma, and in T cells in pleural fluid mononuclear cell (PFMC) and peripheral blood mononuclear cell (PBMC) in HIV/TB co-infected subjects. The relationship between soluble and T cell activation markers with viral load in pleural fluid and blood CD4 T cell count were assessed. The T cell phenotype and activation status of HIV-1 p24 + T cells in PFMC and PBMC from HIV/TB patients were determined. We found that T cell and macrophage-specific and non-specific soluble markers of immune activation, sCD27, sCD163, IL1Ra, and sCD14, were higher in pleural fluid as compared to plasma from HIV/TB co-infected subjects, and higher as compared to pleural fluid from TB mono-infected subjects. Intestinal fatty acid-binding protein, a marker of intestinal tract damage, in plasma from HIV/TB co-infected patients was not different than that in HIV+ subjects. Expression of HLADR and CD38 double positive (HLADR/CD38) on CD4 T cells, and CD69+ on CD8 T cells correlated with pleural fluid viral load, and inversely with blood CD4 T cell count. Higher expression of HLADR/CD38 and CCR5 on CD4 T cells, and HLADR/CD38 and CD69 on CD8 T cells in PFMC were limited to effector memory populations. HIV-1 p24+ CD8 negative (includes CD4 + and double negative T cells) effector memory T cells in PFMC had higher expression of HLADR/CD38, Ki67, and CCR5 compared to HIV-1 p24- CD8 negative PFMC. Cumulatively, these data indicate that sites of HIV/TB co-infection are the source of intense immune activation.