OpenUCT :: Browsing by Subject "T cells"

Browsing by Subject "T cells"

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Open Access
Accumulation of splice variants and transcripts in response to PI3K inhibition in T cells
(Public Library of Science, 2013) Riedel, Alice; Mofolo, Boitumelo; Avota, Elita; Schneider-Schaulies, Sibylle; Meintjes, Ayton; Mulder, Nicola; Kneitz, Susanne
BACKGROUND: Measles virus (MV) causes T cell suppression by interference with phosphatidylinositol-3-kinase (PI3K) activation. We previously found that this interference affected the activity of splice regulatory proteins and a T cell inhibitory protein isoform was produced from an alternatively spliced pre-mRNA. Hypothesis Differentially regulated and alternatively splice variant transcripts accumulating in response to PI3K abrogation in T cells potentially encode proteins involved in T cell silencing. METHODS: To test this hypothesis at the cellular level, we performed a Human Exon 1.0 ST Array on RNAs isolated from T cells stimulated only or stimulated after PI3K inhibition. We developed a simple algorithm based on a splicing index to detect genes that undergo alternative splicing (AS) or are differentially regulated (RG) upon T cell suppression. RESULTS: Applying our algorithm to the data, 9% of the genes were assigned as AS, while only 3% were attributed to RG. Though there are overlaps, AS and RG genes differed with regard to functional regulation, and were found to be enriched in different functional groups. AS genes targeted extracellular matrix (ECM)-receptor interaction and focal adhesion pathways, while RG genes were mainly enriched in cytokine-receptor interaction and Jak-STAT. When combined, AS/RG dependent alterations targeted pathways essential for T cell receptor signaling, cytoskeletal dynamics and cell cycle entry. CONCLUSIONS: PI3K abrogation interferes with key T cell activation processes through both differential expression and alternative splicing, which together actively contribute to T cell suppression.
Open Access
Association of human TLR1 and TLR6 deficiency with altered immune responses to BCG vaccination in South African infants
(Public Library of Science, 2011) Randhawa, April Kaur; Shey, Muki S; Keyser, Alana; Peixoto, Blas; Wells, Richard D; de Kock, Marwou; Lerumo, Lesedi; Hughes, Jane; Hussey, Gregory; Hawkridge, Anthony; Kaplan, Gilla; Hanekom, Willem A; Hawn, Thomas R
The development of effective immunoprophylaxis against tuberculosis (TB) remains a global priority, but is hampered by a partially protective Bacillus Calmette-Guérin (BCG) vaccine and an incomplete understanding of the mechanisms of immunity to Mycobacterium tuberculosis. Although host genetic factors may be a primary reason for BCG's variable and inadequate efficacy, this possibility has not been intensively examined. We hypothesized that Toll-like receptor (TLR) variation is associated with altered in vivo immune responses to BCG. We examined whether functionally defined TLR pathway polymorphisms were associated with T cell cytokine responses in whole blood stimulated ex vivo with BCG 10 weeks after newborn BCG vaccination of South African infants. In the primary analysis, polymorphism TLR6_C745T (P249S) was associated with increased BCG-induced IFN-γ in both discovery (n = 240) and validation (n = 240) cohorts. In secondary analyses of the combined cohort, TLR1_T1805G (I602S) and TLR6_G1083C (synonymous) were associated with increased IFN-γ, TLR6_G1083C and TLR6_C745T were associated with increased IL-2, and TLR1_A1188T was associated with increased IFN-γ and IL-2. For each of these polymorphisms, the hypo-responsive allele, as defined by innate immunity signaling assays, was associated with increased production of TH1-type T cell cytokines (IFN-γ or IL-2). After stimulation with TLR1/6 lipopeptide ligands, PBMCs from TLR1/6-deficient individuals (stratified by TLR1_T1805G and TLR6_C745T hyporesponsive genotypes) secreted lower amounts of IL-6 and IL-10 compared to those with responsive TLR1/6 genotypes. In contrast, no IL-12p70 was secreted by PBMCs or monocytes. These data support a mechanism where TLR1/6 polymorphisms modulate TH1 T-cell polarization through genetic regulation of monocyte IL-10 secretion in the absence of IL-12. These studies provide evidence that functionally defined innate immune gene variants are associated with the development of adaptive immune responses after in vivo vaccination against a bacterial pathogen in humans. These findings could potentially guide novel adjuvant vaccine strategies as well as have implications for IFN-γ-based diagnostic testing for TB.
Open Access
BALB/c mice deficient in CD4 T cell IL-4Rα expression control Leishmania mexicana Load although female but not male mice develop a healer phenotype
(Public Library of Science, 2011) Bryson, Karen J; Millington, Owain R; Mokgethi, Thabang; McGachy, H Adrienne; Brombacher, Frank; Alexander, James
Immunologically intact BALB/c mice infected with Leishmania mexicana develop non-healing progressively growing lesions associated with a biased Th2 response while similarly infected IL-4Rα-deficient mice fail to develop lesions and develop a robust Th1 response. In order to determine the functional target(s) for IL-4/IL-13 inducing non-healing disease, the course of L. mexicana infection was monitored in mice lacking IL-4Rα expression in specific cellular compartments. A deficiency of IL-4Rα expression on macrophages/neutrophils (in LysMcreIL-4Rα−/lox animals) had minimal effect on the outcome of L. mexicana infection compared with control (IL-4Rα−/flox) mice. In contrast, CD4+ T cell specific (LckcreIL-4Rα−/lox) IL-4Rα−/− mice infected with L. mexicana developed small lesions, which subsequently healed in female mice, but persisted in adult male mice. While a strong Th1 response was manifest in both male and female CD4+ T cell specific IL-4Rα−/− mice infected with L. mexicana, induction of IL-4 was manifest in males but not females, independently of CD4+ T cell IL-4 responsiveness. Similar results were obtained using pan-T cell specific (iLckcreIL-4Rα−/lox) IL-4Rα−/− mice. Collectively these data demonstrate that upon infection with L. mexicana, initial lesion growth in BALB/c mice is dependent on non-T cell population(s) responsive to IL-4/IL-13 while progressive infection is dependent on CD4+ T cells responsive to IL-4.
Open Access
The candidate TB vaccine, MVA85A, induces highly durable Th1 responses
(Public Library of Science, 2014) Tameris, Michele; Geldenhuys, Hennie; Luabeya, Angelique KanyKany; Smit, Erica; Hughes, Jane E; Vermaak, Samantha; Hanekom, Willem A; Hatherill, Mark; Mahomed, Hassan; McShane, Helen; Scriba,Thomas J
BACKGROUND: Vaccination against tuberculosis (TB) should provide long-term protective immunity against Mycobacterium tuberculosis ( M.tb ). The current TB vaccine, Bacille Calmette-Guerin (BCG), protects against disseminated childhood TB, but protection against lung TB in adolescents and adults is variable and mostly poor. One potential reason for the limited durability of protection may be waning of immunity through gradual attrition of BCG-induced T cells. We determined if a MVA85A viral-vector boost could enhance the durability of mycobacteria-specific T cell responses above those induced by BCG alone. METHODS: We describe a long-term follow-up study of persons previously vaccinated with MVA85A. We performed a medical history and clinical examination, a tuberculin skin test and measured vaccine-specific T cell responses in persons previously enrolled as adults, adolescents, children or infants into three different Phase II trials, between 2005 and 2011. RESULTS: Of 252 potential participants, 183 (72.6%) consented and completed the study visit. Vaccine-induced Ag85A-specific CD4+ T cell responses were remarkably persistent in healthy, HIV-uninfected adults, adolescents, children and infants, up to 6 years after MVA85A vaccination. Specific CD4+ T cells expressed surface markers consistent with either CD45RA−CCR7+ central memory or CD45RA−CCR7− effector memory T cells. Similarly durable Ag85A-specific CD4+ T cell responses were detected in HIV-infected persons who were on successful antiretroviral therapy when MVA85A was administered. By contrast, Ag85A-specific CD4+ T cell frequencies in untreated MVA85A-vaccinated HIV-infected persons were mostly undetectable 3-5 years after vaccination. CONCLUSION: MVA85A induces remarkably durable T cell responses in immunocompetent persons. However, results from a recent phase IIb trial of MVA85A, conducted in infants from the same geographic area and study population, showed no vaccine efficacy, suggesting that these durable T cell responses do not enhance BCG-induced protection against TB in infants.
Open Access
CD8+ T-cell interleukin-7 receptor alpha expression as a potential indicator of disease status in HIV-infected children
(Public Library of Science, 2008) Sharma, Tanvi S; Hughes, Jane; Murillo, Amarylis; Riley, Joanne; Soares, Andreia; Little, Francesca; Mitchell, Charles D; Hanekom, Willem A
BACKGROUND: Initiation and modification of antiretroviral therapy in HIV-infected children depend on viral load and CD4+ T-cell count. However, these surrogates have limitations, and complementary immunological markers to assess therapeutic response are needed. Our aim was to evaluate CD8+ T-cell expression of CD127 as a marker of disease status in HIV-infected children, based on adult data suggesting its usefulness. We hypothesized that CD127 expression on CD8+ T-cells is lower in children with more advanced disease. METHODS: In a cross-sectional evaluation, we used flow cytometry to measure CD127+ expression on CD8+ T-cells in whole blood from HIV-infected children with varying disease status. This was compared with expression of CD38 on this subset, currently used in clinical practice as a marker of disease status. RESULTS: 51 HIV-infected children were enrolled. There was a strong positive correlation between CD127 expression on CD8+ T-cells and CD4+ T-cell count, and height and weight z-scores, and a strong negative correlation between CD127 expression and viral load. In contrast, we found no association between CD38 expression and these disease status markers. CONCLUSIONS: CD8+ T-cell CD127 expression is significantly higher in children with better HIV disease control, and may have a role as an immunologic indicator of disease status. Longitudinal studies are needed to determine the utility of this marker as a potential indicator of HIV disease progression.
Open Access
A comparative analysis of polyfunctional T cells and secreted cytokines induced by Bacille Calmette-Guerin immunisation in children and adults
(Public Library of Science, 2012) Ritz, Nicole; Strach, Madeleine; Yau, Carmen; Dutta, Binita; Tebruegge, Marc; Connell, Tom G; Hanekom, Willem A; Britton, Warwick J; Robins-Browne, Roy; Curtis, Nigel
BCG vaccine is one of the most commonly-administered vaccines worldwide. Studies suggest the protective efficacy of BCG against TB is better for children than for adults. One potential explanation is that BCG induces a better protective immune response in children. Twenty six children and adults were immunised with BCG. The proportion of Th1-cytokine-producing mycobacterial-specific T cells, and the concentrations of secreted cytokines, were measured before and 10 weeks after BCG immunisation. A significant increase in the proportion of mycobacterial-specific cytokine-producing T cells was observed in both age groups. After BCG immunisation, children and adults had comparable proportions of mycobacterial-specific polyfunctional CD4 T cells when measured relative to the total number of CD4 T cells. However, relative to the subset of Th-1-cytokine-producing CD4 T cells, the proportion of polyfunctional cells was greater in children. Concentrations of secreted cytokines were comparable in children and adults. These findings suggest that the mycobacterial-specific cell-mediated immune response induced by BCG immunisation in children and adults is similar. The implication of a shift to a more polyfunctional immune response within the Th1-cytokine-producing CD4 T cells in children is uncertain as this aspect of the immune response has not been assessed as a potential correlate of protection against TB.
Open Access
Conserved immune recognition hierarchy of mycobacterial PE/PPE proteins during infection in natural hosts
(Public Library of Science, 2012) Vordermeier, H Martin; Hewinson, R Glyn; Wilkinson, Robert J; Wilkinson, Katalin A; Gideon, Hannah P; Young, Douglas B; Sampson, Samantha L
The Mycobacterium tuberculosis genome contains two large gene families encoding proteins of unknown function, characterized by conserved N-terminal proline and glutamate (PE and PPE) motifs. The presence of a large number of PE/PPE proteins with repetitive domains and evidence of strain variation has given rise to the suggestion that these proteins may play a role in immune evasion via antigenic variation, while emerging data suggests that some family members may play important roles in mycobacterial pathogenesis. In this study, we examined cellular immune responses to a panel of 36 PE/PPE proteins during human and bovine infection. We observed a distinct hierarchy of immune recognition, reflected both in the repertoire of PE/PPE peptide recognition in individual cows and humans and in the magnitude of IFN-γ responses elicited by stimulation of sensitized host cells. The pattern of immunodominance was strikingly similar between cattle that had been experimentally infected with Mycobacterium bovis and humans naturally infected with clinical isolates of M. tuberculosis. The same pattern was maintained as disease progressed throughout a four-month course of infection in cattle, and between humans with latent as well as active tuberculosis. Detailed analysis of PE/PPE responses at the peptide level suggests that antigenic cross-reactivity amongst related family members is a major determinant in the observed differences in immune hierarchy. Taken together, these results demonstrate that a subset of PE/PPE proteins are major targets of the cellular immune response to tuberculosis, and are recognized at multiple stages of infection and in different disease states. Thus this work identifies a number of novel antigens that could find application in vaccine development, and provides new insights into PE/PPE biology.
Open Access
Correlation of mycobacterium tuberculosis specific and non-specific quantitative Th1 T-cell responses with bacillary load in a high burden setting
(Public Library of Science, 2012) Theron, Grant; Peter, Jonny; Lenders, Laura; van Zyl-Smit, Richard; Meldau, Richard; Govender, Ureshnie; Dheda, Keertan
BACKGROUND: Measures of bacillary load in patients with tuberculosis (TB) may be useful for predicting and monitoring response to treatment. The relationship between quantitative T-cell responses and mycobacterial load remains unclear. We hypothesised that, in a HIV-prevalent high burden setting, the magnitude of mycobacterial antigen-specific and non-specific T-cell IFN-γ responses would correlate with (a) bacterial load and (b) culture conversion in patients undergoing treatment. METHODS: We compared baseline (n = 147), 2 (n = 35) and 6 month (n = 13) purified-protein-derivative (PPD) and RD1-specific (TSPOT.TB and QFT-GIT) blood RD1-specific (TSPOT.TB; QFT-GIT) responses with associates of sputum bacillary load in patients with culture-confirmed TB in Cape Town, South Africa. RESULTS: IFN-γ responses were not associated with liquid culture time-to-positivity, smear-grade, Xpert MTB/RIF-generated cycle threshold values or the presence of cavities on the chest radiograph in patients with culture-confirmed TB and irrespective of HIV-status. 2-month IGRA conversion rates (positive-to-negative) were negligible [<11% for TSPOT.TB (3/28) and QFT-GIT (1/29)] and lower compared to culture [60% (21/35); p<0.01]. CONCLUSIONS: In a high burden HIV-prevalent setting T-cell IFN-γ responses to M. tuberculosis- specific and non-specific antigens do not correlate with bacillary load, including Xpert MTB/RIF-generated C T values, and are therefore poorly suited for monitoring treatment and prognostication.
Open Access
Deletion of IL-4Ralpha on CD4 T cells renders BALB/c mice resistant to Leishmania major infection
(Public Library of Science, 2007) Radwanska, Magdalena; Cutler, Antony J; Hoving, J Claire; Magez, Stefan; Holscher, Christoph; Bohms, Andreas; Arendse, Berenice; Kirsch, Richard; Hunig, Thomas; Alexander, James
Author Summary Leishmaniasis is a disease induced by a protozoan parasite and transmitted by the sandfly. Several forms of infection are identified, and the different diseases have wide-ranging symptoms from localized cutaneous sores to visceral disease affecting many internal organs. Animal models of human cutaneous leishmaniasis have been established in which disease is induced by infecting mice subcutaneously with Leishmania major. Different strains of inbred mice have been found to be susceptible or resistant to L. major infection. "Healer" C57BL/6 mice control infection with transient lesion development. The protective response to infection in this strain is dominated by type 1 cytokines inducing parasite killing by nitric oxide. Conversely, "nonhealer" BALB/c mice are unable to control infection and develop nonhealing lesions associated with a dominant type 2 immune response driven by cytokines IL-4 and IL-13. However, mice deficient in IL-4/IL-13 signaling are not protected against development of cutaneous leishmaniasis. Here we describe a BALB/c mouse where the ability to polarize to a dominant type 2 response is removed by cell-specific deletion of the receptor for IL-4/IL-13 on CD4 + T cells. These mice are resistant to L. major infection similar to C57BL/6 mice, which highlights the role of T helper 2 cells in driving susceptibility and the protective role of IL-4/IL-13 signaling in non-CD4 + T cells in BALB/c mice.
Open Access
Effect of female genital schistosomiasis and anti-schistosomal treatment on monocytes, CD4+ T-cells and CCR5 expression in the female genital tract
(Public Library of Science, 2014) Kleppa, Elisabeth; Ramsuran, Veron; Zulu, Siphosenkosi; Karlsen, Gunn Hege; Bere, Alfred; Passmore, Jo-Ann S; Ndhlovu, Patricia; Lillebø, Kristine; Holmen, Sigve D; Onsrud, Mathias
BACKGROUND: Schistosoma haematobium is a waterborne parasite that may cause female genital schistosomiasis (FGS), characterized by genital mucosal lesions. There is clinical and epidemiological evidence for a relationship between FGS and HIV. We investigated the impact of FGS on HIV target cell density and expression of the HIV co-receptor CCR5 in blood and cervical cytobrush samples. Furthermore we evaluated the effect of anti-schistosomal treatment on these cell populations. Design The study followed a case-control design with post treatment follow-up, nested in an on-going field study on FGS. METHODS: Blood and cervical cytobrush samples were collected from FGS negative and positive women for flow cytometry analyses. Urine samples were investigated for schistosome ova by microscopy and polymerase chain reaction (PCR). RESULTS: FGS was associated with a higher frequency of CD14 + cells (monocytes) in blood (11.5% in FGS+ vs. 2.2% in FGS-, p = 0.042). Frequencies of CD4 + cells expressing CCR5 were higher in blood samples from FGS+ than from FGS- women (4.7% vs. 1.5%, p = 0.018). The CD14 + cell population decreased significantly in both compartments after anti-schistosomal treatment (p = 0.043). Although the frequency of CD4+ cells did not change after treatment, frequencies of CCR5 expression by CD4+ cells decreased significantly in both compartments (from 3.4% to 0.5% in blood, p = 0.036; and from 42.4% to 5.6% in genital samples, p = 0.025). CONCLUSIONS: The results support the hypothesis that FGS may increase the risk of HIV acquisition, not only through damage of the mucosal epithelial barrier, but also by affecting HIV target cell populations, and that anti-schistosomal treatment can modify this.
Open Access
HIV-1 subtype C mosaic Gag expressed by BCG and MVA elicits persistent effector t cell responses in a prime-boost regimen in mice
(Public Library of Science, 2016) Jongwe, Tsungai Ivai; Chapman, Ros; Douglass, Nicola; Chetty, Shivan; Chege, Gerald; Williamson, Anna-Lise
Over 90% of HIV/AIDS positive individuals in sub-Saharan Africa are infected with highly heterogeneous HIV-1 subtype C (HIV-1C) viruses. One of the best ways to reduce the burden of this disease is the development of an affordable and effective prophylactic vaccine. Mosaic immunogens are computationally designed to overcome the hurdle of HIV diversity by maximizing the expression of potential T cell epitopes. Mycobacterium bovis BCG Δ panCD auxotroph and modified vaccinia Ankara (MVA) vaccines expressing HIV-1C mosaic Gag (Gag M ) were tested in a prime-boost regimen to demonstrate immunogenicity in a mouse study. The BCG-Gag M vaccine was stable and persisted 11.5 weeks post vaccination in BALB/c mice. Priming with BCG-Gag M and boosting with MVA-Gag M elicited higher Gag-specific IFN-γ ELISPOT responses than the BCG-Gag M only and MVA-Gag M only homologous vaccination regimens. The heterologous vaccination also generated a more balanced and persistent CD4 + and CD8 + T cell Gag-specific IFN-γ ELISPOT response with a predominant effector memory phenotype. A Th1 bias was induced by the vaccines as determined by the predominant secretion of IFN-γ, TNF-α, and IL-2. This study shows that a low dose of MVA (10 4 pfu) can effectively boost a BCG prime expressing the same mosaic immunogen, generating strong, cellular immune responses against Gag in mice. Our data warrants further evaluation in non-human primates. A low dose vaccine would be an advantage in the resource limited countries of sub-Saharan Africa and India (where the predominating virus is HIV-1 subtype C).
Open Access
Hypoxia induces an immunodominant target of tuberculosis specific T cells absent from common BCG vaccines
(Public Library of Science, 2010) Gideon, Hannah Priyadarshini; Wilkinson, Katalin Andrea; Rustad, Tige R; Oni, Tolu; Guio, Heinner; Kozak, Robert Andrew; Sherman, David R; Meintjes, Graeme; Behr, Marcel A; Vordermeier, Hans Martin
Author Summary Mycobacterium tuberculosis (the cause of tuberculosis) can persist for many years in humans without causing disease but has the potential to reactivate. One of the conditions the bacterium must survive in these circumstances is hypoxia. In order to do so, the bacterium uses a characteristic set of genes that help alter its metabolism. It follows that the products of such genes may encode protein antigens that can be recognized by the immune response. We therefore analyzed gene response patterns of tuberculosis subject to prolonged hypoxia as a guide to the discovery of new antigens that might be useful as vaccines or diagnostic agents. Amongst the genes most strongly increased by low oxygen levels, one was identified (known as Rv1986) that is missing from most strains of the tuberculosis vaccine Mycobacterium bovis BCG. When we analyzed human immune responses to this protein in tuberculosis infected people our experiments showed it was particularly well recognized by cells that produce a chemical messenger (cytokine) called interleukin-2. Interleukin-2 is important for long-term immunological memory. The BCG vaccine is only partially effective and our experiments therefore suggest one of the reasons could be that an important immunological target is missing from many strains. Further evaluation of BCG strains in which Rv1986 is present or absent is therefore warranted in the hope that this might improve the efficacy of existing or new tuberculosis vaccines.
Open Access
Identification of Antigens Specific to Non-Tuberculous Mycobacteria: The Mce Family of Proteins as a Target of T Cell Immune Responses
(Public Library of Science, 2011) Checkley, Anna M.; Wyllie, David H.; Scriba, Thomas J.; Golubchik, Tanya; Hill, Adrian V. S.; Hanekom, Willem A.; McShane, Helen
The lack of an effective TB vaccine hinders current efforts in combating the TB pandemic. One theory as to why BCG is less protective in tropical countries is that exposure to non-tuberculous mycobacteria (NTM) reduces BCG efficacy. There are currently several new TB vaccines in clinical trials, and NTM exposure may also be relevant in this context. NTM exposure cannot be accurately evaluated in the absence of specific antigens; those which are known to be present in NTM and absent from M. tuberculosis and BCG. We therefore used a bioinformatic pipeline to define proteins which are present in common NTM and absent from the M. tuberculosis complex, using protein BLAST, TBLASTN and a short sequence protein BLAST to ensure the specificity of this process. We then assessed immune responses to these proteins, in healthy South Africans and in patients from the United Kingdom and United States with documented exposure to NTM. Low level responses were detected to a cluster of proteins from the mammalian cell entry family, and to a cluster of hypothetical proteins, using ex vivo ELISpot and a 6 day proliferation assay. These early findings may provide a basis for characterising exposure to NTM at a population level, which has applications in the field of TB vaccine design as well as in the development of diagnostic tests.
Open Access
IL-1 and IL-23 mediate early IL-17A production in pulmonary inflammation leading to late fibrosis
(Public Library of Science, 2011) Gasse, Paméla; Riteau, Nicolas; Vacher, Rachel; Michel, Marie-Laure; Fautrel, Alain; di Padova, Franco; Fick, Lizette; Charron, Sabine; Lagente, Vincent; Eberl, Gérard
BACKGROUND: Idiopathic pulmonary fibrosis is a devastating as yet untreatable disease. We demonstrated recently the predominant role of the NLRP3 inflammasome activation and IL-1β expression in the establishment of pulmonary inflammation and fibrosis in mice. METHODS: The contribution of IL-23 or IL-17 in pulmonary inflammation and fibrosis was assessed using the bleomycin model in deficient mice. RESULTS: We show that bleomycin or IL-1β-induced lung injury leads to increased expression of early IL-23p19, and IL-17A or IL-17F expression. Early IL-23p19 and IL-17A, but not IL-17F, and IL-17RA signaling are required for inflammatory response to BLM as shown with gene deficient mice or mice treated with neutralizing antibodies. Using FACS analysis, we show a very early IL-17A and IL-17F expression by RORγt + γδ T cells and to a lesser extent by CD4αβ + T cells, but not by iNKT cells, 24 hrs after BLM administration. Moreover, IL-23p19 and IL-17A expressions or IL-17RA signaling are necessary to pulmonary TGF-β1 production, collagen deposition and evolution to fibrosis. CONCLUSIONS: Our findings demonstrate the existence of an early IL-1β-IL-23-IL-17A axis leading to pulmonary inflammation and fibrosis and identify innate IL-23 and IL-17A as interesting drug targets for IL-1β driven lung pathology.
Open Access
IL-33-mediated protection against experimental cerebral malaria is linked to induction of Type 2 innate lymphoid cells, M2 macrophages and regulatory T cells
(Public Library of Science, 2015) Besnard, Anne-Gaelle; Guabiraba, Rodrigo; Niedbala, Wanda; Palomo, Jennifer; Reverchon, Flora; Shaw, Tovah N; Couper, Kevin N; Ryffel, Bernhard; Liew, Foo Y
Author Summary Cerebral malaria (CM) caused by the parasite Plasmodium sp . is a fatal disease, especially in children. Currently there is no effective treatment. We report here our investigation on the role of a recently discovered cytokine IL-33, in treating experimental cerebral malaria (ECM) in the susceptible C57BL/6 mice. IL-33 protects the mice against ECM. The protection is accompanied by a reduction of Th1 response and the enhancement of type 2 cytokine response. We also found that IL-33 mediates its protective effect by inducing a population of type 2 innate lymphoid cells (ILC2), which then polarize macrophages to alternatively-activated phenotypes (M2). M2 in turn expand regulatory T cells (Tregs) which suppress the deleterious Th1 response. Our report therefore reveals hitherto unrecognised mechanisms of the regulation of ECM and provide a novel function of IL-33.
Open Access
IL-4Rα-associated antigen processing by B cells promotes immunity in Nippostrongylus brasiliensis infection
(Public Library of Science, 2013) Horsnell, William G C; Darby, Matthew G; Hoving, Jennifer C; Nieuwenhuizen, Natalie; McSorley, Henry J; Ndlovu, Hlumani; Bobat, Saeeda; Kimberg, Matti; Kirstein, Frank; Cutler, Anthony J
In this study, B cell function in protective TH2 immunity against N. brasiliensis infection was investigated. Protection against secondary infection depended on IL-4Rα and IL-13; but not IL-4. Protection did not associate with parasite specific antibody responses. Re-infection of B cell-specific IL-4Rα−/− mice resulted in increased worm burdens compared to control mice, despite their equivalent capacity to control primary infection. Impaired protection correlated with reduced lymphocyte IL-13 production and B cell MHC class II and CD86 surface expression. Adoptive transfer of in vivo N. brasiliensis primed IL-4Rα expressing B cells into naïve BALB/c mice, but not IL-4Rα or IL-13 deficient B cells, conferred protection against primary N. brasiliensis infection. This protection required MHC class II compatibility on B cells suggesting cognate interactions by B cells with CD4+ T cells were important to co-ordinate immunity. Furthermore, the rapid nature of these protective effects by B cells suggested non-BCR mediated mechanisms, such as via Toll Like Receptors, was involved, and this was supported by transfer experiments using antigen pulsed Myd88−/− B cells. These data suggest TLR dependent antigen processing by IL-4Rα-responsive B cells producing IL-13 contribute significantly to CD4+ T cell-mediated protective immunity against N. brasiliensis infection.
Open Access
IL-4Rα-Dependent Alternative Activation of Macrophages Is Not Decisive for Mycobacterium tuberculosis Pathology and Bacterial Burden in Mice
(Public Library of Science, 2015) Guler, Reto; Parihar, Suraj P; Savvi, Suzana; Logan, Erin; Schwegmann, Anita; Roy, Sugata; Nieuwenhuizen, Natalie E; Ozturk, Mumin; Schmeier, Sebastian; Suzuki, Harukazu; Brombacher, Frank
Classical activation of macrophages (caMph or M1) is crucial for host protection against Mycobacterium tuberculosis ( Mtb ) infection. Evidence suggests that IL-4/IL-13 alternatively activated macrophages (aaMph or M2) are exploited by Mtb to divert microbicidal functions of caMph. To define the functions of M2 macrophages during tuberculosis (TB), we infected mice deficient for IL-4 receptor α on macrophages (LysM cre IL-4Rα -/lox ) with Mtb . We show that absence of IL-4Rα on macrophages does not play a major role during infection with Mtb H37Rv, or the clinical Beijing strain HN878. This was demonstrated by similar mortality, bacterial burden, histopathology and T cell proliferation between infected wild-type (WT) and LysM cre IL-4Rα -/lox mice. Interestingly, we observed no differences in the lung expression of inducible nitric oxide synthase (iNOS) and Arginase 1 (Arg1), well-established markers for M1/M2 macrophages among the Mtb -infected groups. Kinetic expression studies of IL-4/IL-13 activated bone marrow-derived macrophages (BMDM) infected with HN878, followed by gene set enrichment analysis, revealed that the MyD88 and IL-6, IL-10, G-CSF pathways are significantly enriched, but not the IL-4Rα driven pathway. Together, these results suggest that IL-4Rα-macrophages do not play a central role in TB disease progression.
Open Access
IL-4Rα-independent expression of mannose receptor and Ym1 by macrophages depends on their IL-10 responsiveness
(Public Library of Science, 2010) Dewals, Benjamin G; Marillier, Reece G; Hoving, Jennifer C; Leeto, Mosiuoa; Schwegmann, Anita; Brombacher, Frank
IL-4Rα-dependent responses are essential for granuloma formation and host survival during acute schistosomiasis. Previously, we demonstrated that mice deficient for macrophage-specific IL-4Rα (LysMcreIl4ra−/lox) developed increased hepatotoxicity and gut inflammation; whereas inflammation was restricted to the liver of mice lacking T cell-specific IL-4Rα expression (iLckcreIl4ra−/lox). In the study presented here we further investigated their role in liver granulomatous inflammation. Frequencies and numbers of macrophage, lymphocyte or granulocyte populations, as well as Th1/Th2 cytokine responses were similar in Schistosoma mansoni-infected LysMcreIl4ra−/lox liver granulomas, when compared to Il4ra−/lox control mice. In contrast, a shift to Th1 responses with high IFN-γ and low IL-4, IL-10 and IL-13 was observed in the severely disrupted granulomas of iLckcreIl4ra−/lox and Il4ra−/− mice. As expected, alternative macrophage activation was reduced in both LysMcreIl4ra−/lox and iLckcreIl4ra−/lox granulomas with low arginase 1 and heightened nitric oxide synthase RNA expression in granuloma macrophages of both mouse strains. Interestingly, a discrete subpopulation of SSChighCD11b+I-A/I-EhighCD204+ macrophages retained expression of mannose receptor (MMR) and Ym1 in LysMcreIl4ra−/lox but not in iLckcreIl4ra−/lox granulomas. While aaMφ were in close proximity to the parasite eggs in Il4ra−/lox control mice, MMR+Ym1+ macrophages in LysMcreIl4ra−/lox mice were restricted to the periphery of the granuloma, indicating that they might have different functions. In vivo IL-10 neutralisation resulted in the disappearance of MMR+Ym1+ macrophages in LysMcreIl4ra−/lox mice. Together, these results show that IL-4Rα-responsive T cells are essential to drive alternative macrophage activation and to control granulomatous inflammation in the liver. The data further suggest that in the absence of macrophage-specific IL-4Rα signalling, IL-10 is able to drive mannose receptor- and Ym1-positive macrophages, associated with control of hepatic granulomatous inflammation.
Open Access
Impaired CD4 T cell memory response to Streptococcus pneumoniae precedes CD4 T cell depletion in HIV-infected Malawian adults
(Public Library of Science, 2011) Glennie, Sarah J; Sepako, Enoch; Mzinza, David; Harawa, Visopo; Miles, David J C; Jambo, Kondwani C; Gordon, Stephen B; Williams, Neil A; Heyderman, Robert S
Objective Invasive pneumococcal disease (IPD) is a leading cause of morbidity and mortality in HIV-infected African adults. CD4 T cell depletion may partially explain this high disease burden but those with relatively preserved T cell numbers are still at increased risk of IPD. This study evaluated the extent of pneumococcal-specific T cell memory dysfunction in asymptomatic HIV infection early on in the evolution of the disease. METHODS: Peripheral blood mononuclear cells were isolated from asymptomatic HIV-infected and HIV-uninfected Malawian adults and stained to characterize the underlying degree of CD4 T cell immune activation, senescence and regulation. Pneumococcal-specific T cell proliferation, IFN-γ, IL-17 production and CD154 expression was assessed using flow cytometry and ELISpot. RESULTS: We find that in asymptomatic HIV-infected Malawian adults, there is considerable immune disruption with an increase in activated and senescent CD4 + CD38 + PD-1 + and CD4 + CD25 high Foxp3 + Treg cells. In the context of high pneumococcal exposure and therefore immune stimulation, show a failure in pneumococcal-specific memory T cell proliferation, skewing of T cell cytokine production with preservation of interleukin-17 but decreased interferon-gamma responses, and failure of activated T cells to express the co-stimulatory molecule CD154. CONCLUSION: Asymptomatic HIV-infected Malawian adults show early signs of pneumococcal- specific immune dysregulation with a shift in the balance of CD4 memory, T helper 17 cells and Treg. Together these data offer a mechanistic understanding of how antigen-specific T cell dysfunction occurs prior to T cell depletion and may explain the early susceptibility to IPD in those with relatively preserved CD4 T cell numbers.
Open Access
Impairment of IFN-gamma response to synthetic peptides of mycobacterium tuberculosis in a 7-day whole blood assay
(Public Library of Science, 2013) Gideon, Hannah Priyadarshini; Hamilton, Melissa Shea; Wood, Kathryn; Pepper, Dominique; Oni, Tolu; Seldon, Ronnett; Banwell, Claire; Langford, Paul R; Wilkinson, Robert J; Wilkinson, Katalin A
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.