Browsing by Author "Horsnell, William"

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    Alterations in preconception, antenatal, and postnatal maternal gut microbiota influence offspring intestinal microbiota and immunity
    (2017) Nyangahu, Donald D; Jaspan, Heather B; Horsnell, William
    Maternal microbiota during pregnancy, as well as maternal disease state, may impact offspring gut bacterial colonisation. Here, we explore the impact of maternal antibiotics during gestation and/or nursing on offspring gut microbiota. Further, we investigate the effect of preconception helminth infections on maternal and infant gut microbiota. For maternal antibiotic experiments, dams were fed vancomycin, polymyxin B, or both, in drinking water during gestation, nursing or gestation plus nursing, and their offspring microbiota analysed at 14 days of life, alongside immunity in the spleens. Offspring born to vancomycin treated mothers had significantly higher relative abundance of Proteobacteria and Tenericutes while maternal oral polymyxin B led to significantly lower abundance of Proteobacteria and Deferribacteres in infants. Maternal oral vancomycin led to significant reduction in proportions of infant central memory CD4+ T cells (CD4+CD44hiCD62Lhi) regardless of antibiotic timing. Effector memory CD4+ T cells were significantly lower in pups born to dams treated with polymyxin B while nursing while proportions of central memory CD4 T cells were significantly increased in gestation only or gestation plus nursing pups. In addition, oral vancomycin in dams during nursing resulted in significantly reduced proportions of both total and follicular B cells in offspring born to antibiotic treated dams. Pups born to Vancomycin treated mothers had a significant delay in growth when infected with Respiratory Syncytial Virus (RSV). On the other hand, pups born to mothers treated with Polymyxin B during gestation or gestation plus nursing were susceptible to Nippostrongylus brasiliensis (Nb) infection. In the second study, we infected female BALB/c mice with 500Nb L3 three weeks prior to mating and examined the effect of preconception helminth infection on offspring microbiota and immunity. Preconception Nb infections led to alterations of maternal gut microbiota during pregnancy. In addition, we observed dramatic differences in offspring microbiota in pups born to previously helminth infected dams. Coriobacteriaceae were predominant in pups born to previously Nb infected dams when compared to uninfected dams. Overall, manipulation of maternal microbiota during gestation or lactation profoundly impacts offspring growth, intestinal microbiota and immunity to RSV and helminths.
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    Bystander influence of nematode exposure on subsequent herpesvirus infections in vivo
    (2019) Chetty, Alisha; Horsnell, William; Dewals, Benjamin
    Parasitic worms have the ability to modulate the hosts immune response to promote host control of the infection and also parasite survival in the host. Helminth infections classically induce a potent Th2-biased and regulatory immune imprint. This immune response also influences unrelated inflammatory processes in the host. Studies have shown helminth infections have bystander influences on unrelated conditions such as allergy and autoimmunity. Additionally, helminth infections can alter susceptibility to other infections. In this thesis, we investigate the systemic influences of murine nematode Nippostrongylus brasiliensis infection on host immunity in colonized and non-colonized tissues, and the implications of these effects on susceptibility to subsequent herpesvirus infections in vivo. We show that prior N. brasiliensis infection enhanced control of acute respiratory murid gammaherpesvirus (MuHV-4) infection, with an increase in viral-specific CD8+ T cells in colonized lung tissue. Enhanced effector cytokine responses by cytotoxic T cells were also observed with prior helminth exposure. Conversely, despite enhanced primary control, prior helminth exposure was associated with earlier and heightened genital reactivation of MuHV4. This demonstrates differences in local bystander and systemic effects of helminth exposure on the host, and on unrelated viral infections. We also show that N. brasiliensis infection, which transits the respiratory and gastrointestinal tracts, also systemically influences immunity in the female genital tract (FGT) in vivo. Here, helminth infection induced Th2-type immunity in the FGT, namely increased tissue IL-4, IL-5 and long-lasting eosinophilia. We further demonstrated that systemic influences of N. brasiliensis infection results in exacerbated genital pathology and inflammation, following subsequent intravaginal herpes simplex virus type II (HSV-2) infection. Increased HSV-2 pathology with prior helminth exposure was associated with diminished innate anti-viral immunity, increased IL-33, ILC2 and IL-5 responses, as well as significant eosinophilia. Interestingly, abolition of canonical Th2 immune signalling by the lack of IL-4Rα expression, enhanced innate anti-viral defences and provided protection from HSV-2 pathology. However, N. brasiliensis-induced exacerbation of HSV-2 illness was IL-4Rαindependent, associated with significant genital eosinophilia. Furthermore, antibody-depletion of eosinophils ameliorated nematode-exacerbated HSV-2 pathology, suggesting that nematode-induced genital eosinophilia mediates increased HSV-2 pathology in coinfected mice. We have therefore shown that helminth infections can induce local and systemic bystander immunity to lymphoid and myeloid immune compartments, which alters susceptibility to subsequent herpesvirus infections.
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    Disruption of maternal gut microbiota during gestation alters offspring microbiota and immunity
    (BioMed Central, 2018-07-07) Nyangahu, Donald D; Lennard, Katie S; Brown, Bryan P; Darby, Matthew G; Wendoh, Jerome M; Havyarimana, Enock; Smith, Peter; Butcher, James; Stintzi, Alain; Mulder, Nicola; Horsnell, William; Jaspan, Heather B
    Background: Early life microbiota is an important determinant of immune and metabolic development and may have lasting consequences. The maternal gut microbiota during pregnancy or breastfeeding is important for defining infant gut microbiota. We hypothesized that maternal gut microbiota during pregnancy and breastfeeding is a critical determinant of infant immunity. To test this, pregnant BALB/c dams were fed vancomycin for 5 days prior to delivery (gestation; Mg), 14 days postpartum during nursing (Mn), or during gestation and nursing (Mgn), or no vancomycin (Mc). We analyzed adaptive immunity and gut microbiota in dams and pups at various times after delivery. Results In addition to direct alterations to maternal gut microbial composition, pup gut microbiota displayed lower α-diversity and distinct community clusters according to timing of maternal vancomycin. Vancomycin was undetectable in maternal and offspring sera, therefore the observed changes in the microbiota of stomach contents (as a proxy for breastmilk) and pup gut signify an indirect mechanism through which maternal intestinal microbiota influences extra-intestinal and neonatal commensal colonization. These effects on microbiota influenced both maternal and offspring immunity. Maternal immunity was altered, as demonstrated by significantly higher levels of both total IgG and IgM in Mgn and Mn breastmilk when compared to Mc. In pups, lymphocyte numbers in the spleens of Pg and Pn were significantly increased compared to Pc. This increase in cellularity was in part attributable to elevated numbers of both CD4+ T cells and B cells, most notable Follicular B cells. Conclusion Our results indicate that perturbations to maternal gut microbiota dictate neonatal adaptive immunity.
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    Early-life immunity and susceptibility to Mycobacteria
    (2018) Logan, Erin; Horsnell, William; Hatherill, Mark; Cunningham, Adam F
    The naïve and not-yet developed infant immune system exhibits heightened susceptibility to external factors (e.g pathogens), and is shaped by these and others, such as maternal immunity. However, we do not yet fully understand their impact on development of infant immunity. A better understanding of these effects would benefit children world-wide, but especially those in low-middle income countries (LMIC), where increased exposure to pathogens due to poorer living conditions highlights the necessity of robust early-life immunity. Mycobacterium tuberculosis (Mtb) and helminths are pathogens co-endemic in many LMIC and cause significant morbidity and mortality in children. Infant immune responses to these pathogens, whether during standalone infection, co-infection or resulting from maternal infection are not fully understood. To contribute to this knowledge gap, we investigated early-life immune responses, how they relate to childhood Mtb/helminth infection and how they are affected by maternal infectious history and immunity. Analysis of clinical humoral responses revealed total IgG that increased significantly between baseline and tuberculosis (TB) investigation in infants who did not acquire Mtb infection; these infants also exhibited raised levels of measles-specific IgG and BCG-specific IgG2. No active helminth infections were detected, but the presence of Ascaris lumbricoides- and Trichuris trichiura-specific class-switched antibodies indicated prior exposure. No association was found between helminth-specific humoral responses and risk of Mtb infection, nor with maternal helminth-specific humoral responses. Conversely, data from murine experiments revealed a protective effect of maternal helminth infection (Nippostrongylus brasiliensis) on BCG infection in offspring, with reduced lung bacterial burden and increased numbers of activated CD4+ T cells and B cells. Maternal Nb infection may have a synergistic effect on BCG vaccination, as BCGvaccinated/infected pups from Nb-infected mothers had reduced lung bacterial burdens, increased CD4+ T cell and B cell responses and increased IFNγ-producing CD4+ T cells. Findings from this study suggest that childhood vaccines could provide heterologous protection against unrelated pathogens such as Mtb. The murine data suggest a protective effect of maternal helminth infection against BCG infection in offspring, but no similar finding was observed with the clinical data. The clear protective effect of maternal Nb infection during offspring BCG infection warrants a more in-depth clinical study addressing the functional effects of maternal helminth infection on Mtb infection outcome in infants.
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    The function of IL-4Rα expression on key immune cells during experimental Nippostrongylus brasiliensis infections
    (2006) Mearns, Helen; Brombacher, Frank; Horsnell, William
    The lifecycle of the parasitic nematode Nippostrogylus brasiliensis resembles that of the human hookworms Necator americanus and Ancylostoma duodenale and as such is a useful murine model for studying hookworm disease.
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    IL-4/IL-13 independent goblet cell hyperplasia in experimental helminth infections
    (BioMed Central Ltd, 2008) Marillier, Reece; Michels, Chesney; Smith, Elizabeth; Fick, Lizette; Leeto, Mosiuoa; Dewals, Benjamin; Horsnell, William; Brombacher, Frank
    BACKGROUND: Intestinal mucus production by hyperplasic goblet cells is a striking pathological feature of many parasitic helminth infections and is related to intestinal protection and worm expulsion. Induction of goblet cell hyperplasia is associated with TH2 immune responses, which in helminth infections are controlled primarily by IL-13, and also IL-4. In the study presented here we examine the goblet cell hyperplasic response to three experimental parasitic helminth infections; namely Nippostrongylus brasiliensis, Syphacia obvelata and Schistosoma mansoni. RESULTS: As expected N. brasiliensis infection induced a strong goblet cell hyperplasia dependent on IL-4/IL-13/IL-4Ralpha expression. In contrast, and despite previously published transiently elevated IL-4/IL-13 levels, S. obvelata infections did not increase goblet cell hyperplasia in the colon. Furthermore, induction of goblet cell hyperplasia in response to S. mansoni eggs traversing the intestine was equivalent between BALB/c, IL-4/IL-13-/- and IL-4Ralpha-/- mice. CONCLUSION: Together these data demonstrate that intestinal goblet cell hyperplasia can be independent of TH2 immune responses associated with parasitic helminth infections.
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    Inducible deletion of CD28 prior to secondary nippostrongylus brasiliensis infection impairs worm expulsion and recall of protective memory CD4 (+) T cell responses
    (Public Library of Science, 2014) Ndlovu, Hlumani; Darby, Mathew; Froelich, Monika; Horsnell, William; Lühder, Fred; Hünig, Thomas; Brombacher, Frank
    IL-13 driven Th2 immunity is indispensable for host protection against infection with the gastrointestinal nematode Nippostronglus brasiliensis. Disruption of CD28 mediated costimulation impairs development of adequate Th2 immunity, showing an importance for CD28 during the initiation of an immune response against this pathogen. In this study, we used global CD28−/− mice and a recently established mouse model that allows for inducible deletion of the cd28 gene by oral administration of tamoxifen (CD28−/loxCre+/−+TM) to resolve the controversy surrounding the requirement of CD28 costimulation for recall of protective memory responses against pathogenic infections. Following primary infection with N. brasiliensis, CD28−/− mice had delayed expulsion of adult worms in the small intestine compared to wild-type C57BL/6 mice that cleared the infection by day 9 post-infection. Delayed expulsion was associated with reduced production of IL-13 and reduced serum levels of antigen specific IgG1 and total IgE. Interestingly, abrogation of CD28 costimulation in CD28−/loxCre+/− mice by oral administration of tamoxifen prior to secondary infection with N. brasiliensis resulted in impaired worm expulsion, similarly to infected CD28−/− mice. This was associated with reduced production of the Th2 cytokines IL-13 and IL-4, diminished serum titres of antigen specific IgG1 and total IgE and a reduced CXCR5+ TFH cell population. Furthermore, total number of CD4+ T cells and B220+ B cells secreting Th1 and Th2 cytokines were significantly reduced in CD28−/− mice and tamoxifen treated CD28−/loxCre+/− mice compared to C57BL/6 mice. Importantly, interfering with CD28 costimulatory signalling before re-infection impaired the recruitment and/or expansion of central and effector memory CD4+ T cells and follicular B cells to the draining lymph node of tamoxifen treated CD28−/loxCre+/− mice. Therefore, it can be concluded that CD28 costimulation is essential for conferring host protection during secondary N. brasiliensis infection.
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    Influence of helminth infection on vaginal immunity
    (2023) Omondi, Fidilia; Horsnell, William; Ritter, Manuel
    Helminth infections induce systemic changes to host immunity and can impact unrelated infections, even those occurring at anatomical sites not normally colonised by the helminths. A few studies have shown that helminths can increase the risk of infection and pathology resulting from sexually transmitted viral infections in the female reproductive tract, however the evidence is limited and the scope of helminth infection on immunity and infection in the female reproductive tract has not been fully elucidated. In this thesis the impact of hookworm infection on immunity in the female reproductive tract and risk of Human Papillomavirus infection in humans was investigated. The influence of helminth infection on B and T cell responses in the female reproductive tract and how this impacts vaccine mediated responses to another viral infection of the female reproductive tract, Herpes Simplex Virus, Type 2 was also assessed in a mouse model. To determine the risk of Human Papillomavirus among hookworm infected participants, we compared the prevalence of Human Papillomavirus infection among hookworm infected and uninfected women. Hookworm infected women were two times more likely to be Human Papillomavirus positive than women with no hookworm infection. Furthermore, hookworm infection was positively associated with the intensity of Human Papillomavirus infection. To determine whether hookworm infection induced changes in vaginal immunity we employed multiplex assays to measure chemokine, cytokine and antibody levels in the vaginal flushes of our study participants. Hookworm infected women displayed an elevated mixed Type 1 (TNF-a, IL-2 and IL-12) and Type 2 (IL-4, IL-5, IL-13, eotaxin and elevated IgG4/ IgE ratio) immune response in the female reproductive tract in xvi comparison to uninfected women. Type 2 immunity was pronounced in hookworm and Human Papillomavirus co-infected women who maintained an elevated Type 2 signature (IL-4, IL-5, IL-13, eotaxin and elevated IgG4/ IgE ratio) and an increased Th2/Th1 ratio in comparison to uninfected women. We then investigated the impact of primary helminth infection on B and T cell immunity in the female reproductive tract using the mouse model of hookworm infection, Nippostrongylus brasiliensis. Nippostrongylus brasiliensis infection of wild type BALB/c mice resulted in increased B cells, IgG1+ B cells and IgG1+ follicular B cells as well as increased effector memory T cells and T follicular helper cells in iliac lymph nodes, which drain the female reproductive tract. We then infected wild type BALB/c mice with Nippostrongylus brasiliensis and immunised them with formalin inactivated Herpes Simplex Virus, Type 2 then challenged them intravaginally with lethal dose Herpes Simplex Virus, Type 2. Nippostrongylus brasiliensis infection did not significantly impact B cell responses to vaccination and subsequent challenge though there was a trend towards lower B cell responses in mice that received Nippostrongylus brasiliensis treatment prior to vaccination. Mice that had prior Nippostrongylus brasiliensis infection, however, had significantly lower effector memory CD4+ T cells than mice that did not have helminth infection before vaccination. In summary, this thesis demonstrates that helminth infection induces Type 2 associated immune changes in the female reproductive tract in humans and alters B and T cell populations in lymph nodes draining the female reproductive tract of mice. Furthermore, in humans, an increased risk of Human Papillomavirus infection and increased intensity of Human Papillomavirus infection was associated with hookworm infection. In mice, a dampening of Herpes Simplex Virus, Type 2 vaccine mediated xvii effector CD4 T cells responses and increased pathology following viral challenge was observed in mice previously infected with Nippostrongylus brasiliensis. The findings in this thesis highlight helminth infection as a significant risk factor for sexually transmitted viral infections and have implications for control of these infections among women living in helminth endemic areas.
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    The influence of maternal Nippostrongylus brasiliensis infection on immunity in offspring
    (2013) Mrdjen, Dunja; Horsnell, William
    This study investigates imprinting of the murine fetal immune system by maternal infection with the helminth Nippostrongylus brasiliensis (Nb) prior to pregnancy and its effect on control of the Salmonella enterica serovar typhimurium (STm) in offspring. We show that maternal Nb infection in BALB/c mice results in the transfer of Nb antigen (NES)-specific IgG1 in utero and through breastmilk, changes in lymphocyte populations and early germinal center formation in naive offspring. Maternal Nb infection does not interfere with control of STm in offspring in BALB/c mice, but may interfere with control of STm in C57BL/6 mice.
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    Investigating the role of CD28 costimulation and IL-4/IL-13 responsive myeloid and lymphoid cells during helminth infections in mice
    (2013) Ndlovu, H Hlumani; Brombacher, Frank; Horsnell, William
    The aim of this study was to evaluate the importance of CD28 in initiating protective Th2 immunity against both primary and secondary infections with N. brasiliensis. Our findings demonstrate that CD28 is required for initiation of protective Th2 immunity against primary infection with N. brasiliensis. Furthermore, the absence of CD28 impairs development of memory CD4⁺ T cell responses resulting in failure to clear adult N. brasiliensis worms during secondary infection. Failure to resolve infection was associated with reduced production of Th2 cytokines particularly IL-13 and IL-4, abrogated humoral immunity and failure to expand CXCR5⁺ TFH cells.
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    Investigation of immune responses in different mouse models of allergic asthma
    (2008) Kirstein, Frank; Lopata, Andreas; Brombacher, Frank; Horsnell, William
    Allergies are a common chronic disease and considerably decrease the quality of life for affected individuals. Understanding the immune responses during allergic diseases is essential for both diagnosis and the development of effective therapies. The route of sensitisation to allergens is one factor that influences the immune response and the outcome of allergic diseases and both human and animal studies have highlighted IL-4Ra as an important component in the induction of allergy. The aim of this study was to investigate the contributions of the route of sensitisation to allergens with focus on the significance of cell specific expression of IL-4Ra in the onset of allergy. The route of sensitization to Anisakis pegreffii influences the outcome of experimental allergic asthma: Worldwide, increasing numbers of allergies to the fish parasite Anisakis pegreffii are reported. Anisakis can cause allergies after accidental infection of humans and in the occupational environment. Currently it is not clear if different exposure routes to Anisakis affect the development of allergic asthma and if they have an influence on the immune response. To address these questions, the present study investigated immune responses and disease development after Anisakis live infection and after nasal sensitisation in a mouse model of allergic airway disease. We showed that the route of sensitisation influences the outcome of Anisakis pegreffii induced allergic asthma and demonstrated important contributions of IL-4Ra to the underlying immune response. Alternatively activated macrophages are not necessary for the development of experimental allergic lung inflammation: Development of alternatively activated macrophages (AAM) is induced by signals of IL-4Ra. Alternatively activated macrophages (AAM) are a feature of allergic asthma in clinical and experimental investigations but their role in the development of allergy is not defined. To address this, a model of acute allergic asthma was used to compare mice deficient in AAM (LysMcrelL-4Ra-110x mice) with control mice. We found that the presence of AAM at early stages of allergic airway inflammation these cells was not required for the onset of the disease. Smooth muscle IL-4Ra is not required for experimental allergic asthma: In vitro studies have suggested that IL-4Ra signalling on airway smooth muscle cells (ASMC) is critical for airway irrflammation and airway hyperresponsiveness. Using mice deficient for IL-4Ra in ASMC, the in vivo effects of impaired IL-4Ra signalling in ASMC on the outcome of asthmatic disease were investigated. The impairment of IL-4Ro: on SMC had no effect on major aetiological markers of allergic asthma. These findings suggest that IL-4Ra responsiveness in airway SMC during the acute phase of allergic asthma is not critical for the outcome of the disease. Conclusions: The present study showed the importance of the route of sensitisation and IL4Ra in the development of allergy to Anisakis pegreffii. The use of in vivo models of experimental allergic asthma revealed that the route of sensitisation can influence the underlying immune response of the disease. Furthermore, by using mice with cell specific deficiencies in IL-4Ra it was demonstrated that expression of this receptor on smooth muscle cells and macrophages is not essential for the development of acute experimental allergic airway disease, as it has been previously suggested.
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    Preconception maternal exposure to Nippostrongylus brasiliensis transfers protection against Nb to her offspring
    (2016) Darby, Matthew G; Horsnell, William; Brombacher, Frank
    In early life the immature immune system has a reduced ability to control infection. This susceptibility is offset by transfer of protective immune components from the mother. Helminth infections are widespread and can have a long lasting influence on host immunity. Children of mothers exposed to helminth infections may display T cell sensitization to endemic helminth infections and associations have been made between maternal helminth infection and altered immune responses to childhood diseases and vaccinations. This shows that helminth-modified maternal immunity may imprint on early offspring immune development in-utero or through breast milk in the form of transfer of, for example, antibodies, cytokines and lymphocytes. Our study shows that, in mice, maternal infection with the helminth Nippostrongylus brasiliensis is not only associated with a passive transfer of antigen specific antibody(IgG1) but also inherently alters offspring immunity, increasing offspring cytokine production, alveolar macrophages, lung neutrophils and B cell population development and proliferation. Pups born to N. brasiliensis exposed mothers also had increased populations of lung and spleen CD4+ cells and higher subpopulations of central memory and effector CD4+ cells compared to pups born to naive mothers.
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    Protective immunity against Nippostrongylus brasiliensis requires antigen presentation by IL-4Rα responsive B cells
    (2012) Darby, Matthew G; Brombacher, Frank; Horsnell, William
    Nippostrongylus brasiliensis is a parasitic nematode infection that affects rodents. B-cells have been shown to play an important role in immunity to many different infections by antibody production and T-cell activation. But B-cell function in the protective TH2 response against N. brasiliensis infection is an area of immunity that is currently not well defined. Recently, it has been shown that B-cells are essential to the resolution of a Heligomosomoides polygyrus infection, another parasitic helminth. Our aim in this study was to investigate any role that B-cells may play in response to a secondary N. brasiliensis infection by analysing the differences in immunity of wild-type and B-cell-specific IL-4Rα knockout mice after a N. brasiliensis re-infection.
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    Regulation of HPV infection and cervical cancer development following a helminth infection
    (2025) Butters, Claire; Horsnell, William; Schafer Georgia
    Soil-transmi,ed helminth (STH) infec7ons elicit systemic immune responses and have the ability to alter suscep7bility to other infec7ons in sites uncolonized by the STH. Recent work published by our group demonstrated that hookworm infec7on increased pathology in the female genital tract (FGT) following infec7on with the commonly sexually transmi,ed herpes simplex virus (HSV)-2. Although epidemiological studies have linked helminth infec7on with an increased prevalence of the most common sexually transmi,ed infec7on, human papillomavirus (HPV), studies in our lab have demonstrated that exposure to helminth products can decrease HPV pseudovirion uptake in vitro. Persistent infec7ons with high-risk types of HPV can result in cervical cancer, the leading cause of cancer related deaths in women in South Africa. Li,le is known about the associa7on between these two diseases. In this thesis, I inves7gated how HPV pseudovirion (PsV) infec7on can be altered by an STH infec7on both in vitro and in vivo. In vitro experiments demonstrated exposure to soma7c helminth an7gens from Nippostrongylus brasiliensis and Heligmosomoides polygyrus bakeri decreased HPV PsV infec7on in two cervical cancer cell lines and one primary kera7nocyte cell line (the target cell of HPV). Similarly, exposure to the excretory-secretory (ES) an7gens from H. polygyrus decreased HPV PsV infec7on in two cell lines, and increased HPV PsV infec7on in the other cervical cancer cell line. When the soma7c an7gens were heat inac7vated, the protec7on against HPV PsV infec7on was abrogated, sugges7ng the molecule involved in this protec7on is a heat unstable protein. In contrast, when H. polygyrus ES an7gen was heat inac7vated, the previously observed increase in infec7on was reversed and instead decreased HPV PsV infec7on. Addi7onally, western blot analysis revealed that exposure to N. brasiliensis soma7c an7gen resulted in increased expression of vimen7n, a molecule known to inhibit HPV infec7on. These results were then validated in vivo, through the development of a physiological murine model for HPV infec7on, u7lising a luminescent HPV PsV and in vivo imaging system (IVIS). Following op7misa7on, I found that HPV PsV infec7on was significantly reduced following intravaginal exposure to N. brasiliensis L3 an7gen and at day 9 post-infec7on with N. brasiliensis. This was associated with a significant increase in eosinophil accumula7on in the female genital tract (FGT) and iliac lymph node (iLN), the draining lymph node of the FGT. Coinfected mice demonstrated a popula7on of eosinophils expressing lower levels of Ly6C and higher levels of CD11b, a recruitment marker. When eosinophil recruitment was blocked, the helminth-dependent reduc7on in HPV infec7on is lost, sugges7ng these immune cells may contribute to this observed protec7on. Addi7onally, western blot analysis revealed that N. brasiliensis infec7on increased the expression of an HPV receptor, glypican. These data suggest that coinfec7on with N. brasiliensis has a protec7ve effect against the ini7al infec7on of HPV. Finally, to inves7gate how STH infec7on may influence the development and growth of HPVrelated cervical cancer, I developed a cervical cancer xenograY model using nude mice. Here, my data suggest that engraYed nude mice infected with N. brasiliensis displayed reduced growth of cervical cancer tumours compared to naïve mice, with no change to tumour immune cell infiltrates but rather an increase in tumour cell p53 expression and altered epithelial to mesenchymal transi7on (EMT) marker expression. Together, these findings show that helminth infec7on can protect against distal viral infec7on and suppress the growth and cancer cell behaviour of HPV associated cervical cancer.
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    Role of M3 muscarinic receptor in regulation of immunity to infectious pathogens
    (2013) Vira, Alykhan; Brombacher, Frank; Horsnell, William
    During the last decade, cholinergic signaling via acetylcholine and its receptors has emerged as an important regulator of immunity. Acetylcholine binds to and signals through two types of receptors; nicotinic and muscarinic receptors. Studies have shown that signaling through nicotinic receptors, particularly the α7 subtype on macrophages has potent anti-inflammatory effects. However, the role for muscarinic receptor has not yet been conclusively characterized. In this study, we demonstrate that M3 muscarinic receptor subtype is required for optimal protective immunity to two pathogens; the nematode Nippostrongylus brasiliensis and the bacterium Salmonella enterica sp. Tyhpimurium. M3R deficient mice (M3R-/-) were susceptible to infection with N.brasiliensis with decreased production of the protective cytokine IL-13. Furthermore, stimulation of lymphocytes with muscarinic agonists enhanced TH2 cytokine production in an M3R dependent manner.
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    Spatial and temporal regulation of IL4Rα expression
    (2008) Smith, Elizabeth M; Brombacher, Frank; Horsnell, William
    In this study, we generated a new mouse model, which allows both inducible and cell-specific deletion and reconstitution of IL-IL4Rα expression. This model has the potential to add a new dimension to our understanding of IL4Rα biology. This has been achieved by using the established Tet System (Goosen and Bujard, 1992) where the crossing of two complementary transgenic mouse lines enable the generation of the final double transgenic model. The first line expresses the transactivator, tTA, from the Tet-Off expression cassette driven by the Vav hemapoeitic specific promoter (Wiesner et al., 2005).
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    The role of platelets in the pathogenesis of and immunity to helminth infections
    (2022) Pollock, Jonathan; Horsnell, William; Darby, Matthew
    Background: Platelets are small, anucleate cells which circulate in blood and are often the first to respond to tissue damage and vascular inflammation caused by pathogens. Here they not only maintain tissue integrity and prevent bleeding, but also initiate and regulate a vast variety of immunologic responses. Little is known on the role of platelets in helminth infections, despite our understanding that many helminth species cause significant vascular pathology as they transfer from the circulatory system to diverse tissues as part of their life cycles. Based on previous studies showing tight association between platelets and innate immune responses during infection with other pathogens, we hypothesized that platelets significantly contribute toward acute (vascular) immunity to helminth infection. Objectives: This project aimed to investigate the role of platelets in regulating acute innate immune responses following infection with the murine gastro-intestinal nematode N. brasiliensis (Nb), commonly used to model human helminthiases. Specifically, it aimed to characterized plateletregulated responses involved in acute innate immunity during the pulmonary stage of infection, in which larvae exit the pulmonary vasculature and invade host lung tissue. Methods: C57BL/6mice were infected with 500 L3 Nb larvae, and the association of platelets with acute innate immune responses in the circulation and the lung were established by flow cytometry and immunohistochemistry. In further experiments, mice were depleted of their platelets using antibodies prior to infection with Nb and the effect of this on pulmonary pathology and innate immune responses was inferred from flow cytometric and histologic analyses of pulmonary tissues. Lastly, antibodies were used to interfere with platelet receptors during Nb infection to gain mechanistic insight into platelet regulation of neutrophil responses. Results: Infection with N. brasiliensis was associated with significant changes in the activation of platelets, their localisation into lung tissue and their interaction with innate immune cells. Additionally, platelet -immune cell interaction was associated with changes in the expression of factors known to play a role in driving the early immune response to Nb, including IFN-γ and RELMα. Furthermore, mice depleted of their platelets prior to infection had significantly enhanced pulmonary pathology and rapidly succumbed to infection. This was associated with significant changes in neutrophil responses, and depletion of neutrophils together with platelets significantly protected against enhanced pathology. Finally, direct and indirect targeting of the platelet receptors CD62P and CLEC-2 did not result in significantly enhanced pulmonary pathology but was associated with altered platelet and neutrophil responses. Conclusion: Herein, we have provided evidence that platelets tightly associate with protective host responses during acute N. brasiliensis infection and that their absence correlates with a dysregulated neutrophil response and enhanced helminth – associated pulmonary pathology. These data therefore collectively show that platelets play notable roles in the acute innate immune response to N. brasiliensis and that future investigations into the immunological functioning of platelets during helminth infection are warranted.
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    The role of pulmonary innate and adaptive immune responses to helminth infection
    (2014) Thawer, Sumaiyya G; Horsnell, William; Brombacher, Frank
    Immunity to nematode infections requires a host T helper 2 (Th2) response promoted by epithelial cell driven IL-33 induction of cytokine secretion of Interleukin (IL)-4, 5 and 13 by a range of immune cells including innate lymphoid cells type 2 (ILC2s) and CD4+ T cells. This induces effector responses such as goblet cell mucus secretion and mast cell activation driving disease resolution. Finding candidate molecules and discrete cell populations that enhance these responses would provide new targets for treating infection via specific host immune-modulation and would contribute to the development of effective vaccines against nematode infections. In this study we addressed how novel components of host adaptive and innate immunity can contribute to pulmonary control of Nippostrongylus brasiliensis infections. Murine reinfection studies with the parasitic nematode N. brasiliensis have shown development of a Th2 CD4+ T cell responses in the lung to be essential for immunity to secondary N. brasiliensis infection. To test if T cell recruitment from secondary lymphoid tissue contributed to this immunity, we used the drug Fingolimod (FTY720) to block T cell egress from lymph nodes (LN) to peripheral tissue. T cell egress from the LN was required for resolution of a primary infection but not for secondary infection. The presence of tissue-resident IL-4Rα responsive CD4+ T cells in the lung was sufficient for protective immunity to N. brasiliensis reinfection. These results demonstrated that effective CD4+ T cell Th2 immunity can be generated at peripheral sites by pre-existing T cell populations, independently of T cell recruitment from secondary lymphoid organs (SLO). Additionally, we identify that the pulmonary epithelial cell-secreted collectin, surfactant protein D (SP-D), is an important component of host immunity to N. brasiliensis infection. We demonstrate here that SP-D production is induced following N. brasiliensis infection in a Th2 dependent manner, it bound preferentially to lung stage L4 parasites and enhanced macrophage and ILC2 protective responses essential for controlling infection. vi Taken together the data presented in this thesis provides two new important insights into pulmonary host immunity to parasitic helminth infections.
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    The role of pulmonary innate and adaptive immune responses to helminth infection
    (2014) Thawer, Sumaiyya G; Horsnell, William; Brombacher, Frank
    Immunity to nematode infections requires a host T helper 2 (Th2) response promoted by epithelial cell driven IL-33 induction of cytokine secretion of Interleukin (IL)-4, 5 and 13 by a range of immune cells including innate lymphoid cells type 2 (ILC2s) and CD4+ T cells. This induces effector responses such as goblet cell mucus secretion and mast cell activation driving disease resolution. Finding candidate molecules and discrete cell populations that enhance these responses would provide new targets for treating infection via specific host immune-modulation and would contribute to the development of effective vaccines against nematode infections. In this study we addressed how novel components of host adaptive and innate immunity can contribute to pulmonary control of Nippostrongylus brasiliensis infections. Murine reinfection studies with the parasitic nematode N. brasiliensis have shown development of a Th2 CD4+ T cell responses in the lung to be essential for immunity to secondary N. brasiliensis infection. To test if T cell recruitment from secondary lymphoid tissue contributed to this immunity, we used the drug Fingolimod (FTY720) to block T cell egress from lymph nodes (LN) to peripheral tissue. T cell egress from the LN was required for resolution of a primary infection but not for secondary infection. The presence of tissue-resident IL-4Rα responsive CD4+ T cells in the lung was sufficient for protective immunity to N. brasiliensis reinfection. These results demonstrated that effective CD4+ T cell Th2 immunity can be generated at peripheral sites by pre-existing T cell populations, independently of T cell recruitment from secondary lymphoid organs (SLO). Additionally, we identify that the pulmonary epithelial cell-secreted collectin, surfactant protein D (SP-D), is an important component of host immunity to N. brasiliensis infection. We demonstrate here that SP-D production is induced following N. brasiliensis infection in a Th2 dependent manner, it bound preferentially to lung stage L4 parasites and enhanced macrophage and ILC2 protective responses essential for controlling infection. vi Taken together the data presented in this thesis provides two new important insights into pulmonary host immunity to parasitic helminth infections.
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    The role of Surfacant Protein D in the control of human helminth infections
    (2020) Baker, Zoe; Horsnell, William
    Lung produced surfactant protein D (SP-D) is essential for both homeostasis and as an innate immune opsonin. In the project presented here, we aimed to translate data recently published by our group, which demonstrated that SP-D contributes to protection against murine parasitic nematode infections, to human work. In the first part of this study, we determined whether individuals exposed to helminths have altered serum SP-D in comparison to unexposed individuals, through analysis (ELISA and Western Blot) of bio banked samples in 2 clinical cohorts from South Africa. Secondly, we aimed to identify if SP-D influences the magnitude of anti-nematode responses in human immune cells (type 2 innate lymphoid cells, monocytes and macrophages) through in vitro cell work and flow cytometry. Our findings indicated an association between serum SP-D and exposure to helminths that have a lung migration stage as part of their life cycle (Ascaris spp and Toxocara spp). Furthermore, in vitro analysis demonstrated that human immune cells primed with SP-D might have an altered response to helminth antigen. These findings point toward the need for further investigation into the novel role of SP-D in the control of human helminth infections in the context of immune physiology, as a biomarker and eventually treatment option.