There is burgeoning interest in the complex tripartite interplays between the commensal microbiota, host's genetic factors, and immune response during helminth infections which are still poorly understood. The study explores this relationship in the context of chronic schistosomiasis-driven pathology. In the first part of the thesis, removal of the host Basic Leucine Zipper ATF-Like Transcription Factor 2 (Batf2) gene in 129Sv (Batf2-/- ) mice resulted in alteration of the intestinal microbial composition and reduced granulomatous inflammatory immune response. These changes associated with rescue from pre-mature mortality and improved fitness of Batf2-/- mice during chronic experimental schistosomiasis in relation to control wild type mice. The prolonged survival and reduced immunopathology were diminished by treatment with α-CD8 antibody highlighting the significance of CD8-expressing immune mediators during chronic Schistosomiasis. Transfer of the altered intestinal microbiota from Batf2-/- mice to wild type mice by co-housing was enough to rescue the latter from exacerbated granulomatous inflammation and prolonged their survival during chronic schistosomiasis. These observations suggest, for the first time, a central role of the host gut microbiota in decisively regulating the tissue immune response, the elicited pathology and host survival during schistosomiasis. To validate the robustness of this tripartite interaction during chronic schistosomiasis around the gut microbiota, the second part of the present work analysed two genetically identical murine models (C57BL/6) housed under two different specific Pathogen free environments (SPF1 and SPF2) and presenting differential susceptibility to chronic schistosomiasis. Our work revealed a higher susceptibility of C57BL/6 mice from the SPF2 facility in relation to C57BL/6 mice from the SPF1 facility. In confirmation with our first series of experiments, that demonstrated a central role of the host intestinal microbiota in regulating the immune responses, the pathology, and the survival of the host during schistosomiasis, the second series of experiments further presented an ameliorated immunological, pathological and vital prognosis of vulnerable SPF2 C57BL/6 mice receiving the intestinal microbiota of more resistant SPF1 C57BL/6 mice. Therefore, the study demonstrates the genetic regulation of gut microbiota which in turn, and/or in concert with the genetic make-up, influence the immunological, pathological, and vital host response during chronic schistosomiasis. The present work expands the conventional knowledge on schistosomiasis disease regulation and presents the gene-microbiota-immune-response interactome as a core piece of the regulatory machinery of this infection as exploitable to alter disease progression in the context of drug and vaccine development.

Prevention of Alzheimer's disease (AD) is a major goal of biomedical sciences. In previous studies, this laboratory demonstrated that high intake of the essential nutrient, choline, during gestation ameliorated hippocampal amyloidosis in hemizygous APPswe/PS1dE9 (APP.PS1) AD model mice. In this study we investigated the effects of a similar treatment on behavioral phenotypes in the APPNL-G-F mouse model for AD. These mice express a humanized APP with three mutations that cause familial AD in humans [Swedish (NL), Arctic (G), and Beyreuther/Iberian (F)] under the control of the endogenous mouse APP promotor. The latter permits to overcome problems related to the overexpression of APP observed in the transgenic mouse models (e.g. APP.PS1) and is therefore considered a more physiological model for AD well suited for studies of the pathophysiology of this disease. We maintained the pregnant and lactating wild type C57BL/6J control mice and homozygous APPNL-G-F mice on a control AIN76A diet containing 1.1 g/kg of choline or a choline-supplemented (5 g/kg) diet. After weaning all offspring consumed the control diet. We used the male and female APPNL-G-F offspring as the AD model and the wild type mice as controls. The animals were examined in a cross-sectional fashion at 3, 6, 9 and 12 months of age using the Open Field (OF), Elevated Plus Maze (EPM), Barnes Maze (BM), and Contextual Fear Conditioning (CFC) experimental paradigms. As compared to controls, the APPNL-G-F mice exhibited abnormalities in anxiety-related behaviors at 3 and 6 months of age and learning and memory deficits at 9 and 12 months of age. Perinatal choline supplementation ameliorated some of the memory deficits in the 12-month old APPNL-G-F mice observed in the CFC test. The data suggest that dietary supplementation with choline during fetal development and early postnatal life prevents some of the behavioral abnormalities in the APPNL-G-F AD model mice.

Allergic asthma is a chronic inflammatory airway disease driven predominantly by a TH2 immune response to environmental allergens. The asthma pathology is predominantly elicited by IL-4 and IL-13 signalling via IL-4Rα-signalling which is essential for driving TH2-type immunity to allergens. Interestingly, the failure by regulatory T cells to maintain tolerance during allergic asthma, suggested to be driven by TH2 inflammatory signals, still remains elusive and anti-TH2 therapies with the potential to effectively reduce airway obstruction and inflammation in allergic asthma, have had limited success. Therefore, we aimed to investigate the function of IL-4/IL-13 responsive regulatory T cells in a TH2 rich environment and the temporal requirement of IL-4Rα-signalling in asymptomatic and acute airway disease. Objective 1: We investigated potential therapeutic effects of selective inhibition of this pathway in mice with established allergic airway disease and systemically sensitised mice to prevent the onset of the disease. We used RosacreERT2IL-4Rα-/lox mice, a novel, tamoxifen inducible IL-4Rα knockdown model to investigate the role of IL-4/IL-13 signalling during the effector phase of ovalbumin induced allergic airway disease (AAD) and for the onset of the disease. The deletion of the IL-4Rα had a therapeutic effect on established AAD and prevented the development of ovalbumin induced airway hyperreactivity, goblet cell metaplasia and eosinophilia in allergensensitised mice. We concluded that the abrogation of IL-4Rα signalling after allergic sensitisation would have significant therapeutic benefit for TH2 type allergic asthma. Objective 2: The canonical IL-4Rα-signalling, was investigated on its role on Foxp3+ Tregs in allergic asthma with aims to re-establish tolerance during allergic asthma. We used transgenic Foxp3cre IL-4Rα-/lox mice IL-4Rα-/lox mice to investigate the role of IL-4/IL-13 signalling during the induction or maintenance of tolerance in house dust mite-induced ADD. The depletion of IL-4Ra on Foxp3+ Tregs exacerbated airway hyperreactivity and airway inflammation in allergen- sensitised mice. Interestingly, a reduced induction of Foxp3+ Tregs in peripheral tissue and an accompanying increased IL-33 induced ILC2 driven inflammation in the lung responsible for the exacerbation of TH2 acute disease. Conclusively, the IL-4Rα responsive Foxp3+ T regulatory cells are key in maintaining tolerance in type 2 innate immune driven allergic asthma, therefore the TH2 environment has both an innate immune specific regulative role in local lung tissue and induction of Foxp3+ Tregs in peripheral tissue during AAD. A combined targeting of the pathogenic TH2 environment in anti-TH2 therapy and the augmentation of regulatory T cell function in the local lung tissue is necessary to inhibit both adaptive and innate drivers of TH2 inflammation in allergic disease.

Lung cancer is the leading cause of death among all cancer types, and a subtype of lung cancer known as lung squamous cell carcinoma (LUSC) is the second most predominant subtype accounting for ~30% of all lung cancer cases. Lung cancer is typically diagnosed at advanced stages, resulting in poor prognosis with a 5-year survival rate of 19% between 2008 and 2014 (Siegel et al., 2019). The lung cancer genome has extensively been profiled in part by The Cancer Genome Atlas (TCGA), identifying mutational signatures and revealing the contributions of tumor microenvironment. TCGA work has enabled the development of biomarkers and therapeutics for both identifying and treating advanced lung cancer. However, due to late diagnosis, the prognosis of lung cancer still remains poor. Therefore, understanding the genomics and immune microenvironment of premalignant lesions (PMLs) that precede the development of LUSC is crucial in order to improve the ability to diagnose disease early and identify intervention strategies to enhance the prognosis of lung cancer. As part of this thesis project, my objective is to validate, in both cancer cell lines and a carcinogenic mouse model, previously identified genes and their correlations with important immuno-regulatory pathways, as well as their impact in the progression or regression of PMLs. The Lung Pre-Cancer Genome Atlas (PCGA) has begun to achieve the aforementioned goals of understanding the early molecular events in the process of lung squamous carcinogenesis (Beane et al., 2019. In the prior study from our group, bronchial PMLs were obtained through bronchoscopy procedures from a high-risk screening cohort at Roswell Park and subject to a molecular and genomic profiling (Beane et al., 2019). Beane et al. identified four molecular subtypes of PMLs via transcriptional profiling, where one subtype, the proliferative subtype, of PMLs were found to be enriched for bronchial dysplastic lesions. Additionally, within samples in the proliferative subtype, it was demonstrated that immunoregulatory pathways, such as interferon signaling and antigen presentation, were suppressed in the progressive/persistent proliferative PMLs. Further computational analyses of the lung PCGA transcriptional data has identified that Glutathione S-transferase P (GSTP1) is up-regulated in PMLs that remain stable as dysplastic lesions or progress into advanced dysplastic lesions, suggesting that there is an anti-correlation between the expression of GSTP1 and immunological responses. Understanding the relationship between GSTP1 and its downstream effectors is important, as targeting GSTP1 may be a strategy to stimulate an immunological response in PMLs to drive a regression rather than progression towards invasive carcinoma. In order to establish the relationship between GSTP1 and immune-regulatory pathways such as the STAT3 and NF-KB pathways, we identified baseline expression of the target genes in cell lines all genes were consistent with the computational findings. Subsequently, the knockdown of GSTP1 demonstrated a significant decrease in the expression of GSTP1 but no change in STAT3 and NF-KB. Based on these results, interleukins such as IL-8 and IL-13 were used to stimulate immunological responses and expected to cause an increase in expression of STAT3 and NF-KB pathways. However, upon 48, 24 and 4 hours of IL-8 and IL-13 stimulation, STAT3 and NF-KB pathways did not present changes in expression. Furthermore, in effort to establish a viable research model for studying premalignant lesions of LUSC, we utilized the NTCU mouse model, a carcinogenic model that has been previously identified to mimic squamous lung carcinogenesis due to smoking in humans. The histology of the PMLs triggered by the NTCU treatment in mice resembles the carcinogenesis observed in human lungs, in which lesions progress from squamous metaplasia to increasing grades of dysplasia. Previous studies have suggested that carcinogenic models share mutational burden and specific gene mutations with humans opposed to genetically engineered mice (Westcott et al., 2015). As part of my work, I aimed to establish the viability of the NTCU mouse model as a representative model of study for PMLs in humans by analyzing the histology of lung lesions in mice at 8, 12 and 16 weeks of NTCU treatment. Furthermore, I established methods for isolating DNA and RNA from the tail and lungs of both control and NTCU treated mice for whole exome sequencing (WES) and RNA sequencing in addition to use for validation of my GSTP1 finding in an in vivo setting. Our goal was to show similarities between genomic changes of PMLs from the NTCU mice and human PMLs in order to establish the NTCU model as a means to further study changes identified in the progression of human disease. / 2021-06-02T00:00:00Z

Introduction: Culture remains the ‘gold standard' for diagnosis of Streptococcus pneumoniae bacteraemia. Time to definitive identification using culture is 24–48 hours, and prior antibiotic therapy, the ability of S. pneumoniae to self-autolyse and its fastidious nature can yield no growth on culture. Novel detection methods for invasive pneumococcal disease include PCR and antigen tests. We evaluated using a urine antigen test directly on selected blood cultures with appropriate Gram stain results, immediately after signalling positive for the rapid identification of S. pneumoniae bacteraemia. Method: We collected 212 blood cultures that had signalled positive with an automated blood culture system, and then yielded gram-positive cocci in pairs/chains or cocci with uncertain morphological arrangement. The BinaxNOW Streptococcus pneumoniae urinary antigen test, routine culture with optochin and real time lytA PCR was performed on all samples. Diagnostic accuracy analysis (sensitivity and specificity) of the antigen test and Gram stain with gram-positive cocci in pairs was each compared to culture positivity for S. pneumoniae, PCR positivity and the composite of culture or PCR positivity for S. pneumoniae as the reference standards. Results: S. pneumoniae (Spn) was cultured in 55 samples, gram-positive organisms other than S. pneumoniae (NSpn) in 140 samples and 17 samples had no growth (NG). Grampositive cocci in pairs was predominant on Gram stain in the Spn/NG groups whilst the minority in the NSpn group. In the Spn group, all except 1 sample which was antigen positive but PCR negative, were antigen and PCR positive. In the NSpn group, antigen and PCR was negative in 123 samples, antigen and PCR positive in 1 sample and antigen positive but PCR negative in the remaining 16 samples. In the NG group, antigen and PCR were positive in 16 samples and antigen positive but PCR negative in 1 sample. Sensitivity of the antigen test compared to culture, PCR or the composite of culture or PCR was 100%. Specificity was 87-88% but increased to 93-96% when used in subsets with gram-positive cocci in pairs or clinical history compatible with respiratory illness or meningitis. Sensitivity and specificity of the antigen test when compared to Gram stain using gram-positive cocci in pairs (69%-75% and 81% respectively) were both higher. Discussion and Conclusion: Accurate and rapid diagnosis of S. pneumoniae bacteraemia is challenging with current diagnostic tools. Specificity of the antigen test is mostly limited by crossreactivity with viridans streptococci, coagulase negative staphylococci and enterococcus species, but this can be overcome if Gram stain morphology and clinical history is available. Sensitivity and specificity of Gram stain alone in predicting S. pneumoniae bacteraemia is poor and is increased with use of the antigen test. The antigen test is a useful adjunctive tool improving diagnosis and turnaround time of S. pneumoniae bacteraemia. In settings like ours, where high-level resistance, defined as minimum inhibitory concentration ≥2μg/mL to penicillin is still relatively low (~7%), rapid de-escalation to penicillin in the appropriate clinical setting would be possible with the introduction of such test and could also potentially be a suitable alternative to molecular testing for S. pneumoniae identification in samples with no growth on culture.

T regulatory (Treg) cells play a pivotal role in the maintenance of self-tolerance and immune homeostasis. Forkhead box P3 (Foxp3)+ Treg function is controlled by environmental cues of which cytokine-mediated signaling is a dominant component. Recently, Interleukin (IL)-4 has been shown to play an important role in determining the fate of Foxp3+ Tregs. In vivo, IL-4-mediated signaling via Interleukin-4 receptor alpha (IL4Rα) was convincingly shown to mediate Treg transdifferentiation into ex-Foxp3 Th2 or Th17 cells, suggesting a negative regulation of Foxp3+ Tregs by IL-4Rα-mediated signaling. Puzzlingly, however, IL-4-mediated signaling was also independently found to reinforce the Foxp3+ Tregs, counter-arguing for the positive regulation of Foxp3+ Tregs by IL-4Rα-mediated signaling. In the face of such a conundrum, the present work was set forth as an attempt to unambiguously and conclusively decipher the bases of the regulation of Foxp3+ Treg by IL-4Rα-mediated signaling using transgenic murine models. It was first noted that Foxp3+ Treg cells do express IL-4Rα under steady-state. Furthermore, in vitro, purified CD25+ Tregs were prompted to higher Foxp3 expression and increased survival upon stimulation with IL-4 arguing for a potentiating role of IL-4Rα mediated signaling on Foxp3+ Treg cells. To better address the need for the host Foxp3+ Treg cells to express IL-4Rα as observed, we generated Foxp3-specific IL-4Rα deficient mice where IL-4Rα is specifically deleted from Foxp3+ T cells in the whole organism. Even though naïve Foxp3cre IL-4Rα -/lox mice model at homeostasis did neither reveal any significant alteration of the cellular, tissular and phenotypic profile nor development of spontaneous inflammatory disorder when compared to wild-type mice, under S. mansoni infection impairment IL-4Rα-mediated signaling on Foxp3+ Tregs resulted in heightened activation marker expression and elevated T cell effector functions as indicated by increased cytokines production and greater T cell proliferation rate. This heightened immune responsiveness translated overall into an exacerbated parasitic egg-driven fibrogranulomatous inflammation in the liver and the gut of schistosomiasis-diseased Foxp3cre IL-4Rα-/lox mice. Furthermore, in another model of helminth infection with the parasitic nematode, Nippostrongylus brasiliensis, Foxp3cre IL-4Rα-/lox mice showed a higher level of mucus and exaggerated emphysematous pathology in the lungs. Interestingly, the impairment of IL-4Rα signaling within the Foxp3+ Treg population in Foxp3cre IL-4Rα-/lox mice led to a reduced recruitment of Foxp3+ Tregs and a diminished expression of Foxp3, and other associated Treg suppressive markers (i.e. IRF4 and Helios) during the course of these helminth infections. Taken together, our findings supported a role for IL-4Rα signaling in the positive regulation of Foxp3+ Tregs function and thus, the suppression of inflammatory responses during helminth infections. In conclusion, this work demonstrated a positive role for IL-4Rα mediated signaling in the biology of Foxp3+ Treg cells whereby the latter cells require IL-4Rα signaling to survive and maintain Foxp3 expression and suppressive functions so as to efficiently control tissue inflammatory responses during infection. The data presented do provide insights into the mechanisms of Foxp3+ Treg regulation that are highly relevant for the therapeutic control of inflammation during infectious diseases.

A subgroup of women who are co-infected with human immunodeficiency virus type 1 (HIV1) and human papillomavirus (HPV) progress relatively rapidly to cervical disease regardless of the number of absolute CD4 count. During infection, viral peptides are recognized by the host immune system. It is reasonable to propose that the development of viral-associated cancers, like cervical cancer, requires interference with specific immune-response genes. This thesis investigates this proposition with consideration of host molecular genetic alterations and variations of the human leukocyte antigen class II (HLA II) genes as one of the groups of immune-response genes that are involved in directing CD4 T-cell responses during infection, in the instance of cervical cancer progression in HIV-1/HPV co-infected women. Study I, reviewed the available literature on host molecular genetics and HIV-1/HPV coinfection on cervical cancer progression. This study suggests that the dual pro-oncogenic effects of HPV oncoproteins E6/E7 and the HIV-1 oncoprotein Tat, may exacerbate and accelerate the rate of cervical disease progression in a subgroup of HIV-1-positive women. Additionally, HIV-1-positive cervical cancer has three important carcinogenesis steps: firstly, HPV integration into the host genome, secondly, dual pro-oncogenic effects of HPV oncoproteins E6/E7, and the HIV-1 Tat oncoprotein in the host genome and, thirdly, the accumulation of repeated, unrepaired genetic mutations and genetic alterations within the host chromosomal DNA. Genetic variations or mutations that affect the following host gene categories were suggested to be responsible for cervical cancer susceptibility and disease progression; (i) genes for the immune-response against oncogenic HPV infection, (ii) oncogenes, (iii) tumour-suppressor genes, (iv) apoptosis-related genes, (v) DNA damagerepair genes, and (vi) cell cycle-regulatory genes. However, studies II, III and IV are linked together and listed according to the specific objectives of this thesis. Study II, characterized the distribution of HPV genotypes within cervical tumour biopsies from a cohort of 181 HPV-unvaccinated South African women and studied the relationships with HIV-1 infection, age of patients, absolute CD4 count, CD4 percentage and the stage of cervical disease, and identified the predictive power of these variables for cervical disease stage. Distribution of HPV genotypes was related to the stage of cervical disease in HIV-1-positive women. Older age was a significant predictor for invasive cervical cancer (ICC) in both HIV-1-seronegative (p<0.0001) ) and HIV1-positive women (p=0.0003, q=0.0003). Sixty-eight percent (59/87) of HIV-1-positive women with different stages of cervical disease presented with CD4 percentage below or equal to 28 and a median absolute CD4 count of 400 cells/µl (IQR 300-500 cells/µl). Of the HIV-1-positive women, 75% (30/40) with ICC, possessed ≤28% CD4 cells versus 25% (10/40) who possessed >28% CD4 cells (both p< 0.001, q<0.001). Furthermore, 70% (28/40) of women with ICC possessed absolute CD4 count >350 cells/µl compared to 30% (12/40) who possessed absolute CD4 count ≤ 350 cells/µl (both p< 0.001, q< 0.001). Study III, was the first case-control study to investigate the association of HIV-1/HPV coinfection with specific host HLA II-DRB1 and -DQB1 alleles in cervical cancer. Two hundred and fifty-six (256) women of the same ethnicity were recruited, comprising 56 cases and 200 age-matched controls. A total of 624 HLA-DRB1 and -DQB1 class II genotypes were studied. HLA II-DQB1*03:01 and -DQB1*06:02 alleles were associated with cervical cancer in HIV-1/HPV co-infected women (p=0.001 and p< 0.0001, respectively) while HLA II-DRB1*13:01 and -DQB1*03:19 were rare or absent in women with cervical disease when compared to the control population (p=0.012 and 0.011, respectively). Study IV, aimed to investigate the host genetic alterations that may be involved in rapid tumour progression in HIV-1/HPV co-infected women. The frequency of loss of heterozygosity (LOH) and microsatellite instability (MSI) at the HLA II locus on chromosome 6p was analysed in cervical tumour biopsy DNA, with regard to HIV-1/HPV co-infection in 164 women. Seventy-four women were HIV-1-positive and ninety women were HIV-1-seronegative. Tumour DNA from HIV-1/HPV co-infected women demonstrated a higher frequency of LOH/MSI at the HLA II locus at 6p21.21 than tumour DNA from HIV1-seronegative women (D6S2447, 74.2% versus 42.6%; p=0.001, q=0.003), D6S2881 at 6p21.31 (78.3% versus 42.9%; p=0.002, q=0.004), D6S1666 at 6p21.32 (79% versus 57.1%; p=0.035, q=0.052), and D6S2746, at 6p21.33 (64.3% versus 29.4%; p< 0.001, q< 0.001), respectively. This thesis provides novel insights and adds to the existing knowledge on the relationships between HIV-1/HPV co-infection, CD4 immune status, host HLA II allele variations and genetic alterations at chromosome 6p in association or likely protection to cervical disease in the studied cohort of South African women. Identification of host molecular genetic susceptibility to disease with regard to viral infection is important for individualized molecular targeted prevention of cervical cancer.

An SOS-inducible DNA repair system has been linked to transient hyper-mutation and the development of drug resistance in Mycobacterium tuberculosis. Previous work has established that this “mycobacterial mutasome” comprises the specialist DNA polymerase, DnaE2, and accessory factors of unknown function, ImuA′ and ImuB. However, the molecular interactions and sub-cellular recruitment dynamics enabling mutasome function remain poorly understood. Here, a panel of fluorescent strains of M. smegmatis was developed to investigate expression and subcellular localization of ImuA′ and ImuB in live mycobacteria exposed to genotoxic agents. Using fluorescence microscopy, it was observed that, during prolonged genotoxic stress, single M. smegmatis cells exhibited an elongated cell phenotype and apparent aneuploidy – potentially providing an environment for recombination between differentially mutated chromosomes. Furthermore, ImuB was seen to associate with the dnaNencoded β clamp in discrete foci during mutagenic DNA repair. In contrast, ImuA′ did not exhibit similar localization and instead appeared to diffuse throughout the bacillus. A mutant ImuB protein deficient in the β clamp-binding motif failed to colocalize with the β clamp, reinforcing the inferred essentiality of the ImuB-β clamp protein-protein interaction for mutasome recruitment and induced mutagenesis. Additionally, exposure of M. smegmatis to griselimycin, a novel β clamp-targeting natural product antibiotic, prevented ImuB-β clamp co-localization during SOS induced mutagenesis, an observation confirmed by superresolution, threedimensional interferometric photo-activated light microscopy. These results establish the capacity of griselimycin to inhibit DNA replication as well as prevent DNA damage-induced mutagenesis by disrupting mutasome assembly and activity. Notably, this differentiates griselimycin from other inhibitors of DNA metabolic function which carry the often-unavoidable liability of accelerating drug-resistance by inducing mutagenic DNA repair. In turn, it suggests the potential application of griselimycin as an anti-evolution agent in novel therapeutic regimens designed to protect existing tuberculosis drugs.

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.

The ability of helminths to regulate inflammatory disorders and the mechanisms by which they carry this out are of great scientific interest. Currently, established literature emphasises the protective role of helminth infection in mouse models of inflammatory bowel disease (IBD). Utilising two well-established murine models of human disease, the oxazolone and dextran sulfate sodium (DSS) models, I found that induction of murine IBD is highly sensitive to diet change and mouse gender. Using the gastrointestinal helminth Heligmosomoides polygyrus (H.polygyrus), I demonstrate that helminth infection exacerbates IBD in both the oxazolone and DSS models of colitis. Underlying helminth infection results in increased inflammation locally in the colon and systemically in the spleen in both models of IBD, as measured by histology and flow cytometry. Exacerbation of DSS colitis is dependent on the dose of H.polygyrus but is independent of the phase of H.polygyrus infection, with both acute and chronic infections resulting in the same phenotype. Helminth exacerbated DSS colitis is characterised by significant bacterial translocation to the spleen, which is concluded to be due to loss of intestinal epithelial integrity. Helminth infection also resulted in a microbial shift of translocating bacteria following DSS administration, as evidenced by gram staining and bacterial sequencing. Administration of an 8- strain probiotic during acute helminth infection ameliorated helminth exacerbation of DSS colitis, restored epithelial integrity and abrogated splenomegaly. This work uncovers an unexpected and novel role for live helminth infection in exacerbating IBD and suggests that helminth-induced dysbiosis of the microbiota may drive disease. These studies reveal restoration of the microbiota through probiotics or helminth eradication as potential therapies for the treatment of gastrointestinal inflammatory disorders.