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Bovine tuberculosis (bTB), caused by Mycobacterium bovis ( M. bovis ), remains an ongoing global issue for human and animal health. The Bacille Calmette Guerin (BCG) vaccine offers immunity against bTB, however, the mechanisms underlying the heterogenous protective response, including variations across species and age groups requires further investigation. In this study, we focused on dendritic cells (DCs), which are crucial for adaptive immune stimulation following BCG vaccination. By capturing afferent lymph DCs (ALDCs) migrating from the skin, we investigated shifts in DC profiles and potential subset-specific functions in response to BCG vaccination. Single-cell RNA sequencing (scRNA-seq) was performed on samples from Bos taurus calves (n=3) before and after BCG vaccination, capturing the transcriptome of 20,761 individual cells expressing on average 3,036 genes, which were clustered into ALDCs, monocytes, T-cells, B-cells and NK cells. The ALDC subsets were further identified as cDC1 and cDC2. In homeostasis, ALDCs expressing potential subset-specific genes for cDC1, including ENSBTAG00000056208, STX4 , NEBL , ADAM23 , ART3 , and cDC2; FN1 , PSPH , FGL2 , SHOX2 , and WWTR1 were identified. Following BCG vaccination, while both DC subsets exhibited gene expression signatures indicative of antigen-presenting function, migration, and DC maturation, cDC1 showed upregulation of genes consistent with metabolic alterations and lymphocyte recruitment, whereas cDC2 upregulated genes consistent with inflammatory responses. Overall, this study comprehensively describes the transcriptomic landscape of bovine ALDC subsets, providing evidence for the importance of subset-specific genes to BCG vaccination responses, while advancing knowledge on how ALDCs contribute to protective immunity against bTB.

We hypothesized that the addition of toceranib to metronomic cyclophosphamide/piroxicam therapy would significantly improve disease-free interval (DFI) and overall survival (OS) in dogs with appendicular osteosarcoma (OSA) following amputation and carboplatin chemotherapy. This was a randomized, prospective clinical trial in which dogs with OSA free of gross metastatic disease (n = 126) received carboplatin chemotherapy (4 doses) following amputation. On study entry, dogs were randomized to receive piroxicam/cyclophosphamide with or without toceranib (n = 63 each) after completing chemotherapy. Patient demographics were not significantly different between both groups. During or immediately following carboplatin chemotherapy, 32 dogs (n = 13 toceranib; n = 19 control) developed metastatic disease, and 13 dogs left the study due to other medical conditions or owner preference. Following carboplatin chemotherapy, 81 dogs (n = 46 toceranib; n = 35 control) received the metronomic treatment; 35 dogs (n = 20 toceranib; n = 15 control) developed metastatic disease during the maintenance therapy, and 26 dogs left the study due to other medical conditions or owner preference. Nine toceranib-treated and 11 control dogs completed the study without evidence of metastatic disease 1-year following amputation. Toceranib-treated dogs experienced more episodes of diarrhea, neutropenia and weight loss than control dogs, although these toxicities were low-grade and typically resolved with supportive care. More toceranib-treated dogs (n = 8) were removed from the study for therapy-associated adverse events compared to control dogs (n = 1). The median DFI for control and toceranib treated dogs was 215 and 233 days, respectively (p = 0.274); the median OS for control and toceranib treated dogs was 242 and 318 days, respectively (p = 0.08). The one year survival rate for control dogs was 35% compared to 38% for dogs receiving toceranib. The addition of toceranib to metronomic piroxicam/cyclophosphamide therapy following amputation and carboplatin chemotherapy did not improve median DFI, OS or the 1-year survival rate in dogs with OSA.

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne's disease, a chronic enteritis that has a damaging economic and welfare impact on the livestock industry. Johne's disease in cattle is known to reduce milk yield and carcass value, making it of economic concern to both dairy and beef farmers. In addition, there is cause for concern regarding zoonotic transmission, as there is an unconfirmed but potential relationship between MAP infection and human Crohn's disease, which presents similar clinical symptoms. MAP is most often contracted by neonates through the faecal-oral route, but can also be spread through contact with contaminated milk and colostrum, as well as in utero. Once the host receives an oral dose, the bacteria traverse the gut epithelium and are phagocytosed by gut macrophages residing in the lamina propria and Peyer's patches. MAP are able to evade the macrophage response by resisting intracellular degradation within phagosomes. Infected macrophages respond to the infection by secreting several pro-inflammatory cytokines that drive the downstream immune response and granuloma formation. This work aimed to elucidate key early responses of bovine monocyte derived macrophages (MDM) to MAP infection, and determine the reliability of using the reference strain, K10 (which is likely to have undergone lab adaptation) to model the infection in vitro, by comparing the MDM response to K10 with the response to a recent clinical isolate, C49. At a multiplicity of infection of 5 (MOI 5), there was a significant decrease in K10 intracellular survival (~90%), compared to C49 intracellular survival, over a 24 hour infection time-course. This suggests that K10 may have lost some virulence mechanism through lab adaptation. Understanding the mechanisms of how MDM respond to these two strains could be informative for the design of targeted vaccines When further investigating the MDM response to both strains, it was found that, at MOI 5, MDM infected with K10 secreted higher levels of IL-1β and IL-10, compared to MDM infected with C49. Both cytokines are associated with mycobacterial infection and could perhaps indicate that MDM are more responsive to the K10 strain at early time-points. In addition, MDM infected with K10 produced significantly higher levels of reactive nitrogen species (RNS). RNS are antimicrobial products that can destroy invading pathogens, and have been shown to have bactericidal effects on MAP. The production of RNS could, therefore be a potential mechanism by which MDM are able to kill K10 more efficiently than C49. An additional aim of this project was to understand the importance of the route of phagocytosis in determining the outcome of MAP infection. MDM express several phagocytic receptors, including Fc receptors (FcRs), complement receptors (CR), Ctype lectin receptors and scavenger receptors. This project mainly focused on the role of the mannose receptor (MR) on bacterial uptake and downstream immune responses, as past studies have suggested that other species of mycobacteria such as M. tuberculosis, target the mannose receptor in order to regulate macrophage immune responses. Blocking the MR reduced intracellular survival for both strains of MAP; however, the mechanism by which the MR influences intracellular survival remains poorly understood The effect of opsonisation on MAP prior to uptake by phagocytic cells was also investigated, as presence of opsonins, such a complement proteins and antibody, can change the mechanism by which pathogens are phagocytosed. MAP were incubated in serum from either MAP- negative or MAP- positive cattle, prior to infection and the percentage uptake and survival assessed by performing colony counts. Opsonisation in serum from Johne's negative cattle resulted in marked increase in MAP uptake but not intracellular survival, whereas opsonisation in serum from Johne's positive cattle did not increase uptake but decreased the intracellular survival rate by 24 HPI. This finding highlights a potential protective role of antibody early in the infection process, and could significantly impact how the infection is modelled in future, as anti-MAP antibody may be present in contaminated milk at the point of infection. Taken together, the data presented in this thesis show that bacterial strain has a significant impact on MDM response to MAP infection, which may have important implications for the interpretation of previous studies and the design of future studies investigating host-pathogen interactions in the context of paratuberculosis. Additionally, this work has shown that RNS production and the mechanism of uptake can affect intracellular survival rates, and although this needs further investigation, the findings could have implications for the design of future vaccines.

Background Public involvement in research on sensitive subjects, such as death and dying, can help to ensure that questions are framed to reflect the interests of their peers, develop a shared understanding of issues raised, and moderate the often unequal power relationship between researcher and participant. This paper describes the contribution and impact of older members of a Public Involvement in Research group (PIRg) to a study on living and dying in care homes. Methods A longitudinal study, with a mixed method approach, its aims were to capture key experiences, events and change over one year, of older people resident in participating care homes in the East of England. Residents were interviewed up to three times and their case notes were reviewed four times over the year. Interviews were semi structured, and recorded. Four members of a Public Involvement in Research group (PIRg) contributed to preliminary discussions about the research and three were involved with many of the subsequent stages of the research process including the facilitation of discussion groups with residents. Results There were three areas where the involvement of the Public Involvement in Research group (PIRg) positively influenced the study process. These were recruitment, governance and safeguarding, and in collaboration with the residents in the care homes, the discussion and interpretation of emergent findings. PIRg members were of similar age to the residents and their involvement provided different and often more reflective insights of the significance of the findings for the participants. There were examples where decision making about the range of PIRg participation was not always negotiable, and this raised issues about power relationships within the team. Nevertheless, PIRg members expressed personal benefit and satisfaction through participating in the research and a commitment to continue to support research with this older age group. Conclusions The contribution of the PIRg supported a successful recruitment process that exceeded response rates of other studies in care homes. It safeguarded residents during the conduct of research on a sensitive topic and helped in validating the interview data gathered by the researchers through the discussion groups facilitated by the PIRg. There were power differentials that persisted and affected PIRg participation. The study has showed the value of developing job descriptions and a more formal means of setting out respective expectations. Future research may wish to elicit the views of focal participants in such studies about the mediation of research by public involvement in research.

Background We hypothesized that the addition of toceranib to metronomic cyclophosphamide/piroxicam therapy would significantly improve disease-free interval (DFI) and overall survival (OS) in dogs with appendicular osteosarcoma (OSA) following amputation and carboplatin chemotherapy. Methods and Findings This was a randomized, prospective clinical trial in which dogs with OSA free of gross metastatic disease (n = 126) received carboplatin chemotherapy (4 doses) following amputation. On study entry, dogs were randomized to receive piroxicam/cyclophosphamide with or without toceranib (n = 63 each) after completing chemotherapy. Patient demographics were not significantly different between both groups. During or immediately following carboplatin chemotherapy, 32 dogs (n = 13 toceranib; n = 19 control) developed metastatic disease, and 13 dogs left the study due to other medical conditions or owner preference. Following carboplatin chemotherapy, 81 dogs (n = 46 toceranib; n = 35 control) received the metronomic treatment; 35 dogs (n = 20 toceranib; n = 15 control) developed metastatic disease during the maintenance therapy, and 26 dogs left the study due to other medical conditions or owner preference. Nine toceranib-treated and 11 control dogs completed the study without evidence of metastatic disease 1-year following amputation. Toceranib-treated dogs experienced more episodes of diarrhea, neutropenia and weight loss than control dogs, although these toxicities were low-grade and typically resolved with supportive care. More toceranib-treated dogs (n = 8) were removed from the study for therapy-associated adverse events compared to control dogs (n = 1). The median DFI for control and toceranib treated dogs was 215 and 233 days, respectively (p = 0.274); the median OS for control and toceranib treated dogs was 242 and 318 days, respectively (p = 0.08). The one year survival rate for control dogs was 35% compared to 38% for dogs receiving toceranib. Conclusions The addition of toceranib to metronomic piroxicam/cyclophosphamide therapy following amputation and carboplatin chemotherapy did not improve median DFI, OS or the 1-year survival rate in dogs with OSA.

CCR1, CCR2 and CCR5 direct recruitment of monocytes and macrophages in inflammation. However, the discrete role for each receptor in monocyte/macrophage biology remains poorly understood, with previous reports citing receptor redundancy. Using transcriptomic approaches to examine inflammatory chemokine receptor expression on lung interstitial macrophage populations, we demonstrate that interstitial macrophages can be divided into three distinct subsets, each of which express specific patterns of chemokine receptors, and that there are dynamic changes in chemokine receptor expression as macrophages differentiate from monocytes in the lung. Furthermore, macrophages expressing different combinations of chemokine receptors are transcriptionally distinct, suggesting non-redundant functions for CCR1, 2 and 5. Finally, we examined changes in macrophage chemokine receptor expression in vitro after treatment with varied TLR ligands, and show that CCR1 is specifically increased in response to bacterial but not viral ligands. Our data provide compelling evidence that macrophage chemokine receptor expression is not redundant, but specific and malleable in response to discrete inflammatory stimuli.

Inflammatory chemokine receptors CCR1/2/3/5 (iCCRs) play an important role in the recruitment of immune cells involved in innate immune functions and orchestrating the adaptive immune response. Here we utilise an influenza A virus (IAV) challenge to investigate the combinatorial roles of the iCCRs in the anti-IAV immune response. We did not observe any gross differences in infection-driven pathology in the absence of iCCRs. Despite iCCR deletion resulting in decreased migration of monocytes, migratory macrophages and B cells to lungs during acute IAV infection, no differences in dendritic cell numbers were observed. Whilst the total number of T cells was similar in lungs of iCCR-deficient mice, the number of IAV-specific CD4 but not CD8 T cells in the lung was strongly reduced in the absence of iCCRs. Furthermore, fewer CD4, but not CD8, T cells produced IFN-γ. This CD4 T cell phenotype persisted into the memory stage of infection, with fewer IAV-specific and IFN-γ+ CD4 but not CD8 T cells at 29 days post infection. In conclusion, despite having no impact on dendritic cell migration between the lung and the draining lymph node, iCCR deletion is associated with an altered CD4 T cell response to IAV infection.

Chemokine receptors control cell migration within the body. Here we reveal a novel interaction between eosinophils and monocytes in the bone marrow, indirectly controlled by the atypical chemokine receptor ACKR2. We demonstrate that ACKR2 maintains eosinophil levels within the bone marrow by scavenging CCL11. In the absence of ACKR2, elevated CCL11 leads to increased egress of eosinophils from the bone marrow into the bloodstream. As a result, eosinophil and monocyte interactions are reduced within the bone marrow niche, leading to changes in monocyte gene expression. Monocytes from ACKR2-/- mice are recruited to the tissues but are fundamentally altered in their ability to differentiate into macrophages, in the lung, peritoneal cavity and cavity wall. Bacterial elimination is impaired in ACKR2-/- mice during peritoneal infection. ACKR2 is therefore a key regulator of eosinophil-driven monocyte education in the bone marrow, required for full monocyte differentiation and macrophage function within the tissues.Competing Interest StatementThe authors have declared no competing interest.