Tumor necrosis factor (TNF)-α is a proinflammatory cytokine that mediates inflammation in response to various pathogens, including Mycobacterium tuberculosis, but is also a key factor in the ...pathogenesis of rheumatoid arthritis and other autoimmune diseases. Three TNF-α-suppressing drugs have been approved to treat selected autoimmune diseases; 2 are monoclonal antibodies against TNF-α (adalimumab and infliximab), and the other is a soluble TNF receptor/Fc fusion protein (etanercept). TNF blockers have been shown to increase the risk of reactivation of latent tuberculosis, and this risk is higher in patients treated with the monoclonal antibodies. We studied the effects of TNF-α blockers on the maturation of mycobacteria-containing phagosomes in human macrophages. All 3 drugs had an inhibitory effect on IFN-γ-induced phagosome maturation in phorbolmyristate acetate-differentiated human THP-1 cells. Adalimumab and infliximab, but not etanercept, suppressed phagosome maturation in primary human peripheral blood monocyte-derived macrophages in the presence or absence of IFN-γ. Treatment of macrophages with TNF-α led to increased maturation of phagosomes containing Mycobacterium bovis bacillus Calmette-Guérin or M. tuberculosis H37Rv. These results suggest a role for TNF-α in activating phagosome maturation and highlight a mechanism through which TNF-α blockade can affect the host response to mycobacteria.
Animal African trypanosomiasis (AAT), caused by Trypanosoma congolense and Trypanosoma vivax , remains one of the most important livestock diseases in sub-Saharan Africa, particularly affecting ...cattle. Despite this, our detailed knowledge largely stems from the human pathogen Trypanosoma brucei and mouse experimental models. In the postgenomic era, the genotypic and phenotypic differences between the AAT-relevant species of parasite or host and their model organism counterparts are increasingly apparent. Here, we outline the timeliness and advantages of increasing the research focus on both the clinically relevant parasite and host species, given that improved tools and resources for both have been developed in recent years. We propose that this shift of emphasis will improve our ability to efficiently develop tools to combat AAT.
Gastrointestinal disease caused by the apicomplexan parasite Cryptosporidium parvum is one of the most important diseases of young ruminant livestock, particularly neonatal calves. Infected animals ...may suffer from profuse watery diarrhoea, dehydration and in severe cases death can occur. At present, effective therapeutic and preventative measures are not available and a better understanding of the host-pathogen interactions is required. Cryptosporidium parvum is also an important zoonotic pathogen causing severe disease in people, with young children being particularly vulnerable. Our knowledge of the immune responses induced by Cryptosporidium parasites in clinically relevant hosts is very limited. This review discusses the impact of bovine cryptosporidiosis and describes how a thorough understanding of the host-pathogen interactions may help to identify novel prevention and control strategies.
Abstract Bovine alveolar macrophages (AMs) defend the lungs against pathogens such as Mycobacterium bovis ( M. bovis) , the causative agent of bovine tuberculosis. However, little is known about the ...surface molecules expressed by bovine AMs and whether there is heterogeneity within the population. The purpose of this study was to characterise the bovine AM cell surface phenotype using flow cytometry. Bronchoalveolar lavage samples from four different calves were stained with a combination of antibodies against immune cell molecules prior to flow cytometric analysis. To assess the degree of expression, we considered the distribution and relative intensities of stained and unstained cells. We demonstrated that bovine AMs have high expression of CD172a, ADGRE1, CD206, and CD14, moderate expression of CD80, MHC II, CD1b, and CD40, low expression of CX3CR1 and CD86, and little or no expression of CD16 and CD26. Two distinct subsets of bovine AMs were identified based on CD163 expression. Subsequent analysis showed that the CD163 + subset had greater expression of other typical macrophage molecules compared to the CD163 - subset, suggesting that these cells may perform different roles during infection. The characterisation of the uninfected bovine AM phenotype will provide a foundation for the examination of M. bovis- infected AMs.
The F4/80 antigen, encoded by the
locus, has been widely-used as a monocyte-macrophage marker in mice, but its value as a macrophage marker in other species is unclear, and has even been questioned. ...ADGRE1 is a seven transmembrane G protein-coupled receptor with an extracellular domain containing repeated Epidermal Growth Factor (EGF)-like calcium binding domains. Using a new monoclonal antibody, we demonstrated that ADGRE1 is a myeloid differentiation marker in pigs, absent from progenitors in bone marrow, highly-expressed in mature granulocytes, monocytes, and tissue macrophages and induced by macrophage colony-stimulating factor (CSF1) treatment
. Based upon these observations, we utilized RNA-Seq to assess the expression of
mRNA in bone marrow or monocyte-derived macrophages (MDM) and alveolar macrophages from 8 mammalian species including pig, human, rat, sheep, goat, cow, water buffalo, and horse.
mRNA was expressed by macrophages in each species, with inter-species variation both in expression level and response to lipopolysaccharide (LPS) stimulation. Analysis of the RNA-Seq data also revealed additional exons in several species compared to current Ensembl annotations. The ruminant species and horses appear to encode a complete duplication of the 7 EGF-like domains. In every species, Sashimi plots revealed evidence of exon skipping of the EGF-like domains, which are highly-variable between species and polymorphic in humans. Consistent with these expression patterns, key elements of the promoter and a putative enhancer are also conserved across all species. The rapid evolution of this molecule and related ADGRE family members suggests immune selection and a role in pathogen recognition.
Leptospira serovar Hardjo are bacterial pathogens of cattle that also cause zoonotic disease in humans. Vaccine-mediated protection against Leptospira serovar Hardjo in cattle is associated with a ...workshop cluster 1 (WC1)+ γδ T cell response that can be recalled in vitro from PBMC by antigenic stimulation. This provides a model system in which to examine protective vaccine-induced γδ T cell responses in a γδ T cell high species. Only a small proportion (5-10%) of WC1+ γδ T cells from immunized cattle are Leptospira responders, implying that Ag specificity is determined by clonally distributed receptors. Both WC1 and TCR are known to be required for Leptospira-specific responses by bovine WC1+ γδ T cells. Through variegated expression patterns and V(D)J recombination, respectively, they have the capacity to confer Ag specificity. In this study, we develop and use a high-throughput TCR-sequencing approach to study the TCRγ and TCRδ repertoires of naive ex vivo PBMC, Leptospira-responding, and Leptospira nonresponding WC1+ γδ T cells to examine the potential role of γδ TCR in determining Ag specificity. Our results provide novel insights into the PBMC γδ TCR repertoires in cattle, demonstrating the TCRγ repertoire to be clonally stratified and essentially public, whereas the TCRδ repertoire shows much higher levels of clonal diversity and is essentially private. TCR repertoire analysis of Leptospira-responding WC1+ γδ T cells identifies no signature of TCR-mediated selection, suggesting that TCR functions largely as an innate-like receptor and does not act as a primary determinant of Ag specificity in the response to this pathogen.
Salmonella enterica is a veterinary and zoonotic pathogen of global importance. While murine and cell-based models of infection have provided considerable knowledge about the molecular basis of ...virulence of Salmonella, relatively little is known about salmonellosis in naturally-affected large animal hosts such as cattle, which are a reservoir of human salmonellosis. As in humans, Salmonella causes bovine disease ranging from self-limiting enteritis to systemic typhoid-like disease and exerts significant economic and welfare costs. Understanding the nature and consequences of Salmonella interactions with bovine cells will inform the design of effective vaccines and interventions to control animal and zoonotic infections. In calves challenged orally with S. Dublin expressing green fluorescent protein (GFP) we observed that the bacteria were predominantly extracellular in the distal ileal mucosa and within gut-associated lymph nodes 48 h post-infection. Intracellular bacteria, identified by flow cytometry using the GFP signal, were predominantly within MHCII
macrophage-like cells. In contrast to observations from murine models, these S. Dublin-infected cells had elevated levels of MHCII and CD40 compared to both uninfected cells from the same tissue and cells from the cognate tissue of uninfected animals. Moreover, no gross changes of the architecture of infected lymph nodes were observed as was described previously in a mouse model. In order to further investigate Salmonella-macrophage interactions, net replication of S. enterica serovars that differ in virulence in cattle was measured in bovine blood-derived macrophages by enumeration of gentamicin-protected bacteria and fluorescence dilution, but did not correlate with host-specificity.
Cases of canine tuberculosis, a zoonotic infection of significant public health significance, are typically only sporadically reported in the literature. For this observational study, case details ...were collated both retrospectively and prospectively for dogs infected with Mycobacterium tuberculosis-complex (MTBC) organisms. A total of 18 previously unreported cases as well as 565 historically reported confirmed cases were reviewed. A variety of diagnostic techniques were used to make a confirmed diagnosis of tuberculosis (culture, interferon-gamma release assay IGRA, and PCR). The reference standard for diagnosis is culture; however, this was negative or not attempted in some dogs. Where fully speciated, all cases were caused by infection with one of three MTBC organisms: M. tuberculosis, Mycobacterium bovis, or Mycobacterium microti. This study includes the first documented canine infections with M. microti in the UK. All cases were assigned to one of four clinical groups based on the presenting signs: 44.1% were primarily pulmonary, 14.5% were primarily abdominal, and the remainder were disseminated or miscellaneous. The development of adjunctive tests remains necessary to support early treatment decisions pending reporting of culture for MTBC organisms, which can take weeks to months. Definitive treatment, where attempted, was successful in most cases. Of the 13 dogs treated by the authors with triple combination antimicrobial therapy, a good clinical outcome was seen in 12 (92%) of them.
•Signalment and presentation of nearly 600 cases of canine tuberculosis are reviewed•This is the first description of Mycobacterium microti in UK-based dogs•M. tuberculosis and M. bovis infections are most frequently confirmed•Clinical signs are often vague and chronic with a rapid terminal decline•Outcome of definitive treatment is excellent with careful case selection
A central community annotated database and website have been created to share reagent information and facilitate the study of veterinary species. It is hoped that with continued community engagement, ...https://www.immunologicaltoolbox.co.uk/ will promote the use of the most informative animal models, maximizing the enormous potential of comparative immunological studies.
Summary
Using the best animal models to study immune responses against specific pathogens or vaccines can dramatically accelerate our understanding. Veterinary species are well studied, particularly livestock, to reduce their disease burden. They have also proven to be powerful models, especially for zoonotic pathogens and novel vaccination strategies. A prerequisite for any model selection is having the right quality and range of species‐specific immunological reagents. To help promote the widest possible use of veterinary species, an open access website (https://www.immunologicaltoolbox.co.uk) has been created as a central community annotated hub for veterinary immunological reagents. The website is also the portal into services offered by the UK Immunological Toolbox project that includes antibody generation, sequencing and recombinant expression. The funding for this effort is linked into sustainable sources, but ultimate success relies on community engagement to continually increase the quality and quantity of information. It is hoped that as more users and reagent owners engage, it will become an essential resource for researchers, veterinarians and clinicians alike by removing barriers that prevent the use of the most informative animal models.
Macrophage colony-stimulating factor (CSF1) controls the proliferation and differentiation of cells of the mononuclear phagocyte system through binding to the receptor CSF1R. The expression and ...function of CSF1 has been well-studied in rodents and humans, but knowledge is lacking in other veterinary species. The development of a novel mouse anti-porcine CSF1 monoclonal antibody (mAb) facilitates the characterisation of this growth factor in pigs. Cell surface expression of CSF1 was confirmed on differentiated macrophage populations derived from blood and bone marrow monocytes, and on lung resident macrophages, the first species for this to be confirmed. However, monocytes isolated from blood and bone marrow lacked CSF1 expression. This species-specific mAb delivers the opportunity to further understanding of porcine myeloid cell biology. This is not only vital for the role of pigs as a model for human health, but also as a veterinary species of significant economic and agricultural importance.
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