[Show abstract][Hide abstract] ABSTRACT: Circulating monocytes in several mammalian species can be subdivided into functionally distinct subpopulations based on differential expression of surface molecules. We confirm that bovine monocytes express CD172a and MHC class II with two distinct populations of CD14 + CD16 low/- CD163 + and CD14 − CD16 ++ CD163 low- cells, and a more diffuse population of CD14 + CD16 + CD163 + cells. In contrast, ovine monocytes consisted of only a major CD14 + CD16 + subset and a very low percentage of CD14 − CD16 ++ cells. The bovine subsets expressed similar levels of CD80, CD40 and CD11c molecules and mRNA encoding CD115. However, further mRNA analyses revealed that the CD14 − CD16 ++ monocytes were CX3CR1 high CCR2 low whereas the major CD14 + subset was CX3CR1 low CCR2 high . The former were positive for CD1b and had lower levels of CD11b and CD86 than the CD14 + monocytes. The more diffuse CD14 + CD16 + population generally expressed intermediate levels of these molecules. All three populations responded to stimulation with phenol-extracted lipopolysaccharide (LPS) by producing interleukin (IL)-1β, with the CD16 ++ subset expressing higher levels of IL-12 and lower levels of IL-10. The CD14 − CD16 ++ cells were more endocytic and induced greater allogeneic T cell responses compared to the other monocyte populations. Taken together the data show both similarities and differences between the classical, intermediate and non-classical definitions of monocytes as described for other mammalian species, with additional potential subpopulations. Further functional analyses of these monocyte populations may help explain inter-animal and inter-species variations to infection, inflammation and vaccination in ruminant livestock.
Full-text · Article · Sep 2015 · Veterinary Research
[Show abstract][Hide abstract] ABSTRACT: Background:
Miscarriage is the spontaneous loss of a pregnancy before 12 weeks (early miscarriage) or from 12 to 24 weeks (late miscarriage) of gestation. Miscarriage occurs in one in five pregnancies and can have considerable physiological and psychological implications for the patient. It is also associated with significant health care costs. There is evidence that potentially preventable infections may account for up to 15% of early miscarriages and up to 66% of late miscarriages. However, the provision of associated screening and management algorithms is inconsistent for newly pregnant women. Here, we review recent population-based studies on infections that have been shown to be associated with miscarriage.
Our aim was to examine where the current scientific focus lies with regards to the role of infection in miscarriage. Papers dating from June 2009 with key words 'miscarriage' and 'infection' or 'infections' were identified in PubMed (292 and 327 papers, respectively, on 2 June 2014). Relevant human studies (meta-analyses, case-control studies, cohort studies or case series) were included. Single case reports were excluded. The studies were scored based on the Newcastle - Ottawa Quality Assessment Scale.
The association of systemic infections with malaria, brucellosis, cytomegalovirus and human immunodeficiency virus, dengue fever, influenza virus and of vaginal infection with bacterial vaginosis, with increased risk of miscarriage has been demonstrated. Q fever, adeno-associated virus, Bocavirus, Hepatitis C and Mycoplasma genitalium infections do not appear to affect pregnancy outcome. The effects of Chlamydia trachomatis, Toxoplasma gondii, human papillomavirus, herpes simplex virus, parvovirus B19, Hepatitis B and polyomavirus BK infections remain controversial, as some studies indicate increased miscarriage risk and others show no increased risk. The latest data on rubella and syphilis indicate increased antenatal screening worldwide and a decrease in the frequency of their reported associations with pregnancy failure. Though various pathogens have been associated with miscarriage, the mechanism(s) of infection-induced miscarriage are not yet fully elucidated.
Further research is required to clarify whether certain infections do increase miscarriage risk and whether screening of newly pregnant women for treatable infections would improve reproductive outcomes.
Full-text · Article · Sep 2015 · Human Reproduction Update
[Show abstract][Hide abstract] ABSTRACT: Animal models of human disease are important tools in many areas of biomedicine; for example, in infectious disease research and in the development of novel drugs and medical devices. Most studies involving animals use rodents, in particular congenic mice, due to the availability of a wide number of strains and the ease with which they can be genetically manipulated. The use of mouse models has led to major advances in many fields of research, in particular in immunology but despite these advances, no animal model can exactly reproduce all the features of human disease. It is increasingly becoming recognised that in many circumstances mice do not provide the best model and that alternative species may be more appropriate. Here, we describe the relative merits of sheep as biomedical models for human physiology and disease in comparison to mice, with a particular focus on reproductive and respiratory pathogens.
[Show abstract][Hide abstract] ABSTRACT: Latency is a key feature of the animal pathogen Chlamydia abortus, where infection remains inapparent in the non-pregnant animal and only becomes evident during a subsequent pregnancy. Often the first sign that an animal is infected is abortion occurring late in gestation. Despite this, little is understood of the underlying mechanisms that control latency or the recrudescence of infection that occurs during subsequent pregnancy. The aim of this study was to develop an experimental model of latency by mimicking the natural route of infection through the intranasal inoculation of non-pregnant sheep with C. abortus.
[Show abstract][Hide abstract] ABSTRACT: Despite the availability of effective management and treatment strategies, Chlamydia abortus remains the single most frequently diagnosed cause of infectious ovine abortion (enzootic abortion of ewes, EAE) in the UK and one of the most significant causes of lamb mortality world-wide. In 2007, a survey of UK farmers, veterinarians and other farm animal holders was conducted to gather information on their perceptions of the risk of acquiring infection and the management practices employed to control the disease. The survey indicated that the preferred options for controlling EAE are either through vaccination and/or keeping flocks closed. However, further analysis of data indicates that implementation of these strategies does not provide a guarantee of exclusion of disease from flocks and thus further work is required to improve on current intervention strategies.
Full-text · Article · Jul 2012 · The Veterinary Journal
[Show abstract][Hide abstract] ABSTRACT: The portfolio of reagents for immunology research in veterinary species is limited compared to those available for humans and model biomedical species such as mice. For example, we still lack the reagents to fully ascertain if the immunological paradigms relating to the development, function and inter-relationships between the major T helper cell subsets (Th1, Th2, Th17) apply in ruminants, including goats. Such reagents are essential for rational and strategic approaches to vaccine design based on the identification of correlates of protection. Although a number of human immunological reagents such as monoclonal antibodies (mAb) and cytokines have been shown to cross-react with the farmed ruminant species (cattle, sheep and goats), a greater degree of cross-reactivity is found for reagents specifically developed against ruminant species. Thus, for goats, the most likely sources of cross-reactive reagents are those made against cattle and sheep. Nevertheless, although high inter-species homologies are evident at the gene level in ruminants, cross-reactivity of mAb, cytokines and molecular probes cannot be guaranteed and reagents may have to be developed specifically. Here we review the current availability of immunological reagents for caprine immunology and how those reagents can be used to understand T cell biology.
No preview · Article · Mar 2012 · Small Ruminant Research
[Show abstract][Hide abstract] ABSTRACT: Ovine enzootic abortion (OEA) is caused by the obligate intracellular Gram-negative bacterium Chlamydia abortus. OEA remains a common cause of infectious abortion in many sheep-rearing countries despite the existence of commercially available vaccines that protect against the disease. There are a number of confounding factors that influence the uptake and use of these vaccines, which includes an inability to discriminate between infected and vaccinated animals (DIVA) using conventional serological diagnostic techniques. This suggests that the immunity elicited by current vaccines is similar to that observed in convalescent, immune sheep that have experienced OEA. The existence of these vaccines provides an opportunity to understand how protection against OEA is elicited and also to understand why vaccines can occasionally appear to fail, as has been reported recently for OEA. Interferon-gamma (IFN-γ), the cytokine that classically defines Th1-type adaptive immunity, is a strong correlate of protection against OEA in sheep and has been shown to inhibit the growth of C. abortus in vitro. Humoral immunity to C. abortus is observed in both vaccinated and naturally infected sheep, but antibody responses tend to be used more as diagnostic markers than targets for strategic vaccine design. A future successful DIVA vaccine against OEA should aim to elicit the immunological correlate of protection (IFN-γ) concomitantly with an antibody profile that is distinct from that of the natural infection. Such an approach requires careful selection of protective components of C. abortus combined with an effective delivery system that elicits IFN-γ-producing CD4+ve memory T cells.
Full-text · Article · Dec 2011 · Comparative immunology, microbiology and infectious diseases
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT: Neospora caninum is recognised worldwide as a major cause of bovine infectious abortion. There is a real need to develop effective strategies to control infection during pregnancy which may lead to either abortion or congenital transmission. Due to the intracellular nature of the parasite, cell-mediated immune (CMI) responses involving CD4+ve, CD8+ve, γ/δ TCR+ve T cells and NK cells, as well as production of IFN-γ, are thought to be important for protective immunity. In this study we applied a combination of proteomic and immunological approaches to identify antigens of N. caninum that are recognized by CD4+ve T cell lines derived from infected cattle. Initially, N. caninum tachyzoite Water Soluble Antigens (NcWSA) were fractionated by size-exclusion HPLC and then screened for immune-potency using CD4+ve T cell lines. LC-ESI-MS/MS (liquid chromatography electrospray ionisation tandem mass spectrometry) was employed to catalogue and identify the proteins comprising three immunologically selected fractions and led to the identification of six N. caninum target proteins as well as sixteen functional orthologues of Toxoplasma gondii. This approach allows the screening of biologically reactive antigenic fractions by the immune cells responsible for protection (such as bovine CD4+ve cells) and the subsequent identification of the stimulating components using tandem mass spectrometry.
Full-text · Article · Aug 2011 · Veterinary Research
[Show abstract][Hide abstract] ABSTRACT: Regulatory T cells (Treg) are an important subset of T lymphocytes which play a key role in maintaining peripheral immunological tolerance. The most studied subpopulation of Treg in mice and humans are natural Treg, which differentiate in the thymus and are identified by expression of CD4, high levels of IL-2Rα (CD25), and forkhead box P3 (Foxp3), a transcription factor intimately associated with Treg function. We and others have previously identified Foxp3(+) T cells in ovine tissue, suggesting that Treg exist in this species. However, the existence of putative natural Treg in sheep, as identified by co-expression of CD4, CD25 and Foxp3, has yet to be determined. In this study we demonstrate that the anti-rat/mouse Foxp3 monoclonal antibody FJK-16s cross-reacts with ovine Foxp3. Using a transfected Chinese hamster ovary cell line that constitutively expresses recombinant ovine Foxp3 as a positive control, we have developed a sensitive triple-labelling flow cytometry protocol to simultaneously label CD4, CD25 and Foxp3. We demonstrate that Foxp3(+) T lymphocytes exist in ovine peripheral blood, and that the majority of Foxp3 expression occurs within the CD4(+)CD25(hi) population. These results are consistent with those seen in other mammalian species and indicate that putative natural Treg exist in sheep.
No preview · Article · Jul 2011 · Veterinary Immunology and Immunopathology
[Show abstract][Hide abstract] ABSTRACT: The 3rd Veterinary Immunology Committee (VIC) Toolkit Workshop took place at the 9th International Veterinary Immunology Symposium (IVIS) in Tokyo, Japan on 18th August 2010. The Workshop built on previous Toolkit Workshops and covered various aspects of reagent development, commercialization and provision to the veterinary immunology research community. The emphasis was on open communication about current progress and future plans to avoid duplication of effort and to update priorities for reagent development. There were presentations on the major reagent development and networking projects such as the BBSRC/RERAD Immunological Toolbox (2004-2009), US Veterinary Immune Reagent Network (VIRN 2006-2010) that has just received renewal funding for 2010-2014, and EU Network for Animal Diseases Infectiology Research Facilities project (NADIR 2009-2013). There were also presentations and discussions on the use of reagents for assay development, particularly multiplexing, and how these new technologies will underpin basic research developments. Mechanisms for improved information exchange, especially though websites with VIC playing a central role, were identified.
No preview · Article · Mar 2011 · Veterinary Immunology and Immunopathology
[Show abstract][Hide abstract] ABSTRACT: Lymphoid and myeloid cell populations in human endometrium are well-documented and are known to play important roles in providing immune tolerance, controlling trophoblast invasion, and mediating vascular remodeling. Immune cell populations in the Fallopian tube have not been comprehensively studied. The aim of this study was to characterize lymphoid and myeloid cell populations in non-pregnant Fallopian tube and determine whether they are altered in Fallopian tube from women with ectopic pregnancy. Fallopian tube was analyzed by flow cytometry and immunohistochemistry. Populations of CD3+ (CD4+ and CD8+) lymphocytes, LIN1-HLADR+ (CD123+ and CD11c+) dendritic cells, monocytes, neutrophils, and CD56(dim)CD16- natural killer (NK) cells were demonstrated to be present in non-pregnant Fallopian tube. CD123+ dendritic cells were predominant over CD11c+ dendritic cells. Numbers of CD11c+ cells were significantly higher in the progesterone-dominant mid-luteal phase of the menstrual cycle compared with the follicular phase. Numbers of CD45+ leukocytes, CD68+ cells, and CD11c+ cells were higher in Fallopian tube from women with ectopic pregnancy compared with mid-luteal phase Fallopian tube. These data will advance our understanding of normal human Fallopian tube physiology and disorders of Fallopian tube function, such as ectopic pregnancy.
Full-text · Article · Mar 2011 · Journal of Reproductive Immunology
[Show abstract][Hide abstract] ABSTRACT: The aim is to review recent findings on immunity and vaccine development to Chlamydia trachomatis.
There is increasing knowledge on the interactions between C. trachomatis and infected host cells. During genital infection the organism avoids generating protective immunity but immune responses to a number of chlamydial proteins have been associated with reproductive tract pathology. Various vaccine and adjuvant preparations have been tried experimentally. Information generated by proteomics and complex studies of serological and T-lymphocyte immune responses points to novel vaccine candidates.
C. trachomatis, an obligate intracellular bacterium, is the commonest sexually transmitted infection worldwide and is associated with reproductive pathology. To develop rational vaccines it is necessary to understand the complex lifecycle of the organism, the host immune response to infection and how these relate to disease. Infection does not prevent re-infection and antibiotic treatment prevents antibody production at a population level. It remains unclear what type of immune response would be sufficient to prevent infection and/or re-infection. Although the prevalence and demographics of infection and the severity of disease associations suggest that it would be desirable, there is no vaccine currently available. A number of studies have identified novel vaccine candidates.
Full-text · Article · Feb 2011 · Current Opinion in Infectious Diseases