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35 result(s) for "Koleva, Petya T."
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Human Milk From Atopic Mothers Has Lower Levels of Short Chain Fatty Acids
Short chain fatty acids (SFCAs) are microbial metabolites produced in the gut upon fermentation of dietary fiber. These metabolites interact with the host immune system and can elicit epigenetic effects. There is evidence to suggest that SCFAs may play a role in the developmental programming of immune disorders and obesity, though evidence in humans remains sparse. Here we have quantified human milk (HM) SCFA levels in an international cohort of atopic and non-atopic mothers ( = 109). Our results demonstrate that human milk contains detectable levels of the SCFAs acetate, butyrate, and formate. Samples from atopic mothers had significantly lower concentrations of acetate and butyrate than those of non-atopic mothers. HM SCFA levels in atopic and non-atopic women also varied based on maternal country of residence (Australia, Japan, Norway, South Africa, USA). Reduced exposure to HM SCFA in early life may program atopy or overweight risk in breastfed infants.
Inulin and fructo-oligosaccharides have divergent effects on colitis and commensal microbiota in HLA-B27 transgenic rats
Modulation of intestinal microbiota by non-digestible carbohydrates may reduce inflammation in inflammatory bowel disease (IBD). The aim of the present study was to assess the effects of inulin and fructo-oligosaccharides (FOS) on intestinal microbiota and colitis in HLA-B27 transgenic rats, a well-validated rodent model for IBD. In this study, 4-week-old rats were fed 8 g/kg body weight inulin or FOS for 12 weeks, or not. Faeces were collected at 4 and 16 weeks of age; and caecal samples were collected at necropsy. The effects of inulin and FOS on chronic intestinal inflammation were assessed using a gross gut score, histology score and levels of mucosal IL-1β. Intestinal microbiota were characterised by quantitative PCR and denaturing gradient gel electrophoresis. Colitis was significantly reduced in all FOS-fed rats compared to the control diet, whereas inulin decreased chronic intestinal inflammation in only half the number of animals. Quantitative analysis of caecal microbiota demonstrated that inulin increased the numbers of total bacteria and the Bacteroides-Prevotella-Porphyromonas group, FOS increased bifidobacteria, and both fructans decreased Clostridium cluster XI. In the faecal samples, both inulin and FOS decreased total bacteria, Bacteroides-Prevotella-Porphyromonas group, and Clostridium clusters XI and XIVa. FOS increased Bifidobacterium spp., and mediated a decrease of gene copies of Enterobacteriaceae and Clostridium difficile toxin B in faeces. SCFA concentrations in the faecal and caecal samples were unaffected by the diets. In conclusion, FOS increased the abundance of Bifidobacterium spp., whereas both fructans reduced Clostridium cluster XI and C. difficile toxin gene expression, correlating with a reduction of chronic intestinal inflammation.
Worldwide Variation in Human Milk Metabolome: Indicators of Breast Physiology and Maternal Lifestyle?
Human milk provides essential substrates for the optimal growth and development of a breastfed infant. Besides providing nutrients to the infant, human milk also contains metabolites which form an intricate system between maternal lifestyle, such as the mother’s diet and the gut microbiome, and infant outcomes. This study investigates the variation of these human milk metabolites from five different countries. Human milk samples (n = 109) were collected one month postpartum from Australia, Japan, the USA, Norway, and South Africa and were analyzed by nuclear magnetic resonance. The partial least squares discriminant analysis (PLS-DA) showed separation between either maternal countries of origin or ethnicities. Variation between countries in concentration of metabolites, such as 2-oxoglutarate, creatine, and glutamine, in human milk, between countries, could provide insights into problems, such as mastitis and/or impaired functions of the mammary glands. Several important markers of milk production, such as lactose, betaine, creatine, glutamate, and glutamine, showed good correlation between each metabolite. This work highlights the importance of milk metabolites with respect to maternal lifestyle and the environment, and also provides the framework for future breastfeeding and microbiome studies in a global context.
The Infant Gut Microbiome: Evidence for Obesity Risk and Dietary Intervention
Increasing globally, particularly in children, obesity is a serious public health issue and risk factor for overweight and metabolic disease in later life. Both in experimental animal and human studies, advances in gene sequencing technologies have yielded intriguing possibilities for the role of the gut microbiome in later development of overweight status. Before translating study findings into practice, we must first reconcile inconsistencies between animal experimentation, and human adult and infant studies. Recent evidence for associations with gut microbiota and infant weight gain or child weight status, implicate Bacteroides and Lactobacillus species. Dietary manipulation with human milk and pre/probiotic formulations holds promise for preventing obesity.
Towards the Development of an Empirical Model for Islamic Corporate Social Responsibility: Evidence from the Middle East
Academic research suggests that variances in contextual dynamics, and more specifically religion, may lead to disparate perceptions and practices of corporate social responsibility (CSR). Driven by the increased geopolitical and economic importance of the Middle East and identified gaps in knowledge, the study aims to examine if indeed there is a divergent form of CSR exercised in the region. The study identifies unique CSR dimensions and constructs presented through an empirical framework in order to outline the practice and perception of CSR in a context with strong Islamic beliefs. The framework goes beyond the platform of mere Islamic philanthropy and is based on CSR-stakeholder management practices. Following an exploratory research design and collecting interview data from representatives of 63 organisations from Saudi Arabia, the United Arab Emirates and Oman, the study offers a snapshot of the CSR reality from the perspective of those living the phenomenon. The results suggest that the practice and perception of CSR in the examined context are largely grounded in the areas of social and altruistic actions but they cannot be examined in isolation from the religious context of CSR operation. This focus is mainly attributed to the dominant role of Islam in the examined sample, which leads to forms of non-structured or semi-structured approaches to CSR. Apart from the theoretical advancements offered to the CSR literature, the study also provides contributions for practitioners and policy makers.
Inherited Scepticism and Neo-communist CSR-washing: Evidence from a Post-communist Society
The sizeable theoretical and empirical literature on corporate social responsibility (CSR) and business ethics in Western, developed economies indicates that the topic has attracted significant interest from academics and practitioners. There is, however, less evidence of the practice of CSR and business ethics in non-Western, transition economies, as insufficient attention is paid to the contextual specifications and underlying processes that may lead to different versions of CSR. Therefore, this paper examines the practice and sense-making of CSR and business ethics from the perspective of the fertile and under researched post-communist context of Central and Eastern Europe (CEE), to join the growing academic debate about the impact of cultural and historical traditions on the practice and sense-making of CSR and business ethics in non-Western contexts. The study adopts a particular focus on the post-communist and under researched context of Bulgaria where CSR is still a relatively new phenomenon. By following an exploratory research design and by collecting qualitative data from 34 executives employed by public and private sector organisations in Bulgaria, the study finds that the local business environment is composed of a complex mix of various institutionalised pressures and challenges that predispose organisations to adopt a particular approach to CSR, ethical misconduct and CSR-washing. Apart from the significant contributions related to the practice, understanding and contextualisation of CSR in non-Western countries, the study also identifies challenges of business ethics in transition economies and adds depth to the emerging literature on CSR-washing by proposing a model for neo-communist CSR-washing. The study also offers contributions for practitioners and policy-makers.
Critical analysis of grounded theory strategy in organisational and management research
PurposeAlthough grounded theory (GT) was introduced in 1967, GT remains widely misunderstood as scholars incorporate a limited spectrum of the GT techniques and fail to integrate GT's full potential into academic research. The purpose of this article is, therefore, to discuss divergences between four GT strategies and by doing so to provide criteria for making an informed choice between one GT approach or another.Design/methodology/approachThe study offers a comparative analysis of four GT approaches by relying on a recently completed empirical work focused on the practice and perception of corporate social responsibility (CSR) in non-Western context conducted by the author.FindingsAs a result, the study outlines the main points of divergence between the four GT strategies and discusses how their differences impact the research outcomes, theoretical products and application of the proposed theories in organisational and management research.Research limitations/implicationsAs a result of the comparative analysis, the study will help researchers make an informed choice when selecting one GT approach or another.Originality/valueThe study demonstrates the potential of GT in organisational and management research by utilising a practical example of GT's implementation from a recently completed empirical study.
CD71+VISTA+ erythroid cells promote the development and function of regulatory T cells through TGF-β
Cell-surface transferrin receptor (CD71+) erythroid cells are abundant in newborns with immunomodulatory properties. Here, we show that neonatal CD71+ erythroid cells express significant levels of V-domain Immunoglobulin (Ig) Suppressor of T Cell Activation (VISTA) and, via constitutive production of transforming growth factor (TGF)- β, play a pivotal role in promotion of naïve CD4+ T cells into regulatory T cells (Tregs). Interestingly, we discovered that CD71+VISTA+ erythroid cells produce significantly higher levels of TGF-β compared to CD71+VISTA- erythroid cells and CD71+ erythroid cells from the VISTA knock-out (KO) mice. As a result, CD71+VISTA+ erythroid cells-compared to CD71+VISTA- and CD71+ erythroid cells from the VISTA KO mice-significantly exceed promotion of naïve CD4+ T cells into induced Tregs (iTreg) via TGF-β in vitro. However, depletion of CD71+ erythroid cells had no significant effects on the frequency of Tregs in vivo. Surprisingly, we observed that the remaining and/or newly generated CD71+ erythroid cells following anti-CD71 antibody administration exhibit a different gene expression profile, evidenced by the up-regulation of VISTA, TGF-β1, TGF-β2, and program death ligand-1 (PDL-1), which may account as a compensatory mechanism for the maintenance of Treg population. We also observed that iTreg development by CD71+ erythroid cells is mediated through the inhibition of key signaling molecules phosphorylated protein kinase B (phospho-Akt) and phosphorylated mechanistic target of rapamycin (phospho-mTOR). Finally, we found that elimination of Tregs using forkhead box P3 (FOXP3)-diptheria toxin receptor (DTR) mice resulted in a significant expansion in the frequency of CD71+ erythroid cells in vivo. Collectively, these studies provide a novel, to our knowledge, insight into the cross-talk between CD71+ erythroid cells and Tregs in newborns. Our results highlight the biological role of CD71+ erythroid cells in the neonatal period and possibly beyond.
CD71+ erythroid suppressor cells impair adaptive immunity against Bordetella pertussis
Infant’s immune system cannot control infection or respond to vaccination as efficiently as older individuals, a phenomenon that has been attributed to immunological immaturity. Recently, we challenged this notion and proposed the presence of actively immunosuppressive and physiologically enriched CD71 + erythroid cells in neonates. Here we utilized Bordetella pertussis , a common neonatal respiratory tract pathogen, as a proof of concept to investigate the role of these cells in adaptive immunity. We observed that CD71 + cells have distinctive immunosuppressive properties and prevent recruitment of immune cells to the mucosal site of infection. CD71 + cells ablation unleashed induction of B. pertussis -specific protective cytokines (IL-17 and IFN-γ) in the lungs and spleen upon re-infection or vaccination. We also found that CD71 + cells suppress systemic and mucosal B. pertussis -specific antibody responses. Enhanced antigen-specific adaptive immunity following CD71 + cells depletion increased resistance of mice to B. pertussis infection. Furthermore, we found that human cord blood CD71 + cells also suppress T and B cell functions in vitro . Collectively, these data provide important insight into the role of CD71 + erythroid cells in adaptive immunity. We anticipate our results will spark renewed investigation in modulating the function of these cells to enhance host defense to infections in newborns.