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Introduction: Chronic kidney disease (CKD) may affect the human microbiome via increased concentrations of uremic toxins such as urea and creatinine. Methods: We have profiled the oral microbiota in patients with CKD before and one week after kidney transplantation. Living kidney donors were also longitudinally tracked over a similar period, allowing direct comparison between a group undergoing transplant surgery alone (donors) (n=13) and a group additionally undergoing the introduction of immunosuppressive agents and the resolution of CKD (recipients) (n=45). Results: Transplantation was associated with a similar pattern of decreasing alpha diversity in the oral microbiome in recipients and donors via Kruskal-Wallis testing, within one week of transplantation. Amplicon sequence variants (ASVs) associated with Haemophilus parainfluenzae, Aggregatibacteria segnis, Peptostreptococcus and Actinobacillus were significantly decreased in recipients within a week of transplantation. Discussion: A reduction in ASVs in these genera could influence the risk of bacterial endocarditis, a rare but high-mortality kidney transplantation complication. A range of factors may drive the observed changes in oral microbiome including both factors associated with surgery itself and the decreases in salivary urea, administration of macrolide antibiotic immunosuppressants, and disruption to immune function that characterise kidney transplant. [ABSTRACT FROM AUTHOR]

D-mannose, a C-2 epimer of glucose, exists naturally in many plants and fruits, and is found in human blood at concentrations less than one-fiftieth of that of glucose. However, although the roles of glucose in T cell metabolism, diabetes and obesity are well characterized, the function of D-mannose in T cell immune responses remains unknown. Here we show that supraphysiological levels of D-mannose safely achievable by drinking-water supplementation suppressed immunopathology in mouse models of autoimmune diabetes and airway inflammation, and increased the proportion of Foxp3[sup.+] regulatory T cells (T[sub.reg] cells) in mice. In vitro, D-mannose stimulated T[sub.reg] cell differentiation in human and mouse cells by promoting TGF-[beta] activation, which in turn was mediated by upregulation of integrin [alpha][sub.v][beta][sub.8] and reactive oxygen species generated by increased fatty acid oxidation. This previously unrecognized immunoregulatory function of D-mannose may have clinical applications for immunopathology., Author(s): Dunfang Zhang [1, 2]; Cheryl Chia [1]; Xue Jiao [1, 3]; Wenwen Jin [1]; Shimpei Kasagi [1]; Ruiqing Wu [1, 2]; Joanne E Konkel [1]; Hiroko Nakatsukasa [1]; Peter [...]

Tregs not only keep immune responses to autoantigens in check, but also restrain those directed toward pathogens and the commensal microbiota. Control of peripheral immune homeostasis by Tregs relies on [...]

[CD4.sup.+] T-helper cells that selectively produce interleukin (IL)-17 ([T.sub.H]17), are critical for host defence and autoimmunity (1-4). Although crucial for [T.sub.H]17 cells in vivo (5,6), IL-23 has been thought to be incapable of driving initial differentiation. Rather, IL-6 and transforming growth factor (TGF)-[β.sub.1] have been proposed to be the factors responsible for initiating specification (7-10). Here we show that [T.sub.H]17 differentiation can occur in the absence of TGF-β signalling. Neither IL-6 nor IL-23 alone efficiently generated [T.sub.H]17 cells; however, these cytokines in combination with IL-1β effectively induced IL-17 production in naive precursors, independently of TGF-β. Epigenetic modification of the Il17a, Il17f and Rorc promoters proceeded without TGF-β1, allowing the generation of cells that co-expressed RORγt (encoded by Rorc) and T-bet. [T-bet.sup.+] RORy[t.sup.+] [T.sub.H]17 cells are generated in vivo during experimental allergic encephalomyelitis, and adoptively transferred [T.sub.H]17 cells generated with IL-23 without TGF-β1 were pathogenic in this disease model. These data indicate an alternative mode for [T.sub.H]17 differentiation. Consistent with genetic data linking IL23R with autoimmunity, our findings re-emphasize the importance of IL-23 and therefore may have therapeutic implications., TGF-βl is important for murine [T.sub.H]17 differentiation (7,8) and accordingly, transgenic expression of a mutant TGF-β subunit receptor II (CD4dnTGF-βRII) in T cells interferes with the generation of [T.sub.H]17 cells [...]

CD4+ T-helper cells that selectively produce interleukin (IL)-17 (TH17), are critical for host defence and autoimmunity. Although crucial for TH17 cells in vivo, IL-23 has been thought to be incapable of driving initial differentiation. Rather, IL-6 and transforming growth factor (TGF)-?1 have been proposed to be the factors responsible for initiating specification. Here we show that TH17 differentiation can occur in the absence of TGF-? signalling. Neither IL-6 nor IL-23 alone efficiently generated TH17 cells; however, these cytokines in combination with IL-1? effectively induced IL-17 production in naive precursors, independently of TGF-?. Epigenetic modification of the Il17a, Il17f and Rorc promoters proceeded without TGF-?1, allowing the generation of cells that co-expressed ROR?t (encoded by Rorc) and T-bet. T-bet+ROR?t+ TH17 cells are generated in vivo during experimental allergic encephalomyelitis, and adoptively transferred TH17 cells generated with IL-23 without TGF-?1 were pathogenic in this disease model. These data indicate an alternative mode for TH17 differentiation. Consistent with genetic data linking IL23R with autoimmunity, our findings re-emphasize the importance of IL-23 and therefore may have therapeutic implications. [ABSTRACT FROM AUTHOR]

The ultimate outcome of T-cell recognition of peptide–major histocompatibility complex (MHC) complexes is determined by the molecular context in which antigen presentation is provided. The paradigm is that, after exposure to peptides presented by steady-state dendritic cells (DCs), inhibitory signals dominate, leading to the deletion and/or functional inactivation of antigen-reactive T cells. This has been utilized in a variety of models providing peptide antigen in soluble form in the absence of adjuvant. A co-inhibitory molecule of considerable current interest is PD-1. Here we show that there is the opportunity for the PD-1/PD-L1 interaction to function in inhibiting the T-cell response during tolerance induction. Using traceable CD4+ T-cell receptor (TCR) transgenic cells, together with a blocking antibody to disrupt PD-1 signalling, we explored the roles of PD-1 in the induction of tolerance versus a productive immune response. Intact PD-1 signalling played a role in limiting the extent of CD4+ T-cell accumulation in response to an immunogenic stimulus. However, PD-1 signalling was not required for either the induction, or the maintenance, of peptide-induced tolerance; a conclusion underlined by successful tolerance induction in TCR transgenic cells genetically deficient for PD-1. These observations contrast with the reported requirement for PD-1 signals in CD8+ T-cell tolerance. [ABSTRACT FROM AUTHOR]

In naïve T cells transforming growth factor-beta (TGF-β) induces Foxp3, a transcription factor essential for programming and developing T regulatory cells (Treg cells). This finding reveals a physiological factor which can turn on the Foxp3 gene and establishes an experimental approach to induce antigen-specific Treg cells as a potential therapy for human diseases. While this role for TGF-β is well confirmed, several critical questions remain largely unanswered and await further investigation. In this regard, it is imperative to understand the molecular pathways by which TGF-β signaling initiates and regulates Foxp3 expression. It is also important to elucidate which factors and/or cytokines influence the TGF-β-mediated conversion of naïve T cells and how to create an immunologically regulatory milieu to facilitate Treg cell generation in vivo. In this short article, we will highlight the key findings and recent progress in the field, discuss the molecular mechanisms underlying the TGF-β-mediated induction of Foxp3, and attempt to outline the challenges ahead. [ABSTRACT FROM PUBLISHER]

Transforming growth factor-β (TGF-β) receptors (TβRs) are essential components for TGF-β signal transduction in T cells, yet the mechanisms by which the receptors are regulated remain poorly understood. We show here that Poly(ADP-ribose) polymerase-1 (PARP-1) regulates TGF-β receptor I (TβRI) and II (Tβ RII) expression in CD4+ T cells and subsequently affects Smad2/3-mediated TGF-β signal transduction. Inhibition of PARP-1 led to the upregulation of both TβRI and TβRII, yet the underlying molecular mechanisms were distinct. PARP-1 selectively bound to the promoter of TβRII, whereas the enzymatic activity of PARP-1 was responsible for the inhibition of TβRI expression. Importantly, inhibition of PARP-1 also enhanced expression of TβRs in human CD4+ T cells. Thus, PARP-1 regulates TβR expression and TGF-β signaling in T cells. [ABSTRACT FROM AUTHOR]

The oral microbiome is influenced by environmental factors in chronic kidney disease and following kidney transplantation affecting microbial composition, which may have implications for health and recovery. A major driver of oral microbiome perturbation is the accumulation of urea in saliva. We have modelled increased salivary urea concentrations associated with CKD and subsequent reductions that may occur post-transplantation. Oral microbiota were established in constant-depth film fermenters by inoculation with saliva. Duplicate validation runs were maintained with artificial saliva with baseline urea concentrations (0.205 mg/mL) for 21 days. Triplicate treatment runs were then done with baseline urea for 10 days (healthy phase) before urea was increased for 10 days to reflect CKD concentrations (0.92 mg/mL) (CKD phase). This was followed by reversion to baseline urea concentrations (post-transplant phase). Biofilms in primary validation runs reached dynamic stability within 5 days according to viable counting. DNA sequence data indicated minimal taxonomic variation over time and between low and high urea treatments despite background noise indicating changes in bacteria belonging to the family Gemellaceae and the genera TG5 and Leptotrichia . Significant differences in alpha and beta diversity occurred between low and high urea states but not following reversion to a low urea environment. Increased abundance of the TG5 was detected in late model phases, despite apparent count stability, and independent of changes in urea concentrations., Importance: This study investigates dynamic changes in the oral microbiome associated with changes in salivary urea concentration, an important factor in chronic kidney disease (CKD). The in vitro system modeled increased urea concentrations and subsequent reductions post-transplantation. The study provides insight into the oral microbial shifts during different simulated clinical phases. Understanding these dynamics is crucial for advancing our comprehension of CKD-associated oral microbiome variations and their potential impact on patient well-being and recovery., Competing Interests: The authors declare no conflict of interest.

The oral microbiome has been implicated as a trigger for immune responsiveness in the oral cavity, particularly in the setting of the inflammatory disease periodontitis. The protocol presented here is aimed at characterizing the oral microbiome in murine models at steady state and during perturbations of immunity or physiology. Herein, we describe murine oral microbiome sampling procedures, processing of low biomass samples and subsequent microbiome characterization based on 16S rRNA gene sequencing., Competing Interests: The authors do not have any conflict of interest or competing interests to declare.

The oral mucosa is a barrier site constantly exposed to rich and diverse commensal microbial communities, yet little is known of the immune cell network maintaining immune homeostasis at this interface. We have performed a detailed characterization of the immune cell subsets of the oral cavity in a large cohort of healthy subjects. We focused our characterization on the gingival interface, a particularly vulnerable mucosal site, with thin epithelial lining and constant exposure to the tooth adherent biofilm. In health, we find a predominance of T cells, minimal B cells, a large presence of granulocytes/neutrophils, a sophisticated network of professional antigen-presenting cells (APCs), and a small population of innate lymphoid cells (ILCs) policing the gingival barrier. We further characterize cellular subtypes in health and interrogate shifts in immune cell populations in the common oral inflammatory disease periodontitis. In disease, we document an increase in neutrophils and an upregulation of interleukin-17 (IL-17) responses. We identify the main source of IL-17 in health and Periodontitis within the CD4(+) T-cell compartment. Collectively, our studies provide a first view of the landscape of physiologic oral immunity and serve as a baseline for the characterization of local immunopathology.

In naïve T cells transforming growth factor-beta (TGF-beta) induces Foxp3, a transcription factor essential for programming and developing T regulatory cells (Treg cells). This finding reveals a physiological factor which can turn on the Foxp3 gene and establishes an experimental approach to induce antigen-specific Treg cells as a potential therapy for human diseases. While this role for TGF-beta is well confirmed, several critical questions remain largely unanswered and await further investigation. In this regard, it is imperative to understand the molecular pathways by which TGF-beta signaling initiates and regulates Foxp3 expression. It is also important to elucidate which factors and/or cytokines influence the TGF-beta-mediated conversion of naïve T cells and how to create an immunologically regulatory milieu to facilitate Treg cell generation in vivo. In this short article, we will highlight the key findings and recent progress in the field, discuss the molecular mechanisms underlying the TGF-beta-mediated induction of Foxp3, and attempt to outline the challenges ahead.