Zika virus (ZIKV) has gained worldwide attention since it emerged, and a global effort is underway to understand the correlates of protection and develop diagnostics to identify rates of infection. As new therapeutics and vaccine approaches are evaluated in clinical trials, additional effort is focused on identifying the adaptive immune correlates of protection against ZIKV disease. To aid in this endeavor we have begun to dissect the role of CD4+T cells in the protection against neuroinvasive ZIKV disease. We have identified an important role for CD4+T cells in protection, demonstrating that in the absence of CD4+T cells mice have more severe neurological sequela and significant increases in viral titers in the central nervous system (CNS). The transfer of CD4+T cells from ZIKV immune mice protect type I interferon receptor deficient animals from a lethal challenge; showing that the CD4+T cell response is necessary and sufficient for control of ZIKV disease. Using a peptide library spanning the complete ZIKV polyprotein, we identified both ZIKV-encoded CD4+T cell epitopes that initiate immune responses, and ZIKV specific CD4+T cell receptors that recognize these epitopes. Within the ZIKV antigen-specific TCRβ repertoire, we uncovered a high degree of diversity both in response to a single epitope and among different mice responding to a CD4+T cell epitope. Overall this study identifies a novel role for polyfunctional and polyclonal CD4+T cells in providing protection against ZIKV infection and highlights the need for vaccines to develop robust CD4+T cell responses to prevent ZIKV neuroinvasion and limit replication within the CNS.
Commensal flora plays important roles in the regulation of the gene expression involved in many intestinal functions and the maintenance of immune homeostasis, as well as in the pathogenesis of inflammatory bowel diseases (IBD). The microRNAs (miRNAs), a class of small, non-coding RNAs, act as key regulators in many biological processes. The miRNAs are highly conserved among species and appear to play important roles in both innate and adaptive immunity, as they can control the differentiation of various immune cells as well as their functions. However, it is still largely unknown how microbiota regulates miRNA expression, thereby contributing to intestinal homeostasis and pathogenesis of IBD. In our current study, we found that microbiota negatively regulated intestinal miR-10a expression, in that the intestines, as well as intestinal epithelial cells and dendritic cells of specific pathogen-free (SPF) mice, expressed much lower levels of miR-10a compared to those in germ-free (GF) mice. Commensal bacteria downregulated DC miR-10a expression via TLR-TLR ligand interactions through a MyD88-dependent pathway. We identified IL-12/IL-23p40, a key molecule for innate immune responses to commensal bacteria, as a target of miR-10a. The ectopic expression of miR-10a precursor inhibited, whereas miR-10a inhibitor promoted, the expression of IL-12/IL-23p40 in DC. Mice with colitis expressing higher levels of IL-12/IL-23p40 exhibit lower levels of intestinal miR-10a compared to that in the control mice. Collectively, our data demonstrated that microbiota negatively regulates host miR-10a expression, which may contribute to the maintenance of intestinal homeostasis by targeting IL-12/IL-23p40 expression.
Infant formula and breastfeeding are environmental factors that influence the incidence of Type 1 Diabetes (T1D) as well as the acidity of newborn diets. To determine if altering the intestinal microbiome is one mechanism through which an acidic liquid plays a role in T1D, we placed non-obese diabetic (NOD)/ShiLtJt mice on neutral (N) or acidified H2O and monitored the impact on microbial composition and diabetes incidence. NOD-N mice showed an increased development of diabetes, while exhibiting a decrease in Firmicutes and an increase in Bacteroidetes, Actinobacteria, and Proteobacteria from as early as 2 weeks of age. NOD-N mice had a decrease in the levels of Foxp3 expression in CD4+Foxp3+ cells, as well as decreased CD4+IL17+ cells, and a lower ratio of IL17/IFNγ CD4+ T-cells. Our data clearly indicates that a change in the acidity of liquids consumed dramatically alters the intestinal microbiome, the presence of protective Th17 and Treg cells, and the incidence of diabetes. This data suggests that early dietary manipulation of intestinal microbiota may be a novel mechanism to delay T1D onset in genetically pre-disposed individuals.
Graphical Abstract Highlights d Sequence TCRb repertoires responding to orthopox viruses d Develop diagnostic assay using infection-associated TCRs d Track T cell responses using TCR sequences over time
ObjectiveSpasmolytic polypeptide-expressing metaplasia (SPEM) is a regenerative lesion in the gastric mucosa and is a potential precursor to intestinal metaplasia/gastric adenocarcinoma in a chronic inflammatory setting. The goal of these studies was to define the transcriptional changes associated with SPEM at the individual cell level in response to acute drug injury and chronic inflammatory damage in the gastric mucosa.DesignEpithelial cells were isolated from the gastric corpus of healthy stomachs and stomachs with drug-induced and inflammation-induced SPEM lesions. Single cell RNA sequencing (scRNA-seq) was performed on tissue samples from each of these settings. The transcriptomes of individual epithelial cells from healthy, acutely damaged and chronically inflamed stomachs were analysed and compared.ResultsscRNA-seq revealed a population Mucin 6 (Muc6)+gastric intrinsic factor (Gif)+ cells in healthy tissue, but these cells did not express transcripts associated with SPEM. Furthermore, analyses of SPEM cells from drug injured and chronically inflamed corpus yielded two major findings: (1) SPEM and neck cell hyperplasia/hypertrophy are nearly identical in the expression of SPEM-associated transcripts and (2) SPEM programmes induced by drug-mediated parietal cell ablation and chronic inflammation are nearly identical, although the induction of transcripts involved in immunomodulation was unique to SPEM cells in the chronic inflammatory setting.ConclusionsThese data necessitate an expansion of the definition of SPEM to include Tff2+Muc6+ cells that do not express mature chief cell transcripts such as Gif. Our data demonstrate that SPEM arises by a highly conserved cellular programme independent of aetiology and develops immunoregulatory capabilities in a setting of chronic inflammation.
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