Equivalent proportion between WT and SND1-/- mice in splenic T (CD3+), NK(NK1.1+CD3-), and B(B220+CD19+) cells. and CKO region was flanked by LoxP sites. DTA will be used for negative selection. The conditional KO allele was obtained after Flp-mediated recombination and the constitutive KO allele was then obtained after Cre-mediated recombination.(PDF) ppat.1009295.s001.pdf (517K) GUID:?E1AD6B66-3593-4594-B093-5A17AB1F7860 S2 Fig: A. Comparable proportion between HDM201 WT and ANGPT2 SND1-/- mice in splenic T (CD3+), NK(NK1.1+CD3-), and B(B220+CD19+) cells. B. Comparable proportion between WT and SND1-/- mice in the ratio of splenic CD4+T cells to CD8+T cells.(PDF) ppat.1009295.s002.pdf (508K) GUID:?F1DF285D-7410-4502-B81B-694C9960BB61 S3 Fig: SND1 does not alter Th1 activity when cocolture CD4+ T cells from Cm-immunized SND1-/- mice with DC from wild-type mice at day 7 p.i. DC (105 cells/well) isolated from WT at day 7 p.i. were cocultured with CD4+ T cells (106 cells/well) isolated from Cm-immunized wild-type or SND1-/- mice mice in the presence of UV-killed EBs, as described in Materials and Methods. Cocultured cells collected at day 2 were analyzed for flow cytometry, as described in Materials and Methods. (A) IFN–producing CD4 cells. (B) Foxp3+Treg cells. (C) IL-12-producing DC cells.(PDF) ppat.1009295.s003.pdf (462K) GUID:?C20A2205-4976-4356-8CB6-3E12A6EB2E32 Data Availability StatementAll relevant data are within the manuscript and its Supporting Information files. Abstract To date, no reports have linked the multifunctional protein, staphylococcal nuclease domain-containing protein 1 (SND1), to host defense against intracellular infections. In this study, we investigated the role and mechanisms of SND1, by using SND1 knockout (SND1-/-) mice, in host defense against the lung infection of evidence that SND1 plays an important role in host defense against intracellular bacterial infection, and suggest that SND1 can promote Th1/17 immunity and inhibit the expansion of Treg cells through modulation of the function of DCs. Author summary Since the initial study from our group reported that SND1 is able to hijack nascent MHC-I heavy chain in tumor cells, thereby impairing the proper assembling of MHC-I and sensitizing tumor cells to a diminished immune surveillance with abolished antigen presentation to cytotoxic CD8+ T cells, large attention has been drawn to its importance in host immunity. To date, no reports have been linked SND1 to immune response against bacterial infection. In this study, we investigated the role and mechanisms of SND1 in chlamydial lung infection by using SND1 knockout mice. We found that SND1 knockout mice showed significantly delayed clearance of bacteria and more severe disease. More importantly, we found that the SND1 deficiency led to alteration of phenotype and function of dendritic cells, which is associated with a failure in the development of protective Th1/17 immunity. These data indicate that SND1 protein plays an important role in host defense against chlamydial infection, at least partially through modulating dendritic cell function. Introduction (Cm), a natural chlamydial strain of murine, has been commonly used in murine models of respiratory and genital tract infections. Recent studies have shown the implications of Th1 immunity particularly IFN- production for host defense against chlamydia[3C5]. More recently, it was found that IL-17/Th17 responses are also significant for protection against chlamydial lung infection[6,7]. Accumulating effort has been made to elucidate the mechanisms underlying varioius patterns of cytokine responses in chlamydial infection and to enhance the type 1 and/or Th17 immune responses against protection. DCs are the primary antigen-presentation cells (APCs) of the immune system and have a key role in both HDM201 sensing pathogens and tuning the immune responses[8,9]. They consist HDM201 of various subtypes and are classified on the basis of their phenotype, location, and function[10,11]. Conventional DCs (cDCs) mainly reside in the lymphoid tissues such as thymus, spleen, and secondary lymph nodes (LNs). These conventional DCs exhibit higher levels of MHC-II and CD11c and can be subsequently divided into CD8chlamydial growth, as described in <0.05; **, <0.05; **, <0.05; **, splenic DCs were either tested by flow cytometry for intracellular cytokine of IL-12 and IL-10 or further cultured for 72 h to test IL-12, IL-23 and IL-10 protein production using ELISA. The intracellular cytokine-staining analyses showed that the DCs isolated from SND1-/- mice expressed significantly lower levels of IL-12, but higher levels of IL-10 compared with control mice under the infected condition (Fig 4AC4D). Consistently, IL-12p40, IL-12p70, IL-23 and IL-10 levels in the culture supernatants matched the pattern of intracellular cytokine (Fig 4EC4H). Moreover, we observed under na?ve condition the production of IL-12p40, IL-12p70 and IL-23 was also decreased in SND1-/- mice compared to control mice, albeit.