We recently reported that lactoferrin (LF) induces Foxp3+ Treg differentiation through binding to TGFβ receptor III (TβRIII), and this activity was further enhanced by TGFβ1. Generally, a low T‐cell ...receptor (TCR) signal strength is favourable for Foxp3+ Treg differentiation. In the present study, we explored the effect of lactoferrin chimera (LFch, containing lactoferricin aa 17–30 and lactoferrampin aa 265–284), along with TGFβ1 on Foxp3+ Treg differentiation. LFch alone did not induce Foxp3 expression, yet LFch dramatically enhanced TGFβ1‐induced Foxp3 expression. LFch had little effect on the phosphorylation of Smad3, a canonical transcriptional factor of TGFβ1. Instead, LFch attenuated the phosphorylation of S6 (a target of mTOR), IκB and PI3K. These activities of LFch were completely abrogated by pretreatment of LFch with soluble TGFβ1 receptor III (sTβRIII). Consistent with this, the activity of LFch on TGFβ1‐induced Foxp3 expression was also abrogated by treatment with sTβRIII. Finally, the TGFβ1/LFch‐induced T cell population substantially suppressed the proliferation of responder CD4+ T cells. These results indicate that LFch robustly enhances TGFβ1‐induced Foxp3+ Treg differentiation by diminishing TCR/CD28 signal intensity.
We previously found that lactoferrin (LF) induces Foxp3+ Treg differentiation and synergized with TGFβ1. In the present study, we investigated the effect of lactoferrin chimera (LFch), mimicking the functional peptide domain of LF, along with TGFβ1 on Foxp3+ Treg differentiation. LFch remarkably enhances TGFβ1‐induced Foxp3+ Treg differentiation by diminishing TCR/CD28 signal intensity.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Lentinan extracted from shiitake (Lentinula edodes) is a β-glucan that has been reported as an intravenous anti-tumor polysaccharide via enhancement of the host immune system. In this study, we ...determined the effect of lentinan on inflammasome activation, a multi-protein platform, in myeloid cells. Mouse bone marrow-derived macrophages were treated with lentinan with/without inflammasome triggers, and maturation of interleukin (IL)-1β, IL-18, or caspase-1 was measured as a readout of inflammasome activation. As a result, lentinan selectively inhibited absent in melanoma 2 (AIM2) inflammasome activation. In addition, lentinan up-regulated pro-inflammatory cytokines and induced expression of inflammasome-related genes through toll-like receptor 4 signaling. Furthermore, we assessed the effect of lentinan on mice treated with Listeria monocytogenes or lipopolysaccharide as an AIM2 or non-canonical inflammasome-mediated model. Lentinan attenuated IL-1β secretion resulting from Listeria-mediated AIM2 inflammasome activation and reduced endotoxin lethality via inhibition of non-canonical inflammasome activation. Thus, lentinan is suggested as an anti-AIM2 and anti-non-canonical inflammasome candidate despite its up-regulation of cytokine expression.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Innate lymphoid cells (ILCs) are important regulators of early infection at mucosal barriers. ILCs are divided into three groups based on expression profiles, and are activated by cytokines and ...neuropeptides. Yet, it remains unknown if ILCs integrate other signals in providing protection. We show that signaling through herpes virus entry mediator (HVEM), a member of the tumor necrosis factor (TNF) receptor superfamily, in ILC3 is important for host defense against oral infection with the bacterial pathogen Yersinia enterocolitica. HVEM stimulates protective interferon-γ (IFN-γ) secretion from ILCs, and mice with HVEM-deficient ILC3 exhibit reduced IFN-γ production, higher bacterial burdens and increased mortality. In addition, IFN-γ production is critical as adoptive transfer of wild-type but not IFN-γ-deficient ILC3 can restore protection to mice lacking ILCs. We identify the TNF superfamily member, LIGHT, as the ligand inducing HVEM signals in ILCs. Thus HVEM signaling mediated by LIGHT plays a critical role in regulating ILC3-derived IFN-γ production for protection following infection.
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•ILC3 are required for early host defense during Y. enterocolitica infection•IFN-γ from CCR6− ILC3 is essential for protection of mice from Yersinia•HVEM expression by ILC3 is important for IFN-γ production following infection•LIGHT is the ligand for HVEM signaling in regulating ILC3-derived IFN-γ production
Seo et al. find that IFN-γ-producing ILC3 in the small intestine are required for host protection against Yersinia enterocolitica infection. HVEM signaling in ILC3, mediated by the ligand LIGHT, is critical for regulating IFN-γ production for protection following infection.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Retinoic acid, in cooperation with TGF‐β1, increases IgA class switching and expression of gut‐homing molecules CCR9 and α4β7, on mouse B cells.
The present study demonstrates that RA has activity of ...an IgA switch factor and is more specific than TGF‐β1. RA independently caused only IgA switching, whereas TGF‐β1 caused IgA and IgG2b switching. We found that RA increased IgA production and that this was a result of its ability to increase the frequency of IgA‐secreting B cell clones. Increased IgA production was accompanied by an increase of GLTα. RA activity was abrogated by an antagonist of the RAR. Additionally, RA affected intestinal IgA production in mice. Surprisingly, RA, in combination with TGF‐β1, notably enhanced not only IgA production and GLTα expression but also CCR9 and α4β7 expression on B cells. These results suggest that RA selectively induces IgA isotype switching through RAR and that RA and TGF‐β have important effects on the overall gut IgA antibody response.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Poly-gamma-glutamic acid (γ-PGA) is a natural, edible and non-toxic polymer synthesized by Bacillus subtilis and is suggested as a safe biomaterial for the use in hydrogels and vaccine adjuvants. ...However, the effect of γ-PGA on inflammasome activation has not yet been studied in macrophages. Inflammasomes, which are intracellular multi-protein complexes, promote acute and chronic inflammation via interleukin-1β or interleukin-18 maturation, and they are known targets for metabolic syndromes and cancer. In this study, we observed that γ-PGA attenuated NLRP3, NLRC4 and AIM2 inflammasome activation, whereas it upregulated pro-inflammatory cytokine expression in human and murine macrophages. Although γ-PGA had conflicting effects on cytokine production and maturation, it clearly alleviated the severity of lipopolysaccharide-induced endotoxin shock in an animal model. Thus, we suggest γ-PGA as a candidate to control inflammasome-mediated disorders.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
VanR is a negative transcriptional regulator of bacteria that belongs to the PadR family and modulates the expression of vanillate transport and degradation proteins in response to vanillate. ...Although VanR plays a key role in the utilization of vanillate as a carbon source, it is barely understood how VanR recognizes its effector. Thus, our knowledge concerning the gene regulatory mechanism of VanR is limited. Here, we reveal the vanillate‐binding mode of VanR through structural, biophysical, and mutational studies. Similar to other PadR family members, VanR forms a functional dimer, and each VanR subunit consists of an N‐terminal DNA‐binding domain (NTD) and a C‐terminal dimerization domain (CTD). One VanR dimer simultaneously binds two vanillate molecules using two interdomain cavities, as observed in PadR. In contrast to these common features, VanR contains an additional α‐helix, αi, that has not been found in other PadR family members. The αi helix functions as an interdomain crosslinker that mediates interactions between the NTD and the CTD. In addition, the VanR‐specific αi helix plays a key role in the formation of a unique effector‐binding site. As a result, the effector‐binding mode of VanR is distinguishable from that of PadR in the location and accessibility of the effector‐binding site as well as the orientation of its bound effector. Furthermore, we propose the DNA‐binding mode and vanillate‐mediated transcriptional regulation mechanism of VanR based on comparative structural and mutational analyses.
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The atomic coordinates and the structure factors for VanR (PDB ID 5Z7B) have been deposited in the Protein Data Bank, www.pdb.org.
The VanR transcription factor from Corynebacterium glutamicum regulates vanABK transcription in response to the vanillate effector. Based on structural, biophysical, and mutational analyses, we reveal that the VanR‐specific αi helix is required for effector recognition and interdomain organization. Our study provides deep insights into the DNA‐binding mode and vanillate‐mediated regulatory mechanism of VanR.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Bacterial motility is provided by the flagellum. FliD is located at the distal end of the flagellum and plays a key role in the insertion of each flagellin protein at the growing tip of the flagellar ...filament. Because FliD functions as an oligomer, the determination of the oligomeric state of FliD is critical to understanding the molecular mechanism of FliD-mediated flagellar growth. FliD has been shown to adopt a pentameric or a hexameric structure depending on the bacterial species. Here, we report another distinct oligomeric form of FliD based on structural and biochemical studies. The crystal structures of the D2 and D3 domains of Serratia marcescens FliD (smFliD) were determined in two crystal forms and together revealed that smFliD assembles into a tetrameric architecture that resembles a four-pointed star plate. smFliD tetramerization was also confirmed in solution by cross-linking experiments. Although smFliD oligomerizes in a head-to-tail orientation using a common primary binding interface between the D2 and D3′ domains (the prime denotes the second subunit in the oligomer) similarly to other FliD orthologs, the smFliD tetramer diverges to present a unique secondary D2-D2′ binding interface. Our structure-based comparative analysis of FliD suggests that bacteria have developed diverse species-specific oligomeric forms of FliD that range from tetramers to hexamers for flagellar growth.
•The crystal structures of FliD from Serratia marcescens (smFliD) were determined.•smFliD assembles into a tetramer that has not been reported in other FliD orthologs.•smFliD oligomerizes into a four-pointed star plate in a head-to-tail organization.•The smFliD tetramer features a unique secondary binding interface.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
TGF‐β induces vascular endothelial growth factor (VEGF), a potent angiogenic factor, at the transcriptional and protein levels in mouse macrophages. VEGF secretion in response to TGF‐β1 is enhanced ...by hypoxia and by overexpression of Smad3/4 and hypoxia‐inducible factor‐1α/β (HIF‐1α/β). To examine the transcriptional regulation of VEGF by TGF‐β1, we constructed mouse reporters driven by the VEGF promoter. Overexpression of HIF‐1α/β or Smad3/4 caused a slight increase of VEGF promoter activity in the presence of TGF‐β1, whereas cotransfection of HIF‐1α/β and Smad3/4 had a marked effect. Smad2 was without effect on this promoter activity, whereas Smad7 markedly reduced it. Analysis of mutant promoters revealed that the one putative HIF‐1 and two Smad‐binding elements were critical for TGF‐β1‐induced VEGF promoter activity. The relevance of these elements was confirmed by chromatin immunoprecipitation assay. p300, which has histone acetyltransferase activity, augmented transcriptional activity in response to HIF‐1α/β and Smad3/4, and E1A, an inhibitor of p300, inhibited it. TGF‐β1 also increased the expression of fetal liver kinase‐1 (Flk‐1), a major VEGF receptor, and TGF‐β1 and VEGF stimulated pro‐matrix metalloproteinase 9 (MMP‐9) and active‐MMP‐9 expression, respectively. The results from the present study indicate that TGF‐β1 can activate mouse macrophages to express angiogenic mediators such as VEGF, MMP‐9, and Flk‐1.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Human rhinovirus (HRV) infection causes more than 80% of all common colds and is associated with severe complications in patients with asthma and chronic obstructive pulmonary disease. To identify ...antiviral drug against HRV infection, we screened 800 FDA-approved drugs and found budesonide as one of the possible drug candidates. Budesonide is a corticosteroid, which is commonly used to prevent exacerbation of asthma and symptoms of common cold. Budesonide specifically protects host cells from cytotoxicity following HRV infection, which depend on the expression of glucocorticoid receptor. Intranasal administration of budesonide lowered the pulmonary HRV load and the levels of IL-1β cytokine leading to decreased lung inflammation. Budesonide regulates IL-1β production following HRV infection independent of inflammasome activation. Instead, budesonide induces mitochondrial reactive oxygen species followed by activation of autophagy. Further, the inhibition of autophagy following chloroquine or bafilomycin A1 treatment reduced the anti-viral effect of budesonide against HRV, suggesting that the antiviral activity of budesonide was mediated via autophagy. The results suggest that budesonide represents a promising antiviral and anti-inflammatory drug candidate for the treatment of human rhinovirus infection.
•Budesonide protected host cells from cytotoxicity following HRV infection.•Intranasal administration of budesonide decreased lung inflammation by HRV infection.•Budesonide induces mitochondrial reactive oxygen species followed by activation of autophagy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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