bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ethyl pyruvate, a modulator of dendritic cell activation and survival (INM1P.437)
Authors: Chakhtoura Marita , Chain Robert , Varghese Linda , Gallucci Stefania 
Published: January 2023

Abstract
Danger Signals induce dendritic cells (DCs) to mature and present antigen in a pro-inflammatory context. When remaining immature however, DCs confer tolerance. Hence the need for new protocols inducing tolerogenic DCs. We assessed the effects of ethyl pyruvate (EP), ester derivative of pyruvate with anti-inflammatory properties, on DC responses. We found that EP (10mM) abolished pro-inflammatory cytokine induction (IL-12, TNFa, IL-6) by the TLR ligand and strong DC activator LPS in bone marrow-derived dendritic cells (BMDCs) at 8, 24, 48 and 72h post-stimulation. Furthermore, EP inhibited the IFN-I response and the anti-inflammatory cytokine IL-10 induced by LPS stimulation. Determining the effects of EP on BMDC viability with a dose titration response showed that EP (10mM) strongly inhibited in vitro DC activation without inducing death. Moreover, EP could prevent LPS-induced killing that normally occurs 72h post-stimulation. EP also decreased the up-regulation of BMDC surface MHC-II and co-stimulatory molecules, suggesting a role in inhibiting antigen presentation. Investigating the mechanism of action, EP decreased Erk and JNK phosphorylation but not p38 phosphorylation. Our results indicate that EP inhibits most of the biological responses of DCs to LPS. We are currently examining further the molecular mechanisms of EP’s action in BMDCs to highlight novel targets to inhibit DC activation.
Estrogen receptor alpha is required for macrophage iron sequestration and homeostasis in female mice (INM1P.438)
Authors: Fluitt Amy , Hevener Andrea 
Published: January 2023

Abstract
Sexual dimorphisms in immunity are known to confer protection against infections at the cost of heightened risk for autoimmunity in women. The female sex hormone, estradiol, can modulate both pro/anti-inflammatory macrophage signals and the mechanisms of action remain unclear. Iron sequestration by macrophages is fundamentally important to limit bacterial infection, and since estradiol is thought to influence iron metabolism in females, we asked whether ERα impacts the innate immune response by regulating macrophage iron metabolism. To address this question, we crossed floxed Esr1 (fl/fl control) and LysM-Cre transgenic animals to generate myeloid-specific ERα knockout (MACER) mice. We studied the effect of ERα deletion on iron homeostasis upon endotoxin treatment in female MACER and fl/fl conrols. MACER mice had increased serum iron (92%; p=0.01) compared to fl/fl under basal conditions. As expected, endotoxin treatment reduced serum iron levels in fl/fl controls (41%, p=.008), however there was no change in serum iron in MACER mice. Consistent with impaired macrophage iron homeostasis, expression of genes associated with iron absorption (TfR, Slc11a2, Cybrd1), efflux (Fpn), and storage (Ftl) were significantly altered in female MACER mice compared to fl/fl controls. Together, these data suggest that ERα regulates macrophage iron metabolism in females, is required for systemic iron homeostasis, and may play a previously unrecognized role in female innate immunity.
The NF-κB p65 and p50 homodimer cooperate with pSTAT1 to synergistically activate iNOS transcription in cancer cells and myeloid cells (INM1P.440)
Authors: Simon Priscilla , Sharman Sarah , Lu Chunwan , Yang Dafeng , Paschall Amy , Liu Kebin 
Published: January 2023

Abstract
Inducible nitric oxide synthase (iNOS) metabolizes L-arginine to produce NO, which was originally identified in myeloid cells as a host defense mechanism against pathogens. However, recent studies have revealed that iNOS is often induced in both tumor and myeloid cells in the tumor microenvironment. Compelling experimental data have shown that iNOS can promote or suppress tumor development in certain cellular conditions. The molecular mechanisms underlying this contrasting function of iNOS is unknown. Because iNOS is often induced by inflammatory signals, it is likely that the opposite functions of iNOS might be controlled by inflammatory signaling pathways. We show here that proinflammatory IFN-γ and NF-κB signals synergistically induce iNOS expression in human colon cancer cells. We further demonstrated that NF-κB directly binds to the NOS2 promoter to regulate iNOS expression. Although the IFN-γ and NF-κB signaling pathways alone are insufficient to induce iNOS expression in myeloid cells, IFN-γ and NF-κB can synergistically induce iNOS expression. We determined that IFN-γ up-regulates IRF8 expression to augment NF-κB induction of iNOS expression. We observed that the p65/p65 and p50/p50 homodimers, not the common canonical p65/p50 heterodimer, directly binds to the nos2 promoter to regulate iNOS expression in myeloid cells. Our results thus determine that the IFN-γ-induced IRF8 acts in concert with the NF-κB p65/p65 and p50/p50 homodimers to regulate iNOS expression.
Calcium binding protein S100a9 protects male lupus-prone BWF1 mice from disease development (IRC4P.448)
Authors: Davison Laura , Alberto Andrés , Liegl Lauren , Vogl Thomas , Jorgensen Trine 
Published: January 2023

Abstract
Testosterone protects from SLE pathogenesis, yet the mechanism of protection remains unknown. Using the (NZB x NZW)F1 (BWF1) mouse model of SLE, we have previously shown that immunosuppressive Gr1+CD11b+ cells are elevated in protected male BWF1 mice compared with females. Female and male Gr1+ cells use different mechanisms of suppression: reactive oxygen and nitrogen species (ROS/NOS) (female), or a secreted component independent of ROS/NOS production (male). Furthermore, female Gr1+ cells lose their capacity to suppress as the mice age. In support hereof, in vivo depletion of Gr1+ cells accelerated disease development in male mice only. Calcium-binding protein S100a9 is induced by inflammation and has been shown to exert either proinflammatory or immunosuppressive functions. Finding that male-derived Gr1+ cells express 3-4 fold higher levels of S100a9 mRNA than females, we hypothesized that S100a9 is the immunosuppressive mechanism used by male Gr1+ cells. Using S100a9-/- BWF1 mice we show that male-derived Gr1+ cells indeed use S100a9 to suppress plasma cell differentiation in vitro. Moreover, BWF1.S100a9-/- males developed increased serum ANA levels and IgG-IC deposition in the kidney glomeruli, and accelerated renal failure, while only the kidney phenotype was somewhat affected in BWF1.S100a9-/- female mice. In conclusion, differential regulation of S100a9 by male and female Gr1+ cells may contribute to the differential development of lupus in male and female BWF1 mice.
Mast cell 2B4 induces antigen-specific CD8+ T cells function (IRC4P.457)
Authors: Kim Jiyoung , Lee Junho , Kim Kwanghee , Lim Seon Ah 
Published: January 2023

Abstract
The signaling lymphocyte activation molecule (SLAM) family receptor, 2B4 (CD244), is expressed on NK cells, a subpopulation of T cells (including CD8+ T cells and γ/δ T cells), monocytes/macrophages, basophils, eosinophils, and mast cells (MCs). Although 2B4 is known to play an important role in the biological function of NK cells, the role of 2B4 on MCs remains unclear. Here, we identified a critical role for 2B4 on MCs in antigen-specific CD8+ T cell activation. Using a co-culture system, we demonstrated that OT-I CD8+ T cells acquired higher expression of CD69 and CD25 activation markers in the presence of OVA-pulsed wild type (WT) bone marrow-derived MCs (BMMCs) but not 2B4 KO BMMCs. In addition, CD8+ T cell activation was significantly reduced by incubation with 2B4-blocked MCs. This effect was potentiated by incubation with CD48-blocked MCs, indicating that while 2B4/CD48 interactions influenced CD8+ T cell activation, CD2/CD48 interactions were also involved in MC regulation of CD8+ T cells. Moreover, CD8+ T cell proliferation was enhanced by 2B4-expressing MCs. Thus, this study provides insight on how MCs can influence CD8+ T cells via 2B4/CD48 interactions.
C1q-CD33 inhibitory immunoreceptor interactions occur via C1q globular heads and CD33 C2-like domains (IRC4P.601)
Authors: Santiago-Schwarz Frances , Son Myoungsun , Wright Janell 
Published: January 2023

Abstract
Complement independent functions of C1q include C1q’s collagen-like region (CLR) engaging the immunoreceptor LAIR-1 to restrict monocyte-derived dendritic cell (mono-DC) differentiation/activation. If C1q’s globular region (gC1q) directly engages distinct inhibitory immunoreceptors is unknown. CD33, a C-type lectin, is highly expressed on monocytes. Like LAIR-1, triggering through CD33 inhibitory motifs (ITIM) restricts monocyte/DC activity. CD33 has C2-like domains potentially recognized by gC1q; thus we hypothesized that C1q would engage CD33. We tested whole (w) C1q/gC1q/C1qCLR for binding to CD33 isoforms (CD33M: one V & one C2 domain and CD33m: C2 domain only). Analyses with purified proteins revealed that wC1q binds to both isoforms and that gC1q, but not C1qCLR, binds to CD33 C2 domains. CD33M and CD33m transfected HEK293T cells bound C1q. On THP-1 cells, masking of CD33 C2 domains by sialic acid impeded binding of C1q. Domain oriented inhibitory partnering was substantiated by coincident triggering of CD33/LAIR-1 ITIM phosphorylation in monocytes by C1q and phosphorylation of LAIR-1 but not CD33 ITIM by C1qCLR. C1q also prompted CD33-LAIR-1 crosslinking on monocytes in proximity ligation assays. Thus, CD33 is a receptor for C1q; CD33 C2 domains are biologically relevant; C1q/CD33/LAIR-1 partnering occurs in monocytes. Masking of CD33 C2 domains by sialic acid suggests a mechanism for controlling C1q-CD33 inhibitory activity.
Natural indoles, indole-3-carbinol (I3C) and 3,3’-diindolylmethane (DIM), attenuate staphylococcal enterotoxin B-mediated liver injury by downregulating miR-31 expression and promoting caspase-2-mediated apoptosis (IRC4P.605)
Authors: Busbee Philip , Nagarkatti Mitzi , Nagarkatti Prakash 
Published: January 2023

Abstract
Staphylococcal enterotoxin B (SEB) is a potent superantigen capable of inducing inflammation characterized by robust immune cell activation and proinflammatory cytokine release. In the current study, we investigated the effect of natural indoles, I3C and DIM on SEB-mediated liver injury. Injection of SEB into D-galactosamine-sensitized female C57BL/6 mice resulted in liver injury as indicated by an increase in enzyme AST levels, induction of inflammatory cytokines, and massive infiltration of immune cells into the liver. Administration of I3C and DIM (40mg/kg), by intraperitonal injection, attenuated SEB-induced acute liver injury, as evidenced by decrease in AST levels, inflammatory cytokines and cellular infiltration in the liver. I3C and DIM triggered apoptosis in SEB-activated cells primarily through activation of the intrinsic mitochondrial pathway. In addition, inhibitor studies involving caspases revealed that I3C and DIM-mediated apoptosis in these activated cells was dependent on caspase-2 but independent of caspase-8, 9 and 3. I3C and DIM also caused a decrease in Bcl-2 expression. Both compounds also down-regulated miR-31, which directly targets caspase-2 and influences apoptosis in SEB-activated cells. Our data demonstrate for the first time that indoles can effectively suppress acute hepatic inflammation caused by SEB and that this may be mediated by decreased expression of miR-31 and consequent caspase-2-dependent apoptosis in T cells.
STAT6-dependent regulation of airway inflammatory responses via OX40L expression on dendritic cells (IRC4P.610)
Authors: Lee Soojin , Shan Jichuan , Jin Manli , Srinivasa Bharat , Fixman Elizabeth 
Published: January 2023

Abstract
Epithelial and other structural cells drive Th2 responses in vivo indirectly upon TLR4 or NOD receptor stimulation and production TSLP and other innate cytokines, which upregulate OX40L on dendritic cells (DCs). These DCs are potent inducers of Th2 cell differentiation. We have investigated the ability of a cell penetrating peptide targeting STAT6, STAT6-IP, to modulate OX40L expression and inhibit Th2 responses. Bone marrow derived CD11c+ DCs (BMDCs) were incubated with OVA (containing LPS) ± STAT6-IP (or control peptides) and MFI of OX40L surface expression was quantified by FACS. OVA-induced increases in OX40L MFI were reduced by STAT6-IP. Our data suggest that STAT6-IP treated, OVA-loaded BMDCs also have reduced Th2 cytokine production from target CD4+ T cells. In vivo, lung OX40L mRNA levels increased in OVA+MDP (a NOD2 agonist) treated mice were inhibited by STAT6-IP treatment. Airway inflammatory responses were assessed in OVA+MDP (± STAT6-IP) treated mice, upon OVA challenge 28 days later. Lung resistance, bronchoalveolar lavage levels of eosinophils and neutrophils, Th2 cytokine production & TARC mRNA levels were all reduced by STAT6-IP treatment at the time of OVA+MDP sensitization. Our data are consistent with a model in which STAT6-IP inhibits antigen-induced OX40L expression on DCs, reducing Th2 cytokine production from target T cells and the subsequent Th2-biased airway inflammatory responses that contribute to pathogenesis in allergic airways disease.
The roles of HMGB1 in mitophagy, as a targeted defense against cellular stress (IRC4P.616)
Authors: Jeong Jang , Yoo Jong , Shin Jeon-Soo 
Published: January 2023

Abstract
High mobility group box 1(HMGB1), an abundant non-histone nuclear protein is translocated to cytosol under cellular stress like oxidative stimuli. Translocated HMGB1 has been reported as regulator of autophagy, which is a process where eukaryotes degrade various intracellular materials such as damaged mitochondria. Autophagy consists of three types: macro, micro, and chaperone-mediated autophagy. In this study, we show that HMGB1 could translocate to mitochondria; migration of HMGB1 was dramatically increased in stress condition. And, we also found that HMGB1 interact with mitophagy related protein. To determine whether HMGB1 is a positive regulator of mitophagy, we confirmed the difference in degree of mitophagy induction with HMGB1 deficient cell line under stress condition. We demonstrated that HMGB1 deficient cells showed higher rate of mitophagy induction than wild type cells did. In summary, HMGB1 could migrate to mitochondria and bind with mitophagy related protein, which may diminish mitophagy induction. Furthermore, because many neurodegenerative diseases are known to be related to autophagy, these findings suggest that HMGB1 might trigger onset of neurodegenerative disease, which can be a novel therapeutic target.
Natural killer cells suppress B cell immunity through perforin-dependent mechanisms (IRC4P.617)
Authors: Rydyznski Carolyn , Karmele Erik , Mahl Sarah , Waggoner Stephen 
Published: January 2023

Abstract
Accumulating evidence suggests that natural killer (NK) cells are critical regulators of antiviral T cells during chronic infection. We find that NK cells are also potent inhibitors of germinal center (GC) responses and the generation of long-lived B cell immunity after acute infection. A similar suppressive function was noted for NK cells after immunization with the non-replicating T cell-dependent antigen NP-KLH, suggesting that strategies to subvert NK cell-mediated inhibition may be able to improve vaccine responses. To determine whether cytotoxic function is important for this regulatory activity, we examined the contributions of perforin-containing granules and the death receptor Fas. NK cell inhibition of GCs was intact in Fas-deficient lpr mice but absent in perforin-deficient mice, thereby implicating granule-mediated cytotoxicity in this process. Moreover, we found that NK cells acted in a perforin-dependent manner during the first three days post-immunization to suppress generation of follicular helper CD4 T cell (Tfh) responses. The suppression of Tfh by NK cells was independent of the presence or absence of B cells, while CD4 T cells were required for development of virus-specific B cells. Thus, NK cells determine the quality and magnitude of B cell responses following immunization predominately via perforin-dependent repression of Tfh responses. This immunoregulatory process represents an innovative target for interventions aimed at enhancing vaccine efficacy.
Scavenger receptor SREC-I mediated entry of TLR4 into lipid microdomains and triggered inflammatory cytokine release in macrophages upon LPS activation (IRC4P.454)
Authors: Murshid Ayesha , Gong Jianlin , Borges Thiago , Calderwood Stuart 
Published: January 2023

Abstract
Scavenger receptor associated with endothelial cells I (SREC-I) was shown to be expressed in immune cells and to play a role in the endocytosis of peptides and antigen presentation. As our previous studies indicated that SREC-I required intact Toll-like receptor 4 (TLR4) expression for its immune functions in tumor immunity, we examined potential interactions between these two receptors. We have shown here that SREC-I became associated with TLR4 on binding bacterial lipopolysaccharides (LPS). The receptors then became internalized together in intracellular endosomes. SREC-I then promoted TLR4-induced signal transduction through the NFĸB and MAP kinase pathways, leading to enhanced inflammatory cytokine release. Activation of inflammatory signaling through SREC-I / TLR4 complexes appeared to involve recruitment of the receptors into detergent-insoluble, cholesterol-rich lipid microdomains that contain the small GTPase Cdc42 and the non-receptor tyrosine kinase c-Src. Under conditions of SREC-I activation by LPS, TLR4 activity required Cdc42 as well as cholesterol and actin polymerization for signaling through NFkB and MAP kinase pathways. SREC-I appeared to respond differently to another ligand, the molecular chaperone Hsp90 that, while triggering SREC-I-TLR4 binding caused only faint activation of the NFkB pathway. Our experiments indicated that SREC-I could bind LPS and might be involved in innate/inflammatory immune responses to extracellular danger signals.
Generation of knock-in mouse model expressing functional CD8ab without an active CD8aa (IRC5P.634)
Authors: Kang Yoon Joong 
Published: January 2023

Abstract
To understand functional significance of Recognition of CD8aa complexes in vivo, we generated transgenic mouse model and knock-in mouse model carrying a variant CD8ab (CD8am3b) capable of forming inactive CD8aa/pMHC1 complexes. These mice show a sub-optimal thymic differentiation with reduced populations of CD8 single-positive thymocytes. Transgenic CD8 T cells exhibit a compromised developmental capacity when competing with CD8 T cells exhibit normal effector function against viral infection. In addition, TCRab+ T cell populations expressing CD8ab+ or CD8aa reduced to about 50% in our TG mice compared to normal B6 mice, and none of these CD8aa+TCRab+ T cells were attained by TL tetramer. Furthermore, this mice show reduced inflammatory responses in DSS-induced colitis model. These findings obtained from our transgenic and knock-in animal models are going to be important to dissect the distinct function of CD8aa molecule.
Searching for natural Treg peptide-MHC ligands by engineering increased affinity/avidity Treg TCRs. (IRC5P.621)
Authors: Phillips Matt 
Published: January 2023

Abstract
Natural Tregs (nTregs) are produced in the thymus by selection to self peptide-MHC (spMHC) complexes. There is abundant data in the literature that suggests nTreg TCRs are higher affinity for self than conventional T cells and respond to spMHC in the periphery. To date, no nTreg ligands have been found, in part, possibly because nTregs may have TCR affinities that fall somewhere between the affinties required for positive and negative selection in the thymus for conventional T cells. This implies that although nTreg TCRs may be higher affinity for self, this affinity may still be lower than a conventional T cell TCR has for it's immunological antigen. To overcome this, we have developed a way to increase the affinity for some nTreg TCRs for pMHC while still mainting peptide specificity. Using these higher affinity nTreg TCRs, we can scan peptide-MHC libraries in order to find peptide mimitopes which may lead us to the actual self-peptides which are able stimulate specific nTregs.
New roles for IL-12: characterizing how IL-12 pretreatment alters human CD4 T cell responses (IRM5P.636)
Authors: Vacaflores Aldo , Chapman Nicole , Houtman Jon 
Published: January 2023

Abstract
Antigen experienced CD4 T cells are constantly exposed to IL-12 during infections and autoimmune disorders. When given concurrently with TCR induction, IL-12 enhances IFN-γ production. However, alterations of TCR-mediated antigen experienced CD4 T cell functions by prior IL-12 exposure remain unexplored. To address this knowledge gap, human antigen experienced CD4 T cells were exposed to IL-12, IL-12 was then removed, and the cells were stimulated with anti-TCR antibodies. We found that IL-12 treatment increased TCR-induced IFN-γ, TNF-α, IL-13, IL-4 and IL-10 production in comparison to untreated cells. This suggests that prior exposure to IL-12 primes the TCR-induced release of a range of cytokines. The potentiation of TCR-mediated cytokine release required at least 90 minutes of IL-12 treatment and only lasted for 6-12 hours after IL-12 removal. Interestingly, we found that IL-12 exposure selectively increased the transcription of IFN-γ and IL-10 without altering the transcript levels of the other cytokines. Furthermore, IL-12 treatment increased the phosphorylation of AKT, p38 and LCK following TCR stimulation without altering other TCR signaling molecules. Our data uncover a new function of IL-12; IL-12 primes antigen experienced CD4 T cells to enhance cytokine release by “rewiring” TCR signaling pathways. This novel function of IL-12 provides insight into potential methods to enhance or suppress CD4 T cell activity that could be harnessed as therapeutics.
Role of hydrogen sulfide in myocardial infarction via immue response of macrophages (IRM5P.645)
Authors: Zhu Yi Zhun 
Published: January 2023

Abstract
Macrophages are critical players in the inflammation, and are of central importance for healing after Myocardial infarction (MI). Hydrogen sulfide (H2S) has been demonstrated to possess cardioprotection in MI. However, it is unclear whether and how macrophage modulation by H2S can affect infarct repair. Thus, the present study was to evaluate the roles and mechanisms of H2S on macrophage post-MI. The cardiac function were improved in both WT mice and CSE KO mice, pretreated with different concentrations of NaHS (Exogenous sources of H2S). Meanwhile, the cardiac tissues that treated with NaHS exerted an increased immunohistochemical staining for macrophage marker (Galectin-3). Enhanced M2 macrophage polarization was observed in the infarcted heart treatment with NaHS following MI, along with increased production of M2 signature cytokines, such as interleukin-10 and CD163. In vitro, NaHS accelerated the migration of macrophage cell line RAW264.7. While, the inhibitors (refer to Pyk2, FAK, Src, and Rac1), not only significantly restored the migratory ability in response to the NaHS, but also blocked the activation of phospho-Src, -Pyk2, -FAK397, and -FAK925. Furthermore, the internalization of integrin β1 on the macrophage surface was induced by NaHS. Whereas, integrin β1 silencing inhibited the macrophage migration and the Src signaling activation. The results suggest that H2S may have the potential as an anti-infarct of MI by immune response of macrophages.