bluuebunny/crossref_metadata_2025_split huggingface dataset:
B cell-intrinsic production of CCL3/4 promotes direct sampling of Germinal Center B cells by T follicular regulatory cells and limits non-foreign antigen specific B cell response.
Authors: Benet Zachary , Wu Rita , Marthi Matangi , Turner Jackson , Grigorova Irina 
Published: January 2023

Abstract
A hallmark of adaptive humoral immunity is the germinal center (GC) reaction. GCs are the primary site of antigen-dependent clonal expansion, immunoglobulin diversification, and affinity maturation and give rise to memory cells and long-lived plasma cells that secrete high-affinity antibodies. These coordinated processes in GCs are highly dependent on cognate follicular T cells. Previous studies and our findings suggest increased expression of proinflammatory chemokines CCL3/4 in GC centrocytes. However, the role of CCL3/4 for centrocyte interactions with follicular T cells and regulation of humoral immunity is poorly understood. We found that B cell intrinsic production of CCL3/4 is required for control of B cell expansion within GCs and restrict the development of class-switched anti-nuclear antibodies following immunization with foreign antigen. We determined that follicular regulatory T cells (Tfr) respond to CCL3/4 chemokines ex vivo and interact more frequently with WT compared to CCL3-deficient GC B cells in vivo using two photon microscopy. Finally, we have identified a subpopulation of GC centrocytes that have significantly increased expression levels of CCL3/4. These data suggests that CCL3/4 secreted by a subset of GC B cells promotes their direct interactions with Tfr cells and plays a role in the elimination of potentially self-reactive B cell clones within GCs.
miRNA regulation of macrophage inflammatory phenotype
Authors: Guerau-De-Arellano Mireia , Jablonski Kyle , Amici Stephanie A. , Gaudet Andrew , Popovich Phillip G. , Webb Lindsay 
Published: January 2023

Abstract
Classically (M1) and alternatively activated (M2) macrophages play distinct roles in various physiological and disease processes. M1 responses can cause inflammatory disease and tissue damage while M2 macrophages can limit inflammation and promote tissue repair. Therefore, understanding key players driving M1 or M2 phenotype may provide novel targets for therapeutic intervention. MicroRNA are small RNAs that bind to messenger RNA and post-transcriptionally modify gene expression and miR-155 has been associated with inflammatory phenotype. miR-155 was up-regulated more than 100-fold in M1, but not M2 macrophages, and inflammatory genes and proteins that define the M1 phenotype (e.g., iNOS, IL-1b, TNF-a) were reduced up to 72% in miR-155 knockout mouse macrophages. In contrast, miR-155 deficiency did not affect expression of genes associated with M2 macrophages (e.g., Arginase-1). Comparative transcriptional profiling of macrophages derived from wild-type and miR-155 knockout mice revealed that approximately half of the wild-type M1 signature was dependent on miR-155. Among miR-155-dependent M1 inflammatory effectors we found IL-6, iNOS, IL-1b, TNF-a and IL-12 as well as the recently described M1 marker CD38. miR-155 targets Bat5, Mafb, c-Maf, Bach1, Ptprj and Il6ra were increased in miR-155 KO M1 macrophages. Importantly, treatment with a miR-155 oligonucleotide inhibitor suppressed iNOS and TNF-a gene expressions in wild-type M1 macrophages, lending support to the idea that miR-155 targeting may be beneficial in inflammatory disease. Overall, these data indicate that miR-155 plays an essential role in the differentiation and effector potential of inflammatory M1 macrophages.
Loss of TRAF3 Promotes a Premalignant Metabolic State in B cells.
Authors: Mambetsariev Nurbek , Lin Wai W , Stunz Laura L , Bishop Gail A 
Published: January 2023

Abstract
TRAF3 is a signaling protein that acts as a tumor suppressor in B cells. B cell conditional TRAF3−/− mice display a remarkable expansion of B cell compartments and parenchymal B cell infiltration, attributed to enhanced B cell survival without increased proliferation. When aged, these mice develop lymphomas, and TRAF3 mutations are common in human B cell lymphoma and multiple myeloma. The mechanism of how loss of TRAF3 promotes B cell survival phenotype is not well understood; this particular role for TRAF3 is not seen in other immune cell types. We find that loss of TRAF3 leads to increased uptake of glucose in B cells in vitro and in vivo. This is accompanied by increased oxidative phosphorylation and glycolysis. In the absence of TRAF3, expression of Glut1 and Hexokinase II, two molecules important for glucose metabolism, is increased. Treatment of B cells with Glut1 inhibitor or the competitive glycolysis inhibitor 2-DG attenuates cell survival, and B cell viability is also substantially reduced in a glucose-free environment. Mechanistically, loss of TRAF3 leads to the induction of Pim2 kinase. Pim2 in turn promotes the protein stability of the oncogenic transcription factor c-Myc, known to drive expression of glycolytic genes. Our study shows that B cell deficiency of TRAF3 is sufficient for altered metabolic programming, consistent with a premalignant abnormal survival phenotype.
Unexpected separation of functions at the level of miR-146a targets regulates immune cell activation and malignant transformation
Authors: Magilnick Nathaniel , Reyes Estefany , Wang Wei-Le , Kramer Nicholas , Boldin Mark 
Published: January 2023

Abstract
microRNA-146a (miR-146a) has been previously implicated as an essential molecular brake that prevents immune overreaction and malignant transformation by attenuating NF-κB signaling. miR-146a−/− mice display an autoimmune disorder, and also develop frank tumors in secondary lymphoid organs and a progressive myelodysplastic syndrome (MDS) as they age. miR-146a was proposed to exert its regulatory activity by targeting Traf6 and Irak1, genes which encode two key adapter proteins that function upstream of NF-κB activation. The exact contribution of miR-146a-mediated silencing of Traf6 and Irak1 to the control of immune activation is currently unknown. Therefore, we defined the role of the miR-146a-Traf6 axis in the regulation of immune homeostasis using mouse genetic epistasis analysis. Our studies have uncovered a unique separation of functions at the level of miR-146a targets. Lowering the Traf6 gene dose and consequent attenuation of NF-κB activation rescued many significant miR-146a−/− phenotypes such as splenomegaly, aberrant myeloproliferation, and excessive inflammatory responses. In contrast, decreasing Traf6 expression had no effect on the development of the MDS-like phenotype in aged miR-146a−/− mice, indicating that miR-146a controls hematopoietic stem cell (HSC) homeostasis through a different molecular mechanism. Our genetic data implicate excessive IFNγ production as the main driver of HSC exhaustion and bone marrow failure in miR-146a−/− mice. Furthermore, our findings suggest that control of the Traf6-NF-κB regulatory axis by miR-146a is not essential for its tumor suppressor activity, because lowering the Traf6 gene dose did not affect the rate of development of miR-146a-deficient lymphomas.
Role of IL-1β and the gut-lung axis in sterile inflammation following lung ischemia reperfusion injury
Authors: Prakash Arun , Tian Xiaoli , Hellman Judith 
Published: January 2023

Abstract

Background
Ischemia reperfusion (IR) injury is a source of sterile inflammation that can complicate the clinical course of severely injured trauma patients in shock, organ transplantation, and thrombotic/embolic events. The lungs are a portal to the external environment and a barrier organ. As such, they are vulnerable to infectious and sterile insults that can be life threatening if their ability to deliver oxygen and eliminate CO2 are compromised. We previously demonstrated a role for the gut microbiome in modulating this inflammatory process in vivo and in priming alveolar macrophages.

Methods
We used an in vivo model of left pulmonary artery occlusion to examine the inflammation generated in mice either genetically deficient or pharmacologically inhibited in IL-1β release or signaling pathways. We also challenged alveolar macrophages and endothelial cells in vitro with colonic lumen filtrates from antibiotic treated and control mice to determine whether shed LPS and metabolites are among the priming factor(s) for alveolar macrophages.

Results/Conclusions
Using knockout mice and inhibitor studies, we have determined that the inflammasome regulates lung IR-induced sterile inflammation. Specifically, the NLRP3 inflammasome, IL-1β release, and downstream IL-1β signaling are important factors in the generation of lung IR inflammation. Finally, we believe that the exponentially higher level of shed LPS in mice with a full complement of gut microbiota, as well as levels of short chain fatty acids, such as butyrate, may intriguingly explain the priming of alveolar macrophages that results in IL-1β production. Together this may constitute a gut-lung axis of communication that modulates the lung IR sterile inflammatory process.
iNOS over expression reduces K562 cell proliferation and promotes neutrophilic differentiation
Authors: Awasthi Deepika , Singh Abhishek Kumar , Dubey Megha , Nagarkoti Sheela , Barthwal Manoj Kumar , Dikshit Madhu 
Published: January 2023

Abstract
Nitric oxide (NO) is low molecular weight gaseous signalling molecule which modulates various immune functions, vasodilation, proliferation, differentiation and apoptosis. NO at low concentrations protects cells from apoptosis or induced proliferation, whereas at high concentration it inhibits cell growth and induces apoptotic cell death. Increasing evidences highlight the pro- and anti-tumorigenic effect of iNOS-derived NO depending on its concentration, redox environment, NO flux and the cell type. The present study was undertaken to assess the role of iNOS derived NO on K562 cell line (human myelogenous cell line). Stable over-expression of iNOS as confirmed by enhanced iNOS mRNA/protein expression also NO donor (DETA-NO) treatment exhibited cell cycle arrest, enhanced apoptosis. Apoptosis gene expression profiling indicated that iNOS over-expressed K562 cell line generated a broad set of alterations in the gene expression: Upregulated expression of apoptosis related genes - BCL10, LRDD, Death effector domains (DEDs), caspase 4, caspase 8, tumor necrosis factor (ligand) superfamily, member10 (TNFSF10), FADD as compared to control K562 cells. Using in vitro approach we further assessed the significance of iNOS in C/EBPα induced neutrophilic differentiation of K562 cells. May-Grünwald-Giemsa and hoechst staining demonstrated that ectopic expression of C/EBPα promotes rapid neutrophilic differentiation in K562iNOS cells as compared to K562 cells. Morphologic differentiation was further accompanied by up-regulation of myeloid-specific surface markers CD11b. Altogether, these results implicate that iNOS play a crucial role in cell cycle arrest, apoptosis and neutrophilic differentiation of K562 cells.
Trim9 mediates macrophage chemotaxis in a RING-dependent manner
Authors: Tokarz Debra A , Yoder Jeffrey A. 
Published: January 2023

Abstract
Tissue infiltration by macrophages and neutrophils is an early and critical step in the innate immune response, yet excessive infiltration by these leukocytes can contribute to disease pathology. Defining intracellular mediators of neutrophil and macrophage chemotaxis will reveal novel targets for modulating inflammation. The tripartite motif (Trim) proteins are a family of E3 ubiquitin ligases, of which several members have defined roles in innate immune responses. Although previously considered to be brain-specific, we have identified trim9 as a gene with increased transcript levels within macrophages and neutrophils of larval zebrafish and of humans following immune stimulation with multiple toll-like receptor agonists. Prior to our studies, Trim9 had no reported immune function, however, its published role in control of axon growth guidance suggests it is important in cell migration. To investigate the role of Trim9 in leukocyte chemotaxis, we disrupted Trim9 function in zebrafish macrophages through expression of a truncated form of Trim9 that lacks the RING domain required for ubiquitin ligase activity (ΔRING-Trim9). Expression of ΔRING-Trim9 results in significantly reduced in vivo chemotaxis of zebrafish macrophages, while overexpression of full-length Trim9 under the same conditions does not. Further, macrophages expressing ΔRING-Trim9 exhibit altered morphology with reduced pseudopod formation. We propose that Trim9, through its ubiquitin ligase activity, may mediate cytoskeletal dynamics necessary for macrophage chemotaxis. Identifying Trim9 substrates and binding partners within macrophages may provide new therapeutic strategies for modulating inflammation.
Intracellular glycogen reserves fuel early glycolytic metabolism associated with dendritic cell maturation and immune function.
Authors: Amiel Eyal , Thwe Phyu M. 
Published: January 2023

Abstract
Dendritic cells (DCs) serve as professional antigen presenting cells of the immune system. DCs activated by toll-like receptor (TLR) ligands undergo a process of maturation that is coupled with an increase in energy demand fulfilled by a TLR-driven burst in glycolytic metabolism. Up-regulation of glycolysis in activated DCs provides these cells with molecular building blocks and cellular energy required for DC effector function. Inhibition of glycolysis impairs both the survival and effector function of activated DCs. According to the prevailing model in the field, TLR-driven glycolysis in DCs is sustained primarily by increases in glucose uptake. We have characterized that DCs store glucose in the form of glycogen in the immature state and that glycogen functions as an intracellular energy reserve that is critical for early effector responses by these cells. Our data show that both human and mouse DCs express enzymes essential for glycogen metabolism and that glycogen synthesis is upregulated by inflammatory signals. In addition, we have observed that inhibition of glycogen metabolism significantly impairs key maturation parameters of these cells. Our findings indicate that glycogen metabolism in DCs plays an important role in supporting the effector function of these cells. This work uncovers a novel pathway for metabolic homeostasis in DCs and provides a new paradigm for how the metabolic requirements of DC activation are regulated.
Mild acidosis delays neutrophil apoptosis and enhances pro-survival signals from inflammatory mediators
Authors: Filep Janos G , de Oliveira Lima dos Santos Everton , Mansouri Soukaina , El Kebir Driss 
Published: January 2023

Abstract
Emerging evidence indicates that local acidosis associated with infection and tissue injury triggers innate and adaptive immunity. Activation of infiltrating neutrophils contributes to transient drop in pH. We investigated the impact of extracellular acidosis on neutrophil apoptosis, one of the check points in the outcome of the inflammatory response, and on the survival signals generated by bacterial DNA and serum amyloid A. Culture of human isolated neutrophils under mild acidosis (pH 6.5–7.0) resulted in concurrent activation of NF-κB, adenyl cyclase and the ERK and PI3K/Akt signaling pathways, leading to preservation of Mcl-1. Consequently, extracellular acidosis prevented disruption of mitochondrial transmembrane potential and translocation of cytochrome c, endonuclease G and apoptosis-inducing factor (AIF) from the mitochondria to cytoplasm and nuclei, respectively and attenuated activation of caspase-3. Pharmacological inhibition of ERK, PI3K, NF-κB and adenylcyclase partially reversed the anti-apoptotic action of acidosis. Furthermore, mild acidosis enhanced the pro-survival signal from bacterial DNA and serum amyloid A by enhancing ERK and PI3K-mediated inhibition of Mcl-1 degradation. Our results identify mild acidosis as a survival signal for neutrophils by suppressing the constitutive apoptotic machinery and suggest that transient decreases in local pH could contribute to amplification of inflammation.
Funding Support: Supported by grants from CIHR (MOP-97742).
Hepatocyte death induces TRIF-mediated sterile inflammation in the liver
Authors: Brempelis Katherine J , Yuen Sebastian , Mohar Isaac , Crispe Ian Nicholas 
Published: January 2023

Abstract
Hepatocyte death occurs as a result of infection, such as with hepatitis B and C viruses, and as a result of non-pathogen insults, such as chronic alcohol abuse, ischemia reperfusion injury, and acetaminophen overdose. The manner in which liver-specific cell populations—hepatocytes, resident macrophage Kupffer cells (KCs), and liver sinusoidal endothelial cells (LSECs)—respond to this death is critical to understand as the resulting immune response often results not in resolution, but in enhanced liver inflammation that can ultimately lead to fibrosis and cirrhosis. Using an adeno-associated virus vector (AAV) encoding the human diphtheria toxin receptor (hDTR), we have created a murine model of hepatocyte-specific death. After administration of diphtheria toxin (DT), we see peak liver damage at 48 hours, as measured by serum alanine aminotransferase (ALT) levels. This response is largely controlled by TIR-domain-containing adapter-inducing interferon-β (TRIF), independent of both Toll-like receptor 4 (TLR4) and Interferon alpha/beta receptor (IFNAR), and is characterized by the up-regulation of Ifn-beta in hepatocytes by 24 hours and the up-regulation of both monocyte- and neutrophil-recruiting chemokines from hepatocytes, LSECs, and KCs most strongly by 48 hours. We see TRIF-dependent up-regulation of adhesion molecules (Vcam1 and Icam1) on hepatocytes and LSECs and down-regulation of MHC-II on the surface of KCs. Understanding how the TRIF pathway controls responses to hepatocyte death provides an intriguing counterpoint when compared to other models of liver death—such as nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, and ischemia reperfusion injury—which occur via MyD88-dependent routes.
Roles of innate immune regulator TAPE in RIG-I signaling and antiviral defenses
Authors: Chen Kuan Ru , Yang Chia-Yu , Lin Chun-Yang , Lin Wan-Ying , Lo Yin-Chiu , Chuang Huai-Chia , Tan Tse-Hua , Ling Pin 
Published: January 2023

Abstract
Pattern-recognition receptors detect pathogen-associated molecular patterns to trigger downstream pathways leading to type I IFN and inflammatory cytokines production to defend pathogen infection. RIG-I-like receptors (RLRs) are key cytosolic sensors for recognizing viral RNA to trigger antiviral immunity. The underlying mechanisms linking RLR-mediated viral recognition to antiviral immunity remain to be further explored. Through our previous work, we uncovered an innate immune regulator termed TAPE (TBK1-Associated Protein in Endolysosomes), also known as CC2D1A, which is implicated in the viral RNA senor TLR3 and RLR pathways. Yet, the in vivo role of TAPE in antiviral defenses and the mechanistic mechanisms of how TAPE regulates cytosolic RIG-I signaling still remain to be established. TAPE conditional knockout mice were generated for our study. Results from in vivo studies showed that TAPEf/f CD11c-Cre mice exhibited a more severe mortality than WT mice upon influenza A virus (IAV) infection. Ex vivo studies also showed that TAPE-deficient mouse embryonic fibroblasts and macrophages were defective in type-I interferon induction upon RLR ligand stimulation. In addition, our biochemical analyses showed that the N-terminal region of TAPE was critical for interacting with the CARD domain of RIG-I while the C-terminal region of TAPE contributed most to the interaction with MAVS/IPS-1, a RLR downstream mediator. Together, our results suggest a crucial role for TAPE in linking RIG-I to type I IFN-mediated antiviral responses. Future work will further determine the in vivo role of TAPE in IAV and other RNA virus infection, and explore the mechanistic mechanisms of how TAPE regulates RIG-I signaling.
Innate immune signaling inhibition via disruption of adapter interactions.
Authors: Brown Lindsey J , Huyhn Kimberly , Satyarthi Divyam , Edwards Erin , Toshchakov Vladimir Y. , Snyder Greg A 
Published: January 2023

Abstract
Toll-like receptors (TLR) form homo- or heterodimers in response to pathogen-associated molecular patterns. The TLR homo- or heterodimers establish an intracellular signaling platform that recruits the signaling adapter protein Toll-Interleukin 1 Receptor (TIR) domain containing adaptor protein (TIRAP). This receptor-mediated platform initiates a signaling cascade which leads to NF-kB activation, cytokine production, and inflammation. Inflammation leads to pathogen clearance; however, excessive stimulation of the innate immune pathway can lead to injury and death. We are investigating mechanisms to disrupt TIRAP-mediated TLR signaling via two mechanisms: the bacterial TIR domain protein, TcpB from Brucella sp., and the decoy peptide, 2R9. We have previously determined the structures of TIRAP and TcpB. Presumably via molecular interactions with TIRAP, TcpB inhibited NF-kB activation. We now report surface plasma resonance binding of TIRAP with TcpB. The decoy peptide, 2R9, was derived from the TLR2 TIR domain D-helix. We have previously described interactions between 2R9 and TIRAP via surface plasma resonance. Based on the ability of 2R9 peptide to protect against lethality in response to acute influenza infection, 2R9 peptide could highlight a novel drug target to prevent injury and death caused by innate immune over activation. Using recombinant TIRAP with TcpB and 2R9 peptide, we are performing structural studies to characterize molecular interactions to identify putative sites for therapeutic intervention.
Keratinocyte Release of Alarmin HMGN1 Is triggered by Elevation of Intracellular Calcium
Authors: Yang De , Li Yana , Nie Yingjie , Trivett Anna , Oppenheim Joost J 
Published: January 2023

Abstract
Intra-nuclear high-mobility group nucleosome-binding 1 (HMGN1) functions as a chromatin modulator to regulate gene expression, whereas extracellular HMGN1 acts as an alarmin and contributes to the induction of antigen-specific immune responses. However, aside from passive release resulting from cell injury, it is unclear whether HMGN1 is released extracellularly by viable cells. In this study, we studied the cell type(s) capable of releasing HMGN1 and the underlying mechanism(s). Using a keratinocyte cell line KERTr, we found that ionomycin could induce the release of HMGN1 without changing its expression at the mRNA level. This release occurred in the absence of cell death. Other stimulants capable of elevating intracellular calcium such as ATP or SDF-1α also induced HMGN1 release. HMGN1 release was dependent on calcium/calmodulin and JAK2. The capacity of ionomycin and ATP to induce HMGN1 release was confirmed using cultured primary keratinocytes. Interestingly, macrophages could not release HMGN1 in response to these diverse stimuli. Thus, HMGN1 is preferentially released by keratinocytes, but not by leukocytes such as macrophages, in response to elevation of intracellular calcium.