bluuebunny/crossref_metadata_2025_split huggingface dataset:
PCSK9 regulates LDL-dependent uptake of bacterial lipids by HepG2 cells through LDL receptor
Authors: Grin Peter , Dwivedi Dhruva J. , Liaw Patricia C. , Fox-Robichaud Alison E. 
Published: January 2023

Abstract

Introduction
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key negative regulator of lipid uptake through low-density lipoprotein (LDL) receptor (LDLR), and has recently been implicated in regulating cytokine production during sepsis. We hypothesize that PCSK9 affects cytokine production by regulating hepatic LDLR-mediated uptake of bacterial lipids, such as lipopolysaccharide (LPS) and lipoteichoic acid (LTA), and that this uptake is LDL-dependent.

Methods
HepG2 cells were cultured in media containing normal serum or lipoprotein-deficient serum (LPDS), and pre-treated with recombinant human PCSK9 or control, and with control IgG, or anti-LDLR antibody. HepG2 cells were also cultured in LPDS with add-back of increasing LDL concentrations. Cells were then treated for 24 h with fluorescent LPS or LTA, or controls. Media was collected for cytokine assays, and flow cytometry was performed to quantify LPS or LTA uptake by measuring fluorescence.

Results
HepG2 cells pre-treated with recombinant PCSK9 or anti-LDLR antibody had significantly decreased fluorescent LPS and LTA uptake compared to controls when cultured in normal serum. Furthermore, cells pre-treated with both anti-LDLR antibody and PCSK9 showed similar uptake as cells treated with anti-LDLR antibody alone. Neither anti-LDLR antibody nor PCSK9 had any effect on cells cultured in LPDS, but LDL add-back dose-dependently increased uptake of both LPS and LTA. Varying uptake of LPS and LTA did not affect secretion of IL-6, IL-8, IL-10, or IL-17 by HepG2 cells.

Conclusion
Bacterial lipid uptake by HepG2 cells through LDLR requires LDL, and is negatively regulated by PCSK9, but does not affect cytokine production by these cells.
Fasciola hepatica Glutathione S-tranferase suppresses the expression of inflammatory cytokines from murine macrophages in vitro and boosts the survival rate of C57Bl/6 mice against lethal doses of lipopolysaccharide
Authors: Aguayo Vasti M. , Colón Edwin , Espino Ana 
Published: January 2023

Abstract
Fasciola hepatica, a world-wide parasitic helminth, is a well-known master of immunomodulation. The survival of this parasite in the mammalian host is highly dependent on its ability to avoid immune responses of the host for which the parasite employs excretory-secretory products (ESPs). Glutathione S-transferase (GST), one of the proteins in the repertoire of parasite ESPs, is an enzyme recognized for its anti-oxidant properties. GST has been studied as a vaccine candidate against animal fascioliasis, but its role in the immunomodulation has been poorly studied. In a previous study, we demonstrated that GST alone incites no activation of the nuclear factor NF-κB, yet it can suppress NF-κB when THP1-CD14 cells are exposed to GST 30 minutes before stimulation with TLR ligands. In this study, we investigate whether GST could exert a similar suppressive effect on NF-κB activation in THP1-CD14 cells when added several hours after TLR-ligand stimulation and if GST is able to suppress the expression of inflammatory cytokines in bone marrow derived macrophages (bmMØs) from naïve mice induced by LPS. Finally, we performed in vivo experiments to investigate whether one 200ug intraperitoneal (IP) injection with GST could increase the survival rate of C57BL/6 mice exposed to a lethal dose of LPS. Our results demonstrate that 10ug of GST on THP1-CD14 cells up to 3 hours after TLR-ligand stimulation significantly suppressed (p≤0.01) NF-kB activation. GST also suppressed the expression of TNF-α and IL-1β cytokines (p&lt;0.05) in bmMØs in a dose dependent manner. Importantly, a single IP injection of GST boosted the survival rate of mice by 80% against lethal doses of LPS, suggesting GST is an anti-inflammatory molecule.
Vasoactive intestinal peptide receptor - 1 deficiency causes an increase in the frequency of antibiotic producing bacteria in mouse fecal samples
Authors: Huber Benjamin , Bains Matt , Laney Caleb , Brooks Amanda , Dorsam Glenn P 
Published: January 2023

Abstract
New antibiotic discovery is critical because bacteria are becoming resistant to currently prescribed antibiotics. A mammalian gut peptide, vasoactive intestinal peptide (VIP), is highly expressed in the gut and possess antimicrobial activity. VIP binds two receptors, designated VPAC1 and VPAC2, and deficiency in all three have been shown to cause significant gut microbiota dysbiosis. We hypothesized that mice deficient for VIP signaling would be good candidates for exploring the existence of novel antibiotic-producing bacteria (APB). To this end, bacteria fecal samples from C57Bl/6 wild type (WT), and heterozygous (HET) and/or homozygous mutant (KO) VIP, VPAC1 and VPAC2 strains were used to test for zones of inhibition against escape pathogens. Our results showed that heterozygous VPAC1 mice resulted in the greatest increase in APB compared to WT controls, VIP or VPAC2 genetically altered strains. Initial taxonomic identification of APB from VPAC1 Het fecal samples reveled previously characterized aerobic bacteria. We conclude that reduction in VPAC1 receptor signaling in the gut, as opposed to loss of the VIP ligand or VPAC2 signaling, elevates the frequency of aerobic APB. Future studies will now focus on utilizing VPAC1 WT, HET and KO littermates to mine for the existence of novel anaerobic APB.
MAIT cells: Shaping the microbiome, contributing to Clostridium difficile infection
Authors: Smith Ashley Dawn , Zhang Irma T , Schubert Alyxandria M , Giordano Nicole P , Hastie Jessica E , Cowley Siobhan C , Carlson Paul E 
Published: January 2023

Abstract
Clostridium difficile (Cd) is a leading cause of nosocomial infection. Cd infection (CDI) typically occurs following antibiotic usage, which perturbs the gut microbiota leaving the host susceptible to Cd colonization. Mucosa-associated invariant T cells (MAIT) cells recognize intermediates of riboflavin biosynthesis presented on MR1, an MHC-I like related molecule. MAIT cell development is dependent on the host microbiome. MAIT cells are found in high numbers at mucosal sites and are beneficial in combatting various pulmonary infections; however their role in gut infections is unknown. We hypothesized that MAIT cells would play a role in controlling CDI. To test this hypothesis, WT and MR1−/−(lacking MAIT cells) mice were treated with antibiotics and then infected with Cd spores. Stool was collected and plated to determine Cd colonization levels for several days post-infection. Contrary to our hypothesis, MR1−/− mice showed no signs of disease or detectable levels of Cd colonization. More pathogenic strains of Cd were also tested and MR1−/− mice remained resistant. Fecal microbiota transplantation (FMT) was conducted to determine the role of the microbiota in this resistance phenotype. Susceptible WT mice given FMT from MR1−/− mice experienced dramatically lower colonization levels by day 7 and cleared detectable Cd by day 14, while WT mice given control FMT continued to exhibit high colonization levels. 16S rRNA sequencing of fecal samples from each strain revealed inherent phylum level differences in relative abundance of Bacteroidetes, Firmicutes, and Verrucomicrobia after antibiotics and FMT. Our data suggest the MR1−/− gut microbiome is resistant to Cd colonization, and this resistance is transferrable via FMT.
Multiple layers of heterogeneity and subset diversity in human MAIT cell responses to distinct microorganisms, and to innate cytokines
Authors: Dias Joana , Leeansyah Edwin , Sandberg Johan K 
Published: January 2023

Abstract
Mucosa-associated invariant T (MAIT) cells are a large innate-like T cell subset in humans defined by invariant TCR Vα7.2 usage and expression of CD161. MAIT cells recognize microbial riboflavin metabolites of bacterial or fungal origin presented by the MR1 molecule. The extraordinary level of evolutionary conservation of MR1 and the limited known diversity of riboflavin metabolite antigens have suggested that MAIT cells are relatively homogeneous and uniform in responses against diverse microbes carrying the riboflavin biosynthesis pathway. The ability of MAIT cells to exhibit microbe-specific functional specialization has not been thoroughly investigated. Here, we found that MAIT cell responses against Escherichia coli and Candida albicans displayed microbe-specific polyfunctional response profiles, antigen-sensitivity and response magnitudes. MAIT cell effector responses against E. coli and C. albicans displayed differential MR1-dependency and TCR β-chain bias, consistent with possible divergent antigen sub-specificities between these microorganisms. Finally, while the MAIT cell immuno-proteome was overall relatively homogenous and consistent with an effector-memory-like profile, it still revealed diversity in a set of NK cell-associated receptors. Among these, CD56, CD84 and CD94 defined a subset with higher expression of the transcription factors promyelocytic leukemia zink finger (PLZF), Eomesodermin and T-bet and enhanced capacity to respond to IL-12 and IL-18 stimulation. Thus, the conserved and innate-like MAIT cells harbor multiple layers of functional heterogeneity as they respond to microorganisms or innate cytokines, and adapt their response patterns in a stimulus-specific manner.
Glucose metabolism regulates reactive oxygen species and nitric oxide production of macrophages in response to IFN-γ and Trypanosoma cruzi
Authors: Koo Sue , Szczesny Bartosz , Garg Nisha 
Published: January 2023

Abstract
Macrophages (mϕ) act as one of the prime barriers to Trypanosoma cruzi infection yet fail to achieve complete clearance of the parasite. The phenotypic diversity of mϕ include pro-inflammatory and immunomodulatory activated states which are supported by cytosolic glycolysis and mitochondrial oxidative phosphorylation (OXPHOS), respectively, for their differential functions.
We previously reported that murine mϕ (RAW264.7 or bone marrow-derived) infected with T. cruzi Sylvio strain (SYL) produce TNF-α, but low levels of reactive oxygen species (ROS) and nitric oxide (NO) and fail to switch to the glycolysis observed in the pro-inflammatory LPS/IFNG-induced mϕ. Pre-blockage of OXPHOS with the ATP synthase inhibitor, oligomycin, resulted in further suppression of NO in mϕ responding to SYL. These data suggested that SYL-infected mϕ may utilize mitochondrial metabolism as an initial activator of NO production.
Providing interferon-γ (IFNG) during SYL infection of mϕ shut down OXPHOS and produced ROS and NO as observed in pro-inflammatory controls by 18 hours posttreatment. We hypothesized that glycolysis was required for the activation of IFNG/SYL- and LPS/IFNG-induced ROS and NO in mϕ. We found that eliminating glucose from the culture media or inhibiting glucose uptake resulted in the failure of ROS and NO production, but sustained TNF-α release. The protein expression of the ROS-producing NADPH oxidase (NOX2) subunit, gp91phox, was not detected in SYL-infected mϕ although abundant in pro-inflammatory mϕ. These data suggest that glycolysis may regulate NOX2 activation in mϕ responding to inflammatory stimuli. How NOX2 function and NO release is controlled by glucose and mitochondrial metabolism in mϕ will be further discussed.
Reciprocal regulation of germinal center and regulatory B cell responses by IFNγ receptor-STAT1 signaling in TLR7 mediated autoimmunity
Authors: Chodisetti Sathi Babu , Domeier Phillip P. , Soni Chetna , Schell Stephanie L. , Fasnacht Melinda J. , Rahman Ziaur S.M. 
Published: January 2023

Abstract
Toll like receptor 7 (TLR7) plays a critical role in systemic autoimmunity. The mechanisms that fine-tune germinal center versus regulatory B cell response in TLR7 mediated autoimmunity remain unclear. Regulatory B cells that produce IL-10 (B10 cells) negatively regulate autoimmunity and infections. We report that TLR7 deficiency in non-autoimmune B6 and autoimmune prone B6.Sle1b mice showed increased IL-10 producing B10 cells. In contrast, B6.Yaa and B6.Sle1b.Yaa mice expressing an extra copy of TLR7 in the Yaa locus showed decreased percentage of B10 cells. TLR7 deficiency in B cells inhibited whereas an extra copy of TLR7 enhanced proliferation and cytokine expression of cocultured antigen specific CD4 T cells. Interestingly, B10 cells displayed highest IFNγR expression compared to other subsets of T and B cells. Whereas B6.Sle1b.Yaa mice lacked B10 cells and marginal zone compartment (MZ), B6.Sle1b.Yaa mice deficient in IFNγR (B6.Sle1b.Yaa/IFNγR−/−) restored these populations. Further, B6.Sle1b.Yaa/IFNγR−/− mice showed diminished spontaneous germinal center (Spt-GC) and serum autoantibody responses, and renal pathology compared to B6.Sle1b.Yaa control mice. Similar results were observed when B6.Sle1b and B6.Sle1b.IFNγR−/− mice were treated with TLR7 ligand, imiquimod. B10 and GC B cells exhibited higher STAT1 and T-bet expression than follicular B cells. Mice deficient in STAT1 and T-bet had significantly reduced GC and IgG2c Ab responses while retained intact B10 and MZ compartments upon imiquimod treatment, contrary to what was observed in wild type mice. Together, these data define the critical differential role of IFNγR, STAT1, and T-bet in GC B cell and B10 cell development in TLR7 mediated autoimmunity.
ENU-induced C-terminal truncation of Runx3 results in Th17-associated autoimmune colitis
Authors: Su Yu-Chia , Chen Yi-Ting , Chen Yu-Ling , Cheng Bing-Ho , Kung John T 
Published: January 2023

Abstract
Inflammatory bowel disease (IBD) is a common, chronic, progressive inflammatory intestinal disease in the world. The etiology of IBD is due to the imbalance of host immune responses to intestinal flora. Many human genes play the important role to induce improper immune responses, including IL-10, STAT3, IRGM, AGT16L1, NOD2 and RUNX3. It has been reported that homozygous Runx3-ko mice develop colitis spontaneously. However, homozygous Runx3-ko mice show very high mortality rate in the first 2 week of life, and are hard to study the role of Runx3 in the spontaneous colitis. A mouse pedigree (spontaneous colitis, SC) carried an ENU-induced Tyr301stop point mutation of Runx3, which resulted in a short form truncated form of Runx3. SC mice started to show spontaneous diarrhea after weaning. SC mice exhibited prominant enlargement of colon that revealed large amounts of inflammatory cells infiltration from mucosal to muscular layers. Immunofluorescent staining showed large amounts of CD4+ T cells involved in the inflammatory colon. Moreover, inflammatory colons of SC mice expressed higher mRNA levels of IL-17A, and serum IL-17A level were also upregulated in SC mice. In addition, SC CD4+ T cells expressed stronger IL-17A than WT CD4+ T cells after in vitro activation. Transfer of total SC CD4+ T cells into Rag1-ko host mice resulted in autoimmune colitis. In summary, C-terminal truncated Runx3 results in autoimmune colitis through elevated Th17 immune responses. Thus, the SC mouse model is a valuable tool for investigations on the effect of immune system upon spontaneous colitis.
Thiol isomerase ERp72 enhances the development of antibody-induced arthritis
Authors: Zhao Zhenzhen , Chen Fengwu , Wu Yi 
Published: January 2023

Abstract
Thiol isomerases control labile disulfide bonds that are important in cell activation, cytokine signaling and in a variety of diseases. However, their role in autoimmune diseases such as arthritis remains unknown. ERp72, a thiol isomerases which contains three highly conserved CGHC active motifs, is capable of oxidizing, reducing and isomerizing disulfide bonds. In this study, we generated a new knockout mouse strain deficient of ERp72 (ERp72−/−). Using K/BxN serum-transfer-induced arthritis model (STIA), we determined the role of ERp72 in the pathogenesis of arthritis. To induce STIA, ERp72+/+and ERp72−/− mice received intraperitoneal injection of 200μl K/BxN serum twice on day 0 and day 2. Severity of arthritis was evaluated by daily measurements of joint diameter and clinical scores. Compared with ERp72+/+ mice, ERp72−/− mice developed much more severe arthritis, their joint swelling diameter was significantly increased. Clinical scoring of hind paw edema and hyperemia showed similar results. As indicated by H&E and Safranin O staining, the joint tissue from ERp72−/− mice exhibits more severe synovial hyperplasia, inflammatory cell infiltration and bone erosion on day 12. To determine the role of ERp72 in regulation of cytokine production, we measured the profiles of proinflammatory cytokines. In the joint tissue of ERp72−/− mice bearing STIA, both IL-1β and IL-6 levels were markedly increased by more than 50% than that of ERp72+/+ mice. Interestingly, the basal level of proinflammatory cytokine TNF-α in ERp72−/− mice was significantly higher in that of ERp72−/− mice. Taken together, our observation demonstrates that ERp72 is a negative regulator of innate immunity and plays an important role in the development of arthritis.
CD11b activation protects against lupus nephritis by suppressing TLR-dependent IFN responses via AKT-FOXO3-IRF7
Authors: Khan Samia Q , Faridi Mohd. Hafeez , Trim Wenpu , Khaliqdina Shehryar , Cimbaluk David J. , Kaplan Mariana J. , Gupta Vineet 
Published: January 2023

Abstract
Genetic variations in the ITGAM gene (coding for CD11b) produce defective CD11b and associate with a risk for systemic lupus erythematosus (SLE, lupus). Elevated level of IFN I in circulation plays a pathogenic role and is a heritable risk factor for SLE. Whether variations in ITGAM are linked to high IFN I and whether CD11b activation could be a therapeutic strategy is unknown and is explored here. We measured serum IFN I activity in 171 SLE patients and report that three ITGAM variants significantly associate with elevated levels of IFN I in lupus, suggesting a direct link between reduced CD11b activity and elevated inflammation in patients. Given that ITGAM SNPs result in functionally deficient CD11b, we tested whether partial CD11b activation with small molecule agonist, leukadherin-1 (LA1) reduces IFN I responses and determined the underlying mechanistic pathways. CD11b activation with LA1 reduced TLR-dependent pro-inflammatory signaling in leukocytes and suppressed IFN I signaling via an AKT-FOXO3-IRF7 pathway. TLR-stimulated macrophages from CD11b SNP carriers showed increased basal expression of IRF7 and IFNB, as well as increased nuclear exclusion of FOXO3, which was suppressed by LA1. To test the efficacy of LA1 in vivo, we used the MRL/lpr mice that develop IFN I-dependent multi-organ lupus. LA1 treatment reduced IFN I responses and protected lupus-prone MRL/lpr mice from kidney injury. LA1-treated mice had reduced proteinuria, IgG renal immune complex deposition, and glomerular damage as compared to controls. LA1 suppresses TLR-stimulated overproduction of cytokines in vivo, which drives lupus pathogenesis. These findings suggest that pharmacological CD11b activation is a promising therapeutic strategy in human SLE.
Deficiency in Interleukin-1 receptor-associated kinase (IRAK) 4 activity attenuates manifestations of murine Lupus
Authors: Medvedev Andrei , Manavalan Tissa , Pattabiraman Goutham , Murphy Michael Bradford 
Published: January 2023

Abstract
IL-1R-associated kinase (IRAK) 4 mediates host defense against infections. As an active kinase, IRAK4 elicits full spectra of MyD88-dependent responses, while kinase-inactive IRAK4 induces a subset of cytokines and negative regulators whose expression is not regulated by mRNA stability. IRAK4 kinase activity is critical for resistance against Streptococcus pneumonia, but its role in autoimmunity is incompletely understood. In this study, we determined the role of IRAK4 kinase activity in murine lupus. Lupus development in BXSB male mice expressing the Y chromosome autoimmunity accelerator (Yaa) increased basal and Toll-like receptor (TLR) 4/7-induced phosphorylation of IRAK1, mitogen-activated protein kinases, p65 nuclear factor-κB (NF-κB), enhanced TNF-α and CCL5 gene expression in splenic macrophages, but decreased levels of Toll-interacting protein (Tollip) and IRAK-M, without affecting IRAK4 or IRAK1 expression. Mice harboring kinase-inactive IRAK4 on the lupus-prone Yaa background had reduced glomerulonephritis, splenomegaly, serum anti-nuclear antibodies, decreased numbers of splenic macrophages, total and TNF-a+ dendritic cells, activated T- and B-lymphocytes, and lower TNF-α expression in macrophages compared to lupus-prone mice with functional IRAK4. Furthermore, mice expressing kinase-inactive IRAK4 had decreased proteinuria and increased survival in the chemically-induced (pristine) lupus model. Thus, IRAK4 kinase activity significantly contributes to murine lupus and could represent a new target for therapeutic interventions.
Ectopic expression of innate immune protein Lipocalin-2 in probiotic Lactococcus lactis protects against environmental and gut inflammatory stressors
Authors: SAHA PIU , Chassaing Benoit , Yeoh Beng San , Viennois Emilie , Xiao Xia , Singh Vishal , Kennett Mary J , VIJAY-KUMAR MATAM 
Published: January 2023

Abstract
Overexpression of lipocalin-2 (Lcn2), an acute phase protein, has been demonstrated to enhance cellular resistance to oxidative stress in various mammalian cell lines, in addition to mediating anti-bacterial effects by sequestering bacterial siderophores (iron chelators). To investigate whether Lcn2 could be exploited to augment the stability and efficacy of probiotic bacteria, we have engineered the recombinant Lactococcus lactis (MG1363) that expresses the murine Lcn2 (LactisLcn2) and the empty plasmid (LactisCon). The expression of Lcn2 did not impair the growth of LactisLcn2, especially since L. lactis do not require iron for its growth. In contrast, the L. Lactis-derived Lcn2 was effective in mitigating the bioactivity of enterobactin (E. coli-derived siderophore) and inhibited the growth of E. coli in vitro. The sequestration of iron in LactisLcn2 could, in part, explain its ability to inhibit the iron-dependent growth of E. coli. Moreover, the Lcn2 expression also augments the capacity of LactisLcn2 to withstand various environmental stressors in vitro, including extreme pH, toxicity of bile salts, H2O2-, and myeloperoxidase-mediated bacterial killing. When administered into mice with DSS-induced acute colitis, LactisLcn2 was observed to survive better in the inflamed gut and provide superior mucoprotection against intestinal inflammation when compared with LactisCon. Overall, our findings suggest that Lcn2 expression can be exploited to augment the iron-scavenging capability and survivability of probiotic bacteria against adverse conditions, which could further enhance their efficacy to treat inflammatory bowel diseases.