bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resistance of macrophages to pore-forming toxins might depend on MEK1/2 and MLK3 activity
Authors: Ray Sucharit , Keyel Peter A. 
Published: January 2023

Abstract
Necrotizing soft tissue infections (NSTIs) are lethal bacterial infections that quickly spread through soft tissues. Virulence factors in NSTIs include pore-forming toxins (PFTs) like Streptolysin O and Perfringolysin O secreted by Streptococcus pyogenes and Clostridium perfringens. These PFTs form large transmembrane pores on host cells leading to cell death. Cells resist death through several poorly understood membrane repair mechanisms, including ceramide generation. Membrane repair is necessary for macrophages to survive and to eliminate PFT-secreting bacteria. Interestingly, macrophages are ~10–20 times more resistant to PFTs than most cells, but this mechanism of increased resistance is unknown. One possibility is that MAP kinase signaling enhances repair because ceramide can signal in other systems through a MAP kinase cascade involving Mixed-Lineage Protein Kinase 3 (MLK3), Mitogen-Activated Protein Kinase Kinase 1/2 (MEK1/2) and Jun amino-terminal kinases (JNK). We tested if MLK3 and downstream kinases MEK1/2, JNK, and Extracellular Signal-Regulated Kinase 1/2 (ERK1/2) contribute to the repair mechanism in cells. We treated immortalized cell lines or murine bone marrow derived macrophages with either the MEK1/2 inhibitor U0126, the JNK inhibitor SP600125, or the MLK3 inhibitor URMC099, challenged cells with Streptolysin O or Perfringolysin O and measured cell death by flow cytometry. Inhibition of MEK1/2 or MLK3, but not JNK, made cells ~2-fold more sensitive to killing by toxins. Overall, these findings suggest that MEK1/2 activation contributes to a general mechanism of membrane repair. Enhancing this mechanism could provide new tools for protecting cells from PFTs during NSTIs.
Neutrophil cathepsin G inhibits hapten-presenting dendritic cell production of IL-12 and skewing of hapten-reactive CD4 T Cell development to IFN-γ- and IL-17-producing effector cells in allergic contact sensitivity
Authors: Kish Danielle , Min Susie , Fairchild Robert L. 
Published: January 2023

Abstract
Contact hypersensitivity (CHS) is a CD8 T cell-mediated response to hapten skin sensitization and challenge. Sensitization of WT mice induces hapten-reactive CD8 cells producing CHS effector cytokines IFN-γ/IL-17 and IL-4-producing CD4 cells that cannot mediate CHS. Although CXCR2-dependent Gr-1+ cell recruitment into hapten challenged skin is required to direct effector CD8 T cell infiltration to elicit CHS, sensitization of CXCR2−/− mice or neutrophil-depleted WT mice induced both hapten-reactive CD4 and CD8 cells producing IFN-γ and IL-17. CD4 T cell-mediated CHS responses were not generated during hapten sensitization of neutrophil depleted WT mice treated with anti-IL-12 mAb or neutrophil depleted IL-12−/−mice. Neutrophil depletion during hapten sensitization of WT mice markedly increased numbers of IL-12-producing hapten-primed dendritic cells (DC), DC-derived p40, and T-bet-expressing CD4 T cells in the skin-draining lymph nodes. Sensitization of mice lacking the neutrophil serine protease cathepsin G induced hapten-reactive CD4 and CD8 T cells producing IFN-γ and IL-17 with elevated and elongated CHS responses to challenge. Few Gr-1+ cells were detected in the skin draining lymph nodes following senstization suggesting this regulation may not be mediated through direct Gr-1-DC interactions. In support of this, induction of CHS effector CD4 T cells producing IFN-γ in neutrophil-depleted WT mice was eliminated by subcutaneous injection of active, but not inactivated, cathepsin G during sensitization. Thus, hapten skin sensitization induces neutrophil release of cathepsin G that systemically inhibits hapten-presenting dendritic cell production of IL-12 and the development of CHS effector CD4 T cells.
A double edge function of type 17 immunity in Streptococcus pneumoniae pathogenesis during a co-infection with Influenza A Virus
Authors: Khan Nadeem , Sohail Ifrah , Schmit Taylor , Jacobson Brenden 
Published: January 2023

Abstract
Streptococcus pneumoniae (Spn) is a respiratory pathogen responsible for significant global disease burden (otitis media, pneumonia, sepsis). Despite success with current Pneumococcal Conjugate Vaccines, a significant proportion of humans remain colonized with Spn, rendering them at risk for developing Spn infections. Upper respiratory nasopharyngeal (NP) colonization by Spn is a precursor to disease, and viral induced inflammation is a key risk factor for the transition of commensal colonization to disease pathogenesis.
We utilized a mouse co-infection model of Spn and influenza virus to determine the role of virus induced acute inflammation in the transition of Spn colonization to disease pathogenesis. We show that early Spn NP colonization is allowed by an immune quiescence state, maintained by the lack of IL-17 expression. Introduction of influenza virus in Spn colonized mice elicits a robust IL-17 driven inflammatory response, which induces robust neutrophilia and tissue damage in the NP. The IL-17 mediated inflammatory response was associated with a significant increase in Spn NP bacterial density, leading to Spn invasion and bacteremia. Antibody mediated neutralization of IL-17 suppressed NP inflammation and bacterial density and prevented bacteremia. IL-17 receptor expression was also detected in nasal myeloid cell infiltrate. RoRγt-KO mice remained protected from bacteremia, mimicking the reduced pathogenesis of IL-17 neutralized WT mice. Using RoRγtGFP mutant mice, we detected the recruitment of GFP expressing RoRγt cell population in NP lavages and nasal associated lymphoid tissues.
We conclude that IL-17 blockade could contain influenza induced NP pathology and protect against Spn invasive pathogenesis.
AMP-activated kinase (AMPK) promotes innate immunity and antiviral defense against Zika virus induced ocular infection
Authors: Kumar Ashok , Singh Pawan Kumar , Giri Shailendra 
Published: January 2023

Abstract

Purpose
We recently reported that Zika Virus infected multiple retinal cell types and caused chorioretinal atrophy in mouse eyes. In this study, we investigated the potential role of AMPK, a master regulator of cellular metabolism, in pathogenesis of ocular ZIKV infection.

Methods
Primary human RPE cells were infected with ZIKV for various time points and AMPK phosphorylation was detected Western blotting (WB). AMPK activity was modulated by pharmacological activators (AICAR and Metformin) and inhibitors (Compound C) of AMPK. ZIKV replication was assessed by immunofluorscence staining for 4G2 and western blot detection of NS3 proteins. For in vivo studies B6 mice eye were challenged with ZIKV with or without AICAR treatment and disease progression were measured by fundus imaging. Activation of innate immune and antiviral response genes was assessed by qPCR.

Results
ZIKV challenge upregulated the AMPK phosphorylation in Pr. RPE cells in a time-dependent fashion. Our results indicate that AMPK deficient mouse embryonic fibroblast (MEF) cells were more permissive to ZIKV replication as compared to WT MEFs. AMPK activation using AICAR and Metformin restricted ZIKV replication in Pr. RPE cells and presence of Compound C reversed the effect of AICAR/Metformin. In vivo AICAR treatment ameliorated ZIKV-induced chorioretinal atrophy in mice with increased antiviral responses. ZIKV infection leads to activation of MEK pathways and an MEK pathways inhibitor, U0126, attenuated ZIKV replication.

Conclusion
Collectively, these findings indicate the AMPK activation evokes antiviral innate responses and restricts ZIKV replication. Hence, targeting AMPK signaling can be explored to develop anti-viral therapy against ZIKV infection.
Glycyrrhizin (GL) modulates HMGB1/miR-222-associated M2bMφ polarization and improves host antibacterial resistance of γ-irradiated mice against gut bacteria-associated sepsis
Authors: Ito Ichiaki , Loucas Bradford D. , Suzuki Sumihiro , Kobayashi Makiko , Suzuki Fujio 
Published: January 2023

Abstract
M2bMφ demonstrated in the mesenteric lymph nodes (MLNs) of whole body γ-irradiated mice (WBI-mice) have been characterized as responsible cells for the increased susceptibility of them to gut bacteria-associated sepsis. In our previous studies, MLN-Mφ from WBI-mice treated with GL have been characterized as non-M2bMφ. In this study, we determined how GL suppresses the γ-irradiation-associated M2bMφ polarization. WBI-mice were treated with GL (10 mg/kg, i.p., twice a day) 8 and 9 days post-irradiation. The antibacterial resistance of WBI-mice to Enterococcus faecalis oral infection (a model of sepsis caused by bacterial translocation) was evaluated by a bacterial growth in organs. F4/80+ cells (Mφ) were isolated from NMLs of GL-treated WBI-mice 10 days post-irradiation, and analyzed for the expression of miR-222 and GAS5 by real-time PCR. Serum HMGB1 level was measured by ELISA. In the results, the pathogen vigorously grew in various organs of WBI-mice, while the bacteria did not grow in organs of the same mice treated with GL. HMGB1, increased in sera of WBI-mice 2–15 days post-irradiation, stimulated the expression of miR-222 with a function to degrade GAS5 RNA (a factor to control the M2bMφ polarization). However, miR-222 was not expressed in the same Mφ cultures supplemented with GL. GL has been shown to bind to HMGB1 directly and inhibit its cytokine activity. The reduction of GAS5 and the M2bMφ polarization were not demonstrated in Mφ from WBI-mice treated with GL. These results suggest that GL improves host antibacterial resistance of WBI-mice against gut bacteria-associated sepsis through the modulation of HMGB1/miR-222-associated M2bMφ polarization.
Heterogeneous ribonucleoprotein M influences specific cytokine outcomes upon Salmonella Typhimurium infection
Authors: West Kelsi , Patrick Kristin L. , Watson Robert O. 
Published: January 2023

Abstract
A complex and dynamic regulatory system is needed to fight infection while also preventing induction of inflammatory disease. In macrophages, much is known about how pathogens modulate the innate immune transcriptional response. However, the significance of alternative splicing and manipulation of splicing factors upon infection remains unclear. We have identified several splicing factors that are differentially phosphorylated upon Salmonella Typhimurium bacterial infection, strongly suggesting an important role for RNA processing in the regulation of innate immune responses. A major family of identified phosphorylated splicing factors was the hnRNP (heterogeneous ribonucleoprotein) RNA binding factors, which contribute to multiple aspects of nucleic acid metabolism. Upon LPS stimulation and Salmonella Typhimurium infection, we have found that one of these proteins, hnRNPM, modulates expression of an inflammatory cytokine, IL-6. We have also identified hnRNPM binding sites within the introns of IL-6. We are currently investigating how hnRNPM localizes to chromatin, how hnRNPM intron recognition regulates IL-6 transcript levels, and how the phosphorylation of hnRNPM influences these processes.
Therapeutic potential of staphylococcal superantigen-like protein 7 for acute complement activation mediated diseases
Authors: Li Yan , Lin Feng 
Published: January 2023

Abstract
Previous studies have demonstrated that staphylococcal superantigen-like protein 7 (SSL7), a protein produced by the opportunistic bacterial pathogen Staphylococcus aureus, potently inhibits the formation of the complement membrane attack complex and release of C5a by binding to complement component 5 (C5). However, because of the predicted immunogenicity of SSL7 in humans, its potential as a new complement inhibitor for treating Complement-Mediated Diseases were uncertain. In this study, we found that administration of SSL7 efficiently protected red blood cells from complement-mediated lysis and reduced hemoglobinuria in a mouse model of paroxysmal nocturnal hemoglobinuria (PNH).
Interestingly, at the dose required for effective complement inhibition in vivo, although repetitive administrations of SSL7 once every other week for six weeks elicited anti-SSL7 antibody production, SSL7 was still able to attenuate acute complement activation mediated Hemolysis and hemoglobinuria significantly in these mice. In addition, anterior chamber administration of SSL7 before repeatedly treating mice with SSL7 suppresses the production of SSL7-reactive antibodies and retain the treatment efficacy of SSL7. These results suggest that SSL7 could thus be developed as an economical alternative to the existing C5-targeted drug eculizumab, especially for controlling acute complement activation in catastrophic conditions such as drug-induced immune hemolytic anemia, ABO-incompatible red blood cell, transfusion, and cardiopulmonary bypass surgery.
cGAS-STING activation in Ly6Chi monocytes induces IFNg during pulmonary pneumococcal infection
Authors: Patel Seema , Tucker Heidi R. , Mansouri Samira , Blaauboer Steven M. , Jin Lei 
Published: January 2023

Abstract
Streptococcus pneumoniae is the most common cause of pneumonia, resulting in high morbidity and mortality worldwide despite advanced antimicrobial therapies and vaccines. Human individuals with constitutively active STING mutations have recurrent pneumococcal infections. Moreover, we found that mice lacking STING expression are more resistant to pulmonary S. pneumoniae infection compared to their wild-type controls. Here we investigated the role STING in the pathogenesis of pulmonary pneumococcal infection. We discovered two waves of IFNg production in the lung and IFNg at 48hrs, but not at 24hrs post-intra-nasal S. pneumoniae infection (hpi) is STING dependent. Using STING conditional knockouts, CCR2−/− and GREAT (interferon-Gamma Reporter with Endogenous polyA Transcript) mice, we found Ly6Chi monocytes to be the major contributors of lung IFNg production at 48hpi. Further, IFNg production requires cGAS-STING signaling pathway in Ly6Chi monocytes. IFNg stimulates inflammatory M1 macrophage polarization. We found STING−/− lung macrophages exhibit anti-inflammatory M2 like phenotype. We propose that cGAS-STING induces late stage IFNg in Ly6Chi monocytes to promote M1-like macrophage differentiation and exacerbate the pulmonary pneumococcal infection. Our novel findings a) Two distinct waves of IFNg production, b) cGAS-STING pathway in Ly6Chimonocytes but not macrophages induce lung IFNg production at 48hpi. How cGAS-STING signaling pathway induces IFNg production in monocytes will be discussed. The findings of this project will add substantial information to the role of IFNg in the host defense mechanism against S. pneumoniae and help design more effective treatment options.
Eomesodermin promotes a central memory phenotype in CD8+ T cells through the induction of IL-10.
Authors: Reiser John , Gerber Allison , Sadashivaiah Kavitha , Furusawa Aki , Banerjee Arnob , Singh Nevil J. 
Published: January 2023

Abstract
Following an immune response, a fraction of antigen-specific T cells persist as memory cells. Of these, central memory CD8+ T cells (TCM), which express secondary lymphoid organ-homing molecules and self-renew efficiently, are critical for maintaining long term memory. High levels of the T-box transcription factor Eomesodermin (Eomes) are associated with the TCM phenotype, but the mechanisms by which Eomes controls different aspects of TCM function are poorly understood. Using Eomes-knockout (EKO) CD8+ T cells, we demonstrate that Eomes regulates the expression of a number of TCM-associated markers including Bcl6, Ly6C and CD62L. In addition, we found that Eomes promotes the expression of IL-10 in activated CD8+ T cells. Interestingly, the addition of exogenous IL-10 was sufficient to upregulate CD62L expression in WT cells. Taken together, our data suggest that Eomes uses IL-10 to promote at least part of the central memory phenotype in CD8+ T cells. Consistent with this model, we find that TCM are secreting IL-10 in vivo, without additional re-stimulation. These findings warrant a modified model of TCM differentiation which includes distinct roles for Eomes and IL-10 in a T cell-intrinsic program driving TCM formation.
Immune impact of tick-borne co-infections on canine leishmaniosis
Authors: Scorza Breanna , Toepp Angela , Mahachi Kurayi , Petersen Christine 
Published: January 2023

Abstract
Visceral leishmaniasis (VL), a zoonotic protozoal disease, kills an estimated 20,000 people annually (WHO, 2012). Dogs are the primary reservoir for parasite transmission to humans and clinical status correlates with infectiousness to sand fly vectors. Like humans, progression from asymptomatic to symptomatic CanL disease is accompanied by loss of CD4+ T cell responsiveness to Leishmania antigen. The molecular signals driving exhaustion in either species are poorly understood. Intriguingly, within a naturally-infected cohort of 174 dogs with CanL, asymptomatic dogs were 9.9× more likely to progress to clinical leishmaniosis if seropositive for ≥2 tick-borne co-infections (TBCs) over a six-month study period (p=0.0071). In Brazil, where dogs are a predominant reservoir for human VL, 80% of dogs were found to be seropositive for at least one TBC. We hypothesize that TBCs cause acute systemic inflammation in Leishmania-infected asymptomatic dogs, which promotes T cell exhaustion and symptomatic CanL. To evaluate this hypothesis, Type 1 immunity (circulating CD4 and CD8+ T cell proliferation, cytokine production, and inhibitory receptor expression in response to Leishmania antigen stimulation ex vivo and peripheral NK cell phenotypes) and clinical progression of CanL (complete blood count, blood chemistry panel, and clinical signs of CanL) will be compared in Leishmania infantum-infected dogs negative for TBCs or seropositive for Anaplasma spp., Ehrlichia spp., and/or Borrelia spp. These data may provide new strategies to prevent disease progression in dogs or people already infected with Leishmania and lead to less parasite transmission to humans by decreasing canine reservoir host parasitemia.
IL-12 and IL-23 dependent NK cell response is essential for protective immunity against secondary Toxoplasma gondii infection
Authors: Ivanova Daria Leonidovna , Gigley Jason P. 
Published: January 2023

Abstract
Natural Killer (NK) cells can develop memory-like features and contribute to long term-immunity in mice and humans in response to viral infections. NK cells are critical for protecting against acute T. gondii infection. How they impact long-term immunity in response to the parasite and mechanism(s) involved is unknown. Using a vaccine-challenge model of parasite infection we addressed these questions. After lethal reinfection of vaccinated mice with or without NK cells, we find they are required for immune control of secondary parasite infection. Unexpectedly, secondary responses of CD4 and CD8 T cells are also reduced in the absence of NK cells during reinfection of vaccinated mice. NK cells mount a secondary response noted by increased IFNγ production, however, adoptive transfer and NK cell fate mapping reveal that T. gondii-experienced cells are not intrinsically different from naïve cells in persistence and ability to protect. This suggests a cell extrinsic mechanism controls protective NK cell response during secondary infection. Although NK cell IFNg is IL-12 dependent during acute T. gondii infection, using anti-IL-12p70 antibody or IL-12p35−/− mice we find that secondary NK cell response is not fully dependent upon IL-12. IL-23 depletion with anti-IL-23p19 in vivo also significantly reduces the secondary NK cell response suggesting both IL-12 and IL-23 are involved. Anti-IL-12p40 treatment, which blocks both IL-12 and IL-23, completely eliminates protective secondary NK cell response, supporting this hypothesis. These results identify a previously unknown protective role of NK cells during secondary T. gondii infection that is not only IL-12 dependent, but also requires IL-23 and may involve an interaction with T cells.
Dynamics of the T follicular helper response in Borrelia burgdorferi infection
Authors: Hammond Elizabeth M. , Olsen Kimberly , Baumgarth Nicole 
Published: January 2023

Abstract
Borrelia burgdorferi (Bb), the bacterial agent of Lyme disease, has evolved numerous immune evasion mechanisms that result in Bb persistence in mice, its natural host, following infection via tick-bite. IgG antibodies control Bb-tissue loads but cannot clear the infection. We previously observed abnormalities in T-dependent B cell responses in mice following infection. Specifically, we demonstrated premature germinal center (GC) collapse, a lack of affinity maturation, memory B cell and long-lived plasma cell responses, and Ig responses that were skewed toward IgM. Due to the central role of CD4+ follicular T helper (TFH) cells in initiating and maintaining GCs, we hypothesized that Bb infection causes TFH dysfunction. Since Bb-specific CD4 T cell responses have not previously been characterized, we first identified an I-Ab restricted epitope on Arthritis related protein (Arp) of Bb, and used tetramers to characterize these Bb-specific CD4 T cells by FACS. We observed a surprisingly robust induction of Arp-specific TFH by day 14 of infection, which was followed by a precipitous decline in total and Arp-specific TFH by day 21 that preceded the observed collapse of GC. In order to explain this sharp TFH decline we studied the expression of inhibitory receptors on TFH. We also followed the induction of FOXP3+ regulatory T follicular (TFR) cells, which are known to limit GC responses. Not only were we able to demonstrate induction of a significant population of TFR, we also found that expression of the inhibitory Programmed death receptor 1 (PD-1) was significantly higher on Arp-specific TFH compared to overall TFH. Our data suggest that overshooting TFH regulatory mechanisms may inhibit T-dependent B cell responses during Bb infection.
Helminth-induced B lymphocytes mediate control of IL-17 and emphysema through their production of RELMα
Authors: Chen Fei , Wu Wenhui , millman Ariel , Palma Mark , El-Naccache Darine W. , Lothstein Katherine E. , Gause William C. 
Published: January 2023

Abstract
The intestinal nematode parasite, Nippostrongylus brasiliensis (Nb), can cause emphysema and the mechanisms remain poorly defined. Here we show that emphysema develops as early as 7 days after Nb inoculation and is associated with increased gene expression of Il17a, as well as increases in type 2 cytokines Nb infection of Il17a−/− mice results in a less severe emphysematous pathology, and decreased neutrophil influx to the lung, with little effect on the development of the type 2 immune response. Surprisingly, Nb infection of B cell deficient Jh−/− mice results in a more severe emphysema at day 7, and as late as day 30, and is associated with higher numbers of neutrophils and increased expression of Il17a in the lung. Most of the B cells in the lung are B2 regulatory cells and are activated through IL-4R signaling. However, IL-10 and other regulatory cytokines typically associated with B regulatory cell function did not play a major role in this response. Instead, at early stages of the response B cells produced high levels of RELMa. Transfer of B lymphocytes from WT mice or Il10−/− mice, but not from Il4Rα−/− mice, or Relmα−/− mice to recipient Jh−/−mice restored the control of emphysema, decreased the influx of neutrophils, and downregulated IL-17A. Although macrophages also expressed RELMa, it was not upregulated until 4 days after inoculation, whereas B cells upregulated RELMa as early as day 3. These studies show that elevations in IL-17 trigger emphysematous pathology and reveal a novel role for helminth-induced B cells in controlling IL-17A and the severity of emphysema through their production of RELMa.