bluuebunny/crossref_metadata_2025_split huggingface dataset:
NK cells support host survival and release IL-10 following polymicrobial sepsis
Authors: Jensen Isaac J , McGonagill Patrick W , Butler Noah S , Griffith Thomas S , Badovinac Vladimir P 
Published: January 2023

Abstract
The sepsis-induced cytokine storm, composed of both pro- and anti-inflammatory cytokines, leads to significant morbidity/mortality. However, the contrasting relationship between the biphasic cytokine storm components remains elusive. NK cells, whose pro-inflammatory IFNγ producing capability is well established, can also prevent immunopathology during systemic infection through anti-inflammatory IL-10 production. This bipolarity of NK cells positions them as a potential throughline for the biphasic components of sepsis. Thus, to precisely delineate the role of NK cells in sepsis utilizing a cecal ligation and puncture (CLP) model we observed diminished survival in NK-depleted mice, attributable to a prolonged cytokine storm. Notably, an increase in IL-15 was observed in NK-depleted mice suggesting that NK cells consume IL-15 during the cytokine storm. To interrogate the potential effect of IL-15, NK cells were treated in culture and with time switched from IFNγ production to IL-10 production. Further, NK cells were shown to have IL-15-dependent IL-10 production during sepsis and that IL-10 deficiency increased sepsis mortality. Importantly, we also observed elevated IL-10 production by NK cells from septic patients relative to healthy controls. Intriguingly, patients with the highest degree of sepsis-induced lymphopenia also had the greatest proportion of NK cell IL-10 production potentially indicating a relationship between the severity of sepsis and the need to counterbalance septic inflammation. These data demonstrate that NK cells limit sepsis-induced immunopathology by producing IL-10 in response to IL-15 during the cytokine storm and suggests a crucial role in balancing the biphasic components of sepsis.
The role of Toll-like receptor 2 and 9 in osteoclast responses to Staphylococcus aureus osteomyelitis
Authors: Petronglo Jenna Rose , Putnam Nicole , Ford Caleb , Curry Jacob , Cassat Jim 
Published: January 2023

Abstract
Staphylococcus aureus is the most common etiology of bone inflammation, or, osteomyelitis (OM). During S. aureus OM, difficulty of treatment is compounded by dysregulation of skeletal homeostasis, which alters the differentiation and function of skeletal cells, namely bone-building osteoblasts and bone-resorbing osteoclasts (OCs), to favor bone loss. Altered cytokine milieu and skeletal cell sensing of bacterial components contribute to this process. In systemic infection, Toll-like receptor (TLR) 2 and TLR9 are critical to antistaphylococcal immunity. Thus, in this study, we sought to determine the importance of TLR2 and TLR9 to the host response to S. aureus OM and to concomitant bone loss. Using in vitro assays, we discovered that S. aureus-induced OC differentiation proceeds in a TLR2-and TLR9-dependent manner. To confirm these findings in vivo, we surgically induced S. aureus OM in Tlr2−/− and Tlr9−/− mice. Despite increased mortality in Myd88−/− mice, we found TLR2 and TLR9 to be individually dispensable during S. aureus OM, with no difference in bacterial burdens nor in trabecular bone loss in femurs post-infection. Overall, our data suggest that redundancy in innate immune responses to S. aureus in bone renders TLR2 and 9 individually expendable in vivo. Because potentiation of these receptors in OCs may share compensatory downstream effects, we have begun in vivo experiments to examine bone loss and bacterial clearance in Tlr2/Tlr9−/− mice and in vitro assays to analyze S. aureus-induced cytokine production in Tlr2−/−, Tlr9−/−, and Tlr2/Tlr9−/− OCs. These findings support further studies into how bacterial stimulation and altered cytokine milieu contribute to dysregulated bone homeostasis during infection.
Immune fibroblasts are unconventional antigen presenting cells and nonprofessional phagocytes in Lyme arthritis
Authors: Lochhead Robert B , Danner Rebecca , Wahhab Amanda , Rouse Joseph 
Published: January 2023

Abstract
Synovial fibroblasts are the primary cell type in synovial tissue and are one of the first cell types involved in immune responses to Borrelia burgdorferi invasion of joint tissue. Recent studies of human Lyme arthritis have shown that synovial fibroblasts up-regulate numerous genes involved in T cell activation upon exposure to the Th1 cytokine IFN-gamma. However, animal model studies are required to better understand their role in host defense and pathogenesis in Lyme arthritis. Using primary synovial fibroblasts isolated from the tibiotarsal joint of C57BL/6 mice, we have found that fibroblasts stimulated with IFN-gamma and B. burgdorferi express MHC class II molecules, a number of costimulatory molecules, and effector cytokines involved in lymphocyte activation, including activation of CD4+ T cells and NK cells. MHC class II molecules isolated from stimulated fibroblasts contained MHC-II peptides, indicating that these cells are capable of presenting antigen to CD4+ T cells. Stimulation with IFN-gamma also reduced fibroblast migration, indicating these cells have impaired ability to repair damaged tissue. Synovial fibroblasts were also able to internalize B. burgdorferi in cell culture, indicating that these cells are capable of acting as nonprofessional phagocytes. Ongoing experiments will determine which lymphocyte subsets interact with inflammatory synovial fibroblasts, and whether these subsets are protective against B. burgdorferi invasion of joint tissue and/or arthritogenic. Together, these data indicate that immune fibroblasts are important in shaping tissue-specific immune responses to B. burgdorferi infection and subsequent inflammation.
Low density neutrophils as a potential biomarker of leprosy severity
Authors: Tavares Isabella Forasteiro , dos Santos Jessica Brandão , dos Santos Pacheco Fabiana , Gandini Mariana , Meyer Rafael Mariante , Moraes Milton Ozório , Schmitz Veronica 
Published: January 2023

Abstract
Erythema Nodosum Leprosum (ENL) is a recurrent acute inflammatory complication of leprosy affecting up to 50% of patients with multibacillary (MB) leprosy, and is treated with thalidomide. Although ENL is described as an immune reaction mediated by neutrophils, studies showing the direct role of neutrophils in ENL are still neglected. One subpopulation of low-density neutrophils (LDNs), present within the fraction of peripheral blood mononuclear cells (PBMC), is associated in the pathogenesis and severity of diseases like sepsis, lupus and tuberculosis. In this study, we characterized circulating LDNs in leprosy, highlighting their involvement in the development of ENL. First, we observed segmented/hypersegmented cells morphologically compatible to neutrophils in PBMC of nonreactional and ENL patients. By flow cytometry, we confirmed the elevated frequency of circulating LDNs (CD14−CD15+) in ENL patients compared to nonreactional. Also, the pattern of expression of neutrophil activation markers suggests a greater activation of LDNs during ENL. Treatment with thalidomide did not interfered the frequency of LDNs, but reduced their activation. Serum levels of MMP-9 (neutrophilic degranulation marker) were correlated with the frequency of LDNs. Finally, we revealed that Mycobacterium leprae (ML) induce generation of LDNs in whole blood and purified normal density neutrophils of healthy individuals in vitro. In brief, we showed that activated LDNs are elevated in the circulation of ENL patients, and may be originated by degranulation caused by ML stimulus. These results point the neutrophilic involvement in leprosy especially on ENL favoring the systemic inflammation and suggest LDNs as a biomarker in ENL development.
Regulation of human macrophage phenotype and GPBAR1 expression by cell seeding density and glucocorticosteroids
Authors: Hammerbeck Christopher , Goetz Christine , Peng Li , Constans Megan , Peterson Ryan , Astry Brian , Hudacek Andrew , Bonnevier Jody L 
Published: January 2023

Abstract
Macrophages are key mediators of tissue homeostasis and inflammation and do so by virtue of differential expression of secreted and cell surface proteins. Cytokines such as IFNγ or IL-4 and IL-13 are known to generate classical proinflammatory M1 and alternatively activated M2 macrophages, respectively, but it is less clear how cell density, cell-cell contact and corticosteroids work together to affect macrophage function. Corticosteroids such as cortisol are known to downregulate the inflammatory signaling but they can also alter the expression of cell surface proteins, such as CD163, on steady-state macrophages. Here we examined the effect of monocyte seeding density and cortisol on the expression of cell surface proteins on human macrophages.
The expression of the macrophage markers CD16, CD163, CD204 and VSIG4 were found to correlate with monocyte seeding density such that at low seeding densities, monocyte-derived macrophages were found to express minimal amounts of CD16, CD163, CD204 and VSIG4 while at high seeding densities, expression of these markers was restored. When cultured in the presence of cortisol, macrophages seeded at low densities were found to upregulate expression of these markers, but not CD204, to levels comparable to macrophages seeded at high densities grown in the presence of MCSF. Additionally, in the presence of cortisol, macrophages expressed higher levels of GPBAR1 which has also been shown to reduce classical proinflammatory macrophage activation in colitis models.
This data suggests that corticosteroids may regulate macrophage function by modulating the expression of cell surface proteins such as GPBAR1 and not just interfering with morer conventional inflammatory cell signaling pathways..
Leishmania donovani metacyclic promastigotes colonize inflammatory monocytes by impairing phagosome function
Authors: Matte Christine , Descoteaux Albert 
Published: January 2023

Abstract
Protozoan parasites of the Leishmania genus are the etiological agents of leishmaniasis, a debilitating disease with a wide spectrum of clinical symptoms ranging from self-healing ulcers to life-threatening visceral pathologies. These vacuolar pathogens are transmitted to mammalian hosts as metacyclic promastigotes by the bite of an infected sandfly. Parasites are then internalized by various phagocyte populations such as inflammatory monocytes. The nature of Leishmania-monocyte interactions over the course of infection and the specific role of these cells in pathogenesis are still unclear. Here, we aimed to investigate the impact of Leishmania donovani metacyclic promastigotes on inflammatory monocyte antimicrobial responses. Our results first show that these cells are highly permissive to L. donovani infection, while bacteria are rapidly eliminated. Upon internalization, L. donovani promastigotes inhibit phagosome acidification, as detected by confocal microscopy using the acidotropic probe LysoTracker. Furthermore, these parasites inhibit NOX2 assembly at the parasitophorous vacuole. Indeed, we found that the membrane-bound subunit gp91phox and the cytosolic subunit p47phox are excluded from the PV membrane. As a result, L. donovani metacyclic promastigotes prevent the production of reactive oxygen species within the PV, as detected using NitroBlue Tetrazolium. Permissiveness of inflammatory monocytes to L. donovani may thus be related to the ability of this parasite to impair the microbicidal properties of phagosomes. The virulence factors involved in these processes are currently being investigated.
Innate immune response changes during the progression of Alzheimer’s disease
Authors: Fulop Tamas , Munawara Usma , Catanzaro Michele , Frost Eric H 
Published: January 2023

Abstract
Alzheimer’s disease (AD) is the most frequent type of dementia. It is primarily a neurodegenerative disease but neuroinflammation plays an important role in the pathogenesis. The dementia develops over decades and progresses from health to AD via a Mild cognitive impairment (MCI) stage. Neuroinflammation precedes the development of the other pathological hallmarks like amyloid plaque formation. Monocytes and macrophages play an important role in neuroinflammation. The aim of the present work was to determine the phenotypes and functions of peripheral monocytes and macrophages, differentiated from these monocytes, through various stages of the disease from health via subjective memory complaints and MCI to mild AD. After informed consent, we enrolled 9 individuals into each of the four groups. We studied phagoburst (flow cytometry), chemotaxis (Boyden chamber), cytokine production (Luminex) and phenotypes (flow cytometry). The results showed a progressive decrease from the healthy group to the mild AD group in both free radical production as well as chemotaxis concomitantly with an increase in inflammatory cytokine production. There was also a shift towards the more inflammatory phenotype (intermediate) of monocytes from healthy to AD. In contrast, monocytes showed increased M2 phenotype in AD compared to healthy. The results demonstrated an increased inflammatory status during progression towards AD, however the various parameters of the innate immune system showed differential changes during this progression depending on their differentiation status.
Hippocampal damage and seizure severity during acute viral encephalitis are determined by the intensity of the infiltrating inflammatory monocyte response
Authors: LaFrance-Corey Reghann , Howe Charles L 
Published: January 2023

Abstract
The immunological response to CNS viral infection must balance the need for effective viral clearance with the need to preserve irreplaceable neurons. Failure to achieve this balance may result in death or severe cognitive impairment. We have observed hippocampal injury, compromised cognitive function, and seizures in C57BL/6 mice following acute infection with TMEV. We established that an initial innate immune response controlled by inflammatory monocyte infiltration into the brain is responsible for this neural injury. To better understand the pathogenic mechanisms involved in monocyte recruitment to the CNS we asked whether reducing the initial viral inoculum impacted the evolution of neural injury. We found that mice infected with standard (2×105 PFU) or low inoculum (1.25×104 PFU) TMEV exhibited a graded inflammatory response. Notably, a 16-fold reduction in viral inoculum resulted in 80% attenuation of the inflammatory monocyte response, concomitant with a 90% attenuation in acute production of CCL2 and complete abrogation of acute increases in TNFα and IL-6 in the hippocampus. Cognitive performance was preserved in low inoculum mice and seizure burden was highly attenuated. Despite the introduction of 16-times less virus, viral load in the brain was equivalent at 3 dpi between groups, indicating that the amount of replicating virus was not associated with reduced neuropathology. Our findings support a model in which the earliest host response to pathogen in the CNS shapes the size of the inflammatory response and constrains the downstream pathological sequelae.
CD169+ macrophages subsets are critical for regulating inflammation during sepsis
Authors: Yeung Stephen T , Khanna Kamal M 
Published: January 2023

Abstract
Sepsis affects more than 30 million people and accounts for approximately 6 million deaths worldwide each year. Current therapy consists of supportive care to keep organs functional and antibiotics to combat infections, with survival contingent on early detection. Our current knowledge of the cellular/molecular mechanisms that regulate the inflammatory pathways resulting in septic shock is limited. Notably, we know little about the precise populations of immune cells that play a central role during sepsis. To bridge these gaps in our knowledge, we examined the role of CD169+ macrophages in septic shock. We utilized both CD169-cre and CD169-diphtheria toxin receptor (DTR) mice to conditionally knockout (CKO) genes and selectively and temporally deplete CD169+ macrophage, respectively. We report that CD169+ macrophages, signaling pathways, and even the CD169 receptor is critical for protection against LPS shock. We show that in the absence of these macrophages, sensors, or the receptor; mice treated with sublethal LPS fail to survive and exhibit increased inflammatory cytokines and impaired IL-10 production. We also show that in the absence of these macrophages, mice exhibit increased dissemination of endotoxin to organs. Protection against LPS induced lethality is rescued by supplemental treatment with rIL-10. Lastly, we show that following LPS treatment, CD169+ macrophages are the initial targeted cell. These findings not only reveal a pivotal role for CD169+ macrophages and its sensing of LPS but also the role for the CD169 receptor as a critical mediator of protection from sepsis induced lethality, and provide new therapeutic targets against sepsis.
A genome-wide CRISPR/Cas9 screen identifies novel regulators of GSDMD pore formation in engineered macrophages
Authors: Evavold Charles Lee , Hafner-Bratkovic Iva , Jerala Roman , Kagan Jonathan C. 
Published: January 2023

Abstract
Cleavage of gasdermin D (GSDMD) by inflammatory caspases results in pore formation at the plasma membrane. GSDMD pores are recognized to mediate pyroptotic lysis of the cell or direct translocation of IL-1 family cytokines from the cytosol into the extracellular space depending on the quantity of pores or duration of plasma membrane occupancy. Hyperactive cells display evidence of fewer GSDMD pores compared to their pyroptotic counterparts, and recent work suggests that ESCRT-dependent membrane repair pathways oppose the cell fate towards pyroptosis through removal of GSDMD pores from the plasma membrane. To identify regulators of GSDMD pore formation at the plasma membrane, we utilized a genome-wide CRISPR/Cas9 screening platform in immortalized bone marrow derived macrophages (iBMDMs). This screen uncovered novel regulators of GSDMD pore formation in the plasma membrane.
Exosomes secreted from microglia during chronic virus infection can induce demyelinating disease
Authors: Luong Nhungoc H , Olson Julie K 
Published: January 2023

Abstract
Theiler’s murine encephalomyelitis virus (TMEV) induced demyelinating disease is a murine model for multiple sclerosis (MS). TMEV persists in microglia and leads to development of chronic progressive demyelinating disease associated with an inflammatory immune response in the central nervous system (CNS) of susceptible mice. TMEV-infected microglia secrete innate immune cytokines, chemokines, and effector molecules associated with development and progression of demyelinating disease. Recently, we have found that TMEV-infected microglia secrete nanovesicles called exosomes that contain and transfer viral RNA to bystander cells in the CNS. Our present studies show that exosomes secreted by microglia during TMEV-induced demyelinating disease (63–98dpi) contain viral RNA/genome that can be taken up by other CNS resident cells, transferring the viral RNA. More importantly, these exosomes could induce the bystander CNS cells to express inflammatory cytokines and chemokines. When administered into naïve mice, exosomes secreted by microglia during TMEV-induced demyelinating disease promoted MS-like pathology including microglia activation and demyelination in the spinal cord. These results suggest that exosomes secreted by infected microglia may directly contribute to the development and progression of demyelinating disease.
A road map of memory CD8+ T cell functional imprinting and fitness
Authors: Chin Shu Shien , Chorro Laurent , Achar Sooraj , Zehn Dietmar , Altan-Bonnet Grergoire , Delahaye Fabien , Lauvau Gregoire 
Published: January 2023

Abstract
Previous studies established that TCR signaling strength determines the size of CD8+ T cell expansion and memory pool. Here we hypothesized that TCR signaling strength further modulates the functional features of memory CD8+ T cells. We immunized mice transferred with naïve OT-I cells, which recognize the Ovalbumin (Ova)-derived epitope SIINFEKL, with Listeria monocytogenes expressing different variants, exposing OT-I cells to various TCR signaling strength. Transcriptomic analysis at early times after priming revealed that compared to OT-I cells primed with strong TCR signals, those primed with weak TCR signals upregulated genes involved in cell cycle (IL-2) and type I IFN response, suggesting that TCR signaling strength could determine how CD8+ T cells respond to cytokines at the time of priming. We postulated that disrupting cytokine signaling in T cells primed with weak TCR signals could alter memory T cell fate. As proposed, OT-I memory cells primed with weak TCR signals and lacking IL-2 or type I IFN cytokine signaling (Ifnar−/−, Il2ramut/mut) failed to re-expand upon secondary challenge compared to WT counterparts. Moreover, transcriptomic and epigenetic analyses of WT or Il2ramut/mut OT-I memory cells primed with strong versus weak TCR signals revealed that while gene expression remained similar, chromatin accessibility was significantly different. TCR and IL-2 signaling together regulate an epigenetic landscape reflecting a broad functional fitness of memory CD8+ T cells, whereas TCR signaling selectively imprinted an epigenetic landscape related to metabolism. These results suggest that epitope selection for effective CD8+ T cell vaccine design is pivotal to modulate the functional programming of memory T cells.
Enhanced ER stress responses accompany greater effector T cell functions with deficiency of PSGL-1
Authors: Bae Eun-ah , Hope Jennifer L , Otero Dennis C , Stairiker Christopher J , Faso Hannah A , Palete Ashley B , Bradley Linda M 
Published: January 2023

Abstract
Endoplasmic reticulum (ER) stress is induced by the accumulation of misfolded proteins and other cellular stresses, which lead to the unfolded protein response to restore ER homeostasis. Previous studies have shown that the ER stress response is required for T cell activation and differentiation. However, recent studies demonstrated that inhibition or deletion of ER stress mediators in T cells actually promotes anti-tumor immunity. Therefore, this incongruity as to the role of ER stress response in effector T cell function warrants further investigation. Our lab previously identified that the adhesion molecule, P-selectin glycoprotein ligand-1 (PSGL-1), acts as a T cell immune checkpoint regulator. PSGL-1-deficiency enhances T cell function, resulting in the clearance of chronic viral infection and dramatic tumor control. To better understand the contribution of ER stress to T cell function, we assessed T cell phenotype and function together with the ER stress mediators, XBP1s and ATF4, in highly-functional PSGL-1−/− T cells as well as exhausted wild-type T cells in both tumor and virus models. In melanoma models, ER stress was highly induced in activated tumor-infiltrating T cells (TILs). Effector CD8+ TILs producing IFNg displayed elevated XBP1s and ATF4 compared to IFNg− TILs. Upon chronic LCMV Cl13 viral infection in PSGL-1−/− mice, we found increased virus-specific T cells with enhanced multi-functional effector responses and increased memory/stem cell-like T cell populations characterized by the expression of the transcription factor TCF-1, as well as increased ER stress responses. Together, these data suggest that ER stress plays an essential role in effector T cell functions in settings of chronic antigen stimulation.