SARS-CoV-2 NSP5 antagonizes MHC II expression by subverting histone deacetylase 2.

SARS-CoV-2 interferes with antigen presentation by downregulating major histocompatibility complex (MHC) II on antigen-presenting cells, but the mechanism mediating this process is unelucidated. Herein, analysis of protein and gene expression in human antigen-presenting cells reveals that MHC II is downregulated by the SARS-CoV-2 main protease, NSP5. This suppression of MHC II expression occurs via decreased expression of the MHC II regulatory protein CIITA. CIITA downregulation is independent of the proteolytic activity of NSP5, and rather, NSP5 delivers HDAC2 to the transcription factor IRF3 at an IRF-binding site within the CIITA promoter. Here, HDAC2 deacetylates and inactivates the CIITA promoter. This loss of CIITA expression prevents further expression of MHC II, with this suppression alleviated by ectopic expression of CIITA or knockdown of HDAC2. These results identify a mechanism by which SARS-CoV-2 limits MHC II expression, thereby delaying or weakening the subsequent adaptive immune response.

In vivo tracking of adenoviral-transduced iron oxide-labeled bone marrow-derived dendritic cells using magnetic particle imaging.

BACKGROUND: Despite widespread study of dendritic cell (DC)-based cancer immunotherapies, the in vivo postinjection fate of DC remains largely unknown. Due in part to a lack of quantifiable imaging modalities, this is troubling as the amount of DC migration to secondary lymphoid organs correlates with therapeutic efficacy. Magnetic particle imaging (MPI) has emerged as a suitable modality to quantify in vivo migration of superparamagnetic iron oxide (SPIO)-labeled DC. Herein, we describe a popliteal lymph node (pLN)-focused MPI scan to quantify DC in vivo migration accurately and consistently. METHODS: Adenovirus (Ad)-transduced SPIO+ (Ad SPIO+) and SPIO+ C57BL/6 bone marrow-derived DC were generated and assessed for viability and phenotype, then fluorescently labeled and injected into mouse hind footpads (n = 6). Two days later, in vivo DC migration was quantified using whole animal, pLN-focused, and ex vivo pLN MPI scans. RESULTS: No significant differences in viability, phenotype and in vivo pLN migration were noted for Ad SPIO+ and SPIO+ DC. Day 2 pLN-focused MPI quantified DC migration in all instances while whole animal MPI only quantified pLN migration in 75% of cases. Ex vivo MPI and fluorescence microscopy confirmed that pLN MPI signal was due to originally injected Ad SPIO+ and SPIO+ DC. CONCLUSION: We overcame a reported limitation of MPI by using a pLN-focused MPI scan to quantify pLN-migrated Ad SPIO+ and SPIO+ DC in 100% of cases and detected as few as 1000 DC (4.4 ng Fe) in vivo. MPI is a suitable preclinical imaging modality to assess DC-based cancer immunotherapeutic efficacy. RELEVANCE STATEMENT: Tracking the in vivo fate of DC using noninvasive quantifiable magnetic particle imaging can potentially serve as a surrogate marker of therapeutic effectiveness. KEY POINTS: • Adenoviral-transduced and iron oxide-labeled dendritic cells are in vivo migration competent. • Magnetic particle imaging is a suitable modality to quantify in vivo dendritic cell migration. • Magnetic particle imaging focused field of view overcomes dynamic range limitation.

Correction: A vesicular stomatitis virus-based prime-boost vaccination strategy induces potent and protective neutralizing antibodies against SARS-CoV-2.

[This corrects the article DOI: 10.1371/journal.ppat.1010092.].

Identification and differential usage of a host metalloproteinase entry pathway by SARS-CoV-2 Delta and Omicron.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike glycoprotein (S) binds to angiotensin-converting enzyme 2 (ACE2) to mediate membrane fusion via two distinct pathways: 1) a surface, serine protease-dependent or 2) an endosomal, cysteine protease-dependent pathway. In this study, we found that SARS-CoV-2 S has a wider protease usage and can also be activated by TMPRSS13 and matrix metalloproteinases (MMPs). We found that MMP-2 and MMP-9 played roles in SARS-CoV-2 S cell-cell fusion and TMPRSS2- and cathepsin-independent viral entry in cells expressing high MMP levels. MMP-dependent viral entry required cleavage at the S1/S2 junction in viral producer cells, and differential processing of variants of concern S dictated its usage; the efficiently processed Delta S preferred metalloproteinase-dependent entry when available, and less processed Omicron S was unable to us metalloproteinases for entry. As MMP-2/9 are released during inflammation, they may play roles in S-mediated cytopathic effects, tropism, and disease outcome.

Magnetic Particle Imaging Is a Sensitive In Vivo Imaging Modality for the Detection of Dendritic Cell Migration.

PURPOSE: The purpose of this study was to evaluate magnetic particle imaging (MPI) as a method for the in vivo tracking of dendritic cells (DC). DC are used in cancer immunotherapy and must migrate from the site of implantation to lymph nodes to be effective. The magnitude of the ensuing T cell response is proportional to the number of lymph node-migrated DC. With current protocols, less than 10% of DC are expected to reach target nodes. Therefore, imaging techniques for studying DC migration must be sensitive and quantitative. Here, we describe the first study using MPI to detect and track DC injected into the footpads of C57BL/6 mice migrating to the popliteal lymph nodes (pLNs). PROCEDURES: DC were labelled with Synomag-D™ and injected into each hind footpad of C57BL/6 mice (n = 6). In vivo MPI was conducted immediately and repeated 48 h later. The MPI signal was measured from images and related to the signal from a known number of cells to calculate iron content. DC numbers were estimated by dividing iron content in the image by the iron per cell measured from a separate cell sample. The presence of SPIO-labeled DC in nodes was validated by ex vivo MPI, histology, and fluorescence microscopy. RESULTS: Day 2 imaging showed a decrease in MPI signal in the footpads and an increase in signal at the pLNs, indicating DC migration. MPI signal was detected in the left pLN in four of the six mice and two of the six mice showed MPI signal in the right pLN. Ex vivo imaging detected signal in 11/12 nodes. We report a sensitivity of approximately 4000 cells (0.015 µg Fe) in vivo and 2000 cells (0.007 µg Fe) ex vivo. CONCLUSIONS: Here, we describe the first study to use MPI to detect and track DC in a migration model with immunotherapeutic applications. We also bring attention to the issue of resolving unequal signals within close proximity, a challenge for any pre-clinical study using a highly concentrated tracer bolus that shadows nearby lower signals.

Inhibiteurs de Nef du VIH-1 : applications et développements pour une guérison efficace.

Résumé La thérapie anti-rétrovirale peut contrôler la réplication du virus de l'immunodéficience humaine de type 1 (VIH-1) chez les individus vivant avec le VIH. Par contre, ces traitements ne constituent pas une guérison et aucune approche pour une guérison du VIH-1 n'a encore montré de succès lors des études cliniques. Les approches de guérison sont souvent contrées in vivo par des barrières développées par le VIH-1. L'inhibition pharmacologique de la protéine accessoire Nef du VIH-1 représente une approche ambitieuse et prometteuse pour développer une nouvelle stratégie de guérison. Des petites molécules inhibitrices de Nef peuvent inverser les défauts reliés à l'infection par le VIH dans la signalisation des récepteurs des cellules T et les kinases, l'apoptose, l'autophagie et surtout, la présentation d'antigène. Ensemble, ces activités démontrent la grande capacité des inhibiteurs de Nef à être appliqués comme agents thérapeutiques dans un traitement contre le VIH-1. Dans cette revue, nous présentons les motifs pour lesquels Nef constitue une cible thérapeutique et nous soulignons les progrès effectués dans l'identification et le développement d'inhibiteurs de Nef.

Inhibitors of HIV-1 Nef: applications and developments for a practical cure.

Antiretroviral therapy can control human immunodeficiency virus type 1 (HIV-1) replication in people living with HIV; however, these treatments are not curative and no practical approach for an HIV-1 cure has yet shown success in clinical trials. Counteracting the multiple barriers HIV-1 presents against a practical cure is a direct means to functionalize these curative approaches in vivo. Pharmacological inhibition of the HIV-1 accessory protein, Nef, represents a particularly promising and ambitious approach, with Nef inhibitors holding the potential to reverse HIV-1-related defects in T cell receptor and kinase signaling, apoptosis, autophagy and most importantly, antigen presentation. Together, the capacity for Nef inhibitors to restore these activities underscores their potential as supportive agents in a practical HIV-1 cure. In this review, we outline a rationale for pharmacologically targeting Nef and review the progress made in the identification and development of Nef inhibitors.

KIM-1/TIM-1 is a Receptor for SARS-CoV-2 in Lung and Kidney.

SARS-CoV-2 precipitates respiratory distress by infection of airway epithelial cells and is often accompanied by acute kidney injury. We report that Kidney Injury Molecule-1/T cell immunoglobulin mucin domain 1 (KIM-1/TIM-1) is expressed in lung and kidney epithelial cells in COVID-19 patients and is a receptor for SARS-CoV-2. Human and mouse lung and kidney epithelial cells express KIM-1 and endocytose nanoparticles displaying the SARS-CoV-2 spike protein (virosomes). Uptake was inhibited by anti-KIM-1 antibodies and TW-37, a newly discovered inhibitor of KIM-1-mediated endocytosis. Enhanced KIM-1 expression by human kidney tubuloids increased uptake of virosomes. KIM-1 binds to the SARS-CoV-2 Spike protein in vitro . KIM-1 expressing cells, not expressing angiotensin-converting enzyme 2 (ACE2), are permissive to SARS-CoV-2 infection. Thus, KIM-1 is an alternative receptor to ACE2 for SARS-CoV-2. KIM-1 targeted therapeutics may prevent and/or treat COVID-19.

ß2 Integrin CD11d/CD18: From Expression to an Emerging Role in Staged Leukocyte Migration.

CD11d/CD18 is the most recently discovered and least understood ß2 integrin. Known CD11d adhesive mechanisms contribute to both extravasation and mesenchymal migration - two key aspects for localizing peripheral leukocytes to sites of inflammation. Differential expression of CD11d induces differences in monocyte/macrophage mesenchymal migration including impacts on macrophage sub-set migration. The participation of CD11d/CD18 in leukocyte localization during atherosclerosis and following neurotrauma has sparked interest in the development of CD11d-targeted therapeutic agents. Whereas the adhesive properties of CD11d have undergone investigation, the signalling pathways induced by ligand binding remain largely undefined. Underlining each adhesive and signalling function, CD11d is under unique transcriptional control and expressed on a sub-set of predominately tissue-differentiated innate leukocytes. The following review is the first to capture the nearly three decades of CD11d research and discusses the emerging role of CD11d in leukocyte migration and retention during the progression of a staged immune response.

A vesicular stomatitis virus-based prime-boost vaccination strategy induces potent and protective neutralizing antibodies against SARS-CoV-2.

The development of safe and effective vaccines to prevent SARS-CoV-2 infections remains an urgent priority worldwide. We have used a recombinant vesicular stomatitis virus (rVSV)-based prime-boost immunization strategy to develop an effective COVID-19 vaccine candidate. We have constructed VSV genomes carrying exogenous genes resulting in the production of avirulent rVSV carrying the full-length spike protein (SF), the S1 subunit, or the receptor-binding domain (RBD) plus envelope (E) protein of SARS-CoV-2. Adding the honeybee melittin signal peptide (msp) to the N-terminus enhanced the protein expression, and adding the VSV G protein transmembrane domain and the cytoplasmic tail (Gtc) enhanced protein incorporation into pseudotype VSV. All rVSVs expressed three different forms of SARS-CoV-2 spike proteins, but chimeras with VSV-Gtc demonstrated the highest rVSV-associated expression. In immunized mice, rVSV with chimeric S protein-Gtc derivatives induced the highest level of potent neutralizing antibodies and T cell responses, and rVSV harboring the full-length msp-SF-Gtc proved to be the superior immunogen. More importantly, rVSV-msp-SF-Gtc vaccinated animals were completely protected from a subsequent SARS-CoV-2 challenge. Overall, we have developed an efficient strategy to induce a protective response in SARS-CoV-2 challenged immunized mice. Vaccination with our rVSV-based vector may be an effective solution in the global fight against COVID-19.

Live imaging of SARS-CoV-2 infection in mice reveals that neutralizing antibodies require Fc function for optimal efficacy.

Neutralizing antibodies (NAbs) are effective in treating COVID-19, but the mechanism of immune protection is not fully understood. Here, we applied live bioluminescence imaging (BLI) to monitor the real-time effects of NAb treatment during prophylaxis and therapy of K18-hACE2 mice intranasally infected with SARS-CoV-2-nanoluciferase. Real-time imaging revealed that the virus spread sequentially from the nasal cavity to the lungs in mice and thereafter systemically to various organs including the brain, culminating in death. Highly potent NAbs from a COVID-19 convalescent subject prevented, and also effectively resolved, established infection when administered within three days. In addition to direct neutralization, depletion studies indicated that Fc effector interactions of NAbs with monocytes, neutrophils, and natural killer cells were required to effectively dampen inflammatory responses and limit immunopathology. Our study highlights that both Fab and Fc effector functions of NAbs are essential for optimal in vivo efficacy against SARS-CoV-2.

Live Imaging of SARS-CoV-2 Infection in Mice Reveals Neutralizing Antibodies Require Fc Function for Optimal Efficacy.

Neutralizing antibodies (NAbs) are effective in treating COVID-19 but the mechanism of immune protection is not fully understood. Here, we applied live bioluminescence imaging (BLI) to monitor the real-time effects of NAb treatment in prophylaxis and therapy of K18-hACE2 mice intranasally infected with SARS-CoV-2-nanoluciferase. We could visualize virus spread sequentially from the nasal cavity to the lungs and thereafter systemically to various organs including the brain, which culminated in death. Highly potent NAbs from a COVID-19 convalescent subject prevented, and also effectively resolved, established infection when administered within three days. In addition to direct Fab-mediated neutralization, Fc effector interactions of NAbs with monocytes, neutrophils and natural killer cells were required to effectively dampen inflammatory responses and limit immunopathology. Our study highlights that both Fab and Fc effector functions of NAbs are essential for optimal in vivo efficacy against SARS-CoV-2.

Preconditioning Human Adipose-Derived Stromal Cells on Decellularized Adipose Tissue Scaffolds Within a Perfusion Bioreactor Modulates Cell Phenotype and Promotes a Pro-regenerative Host Response.

Cell-based therapies involving the delivery of adipose-derived stromal cells (ASCs) on decellularized adipose tissue (DAT) scaffolds are a promising approach for soft tissue augmentation and reconstruction. Our lab has recently shown that culturing human ASCs on DAT scaffolds within a perfusion bioreactor prior to implantation can enhance their capacity to stimulate in vivo adipose tissue regeneration. Building from this previous work, the current study investigated the effects of bioreactor preconditioning on the ASC phenotype and secretory profile in vitro, as well as host cell recruitment following implantation in an athymic nude mouse model. Immunohistochemical analyses indicated that culturing within the bioreactor increased the percentage of ASCs co-expressing inducible nitric oxide synthase (iNOS) and arginase-1 (Arg-1), as well as tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10), within the peripheral regions of the DAT relative to statically cultured controls. In addition, bioreactor culture altered the expression levels of a range of immunomodulatory factors in the ASC-seeded DAT. In vivo testing revealed that culturing the ASCs on the DAT within the perfusion bioreactor prior to implantation enhanced the infiltration of host CD31+ endothelial cells and CD26+ cells into the DAT implants, but did not alter CD45+F4/80+CD68+ macrophage recruitment. However, a higher fraction of the CD45+ cell population expressed the pro-regenerative macrophage marker CD163 in the bioreactor group, which may have contributed to enhanced remodeling of the scaffolds into host-derived adipose tissue. Overall, the findings support that bioreactor preconditioning can augment the capacity of human ASCs to stimulate regeneration through paracrine-mediated mechanisms.

Repetitive mild traumatic brain injury in mice triggers a slowly developing cascade of long-term and persistent behavioral deficits and pathological changes.

We have previously reported long-term changes in the brains of non-concussed varsity rugby players using magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI) and functional magnetic imaging (fMRI). Others have reported cognitive deficits in contact sport athletes that have not met the diagnostic criteria for concussion. These results suggest that repetitive mild traumatic brain injuries (rmTBIs) that are not severe enough to meet the diagnostic threshold for concussion, produce long-term consequences. We sought to characterize the neuroimaging, cognitive, pathological and metabolomic changes in a mouse model of rmTBI. Using a closed-skull model of mTBI that when scaled to human leads to rotational and linear accelerations far below what has been reported for sports concussion athletes, we found that 5 daily mTBIs triggered two temporally distinct types of pathological changes. First, during the first days and weeks after injury, the rmTBI produced diffuse axonal injury, a transient inflammatory response and changes in diffusion tensor imaging (DTI) that resolved with time. Second, the rmTBI led to pathological changes that were evident months after the injury including: changes in magnetic resonance spectroscopy (MRS), altered levels of synaptic proteins, behavioural deficits in attention and spatial memory, accumulations of pathologically phosphorylated tau, altered blood metabolomic profiles and white matter ultrastructural abnormalities. These results indicate that exceedingly mild rmTBI, in mice, triggers processes with pathological consequences observable months after the initial injury.

Major role of IgM in the neutralizing activity of convalescent plasma against SARS-CoV-2.

Characterization of the humoral response to SARS-CoV-2, the etiological agent of COVID-19, is essential to help control the infection. The neutralization activity of plasma from patients with COVID-19 decreases rapidly during the first weeks after recovery. However, the specific role of each immunoglobulin isotype in the overall neutralizing capacity is still not well understood. In this study, we select plasma from a cohort of convalescent patients with COVID-19 and selectively deplete immunoglobulin A, M, or G before testing the remaining neutralizing capacity of the depleted plasma. We find that depletion of immunoglobulin M is associated with the most substantial loss of virus neutralization, followed by immunoglobulin G. This observation may help design efficient antibody-based COVID-19 therapies and may also explain the increased susceptibility to SARS-CoV-2 of autoimmune patients receiving therapies that impair the production of immunoglobulin M (IgM).

Adipose Stromal Cells Enhance Decellularized Adipose Tissue Remodeling Through Multimodal Mechanisms.

Decellularized adipose tissue (DAT) scaffolds represent a promising cell-instructive platform for soft tissue engineering. While recent work has highlighted that mesenchymal stromal cells, including adipose-derived stromal cells (ASCs), can be combined with decellularized scaffolds to augment tissue regeneration, the mechanisms involved require further study. The objective of this work was to probe the roles of syngeneic donor ASCs and host-derived macrophages in tissue remodeling of DAT scaffolds within an immunocompetent mouse model. Dual transgenic reporter mouse strains were employed to track and characterize the donor ASCs and host macrophages within the DAT implants. More specifically, ASCs isolated from dsRed mice were seeded on DAT scaffolds, and the seeded and unseeded control scaffolds were implanted subcutaneously into MacGreen transgenic mice for up to 8 weeks. ASC seeding was shown to augment cell infiltration into the DAT implants at 8 weeks, and this was linked to significantly enhanced angiogenesis relative to the unseeded controls. Immunohistochemical staining demonstrated long-term retention of the syngeneic donor ASCs over the duration of the 8-week study, providing evidence that the DAT scaffolds are a cell-supportive delivery platform. Notably, newly formed adipocytes within the DAT implants were not dsRed+, indicating that the donor ASCs supported fat formation through indirect mechanisms. Immunohistochemical tracking of host macrophages through costaining for enhanced green fluorescent protein with the macrophage marker Iba1 revealed that ASC seeding significantly increased the number of infiltrating macrophages within the DAT implants at 3 weeks, while the fraction of macrophages relative to the total cellular infiltrate was similar between the groups at 1, 3, and 8 weeks. Consistent with the tissue remodeling response that was observed, western blotting demonstrated that there was significantly augmented expression of CD163 and CD206, markers of constructive M2-like macrophages, within the ASC-seeded DAT implants. Overall, our results demonstrate that exogenous ASCs enhance tissue regeneration within DAT scaffolds indirectly through multimodal mechanisms that include host cell recruitment and immunomodulation. These data provide further evidence to support the use of decellularized scaffolds as a delivery platform for ASCs in tissue engineering.

Putative Concussion Biomarkers Identified in Adolescent Male Athletes Using Targeted Plasma Proteomics.

Sport concussions can be difficult to diagnose and if missed, they can expose athletes to greater injury risk and long-lasting neurological disabilities. Discovery of objective biomarkers to aid concussion diagnosis is critical to protecting athlete brain health. To this end, we performed targeted proteomics on plasma obtained from adolescent athletes suffering a sports concussion. A total of 11 concussed male athletes were enrolled at our academic Sport Medicine Concussion Clinic, as well as 24 sex-, age- and activity-matched healthy control subjects. Clinical evaluation was performed and blood was drawn within 72 h of injury. Proximity extension assays were performed for 1,472 plasma proteins; a total of six proteins were considered significantly different between cohorts (P < 0.01; five proteins decreased and one protein increased). Receiver operating characteristic curves on the six individual protein biomarkers identified had areas-under-the-curves (AUCs) for concussion diagnosis ≥0.78; antioxidant 1 copper chaperone (ATOX1; AUC 0.81, P = 0.003), secreted protein acidic and rich in cysteine (SPARC; AUC 0.81, P = 0.004), cluster of differentiation 34 (CD34; AUC 0.79, P = 0.006), polyglutamine binding protein 1 (PQBP1; AUC 0.78, P = 0.008), insulin-like growth factor-binding protein-like 1 (IGFBPL1; AUC 0.78, P = 0.008) and cytosolic 5'-nucleotidase 3A (NT5C3A; AUC 0.78, P = 0.009). Combining three of the protein biomarkers (ATOX1, SPARC and NT5C3A), produced an AUC of 0.98 for concussion diagnoses (P < 0.001; 95% CI: 0.95, 1.00). Despite a paucity of studies on these three identified proteins, the available evidence points to their roles in modulating tissue inflammation and regulating integrity of the cerebral microvasculature. Taken together, our exploratory data suggest that three or less novel proteins, which are amenable to a point-of-care immunoassay, may be future candidate biomarkers for screening adolescent sport concussion. Validation with protein assays is required in larger cohorts.

Concussion Acutely Decreases Plasma Glycerophospholipids in Adolescent Male Athletes.

Concussions are frequent in sports and can contribute to significant and long-lasting neurological disability. Adolescents are particularly susceptible to concussions, with accurate determination of the injury challenging. Our previous study demonstrated that concussion diagnoses could be aided by metabolomics profiling and machine learning, with particular weighting on changes in plasma glycerophospholipids (PCs). Here, our aim was to report directional change of PCs after concussion and develop a diagnostic concussion panel utilizing a minimum number of plasma PCs. To this end, we enrolled 12 concussed male athletes at our academic Sport Medicine Concussion Clinic, as well as 17 sex-, age-, and activity-matched healthy controls. Blood was drawn and 71 plasma PCs were measured for statistically significant changes within 72 h of injury, and individual PCs were further analyzed with receiver operating characteristic (ROC) curves. Our data demonstrated that 26 of 71 PCs measured were significantly decreased after sports-related concussion (p < 0.01). None of the PCs increased in plasma after concussion. ROC curve analyses identified the top four PCs with areas under the curve (AUCs) ≥0.86 for concussion diagnosis: PCaeC36:0 (0.92; p < 0.001); PCaaC42:6 (0.90; p < 0.001); PCaeC36:2 (0.86; p = 0.001), and PCaaC32:0 (0.86; p = 0.001). Cut-off values in µM were ≤0.31, 0.22, 5.07, and 4.63, respectively. Importantly, combining these four PCs produced an AUC of 0.96 for concussion diagnoses (p < 0.001; 95% confidence interval, 0.89, 1.00). Our data suggest that as few as four circulating PCs may provide excellent diagnostic potential for adolescent concussion. External validation is required in larger cohorts.

Brain Metabolite Levels in Sedentary Women and Non-contact Athletes Differ From Contact Athletes.

White matter tracts are known to be susceptible to injury following concussion. The objective of this study was to determine whether contact play in sport could alter white matter metabolite levels in female varsity athletes independent of changes induced by long-term exercise. Metabolite levels were measured by single voxel proton magnetic resonance spectroscopy (MRS) in the prefrontal white matter at the beginning (In-Season) and end (Off-Season) of season in contact (N = 54, rugby players) and non-contact (N = 23, swimmers and rowers) varsity athletes. Sedentary women (N = 23) were scanned once, at a time equivalent to the Off-Season time point. Metabolite levels in non-contact athletes did not change over a season of play, or differ from age matched sedentary women except that non-contact athletes had a slightly lower myo-inositol level. The contact athletes had lower levels of myo-inositol and glutamate, and higher levels of glutamine compared to both sedentary women and non-contact athletes. Lower levels of myo-inositol in non-contact athletes compared to sedentary women indicates long-term exercise may alter glial cell profiles in these athletes. The metabolite differences observed between contact and non-contact athletes suggest that non-contact athletes should not be used as controls in studies of concussion in high-impact sports because repetitive impacts from physical contact can alter white matter metabolite level profiles. It is imperative to use athletes engaged in the same contact sport as controls to ensure a matched metabolite profile at baseline.

Infiltrating Hematogenous Macrophages Aggregate Around ß-Amyloid Plaques in an Age- and Sex-Dependent Manner in a Mouse Model of Alzheimer Disease.

ß-Amyloid (Aß) plaques can trigger chronic inflammation in the cellular environment that recruits infiltrating macrophages during the course of Alzheimer disease (AD). Activated macrophages release pro-inflammatory cytokines that increase neurotoxicity associated with AD. A major impediment to investigating neuroinflammation involving macrophage activity is the inability to discriminate resident microglial macrophages (mMϕ) from hematogenous macrophages (hMϕ), as they are morphologically and phenotypically similar when activated. To distinguish between mMϕ and hMϕ and to determine their respective roles in chronic inflammation associated with the progression of amyloidosis, we used lys-EGFP-ki transgenic mice that express enhanced green fluorescent protein in hMϕ, but not in mMϕ. These mice were crossed with 5XFAD mice. The offspring demonstrated robust AD pathology and enabled visual discrimination of mMϕ from hMϕ. Mutant mice demonstrated robust increases in Aß1-42, area of Aß plaques, gliosis and deficits in spatial learning by age 5 months. The time-course of Aß accumulation, paralleled by the accumulation of hMϕ around Aß plaques, was more robust in female compared with male mice and preceded behavioral changes. Thus, the accumulation of infiltrating hMϕ around Aß plaques was age- and sex-dependent and preceded cognitive impairment.