Bloodstream Of Mice Research Articles

Hydrogel based on M1 macrophage lysate and alginate loading with oxaliplatin for effective immunomodulation to inhibit melanoma progression, recurrence and metastasis

Despite the monumental success of immunotherapy in treating melanoma clinically, it still confronts significant challenges, chiefly that singular immunomodulatory tactics are insufficient to suppress the recurrence and metastasis of melanoma. Herein, these challenges are addressed by a hydrogel based on M1 macrophage lysate and alginate (M1LMHA) loaded with oxaliplatin (OXA), named M1LMHA@OXA.The results obtained from scanning electron microscopy and confocal microscopy indicate that the structure and morphology of M1LMHA@OXA remain unchanged. Flow cytometry results reveal that M1LMHA@OXA significantly promotes the maturation of dendritic cells (DCs) and enhances the proliferation of T lymphocytes. In a subcutaneous melanoma transplant model, M1LMHA@OXA effectively suppressed tumor growth in comparison to OXA alone and M1LMHA alone. Flow cytometry demonstrated that M1LMHA@OXA markedly increased the number of mature DCs and CD8+ T cells at the tumor site, while significantly reducing the quantity of M2-like tumor-associated macrophages (TAM) and enhancing the presence of M1 macrophages. Enzyme-linked immunosorbent assay (ELISA) results indicated that following treatment with M1LMHA@OXA, the levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in the bloodstream of mice were significantly elevated, whereas interleukin-10 (IL-10) exhibited no significant difference. This outcome further corroborates the ability of M1LMHA@OXA to substantially bolster the immune capability of mice. Similar results have also been observed in a melanoma subcutaneous transplantation recurrence model, and optical imaging of the lungs of mice revealed that M1LMHA@OXA inhibited tumor metastasis to the lungs. Notably, M1LMHA@OXA exhibits an exceptional therapeutic effect on the growth, post-surgical recurrence, and metastasis of the B16F10 melanoma. Therefore, this study provides a straightforward strategy that leverages the cooperative regulation of multiple immune cells to thwart the proliferation, recurrence, and spread of melanoma.

In Vivo Efficacy of Rezafungin, Anidulafungin, Caspofungin, and Micafungin against Four Candida auris Clades in a Neutropenic Mouse Bloodstream Infection Model.

Rezafungin is the first new drug approved to treat candidaemia and invasive candidiasis in more than 10 years. However, data are scant on the in vivo efficacy of rezafungin and the other three approved echinocandins against different Candida auris clades. This study involved 10 isolates representing 4 C. auris clades: South Asian (n = 2), East Asian (n = 2), South African (n = 2), and South American (n = 4, including 2 environmental isolates). In the lethality experiment and fungal tissue burden experiment (kidney, heart, and brain), cyclophosphamide-treated BALB/c male mice were intravenously infected (107 and 8 × 106 colony-forming units [CFU]/mouse, respectively). A 20 mg/kg dose of rezafungin was administered on days 1, 3, and 6. Alternatively, beginning 24 h post-infection, mice received 3 mg/kg of caspofungin, 5 mg/kg of micafungin, or 5 mg/kg of anidulafungin once daily for 6 days. Regardless of isolate and clade, all echinocandin regimens improved survival after 21 days (p = 0.0041 to p < 0.0001). All echinocandins frequently produced >3-log mean CFU/g decreases in the fungal kidney and heart burdens, although some of these decreases were not statistically significant. Rezafungin, regardless of clade, produced 3-5 and 2-4 log CFU/g decreases in the kidney and heart burdens, respectively. Echinocandins did not inhibit fungal growth in the brain. Histopathological examination performed on day 7 showed no fungal cells in the heart and kidneys of rezafungin-treated mice and to a lesser extent, caspofungin-treated mice, regardless of the clinical isolate. All echinocandin-treated mice showed medium and/or large foci of fungal cells in their cerebrum or cerebellum. Regardless of the C. auris clade, rezafungin activity in vivo was comparable to or improved over that of the three previously approved echinocandins.

CXCL12 chemokine dimer signaling modulates acute myelogenous leukemia cell migration through altered receptor internalization.

Acute myeloid leukemia (AML) is a malignancy of immature myeloid blast cells with stem-like and chemoresistant cells being retained in the bone marrow through CXCL12-CXCR4 signaling. Current CXCR4 inhibitors mobilize AML cells into the bloodstream where they become more chemosensitive have failed to improve patient survival, likely reflecting persistent receptor localization on target cells. Here we characterize the signaling properties of CXCL12-locked dimer (CXCL12-LD), a bioengineered variant of the dimeric CXCL12 structure. CXCL12-LD binding resulted in lower levels of G protein, β-arrestin, and intracellular calcium mobilization, consistent with the locked dimer being a partial agonist of CXCR4. Further, CXCL12-LD failed to induce chemotaxis in AML cells. Despite these partial agonist properties, CXCL12-LD increased CXCR4 internalization compared to wildtype and locked-monomer forms of CXCL12. Analysis of a previously published AML transcriptomic data showed CXCR4 positive AML cells co-express genes involved in chemoresistance and maintenance of a blast-like state. The CXCL12-LD partial agonist effectively mobilized stem cells into the bloodstream in mice suggesting a potential role for their use in targeting CXCR4. Together, our results suggest that enhanced internalization by CXCL12-LD partial agonist signaling can avoid pharmacodynamic tolerance and may identify new avenues to better target GPCRs.

Novel Delivery Systems for Oral Administration of Enfuvirtide: New Treatment Options for HIV/AIDS

AbstractEnfuvirtide (T‐20) is a synthetic peptide fusion inhibitor for the human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS). However, the peptide nature limits a wider application of T‐20 with subcutaneous injection (Fuzeon) the only available formulation. In this groundbreaking study, it is sought to overcome this limitation by employing poly lactic‐co‐glycolic acid (PLGA) and alginate to create novel oral delivery systems for T‐20. Remarkably, this investigation marks the first instance of assessing the efficacy of oral delivery systems in mice. Notably, both the PLGA and alginate formulations exhibit the capability to sustain T‐20 release, maintaining detectable levels in the bloodstream of mice for over 24 h after a single dose. By venturing into the realm of oral T‐20 delivery, this study opens avenues for the prospective development of oral formulations of T‐20, potentially leading to their evaluation in clinical trials.

Verification of Outer Hair Cell Motor Protein, Prestin, as a Serological Biomarker for Mouse Cochlear Damage.

The motor protein prestin, found in the inner ear's outer hair cells (OHCs), is responsible for high sensitivity and sharp frequency selectivity in mammalian hearing. Some studies have suggested that prestin could be a serological biomarker for cochlear damage, as OHCs are highly vulnerable to damage from various sources. However, the reported data are inconsistent and lack appropriate negative controls. To investigate whether prestin can be used as a serological biomarker for cochlear damage or stress, we measured prestin quantities in the bloodstreams of mice using ELISA kits from different companies. Wildtype (WT) mice were exposed to different ototoxic treatments, including noise exposure and ototoxic reagents that rapidly kill OHCs. Prestin-knockout (KO) mice were used as a negative control. Our data show that some ELISA kits were not able to detect prestin specifically. The ELISA kit that could detect the prestin protein from cochlear homogenates failed to detect prestin in the bloodstream, despite there being significant damage to OHCs in the cochleae. Furthermore, the optical densities of the serum samples, which correlate to prestin quantities, were significantly influenced by hemolysis in the samples. In conclusion, Prestin from OHCs is not a sensitive and reliable serological biomarker for detecting cochlear damage in mice using ELISA.

Discovery of Antimicrobial Lysins from the "Dark Matter" of Uncharacterized Phages Using Artificial Intelligence.

The rapid rise of antibiotic resistance and slow discovery of new antibiotics have threatened global health. While novel phage lysins have emerged as potential antibacterial agents, experimental screening methods for novel lysins pose significant challenges due to the enormous workload. Here, the first unified software package, namely DeepLysin, is developed to employ artificial intelligence for mining the vast genome reservoirs ("dark matter") for novel antibacterial phage lysins. Putative lysins are computationally screened from uncharacterized Staphylococcus aureus phages and 17 novel lysins are randomly selected for experimental validation. Seven candidates exhibit excellent in vitro antibacterial activity, with LLysSA9 exceeding that of the best-in-class alternative. The efficacy of LLysSA9 is further demonstrated in mouse bloodstream and wound infection models. Therefore, this study demonstrates the potential of integrating computational and experimental approaches to expedite the discovery of new antibacterial proteins for combating increasing antimicrobial resistance.

A novel strategy to elicit enduring anti-morphine immunity and relief from addiction by targeting Acr1 protein nano vaccine through TLR-2 to dendritic cells

Morphine addiction poses a significant challenge to global healthcare. Current opioid substitution therapies, such as buprenorphine, naloxone and methadone are effective but often lead to dependence. Thus, exploring alternative treatments for opioid addiction is crucial. We have developed a novel vaccine that presents morphine and Pam3Cys (a TLR-2 agonist) on the surface of Acr1 nanoparticles. This vaccine has self-adjuvant properties and targets TLR-2 receptors on antigen-presenting cells, particularly dendritic cells. Our vaccination strategy promotes the proliferation and differentiation of morphine-specific B-cells and Acr1-reactive CD4 T-cells. Additionally, the vaccine elicited the production of high-affinity anti-morphine antibodies, effectively eliminating morphine from the bloodstream and brain in mice. It also reduced the expression of addiction-associated μ-opioid receptor and dopamine genes. The significant increase in memory CD4 T-cells and B-cells indicates the vaccine's ability to induce long-lasting immunity against morphine. This vaccine holds promise as a prophylactic measure against morphine addiction.

Cryptococcus neoformans rapidly invades the murine brain by sequential breaching of airway and endothelial tissues barriers, followed by engulfment by microglia.

Cryptococcus neoformans causes lethal meningitis and accounts for approximately 10%-15% of AIDS-associated deaths worldwide. There are major gaps in our understanding of how this fungus invades the mammalian brain. To investigate the dynamics of C. neoformans tissue invasion, we mapped fungal localization and host cell interactions in infected brain, lung, and upper airways using mouse models of systemic and airway infection. To enable this, we developed an in situ imaging pipeline capable of measuring large volumes of tissue while preserving anatomical and cellular information by combining thick tissue sections, tissue clarification, and confocal imaging. We confirm high fungal burden in mouse upper airway after nasal inoculation. Yeast in turbinates were frequently titan cells, with faster kinetics than reported in mouse lungs. Importantly, we observed one instance of fungal cells enmeshed in lamina propria of the upper airways, suggesting penetration of airway mucosa as a possible route of tissue invasion and dissemination to the bloodstream. We extend previous literature positing bloodstream dissemination of C. neoformans, by finding viable fungi in the bloodstream of mice a few days after intranasal infection. As early as 24 h post systemic infection, the majority of C. neoformans cells traversed the blood-brain barrier, and were engulfed or in close proximity to microglia. Our work presents a new method for investigating microbial invasion, establishes that C. neoformans can breach multiple tissue barriers within the first days of infection, and demonstrates microglia as the first cells responding to C. neoformans invasion of the brain.IMPORTANCECryptococcal meningitis causes 10%-15% of AIDS-associated deaths globally. Still, brain-specific immunity to cryptococci is a conundrum. By employing innovative imaging, this study reveals what occurs during the first days of infection in brain and in airways. We found that titan cells predominate in upper airways and that cryptococci breach the upper airway mucosa, which implies that, at least in mice, the upper airways are a site for fungal dissemination. This would signify that mucosal immunity of the upper airway needs to be better understood. Importantly, we also show that microglia, the brain-resident macrophages, are the first responders to infection, and microglia clusters are formed surrounding cryptococci. This study opens the field to detailed molecular investigations on airway immune response, how fungus traverses the blood-brain barrier, how microglia respond to infection, and ultimately how microglia monitor the blood-brain barrier to preserve brain function.

Biodistribution of Therapeutic Small Interfering RNAs Delivered with Lipid-Substituted Polyethylenimine-Based Delivery Systems.

Small interfering RNAs (siRNAs) have emerged as a powerful tool to manipulate gene expression in vitro. However, their potential therapeutic application encounters significant challenges, such as degradation in vivo, limited cellular uptake, and restricted biodistribution, among others. This study evaluates the siRNA delivery efficiency of three different lipid-substituted polyethylenimine (PEI)-based carriers, named Leu-Fect A-C, to different organs in vivo, including xenograft tumors, when injected into the bloodstream of mice. The siRNA analysis was undertaken by stem-loop RT-PCR, followed by qPCR or digital droplet PCR. Formulating siRNAs with a Leu-Fect series of carriers generated nanoparticles that effectively delivered the siRNAs into K652 and MV4-11 cells, both models of leukemia. The Leu-Fect carriers were able to successfully deliver BCR-Abl and FLT3 siRNAs into leukemia xenograft tumors in mice. All three carriers demonstrated significantly enhanced siRNA delivery into organs other than the liver, including the xenograft tumors. Preferential biodistribution of siRNAs was observed in the lungs and spleen. Among the delivery systems, Leu-Fect A exhibited the highest biodistribution into organs. In conclusion, lipid-substituted PEI-based delivery systems offer improvements in addressing pharmacokinetic challenges associated with siRNA-based therapies, thus opening avenues for their potential translation into clinical practice.

Stable isotope-assisted mass spectrometry reveals in vivo distribution, metabolism, and excretion of tire rubber-derived 6PPD-quinone in mice

6PPD-quinone (6PPD-Q) has been identified as a ubiquitous contaminant in the surrounding locality, including air particles, roadside soils, dust, and water. Recently, the prevalence of 6PPD-Q in human urine has accentuated the urgency for investigating its biological fate. To address this, we conducted a stable isotope-assisted high-resolution mass spectrometry (HRMS) assay to unveil the distribution, metabolism, excretion, and toxicokinetic properties of this contaminant in a mouse model. Mice were fed with a single dose of deuterated 6PPD-Q-d5 at human-relevant exposure levels. Results indicated that 6PPD-Q was quickly assimilated and distributed into bloodstream and main organs of mice, with the concentrations reaching peaks under 1 h following administration. Notably, 6PPD-Q was primarily distributed in the adipose tissue, marked by a significant Cmax (p < 0.05), followed by the kidney, lung, testis, liver, spleen, heart, and muscle. In addition, our measurement demonstrated that 6PPD-Q can penetrate the blood-brain barrier of mice within 0.5 h after exposure. The half-lives (t1/2) of 6PPD-Q in serum, lung, kidney, and spleen of mice were measured at 12.7 ± 0.3 h, 20.7 ± 1.4 h, 21.6 ± 5.3 h, and 20.6 ± 2.8 h, respectively. Using HRMS combined with isotope tracing techniques, two novel hydroxylated metabolites of 6PPD-Q in the mice liver were identified for the first time, which provides new insights into its rapid elimination in-vivo. Meanwhile, fecal excretion was identified as the main excretory pathway for 6PPD-Q and its hydroxylated metabolites. Collectively, our findings extend the current knowledge on the biological fate and exposure status of 6PPD-Q in a mouse model, which has the potential to be extrapolated to humans.

Differential expression of SLC30A10 and RAGE in mouse pups by early life lead exposure

BackgroundSLC30A10 and RAGE are widely recognized as pivotal regulators of Aβ plaque transport and accumulation. Prior investigations have established a link between early lead exposure and cerebral harm in offspring, attributable to Aβ buildup and amyloid plaque deposition. However, the impact of lead on the protein expression of SLC30A10 and RAGE has yet to be elucidated. This study seeks to confirm the influence of maternal lead exposure during pregnancy, specifically through lead-containing drinking water, on the protein expression of SLC30A10 and RAGE in mice offspring. Furthermore, this research aims to provide further evidence of lead-induced neurotoxicity. MethodsFour cohorts of mice were subjected to lead exposure at concentrations of 0 mM, 0.25 mM, 0.5 mM, and 1 mM over a period of 42 uninterrupted days, spanning from pregnancy to the weaning phase. On postnatal day 21, the offspring mice underwent assessments. The levels of lead in the blood, hippocampus, and cerebral cortex were scrutinized, while the mice's cognitive abilities pertaining to learning and memory were probed through the utilization of the Morris water maze. Furthermore, Western blotting and immunofluorescence techniques were employed to analyze the expression levels of SLC30A10 and RAGE in the hippocampus and cerebral cortex. ResultsThe findings revealed a significant elevation in lead concentration within the brains and bloodstreams of mice, mirroring the increased lead exposure experienced by their mothers during the designated period (P < 0.05). Notably, in the Morris water maze assessment, the lead-exposed group exhibited noticeably diminished spatial memory compared to the control group (P < 0.05). Both immunofluorescence and Western blot analyses effectively demonstrated the concomitant impact of varying lead exposure levels on the hippocampal and cerebral cortex regions of the offspring. The expression levels of SLC30A10 displayed a negative correlation with lead doses (P < 0.05). Surprisingly, under identical circumstances, the expression of RAGE in the hippocampus and cortex of the offspring exhibited a positive correlation with lead doses (P < 0.05). ConclusionSLC30A10 potentially exerts distinct influence on exacerbated Aβ accumulation and transportation in contrast to RAGE. Disparities in brain expression of RAGE and SLC30A10 may contribute to the neurotoxic effects induced by lead.

Peptidoglycan-induced modulation of metabolic and inflammatory responses.

Bacterial cell wall peptidoglycan is composed of innate immune ligands and, due to its important structural role, also regulates access to many other innate immune ligands contained within the bacteria. There is a growing body of literature demonstrating how innate immune recognition impacts the metabolic functions of immune cells and how metabolic changes are not only important to inflammatory responses but are often essential. Peptidoglycan is primarily sensed in the context of the whole bacteria during lysosomal degradation; consequently, the innate immune receptors for peptidoglycan are primarily intracellular cytosolic innate immune sensors. However, during bacterial growth, peptidoglycan fragments are shed and can be found in the bloodstream of humans and mice, not only during infection but also derived from the abundant bacterial component of the gut microbiota. These peptidoglycan fragments influence cells throughout the body and are important for regulating inflammation and whole-body metabolic function. Therefore, it is important to understand how peptidoglycan-induced signals in innate immune cells and cells throughout the body interact to regulate how the body responds to both pathogenic and nonpathogenic bacteria. This mini-review will highlight key research regarding how cellular metabolism shifts in response to peptidoglycan and how systemic peptidoglycan sensing impacts whole-body metabolic function.

Helicobacter pylori outer membrane vesicles induce astrocyte reactivity through nuclear factor-κappa B activation and cause neuronal damage in vivo in a murine model

BackgroundHelicobacter pylori (Hp) infects the stomach of 50% of the world’s population. Importantly, chronic infection by this bacterium correlates with the appearance of several extra-gastric pathologies, including neurodegenerative diseases. In such conditions, brain astrocytes become reactive and neurotoxic. However, it is still unclear whether this highly prevalent bacterium or the nanosized outer membrane vesicles (OMVs) they produce, can reach the brain, thus affecting neurons/astrocytes. Here, we evaluated the effects of Hp OMVs on astrocytes and neurons in vivo and in vitro.MethodsPurified OMVs were characterized by mass spectrometry (MS/MS). Labeled OMVs were administered orally or injected into the mouse tail vein to study OMV-brain distribution. By immunofluorescence of tissue samples, we evaluated: GFAP (astrocytes), βIII tubulin (neurons), and urease (OMVs). The in vitro effect of OMVs in astrocytes was assessed by monitoring NF-κB activation, expression of reactivity markers, cytokines in astrocyte-conditioned medium (ACM), and neuronal cell viability.ResultsUrease and GroEL were prominent proteins in OMVs. Urease (OMVs) was present in the mouse brain and its detection coincided with astrocyte reactivity and neuronal damage. In vitro, OMVs induced astrocyte reactivity by increasing the intermediate filament proteins GFAP and vimentin, the plasma membrane αVβ3 integrin, and the hemichannel connexin 43. OMVs also produced neurotoxic factors and promoted the release of IFNγ in a manner dependent on the activation of the transcription factor NF-κB. Surface antigens on reactive astrocytes, as well as secreted factors in response to OMVs, were shown to inhibit neurite outgrowth and damage neurons.ConclusionsOMVs administered orally or injected into the mouse bloodstream reach the brain, altering astrocyte function and promoting neuronal damage in vivo. The effects of OMVs on astrocytes were confirmed in vitro and shown to be NF-κB-dependent. These findings suggest that Hp could trigger systemic effects by releasing nanosized vesicles that cross epithelial barriers and access the CNS, thus altering brain cells.

Nigericin is effective against multidrug resistant gram-positive bacteria, persisters, and biofilms.

Multidrug-resistant (MDR) bacteria pose a significant clinical threat to human health, but the development of antibiotics cannot meet the urgent need for effective agents, especially those that can kill persisters and biofilms. Here, we reported that nigericin showed potent bactericidal activity against various clinical MDR Gram-positive bacteria, persisters and biofilms, with low frequencies of resistance development. Moreover, nigericin exhibited favorable in vivo efficacy in deep-seated mouse biofilm, murine skin and bloodstream infection models. With Staphylococcus aureus, nigericin disrupted ATP production and electron transport chain; cell death was associated with altered membrane structure and permeability. Obtaining nigericin-resistant/tolerant mutants required multiple rounds of challenge, and, cross-resistance to members of several antimicrobial classes was absent, probably due to distinct nigericin action with the GraSR two-component regulatory system. Thus, our work reveals that nigericin is a promising antibiotic candidate for the treatment of chronic or recurrent infections caused by Gram-positive bacteria.

Platelets Bind Senescent Red Blood Cells and Mediate Their Clearance from the Circulation

The bloodstream of mice and humans contain consistent proportions of red blood cells (RBC) which are bound to platelets (1-2% and 0.1-0.3%, respectively). This study identifies senescent RBC as the main constituent of platelet-RBC complexes (Plt-RBC) and their importance in RBC clearance. RBC have a defined circulation lifespan and upon reaching senescence are eliminated by phagocytes, thereby ensuring homeostasis and preventing accumulation of dead cells and toxic hemolytic byproducts. Senescent RBC are characterized by cellular and molecular changes, including reduced deformability, externalization of membrane phosphatidylserine (PS), and altered expression of membrane proteins such Fas ligand (CD95; upregulated) and integrin associated protein (CD47; downregulated), which act as pro-phagocytic signals. Similar changes to deformability and membrane composition occur in RBC compromised by sickle cell disease or Plasmodium infection. These pathologic cells also display a 10x higher platelet-binding capacity which is related to disease pathogenesis. Thus, we investigated how platelets may interact with senescent RBC and the purpose of Plt-RBC. Platelet binding to senescent RBC was studied using mice pulse-labelled with biotin-NHS, which enabled tracking of RBC age and clearance over time. The biotin+ RBC remaining for longer times represented older cells; the oldest detected were aged ≥58 days consistent with the reported maximal RBC lifespan in mice. During the first 45 days of observation Plt-RBC were similar in biotin+ versus newly replenished biotin- RBC (1.6-2.2%), but were significantly higher in biotin+ cells detected at 52 and 58 days (average ± SD: 6.7 ± 5.1% and 15 ± 8.1%, respectively; p < 0.001). These observations were replicated when biotin-NHS was replaced with CFSE. The aged RBC and Plt-RBC also contained significantly increased PS and CD95 compared to the replenished and non-complexed cells, although CD47 levels were not different. Flow cytometry imaging revealed Plt-RBC were composed of single RBC bound by 1-2 platelets. Collectively this indicated that platelets preferentially bind senescent RBC. To investigate if platelet binding affected senescent RBC clearance, platelet-depleting antibodies (anti-GPIbα or anti-GPIIb/IIIa) were given to temporarily reduce Plt-RBC when biotin+ Plt-RBC levels first began to diverge (Day 46-49 in multiple experiments). The treatment caused a maximal 10-fold reduction in Plt-RBC levels sustained for 2-3 days, and a marked retention of biotin+ RBC which coincided with Plt-RBC reductions. Consistent with these results, the clearance of transfused RBC in platelet-depleted mice was also significantly inhibited compared to control mice. Erythrophagocytes in the spleen, but not the liver, from the platelet-depleted mice also contained fewer transfused cells, and erythrophagocytes containing platelets were observed using flow cytometry and microscopy. Thus, platelets are important for the clearance and/or phagocytosis of both senescent and transfused RBC. We also studied the Plt-RBC clearance mechanism by transfusing ex vivo generated and labelled Plt-RBC and RBC. The Plt-RBC were cleared at least 5x faster than RBC (p=0.0014) suggesting that once formed, their lifespan in the circulation is transient. Similar transfusions in mice depleted of phagocytes (using clodronate liposomes) impeded Plt-RBC clearance, indicating a phagocyte-dependent pathway for their removal. An additional mechanistic insight, Plt-RBC displayed an increased retention in a microsphiltration assay system, indicating platelet binding may hinder the passage of cells through the microcirculation. Our studies have thus revealed an unexpected contribution by platelets in senescent RBC clearance. In our proposed model (Figure 1) senescent RBC have an enhanced ability to bind platelets, possibly due to upregulated PS and CD95, which accelerates their removal via splenic retention and phagocytosis. Platelets may also present additional pro-phagocytic signals to stimulate erythrophagocytosis. A normal platelet count provides surplus platelets to maintain RBC clearance, but in conditions of acute platelet loss, reduction of plt-RBC may cause accumulation of senescent RBC to pathological levels. Conversely, conditions where more RBC bind platelets such as in malarial infection will increase plt-RBC and result in thrombocytopenia. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Abstract 13114: Micro RNA206 Secreted From Growing Skeletal Muscle Promotes Angiogenic Response in Endothelial Cells

Introduction: In addition to aerobic exercise, it has been recognized that resistance exercise has beneficial effects for the patients with peripheral arterial disease. Recently, muscle-derived exosomes are demonstrated to convey many types of signaling molecules including microRNAs (miRNAs). Hypothesis: We assessed the hypothesis that exosomal miRNA secreted by growing muscle promotes angiogenic response in endothelial cells. Methods: We utilized skeletal muscle-specific inducible Akt1 transgenic (Akt1-TG) mice that can induce growth of skeletal muscles without exercise training. Exosomes was purified combined usage of ultracentrifugation, and miRNAs were extracted from purified exosomes by spin column-based method. Real-time PCR array and droplet digital PCR was performed to evaluate exosomal miRNA expression. Results: Akt1-TG mice showed remarkable skeletal muscle growth 2 weeks after gene activation (weight of gastrocnemius muscle: 0.21±0.03 vs 0.16±0.02, g, p&lt;0.01). The amount of exosomal proteins did not different between Akt1-TG mice and WT mice (977.7±11.3 vs 826.0±45.2, μg/mL serum, p=0.07). KEGG pathway frequency analysis for 4665 target genes identified by real-time PCR array of miRNAs revealed a significant increase in Akt and its downstream signaling pathways. Among upregulated miRNAs, droplet digital PCR identified that miR-1, -133 and -206 expression was significantly upregulated in Akt1 TG mice compared with WT mice in serum. miR206 was increased in IGF-1-stimulated myotubes. PKH26-labeled exosomes were taken up by human umbilical vein endothelial cells. Exogenous supplementation of exosomal miRNA206 promoted angiogenesis as revealed by spheroid assay, and increased expression of HIF-1 and VEGF in endometrial cells. Conclusions: Exosomal miR206 was upregulated in blood stream in Akt1-TG mice and IGF-stimulated cultured myotubes. Exogenous supplementation of miR206 promoted angiogenic response in endothelial cells. Our data suggest that miR206 secreted from growing muscle act on endothelial cells and promote angiogenesis.

Emergence of a NDM-1-producing ST25 Klebsiella pneumoniae strain causing neonatal sepsis in China.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) seriously threaten the efficacy of modern medicine with a high associated mortality rate and unprecedented transmission rate. In this study, we isolated a clinical K. pneumoniae strain DY1928 harboring bla NDM-1 from a neonate with blood infection. Antimicrobial susceptibility testing indicated that DY1928 was resistant to various antimicrobial agents, including meropenem, imipenem, ceftriaxone, cefotaxime, ceftazidime, cefepime, piperacillin-tazobactam, and amoxicillin-clavulanate. S1 nuclease-pulsed field gel electrophoresis (S1-PFGE), southern blot and conjugation experiment revealed that the bla NDM-1 gene was located on a conjugative plasmid of IncA/C2 type with a 147.9 kb length. Whole-genome sequencing showed that there was a conservative structure sequence (bla NDM-1-ble-trpF-dsbD) located downstream of the bla NDM-1 gene. Multilocus sequence typing (MLST) classified DY1928 as ST25, which was a hypervirulent K. pneumoniae type. Phylogenetic analysis of genomic data from all ST25 K. pneumoniae strains available in the NCBI database suggested that all bla NDM-1 positive strains were isolated in China and had clinical origins. A mouse bloodstream infection model was constructed to test the virulence of DY1928, and 11 K. pneumoniae strains homologous to DY1928 were isolated from the feces of infected mice. Moreover, we found that DY1928 had a tendency to flow from the blood into the intestine in mice and caused multiple organ damage. To our knowledge, this is the first study to report an infection caused by bla NDM-1-positive ST25 K. pneumoniae in the neonatal unit. Our findings indicated that stricter surveillance and more effective actions were needed to reduce the risk of disseminating such K. pneumoniae strains in clinical settings, especially in neonatal wards.

CAQK, a peptide associating with extracellular matrix components targets sites of demyelinating injuries.

The destruction of the myelin sheath that encircles axons leads to impairments of nerve conduction and neuronal dysfunctions. A major demyelinating disorder is multiple sclerosis (MS), a progressively disabling disease in which immune cells attack the myelin. To date, there are no therapies to target selectively myelin lesions, repair the myelin or stop MS progression. Small peptides recognizing epitopes selectively exposed at sites of injury show promise for targeting therapeutics in various pathologies. Here we show the selective homing of the four amino acid peptide, cysteine-alanine-lysine glutamine (CAQK), to sites of demyelinating injuries in three different mouse models. Homing was assessed by administering fluorescein amine (FAM)-labeled peptides into the bloodstream of mice and analyzing sites of demyelination in comparison with healthy brain or spinal cord tissue. FAM-CAQK selectively targeted demyelinating areas in all three models and was absent from healthy tissue. At lesion sites, the peptide was primarily associated with the fibrous extracellular matrix (ECM) deposited in interstitial spaces proximal to reactive astrocytes. Association of FAM-CAQK was detected with tenascin-C although tenascin depositions made up only a minor portion of the examined lesion sites. In mice on a 6-week cuprizone diet, FAM-CAQK peptide crossed the nearly intact blood-brain barrier and homed to demyelinating fiber tracts. These results demonstrate the selective targeting of CAQK to demyelinating injuries under multiple conditions and confirm the previously reported association with the ECM. This work sets the stage for further developing CAQK peptide targeting for diagnostic and therapeutic applications aimed at localized myelin repair.

The quorum sensing peptide EntF* promotes colorectal cancer metastasis in mice: a new factor in the host-microbiome interaction

BackgroundColorectal cancer, one of the most common malignancies worldwide, is associated with a high mortality rate, mainly caused by metastasis. Comparative metagenome-wide association analyses of healthy individuals and cancer patients suggest a role for the human intestinal microbiota in tumor progression. However, the microbial molecules involved in host-microbe communication are largely unknown, with current studies mainly focusing on short-chain fatty acids and amino acid metabolites as potential mediators. Quorum sensing peptides are not yet considered in this context since their presence in vivo and their ability to affect host cells have not been reported so far.ResultsHere, we show that EntF*, a metabolite of the quorum sensing peptide EntF produced by Enterococcus faecium, is naturally present in mice bloodstream. Moreover, by using an orthotopic mouse model, we show that EntF* promotes colorectal cancer metastasis in vivo, with metastatic lesions in liver and lung tissues. In vitro tests suggest that EntF* regulates E-cadherin expression and consequently the epithelial-mesenchymal transition, via the CXCR4 receptor. In addition, alanine-scanning analysis indicates that the first, second, sixth, and tenth amino acid of EntF* are critical for epithelial-mesenchymal transition and tumor metastasis.ConclusionOur work identifies a new class of molecules, quorum sensing peptides, as potential regulators of host-microbe interactions. We prove, for the first time, the presence of a selected quorum sensing peptide metabolite in a mouse model, and we demonstrate its effects on colorectal cancer metastasis. We believe that our work represents a starting point for future investigations on the role of microbiome in colorectal cancer metastasis and for the development of novel bio-therapeutics in other disease areas.

Improved stability and pharmacokinetics of wogonin through loading into PASylated ferritin

Wogonin (Wog) plays an important role in human diseases, especially cancer and inflammatory diseases, but its poor solubility, unstable metabolism and low bioavailability greatly limit its application in biomedical fields. Therefore, we developed a temperature-dependent method to encapsulate wogonin into a novel ferritin-based nanocarrier. To improve the loading capacity and stability, the human H chain ferritin (HFtn) was functionalized with a repetitive polypeptide sequence composed of proline (Pro), alanine (Ala), and serine (Ser) in different residues lengths (PAS10 and PAS30). Wogonin loading and release studies demonstrated that the encapsulation efficiency and stability of the PASylated nanocarriers were significantly higher than those of the wild type. PAS-HFtn-Wog exhibited enhanced cytotoxicity to MCF-7 breast cancer cells and HepG2 liver cancer cells. Notably, the PASylated HFtn, especially PAS30-HFtn greatly prolonged the pharmacokinetics of wogonin in the mice bloodstream. Therefore, wogonin-loaded PAS-HFtn may be a promising drug candidate for cancer therapy.