scholarly journals cas9Enhances Bacterial Virulence by Repressing theregRTranscriptional Regulator inStreptococcus agalactiae

2017 ◽  
Vol 86 (3) ◽  
Author(s):  
Ke Ma ◽  
Qing Cao ◽  
Su Luo ◽  
Zhaofei Wang ◽  
Guangjin Liu ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Blood Brain Barrier ◽  
Streptococcus Agalactiae ◽  
Critical Factor ◽  
Transcriptional Regulator ◽  
Intracellular Survival ◽  
Bacterial Virulence ◽  
Brain Barrier ◽  
Content Type ◽  
Endogenous Gene

ABSTRACTClustered regularly interspaced palindromic repeats (CRISPR) and their associatedcasgenes have been demonstrated to regulate self-genes and virulence in many pathogens. In this study, we found that inactivation ofcas9caused reduced adhesion and intracellular survival of the piscineStreptococcus agalactiaestrain GD201008-001 and significantly decreased the virulence of this strain in zebrafish and mice. Further investigation indicated that theregRtranscriptional regulator was upregulated in the Δcas9mutant. AsregRmediates the repression of hyaluronidase, a critical factor involved in opening the blood-brain barrier (BBB) in mice,cas9-mediated repression ofregRtranscription is important forS. agalactiaeto open the BBB and thereby cause meningitis in animals. This study expands our understanding of endogenous gene regulation mediated by CRISPR-Cas systems in bacteria.

scholarly journals Manipulation of Autophagy in Phagocytes Facilitates Staphylococcus aureus Bloodstream Infection

2015 ◽  
Vol 83 (9) ◽  
pp. 3445-3457 ◽  
Author(s):  
Kate M. O'Keeffe ◽  
Mieszko M. Wilk ◽  
John M. Leech ◽  
Alison G. Murphy ◽  
Maisem Laabei ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Systemic Infection ◽  
Critical Factor ◽  
Intracellular Survival ◽  
Autophagic Flux ◽  
Content Type ◽  
Bactericidal Effects ◽  
Staphylococcus Aureus Bloodstream Infection ◽  
Direct Killing

The capacity for intracellular survival within phagocytes is likely a critical factor facilitating the dissemination ofStaphylococcus aureusin the host. To date, the majority of work onS. aureus-phagocyte interactions has focused on neutrophils and, to a lesser extent, macrophages, yet we understand little about the role played by dendritic cells (DCs) in the direct killing of this bacterium. Using bone marrow-derived DCs (BMDCs), we demonstrate for the first time that DCs can effectively killS. aureusbut that certain strains ofS. aureushave the capacity to evade DC (and macrophage) killing by manipulation of autophagic pathways. Strains with high levels of Agr activity were capable of causing autophagosome accumulation, were not killed by BMDCs, and subsequently escaped from the phagocyte, exerting significant cytotoxic effects. Conversely, strains that exhibited low levels of Agr activity failed to accumulate autophagosomes and were killed by BMDCs. Inhibition of the autophagic pathway by treatment with 3-methyladenine restored the bactericidal effects of BMDCs. Using anin vivomodel of systemic infection, we demonstrated that the ability ofS. aureusstrains to evade phagocytic cell killing and to survive temporarily within phagocytes correlated with persistence in the periphery and that this effect is critically Agr dependent. Taken together, our data suggest that strains ofS. aureusexhibiting high levels of Agr activity are capable of blocking autophagic flux, leading to the accumulation of autophagosomes. Within these autophagosomes, the bacteria are protected from phagocytic killing, thus providing an intracellular survival niche within professional phagocytes, which ultimately facilitates dissemination.

Quantification and pharmacokinetics of blood-brain barrier disruption in humans

1996 ◽  
Vol 85 (6) ◽  
pp. 1056-1065 ◽  
Author(s):  
Bernhard Zünkeler ◽  
Richard E. Carson ◽  
Jeff Olson ◽  
Ronald G. Blasberg ◽  
Hetty Devroom ◽  
...  
Keyword(s):  
Brain Tumors ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Normal Brain ◽  
Content Type ◽  
Barrier Disruption ◽  
Blood Brain Barrier Disruption ◽  
Blood Brain ◽  
Brain Barrier Disruption ◽  
Fine Print

✓ Hyperosmolar blood-brain barrier disruption (HBBBD), produced by infusion of mannitol into the cerebral arteries, has been used in the treatment of brain tumors to increase drug delivery to tumor and adjacent brain. However, the efficacy of HBBBD in brain tumor therapy has been controversial. The goal of this study was to measure changes in vascular permeability after HBBBD in patients with malignant brain tumors. The permeability (K1) of tumor and normal brain blood vessels was measured using rubidium-82 and positron emission tomography before and repeatedly at 8- to 15-minute intervals after HBBBD. Eighteen studies were performed in 13 patients, eight with glioblastoma multiforme and five with anaplastic astrocytoma. The HBBBD increased K1 in all patients. Baseline K1 values were 2.1 ± 1.4 and 34.1 ± 22.1 µl/minute/ml (± standard deviation) for brain and tumor, respectively. The peak absolute increases in K1 following HBBBD were 20.8 ± 11.7 and 19.7 ± 10.7 µl/minute/ml for brain and tumor, corresponding to percentage increases of approximately 1000% in brain and approximately 60% in tumor. The halftimes for return of K1 to near baseline for brain and tumor were 8.1 ± 3.8 and 4.2 ± 1.2 minutes, respectively. Simulations of the effects of HBBBD made using a very simple model with intraarterial methotrexate, which is exemplary of drugs with low permeability, indicate that 1) total exposure of the brain and tumor to methotrexate, as measured by the methotrexate concentration-time integral (or area under the curve), would increase with decreasing infusion duration and would be enhanced by 130% to 200% and by 7% to 16%, respectively, compared to intraarterial infusion of methotrexate alone; and 2) exposure time at concentrations above 1 µM, the minimal concentration required for the effects of methotrexate, would not be enhanced in tumor and would be enhanced by only 10% in brain. Hyperosmolar blood-brain barrier disruption transiently increases delivery of water-soluble compounds to normal brain and brain tumors. Most of the enhancement of exposure results from trapping the drug within the blood-brain barrier, an effect of the very transient alteration of the blood-brain barrier by HBBBD. Delivery is most effective when a drug is administered within 5 to 10 minutes after disruption. However, the increased exposure and exposure time that occur with methotrexate, the permeability of which is among the lowest of the agents currently used clinically, are limited and the disproportionate increase in brain exposure, compared to tumor exposure, may alter the therapeutic index of many drugs.

Quantitative autoradiographic measurements of blood-brain barrier permeability in the rat glioma model

1982 ◽  
Vol 57 (3) ◽  
pp. 394-398 ◽  
Author(s):  
Kazuo Yamada ◽  
Yukitaka Ushio ◽  
Toru Hayakawa ◽  
Amami Kato ◽  
Noriko Yamada ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Chemotherapeutic Drugs ◽  
Content Type ◽  
Rat Glioma ◽  
Blood Brain ◽  
Brain Barrier Permeability ◽  
Bbb Permeability ◽  
Autoradiographic Technique ◽  
The Brain

✓ Quantitative autoradiographic technique was applied in measuring blood-brain barrier (BBB) permeability of autochthonous gliomas in rats. In small tumors (less than 2 mm in diameter), no increase in BBB permeability was noted. As the tumor grew and neovascularization occurred, BBB permeability increased in the center of the tumor, and it was suggested that the BBB was partly disrupted in the neovascularized vessels. In the fully grown tumors, BBB permeability was markedly increased in the viable part of the tumor to levels similar to the choroid plexus. Yet, the BBB was partly preserved at the periphery of the tumor and in the brain adjacent to the tumor. The heterogeneity of the BBB phenomenon according to the stage of tumor growth may be a major obstacle for uptake of chemotherapeutic drugs that do not cross the BBB easily.

Penetration of recombinant interleukin-2 across the blood-cerebrospinal fluid barrier

1988 ◽  
Vol 69 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Stephen C. Saris ◽  
Steven A. Rosenberg ◽  
Robert B. Friedman ◽  
Joshua T. Rubin ◽  
David Barba ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Blood Brain Barrier ◽  
Interleukin 2 ◽  
Albumin Level ◽  
Brain Barrier ◽  
Lymphokine Activated Killer Cells ◽  
Content Type ◽  
Blood Brain ◽  
Recombinant Interleukin 2 ◽  
Fine Print

✓ Recombinant interleukin-2 (rIL-2) is an immunotherapeutic agent with efficacy against certain advanced cancers. The penetration of rIL-2 across the blood-cerebrospinal fluid (CSF) barrier was studied in 12 cancer patients who had no evidence of tumor involvement of the central nervous system. At different times during treatment with intravenous rIL-2, CSF was withdrawn either continuously for 8 to 26 hours via a lumbar subarachnoid catheter (in eight patients) or by a single lumbar puncture (in four). Bioassay showed the appearance of rIL-2 in lumbar CSF 4 to 6 hours after the first intravenous dose, a rise over 2 to 4 hours to a plateau of 3 to 9 U/ml, and clearance to less than 0.1 U/ml by 10 hours after the last dose. An abnormally elevated CSF albumin level in two of the twelve patients indicated alteration of the blood-brain barrier. There were no abnormalities in the CSF glucose level or white blood cell count. The CSF pharmacokinetics contrast with the rapid elimination of rIL-2 from plasma and demonstrate significant blood-CSF barrier penetration. These data support the possibility of achieving CSF levels of rIL-2 that are adequate to maintain activity of lymphokine-activated killer cells after parenteral administration, and argue for rIL-2-associated disruption of the human blood-brain barrier in some patients.

scholarly journals Oxidative Stress, Cytokine/Chemokine and Disruption of Blood–Brain Barrier in Neonate Rats After Meningitis by Streptococcus agalactiae

2011 ◽  
Vol 36 (10) ◽  
pp. 1922-1930 ◽  
Author(s):  
Tatiana Barichello ◽  
Joelson C. Lemos ◽  
Jaqueline S. Generoso ◽  
Andreza L. Cipriano ◽  
Graziele L. Milioli ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Blood Brain Barrier ◽  
Streptococcus Agalactiae ◽  
Brain Barrier ◽  
Blood Brain

Selective blood-tumor barrier disruption by leukotrienes

1992 ◽  
Vol 77 (3) ◽  
pp. 407-410 ◽  
Author(s):  
Chung-Ching Chio ◽  
Takehiko Baba ◽  
Keith L. Black
Keyword(s):  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Normal Brain ◽  
Barrier Permeability ◽  
Content Type ◽  
Blood Brain Barrier Permeability ◽  
Blood Brain ◽  
Brain Barrier Permeability ◽  
The Mean ◽  
Fine Print

✓ The authors have previously reported that intracarotid infusion of 5 µg leukotriene C4 (LTC4) selectively increases blood-tumor barrier permeability in rat RG-2 tumors. In this study, rats harboring RG-2 tumors were given 15-minute intracarotid infusions of LTC4 at concentrations ranging from 0.5 µg to 50.0 µg (seven rats in each dose group). Blood-tumor and blood-brain barrier permeability were determined by quantitative autoradiography using 14C aminoisobutyric acid. The transfer constant for permeability (Ki) within the tumors was increased twofold by LTC4 doses of 2.5, 5.0, and 50.0 µg compared to vehicle alone (90.00 ±21.14, 92.68 ± 15.04, and 80.17 ± 16.15 vs. 39.37 ± 6.45 µl/gm/min, respectively; mean ± standard deviation; p < 0.01). No significant change in Ki within the tumors was observed at the 0.5-µg LTC4 dose. Blood-brain barrier permeability was selectively increased within the tumors. At no dose in this study did leukotrienes increase permeability within normal brain. To determine the duration of increased opening of the blood-tumor barrier by LTC4 administration, Ki was measured at 15, 30, and 60 minutes after termination of a 15-minute LTC4 infusion (seven rats at each time point). The mean Ki value was still high at 15 minutes (92.68 ± 15.04 µl/gm/min), but declined at 30 minutes (56.58 ± 12.50 µl/gm/min) and 60 minutes (55.40 ± 8.10 µl/gm/min) after the end of LTC4 infusion. Sulfidopeptide leukotrienes LTC4, LTD4, LTE4 and LTF4 were infused to compare their potency in opening the blood-tumor barrier. The mean leukotriene E4 was the most potent, increasing the permeability value 37½ fold compared with vehicle alone (139.86 ± 23.95 vs. 39.37 ± 6.45 µl/gm/min).

The effect of interleukin-2 on the blood-brain barrier in the 9L gliosarcoma rat model

1989 ◽  
Vol 70 (1) ◽  
pp. 92-96 ◽  
Author(s):  
Joseph T. Alexander ◽  
Stephen C. Saris ◽  
Edward H. Oldfield
Keyword(s):  
Blood Brain Barrier ◽  
Interleukin 2 ◽  
Brain Barrier ◽  
High Dose ◽  
Normal Brain ◽  
Content Type ◽  
Tumor Bearing ◽  
Blood Brain ◽  
Significant Difference ◽  
Fine Print

✓ Carbon-14-labeled aminoisobutyric acid was used to determine local blood-to-tissue transfer constants in 22 Fischer rats with intracerebral 9L gliosarcomas that received either high-dose parenteral interleukin-2 (IL-2) or a control injection. In tumor and peritumoral tissue, the transfer constants in the IL-2-treated animals (89.6 ± 14.6 and 35.8 ± 6.0, respectively, mean ± standard error of the mean) were larger (p < 0.05) than in control animals (61.4 ± 6.4 and 14.6 ± 2.2, respectively). In contrast, in normal frontal and occipital tissue contralateral to the tumor-bearing hemisphere, there was no significant difference between the transfer constants in IL-2-treated and control animals. Furthermore, treatment of animals with IL-2 excipient caused no change in permeability as compared to animals treated with Hanks' balanced salt solution. Parenteral injection of IL-2 increases blood-brain barrier disruption in tumor-bearing rat brain but does not increase the vascular permeability of normal brain. Methods to prevent this increased tumor vessel permeability are required before parenteral IL-2 can be used safely for the treatment of primary or metastatic brain tumors.

Ultrastructural blood-brain barrier alterations and edema formation in acute spinal cord trauma

1976 ◽  
Vol 44 (4) ◽  
pp. 418-424 ◽  
Author(s):  
Joseph H. Goodman ◽  
W. George Bingham ◽  
William E. Hunt
Keyword(s):  
Spinal Cord ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Edema Formation ◽  
Content Type ◽  
Vascular Disruption ◽  
Blood Brain ◽  
Glutaraldehyde Solution ◽  
Vascular Structures ◽  
Cellular Separation

✓ Endothelial changes leading to edema formation are examined in the primate spinal cord (Macaca mulatta) following a lesion created by a 20-gm weight falling 15 cm onto the exposed dura. Intravascular perfusion of a paraformaldehyde-glutaraldehyde solution followed by carbon black provides adequate fixation of vascular structures and glial elements. Myelin is poorly preserved. Ultrastructural alterations of the blood-brain barrier consist of loss of integrity of the endothelial tight junctions. Edema caused by vascular disruption and parenchymatous extravasation of intravascular contents is observed along with glial swelling. Interglial gap junctions persist in areas of marked cellular separation and do not impede the migration of edema fluid.

Cerebrovascular permeability and delivery of gentamicin to normal brain and experimental brain abscess in rats

1984 ◽  
Vol 61 (3) ◽  
pp. 430-439 ◽  
Author(s):  
Edward A. Neuwelt ◽  
David E. Baker ◽  
Michael A. Pagel ◽  
Nathan K. Blank
Keyword(s):  
Brain Abscess ◽  
Blood Brain Barrier ◽  
Medical Management ◽  
Brain Barrier ◽  
High Dose ◽  
Normal Brain ◽  
Content Type ◽  
Stage Of Development ◽  
Blood Brain ◽  
Brain Abscesses

✓ Antibiotics vary widely in their ability to penetrate the blood-brain barrier. In studies of 70 rats, the permeability of the normal blood-brain barrier to gentamicin was shown to be poor. In experimental brain abscesses, during the cerebritic stage of development, the penetration of intravenous antibiotics was increased compared to normal brain but was very inconsistent. Antibiotic delivery to brain abscess was not significantly altered with the administration of high-dose steroids, but the macrophage and glial response was markedly decreased with high-dose steroid therapy. Reversible osmotic blood-brain barrier modification with mannitol increased the delivery of gentamicin both to brain abscess and to the surrounding brain. It also resulted in more consistent tissue drug levels. The clinical implications of these studies suggest that, because of the inconsistent delivery of gentamicin to brain abscess, the therapeutic efficacy of medical management alone may be quite variable. This mode of therapy could possibly increase the efficacy of medical management of brain abscesses, especially in patients with multiple or surgically inaccessible brain abscesses.

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