| 1. |
- Akil, Shahnaz, et al.
(författare)
-
Appropriate coronary revascularization can be accomplished if myocardial perfusion is quantified by positron emission tomography prior to treatment decision
- 2021
-
Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1071-3581 .- 1532-6551. ; 28:4, s. 1664-1672
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Many patients undergo percutaneous coronary intervention (PCI) without the use of non-invasive stress testing prior to treatment. The aim of this study was to determine the potential added value of guiding revascularization by quantitative assessment of myocardial perfusion prior to intervention. Methods and Results: Thirty-three patients (10 females) with suspected or established CAD who had been referred for a clinical coronary angiography (CA) with possibility for PCI were included. Adenosine stress and rest 13N-NH3 PET, cardiac magnetic resonance (CMR), and cardiopulmonary exercise test were performed 4 ± 3 weeks before and 5 ± 1 months after CA. The angiographer was blinded to the PET and CMR results. Myocardial flow reserve (MFR) < 2.0 by PET was considered abnormal. A PCI was performed in 19/33 patients. In 41% (11/27) of the revascularized vessel territories, a normal regional MFR was found prior to the PCI and no improvement in MFR was found at follow-up (P = 0.9). However, vessel territories with regional MFR < 2.0 at baseline improved significantly after PCI (P = 0.003). Of the 14 patients not undergoing PCI, four had MFR < 2.0 in one or more coronary territories. Conclusion: Assessment of quantitative myocardial perfusion prior to revascularization could lead to more appropriate use of CA when managing patients with stable CAD.
|
|
| 2. |
- Akil, Shahnaz, et al.
(författare)
-
Qualitative assessments of myocardial ischemia by cardiac MRI and coronary stenosis by invasive coronary angiography in relation to quantitative perfusion by positron emission tomography in patients with known or suspected stable coronary artery disease
- 2020
-
Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1071-3581 .- 1532-6551. ; 27:6, s. 2351-2359
-
Tidskriftsartikel (refereegranskat)abstract
- Background: To relate findings of qualitative evaluation of first-pass perfusion-CMR and anatomical evaluation on coronary angiography (CA) to the reference standard of quantitative perfusion, cardiac PET, in patients with suspected or known stable coronary artery disease (CAD). Methods and Results: Forty-one patients referred for CA due to suspected stable CAD, prospectively performed adenosine stress/rest first-pass perfusion-CMR as well as 13N-NH3 PET on the same day, 4 ± 3 weeks before CA. Angiographers were blinded to PET and CMR results. Regional myocardial flow reserve (MFR) < 2.0 on PET was considered pathological. Vessel territories with stress-induced ischemia by CMR or vessels with stenosis needing revascularization had a significantly lower MFR compared to those with no regional stress-induced ischemia or vessels not needing revascularization (P < 0.001). In 4 of 123 vessel territories with stress-induced ischemia by CMR, PET showed a normal MFR. In addition, 12 of 123 vessels that underwent intervention showed normal MFR assessed by PET. Conclusion: The limited performance of qualitative assessment of presence of stable CAD with CMR and CA, when related to quantitative 13N-NH3 cardiac PET, shows the need for fully quantitative assessment of myocardial perfusion and the use of invasive flow reserve measurements for CA, to confirm the need of elective revascularization.
|
|
| 3. |
- Boettcher, Mareike, et al.
(författare)
-
NF-kappa B signaling in tanycytes mediates inflammation-induced anorexia
- 2020
-
Ingår i: Molecular Metabolism. - : ELSEVIER. - 2212-8778. ; 39
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: Infections, cancer, and systemic inflammation elicit anorexia. Despite the medical significance of this phenomenon, the question of how peripheral inflammatory mediators affect the central regulation of food intake is incompletely understood. Therefore, we have investigated the sickness behavior induced by the prototypical inflammatory mediator IL-1 beta. Methods: IL-1 beta was injected intravenously. To interfere with IL-1 beta signaling, we deleted the essential modulator of NF-kappa B signaling (Nemo) in astrocytes and tanycytes. Results: Systemic IL-1 beta increased the activity of the transcription factor NF-kB in tanycytes of the mediobasal hypothalamus (MBH). By activating NF-kappa B signaling, IL-1 beta induced the expression of cyclooxygenase-2 (Cox-2) and stimulated the release of the anorexigenic prostaglandin E-2 (PGE(2)) from tanycytes. When we deleted Nemo in astrocytes and tanycytes, the IL-1 beta-induced anorexia was alleviated whereas the fever response and lethargy response were unchanged. Similar results were obtained after the selective deletion of Nemo exclusively in tanycytes. Conclusions: Tanycytes form the brain barrier that mediates the anorexic effect of systemic inflammation in the hypothalamus. (C) 2020 The Author(s). Published by Elsevier GmbH. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
|
|
| 4. |
- Brito, Haissa Oliveira, et al.
(författare)
-
Immune-mediated febrile response in female rats: Role of central hypothalamic mediators
- 2020
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Lipopolysaccharide (LPS) induces fever through cytokines like receptor-activator of nuclear factor kappa B ligand (RANKL), triggering mediators like prostaglandins (PG), endothelin-1 (ET-1), corticotrophin-releasing factor (CRF), substance P (SP) and endogenous opioids. LPS-induced fever is reduced in females compared with males except in ovariectomized (OVX) females which show increased fever mediated by PG. The present study aimed to identify the mediators involved in fever in intact and OVX female rats. Fever was induced with LPS (50 mu g/kg) intraperitoneally or CRF (2.5 mu g), ET-1 (1 pg), morphine (10 mu g) and SP (500 ng) intracerebroventricularly in sham-operated and OVX rats. The role of RANKL was evaluated with osteoprotegerin (OPG, 1 mu g, intracerebroventricularly). Expression of RANK, CRFI/II, ETB, mu-opioid (MOR) and NK1 receptors was evaluated by confocal microscopy. Besides LPS, only morphine induced fever in OVX rats while all mediators induced fever in sham-operated animals. OPG abolished LPS-induced fever in OVX but not sham-operated animals. Overall, fever involves similar central mediators in cycling females and males but only morphine induced fever in OVX females. Importantly, RANK/RANKL participates in LPS-induced fever in OVX females, as in males but not in cycling females.
|
|
| 5. |
- de Paula, Gabriela Cristina, et al.
(författare)
-
Hippocampal Function Is Impaired by a Short-Term High-Fat Diet in Mice : Increased Blood-Brain Barrier Permeability and Neuroinflammation as Triggering Events
- 2021
-
Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- Worldwide, and especially in Western civilizations, most of the staple diets contain high amounts of fat and refined carbohydrates, leading to an increasing number of obese individuals. In addition to inducing metabolic disorders, energy dense food intake has been suggested to impair brain functions such as cognition and mood control. Here we demonstrate an impaired memory function already 3 days after the start of a high-fat diet (HFD) exposure, and depressive-like behavior, in the tail suspension test, after 5 days. These changes were followed by reduced synaptic density, changes in mitochondrial function and astrocyte activation in the hippocampus. Preceding or coinciding with the behavioral changes, we found an induction of the proinflammatory cytokines TNF-alpha and IL-6 and an increased permeability of the blood-brain barrier (BBB), in the hippocampus. Finally, in mice treated with a TNF-alpha inhibitor, the behavioral and BBB alterations caused by HFD-feeding were mitigated suggesting that inflammatory signaling was critical for the changes. In summary, our findings suggest that HFD rapidly triggers hippocampal dysfunction associated with BBB disruption and neuroinflammation, promoting a progressive breakdown of synaptic and metabolic function. In addition to elucidating the link between diet and cognitive function, our results might be relevant for the comprehension of the neurodegenerative process.
|
|
| 6. |
- Eskilsson, Anna, 1986-, et al.
(författare)
-
Fever During Localized Inflammation in Mice Is Elicited by a Humoral Pathway and Depends on Brain Endothelial Interleukin-1 and Interleukin-6 Signaling and Central EP3 Receptors
- 2021
-
Ingår i: Journal of Neuroscience. - : SOC NEUROSCIENCE. - 0270-6474 .- 1529-2401. ; 41:24, s. 5206-5218
-
Tidskriftsartikel (refereegranskat)abstract
- We examined the signaling route for fever during localized inflammation in male and female mice, elicited by casein injection into a preformed air pouch. The localized inflammation gave rise to high concentrations of prostaglandins of the E species (PGE(2)) and cytokines in the air pouch and elevated levels of these inflammatory mediators in plasma. There were also elevated levels of PGE(2) in the cerebrospinal fluid, although there was little evidence for PGE(2) synthesis in the brain. Global deletion of the PGE(2) prostaglandin E receptor 3 (EP3) abolished the febrile response as did deletion of the EP3 receptor in neural cells, whereas its deletion on peripheral nerves had no effect, implying that PGE(2) action on this receptor in the CNS elicited the fever. Global deletion of the interleukin-1 receptor type 1 (IL-1R1) also abolished the febrile response, whereas its deletion on neural cells or peripheral nerves had no effect. However, deletion of the IL-1R1 on brain endothelial cells, as well as deletion of the interleukin-6 receptor a on these cells, attenuated the febrile response. In contrast, deletion of the PGE(2) synthesizing enzymes cyclooxygenase-2 and microsomal prostaglandin synthase-1 in brain endothelial cells, known to attenuate fever evoked by systemic inflammation, had no effect. We conclude that fever during localized inflammation is not mediated by neural signaling from the inflamed site, as previously suggested, but is dependent on humoral signaling that involves interleukin actions on brain endothelial cells, probably facilitating PGE(2) entry into the brain from the circulation and hence representing a mechanism distinct from that at work during systemic inflammation.
|
|
| 7. |
- Eskilsson, Anna, 1986-
(författare)
-
Inflammatory Signaling Across the Blood-Brain Barrier and the Generation of Fever
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fever is a cardinal sign of inflammation and is evolutionary conserved. Fever is known to be beneficial during acute inflammation, but over time and if very high it can be detrimental. The signaling pathways by which fever is initiated by the brain and the peripheral mechanisms through which the temperature increase is generated were studied from several point of views. Fever is known to be dependent on prostaglandin E2 (PGE2) binding to its receptors in the median preoptic nucleus of the hypothalamus, which signals to the brainstem and through sympathetic nerves to heat conserving and heat producing effector organs. This thesis focuses on identifying the cells that produce the PGE2 critical for the fever response; showing where in the brain the critical PGE2 production takes place; demonstrating how peripheral inflammation activates these cells to produce PGE2; and finally, identifying the effector mechanisms behind the temperature elevation in fever. By using a newly developed specific antibody we showed that the enzyme responsible for the terminal step in the production of PGE2, microsomal prostaglandin E-synthase 1 (mPGES-1), is expressed in endothelial cells of brain blood vessels in mice where it is co-expressed with the enzyme cyclooxygenase-2 (Cox-2), which is known to be induced in these cells and to be rate limiting for the PGE2 production. The mPGES-1 enzyme was also expressed in several other cell types and structures which however did not express Cox-2, such as capillary-associated pericytes, astroglial cells, leptomeninges, and the choroid plexus. The role of the mPGES-1 in these other cells/structures remains unknown. Next, by using mice with selective deletion of Cox-2 in brain endothelial cells, we showed that local PGE2 production in deep brain areas, such as the hypothalamus, is critical for the febrile response to peripheral inflammation. In contrast, PGE2 production in other brain areas and the overall PGE2 level in the brain were not critical for the febrile response. Partly restoring the PGE2 synthesizing capacity in the anterior hypothalamus of mice lacking such capacity with a lentiviral vector resulted in a temperature elevation in response to an intraperitoneal injection of bacterial wall lipopolysaccharide (LPS). The data show that the febrile response is dependent on the local release of PGE2 onto its target neurons, possibly by a paracrine mechanism. Deletion of the receptor for the pyrogenic cytokine IL-6 on brain endothelial cells, but not on neurons or peripheral nerves, strongly attenuated the febrile response to LPS and reduced the induction of the Cox-2 expression in the hypothalamus. Furthermore, mice deficient of the IL- 6Rα gene in the brain endothelial cells showed a reduced SOCS3 mRNA induction, whereas IκB mRNA-levels were unaffected, suggesting that the IL-6 signaling occurs via STAT3 activation and not signaling through the transcription factor NF-κB. This idea was confirmed by the observation of attenuated fever in mice deficient of STAT3 in brain endothelial cells. These data show that IL-6, when endogenously released during systemic inflammation, is pyrogenic by binding to IL-6R on brain endothelial cells to induce prostaglandin synthesis in these cells. Finally, we demonstrate that mice with genetic deletion of uncoupling protein-1 (UCP-1), hence lacking functional brown adipose tissue, had a normal fever response to LPS, and that LPS caused no activation of brown adipose tissue in wild type mice. However, blocking peripheral cutaneous vasoconstriction resulted in a blunted fever response to LPS, suggesting that heat conservation, possibly together with shivering or non-shivering thermogenesis in the musculature, is responsible for the generation of immune-induced fever, whereas brown adipose tissue thermogenesis is not involved.
|
|
| 8. |
- Eskilsson, Anna, et al.
(författare)
-
The generation of immune-induced fever and emotional stress-induced hyperthermia in mice does not involve brown adipose tissue thermogenesis
- 2020
-
Ingår i: FASEB Journal. - : WILEY. - 0892-6638 .- 1530-6860. ; 34:4, s. 5863-5876
-
Tidskriftsartikel (refereegranskat)abstract
- We examined the role of brown adipose tissue (BAT) for fever and emotional stress-induced hyperthermia. Wild-type and uncoupling protein-1 (UCP-1) knockout mice were injected with lipopolysaccharide intraperitoneally or intravenously, or subjected to cage exchange, and body temperature monitored by telemetry. Both genotypes showed similar febrile responses to immune challenge and both displayed hyperthermia to emotional stress. Neither procedure resulted in the activation of BAT, such as the induction of UCP-1 or peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1 alpha) mRNA, or reduced BAT weight and triglyceride content. In contrast, in mice injected with a beta (3) agonist, UCP-1 and PGC-1 alpha were strongly induced, and BAT weight and triglyceride content reduced. Both lipopolysaccharide and the beta (3) agonist, and emotional stress, induced UCP-3 mRNA in skeletal muscle. A beta (3) antagonist did not attenuate lipopolysaccharide-induced fever, but augmented body temperature decrease and inhibited BAT activation when mice were exposed to cold. An alpha (1)/alpha (2b) antagonist or a 5HT(1A) agonist, which inhibit vasoconstriction, abolished lipopolysaccharide-induced fever, but had no effect on emotional stress-induced hyperthermia. These findings demonstrate that in mice, UCP-1-mediated BAT thermogenesis does not take part in inflammation-induced fever, which is dependent on peripheral vasoconstriction, nor in stress-induced hyperthermia. However, both phenomena may involve UCP-3-mediated muscle thermogenesis.
|
|
| 9. |
- Klawonn, Anna, et al.
(författare)
-
Microglial activation elicits a negative affective state through prostaglandin-mediated modulation of striatal neurons
- 2021
-
Ingår i: Immunity. - : CELL PRESS. - 1074-7613 .- 1097-4180. ; 54:2, s. 225-234.e6
-
Tidskriftsartikel (refereegranskat)abstract
- Microglia are activated in many neurological diseases and have been suggested to play an important role in the development of affective disorders including major depression. To investigate how microglial signaling regulates mood, we used bidirectional chemogenetic manipulations of microglial activity in mice. Activation of microglia in the dorsal striatum induced local cytokine expression and a negative affective state characterized by anhedonia and aversion, whereas inactivation of microglia blocked aversion induced by systemic inflammation. Interleukin-6 signaling and cyclooxygenase-1 mediated prostaglandin synthesis in the microglia were critical for the inflammation-induced aversion. Correspondingly, microglial activation led to a prostaglandin-dependent reduction of the excitability of striatal neurons. These findings demonstrate a mechanism by which microglial activation causes negative affect through prostaglandin-dependent modulation of striatal neurons and indicate that interference with this mechanism could milden the depressive symptoms in somatic and psychiatric diseases involving microglial activation.
|
|
| 10. |
- Mirrasekhian, Elahe, 1978-
(författare)
-
Immune-to-Brain Signaling in Fever : The Brain Endothelium as Interface
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fever is a brain-regulated elevation of body temperature that occurs in response to infectious and non-infectious stimuli. During inflammatory episodes, circulating cytokines that are released by activated immune cells, trigger the induction of cyclooxygenase (COX)-2 in the ventromedial preoptic area of the hypothalamus (the thermoregulation center). COX-2-dependent-prostaglandin (PG)E2 synthesis is essential for the generation of fever and upon an immune challenge, it is induced in several cells within the brain including the brain endothelial cells and perivascular macrophages. However, due to lack of experimental models with cell type-specific modulation of PGE2 synthesizing enzymes, the cellular source of pyrogenic PGE2 and its induction mechanism(s) remained obscure. Using such technology, we showed that the brain endothelium is the cellular source of pyrogenic PGE2 and that activation of brain endothelial IL-6 receptors by circulating IL-6 is critical for the PGE2 induction.Inhibition of PGE2 synthesis is assumed to be the mode of action of many antipyretic drugs, possibly including paracetamol. Given that paracetamol at a high dose has been shown to induce hypothermia by activation of the transient receptor potential ankyrin 1 (TRPA1) ion channel, we examined whether the antipyretic effect of paracetamol is also TRPA1 dependent. Our findings revealed that the antipyretic effect of paracetamol is independent of TRPA1 and associated with inhibition of the PGE2 synthesis in the brain.This thesis provides new insight into the molecular mechanism behind the febrile response in which the peripheral circulating IL-6 communicates with the brain by induction of pyrogenic PGE2 in the brain endothelium. It also demonstrates that the antipyretic effect of paracetamol is exerted by inhibition of the PGE2 synthesis in the brain.
|
|
