| 1. |
- Fenhammar, Johan, et al.
(författare)
-
Renal effects of treatment with a TLR4-inhibitor in conscious septic sheep
- 2014
-
Ingår i: Critical Care. - : Springer Science and Business Media LLC. - 1364-8535 .- 1466-609X. ; 18:5, s. 488-
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Acute kidney injury (AKI) is a common and feared complication of sepsis. The pathogenesis of sepsis-induced AKI is largely unknown, and therapeutic interventions are mainly supportive. In the present study, we tested the hypothesis that pharmacological inhibition of Toll-like receptor 4 (TLR4) would improve renal function and reduce renal damage in experimental sepsis, even after AKI had already developed. Methods: Sheep were surgically instrumented and subjected to a 36-hour intravenous infusion of live Escherichia coli. After 12 hours, they were randomized to treatment with a selective TLR4 inhibitor (TAK-242) or vehicle. Results: The E. coli caused normotensive sepsis characterized by fever, increased cardiac index, hyperlactemia, oliguria, and decreased creatinine clearance. TAK-242 significantly improved creatinine clearance and urine output. The increase in N-acetyl-beta-D-glucosaminidas, a marker of tubular damage, was attenuated. Furthermore, TAK-242 reduced the renal neutrophil accumulation and glomerular endothelial swelling caused by sepsis. These effects were independent of changes in renal artery blood flow and renal microvascular perfusion in both cortex and medulla. TAK-242 had no effect per se on the measured parameters. Conclusions: These results show that treatment with a TLR4 inhibitor is able to reverse a manifest impairment in renal function caused by sepsis. In addition, the results provide evidence that the mechanism underlying the effect of TAK-242 on renal function does not involve improved macro-circulation or micro-circulation, enhanced renal oxygen delivery, or attenuation of tubular necrosis. TLR4-mediated inflammation resulting in glomerular endothelial swelling may be an important part of the pathogenesis underlying Gram-negative septic acute kidney injury.
|
|
| 2. |
- Kenne, Ellinor
(författare)
-
Leukocyte recruitment and control of vascular permeability in acute inflammation
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The inflammatory process is fundamental in host defense against tissue injury or infection. However, the inflammatory reaction may itself cause harm to the host and contribute to tissue damage and organ dysfunction. Leukocyte recruitment and edema formation are key components of the inflammatory response. This thesis reports experiments that were undertaken to further elucidate the mechanisms controlling leukocyte extravasation and concurrent alteration of vascular permeability in acute inflammation. In order for leukocytes to penetrate the vessel wall they need to sequentially interact with the endothelial lining and the perivascular basement membrane (BM) of which laminin-411 is a major constituent. The role of BM laminin-411 in leukocyte recruitment to inflammatory loci was addressed using α4 chain deficient (Lam4-/-) and wild-type (WT) mice. Recruitment of all major leukocyte subsets (neutrophils, monocytes, and lymphocytes) was reduced in Lam4-/- mice compared to WT. With the use of intravital microscopy it was concluded that this decrease was due to impaired diapedesis through the vessel wall. Concurrent with neutrophil recruitment to extravascular tissue, there is an increase in vascular permeability. However, the mechanism behind this alteration is unknown. It was shown that stimulation of neutrophils with the potent chemoattractant leukotriene B4 (LTB4) leads to degranulation and release of, amongst others, heparin binding protein (HBP). Further, postsecretory supernatants from LTB4-stimulated neutrophils induced intracellular calcium mobilization in endothelial cells in vitro and increase in vascular permeability in vivo. Selective removal of HBP from the supernatant significantly reduced these activities indicating a role for HBP in LTB4-induced plasma extravasation. The mechanism behind neutrophil-induced alteration of endothelial barrier function was further investigated and revealed a pivotal role of the kallikrein-kinin system. Neutrophil activation was shown to enable proteolytic processing of high molecular weight kininogen bound to endothelial cells. Accordingly, plasma exudation in vivo in response to challenge with leukocyte chemoattractants was largely annulled by antagonists of the kallikrein-kinin system. Collectively, the data provide novel insight into the regulation of neutrophil-induced plasma extravasation and may help to identify better therapeutic strategies for interventions in inflammatory disease. To investigate the role of neutrophil-induced alterations in vascular permeability in a clinically relevant setting, experiments were performed using controlled cortical impact (CCI) as a model for traumatic brain injury (TBI) in normal mice and in mice that were depleted of neutrophils. Neutrophil depletion did not significantly affect plasma leakage across the bloodbrain barrier after CCI. Yet, neutrophils were found to play a role in edema formation in brain tissue after injury. At a later phase, neutropenic mice displayed a decreased number of activated microglia, and an attenuation of tissue loss after injury. These results suggest that neutrophils contribute to the secondary injury following TBI. Altogether, this thesis provides insight into the role of the BM in leukocyte recruitment and clarifies the mechanism behind neutrophil-induced edema formation in acute inflammation.
|
|
| 3. |
|
|
| 4. |
- Kenne, Ellinor, et al.
(författare)
-
Neutrophil depletion reduces edema formation and tissue loss following traumatic brain injury in mice
- 2012
-
Ingår i: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 9, s. 17-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Brain edema as a result of secondary injury following traumatic brain injury (TBI) is a major clinical concern. Neutrophils are known to cause increased vascular permeability leading to edema formation in peripheral tissue, but their role in the pathology following TBI remains unclear. Methods: In this study we used controlled cortical impact (CCI) as a model for TBI and investigated the role of neutrophils in the response to injury. The outcome of mice that were depleted of neutrophils using an anti-Gr-1 antibody was compared to that in mice with intact neutrophil count. The effect of neutrophil depletion on blood-brain barrier function was assessed by Evan's blue dye extravasation, and analysis of brain water content was used as a measurement of brain edema formation (24 and 48 hours after CCI). Lesion volume was measured 7 and 14 days after CCI. Immunohistochemistry was used to assess cell death, using a marker for cleaved caspase-3 at 24 hours after injury, and microglial/macrophage activation 7 days after CCI. Data were analyzed using Mann-Whitney test for non-parametric data. Results: Neutrophil depletion did not significantly affect Evan's blue extravasation at any time-point after CCI. However, neutrophil-depleted mice exhibited a decreased water content both at 24 and 48 hours after CCI indicating reduced edema formation. Furthermore, brain tissue loss was attenuated in neutropenic mice at 7 and 14 days after injury. Additionally, these mice had a significantly reduced number of activated microglia/macrophages 7 days after CCI, and of cleaved caspase-3 positive cells 24 h after injury. Conclusion: Our results suggest that neutrophils are involved in the edema formation, but not the extravasation of large proteins, as well as contributing to cell death and tissue loss following TBI in mice.
|
|
