13188
2013
eng
16
5
article
1
2016-04-12
--
--
Ischemia-induced cell depolarization: does the hyperpolarization-activated cation channel HCN2 affect the outcome after stroke in mice?
Background
Brain ischemia is known to include neuronal cell death and persisting neurological deficits. A lack of oxygen and glucose are considered to be key mediators of ischemic neurodegeneration while the exact mechanisms are yet unclear. In former studies the expression of two different two-pore domain potassium \((K_{2P})\) channels (TASK1, TREK1) were shown to ameliorate neuronal damage due to cerebral ischemia. In neurons, TASK channels carrying hyperpolarizing \(K^+\) leak currents, and the pacemaker channel HCN2, carrying depolarizing \(I_h\), stabilize the membrane potential by a mutual functional interaction. It is assumed that this ionic interplay between TASK and HCN2 channels enhances the resistance of neurons to insults accompanied by extracellular pH shifts.
Methods
In C57Bl/6 (wildtype, WT), \(hcn2^{+/+}\) and \(hcn2^{-/-}\) mice we used an in vivo model of cerebral ischemia (transient middle cerebral artery occlusion (tMCAO)) to depict a functional impact of HCN2 in stroke formation. Subsequent analyses comprise behavioural tests and hcn2 gene expression assays.
Results
After 60 min of tMCAO induction in WT mice, we collected tissue samples at 6, 12, and 24 h after reperfusion. In the infarcted neocortex, hcn2 expression analyses revealed a nominal peak of hcn2 expression 6 h after reperfusion with a tendency towards lower expression levels with longer reperfusion times. Hcn2 gene expression levels in infarcted basal ganglia did not change after 6 h and 12 h. Only at 24 h after reperfusion, hcn2 expression significantly decreases by ~55%. However, 30 min of tMCAO in hcn2-/- as well as hcn2+/+ littermates induced similar infarct volumes. Behavioural tests for global neurological function (Bederson score) and motor function/coordination (grip test) were performed at day 1 after surgery. Again, we found no differences between the groups.
Conclusions
Here, we hypothesized that the absence of HCN2, an important functional counter player of TASK channels, affects neuronal survival during stroke-induced tissue damage. However, together with a former study on TASK3 these results implicate that both TASK3 and HCN2 which were supposed to be neuroprotective due to their pH-dependency, do not influence ischemic neurodegeneration during stroke in the tMCAO model.
Experimental & Translational Stroke Medicine
10.1186/2040-7378-5-16
urn:nbn:de:bvb:20-opus-131887
Experimental & Translational Stroke Medicine 2013, 5:16. doi:10.1186/2040-7378-5-16
Petra Ehling
Eva Göb
Stefan Bittner
Thomas Budde
Andreas Ludwig
Christoph Kleinschnitz
Sven G. Meuth
eng
uncontrolled
ischemia
Medizin und Gesundheit
open_access
Neurologische Klinik und Poliklinik
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/13188/038_Ehling_Ischemia-induced.pdf
12924
2013
eng
16
5
article
1
2016-03-10
--
--
Ischemia-induced cell depolarization: does the hyperpolarization-activated cation channel HCN2 affect the outcome after stroke in mice?
Background
Brain ischemia is known to include neuronal cell death and persisting neurological deficits. A lack of oxygen and glucose are considered to be key mediators of ischemic neurodegeneration while the exact mechanisms are yet unclear. In former studies the expression of two different two-pore domain potassium \((K_{2P})\) channels (TASK1, TREK1) were shown to ameliorate neuronal damage due to cerebral ischemia. In neurons, TASK channels carrying hyperpolarizing \(K^+\) leak currents, and the pacemaker channel HCN2, carrying depolarizing Ih, stabilize the membrane potential by a mutual functional interaction. It is assumed that this ionic interplay between TASK and HCN2 channels enhances the resistance of neurons to insults accompanied by extracellular pH shifts.
Methods
In C57Bl/6 (wildtype, WT), \(hcn2^{+/+}\) and \(hcn2^{-/-}\) mice we used an in vivo model of cerebral ischemia (transient middle cerebral artery occlusion (tMCAO)) to depict a functional impact of HCN2 in stroke formation. Subsequent analyses comprise behavioural tests and hcn2 gene expression assays.
Results
After 60 min of tMCAO induction in WT mice, we collected tissue samples at 6, 12, and 24 h after reperfusion. In the infarcted neocortex, hcn2 expression analyses revealed a nominal peak of hcn2 expression 6 h after reperfusion with a tendency towards lower expression levels with longer reperfusion times. Hcn2 gene expression levels in infarcted basal ganglia did not change after 6 h and 12 h. Only at 24 h after reperfusion, hcn2 expression significantly decreases by ~55%. However, 30 min of tMCAO in hcn2-/- as well as hcn2+/+ littermates induced similar infarct volumes. Behavioural tests for global neurological function (Bederson score) and motor function/coordination (grip test) were performed at day 1 after surgery. Again, we found no differences between the groups.
Conclusions
Here, we hypothesized that the absence of HCN2, an important functional counter player of TASK channels, affects neuronal survival during stroke-induced tissue damage. However, together with a former study on TASK3 these results implicate that both TASK3 and HCN2 which were supposed to be neuroprotective due to their pH-dependency, do not influence ischemic neurodegeneration during stroke in the tMCAO model.
Experimental & Translational Stroke Medicine
10.1186/2040-7378-5-16
urn:nbn:de:bvb:20-opus-129240
Experimental & Translational Stroke Medicine 2013 5:16. doi:10.1186/2040-7378-5-16
Petra Ehling
Eva Göb
Stefan Bittner
Thomas Budde
Andreas Ludwig
Christoph Kleinschnitz
Sven G. Meuth
eng
uncontrolled
neurology
Medizin und Gesundheit
open_access
Neurologische Klinik und Poliklinik
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/12924/131_Ehling_Exp_Transl_Stroke_Med.pdf
13933
2011
eng
R21
13
article
1
2016-10-14
--
--
Expression of K\(_2\)\(_P\)5.1 potassium channels on CD4\(^+\)T lymphocytes correlates with disease activity in rheumatoid arthritis patients
Introduction
CD4+ T cells express K2P5.1 (TWIK-related acid-sensitive potassium channel 2 (TASK2); KCNK5), a member of the two-pore domain potassium channel family, which has been shown to influence T cell effector functions. Recently, it was shown that K2P5.1 is upregulated upon (autoimmune) T cell stimulation. The aim of this study was to correlate expression levels of K2P5.1 on T cells from patients with rheumatoid arthritis (RA) to disease activity in these patients.
Methods
Expression levels of K2P5.1 were measured by RT-PCR in the peripheral blood of 58 patients with RA and correlated with disease activity parameters (C-reactive protein levels, erythrocyte sedimentation rates, disease activity score (DAS28) scores). Twenty patients undergoing therapy change were followed-up for six months. Additionally, synovial fluid and synovial biopsies were investigated for T lymphocytes expressing K2P5.1.
Results
K2P5.1 expression levels in CD4+ T cells show a strong correlation to DAS28 scores in RA patients. Similar correlations were found for serological inflammatory parameters (erythrocyte sedimentation rate, C-reactive protein). In addition, K2P5.1 expression levels of synovial fluid-derived T cells are higher compared to peripheral blood T cells. Prospective data in individual patients show a parallel behaviour of K2P5.1 expression to disease activity parameters during a longitudinal follow-up for six months.
Conclusions
Disease activity in RA patients correlates strongly with K2P5.1 expression levels in CD4+ T lymphocytes in the peripheral blood in cross-sectional as well as in longitudinal observations. Further studies are needed to investigate the exact pathophysiological mechanisms and to evaluate the possible use of K2P5.1 as a potential biomarker for disease activity and differential diagnosis.
Arthritis Research & Therapy
10.1186/ar3245
urn:nbn:de:bvb:20-opus-139334
Arthritis Research & Therapy 2011 13:R21.
Stefan Bittner
Nicole Bobak
Martin Feuchtenberger
Alexander M Herrmann
Kerstin Göbel
Raimund W Kinne
Anker J Hansen
Thomas Budde
Christoph Kleinschnitz
Oliver Frey
Hans-Peter Tony
Heinz Wiendl
Sven G Meuth
eng
uncontrolled
neurology
Medizin und Gesundheit
open_access
Neurologische Klinik und Poliklinik
Medizinische Klinik und Poliklinik II
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/13933/050_Bittner_Arthritis-Research-and-Therapy.pdf