TY  - JOUR
A1  - Schanbacher, Constanze
A1  - Bieber, Michael
A1  - Reinders, Yvonne
A1  - Cherpokova, Deya
A1  - Teichert, Christina
A1  - Nieswandt, Bernhard
A1  - Sickmann, Albert
A1  - Kleinschnitz, Christoph
A1  - Langhauser, Friederike
A1  - Lorenz, Kristina
T1  - ERK1/2 activity is critical for the outcome of ischemic stroke
JF  - International Journal of Molecular Sciences
N2  - Ischemic disorders are the leading cause of death worldwide. The extracellular signal-regulated kinases 1 and 2 (ERK1/2) are thought to affect the outcome of ischemic stroke. However, it is under debate whether activation or inhibition of ERK1/2 is beneficial. In this study, we report that the ubiquitous overexpression of wild-type ERK2 in mice (ERK2\(^{wt}\)) is detrimental after transient occlusion of the middle cerebral artery (tMCAO), as it led to a massive increase in infarct volume and neurological deficits by increasing blood–brain barrier (BBB) leakiness, inflammation, and the number of apoptotic neurons. To compare ERK1/2 activation and inhibition side-by-side, we also used mice with ubiquitous overexpression of the Raf-kinase inhibitor protein (RKIP\(^{wt}\)) and its phosphorylation-deficient mutant RKIP\(^{S153A}\), known inhibitors of the ERK1/2 signaling cascade. RKIP\(^{wt}\) and RKIP\(^{S153A}\) attenuated ischemia-induced damages, in particular via anti-inflammatory signaling. Taken together, our data suggest that stimulation of the Raf/MEK/ERK1/2-cascade is severely detrimental and its inhibition is rather protective. Thus, a tight control of the ERK1/2 signaling is essential for the outcome in response to ischemic stroke.
KW  - ERK1/2
KW  - tMCAO
KW  - ischemic stroke
KW  - RKIP
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-283991
SN  - 1422-0067
VL  - 23
IS  - 2
ER  - 
TY  - JOUR
A1  - Schuhmann, Michael K.
A1  - Langhauser, Friederike
A1  - Kraft, Peter
A1  - Kleinschnitz, Christoph
T1  - B cells do not have a major pathophysiologic role in acute ischemic stroke in mice
JF  - Journal of Neuroinflammation
N2  - Background
Lymphocytes have been shown to play an important role in the pathophysiology of acute ischemic stroke, but the properties of B cells remain controversial. The aim of this study was to unravel the role of B cells during acute cerebral ischemia using pharmacologic B cell depletion, B cell transgenic mice, and adoptive B cell transfer experiments.

Methods
Transient middle cerebral artery occlusion (60 min) was induced in wild-type mice treated with an anti-CD20 antibody 24 h before stroke onset, JHD\(^{−/−}\) mice and Rag1\(^{−/−}\) mice 24 h after adoptive B cell transfer. Stroke outcome was assessed at days 1 and 3. Infarct volumes were calculated from 2,3,5-triphenyltetrazolium chloride (TTC)-stained brain sections, and neurological scores were evaluated. The local inflammatory response was determined by real-time PCR and immunohistochemistry. Apoptosis was analyzed by TUNEL staining, and astrocyte activation was revealed using immunohistochemistry and Western blot.

Results
Pharmacologic depletion of B cells did not influence infarct volumes and functional outcome at day 1 after stroke. Additionally, lack of circulating B cells in JHD\(^{−/−}\) mice also failed to influence stroke outcome at days 1 and 3. Furthermore, reconstitution of Rag1\(^{−/−}\) mice with B cells had no influence on infarct volumes.

Conclusion
Targeting B cells in experimental stroke did not influence lesion volume and functional outcome during the acute phase. Our findings argue against a major pathophysiologic role of B cells during acute ischemic stroke.
KW  - ischemic stroke
KW  - transient middle cerebral artery occlusion
KW  - B cells
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158155
VL  - 14
IS  - 112
ER  -