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Bruton's tyrosine kinase is essential for NLRP3 inflammasome activation and contributes to ischaemic brain injury.

Ito M, Shichita T, Okada M, Komine R, Noguchi Y, Yoshimura A, Morita R - Nat Commun (2015)

Bottom Line: Inflammasomes mediate activation of caspase-1, which subsequently induces secretion of pro-inflammatory cytokines such as IL-1β and IL-18, as well as a form of cell death called pyroptosis.Inhibition of BTK by pharmacological or genetic means severely impairs activation of the NLRP3 inflammasome.Our study indicates that BTK is essential for NLRP3 inflammasome activation and could be a potent therapeutic target in ischaemic stroke.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Microbiology and Immunology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan [2] Japan Science and Technology Agency (JST), CREST, Chiyoda-ku, Tokyo 102-0075, Japan.

ABSTRACT
Inflammasome activation has been implicated in various inflammatory diseases including post-ischaemic inflammation after stroke. Inflammasomes mediate activation of caspase-1, which subsequently induces secretion of pro-inflammatory cytokines such as IL-1β and IL-18, as well as a form of cell death called pyroptosis. In this study, we report that Bruton's tyrosine kinase (BTK) is an essential component of the NLRP3 inflammasome, in which BTK physically interacts with ASC and NLRP3. Inhibition of BTK by pharmacological or genetic means severely impairs activation of the NLRP3 inflammasome. The FDA-approved BTK inhibitor ibrutinib (PCI-32765) efficiently suppresses infarct volume growth and neurological damage in a brain ischaemia/reperfusion model in mice. Ibrutinib inhibits maturation of IL-1β by suppressing caspase-1 activation in infiltrating macrophages and neutrophils in the infarcted area of ischaemic brain. Our study indicates that BTK is essential for NLRP3 inflammasome activation and could be a potent therapeutic target in ischaemic stroke.

No MeSH data available.


Related in: MedlinePlus

Neuronal protection and inhibition of IL-1β maturation by ibrutinib in ischaemic brain injury.Infarct volume on day 4 after stroke onset (a) and neurological scores (b) of mice treated with PBS or ibrutinib (3.125 mg kg−1 per day on Day 0, 1) immediately after stroke onset (n=9 for PBS and n=8 for ibrutinib). Infarct volume on day 4 after stroke onset of mice treated with PBS or ibrutinib 12 (c) or 24 h (d) after stroke onset (n=6). Scale bars, 1 mm (a,c,d). (e) mRNA levels of IL-1β or IL-6 in the ischaemic brain tissue on day 1 and 4 after stroke onset (n=3). (f) Enzyme-linked immunosorbent assay of IL-1β, IL-6 or TNF-α in the ischaemic brain lysate on day 1 after stroke onset (n=3). (g) mRNA levels of IL-1β or IL-6 in the ischaemic brain on day 1 after stroke onset (n=3). (h) mRNA levels of IL-1β, IL-6 or IL-23 in mononuclear cell fractions on day 1 after stroke onset (n=5). Data are representative of three independent experiments. Data are presented as mean±s.e.m. *P<0.05; **P<0.01. Two-sided Student's t-test.
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f3: Neuronal protection and inhibition of IL-1β maturation by ibrutinib in ischaemic brain injury.Infarct volume on day 4 after stroke onset (a) and neurological scores (b) of mice treated with PBS or ibrutinib (3.125 mg kg−1 per day on Day 0, 1) immediately after stroke onset (n=9 for PBS and n=8 for ibrutinib). Infarct volume on day 4 after stroke onset of mice treated with PBS or ibrutinib 12 (c) or 24 h (d) after stroke onset (n=6). Scale bars, 1 mm (a,c,d). (e) mRNA levels of IL-1β or IL-6 in the ischaemic brain tissue on day 1 and 4 after stroke onset (n=3). (f) Enzyme-linked immunosorbent assay of IL-1β, IL-6 or TNF-α in the ischaemic brain lysate on day 1 after stroke onset (n=3). (g) mRNA levels of IL-1β or IL-6 in the ischaemic brain on day 1 after stroke onset (n=3). (h) mRNA levels of IL-1β, IL-6 or IL-23 in mononuclear cell fractions on day 1 after stroke onset (n=5). Data are representative of three independent experiments. Data are presented as mean±s.e.m. *P<0.05; **P<0.01. Two-sided Student's t-test.

Mentions: NLRP3-mediated IL-1α/β has been shown to contribute to the progression of cerebral ischaemic injury14. We confirmed that IL-1α/β knockout mice, in which both IL-1α and IL-1β were functionally deficient40, were highly resistant to ischaemic brain injury (Supplementary Fig. 9a). Previous studies have shown that caspase-1 deficiency and caspase-1 inhibitor strongly suppress ischaemic brain damage4142. Thus, the inflammasome-caspase-1 cascade plays an important role in brain damage. Therefore, we investigated the therapeutic effect of ibrutinib on the stroke model. The dosage of ibrutinib used in this experiment was equal to that used in a previously published mouse CIA model3643. When ibrutinib was administered twice by intravenous injection (3.125 mg per kg body weight), once immediately after reperfusion (on day 0) and once 24 h after later (on day 1), the infarct area was significantly reduced compared with PBS-injected control (Fig. 3a). Neurological deficits were also improved by ibrutinib treatment (Fig. 3b). To determine the therapeutic time window, we examined the effect of BTK inhibitor administration 12 and 24 h after stroke onset. Administration of ibrutinib 12 h after stroke onset still significantly reduced ischaemic brain damage (Fig. 3c); administration 24 h after stroke onset, however, did not result in any protective effect (Fig. 3d). This indicates that ibrutinib inhibits early events occurring within 24 h after ischaemia.


Bruton's tyrosine kinase is essential for NLRP3 inflammasome activation and contributes to ischaemic brain injury.

Ito M, Shichita T, Okada M, Komine R, Noguchi Y, Yoshimura A, Morita R - Nat Commun (2015)

Neuronal protection and inhibition of IL-1β maturation by ibrutinib in ischaemic brain injury.Infarct volume on day 4 after stroke onset (a) and neurological scores (b) of mice treated with PBS or ibrutinib (3.125 mg kg−1 per day on Day 0, 1) immediately after stroke onset (n=9 for PBS and n=8 for ibrutinib). Infarct volume on day 4 after stroke onset of mice treated with PBS or ibrutinib 12 (c) or 24 h (d) after stroke onset (n=6). Scale bars, 1 mm (a,c,d). (e) mRNA levels of IL-1β or IL-6 in the ischaemic brain tissue on day 1 and 4 after stroke onset (n=3). (f) Enzyme-linked immunosorbent assay of IL-1β, IL-6 or TNF-α in the ischaemic brain lysate on day 1 after stroke onset (n=3). (g) mRNA levels of IL-1β or IL-6 in the ischaemic brain on day 1 after stroke onset (n=3). (h) mRNA levels of IL-1β, IL-6 or IL-23 in mononuclear cell fractions on day 1 after stroke onset (n=5). Data are representative of three independent experiments. Data are presented as mean±s.e.m. *P<0.05; **P<0.01. Two-sided Student's t-test.
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Related In: Results  -  Collection

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f3: Neuronal protection and inhibition of IL-1β maturation by ibrutinib in ischaemic brain injury.Infarct volume on day 4 after stroke onset (a) and neurological scores (b) of mice treated with PBS or ibrutinib (3.125 mg kg−1 per day on Day 0, 1) immediately after stroke onset (n=9 for PBS and n=8 for ibrutinib). Infarct volume on day 4 after stroke onset of mice treated with PBS or ibrutinib 12 (c) or 24 h (d) after stroke onset (n=6). Scale bars, 1 mm (a,c,d). (e) mRNA levels of IL-1β or IL-6 in the ischaemic brain tissue on day 1 and 4 after stroke onset (n=3). (f) Enzyme-linked immunosorbent assay of IL-1β, IL-6 or TNF-α in the ischaemic brain lysate on day 1 after stroke onset (n=3). (g) mRNA levels of IL-1β or IL-6 in the ischaemic brain on day 1 after stroke onset (n=3). (h) mRNA levels of IL-1β, IL-6 or IL-23 in mononuclear cell fractions on day 1 after stroke onset (n=5). Data are representative of three independent experiments. Data are presented as mean±s.e.m. *P<0.05; **P<0.01. Two-sided Student's t-test.
Mentions: NLRP3-mediated IL-1α/β has been shown to contribute to the progression of cerebral ischaemic injury14. We confirmed that IL-1α/β knockout mice, in which both IL-1α and IL-1β were functionally deficient40, were highly resistant to ischaemic brain injury (Supplementary Fig. 9a). Previous studies have shown that caspase-1 deficiency and caspase-1 inhibitor strongly suppress ischaemic brain damage4142. Thus, the inflammasome-caspase-1 cascade plays an important role in brain damage. Therefore, we investigated the therapeutic effect of ibrutinib on the stroke model. The dosage of ibrutinib used in this experiment was equal to that used in a previously published mouse CIA model3643. When ibrutinib was administered twice by intravenous injection (3.125 mg per kg body weight), once immediately after reperfusion (on day 0) and once 24 h after later (on day 1), the infarct area was significantly reduced compared with PBS-injected control (Fig. 3a). Neurological deficits were also improved by ibrutinib treatment (Fig. 3b). To determine the therapeutic time window, we examined the effect of BTK inhibitor administration 12 and 24 h after stroke onset. Administration of ibrutinib 12 h after stroke onset still significantly reduced ischaemic brain damage (Fig. 3c); administration 24 h after stroke onset, however, did not result in any protective effect (Fig. 3d). This indicates that ibrutinib inhibits early events occurring within 24 h after ischaemia.

Bottom Line: Inflammasomes mediate activation of caspase-1, which subsequently induces secretion of pro-inflammatory cytokines such as IL-1β and IL-18, as well as a form of cell death called pyroptosis.Inhibition of BTK by pharmacological or genetic means severely impairs activation of the NLRP3 inflammasome.Our study indicates that BTK is essential for NLRP3 inflammasome activation and could be a potent therapeutic target in ischaemic stroke.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Microbiology and Immunology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan [2] Japan Science and Technology Agency (JST), CREST, Chiyoda-ku, Tokyo 102-0075, Japan.

ABSTRACT
Inflammasome activation has been implicated in various inflammatory diseases including post-ischaemic inflammation after stroke. Inflammasomes mediate activation of caspase-1, which subsequently induces secretion of pro-inflammatory cytokines such as IL-1β and IL-18, as well as a form of cell death called pyroptosis. In this study, we report that Bruton's tyrosine kinase (BTK) is an essential component of the NLRP3 inflammasome, in which BTK physically interacts with ASC and NLRP3. Inhibition of BTK by pharmacological or genetic means severely impairs activation of the NLRP3 inflammasome. The FDA-approved BTK inhibitor ibrutinib (PCI-32765) efficiently suppresses infarct volume growth and neurological damage in a brain ischaemia/reperfusion model in mice. Ibrutinib inhibits maturation of IL-1β by suppressing caspase-1 activation in infiltrating macrophages and neutrophils in the infarcted area of ischaemic brain. Our study indicates that BTK is essential for NLRP3 inflammasome activation and could be a potent therapeutic target in ischaemic stroke.

No MeSH data available.


Related in: MedlinePlus