Bruton tyrosine kinase deficiency augments NLRP3 inflammasome activation and causes IL-1β–mediated colitis
Liming Mao, … , Adrian Wiestner, Warren Strober
Liming Mao, … , Adrian Wiestner, Warren Strober
Published January 2, 2020
Citation Information: J Clin Invest. 2020;130(4):1793-1807. https://doi.org/10.1172/JCI128322.
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Research Article Gastroenterology

Bruton tyrosine kinase deficiency augments NLRP3 inflammasome activation and causes IL-1β–mediated colitis

Abstract

Bruton tyrosine kinase (BTK) is present in a wide variety of cells and may thus have important non–B cell functions. Here, we explored the function of this kinase in macrophages with studies of its regulation of the NLR family, pyrin domain–containing 3 (NLRP3) inflammasome. We found that bone marrow–derived macrophages (BMDMs) from BTK-deficient mice or monocytes from patients with X-linked agammaglobulinemia (XLA) exhibited increased NLRP3 inflammasome activity; this was also the case for BMDMs exposed to low doses of BTK inhibitors such as ibrutinib and for monocytes from patients with chronic lymphocytic leukemia being treated with ibrutinib. In mechanistic studies, we found that BTK bound to NLRP3 during the priming phase of inflammasome activation and, in doing so, inhibited LPS- and nigericin-induced assembly of the NLRP3 inflammasome during the activation phase of inflammasome activation. This inhibitory effect was caused by BTK inhibition of protein phosphatase 2A–mediated (PP2A-mediated) dephosphorylation of Ser5 in the pyrin domain of NLRP3. Finally, we show that BTK-deficient mice were subject to severe experimental colitis and that such colitis was normalized by administration of anti–IL-β or anakinra, an inhibitor of IL-1β signaling. Together, these studies strongly suggest that BTK functions as a physiologic inhibitor of NLRP3 inflammasome activation and explain why patients with XLA are prone to develop Crohn’s disease.

Authors

Liming Mao, Atsushi Kitani, Eitaro Hiejima, Kim Montgomery-Recht, Wenchang Zhou, Ivan Fuss, Adrian Wiestner, Warren Strober

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Figure 1

BTK deficiency causes increased NLRP3 inflammasome activation in murine and human cells.

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BTK deficiency causes increased NLRP3 inflammasome activation in murine ...
(A–C) Murine BMDMs were primed with LPS (200 ng/mL) for 3 hours and then stimulated with nigericin (NI) (1 μM) or ATP (5 mM) for 30 minutes. The culture supernatants were then subjected to ELISA to detect mature IL-1β (mIL-1β) (A) and mature IL-6 (mIL-6) (B) and WB to detect mature IL-1β and caspase-1 (C). (D and E) Mouse BMDCs were treated as above, and the culture supernatants were subjected to IL-1β (D) and IL-6 (E) ELISAs. (F–H) BMDMs from WT or BTK-KO mice were transduced with a lentiviral vector expressing BTK or an empty vector control for 48 hours and then primed with LPS (200 ng/mL) for 3 hours, followed by stimulation with nigericin (1 μM) for 30 minutes. Next, the cells were lysed and the lysates subjected to WB for detection of BTK and NLRP3 (F). Culture supernatants were collected for IL-1β (G) and IL-6 (H) ELISAs. (I and J) Human monocytes from patients with XLA (XLA pts) (n = 4) and healthy individuals (NCs) (n = 4) were primed with LPS (200 ng/mL) for 3 hours and then stimulated with ATP (5 mM) or nigericin (1 μM) for 30 minutes. The culture supernatants were then subjected to IL-1β (I) and IL-6 (J) ELISAs. **P < 0.01, by 1-way ANOVA with multiple comparisons test (A, B, D, E, G, and H) and 2-tailed Student t test (I and J). Data are presented as the mean ± SD and are representative of 3 independent experiments. α, anti.