Elevated PTEN expression maintains anergy in human B cells and reveals unexpectedly high repertoire autoreactivity
Mia J. Smith, … , Peter A. Gottlieb, John C. Cambier
Mia J. Smith, … , Peter A. Gottlieb, John C. Cambier
Published February 7, 2019
Citation Information: JCI Insight. 2019;4(3):e123384. https://doi.org/10.1172/jci.insight.123384.
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Research Article Immunology

Elevated PTEN expression maintains anergy in human B cells and reveals unexpectedly high repertoire autoreactivity

Abstract

It has been reported that 2.5%–30% of human peripheral CD27– B cells are autoreactive and anergic based on unresponsiveness to antigen receptor (BCR) stimulation and autoreactivity of cloned and expressed BCR. The molecular mechanisms that maintain this unresponsiveness are unknown. Here, we showed that in humans anergy is maintained by elevated expression of PTEN, a phosphatidylinositol 3,4,5P-3-phosphatase. Upregulation of PTEN was associated with reduced expression of microRNAs that control its expression. Pharmacologic inhibition of PTEN lead to significant restoration of responsiveness. Consistent with a role in conferring risk of autoimmunity, B cells from type 1 diabetics and autoimmune thyroid disease patients expressed reduced PTEN. Unexpectedly, in healthy individuals PTEN expression was elevated in on average 40% of CD27– B cells, with levels gradually decreasing as IgM levels increase. Our findings suggest that a much higher proportion of the peripheral repertoire is autoreactive than previously thought and that B cells upregulate PTEN in a manner that is proportional to the recognition of autoantigens of increasing avidity, thus tuning BCR signaling to prevent development of autoimmunity while providing a reservoir of cells that can be readily activated to respond when needed.

Authors

Mia J. Smith, B. Rhodes Ford, Marynette Rihanek, Brianne M. Coleman, Andrew Getahun, Virginia D. Sarapura, Peter A. Gottlieb, John C. Cambier

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Figure 2

PTEN limits signaling in anergic B cells.

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PTEN limits signaling in anergic B cells. (A) miRNA-7, -21, and -92a (bu...
(A) miRNA-7, -21, and -92a (but not miRNA-22) are decreased in BND cells compared with mature naive (MN) B cells; the miRNA comparison was compiled from n = 5 healthy individuals. Statistics were determined using unpaired Mann-Whitney t test. (B) Inhibition of PTEN with 325 μM SF1670 restores Ca2+ mobilization in BND cells to similar levels to MN B cells. Representative plot shown for n = 5 healthy individuals. (C) The change in the AUC in BND and MN B cells following addition of SF1670, ran in triplicates. Data are representative of n = 5 healthy individuals. (D and F) Inhibition of PTEN with SF1670 causes an elevation in basal pPLCy2 and pAkt in BND cells, (E and G) without an overall increase in change in pPLCy2 or pAkt following stimulation. (H and I) Basal and changes in pSyk following stimulation were unchanged following addition of the PTEN inhibitor in BND cells. Phosflow samples were run and analyzed in triplicates. Data depict results from triplicate samples from the same individual; data is representative of n = 9 independent experiments. Statistics were determined using 1-way ANOVA followed by a Bonferroni’s multiple comparison post-test test; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.