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.
View: Text | PDF
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

×

Figure 3

PTEN expression is correlated with hyporesponsiveness of anergic B cells.

Options: View larger image (or click on image) Download as PowerPoint
PTEN expression is correlated with hyporesponsiveness of anergic B cells...
(A) Gating strategy to determine the geometric mean fluorescence intensity of PTEN in 10% increments of increasing mIgM expression from naive (CD27–) IgD+ B cells in healthy individuals. (B) Representative pattern of PTEN expression versus mIgM expression of CD19+CD27–IgD+ cells from 1 healthy control. Cutoff for determination of PTENhi (gray circles) versus PTEN+/lo (dark gray to black circles) is shown and was determined as the point at which PTEN levels begin to decrease steadily as IgM expression increased. Results depict triplicate samples from the same individual; data are representative of (n = 24) individual experiments. (C) PTEN levels are inversely correlated with IgM expression. A nonlinear regression line is shown. (D) Percentage of PTENhi B cells (gray circles) versus PTEN+/lo B cells (black circles), as determined in B, from 24 healthy controls; the average percentage of PTENhi B cells is approximately 40%. ***P < 0.001 by unpaired Mann-Whitney test. (E) Representative change in pPLCy2 following stimulation (average MFI of unstimulated cells subtracted from individual stimulated MFI) with 10 μg/ml F(ab′)2 rabbit anti-human IgG H&L along the continuum of mIgM expression. (F) Change in pPLCy2 is correlated with IgM expression. A nonlinear regression line is shown. (G) PTEN levels are inversely correlated with change in pPLCy2. A linear regression line is shown. (H) Representative change in pAkt following stimulation, as in F, along the continuum of mIgM expression. (I) Change in pAkt is correlated with IgM expression. A nonlinear regression line is shown. (J) PTEN levels are inversely correlated with change in pAkt. A linear regression line is shown. For E–J, results are representative of at least 5 healthy controls.