Enhanced Tyrosine Phosphatase Activity Underlies Dysregulated B Cell Receptor Signaling and Promotes Survival of Human Lupus B Cells
- PMID: 26713408
- DOI: 10.1002/art.39559
Enhanced Tyrosine Phosphatase Activity Underlies Dysregulated B Cell Receptor Signaling and Promotes Survival of Human Lupus B Cells
Abstract
Objective: Systemic lupus erythematosus (SLE) is associated with hyperactivity of B cells and abnormalities of B cell receptor (BCR) signaling. To address the linkage between dysregulated BCR signaling and increased B cell function, we assessed immediate phosphorylation events in lupus B cells.
Methods: B cells from SLE patients and healthy donors were analyzed by flow cytometry to assess phosphorylated CD22, Syk, and Akt as well as the basal expression of the BCR coreceptors CD22 and CD19. Confocal microscopy studies determined the recruitment of CD22 and the tyrosine phosphatase SH2 domain-containing phosphatase 1 to the activated BCR complex. Additionally, phosphatase activity in SLE versus healthy donor B cells was measured.
Results: B cells from SLE patients showed diminished Syk phosphorylation and reduced intracellular calcium release after BCR activation as compared to B cells from healthy donors. This was related to an enhanced activity of tyrosine, but not serine/threonine, phosphatases and was corrected by inhibition of tyrosine phosphatase activity. In contrast to reduced Syk phosphorylation after BCR activation, phosphorylation of Akt was significantly increased in SLE B cells. The disturbed balance between Syk and Akt phosphorylation was significantly correlated with B cell survival following BCR engagement. Furthermore, CD27-, but not CD27+, B cells from SLE patients displayed increased expression and phosphorylation of the inhibitory BCR coreceptor CD22.
Conclusion: These results indicate that an imbalance between serine and tyrosine phosphatases in SLE contributes to an intrinsically disturbed balance of BCR-initiated signaling pathways, resulting in enhanced survival of lupus B cells and differentiation into plasma cells.
© 2016, American College of Rheumatology.
Similar articles
-
Therapeutic implications of the anergic/postactivated status of B cells in systemic lupus erythematosus.RMD Open. 2020 Jul;6(2):e001258. doi: 10.1136/rmdopen-2020-001258. RMD Open. 2020. PMID: 32675278 Free PMC article. Review.
-
Increased frequency of a unique spleen tyrosine kinase bright memory B cell population in systemic lupus erythematosus.Arthritis Rheumatol. 2014 Dec;66(12):3424-35. doi: 10.1002/art.38854. Arthritis Rheumatol. 2014. PMID: 25156507
-
Increased Syk phosphorylation leads to overexpression of TRAF6 in peripheral B cells of patients with systemic lupus erythematosus.Lupus. 2015 Jun;24(7):695-704. doi: 10.1177/0961203314560424. Epub 2014 Nov 28. Lupus. 2015. PMID: 25432781
-
CD22 associates with protein tyrosine phosphatase 1C, Syk, and phospholipase C-gamma(1) upon B cell activation.J Exp Med. 1996 Feb 1;183(2):547-60. doi: 10.1084/jem.183.2.547. J Exp Med. 1996. PMID: 8627166 Free PMC article.
-
The mechanistic impact of CD22 engagement with epratuzumab on B cell function: Implications for the treatment of systemic lupus erythematosus.Autoimmun Rev. 2015 Dec;14(12):1079-86. doi: 10.1016/j.autrev.2015.07.013. Epub 2015 Jul 23. Autoimmun Rev. 2015. PMID: 26212727 Review.
Cited by
-
Therapeutic implications of the anergic/postactivated status of B cells in systemic lupus erythematosus.RMD Open. 2020 Jul;6(2):e001258. doi: 10.1136/rmdopen-2020-001258. RMD Open. 2020. PMID: 32675278 Free PMC article. Review.
-
Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition).Eur J Immunol. 2021 Dec;51(12):2708-3145. doi: 10.1002/eji.202170126. Epub 2021 Dec 7. Eur J Immunol. 2021. PMID: 34910301 Free PMC article. Review.
-
2D4, a humanized monoclonal antibody targeting CD132, is a promising treatment for systemic lupus erythematosus.Signal Transduct Target Ther. 2024 Nov 17;9(1):323. doi: 10.1038/s41392-024-02017-6. Signal Transduct Target Ther. 2024. PMID: 39551768 Free PMC article.
-
Age-associated B Cells Appear in Patients with Granulomatous Lung Diseases.Am J Respir Crit Care Med. 2020 Oct 1;202(7):1013-1023. doi: 10.1164/rccm.201911-2151OC. Am J Respir Crit Care Med. 2020. PMID: 32501729 Free PMC article.
-
BTLA Expression and Function Are Impaired on SLE B Cells.Front Immunol. 2021 Apr 22;12:667991. doi: 10.3389/fimmu.2021.667991. eCollection 2021. Front Immunol. 2021. PMID: 33968071 Free PMC article.
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Other Literature Sources
Medical
Research Materials
Miscellaneous