scholarly journals XBP-1s Promotes B Cell Pathogenicity in Chronic GVHD by Restraining the Activity of Regulated IRE-1α-Dependent Decay

2021 ◽  
Vol 12 ◽  
Author(s):  
Hee-Jin Choi ◽  
Chih-Hang Anthony Tang ◽  
Linlu Tian ◽  
Yongxia Wu ◽  
M. Hanief Sofi ◽  
...  
Keyword(s):  
Stress Response ◽  
B Cells ◽  
Er Stress ◽  
B Cell ◽  
Hematopoietic Cell Transplantation ◽  
Chronic Gvhd ◽  
Critical Role ◽  
Secretory Cells ◽  
Secretory Proteins ◽  
Er Stress Response

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective therapeutic procedure to treat hematological malignancies. However, the benefit of allo-HCT is limited by a major complication, chronic graft-versus-host disease (cGVHD). Since transmembrane and secretory proteins are generated and modified in the endoplasmic reticulum (ER), the ER stress response is of great importance to secretory cells including B cells. By using conditional knock-out (KO) of XBP-1, IRE-1α or both specifically on B cells, we demonstrated that the IRE-1α/XBP-1 pathway, one of the major ER stress response mediators, plays a critical role in B cell pathogenicity on the induction of cGVHD in murine models of allo-HCT. Endoribonuclease activity of IRE-1α activates XBP-1 signaling by converting unspliced XBP-1 (XBP-1u) mRNA into spliced XBP-1 (XBP-1s) mRNA but also cleaves other ER-associated mRNAs through regulated IRE-1α-dependent decay (RIDD). Further, ablation of XBP-1s production leads to unleashed activation of RIDD. Therefore, we hypothesized that RIDD plays an important role in B cells during cGVHD development. In this study, we found that the reduced pathogenicity of XBP-1 deficient B cells in cGVHD was reversed by RIDD restriction in IRE-1α kinase domain KO mice. Restraining RIDD activity per se in B cells resulted in an increased severity of cGVHD. Besides, inhibition of RIDD activity compromised B cell differentiation and led to dysregulated expression of MHC II and costimulatory molecules such as CD86, CD40, and ICOSL in B cells. Furthermore, restraining the RIDD activity without affecting XBP-1 splicing increased B cell ability to induce cGVHD after allo-HCT. These results suggest that RIDD is an important mediator for reducing cGVHD pathogenesis through targeting XBP-1s.

scholarly journals Ridd Is Required for the Prevention of Chronic Gvhd By Targeting IRE-1a/Xbp-1s Signaling

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1681-1681
Author(s):  
Hee-Jin Choi ◽  
Chih-Hang Anthony Tang ◽  
Linlu Tian ◽  
Yongxia Wu ◽  
Mohammed Hanief Sofi ◽  
...  
Keyword(s):  
T Cells ◽  
Stress Response ◽  
B Cells ◽  
Er Stress ◽  
B Cell ◽  
Critical Role ◽  
Secretory Cells ◽  
Hematopoietic Stem ◽  
Er Stress Response

Abstract Allogeneic hematopoietic stem cell transplantation (allo-HCT) is an effective therapeutic procedure to treat hematological malignancies. However, the benefit of allo-HCT is limited by a major complication, chronic graft-versus-host disease (cGVHD). Since transmembrane and secretory proteins are generated and modified in the endoplasmic reticulum (ER), the ER stress response is of great importance to secretory cells including B cells. By using conditional knock-out (KO) of XBP-1, IRE-1α or both specifically on B cells, we demonstrated that the IRE-1α/XBP-1s pathway, one of the major ER stress response mediators, plays a critical role in B cell pathogenicity on the induction of cGVHD in murine models of allo-HCT. Endoribonuclease activity of IRE-1α not only activates XBP-1s transcription factor by converting unspliced XBP-1 (XBP-1u) mRNA into spliced XBP-1 (XBP-1s) mRNA but also cleaves other ER-associated mRNAs through regulated IRE-1α-dependent decay (RIDD). Besides, it is known that ablation of XBP-1s production leads to unleashed activation of RIDD. Therefore, we hypothesized that RIDD plays an important role in B cells during cGVHD development. In this study, we found that B cells deficient for XBP-1s reduced ability to induce cGVHD, which however was reversed by inactivation of IRE-1α, highlighting the role of RIDD in controlling cGVHD (Fig. A). Activation of RIDD targets IgM mRNA of (Fig. B), a contributor to organ damage and fibrosis in cGVHD, which correlated with dysregulated expression of MHC II and costimulatory molecules such as CD86, CD40, and ICOSL in B cells (Fig. C). Alloreactive T cells need to be primed by APCs to initiate GVHD, and specifically, CD86 and CD40 mediated-costimulation from APCs has been demonstrated to play an essential role in eliciting cGVHD. We demonstrated that alloreactivity of T cells, especially CD4 T cells, can be recovered by suppressing RIDD in XBP-1s-deficient B cells (Fig. D). Since IRE-1α carrying a S729A mutation shows ablated RIDD activity without effect on splicing XBP-1 mRNA, we investigated the contribution of B cells from S729A knock-in mice to confirm the role of RIDD in B cells. We found that B cells from S729A mice increased GVHD severity (Fig. E). S729A B cells showed significant increases in IgM secretion (Fig. F), GC cell differentiation (Fig. G), and the expression levels of MHCII and co-stimulatory factors (Fig. H). In conclusion, these results provide a novel insight on how ER stress response regulates B cell activity after allo-HCT and suggest RIDD is an important mediator for reducing cGVHD pathogenesis. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Prevention of Chronic Gvhd By Targeting Xbp-1 Genetically or Pharmacologically in Mice

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4541-4541
Author(s):  
Steven D Schutt ◽  
Chih-Hang Anthony Tang ◽  
Yongxia Wu ◽  
David A Bastian ◽  
Juan Del Valle ◽  
...  
Keyword(s):  
T Cells ◽  
Stress Response ◽  
B Cells ◽  
Er Stress ◽  
B Cell ◽  
Chronic Gvhd ◽  
Critical Role ◽  
Conditional Knockout ◽  
Er Stress Response

Abstract Inhibition of the endoplasmic reticulum (ER) stress response via blockade of inositol-requiring enzyme-1α (IRE-1α) is currently a promising therapeutic strategy to treat B-cell leukemia, lymphoma, and myeloma. Because B cells play an important role in the development of chronic graft-versus-host disease (cGVHD), we hypothesize that the ER stress response contributes to B-cell function and pathogenicity in cGVHD. Here, we report that the ER stress response mediated by IRE-1α and its target X-box binding protein-1 (XBP-1) plays a critical role in cGVHD pathophysiology and represents a potential therapeutic target to prevent cGVHD. We tested the role of XBP-1 specifically in B cells by testing XBP-1 conditional knockout B cell grafts (XBP1fl/flCD19Cre+) in two mouse models of cGVHD. In the first model (B6 to BALB/c), recipients given XBP-1-deficient donor grafts showed significantly reduced cGVHD clinical scores, which were associated with reduced frequencies of donor-derived CD4 helper T cells within the lungs compared to the recipients of XBP-1fl/flCD19Cre- littermate donor grafts. XBP-1-deficient B cells produced significantly higher levels of IL-10 compared to WT control B cells after activation ex vivo. In the second model (B6 to B10.BR), the conversion of donor B cells to plasma cells (B220+CD38+CD138+) was reduced in both the spleens and lungs of recipients transplanted with XBP1fl/flCD19Cre+ grafts compared to those of the recipients given XBP1fl/flCD19Cre- grafts. Recipients given XBP1fl/flCD19Cre+ grafts also showed significantly higher total splenocytes and vastly increased splenic B-cell populations when compared with the recipients of XBP1fl/flCD19Cre- grafts. To expand on these findings, we tested if systemic XBP-1 blockade via a novel IRE-1α inhibitor, B-I09, would attenuate cGVHD. In a cutaneous model of cGVHD (B10.D2 to BALB/c), we found that prophylactic administration of B-I09 significantly reduced clinical features of cGVHD compared to vehicle controls (Fig. 1A). Validating these findings, hematoxylin and eosin stained skin sections of B-I09-treated mice had significantly lower pathology scores compared to vehicle controls (Fig. 1B). Isolated skin lymphocytes from recipients treated with B-I09 showed significant reductions in donor derived T cells and DCs compared to those treated with vehicle controls (Fig. 1C and D). Taken together, our findings reveal a novel role of the IRE-1α/XBP-1 pathway of the ER stress response in cGVHD pathophysiology and provide a readily translatable strategy to prevent the development of cGVHD in the clinic. Disclosures No relevant conflicts of interest to declare.

scholarly journals PRMT1 suppresses ATF4-mediated endoplasmic reticulum response in cardiomyocytes

2019 ◽  
Vol 10 (12) ◽  
Author(s):  
Myong-Ho Jeong ◽  
Hyeon-Ju Jeong ◽  
Byeong-Yun Ahn ◽  
Jung-Hoon Pyun ◽  
Ilmin Kwon ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Stress Response ◽  
Er Stress ◽  
Regulatory Mechanism ◽  
Critical Role ◽  
Mechanistic Study ◽  
Stress Signaling ◽  
Deficient Mutant ◽  
Er Stress Response

AbstractEndoplasmic reticulum (ER) stress signaling plays a critical role in the control of cell survival or death. Persistent ER stress activates proapoptotic pathway involving the ATF4/CHOP axis. Although accumulating evidences support its important contribution to cardiovascular diseases, but its mechanism is not well characterized. Here, we demonstrate a critical role for PRMT1 in the control of ER stress in cardiomyocytes. The inhibition of PRMT1 augments tunicamycin (TN)-triggered ER stress response in cardiomyocytes while PRMT1 overexpression attenuates it. Consistently, PRMT1 null hearts show exacerbated ER stress and cell death in response to TN treatment. Interestingly, ATF4 depletion attenuates the ER stress response induced by PRMT1 inhibition. The methylation-deficient mutant of ATF4 with the switch of arginine 239 to lysine exacerbates ER stress accompanied by enhanced levels of proapoptotic cleaved Caspase3 and phosphorylated-γH2AX in response to TN. The mechanistic study shows that PRMT1 modulates the protein stability of ATF4 through methylation. Taken together, our data suggest that ATF4 methylation on arginine 239 by PRMT1 is a novel regulatory mechanism for protection of cardiomyocytes from ER stress-induced cell death.

Rituximab Infusion Two Months after HCT Decreases Alloreactive B Cell Responses While Recipient Plasma Cells Persist.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2234-2234 ◽  
Author(s):  
Bi ta Sahaf ◽  
Julie R. Boiko ◽  
George Chen ◽  
Kartoosh Heydari ◽  
Sally Arai ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Hematopoietic Cell Transplantation ◽  
Plasma Cells ◽  
Bone Marrow Cells ◽  
Chronic Gvhd ◽  
Lymphocytic Leukemia ◽  
Facs Analysis ◽  
Peripheral B Cells

Abstract B cells and their effector molecules, antibodies, are implicated in pathophysiology of the chronic graft-vs-host disease (cGVHD) and rituximab is effective cGVHD therapy. Here we investigate B cell reconstitution in bone marrow aspirates collected from 14 mantle cell lymphoma and 22 chronic lymphocytic leukemia patients receiving rituximab infusion 375mg/m2 weekly x 4 beginning 56 days after allogeneic hematopoietic cell transplantation (HCT) following total lymphoid irradiation 80cGy x10 daily fractions and anti-thymoglobulin (1.5 mg/Kg/day x 5). Primary GVHD prophylaxis was mycophenolic acid and cyclosporine tapered off by 6 months. We hypothesized rituximab would deplete alloreactive na•ve and memory B cells and result in less chronic GVHD. Here we present multi-parameter B cell FACS analysis characterizing extent of B cell depletion and developmental stage analysis and subsequent reconstitution kinetics. We collected bone marrow aspirates prior to rituximab, and then days 90, 180, and 365 following HCT. Peripheral B cells were detected in 17 of 34 HCT patients prior to rituximab infusion day 56. Following rituximab, peripheral blood CD19+ B cells were detected in 4 by one year, 18 by 1.5 years, and 9 by 2 years post HCT. Multi-parameter (12 colors-14 parameters) FACS analysis of bone marrow B cells using 2 different cocktails on the same bone marrow cells distinguished: common lymphoid progenitor (CD34+CD117+CD7+), Pro B cells (CD34+CD20−CD10−), pre B cells (CD34−CD20−, CD10+), immature B cell (CD20−CD38−IgM+ IgD low/neg), mature (CD20+CD38+IgD+, IgM+) B cells, and CD38+ CD138+ plasma cells. Despite only modest reconstitution of PERIPHERAL B cells 2 months after HCT (17/32), bone marrow B cells expressing CD19 were present in 9 out of 9 patients at 56 days post HCT and were depleted to less than 0.05% of total lymphocytes after 4 rituximab infusions when measured 90 days post-HCT (below table). Following rituximab, CD19+ B cells were first detected in the bone marrow 180 days after HCT. The mature CD19+ B cells accounted for 2–5% by 365 days post HCT. While rituximab depleted mature B cells, plasma cells remained unchanged. Furthermore, CD138+CD38+ plasma cells were FACS sorted shown by STR DNA polymorphism testing to be recipient derived (n=5). Consistent with observed stable plasma cell frequency, total plasma IgG showed no significant change. Inherited polymorphisms in IgG heavy chain constant regions can be recognized by allotype-specific monoclonal antibodies and thereby distinguish donor and recipient antibodies. Such allotype detection of antimicrobial IgG confirmed stable anti-VZV and EBV as well as recipient origin of these plasma IgG up to 2 years post HCT. In support of our hypothesis, alloreactive IgG responses against 5 minor histocompability antigens (mHA) encoded on Y chromosome (DBY, UTY, ZFY, RPS4Y, and EIF1AY) were decreased in TLI/ATG/rituximab treated patients. None of the 11 male patients with female donors treated with rituximab developed antibodies against H-Y proteins while 12 out of 24 (50%) F̂M undergoing TLI/ATG without rituximab developed allo-antibodies against H-Y proteins (p=0.09). In summary, multi-parameter (12 colors-14 parameters) immunophenotyping of bone marrow shows rituximab treatment two months after allo-HCT causes delayed donor derived B cell reconstitution, persistent antimicrobial IgG from persistent recipient plasma cells, and undetectable allogeneic H-Y antibodies. Summary table. Days after HCT LYMPHOID PROGENITORS CD34+ CD117+ CD7+ PRO B CELLS CD34+ CD20− CD10− PRE B CELLS CD34+ CD20− CD10− MATURE B CELLS CD20+ Ig D+ Ig M+ PLASMA CELLS CD38+ CD138+ TOTAL IgG μg/dl(pre) 56 pre = ritux n = 9 20–25% 2–6% 0.1–4% 0.2–1% 0.7–1% 655 81% 90 n = 25 20–40% 2–9% 0.5–2% ND** 0.5–3% 910 101% 180 n = 28 13–20% 5–12% 0–0.7% ND** 0.5–2% 507 60% 365 n = 16 3–8% 2–10% 0–0.5% 1–5% 0.5–3.7% 642 78%

Inhibition of Autophagy Promotes Bortezomib-Mediated Cell Death in Myeloma Cells

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3677-3677 ◽  
Author(s):  
Terry H. Landowski ◽  
Aluvia M Escalante ◽  
Andrew Jefferson ◽  
Robert T Dorr ◽  
Ronald Lynch
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Stress Response ◽  
Er Stress ◽  
B Cell ◽  
Cellular Stress Response ◽  
Calpain Activity ◽  
B Cell Malignancies ◽  
Myeloma Cells ◽  
Er Stress Response

Abstract The 26S proteasome is a key regulator of proteins controlling many important cellular functions, including cell cycle progression, differentiation, gene transcription and apoptosis. Proteasome inhibition is a new therapeutic strategy that has shown promise in the treatment of B cell malignancies, primarily multiple myeloma. We and others have demonstrated that proteasome inhibitors induce endoplasmic reticulum (ER) stress and activate an unfolded protein response (UPR) in transformed cells. Our previous work demonstrated that bortezomib induces an endoplasmic reticulum (ER) stress response ultimately leading to calcium-dependent apoptotic cell death. Co-treatment of myeloma cells with the mitochondrial uniporter inhibitor ruthenium red (RuR) abrogated bortezomib mediated cell death, indicating that the cytotoxic effects of proteasomal inhibition requires dysregulation of intracellular Ca2+. Intracellular Ca2+ has also been implicated in the cellular stress response known as autophagy or “self-eating”. Macroautophagy (hereafter referred to as autophagy) is induced by various cellular stresses including nutrient deprivation, metabolic insufficiency, interruption of growth factor signaling, elevated ROS, accumulation of intracellular Ca2+, and the UPR. The biochemical events linking the cellular stress response with the induction of autophagy, and the relationship between autophagy and apoptosis is not well understood. In this study, we investigate the role of the Ca2+ dependent serine protease, calpain, as a mediator of the conversion from autophagic cell survival to accelerated cell death in the ER stress response. We demonstrate that the proteasome inhibitor, bortezomib, initiates autophagy in myeloma cells, and protection from bortezomib-mediated cell death by mitochondrial Ca2+ inhibitors is associated with a promotion and stabilization of the autophagosome. This response can be reversed, and indeed, accelerated, leading to enhanced cell death, by blockade of calpain activity. Inhibition of calpain activity with the tri-peptide zLLY-FMK (Calpain Inhibitor IV, (CiIV) or the non-peptide inhibitor, PD150606, demonstrated a significant increase in the cytotoxic activity of bortezomib. Similarly, elimination of the small catalytic subunit, CAPNS1, using siRNA, enhanced bortezomib-mediated cell death, and prevented autophagosome-lysosomal progression. Furthermore, inhibition of calpain by clinically approved HIV protease inhibitors including Nelfinavir, Ritonavir, Saquinavir, and Indinavir sulfate, significantly increased the cytotoxic activity of bortezomib in vitro. We suggest that disregulation of Ca2+ by bortezomib-mediated ER stress activates the autophagic survival response. Inhibition of mitochondrial Ca2+ uptake by the uniporter inhibitor RuR promotes autophagy, and confers resistance to bortezomib. Conversely, inhibition of the Ca2+-dependent serine protease, calpain, prevents autophagolysosome maturation, and subverts the survival response to cell death. These data are likely to have important clinical implications for the treatment of refractory myeloma and other B cell malignancies.

scholarly journals Hyaluronate-CD44 Interactions Can Induce Murine B-Cell Activation

Blood ◽  
1997 ◽  
Vol 89 (8) ◽  
pp. 2901-2908 ◽  
Author(s):  
Asimah Rafi ◽  
Mitzi Nagarkatti ◽  
Prakash S. Nagarkatti
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Critical Role ◽  
Surface Glycoprotein ◽  
B Cell Differentiation ◽  
B Cell Activation ◽  
Cell Surface Glycoprotein ◽  
Immunodeficient Mice

Abstract CD44 is a widely distributed cell surface glycoprotein whose principal ligand has been identified as hyaluronic acid (HA), a major component of the extracellular matrix (ECM). Recent studies have demonstrated that activation through CD44 leads to induction of effector function in T cells and macrophages. In the current study, we investigated whether HA or monoclonal antibodies (MoAbs) against CD44 would induce a proliferative response in mouse lymphocytes. Spleen cells from normal and nude, but not severe combined immunodeficient mice, exhibited strong proliferative responsiveness to stimulation with soluble HA or anti-CD44 MoAbs. Furthermore, purified B cells, but not T cells, were found to respond to HA. HA was unable to stimulate T cells even in the presence of antigen presenting cells (APC) and was unable to act as a costimulus in the presence of mitogenic or submitogenic concentrations of anti-CD3 MoAbs. In contrast, stimulation of B cells with HA in vitro, led to B-cell differentiation as measured by production of IgM antibodies in addition to increased expression of CD44 and decreased levels of CD45R. The fact that the B cells were responding directly to HA through its binding to CD44 and not to any contaminants or endotoxins was demonstrated by the fact that F(ab)2 fragments of anti-CD44 MoAbs or soluble CD44 fusion proteins could significantly inhibit the HA-induced proliferation of B cells. Also, HA-induced proliferation of B cells was not affected by the addition of polymixin B, and B cells from lipopolysaccharide (LPS)-unresponsive C3H/HeJ strain responded strongly to stimulation with HA. Furthermore, HA, but not chondroitin-sulfate, another major component of the ECM, induced B-cell activation. It was also noted that injection of HA intraperitoneally, triggered splenic B cell proliferation in vivo. Together, the current study demonstrates that interaction between HA and CD44 can regulate murine B-cell effector functions and that such interactions may play a critical role during normal or autoimmune responsiveness of B cells.

Targeted regulation of lymphocytic ER stress response with an overall immunosuppression to alleviate allograft rejection

Biomaterials ◽  
2021 ◽  
pp. 120757
Author(s):  
Yingying Shi ◽  
Yichao Lu ◽  
Chunqi Zhu ◽  
Zhenyu Luo ◽  
Xiang Li ◽  
...  
Keyword(s):  
Stress Response ◽  
Er Stress ◽  
Allograft Rejection ◽  
Er Stress Response

scholarly journals Highly Specialized Ubiquitin-Like Modifications: Shedding Light into the UFM1 Enigma

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 255
Author(s):  
Katharina F. Witting ◽  
Monique P.C. Mulder
Keyword(s):  
Dna Repair ◽  
Stress Response ◽  
Embryonic Development ◽  
Er Stress ◽  
Unmet Needs ◽  
Biological Function ◽  
Post Translational Modification ◽  
Er Stress Response ◽  
Cellular Events ◽  
Complex Signaling

Post-translational modification with Ubiquitin-like proteins represents a complex signaling language regulating virtually every cellular process. Among these post-translational modifiers is Ubiquitin-fold modifier (UFM1), which is covalently attached to its substrates through the orchestrated action of a dedicated enzymatic cascade. Originally identified to be involved embryonic development, its biological function remains enigmatic. Recent research reveals that UFM1 regulates a variety of cellular events ranging from DNA repair to autophagy and ER stress response implicating its involvement in a variety of diseases. Given the contribution of UFM1 to numerous pathologies, the enzymes of the UFM1 cascade represent attractive targets for pharmacological inhibition. Here we discuss the current understanding of this cryptic post-translational modification especially its contribution to disease as well as expand on the unmet needs of developing chemical and biochemical tools to dissect its role.

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