scholarly journals CLL-Derived Exosomes Function As Trojan Horses That Induce SMAD6-Dependent Apoptosis of Normal B-Cells

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1734-1734
Author(s):  
Orit Uziel ◽  
Zinab Sarsur- Amer ◽  
Einat Beery ◽  
Pia Raanani ◽  
Uri Rozovski
Keyword(s):  
B Cells ◽  
Time Dependent ◽  
Dependent Manner ◽  
Environmental Resources ◽  
Type B ◽  
Wild Type ◽  
Cell Competition ◽  
Western Immunoblotting ◽  
Competition Theory

Studies from recent years unraveled the role of monocytes and T-cells in the pathogenesis of chronic lymphocytic leukemia (CLL). The role of other immune cells in the pathobiology of CLL is less known. Specifically, whether B-cells, the normal counterpart of CLL cells play a role in CLL is unknown. Nevertheless, since both CLL cells and wild type B-cells reside in lymphatic organs and travel in blood, they either share or compete over common environmental resources. According to the cell competition theory, a sensing mechanism measures the relative fitness of a cell and ensures the elimination of cells deemed to be less fit then their neighbors. Since constitutive activation of intracellular pathways protect CLL cells from apoptosis, the cell competition theory predicts that compared with normal B-cells these cells are sensed as "super fit" and B-cells, the less fit counterparts, are eliminated. Yet, what delivers this massage across a population of cells is unknown. Exosomes are nanosized particles that are secreted by various types of cells. Exosomes carry a cargo of proteins and different types of RNA. They travel in body fluids and are taken up by cells in their vicinity. Since cancer cells including CLL cells secrete exosomes, we have formulated our hypothesis, namely, that exosomes derived from CLL cells are the vehicles that carry a death massage to wild type B-cells. To test this hypothesis, we isolated CLL cells from 3 previously untreated patients with CLL. We then grew these cells in exosome free media for 72 hours and harvested the exosomes by ultracentrifugation. We used NanoSight tracking analysis, Western immunoblotting for CD63, a common exosomal marker, and electron microscopy imaging studies to ensure that our pellet include the typical 100nm exosomal particles. Subsequently, we subjected normal B-cells derived from healthy volunteers to CLL derived exosomes stained by FM-143 dye. Using flow cytometry we found that exosomes are taken up by normal B-cells in a dose- and time- dependent manner. Double staining of the recipient B-cells to Annexin/PI revealed that exosomes induce apoptosis of these cells in a dose- and time- dependent manner. We then used RNA-seq to trace the changes in the molecular makeup of B-cells after exosomal uptake?? they took up exosomes. We found 24 transcripts that were differentially expressed (11 that were upregulated and 13 that were downregulated). We then verified the array results by quantitative real-time PCR for four of these genes. Among the top transcripts that were upregulated in exosome-positive B-cells is SMAD6. Because the upregulation of the SMAD family members including SMAD6 is associated with the induction of apoptosis in various malignant and non-malignant cells we wondered whether the upregulation of SMAD6 also induces apoptosis in normal B-cells. To test this, we transfected normal B-cells with SMAD6 containing vector and verified by RT-PCR that level of SMAD6 transcript were upregulated and by Western immunoblotting that levels of SMAD6 protein are upregulated as well. As expected, the rate of apoptosis was higher, and the rates of viable cells and proliferating cells were significantly lower in SMAD6-transfected B-cells. Taken together, we show here that CLL cells secrete exosomes that function as "Trojan horses". Once they are taken up by normal B-cells they induce SMAD6-dependent apoptosis. In this way the neoplastic cells may actively eliminate their competitors and take over the common environmental resources. Disclosures No relevant conflicts of interest to declare.

scholarly journals Diacylglycerol kinase ζ promotes actin cytoskeleton remodeling and mechanical forces at the B cell immune synapse

2020 ◽  
Vol 13 (627) ◽  
pp. eaaw8214 ◽  
Author(s):  
Sara V. Merino-Cortés ◽  
Sofia R. Gardeta ◽  
Sara Roman-Garcia ◽  
Ana Martínez-Riaño ◽  
Judith Pineau ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Force Generation ◽  
Lymphocyte Function ◽  
Dependent Manner ◽  
Type B ◽  
Wild Type ◽  
Microtubule Organizing Center ◽  
Antigen Uptake ◽  
Immune Synapse

Diacylglycerol kinases (DGKs) limit antigen receptor signaling in immune cells by consuming the second messenger diacylglycerol (DAG) to generate phosphatidic acid (PA). Here, we showed that DGKζ promotes lymphocyte function–associated antigen 1 (LFA-1)–mediated adhesion and F-actin generation at the immune synapse of B cells with antigen-presenting cells (APCs), mostly in a PA-dependent manner. Measurement of single-cell mechanical force generation indicated that DGKζ-deficient B cells exerted lower forces at the immune synapse than did wild-type B cells. Nonmuscle myosin activation and translocation of the microtubule-organizing center (MTOC) to the immune synapse were also impaired in DGKζ-deficient B cells. These functional defects correlated with the decreased ability of B cells to present antigen and activate T cells in vitro. The in vivo germinal center response of DGKζ-deficient B cells was also reduced compared with that of wild-type B cells, indicating that loss of DGKζ in B cells impaired T cell help. Together, our data suggest that DGKζ shapes B cell responses by regulating actin remodeling, force generation, and antigen uptake–related events at the immune synapse. Hence, an appropriate balance in the amounts of DAG and PA is required for optimal B cell function.

scholarly journals Role for Mismatch Repair Proteins Msh2, Mlh1, and Pms2 in Immunoglobulin Class Switching Shown by Sequence Analysis of Recombination Junctions

2002 ◽  
Vol 195 (3) ◽  
pp. 367-373 ◽  
Author(s):  
Carol E. Schrader ◽  
Joycelyn Vardo ◽  
Janet Stavnezer
Keyword(s):  
B Cells ◽  
Mismatch Repair ◽  
Type B ◽  
Wild Type ◽  
Class Switching ◽  
Class Switch ◽  
Mmr Proteins

B cells from mice deficient in mismatch repair (MMR) proteins show decreased ability to undergo class switch recombination in vitro and in vivo. The deficit is not accompanied by any reduction in cell viability or alterations in the cell cycle in B cells cultured in vitro. To assess the role of MMR in switching we examined the nucleotide sequences of Sμ-Sγ3 recombination junctions in splenic B cells induced in culture to switch to IgG3. The data demonstrate clear differences in the sequences of switch junctions in wild-type B cells in comparison with Msh2-, Mlh1-, and Pms2-deficient B cells. Sequences of switch junctions from Msh2-deficient cells showed decreased lengths of microhomology between Sμ and Sγ3 relative to junctions from wild-type cells and an increase in insertions, i.e., nucleotides which do not appear to be derived from either the Sμ or Sγ3 parental sequence. By contrast, 23% of junctions from Mlh1- and Pms2-deficient cells occurred at unusually long stretches of microhomology. The data indicate that MMR proteins are directly involved in class switching and that the role of Msh2 differs from that of Mlh1 and Pms2.

scholarly journals Phosphoinositide 3-Kinase P110δ-Signaling Is Critical for Microbiota-Activated IL-10 Production by B Cells that Regulate Intestinal Inflammation

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1121 ◽  
Author(s):  
Akihiko Oka ◽  
Yoshiyuki Mishima ◽  
Bo Liu ◽  
Jeremy W. Herzog ◽  
Erin C. Steinbach ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Intestinal Inflammation ◽  
Mucosal Inflammation ◽  
Regulatory Function ◽  
Type B ◽  
Wild Type ◽  
Phosphoinositide 3 Kinase

The phosphoinositide 3-kinase catalytic subunit p110δ (PI3Kδ) gene maps to a human inflammatory bowel diseases (IBD) susceptibility locus, and genetic deletion of PI3Kδ signaling causes spontaneous colitis in mice. However, little is known regarding the role of PI3Kδ on IL-10-producing B cells that help regulate mucosal inflammation in IBD. We investigated the role of PI3Kδ signaling in B cell production of IL-10, following stimulation by resident bacteria and B cell regulatory function against colitis. In vitro, B cells from PI3KδD910A/D910A mice or wild-type B cells treated with PI3K specific inhibitors secreted significantly less IL-10 with greater IL-12p40 following bacterial stimulation. These B cells failed to suppress inflammatory cytokines by co-cultured microbiota-activated macrophages or CD4+ T cells. In vivo, co-transferred wild-type B cells ameliorated T cell-mediated colitis, while PI3KδD910A/D910A B cells did not confer protection from mucosal inflammation. These results indicate that PI3Kδ-signaling mediates regulatory B cell immune differentiation when stimulated with resident microbiota or their components, and is critical for induction and regulatory function of IL-10-producing B cells in intestinal homeostasis and inflammation.

scholarly journals Endothelial cell-related autophagic pathways in Sugen/hypoxia-exposed pulmonary arterial hypertensive rats

2017 ◽  
Vol 313 (5) ◽  
pp. L899-L915 ◽  
Author(s):  
Fumiaki Kato ◽  
Seiichiro Sakao ◽  
Takao Takeuchi ◽  
Toshio Suzuki ◽  
Rintaro Nishimura ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Endothelial Cell ◽  
Vascular Remodeling ◽  
Time Dependent ◽  
Causative Role ◽  
Dependent Manner ◽  
Vascular Endothelial ◽  
Pulmonary Vascular Remodeling ◽  
Pulmonary Arterial

Pulmonary arterial hypertension (PAH) is characterized by progressive obstructive remodeling of pulmonary arteries. However, no reports have described the causative role of the autophagic pathway in pulmonary vascular endothelial cell (EC) alterations associated with PAH. This study investigated the time-dependent role of the autophagic pathway in pulmonary vascular ECs and pulmonary vascular EC kinesis in a severe PAH rat model (Sugen/hypoxia rat) and evaluated whether timely induction of the autophagic pathway by rapamycin improves PAH. Hemodynamic and histological examinations as well as flow cytometry of pulmonary vascular EC-related autophagic pathways and pulmonary vascular EC kinetics in lung cell suspensions were performed. The time-dependent and therapeutic effects of rapamycin on the autophagic pathway were also assessed. Sugen/hypoxia rats treated with the vascular endothelial growth factor receptor blocker SU5416 showed increased right ventricular systolic pressure (RVSP) and numbers of obstructive vessels due to increased pulmonary vascular remodeling. The expression of the autophagic marker LC3 in ECs also changed in a time-dependent manner, in parallel with proliferation and apoptotic markers as assessed by flow cytometry. These results suggest the presence of cross talk between pulmonary vascular remodeling and the autophagic pathway, especially in small vascular lesions. Moreover, treatment of Sugen/hypoxia rats with rapamycin after SU5416 injection activated the autophagic pathway and improved the balance between cell proliferation and apoptosis in pulmonary vascular ECs to reduce RVSP and pulmonary vascular remodeling. These results suggested that the autophagic pathway can suppress PAH progression and that rapamycin-dependent activation of the autophagic pathway could ameliorate PAH.

scholarly journals A reassessment of the role of B7-1 expression in tumor rejection.

1995 ◽  
Vol 182 (5) ◽  
pp. 1415-1421 ◽  
Author(s):  
T C Wu ◽  
A Y Huang ◽  
E M Jaffee ◽  
H I Levitsky ◽  
D M Pardoll
Keyword(s):  
T Cells ◽  
Tumor Cells ◽  
Cd8 T Cells ◽  
Tumor Rejection ◽  
Type B ◽  
Wild Type ◽  
Systemic Immunity ◽  
Murine Tumor

Introduction of the B7-1 gene into murine tumor cells can result in rejection of the B7-1 transductants and, in some cases, systemic immunity to subsequent challenge with the nontransduced tumor cells. These effects have been largely attributed to the function of B7-1 as a costimulator in directly activating tumor specific, major histocompatibility class I-restricted CD8+ T cells. We examined the role of B7-1 expression in the direct rejection as well as in the induction of systemic immunity to a nonimmunogenic murine tumor. B-16 melanoma cells with high levels of B7-1 expression did not grow in C57BL/6 recipient mice, while wild-type B-16 cells and cells with low B7-1 expression grew progressively within 21 d. In mixing experiments with B7-1hi and wild-type B-16 cells, tumors grew out in vivo even when a minority of cells were B7-1-. Furthermore, the occasional tumors that grew out after injection of 100% B-16 B7-1hi cells showed markedly decreased B7-1 expression. In vivo antibody depletions showed that NK1.1 and CD8+ T cells, but not CD4+ T cells, were essential for the in vivo rejection of tumors. Animals that rejected B-16 B7-1hi tumors did not develop enhanced systemic immunity against challenge with wild-type B-16 cells. These results suggest that a major role of B7-1 expression by tumors is to mediate direct recognition and killing by natural killer cells. With an intrinsically nonimmunogenic tumor, this direct killing does not lead to enhanced systemic immunity.

scholarly journals Phospholipid flippases enable precursor B cells to flee engulfment by macrophages

2018 ◽  
Vol 115 (48) ◽  
pp. 12212-12217 ◽  
Author(s):  
Katsumori Segawa ◽  
Yuichi Yanagihashi ◽  
Kyoko Yamada ◽  
Chigure Suzuki ◽  
Yasuo Uchiyama ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
B Cell ◽  
Developmental Stages ◽  
Peritoneal Macrophages ◽  
Dependent Manner ◽  
Wild Type ◽  
Immature B Cells ◽  
T Lymphoma ◽  
Precursor B Cells

ATP11A and ATP11C, members of the P4-ATPases, are flippases that translocate phosphatidylserine (PtdSer) from the outer to inner leaflet of the plasma membrane. Using the W3 T lymphoma cell line, we found that Ca2+ ionophore-induced phospholipid scrambling caused prolonged PtdSer exposure in cells lacking both the ATP11A and ATP11C genes. ATP11C-null (ATP11C−/y) mutant mice exhibit severe B-cell deficiency. In wild-type mice, ATP11C was expressed at all B-cell developmental stages, while ATP11A was not expressed after pro−B-cell stages, indicating that ATP11C−/y early B-cell progenitors lacked plasma membrane flippases. The receptor kinases MerTK and Axl are known to be essential for the PtdSer-mediated engulfment of apoptotic cells by macrophages. MerTK−/− and Axl−/− double deficiency fully rescued the lymphopenia in the ATP11C−/y bone marrow. Many of the rescued ATP11C−/y pre-B and immature B cells exposed PtdSer, and these cells were engulfed alive by wild-type peritoneal macrophages, in a PtdSer-dependent manner. These results indicate that ATP11A and ATP11C in precursor B cells are essential for rapidly internalizing PtdSer from the cell surface to prevent the cells’ engulfment by macrophages.

scholarly journals Active elimination of intestinal cells drives oncogenic growth in organoids

2020 ◽  
Author(s):  
Ana Krotenberg Garcia ◽  
Arianna Fumagalli ◽  
Huy Quang Le ◽  
Owen J. Sansom ◽  
Jacco van Rheenen ◽  
...  
Keyword(s):  
Quality Control ◽  
Cell Death ◽  
Cancer Cells ◽  
Cell Fate ◽  
Crucial Role ◽  
Intestinal Cells ◽  
Dependent Manner ◽  
Wild Type ◽  
Cell Competition ◽  
Type Population

AbstractCompetitive cell-interactions play a crucial role in quality control during development and homeostasis. Here we show that cancer cells use such interactions to actively eliminate wild-type intestine cells in enteroid monolayers and organoids. This apoptosis-dependent process boosts proliferation of intestinal cancer cells. The remaining wild-type population activates markers of primitive epithelia and transits to a fetal-like state. Prevention of this cell fate transition avoids elimination of wild-type cells and, importantly, limits the proliferation of cancer cells. JNK signalling is activated in competing cells and is required for cell fate change and elimination of wild-type cells. Thus, cell competition drives growth of cancer cells by active out-competition of wild-type cells through forced cell death and cell fate change in a JNK dependent manner.

scholarly journals TLR7 modulating B-cell immune responses in the spleen of C57BL/6 mice infected with Schistosoma japonicum

2021 ◽  
Vol 15 (11) ◽  
pp. e0009943
Author(s):  
Haixia Wei ◽  
Hongyan Xie ◽  
Jiale Qu ◽  
Anqi Xie ◽  
Shihao Xie ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Gene Knockout ◽  
Innate Immune ◽  
Wild Type ◽  
Cell Responses ◽  
Splenic Cells ◽  
And Function ◽  
Egg Antigen

B cells played an important role in Schistosoma infection-induced diseases. TLR7 is an intracellular member of the innate immune receptor. The role of TLR7 on B cells mediated immune response is still unclear. Here, C57BL/6 mice were percutaneously infected by S. japonicum for 5–6 weeks. The percentages and numbers of B cells increased in the infected mice (p < 0.05), and many activation and function associated molecules were also changed on B cells. More splenic cells of the infected mice expressed TLR7, and B cells were served as the main cell population. Moreover, a lower level of soluble egg antigen (SEA) specific antibody and less activation associated molecules were found on the surface of splenic B cells from S. japonicum infected TLR7 gene knockout (TLR7 KO) mice compared to infected wild type (WT) mice (p < 0.05). Additionally, SEA showed a little higher ability in inducing the activation of B cells from naive WT mice than TLR7 KO mice (p < 0.05). Finally, the effects of TLR7 on B cells are dependent on the activation of NF-κB p65. Altogether, TLR7 was found modulating the splenic B cell responses in S. japonicum infected C57BL/6 mice.

scholarly journals Regulatory B cells (Bregs) inhibit osteoclastogenesis and prevent bone loss in osteoporotic mice model

2021 ◽  
Author(s):  
Leena Sapra ◽  
Asha Bhardwaj ◽  
Pradyumna K. Mishra ◽  
Bhupendra K. Verma ◽  
Rupesh K. Srivastava
Keyword(s):  
B Cells ◽  
Bone Marrow Cells ◽  
Dependent Manner ◽  
Regulatory B Cells ◽  
Mice Model ◽  
Post Menopausal Osteoporosis ◽  
Post Menopausal ◽  
First Time

AbstractIncreasing evidences in recent years have suggested that regulatory B cells (Bregs) are crucial modulator in various inflammatory disease conditions. However, the role of Bregs in case of postmenopausal osteoporosis remains unknown. Also, no study till date have ever investigated the significance of Bregs in modulating osteoclastogenesis. In the present study, we for the first time examined the anti-osteoclastogenic potential of Bregs under in vitro conditions and we observed that Bregs suppressed RANKL mediated osteoclastogenesis in bone marrow cells in a dose dependent manner. We further elucidated the mechanism behind the suppression of osteoclasts differentiation by Bregs and found that Bregs inhibit osteoclastogenesis via IL-10 production. To further confirm the bone health modulating potential of Bregs we employed post-menopausal osteoporotic mice model. Remarkably, our in vivo data clearly suggest a significant reduction (p < 0.01) in both CD19+IL-10+ and CD19+CD1dhiCD5+IL-10+ B10 Bregs in case of osteoporotic mice model. Moreover, our serum cytokine data further confirms the significant reduction of IL-10 levels in osteoporotic mice. Taken together, the present study for the first time unravels and establish the unexplored role of regulatory B cells in case of osteoporosis and provide new insight into Bregs biology in the context of post-menopausal osteoporosis.

Role of common cytokine receptor γ chain (γc)– and Jak3-dependent signaling in the proliferation and survival of murine mast cells

Blood ◽  
2000 ◽  
Vol 96 (6) ◽  
pp. 2172-2180 ◽  
Author(s):  
Kotaro Suzuki ◽  
Hiroshi Nakajima ◽  
Norihiko Watanabe ◽  
Shin-ichiro Kagami ◽  
Akira Suto ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mast Cells ◽  
Cytokine Receptor ◽  
Type I ◽  
Dependent Manner ◽  
Type Ii ◽  
Wild Type ◽  
Peritoneal Mast Cells ◽  
The Common

Abstract The regulatory roles of the common cytokine receptor γ chain (γc)– and Jak3-dependent signaling in the proliferation and survival of mast cells were determined using γc-deficient (γc−) and Jak3-deficient (Jak3−) mice. Although the mast cells in γc− and Jak3− mice were morphologically indistinguishable from those in wild-type mice, the number of peritoneal mast cells was decreased in γc− and Jak3− mice as compared with that in wild-type mice. Among γc-related cytokines, interleukin (IL)-4 and IL-9, but not IL-2, IL-7, or IL-15, enhanced the proliferation and survival of bone marrow–derived mast cells (BMMCs) from wild-type mice. However, the effects of IL-4 and IL-9 were absent in BMMCs from γc− and Jak3−mice. In addition, IL-4Rα, γc, and Jak3, but not IL-2Rβ or IL-7Rα, were expressed in BMMCs. In contrast, IL-13 did not significantly induce the proliferation and survival of BMMCs even from wild-type mice, and IL-13Rα1 was not expressed in BMMCs. Furthermore, IL-4 phosphorylated the 65-kd isoform of Stat6 in BMMCs from wild-type mice but not from γc− and Jak3− mice. These results indicate that γc- and Jak3-dependent signaling is essential for IL-4– and IL-9–induced proliferation and survival of murine mast cells, that the effects of IL-4 are mediated by type I IL-4R and that type II IL-4R is absent on mast cells, and that IL-4 phosphorylates the 65-kd isoform of Stat6 in mast cells in a γc- and Jak3-dependent manner.

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