Abstract 2: Loss of Rictor in Macrophages Suppresses Their Viability and Reduces Atherosclerosis in LDLR Null Mice

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Vladimir R Babaev ◽  
Lei Ding ◽  
Youmin Zhang ◽  
James M May ◽  
MacRae F Linton

The mammalian target of rapamycin (mTOR) is a conserved serine/threonine kinase that plays a central role in the regulation of cell viability, growth and metabolism. mTOR complex 2 (mTORC2) directly activates phosphorylation of Akt at S 473 , promoting pro-survival signaling. Rictor is an essential component of mTORC2, and genetic loss of Rictor inactivates the complex. To examine whether macrophage mTORC2 signaling has an impact on atherosclerosis, we transplanted male Ldlr null mice with bone marrow isolated from male mice with myeloid-specific Rictor deletion ( Rictor -/- , n=9) and control marrow from Rictor flox-flox mice ( Rictor flox/flox ; n=10). Compared to control mice reconstituted with Rictor flox/flox cells, the recipients of Rictor -/- bone marrow cells exhibited dramatic changes in blood cells including lower levels of white blood cells, B-cells, T-cells and monocytes but had similar levels of neutrophils. After 8 weeks of the Western diet, both groups of recipients had similar levels of body weight, blood glucose, plasma total cholesterol and triglycerides. However, Rictor -/- → Ldlr -/- mice developed smaller atherosclerotic lesions in the proximal and distal aorta (46 and 40% reduction, respectively). These lesions contained less macrophage area and more apoptotic macrophages than lesions of control Rictor flox/flox → Ldlr -/- mice. Importantly, blood monocytes and peritoneal macrophages isolated from Rictor -/- → Ldlr -/- mice were more sensitive to apoptotic stimuli compared to control Rictor flox/flox cells. In response to LPS, Rictor -/- macrophages exhibited the M1 phenotype with high levels of pro-inflammatory gene expression. Both Rictor -/- blood monocytes and macrophages had lower levels of Il10 gene expression than Rictor flox/flox cells. Thus, loss of Rictor and, consequently, mTORC2 in monocyte/macrophages significantly compromises their survival, and this markedly diminishes early atherosclerosis in Ldlr -/- mice. Our results indicate that mTORC2 is a key signaling regulator of macrophage survival and inflammatory responses and promote atherosclerosis.

Blood ◽  
1997 ◽  
Vol 90 (6) ◽  
pp. 2148-2159 ◽  
Author(s):  
Harshal H. Nandurkar ◽  
Lorraine Robb ◽  
David Tarlinton ◽  
Louise Barnett ◽  
Frank Köntgen ◽  
...  

Abstract Interleukin-11 (IL-11) is a pleiotropic growth factor with a prominent effect on megakaryopoiesis and thrombopoiesis. The receptor for IL-11 is a heterodimer of the signal transduction unit gp130 and a specific receptor component, the α-chain (IL-11Rα). Two genes potentially encode the IL-11Rα: the IL11Ra and IL11Ra2 genes. The IL11Ra gene is widely expressed in hematopoietic and other organs, whereas the IL11Ra2 gene is restricted to only some strains of mice and its expression is confined to testis, lymph node, and thymus. To investigate the essential actions mediated by the IL-11Rα, we have generated mice with a null mutation of IL11Ra (IL11Ra−/−) by gene targeting. Analysis of IL11Ra expression by Northern blot and reverse transcriptase-polymerase chain reaction, as well as the absence of response of IL11Ra−/− bone marrow cells to IL-11 in hematopoietic assays, further confirmed the null mutation. Compensatory expression of the IL11Ra2 in bone marrow cells was not detected. IL11Ra−/− mice were healthy with normal numbers of peripheral blood white blood cells, hematocrit, and platelets. Bone marrow and spleen contained normal numbers of cells of all hematopoietic lineages, including megakaryocytes. Clonal cultures did not identify any perturbation of granulocyte-macrophage (GM), erythroid, or megakaryocyte progenitors. The number of day-12 colony-forming unit-spleen progenitors were similar in wild-type and IL11Ra−/− mice. The kinetics of recovery of peripheral blood white blood cells, platelets, and bone marrow GM progenitors after treatment with 5-flurouracil were the same in IL11Ra−/− and wild-type mice. Acute hemolytic stress was induced by phenylhydrazine and resulted in a 50% decrease in hematocrit. The recovery of hematocrit was comparable in IL11Ra−/− and wild-type mice. These observations indicate that IL-11 receptor signalling is dispensable for adult hematopoiesis.


Blood ◽  
2003 ◽  
Vol 101 (8) ◽  
pp. 2990-2995 ◽  
Author(s):  
Tetsuo Mitsui ◽  
Sumiko Watanabe ◽  
Yoshihiro Taniguchi ◽  
Sachiyo Hanada ◽  
Yasuhiro Ebihara ◽  
...  

Abstract Severe congenital neutropenia (SCN) is a hematopoietic disorder characterized by neutropenia in peripheral blood and maturation arrest of neutrophil precursors in bone marrow. Patients with SCN may evolve to have myelodysplastic syndrome or acute myelocytic leukemia. In approximately 20% of SCN cases, a truncation mutation is found in the cytoplasmic region of the granulocyte colony-stimulating factor receptor (G-CSFR). We then generated mice carrying murine wild-type G-CSFR and its mutants equivalent to truncations at amino acids 718 and 731 in human G-CSFR, those were reported to be related to leukemic transformation of SCN. Although numbers of peripheral white blood cells, red blood cells, and platelets did not differ among mutant and wild-type G-CSFR transgenic (Tg) mice, both of the mutant receptor Tg mice had one third of peripheral neutrophil cell counts compared with wild-type receptor Tg mice. The mutant receptor Tg mice also showed impaired resistance to the infection with Staphylococcus aureus. Moreover, bone marrow of these Tg mice had an increased percentage of immature myeloid cells, a feature of SCN. This maturation arrest was also observed in in vitro cultures of bone marrow cells of truncated G-CSFR Tg mice under G-CSF stimulation. In addition, clonal culture of bone marrow cells of the truncated G-CSFR Tg mice showed the hypersensitivity to G-CSF in myeloid progenitors. Our Tg mice may be useful in the analysis of the role of truncated G-CSFR in SCN pathobiology.


Blood ◽  
1997 ◽  
Vol 90 (6) ◽  
pp. 2148-2159 ◽  
Author(s):  
Harshal H. Nandurkar ◽  
Lorraine Robb ◽  
David Tarlinton ◽  
Louise Barnett ◽  
Frank Köntgen ◽  
...  

Interleukin-11 (IL-11) is a pleiotropic growth factor with a prominent effect on megakaryopoiesis and thrombopoiesis. The receptor for IL-11 is a heterodimer of the signal transduction unit gp130 and a specific receptor component, the α-chain (IL-11Rα). Two genes potentially encode the IL-11Rα: the IL11Ra and IL11Ra2 genes. The IL11Ra gene is widely expressed in hematopoietic and other organs, whereas the IL11Ra2 gene is restricted to only some strains of mice and its expression is confined to testis, lymph node, and thymus. To investigate the essential actions mediated by the IL-11Rα, we have generated mice with a null mutation of IL11Ra (IL11Ra−/−) by gene targeting. Analysis of IL11Ra expression by Northern blot and reverse transcriptase-polymerase chain reaction, as well as the absence of response of IL11Ra−/− bone marrow cells to IL-11 in hematopoietic assays, further confirmed the null mutation. Compensatory expression of the IL11Ra2 in bone marrow cells was not detected. IL11Ra−/− mice were healthy with normal numbers of peripheral blood white blood cells, hematocrit, and platelets. Bone marrow and spleen contained normal numbers of cells of all hematopoietic lineages, including megakaryocytes. Clonal cultures did not identify any perturbation of granulocyte-macrophage (GM), erythroid, or megakaryocyte progenitors. The number of day-12 colony-forming unit-spleen progenitors were similar in wild-type and IL11Ra−/− mice. The kinetics of recovery of peripheral blood white blood cells, platelets, and bone marrow GM progenitors after treatment with 5-flurouracil were the same in IL11Ra−/− and wild-type mice. Acute hemolytic stress was induced by phenylhydrazine and resulted in a 50% decrease in hematocrit. The recovery of hematocrit was comparable in IL11Ra−/− and wild-type mice. These observations indicate that IL-11 receptor signalling is dispensable for adult hematopoiesis.


1980 ◽  
Vol 29 (2) ◽  
pp. 520-525
Author(s):  
P A LeBlanc ◽  
H R Katz ◽  
S W Russell

Rat monoclonal antibody raised against cultured mouse bone marrow was used to detect an antigenic determinant on a discrete population of mouse mononuclear phagocytes by indirect immunofluorescence. The antigen was expressed on adherent, late-cultured bone marrow macrophages and chronic inflammatory peritoneal macrophages elicited by the injection of thioglycolate broth. Binding of the antibody to resident peritoneal or alveolar macrophages, blood monocytes, or freshly explanted bone marrow cells was not detected. Less than 10% of acute inflammatory mononuclear phagocytes expressed the antigen. The antibody did not bind detectably to lymphocytes, granulocytes, erythrocytes, fibroblasts, or the cells of several murine tumor lines. Results suggesting binding to mast cells were equivocal. The antigen was species, but not strain, specific. It was concluded that maturation, at least, was required for expression of the antigen. Results suggested that additional influences were also involved.


2012 ◽  
Author(s):  
Erin Sandford ◽  
Megan Orr ◽  
Xianyao Li ◽  
Huaijun Zhou ◽  
timothy J. Johnson ◽  
...  

2019 ◽  
Vol 18 (14) ◽  
pp. 1936-1951 ◽  
Author(s):  
Raghav Dogra ◽  
Rohit Bhatia ◽  
Ravi Shankar ◽  
Parveen Bansal ◽  
Ravindra K. Rawal

Background: Acute myeloid leukemia is the collective name for different types of leukemias of myeloid origin affecting blood and bone marrow. The overproduction of immature myeloblasts (white blood cells) is the characteristic feature of AML, thus flooding the bone marrow and reducing its capacity to produce normal blood cells. USFDA on August 1, 2017, approved a drug named Enasidenib formerly known as AG-221 which is being marketed under the name Idhifa to treat R/R AML with IDH2 mutation. The present review depicts the broad profile of enasidenib including various aspects of chemistry, preclinical, clinical studies, pharmacokinetics, mode of action and toxicity studies. Methods: Various reports and research articles have been referred to summarize different aspects related to chemistry and pharmacokinetics of enasidenib. Clinical data was collected from various recently published clinical reports including clinical trial outcomes. Result: The various findings of enasidenib revealed that it has been designed to allosterically inhibit mutated IDH2 to treat R/R AML patients. It has also presented good safety and efficacy profile along with 9.3 months overall survival rates of patients in which disease has relapsed. The drug is still under study either in combination or solely to treat hematological malignancies. Molecular modeling studies revealed that enasidenib binds to its target through hydrophobic interaction and hydrogen bonding inside the binding pocket. Enasidenib is found to be associated with certain adverse effects like elevated bilirubin level, diarrhea, differentiation syndrome, decreased potassium and calcium levels, etc. Conclusion: Enasidenib or AG-221was introduced by FDA as an anticancer agent which was developed as a first in class, a selective allosteric inhibitor of the tumor target i.e. IDH2 for Relapsed or Refractory AML. Phase 1/2 clinical trial of Enasidenib resulted in the overall survival rate of 40.3% with CR of 19.3%. Phase III trial on the Enasidenib is still under process along with another trial to test its potency against other cell lines. Edasidenib is associated with certain adverse effects, which can be reduced by investigators by designing its newer derivatives on the basis of SAR studies. Hence, it may come in the light as a potent lead entity for anticancer treatment in the coming years.


2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Shuxia Wang ◽  
Shuhang Xu ◽  
Jing Zhou ◽  
Li Zhang ◽  
Xiaodong Mao ◽  
...  

Abstract Background Macrophages are indispensable regulators of inflammatory responses. Macrophage polarisation and their secreted inflammatory factors have an association with the outcome of inflammation. Luteolin, a flavonoid abundant in plants, has anti-inflammatory activity, but whether luteolin can manipulate M1/M2 polarisation of bone marrow-derived macrophages (BMDMs) to suppress inflammation is still unclear. This study aimed to observe the effects of luteolin on the polarity of BMDMs derived from C57BL/6 mice and the expression of inflammatory factors, to explore the mechanism by which luteolin regulates the BMDM polarity. Methods M1-polarised BMDMs were induced by lipopolysaccharide (LPS) + interferon (IFN)-γ and M2-polarisation were stimulated with interleukin (IL)-4. BMDM morphology and phagocytosis were observed by laser confocal microscopy; levels of BMDM differentiation and cluster of differentiation (CD)11c or CD206 on the membrane surface were assessed by flow cytometry (FCM); mRNA and protein levels of M1/M2-type inflammatory factors were performed by qPCR and ELISA, respectively; and the expression of p-STAT1 and p-STAT6 protein pathways was detected by Western-blotting. Results The isolated mouse bone marrow cells were successfully differentiated into BMDMs, LPS + IFN-γ induced BMDM M1-phenotype polarisation, and IL-4 induced M2-phenotype polarisation. After M1-polarised BMDMs were treated with luteolin, the phagocytosis of M1-polarized BMDMs was reduced, and the M1-type pro-inflammatory factors including IL-6, tumour necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS), and CD86 were downregulated while the M2-type anti-inflammatory factors including IL-10, IL-13, found in inflammatory zone (FIZZ)1, Arginase (Arg)1 and CD206 were upregulated. Additionally, the expression of M1-type surface marker CD11c decreased. Nevertheless, the M2-type marker CD206 increased; and the levels of inflammatory signalling proteins phosphorylated signal transducer and activator of transcription (p-STAT)1 and p-STAT6 were attenuated and enhanced, respectively. Conclusions Our study suggests that luteolin may transform BMDM polarity through p-STAT1/6 to regulate the expression of inflammatory mediators, thereby inhibiting inflammation. Naturally occurring luteolin holds promise as an anti-inflammatory and immunomodulatory agent.


1969 ◽  
Vol 129 (4) ◽  
pp. 757-774 ◽  
Author(s):  
Nabih I. Abdou ◽  
Maxwell Richter

Irradiated rabbits given allogeneic bone marrow cells from normal adult donors responded to an injection of sheep red blood cells by forming circulating antibodies. Their spleen cells were also capable of forming many plaques using the hemolysis in gel technique, and were also capable of undergoing blastogenesis and mitosis and of incorporating tritiated thymidine upon exposure to the specific antigen in vitro. However, irradiated rabbits injected with allogeneic bone marrow obtained from rabbits injected with sheep red blood cells 24 hr prior to sacrifice (primed donors) were incapable of mounting an immune response after stimulation with sheep red cells. This loss of reactivity by the bone marrow from primed donors is specific for the antigen injected, since the immune response of the irradiated recipients to a non-cross-reacting antigen, the horse red blood cell, is unimpaired. Treatment of the bone marrow donors with high-titered specific antiserum to sheep red cells for 24 hr prior to sacrifice did not result in any diminished ability of their bone marrow cells to transfer antibody-forming capacity to sheep red blood cells. The significance of these results, with respect to the origin of the antigen-reactive and antibody-forming cells in the rabbit, is discussed.


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