Critical role for bone marrow stromal antigen 2 in acute Chikungunya virus infection

Bone marrow stromal antigen 2 (BST-2; also known as tetherin or CD317) is an IFN-inducible gene that functions to block the release of a range of nascent enveloped virions from infected host cells. However, the role of BST-2 in viral pathogenesis remains poorly understood. BST-2 plays a multifaceted role in innate immunity, as it hinders retroviral infection and possibly promotes infection with some rhabdo- and orthomyxoviruses. This paradoxical role has probably hindered exploration of BST-2 antiviral function in vivo. We reported previously that BST-2 tethers Chikungunya virus (CHIKV)-like particles on the cell plasma membrane. To explore the role of BST-2 in CHIKV replication and host protection, we utilized CHIKV strain 181/25 to examine early events during CHIKV infection in a BST-2−/− mouse model. We observed an interesting dichotomy between WT and BST-2−/− mice. BST-2 deficiency increased inoculation site viral load, culminating in higher systemic viraemia and increased lymphoid tissues tropism. A suppressed inflammatory innate response demonstrated by impaired expression of IFN-α, IFN-γ and CD40 ligand was observed in BST-2−/− mice compared with the WT controls. These findings suggested that, in part, BST-2 protects lymphoid tissues from CHIKV infection and regulates CHIKV-induced inflammatory response by the host.

Download Full-text

Allogeneic Environment and Tissue Damage Provide Critical Stimuli for Regulatory T Cell Expansion and Survival In Vivo after Hematopoietic Cell Transplantation.

Blood ◽

10.1182/blood.v108.11.1731.1731 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1731-1731

Author(s):

Vu H. Nguyen ◽

Daisy Chang ◽

Robert S. Negrin

Keyword(s):

Bone Marrow ◽

T Cells ◽

Tissue Damage ◽

Hematopoietic Cell Transplantation ◽

Critical Role ◽

Lymphoid Organs ◽

Gamma Chain ◽

Secondary Lymphoid Organs

Abstract CD4+CD25+ regulatory T cells (Treg) mediate alloresponses in murine models of bone marrow transplantation (BMT), leading to protection from graft-versus-host disease (GvHD). However, in vivo migration and tissue localization of Treg during this inflammatory response remain unclear. We previously demonstrated co-localization of Treg with effector T cells (Tcon) with initial expansion in secondary lymphoid organs prior to migration into inflamed tissues in a major MHC-mismatched BMT model. To explore the stimuli for Treg proliferation, we evaluated the role of the allogeneic environment by transferring FVB donor luciferase-expressing (luc+) Treg into lethally-irradiated syngeneic recipients. Unlike the allogeneic irradiated setting where Treg expand in the presence or absence of Tcon, adoptively transferred luc+ Treg were not detected in secondary lymphoid organs of syngeneic lethally-irradiated BMT recipients by in vivo bioluminescence imaging (BLI). Syngeneic luc+ Tcon also had significantly different in vivo dynamics, with a 4 day delay and only moderate expansion in lymph nodes. Proliferation was not detected in the spleen, unlike their allogeneic Tcon counterparts, nor in the bone marrow compartments, as seen in lymphopenic models. To assess whether irradiation induced the observed in vivo dynamics of Treg in the allogeneic setting, we transferred FVB luc+ Treg or luc+ Tcon into unirradiated Balb/c Rag2−/−gamma chain (γC) −/− recipients, which lack T, B, and NK cells. After adoptive transfer into Rag2−/−γC−/− recipients, robust Tcon proliferation was observed in secondary lymphoid organs and the bone marrow compartments; however, Treg expansion was weak, and specific localization to lymphoid or nonlymphoid tissues was not observed. Treg were stimulated to localize to and expand in secondary lymphoid organs by the co-transfer of Tcon in unirradiated Rag2−/− (γC) −/− or by conditioning Rag2−/− (γC) −/− recipients with irradiation. Exogenous IL2 administration two weeks following luc+ Treg transfer into unirradiated Rag2−/− (γC) −/− recipients similarly led to localization and expansion of Treg in secondary lymphoid organs. These studies indicate the critical role of proinflammatory cytokines, such as IL2, generated either by irradiation-induced tissue damage or donor Tcon, in the expansion and localization of Treg. Differences between Tcon and Treg expansion in syngeneic or unconditioned allogeneic Rag2−/− γC−/− hosts suggest an important role of conditioning with irradiation alone or in concert with the allogeneic environment, in providing distinct signals for Tcon versus Treg activation, proliferation, and localization.

Download Full-text

G-CSF Mediated Decrease in Bone-Marrow SDF-1 Level Is Neutrophil Dependent but CD26 Independent

Blood ◽

10.1182/blood.v112.11.3469.3469 ◽

2008 ◽

Vol 112 (11) ◽

pp. 3469-3469

Author(s):

Pratibha Singh ◽

Seiji Fukuda ◽

Janardhan Sampath ◽

Louis M. Pelus

Keyword(s):

Bone Marrow ◽

Magnetic Beads ◽

Critical Role ◽

Alternative Mechanism ◽

Wild Type ◽

Hematopoietic Stem ◽

Osteoblast Activity

Abstract Interaction of CXCR4 expressed on hematopoietic stem and progenitor cells (HSPC) with bone-marrow stromal SDF-1 is believed to play a central role in retention or mobilization of HSPC. Recently, a mobilization regimen of G-CSF was shown to decrease osteoblast number resulting in reduced levels of bone-marrow SDF-1, however the detailed mechanism leading to this reduction is currently unknown. It is unlikely that G-CSF directly regulates osteoblast SDF-1 production since osteoblasts do not express G-CSF receptor. Proteolytic cleavage of SDF-1 by peptidase CD26 in the bone-marrow may be an alternative mechanism responsible for reduction of SDF-1 level. Although CD26 can cleave SDF-1 in vitro, direct evidence of SDF-1 cleavage by CD26 in vivo during G-CSF induced HSPC mobilization has not been demonstrated. We previously demonstrated that neutrophils are required for G-CSF induced HSPC mobilization and that CD26 expression on neutrophils, rather than HSPC, is critical for mobilization. To more fully understand the role of CD26 in altering SDF-1 protein/activity during G-CSF induced HSPC mobilization, we quantitated bone-marrow SDF-1 levels in CD26−/− and wild-type CD26+/+ mice by ELISA during G-CSF administration. A standard 4 day G-CSF mobilization regimen (100 μg/kg bid, sc × 4 days) decreased bone-marrow total SDF-1 from 4.55±0.3 to 0.52±0.06 ng/femur in wild-type CD26+/+ mice (8.7-fold) and from 4.51±0.3 to 0.53±0.05 ng/femur (8.5-fold) in CD26−/− mice. However, despite an equivalent decrease in SDF-1, total CFU mobilization and the absolute number of mobilized SKL cells were decreased (3.1 and 2.0 fold lower, respectively) in CD26−/− mice compared to wild-type CD26+/+ controls. These results suggest that the decrease in total SDF-1 level in marrow seen following G-CSF treatment is independent of CD26. Cytological examination of bone-marrow smears showed that the reduction in SDF-1 levels in bone-marrow of both wild-type CD26+/+ and CD26−/− mice following G-CSF administration correlated with an increase in total absolute bone-marrow neutrophil cell number, suggesting a role for neutrophils in modulation of SDF-1 protein. To determine if neutrophils affect osteoblast SDF-1 production, bone marrow Gr-1+ neutrophils from wild-type CD26+/+ and CD26−/− mice were purified using anti-Ly6G magnetic beads and co-cultured with MC3T3-E1 preosteoblasts in vitro. Gr-1+ neutrophils from both wild-type and CD26−/− mice decreased pre-osteoblast SDF-1 production by similar amounts (15.4-fold vs 14.8-fold respectively), while Gr-1 neg cells from both wild-type CD26+/+ or CD26−/− were without effect on SDF-1 levels. Similarly, Gr-1+ neutrophils from both wild-type and CD26−/− mice decreased SDF-1 produced by MC3T3-E1-derived osteoblasts from 1.85±0.3 to 0.52±0.06 ng/ml (3.5 fold) and 0.56±0.07 ng/ml (3.3 fold) respectively, with Gr-1neg cells having no effect. Gr-1+ neutrophils either from wild-type or CD26−/− mice, but not Gr-1neg cells, significantly induced apoptosis of MC3T3-E1 cells as measured by Annexin-V staining (70.5%±10.2 vs 71.2%±12.5 for wild-type CD26+/+ and CD26−/− neutrophils respectively) and significantly inhibited osteoblast activity (20-fold vs 20.6-fold for CD26+/+ and CD26−/− neutrophils respectively) as measured by osteocalcin expression. Furthermore, irrespective of G-CSF treatment, an inverse correlation between absolute neutrophil number and SDF-1 protein levels was observed, suggesting that G-CSF induces neutrophil expansion but does not directly affect SDF-1 production. Collectively, these results provide additional support for the critical role of neutrophils in G-CSF induced mobilization and strongly suggested that neutrophils directly regulate bone-marrow SDF-1 levels independent of CD26 activity.

Download Full-text

The role of Leishmania GP63 in the modulation of innate inflammatory response to Leishmania major infection

PLoS ONE ◽

10.1371/journal.pone.0262158 ◽

2021 ◽

Vol 16 (12) ◽

pp. e0262158

Author(s):

Aretha Chan ◽

Jose-Mauricio Ayala ◽

Fernando Alvarez ◽

Ciriaco Piccirillo ◽

George Dong ◽

...

Keyword(s):

Inflammatory Response ◽

Leishmania Major ◽

Critical Role ◽

Protozoan Parasite ◽

Inflammatory Cells ◽

Host Cells ◽

Cell Infection ◽

Zinc Metalloprotease

Leishmaniasis is a disease caused by the protozoan parasite Leishmania and is known to affect millions of individuals worldwide. In recent years, we have established the critical role played by Leishmania zinc-metalloprotease GP63 in the modulation of host macrophage signalling and functions, favouring its survival and progression within its host. Leishmania major lacking GP63 was reported to cause limited infection in mice, however, it is still unclear how GP63 may influence the innate inflammatory response and parasite survival in an in vivo context. Therefore, we were interested in analyzing the early innate inflammatory events upon Leishmania inoculation within mice and establish whether Leishmania GP63 influences this initial inflammatory response. Experimentally, L. major WT (L. majorWT), L. major GP63 knockout (L. majorKO), or L. major GP63 rescue (L. majorR) were intraperitoneally inoculated in mice and the inflammatory cells recruited were characterized microscopically and by flow cytometry (number and cell type), and their infection determined. Pro-inflammatory markers such as cytokines, chemokines, and extracellular vesicles (EVs, e.g. exosomes) were monitored and proteomic analysis was performed on exosome contents. Data obtained from this study suggest that Leishmania GP63 does not significantly influence the pathogen-induced inflammatory cell recruitment, but rather their activation status and effector function. Concordantly, internalization of promastigotes during early infection could be influenced by GP63 as fewer L. majorKO amastigotes were found within host cells and appear to maintain in host cells over time. Collectively this study provides a clear analysis of innate inflammatory events occurring during L. major infection and further establish the prominent role of the virulence factor GP63 to provide favourable conditions for host cell infection.

Download Full-text

The Coxiella burnetii QpH1 plasmid is a virulence factor for colonizing bone marrow-derived murine macrophages

10.1101/2020.03.22.001875 ◽

2020 ◽

Author(s):

Shengdong Luo ◽

Zhihui Sun ◽

Huahao Fan ◽

Shanshan Lu ◽

Yan Hu ◽

...

Keyword(s):

Bone Marrow ◽

Coxiella Burnetii ◽

Virulence Factor ◽

Critical Role ◽

Murine Macrophages ◽

Infection Models

AbstractCoxiella burnetii carries a large conserved plasmid or plasmid-like chromosomally integrated sequence of unknown function. Here we report the curing of QpH1 plasmid from C. burnetii Nine Mile phase II, the characterization of QpH1-deficient C. burnetii in in vitro and in vivo infection models, and the characterization of plasmid biology. A shuttle vector pQGK, which is composed of the CBUA0036-0039a region (predicted for QpH1 maintenance), an E. coli plasmid ori, eGFP and kanamycin resistance genes was constructed. The pQGK vector can be stably transformed into Nine Mile II and maintained at a similar low copy like QpH1. Importantly, transformation with pQGK cured the endogenous QpH1 due to plasmid incompatibility. Compared to a Nine Mile II transformant of a RSF1010-based vector, the pQGK transformant shows an identical one-step growth curve in axenic media, a similar growth curve in Buffalo green monkey kidney cells, an evident growth defect in macrophage-like THP-1 cells, and dramatically reduced ability of colonizing bone marrow-derived murine macrophages. In the SCID mouse infection model, the pQGK transformants caused a lesser extent of splenomegaly. Moreover, the plasmid biology was investigated by mutagenesis. We found CBUA0037-0039 are essential for plasmid maintenance, and CBUA0037-0038 account for plasmid compatibility. Taken together, our data suggest that QpH1 encodes factor(s) essential for colonizing murine macrophages, and to a lesser extent for colonizing human macrophages. This study highlights a critical role of QpH1 for C. burnetii persistence in rodents, and expands the toolkit for genetic studies in C. burnetii.Author summaryIt is postulated that C. burnetii recently evolved from an inherited symbiont of ticks by the acquisition of novel virulence factors. All C. burnetii isolates carry a large plasmid or have a chromosomally integrated plasmid-like sequence. The plasmid is a candidate virulence factor that contributes to C. burnetii evolution. Here we describe the construction of novel shuttle vectors that allow to make plasmid-deficient C. burnetii mutants. With this plasmid-curing approach, we characterized the role of the QpH1 plasmid in in vitro and in vivo C. burnetii infection models. We found that the plasmid plays a critical role for C. burnetii growth in macrophages, especially in murine macrophages, but not in axenic media and BGMK cells. Our work highlights an essential role of the plasmid for the acquisition of colonizing capability in rodents by C. burnetii. This study represents a major step toward unravelling the mystery of the C. burnetii cryptic plasmids.

Download Full-text

Critical Role of Hem1 in Hematopoietic Cell Chemotaxis and Innate Immunity to S. Pneumoniae

Blood ◽

10.1182/blood.v108.11.1630.1630 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1630-1630

Author(s):

Robert B. Lorsbach ◽

Yoon-Sang Kim ◽

Jennifer Moore ◽

Hope Smith-Sielicki ◽

Tiffany M. Jones ◽

...

Keyword(s):

Bone Marrow ◽

Innate Immunity ◽

Stem Cell ◽

Peripheral Blood ◽

Critical Role ◽

Hematopoietic Cell ◽

Wild Type ◽

Regulatory Complex

Abstract Hem1 is a hematopoietic specific member of the HEM family proteins, which have been identified as components of the WAVE regulatory complex. To further characterize the role of Hem1 in hematopoietic cell function, we have generated mice deficient in Hem1 using gene targeting methodology. Hem1-deficient mice manifest several phenotypic abnormalities, including peripheral blood lymphopenia and neutrophilia, splenomegaly, premature mortality, and with variable penetrance thymic hypoplasia and alopecia. Flow cytometric analysis of peripheral blood and spleen demonstrated that Hem1−/ − mice have a marked reduction in peripheral B cells, changes that were evident in both adult and neonatal mice; the splenomegaly in Hem1−/ − mice was attributable to increased extramedullary hematopoiesis. The frequency of bone marrow B cell progenitors was also markedly reduced in Hem1−/ − mice. To assess the role of Hem1 in hematopoietic stem cell (HSC) function, competitive bone marrow transplantation assays were performed. In contrast to wild-type HSCs, Hem1-deficient HSCs had poor competitive repopulating activity in irradiated recipient mice. KSL cell analysis demonstrated no significant difference in the frequency of lin-c-kit+Sca1+ HSCs between wild-type and Hem1−/ − bone marrow, suggesting that the defective competitive repopulating activity of Hem1−/ − HSCs is attributable to defective bone marrow homing or stem cell niche interaction. Given the biochemical evidence implicating the HEM proteins as a component of the WAVE regulatory complex, we also assessed the ability of Hem1-deficient leukocytes to undergo cytoskeletal remodeling in vitro. Using a transwell assay, Hem1−/ − bone marrow storage pool neutrophils demonstrated markedly blunted chemotactic responses to formylated peptide which was attributable to defective f-actin formation. Hem1−/ − peripheral CD4+ T cells similarly manifested chemotactic defects in response to SDF-1, and showed blunted proliferation when stimulated with antibodies against CD3 and CD28. Finally, a model of Streptococcus pneumoniae infection was employed to test the role of Hem1 in the in vivo function of neutrophils. Hem1−/ − mice were dramatically more sensitive to S. pneumoniae than wild-type littermates, as manifested by the inability to eliminate S. pneumoniae organisms in vivo and higher mortality. In summary, Hem1 deficiency results in deficiencies and functional defects in multiple hematopoietic lineages due to defective signaling to the actin cytoskeleton, and importantly, Hem1 plays a critical role in innate immunity to S. pneumoniae in vivo.

Download Full-text

Distinct Role of Antigen-Specific Tc1 and Tc17 Cells in Tumor Eradication In Vivo

Blood ◽

10.1182/blood.v118.21.1910.1910 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1910-1910

Author(s):

Yu Yu ◽

Hyun Il Cho ◽

Dapeng Wang ◽

Kane Kaosaard ◽

Claudio Anasetti ◽

...

Keyword(s):

Bone Marrow ◽

Tumor Growth ◽

Tumor Immunity ◽

Conflicts Of Interest ◽

B16 Melanoma ◽

Host Cells ◽

Tumor Bearing ◽

Tc17 Cells

Abstract Abstract 1910 Background: Adoptive cell transfer (ACT) of tumor-reactive T cells is one of the most promising approaches for the treatment of established melanoma. Recently, limited studies provide some evidence that Th/Tc17 cells may also have potent anti-tumor activities, but the conclusion is far from reach. Methods: Human gp10025-specific Tc1 or Tc17 cells were generated from pmel-1 transgeneic mice and used as cell source for ACT. Luciferase-transduced B16 melanoma was intravenously injected into C57BL/6 mice to establish lung-metastasis. After 7 days, tumor-bearing mice were lethally irradiated and transferred gp-10025 specific Tc1 or Tc17 cells in the combination of syngeneic bone marrow. Survival of those tumor-bearing mice was monitored daily, and tumor growth was monitored weekly using in vivo bioluminescent imaging (BLI). Donor T-cell expansion and cytokine secretion from the spleen and lung of tumor bearing mice were analyzed using flow cytometry and ELISPOT assays. To evaluate the role of IFNγ in anti-tumor immunity, we used a B16 melanoma cell line that was transduced with a plasmid encoding a dominant-negative IFNγ receptor (B16-IFNγRDN), and IFNγR knockout mice as tumor-bearers. Results: As expected, irradiation and transfer of syngeneic bone marrow had little or no effect on established melanoma. Adoptive transfer of tumor-specific Tc17 cells significantly suppressed the tumor growth, whereas Tc1 cells induced long-term regression of established melanoma. After ACT, Tc1 cells maintained their phenotype to produce IFNγ. However, Tc17 cells largely preserved their ability to produce IL-17, but a subset of them secreted IFNγ, indicating the plasticity of Tc17 cells in vivo. Mechanistically, Tc1 cells executed their anti-tumor immunity primarily through the direct effect of IFNγ on melanoma cells because Tc1 cells had essentially no effect on B16-IFNγRDN tumor. However, Tc1 cells had a similar therapeutic effect on IFNγR knockout as wild type mice, indicating that IFNγ signaling in host cells was not critical. In contrast, despite the fact that Tc17 cells also secreted IFNγ, Tc17-mediated anti-tumor immunity was independent of the effect through IFNγ. Ironically, IFNγ was inhibitory to Tc17-mediated anti-tumor activity. Conclusions: Taken together, these studies demonstrate that both Tc1 and Tc17 cells can mediate effective anti-tumor immunity, but Tc1 is superior to Tc17. These findings also demonstrated for the distinct effect mechanisms of antigen-specific Tc1 and Tc17 cells in anti-tumor response, and direct IFNγ signaling on tumor cells is a key effect to eradicate established tumors mediated by Tc1 cells. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

RUNX1 mutations promote leukemogenesis of myeloid malignancies in ASXL1-mutated leukemia

Journal of Hematology & Oncology ◽

10.1186/s13045-019-0789-3 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 4

Author(s):

Rabindranath Bera ◽

Ming-Chun Chiu ◽

Ying-Jung Huang ◽

Tung-Huei Lin ◽

Ming-Chung Kuo ◽

...

Keyword(s):

Gene Expression ◽

Bone Marrow ◽

Bone Marrow Cells ◽

Critical Role ◽

Mouse Bone Marrow ◽

Myeloid Malignancies ◽

Inhibitor Of Dna Binding

Abstract Background Additional sex combs-like 1 (ASXL1) mutations have been described in all forms of myeloid neoplasms including chronic myelomonocytic leukemia (CMML) and associated with inferior outcomes, yet the molecular pathogenesis of ASXL1 mutations (ASXL1-MT) remains poorly understood. Transformation of CMML to secondary AML (sAML) is one of the leading causes of death in CMML patients. Previously, we observed that transcription factor RUNX1 mutations (RUNX1-MT) coexisted with ASXL1-MT in CMML and at myeloid blast phase of chronic myeloid leukemia. The contribution of RUNX1 mutations in the pathogenesis of myeloid transformation in ASXL1-mutated leukemia, however, remains unclear. Methods To evaluate the leukemogenic role of RUNX1-MT in ASXL1-mutated cells, we co-expressed RUNX1-MT (R135T) and ASXL1-MT (R693X) in different cell lines and performed immunoblot, co-immunoprecipitation, gene expression microarray, quantitative RT-PCR, cell proliferation, differentiation, and clonogenic assays for in vitro functional analyses. The in vivo effect was investigated using the C57BL/6 mouse bone marrow transplantation (BMT) model. Results Co-expression of two mutant genes increased myeloid stem cells in animal model, suggesting that cooperation of RUNX1 and ASXL1 mutations played a critical role in leukemia transformation. The expression of RUNX1 mutant in ASXL1-mutated myeloid cells augmented proliferation, blocked differentiation, and increased self-renewal activity. At 9 months post-BMT, mice harboring combined RUNX1 and ASXL1 mutations developed disease characterized by marked splenomegaly, hepatomegaly, and leukocytosis with a shorter latency. Mice transduced with both ASXL1 and RUNX1 mutations enhanced inhibitor of DNA binding 1 (ID1) expression in the spleen, liver, and bone marrow cells. Bone marrow samples from CMML showed that ID1 overexpressed in coexisted mutations of RUNX1 and ASXL1 compared to normal control and either RUNX1-MT or ASXL1-MT samples. Moreover, the RUNX1 mutant protein was more stable than WT and increased HIF1-α and its target ID1 gene expression in ASXL1 mutant cells. Conclusion The present study demonstrated the biological and functional evidence for the critical role of RUNX1-MT in ASXL1-mutated leukemia in the pathogenesis of myeloid malignancies.

Download Full-text

MK2a inhibitor CMPD1 abrogates chikungunya virus infection by modulating actin remodeling pathway

10.1101/2021.05.26.445768 ◽

2021 ◽

Author(s):

Soma Chattopadhyay ◽

Prabhudutta Mamidi ◽

Tapas Kumar Nayak ◽

Abhishek Kumar ◽

Sameer Kumar ◽

...

Keyword(s):

Viral Infection ◽

Gene Silencing ◽

Chikungunya Virus ◽

Late Phase ◽

Health Concern ◽

Chikv Infection ◽

Viral Copy Number

Chikungunya virus (CHIKV) epidemics around the world have created public health concern with the unavailability of effective drugs and vaccines. This emphasizes the need for molecular understanding of host-virus interactions for developing effective targeted antivirals. Microarray analysis was carried out using CHIKV strain (Prototype and Indian) infected Vero cells and two host isozymes, MK2 and MK3 were selected for further analysis. Gene silencing and drug treatment were performed in vitro and in vivo to unravel the role of MK2/MK3 in CHIKV infection. Gene silencing of MK2 and MK3 abrogated around 58% CHIKV progeny release from the host cell and a MK2 activation (a) inhibitor (CMPD1) treatment demonstrated 68% inhibition of viral infection suggesting a major role of MAPKAPKs during the late phase of CHIKV infection in vitro. Further, it was observed that the inhibition in viral infection is primarily due to the abrogation of lamellipodium formation through modulation of factors involved in the actin cytoskeleton remodeling pathway that is responsible for releasing the virus from the infected cells. Moreover, CHIKV-infected C57BL/6 mice demonstrated reduction in the viral copy number, lessened disease score and better survivability after CMPD1 treatment. In addition, reduction in expression of key pro-inflammatory mediators such as CXCL13, RAGE, FGF, MMP9 and increase in HGF (a CHIKV infection recovery marker) was observed indicating the effectiveness of this drug against CHIKV. Additionally, CMPD1 also inhibited HSV1 and SARS CoV2-19 infection in vitro. Taken together it can be proposed that MK2 and MK3 are crucial host factors for CHIKV infection and can be considered as key targets for developing effective anti-CHIKV strategies in future.

Download Full-text

Flt3-Ligand Plays a Critical Role in Development and Function of CD8+/TCR− Facilitating Cells in Bone Marrow,

Blood ◽

10.1182/blood.v118.21.4003.4003 ◽

2011 ◽

Vol 118 (21) ◽

pp. 4003-4003

Author(s):

Yiming Huang ◽

Thomas Miller ◽

Hong Xu ◽

Yujie Wen ◽

Suzanne T Ildstad

Keyword(s):

Bone Marrow ◽

Critical Role ◽

Flt3 Ligand ◽

Wild Type ◽

Graft Versus Host ◽

Equity Ownership ◽

Total Body ◽

And Function

Abstract Abstract 4003 Graft facilitating cells (FC) are a CD8+/TCR− bone marrow subpopulation that enhance engraftment of purified hematopoietic cells (HSC) in allogeneic mouse recipients without causing graft-versus-host disease. They also enhance engraftment of suboptimal numbers of syngeneic HSC. FC induce antigen-specific CD4+/CD25+/FoxP3+ regulatory T cells in vivo. The major subpopulation in FC is resembles plasmacytoid precursor dendritic cells (p-preDC) both phenotypically and functionally. Treatment of mice with Flt3 ligand (FL) results in a significant increase in FC in peripheral blood (PB) and FL-expanded-PB FC enhanced HSC engraftment. In this study, we evaluated the role of FL in FC development using FL-KO mice. We first compared FC from FL-KO B6 mice with FC from B6 mice to evaluate the FC total cellular composition. The number of FC was significantly decreased in FL-KO mice compared to wild type controls (P = 0.0003). The number of p-preDC FC was also significantly decreased (P = 0.0001), suggesting that FL is important in the development of p-preDC FC. Next, we tested whether FL-KO FC facilitate engraftment of HSC in allogeneic recipients. FC were sorted from FL-KO B6 mice and HSC (C-Kit+/Sca-1+/Lin−) were sorted from B6 mice. 10,000 B6 HSC plus 30,000 FL-KO FC were transplanted into NOD recipients conditioned with 950 cGy of total body irradiation. Controls received 10,000 B6 HSC with or without 30,000 B6 FC. Only 36% (5 of 14) NOD recipients of B6 HSC alone engrafted and two mice survived up to 160 days (Figure). Sixty-three percent (5 of 8) of recipients transplanted with B6 HSC + FL-KO B6 FC engrafted and only one mouse survived up to 160 days. Seventy-five percent (9 of 12) recipients of B6 HSC + B6 FC engrafted and seven of the mice survived more than 160 days. The level of donor chimerism in recipients of B6 HSC + B6 FC (57% ± 10%) was significantly higher than recipients of B6 HSC + FL-KO B6 FC (14% ± 3%; P = 0.003) or B6 HSC alone (22% ± 6%; P = 0.005). These data demonstrate that FL-KO FC fail to facilitate durable allogeneic HSC engraftment, suggesting that flt3-ligand plays a critical role in development of functional FC. Disclosures: Ildstad: Regenerex, LLC: Equity Ownership.

Download Full-text

Maea expressed by macrophages, but not erythroblasts, maintains postnatal murine bone marrow erythroblastic islands

Blood ◽

10.1182/blood-2018-11-888180 ◽

2019 ◽

Vol 133 (11) ◽

pp. 1222-1232 ◽

Cited By ~ 12

Author(s):

Qiaozhi Wei ◽

Philip E. Boulais ◽

Dachuan Zhang ◽

Sandra Pinho ◽

Masato Tanaka ◽

...

Keyword(s):

Bone Marrow ◽

Molecular Mechanisms ◽

Dominant Role ◽

Critical Role ◽

Conditional Knockout ◽

Murine Bone Marrow ◽

Conditional Knockout Mouse ◽

Homophilic Adhesion

Abstract The erythroblastic island (EI), formed by a central macrophage and developing erythroblasts (EBs), was first described decades ago and was recently shown to play an in vivo role in homeostatic and pathological erythropoiesis. The exact molecular mechanisms, however, mediating the interactions between macrophages and EBs remain unclear. Macrophage-EB attacher (Maea) has previously been suggested to mediate homophilic adhesion bounds bridging macrophages and EBs. Maea-deficient mice die perinatally with anemia and defective erythrocyte enucleation, suggesting a critical role in fetal erythropoiesis. Here, we generated conditional knockout mouse models of Maea to assess its cellular and postnatal contributions. Deletion of Maea in macrophages using Csf1r-Cre or CD169-Cre caused severe reductions of bone marrow (BM) macrophages, EBs, and in vivo island formation, whereas its deletion in the erythroid lineage using Epor-Cre had no such phenotype, suggesting a dominant role of Maea in the macrophage for BM erythropoiesis. Interestingly, Maea deletion in spleen macrophages did not alter their numbers or functions. Postnatal Maea deletion using Mx1-Cre or function inhibition using a novel monoclonal antibody also impaired BM erythropoiesis. These results indicate that Maea contributes to adult BM erythropoiesis by regulating the maintenance of macrophages and their interaction with EBs via an as-yet-unidentified EB receptor.

Download Full-text