Primary ovarian insufficiency (POI) is defined as the loss of ovarian function before 40 years of age. It clinically manifests as amenorrhea, infertility, and signs of estrogen insufficiency. POI is ...frequently induced by chemotherapy. Gonadotoxic chemotherapy reagents damage granulosa cells, which are essential for follicular function and development. Our recently published studies demonstrated that intraovarian transplantation of human mesenchymal stem cells (hMSCs) can restore fertility in a chemotherapy-induced POI mouse model. However, the regenerative mechanism underlying the hMSC effect in POI mice is not fully understood. Here, we report that the hMSC secretome increased the proliferation of human granulosa cells (HGrC1). We showed by FACS analysis that treatment of HGrC1 cells with hMSC-conditioned media (hMSC CM) stimulates cellular proliferation. We also demonstrated that the expression of steroidogenic enzymes involved in the production of estrogen, CYP19A1 and StAR, are significantly elevated in hMSC CM-treated HGrC1 cells. Our data suggest that hMSC CM stimulates granulosa cell proliferation and function, which may explain the therapeutic effect of hMSCs in our chemotherapy-induced POI animal model. Our findings indicate that the hMSC secretome may be a novel treatment approach for restoring granulosa cell and ovarian function in patients with POI.
Ehrlichia is Gram negative obligate intracellular bacterium that cause human monocytotropic ehrlichiosis (HME). HME is characterized by acute liver damage and inflammation that may progress to fatal ...toxic shock. We previously showed that fatal ehrlichiosis is due to deleterious activation of inflammasome pathways, which causes excessive inflammation and liver injury. Mammalian cells have developed mechanisms to control oxidative stress via regulation of nuclear factor erythroid 2 related 2 (NRF2) signaling. However, the contribution of NRF2 signaling to Ehrlichia-induced inflammasome activation and liver damage remains elusive. In this study, we investigated the contribution of NRF2 signaling in hepatocytes (HCs) to the pathogenesis of Ehrlichia-induced liver injury following infection with virulent Ixodes ovatus Ehrlichia (IOE, AKA E. japonica). Employing murine model of fatal ehrlichiosis, we found that virulent IOE inhibited NRF2 signaling in liver tissue of infected mice and in HCs as evidenced by downregulation of NRF2 expression, and downstream target GPX4, as well as decreased NRF2 nuclear translocation, a key step in NRF2 activation. This was associated with activation of non-canonical inflammasomes pathway marked by activation of caspase 11, accumulation of reactive oxygen species (ROS), mitochondrial dysfunction, and endoplasmic reticulum (ER) stress. Mechanistically, treatment of IOE-infected HCs with the antioxidant 3H-1,2-Dithiole-3-Thione (D3T), that induces NRF2 activation, attenuated oxidative stress and caspase 11 activation, as well as restored cell viability. Importantly, treatment of IOE-infected mice with D3T resulted in attenuated liver pathology, decreased inflammation, enhanced bacterial clearance, prolonged survival, and resistance to fatal ehrlichiosis. Our study reveals, for the first time, that targeting anti-oxidative signaling pathway is a key approach in the treatment of severe and potential Ehrlichia-induced acute liver injury and sepsis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
IFN‐I signaling exacerbate liver pathology and contribute to sepsis following fatal Ehrlichia infection by promoting Ehrlichia replication and mediating detrimental inflammasome activation.
...Inflammasomes are an important innate immune host defense against intracellular microbial infection. Activation of inflammasomes by microbial or host ligands results in cleavage of caspase‐1 (canonical pathway) or caspase‐11 (noncanonical pathway), release of interleukin (IL)‐1β, IL‐18, high mobility group box 1 (HMGB1), and inflammatory cell death known as pyroptosis. Ehrlichia are obligate, intracellular, gram‐negative bacteria that lack lipopolysaccharide but cause potentially life‐threatening monocytic ehrlichiosis in humans and mice that is characterized by liver injury followed by sepsis and multiorgan failure. Employing murine models of mild and fatal ehrlichiosis caused by infection with mildly and highly virulent Ehrlichia muris (EM) and Ixodes ovatus Ehrlichia (IOE), respectively, we have previously shown that IOE infection triggers type I interferon (IFN‐I) response and deleterious caspase‐11 activation in liver tissues, which promotes liver injury and sepsis. In this study, we examined the contribution of IFN‐I signaling in hepatocytes (HCs) to Ehrlichia‐induced liver injury. Compared to EM infection, we found that IOE enter and replicate in vitro cultured primary murine HCs and induce secretion of IFNβ and several chemokines, including regulated upon activation, normal T‐cell expressed, and secreted (RANTES), monocyte chemoattractant protein 1 (MCP1), monokine induced by gamma (MIG)/chemokine (C‐X‐C motif) ligand 9 (CXCL9), macrophage inflammatory protein 1 alpha (MIP1α), keratinocyte‐derived chemokine (KC), and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF). Notably, in vitro stimulation of uninfected and Ehrlichia‐infected HCs with recombinant IFNβ triggered activation of caspase‐1/11, cytosolic translocation of HMGB1, and enhanced autophagy and intracellular bacterial replication. Secretion of HMGB1 by IOE‐infected HCs was dependent on caspase‐11. Primary HCs from IOE‐ but not EM‐infected mice also expressed active caspase‐1/11. Conclusion: HC‐specific IFN‐I signaling may exacerbate liver pathology during infection with obligate intracellular Ehrlichia by promoting bacterial replication and detrimental caspase‐11‐mediated inflammasome activation.
It is widely accepted that dynamic and reversible tumour cell plasticity is required for metastasis, however, in vivo steps and molecular mechanisms are poorly elucidated. We demonstrate here that ...monocytic (mMDSC) and granulocytic (gMDSC) subsets of myeloid-derived suppressor cells infiltrate in the primary tumour and distant organs with different time kinetics and regulate spatiotemporal tumour plasticity. Using co-culture experiments and mouse transcriptome analyses in syngeneic mouse models, we provide evidence that tumour-infiltrated mMDSCs facilitate tumour cell dissemination from the primary site by inducing EMT/CSC phenotype. In contrast, pulmonary gMDSC infiltrates support the metastatic growth by reverting EMT/CSC phenotype and promoting tumour cell proliferation. Furthermore, lung-derived gMDSCs isolated from tumour-bearing animals enhance metastatic growth of already disseminated tumour cells. MDSC-induced 'metastatic gene signature' derived from murine syngeneic model predicts poor patient survival in the majority of human solid tumours. Thus spatiotemporal MDSC infiltration may have clinical implications in tumour progression.
Glioblastoma is the most common primary brain tumor in adults and one of its hallmarks is resistance to apoptosis. Acyl-CoA: cholesterol acyltransferase (ACAT) is an intracellular membrane-bound ...enzyme that uses cholesterol and long chain fatty acyl-CoA as substrates to produce cholesteryl esters. The presence of cholesteryl esters in glioblastoma may be related to vascular and/or cell neoplastic proliferation in the tumor mass, two prerequisites for tumor cell growth. ACAT activity has been detected in glioblastoma cell homogenates. The present study is the first report on the effect of Avasimibe, a specific inhibitor of ACAT, on glioma cell lines (U87, A172, and GL261). Our results showed that Avasimibe inhibited ACAT-1 expression and cholesterol ester synthesis in glioma cell lines. Moreover, Avasimibe inhibited the growth of the cells by inducing cell cycle arrest and induced apoptosis as a result of caspase-8 and caspase-3 activation. Also, Our findings provide proof of principle that targeting ACAT-1 with the inhibitor Avasimibe could be an efficient therapy in the treatment of glioblastoma.
The Hedgehog (Hh) signaling pathway is a developmentally conserved regulator of stem cell function. Several reports suggested that Hh signaling is an important regulator of hematopoietic stem cell ...(HSC) maintenance and differentiation. Here we test this hypothesis in vivo using both gain- and loss-of-function Hh genetic models. Surprisingly, our studies demonstrate that conditional
Smoothened (
Smo) deletion or overactivation has no significant effects on adult HSC self-renewal and function. Moreover, they indicate a lack of synergism between the Notch and Hh pathways in HSC function, as compound
RBPJ and
Smo deficiency does not affect hematopoiesis. In agreement with this notion, detailed genome-wide transcriptome analysis reveals that silencing of Hh signaling does not significantly alter the HSC-specific gene expression “signature.” Our studies demonstrate that the Hh signaling pathway is dispensable for adult HSC function and suggest that Hh inhibition on leukemia-initiating cell maintenance can be targeted in future clinical trials.
Regulatory CD4+CD25+ T cells have been shown to play an important role in the regulation of the immune response. Whereas the presence of these cells has been associated with immune suppression, the ...lack of regulatory T (Treg) cells has been shown to induce autoimmunity. The purpose of this study was to define the role of Treg cells in tumors of the central nervous system (CNS).
The authors implanted syngeneic GL261 tumor cells in the brains or flanks of C57BL/6 mice. The resulting tumors were later removed at specific time points, and the presence of tumor-infiltrating lymphocytes was analyzed by performing flow cytometry for the presence of Treg cells. In a separate experiment, mice with GL261 tumors were treated with injections of anti-CD25 monoclonal antibody (mAb) to determine whether depletion of Treg cells may have an impact on the length of survival in mice with brain tumors. Tumor-infiltrating lymphocytes isolated from mice with GL261 tumors were found to have a significant increase in the presence of Treg cells compared with control lymphocytes (p < 0.05). Moreover, Treg cells isolated in murine brain tumors expressed FoxP3, CTLA-4, and CD62L. Mice treated with anti-CD25 mAb lived significantly longer than tumor-bearing control animals (p < 0.05). An analysis of brains in surviving animals showed a depletion of CD4+CD25+ T cells.
The results of this study indicate that CD4+CD25+ Treg cells play an important role in suppressing the immune response to CNS tumors. These Treg cells may therefore represent a potentially novel target for immunotherapy of malignant gliomas.
Ehrlichiae are gram-negative obligate intracellular bacteria that cause potentially fatal human monocytic ehrlichiosis. We previously showed that natural killer (NK) cells play a critical role in ...host defense against Ehrlichia during primary infection. However, the contribution of NK cells to the memory response against Ehrlichia remains elusive. Primary infection of C57BL/6 mice with Ehrlichia muris provides long-term protection against a second challenge with the highly virulent Ixodes ovatus Ehrlichia (IOE), which ordinarily causes fatal disease in naïve mice. Here, we show that the depletion of NK cells in E. muris-primed mice abrogates the protective memory response against IOE. Approximately, 80% of NK cell-depleted E. muris-primed mice succumbed to lethal IOE infection on days 8-10 after IOE infection, similar to naïve mice infected with the same dose of IOE. The lack of a recall response in NK cell-depleted mice correlated with an increased bacterial burden, extensive liver injury, decreased frequency of Ehrlichia-specific IFN-γ-producing memory CD4+ and CD8+ T-cells, and a low titer of Ehrlichia-specific antibodies. Intraperitoneal infection of mice with E. muris resulted in the production of IL-15, IL-12, and IFN-γ as well as an expansion of activated NKG2D+ NK cells. The adoptive transfer of purified E. muris-primed hepatic and splenic NK cells into Rag2-/-Il2rg-/- recipient mice provided protective immunity against challenge with E. muris. Together, these data suggest that E. muris-induced memory-like NK cells, which contribute to the protective, recall response against Ehrlichia.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A polarized macrophage response into inflammatory (M1) or regenerative/anti-inflammatory (M2) phenotypes is critical in host response to multiple intracellular bacterial infections. Ehrlichia is an ...obligate Gram-negative intracellular bacterium that causes human monocytic ehrlichiosis (HME): a febrile illness that may progress to fatal sepsis with multi-organ failure. We have shown that liver injury and Ehrlichia-induced sepsis occur due to dysregulated inflammation. Here, we investigated the contribution of macrophages to Ehrlichia-induced sepsis using murine models of mild and fatal ehrlichiosis. Lethally-infected mice showed accumulation of M1 macrophages (iNOS-positive) in the liver. In contrast, non-lethally infected mice showed polarization of M2 macrophages and their accumulation in peritoneum, but not in the liver. Predominance of M1 macrophages in lethally-infected mice was associated with expansion of IL-17-producing T, NK, and NKT cells. Consistent with the in vivo data, infection of bone marrow-derived macrophages (BMM) with lethal Ehrlichia polarized M0 macrophages into M1 phenotype under an mTORC1-dependent manner, while infection with non-lethal Ehrlichia polarized these cells into M2 types. This work highlights that mTORC1-mediated polarization of macrophages towards M1 phenotype may contribute to induction of pathogenic immune responses during fatal ehrlichiosis. Targeting mTORC1 pathway may provide a novel aproach for treatment of HME.
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