scholarly journals Role of Inflammatory Monocytes in Vaccine-Induced Reduction of Helicobacter felis Infection

2015 ◽  
Vol 83 (11) ◽  
pp. 4217-4228 ◽  
Author(s):  
Mati Moyat ◽  
Matthias Mack ◽  
Hanifa Bouzourene ◽  
Dominique Velin
Keyword(s):  
Flow Cytometric Analysis ◽  
Antimicrobial Activities ◽  
Dependent Manner ◽  
Direct Role ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Helicobacter Felis ◽  
Inflammatory Monocytes

ABSTRACTDespite the proven ability of immunization to reduceHelicobacterinfection in mouse models, the precise mechanism of protection has remained elusive. In this study, we evaluated the role of inflammatory monocytes in the vaccine-induced reduction ofHelicobacter felisinfection. We first showed by using flow cytometric analysis that Ly6Clowmajor histocompatibility complex class II-positive chemokine receptor type 2 (CCR2)-positive CD64+inflammatory monocytes accumulate in the stomach mucosa during the vaccine-induced reduction ofH. felisinfection. To determine whether inflammatory monocytes played a role in the protection, these cells were depleted with anti-CCR2 depleting antibodies. Indeed, depletion of inflammatory monocytes was associated with an impaired vaccine-induced reduction ofH. felisinfection on day 5 postinfection. To determine whether inflammatory monocytes had a direct or indirect role, we studied their antimicrobial activities. We observed that inflammatory monocytes produced tumor necrosis factor alpha and inducible nitric oxide synthase (iNOS), two major antimicrobial factors. Lastly, by using aHelicobacterin vitrokilling assay, we showed that mouse inflammatory monocytes and activated human monocytes killedH. pyloriin an iNOS-dependent manner. Collectively, these data show that inflammatory monocytes play a direct role in the immunization-induced reduction ofH. felisinfection from the gastric mucosa.

scholarly journals Protective Role of Akt2 in Salmonella enterica Serovar Typhimurium-Induced Gastroenterocolitis

2011 ◽  
Vol 79 (7) ◽  
pp. 2554-2566 ◽  
Author(s):  
Winnie W. S. Kum ◽  
Bernard C. Lo ◽  
Hong B. Yu ◽  
B. Brett Finlay
Keyword(s):  
Salmonella Enterica ◽  
Annexin V ◽  
Immunohistochemical Analysis ◽  
Neutrophil Infiltration ◽  
Protective Role ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTTheSalmonellaeffector protein SopB has previously been shown to induce activation of Akt and protect epithelial cells from apoptosisin vitro. To characterize the role of Akt2 in host defense againstSalmonella entericaserovar Typhimurium infection, wild-type (WT) mice and mice lacking Akt2 (Akt2 knockout [KO] mice) were infected using aSalmonellaacute gastroenteritis model. Infected Akt2 KO mice showed a more pronounced morbidity and mortality associated with higher bacterial loads in the intestines and elevated levels of proinflammatory cytokines, including tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), and MCP-1, in the colons at 1 day postinfection compared to those shown in WT mice. Histopathological assessment and immunohistochemical analysis of cecal sections at 1 day postinfection revealed more severe inflammation and higher levels of neutrophil infiltration in the ceca of Akt2 KO mice. Flow cytometry analysis further confirmed an increase in the recruitment of Gr-1+CD11b+neutrophils and F4/80+CD11b+macrophages in the intestines of infected Akt2 KO mice. Additionally, enhanced levels of annexin V+and terminal transferase dUTP nick end labeling-positive (TUNEL+) apoptotic cells in the intestines of infected Akt2 KO mice were also observed, indicating that Akt2 plays an essential role in protection against apoptosis. Finally, the differences in bacterial loads and cecal inflammation in WT and Akt2 KO mice infected with WTSalmonellawere abolished when these mice were infected with thesopBdeletion mutant, indicating that SopB may play a role in protecting the mice fromSalmonellainfection through the activation of Akt2. These data demonstrate a definitive phenotypic abnormality in the innate response in mice lacking Akt2, underscoring the important protective role of Akt2 inSalmonellainfection.

scholarly journals Decoding the role of CBLB for innate immune responses regulating systemic dissemination during Non-Tuberculous Mycobacteria infection

2020 ◽  
Author(s):  
Srinivasu Mudalagiriyappa ◽  
Jaishree Sharma ◽  
Hazem F. M. Abdelaal ◽  
Thomas C. Kelly ◽  
Woosuk Choi ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
Granulomatous Inflammation ◽  
Innate Immune ◽  
Dependent Manner ◽  
Innate Immune Responses ◽  
Inflammatory Monocytes ◽  
Cell Immunity

AbstractNon-Tuberculous Mycobacteria (NTM) are ubiquitous in nature, present in soil and water, and cause primary leading to disseminated infections in immunocompromised individuals. NTM infections are surging in recent years due to an increase in an immune-suppressed population, medical interventions, and patients with underlying lung diseases. Host regulators of innate immune responses, frontiers for controlling infections and dissemination, are poorly defined during NTM infections. Here, we describe the role of CBLB, an E3-ubiquitin ligase, for innate immune responses and disease progression in a mouse model of NTM infection under compromised T-cell immunity. We found that CBLB thwarted NTM growth and dissemination in a time- and infection route- dependent manner. Mechanistically, we uncovered defects in many innate immune cells in the absence of Cblb, including poor responses of NK cells, inflammatory monocytes, and conventional dendritic cells. Strikingly, Cblb-deficient macrophages were competent to control NTM growth in vitro. Histopathology suggested the lack of early formation of granulomatous inflammation in the absence of CBLB. Collectively, CBLB is essential to mount productive innate immune responses and help prevent the dissemination during an NTM infection under T-cell deficiency.

scholarly journals Wnt/beta-catenin signalling is dispensable for adult neural stem cell homeostasis and activation

2020 ◽  
Author(s):  
Sophie H. L. Austin ◽  
Lachlan Harris ◽  
Oana Paun ◽  
Piero Rigo ◽  
François Guillemot ◽  
...  
Keyword(s):  
Stem Cell ◽  
Beta Catenin ◽  
Dependent Manner ◽  
Direct Role ◽  
Adult Nscs ◽  
Hippocampal Networks ◽  
Dose Dependent

AbstractAdult mouse hippocampal neural stem cells (NSCs) generate new neurons that integrate into existing hippocampal networks and modulate mood and memory. These NSCs are largely quiescent and are stimulated by niche signals to activate and produce neurons. Wnt/β-catenin signalling acts at different steps along the hippocampal neurogenic lineage and has been shown to promote the proliferation of intermediate progenitor cells. However, whether it has a direct role in the regulation of NSCs still remains unclear. Here we used Wnt/β-catenin reporters and transcriptomic data from in vivo and in vitro models to show that both active and quiescent adult NSCs respond to Wnt/β-catenin signalling. Wnt/β-catenin stimulation instructed neuronal differentiation of active NSCs and promoted the activation or differentiation of quiescent NSCs in a dose-dependent manner. However, we found that inhibiting NSCs response to Wnt, by conditionally deleting β-catenin, did not affect their activation or maintenance of their stem cell characteristics. Together, our results indicate that whilst NSCs do respond to Wnt/β-catenin stimulation in a dose-dependent and state-specific manner, Wnt/β-catenin signalling is not cell-autonomously required to maintain NSC homeostasis, which could reconcile some of the contradictions in the literature as to the role of Wnt/β-catenin signalling in adult hippocampal NSCs.

scholarly journals Induction of Glutathione Peroxidase 4 Expression during Enterocytic Cell Differentiation

2011 ◽  
Vol 286 (12) ◽  
pp. 10764-10772 ◽  
Author(s):  
Bodo Speckmann ◽  
Hans-Jürgen Bidmon ◽  
Antonio Pinto ◽  
Martin Anlauf ◽  
Helmut Sies ◽  
...  
Keyword(s):  
Glutathione Peroxidase ◽  
Promoter Activity ◽  
Tissue Cell ◽  
Dependent Manner ◽  
Direct Role ◽  
Intestinal Epithelia ◽  
Protein Levels ◽  
Enterocytic Differentiation

Glutathione peroxidase 4 (GPx4), an abundant selenoenzyme, is ubiquitously expressed in a tissue-, cell- and differentiation-dependent manner, and it is localized in cytoplasmic, mitochondrial, and nuclear cellular compartments. Here, we report cytoplasmic and nuclear localization of GPx4 in Caco-2 intestinal epithelial cells. Enterocytic differentiation of Caco-2 cells triggers an increase in GPx4 mRNA and protein levels, mediated by enhanced promoter activity. We identified a combined cAMP response element (CREB) and CCAAT/enhancer binding protein (C/EBP) site as critical for the differentiation-triggered GPx4 promoter activity. Induction of GPx4 correlated with C/EBPα transcript levels during differentiation, suggesting a role of C/EBPα as regulator of enterocytic GPx4 expression. Consistent with the in vitro results, GPx4 protein was detected in cytoplasmic and nuclear compartments of enterocytes in human intestinal epithelia. GPx4 is uniformly expressed in colonic crypts and is differentially expressed along the crypt-to-villus axis in the small intestine with a more pronounced expression of GPx4 in the upper villi, which contain fully differentiated enterocytes. These data suggest that intestinal GPx4 expression is modulated by the enterocytic differentiation program, and the results support a direct role of nuclear GPx4 in the (selenium-dependent) prevention of oxidative damage in the gastrointestinal tract.

scholarly journals DhhP, a Cyclic di-AMP Phosphodiesterase of Borrelia burgdorferi, Is Essential for Cell Growth and Virulence

2014 ◽  
Vol 82 (5) ◽  
pp. 1840-1849 ◽  
Author(s):  
Meiping Ye ◽  
Jun-Jie Zhang ◽  
Xin Fang ◽  
Gavin B. Lawlis ◽  
Bryan Troxell ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Wild Type Strain ◽  
Wall Structure ◽  
Mammalian Host ◽  
Dependent Manner ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria

ABSTRACTCyclic di-AMP (c-di-AMP) is a recently discovered second messenger in bacteria. Most of work on c-di-AMP signaling has been done in Gram-positive bacteria, firmicutes, and actinobacteria, where c-di-AMP signaling pathways affect potassium transport, cell wall structure, and antibiotic resistance. Little is known about c-di-AMP signaling in other bacteria.Borrelia burgdorferi, the causative agent of Lyme disease, is a spirochete that has a Gram-negative dual membrane. In this study, we demonstrated thatB. burgdorferiBB0619, aDHH-DHHA1 domainprotein (herein designated DhhP), functions as c-di-AMP phosphodiesterase. Recombinant DhhP hydrolyzed c-di-AMP to pApA in a Mn2+- or Mg2+-dependent manner. In contrast to c-di-AMP phosphodiesterases reported thus far, DhhP appears to be essential forB. burgdorferigrowth bothin vitroand in the mammalian host. Inactivation of the chromosomaldhhPgene could be achieved only in the presence of a plasmid-encoded inducibledhhPgene. The conditionaldhhPmutant had a dramatic increase in intracellular c-di-AMP level in comparison to the isogenic wild-type strain. Unlike what has been observed in Gram-positive bacteria, elevated cellular c-di-AMP inB. burgdorferidid not result in an increased resistance to β-lactamase antibiotics, suggesting that c-di-AMP's functions in spirochetes differ from those in Gram-positive bacteria. In addition, thedhhPmutant was defective in induction of the σSfactor, RpoS, and the RpoS-dependent outer membrane virulence factor OspC, which uncovers an important role of c-di-AMP inB. burgdorferivirulence.

scholarly journals Identification and Characterization of the Rhoptry Neck Protein 2 in Babesia divergens and B. microti

2016 ◽  
Vol 84 (5) ◽  
pp. 1574-1584 ◽  
Author(s):  
Rosalynn L. Ord ◽  
Marilis Rodriguez ◽  
Jeny R. Cursino-Santos ◽  
Hyunryung Hong ◽  
Manpreet Singh ◽  
...  
Keyword(s):  
Direct Role ◽  
Parasite Invasion ◽  
Content Type ◽  
Apicomplexan Parasites ◽  
Babesia Divergens ◽  
Associated Proteins ◽  
Identification And Characterization

Apicomplexan parasites include those of the generaPlasmodium,Cryptosporidium, andToxoplasmaand those of the relatively understudied zoonotic genusBabesia. In humans, babesiosis, particularly transfusion-transmitted babesiosis, has been emerging as a major threat to public health. Like malaria, the disease pathology is a consequence of the parasitemia which develops through cyclical replication ofBabesiaparasites in host erythrocytes. However, there are no exoerythrocytic stages inBabesia, so targeting of the blood stage and associated proteins to directly prevent parasite invasion is the most desirable option for effective disease control. Especially promising among such molecules are the rhoptry neck proteins (RONs), whose homologs have been identified in many apicomplexan parasites. RONs are involved in the formation of the moving junction, along with AMA1, but no RON has been identified and characterized in anyBabesiaspp. Here we identify the RON2 proteins ofBabesia divergens(BdRON2) andB. microti(BmRON2) and show that they are localized apically and that anti-BdRON2 antibodies are significant inhibitors of parasite invasionin vitro. Neither protein is immunodominant, as both proteins react only marginally with sera from infected animals. Further characterization of the direct role of both BdRON2 and BmRON2 in parasite invasion is required, but knowledge of the level of conformity of RON2 proteins within the apicomplexan phylum, particularly that of the AMA1-RON2 complex at the moving junction, along with the availability of an animal model forB. microtistudies, provides a key to target this complex with a goal of preventing the erythrocytic invasion of these parasites and to further our understanding of the role of these conserved ligands in invasion.

scholarly journals Role of Sca2 and RickA in the Dissemination ofRickettsia parkeriinAmblyomma maculatum

2018 ◽  
Vol 86 (6) ◽  
Author(s):  
Emma K. Harris ◽  
Krit Jirakanwisal ◽  
Victoria I. Verhoeve ◽  
Chanida Fongsaran ◽  
Chanakan Suwanbongkot ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Actin Polymerization ◽  
Dependent Manner ◽  
Wild Type ◽  
Cell Infection ◽  
Rickettsia Parkeri ◽  
Content Type ◽  
Tick Infection

ABSTRACTThe Gram-negative obligate intracellular bacteriumRickettsia parkeriis an emerging tick-borne human pathogen. Recently,R. parkeriSca2 and RickA have been implicated in adherence and actin-based motility in vertebrate host cell infection models; however, the rickettsia-derived factors essential to tick infection are unknown. UsingR. parkerimutants lacking functional Sca2 or RickA to compare actin polymerization, replication, and cell-to-cell spreadin vitro, similar phenotypes in tick and mammalian cells were observed. Specifically, actin polymerization in cultured tick cells is controlled by the two separate proteins in a time-dependent manner. To assess the role of Sca2 and RickA in dissemination in the tick host,Rickettsia-freeAmblyomma maculatum, the natural vector ofR. parkeri, was exposed to wild-type,R. parkeri rickA::tn, orR. parkeri sca2::tnbacteria, and individual tick tissues, including salivary glands, midguts, ovaries, and hemolymph, were analyzed at 12 h and after continued bloodmeal acquisition for 3 or 7 days postexposure. Initially, ticks exposed to wild-typeR. parkerihad the highest rickettsial load across all organs; however, rickettsial loads decreased and wild-type rickettsiae were cleared from the ovaries at 7 days postexposure. In contrast, ticks exposed toR. parkeririckA::tnorR. parkerisca2::tnhad comparatively lower rickettsial loads, but bacteria persisted in all organs for 7 days. These data suggest that while RickA and Sca2 function in actin polymerization in tick cells, the absence of these proteins did not change dissemination patterns within the tick vector.

scholarly journals Yeast Mpo1 Is a Novel Dioxygenase That Catalyzes the α-Oxidation of a 2-Hydroxy Fatty Acid in an Fe2+-Dependent Manner

2018 ◽  
Vol 39 (5) ◽  
Author(s):  
Naoya Seki ◽  
Keisuke Mori ◽  
Takuya Kitamura ◽  
Masatoshi Miyamoto ◽  
Akio Kihara
Keyword(s):  
Fatty Acid ◽  
Metabolic Pathway ◽  
Oxidation Reaction ◽  
Soluble Fraction ◽  
Dependent Manner ◽  
The Novel ◽  
Content Type ◽  
Long Chain Base

ABSTRACT Phytosphingosine (PHS) is the major long-chain base component of sphingolipids in Saccharomyces cerevisiae. The PHS metabolic pathway includes a fatty acid (FA) α-oxidation reaction. Recently, we identified the novel protein Mpo1, which is involved in PHS metabolism. However, the details of the FA α-oxidation reaction and the role of Mpo1 in PHS metabolism remained unclear. In the present study, we revealed that Mpo1 is involved in the α-oxidation of 2-hydroxy (2-OH) palmitic acid (C16:0-COOH) in the PHS metabolic pathway. Our in vitro assay revealed that not only the Mpo1-containing membrane fraction but also the soluble fraction was required for the α-oxidation of 2-OH C16:0-COOH. The addition of Fe2+ eliminated the need for the soluble fraction. Purified Mpo1 converted 2-OH C16:0-COOH to C15:0-COOH in the presence of Fe2+, indicating that Mpo1 is the enzyme body responsible for catalyzing the FA α-oxidation reaction. This reaction was also found to require an oxygen molecule. Our findings indicate that Mpo1 catalyzes the FA α-oxidation reaction as 2-OH fatty acid dioxygenase, mediated by iron(IV) peroxide. Although numerous Mpo1 homologs exist in bacteria, fungi, protozoa, and plants, their functions had not yet been clarified. However, our findings suggest that these family members function as dioxygenases.

scholarly journals MicroRNA-155 Deficiency Exacerbates Trypanosoma cruzi Infection

2020 ◽  
Vol 88 (7) ◽  
Author(s):  
Bijay K. Jha ◽  
Sanjay Varikuti ◽  
Gabriella R. Seidler ◽  
Greta Volpedo ◽  
Abhay R. Satoskar ◽  
...  
Keyword(s):  
T Cells ◽  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Public Health Problem ◽  
Protozoan Parasite ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Inflammatory Monocytes ◽  
Nk T Cells

ABSTRACT Chagas disease, caused by the intracellular protozoan parasite Trypanosoma cruzi, is a public health problem affecting 6 to 8 million people, mainly in Latin America. The role of microRNAs in the pathogenesis of Chagas disease has not been well described. Here, we investigate the role of microRNA-155 (miR-155), a proinflammatory host innate immune regulator responsible for T helper type 1 and type 17 (Th1 and Th17) development and macrophage responses during T. cruzi infection. For this, we compared the survival and parasite growth and distribution in miR-155−/− and wild-type (WT) C57BL/6 mice. The lack of miR-155 caused robust parasite infection and diminished survival of infected mice, while WT mice were resistant to infection. Immunological analysis of infected mice indicated that, in the absence of miR-155, there was decreased interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) production. In addition, we found that there was a significant reduction of CD8-positive (CD8+) T cells, natural killer (NK) cells, and NK-T cells and increased accumulation of neutrophils and inflammatory monocytes in miR-155−/− mice. Collectively, these data indicate that miR-155 is an important immune regulatory molecule critical for the control of T. cruzi infection.

Role of estrogen receptor—related antigen in initiating the growth of human glioma cells

2004 ◽  
Vol 100 (5) ◽  
pp. 923-930 ◽  
Author(s):  
M. Humayun Khalid ◽  
Shobu Shibata ◽  
Koichi Furukawa ◽  
Amal Nadel ◽  
Matthew D. Ammerman ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Cell Growth ◽  
Cell Lines ◽  
Cycle Phase ◽  
Normal Brain ◽  
Dependent Manner ◽  
Content Type ◽  
Fine Print

Object. The expression of estrogen receptor—related antigen (ER-D5) has been demonstrated in many tumors, including those of the brain, but the actual role of ER-D5 in cell growth is unknown. The authors evaluated the role of ER-D5 in the growth of gliomas in vitro. Methods. Human glioblastoma multiforme (GBM) cell lines A172, T98G, U87MG, and U118MG; rat C6 glioma and 9L gliosarcoma; AS human astrocytoma; GBM in primary culture and tumor tissues; and normal brain tissues were examined for ER-D5 by using immunohistochemical, Western immunoblot, flow cytometry, and enzyme-linked immunosorbent assays. The ER-D5 was detected in all tumor cell types of human origin, but not in rat cell lines and normal brain; the expression of ER-D5 was not related to cell cycle phase. Kinetic analysis of ER-D5 expression in cultured cell lines revealed that an enhanced and sharp accumulation of ER-D5 occurred during the first 24 hours of culture, followed by a sharp fall in the next 24 hours. Gradual decreases of ER-D5 during the subsequent days were demonstrated in all human cell lines, and in primary cultures of GBM. This accumulation pattern of ER-D5 was confirmed on Western blot analysis. The ER-D5 was also detected in cells cultured in serum-free medium. Culture cells were treated with D5 antibody against ER-D5 for 48 hours and the effects were evaluated using a monotetrazolium colorimetric assay; the result revealed that growth of cultured cells was inhibited in a dose-dependent manner, and that addition of a single median inhibitory concentration dose resulted in complete growth inhibition and arrest of cell growth at the G0/G1 phase at 96 hours posttreatment. Conclusions. These findings indicated that synthesis and accumulation of ER-D5 is an essential event in the very early phase of in vitro growth of human gliomas.

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