Pseudomonas aeruginosa eliminates natural killer cells via phagocytosis-induced apoptosis.
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ABSTRACT:
SUBMITTER: Chung JW
PROVIDER: S-EPMC2726936 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Defects in natural killer (NK) cell functions are necessary for tumor immune escape, but their underlying regulatory mechanisms in human cancers remain largely unknown. Here we showed, in detailed studies of NK cells from 235 untreated patients with gastric cancer (GC), the NK cell density in GC tissues could predict improved survival of patients. However, NK cells were significantly decreased in number with advanced-stage GC. A multivariate Cox analysis revealed that the intratumoral NK cell density was an independent prognostic factor for overall survival and disease-free survival in the GC patients. Most of the intratumoral NK cells exhibited a normal phenotype and secreted normal levels of cytokines, but the expression of Ki67 was decreased compared with NK cells from nontumoral regions. Moreover, the levels of intratumoral NK cells were negatively correlated with the intratumoral expression of cyclooxygenase-2. Furthermore, we found that PGE2 derived from GC cells suppressed NK cell proliferation and increased apoptosis in vitro. These data reveal that tumor-derived PGE2 is critical for inducing NK cell dysfunction in GC and demonstrate that an extensive infiltration of NK cells predicts a good prognosis in patients with GC. Our findings suggest that immunosuppressive barriers erected by tumors greatly hamper the antitumor activity of human NK cells, thereby favoring tumor outgrowth and progression.
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Project description:Pseudomonas aeruginosa infection can induce alveolar macrophage apoptosis and autophagy, which play a vital role in eliminating pathogens. These two processes are usually not independent. Recently, autophagy has been found to interact with apoptosis during pathogen infections. Nevertheless, the role of autophagy in P. aeruginosa-infected cell apoptosis is unclear. In this study, we explored the impact of P. aeruginosa infection on autophagy and apoptosis in RAW264.7 cells. The autophagy activator rapamycin was used to stimulate autophagy and explore the role of autophagy on apoptosis in P. aeruginosa-infected RAW264.7 cells. The results indicated that P. aeruginosa infection induced autophagy and apoptosis in RAW264.7 cells, and that rapamycin could suppress P. aeruginosa-induced apoptosis by regulating the expression of apoptosis-related proteins. In addition, rapamycin scavenged the cellular reactive oxygen species (ROS) and diminished p-JNK, p-ERK1/2 and p-p38 expression of MAPK pathways in RAW264.7 cells infected with P. aeruginosa. In conclusion, the promotion of autophagy decreased P. aeruginosa-induced ROS accumulation and further attenuated the apoptosis of RAW264.7 cells through MAPK pathway. These results provide novel insights into host-pathogen interactions and highlight a potential role of autophagy in eliminating P. aeruginosa.
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Project description:Epidemiological studies have suggested that the recent increase in the incidence and severity of immunoglobulin (Ig)E-mediated allergic disorders is inversely correlated with Mycobacterium bovis bacillus Calmette Guerin (BCG) vaccination; however, the underlying mechanisms remain uncertain. Here, we demonstrate that natural killer T (NKT) cells in mice and humans play a crucial role in the BCG-induced suppression of IgE responses. BCG-activated murine Valpha14 NKT cells, but not conventional CD4 T cells, selectively express high levels of interleukin (IL)-21, which preferentially induces apoptosis in Bepsilon cells. Signaling from the IL-21 receptor increases the formation of a complex between Bcl-2 and the proapoptotic molecule Bcl-2-modifying factor, resulting in Bepsilon cell apoptosis. Similarly, BCG vaccination induces IL-21 expression by human peripheral blood mononuclear cells (PBMCs) in a partially NKT cell-dependent fashion. BCG-activated PBMCs significantly reduce IgE production by human B cells. These findings provide new insight into the therapeutic effect of BCG in allergic diseases.
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Project description:The mammalian immune response to infection is mediated by 2 broad arms, the innate and adaptive immune systems. Innate immune cells are a first-line defense against pathogens and are thought to respond consistently to infection, regardless of previous exposure, i.e., they do not exhibit memory of prior activation. By contrast, adaptive immune cells display immunologic memory that has 2 basic characteristics, antigen specificity and an amplified response upon subsequent exposure. Whereas adaptive immune cells have rearranged receptor genes to recognize the universe of antigens, natural killer (NK) cells are innate immune lymphocytes with a limited repertoire of germ-line encoded receptors for target recognition. NK cells also produce cytokines such as IFN-gamma (IFN-gamma) to protect the host during the innate response to infection. Herein, we show that cytokine-activated NK cells transferred into naïve hosts can be specifically detected 7-22 days later when they are phenotypically similar to naïve cells and are not constitutively producing IFN-gamma. However, they produce significantly more IFN-gamma when restimulated. This memory-like property is intrinsic to the NK cell. By contrast, memory-like NK cells do not express granzyme B protein and kill targets similarly to naïve NK cells. Thus, these experiments identify an ability of innate immune cells to retain an intrinsic memory of prior activation, a function until now attributed only to antigen-specific adaptive immune cells.
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Project description:Pseudomonas aeruginosa causes severe respiratory tract infections in patients with cystic fibrosis (CF). We have been examining nonopsonic phagocytosis of P. aeruginosa by macrophages. To study the P. aeruginosa-macrophage interaction at the molecular level, we have constructed a transposon Tn5G bank in a clinical isolate of P. aeruginosa (strain 4020) and identified mutants resistant to nonopsonic phagocytosis. Phagocytosis-resistant mutants were enriched by passaging the transposon bank over 18 macrophage monolayers. Of 900 individual mutants isolated from this enriched pool in a nonopsonic phagocytosis assay, we identified 85 putative mutants that were resistant to phagocytosis. In this study, we have characterized one of these transposon mutants, P. aeruginosa 4020 H27A, which was poorly ingested. H27A possessed a Tn5G insertion in a gene encoding a protein with homology to the MotA proteins of several species of bacteria. We have called this gene rpmA for required for phagocytosis by macrophages. RpmA is one of two MotA paralogs in P. aeruginosa. This rpmA::Tn5G mutant was motile both on agar plates and in visual examination of wet mounts. The phagocytosis defect was partially complemented by providing the rpmA gene in trans and fully complemented when both rpmA and rpmB were provided. A rpmA null mutant was ingested by macrophages similar to the H27A transposon mutant. These data suggest that the rpmA and rpmB gene products are required for the efficient ingestion of P. aeruginosa by macrophages.
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Project description:Pathogenic bacteria that establish chronic infections in immunocompromised patients frequently undergo adaptation or selection for traits that are advantageous for their growth and survival. Clinical isolates of Pseudomonas aeruginosa, a Gram-negative, opportunistic bacterial pathogen, exhibit a temporal transition from a motile to a nonmotile phenotype through loss of flagellar motility during the course of chronic infection. This progressive loss of motility is associated with increased resistance to both antibiotic and immune clearance. We have previously shown that loss of bacterial motility enables P. aeruginosa to evade phagocytic clearance both in vitro and in vivo and fails to activate the phosphatidylinositol 3-kinase (PI3K)/Akt-dependent phagocytic pathway. Therefore, we tested the hypothesis that clearance of phagocytosis-resistant bacteria could be induced by exogenously pretreating innate immune cells with the Akt-activating molecule phosphatidylinositol-(3,4,5)-trisphosphate (PIP3). Here, we demonstrate that PIP3 induces the uptake of nonmotile P. aeruginosa by primary human neutrophils >25-fold, and this effect is phenocopied with the use of murine phagocytes. However, surprisingly, mechanistic studies revealed that the induction of phagocytosis by PIP3 occurs because polyphosphoinositides promote bacterial binding by the phagocytes rather than bypassing the requirement for PI3K. Moreover, this induction was selective since the uptake of other nonmotile Gram-negative, but not Gram-positive, bacteria can also be induced by PIP3 Since there is currently no treatment that effectively eradicates chronic P. aeruginosa infections, these findings provide novel insights into a potential methodology by which to induce clearance of nonmotile pathogenic bacteria and into the endogenous determinants of phagocytic recognition of P. aeruginosa.
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Project description:Natural killer (NK) cells belong to innate immunity and exhibit cytolytic activity against infectious pathogens and tumor cells. NK-cell function is finely tuned by receptors that transduce inhibitory or activating signals, such as killer immunoglobulin-like receptors, NK Group 2 member D (NKG2D), NKG2A/CD94, NKp46, and others, and recognize both foreign and self-antigens expressed by NK-susceptible targets. Recent insights into NK-cell developmental intermediates have translated into a more accurate definition of culture conditions for the in vitro generation and propagation of human NK cells. In this respect, interleukin (IL)-15 and IL-21 are instrumental in driving NK-cell differentiation and maturation, and hold great promise for the design of optimal NK-cell culture protocols. Cytokine-induced killer (CIK) cells possess phenotypic and functional hallmarks of both T cells and NK cells. Similar to T cells, they express CD3 and are expandable in culture, while not requiring functional priming for in vivo activity, like NK cells. CIK cells may offer some advantages over other cell therapy products, including ease of in vitro propagation and no need for exogenous administration of IL-2 for in vivo priming. NK cells and CIK cells can be expanded using a variety of clinical-grade approaches, before their infusion into patients with cancer. Herein, we discuss GMP-compliant strategies to isolate and expand human NK and CIK cells for immunotherapy purposes, focusing on clinical trials of adoptive transfer to patients with hematological malignancies.
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Project description:Natural killer (NK) cells are innate lymphoid cells that are important for host defense against infection and mediate antitumor responses. Recent reports from several laboratories have identified that NK cells can remember a prior activation event and consequently respond more robustly when restimulated, a property termed innate NK cell memory. NK cell memory has now been identified following hapten exposure, viral infection, and combined cytokine preactivation with IL-12, IL-15, and IL-18. Many questions in the field remain regarding the cellular and molecular mechanisms regulating memory NK cells and their responses, as well as their formation and function in mice and humans. Here we review our current understanding of cytokine-induced memory-like (CIML) NK cells that are generated by combined preactivation with IL-12, IL-15, and IL-18. These cells exhibit enhanced NK cell effector functions weeks after the initial cytokine preactivation. Further, we highlight the preclinical rationale and ongoing therapeutic application of CIML NK cells for adoptive immunotherapy in patients with hematologic malignancies.
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Project description:The great demand of people for consumption of natural additives resulted in producing natural vanillin. There are plant sources and chemical procedures for vanillin production but microbial bioconversions are being sought as a suitable alternative. In the present work, the ability to produce vanillin from isoeugenol was screened using growing cultures of various bacteria. Among the 56 strains of bacteria isolated from the soil environments of Iran, a Gram-negative rod designated as strain ISPC2 showed the capability of promoting the formation of high amounts of vanillin when grown in the presence of isoeugenol. On the basis of morphological and physiochemical characteristics and 16S ribosomal ribonucleic acid (rRNA) gene sequence analysis, the isolate was identified as Pseudomonas aeruginosa ISPC2. Vanillin formation was analyzed by GC/FID. In the presence of isoeugenol, a growing culture of P. aeruginosa ISPC2 produced 1.62 g/L vanillin (molar yield of 17.3%) after a 72 h reaction at 30°C and 200 rpm. This proposed procedure is an alternative approach to obtain vanillin in an environmentally friendly way. Further studies for standardization and optimization for higher yield of vanillin production, needs to be investigated.
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Project description:PurposeWe determined whether elimination of CD105+ cells in the tumor microenvironment (TME) with anti-CD105 antibodies enhanced anti-disialoganglioside (GD2) antibody dinutuximab therapy of neuroblastoma when combined with activated natural killer (aNK) cells.Experimental designThe effect of MSCs and monocytes on antibody-dependent cellular cytotoxicity (ADCC) mediated by dinutuximab with aNK cells against neuroblastoma cells was determined in vitro. ADCC with anti-CD105 mAb TRC105 and aNK cells against MSCs, monocytes, and endothelial cells, which express CD105, was evaluated. Anti-neuroblastoma activity in immunodeficient NSG mice of dinutuximab with aNK cells without or with anti-CD105 mAbs was determined using neuroblastoma cell lines and a patient-derived xenograft.ResultsADCC mediated by dinutuximab with aNK cells against neuroblastoma cells in vitro was suppressed by addition of MSCs and monocytes, and dinutuximab with aNK cells was less effective against neuroblastomas formed with coinjected MSCs and monocytes in NSG mice than against those formed by tumor cells alone. Anti-CD105 antibody TRC105 with aNK cells mediated ADCC against MSCs, monocytes, and endothelial cells. Neuroblastomas formed in NSG mice by two neuroblastoma cell lines or a patient-derived xenograft coinjected with MSCs and monocytes were most effectively treated with dinutuximab and aNK cells when anti-human (TRC105) and anti-mouse (M1043) CD105 antibodies were added, which depleted human MSCs and murine endothelial cells and macrophages from the TME.ConclusionsImmunotherapy of neuroblastoma with anti-GD2 antibody dinutuximab and aNK cells is suppressed by CD105+ cells in the TME, but suppression is overcome by adding anti-CD105 antibodies to eliminate CD105+ cells.
| S-EPMC6738573 | biostudies-literature