scholarly journals Miltefosine enhances infectivity of miltefosine-resistant Leishmania infantum by attenuating innate immune recognition

2021 ◽  
Author(s):  
Dimitri Bulté ◽  
Lieselotte Van Bockstal ◽  
Laura Dirkx ◽  
Magali Van den Kerkhof ◽  
Carl De Trez ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Leishmania Infantum ◽  
Innate Immune ◽  
Clinical Isolates ◽  
Sand Fly ◽  
Oral Drug ◽  
Immune Recognition ◽  
Drug Dependency ◽  
Ifn Γ

AbstractMiltefosine (MIL) is currently the only oral drug available to treat visceral leishmaniasis but its use as first-line monotherapy has been compromised by an increasing treatment failure. Despite the scarce number of resistant clinical isolates, MIL-resistance by mutations in a single aminophospholipid transporter gene can easily be selected in a laboratory environment. These mutations result in a reduced survival in the mammalian host, which can partially be restored by exposure to MIL, suggesting a kind of drug-dependency. To enable a combined study of the infection dynamics and underlying immunological events for differential in vivo survival, firefly luciferase (PpyRE9) / red fluorescent protein (DsRed) double-reporter strains were generated of MIL-resistant (MIL-R) and syngeneic MIL-sensitive (MIL-S) Leishmania infantum. Results in C57Bl/6 and BALB/c mice show that MIL-R parasites induce an increased innate immune response that is characterized by enhanced influx and infection of neutrophils, monocytes and dendritic cells in the liver and elevated serum IFN-γ levels, finally resulting in a less efficient establishment in liver macrophages. The elevated IFN-γ levels were shown to originate from an increased response of hepatic NK and NKT cells to the MIL-R parasites. In addition, we demonstrated that MIL could increase the in vivo fitness of MIL-R parasites by lowering NK and NKT cell activation, leading to a reduced IFN-γ production. These data provide an immunological basis for the MIL-R-associated attenuated phenotype and for the peculiar drug-dependency that may constitute one of the mechanisms of treatment failure.ImportanceRecently, our laboratory demonstrated an in vivo fitness loss of experimentally selected MIL-R parasites in both the sand fly vector and vertebrate host. These findings could explain the scarce number of MIL-R clinical isolates. Surprisingly, MIL-R parasites developed a MIL-dependency which could partially rescue their fitness loss and which may constitute a mechanism of treatment failure. This research aimed to better understand the immunological basis of the attenuated phenotype and the effect of MIL on infectivity traits. Together, this study provides new insights into the complex interplay between the parasite, drug and host and discloses an immune-related mechanism of treatment failure.

scholarly journals Miltefosine enhances infectivity of a miltefosine-resistant Leishmania infantum strain by attenuating its innate immune recognition

2021 ◽  
Vol 15 (7) ◽  
pp. e0009622
Author(s):  
Dimitri Bulté ◽  
Lieselotte Van Bockstal ◽  
Laura Dirkx ◽  
Magali Van den Kerkhof ◽  
Carl De Trez ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Leishmania Infantum ◽  
Innate Immune ◽  
Oral Drug ◽  
Mammalian Host ◽  
Immune Recognition ◽  
Drug Dependency ◽  
Ifn Γ ◽  
The Impact

Background Miltefosine (MIL) is currently the only oral drug available to treat visceral leishmaniasis but its use as first-line monotherapy has been compromised by an increasing treatment failure. Despite the scarce number of resistant clinical isolates, MIL-resistance by mutations in a single aminophospholipid transporter gene can easily be selected in a laboratory environment. These mutations result in a reduced survival in the mammalian host, which can partially be restored by exposure to MIL, suggesting a kind of drug-dependency. Methodology/Principal findings To enable a combined study of the infection dynamics and underlying immunological events for differential in vivo survival, firefly luciferase (PpyRE9) / red fluorescent protein (DsRed) double-reporter strains were generated of MIL-resistant (MIL-R) and syngeneic MIL-sensitive (MIL-S) Leishmania infantum. Results in C57Bl/6 and BALB/c mice show that MIL-R parasites induce an increased innate immune response that is characterized by enhanced influx and infection of neutrophils, monocytes and dendritic cells in the liver and elevated serum IFN-γ levels, finally resulting in a less efficient establishment in liver macrophages. The elevated IFN-γ levels were shown to originate from an increased response of hepatic NK and NKT cells to the MIL-R parasites. In addition, we demonstrated that MIL could increase the in vivo fitness of MIL-R parasites by lowering NK and NKT cell activation, leading to a reduced IFN-γ production. Conclusions/Significance Differential induction of innate immune responses in the liver was found to underlie the attenuated phenotype of a MIL-R parasite and its peculiar feature of drug-dependency. The impact of MIL on hepatic NK and NKT activation and IFN-γ production following recognition of a MIL-R strain indicates that this mechanism may sustain infections with resistant parasites and contribute to treatment failure.

scholarly journals Stem Cell Factor Enhances Interleukin-2–Mediated Expansion of Murine Natural Killer Cells In Vivo

Blood ◽  
1997 ◽  
Vol 90 (9) ◽  
pp. 3647-3653 ◽  
Author(s):  
Todd A. Fehniger ◽  
William E. Carson ◽  
Ewa Mrózek ◽  
Michael A. Caligiuri
Keyword(s):  
Nk Cells ◽  
Cell Expansion ◽  
Stem Cell Factor ◽  
Low Dose ◽  
Nk Cell ◽  
Interleukin 2 ◽  
Innate Immune ◽  
Ifn Γ

Abstract The administration of low dose interleukin-2 (IL-2) results in a selective expansion of natural killer (NK) cells in vivo, and promotes the differentiation of NK cells from hematopoietic precursor cells in vitro. We have previously shown that stem cell factor (SCF ), the ligand to the c-kit tyrosine kinase receptor, enhances IL-2–induced NK cell proliferation and differentiation in vitro. Here, we investigated the effects of SCF plus IL-2 delivered to mice in vivo. Eight-week-old C57BL/6 mice were treated with a continuous subcutaneous infusion of IL-2 (1 × 104 IU/d) plus a daily intraperitoneal dose of SCF (100 μg/kg/d), IL-2 alone, SCF alone, or vehicle alone for 8 weeks. The in vivo serum concentration of IL-2 ranged between 352 ± 12.0 pg/mL and 606 ± 9.0 pg/mL, achieving selective saturation of the high affinity IL-2 receptor, while the peak SCF serum concentration was 296 ± 13.09 ng/mL. Alone, the daily administration of SCF had no effect on the expansion of NK cells. The continuous infusion of IL-2 alone did result in a significant expansion of NK1.1+CD3− cells compared to mice treated with placebo or SCF. However, mice treated with both SCF and IL-2 showed an increase in the absolute number of NK cells that was more than twofold that seen with IL-2 alone, in the spleen (P ≤ .005), bone marrow (P ≤ .025), and blood (P < .05). NK cytotoxic activity against YAC-1 target cells was significantly higher for mice treated with SCF plus IL-2, compared to mice treated with IL-2 alone (P ≤ .0005). Interferon-γ (IFN-γ) production in cytokine-activated splenocytes was also greater for the SCF plus IL-2 group, over IL-2 treatment alone (P ≤ .01). The effect of SCF plus IL-2 on NK cell expansion was likely mediated via NK cell precursors, rather than mature NK cells. In summary, we provide the first evidence that SCF can significantly enhance expansion of functional NK cells induced by the prolonged administration of low dose IL-2 in vivo. Since the NK cell is a cytotoxic innate immune effector and a potent source of IFN-γ, this therapeutic strategy for NK cell expansion may serve to further enhance innate immune surveillance against malignant transformation and infection in the setting of cancer and/or immunodeficiency.

scholarly journals The Exopolysaccharide of Lactobacillus fermentum UCO-979C Is Partially Involved in Its Immunomodulatory Effect and Its Ability to Improve the Resistance against Helicobacter pylori Infection

2020 ◽  
Vol 8 (4) ◽  
pp. 479
Author(s):  
Valeria Garcia-Castillo ◽  
Guillermo Marcial ◽  
Leonardo Albarracín ◽  
Mikado Tomokiyo ◽  
Patricia Clua ◽  
...  
Keyword(s):  
Immune Response ◽  
Helicobacter Pylori ◽  
Gastric Mucosa ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Helicobacter Pylori Infection ◽  
Beneficial Effects ◽  
Ifn Γ ◽  
H Pylori

Lactobacillus fermentum UCO-979C (Lf979C) beneficially modulates the cytokine response of gastric epithelial cells and macrophages after Helicobacter pylori infection in vitro. Nevertheless, no in vivo studies were performed with this strain to confirm its beneficial immunomodulatory effects. This work evaluated whether Lf979C improves protection against H. pylori infection in mice by modulating the innate immune response. In addition, we evaluated whether its exopolysaccharide (EPS) was involved in its beneficial effects. Lf979C significantly reduced TNF-α, IL-8, and MCP-1 and augmented IFN-γ and IL-10 in the gastric mucosa of H. pylori-infected mice. The differential cytokine profile induced by Lf979C in H. pylori-infected mice correlated with an improved reduction in the pathogen gastric colonization and protection against inflammatory damage. The purified EPS of Lf979C reduced IL-8 and enhanced IL-10 levels in the gastric mucosa of infected mice, while no effect was observed for IFN-γ. This work demonstrates for the first time the in vivo ability of Lf979C to increase resistance against H. pylori infection by modulating the gastric innate immune response. In addition, we advanced knowledge of the mechanisms involved in the beneficial effects of Lf979C by demonstrating that its EPS is partially responsible for its immunomodulatory effect.

scholarly journals Modulation of the host microenvironment by a common non-oncolytic mouse virus leads to inhibition of plasmacytoma development through NK cell activation

2014 ◽  
Vol 95 (7) ◽  
pp. 1504-1509 ◽  
Author(s):  
Gaëtan Thirion ◽  
Anubha Saxena ◽  
Xavier Hulhoven ◽  
Dominique Markine-Goriaynoff ◽  
Jacques Van Snick ◽  
...  
Keyword(s):  
Cell Activation ◽  
Nk Cell ◽  
Infectious Agent ◽  
Innate Immune ◽  
Mouse Virus ◽  
Nk T Cells ◽  
Ifn Γ ◽  
Specific Stimulation ◽  
Micro Organisms

Although many cells undergo transformation, few actually develop into tumours, due to successful mechanisms of immunosurveillance. To investigate whether an infectious agent may play a role in this process, the growth of a plasmacytoma was investigated in mice infected by lactate dehydrogenase-elevating virus. Acutely infected animals were significantly protected against tumour development. The mechanisms responsible for this protection were analysed in mice deficient for relevant immune cells or molecules and after in vivo cell depletion. This protection by viral infection correlated with NK cell activation and with IFN-γ production. It might also be related to activation of NK/T-cells, although this remains to be proven formally. Therefore, our results indicated that infections with benign micro-organisms may protect the host against cancer development, through non-specific stimulation of the host's innate immune system and especially of NK cells.

scholarly journals A murine DC-SIGN homologue contributes to early host defense against Mycobacterium tuberculosis

2009 ◽  
Vol 206 (10) ◽  
pp. 2205-2220 ◽  
Author(s):  
Antoine Tanne ◽  
Bo Ma ◽  
Frédéric Boudou ◽  
Ludovic Tailleux ◽  
Hélène Botella ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Host Defense ◽  
Host Response ◽  
Bacterial Pathogen ◽  
Innate Immune ◽  
Intercellular Adhesion Molecule ◽  
Immune Recognition ◽  
Unique Contribution ◽  
Necrosis Factor

The C-type lectin dendritic cell−specific intercellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN) mediates the innate immune recognition of microbial carbohydrates. We investigated the function of this molecule in the host response to pathogens in vivo, by generating mouse lines lacking the DC-SIGN homologues SIGNR1, SIGNR3, and SIGNR5. Resistance to Mycobacterium tuberculosis was impaired only in SIGNR3-deficient animals. SIGNR3 was expressed in lung phagocytes during infection, and interacted with M. tuberculosis bacilli and mycobacterial surface glycoconjugates to induce secretion of critical host defense inflammatory cytokines, including tumor necrosis factor (TNF). SIGNR3 signaling was dependent on an intracellular tyrosine-based motif and the tyrosine kinase Syk. Thus, the mouse DC-SIGN homologue SIGNR3 makes a unique contribution to protection of the host against a pulmonary bacterial pathogen.

scholarly journals Bordetella pertussis Naturally Occurring Isolates with Altered Lipooligosaccharide Structure Fail To Fully Mature Human Dendritic Cells

2014 ◽  
Vol 83 (1) ◽  
pp. 227-238 ◽  
Author(s):  
Jolanda Brummelman ◽  
Rosanne E. Veerman ◽  
Hendrik Jan Hamstra ◽  
Anna J. M. Deuss ◽  
Tim J. Schuijt ◽  
...  
Keyword(s):  
Immune Response ◽  
Dendritic Cells ◽  
Bordetella Pertussis ◽  
Lipid A ◽  
Whooping Cough ◽  
Human Monocyte ◽  
Innate Immune ◽  
Clinical Isolates ◽  
Immune Recognition ◽  
Content Type

Bordetella pertussisis a Gram-negative bacterium and the causative agent of whooping cough. Despite high vaccination coverage, outbreaks are being increasingly reported worldwide. Possible explanations include adaptation of this pathogen, which may interfere with recognition by the innate immune system. Here, we describe innate immune recognition and responses to differentB. pertussisclinical isolates. By using HEK-Blue cells transfected with different pattern recognition receptors, we found that 3 out of 19 clinical isolates failed to activate Toll-like receptor 4 (TLR4). These findings were confirmed by using the monocytic MM6 cell line. Although incubation with high concentrations of these 3 strains resulted in significant activation of the MM6 cells, it was found to occur mainly through interaction with TLR2 and not through TLR4. When using live bacteria, these 3 strains also failed to activate TLR4 on HEK-Blue cells, and activation of MM6 cells or human monocyte-derived dendritic cells was significantly lower than activation induced by the other 16 strains. Mass spectrum analysis of the lipid A moieties from these 3 strains indicated an altered structure of this molecule. Gene sequence analysis revealed mutations in genes involved in lipid A synthesis. Findings from this study indicate thatB. pertussisisolates that do not activate TLR4 occur naturally and that this phenotype may give this bacterium an advantage in tempering the innate immune response and establishing infection. Knowledge on the strategies used by this pathogen in evading the host immune response is essential for the improvement of current vaccines or for the development of new ones.

scholarly journals The E3 ligase RNF115 regulates phagosome maturation and host response to bacterial infection

2021 ◽  
Author(s):  
Orsolya Bilkei-Gorzo ◽  
Tiaan Heunis ◽  
Daniela Fabrikova ◽  
Jose-Luis Marin Rubio ◽  
Julien Peltier ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
Immune Functions ◽  
Ubiquitin Chain ◽  
Knock Out ◽  
Phagosomal Maturation ◽  
Ifn Γ ◽  
Knock Out Mice

Phagocytosis as a key process in innate immunity and homeostasis. After uptake, newly formed phagosomes mature by acquisition of endo-lysosomal enzymes. Macrophage activation by interferon-gamma (IFN-γ) increases microbicidal activity, but delays phagosomal maturation by an unknown mechanism. Using quantitative proteomics, we show that phagosomal proteins harbour high levels of typical and atypical ubiquitin chain types. Moreover, phagosomal ubiquitylation of vesicle trafficking proteins is substantially enhanced upon IFN-γ activation of macrophages, suggesting a role in regulating phagosomal functions. Furthermore, we identified the E3 ubiquitin ligase RNF115, which is enriched on phagosomes of IFN-γ activated macrophages, as an important regulator of phagosomal maturation. Loss of RNF115 protein or ligase activity enhanced phagosomal maturation and increased cytokine responses to Staphylococcus aureus, suggesting that both innate immune signalling from the phagosome and phagolysosomal trafficking are controlled through ubiquitylation. RNF115 knock-out mice show less tissue damage in response to S. aureus infection, indicating a role of RNF115 in inflammatory responses in vivo. In conclusion, RNF115 and phagosomal ubiquitylation are important regulators of innate immune functions during bacterial infections.

scholarly journals Cutting Edge: IL-15 Costimulates the Generalized Shwartzman Reaction and Innate Immune IFN-γ Production In Vivo

2000 ◽  
Vol 164 (4) ◽  
pp. 1643-1647 ◽  
Author(s):  
Todd A. Fehniger ◽  
Haixin Yu ◽  
Megan A. Cooper ◽  
Kazuhiro Suzuki ◽  
Manisha H. Shah ◽  
...  
Keyword(s):  
Innate Immune ◽  
Cutting Edge ◽  
Shwartzman Reaction ◽  
Ifn Γ

scholarly journals Identification of Natural Target Proteins Indicates Functions of a Serralysin-Type Metalloprotease, PrtA, in Anti-Immune Mechanisms

2009 ◽  
Vol 75 (10) ◽  
pp. 3120-3126 ◽  
Author(s):  
Gabriella Felf�ldi ◽  
Judit Marokh�zi ◽  
Mikl�s K�pir� ◽  
Istv�n Venekei
Keyword(s):  
Immune Defense ◽  
Innate Immune ◽  
Coagulation Cascade ◽  
Sequence Information ◽  
Specific Substrate ◽  
Immune Recognition ◽  
Host Pathogen ◽  
Substrate Proteins

ABSTRACT Serralysins are generally thought to function as pathogenicity factors of bacteria, but so far no hard evidence of this (e.g., specific substrate proteins that are sensitive to the cleavage by these proteases) has been found. We have looked for substrate proteins to a serralysin-type proteinase, PrtA, in a natural host-pathogen molecular interaction system involving Manduca sexta and Photorhabdus luminescens. The exposure in vitro of hemolymph to PrtA digestion resulted in selective cleavage of 16 proteins, provisionally termed PAT (PrtA target) proteins. We could obtain sequence information for nine of these PrtA sensitive proteins, and by searching databases, we could identify six of them. Each has immune-related function involving every aspect of the immune defense: β-1,3 glucan recognition protein 2 (immune recognition), hemocyte aggregation inhibitor protein (HAIP), serine proteinase homolog 3, six serpin-1 variants, including serpin-1I (immune signaling and regulation), and scolexins A and B (coagulation cascade effector function). The functions of the identified PrtA substrate proteins shed new light on a possible participation of a serralysin in the virulence mechanism of a pathogen. Provided these proteins are targets of PrtA in vivo, this might represent, among others, a complex suppressive role on the innate immune response via interference with both the recognition and the elimination of the pathogen during the first, infective stage of the host-pathogen interaction. Our results also raise the possibility that the natural substrate proteins of serralysins of vertebrate pathogens might be found among the components of the innate immune system.

Sign in / Sign up

Export Citation Format

Share Document