Activation of GPR37 in macrophages confers protection against infection-induced sepsis and pain-like behaviour in mice

AbstractGPR37 was discovered more than two decades ago, but its biological functions remain poorly understood. Here we report a protective role of GPR37 in multiple models of infection and sepsis. Mice lacking Gpr37 exhibited increased death and/or hypothermia following challenge by lipopolysaccharide (LPS), Listeria bacteria, and the mouse malaria parasite Plasmodium berghei. Sepsis induced by LPS and Listeria in wild-type mice is protected by artesunate (ARU) and neuroprotectin D1 (NPD1), but the protective actions of these agents are lost in Gpr37−/− mice. Notably, we found that ARU binds to GPR37 in macrophages and promotes phagocytosis and clearance of pathogens. Moreover, ablation of macrophages potentiated infection, sepsis, and their sequelae, whereas adoptive transfer of NPD1- or ARU-primed macrophages reduced infection, sepsis, and pain-like behaviors. Our findings reveal physiological actions of ARU in host cells by activating macrophages and suggest that GPR37 agonists may help to treat sepsis, bacterial infections, and malaria.

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The role of PCSK9 in infectious diseases.

Current Medicinal Chemistry ◽

10.2174/0929867328666210714160343 ◽

2021 ◽

Vol 28 ◽

Author(s):

Laura Magnasco ◽

Chiara Sepulcri ◽

Roberta Maria Antonello ◽

Stefano Di Bella ◽

Laura Labate ◽

...

Keyword(s):

Infectious Diseases ◽

Malaria Infection ◽

Bacterial Infections ◽

Viral Infections ◽

Physiological Role ◽

Protective Role ◽

Loss Of Function ◽

Pcsk9 Inhibition ◽

Sepsis And Septic Shock

Background: In recent years, many aspects of the physiological role of PCSK9 have been elucidated, particularly regarding its role in lipid metabolism, cardiovascular risk, and its role in innate immunity. Increasing evidence is available about the involvement of PCSK9 in the pathogenesis of viral infections, mainly HCV, and the regulation of host response to bacterial infections, primarily sepsis and septic shock. Moreover, the action of PCSK9 has been investigated as a crucial step in the pathogenesis of malaria infection and disease severity. Objective: This paper aims to review the available published literature on the role of PCSK9 in a wide array of infectious diseases. Conclusion: Besides the ongoing investigation on PCSK9 inhibition among HIV-infected patients to treat HIV- and ART-related hyperlipidemia, preclinical studies indicate how PCSK9 is involved in reducing the replication of HCV. Interestingly, high plasmatic PCSK9 levels have been described in patients with sepsis. Moreover, a protective role of PCSK9 inhibition has also been proposed against dengue and SARS-CoV-2 viral infections. Finally, a loss of function in the PCSK9-encoding gene has been reported to reduce malaria infection mortality.

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Role of the β1-integrin cytoplasmic tail in mediating invasin-promoted internalization of Yersinia

Journal of Cell Science ◽

10.1242/jcs.115.13.2669 ◽

2002 ◽

Vol 115 (13) ◽

pp. 2669-2678 ◽

Cited By ~ 2

Author(s):

Anna Gustavsson ◽

Annika Armulik ◽

Cord Brakebusch ◽

Reinhard Fässler ◽

Staffan Johansson ◽

...

Keyword(s):

Marked Reduction ◽

Yersinia Pseudotuberculosis ◽

Host Cells ◽

Β1 Integrin ◽

Complex Structures ◽

Wild Type ◽

Similar Reduction ◽

Focal Complex ◽

Β1 Integrins

Invasin of Yersinia pseudotuberculosis binds to β1-integrins on host cells and triggers internalization of the bacterium. To elucidate the mechanism behind the β1-integrin-mediated internalization of Yersinia, a β1-integrin-deficient cell line, GD25, transfected with wild-type β1A, β1B or different mutants of the β1A subunit was used. Both β1A and β1B bound to invasin-expressing bacteria, but only β1A was able to mediate internalization of the bacteria. The cytoplasmic region of β1A, differing from β1B, contains two NPXY motifs surrounding a double threonine site. Exchanging the tyrosines of the two NPXYs to phenylalanines did not inhibit the uptake, whereas a marked reduction was seen when the first tyrosine (Y783) was exchanged to alanine. A similar reduction was seen when the two nearby threonines (TT788-9) were exchanged with alanines. It was also noted that cells affected in bacterial internalization exhibited reduced spreading capability when seeded onto invasin, suggesting a correlation between the internalization of invasin-expressing bacteria and invasin-induced spreading. Likewise, integrins defective in forming peripheral focal complex structures was unable to mediate uptake of invasin-expressing bacteria.

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Fluorescence-Reported Allelic Exchange Mutagenesis-Mediated Gene Deletion Indicates a Requirement for Chlamydia trachomatis Tarp during In Vivo Infectivity and Reveals a Specific Role for the C Terminus during Cellular Invasion

Infection and Immunity ◽

10.1128/iai.00841-19 ◽

2020 ◽

Vol 88 (5) ◽

Author(s):

Susmita Ghosh ◽

Elizabeth A. Ruelke ◽

Joshua C. Ferrell ◽

Maria D. Bodero ◽

Kenneth A. Fields ◽

...

Keyword(s):

Chlamydia Trachomatis ◽

Host Cell ◽

Host Cells ◽

Actin Binding ◽

Wild Type ◽

Content Type ◽

Allelic Exchange ◽

Binding Domains

ABSTRACT The translocated actin recruiting phosphoprotein (Tarp) is a multidomain type III secreted effector used by Chlamydia trachomatis. In aggregate, existing data suggest a role of this effector in initiating new infections. As new genetic tools began to emerge to study chlamydial genes in vivo, we speculated as to what degree Tarp function contributes to Chlamydia’s ability to parasitize mammalian host cells. To address this question, we generated a complete tarP deletion mutant using the fluorescence-reported allelic exchange mutagenesis (FRAEM) technique and complemented the mutant in trans with wild-type tarP or mutant tarP alleles engineered to harbor in-frame domain deletions. We provide evidence for the significant role of Tarp in C. trachomatis invasion of host cells. Complementation studies indicate that the C-terminal filamentous actin (F-actin)-binding domains are responsible for Tarp-mediated invasion efficiency. Wild-type C. trachomatis entry into HeLa cells resulted in host cell shape changes, whereas the tarP mutant did not. Finally, using a novel cis complementation approach, C. trachomatis lacking tarP demonstrated significant attenuation in a murine genital tract infection model. Together, these data provide definitive genetic evidence for the critical role of the Tarp F-actin-binding domains in host cell invasion and for the Tarp effector as a bona fide C. trachomatis virulence factor.

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Susceptibility to Entamoeba histolytica intestinal infection is related to reduction in natural killer T-lymphocytes in C57BL/6 mice

Infectious Disease Reports ◽

10.4081/idr.2012.e27 ◽

2012 ◽

Vol 4 (1) ◽

pp. 27 ◽

Cited By ~ 3

Author(s):

Fabrício M.S. Oliveira ◽

Bernardo C. Horta ◽

Luana O. Prata ◽

Andrezza F. Santiago ◽

Andréa C. Alves ◽

...

Keyword(s):

T Lymphocytes ◽

Natural Killer ◽

Entamoeba Histolytica ◽

Protective Role ◽

Amoebic Liver Abscess ◽

Wild Type ◽

Quantitative Analyses ◽

Cd1 Mice ◽

Natural Killer T

Entamoeba histolytica is a protozoan that causes amoebiasis. Recent studies demonstrated that natural killer T lymphocytes (NKT) are critical for preventing the development of amoebic liver abscess. In spite of that, there are only a handful of studies in the area. Herein, we explored the role of NKT cells in E. histolytica infection using C57BL/6 wild-type and CD1-/- mice. Animals were inoculated with E. histolytica and sacrificed 48 hours later to collect caecum samples that were used for quantitative analyses of lesions, trophozoites, NK1.1+ T lymphocytes and expression of the mucus protein MUC-2 by immunohistochemistry technique. Quantitative analyses confirmed that the frequency of NK1.1+ T cells was significantly lower in samples from C57BL/6 CD1-/- mice as compared to their wild type (WT) counterparts. The extension of necrotic mucosa was larger and the number of trophozoites higher in Entamoeba (Eh)-infected CD1-/- mice when compared with Eh-infected WT mice. In mice from both groups, noninfected (CTRL) and Eh-infected CD1-/-, there was a reduction in the thickness of the caecal mucosa and in the MUC-2-stained area in comparison with CTRL- and Eh-WT mice. Our results showed that NKT lymphocytes contribute to resistance against Entamoeba histolytica infection and to the control of inflammation in the colitis induced by infection. The presence of a normal epithelial layer containing appropriate levels of mucus had also a protective role against infection.

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OmpD but not OmpC is involved in adherence ofSalmonella entericaserovar Typhimurium to human cells

Canadian Journal of Microbiology ◽

10.1139/w04-056 ◽

2004 ◽

Vol 50 (9) ◽

pp. 719-727 ◽

Cited By ~ 17

Author(s):

Bochiwe Hara-Kaonga ◽

Thomas G Pistole

Keyword(s):

Epithelial Cells ◽

Intestinal Epithelial Cells ◽

Human Cells ◽

Host Cells ◽

Intestinal Epithelial ◽

Wild Type ◽

Human Macrophages ◽

Significant Difference ◽

Serovar Typhimurium

Conflicting reports exist regarding the role of porins OmpC and OmpD in infections due to Salmonella enterica serovar Typhimurium. This study investigated the role of these porins in bacterial adherence to human macrophages and intestinal epithelial cells. ompC and ompD mutant strains were created by transposon mutagenesis using P22-mediated transduction of Tn10 and Tn5 insertions, respectively, into wild-type strain 14028. Fluorescein-labeled wild-type and mutant bacteria were incubated with host cells at various bacteria to cell ratios for 1 h at 37 °C and analyzed by flow cytometry. The mean fluorescence intensity of cells with associated wild-type and mutant bacteria was used to estimate the number of bacteria bound per host cell. Adherence was also measured by fluorescence microscopy. Neither assay showed a significant difference in binding of the ompC mutant and wild-type strains to the human cells. In contrast, the ompD mutant exhibited lowered binding to both cell types. Our findings suggest that OmpD but not OmpC is involved in the recognition of Salmonella serovar Typhimurium by human macrophages and intestinal epithelial cells.Key words: Salmonella, adherence, porins, intestinal epithelial cells, macrophage.

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CRISPR-Cas9 Mediated RNase L Knockout Regulates Cellular Function of PK-15 Cells and Increases PRV Replication

BioMed Research International ◽

10.1155/2019/7398208 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Chao Sui ◽

Dandan Jiang ◽

Xiangju Wu ◽

Xiaoyan Cong ◽

Feng Li ◽

...

Keyword(s):

Cell Line ◽

Gene Editing ◽

Rna Degradation ◽

Type I ◽

Rnase L ◽

Agarose Gel Electrophoresis ◽

Biological Functions ◽

Wild Type ◽

Induction Of Apoptosis

Ribonuclease L (RNase L) is an important antiviral endoribonuclease regulated by type I IFN. RNase L is activated by viral infection and dsRNA. Because the role of swine RNase L (sRNase L) is not fully understood, in this study, we generated a sRNase L knockout PK-15 (KO-PK) cell line through the CRISPR/Cas9 gene editing system to evaluate the function of sRNase L. After transfection with CRISPR-Cas9 followed by selection using puromycin, sRNase L knockout in PK-15 cells was further validated by agarose gel electrophoresis, DNA sequencing, and Western blotting. The sRNase L KO-PK cells failed to trigger RNA degradation and induced less apoptosis than the parental PK-15 cells after transfected with poly (I: C). Furthermore, the levels of ISGs mRNA in sRNase L KO-PK cells were higher than those in the parental PK-15 cells after treated with poly (I: C). Finally, both wild type and attenuated pseudorabies viruses (PRV) replicated more efficiently in sRNase L KO-PK cells than the parental PK-15 cells. Taken together, these findings suggest that sRNase L has multiple biological functions including cellular single-stranded RNA degradation, induction of apoptosis, downregulation of transcript levels of ISGs, and antiviral activity against PRV. The sRNase L KO-PK cell line will be a valuable tool for studying functions of sRNase L as well as for producing PRV attenuated vaccine.

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Role of Adhesin Release for Mucosal Colonization by a Bacterial Pathogen

Journal of Experimental Medicine ◽

10.1084/jem.20021153 ◽

2003 ◽

Vol 197 (6) ◽

pp. 735-742 ◽

Cited By ~ 81

Author(s):

Loïc Coutte ◽

Sylvie Alonso ◽

Nathalie Reveneau ◽

Eve Willery ◽

Brigitte Quatannens ◽

...

Keyword(s):

Respiratory Tract ◽

Bacterial Pathogen ◽

Host Cells ◽

Wild Type ◽

Early Step ◽

Bacterial Surface ◽

Extracellular Milieu ◽

Wild Type Parent

Pathogen attachment is a crucial early step in mucosal infections. This step is mediated by important virulence factors called adhesins. To exert these functions, adhesins are typically surface-exposed, although, surprisingly, some are also released into the extracellular milieu, the relevance of which has previously not been studied. To address the role of adhesin release in pathogenesis, we used Bordetella pertussis as a model, since its major adhesin, filamentous hemagglutinin (FHA), partitions between the bacterial surface and the extracellular milieu. FHA release depends on its maturation by the specific B. pertussis protease SphB1. We constructed SphB1-deficient mutants and found that they were strongly affected in their ability to colonize the mouse respiratory tract, although they adhered even better to host cells in vitro than their wild-type parent strain. The defect in colonization could be overcome by prior nasal instillation of purified FHA or by coinfection with FHA-releasing B. pertussis strains, but not with SphB1-producing FHA-deficient strains, ruling out a nonspecific effect of SphB1. These results indicate that the release of FHA is important for colonization, as it may facilitate the dispersal of bacteria from microcolonies and the binding to new sites in the respiratory tract.

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Legionella pneumophila Entry GenertxA Is Involved in Virulence

Infection and Immunity ◽

10.1128/iai.69.1.508-517.2001 ◽

2001 ◽

Vol 69 (1) ◽

pp. 508-517 ◽

Cited By ~ 74

Author(s):

Suat L. G. Cirillo ◽

Luiz E. Bermudez ◽

Sahar H. El-Etr ◽

Gerald E. Duhamel ◽

Jeffrey D. Cirillo

Keyword(s):

Legionella Pneumophila ◽

Bacterial Species ◽

Host Cells ◽

Intracellular Pathogen ◽

Wild Type ◽

Integrin Receptors ◽

Legionnaires Disease ◽

Cell Spread ◽

Gain Access

ABSTRACT Successful parasitism of host cells by intracellular pathogens involves adherence, entry, survival, intracellular replication, and cell-to-cell spread. Our laboratory has been examining the role of early events, adherence and entry, in the pathogenesis of the facultative intracellular pathogen Legionella pneumophila. Currently, the mechanisms used by L. pneumophila to gain access to the intracellular environment are not well understood. We have recently isolated three loci, designated enh1,enh2, and enh3, that are involved in the ability of L. pneumophila to enter host cells. One of the genes present in the enh1 locus, rtxA, is homologous to repeats in structural toxin genes (RTX) found in many bacterial pathogens. RTX proteins from other bacterial species are commonly cytotoxic, and some of them have been shown to bind to β2 integrin receptors. In the current study, we demonstrate that the L. pneumophila rtxA gene is involved in adherence, cytotoxicity, and pore formation in addition to its role in entry. Furthermore, an rtxA mutant does not replicate as well as wild-type L. pneumophila in monocytes and is less virulent in mice. Thus, we conclude that the entry genertxA is an important virulence determinant in L. pneumophila and is likely to be critical for the production of Legionnaires' disease in humans.

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Attenuated Endocytosis and Toxicity of a Mutant Cholera Toxin with Decreased Ability To Cluster Ganglioside GM1 Molecules

Infection and Immunity ◽

10.1128/iai.01286-07 ◽

2008 ◽

Vol 76 (4) ◽

pp. 1476-1484 ◽

Cited By ~ 39

Author(s):

Anne A. Wolf ◽

Michael G. Jobling ◽

David E. Saslowsky ◽

Eli Kern ◽

Kimberly R. Drake ◽

...

Keyword(s):

Cholera Toxin ◽

Host Cells ◽

Wild Type ◽

Intact Cells ◽

B Subunit ◽

Binding Pockets ◽

Detergent Resistant Membranes ◽

Toxin Uptake ◽

Chimeric Toxins

ABSTRACT Cholera toxin (CT) moves from the plasma membrane (PM) of host cells to the endoplasmic reticulum (ER) by binding to the lipid raft ganglioside GM1. The homopentomeric B-subunit of the toxin can bind up to five GM1 molecules at once. Here, we examined the role of polyvalent binding of GM1 in CT action by producing chimeric CTs that had B-subunits with only one or two normal binding pockets for GM1. The chimeric toxins had attenuated affinity for binding to host cell PM, as expected. Nevertheless, like wild-type (wt) CT, the CT chimeras induced toxicity, fractionated with detergent-resistant membranes extracted from toxin-treated cells, displayed restricted diffusion in the plane of the PM in intact cells, and remained bound to GM1 when they were immunoprecipitated. Thus, binding normally to two or perhaps only one GM1 molecule is sufficient for association with lipid rafts in the PM and toxin action. The chimeric toxins, however, were much less potent than wt toxin, and they entered the cell by endocytosis more slowly, suggesting that clustering of GM1 molecules by the B-subunit enhances the efficiency of toxin uptake and perhaps also trafficking to the ER.

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Revisiting the role of Toxoplasma gondii ERK7 in the maintenance and stability of the apical complex

10.1101/2021.03.22.436543 ◽

2021 ◽

Author(s):

Dominique Soldati-Favre ◽

Nicolas Dos Santos Pacheco ◽

Nicolò Tosetti ◽

Aarti Krishnan ◽

Romuald Haase

Keyword(s):

Toxoplasma Gondii ◽

Comparative Proteomics ◽

Host Cells ◽

Wild Type ◽

Proteomics Analysis ◽

Polar Ring ◽

Intracellular Parasites ◽

Apical Complex ◽

Microneme Proteins

Toxoplasma gondii ERK7 is known to contribute to the integrity of the apical complex and to be involved only in the final step of the conoid biogenesis. In the absence of ERK7, mature parasites lose their conoid complex and are unable to glide, invade or egress from host cells. In contrast to a previous report, we show here that depletion of ERK7 phenocopies the depletion of the apical cap proteins AC9 or AC10. The absence of ERK7 leads to the loss of the apical polar ring, the disorganization of the basket of subpellicular microtubules and an impairment in micronemes secretion. Ultra-expansion microscopy (U-ExM) coupled to NHS-Ester staining on intracellular parasites offers an unprecedented level of resolution and highlights the disorganization of the rhoptries as well as the dilated plasma membrane at the apical pole in the absence of ERK7. Comparative proteomics analysis of wild-type and ERK7 or AC9 depleted parasites led to the disappearance of known, predicted, as well as putative novel components of the apical complex. In contrast, the absence of ERK7 led to an accumulation of microneme proteins, resulting from the defect in exocytosis of the organelles.

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