CXCR2 deficient mice display macrophage-dependent exaggerated acute inflammatory responses

Abstract CXCR2 is an essential regulator of neutrophil recruitment to inflamed and damaged sites and plays prominent roles in inflammatory pathologies and cancer. It has therefore been highlighted as an important therapeutic target. However the success of the therapeutic targeting of CXCR2 is threatened by our relative lack of knowledge of its precise in vivo mode of action. Here we demonstrate that CXCR2-deficient mice display a counterintuitive transient exaggerated inflammatory response to cutaneous and peritoneal inflammatory stimuli. In both situations, this is associated with reduced expression of cytokines associated with the resolution of the inflammatory response and an increase in macrophage accumulation at inflamed sites. Analysis using neutrophil depletion strategies indicates that this is a consequence of impaired recruitment of a non-neutrophilic CXCR2 positive leukocyte population. We suggest that these cells may be myeloid derived suppressor cells. Our data therefore reveal novel and previously unanticipated roles for CXCR2 in the orchestration of the inflammatory response.

Download Full-text

Modulation of Immune Complex–induced Inflammation In Vivo by the Coordinate Expression of Activation and Inhibitory Fc Receptors

Journal of Experimental Medicine ◽

10.1084/jem.189.1.179 ◽

1999 ◽

Vol 189 (1) ◽

pp. 179-186 ◽

Cited By ~ 295

Author(s):

Raphael Clynes ◽

Jay S. Maizes ◽

Rodolphe Guinamard ◽

Masao Ono ◽

Toshiyuki Takai ◽

...

Keyword(s):

Inflammatory Response ◽

Immune Complexes ◽

Inflammatory Responses ◽

Fc Receptors ◽

Inflammatory Cells ◽

Neutrophil Infiltration ◽

Calcium Flux ◽

Deficient Mice

Autoantibodies and immune complexes are major pathogenic factors in autoimmune injury, responsible for initiation of the inflammatory cascade and its resulting tissue damage. This activation results from the interaction of immunoglobulin (Ig)G Fc receptors containing an activation motif (ITAM) with immune complexes (ICs) and cytotoxic autoantibodies which initiates and propagates an inflammatory response. In vitro, this pathway can be interrupted by coligation to FcγRIIB, an IgG Fc receptor containing an inhibitory motif (ITIM). In this report, we describe the in vivo consequences of FcγRII deficiency in the inflammatory response using a mouse model of IC alveolitis. At subthreshold concentrations of ICs that fail to elicit inflammatory responses in wild-type mice, FcγRII-deficient mice developed robust inflammatory responses characterized by increased hemorrhage, edema, and neutrophil infiltration. Bronchoalveolar fluids from FcγRII−/− stimulated mice contain higher levels of tumor necrosis factor and chemotactic activity, suggesting that FcγRII deficiency lowers the threshold of IC stimulation of resident cells such as the alveolar macrophage. In contrast, complement- and complement receptor–deficient mice develop normal inflammatory responses to suprathreshold levels of ICs, while FcRγ−/− mice are completely protected from inflammatory injury. An inhibitory role for FcγRII on macrophages is demonstrated by analysis of FcγRII−/− macrophages which show greater phagocytic and calcium flux responses upon FcγRIII engagement. These data reveal contrasting roles for the cellular receptors for IgG on inflammatory cells, providing a regulatory mechanism for setting thresholds for IC sensitivity based on the ratio of ITIM to ITAM FcγR expression. Exploiting the FcγRII inhibitory pathway could thus provide a new therapeutic approach for modulating antibody-triggered inflammation.

Download Full-text

CLEC5A-Mediated Enhancement of the Inflammatory Response in Myeloid Cells Contributes to Influenza Virus Pathogenicity In Vivo

Journal of Virology ◽

10.1128/jvi.01813-16 ◽

2016 ◽

Vol 91 (1) ◽

Cited By ~ 15

Author(s):

Ooiean Teng ◽

Szu-Ting Chen ◽

Tsui-Ling Hsu ◽

Sin Fun Sia ◽

Suzanne Cole ◽

...

Keyword(s):

Inflammatory Response ◽

Proinflammatory Cytokines ◽

Inflammatory Responses ◽

Myeloid Cells ◽

Influenza Viruses ◽

Host Responses ◽

Wild Type ◽

Survival Difference ◽

Deficient Mice

ABSTRACT Human infections with influenza viruses exhibit mild to severe clinical outcomes as a result of complex virus-host interactions. Induction of inflammatory mediators via pattern recognition receptors may dictate subsequent host responses for pathogen clearance and tissue damage. We identified that human C-type lectin domain family 5 member A (CLEC5A) interacts with the hemagglutinin protein of influenza viruses expressed on lentiviral pseudoparticles through lectin screening. Silencing CLEC5A gene expression, blocking influenza-CLEC5A interactions with anti-CLEC5A antibodies, or dampening CLEC5A-mediated signaling using a spleen tyrosine kinase inhibitor consistently reduced the levels of proinflammatory cytokines produced by human macrophages without affecting the replication of influenza A viruses of different subtypes. Infection of bone marrow-derived macrophages from CLEC5A-deficient mice showed reduced levels of tumor necrosis factor alpha (TNF-α) and IP-10 but elevated alpha interferon (IFN-α) compared to those of wild-type mice. The heightened type I IFN response in the macrophages of CLEC5A-deficient mice was associated with upregulated TLR3 mRNA after treatment with double-stranded RNA. Upon lethal challenges with a recombinant H5N1 virus, CLEC5A-deficient mice showed reduced levels of proinflammatory cytokines, decreased immune cell infiltration in the lungs, and improved survival compared to the wild-type mice, despite comparable viral loads noted throughout the course of infection. The survival difference was more prominent at a lower dose of inoculum. Our results suggest that CLEC5A-mediated enhancement of the inflammatory response in myeloid cells contributes to influenza pathogenicity in vivo and may be considered a therapeutic target in combination with effective antivirals. Well-orchestrated host responses together with effective viral clearance are critical for optimal clinical outcome after influenza infections. IMPORTANCE Multiple pattern recognition receptors work in synergy to sense viral RNA or proteins synthesized during influenza replication and mediate host responses for viral control. Well-orchestrated host responses may help to maintain the inflammatory response to minimize tissue damage while inducing an effective adaptive immune response for viral clearance. We identified that CLEC5A, a C-type lectin receptor which has previously been reported to mediate flavivirus-induced inflammatory responses, enhanced induction of proinflammatory cytokines and chemokines in myeloid cells after influenza infections. CLEC5A-deficient mice infected with influenza virus showed reduced inflammation in the lungs and improved survival compared to that of the wild-type mice despite comparable viral loads. The survival difference was more prominent at a lower dose of inoculum. Collectively, our results suggest that dampening CLEC5A-mediated inflammatory responses in myeloid cells reduces immunopathogenesis after influenza infections.

Download Full-text

Impaired hepatic insulin signalling in PON2-deficient mice: a novel role for the PON2/apoE axis on the macrophage inflammatory response

Biochemical Journal ◽

10.1042/bj20101891 ◽

2011 ◽

Vol 436 (1) ◽

pp. 91-100 ◽

Cited By ~ 16

Author(s):

Noam Bourquard ◽

Carey J. Ng ◽

Srinivasa T. Reddy

Keyword(s):

Oxidative Stress ◽

Inflammatory Response ◽

Insulin Signalling ◽

Antioxidant Properties ◽

Hepatic Glucose Metabolism ◽

Hepatic Glucose ◽

Activated Macrophage ◽

Inflammatory Stimuli ◽

Deficient Mice

Hepatic glucose metabolism is strongly influenced by oxidative stress and pro-inflammatory stimuli. PON2 (paraoxonase 2), an enzyme with undefined antioxidant properties, protects against atherosclerosis. PON2-deficient (PON2-def) mice have elevated hepatic oxidative stress coupled with an exacerbated inflammatory response from PON2-deficient macrophages. In the present paper, we demonstrate that PON2 deficiency is associated with inhibitory insulin-mediated phosphorylation of hepatic IRS-1 (insulin receptor substrate-1). Unexpectedly, we observed a marked improvement in the hepatic IRS-1 phosphorylation state in PON2-def/apoE (apolipoprotein E)−/− mice, relative to apoE−/− mice. Factors secreted from activated macrophage cultures derived from PON2-def and PON2-def/apoE−/− mice are sufficient to modulate insulin signalling in cultured hepatocytes in a manner similar to that observed in vivo. We show that the protective effect on insulin signalling in PON2-def/apoE−/− mice is directly associated with altered production of macrophage pro-inflammatory mediators, but not elevated intracellular oxidative stress levels. We further present evidence that modulation of the macrophage inflammatory response in PON2-def/apoE−/− mice is mediated by a shift in the balance of NO and ONOO− (peroxynitrite) formation. Our results demonstrate that PON2 plays an important role in hepatic insulin signalling and underscores the influence of macrophage-mediated inflammatory response on hepatic insulin sensitivity.

Download Full-text

Blocking Migration of Polymorphonuclear Myeloid-Derived Suppressor Cells Inhibits Mouse Melanoma Progression

Cancers ◽

10.3390/cancers13040726 ◽

2021 ◽

Vol 13 (4) ◽

pp. 726

Author(s):

Christopher Groth ◽

Ludovica Arpinati ◽

Merav E. Shaul ◽

Nina Winkler ◽

Klara Diester ◽

...

Keyword(s):

Tumor Progression ◽

Checkpoint Inhibitors ◽

Suppressor Cells ◽

Receptor Expression ◽

Myeloid Derived Suppressor Cells ◽

Melanoma Progression ◽

Relative Contribution ◽

Immunosuppressive Tumor Microenvironment ◽

Metastatic Sites

Background: Despite recent improvement in the treatment of malignant melanoma by immune-checkpoint inhibitors, the disease can progress due to an immunosuppressive tumor microenvironment (TME) mainly represented by myeloid-derived suppressor cells (MDSC). However, the relative contribution of the polymorphonuclear (PMN) and monocytic (M) MDSC subsets to melanoma progression is not clear. Here, we compared both subsets regarding their immunosuppressive capacity and recruitment mechanisms. Furthermore, we inhibited PMN-MDSC migration in vivo to determine its effect on tumor progression. Methods: Using the RET transgenic melanoma mouse model, we investigated the immunosuppressive function of MDSC subsets and chemokine receptor expression on these cells. The effect of CXCR2 inhibition on PMN-MDSC migration and tumor progression was studied in RET transgenic mice and in C57BL/6 mice after surgical resection of primary melanomas. Results: Immunosuppressive capacity of intratumoral M- and PMN-MDSC was comparable in melanoma bearing mice. Anti-CXCR2 therapy prolonged survival of these mice and decreased the occurrence of distant metastasis. Furthermore, this therapy reduced the infiltration of melanoma lesions and pre-metastatic sites with PMN-MDSC that was associated with the accumulation of natural killer (NK) cells. Conclusions: We provide evidence for the tumor−promoting properties of PMN-MDSC as well as for the anti-tumor effects upon their targeting in melanoma bearing mice.

Download Full-text

A Comparative Transcriptome Analysis of Human and Porcine Choroid Plexus Cells in Response to Streptococcus suis Serotype 2 Infection Points to a Role of Hypoxia

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.639620 ◽

2021 ◽

Vol 11 ◽

Author(s):

Alexa N. Lauer ◽

Rene Scholtysik ◽

Andreas Beineke ◽

Christoph Georg Baums ◽

Kristin Klose ◽

...

Keyword(s):

Epithelial Cells ◽

Inflammatory Response ◽

Choroid Plexus ◽

Cellular Proliferation ◽

Inflammatory Responses ◽

Streptococcus Suis ◽

Gene Set Enrichment Analysis ◽

Rna Seq

Streptococcus suis (S. suis) is an important opportunistic pathogen, which can cause septicemia and meningitis in pigs and humans. Previous in vivo observations in S. suis-infected pigs revealed lesions at the choroid plexus (CP). In vitro experiments with primary porcine CP epithelial cells (PCPEC) and human CP epithelial papilloma (HIBCPP) cells demonstrated that S. suis can invade and traverse the CP epithelium, and that the CP contributes to the inflammatory response via cytokine expression. Here, next generation sequencing (RNA-seq) was used to compare global transcriptome profiles of PCPEC and HIBCPP cells challenged with S. suis serotype (ST) 2 infected in vitro, and of pigs infected in vivo. Identified differentially expressed genes (DEGs) were, amongst others, involved in inflammatory responses and hypoxia. The RNA-seq data were validated via quantitative PCR of selected DEGs. Employing Gene Set Enrichment Analysis (GSEA), 18, 28, and 21 enriched hallmark gene sets (GSs) were identified for infected HIBCPP cells, PCPEC, and in the CP of pigs suffering from S. suis ST2 meningitis, respectively, of which eight GSs overlapped between the three different sample sets. The majority of these GSs are involved in cellular signaling and pathways, immune response, and development, including inflammatory response and hypoxia. In contrast, suppressed GSs observed during in vitro and in vivo S. suis ST2 infections included those, which were involved in cellular proliferation and metabolic processes. This study suggests that similar cellular processes occur in infected human and porcine CP epithelial cells, especially in terms of inflammatory response.

Download Full-text

Thrombin-activatable procarboxypeptidase B regulates activated complement C5a in vivo

Blood ◽

10.1182/blood-2006-03-012567 ◽

2006 ◽

Vol 109 (5) ◽

pp. 1992-1997 ◽

Cited By ~ 38

Author(s):

Toshihiko Nishimura ◽

Timothy Myles ◽

Adrian M. Piliposky ◽

Peter N. Kao ◽

Gerald J. Berry ◽

...

Keyword(s):

Beneficial Effect ◽

Inflammatory Mediators ◽

Protein C ◽

Inflammatory Responses ◽

Cell Counts ◽

Fibrinolysis Inhibitor ◽

Complement C5a ◽

Homeostatic Response ◽

Deficient Mice

Abstract Plasma procarboxypeptidase B (proCPB) is activated by the endothelial thrombin-prothrombomodulin complex. Activated (CPB) functions as a fibrinolysis inhibitor, but it may play a broader role by inactivating inflammatory mediators. To test this hypothesis, C5a-induced alveolitis was studied in wild-type (WT) and proCPB-deficient mice (proCPB−/−). C5a-induced alveolitis, as measured by cell counts and total protein contents in bronchoalveolar lavage fluids, was markedly enhanced in the proCPB−/− mice. E229K thrombin, a thrombin mutant with minimal clotting activity but retaining its ability to activate protein C and proCPB, attenuated C5a-induced alveolitis in WT but not in proCPB−/− mice, indicating that its beneficial effect is mediated primarily by its activation of proCPB. Lung tissue histology confirmed these cellular inflammatory responses. Delayed administration of E229K thrombin after the C5a instillation was ineffective in reducing alveolitis in WT mice, suggesting that the beneficial effect of E229K thrombin is due to the direct inhibition of C5a by CPB. Our studies show that thrombin-activatable proCPB, in addition to its role in fibrinolysis, has intrinsic anti-inflammatory functions. Its activation, along with protein C, by the endothelial thrombin-TM complex represents a homeostatic response to counteract the inflammatory mediators generated at the site of vascular injury.

Download Full-text

Disruption of γ-Glutamyl Leukotrienase Results in Disruption of Leukotriene D4 Synthesis In Vivo and Attenuation of the Acute Inflammatory Response

Molecular and Cellular Biology ◽

10.1128/mcb.21.16.5389-5395.2001 ◽

2001 ◽

Vol 21 (16) ◽

pp. 5389-5395 ◽

Cited By ~ 41

Author(s):

Zheng-Zheng Shi ◽

Bing Han ◽

Geetha M. Habib ◽

Martin M. Matzuk ◽

Michael W. Lieberman

Keyword(s):

Inflammatory Response ◽

Double Mutant ◽

Inflammatory Process ◽

Embryonic Stem ◽

Acute Inflammatory Response ◽

Leukotriene D4 ◽

Glutamyl Transpeptidase ◽

Targeting Strategy ◽

Deficient Mice

ABSTRACT To study the function of γ-glutamyl leukotrienase (GGL), a newly identified member of the γ-glutamyl transpeptidase (GGT) family, we generated null mutations in GGL (GGLtm1) and in both GGL and GGT (GGLtm1-GGTtm1) by a serial targeting strategy using embryonic stem cells. Mice homozygous for GGLtm1 show no obvious phenotypic changes. Mice deficient in both GGT and GGL have a phenotype similar to the GGT-deficient mice, but ∼70% of these mice die before 4 weeks of age, at least 2 months earlier than mice deficient only in GGT. These double-mutant mice are unable to cleave leukotriene C4 (LTC4) to LTD4, indicating that this conversion is completely dependent on the two enzymes, and in some organs (spleen and uterus) deletion of GGL alone abolished more than 90% of this activity. In an experimental model of peritonitis, GGL alone is responsible for the generation of peritoneal LTD4. Further, during the development of peritonitis, GGL-deficient mice show an attenuation in neutrophil recruitment but not of plasma protein influx. These findings demonstrate an important role for GGL in the inflammatory response and suggest that LTC4 and LTD4 have distinctly different functions in the inflammatory process.

Download Full-text

Disruption of endothelial Pfkfb3 ameliorates diet-induced murine insulin resistance

Journal of Endocrinology ◽

10.1530/joe-20-0524 ◽

2021 ◽

Author(s):

Qiuhua Yang ◽

Jiean Xu ◽

Qian Ma ◽

Zhiping Liu ◽

Yaqi Zhou ◽

...

Keyword(s):

Insulin Resistance ◽

Endothelial Cells ◽

High Fat Diet ◽

Inflammatory Responses ◽

Critical Role ◽

Endothelial Inflammation ◽

Glucose Clearance ◽

Deficient Mice

Overnutrition-induced endothelial inflammation plays a crucial role in high fat diet (HFD)-induced insulin resistance in animals. Endothelial glycolysis plays a critical role in endothelial inflammation and proliferation, but its role in diet-induced endothelial inflammation and subsequent insulin resistance has not been elucidated. PFKFB3 is a critical glycolytic regulator, and its increased expression has been observed in adipose vascular endothelium of C57BL/6J mice fed with HFD in vivo, and in palmitate (PA)-treated primary human adipose microvascular endothelial cells (HAMECs) in vitro. We generated mice with Pfkfb3 deficiency selective for endothelial cells to examine the effect of endothelial Pfkfb3 in endothelial inflammation in metabolic organs and in the development of HFD-induced insulin resistance. EC Pfkfb3-deficient mice exhibited mitigated HFD-induced insulin resistance, including decreased body weight and fat mass, improved glucose clearance and insulin sensitivity, and alleviated adiposity and hepatic steatosis. Mechanistically, cultured PFKFB3 knockdown HAMECs showed decreased NF-κB activation induced by PA, and consequent suppressed adhesion molecule expression and monocyte adhesion. Taken together, these results demonstrate that increased endothelial PFKFB3 expression promotes diet-induced inflammatory responses and subsequent insulin resistance, suggesting that endothelial metabolic alteration plays an important role in the development of insulin resistance.

Download Full-text

A Role of Plasminogen in Atherosclerosis and Restenosis Models in Mice

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615544 ◽

1999 ◽

Vol 82 (S 01) ◽

pp. 4-7 ◽

Cited By ~ 14

Author(s):

Victoria A. Ploplis ◽

Steven Busuttil ◽

Peter Carmeliet ◽

Desire Collen ◽

Edward F. Plow

Keyword(s):

Vessel Wall ◽

Inflammatory Responses ◽

Leukocyte Migration ◽

Early Event ◽

Macrophage Migration ◽

Murine Models ◽

Response Models ◽

Deficient Mice

SummaryIn addition to its preeminent role in fibrinolysis, the plasminogen system is believed to play a key role in mediating cell migration. Leukocyte migration into the vessel wall is a key and early event in the development of the lesions of atherosclerosis and restenosis, pathologies which may be viewed as specific examples of vascular inflammatory responses. The development of mice in which the plasminogen gene has been inactivated affords an opportunity to test the contribution of plasminogen in leukocyte migration during in vivo. This article summarizes recent studies conducted in murine models of the inflammatory repsonse, restenosis and atherosclerosis in which leukocyte migration, and in particular monocyte/macrophage migration, has been evaluated in plasminogen-deficient mice. Recruitment of these cells through the vessel wall in inflammatory response models and into the vessel wall in restenosis and transplant atherosclerosis models is substantially blunted. These data implicate plasminogen in the migration of leukocytes in these murine models. With the numerous correlations between components and/or activation of the plasminogen system in restenosis and atherosclerosis, these results also support a role of plasminogen in the corresponding human pathologies.

Download Full-text