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Salmonella enterica is a common source of food and water-borne infections, causing a wide range of clinical ailments in both human and animal hosts. Immunity to Salmonella involves an interplay between different immune responses, which are rapidly initiated to control bacterial burden. However, Salmonella has developed several strategies to evade and modulate the host immune responses. In this sense, the main knowledge about the pathogenicity of this bacterium has been obtained by the study of mouse models with non-typhoidal serovars. However, this knowledge is not representative of all the pathologies caused by non-typhoidal serovars in the human. Here we review the most important features of typhoidal and non-typhoidal serovars and the diseases they cause in the human host, describing the virulence mechanisms used by these pathogens that have been identified in different models of infection.
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OBJECTIVE AND DESIGN: Respiratory syncytial virus (RSV) is the major cause of infection in children up to 2 years old and reinfection is very common among patients. Tissue damage in the lung caused by RSV leads to an immune response and infected cells activate multiple signaling pathways and massive production of inflammatory mediators like macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine. Therefore, we sought to investigate the role of MIF during RSV infection in macrophages. METHODS: We evaluated MIF expression in BALB/c mice-derived macrophages stimulated with different concentrations of RSV by Western blot and real-time PCR. Additionally, different inhibitors of signaling pathways and ROS were used to evaluate their importance for MIF expression. Furthermore, we used a specific MIF inhibitor, ISO-1, to evaluate the role of MIF in viral clearance and in RSV-induced TNF-α, MCP-1 and IL-10 release from macrophages. RESULTS: We showed that RSV induces MIF expression dependently of ROS, 5-LOX, COX and PI3K activation. Moreover, viral replication is necessary for RSV-triggered MIF expression. Differently, p38 MAPK in only partially needed for RSV-induced MIF expression. In addition, MIF is important for the release of TNF-α, MCP-1 and IL-10 triggered by RSV in macrophages. CONCLUSIONS: In conclusion, we demonstrate that MIF is expressed during RSV infection and controls the release of pro-inflammatory cytokines from macrophages in an in vitro model.
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Citocinas/imunologia , Fatores Inibidores da Migração de Macrófagos/imunologia , Macrófagos/imunologia , Infecções por Vírus Respiratório Sincicial/imunologia , Animais , Líquido da Lavagem Broncoalveolar , Fatores Inibidores da Migração de Macrófagos/genética , Macrófagos/virologia , Camundongos Endogâmicos BALB C , Transdução de Sinais , Carga ViralRESUMO
Respiratory syncytial virus (RSV) is a major cause of diseases of the respiratory tract in young children and babies, being mainly associated with bronchiolitis. RSV infection occurs primarily in pulmonary epithelial cells and, once infection is established, an immune response is triggered and neutrophils are recruited. In this study, we investigated the mechanisms underlying NET production induced by RSV. We show that RSV induced the classical ROS-dependent NETosis in human neutrophils and that RSV was trapped in DNA lattices coated with NE and MPO. NETosis induction by RSV was dependent on signaling by PI3K/AKT, ERK and p38 MAPK and required histone citrullination by PAD-4. In addition, RIPK1, RIPK3 and MLKL were essential to RSV-induced NETosis. MLKL was also necessary to neutrophil necrosis triggered by the virus, likely promoting membrane-disrupting pores, leading to neutrophil lysis and NET extrusion. Finally, we found that RSV infection of alveolar epithelial cells or lung fibroblasts triggers NET-DNA release by neutrophils, indicating that neutrophils can identify RSV-infected cells and respond to them by releasing NETs. The identification of the mechanisms responsible to mediate RSV-induced NETosis may prove valuable to the design of new therapeutic approaches to treat the inflammatory consequences of RSV bronchiolitis in young children.
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Armadilhas Extracelulares/metabolismo , Necrose/metabolismo , Neutrófilos/metabolismo , Desiminases de Arginina em Proteínas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Infecções por Vírus Respiratório Sincicial/metabolismo , Vírus Sincicial Respiratório Humano/patogenicidade , Adulto , Células Epiteliais Alveolares/metabolismo , Células Epiteliais Alveolares/virologia , Animais , Apoptose/fisiologia , Bronquiolite/metabolismo , Bronquiolite/virologia , Linhagem Celular , Chlorocebus aethiops , Armadilhas Extracelulares/virologia , Feminino , Humanos , Pulmão/metabolismo , Pulmão/virologia , Masculino , Necrose/virologia , Neutrófilos/virologia , Fosfatidilinositol 3-Quinases/metabolismo , Proteína-Arginina Desiminase do Tipo 4 , Infecções por Vírus Respiratório Sincicial/virologia , Transdução de Sinais/fisiologia , Células VeroRESUMO
Drug-induced liver injury (DILI) is a major cause of acute liver failure (ALF), where hepatocyte necrotic products trigger liver inflammation, release of CXC chemokine receptor 2 (CXCR2) ligands (IL-8) and other neutrophil chemotactic molecules. Liver infiltration by neutrophils is a major cause of the life-threatening tissue damage that ensues. A GRPR (gastrin-releasing peptide receptor) antagonist impairs IL-8-induced neutrophil chemotaxis in vitro. We investigated its potential to reduce acetaminophen-induced ALF, neutrophil migration, and mechanisms underlying this phenomenon. We found that acetaminophen-overdosed mice treated with GRPR antagonist had reduced DILI and neutrophil infiltration in the liver. Intravital imaging and cell tracking analysis revealed reduced neutrophil mobility within the liver. Surprisingly, GRPR antagonist inhibited CXCL2-induced migration in vivo, decreasing neutrophil activation through CD11b and CD62L modulation. Additionally, this compound decreased CXCL8-driven neutrophil chemotaxis in vitro independently of CXCR2 internalization, induced activation of MAPKs (p38 and ERK1/2) and downregulation of neutrophil adhesion molecules CD11b and CD66b. In silico analysis revealed direct binding of GRPR antagonist and CXCL8 to the same binding spot in CXCR2. These findings indicate a new potential use for GRPR antagonist for treatment of DILI through a mechanism involving adhesion molecule modulation and possible direct binding to CXCR2.
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Bombesina/análogos & derivados , Doença Hepática Induzida por Substâncias e Drogas/tratamento farmacológico , Neutrófilos/imunologia , Fragmentos de Peptídeos/farmacologia , Receptores da Bombesina/antagonistas & inibidores , Receptores de Interleucina-8B/metabolismo , Animais , Bombesina/farmacologia , Movimento Celular/efeitos dos fármacos , Células Cultivadas , Doença Hepática Induzida por Substâncias e Drogas/imunologia , Quimiotaxia/efeitos dos fármacos , Humanos , Interleucina-8/metabolismo , Camundongos , Camundongos Endogâmicos , Ativação de Neutrófilo/efeitos dos fármacos , Ligação Proteica , Transdução de Sinais/efeitos dos fármacosRESUMO
Nerve fibers and neurotransmitters have increasingly been shown to have a role in tumor progression. Gastrin-releasing peptide is a neuropeptide linked to tumor aggressiveness, acting as an autocrine tumor growth factor by binding to its receptor, gastrin-releasing peptide receptor, expressed by many tumors. Although neuropeptides have been previously linked to tumor cell proliferation, more recent studies have uncovered roles for neuropeptides in chemotaxis and metastasis. Understanding the precise roles of such peptides in cancer is crucial to optimizing targeted therapy design. We have previously described that gastrin-releasing peptide acts directly as a chemotactic factor for neutrophils, dependent on PI3K, ERK, and p38. In this study, we investigated roles for gastrin-releasing peptide in lung adenocarcinoma. We asked if gastrin-releasing peptide would act as a proliferative and/or chemotactic stimulus for gastrin-releasing peptide receptor-expressing tumor cells. In A549 cells, a non-small cell lung carcinoma line, the treatment with gastrin-releasing peptide leads to activation of AKT and ERK1/2, and production of reactive oxygen species. Gastrin-releasing peptide induced migration of A549 cells, dependent on gastrin-releasing peptide receptor and PI3K, but not ERK. However, no proliferation was observed in these cells in response to gastrin-releasing peptide, and gastrin-releasing peptide did not promote resistance to treatment with a chemotherapy drug. Our results suggest that, similar to what happens in neutrophils, gastrin-releasing peptide is a migratory, rather than a proliferative, stimulus, for non-small cell lung carcinoma cells, indicating a putative role for gastrin-releasing peptide and gastrin-releasing peptide receptor in metastasis.
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Adenocarcinoma/genética , Carcinogênese/genética , Peptídeo Liberador de Gastrina/genética , Neoplasias Pulmonares/genética , Receptores da Bombesina/genética , Células A549 , Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Adenocarcinoma de Pulmão , Antineoplásicos/administração & dosagem , Movimento Celular/genética , Proliferação de Células/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Peptídeo Liberador de Gastrina/administração & dosagem , Peptídeo Liberador de Gastrina/metabolismo , Humanos , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Sistema de Sinalização das MAP Quinases/genética , Proteína Oncogênica v-akt/genética , Fosfatidilinositol 3-Quinases/genética , Espécies Reativas de Oxigênio/metabolismo , Receptores da Bombesina/metabolismoRESUMO
Gastric infection by Helicobacter pylori is considered a risk factor for gastric and duodenal cancer, and extragastric diseases. Previous data have shown that, in a non-enzymatic way, H. pylori urease (HPU) activates neutrophils to produce ROS and also induces platelet aggregation, requiring ADP secretion modulated by the 12-lipoxygenase pathway, a signaling cascade also triggered by the physiological agonist collagen. Here we investigated further the effects on platelets of recombinant versions of the holoenzyme HPU, and of its two subunits (HpUreA and HpUreB). Although HpUreA had no aggregating activity on platelets, it partially inhibited collagen-induced aggregation. HpUreB induced platelet aggregation in the nanomolar range, and also interfered dose-dependently on both collagen- and ADP-induced platelet aggregation. HPU-induced platelet aggregation was inhibited by antibodies against glycoprotein VI (GPVI), the main collagen receptor in platelets. Flow cytometry analysis revealed exposure of P-selectin in HPU-activated platelets. Anti-glycoprotein IIbIIIa (GPIIbIIIa) antibodies increased the binding of FITC-labeled HPU to activated platelets, whereas anti-GPVI did not. Evaluation of post-transcriptional events in HPU-activated platelets revealed modifications in the pre-mRNA processing of pro-inflammatory proteins, with increased levels of mRNAs encoding IL-1ß and CD14. We concluded that HPU activates platelets probably through its HpUreB subunit. Activation of platelets by HPU turns these cells into a pro-inflammatory phenotype. Altogether, our data suggest that H. pylori urease, besides allowing bacterial survival within the gastric mucosa, may have an important, and so far overlooked, role in gastric inflammation mediated by urease-activated neutrophils and platelets.
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The aim of this study is to evaluate the response to an inflammatory stimulus in mice exposed to LPS-induced neonatal stress at different ages and sexes. Balb/c mice were submitted to intraperitoneal injections on postnatal days 3 and 10 with lipopolysaccharide (nLPS) or saline solution (nSal). At 21 or 60 days, either saline solution was injected or an inflammatory stimulus was induced by the injection of 1% carrageenan. Inflammatory cytokines, reactive oxygen species, and neutrophil extracellular traps (NETs) production were measured in peritoneal fluid. LPS-induced neonatal stress can reduce inflammatory cytokines in males and females. An increase in NETs production was observed when 60 day nLPS animals were compared to 21 day mice in both sexes. The ROS production was not affected by neonatal stress. The results shown here indicate that LPS-induced neonatal stress can alter cytokine production in response to inflammatory stimuli at different ages, in a sex-dependent effect. © 2016 Wiley Periodicals, Inc. Dev Psychobiol 58: 600-613, 2016.
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Líquido Ascítico/metabolismo , Citocinas/metabolismo , Armadilhas Extracelulares/metabolismo , Inflamação/imunologia , Inflamação/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico/imunologia , Fatores Etários , Animais , Animais Recém-Nascidos , Carragenina/administração & dosagem , Feminino , Interleucina-10/metabolismo , Interleucina-6/metabolismo , Lipopolissacarídeos/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Fatores Sexuais , Fatores de Necrose Tumoral/metabolismoRESUMO
Neutrophil extracellular traps (NETs) are a combination of DNA fibers and granular proteins, such as neutrophil elastase (NE). NETs are released in the extracellular space in response to different stimuli. Carrageenan is a sulfated polysaccharide extracted from Chondrus crispus, a marine algae, used for decades in research for its potential to induce inflammation in different animal models. In this study, we show for the first time that carrageenan injection can induce NET release in a mouse model of acute peritonitis. Carrageenan induced NET release by viable neutrophils with NE and myeloperoxidase (MPO) expressed on DNA fibers. Furthermore, although this polysaccharide was able to stimulate reactive oxygen species (ROS) generation by peritoneal neutrophils, NADPH oxidase derived ROS were dispensable for NET formation by carrageenan. In conclusion, our results show that carrageenan-induced inflammation in the peritoneum of mice can induce NET formation in an ROS-independent manner. These results may add important information to the field of inflammation and potentially lead to novel anti-inflammatory agents targeting the production of NETs.
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Carragenina/toxicidade , Armadilhas Extracelulares/imunologia , Inflamação/patologia , Neutrófilos/imunologia , Peritonite/patologia , Espécies Reativas de Oxigênio/metabolismo , Animais , DNA/genética , Modelos Animais de Doenças , Inflamação/induzido quimicamente , Inflamação/imunologia , Elastase de Leucócito/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , NADPH Oxidases/metabolismo , Peritonite/induzido quimicamente , Peritonite/imunologia , Peroxidase/biossínteseRESUMO
High concentrations of free heme found during hemolytic events or cell damage leads to inflammation, characterized by neutrophil recruitment and production of reactive oxygen species, through mechanisms not yet elucidated. In this study, we provide evidence that heme-induced neutrophilic inflammation depends on endogenous activity of the macrophage-derived lipid mediator leukotriene B(4) (LTB(4)). In vivo, heme-induced neutrophil recruitment into the peritoneal cavity of mice was attenuated by pretreatment with 5-lipoxygenase (5-LO) inhibitors and leukotriene B(4) receptor 1 (BLT1) receptor antagonists as well as in 5-LO knockout (5-LO(-/-)) mice. Heme administration in vivo increased peritoneal levels of LTB(4) prior to and during neutrophil recruitment. Evidence that LTB(4) was synthesized by resident macrophages, but not mast cells, included the following: 1) immuno-localization of heme-induced LTB(4) was compartmentalized exclusively within lipid bodies of resident macrophages; 2) an increase in the macrophage population enhanced heme-induced neutrophil migration; 3) depletion of resident mast cells did not affect heme-induced LTB(4) production or neutrophil influx; 4) increased levels of LTB(4) were found in heme-stimulated peritoneal cavities displaying increased macrophage numbers; and 5) in vitro, heme was able to activate directly macrophages to synthesize LTB(4). Our findings uncover a crucial role of LTB(4) in neutrophil migration induced by heme and suggest that beneficial therapeutic outcomes could be achieved by targeting the 5-LO pathway in the treatment of inflammation associated with hemolytic processes.
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Movimento Celular/efeitos dos fármacos , Heme/farmacologia , Leucotrieno B4/metabolismo , Neutrófilos/efeitos dos fármacos , Animais , Araquidonato 5-Lipoxigenase/genética , Araquidonato 5-Lipoxigenase/metabolismo , Células Cultivadas , Feminino , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/metabolismo , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/citologia , Neutrófilos/metabolismo , Receptores do Leucotrieno B4/metabolismo , Tioglicolatos/farmacologia , p-Metoxi-N-metilfenetilamina/farmacologiaRESUMO
BACKGROUND: Heat shock proteins (Hsps) are stress induced proteins with immunomodulatory properties. The Hsp70 of Mycobacterium tuberculosis (TBHsp70) has been shown to have an anti-inflammatory role on rodent autoimmune arthritis models, and the protective effects were demonstrated to be dependent on interleukin-10 (IL-10). We have previously observed that TBHsp70 inhibited maturation of dendritic cells (DCs) and induced IL-10 production by these cells, as well as in synovial fluid cells. METHODOLOGY/PRINCIPAL FINDINGS: We investigated if TBHsp70 could inhibit allograft rejection in two murine allograft systems, a transplanted allogeneic melanoma and a regular skin allograft. In both systems, treatment with TBHsp70 significantly inhibited rejection of the graft, and correlated with regulatory T cells (Tregs) recruitment. This effect was not tumor mediated because injection of TBHsp70 in tumor-free mice induced an increase of Tregs in the draining lymph nodes as well as inhibition of proliferation of lymph node T cells and an increase in IL-10 production. Finally, TBHsp70 inhibited skin allograft acute rejection, and depletion of Tregs using a monoclonal antibody completely abolished this effect. CONCLUSIONS/SIGNIFICANCE: We present the first evidence for an immunosuppressive role for this protein in a graft rejection system, using an innovative approach--immersion of the graft tissue in TBHsp70 solution instead of protein injection. Also, this is the first study that demonstrates dependence on Treg cells for the immunosuppressive role of TBHsp70. This finding is relevant for the elucidation of the immunomodulatory mechanism of TBHsp70. We propose that this protein can be used not only for chronic inflammatory diseases, but is also useful for organ transplantation management.
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Linfócitos T CD4-Positivos/citologia , Células Dendríticas/citologia , Proteínas de Choque Térmico HSP70/metabolismo , Subunidade alfa de Receptor de Interleucina-2/biossíntese , Linfócitos T Reguladores/citologia , Animais , Linfócitos T CD4-Positivos/metabolismo , Linhagem Celular Tumoral , Doença Crônica , Feminino , Imunossupressores/metabolismo , Interleucina-10/metabolismo , Melanoma Experimental , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Líquido Sinovial/metabolismo , Linfócitos T/citologia , Transplante HomólogoRESUMO
Trypanosoma cruzi, the etiological agent of Chagas disease, is transmitted by bug feces deposited on human skin during a blood meal. However, parasite infection occurs through the wound produced by insect mouthparts. Saliva of the Triatominae bug Rhodnius prolixus is a source of lysophosphatidylcholine (LPC). Here, we tested the role of both triatomine saliva and LPC on parasite transmission. We show that vector saliva is a powerful inducer of cell chemotaxis. A massive number of inflammatory cells were found at the sites where LPC or saliva was inoculated into the skin of mice. LPC is a known chemoattractant for monocytes, but neutrophil recruitment induced by saliva is LPC independent. The preincubation of peritoneal macrophages with saliva or LPC increased fivefold the association of T. cruzi with these cells. Moreover, saliva and LPC block nitric oxide production by T. cruzi-exposed macrophages. The injection of saliva or LPC into mouse skin in the presence of the parasite induces an up-to-sixfold increase in blood parasitemia. Together, our data suggest that saliva of the Triatominae enhances T. cruzi transmission and that some of its biological effects are attributed to LPC. This is a demonstration that a vector-derived lysophospholipid may act as an enhancing factor of Chagas disease.
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Doença de Chagas/transmissão , Imunossupressores/imunologia , Insetos Vetores/parasitologia , Lisofosfatidilcolinas/imunologia , Rhodnius/parasitologia , Saliva/imunologia , Animais , Doença de Chagas/imunologia , Quimiotaxia de Leucócito/imunologia , Cromatografia em Camada Fina , Citocinas/biossíntese , Humanos , Lisofosfatidilcolinas/metabolismo , Macrófagos/imunologia , Macrófagos/microbiologia , Masculino , Camundongos , Infiltração de Neutrófilos/imunologia , Óxido Nítrico/biossíntese , Parasitemia/imunologia , Saliva/química , Trypanosoma cruziRESUMO
Snake venom is a complex mixture containing diverse protein components with different structures and functions that are used for prey immobilization and death. Snake venoms from the family Viperidae cause pronounced local and systemic effects, such as pain, edema, hemorrhage and necrosis. Here, we investigated the enzymatic and biological activities of venoms from two Amazonian snakes, Bothriopsis bilineata and Bothriopsis taeniata. Both venoms presented high enzymatic activities for proteases kallikrein, thrombin and plasmin, low levels of trypsin, cathepsin C and leucine aminopeptidase activities, while lacked acetylcholinesterase activity. B. taeniata and B. bilineata crude venoms caused inflammation inducing neutrophil recruitment into peritoneal cavity of mice 4h after injection. Neutrophil recruitment induced by B. taeniata venom was accompanied by hemorrhage. EDTA treatment profoundly impaired neutrophil recruitment, suggesting the involvement of a metalloproteinase on venoms-induced neutrophil recruitment. Pretreatment with dexamethasone and zileuton, a 5-lipoxygenase inhibitor, significantly reduced neutrophil migration, but indomethacin and montelukast, a cysteinyl leukotriene receptor antagonist, had no effect, suggesting the involvement of lipoxygenase-derived metabolites, probably LTB(4). Together, these results show that B. bilineata and B. taeniata venoms induce a marked inflammatory reaction, with leukocyte recruitment, and hemorrhage, which parallels to a high proteolytic activity found in these venoms.
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Bothrops/fisiologia , Venenos de Crotalídeos/toxicidade , Animais , Movimento Celular/efeitos dos fármacos , Venenos de Crotalídeos/química , Venenos de Crotalídeos/enzimologia , Ácido Edético/farmacologia , Liofilização , Inflamação/patologia , Camundongos , Camundongos Endogâmicos C57BL , Infiltração de Neutrófilos/efeitos dos fármacos , Neutrófilos/efeitos dos fármacos , América do Sul , Especificidade da EspécieRESUMO
Heme is an ancient and ubiquitous molecule present in organisms of all kingdoms, composed of an atom of iron linked to four ligand groups of porphyrin. A high amount of free heme, a potential amplifier of the inflammatory response, is a characteristic feature of diseases with increased hemolysis or extensive cell damage. Here we demonstrate that heme, but not its analogs/precursors, induced tumor necrosis factor-alpha (TNF-alpha) secretion by macrophages dependently on MyD88, TLR4, and CD14. The activation of TLR4 by heme is exquisitely strict, requiring its coordinated iron and the vinyl groups of the porphyrin ring. Signaling of heme through TLR4 depended on an interaction distinct from the one established between TLR4 and lipopolysaccharide (LPS) since anti-TLR4/MD2 antibody or a lipid A antagonist inhibited LPS-induced TNF-alpha secretion but not heme activity. Conversely, protoporphyrin IX antagonized heme without affecting LPS-induced activation. Moreover, heme induced TNF-alpha and keratinocyte chemokine but was ineffective to induce interleukin-6, interleukin-12, and interferon-inducible protein-10 secretion or co-stimulatory molecule expression. These findings support the concept that the broad ligand specificity of TLR4 and the different activation profiles might in part reside in its ability to recognize different ligands in different binding sites. Finally, heme induced oxidative burst, neutrophil recruitment, and heme oxygenase-1 expression independently of TLR4. Thus, our results presented here reveal a previous unrecognized role of heme as an extracellular signaling molecule that affects the innate immune response through a receptor-mediated mechanism.