RESUMO
[This corrects the article on p. 499 in vol. 9, PMID: 29616011.].
RESUMO
During Chagas disease, the Trypanosoma cruzi can induce some changes in the host cells in order to escape or manipulate the host immune response. The modulation of the lipid metabolism in the host phagocytes or in the parasite itself is one feature that has been observed. The goal of this mini review is to discuss the mechanisms that regulate intracellular lipid body (LB) biogenesis in the course of this parasite infection and their meaning to the pathophysiology of the disease. The interaction host-parasite induces LB (or lipid droplet) formation in a Toll-like receptor 2-dependent mechanism in macrophages and is enhanced by apoptotic cell uptake. Simultaneously, there is a lipid accumulation in the parasite due to the incorporation of host fatty acids. The increase in the LB accumulation during infection is correlated with an increase in the synthesis of PGE2 within the host cells and the parasite LBs. Moreover, the treatment with fatty acid synthase inhibitor C75 or non-steroidal anti-inflammatory drugs such as NS-398 and aspirin inhibited the LB biogenesis and also induced the down modulation of the eicosanoid production and the parasite replication. These findings show that LBs are organelles up modulated during the course of infection. Furthermore, the biogenesis of the LB is involved in the lipid mediator generation by both the macrophages and the parasite triggering escape mechanisms.
RESUMO
Leptin directly activates macrophages and lymphocytes, but the role of leptin in neutrophil activation and migration is still controversial. Here, we investigate the in vivo mechanisms of neutrophil migration induced by leptin. The intraperitoneal injection of leptin (1 mg/kg) induces a time- and concentration-dependent neutrophil influx. We did not observe the enhancement of lipid bodies/droplets in neutrophils, after leptin treatment, as we had observed previously in peritoneal macrophages. The participation of leukotriene B4 (LTB4) in neutrophil recruitment triggered by leptin was investigated using different strategies. Leptin-induced neutrophil recruitment occurs both in the absence of 5-lipoxygenase activity in 5-lipoxygenase (5-LO)-/- mice and after the administration of either 5-LO inhibitor (Zileuton) or the LTB4 receptor antagonist (U-75302). Moreover, no direct induction of LTB4 by leptin could be observed. Neutrophil influx could not be prevented by the mammalian target of rapamycin (mTOR) inhibitor, rapamycin, contrasting with the leptin-induced signaling for lipid body formation in macrophage that is mTOR-dependent. Leptin administration led to tumor necrosis factor-alpha (TNFα) production by the peritoneal cells both in vivo and in vitro. In addition, neutrophil recruitment was inhibited in tumor necrosis factor receptor 1 (TNFR1-/-) mice, indicating a role for TNF in leptin-induced neutrophil recruitment to the peritoneal cavity. Leptin-induced neutrophil influx was PI3Kγ-dependent, as it was absent in PI3Kγ-/- mice. Accordingly, leptin induced the peritoneal cells to produce CXCL1, both in vivo and in vitro, and the neutrophil influx was ablated after using an antibody against CXCL1. Our results establish TNFα/TNFR1- and CXCL1-dependent signaling as important pathways for leptin-induced neutrophil migration in vivo.
Assuntos
Quimiocina CXCL1/fisiologia , Leptina/fisiologia , Neutrófilos/fisiologia , Receptores Tipo I de Fatores de Necrose Tumoral/fisiologia , Fator de Necrose Tumoral alfa/fisiologia , Animais , Araquidonato 5-Lipoxigenase/genética , Movimento Celular , Quimiocina CCL3/genética , Macrófagos Peritoneais/imunologia , Masculino , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Camundongos Knockout , Infiltração de Neutrófilos , Fosfatidilinositol 3-Quinases/genéticaRESUMO
Mansonic schistosomiasis is a disease caused by the trematode Schistosoma mansoni, endemic to tropical countries. S. mansoni infection induces the formation of granulomas and potent polarization of Th2-type immune response. There is great interest in understanding the mechanisms used by this parasite that causes a modulation of the immune system. Recent studies from our group demonstrated that lipids of S. mansoni, including lysophosphatidylcholine (LPC) have immunomodulatory activity. In the present study, our aim was to investigate the role of lipids derived from S. mansoni in the activation and polarization of macrophages and to characterize the mechanisms involved in this process. Peritoneal macrophages obtained from wild type C57BL/6mice or bone marrow derived macrophages were stimulated in vitro with lipids extracted from adult worms of S. mansoni. We demonstrated that total schistosomal-derived lipids as well as purified LPC induced alternatively activated macrophages/M2 profile observed by increased expression of arginase-1, mannose receptor, Chi3l3, TGFß and production of IL-10 and PGE2 24h after stimulation. The involvement of the nuclear receptor PPARγ in macrophage response against LPC was investigated. Through Western blot and immunofluorescence confocal microscopy we demonstrated that schistosomal-derived LPC induces increased expression of PPARγ in macrophages. The LPC-induced increased expression of arginase-1 were significantly inhibited by the PPAR-γ antagonist GW9662. Together, these results demonstrate an immunomodulatory role of schistosomal-derived LPC in activating macrophages to a profile of the type M2 through PPARγ-dependent mechanisms, indicating a novel pathway for macrophage polarization triggered by parasite-derived LPC with potential implications to disease pathogenesis.
Assuntos
Lisofosfatidilcolinas/metabolismo , Macrófagos Peritoneais/metabolismo , Macrófagos Peritoneais/fisiologia , PPAR gama/metabolismo , Schistosoma mansoni/metabolismo , Animais , Arginase/metabolismo , Interleucina-10/metabolismo , Lipídeos/fisiologia , Ativação de Macrófagos/fisiologia , Camundongos , Camundongos Endogâmicos C57BLRESUMO
We recently showed that Mycobacterium leprae (ML) is able to induce lipid droplet formation in infected macrophages. We herein confirm that cholesterol (Cho) is one of the host lipid molecules that accumulate in ML-infected macrophages and investigate the effects of ML on cellular Cho metabolism responsible for its accumulation. The expression levels of LDL receptors (LDL-R, CD36, SRA-1, SR-B1, and LRP-1) and enzymes involved in Cho biosynthesis were investigated by qRT-PCR and/or Western blot and shown to be higher in lepromatous leprosy (LL) tissues when compared to borderline tuberculoid (BT) lesions. Moreover, higher levels of the active form of the sterol regulatory element-binding protein (SREBP) transcriptional factors, key regulators of the biosynthesis and uptake of cellular Cho, were found in LL skin biopsies. Functional in vitro assays confirmed the higher capacity of ML-infected macrophages to synthesize Cho and sequester exogenous LDL-Cho. Notably, Cho colocalized to ML-containing phagosomes, and Cho metabolism impairment, through either de novo synthesis inhibition by statins or depletion of exogenous Cho, decreased intracellular bacterial survival. These findings highlight the importance of metabolic integration between the host and bacteria to leprosy pathophysiology, opening new avenues for novel therapeutic strategies to leprosy.
Assuntos
Colesterol/metabolismo , Interações Hospedeiro-Patógeno , Macrófagos/microbiologia , Viabilidade Microbiana , Mycobacterium leprae/fisiologia , Fagossomos/microbiologia , Animais , Western Blotting , Células Cultivadas , Perfilação da Expressão Gênica , Humanos , Hanseníase/tratamento farmacológico , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Fagossomos/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Receptores de LDL/biossíntese , Receptores de LDL/genética , Proteínas de Ligação a Elemento Regulador de Esterol/biossíntese , Proteínas de Ligação a Elemento Regulador de Esterol/genéticaRESUMO
The nuclear receptor PPARγ acts as a key modulator of lipid metabolism, inflammation and pathogenesis in BCG-infected macrophages. However, the molecular mechanisms involved in PPARγ expression and functions during infection are not completely understood. Here, we investigate signaling pathways triggered by TLR2, the involvement of co-receptors and lipid rafts in the mechanism of PPARγ expression, lipid body formation and cytokine synthesis in macrophages during BCG infection. BCG induces NF-κB activation and increased PPARγ expression in a TLR2-dependent manner. Furthermore, BCG-triggered increase of lipid body biogenesis was inhibited by the PPARγ antagonist GW9662, but not by the NF-κB inhibitor JSH-23. In contrast, KC/CXCL1 production was largely dependent on NF-κB but not on PPARγ. BCG infection induced increased expression of CD36 in macrophages in vitro. Moreover, CD36 co-immunoprecipitates with TLR2 in BCG-infected macrophages, suggesting its interaction with TLR2 in BCG signaling. Pretreatment with CD36 neutralizing antibodies significantly inhibited PPARγ expression, lipid body formation and PGE2 production induced by BCG. Involvement of CD36 in lipid body formation was further confirmed by decreased BCG-induced lipid body formation in CD36 deficient macrophages. Similarly, CD14 and CD11b/CD18 blockage also inhibited BCG-induced lipid body formation, whereas TNF-α synthesis was not affected. Disruption of rafts recapitulates the latter result, inhibiting lipid body formation, but not TNF-α synthesis in BCG-infected macrophages. In conclusion, our results suggest that CD36-TLR2 cooperation and signaling compartmentalization within rafts, divert host response signaling through PPARγ-dependent and NF-κB-independent pathways, leading to increased macrophage lipid accumulation and down-modulation of macrophage response.
Assuntos
Quimiocina CXCL1/biossíntese , Metabolismo dos Lipídeos , Mycobacterium bovis , Transdução de Sinais , Receptor 2 Toll-Like/metabolismo , Tuberculose , Fator de Necrose Tumoral alfa/biossíntese , Anilidas/farmacologia , Animais , Antígeno CD11b/biossíntese , Antígeno CD11b/genética , Antígenos CD18/biossíntese , Antígenos CD18/genética , Antígenos CD36/biossíntese , Antígenos CD36/genética , Quimiocina CXCL1/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Receptores de Lipopolissacarídeos/biossíntese , Receptores de Lipopolissacarídeos/genética , Macrófagos/metabolismo , Macrófagos/microbiologia , Macrófagos/patologia , Microdomínios da Membrana/genética , Microdomínios da Membrana/metabolismo , Microdomínios da Membrana/patologia , Camundongos , Camundongos Knockout , NF-kappa B/antagonistas & inibidores , NF-kappa B/genética , NF-kappa B/metabolismo , PPAR gama/antagonistas & inibidores , PPAR gama/biossíntese , PPAR gama/genética , Fenilenodiaminas/farmacologia , Receptor 2 Toll-Like/genética , Tuberculose/metabolismo , Tuberculose/patologia , Tuberculose/veterinária , Fator de Necrose Tumoral alfa/genéticaRESUMO
We recently showed that Mycobacterium leprae (ML) is able to induce lipid droplet formation in infected macrophages. We herein confirm that cholesterol (Cho) is one of the host lipid molecules that accumulate in ML-infected macrophages and investigate the effects of ML on cellular Cho metabolism responsible for its accumulation. The expression levels of LDL receptors (LDL-R, CD36, SRA-1, SR-B1, and LRP-1) and enzymes involved in Cho biosynthesis were investigated by qRT-PCR and/or Western blot and shown to be higher in lepromatous leprosy (LL) tissues when compared to borderline tuberculoid (BT) lesions. Moreover, higher levels of the active form of the sterol regulatory element-binding protein (SREBP) transcriptional factors, key regulators of the biosynthesis and uptake of cellular Cho, were found in LL skin biopsies. Functional in vitro assays confirmed the higher capacity of ML-infected macrophages to synthesize Cho and sequester exogenous LDL-Cho. Notably, Cho colocalized to ML-containing phagosomes, and Cho metabolism impairment, through either de novo synthesis inhibition by statins or depletion of exogenous Cho, decreased intracellular bacterial survival. These findings highlight the importance of metabolic integration between the host and bacteria to leprosy pathophysiology, opening new avenues for novel therapeutic strategies to leprosy.
Assuntos
Humanos , Animais , Fagossomos/metabolismo , Fagossomos/microbiologia , Receptores de LDL/biossíntese , Células Cultivadas , Western Blotting , Colesterol/metabolismo , Perfilação da Expressão Gênica , Proteínas de Ligação a Elemento Regulador de Esterol/biossíntese , Viabilidade Microbiana , Interações Hospedeiro-Patógeno , Reação em Cadeia da Polimerase em Tempo Real , Hanseníase/tratamento farmacológico , Macrófagos/metabolismo , Macrófagos/microbiologia , Camundongos Endogâmicos C57BL , Mycobacterium leprae/fisiologiaRESUMO
Bacterial clearance is one of the most important beneficial consequences of the innate immune response. Chemokines are important mediators controlling leukocyte trafficking and activation, whereas reactive oxygen and nitrogen species are effectors in bacterial killing. In the present work, we used in vivo and in vitro models of infections to study the role of monocyte chemoattractant protein 1 (MCP-1)/CCL2 and nitric oxide (NO) in the bacterial clearance in sepsis. Our results show that MCP-1/CCL2 and NO levels are increased in the peritoneal cavity of mice 6 h after sepsis induced by cecal ligation and puncture. Pretreatment with anti-MCP-1/CCL2 monoclonal antibodies increased the number of colony-forming units (CFUs) recovered in the peritoneal lavage fluid. Moreover, CFU counts were increased in the peritoneal fluid of CCR2 mice subjected to cecal ligation and puncture. In vitro stimulation of peritoneal macrophages with recombinant MCP-1/CCL2 reduced CFU counts in the supernatant after challenge with Escherichia coli. Conversely, treatment with anti-MCP-1/CCL2 increased CFU counts under the same experimental condition. Stimulation of cultured macrophages with MCP-1/CCL2 and interferon had a synergistic effect on NO production. Macrophages from CCL2 mice showed a consistent decrease in NO production when compared with wild-type controls after stimulation with LPS + interferon. Finally, we showed incubation of macrophages with E. coli, and the ERK inhibitor U0126 increased CFU numbers and decreased intracellular levels of NO. In conclusion, we demonstrated for the first time that MCP-1/CCL2 has a crucial role in the clearance of bacteria by mechanisms involving increased expression of inducible NO synthase and production of NO by ERK signaling pathways.
Assuntos
Infecções Bacterianas/imunologia , Quimiocina CCL2/imunologia , Óxido Nítrico/imunologia , Sepse/imunologia , Animais , Líquido Ascítico/microbiologia , Infecções Bacterianas/microbiologia , Butadienos/farmacologia , Células Cultivadas , Quimiocina CCL2/deficiência , Contagem de Colônia Microbiana , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , MAP Quinases Reguladas por Sinal Extracelular/antagonistas & inibidores , MAP Quinases Reguladas por Sinal Extracelular/imunologia , Sistema de Sinalização das MAP Quinases/imunologia , Ativação de Macrófagos/imunologia , Macrófagos Peritoneais/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Óxido Nítrico/biossíntese , Nitrilas/farmacologia , Fagocitose/imunologia , Proteínas Recombinantes/imunologia , Sepse/microbiologiaRESUMO
Tuberculosis continues to be a global health threat, with drug resistance and HIV coinfection presenting challenges for its control. Mycobacterium tuberculosis, the etiological agent of tuberculosis, is a highly adapted pathogen that has evolved different strategies to subvert the immune and metabolic responses of host cells. Although the significance of peroxisome proliferator-activated receptor gamma (PPARγ) activation by mycobacteria is not fully understood, recent findings are beginning to uncover a critical role for PPARγ during mycobacterial infection. Here, we will review the molecular mechanisms that regulate PPARγ expression and function during mycobacterial infection. Current evidence indicates that mycobacterial infection causes a time-dependent increase in PPARγ expression through mechanisms that involve pattern recognition receptor activation. Mycobacterial triggered increased PPARγ expression and activation lead to increased lipid droplet formation and downmodulation of macrophage response, suggesting that PPARγ expression might aid the mycobacteria in circumventing the host response acting as an escape mechanism. Indeed, inhibition of PPARγ enhances mycobacterial killing capacity of macrophages, suggesting a role of PPARγ in favoring the establishment of chronic infection. Collectively, PPARγ is emerging as a regulator of tuberculosis pathogenesis and an attractive target for the development of adjunctive tuberculosis therapies.
RESUMO
Parasitederived lipids may play important roles in hostpathogen interactions and escape mechanisms. Herein, we evaluated the role of schistosomalderived lipids in Tolllike receptor (TLR)-2 and eosinophil activation in Schistosoma mansoni infection. Mice lacking TLR2 exhibited reduced liver eosinophilic granuloma, compared with that of wildtype animals, following S. mansoni infection. Decreased eosinophil accumulation and eosinophil lipid body (lipid droplet) formation, at least partially due to reduced production of eotaxin, interleukin (IL)5, and IL13 in S. mansoni-infected TLR2-/- mice, compared with the corresponding production in wildtype mice, was noted. Although no differences were observed in survival rates during the acute schistosomal infection (up to 50 days), increased survival of TLR2-/- mice, compared with survival of wildtype mice, was observed during the chronic phase of infection. Schistosomal lipid extract and schistosomalderived lysophosphatidylcholine (lysoPC)-stimulated macrophages in vitro induced TLR2dependent NFkB activation and cytokine production. Furthermore, in vivo schistosomal lysoPC administration induced eosinophil recruitment and cytokine production, in a mechanism largely dependent on TLR2. Taken together, our results suggest that schistosomalderived lysoPC may participate in cytokine production and eosinophil activation through a TLR2dependent pathway in S. mansoni infection. Moreover, our results suggest that TLR2dependent inflammatory reaction, cytokine production, and eosinophil recruitment and activation may contribute to the pathogenesis and lethality in the chronic phase of infection.