RESUMO
Neutrophil extracellular traps (NETs) are fiber structures composed of chromatin and granular proteins that capture and eliminate microorganisms. The NETs formation is induced in response to pathogens and physiological stimuli; however, some pathogens have developed strategies to evade NETs activity. Trichinella spiralis excretory-secretory (ES) antigens are proteins that allow the establishment of the parasite in the host, facilitating penetration, migration, nutrition, and survival. In this paper we described that ES antigens inhibit NETs release, since neutrophils incubated with these antigens maintains a delobulated nucleus, without the release fibers structures indicative of NETs. We also found that other antimicrobial functions of neutrophils, such as phagocytic activity, degranulation, and ROS production, remain unchanged after incubation with ES antigens. This is relevant since it could constitute a novel strategy for the treatment of autoimmune pathologies in which the formation of NETs performs an important role.
Assuntos
Anti-Infecciosos , Armadilhas Extracelulares , Trichinella spiralis , Animais , Neutrófilos , LarvaRESUMO
Scedosporium apiospermum is an opportunistic emerging pathogen that can develop in both immunosuppressive and immunocompetent patients with pulmonary infections. Neutrophils are recognized as critical cells in the early response to a fungal infection through different mechanisms that eliminate or control the infection such as neutrophil extracellular traps (NETs). In this work, we investigate the presence of NETs in the lung tissue of immunocompetent mice infected with Scedosporium apiospermum. In the histopathological study the presence of filamentous basophilic material with hematoxylin-eosin and periodic acid Schiff stains suggestive of extracellular DNA was observed. We demonstrated the presence of NETs by immunofluorescence staining of extracellular DNA, myeloperoxidase, and elastase in lung tissue. Our results showed that on days 1 and 3 post-infection extracellular DNA, myeloperoxidase, and elastase correlate with areas of high concentration of cell infiltrates and fungal structures. The observation of fungal structures in the tissue decreased as did the presence of NETs by day 5 post-infection. We suggest that NETs release may play an important role in the early containment of Scedosporium apiospermum lung infection.
Assuntos
Armadilhas Extracelulares , Micoses , Scedosporium , Animais , Modelos Animais de Doenças , Humanos , Camundongos , NeutrófilosRESUMO
Background: Serratia marcescens is an enteric bacterium with increasing incidence in clinical settings, attributed mainly to the opportune expression of diverse virulence determinants plus a wide intrinsic and acquired antibiotic resistance. Methods: The aim of this study was to compare the virulence factor profiles of 185 Serratia marcescens isolates from different clinical origins. In vitro proteolytic and hemolytic activities, biofilm formation, and motility were assessed in each strain. Additionally, the pathogenicity of four hypervirulent strains was analyzed in vivo in Galleria mellonella. Results: We found that bacterial isolates from wound/abscess and respiratory tract specimens exhibited the highest protease activity along with a strong biofilm production, while uropathogenic isolates showed the highest hemolytic activity. Swarming and swimming motilities were similar among all the strains. However, respiratory tract isolates showed the most efficient motility. Two hyperhemolytic and two hyperproteolytic strains were detected; the latter were more efficient killing Galleria mellonella with a 50%-60% larval mortality 48 hours after challenge. Conclusion: A correlation was found between biofilm formation and proteolytic and hemolytic activities in biopsy specimens and bloodstream isolates, respectively. Overall, it becomes critical to evaluate and compare the clinical strains virulence diversity in order to understand the underlying mechanisms that allow the establishment and persistence of opportunistic bacterial infections in the host.
Assuntos
Antibacterianos/farmacologia , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Serratia marcescens/patogenicidade , Biofilmes/crescimento & desenvolvimento , Infecção Hospitalar , Hemólise/fisiologia , Humanos , México/epidemiologia , Peptídeo Hidrolases/fisiologia , Serratia marcescens/isolamento & purificação , Virulência , Fatores de VirulênciaRESUMO
Nowadays, Huanglongbing (HLB) disease, commonly known as "yellow dragon disease", affects citrus crops worldwide and has a devastating effect in the agro-industrial sector. Significant efforts have been made to fight the illness, but still, there is no effective treatment to eradicate the disease. This work is the first approach to evaluate the capacity of silver nanoparticles (AgNPs) to directly eradicate the bacteria responsible for Huanglongbing disease, Candidatus Liberibacter asiaticus (CLas), in the field. The AgNPs were administered by foliar sprinkling and trunk injection of 93 sick trees with remarkable results. Both methods produce an 80-90% decrease of bacterial titre, quantified by qRT-PCR in collected foliar tissue, compared with the control group. Scanning electron microscopy images show an essential reduction of starch accumulation in phloem vessels after AgNP treatments without evidence of bacteria in the analyzed samples. Compared with other effective methods that involve ß-lactam antibiotics, the potency of AgNPs is 3 to 60-times higher when it is administered by foliar sprinkling and from 75 to 750-fold higher when the administration was by trunk-injection. All these results allow us to propose this AgNP formulation as a promising alternative for the treatment of infected trees in the field.
RESUMO
Protease-activated receptors (PARs) have been described in a wide diversity of vertebrate cells, including human immune cells. Macrophages are pivotal cells in the host-pathogen interaction and their polarization in M1 or M2 cells has been described as a new central paradigm in the immune response to pathogens. In this context, we explored the involvement of PAR activation by serine proteases on M1/M2 macrophage differentiation and their impact on the Th1/Th2 cytokine profile in response to Mycobacterium tuberculosis antigen. Our results demonstrate that the serine proteases, thrombin and trypsin, induce interleukin (IL)-4 release from human monocytes, together with upregulation of the macrophage mannose receptor (CD206) in the same way that alternative M2a differentiated cells with M-CSF/IL-4. Protease stimulation of monocytes in the presence of PAR-1 (SCH-79797) or PAR-2 (FSLLRY-NH2) antagonists abolished IL-4 release from monocytes, whereas the use of the peptide agonist for PAR-1 (SFLLRNPNDKYEPF-NH2) or PAR-2 (SLIGKV-NH2) induced the secretion of IL-4 at a level comparable to thrombin or trypsin. When these protease-induced M2 macrophages from healthy human PPD + donors were co-cultured with autologous lymphocyte population in the presence of Mycobacterium tuberculosis antigen, we found a consistent inhibition of IFN-γ/IL-12 release together with persistent IL-4 expression, in contrast to the expected Th1 profile obtained with M2a macrophages. To our knowledge, this is the first observation that proteolytic activation of PAR1/2 receptors in monocytes induces M2-like macrophages with impaired plasticity and their implication in the driving of the Th1/Th2 cytokine profile.
Assuntos
Polaridade Celular/fisiologia , Macrófagos/metabolismo , Macrófagos/fisiologia , Receptor PAR-1/metabolismo , Receptor PAR-2/metabolismo , Diferenciação Celular/fisiologia , Plasticidade Celular , Células Cultivadas , Citocinas/metabolismo , Humanos , Interleucina-4/metabolismo , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/fisiologia , Ativação de Macrófagos/fisiologia , Fator Estimulador de Colônias de Macrófagos/metabolismo , Monócitos/metabolismo , Monócitos/fisiologia , Mycobacterium tuberculosis/patogenicidade , Tripsina/metabolismo , Tuberculose/metabolismo , Regulação para Cima/fisiologiaRESUMO
Neutrophils activated with pathogens or their products induce formation of extracellular traps (NETs), but if this constitutes a general response against all pathogenic species in a single genus or intrageneric differences exist remains unknown, yet this is of great importance for the establishment of effective treatments. To determine this, we analyzed neutrophil extracellular traps formation after the stimulation with bloodstream isolates from different Candida species (Candida albicans, C. tropicalis, C. parapsilosis, and C. glabrata), and found that each species has a different capacity to induce DNA extrusion, which is independent of their morphology (yeast or hyphae). We observed that phospholipase producer's strains and their secretion products were able to induce NETs, a property not observed with phospholipase deficient strains, with exception of some Candida glabrata sensu stricto isolates, which showed no NETs induction although they did show phospholipase production. To further analyze this, we extended our study to include Candida glabrata cryptic species (C. bracarensis and C. nivariensis) and no extracellular traps formation was observed. Here, we contribute to the understanding of how neutrophils initiate NETs, and we found that certain strains may have a differential capacity to trigger these structures, which may explain the high mortality of some isolates.
RESUMO
Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the gene that codes for the CF trans-membrane conductance regulator. These mutations result in abnormal secretions viscous airways of the lungs, favoring pulmonary infection and inflammation in the middle of neutrophil recruitment. Recently it was described that neutrophils can contribute with disease pathology by extruding large amounts of nuclear material through a mechanism of cell death known as Neutrophil Extracellular Traps (NETs) into the airways of patients with CF. Additionally, NETs production can contribute to airway colonization with bacteria, since they are the microorganisms most frequently found in these patients. In this review, we will discuss the implication of individual or mixed bacterial infections that most often colonize the lung of patients with CF, and the NETs role on the disease.
Assuntos
Infecções Bacterianas/patologia , Fibrose Cística/complicações , Fibrose Cística/imunologia , Armadilhas Extracelulares , Infiltração de Neutrófilos , Bactérias/imunologia , Infecções Bacterianas/microbiologia , Coinfecção/microbiologia , Coinfecção/patologia , Fibrose Cística/patologia , HumanosRESUMO
Trichosporon asahii is considered an opportunistic pathogen responsible for severe infections, mainly in immunocompromised patients. The aims of this study were to investigate the prevalent genotypes among 39 clinical isolates of this microorganism by sequencing the IGS1 region and to determine the in vitro production of DNAse, hemolysin, aspartyl proteinase, phospholipase and esterase, as well as the susceptibilities of the isolates to amphotericin B, anidulafungin, micafungin, caspofungin, voriconazole, posaconazole, fluconazole and 5-flucytosine. Our findings showed that genotype I was the most prevalent comprising 69.23% of the isolates. We confirmed the production of esterase for all our isolates, and report the production of DNAse and aspartyl proteinase in 84.62% and 23% of the isolates, respectively. Only one isolate of T. asahii produced hemolysin. None of the isolates showed phospholipase activity. Fifty-three percent of the T. asahii strains exhibited amphotericin B MICs ≥ 2 µg/ml. The three echinocandins evaluated yielded high MICs (≥2 µg/ml) in all isolates. Thirty-five percent of the isolates had high MICs for 5-flucytosine (≥32 µg/ml), and 97% of the isolates were susceptible to the evaluated triazoles.
Assuntos
Antifúngicos/farmacologia , Tipagem Molecular , Técnicas de Tipagem Micológica , Trichosporon/classificação , Trichosporon/metabolismo , Tricosporonose/microbiologia , Fatores de Virulência/metabolismo , Genótipo , Técnicas de Genotipagem , Proteínas Hemolisinas/metabolismo , Humanos , Hidrolases/metabolismo , México , Testes de Sensibilidade Microbiana , Análise de Sequência de DNA , Trichosporon/efeitos dos fármacos , Trichosporon/isolamento & purificaçãoRESUMO
Identification of mycobacterial adhesins is needed to understand better the pathogenesis of tuberculosis and to develop new strategies to fight this infection. In this work, THP-1 monocytic cells were incubated with Mycobacterium tuberculosis culture filtrate proteins labelled with biotin and a dominant 19-kDa adhesin was found. This adhesin was characterized as the glycosylated and acylated 19-kDa antigen (Rv 3763). These findings were confirmed in assays with culture filtrate proteins and cell-wall fractions from a recombinant Mycobacterium smegmatis strain that overexpresses the 19-kDa antigen. Further, fluorescent microspheres coated with recombinant culture filtrate proteins adhere to cells in higher numbers than microspheres coated with native M. smegmatis proteins. The binding of the 19-kDa antigen to cells was inhibited with mannose receptor competitor sugars, Ca(2+) chelators and with a monoclonal antibody to the human mannose receptor. Phagocytosis assays showed high-level binding of bacilli to THP-1 cells that was inhibited with alpha-methyl-mannoside, mannan, EDTA and mAbs to the mannose receptor and to the 19-kDa M. tuberculosis antigen. Immunoprecipitation, cell-surface ELISA and immunostaining confirmed the expression of the mannose receptor by THP-1 cells. In conclusion, here we show that the macrophage mannose receptor, considered a pathogen pattern recognition receptor, may interact with mannose residues of mycobacterial glycoproteins that could promote the phagocytosis of mycobacteria.