RESUMO
INTRODUCTION: Streptococcus pneumoniae colonizes the nasopharynx of healthy individuals establishing a commensal relationship with the host. In some conditions, bacteria invade the lower respiratory tract and innate immune responses are crucial to avoid diseases such as pneumonia, sepsis, or meningitis. METHODS: Here, we compared the susceptibility to pneumococcal respiratory infection of two outbred mouse lines, AIRmin and AIRmax, selected for low or high acute inflammatory responses, respectively. RESULTS: AIRmin mice showed increased susceptibility to infection with different pneumococcal serotypes, when compared to AIRmax. Significant higher numbers of alveolar macrophages expressing the CD206 mannose receptor were observed in AIRmin mice when compared to AIRmax mice. Despite this difference, secretion of several cytokines and chemokines in the respiratory tract of AIRmin and AIRmax mice, after infection, was similar. The only exception was CXCL5, which was highly induced after pneumococcal infection in AIRmax mice but not in AIRmin mice. Reduced expression of the matrix metalloproteinases (MMP) 2, 3, 8, and 9, as well as reduced activities of MMPs were also observed in the lungs of AIRmin mice, after infection. Such impaired responses may have contributed to the low influx of neutrophils observed in the airways of these mice. Finally, high percentages of macrophages and neutrophils in apoptosis or necrosis, at the site of infection, were also observed in AIRmin mice, suggesting that leukocyte functionality is also compromised. CONCLUSIONS: Our results indicate that CXCL5 and MMPs contribute to the resistance to pneumococcal infection in mice.
Assuntos
Quimiocina CXCL5/imunologia , Colagenases/imunologia , Imunidade Inata , Pulmão/imunologia , Pneumonia Pneumocócica/imunologia , Streptococcus pneumoniae/imunologia , Animais , Suscetibilidade a Doenças , Feminino , Pulmão/microbiologia , Pulmão/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Pneumonia Pneumocócica/patologiaRESUMO
Scorpion stings are the main cause of human envenomation in Brazil and, for the treatment of victims, the World Health Organization (WHO) recommends the use of antivenoms. The first step to achieve effective antivenom is to use a good quality venom pool and to evaluate it, with LD50 determination as the most accepted procedure. It is, however, time-consuming and requires advanced technical training. Further, there are significant ethical concerns regarding the number of animals required for testing. Hence, we investigated the correspondence between LD50 results, in vitro assays, and a strong correlation with proteolytic activity levels was observed, showing, remarkably, that proteases are potential toxicity markers for Tityus serrulatus venom. The comparison of reversed-phase chromatographic profiles also has a potential application in venoms' quality control, as there were fewer neurotoxins detected in the venom with high LD50 value. These results were confirmed by mass spectrometry analysis. Therefore, these methods could precede the LD50 assay to evaluate the venom excellence by discriminating-and discarding-poor-quality batches, and, consequently, with a positive impact on the number of animals used. Notably, proposed assays are fast and inexpensive, being technically and economically feasible in Tityus serrulatus venom quality control to produce effective antivenoms.
Assuntos
Venenos de Escorpião/química , Venenos de Escorpião/toxicidade , Animais , Proteínas de Artrópodes/análise , Bioensaio , Cromatografia de Fase Reversa , Eletroforese em Gel de Poliacrilamida , Feminino , Hialuronoglucosaminidase/metabolismo , Dose Letal Mediana , Masculino , Espectrometria de Massas , Nitrogênio/análise , Proteólise , EscorpiõesRESUMO
BACKGROUND: The snakes from the Bitis genus are some of the most medically important venomous snakes in sub Saharan Africa, however little is known about the composition and effects of these snake venom peptides. Considering that the victims with Bitis genus snakes have exacerbate hypotension and cardiovascular disorders, we investigated here the presence of angiotensin-converting enzyme modulators on four different species of venoms. METHODS: The peptide fractions from Bitis gabonica gabonica, Bitis nasicornis, Bitis gabonica rhinoceros and Bitis arietans which showed inhibitory activity on angiotensin-converting enzyme were subjected to mass spectrometry analysis. Eight proline-rich peptides were synthetized and their potencies were evaluated in vitro and in vivo. RESULTS: The MS analysis resulted in over 150 sequences, out of which 32 are new proline-rich oligopeptides, and eight were selected for syntheses. For some peptides, inhibition assays showed inhibitory potentials of cleavage of angiotensin I ten times greater when compared to bradykinin. In vivo tests showed that all peptides decreased mean arterial pressure, followed by tachycardia in 6 out of 8 of the tests. CONCLUSION: We describe here some new and already known proline-rich peptides, also known as bradykinin-potentiating peptides. Four synthetic peptides indicated a preferential inhibition of angiotensin-converting enzyme C-domain. In vivo studies show that the proline-rich oligopeptides are hypotensive molecules. GENERAL SIGNIFICANCE: Although proline-rich oligopeptides are known molecules, we present here 32 new sequences that are inhibitors of the angiotensin-converting enzyme and consistent with the symptoms of the victims of Bitis spp, who display severe hypotension.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/toxicidade , Pressão Arterial/efeitos dos fármacos , Hipotensão/induzido quimicamente , Oligopeptídeos/toxicidade , Venenos de Víboras/toxicidade , Inibidores da Enzima Conversora de Angiotensina/síntese química , Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Animais , Cromatografia Líquida de Alta Pressão , Transferência Ressonante de Energia de Fluorescência , Frequência Cardíaca/efeitos dos fármacos , Hipotensão/fisiopatologia , Masculino , Oligopeptídeos/síntese química , Oligopeptídeos/isolamento & purificação , Prolina , Ratos Wistar , Sistema Renina-Angiotensina/efeitos dos fármacos , Taquicardia/induzido quimicamente , Taquicardia/fisiopatologia , Espectrometria de Massas em Tandem , Venenos de Víboras/químicaRESUMO
Accidents caused by scorpions represent a relevant public health issue in Brazil, being more recurring than incidents with snakes and spiders. The main species responsible for this situation is the yellow scorpion, Tityus serrulatus, due especially to the great frequency with which accidents occur and the potential of its venom to induce severe clinical manifestations, even death, mainly among children. Although neurotoxins are well characterized, little information is known about other components of scorpion venoms, such as peptidases, and their effect on envenomation. Previous results from our group showed that the metallopeptidases present in this venom are capable of hydrolyzing the neuropeptide dynorphin 1-13 in vitro, releasing Leu-enkephalin, which may interact with ion channels and promote indirect neurotoxicity. Thus, this study aims to get more information about the effect of toxic peptidase activity present in the venom on biologically active peptides, and to evaluate the in vitro neutralizing potential of commercial antivenoms produced by the Butantan Institute. A set of human bioactive peptides were studied as substrates for the peptidases, and the members of the neuropeptide Y family were found to be the most susceptible ones. All new substrate hydrolyses were totally inhibited by ethylenediaminetetracetic and not blocked by phenylmethanesulfonylfluoride, indicating that metallopeptidases were responsible for the peptidase activity. Also, peptidase activities were only partially inhibited by therapeutic Brazilian scorpion antivenom (SAV) and arachnid antivenom (AAV). The dose-response inhibition by both antivenoms indicates that AAV neutralizes better than SAV at the used doses. These characterizations, unpublished until now, can contribute to the improvement of our knowledge about the venom and envenomation processes by T. serrulatus.