Pathogen-produced catalase affects immune priming: A potential pathogen strategy.

Immune priming in invertebrates occurs when the first contact with a pathogen/parasite enhances resistance after a second encounter with the same strain or species. Although the mechanisms are not well understood, there is evidence that priming the immune response of some hosts leads to greater pro-oxidant production. Parasites, in turn, might counteract the host attack with antioxidants. Virulent pathogen strains may therefore mask invertebrate immune priming. For example, different parasite species overexpress catalase as a virulence factor to resist host pro-oxidants, possibly impairing the immune priming response. The aim of this study was firstly to evaluate the specificity of immune priming in Tenebrio molitor when facing homologous and heterologous challenges. Secondly, homologous challenges were carried out with two Metarhizium anisopliae strains (Ma10 and CAT). The more virulent strain (CAT) overexpresses catalase, an antioxidant that perhaps impairs a host immune response mediated by reactive oxygen species (ROS). Indeed, T. molitor larvae exhibited better immune priming (survival) in response to the Ma10 than CAT homologous challenge. Moreover, the administration of paraquat, an ROS-promoting agent, favoured survival of the host upon exposure to each fungal strain. We propose that some pathogens likely overcome pro-oxidant-mediated immune priming defences by producing antioxidants such as catalase.

The occurrence of immune priming can be species-specific in entomopathogens.

Immune priming in invertebrates refers to an improved immune response (and therefore a better chance of survival) upon a second encounter with a specific pathogen. Although the existence of immune priming has been evaluated in invertebrate hosts, the ability of a particular entomopathogen species or strain to influence the occurrence of immune priming has not been thoroughly evaluated. The aim of the current study was to compare the occurrence of immune priming in Tenebrio molitor larvae after homologous challenges (a dual exposure to similar entomopathogens) with Serratia marcescens, Bacillus thuringiensis and Metarhizium anisopliae. Larvae presented more effective immune priming (measured as survival rates) when exposed to M. anisopliae or B. thuringiensis than when exposed to S. marcescens. We hypothesize that the toll pathway may help T. molitor survive these enemies and that the IMD pathway may be expressed to a lesser degree in this species, which may explain why they succumb to Gram-negative bacteria. This and other recent evidence suggest that the occurrence of immune priming in these organisms must not be ruled out until this phenomenon is tested with different entomopathogens.

[Hemorrhagic pericarditis and cardiac tamponade in systemic lupus erythematosus. A case report]. / Reporte de un caso depericarditis hemorrágica y taponamiento cardíaco asociados a lupus eritematoso sistémico.

Systemic lupus erythematosus is a chronic inflammatory autoimmune disorder that can affect any organ or system. Although pericarditis is the most frequent cardiac manifestation of this entity, usually is not a life threatening situation. Pericardial effusion causing cardiac tamponade is a very rare complication in lupus, with an incidence less than 2%. We report a case of pericardial tamponade due to SLE with severe hemodynamic involvement in a 21-year-old woman associated to rapidly progressive glomerulonephritis, acute pancreatitis, acute acalculous cholecystitis, pleural effusion, hematologic, cutaneous and neurologic lupus activity. Recognition of this rare manifestation of SLE may be life saving.

Reporte de un caso de pericarditis hemorrágica y taponamiento cardíaco asociados a lupus eritematoso sistémico / Hemorrhagic pericarditis and cardiac tamponade in systemic lupus erythematosus. A case report

El lupus eritematoso sistémico es una enfermedad autoinmune inflamatoria capaz de afectar cualquier aparato y sistema. Aunque la pericarditis es la manifestación cardíaca más frecuentemente observada, usualmente no es una situación que comprometa la vida del paciente. El taponamiento cardíaco ocasionado por derrame pericárdico en el lupus es una situación extremadamente rara, con una incidencia no mayor al 2%. Informamos el caso de una mujer de 21 años de edad con taponamiento cardíaco por lupus eritematoso sistémico, asociado a glomerulonefritis rápidamente progresiva, pancreatitis aguda, colecistitis aguda acalculosa, derrame pleural y actividad lúpica hematológica, cutánea y neurológica. El reconocimiento oportuno de esta rara manifestación del lupus puede salvar la vida de un paciente.

Systemic lupus erythematosus is a chronic inflammatory autoimmune disorder that can affect any organ or system. Although pericarditis is the most frequent cardiac manifestation of this entity, usually is not a life threatening situation. Pericardial effusion causing cardiac tamponade is a very rare complication in lupus, with an incidence less than 2%. We report a case of pericardial tamponade due to SLE with severe hemodynamic involvement in a 21-year-old woman associated to rapidly progressive glomerulonephritis, acute pancreatitis, acute acalculous cholecystitis, pleural effusion, hematologic, cutaneous and neurologic lupus activity. Recognition of this rare manifestation of SLE may be life saving.