No abstract

PDE4 inhibitors are effective anti-inflammatory drugs whose effects and putative mechanisms on resolution of inflammation and neutrophil apoptosis in vivo are still unclear. Here, we examined the effects of specific PDE4 inhibition on the resolution of neutrophilic inflammation in the pleural cavity of LPS-challenged mice. LPS induced neutrophil recruitment that was increased at 4 h, peaked at 8-24 h, and declined thereafter. Such an event in the pleural cavity was preceded by increased levels of KC and MIP-2 at 1 and 2 h. Treatment with the PDE4 inhibitor rolipram, at 4 h after LPS administration, decreased the number of neutrophils and increased the percentage of apoptotic cells in the pleural cavity in a PKA-dependent manner. Conversely, delayed treatment with a CXCR2 antagonist failed to prevent neutrophil recruitment. Forskolin and db-cAMP also decreased the number of neutrophils and increased apoptosis in the pleural cavity. The proapoptotic effect of rolipram was associated with decreased levels of the prosurvival protein Mcl-1 and increased caspase-3 cleavage. The pan-caspase inhibitor zVAD-fmk prevented rolipram-induced resolution of inflammation. LPS resulted in a time-dependent activation of Akt, which was blocked by treatment with rolipram or PI3K and Akt inhibitors, and PI3K and Akt inhibitors also enhanced apoptosis and promoted neutrophil clearance. Although LPS induced NF-kappaB activation, which was blocked by rolipram, NF-kappaB inhibitors did not promote resolution of neutrophil accumulation in this model. In conclusion, our data show that PDE4 inhibition resolves neutrophilic inflammation by promoting caspase-dependent apoptosis of inflammatory cells by targeting a PKA/PI3K/Akt-dependent survival pathway.

Passatempo virus was isolated during a zoonotic outbreak. Biologic features and molecular characterization of hemagglutinin, thymidine kinase, and vaccinia growth factor genes suggested a vaccinia virus infection, which strengthens the idea of the reemergence and circulation of vaccinia virus in Brazil. Molecular polymorphisms indicated that Passatempo virus is a different isolate.

BackgroundDespite the fact that smallpox eradication was declared by the World Health Organization (WHO) in 1980, other poxviruses have emerged and re-emerged, with significant public health and economic impacts. Vaccinia virus (VACV), a poxvirus used during the WHO smallpox vaccination campaign, has been involved in zoonotic infections in Brazilian rural areas (Bovine Vaccinia outbreaks – BV), affecting dairy cattle and milkers. Little is known about VACV's natural hosts and its epidemiological and ecological characteristics. Although VACV was isolated and/or serologically detected in Brazilian wild animals, the link between wildlife and farms has not yet been elucidated.Methodology/Principal FindingsIn this study, we describe for the first time, to our knowledge, the isolation of a VACV (Mariana virus - MARV) from a mouse during a BV outbreak. Genetic data, in association with biological assays, showed that this isolate was the same etiological agent causing exanthematic lesions observed in the cattle and human inhabitants of a particular BV-affected area. Phylogenetic analysis grouped MARV with other VACV isolated during BV outbreaks.Conclusion/SignificanceThese data provide new biological and epidemiological information on VACV and lead to an interesting question: could peridomestic rodents be the link between wildlife and BV outbreaks?

Interferons (IFNs) were discovered as antiviral agents 50 years ago, and enormous progress has been made since then. Nowadays, IFNs (specifically type I IFNs), have been ascribed as the cytokines that bridge the innate and adaptive immunity soon after the recognition of pathogen-associated molecular patterns (PAMPs) by the infected host. Notably, a unifying mechanism for type I IFN production has been established upon innate immune detection. Thus, TLR 3, 4, 7 and 9 associate endosomal recognition of PAMPs to type I IFN responses, a mechanism that has been shown in plasmacytoid dendritic cells to be dependent on the PI3K/mTOR/S6K pathway. It is worth noting that pathogen recognition triggers a fine-tuned controlled program that not only includes the production of antiviral (IFN) and pro-inflammatory cytokines to initiate the antiviral response but also signals the cessation of the response through the induction of suppressors of cytokine signaling (SOCS). SOCS in turn is under tight regulation of the TAM receptors (protein tyrosine kinase receptors TYRO3, AXL and MER), and activation of which thereby protects the host from the threats of autoimmune diseases.

Early events play a decisive role in virus multiplication. We have shown previously that activation of MAPK/ERK1/2 (mitogen-activated protein kinase/extracellular-signal-regulated kinase 1/2) and protein kinase A are pivotal for vaccinia virus (VV) multiplication [de Magalhães, Andrade, Silva, Sousa, Ropert, Ferreira, Kroon, Gazzinelli and Bonjardim (2001) J. Biol. Chem. 276, 38353-38360]. In the present study, we show that VV infection provoked a sustained activation of both ERK1/2 and RSK2 (ribosomal S6 kinase 2). Our results also provide evidence that this pattern of kinase activation depends on virus multiplication and ongoing protein synthesis and is maintained independently of virus DNA synthesis. It is noteworthy that the VGF (VV growth factor), although involved, is not essential for prolonged ERK1/2 activation. Furthermore, our findings suggest that the VV-stimulated ERK1/2 activation also seems to require actin dynamics, microtubule polymerization and tyrosine kinase phosphorylation. The VV-stimulated pathway MEK/ERK1/2/RSK2 (where MEK stands for MAPK/ERK kinase) leads to phosphorylation of the ternary complex factor Elk-1 and expression of the early growth response (egr-1) gene, which kinetically paralleled the kinase activation. The recruitment of this pathway is biologically relevant, since its disruption caused a profound effect on viral thymidine kinase gene expression, viral DNA replication and VV multiplication. This pattern of sustained kinase activation after VV infection is unique. In addition, by connecting upstream signals generated at the cytoskeleton and by tyrosine kinase, the MEK/ERK1/2/RSK2 cascade seems to play a decisive role not only at early stages of the infection, i.e. post-penetration, but is also crucial to define the fate of virus progeny.

This study confirms the high clinical frequency of human VACV infection, even among vaccinated individuals. The infection was related to detection of IgG- or IgM-specific antibodies that correlates in most of the cases with positive PRNT. The DNAemia suggests viremia during VACV natural infections. Our data indicate that patients vaccinated against smallpox may no longer be protected.

Outbreaks of bovine vaccinia disease caused by circulation of Vaccinia virus (VACV) strains have been a common occurrence in Brazil in the recent years, being an important emergent zoonosis. During a single outbreak that took place in 2001, two genetically different VACV strains were isolated and named Guarani P1 virus (GP1V) and Guarani P2 virus (GP2V). Molecular diagnosis was done through restriction fragment length polymorphism (RFLP) of ati gene (A26L) and by sequence analysis of a group of five VACV genes including the C11R, J2R, A56R, B18R, and E3L genes. These findings confirmed the co-circulation of two different Vaccinia virus strains during the same outbreak, raising important questions about the origin, emergence, and circulation of VACV strains in Brazil.