PI3Kgamma inhibition blocks glomerulonephritis and extends lifespan in a mouse model of systemic lupus.

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease generated by deregulation of T cell-mediated B-cell activation, which results in glomerulonephritis and renal failure. Disease is treated with immunosuppressants and cytostatic agents that have numerous side effects. Here we examine the use of inhibitors of phosphoinositide 3-kinase (PI3K) gamma, a lipid kinase that regulates inflammation, in the MRL-lpr mouse model of SLE. Treatment reduced glomerulonephritis and prolonged lifespan, suggesting that P13Kgamma may be a useful target in the treatment of chronic inflammation.

Salmonella enterica serovar Choleraesuis derivatives harbouring deletions in rpoS and phoP regulatory genes are attenuated in pigs, and survive and multiply in porcine intestinal macrophages and fibroblasts, respectively.

Live attenuated Salmonella enterica strains have been extensively studied as potential vectors for the oral delivery of heterologous antigens. Due to its ability to target immune cells, its specific mechanism for crossing the intestinal barrier, and its swine-restricted tropism, S. enterica subspecies enterica serovar Choleraesuis (S. Choleraesuis) has attracted a great deal of interest for the production of bacterial-based oral carriers specifically adapted to swine. In this study, two mutants of S. Choleraesuis were constructed and their attenuation and intracellular fate analysed with the purpose of engineering new attenuated live strains with improved properties as oral vaccine carriers. Those strains harboured a specific deletion either within the phoP or rpoS genes, which encode virulence-related regulators in S. Typhimurium. In comparison to the wild-type parental S. Choleraesuis, the mutant strains, especially DeltaphoP, were extremely low in virulence in the murine model and in the natural host, the pig. Moreover, when compared with a commercial live vaccine strain, SC-54, the two mutants showed a higher level of attenuation in mice and DeltaphoP also in pigs. In addition, DeltarpoS and DeltaphoP presented a proliferation and survival phenotype within swine intestinal primary fibroblast and macrophage cell cultures, respectively. Collectively, the present results indicate that the DeltarpoS and DeltaphoP strains of S. Choleraesuis gather adequate features to be potential candidates for vaccine vectors for the specific delivery of heterologous antigens adapted to pigs.

Salmonella enterica serovar Choleraesuis derivatives harbouring deletions in rpoS and phoP regulatory genes as vehicles for DNA vaccines.

We investigated the use of two previously described attenuated strains of Salmonella enterica subspecies enterica serovar Choleraesuis (S. Choleraesuis), DeltaphoP and DeltarpoS, compared with the commercial attenuated SC-54 strain, as bactofection vehicles, to deliver an epitope model (3xFLAG) to the intestinal immune system. The gene encoding the epitope 3xFLAG was subcloned into the pCMVbetam2A mammalian expression vector (creating pCMV3xFLAGm2A) and introduced into S. Choleraesuis strains. The 3xFLAG epitope was expressed efficiently in murine macrophage J774A.1 cell cultures infected with Salmonella DeltaphoP and DeltarpoS vehicles but not with SC-54, as shown by gene-specific quantitative real-time reverse-transcriptase PCR. The stability of pCMV3xFLAGm2A in each strain was determined in vitro in the absence of antibiotic selection, and in vivo following oral immunisation of BALB/c mice. Administration of the DNA vaccine to mice led to the production of 3xFLAG-specific serum IgG and intestinal IgA antibody responses in DeltarpoS and SC-54, and spleen cell secretion of IFN-gamma following specific 3xFLAG stimulation in DeltaphoP. All together, these results indicate that DeltaphoP, DeltarpoS and SC-54 that expressed 3xFLAG from pCMV3xFLAGm2A elicited a different biased immune response, in which the T-helper-1-like cellular immune response was predominant in DeltaphoP, whilst IgA-related mucosal immunity predominated in DeltarpoS and SC-54. We conclude that DeltaphoP and DeltarpoS of S. Choleraesuis are new promising candidates as vaccine bactofection vectors.

Class IB-phosphatidylinositol 3-kinase (PI3K) deficiency ameliorates IA-PI3K-induced systemic lupus but not T cell invasion.

Class I PI3K catalyzes formation of 3-poly-phosphoinositides. The family is divided into IA isoforms, activated by Tyr kinases and the IB isoform (PI3Kgamma), activated by G protein-coupled receptors. Mutations that affect PI3K are implicated in chronic inflammation, although the differential contribution of each isoform to pathology has not been elucidated. Enhanced activation of class IA-PI3K in T cells extends CD4+ memory cell survival, triggering an invasive lymphoproliferative disorder and systemic lupus. As both IA- and IB-PI3K isoforms regulate T cell activation, and activated pathogenic CD4+ memory cells are involved in triggering systemic lupus, we examined whether deletion of IB could reduce the pathological consequences of increased IA-PI3K activity. IB-PI3Kgamma deficiency did not abolish invasion or lymphoproliferation, but reduced CD4+ memory cell survival, autoantibody production, glomerulonephritis, and systemic lupus. Deletion of the IB-PI3Kgamma isoform thus decreased survival of pathogenic CD4+ memory cells, selectively inhibiting systemic lupus development. These results validate the PI3Kgamma isoform as a target for systemic lupus erythematosus treatment.