Long-lasting pro-inflammatory suppression of microglia by LPS-preconditioning is mediated by RelB-dependent epigenetic silencing.

Microglia, the innate immune cells of the central nervous system (CNS), react to endotoxins like bacterial lipopolysaccharides (LPS) with a pronounced inflammatory response. To avoid excess damage to the CNS, the microglia inflammatory response needs to be tightly regulated. Here we report that a single LPS challenge results in a prolonged blunted pro-inflammatory response to a subsequent LPS stimulation, both in primary microglia cultures (100 ng/ml) and in vivo after intraperitoneal (0.25 and 1mg/kg) or intracerebroventricular (5 µg) LPS administration. Chromatin immunoprecipitation (ChIP) experiments with primary microglia and microglia acutely isolated from mice showed that LPS preconditioning was accompanied by a reduction in active histone modifications AcH3 and H3K4me3 in the promoters of the IL-1ß and TNF-α genes. Furthermore, LPS preconditioning resulted in an increase in the amount of repressive histone modification H3K9me2 in the IL-1ß promoter. ChIP and knock-down experiments showed that NF-κB subunit RelB was bound to the IL-1ß promoter in preconditioned microglia and that RelB is required for the attenuated LPS response. In addition to a suppressed pro-inflammatory response, preconditioned primary microglia displayed enhanced phagocytic activity, increased outward potassium currents and nitric oxide production in response to a second LPS challenge. In vivo, a single i.p. LPS injection resulted in reduced performance in a spatial learning task 4 weeks later, indicating that a single inflammatory episode affected memory formation in these mice. Summarizing, we show that LPS-preconditioned microglia acquire an epigenetically regulated, immune-suppressed phenotype, possibly to prevent excessive damage to the central nervous system in case of recurrent (peripheral) inflammation.

Anticancer effects of an oncolytic parvovirus combined with non-conventional therapeutics on pancreatic carcinoma cell lines.

Standard therapies such as surgery and chemotherapy offer only minimal improvement in pancreatic cancer. However, the viruses killing cancer cells and substances like some antibiotics and phytoalexins with anticancer potential may represent a candidate non-conventional mean of cancer treatment in the future. In this study, the effect of infection with oncolytic H-1 parvovirus (H-1PV) combined with antibiotic norfloxacin (NFX) or phytoalexin resveratrol on the survival of cell lines Panc-1 and BxPC3 derived from human pancreatic carcinoma was tested. Whereas H-1PV with NFX exerted a synergistic effect, H-1PV with resveratrol resulted in an additive effect only. All the effects were partial, but they were more pronounced in Panc-1 compared to BxPC3 cells.