No abstract

Background: Prion protein (PrP C ) modulates inflammation, and prion diseases affect neutrophil numbers and functions, but the regulation of PrP C in neutrophils is unknown. Results: Inflammation and stress massively up-regulated PrP C in neutrophils via glucocorticoids and TGF-␤. Conclusion:We show a novel pathway of regulation of PrP C , with functional consequences for neutrophils. Significance: Systemic control of the expression and function of PrP C broadly modulates cellular physiology and pathology.The prion protein (PrP C ) is a cell surface protein expressed mainly in the nervous system. In addition to the role of its abnormal conformer in transmissible spongiform encephalopathies, normal PrP C may be implicated in other degenerative conditions often associated with inflammation. PrP C is also present in cells of hematopoietic origin, including T cells, dendritic cells, and macrophages, and it has been shown to modulate their functions. Here, we investigated the impact of inflammation and stress on the expression and function of PrP C in neutrophils, a cell type critically involved in both acute and chronic inflammation. We found that systemic injection of LPS induced transcription and translation of PrP C in mouse neutrophils. Up-regulation of PrP C was dependent on the serum content of TGF-␤ and glucocorticoids (GC), which, in turn, are contingent on the activation of the hypothalamic-pituitary-adrenal axis in response to systemic inflammation. GC and TGF-␤, either alone or in combination, directly up-regulated PrP C in neutrophils, and accordingly, the blockade of GC receptors in vivo curtailed the LPS-induced increase in the content of PrP C . Moreover, GC also mediated up-regulation of PrP C in neutrophils following noninflammatory restraint stress. Finally, neutrophils with upregulated PrP C presented enhanced peroxide-dependent cytotoxicity to endothelial cells. The data demonstrate a novel interplay of the nervous, endocrine, and immune systems upon both the expression and function of PrP C in neutrophils, which may have a broad impact upon the physiology and pathology of various organs and systems.

Conhecimento da população de Viçosa, MG, sobre as formas de transmissão da aidsThe knowledge of the population of Viçosa, MG, about the ways of AIDS transmission

Graft versus host disease (GVHD) is the major limitation of allogeneic hematopoietic stem cell transplantation (HSCT) presenting high mortality and morbidity rates. However, the exact cause of death is not completely understood and does not correlate with specific clinical and histological parameters of disease. Here we show, by using a semi-allogeneic mouse model of GVHD, that mortality and morbidity can be experimentally separated. We injected bone marrow-derived dendritic cells (BMDC) from NOD2/CARD15-deficient donors into semi-allogeneic irradiated chimaeras and observed that recipients were protected from death. However, no protection was observed regarding clinical or pathological scores up to 20 days after transplantation. Protection from death was associated with decreased bacterial translocation, faster hematologic recovery and epithelial integrity maintenance despite mononuclear infiltration at day 20 post-GVHD induction with no skew towards different T helper phenotypes. The protected mice recovered from aGVHD and progressively reached scores compatible with healthy animals. Altogether, our data indicate that severity and mortality can be separate events providing a model to study transplant-related mortality.