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Observations of elevated basal cortisol levels in Alzheimer's disease (AD) patients prompted the hypothesis that stress and glucocorticoids (GC) may contribute to the development and/or maintenance of AD. Consistent with that hypothesis, we show that stress and GC provoke misprocessing of amyloid precursor peptide in the rat hippocampus and prefrontal cortex, resulting in increased levels of the peptide C-terminal fragment 99 (C99), whose further proteolytic cleavage results in the generation of amyloid-b (Ab). We also show that exogenous Ab can reproduce the effects of stress and GC on C99 production and that a history of stress strikingly potentiates the C99-inducing effects of Ab and GC. Previous work has indicated a role for Ab in disruption of synaptic function and cognitive behaviors, and AD patients reportedly show signs of heightened anxiety. Here, behavioral analysis revealed that like stress and GC, Ab administration causes spatial memory deficits that are exacerbated by stress and GC; additionally, Ab, stress and GC induced a state of hyperanxiety. Given that the intrinsic properties of C99 and Ab include neuroendangerment and behavioral impairment, our findings suggest a causal role for stress and GC in the etiopathogenesis of AD, and demonstrate that stressful life events and GC therapy can have a cumulative impact on the course of AD development and progression.

The online version of this article has a Supplementary Appendix. BackgroundThe immunoregulatory enzyme indoleamine 2,3-dioxygenase, which catalyzes the conversion of tryptophan into kynurenine, is expressed in a significant subset of patients with acute myeloid leukemia, resulting in the inhibition of T-cell proliferation and the induction of regulatory T cells. Acute myeloid leukemia cells can be differentiated into dendritic cells, which have increased immunogenicity and have been proposed as vaccines against leukemia. Design and MethodsLeukemic dendritic cells were generated from acute myeloid leukemia cells and used as stimulators in functional assays, including the induction of regulatory T cells. Indoleamine 2,3-dioxygenase expression in leukemic dendritic cells was evaluated at molecular, protein and enzymatic levels. ResultsWe demonstrate that, after differentiation into dendritic cells, both indoleamine 2,3-dioxygenase-negative and indoleamine 2,3-dioxygenase-positive acute myeloid leukemia samples show induction and up-regulation of indoleamine 2,3-dioxygenase gene and protein, respectively. Indoleamine 2,3-dioxygenase-positive acute myeloid leukemia dendritic cells catabolize tryptophan into kynurenine metabolite and inhibit T-cell proliferation through an indoleamine 2,3-dioxygenase-dependent mechanism. Moreover, indoleamine 2,3-dioxygenase-positive leukemic dendritic cells increase the number of allogeneic and autologous CD4 ConclusionsThese data identify indoleamine 2,3-dioxygenase-mediated catabolism as a tolerogenic mechanism exerted by leukemic dendritic cells and have clinical implications for the use of these cells for active immunotherapy of leukemia.Key words: acute myeloid leukemia, dendritic cells, T regulatory cells, immunotherapy, indoleamine 2,3-dioxygenase.Citation: Curti A, Trabanelli S, Onofri C, Aluigi M, Salvestrini V, Ocadlikova D, Evangelisti C, Rutella S, De Cristofaro R, Ottaviani E, Baccarani M, and Lemoli RM. Indoleamine 2, leukemic dendritic cells impair a leukemia-specific immune response by inducing potent T regulatory cells. Haematologica 2010;95(12):2022-2030. doi:10.3324/haematol.2010 This is an open-access paper. © F e r r a t a S t o r t i F o u n d a t i o n Indoleamine 2,3-dioxygenase-expressing leukemic dendritic cells impair a leukemia-specific immune response by inducing potent T regulatory cells

As for any solid tumour, pituitary adenoma expansion is dependent on neovascularization through angiogenesis.

TGF-beta isoforms are expressed in the anterior pituitary and modulate the growth and function of endocrine pituitary cells. Recently, TGF-beta has been shown to stimulate growth and basic fibroblast growth factor secretion in nonendocrine folliculostellate (FS) pituitary cells. We therefore studied whether the production of FS cell-derived vascular endothelial growth factor (VEGF), the most important regulator of vascular permeability and angiogenesis, is affected by TGF-beta. We observed by RT-PCR that TtT/GF cells, which are FS mouse pituitary tumor cells, synthesize TGF-beta1, -beta2, and -beta3. They also express TGF-beta receptors types 1 and 2, as well as Smad2, Smad3, and Smad4 proteins, which are essential for TGF-betabinding and signaling. Stimulation of TtT/GF cells with either TGF-beta1 or TGF-beta3 induced a rapid translocation of Smad2 into the cell nuclei. Both TGF-beta isoforms dose dependently stimulated VEGF production in TtT/GF cells, but not in lactosomatotroph GH3 cells. Time-course studies and suppression of TGF-beta-induced VEGF production by cycloheximide suggest that TGF-beta induces de novo synthesis of VEGF in folliculostellate cells, which is completely blocked by dexamethasone. In primary rat pituitary cell cultures, TGF-beta1 and -beta3 stimulated VEGF production. TGF-beta stimulation of VEGF production by folliculostellate cells could modulate intrapituitary vascular permeability and integrity as well as angiogenesis in an auto-/paracrine manner.