Vincenzo Dinallo

Neuroprotective Effect of Neuropeptide Y against Beta-Amyloid 25–35 Toxicity in SH-SY5Y Neuroblastoma Cells Is Associated with Increased Neurotrophin Production

Background: In the central nervous system, several neuropeptides are believed to be involved in the pathophysiology of Alzheimer’s disease (AD). Among them, neuropeptide Y (NPY) is a small peptide widely distributed throughout the brain, where it serves as a neurotransmitter and/or a modulator of several neuroendocrine functions. More recently, NPY has generated interest because of its role in neuroprotection against excitotoxicity and modulation of neurogenesis. Interestingly, these effects are also influenced by neurotrophins, critical molecules for the function and survival of neurons that degenerate in AD. Objective: Our purpose was to investigate whether NPY might be a neuroprotective agent in AD and whether neurotrophins are involved in NPY-induced neuroprotection. Methods: To test this hypothesis, we exposed the SH-SY5Y neuroblastoma cell line to toxic concentrations of β-amyloid (Aβ) peptide fragment 25–35 (Aβ25–35) and measured cell survival and neurotrophin expression before and after a preincubation with NPY in the growth medium. Results: Our results demonstrated that preincubation with NPY prevented cell loss due to the toxic effect of Aβ25–35. Moreover, while intracellular production of nerve growth factor and brain-derived neurotrophic factor were reduced by Aβ, NPY restored or even increased neurotrophin protein and mRNA in SH-SY5Y cells. Conclusion: In conclusion, this study demonstrates that NPY increases the survival of SH-SY5Y neuroblastoma cells and counteracts the toxic effect of Aβ. In addition, NPY restores the neurotrophin levels in these cells. Although preliminary, these observations might be useful to understand the pathology of Alzheimer’s and/or develop new therapeutic strategies.

Paroxetine rapidly modulates the expression of brain-derived neurotrophic factor mRNA and protein in a human glioblastoma-astrocytoma cell line.

Neuronal upregulation of the brain-derived neurotrophic factor (BDNF) gene appears to be a crucial factor for the efficacy of antidepressants. However, besides neurons, little information is present on the modulation of BDNF by antidepressants at RNA and protein levels in other cell types of the central nervous system. Glial cells are able to store and release BDNF, and it has been hypothesized that glial dysfunction may contribute to the etiopathogenesis of depression. Thus, in this study we used the human glioblastoma-astrocytoma cell line U87 exposed to the antidepressant drug paroxetine, and evaluated BDNF mRNA and protein expression. In addition, since the BDNF gene can be posttranscriptionally modulated by a family of microRNA, we also evaluated the levels for one of these microRNA (miR-30a-5p) in the U87 cell line during paroxetine treatment. We found that paroxetine treatment rapidly increased BDNF in U87 cells, resulting from an induction of BDNF mRNA expression and de novo protein synthesis, and that these increases occurred in a time-dependent manner. Paroxetine effects were evident at 6 h of incubation for BDNF mRNA and at 12 h for BDNF protein. In addition, the transcriptional BDNF inhibitor miR-30a-5p was also overexpressed at 6 and 12 h of paroxetine incubation. These findings indicate that the U87 cell line, an in vitro model of glial cells, rapidly responds to paroxetine by increasing BDNF production, and that these effects are potentially limited by microRNA induction. These data may contribute to explain the action of paroxetine on cells of nonneuronal origin.

Sodium chloride–enriched Diet Enhanced Inflammatory Cytokine Production and Exacerbated Experimental Colitis in Mice

Background and Aim: Environmental factors are supposed to play a decisive role in the pathogenesis of inflammatory bowel diseases [IBDs]. Increased dietary salt intake has been linked with the development of autoimmune diseases, but the impact of a salt-enriched diet on the course of IBD remains unknown. In this study, we examined whether high salt intake alters mucosal cytokine production and exacerbates colitis. Methods: Normal intestinal lamina propria mononuclear cells [LPMCs] were activated with anti-CD3/CD28 in the presence or absence of increasing concentrations of sodium chloride [NaCl] and/or SB202190, a specific inhibitor of p38/MAP Kinase. For in vivo experiments, a high dose of NaCl was administered to mice 15 days before induction of trinitrobenzene-sulfonic acid [TNBS]-colitis or dextran sulfate sodium [DSS]-colitis. In parallel, mice were given SB202190 before induction of TNBS-colitis. Transcription factors and effector cytokines were evaluated by flow-cytometry and real-time PCR. Results: IL-17A, IL-23R, TNF-&agr;, and Ror-&ggr;T were significantly increased in human LPMCs following NaCl exposure, while there was no significant change in IFN-&ggr;, T-bet or Foxp3. Pharmacologic inhibition of p38/MAPK abrogated the NaCl-inducing effect on LPMC-derived cytokines. Mice receiving the high-salt diet developed a more severe colitis than control mice, and this effect was preventable by SB202190. Conclusions: Our data indicated that exposure of intestinal mononuclear cells to a high-NaCl diet enhanced effector cytokine production and contributed to the exacerbation of experimental colitis in mice.

Aryl hydrocarbon receptor-driven signals inhibit collagen synthesis in the gut

Fibrostrictures (FS) are a major complication of Crohns disease (CD). Pathogenesis of FS is not fully understood, but activation of fibroblasts and excessive collagen deposition are crucial in the development of FS. Here, we investigated the role of aryl hydrocarbon receptor (AhR) in intestinal fibrosis. AhR RNA and protein expression were evaluated in intestinal fibroblasts of CD patients and controls. CD fibroblasts were stimulated with TGF‐β1 or TNF‐α in the presence or absence of the AhR activator Ficz, an AhR antagonist CH223191, or a specific AhR‐silencing RNA. In CD fibroblasts, TGF‐β1 and TNF‐α increased Col1A1, Col3A1 and α‐SMA transcripts and collagen secretion and this effect was reduced by Ficz and upregulated by CH22319. TGF‐β1 or TNF‐α induced activation of p38 and ERK1/2 MAP kinases was decreased by Ficz and increased by CH223191. The inhibitory effect of Ficz on Map kinase activation and collagen induction was abolished by AhR silencing. To assess the role of AhR in vivo, mice with trinitrobenzene‐sulfonic‐acid induced colonic fibrosis were given Ficz or CH223191. Mice given either Ficz or CH223191 produced less or more collagen respectively as compared with control mice. Our results indicate that AhR is a negative regulator of profibrotic signals in the gut.

CCL20 Is Negatively Regulated by TGF-β1 in Intestinal Epithelial Cells and Reduced in Crohn’s Disease Patients With a Successful Response to Mongersen, a Smad7 Antisense Oligonucleotide

Background and Aims The chemokine CCL20 is over-produced in epithelium of Crohns disease [CD] patients and contributes to recruiting immune cells to inflamed gut. Tumour necrosis factor-α [TNF-α] is a powerful inducer of CCL20 in intestinal epithelial cells. In CD, high levels of Smad7 block the activity of transforming growth factor-β1 [TGF-β1], a negative regulator of TNF signalling. We investigated whether intestinal epithelial cell-derived CCL20 is negatively regulated by TGF-β1 and whether Smad7 knock-down reduces CCL20 in CD. Methods CCL20 was evaluated in NCM460, a normal colonic epithelial cell line, stimulated with TGF-β1 and TNF-α, and in Smad7 over-expressing NCM460 cells. CCL20 and Smad7 expression were assessed in sections of CD intestinal specimens by immunochemistry, and in CD colonic explants treated with mongersen, a Smad7 antisense oligonucleotide. CCL20 was examined in serum samples taken from 95 of 166 active CD patients receiving mongersen or placebo for 2 weeks and participating in a phase II, multicentre, double-blind, placebo-controlled study. Results CCL20 expression was increased by TNF-α, and this effect was inhibited by TGF-β1 in NCM460 cells, but not in Smad7 over-expressing NCM460 cells. In CD, epithelium CCL20 and Smad7 co-localised, and treatment of CD explants with mongersen reduced CCL20 production. During follow-up, in responders to mongersen, serum CCL20 levels significantly decreased, whereas patients without response/remission to mongersen and placebo patients did not have change in CCL20. Conclusions TGF-β1 reduces intestinal epithelial cell-derived CCL20 production, an effect abrogated by Smad7. CD patients responding to mongersen demonstrated a reduction in serum CCL20.

The TGF-β/Smad System in IBD Pathogenesis

Abstract:In Crohns disease and ulcerative colitis, the tissue-damaging destructive immune response is sustained by defects of counterregulatory mechanisms, which normally attenuate inflammatory pathways and promote repair of mucosal injury. One such mechanism involves transforming growth factor-&bgr;1 (TGF-&bgr;1), a cytokine that is produced by multiple cell types and targets both immune and nonimmune cells. Both in vitro and in vivo studies strongly support the role of TGF-&bgr;1 as a negative regulator of mucosal inflammation and indicate that defective production/activity of this cytokine can lead to the development of or exacerbate colitis. Interestingly, in the inflamed intestine of patients with inflammatory bowel disease, TGF-&bgr;1 expression is upregulated but TGF-&bgr;1–mediated immunosuppression is markedly impaired because of high Smad7, an intracellular inhibitor of TGF-&bgr;1–associated signaling. Consistently, knockdown of Smad7 with a specific antisense oligonucleotide restores TGF-&bgr;1 activity, thus leading to decreased production of inflammatory cytokines in both colitic mice and inflammatory bowel disease patients and attenuates clinical activity in Crohns disease patients. In this article, we review data supporting the role of Smad7 in the pathogenesis of inflammatory bowel disease and discuss whether inhibition of Smad7 is therapeutically useful in Crohns disease and how the benefit/risk of such an intervention should be monitored in the patients.

Smad7 knockdown activates protein kinase RNA-associated eIF2α pathway leading to colon cancer cell death

Upregulation of Smad7, an inhibitor of transforming growth factor-β1 (TGF-β1), occurs in sporadic colorectal cancer (CRC) and knockdown of Smad7 inhibits CRC cell growth, a phenomenon that associates with decreased expression of cell division cycle 25 homolog A and arrest of cells in the S phase of the cell cycle. These findings occur in CRC cells unresponsive to TGF-β1, thus suggesting the existence of a Smad7-mediated TGF-β1-independent mechanism that controls CRC cell behavior. Here we show that Smad7 inhibition with a specific Smad7 antisense oligonucleotide upregulates eukaryotic translation initiation factor 2α (eIF2α) phosphorylation, a transcription factor involved in the regulation of cell cycle arrest and induction of cell death, and induces activating transcription factor 4 (ATF4) and CCAAT/enhancer binding protein homology protein (CHOP), two downstream targets of eIF2α. Among the upstream kinases that control eIF2α phosphorylation, the serine–threonine protein kinase RNA (PKR), but not general control non-derepressible 2 (GCN2) and protein kinase RNA-like endoplasmic reticulum kinase (PERK), is activated by Smad7 knockdown. PKR silencing abolishes Smad7 antisense-induced eIF2α phosphorylation and ATF4/CHOP induction, thereby preventing Smad7 antisense-driven cell death. Smad7 inhibition diminishes interaction of PKR with protein kinase inhibitor p58 (p58IPK), a cellular inhibitor of PKR, but does not change the expression and/or activity of other factors involved in the control of PKR activation. These findings delineate a novel mechanism by which Smad7 knockdown promotes CRC cell death.

Plasmin system of Alzheimer’s disease patients: CSF analysis

Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder characterized by the extracellular deposit of Amyloid beta (Aβ), mainly of the Amyloid beta1–42 (Aβ1–42) peptide in the hippocampus and neocortex leading to progressive cognitive decline and dementia. The possible imbalance between the Aβ production/degradation process was suggested to contribute to the pathogenesis of AD. Among others, the serine protease plasmin has shown to be involved in Aβ1–42 clearance, a hypothesis strengthened by neuropathological studies on AD brains. To explore whether there is a change in plasmin system in CSF of AD patients, we analyzed CSF samples from AD and age-matched controls, looking at plasminogen, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) protein levels and t-PA and urokinase plasminogen activator (u-PA) enzymatic activities. We also measured Aβ1–42, total-tau and phospho-tau 181 CSF levels and sought for a possible relationship between them and plasmin system values. Our findings showed that t-PA, plasminogen and PAI-1 levels, as t-PA enzymatic activity, remained unchanged in AD with respect to controls; u-PA activity was not detected. We conclude that CSF analysis of plasminogen system does not reflect changes observed post-mortem. Unfortunately, the CSF detection of plasmin system could not be a useful biomarker for either AD diagnosis or disease progression. However, these findings do not exclude the possible involvement of the plasmin system in AD.

Smad7 Knockdown Restores Aryl Hydrocarbon Receptor-mediated Protective Signals in the Gut.

BACKGROUND AND AIM In Crohns disease [CD], the pathological process is driven by an excessive immune response that is poorly counterbalanced by regulatory mechanisms. One such a mechanism involves aryl hydrocarbon receptor [AhR], a transcription factor that delivers protective signals in the gut. Expression of AhR is reduced in CD lamina propria mononuclear cells [LPMC] even though factors accounting for such a defect remain unknown. Since CD LPMC express elevated levels of Smad7, an inhibitor of transforming growth factor beta 1 [TGF-β1] activity, and TGF-β1 regulates AhR in other systems, we examined the link between AhR and Smad7 in the gut. METHODS AhR and interleukin [IL]-22 were evaluated in normal LPMC stimulated with TGF-β1 and 6-formylindolo[3,2-b]carbazole [Ficz], an activator of AhR, and in CD LPMC incubated with a Smad7 antisense oligonucleotide and then stimulated with Ficz and TGF-β1. AhR and IL-22 expression was evaluated in LPMC of Smad7-transgenic mice. Finally, we evaluated the protective effect of Ficz on colitis in RAG1 mice injected with naïve or Smad7-overexpressing T cells. RESULTS In normal LPMC, TGF-β1 induced AhR and this event was associated with increased production of IL-22 following stimulation with Ficz. Treatment of CD LPMC with Smad7 antisense oligonucleotide enabled TGF-β1 to enhance AhR expression. Consistently, AhR expression and Ficz-induced IL-22 production were markedly reduced in T cells of Smad7-transgenic mice. In RAG1 mice, Ficz ameliorated colitis induced by wild type T cells but did not affect colitis induced by transfer of Smad7-overexpressing T cells. CONCLUSIONS The inverse correlation between Smad7 and AhR expression helps to propagate inflammatory signals in the gut.

New insights into the pharmacokinetics of intravenous busulfan in children with sickle cell anemia undergoing bone marrow transplantation

Busulfan (Bu) is an integral part of conditioning regimens for patients with sickle cell anemia (SCA) undergoing transplantation. Patients with SCA might predispose to transplant‐related neurological and pulmonary toxicities due to pre‐existing disease‐related cerebrovascular and lung injury. Bu therapy appears to be an important contributing factor in this context.