Potential Role of Cytochrome c and Tryptase in Psoriasis and Psoriatic Arthritis Pathogenesis: Focus on Resistance to Apoptosis and Oxidative Stress

Psoriasis (PsO) is an autoimmune disease characterized by keratinocyte proliferation, chronic inflammation and mast cell activation. Up to 42% of patients with PsO may present psoriatic arthritis (PsA). PsO and PsA share common pathophysiological mechanisms: keratinocytes and fibroblast-like synoviocytes are resistant to apoptosis: this is one of the mechanism facilitating their hyperplasic growth, and at joint level, the destruction of articular cartilage, and bone erosion and/or proliferation. Several clinical studies regarding diseases characterized by impairment of cell death, either due to apoptosis or necrosis, reported cytochrome c release from the mitochondria into the extracellular space and finally into the circulation. The presence of elevated cytochrome c levels in serum has been demonstrated in diseases as inflammatory arthritis, myocardial infarction and stroke, and liver diseases. Cytochrome c is a signaling molecule essential for apoptotic cell death released from mitochondria to the cytosol allowing the interaction with protease, as the apoptosis protease activation factor, which lead to the activation of factor-1 and procaspase 9. It has been demonstrated that this efflux from the mitochondria is crucial to start the intracellular signaling responsible for apoptosis, then to the activation of the inflammatory process. Another inflammatory marker, the tryptase, a trypsin-like serine protease produced by mast cells, is released during inflammation, leading to the activation of several immune cells through proteinase-activated receptor-2. In this review, we aimed at discussing the role played by cytochrome c and tryptase in PsO and PsA pathogenesis. To this purpose, we searched pathogenetic mechanisms in PUBMED database and review on oxidative stress, cytochrome c and tryptase and their potential role during inflammation in PsO and PsA. To this regard, the cytochrome c release into the extracellular space and tryptase may have a role in skin and joint inflammation

Metabolites

An altered amino acid metabolism has been described in frail older adults which may contribute to muscle loss and functional decline associated with frailty. In the present investigation, we compared circulating amino acid profiles of older adults with physical frailty and sarcopenia (PF&S, = 94), frail/pre-frail older adults with type 2 diabetes mellitus (F-T2DM, = 66), and robust non-diabetic controls ( = 40). Partial least squares discriminant analysis (PLS-DA) models were built to define the amino acid signatures associated with the different frailty phenotypes. PLS-DA allowed correct classification of participants with 78.2 ± 1.9% accuracy. Older adults with F-T2DM showed an amino acid profile characterized by higher levels of 3-methylhistidine, alanine, arginine, ethanolamine, and glutamic acid. PF&S and control participants were discriminated based on serum concentrations of aminoadipic acid, aspartate, citrulline, cystine, taurine, and tryptophan. These findings suggest that different types of frailty may be characterized by distinct metabolic perturbations. Amino acid profiling may therefore serve as a valuable tool for frailty biomarker discovery

Cerium Oxide Nanoparticles Reduce Microglial Activation and Neurodegenerative Events in Light Damaged Retina.

The first target of any therapy for retinal neurodegeneration is to slow down the progression of the disease and to maintain visual function. Cerium oxide or ceria nanoparticles reduce oxidative stress, which is known to play a pivotal role in neurodegeneration. Our aim was to investigate whether cerium oxide nanoparticles were able to mitigate neurodegeneration including microglial activation and related inflammatory processes induced by exposure to high intensity light. Cerium oxide nanoparticles were injected intravitreally or intraveinously in albino Sprague-Dawley rats three weeks before exposing them to light damage of 1000 lux for 24 h. Electroretinographic recordings were performed a week after light damage. The progression of retinal degeneration was evaluated by measuring outer nuclear layer thickness and TUNEL staining to quantify photoreceptors death. Immunohistochemical analysis was used to evaluate retinal stress, neuroinflammatory cytokines and microglial activation. Only intravitreally injected ceria nanoparticles were detected at the level of photoreceptor outer segments 3 weeks after the light damage and electoretinographic recordings showed that ceria nanoparticles maintained visual response. Moreover, this treatment reduced neuronal death and "hot spot" extension preserving the outer nuclear layer morphology. It is noteworthy that in this work we demonstrated, for the first time, the ability of ceria nanoparticles to reduce microglial activation and their migration toward outer nuclear layer. All these evidences support ceria nanoparticles as a powerful therapeutic agent in retinal neurodegenerative processes

SUN-717 SG-2 a Novel Multi-Target Directed Ligand (MTDL) for the Treatment of Neurodegenerative Diseases (NDDS)

Abstract NDDs are progressive multifactorial disorders that impair memory, cognition, movements, and general functioning. This deterioration is mostly due to inflammation triggered by aberrant protein deposition, oxidative stress and modification in lipid pathways. Because of these multifactorial aspects, the development of multi-target directed ligand (MTDL) could represent a potential strategy for the treatment of NDDs. Recently, the thyronamine-like analog SG-2, originally developed as a synthetic TAAR1 agonist, has revealed to efficiently reprogram lipid metabolism and to produce memory-enhancement in mice1. Long-term potentiation (LTP) is one of the basic mechanisms of memory. LTP is inhibited by beta-Amyloid oligomers (Aβ), and in the early stage of AD it is selectively impaired in the entorhinal cortex (EC). In the present study, to further expand our knowledge on the potential of this novel analog to act as a neuroprotective agent, we investigated if administration of SG-2 has any effect on LTP in EC of a transgenic model of AD (hAPP-J20 mouse). Extracellular in vitro recordings were performed in EC slices from 2 month-old APP-J20 mice: field potentials were evoked in layer II after stimulation of the same layer and LTP was elicited by high frequency stimulation (HFS), consisting of three trains of 100 pulses at 100Hz. SG-2 (1 or 5μM) was administered for 10 minutes, starting 5 minutes before the delivery of HFS. LTP cannot be elicited by HFS in mhAPP slices perfused with artificial cerebrospinal fluid (ACSF) alone. When we tried to rescue LTP in mhAPP slices using SG2 at the lowest concentration (1µM), 10 min perfusion with SG2 was not effective. In contrast, a higher concentration of SG2 (5 μM), rescued LTP to a level that was significantly higher than that observed in mhAPP slices alone (n=6; p=0.046), as well as in mhAPP slices perfused with SG2 1 μM (n=5; p=0.043). Our results suggest that SG-2 plays a neuroprotective effect, rescuing Aβ-induced neuronal dysfunction and might open new perspective in the study of AD. Metabolic reprogramming and neuroprotective functions for the histone deacetylase SIRT6 are well known, and a reduction of SIRT6 expression has been observed in patients with AD. Exposure of human neuroblastoma (SH-SY5Y) cells to SG-2 (1 or 10 μM) resulted in significant (p=0.044) over-expression of SIRT6, and concomitant activation of AMPK leading to the inhibition of mTOR phosphorylation, further underlying potential for SG-2 as a multi-target neuroprotective ligand

Functional analysis.

<p>Panel A. Mean b-wave fERG amplitude (μV) plotted against luminance (cd/m²). The mean ± SE is reported for each experimental group (n = 6 for each group). Dash dot-dot and continuous line represent the trend of LD Control group, respectively. Panel B: Representative fERG response in the three experimental conditions (CeO₂ NP, Saline, Vein) at 3 cd/m². Statistical analysis was performed, for each group versus CeO₂ NP, using one-way ANOVA followed by Tukey test. *P< 0.05.</p

Microglia and TUNEL images in LD and intravenous injection.

<p>Immunolabelling for microglia (anti-Iba1) in green and apoptotic nuclei in red. The figure shows two different parts of superior retina, in each experimental group, one week after BCL. The arrows indicate the presence of activated microglia in the ONL. Panels A-B: “hot spot” region in LD and Vein; panels A1-B1: “near hot spot” in LD and Vein; panel C: control. ONL: outer nuclear layer, INL: inner nuclear layer, GCL: ganglion cell layer.</p

Electronic and structural properties of CeO₂ Nanoparticles.

<p>Decomposition of the XPS Ce 3<i>d</i> core level into Ce³⁺ and Ce⁴⁺ emission (left panel) and XRD pattern (right panel) for the as prepared CeO_<b>2</b> nanoparticles.</p

Microglia and TUNEL images in intravitreal injection.

<p>Panels A-B: “hot spot” region in CeO₂ NP and Saline group; Panels A1-B1: “near hot spot” in CeO₂ NP and Saline; panel C: Control. Abbreviations and arrows as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140387#pone.0140387.g006" target="_blank">Fig 6</a>.</p

Thickness of ONL in all experimental conditions.

<p>Representative sections from superior retina (1 mm from optic disc) of Control (A), CeO₂ NP: (B), Saline: (C), Vein: injected trough the tail vein (D) and LD (E). In all panels nuclei, labelled with propidium iodide, are reported in black and white. Panel F shows ONL thickness as a function of distance from the superior to the inferior edge crossing optic disc. Measurements are expressed as ratio ONL/total retina thickness. Statistical analysis was performed by one-way ANOVA followed by Tukey test for each group versus CeO₂ NP group. Data are shown as mean ± SE; (n = 6 for each group). *P< 0.05, **P<0.01. ONL: outer nuclear layer, INL: inner nuclear layer, GCL: ganglion cell layer.</p

FGF2 immunolabelling in “hot spot” region.

<p>In panel A: Control, panel B: CeO₂ NP, panel C: Saline, panel D: Vein and panel E: LD, with a scale bar of 50 μm. Panels A1-B1-C1-D1-E1: High magnification with a scale bar of 10 μm. ONL: outer nuclear layer, INL: inner nuclear layer, GCL: ganglion cell layer.</p