Amyotrophic Lateral Sclerosis (ALS) is a fatal and progressive neurodegenerative disease affecting motor neurons in motor cortex and spinal cord. The etiology of ALS is multifactorial; however, growing evidence points to oxidative stress and neuroinflammation as pathological features mainly contributing to neurodegeneration. Oxidative stress promotes an aberrant modulation of several genes and proteins which, in turn, elicits a pro-inflammatory environment, involving both the central nervous system and peripheral immune system. Next to soluble factors, such as cytokines and chemokines, extracellular vesicles (EVs) secreted by both nervous and immune cells are likely to take part in the spreading of the damage and inflammation. Actually, several compounds with antioxidant properties are under investigation as potential treatment of neurodegenerative diseases, including curcumin. Despite its great therapeutic potential, medical use of curcumin display some limits, including poor bioavailability; however, this issue could be solved with the use of nanocarriers. The aim of the project is to characterize the role of EVs in ALS inflammation in an in vitro system, and to evaluate the antioxidant effects of curcumin-loaded nanoparticles. To date, ALS is still a poorly understood disease, and therapies currently available are largely ineffective. Unravelling the mechanisms involved in oxidative stress and inflammation may contribute to the understanding of ALS pathogenesis and have an impact on the pursuit of new therapeutic strategies.
Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease affecting primarily upper and lower motor neurons, which onset generally occurs in middle life, leading to progressive muscle atrophy till paralysis and respiratory failure [Ralli M et al, 2019]. About 10% of ALS cases are familial (fALS) and display heritability in an autosomal dominant manner; the remaining 90% are sporadic (sALS) and have no family history [Kim G et al, 2020]. Next-Generation-Sequencing techniques are contributing to understand ALS genetics: in fact, more than 50 potentially causative genes have been identified, including SOD1 (encoding the copper-zinc superoxide dismutase 1, involved in ROS detoxification), C9ORF73 (encoding a product which function is still poorly understood), FUS, and TARDBP (encoding RNA and DNA/RNA binding proteins, respectively) as the most common mutated genes found in the disease [Zou ZY et al, 2017]. However, as a complex and multifactorial disease, etiology of ALS is still largely unknown, especially for sporadic cases, and several hypotheses have been proposed regarding its pathogenesis. These include impaired DNA repair [Hill SJ et al, 2016], RNA metabolism and protein homeostasis [Zhao M et al, 2018]; defects in nucleocytoplasmic and axonal transport [Kim HJ, 2017]; excitotoxicity [King AE et al, 2016]; mitochondrial dysfunction and oxidative stress [Bozzo F et al, 2016]; and neuroinflammation [Liu J, 2017]. Recently, oxidative stress, neuroinflammation and peripheral immune system activation have emerged as key players in ALS neurodegeneration [Beers DR, 2019]: beside soluble factors, exosomes and microvesicles, containing proteins, lipids, and different types of RNAs, and released from both nervous and immune cells, seem to be involved in sustaining the inflammation and have gained interest for the understanding of ALS pathogenesis [Brites D, 2015]. To date, the interplay between motor neurons and microglia cells through exosomes containing misfolded and mutant copper-zinc superoxide dismutase 1 (mSOD1) has been shown to take part in disease outcome and progression, impacting on microglia polarization [Pinto S et al, 2017]; nevertheless, only few studies have investigated the effects of motor neuron-derived exosomes in other cell function [Madison RD et al, 2014; Korkut C et al, 2013]. Among peripheral immune system cells, monocytes appear to be deregulated even before disease onset and to migrate from periphery to central nervous system of ALS patients [Zondler L et al, 2016]; however, the trigger of such dysfunction is still unexplored and, as exosomes are abundant in all body fluids, including serum, it is likely that they could interact with blood cells and could be potential immune messengers in ALS pathogenesis [Robbins PD, 2014]. On the other side, the intrinsic capability of EVs to cross the blood-brain barrier (BBB), a vascular network preventing drugs or toxins from reaching the brain, makes EVs a promising tool in therapy development [Gagliardi D et al, 2020]. In this context, curcumin, a polyphenol compound with antioxidant and anti-inflammatory activity, has been considered an interesting candidate as treatment for neurodegenerative disorders: however, its poor bioavailability and limited BBB permeability pushed forward to propose nanocarriers as curcumin delivering systems [Maiti P et al, 2018]. Despite several mechanisms of the involvement of EVs in ALS pathophysiology are still under investigation, the identification and characterization of circulating extracellular vesicles as mediators of neuroinflammation is imperative and may be useful for the development of new non-invasive diagnostic biomarkers or the design of new potential therapeutic strategies, including the use of nanocarriers for the delivery of antioxidant molecules, such as curcumin [Mejzini R et al, 2019]. The aim of the project consists in the development of an in vitro system recapitulating a new and still unknown ALS pathogenic feature, highlighting the role of extracellular vesicles in inflammation. To date, only few studies have investigated the role of EVs in ALS pathogenesis and, since ALS is an incurable and complex disease, the understanding of the processes contributing to the inflammation could be of great relevance. Moreover, the use of nano-delivered curcumin may represent a new drug delivery strategy and a potential treatment for such disease.