Altered inflammasome machinery as a key player in the perpetuation of Rett syndrome oxinflammation

Abstract

Rett syndrome (RTT) is a progressive neurodevelopmental disorder mainly caused by mutations in the X-linked MECP2 gene. RTT patients show multisystem disturbances associated with an oxinflammatory status. Inflammasomes are multi-protein complexes, responsible for host immune responses against pathogen infections and redox-related cellular stress. Assembly of NLRP3/ASC inflammasome triggers pro-caspase-1 activation, thus, resulting in IL-1β and IL-18 maturation. However, an aberrant activation of inflammasome system has been implicated in several human diseases. Our aim was to investigate the possible role of inflammasome in the chronic subclinical inflammatory condition typical of RTT, by analyzing this complex in basal and lipopolysaccharide (LPS)+ATP-stimulated primary fibroblasts, as well as in serum from RTT patients and healthy volunteers. RTT cells showed increased levels of nuclear p65 and ASC proteins, pro-IL-1β mRNA, and NLRP3/ASC interaction in basal condition, without any further response upon the LPS + ATP stimuli. Moreover, augmented levels of circulating ASC and IL-18 proteins were found in serum of RTT patients, which are likely able to amplify the inflammatory response. Taken together, our findings suggest that RTT patients exhibited a challenged inflammasome machinery at cellular and systemic level, which may contribute to the subclinical inflammatory state feedback observed in this pathology.

Alterations of mitochondrial bioenergetics, dynamics, and morphology support the theory of oxidative damage involvement in autism spectrum disorder

“…Primary cultures of dermal fibroblasts were obtained from 3‐mm skin biopsies taken during the periodic clinical checks‐up for the ASD patients or during health checks or by donations for the healthy donors. As previously described, 8 fibroblasts were cultured in Dulbecco's Modification of Eagle's Medium (DMEM) (cat. 10‐014‐CV, Corning, New York, NY, USA) supplemented with 10% of fetal bovine serum (FBS) (cat.…”

“…H1009, Sigma‐Aldrich, St. Louis, MO, USA) for different time points. Total, cytoplasmic and nuclear extracts were obtained as previously described 8 . Briefly, cells were lysed in Radio‐Immunoprecipitation Assay (RIPA) buffer (cat.…”

“…As previously reported, 8 total RNA was extracted from fibroblasts by using Aurum Total RNA Mini Kit (cat.732‐6820, Bio‐Rad Laboratories, Inc.), removing genomic contamination by using DNase I. cDNA synthesis was performed with 1 μg of total RNA using iScript Reverse Transcription kit (cat. 1708841, Bio‐Rad Laboratories, Inc), according to the manufacturer's instructions.…”

“…Indeed, the reorganization of the mitochondrial network through the mitochondrial dynamics processes reflects the cellular metabolic status, and therefore, is critical under stress conditions in order to sustain the increased cellular energy demands 7 . Impaired mitochondrial dynamics and quality control processes are directly implicated in the major neurodegenerative diseases including Parkinson's, Alzheimer's and Huntington's disease 8 . While the occurrence of mitochondrial dysfunction is well established in ASD, not all aspects of mitochondrial physiology have been fully examined in these patients.…”

MeCP2 deficiency exacerbates the neuroinflammatory setting and autoreactive response during an autoimmune challenge: implications for Rett Syndrome

“…Little is known about the role of this cytokine in disorders linked to MeCP2 mutations; however, the role of the inflammasome and its products (IL-1 and IL-18) in RTT pathogenesis has been recently explored. Pecorelli et al demonstrated that fibroblasts isolated from RTT patients show an activated inflammasome machinery even under baseline conditions [46]. These data suggest that MeCP2 is an essential regulatory factor for the activation of the inflammasome and for preventing the perpetuation of an inflammatory state.…”