Cytokine Dysregulation in MECP2- and CDKL5-Related Rett Syndrome: Relationships with Aberrant Redox Homeostasis, Inflammation, and ω-3 PUFAs.

An involvement of the immune system has been suggested in Rett syndrome (RTT), a devastating neurodevelopmental disorder related to oxidative stress, and caused by a mutation in the methyl-CpG binding protein 2 gene (MECP2) or, more rarely, cyclin-dependent kinase-like 5 (CDKL5). To date, it is unclear whether both mutations may have an impact on the circulating cytokine patterns. In the present study, cytokines involved in the Th1-, Th2-, and T regulatory (T-reg) response, as well as chemokines, were investigated in MECP2- (MECP2-RTT) (n = 16) and CDKL5-Rett syndrome (CDKL5-RTT) (n = 8), before and after ω-3 polyunsaturated fatty acids (PUFAs) supplementation. A major cytokine dysregulation was evidenced in untreated RTT patients. In MECP2-RTT, a Th2-shifted balance was evidenced, whereas in CDKL5-RTT both Th1- and Th2-related cytokines (except for IL-4) were upregulated. In MECP2-RTT, decreased levels of IL-22 were observed, whereas increased IL-22 and T-reg cytokine levels were evidenced in CDKL5-RTT. Chemokines were unchanged. The cytokine dysregulation was proportional to clinical severity, inflammatory status, and redox imbalance. Omega-3 PUFAs partially counterbalanced cytokine changes, as well as aberrant redox homeostasis and the inflammatory status. RTT is associated with a subclinical immune dysregulation as the likely consequence of a defective inflammation regulatory signaling system.

Red blood cells in Rett syndrome: oxidative stress, morphological changes and altered membrane organization.

In this review, we summarize the current evidence on the erythrocyte as a previously unrecognized target cell in Rett syndrome, a rare (1:10 000 females) and devastating neurodevelopmental disorder caused by loss-of-function mutations in a single gene (i.e. MeCP2, CDKL5, or rarely FOXG1). In particular, we focus on morphological changes, membrane oxidative damage, altered membrane fatty acid profile, and aberrant skeletal organization in erythrocytes from patients with typical Rett syndrome and MeCP2 gene mutations. The beneficial effects of ω-3 polyunsaturated fatty acids (PUFAs) are also summarized for this condition to be considered as a 'model' condition for autism spectrum disorders.

Altered erythrocyte membrane fatty acid profile in typical Rett syndrome: effects of omega-3 polyunsaturated fatty acid supplementation.

This study mainly aims at examining the erythrocyte membrane fatty acid (FAs) profile in Rett syndrome (RTT), a genetically determined neurodevelopmental disease. Early reports suggest a beneficial effects of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) on disease severity in RTT. A total of 24 RTT patients were assigned to ω-3 PUFAs-containing fish oil for 12 months in a randomized controlled study (average DHA and EPA doses of 72.9, and 117.1mg/kgb.w./day, respectively). A distinctly altered FAs profile was detectable in RTT, with deficient ω-6 PUFAs, increased saturated FAs and reduced trans 20:4 FAs. FAs changes were found to be related to redox imbalance, subclinical inflammation, and decreased bone density. Supplementation with ω-3 PUFAs led to improved ω-6/ω-3 ratio and serum plasma lipid profile, decreased PUFAs peroxidation end-products, normalization of biochemical markers of inflammation, and reduction of bone hypodensity as compared to the untreated RTT group. Our data indicate that a significant FAs abnormality is detectable in the RTT erythrocyte membranes and is partially rescued by ω-3 PUFAs.

Morphological changes and oxidative damage in Rett Syndrome erythrocytes.

BACKGROUND: Hypoxemia and increased oxidative stress (OS) have been reported in Rett Syndrome (RTT), a genetical neurodevelopmental disorder. Although OS and hypoxemia can lead to red blood cells (RBCs) shape abnormalities, no information on RBCs morphology in RTT exists. Here, RBCs shape was evaluated in RTT patients and healthy subjects as a function of OS markers, blood oxygenation, pulmonary gas exchange, and cardio-respiratory parameters. METHODS: RBCs morphology was evaluated by Scanning Electron Microscopy. Intraerythrocyte and plasma non protein-bound iron (NPBI), esterified F(2)-Isoprostanes (F(2)-IsoPs), 4-HNE protein adducts (4-HNE PAs) were measured. Pulmonary oxygen gradients and PaO(2) were evaluated by gas analyzers and cardiopulmonary variables by pulse oximetry. In RTT patients these parameters were assessed before and after ω-3 polyunsaturated fatty acids (ω-3 PUFAs) administration. RESULTS: Altered RBCs shapes (leptocytes) and increased NPBI were present in RTT, together with increased erythrocyte membrane esterified F(2)-IsoPs and 4-HNE PAs. Abnormal erythrocyte shapes were related to OS markers levels, pulmonary gas exchange, PaO(2) and cardio-respiratory variables. After ω-3 PUFAs, a decrease of leptocytes was accompanied by a progressive increase in reversible forms of RBCs. This partial RBCs morphology rescue was related to decreased OS damage markers, improved pulmonary oxygen exchange, and cardiopulmonary physiology. CONCLUSIONS: These findings indicate that in RTT 1) RBCs shape is altered; 2) the OS-hypoxia diad is critical in generating altered RBCs shape and membrane damage; 3) ω-3 PUFAs are able to partially rescue RBCs morphology and the OS-derived damage. GENERAL SIGNIFICANCE: RBCs morphology is an important biosensor for OS imbalance and chronic hypoxemia.

F4-neuroprostanes mediate neurological severity in Rett syndrome.

BACKGROUND: Rett syndrome (RTT) is a pervasive development disorder, mainly caused by mutations in the methyl-CpG binding protein 2 (MeCP2) gene. No reliable biochemical markers of the disease are available. Here we assess F4-neuroprostanes (F4-NeuroPs), lipid peroxidation products of the docosahexaenoic acid, as a novel disease marker in RTT and correlate it with clinical presentation, MeCP2 mutation type, and disease progression. In addition, we investigate on the impact of ω-3 polyunsaturated fatty acids (ω-3 PUFAs) supplementation on F4-NeuroPs levels. METHODS: A case-control study design was used. A cohort of RTT patients (n=144) exhibiting different clinical presentations, disease stages, and MeCP2 gene mutations were evaluated. F4-NeuroPs were measured in free form using a GC/NICI-MS/MS technique. Plasma F4-NeuroPs levels in patients were compared to healthy controls and related to RTT forms, disease progression, and response to ω-3 PUFAs supplementation. RESULTS: Plasma F4-NeuroPs levels were i) higher in RTT than in controls; ii) increased with the severity of neurological symptoms; iii) significantly elevated during the typical disease progression; iv) higher in MeCP2-nonsense as compared to missense mutation carriers; v) higher in typical RTT as compared to RTT variants; and vi) decreased in response to 12 months ω-3 PUFAs oral supplementation. CONCLUSIONS: Quantification of plasma F4-NeuroPs provides a novel RTT marker, related to neurological symptoms severity, mutation type and clinical presentation.