Influenza vaccination induces autoimmunity against orexinergic neurons in a mouse model for narcolepsy.

Narcolepsy with cataplexy or narcolepsy type 1 is a disabling chronic sleep disorder resulting from the destruction of orexinergic neurons in the hypothalamus. The tight association of narcolepsy with HLA-DQB1*06:02 strongly suggest an autoimmune origin to this disease. Furthermore, converging epidemiological studies have identified an increased incidence for narcolepsy in Europe following Pandemrix® vaccination against the 2009-2010 pandemic 'influenza' virus strain. The potential immunological link between the Pandemrix® vaccination and narcolepsy remains, however, unknown. Deciphering these mechanisms may reveal pathways potentially at play in most cases of narcolepsy. Here, we developed a mouse model allowing to track and study the T-cell response against 'influenza' virus haemagglutinin, which was selectively expressed in the orexinergic neurons as a new self-antigen. Pandemrix® vaccination in this mouse model resulted in hypothalamic inflammation and selective destruction of orexin-producing neurons. Further investigations on the relative contribution of T-cell subsets in this process revealed that haemagglutinin-specific CD4 T cells were necessary for the development of hypothalamic inflammation, but insufficient for killing orexinergic neurons. Conversely, haemagglutinin-specific CD8 T cells could not initiate inflammation but were the effectors of the destruction of orexinergic neurons. Additional studies revealed pathways potentially involved in the disease process. Notably, the interferon-γ pathway was proven essential, as interferon-γ-deficient CD8 T cells were unable to elicit the loss of orexinergic neurons. Our work demonstrates that an immunopathological process mimicking narcolepsy can be elicited by immune cross-reactivity between a vaccine antigen and a neuronal self-antigen. This process relies on a synergy between autoreactive CD4 and CD8 T cells for disease development. This work furthers our understanding of the mechanisms and pathways potentially involved in the development of a neurological side effect due to a vaccine and, likely, to narcolepsy in general.

Dietary antioxidants and fibre intake and depressive symptoms in Iranian adolescent girls.

OBJECTIVE: To investigate the cross-sectional association between dietary intakes of antioxidants and fibre and depressive symptoms among Iranian adolescent girls. DESIGN: A cross-sectional population-based study. SETTING: Primary schools in two different cities located in northeastern Iran (Mashhad and Sabzevar). PARTICIPANTS: A total of 988 adolescent girls aged 12-18 years were included in the study. RESULTS: Subjects with no or minimal depression symptoms had significantly higher dietary intakes of α-carotene (P = 0·01), ß-carotene (P = 0·006), lutein (P = 0·03) and vitamin C (P = 0·04) when compared with subjects with mild-to-severe depression symptoms. Soluble dietary fibre and insoluble dietary fibre intakes were also significantly higher in healthy adolescents compared with those with depression symptoms (P < 0·001). In multivariate-adjusted model 2, the OR (95 % CI) of depressive symptoms were 0·61 (95 % CI 0·37, 1·01), 0·42 (95 % CI 0·26, 0·69), 0·50 (95 % CI 0·31, 0·79), 0·71 (95 % CI 0·44, 1·15), 0·51 (95 % CI 0·32, 0·82) and 0·42 (95 % CI 0·25, 0·68) for the highest v. lowest quartile of vitamin C, ß-carotene, α-carotene, lutein, soluble dietary fibre and insoluble dietary fibre cereal intakes, respectively. CONCLUSIONS: Dietary intake of some antioxidants and dietary fibre intake was inversely associated with depression symptoms among Iranian adolescent girls.

A variant in CYP2R1 predicts circulating vitamin D levels after supplementation with high-dose of vitamin D in healthy adolescent girls.

AIM: The determinants of serum vitamin D seems to be the environmental factors (dietary and supplementary intake and exposure to ultraviolet light) and genetic factors. We aimed to study the relationship between a vitamin D-associated genetic polymorphism and serum 25(OH)D concentrations in healthy adolescent girls in Iran, and its effects on a high-dose supplement of vitamin D. MATERIAL AND METHOD: A total of 616 healthy adolescent girls with mean age 15 received 50,000 IU of vitamin D3 weekly over 9 weeks. Serum vitamin D levels and other metabolic factors were measured at baseline and after the intervention. The genotyping of the CYP2R1 variant (rs10741657) was performed by TaqMan genotyping assays. RESULTS: Regardless of the genetic background, at baseline, 87% of adolescent girls were vitamin D deficient (serum 25(OH)D level < 50 nmol/l). High-dose supplementation with VitD reduced the proportion of girls who were deficient substantially to about 24%. The genetic analysis revealed that although at baseline there was not a gene-vitamin D association ( p trend = 0.1), the response to supplementation appeared to be modulated by this variant ( p trend < 0.001). However, other anthropometric and biochemical measures were not affected by this intervention, over this short period. Serum 25(OH)D was increased in all participants although the carriers of the minor A allele seemed to be better responders so that the percentages of the change serum vitamin D in the holder of AA and AG genotypes were 539.4 ± 443.1 and 443.7 ± 384.6, respectively, compared with those with common GG genotype (363.3 ± 354.0). Our regression analysis revealed that the probability of an increase in serum 25(OH)D in a participant with AA genotype was 2.5-fold greater than those with a GG genotype (OR = 2.5 (1.4-4.4); p value = 0.002). CONCLUSION: Based on our findings, it appears that the rs10741657 variant of the CYP2R1 gene modulates the response to high-dose of vitamin D supplementation.

The transcriptomics profiling of blood CD4 and CD8 T-cells in narcolepsy type I.

Background: Narcolepsy Type I (NT1) is a rare, life-long sleep disorder arising as a consequence of the extensive destruction of orexin-producing hypothalamic neurons. The mechanisms involved in the destruction of orexin neurons are not yet elucidated but the association of narcolepsy with environmental triggers and genetic susceptibility (strong association with the HLA, TCRs and other immunologically-relevant loci) implicates an immuno-pathological process. Several studies in animal models and on human samples have suggested that T-cells are the main pathogenic culprits. Methods: RNA sequencing was performed on four CD4 and CD8 T-cell subsets (naive, effector, effector memory and central memory) sorted by flow cytometry from peripheral blood mononuclear cells (PBMCs) of NT1 patients and HLA-matched healthy donors as well as (age- and sex-) matched individuals suffering from other sleep disorders (OSD). The RNAseq analysis was conducted by comparing the transcriptome of NT1 patients to that of healthy donors and other sleep disorder patients (collectively referred to as the non-narcolepsy controls) in order to identify NT1-specific genes and pathways. Results: We determined NT1-specific differentially expressed genes, several of which are involved in tubulin arrangement found in CD4 (TBCB, CCT5, EML4, TPGS1, TPGS2) and CD8 (TTLL7) T cell subsets, which play a role in the immune synapse formation and TCR signaling. Furthermore, we identified genes (GZMB, LTB in CD4 T-cells and NLRP3, TRADD, IL6, CXCR1, FOXO3, FOXP3 in CD8 T-cells) and pathways involved in various aspects of inflammation and inflammatory response. More specifically, the inflammatory profile was identified in the "naive" subset of CD4 and CD8 T-cell. Conclusion: We identified NT1-specific differentially expressed genes, providing a cell-type and subset specific catalog describing their functions in T-cells as well as their potential involvement in NT1. Several genes and pathways identified are involved in the formation of the immune synapse and TCR activation as well as inflammation and the inflammatory response. An inflammatory transcriptomic profile was detected in both "naive" CD4 and CD8 T-cell subsets suggesting their possible involvement in the development or progression of the narcoleptic process.

Tissue-resident CD8+ T cells drive compartmentalized and chronic autoimmune damage against CNS neurons.

The mechanisms underlying the chronicity of autoimmune diseases of the central nervous system (CNS) are largely unknown. In particular, it is unclear whether tissue-resident memory T cells (TRM) contribute to lesion pathogenesis during chronic CNS autoimmunity. Here, we observed that a high frequency of brain-infiltrating CD8+ T cells exhibit a TRM-like phenotype in human autoimmune encephalitis. Using mouse models of neuronal autoimmunity and a combination of T single-cell transcriptomics, high-dimensional flow cytometry, and histopathology, we found that pathogenic CD8+ T cells behind the blood-brain barrier adopt a characteristic TRM differentiation program, and we revealed their phenotypic and functional heterogeneity. In the diseased CNS, autoreactive tissue-resident CD8+ T cells sustained focal neuroinflammation and progressive loss of neurons, independently of recirculating CD8+ T cells. Consistently, a large fraction of autoreactive tissue-resident CD8+ T cells exhibited proliferative potential as well as proinflammatory and cytotoxic properties. Persistence of tissue-resident CD8+ T cells in the CNS and their functional output, but not their initial differentiation, were crucially dependent on CD4+ T cells. Collectively, our results point to tissue-resident CD8+ T cells as essential drivers of chronic CNS autoimmunity and suggest that therapies targeting this compartmentalized autoreactive T cell subset might be effective for treating CNS autoimmune diseases.

MeCP2-E1 isoform is a dynamically expressed, weakly DNA-bound protein with different protein and DNA interactions compared to MeCP2-E2.

BACKGROUND: MeCP2-a chromatin-binding protein associated with Rett syndrome-has two main isoforms, MeCP2-E1 and MeCP2-E2, differing in a few N-terminal amino acid residues. Previous studies have shown brain region-specific expression of these isoforms which, in addition to their different cellular localization and differential expression during brain development, suggest that they may also have non-overlapping molecular mechanisms. However, differential functions of MeCP2-E1 and E2 remain largely unexplored. RESULTS: Here, we show that the N-terminal domains (NTD) of MeCP2-E1 and E2 modulate the ability of the methyl-binding domain (MBD) to interact with DNA as well as influencing the turn-over rates, binding dynamics, response to neuronal depolarization, and circadian oscillations of the two isoforms. Our proteomics data indicate that both isoforms exhibit unique interacting protein partners. Moreover, genome-wide analysis using ChIP-seq provide evidence for a shared as well as a specific regulation of different sets of genes. CONCLUSIONS: Our study supports the idea that Rett syndrome might arise from simultaneous impairment of cellular processes involving non-overlapping functions of MECP2 isoforms. For instance, MeCP2-E1 mutations might impact stimuli-dependent chromatin regulation, while MeCP2-E2 mutations could result in aberrant ribosomal expression. Overall, our findings provide insight into the functional complexity of MeCP2 by dissecting differential aspects of its two isoforms.

Association of dysglycemia with mortality in children receiving parenteral nutrition in pediatric intensive care unit.

Khajavi L, Khademi G, Mehramiz M, Norouzy A, Safarian M. Association of dysglycemia with mortality in children receiving parenteral nutrition in pediatric intensive care unit. Turk J Pediatr 2018; 60: 134-141. One of the most important complications of parenteral nutrition (PN) is a high incidence of hyperglycemia. The aim of this study was to assess the effect of parenteral nutrition dysglycemia on clinical outcomes among critically ill children in pediatric intensive care unit (PICU). Charts of 201 critically ill children admitted in PICU during 2012-2015 were reviewed retrospectively. We included patients who were < 6 years of age and had received at least 60% of total energy from PN for a minimum of 5 days in PICU. The exclusion criteria were patients with diagnosis of diabetes mellitus, primary hypoglycemia, inborn errors of metabolism and patients who received dialyses. We defined hyperglycemia as blood glucose ≥150 mg/dl, and hypoglycemia as blood glucose ≤60 mg/dl. Based on blood glucose, patients were divided into four groups: `only hyperglycemia group` (having at least one hyperglycemia episode), `only hypoglycemia group` (having at least one hypoglycemia episode), `glucose variability` (having both hypoglycemia and hyperglycemia episodes), and `normoglycemia` (all glucose measurements were in normal range). Hyperglycemia and hypoglycemia occurred in 52.8% and 24.9% of all children, respectively; glucose variability occurred in 13.9% of all children. Multiple logistic regression analysis showed that glucose variability (OR: 3.1; 95% CI: 1.13-8.43) and hyperglycemia (OR: 2.14; 95% CI: 1.1-4.57) were associated with mortality independently. In `only hypoglycemia` group (N=22) there were only three deaths. There were no significant differences in the quantities of macronutrients prescribed via parenteral nutrition among the four blood glucose groups. Results of this study showed that hyperglycemia and glucose variability are strong predictors of mortality in pediatrics receiving parenteral nutrition.