Clinical and genetic features of cervical dystonia in a large multicenter cohort.

OBJECTIVE: To characterize the clinical and genetic features of cervical dystonia (CD). METHODS: Participants enrolled in the Dystonia Coalition biorepository (NCT01373424) with initial manifestation as CD were included in this study (n = 1,000). Data intake included demographics, family history, and the Global Dystonia Rating Scale. Participants were screened for sequence variants (SVs) in GNAL, THAP1, and Exon 5 of TOR1A. RESULTS: The majority of participants were Caucasian (95%) and female (75%). The mean age at onset and disease duration were 45.5 ± 13.6 and 14.6 ± 11.8 years, respectively. At the time of assessment, 68.5% had involvement limited to the neck, shoulder(s), and proximal arm(s), whereas 47.4% had dystonia limited to the neck. The remaining 31.5% of the individuals exhibited more extensive anatomical spread. A head tremor was noted in 62% of the patients. Head tremor and laryngeal dystonia were more common in females. Psychiatric comorbidities, mainly depression and anxiety, were reported by 32% of the participants and were more common in females. Family histories of dystonia, parkinsonian disorder, and tremor were present in 14%, 11%, and 29% of the patients, respectively. Pathogenic or likely pathogenic SVs in THAP1, TOR1A, and GNAL were identified in 8 participants (0.8%). Two individuals harbored novel missense SVs in Exon 5 of TOR1A. Synonymous and noncoding SVs in THAP1 and GNAL were identified in 4% of the cohort. CONCLUSIONS: Head tremor, laryngeal dystonia, and psychiatric comorbidities are more common in female participants with CD. Coding and noncoding variants in GNAL, THAP1, and TOR1A make small contributions to the pathogenesis of CD.

Blepharospasm in a multiplex African-American pedigree.

BACKGROUND: Isolated blepharospasm (BSP) is a late-onset focal dystonia characterized by involuntary contractions of the orbicularis oculi muscles. Genetic studies of BSP have been limited by the paucity of large multiplex pedigrees. Although sequence variants (SVs) in THAP1 have been reported in rare cases of BSP, the genetic causes of this focal dystonia remain largely unknown. Moreover, in the absence of family history and strong in silico or in vitro evidence of deleteriousness, the pathogenicity of novel SVs in THAP1 and other dystonia-associated genes can be indeterminate. METHODS: A large African-American pedigree with BSP was phenotypically characterized and screened for mutations in THAP1, TOR1A and GNAL with Sanger sequencing. Whole-exome sequencing of the proband was used to examine other dystonia-associated genes for potentially pathogenic SVs. In silico and co-segregation analyses were performed for a novel THAP1 SV identified in the proband. RESULTS: Seven family members exhibited increased blinking and/or stereotyped bilateral and synchronous orbicularis oculi spasms with age of onset ranging from early childhood to late adult life (7 to 54 years). The proband was found to harbor a novel THAP1 SV (c.314T>C, p.L105S). However, the p.L105S SV did not co-segregate with blepharospasm in the pedigree. Moreover, in silico analyses suggest that p.L105S is benign. No pathogenic or likely pathogenic SVs in other dystonia-associated genes were identified with whole-exome sequencing. CONCLUSIONS: Blepharospasm can be familial and may be hereditary in African-Americans. A comprehensive array of in silico tools, and, if possible, co-segregation analysis should be used to classify SVs in dystonia-associated genes.

Evidence for a novel functional role of astrocytes in the acute homeostatic response to high-fat diet intake in mice.

OBJECTIVE: Introduction of a high-fat diet to mice results in a period of voracious feeding, known as hyperphagia, before homeostatic mechanisms prevail to restore energy intake to an isocaloric level. Acute high-fat diet hyperphagia induces astrocyte activation in the rodent hypothalamus, suggesting a potential role of these cells in the homeostatic response to the diet. The objective of this study was to determine physiologic role of astrocytes in the acute homeostatic response to high-fat feeding. METHODS: We bred a transgenic mouse model with doxycycline-inducible inhibition of NFkappaB (NFκB) signaling in astrocytes to determine the effect of loss of NFκB-mediated astrocyte activation on acute high-fat hyperphagia. ELISA was used to measure the levels of markers of astrocyte activation, glial-fibrillary acidic protein (GFAP) and S100B, in the medial basal hypothalamus. RESULTS: Inhibition of NFκB signaling in astrocytes prevented acute high-fat diet-induced astrocyte activation and resulted in a 15% increase in caloric intake (P < 0.01) in the first 24 h after introduction of the diet. CONCLUSIONS: These data reveal a novel homeostatic role for astrocytes in the acute physiologic regulation of food intake in response to high-fat feeding.

Obesity induced by a high-fat diet is associated with increased immune cell entry into the central nervous system.

Obesity is associated with chronic low-grade inflammation in peripheral tissues caused, in part, by the recruitment of inflammatory monocytes into adipose tissue. Studies in rodent models have also shown increased inflammation in the central nervous system (CNS) during obesity. The goal of this study was to determine whether obesity is associated with recruitment of peripheral immune cells into the CNS. To do this we used a bone marrow chimerism model to track the entry of green-fluorescent protein (GFP) labeled peripheral immune cells into the CNS. Flow cytometry was used to quantify the number of GFP(+) immune cells recruited into the CNS of mice fed a high-fat diet compared to standard chow fed controls. High-fat feeding resulted in obesity associated with a 30% increase in the number of GFP(+) cells in the CNS compared to control mice. Greater than 80% of the GFP(+) cells recruited to the CNS were also CD45(+) CD11b(+) indicating that the GFP(+) cells displayed characteristics of microglia/macrophages. Immunohistochemistry further confirmed the increase in GFP(+) cells in the CNS of the high-fat fed group and also indicated that 93% of the recruited cells were found in the parenchyma and had a stellate morphology. These findings indicate that peripheral immune cells can be recruited to the CNS in obesity and may contribute to the inflammatory response.

Translocator protein 18 kDa (TSPO) is regulated in white and brown adipose tissue by obesity.

Translocator protein 18 kDa (TSPO) is an outer-mitochondrial membrane transporter which has many functions including participation in the mitochondrial permeability transition pore, regulation of reactive oxygen species (ROS), production of cellular energy, and is the rate-limiting step in the uptake of cholesterol. TSPO expression is dysregulated during disease pathologies involving changes in tissue energy demands such as cancer, and is up-regulated in activated macrophages during the inflammatory response. Obesity is associated with decreased energy expenditure, mitochondrial dysfunction, and chronic low-grade inflammation which collectively contribute to the development of the Metabolic Syndrome. Therefore, we hypothesized that dysregulation of TSPO in adipose tissue may be a feature of disease pathology in obesity. Radioligand binding studies revealed a significant reduction in TSPO ligand binding sites in mitochondrial extracts from both white (WAT) and brown adipose tissue (BAT) in mouse models of obesity (diet-induced and genetic) compared to control animals. We also confirmed a reduction in TSPO gene expression in whole tissue extracts from WAT and BAT. Immunohistochemistry in WAT confirmed TSPO expression in adipocytes but also revealed high-levels of TSPO expression in WAT macrophages in obese animals. No changes in TSPO expression were observed in WAT or BAT after a 17 hour fast or 4 hour cold exposure. Treatment of mice with the TSPO ligand PK11195 resulted in regulation of metabolic genes in WAT. Together, these results suggest a potential role for TSPO in mediating adipose tissue homeostasis.

Regional astrogliosis in the mouse hypothalamus in response to obesity.

Obesity is associated with chronic low-grade inflammation in peripheral tissues, which contributes to the development of comorbidities such as insulin resistance and cardiovascular disease. While less extensively characterized, obesity also promotes inflammation in the central nervous system (CNS) and the consequences of this inflammation for CNS function are only beginning to be examined. In response to CNS insults such as inflammation, astrocytes undergo a process of hypertrophy and hyperplasia known as reactive astrogliosis. We used immunohistochemistry to examine the differential distribution of the astrocyte marker glial-fibrillary acidic protein (GFAP) in the brains of diet-induced or genetically obese mice compared with their respective lean controls to determine whether different nuclei of the hypothalamus showed comparable astrogliosis in response to obesity. The areas that showed the highest differential GFAP immunoreactivity between lean and obese animals include the medial preoptic, paraventricular, and dorsomedial nuclei. Comparatively, little astrogliosis was seen in the ventromedial nucleus, lateral hypothalamus, or anterior hypothalamic area. In obese animals high levels of GFAP immunoreactivity were often associated with the microvasculature. There were no differences in the differential distribution of GFAP staining between obese animals and their lean controls in the diet-induced compared with the genetic model of obesity. The exact cause(s) of the astrogliosis in obesity is not known. The finding that obesity causes a distinct pattern of elevated GFAP immunoreactivity associated with microvessels suggests that the astrogliosis may be occurring as a response to changes at the blood-brain barrier and/or in the peripheral circulation.