Exploration of potential immune mechanisms in cervical dystonia.

BACKGROUND: Although there are many possible causes for cervical dystonia (CD), a specific etiology cannot be identified in most cases. Prior studies have suggested a relationship between autoimmune disease and some cases of CD, pointing to possible immunological mechanisms. OBJECTIVE: The goal was to explore the potential role of multiple different immunological mechanisms in CD. METHODS: First, a broad screening test compared neuronal antibodies in controls and CD. Second, unbiased blood plasma proteomics provided a broad screen for potential biologic differences between controls and CD. Third, a multiplex immunoassay compared 37 markers associated with immunological processes in controls and CD. Fourth, relative immune cell frequencies were investigated in blood samples of controls and CD. Finally, sequencing studies investigated the association of HLA DQB1 and DRB1 alleles in controls versus CD. RESULTS: Screens for anti-neuronal antibodies did not reveal any obvious abnormalities. Plasma proteomics pointed towards certain abnormalities of immune mechanisms, and the multiplex assay pointed more specifically towards abnormalities in T lymphocytes. Abnormal immune cell frequencies were identified for some CD cases, and these cases clustered together as a potential subgroup. Studies of HLA alleles indicated a possible association between CD and DRB1*15:03, which is reported to mediate the penetrance of autoimmune disorders. CONCLUSIONS: Altogether, the association of CD with multiple different blood-based immune measures point to abnormalities in cell-mediated immunity that may play a pathogenic role for a subgroup of individuals with CD.

A new physiological medium uncovers biochemical and cellular alterations in Lesch-Nyhan disease fibroblasts.

BACKGROUND: Lesch-Nyhan disease (LND) is a severe neurological disorder caused by the genetic deficiency of hypoxanthine-guanine phosphoribosyltransferase (HGprt), an enzyme involved in the salvage synthesis of purines. To compensate this deficiency, there is an acceleration of the de novo purine biosynthetic pathway. Most studies have failed to find any consistent abnormalities of purine nucleotides in cultured cells obtained from the patients. Recently, it has been shown that 5-aminoimidazole-4-carboxamide riboside 5'-monophosphate (ZMP), an intermediate of the de novo pathway, accumulates in LND fibroblasts maintained with RPMI containing physiological levels (25 nM) of folic acid (FA), which strongly differs from FA levels of regular cell culture media (2200 nM). However, RPMI and other standard media contain non-physiological levels of many nutrients, having a great impact in cell metabolism that does not precisely recapitulate the in vivo behavior of cells. METHODS: We prepared a new culture medium containing physiological levels of all nutrients, including vitamins (Plasmax-PV), to study the potential alterations of LND fibroblasts that may have been masked by the usage of non-physiological media. We quantified ZMP accumulation under different culture conditions and evaluated the activity of two known ZMP-target proteins (AMPK and ADSL), the mRNA expression of the folate carrier SLC19A1, possible mitochondrial alterations and functional consequences in LND fibroblasts. RESULTS: LND fibroblasts maintained with Plasmax-PV show metabolic adaptations such a higher glycolytic capacity, increased expression of the folate carrier SCL19A1, and functional alterations such a decreased mitochondrial potential and reduced cell migration compared to controls. These alterations can be reverted with high levels of folic acid, suggesting that folic acid supplements might be a potential treatment for LND. CONCLUSIONS: A complete physiological cell culture medium reveals new alterations in Lesch-Nyhan disease. This work emphasizes the importance of using physiological cell culture conditions when studying a metabolic disorder.

Striatal Subregion-selective Dysregulated Dopamine Receptor-mediated Intracellular Signaling in a Model of DOPA-responsive Dystonia.

Although the mechanisms underlying dystonia are largely unknown, dystonia is often associated with abnormal dopamine neurotransmission. DOPA-responsive dystonia (DRD) is a prototype disorder for understanding dopamine dysfunction in dystonia because it is caused by mutations in genes necessary for the synthesis of dopamine and alleviated by the indirect-acting dopamine agonist l-DOPA. Although adaptations in striatal dopamine receptor-mediated intracellular signaling have been studied extensively in models of Parkinson's disease, another movement disorders associated with dopamine deficiency, little is known about dopaminergic adaptations in dystonia. To identify the dopamine receptor-mediated intracellular signaling associated with dystonia, we used immunohistochemistry to quantify striatal protein kinase A activity and extracellular signal-related kinase (ERK) phosphorylation after dopaminergic challenges in a knockin mouse model of DRD. l-DOPA treatment induced the phosphorylation of both protein kinase A substrates and ERK largely in D1 dopamine receptor-expressing striatal neurons. As expected, this response was blocked by pretreatment with the D1 dopamine receptor antagonist SCH23390. The D2 dopamine receptor antagonist raclopride also significantly reduced the phosphorylation of ERK; this contrasts with models of parkinsonism in which l-DOPA-induced ERK phosphorylation is not mediated by D2 dopamine receptors. Further, the dysregulated signaling was dependent on striatal subdomains whereby ERK phosphorylation was largely confined to dorsomedial (associative) striatum while the dorsolateral (sensorimotor) striatum was unresponsive. This complex interaction between striatal functional domains and dysregulated dopamine-receptor mediated responses has not been observed in other models of dopamine deficiency, such as parkinsonism, suggesting that regional variation in dopamine-mediated neurotransmission may be a hallmark of dystonia.

Abnormalities of neural stem cells in Lesch-Nyhan disease.

Lesch-Nyhan disease (LND) is a neurodevelopmental disorder caused by variants in the HPRT1 gene, which encodes the enzyme hypoxanthine-guanine phosphoribosyl transferase (HGprt). HGprt deficiency provokes numerous metabolic changes which vary among different cell types, making it unclear which changes are most relevant for abnormal neural development. To begin to elucidate the consequences of HGprt deficiency for developing human neurons, neural stem cells (NSCs) were prepared from 6 induced pluripotent stem cell (iPSC) lines from individuals with LND and compared to 6 normal healthy controls. For all 12 lines, gene expression profiles were determined by RNA-seq and protein expression profiles were determined by shotgun proteomics. The LND lines revealed significant changes in expression of multiple genes and proteins. There was little overlap in findings between iPSCs and NSCs, confirming the impact of HGprt deficiency depends on cell type. For NSCs, gene expression studies pointed towards abnormalities in WNT signaling, which is known to play a role in neural development. Protein expression studies pointed to abnormalities in the mitochondrial F0F1 ATPase, which plays a role in maintaining cellular energy. These studies point to some mechanisms that may be responsible for abnormal neural development in LND.

Induced pluripotent stem cells from subjects with Lesch-Nyhan disease.

Lesch-Nyhan disease (LND) is an inherited disorder caused by pathogenic variants in the HPRT1 gene, which encodes the purine recycling enzyme hypoxanthine-guanine phosphoribosyltransferase (HGprt). We generated 6 induced pluripotent stem cell (iPSC) lines from 3 individuals with LND, along with 6 control lines from 3 normal individuals. All 12 lines had the characteristics of pluripotent stem cells, as assessed by immunostaining for pluripotency markers, expression of pluripotency genes, and differentiation into the 3 primary germ cell layers. Gene expression profiling with RNAseq demonstrated significant heterogeneity among the lines. Despite this heterogeneity, several anticipated abnormalities were readily detectable across all LND lines, including reduced HPRT1 mRNA. Several unexpected abnormalities were also consistently detectable across the LND lines, including decreases in FAR2P1 and increases in RNF39. Shotgun proteomics also demonstrated several expected abnormalities in the LND lines, such as absence of HGprt protein. The proteomics study also revealed several unexpected abnormalities across the LND lines, including increases in GNAO1 decreases in NSE4A. There was a good but partial correlation between abnormalities revealed by the RNAseq and proteomics methods. Finally, functional studies demonstrated LND lines had no HGprt enzyme activity and resistance to the toxic pro-drug 6-thioguanine. Intracellular purines in the LND lines were normal, but they did not recycle hypoxanthine. These cells provide a novel resource to reveal insights into the relevance of heterogeneity among iPSC lines and applications for modeling LND.

Physiological levels of folic acid reveal purine alterations in Lesch-Nyhan disease.

Lesch-Nyhan disease (LND), caused by a deficient salvage purine pathway, is characterized by severe neurological manifestations and uric acid overproduction. However, uric acid is not responsible for brain dysfunction, and it has been suggested that purine nucleotide depletion, or accumulation of other toxic purine intermediates, could be more relevant. Here we show that purine alterations in LND fibroblasts depend on the level of folic acid in the culture media. Thus, physiological levels of folic acid induce accumulation of 5-aminoimidazole-4-carboxamide riboside 5'-monophosphate (ZMP), an intermediary of de novo purine biosynthetic pathway, and depletion of ATP. Additionally, Z-nucleotide derivatives (AICAr, AICA) are detected at high levels in the urine of patients with LND and its variants (hypoxanthine-guanine phosphoribosyltransferase [HGprt]-related neurological dysfunction and HGprt-related hyperuricemia), and the ratio of AICAr/AICA is significantly increased in patients with neurological problems (LND and HGprt-related neurological dysfunction). Moreover, AICAr is present in the cerebrospinal fluid of patients with LND, but not in control individuals. We hypothesize that purine alterations detected in LND fibroblasts may also occur in the brain of patients with LND.

Magnetic targeting of human mesenchymal stem cells with internalized superparamagnetic iron oxide nanoparticles.

Cell therapies offer exciting new opportunities for effectively treating many human diseases. However, delivery of therapeutic cells by intravenous injection, while convenient, relies on the relatively inefficient process of homing of cells to sites of injury. To address this limitation, a novel strategy has been developed to load cells with superparamagnetic iron oxide nanoparticles (SPIOs), and to attract them to specific sites within the body by applying an external magnetic field. The feasibility of this approach is demonstrated using human mesenchymal stem cells (hMSCs), which may have a significant potential for regenerative cell therapies due to their ease of isolation from autologous tissues, and their ability to differentiate into various lineages and modulate their paracrine activity in response to the microenvironment. The efficient loading of hMSCs with polyethylene glycol-coated SPIOs is achieved, and it is found that SPIOs are localized primarily in secondary lysosomes of hMSCs and are not toxic to the cells. Further, the key stem cell characteristics, including the immunophenotype of hMSCs and their ability to differentiate, are not altered by SPIO loading. Through both experimentation and mathematical modeling, it is shown that, under applied magnetic field gradients, SPIO-containing cells can be localized both in vitro and in vivo. The results suggest that, by loading SPIOs into hMSCs and applying appropriate magnetic field gradients, it is possible to target hMSCs to particular vascular networks.

Circulating proangiogenic cell activity is associated with cardiovascular disease risk.

Vascular injury mobilizes bone marrow-derived proangiogenic cells into the circulation, where these cells can facilitate vascular repair and new vessel formation. We sought to determine the relationship between a new biomarker of circulating bone marrow-derived proangiogenic cell activity, the presence of atherosclerotic cardiovascular disease (CVD) and its risk factors, and clinical outcomes. Circulating proangiogenic cell activity was estimated using a reproducible angiogenic colony-forming unit (CFU-A) assay in 532 clinically stable subjects aged 20 to 90 years and ranging in the CVD risk spectrum from those who are healthy without risk factors to those with active CVD. CFU-A counts increased with the burden of CVD risk factors (p < 0.001). CFU-A counts were higher in subjects with symptomatic CVD than in those without (p < 0.001). During follow-up of 232 subjects with CVD, CFU-A counts were higher in those with death, myocardial infarction, or stroke than in those without (110 [70-173] vs 84 [51-136], p = 0.01). Therefore, we conclude that circulating proangiogenic cell activity, as estimated by CFU-A counts, increases with CVD risk factor burden and in the presence of established CVD. Furthermore, higher circulating proangiogenic cell activity is associated with worse clinical outcome in those with CVD.

Proangiogenic cell colonies grown in vitro from human peripheral blood mononuclear cells.

Although multiple culture assays have been designed to identify endothelial progenitor cells (EPCs), the phenotype of cells grown in culture often remains undefined. We sought to define and characterize the proangiogenic cell population within human peripheral blood mononuclear cells. Mononuclear cells were isolated from peripheral blood and grown under angiogenic conditions for 7 days. Formed colonies (CFU-As) were identified and analyzed for proliferation, mRNA and surface antigen expression, tube-forming ability, and chromosomal content. Colonies were composed of a heterogeneous group of cells expressing the leukocyte antigens CD45, CD14, and CD3, as well as the endothelial proteins vascular endothelial (VE) cadherin, von Willebrand's factor (vWF), CD31, and endothelial nitric oxide synthase (eNOS). Colony cells expressed increased levels of proangiogenic growth factors, and they formed tubes in Matrigel. In comparison with colonies from the CFU-Hill assay, our assay resulted in a greater number of colonies (19 ± 9 vs. 13 ± 7; p < 0.0001) with a substantial number of cells expressing an endothelial phenotype (20.2% ± 7.4% vs. 2.2% ± 1.2% expressing eNOS, p = 0.0006). Chromosomal analysis indicated the colony cells were bone marrow derived. We, therefore, describe a colony-forming unit assay that measures bone marrow-derived circulating mononuclear cells with the capacity to proliferate and mature into proangiogenic leukocytic and endothelial-like cells. This assay, therefore, reflects circulating, bone marrow-derived proangiogenic activity.

Circulating endothelial progenitor cells inversely associate with organ dysfunction in sepsis.

PURPOSE: Endothelial dysfunction is a primary contributor to sepsis-related organ dysfunction and death. In sepsis animal models, endothelial progenitor cells (EPC) have contributed to vascular repair. The role of endothelial progenitor cells as a biomarker for organ dysfunction is still unknown. We hypothesized that circulating numbers of endothelial progenitor cells would be associated with improved outcomes in sepsis. METHODS: Prospective, observational single-center cohort study in adult intensive care units at Grady Memorial Hospital, an affiliate of Emory University, from July 2007 through April 2009. Peripheral blood was obtained from 95 patients with sepsis, 37 intensive care unit controls, and 51 healthy controls, of whom only 86 patients with sepsis were used in the analysis because we were not able to obtain enough blood in 9 sepsis patients. Clinical data were obtained, and organ dysfunction was measured by Sepsis-Related Organ Failure Assessment (SOFA) score. Endothelial progenitor cells were assessed by a colony-forming unit (CFU) assay in which peripheral blood mononuclear cells were isolated using Ficoll density-gradient centrifugation and cultured in growth media. RESULTS: The patients with sepsis had significantly lower mean endothelial progenitor cell colony counts compared with intensive care unit controls (p = 0.035) and healthy controls (p = 0.0005). There was no difference in colony counts between ICU controls and healthy controls (p = 0.81). In the sepsis patients, EPC CFU numbers inversely associated with SOFA score, adjusting for mortality (r (2) = 0.05, p = 0.04). CONCLUSION: Increased circulating endothelial progenitor cells inversely correlate with organ dysfunction in sepsis patients.