Biomolecules to Biomarkers? U87MG Marker Evaluation on the Path towards Glioblastoma Multiforme Pathogenesis

The heterogeneity of the glioma subtype glioblastoma multiforme (GBM) challenges effective neuropathological treatment. The reliance on in vitro studies and xenografted animal models to simulate human GBM has proven ineffective. Currently, a dearth of knowledge exists regarding the applicability of cell line biomolecules to the realm of GBM pathogenesis. Our study's objectives were to address this preclinical issue and assess prominin-1, ICAM-1, PARTICLE and GAS5 as potential GBM diagnostic targets. The methodologies included haemoxylin and eosin staining, immunofluorescence, in situ hybridization and quantitative PCR. The findings identified that morphology correlates with malignancy in GBM patient pathology. Immunofluorescence confocal microscopy revealed prominin-1 in pseudo-palisades adjacent to necrotic foci in both animal and human GBM. Evidence is presented for an ICAM-1 association with degenerating vasculature. Significantly elevated nuclear PARTICLE expression from in situ hybridization and quantitative PCR reflected its role as a tumor activator. GAS5 identified within necrotic GBM validated this potential prognostic biomolecule with extended survival. Here we present evidence for the stem cell marker prominin-1 and the chemotherapeutic target ICAM-1 in a glioma animal model and GBM pathology sections from patients that elicited alternative responses to adjuvant chemotherapy. This foremost study introduces the long non-coding RNA PARTICLE into the context of human GBM pathogenesis while substantiating the role of GAS5 as a tumor suppressor. The validation of GBM biomarkers from cellular models contributes to the advancement towards superior detection, therapeutic responders and the ultimate attainment of promising prognoses for this currently incurable brain cancer.

Cerebellar demyelination and neurodegeneration associated with mTORC1 hyperactivity may contribute to the developmental onset of autism-like neurobehavioral phenotype in a rat model

The cerebellum hosts more than half of all neurons of the human brain, with their organized activity playing a key role in coordinating motor functions. Cerebellar activity has also been implicated in the control of speech, communication, and social behavior, which are compromised in autism spectrum disorders (ASD). Despite major research advances, there is a shortage of mechanistic data relating cellular and molecular changes in the cerebellum to autistic behavior. We studied the impact of tuberous sclerosis complex 2 haploinsufficiency (Tsc2+/-) with downstream mTORC1 hyperactivity on cerebellar morphology and cellular organization in 1, 9, and 18 m.o. Eker rats, to determine possible structural correlates of an autism-like behavioural phenotype in this model. We report a greater developmental expansion of the cerebellar vermis, owing to enlarged white matter and thickened molecular layer. Histochemical and immunofluorescence data suggest age-related demyelination of central tract of the vermis, as evident from reduced level of myelin-basic protein in the arbora vitae. We also observed a higher number of astrocytes in Tsc2+/- rats of older age while the number of Purkinje cells (PCs) in these animals was lower than in wild-type controls. Unlike astrocytes and PCs, Bergmann glia remained unaltered at all ages in both genotypes, while the number of microglia was higher in Tsc2+/- rats of older age. The convergent evidence for a variety of age-dependent cellular changes in the cerebellum of rats associated with mTORC1 hyperactivity, thus, predicts an array of functional impairments, which may contribute to the developmental onset of an autism-like behavioral phenotype in this model. LAY SUMMARY: This study elucidates the impact of constitutive mTORC1 hyperactivity on cerebellar morphology and cellular organization in a rat model of autism and epilepsy. It describes age-dependent degeneration of Purkinje neurons, with demyelination of central tract as well as activation of microglia, and discusses the implications of these changes for neuro-behavioral phenotypes. The described changes provide new indications for the putative mechanisms underlying cerebellar impairments with their age-related onset, which may contribute to the pathobiology of autism, epilepsy, and related disorders.

Celiac Disease Defined by Over-Sensitivity to Gliadin Activation and Superior Antigen Presentation of Dendritic Cells

The autoimmune condition, Celiac Disease (CeD), displays broad clinical symptoms due to gluten exposure. Its genetic association with DQ variants in the human leukocyte antigen (HLA) system has been recognised. Monocyte-derived mature dendritic cells (MoDCs) present gluten peptides through HLA-DQ and co-stimulatory molecules to T lymphocytes, eliciting a cytokine-rich microenvironment. Having access to CeD associated families prevalent in the Czech Republic, this study utilised an in vitro model to investigate their differential monocyte profile. The higher monocyte yields isolated from PBMCs of CeD patients versus control individuals also reflected the greater proportion of dendritic cells derived from these sources following lipopolysaccharide (LPS)/ peptic-tryptic-gliadin (PTG) fragment stimulation. Cell surface markers of CeD monocytes and MoDCs were subsequently profiled. This foremost study identified a novel bio-profile characterised by elevated CD64 and reduced CD33 levels, unique to CD14++ monocytes of CeD patients. Normalisation to LPS stimulation revealed the increased sensitivity of CeD-MoDCs to PTG, as shown by CD86 and HLA-DQ flow cytometric readouts. Enhanced CD86 and HLA-DQ expression in CeD-MoDCs were revealed by confocal microscopy. Analysis highlighted their dominance at the CeD-MoDC membrane in comparison to controls, reflective of superior antigen presentation ability. In conclusion, this investigative study deciphered the monocytes and MoDCs of CeD patients with the identification of a novel bio-profile marker of potential diagnostic value for clinical interpretation. Herein, the characterisation of CD86 and HLA-DQ as activators to stimulants, along with robust membrane assembly reflective of efficient antigen presentation, offers CeD targeted therapeutic avenues worth further exploration.

Revisiting Brain Tuberous Sclerosis Complex in Rat and Human: Shared Molecular and Cellular Pathology Leads to Distinct Neurophysiological and Behavioral Phenotypes

Tuberous sclerosis complex (TSC) is a dominant autosomal genetic disorder caused by loss-of-function mutations in TSC1 and TSC2, which lead to constitutive activation of the mammalian target of rapamycin C1 (mTORC1) with its decoupling from regulatory inputs. Because mTORC1 integrates an array of molecular signals controlling protein synthesis and energy metabolism, its unrestrained activation inflates cell growth and division, resulting in the development of benign tumors in the brain and other organs. In humans, brain malformations typically manifest through a range of neuropsychiatric symptoms, among which mental retardation, intellectual disabilities with signs of autism, and refractory seizures, which are the most prominent. TSC in the rat brain presents the first-rate approximation of cellular and molecular pathology of the human brain, showing many instructive characteristics. Nevertheless, the developmental profile and distribution of lesions in the rat brain, with neurophysiological and behavioral manifestation, deviate considerably from humans, raising numerous research and translational questions. In this study, we revisit brain TSC in human and Eker rats to relate their histopathological, electrophysiological, and neurobehavioral characteristics. We discuss shared and distinct aspects of the pathology and consider factors contributing to phenotypic discrepancies. Given the shared genetic cause and molecular pathology, phenotypic deviations suggest an incomplete understanding of the disease. Narrowing the knowledge gap in the future should not only improve the characterization of the TSC rat model but also explain considerable variability in the clinical manifestation of the disease in humans.

Tuberous Sclerosis (tsc2+/-) Model Eker Rats Reveals Extensive Neuronal Loss with Microglial Invasion and Vascular Remodeling Related to Brain Neoplasia

Tuberous sclerosis complex (TSC) is a genetic disorder characterized by frequent noncancerous neoplasia in the brain, which can induce a range of severe neuropsychiatric symptoms in humans, resulting from out of control tissue growth. The causative spontaneous loss-of-function mutations have been also identified in rats. Herein, we studied histopathological and molecular changes in brain lesions of the Eker rat model carrying germline mutation of the tsc2 gene, predisposed to multiple neoplasias. Predominant subcortical tumors were analyzed, along with a rare form occurring within the pyriform lobe. The uniform composition of lesions supports the histochemical parity of malformations, with immunofluorescence data supporting their neuro-glial origin. Massive depletion of mature neurons and axonal loss were evident within lesions, with occasional necrotic foci implying advanced stage of pathology. Enrichment of mesenchymal-derived cell markers with hallmarks of neurogenesis and active microglia imply enhanced cell proliferation, with local immune response. The depletion of capillaries within the core was complemented by the formation of dense mesh of nascent vessels at the interface of neoplasia with healthy tissue, implying large-scale vascular remodeling. Taken as a whole, these findings present several novel features of brain tumors in Eker rat model, rendering it suitable for studies of the pathobiology and progression of primary brain tumors, with therapeutic interventions.

New Design of the Electrophoretic Part of CLARITY Technology for Confocal Light Microscopy of Rat and Human Brains

Background: CLARITY is a method of rendering postmortem brain tissue transparent using acrylamide-based hydrogels so that this tissue could be further used for immunohistochemistry, molecular biology, or gross anatomical studies. Published papers using the CLARITY method have included studies on human brains suffering from Alzheimer’s disease using mouse spinal cords as animal models for multiple sclerosis. Methods: We modified the original design of the Chung CLARITY system by altering the electrophoretic flow-through cell, the shape of the platinum electrophoresis electrodes and their positions, as well as the cooling and recirculation system, so that it provided a greater effect and can be used in any laboratory. Results: The adapted CLARITY system is assembled from basic laboratory components, in contrast to the original design. The modified CLARITY system was tested both on rat brain stained with a rabbit polyclonal anti-Iba-1 for microglial cells and on human nucleus accumbens stained with parvalbumin and tyrosine hydroxylase for visualization of specific neurons by confocal laser scanning microscopy. Conclusions: Our design has the advantage of simplicity, functional robustness, and minimal requirement for specialized additional items for the construction of the CLARITY apparatus.

Peroral administration of 5-bromo-2-deoxyuridine in drinking water is not a reliable method for labeling proliferating S-phase cells in rats

In rodents, peroral (p.o.) administration of 5-bromo-2'-deoxyuridine (BrdU) dissolved in drinking water is a widely used method for labeling newly formed cells over a prolonged time-period. Despite the broad applicability of this method, the pharmacokinetics of BrdU in rats or mice after p.o. administration remains unknown. Moreover, the p.o. route of administration may be limited by the relatively low amount of BrdU consumed over 24h and the characteristic drinking pattern of rats, with water intake being observed predominantly during the dark phase. Therefore, we investigated the reliability of staining proliferating S-phase cells with BrdU after p.o. administration (1mg/ml) to rats using both in vitro and in vivo conditions. Flow cytometric analysis of tumor cells co-cultivated with sera from experimental animals exposed to BrdU dissolved in drinking water or 25% orange juice revealed that the concentration of BrdU in the blood sera of rats throughout the day was below the detection limits of our assay. Ingested BrdU was only sufficient to label approximately 4.2±0.3% (water) or 4.2±0.3% (25% juice) of all S-phase cells. Analysis of data from in vivo conditions indicates that only 7.6±3.3% or 15.5±2.3% of all S-phase cells in the dentate gyrus of the hippocampus was labeled in animals administered drinking water containing BrdU during the light and dark phases of the day. In addition, the intensity of BrdU-positive nuclei in animals receiving p.o. administration of BrdU was significantly lower than in control animals intraperitoneally injected with BrdU. Our data indicate that the conventional approach of p.o. administration of BrdU in the drinking water to rats provides strongly inaccurate information about the number of proliferating cells in target tissues. Therefore other administration routes, such as osmotic mini pumps, should be considered for labeling of proliferating cells over a prolonged time-period.

Evidence that the central canal lining of the spinal cord contributes to oligodendrogenesis during postnatal development and adulthood in intact rats

Two waves of oligodendrogenesis in the ventricular zone of the spinal cord (SC-VZ) during rat development, which take place between embryonic days 14 and 18 (E14-E18) and E20-E21, have been described. In the VZ of the brain, unlike the SC-VZ, a third wave of oligodendrogenesis occurs during the first weeks of postnatal development. Using immunofluorescence staining of intact rat SC tissue, we noticed the presence of small numbers of Olig2(+) /Sox-10(+) cells inside the lining of the central canal (CC) during postnatal development and adulthood. Olig2(+) /Sox-10(+) cells appeared inside the lining of the CC shortly after birth, and their number reached a maximum of approximately 0.65 ± 0.14 cell/40-μm section during the second postnatal week. After the latter development, the number of Olig2(+) /Sox-10(+) cells decreased to 0.21 ± 0.07 (P36) and 0.18 ± 0.1 cell/section (P120). At P21, Olig2(+) /Sox-10(+) cells inside the CC lining started to express other oligodendroglial markers such as CNPase, RIP, and APC. Olig2(+) /Sox-10(+) cells usually did not proliferate inside the CC lining and were only rarely found to be immunoreactive against oligodendrocyte progenitor markers such as NG2 or PDGFRα. Using 5-bromo-2-deoxyuridine administration at P2, P11, P22, or P120-P125, we revealed that these cells arose in the CC lining during postnatal development and adulthood. Our findings confirmed that the CC lining is the source of a small number of cells with an oligodendroglial phenotype during postnatal development and adulthood in the SC of intact rats.

Enigmatic cerebrospinal fluid-contacting neurons arise even after the termination of neurogenesis in the rat spinal cord during embryonic development and retain their immature-like characteristics until adulthood

Despite the abundance of cerebrospinal fluid-contacting neurons (CSF-cNs) lining the central canal of the spinal cord of mammals, little information is known regarding the phenotype and fate of these cells during development and in adulthood. Using immunofluorescence of spinal cord tissue of rats from the first postnatal day (P1) until the end of the 5th postnatal week (P36), we observed that these neurons show both immature (doublecortin+, β-III-tubulin+, neurofilament 200 kDa-) and more mature (weak NeuN+, P2X2+, GAD65+) characteristics during the first postnatal weeks. Because of the gradually decreasing number of CSF-cNs in the central canal lining during development, we were also interested in the migration potential of these cells. However, the assessment of the number of CSF-cNs in the lining of the central canal during postnatal development revealed that this decline is most likely associated with the growth of the spinal cord. Lastly, to reveal the birth date of CSF-cNs, we performed 5-bromo-2-deoxyuridine administration and colocalization analyses. We found that production of these cells appears from day 12 of embryonic development (E12) until E22. The vast majority of CSF-contacting neurons arise on E14 and E15. In contrast with other types of spinal neurons, the production of CSF-cNs is not restricted to a particular neuroepithelial region and occurs even after what is thought to be the termination of neurogenesis.