Molecular composition of skeletal muscle in infants and adults: a comparative proteomic and transcriptomic study.

To gain a deeper understanding of skeletal muscle function in younger age and aging in elderly, identification of molecular signatures regulating these functions under physiological conditions is needed. Although molecular studies of healthy muscle have been conducted on adults and older subjects, there is a lack of research on infant muscle in terms of combined morphological, transcriptomic and proteomic profiles. To address this gap of knowledge, we performed RNA sequencing (RNA-seq), tandem mass spectrometry (LC-MS/MS), morphometric analysis and assays for mitochondrial maintenance in skeletal muscle biopsies from both, infants aged 4-28 months and adults aged 19-65 years. We identified differently expressed genes (DEGs) and differentially expressed proteins (DEPs) in adults compared to infants. The down-regulated genes in adults were associated with functional terms primarily related to sarcomeres, cellular maintenance, and metabolic, immunological and developmental processes. Thus, our study indicates age-related differences in the molecular signatures and associated functions of healthy skeletal muscle. Moreover, the findings assert that processes previously associated solely with aging are indeed part of development and healthy aging. Hence, combined findings of this study also indicate that age-dependent controls are crucial in muscle disease studies, as otherwise the comparative results may not be reliable.

Characterization of the neuropathic pain component contributing to myalgia in patients with myotonic dystrophy type 1 and 2.

Introduction: Chronic muscle pain is common in myotonic dystrophies (DM). Little is known about its pathophysiology. We aimed to investigate the characteristics of the neuropathic pain component contributing contributes to the pathogenesis of chronic pain in DM. Methods: Twenty-one DM1 and 32 DM2 patients completed pain questionnaires (Brief pain inventory-BPI, PAIN-DETECT, pain disability index-PDI) and underwent neurological examination, nerve conduction studies (NCS), quantitative sensory testing (QST, dorsum of the right hand and right thigh) and skin biopsy to determine the intraepidermal nerve fiber density (IENFD, distal and proximal site of lower extremity). NCS and QST results at the thigh were compared to 27 healthy controls and IENFD and QST at the dorsum of the hand to published reference values. Results: The sensory profile of DM2 patients was characterized by a loss in thermal and mechanical detection, while DM1 patients showed reduced mechanical and heat pain thresholds and higher mechanical pain sensitivity. Both DM groups showed pressure hyperalgesia. IENFD was reduced in 63% of DM1 patients and 50% of DM2. The slightly higher pain interference and disability found in DM2 was rather due to age difference than disease. Conclusion: Similar pain mechanisms likely occur in both DM1 and DM2, even though a tendency toward more pain sensitivity was observed in DM1 and more sensory loss in DM2. Both QST and reduced IENFD highlight the presence of peripheral nerve damage in DM. This must be considered for the best pain management strategies.

Differentiating idiopathic inflammatory myopathies by automated morphometric analysis of MHC-1, MHC-2 and ICAM-1 in muscle tissue.

AIMS: Diagnosis of idiopathic inflammatory myopathies (IIM) is based on morphological characteristics and the evaluation of disease-related proteins. However, although broadly applied, substantial bias is imposed by the respective methods, observers and individual staining approaches. We aimed to quantify the protein levels of major histocompatibility complex (MHC)-1, (MHC)-2 and intercellular adhesion molecule (ICAM)-1 using an automated morphometric method to mitigate bias. METHODS: Double immunofluorescence staining was performed on whole muscle sections to study differences in protein expression in myofibre and endomysial vessels. We analysed all IIM subtypes including dermatomyositis (DM), anti-synthetase syndrome (ASyS), inclusion body myositis (IBM), immune-mediated-necrotising myopathy (IMNM), dysferlinopathy (DYSF), SARS-CoV-2 infection and vaccination-associated myopathy. Biopsies with neurogenic atrophy (NA) and normal morphology served as controls. Bulk RNA-Sequencing (RNA-Seq) was performed on a subset of samples. RESULTS: Our study highlights the significance of MHC-1, MHC-2 and ICAM-1 in diagnosing IIM subtypes and reveals distinct immunological profiles. RNASeq confirmed the precision of our method and identified specific gene pathways in the disease subtypes. Notably, ASyS, DM and SARS-CoV-2-associated myopathy showed increased ICAM-1 expression in the endomysial capillaries, indicating ICAM-1-associated vascular activation in these conditions. In addition, ICAM-1 showed high discrimination between different subgroups with high sensitivity and specificity. CONCLUSIONS: Automated morphometric analysis provides precise quantitative data on immune-associated proteins that can be integrated into our pathophysiological understanding of IIM. Further, ICAM-1 holds diagnostic value for the detection of IIM pathology.

Anti-Ku + myositis: an acquired inflammatory protein-aggregate myopathy.

Myositis with anti-Ku-autoantibodies is a rare inflammatory myopathy associated with various connective tissue diseases. Histopathological studies have identified inflammatory and necrotizing aspects, but a precise morphological analysis and pathomechanistic disease model are lacking. We therefore aimed to carry out an in-depth morpho-molecular analysis to uncover possible pathomechanisms. Muscle biopsy specimens from 26 patients with anti-Ku-antibodies and unequivocal myositis were analyzed by immunohistochemistry, immunofluorescence, transcriptomics, and proteomics and compared to biopsy specimens of non-disease controls, immune-mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM). Clinical findings and laboratory parameters were evaluated retrospectively and correlated with morphological and molecular features. Patients were mainly female (92%) with a median age of 56.5 years. Isolated myositis and overlap with systemic sclerosis were reported in 31%, respectively. Isolated myositis presented with higher creatine kinase levels and cardiac involvement (83%), whereas systemic sclerosis-overlap patients often had interstitial lung disease (57%). Histopathology showed a wide spectrum from mild to pronounced myositis with diffuse sarcolemmal MHC-class I (100%) and -II (69%) immunoreactivity, myofiber necrosis (88%), endomysial inflammation (85%), thickened capillaries (84%), and vacuoles (60%). Conspicuous sarcoplasmic protein aggregates were p62, BAG3, myotilin, or immunoproteasomal beta5i-positive. Proteomic and transcriptomic analysis identified prominent up-regulation of autophagy, proteasome, and hnRNP-related cell stress. To conclude, Ku + myositis is morphologically characterized by myofiber necrosis, MHC-class I and II positivity, variable endomysial inflammation, and distinct protein aggregation varying from IBM and IMNM, and it can be placed in the spectrum of scleromyositis and overlap myositis. It features characteristic sarcoplasmic protein aggregation on an acquired basis being functionally associated with altered chaperone, proteasome, and autophagy function indicating that Ku + myositis exhibit aspects of an acquired inflammatory protein-aggregate myopathy.

[Idiopathic inflammatory myopathies : An interdisciplinary challenge]. / Idiopathische inflammatorische Myopathien : Eine interdisziplinäre Herausforderung.

Idiopathic inflammatory myopathies (IIM) are rare diseases (incidence 1:100,000) with a wide range of clinical symptoms and manifestations. Typical indicators of IIM are proximally emphasized muscle weakness and myalgias, which are usually accompanied by elevated creatine kinase levels and muscle atrophy. The autoantibody diagnostics separate IIM into different entities, which are each associated with a typical risk of organ manifestations and the occurrence of tumors. The IIM represents an interdisciplinary challenge and the diagnostics and treatment require the involvement of several disciplines including rheumatology, neurology, neuropathology, dermatology and pneumology. An accurate diagnosis and careful tumor screening are essential because of the association between certain subgroups of IIM and the occurrence of malignant tumors.

Inhibition of autophagy prevents cardiac dysfunction at early stages of cardiomyopathy in Bag3-deficient hearts.

The HSP70 co-chaperone BAG3 targets unfolded proteins to degradation via chaperone assisted selective autophagy (CASA), thereby playing pivotal roles in the proteostasis of adult cardiomyocytes (CMs). However, the complex functions of BAG3 for regulating autophagy in cardiac disease are not completely understood. Here, we demonstrate that conditional inactivation of Bag3 in murine CMs leads to age-dependent dysregulation of autophagy, associated with progressive cardiomyopathy. Surprisingly, Bag3-deficient CMs show increased canonical and non-canonical autophagic flux in the juvenile period when first signs of cardiac dysfunction appear, but reduced autophagy during later stages of the disease. Juvenile Bag3-deficient CMs are characterized by decreased levels of soluble proteins involved in synchronous contraction of the heart, including the gap junction protein Connexin 43 (CX43). Reiterative administration of chloroquine (CQ), an inhibitor of canonical and non-canonical autophagy, but not inactivation of Atg5, restores normal concentrations of soluble cardiac proteins in juvenile Bag3-deficient CMs without an increase of detergent-insoluble proteins, leading to complete recovery of early-stage cardiac dysfunction in Bag3-deficient mice. We conclude that loss of Bag3 in CMs leads to age-dependent differences in autophagy and cardiac dysfunction. Increased non-canonical autophagic flux in the juvenile period removes soluble proteins involved in cardiac contraction, leading to early-stage cardiomyopathy, which is prevented by reiterative CQ treatment.

Aluminium Chloride instead of Ferric chloride for inducing superior sagittal sinus thrombosis to reduce ferromagnetic artifacts on MRI-imaging in experimental models.

Using ferric chloride (FeCl3) to induce experimental superior sagittal sinus (SSS) thrombosis might interfere with magnetic resonance imaging (MRI)-assisted visualization and evaluation of the thrombus, the brain parenchyma, and the quality of the occlusion. The aim of this study was to investigate whether aluminum chloride (AlCl3)-induced thrombosis of the SSS has comparable properties to those of FeCl3 without causing artifacts in MRI. SSS thrombosis was induced in 14 male Wistar rats by exposure of the SSS and subsequent topical application of a filter paper strip soaked in AlCl3 (n = 7) or FeCl3 (n = 7) over a period of 15 min. The animals with AlCl3-induced SSS thrombosis showed a constant and complete occlusion with in histological analysis large thrombi. Blood flow measurements indicated a significant reduction on the first and seventh postoperative day compared to preoperative measurements. MRI enabled visualization and subsequent evaluation of the thrombus and the surrounding parenchyma. In comparison, FeCl3-induced SSS thrombosis could not be evaluated by MRI due to artifacts caused by the paramagnetic properties and increased susceptibility of FeCl3. The occluded sinus and the surrounding area appeared hypointense. The quality of SSS occlusion by AlCl3 was comparable to that of FeCl3. AlCl3 therefore represents a significant alternative substance in experimental SSS thrombosis ideally suited for studies using MRI.

A Homozygous NDUFS6 Variant Associated with Neuropathy and Optic Atrophy.

Background: The NADH dehydrogenase [ubiquinone] iron-sulfur protein 6 (NDUFS6) gene encodes for an accessory subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (complex I). Bi-allelic NDUFS6 variants have been linked with a severe disorder mostly reported as a lethal infantile mitochondrial disease (LMID) or Leigh syndrome (LS). Objective: Here, we identified a homozygous variant (c.309 + 5 G > A) in NDUFS6 in one male patient with axonal neuropathy accompanied by loss of small fibers in skin biopsy and further complicated by optic atrophy and borderline intellectual disability. Methods: To address the pathogenicity of the variant, biochemical studies (mtDNA copy number quantification, ELISA, Proteomic profiling) of patient-derived leukocytes were performed. Results: The analyses revealed loss of NDUFS6 protein associated with a decrease of three further mitochondrial NADH dehydrogenase subunit/assembly proteins (NDUFA12, NDUFS4 and NDUFV1). Mitochondrial copy number is not altered in leukocytes and the mitochondrial biomarker GDF15 is not significantly changed in serum. Conclusions: Hence, our combined clinical and biochemical data strengthen the concept of NDUFS6 being causative for a very rare form of axonal neuropathy associated with optic atrophy and borderline intellectual disability, and thus expand (i) the molecular genetic landscape of neuropathies and (ii) the clinical spectrum of NDUFS6-associated phenotypes.

Cardiomyocyte maturation alters molecular stress response capacities and determines cell survival upon mitochondrial dysfunction.

Cardiomyocyte maturation during pre- and postnatal development requires multiple intertwined processes, including a switch in energy generation from glucose utilization in the embryonic heart towards fatty acid oxidation after birth. This is accompanied by a boost in mitochondrial mass to increase capacities for oxidative phosphorylation and ATP generation required for efficient contraction. Whether cardiomyocyte differentiation is paralleled by augmented capacities to deal with reactive oxygen species (ROS), physiological byproducts of the mitochondrial electron transport chain (ETC), is less clear. Here we show that expression of genes and proteins involved in redox homeostasis and protein quality control within mitochondria increases after birth in the mouse and human heart. Using primary embryonic, neonatal and adult mouse cardiomyocytes in vitro we investigated how excessive ROS production induced by mitochondrial dysfunction affects cell survival and stress response at different stages of maturation. Embryonic and neonatal cardiomyocytes largely tolerate inhibition of ETC complex III by antimycin A (AMA) as well as ATP synthase (complex V) by oligomycin but are susceptible to complex I inhibition by rotenone. All three inhibitors alter the intracellular distribution and ultrastructure of mitochondria in neonatal cardiomyocytes. In contrast, adult cardiomyocytes treated with AMA undergo rapid morphological changes and cellular disintegration. At the molecular level embryonic cardiomyocytes activate antioxidative defense mechanisms, the integrated stress response (ISR) and ER stress but not the mitochondrial unfolded protein response upon complex III inhibition. In contrast, adult cardiomyocytes fail to activate the ISR and antioxidative proteins following AMA treatment. In conclusion, our results identified fundamental differences in cell survival and stress response in differentiated compared to immature cardiomyocytes subjected to mitochondrial dysfunction. The high stress tolerance of immature cardiomyocytes might allow outlasting unfavorable intrauterine conditions thereby preventing fetal or perinatal heart disease and may contribute to the regenerative capacity of the embryonic and neonatal mammalian heart.

Automated pipeline for nerve fiber selection and g-ratio calculation in optical microscopy: exploring staining protocol variations.

G-ratio is crucial for understanding the nervous system's health and function as it measures the relative myelin thickness around an axon. However, manual measurement is biased and variable, emphasizing the need for an automated and standardized technique. Although deep learning holds promise, current implementations lack clinical relevance and generalizability. This study aimed to develop an automated pipeline for selecting nerve fibers and calculating relevant g-ratio using quality parameters in optical microscopy. Histological sections from the sciatic nerves of 16 female mice were prepared and stained with either p-phenylenediamine (PPD) or toluidine blue (TB). A custom UNet model was trained on a mix of both types of staining to segment the sections based on 7,694 manually delineated nerve fibers. Post-processing excluded non-relevant nerves. Axon diameter, myelin thickness, and g-ratio were computed from the segmentation results and its reliability was assessed using the intraclass correlation coefficient (ICC). Validation was performed on adjacent cuts of the same nerve. Then, morphometrical analyses of both staining techniques were performed. High agreement with the ground truth was shown by the model, with dice scores of 0.86 (axon) and 0.80 (myelin) and pixel-wise accuracy of 0.98 (axon) and 0.94 (myelin). Good inter-device reliability was observed with ICC at 0.87 (g-ratio) and 0.83 (myelin thickness), and an excellent ICC of 0.99 for axon diameter. Although axon diameter significantly differed from the ground truth (p = 0.006), g-ratio (p = 0.098) and myelin thickness (p = 0.877) showed no significant differences. No statistical differences in morphological parameters (g-ratio, myelin thickness, and axon diameter) were found in adjacent cuts of the same nerve (ANOVA p-values: 0.34, 0.34, and 0.39, respectively). Comparing all animals, staining techniques yielded significant differences in mean g-ratio (PPD: 0.48 ± 0.04, TB: 0.50 ± 0.04), myelin thickness (PPD: 0.83 ± 0.28 µm, TB: 0.60 ± 0.20 µm), and axon diameter (PPD: 1.80 ± 0.63 µm, TB: 1.78 ± 0.63 µm). The proposed pipeline automatically selects relevant nerve fibers for g-ratio calculation in optical microscopy. This provides a reliable measurement method and serves as a potential pre-selection approach for large datasets in the context of healthy tissue. It remains to be demonstrated whether this method is applicable to measure g-ratio related with neurological disorders by comparing healthy and pathological tissue. Additionally, our findings emphasize the need for careful interpretation of inter-staining morphological parameters.

Muscle diffusion MRI reveals autophagic buildup in a mouse model for Pompe disease.

Quantitative muscle MRI is increasingly important in the non-invasive evaluation of neuromuscular disorders and their progression. Underlying histopathotological alterations, leading to changes in qMRI parameters are incompletely unraveled. Early microstructural differences of unknown origin reflected by Diffusion MRI in non-fat infiltrated muscles were detected in Pompe patients. This study employed a longitudinal approach with a Pompe disease mouse model to investigate the histopathological basis of these changes. Monthly scans of Pompe (Gaa6neo/6neo) and wildtype mice (age 1-8 months) were conducted using diffusion MRI, T2-mapping, and Dixon-based water-fat imaging on a 7 T scanner. Immunofluorescence studies on quadriceps muscles were analyzed for lysosomal accumulations and autophagic buildup and correlated with MRI outcome measures. Fat fraction and water-T2 did not differ between groups and remained stable over time. In Pompe mice, fractional anisotropy increased, while mean diffusivity (MD) and radial diffusivity (RD) decreased in all observed muscles. Autophagic marker and muscle fibre diameter revealed significant negative correlations with reduced RD and MD, while lysosomal marker did not show any change or correlation. Using qMRI, we showed diffusion changes in muscles of presymptomatic Pompe mice without fat-infiltrated muscles and correlated them to autophagic markers and fibre diameter, indicating diffusion MRI reveals autophagic buildup.

Dysregulation of Metabolism and Proteostasis in Skeletal Muscle of a Presymptomatic Pompe Mouse Model.

Pompe disease is a rare genetic metabolic disorder caused by mutations in acid-alpha glucoside (GAA) leading to pathological lysosomal glycogen accumulation associated with skeletal muscle weakness, respiratory difficulties and cardiomyopathy, dependent from the GAA residual enzyme activity. This study aimed to investigate early proteomic changes in a mouse model of Pompe disease and identify potential therapeutic pathways using proteomic analysis of skeletal muscles from pre-symptomatic Pompe mice. For this purpose, quadriceps samples of Gaa6neo/6neo mutant (Pompe) and wildtype mice, at the age of six weeks, were studied with three biological replicates for each group. The data were validated with skeletal muscle morphology, immunofluorescence studies and western blot analysis. Proteomic profiling identified 538 significantly upregulated and 16 significantly downregulated proteins in quadriceps muscles derived from Pompe animals compared to wildtype mice. The majority of significantly upregulated proteins were involved in metabolism, translation, folding, degrading and vesicular transport, with some having crucial roles in the etiopathology of other neurological or neuromuscular diseases. This study highlights the importance of the early diagnosis and treatment of Pompe disease and suggests potential add-on therapeutic strategies targeting protein dysregulations.

Molecular and cellular evidence for the impact of a hypertrophic cardiomyopathy-associated RAF1 variant on the structure and function of contractile machinery in bioartificial cardiac tissues.

Noonan syndrome (NS), the most common among RASopathies, is caused by germline variants in genes encoding components of the RAS-MAPK pathway. Distinct variants, including the recurrent Ser257Leu substitution in RAF1, are associated with severe hypertrophic cardiomyopathy (HCM). Here, we investigated the elusive mechanistic link between NS-associated RAF1S257L and HCM using three-dimensional cardiac bodies and bioartificial cardiac tissues generated from patient-derived induced pluripotent stem cells (iPSCs) harboring the pathogenic RAF1 c.770 C > T missense change. We characterize the molecular, structural, and functional consequences of aberrant RAF1-associated signaling on the cardiac models. Ultrastructural assessment of the sarcomere revealed a shortening of the I-bands along the Z disc area in both iPSC-derived RAF1S257L cardiomyocytes and myocardial tissue biopsies. The aforementioned changes correlated with the isoform shift of titin from a longer (N2BA) to a shorter isoform (N2B) that also affected the active force generation and contractile tensions. The genotype-phenotype correlation was confirmed using cardiomyocyte progeny of an isogenic gene-corrected RAF1S257L-iPSC line and was mainly reversed by MEK inhibition. Collectively, our findings uncovered a direct link between a RASopathy gene variant and the abnormal sarcomere structure resulting in a cardiac dysfunction that remarkably recapitulates the human disease.

Rise and fall of peroxisomes during Alzheimer´s disease: a pilot study in human brains.

Peroxisomes are eukaryotic organelles that rapidly change in number depending on the metabolic requirement of distinct cell types and tissues. In the brain, these organelles are essential for neuronal migration and myelination during development and their dysfunction is associated with age-related neurodegenerative diseases. Except for one study analysing ABCD3-positive peroxisomes in neurons of the frontal neocortex of Alzheimer disease (AD) patients, no data on other brain regions or peroxisomal proteins are available. In the present morphometric study, we quantified peroxisomes labelled with PEX14, a metabolism-independent peroxisome marker, in 13 different brain areas of 8 patients each either with low, intermediate or high AD neuropathological changes compared to 10 control patients. Classification of patient samples was based on the official ABC score. During AD-stage progression, the peroxisome density decreased in the area entorhinalis, parietal/occipital neocortex and cerebellum, it increased and in later AD-stage patients decreased in the subiculum and hippocampal CA3 region, frontal neocortex and pontine gray and it remained unchanged in the gyrus dentatus, temporal neocortex, striatum and inferior olive. Moreover, we investigated the density of catalase-positive peroxisomes in a subset of patients (> 80 years), focussing on regions with significant alterations of PEX14-positive peroxisomes. In hippocampal neurons, only one third of all peroxisomes contained detectable levels of catalase exhibiting constant density at all AD stages. Whereas the density of all peroxisomes in neocortical neurons was only half of the one of the hippocampus, two thirds of them were catalase-positive exhibiting increased levels at higher ABC scores. In conclusion, we observed spatiotemporal differences in the response of peroxisomes to different stages of AD-associated pathologies.

Gadolinium contrast agents: dermal deposits and potential effects on epidermal small nerve fibers.

Small fiber neuropathy (SFN) affects unmyelinated and thinly myelinated nerve fibers causing neuropathic pain with distal distribution and autonomic symptoms. In idiopathic SFN (iSFN), 30% of the cases, the underlying aetiology remains unknown. Gadolinium (Gd)-based contrast agents (GBCA) are widely used in magnetic resonance imaging (MRI). However, side-effects including musculoskeletal disorders and burning skin sensations were reported. We investigated if dermal Gd deposits are more prevalent in iSFN patients exposed to GBCAs, and if dermal nerve fiber density and clinical parameters are likewise affected. 28 patients (19 females) with confirmed or no GBCA exposure were recruited in three German neuromuscular centers. ISFN was confirmed by clinical, neurophysiological, laboratory and genetic investigations. Six volunteers (two females) served as controls. Distal leg skin biopsies were obtained according to European recommendations. In these samples Gd was quantified by elemental bioimaging and intraepidermal nerve fibers (IENF) density via immunofluorescence analysis. Pain phenotyping was performed in all patients, quantitative sensory testing (QST) only in a subset (15 patients; 54%). All patients reported neuropathic pain, described as burning (n = 17), jabbing (n = 16) and hot (n = 11) and five QST scores were significantly altered. Compared to an equal distribution significantly more patients reported GBCA exposures (82%), while 18% confirmed no exposures. Compared to unexposed patients/controls significantly increased Gd deposits and lower z-scores of the IENF density were confirmed in exposed patients. QST scores and pain characteristics were not affected. This study suggests that GBCA exposure might alter IENF density in iSFN patients. Our results pave the road for further studies investigating the possible role of GBCA in small fiber damage, but more investigations and larger samples are needed to draw firm conclusions.

Genetic Screening Reveals Heterogeneous Clinical Phenotypes in Patients with Dilated Cardiomyopathy and Troponin T2 Variants.

BACKGROUND: Cardiomyopathies (CMs) are a heterogeneous and severe group of diseases that shows a highly variable cardiac phenotype and an incidence of app. 1/100.000. Genetic screening of family members is not yet performed routinely. PATIENTS AND METHODS: Three families with dilated cardiomyopathy (DCM) and pathogenic variants in the troponin T2, Cardiac Type (TNNT2) gene were included. Pedigrees and clinical data of the patients were collected. The reported variants in the TNNT2 gene showed a high penetrance and a poor outcome, with 8 of 16 patients dying or receiving heart transplantation. The age of onset varied from the neonatal period to the age of 52. Acute heart failure and severe decompensation developed within a short period in some patients. CONCLUSION: Family screening of patients with DCM improves risk assessment, especially for individuals who are currently asymptomatic. Screening contributes to improved treatment by enabling practitioners to set appropriate control intervals and quickly begin interventional measures, such as heart failure medication or, in selected cases, pulmonary artery banding.

Significantly higher expression of high-mobility group AT hook protein 2 (HMGA2) in the border zone of glioblastoma.

BACKGROUND: High-mobility group AT-hook protein 2 (HMGA2) is a gene regulatory protein that is correlated with metastatic potential and poor prognosis. It has been shown that HMGA2 is overexpressed in various tumors such as lung cancer or pancreatic cancer. The invasive character and highly aggressive structure of glioblastoma let us to investigate HMGA2 expression in the border zone of the tumor more closely. We compared HMGA2 expression between glioblastoma and normal brain tissue. In addition, we analyzed and compared HMGA2 expression in the border and center zones of tumors. Correlation tests between HMGA expression and clinical parameters such as MGMT-status and survival were performed. METHODS: Samples from 23 patients with WHO grade 4 glioblastomas were analyzed for HMGA2 expression using quantitative real-time polymerase chain reaction (qPCR) and immunohistochemistry (IHC) and correlated with clinical parameters. The areas from the tumor center and border were analyzed separately. Two normal brain tissue specimens were used as the controls. RESULTS: Our results confirm that HMGA2 is higher expressed in glioblastoma compared to healthy brain tissue (qPCR, P=0.013; IHC, P=0.04). Moreover, immunohistochemistry revealed significantly higher HMGA2 expression in the border zone of the tumor than in the tumor center zone (P=0.012). Survival analysis revealed a tendency for shorter survival when HMGA2 was highly expressed in the border zone. CONCLUSIONS: The results reveal an overexpression of HMGA2 in the border zone of glioblastomas; thus, the expression cluster of HMGA2 seems to be heterogenous and thorough borough surgical resection of the vital and aggressive border cells might be important to inhibit the invasive character of the tumor.