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46 result(s) for "Bleyer, Martina"
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Findings from transcriptomics and immunohistochemistry indicate an autoimmune disease targeting brainstem inhibitory interneurons in bovine spastic paresis
Bovine spastic paresis (BSP) is a progressive neuromuscular disease of unknown origin that causes persistent stiffness of the hind limbs. The symptoms are similar to those of human motor neuron diseases such as primary (PLS) or amyotrophic lateral sclerosis (ALS). BSP occurs worldwide in cattle production with an estimated prevalence of <1%. For Germany, this means that around 20,000 Holstein cattle are affected. BSP is generally considered a hereditary disease, but there is no prevention through breeding programs. As a result, BSP not only affects animal welfare but also leads to economic losses in milk and beef production. Here, we used transcriptomics to analyse the brainstem, spinal cord and affected gastrocnemius muscle tissue of eight animals affected by BSP and eight control animals from slaughterhouses to gain new insights into the molecular mechanisms underlying BSP. We found that the expression of several genes was significantly different in animals affected by BSP compared to control animals. Specific genes for inhibitory neurons were downregulated in the brainstems of the affected animals, namely CCK (cholecystokinin), NPY (neuropeptide Y), and SST (somatostatin). These inhibitory neurotransmitters influence cerebral movement control, among other processes. Furthermore, OOSP2 (oocyte secreted protein 2) was found to be significantly upregulated in the affected animals in all tissues. This expression could best be explained by the presence of T-follicular-helper cells which, through interleukin 21, can trigger a TH-2-dominated immune response and lead to autoimmune encephalitis. Further cases were sampled for confirmation and we detected cell infiltrates of activated microglia and T-cells in the brainstem using immunohistochemistry. Microglial foci were significantly more abundant in animals affected by BSP than control animals. We conclude that BSP is caused by an autoimmune reaction directed against inhibitory interneurons in the brainstem and is due to a combination of genetics and environmental influences. This may result in lost controlling influence on the upper motor neurons via extrapyramidal pathways and therefore triggers the specific symptoms of motor neuron disease.
A missense mutation in the highly conserved TNF-like domain of Ectodysplasin A is the candidate causative variant for X-linked hypohidrotic ectodermal dysplasia in Limousin cattle: Clinical, histological, and molecular analyses
Ectodysplasin A related hypohidrotic ectodermal dysplasia (XLHED) is a well-studied fetal developmental disorder in mammals that mainly affects ectodermal structures. It has been identified in a variety of species, including mice, rats, dogs, cattle, and humans. Here, we report the clinical, histological, and molecular biological analyses of a case of XLHED in Limousin cattle. An affected Limousin calf showed pathognomonic signs of ectodermal dysplasia, i.e. sparse hair and characteristic dental aplasia. Histopathologic comparison of hairy and glabrous skin and computed tomography of the mandible confirmed the phenotypic diagnosis. In addition, a keratoconjunctivitis sicca was noted in one eye, which was also confirmed histopathologically. To identify the causative variant, we resequenced the bovine X-chromosomal ectodysplasin A gene ( EDA ) of the affected calf and compared the sequences to the bovine reference genome. A single missense variant (rs439722471) at position X:g.80411716T>C (ARS-UCD1.3) was identified. The variant resulted in an amino acid substitution from glutamic acid to glycine within the highly conserved TNF-like domain. To rule out the possibility that the variant was relatively common in the cattle population we genotyped 2,016 individuals including 40% Limousin cattle by fluorescence resonance energy transfer analysis. We also tested 5,116 multibreed samples from Run9 of the 1000 Bull Genomes Project for the said variant. The variant was not detected in any of the cattle tested, confirming the assumption that it was the causative variant. This is the first report of Ectodysplasin A related hypohidrotic ectodermal dysplasia in Limousin cattle and the description of a novel causal variant in cattle.
Favorable outcome of experimental islet xenotransplantation without immunosuppression in a nonhuman primate model of diabetes
Transplantation of pancreatic islets for treating type 1 diabetes is restricted to patients with critical metabolic lability resulting from the need for immunosuppression and the shortage of donor organs. To overcome these barriers, we developed a strategy to macroencapsulate islets from different sources that allow their survival and function without immunosuppression. Here we report successful and safe transplantation of porcine islets with a bioartificial pancreas device in diabetic primates without any immune suppression. This strategy should lead to pioneering clinical trials with xenotransplantation for treatment of diabetes and, thereby, represents a previously unidentified approach to efficient cell replacement for a broad spectrum of endocrine disorders and other organ dysfunctions.
N-terminal truncation of STAT1 transcription factor causes CD3- and CD20-negative non-Hodgkin lymphoma through upregulation of STAT3-mediated oncogenic functions
The cytokine-driven transcription factor STAT1 (signal transducer and activator of transcription 1) executes anti-microbial and pro-apoptotic functions, and loss-of-function mutations are associated with increased susceptibility to various infections and the development of tumors. A targeted mutation in mice expressing an N-terminally truncated STAT1 protein (STAT1-ΔN) typically develops splenomegaly in animals older than 6 months due to the formation of splenic non-Hodgkin lymphomas. The expression of the STAT1-ΔN variant resulted in the disruption of normal spleen architecture by malignant CD3- and CD20-negative tumor cells, which stained positively for both tyrosine-phosphorylated STAT1 and STAT3. Immunoblotting of lysates from isolated tumor cells revealed the cytokine-independent hyperphosphorylation of both STAT proteins, whereas the expression level of NF-κB was significantly reduced. Gel-shift assays showed that the DNA-binding activity of STAT1-ΔN was increased compared to the wild-type protein. This elevated level of tyrosine-phosphorylated STAT1-ΔN did not further increase upon stimulation of isolated tumor cells with either interferon-γ (IFNγ), lipopolysaccharide (LPS), or the combination of both. Since the truncation mutant was unable to accumulate in the nucleus upon cytokine stimulation, real-time PCR data from tumor tissue as well as from isolated, IFNγ/LPS-treated lymphoma cells demonstrated significantly reduced STAT1-regulated target gene expression despite its observed hyperphosphorylation. The nuclear import defect of tyrosine-phosphorylated STAT1-ΔN was associated with an elevated tyrosine-phosphorylation level of its antagonistic homolog STAT3, which is a known oncogene. These data demonstrate that the lack of STAT1 nuclear accumulation interferes with the functional balance between the two STAT proteins and, thereby, promotes the formation of phospho-STAT3-expressing CD3 -/- CD20 -/- non-Hodgkin lymphomas in the spleens of the diseased animals.
Taenia martis Cysticercosis in a Common Marmoset (Callithrix jacchus)
Taenia martis cysticercosis is a rare but recently more frequently reported disease that can affect both human and non-human primates as aberrant hosts. A common marmoset was noticed as being affected by advancing weight loss that did not respond to therapy and finally had to be euthanized due to poor prognosis. A complete necropsy with gross evaluation and subsequent histological and molecular analyses was performed, revealing the presence of a cysticercosis in the thoracic and pelvic cavity and in the mesentery. Molecular analysis identified the cestode as Taenia martis. This is the fifth case of Taenia martis cysticercosis in a non-human primate and the first case in a platyrrhine primate.
Magnetisation transfer, T1 and T2 relaxation in canine menisci of elderly dogs—an ex vivo study in stifle joints
Magnetic resonance imaging (MRI) is widely used in human medicine, offering multiple contrast mechanisms to visualise different tissue types. It is also gaining importance in veterinary medicine, including diagnosing joint disorders. The menisci of the stifle joint play a crucial role in the development of osteoarthritis (OA), and multi-parameter MRI of the menisci may aid in early OA diagnosis, potentially improving therapeutic outcomes. In a previous ex vivo study, we measured T2 relaxation times in menisci of elderly dogs with mild histological signs of degeneration but no clinical symptoms of lameness. As no significant changes in T2 relaxation times were observed in relation to histological scores, the present study extends this investigation by exploring more advanced MR parameters—including T1 relaxation time, T2* relaxation time, magnetisation transfer ratio (MTR), and magnetisation transfer saturation (MTsat)—to assess their potential for detecting early microstructural changes in the menisci. While T2* relaxation times and MTR showed no significant variation across histological scores, MTsat values increased with higher proteoglycan staining. In contrast, the apparent T1 relaxation time (T1app) was lower in menisci with elevated proteoglycan scores and increased with higher cellularity scores. The correlation between MTsat and proteoglycan content suggests that MTsat, along with T1app, could be a promising parameter for characterising the extracellular matrix. However, further research is needed to validate these findings.
Simultaneous targeting of KRAS and CDK4 synergistically induces durable growth arrest in pancreatic cancer cells
Mutant Ras oncoproteins, particularly KRAS, are among the most prevalent drivers of cancer. Small-molecule KRAS inhibitors have emerged as promising cancer therapeutics, yet resistance development remains a major hurdle. To overcome this challenge, we explored rational combination strategies aimed at enhancing therapeutic efficacy and durability. We show that the KRAS-G12C inhibitor Sotorasib synergizes with the CDK4/6 inhibitor Palbociclib to eliminate pancreatic ductal adenocarcinoma (PDAC) cells and organoids harboring KRAS-G12C mutations. This synergy was especially pronounced following drug washout, indicating a durable cellular response. Similar synergistic effects were observed in non-small-cell lung cancer (NSCLC) cells. Additionally, the KRAS-G12D inhibitor MRTX1133 cooperated with Palbociclib to suppress growth of KRAS-G12D-mutant PDAC cells. Mechanistically, the combinations induced sustained cell cycle arrest, marked by reduced RB phosphorylation, decreased E2F1 expression, and increased levels of CDKN1B/p27. Deletion of CDKN1B largely reversed the growth-inhibitory effect, highlighting its essential role in mediating the observed synergy. In an orthotopic, immunocompetent mouse model of PDAC, MRTX1133 significantly reduced tumor growth and extended survival; however, despite its ability to suppress RB phosphorylation, Palbociclib failed to enhance these effects. Single-cell RNA sequencing suggested that Palbociclib treatment induces tumor vascularization, perhaps contributing to the lack of drug synergy observed in vivo. In summary, our findings demonstrate the therapeutic potential of enhancing cell cycle restriction point activation in KRAS inhibitor-based therapies, while emphasizing the importance of placing combination therapies into a suitable context.
Histological Findings and T2 Relaxation Time in Canine Menisci of Elderly Dogs—An Ex Vivo Study in Stifle Joints
Osteoarthritis is a chronic disease that often affects the canine stifle joint. Due to their biomechanical function, the menisci in the canine stifle play an important role in osteoarthritis. They compensate for the incongruence in the joint and distribute and minimize compressive loads, protecting the hyaline articular cartilage from damage. Meniscal degeneration favors the development and progression of stifle joint osteoarthritis. Qualitative magnetic resonance imaging (MRI) is the current golden standard for detecting meniscal changes, but it has limitations in detecting early signs of meniscal degeneration. A quantitative MRI offers new options for detecting early structural changes. T2 mapping can especially visualize structural changes such as altered collagen structures and water content, as well as deviations in proteoglycan content. This study evaluated T2 mapping and performed a histological scoring of menisci in elderly dogs that had no or only low radiographic osteoarthritis grades. A total of 16 stifles from 8 older dogs of different sex and breed underwent ex vivo magnet resonance imaging, including a T2 mapping pulse sequence with multiple echoes. A histological analysis of corresponding menisci was performed using a modified scoring system. The mean T2 relaxation time was 18.2 ms and the mean histological score was 4.25. Descriptive statistics did not reveal a correlation between T2 relaxation time and histological score. Ex vivo T2 mapping of canine menisci did not demonstrate histological changes, suggesting that early meniscal degeneration can be present in the absence of radiological signs of osteoarthritis, including no significant changes in T2 relaxation time.
LPS-Induced Lung Inflammation in Marmoset Monkeys – An Acute Model for Anti-Inflammatory Drug Testing
Increasing incidence and substantial morbidity and mortality of respiratory diseases requires the development of new human-specific anti-inflammatory and disease-modifying therapeutics. Therefore, new predictive animal models that closely reflect human lung pathology are needed. In the current study, a tiered acute lipopolysaccharide (LPS)-induced inflammation model was established in marmoset monkeys (Callithrix jacchus) to reflect crucial features of inflammatory lung diseases. Firstly, in an ex vivo approach marmoset and, for the purposes of comparison, human precision-cut lung slices (PCLS) were stimulated with LPS in the presence or absence of the phosphodiesterase-4 (PDE4) inhibitor roflumilast. Pro-inflammatory cytokines including tumor necrosis factor-alpha (TNF-α) and macrophage inflammatory protein-1 beta (MIP-1β) were measured. The corticosteroid dexamethasone was used as treatment control. Secondly, in an in vivo approach marmosets were pre-treated with roflumilast or dexamethasone and unilaterally challenged with LPS. Ipsilateral bronchoalveolar lavage (BAL) was conducted 18 hours after LPS challenge. BAL fluid was processed and analyzed for neutrophils, TNF-α, and MIP-1β. TNF-α release in marmoset PCLS correlated significantly with human PCLS. Roflumilast treatment significantly reduced TNF-α secretion ex vivo in both species, with comparable half maximal inhibitory concentration (IC(50)). LPS instillation into marmoset lungs caused a profound inflammation as shown by neutrophilic influx and increased TNF-α and MIP-1β levels in BAL fluid. This inflammatory response was significantly suppressed by roflumilast and dexamethasone. The close similarity of marmoset and human lungs regarding LPS-induced inflammation and the significant anti-inflammatory effect of approved pharmaceuticals assess the suitability of marmoset monkeys to serve as a promising model for studying anti-inflammatory drugs.
Engineered heart muscle allografts for heart repair in primates and humans
Cardiomyocytes can be implanted to remuscularize the failing heart 1 , 2 , 3 , 4 , 5 , 6 – 7 . Challenges include sufficient cardiomyocyte retention for a sustainable therapeutic impact without intolerable side effects, such as arrhythmia and tumour growth. We investigated the hypothesis that epicardial engineered heart muscle (EHM) allografts from induced pluripotent stem cell-derived cardiomyocytes and stromal cells structurally and functionally remuscularize the chronically failing heart without limiting side effects in rhesus macaques. After confirmation of in vitro and in vivo (nude rat model) equivalence of the newly developed rhesus macaque EHM model with a previously established Good Manufacturing Practice-compatible human EHM formulation 8 , long-term retention (up to 6 months) and dose-dependent enhancement of the target heart wall by EHM grafts constructed from 40 to 200 million cardiomyocytes/stromal cells were demonstrated in macaques with and without myocardial infarction-induced heart failure. In the heart failure model, evidence for EHM allograft-enhanced target heart wall contractility and ejection fraction, which are measures for local and global heart support, was obtained. Histopathological and gadolinium-based perfusion magnetic resonance imaging analyses confirmed cell retention and functional vascularization. Arrhythmia and tumour growth were not observed. The obtained feasibility, safety and efficacy data provided the pivotal underpinnings for the approval of a first-in-human clinical trial on tissue-engineered heart repair. Our clinical data confirmed remuscularization by EHM implantation in a patient with advanced heart failure. Epicardial engineered heart muscle allografts from induced pluripotent stem cell-derived cardiomyocytes can safely and effectively remuscularize chronically failing hearts in rhesus macaques, leading to improved cardiac function and paving the way for human clinical trials.