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Neuro-behcet's syndrome: epidemiology, mechanisms, and emerging strategies in diagnosis and treatment
No full textNeuro-Behçet’s Syndrome (NBS) is a severe and heterogeneous neurological manifestation of Behcet’s Syndrome (BS), a systemic vasculitis with a distinct prevalence along the historic Silk Road. This review synthesizes current knowledge on epidemiology, pathophysiology, clinical spectrum, and emerging treatment strategies for NBS. Genetic predisposition, particularly the HLA B51 allele, coupled with environmental triggers contributes to an aberrant immune response characterized by immune mediated vasculitis, blood brain barrier disruption, and the release of pro inflammatory cytokines such as TNF-α, IL-6, and IL-17. Two primary subtypes of NBS are recognized: parenchymal NBS, manifesting as meningoencephalitis with brain-stem, basal ganglia, or white matter lesions; and non-parenchymal NBS, which predominantly involves vascular complications such as cerebral venous sinus thrombosis. Clinical presentations range from cranial neuropathies and pyramidal signs to cognitive decline and psychiatric disturbances, with diagnosis relying on a combination of clinical findings, cerebrospinal fluid analysis, and advanced neuroimaging techniques. Magnetic Resonance Imaging (MRI) remains the diagnostic modality of choice, revealing T2 weighted hyperintensities and diffusion abnormalities, while emerging techniques such as Diffusion Tensor Imaging (DTI) further elucidate white matter microstructural changes. Current therapeutic approaches emphasize early and aggressive immunosuppression using high dose corticosteroids, conventional immunosuppressants, and biologic agents such as TNF-α inhibitors and IL-6 receptor antagonists. Despite these advances, long term outcomes remain suboptimal, prompting ongoing research into novel biomarkers and targeted therapies. The evidence presented underscores the urgent need for a multidisciplinary approach to optimize diagnosis, management, and patient outcomes in NBS
Loss of cardiomyocyte eukaryotic elongation factor 1A2 in adult mice triggers cardiomyopathy due to defective proteostasis
No full textThe eukaryotic elongation factor 1A (eEF1A) is known for its canonical role to promote the translocation of aminoacyl-tRNAs to ribosomes during translational elongation, but also has non-canonical functions. In mammals, two paralogs of eEF1A exist: Whereas eEF1A1 is ubiquitously expressed, eEF1A2 expression is restricted to adult cardiomyocytes, skeletal myocytes and neurons. Although patients with mutations in EEF1A2 develop cardiomyopathies, the mechanism involved is unknown. To study the role of cardiac eEF1A2 in adult mice, we generated adult induced, cardiomyocyte specific Eef1a2 knock-out (eEF1A2-cKO), and Eef1a1/Eef1a2 double knock-out (eEF1A1/eEF1A2-cKO) mice. eEF1A2-cKO mice developed cardiomyopathy associated with increased mouse mortality, cardiac dysfunction and fibrosis, but unchanged global protein synthesis rates, while eEF1A1/eEF1A2-cKO mice exhibited early sudden death. Combined RNA sequencing, proteomics and ribosomal sequencing analyses from hearts of eEF1A2-cKO and eEF1A1/eEF1A2-cKO mice revealed a post-transcriptional upregulation of ribosomal proteins and translational regulators. On the other hand, we observed an increase of autophagosomes and protein aggregates in heart tissue of eEF1A2-cKO mice as sign of defective autophagy. Mechanistically, we demonstrate that eEF1A2 acts as a chaperone in cardiomyocytes. Finally, administration of rapamycin (mTORC1 inhibitor) at an early disease stage in eEF1A2-cKO mice normalized systolic cardiac dysfunction and mortality and eliminated the accumulation of autophagosomes and protein aggregates. Together, we found that eEF1A2 promotes proteostasis in cardiomyocytes, at least in part by supporting protein folding. More importantly, increased mortality, cardiomyopathy and proteostasis defects due to the lack of eEF1A2 could be rescued by administration of rapamycin, which might therefore constitute a treatment strategy for patients with EEF1A2 mutations
Conservation and specificity in Bacillus biofilm dynamics: on structure and function of B. cereus Camelysins
Full text linkThe B. cereus family comprises members highly pathogenic for mammals or insects, with B. anthracis and B. thuringiensis respectively as notable examples. The biofilm operon of these bacteria encodes two TasA-like proteins, the 60% identical Camelysins CalY1 and CalY2. In this study, we observed that at neutral pH CalY2 alone polymerizes readily into filaments, whereas CalY1 forms a polydispersed mixture of oligomers without filament formation. However, at basic or acidic pH CalY1 also modestly polymerizes. CalY2 polymerization into filaments involves ß-sheet remodeling via donor strand complementation, as demonstrated here by a combination of NMR and AlphaFold studies. In contrast to TasA of B. subtilis, this process is spontaneous and does not require initiation by a TapA homolog. NMR studies show that the functionally relevant region (b1–b2–b3) of the CalY2 monomer structure closely resembles that of B. subtilis TasA, and differs from AlphaFold models. A survey of AlphaFold 2 predictions on 12 homologous B. cereus group Camelysins yielded only four correctly predicted b1–b2–b3 segments, which decreased to one when using AlphaFold 3. Since crucial residues in the protomer contact region are conserved among TasA-like proteins, we investigated whether family members of different species could form mixed filaments. NMR revealed features in CalY2 filaments that are structurally conserved with TasA filaments but sequentially different, promoting specificity. These interactions and differences, respectively, involve the C-terminus and the beginning of b3, which most likely hinder joint TasA and CalY1 copolymerization. A protease activity could not be observed for the heterologously expressed B. cereus Camelysins. Significance: The B. cereus group includes extremely harmful and surprisingly benign bacterial strains. The Anthrax-toxin-producing B. anthracis is one of the most toxic bacterial threats to man, whereas B. thuringiensis toxin is used as a biological insecticide. Other B. cereus strains pose problems in food production and medical implant usage. These bacteria can exist as biofilms allowing them to survive and proliferate, an essential feature of which are protein filaments. Here we characterize the B. cereus Camelysins CalY1 and CalY2 and compare their structure and filament formation with B. subtilis filaments to understand principles determining patterns of conservation and specificity. This investigation provides the basis for developing novel means to suppress or enhance biofilms with potential benefits for plant protection
Dynamics of clonal hematopoiesis and cellular responses to stress-induced toxicity in autologous stem cell transplantation
Full text linkAutologous stem cell transplantation (ASCT) involves harvesting hematopoietic stem and progenitor cells (HSPCs) prior to chemotherapy and subsequent repopulation of the bone marrow. This process imposes a bottleneck, providing a framework to dissect the unresolved short- and long-term clonal dynamics during hematopoietic reconstitution. By integrating bulk error-corrected targeted sequencing of clonal hematopoiesis (CH)-associated genes with mitochondrial single-cell Assay for Transposase-Accessible Chromatin sequencing (mtscATAC-seq), we characterized mutational trajectories in frequently altered hematological genes and traced clonal evolution through somatic mitochondrial DNA variants, revealing post-transplant cellular heterogeneity and clonal architecture. Among 60 patients (multiple myeloma, n = 51; non-Hodgkin lymphoma, n = 6; Hodgkin lymphoma, n = 3), CH-associated mutations were identified in 53% pre-ASCT, predominantly involving DNMT3A. A transient increase in mutation counts and gene diversity occurred 10-25 days post-ASCT, with a gradual clonal expansion two years post-transplantation. Tandem ASCT amplified clonal complexity, with a twofold increase in mutation count and gene-level diversity, while preserving clonal trajectories across both transplant courses. Mitochondrial single-cell profiling in longitudinal samples of 3 patients showed patient-specific immune reconstitution and clonal dynamics, with balanced multilineage output from graft HSPCs. Collectively, our findings provide a firsthand comprehensive view of ASCT-induced clonal dynamics and immune reconstitution, paving the way for targeted gene-specific post-transplant monitoring
Similar and yet not quite the same: unmasking distinct type I interferon signatures in ANCA vasculitis
No full textAntineutrophil cytoplasmic autoantibody–associated vasculitides can be classified by clinical phenotype or antineutrophil cytoplasmic autoantibody specificity, with overlapping yet distinct characteristics. Transcriptomic analyses of kidney biopsies from 2 French antineutrophil cytoplasmic autoantibody–associated vasculitis (AAV) cohorts revealed a pronounced type I interferon signature in microscopic polyangiitis (microscopic polyangiitis/myeloperoxidaseAAV) compared with granulomatosis with polyangiitis (granulomatosis with polyangiitis/proteinase 3-AAV). Among biopsies with high interferon scores, 66% were myeloperoxidase-AAV and 28% proteinase 3-AAV. The interferon score was associated with decreased kidney survival. These findings highlight AAV patient heterogeneity and support targeted treatment approaches
A simulation procedure for stereological correction of early AMD lesion sizes observed in single OCT-B-scans
Full text linkPURPOSE: Early lesions caused by age-related macular degeneration (AMD) are imaged by optical coherence tomography (OCT) in unprecedented detail. Most probably, however, the sampling plane of an OCT scan meets a given lesion noncentrally, and the observed sizes of its diameter, cross-sectional area, and volume must be stereologically corrected. METHODS: Stereological corrections are obtained by a simulation procedure, which is applied to the leading scans in a consecutive sample of 100 early AMD participants. RESULTS: Mean corrections for lesion diameter, cross-sectional area and volume amount to +9.1%, +32.0%, and +46.6%, respectively. After correction, AMD stage classifications with respect to the 125-µm diameter cutpoint had to be changed for seven participants. CONCLUSIONS: Simulation results confirm that for lesions pictured and measured in OCT scans - regardless of the accuracy of OCT imaging - stereological correction of observed sizes is compelling and unavoidable. TRANSLATIONAL RELEVANCE: Categorial AMD classifications based on observed OCT data must be reexaminated after stereological correction
Ligand-specific activation trajectories dictate GPCR signalling in cells
Full text linkG-protein-coupled receptors (GPCRs) are key mediators of cell communication and represent the most important class of drug targets. Biophysical studies with purified GPCRs in vitro have suggested that they exist in an equilibrium of distinct inactive and active states, which is modulated by ligands in an efficacy-dependent manner. However, how efficacy is encoded and whether multiple receptor states occur in living cells remain unclear. Here we use genetic code expansion and bioorthogonal labelling to generate a panel of fluorescence-based biosensors for a prototypical GPCR, the M(2) muscarinic acetylcholine receptor (M(2)R). These biosensors enable real-time monitoring of agonist-promoted conformational changes across the receptor’s extracellular surface in intact cells. We demonstrate that different agonists produce equilibria of at least four distinct active states of the G-protein-bound M(2)R, each with a different ability to activate G proteins. The formation of these M(2)R–G-protein complexes occurs over 0.2–5 s along trajectories that involve both common and ligand-specific conformational changes and appear to determine G-protein selectivity. These observations reveal the molecular nature of ligand efficacy in intact cells. Selectively exploiting such different GPCR activation trajectories and conformational equilibria may open new avenues for GPCR drug discovery
Pathway for the development of ATR inhibitors in pediatric malignancies: an ACCELERATE multistakeholder analysis
Full text linkPURPOSE: High levels of DNA replication stress and defects in the DNA damage response (DDR) pathways are vulnerabilities of many poor prognosis childhood malignancies. Ataxia telangiectasia and Rad3-related protein (ATR) is a key regulator of these pathways and constitutes an attractive target, especially in combination. However, the malignancies where ATR inhibitors have maximum benefit and synergistic combinations differ between adults and children. DESIGN: ACCELERATE convened a multistakeholder meeting and conducted review and analysis to propose the optimal pathway for the development of ATR inhibitors in pediatric malignancies. RESULTS: Considering the lack of identified biomarkers, the initial evaluation of ATR inhibitors should focus on Ewing sarcoma, rhabdomyosarcoma, and neuroblastoma in view of their high levels of DNA replication stress and defects in DDR pathways. Early phase trials of ATR inhibitors should be iterative, based on a clear hypothesis with responders and nonresponders undergoing detailed molecular analysis and a revised new hypothesis generated. Trial designs should restrict monotherapy evaluation to a brief exposure in a small number of patients and progress rapidly to combinations. Highlighted combination partners are poly(ADP-ribose) polymerase inhibitors and antibody drug conjugates with topoisomerase I inhibitor payloads. Combinations with ALK inhibitors (in ALK/MYCN-aberrant neuroblastoma) and aurora A kinase (in MYCN-amplified) are supported by robust mechanisms of action and preclinical data. Early interactions with regulators are crucial, and early phase clinical trials should be conducted in regulatory-approved, academic-sponsored, industry-supported, platform trials. CONCLUSION: ATR inhibitors are a prototype for the development of medicinal products in a limited pediatric population. For the substantial potential of ATR inhibitors in children with malignancy to be realized, strategic planning between academia, industry, regulators, and patient advocates is vital
Blood-based obesity biomarkers and their relevance for disease risk
No full textObesity is a risk factor for chronic diseases and early death; however, the underlying mechanisms are not fully understood. Whereas insulin resistance and inflammation are established pathways in several of these relationships, it is less clear how increases in body adipose tissue relate to these pathways and disease risk. Several adipose tissue-derived blood-based biomarkers have been identified as purported mediators, including adipokines, inflammatory cytokines and sex steroid hormones. Traditionally, these markers were discovered in animal models and their relevance in humans has then been investigated in epidemiological studies. Today, proteomics and metabolomics approaches in human observational studies are used to discover obesity biomarkers in blood, supported by Mendelian randomization studies to draw causal inferences. Here we review adipose tissue-derived blood-based obesity biomarkers and their relevance for disease risk, along with their potential role as mediators. Proteomics and metabolomics studies have partly re-identified traditional biomarkers, but more large-scale prospective analyses are needed to obtain evidence of the relevance of omics-based and traditional obesity biomarkers to disease
Non-viral in situ gene editing effectively and safely rescues congenital ichthyosis-causing mutations in human skin
No full textAutosomal recessive congenital ichthyosis (ARCI) comprises a heterogeneous group of rare, severe genodermatoses that profoundly reduce patients’ quality of life and for which no curative therapies are currently available. In this study, we demonstrate clinically relevant in situ correction of the most prevalent ARCI-associated mutation, TGM1 c.877-2A>G, a pathogenic splice-site variant, using human disease models. Transient modulation of the skin barrier followed by topical delivery of the cytosine base editor eTD encapsulated in lipid nanoparticles resulted in restoration of approximately 30% of wild-type transglutaminase 1 activity in treated skin tissue. Repeated dosing was well tolerated and revealed an excellent safety profile, with no evidence of systemic exposure to either the lipid nanoparticles or the genetic payload, as confirmed by highly sensitive analyses including desorption electrospray ionization (DESI) metabolic imaging. Together, these data provide a comprehensive preclinical framework supporting the feasibility of in situ gene correction for genodermatoses and highlight its potential to enable curative, next-generation therapies for severe inherited skin disorders