Search Results (317)

Classic Hodgkin lymphoma (cHL) is a distinctive B-cell malignancy defined by the presence of scarce but pathobiologically dominant Hodgkin Reed-Sternberg (HRS) cells within an inflammatory tumor microenvironment (TME). Although representing less than 10% of total tumor cellularity, HRS cells shape the TME by recruiting and functionally polarizing immune and stromal elements through cytokine- and chemokine-mediated signaling. Morphologically, HRS cells are large, atypical, often binucleated or multinucleated cells with prominent eosinophilic nucleoli and abundant cytoplasm, giving rise to the classic “owl’s eye” appearance. Distinct morphological variants—including lacunar, mummified, mononuclear, and anaplastic forms—contribute to the histopathologic diversity across cHL subtypes such as nodular sclerosis, mixed cellularity, lymphocyte-rich, and lymphocyte-depleted disease. The immunophenotype of HRS cells is equally characteristic, with strong and uniform CD30 expression, frequent CD15 positivity, reduced expression of B-cell markers (CD20, CD79A/B), and partial retention of PAX5, reflecting profound lineage dysregulation. Aberrant expression of activation markers and immune-evasion molecules, including PD-L1 driven by recurrent 9p24.1 amplification, underscores their capacity for immune escape. Genetically, HRS cells display alterations affecting NF-κB, JAK/STAT, and PI3K/AKT pathways, facilitated by somatic mutations, chromosomal gains, and epigenetic remodeling that silence B-cell-defining genes. Despite reprogramming, clonality and somatic hypermutation patterns confirm their origin from germinal center B-cells, even in EBV-associated cases. Collectively, the morphology, phenotype, and genotype of HRS cells reveal a complex pathogenic network in which intrinsic oncogenic pathways and extrinsic TME interactions co-operate to sustain malignant transformation. Understanding these integrated mechanisms provides a biological foundation for current therapeutic strategies. Full article

Aging profoundly alters hematopoiesis by impairing stem cell self-renewal, skewing lineage differentiation, and remodeling immune and stromal compartments within the bone marrow. Consequently, these changes contribute to an increased susceptibility to leukemia. Conversely, leukemia contributes to systemic aging. Although the connection between hematopoietic aging and leukemogenesis has been well-recognized, the precise molecular and microenvironmental mechanisms underlying this association remain poorly elucidated. In recent years, emerging studies have identified altered clonal dynamics, chronic inflammation, and niche-dependent metabolic remodeling as major contributors to malignant transformation. Building on these findings, we synthesize current insights into how aging reprograms the hematopoietic ecosystem to promote leukemic initiation and progression, and furthermore, discuss potential strategies to counteract these processes by targeting aging-related pathways. Full article

Background/Objectives: Spontaneous remission (SR) of acute myeloid leukemia (AML) offers unique clinical insights into host anti-tumor immunity. However, the comprehensive clinical landscape and molecular dynamics of blast clearance and subsequent relapse remain unclear. This study aimed to elucidate these dynamics. Methods: We conducted a two-phase observational study: a systematic pooled analysis of 66 adult AML SR cases (1990–2024) to define clinical triggers and outcomes and longitudinal molecular tracking of two institutional cases to map clonal shifts (with immune profiling for Patient 1 and genomic tracking for both). Results: In the pooled analysis, infection was the predominant trigger, accounting for 78.6% (95% CI: 65.6–88.4%) of SR events. The dataset showed male predominance and monocytic leukemia enrichment (57.6% [95% CI: 44.1–70.4%]), suggesting lineage-specific susceptibility. SR duration and relapse risk were independent of the infection trigger, AML subtype, or age. When integrated with these clinical patterns, institutional tracking was consistent with a biphasic evolutionary model: an acute IL-8 surge alongside NKT and CD4+ T cell activation coincided with blast clearance, as observed primarily in Patient 1. Subsequently, the emergence of TP53 or NRAS mutations within persistent DNMT3A-mutated clones during relapse raised the hypothesis that unresolved chronic inflammation could potentially exert selective pressure favoring resistant subclones. Such interpretations remain correlational and require prospective validation. Conclusions: Our findings outline a clinical–evolutionary framework for AML SR. Remission durability likely relies on balancing acute immune activation with underlying clonal stability. These observational insights highlight complex immune-genomic crosstalk, generating hypotheses for future prospective investigations. Full article

Lower-grade gliomas (LGGs) often follow a relatively protracted clinical course; however, a substantial proportion eventually undergo malignant transformation to high-grade, treatment-refractory disease. This process has traditionally been interpreted in the context of stepwise histopathologic progression and recurrent genetic alterations. Increasing evidence, however, suggests that malignant transformation is more accurately understood as an evolutionary process shaped by the interplay among epigenetic constraints, cell-state plasticity, and selective pressures. In this review, we examine current evidence supporting a model in which early LGGs, particularly isocitrate dehydrogenase (IDH)-mutant tumors, are initially maintained in relatively restricted cellular states by metabolically imposed epigenetic programs, but progressively escape these constraints under the cumulative influence of therapy, hypoxia, immune remodeling, and genomic instability. We summarize recent advances demonstrating that progression from lower-grade to high-grade disease is accompanied by cell-state transitions characterized by altered lineage identity, acquisition of stem-like features, increased proliferative capacity, and adaptation to cellular stress. We further discuss how these transitions are reinforced by microenvironmental evolution, including vascular remodeling, extracellular matrix reorganization, and changes in immune composition, thereby creating conditions that favor clonal expansion, invasion, and therapeutic resistance. Particular attention is given to longitudinal, single-cell, and spatially resolved studies, which collectively indicate that malignant transformation is not a discrete event but a continuous process of evolutionary selection and phenotypic reprogramming. Finally, we discuss the translational implications of this framework for early risk stratification, biomarker development, and mechanism-based therapeutic intervention. By reframing malignant transformation in LGGs as a process of cell-state escape under persistent selective pressure, this review aims to provide an integrated view of glioma progression and to highlight new opportunities for precision monitoring and treatment. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) is a major antimicrobial-resistant pathogen affecting both human and animal health. Although historically associated with healthcare settings, MRSA is now established in livestock production and throughout the production chain. Its detection in animals, food products, and processing environments reflects the complex ecology of antimicrobial resistance (AMR) in modern food systems. This narrative review synthesizes current evidence on the molecular basis of methicillin resistance and multidrug resistance determinants, as well as the epidemiology of MRSA in food-associated settings. Particular emphasis is placed on its occurrence in animal-derived foods and key reservoirs within farms, slaughterhouses, and processing environments. Livestock-associated populations are dominated by clonal complex CC398. In contrast, CC9 is prevalent in pig production systems in Asia, while CC5-related lineages occur at the human and animal interface. MRSA has been detected in retail meat and animal-derived foods at low but measurable prevalence, indicating contamination during slaughter and processing. Virulence determinants include staphylococcal enterotoxins linked to food poisoning and Panton–Valentine leukocidin associated with severe infections. Biofilm formation and adhesins further support persistence and colonization. Epidemiological and molecular evidence indicates that livestock, processing environments, and food-contact surfaces act as interconnected reservoirs sustaining MRSA circulation. Human exposure occurs primarily through occupational contact and environmental pathways, whereas foodborne transmission appears less common. Effective control requires integrated surveillance, responsible antimicrobial use in livestock production, and strict hygiene practices throughout the production chain within a One Health framework. Full article

Shigella spp., and Escherichia coli exhibit notable genomic and phenotypic similarities, including serologically and genetically related somatic antigens. For example, the relationship among pathogenic strains E. coli 64474, O179, O188, and S. boydii O16 suggests a shared clonal origin. To evaluate their genomic proximity, a comparative genomics study was conducted using whole-genome sequencing. Comparative genomics involved rfb gene cluster regions and whole-genome comparisons. Phylogenomic inferences were performed using the virtual genome fingerprint (VGF) method with bootstrap support. The results revealed a high degree of genomic similarity and a close evolutionary relationship among E. coli strains, which also demonstrated genetic associations with clinically relevant pathotypes through the presence of virulence genes. Furthermore, serogroups 64474, O188, and S. boydii O16 exhibited close genetic relationships, suggesting that serotype 64474 could represent a novel serogroup, although its similarity to O188 indicates the influence of divergent factors. These findings support the hypothesis that these E. coli strains originated from a common clonal lineage, enhancing our understanding of serogroup diversity and the evolutionary dynamics within enteric pathogens. Full article

Background/Objectives: Myeloid neoplasms (MNs) with SF3B1 mutations define a distinct entity associated with a favorable prognosis. However, not all MN patients harboring SF3B1 mutations meet the diagnostic criteria for this entity, and different mutation types may be associated with distinct clinical outcomes. We aimed to evaluate the impact of variant allele frequency (VAF) and SF3B1 mutation type across hematopoietic lineages to improve patient stratification. Methods: VAF and the distribution of the p.K700E hotspot compared with other SF3B1 variants were evaluated using paired sequencing data from bone marrow (myeloid) and CD3⁺ (non-myeloid) samples from 23 MN patients with SF3B1 mutations to assess their association with clinical outcomes. Results: Overall, 47.8% of SF3B1 mutations detected in myeloid samples (VAF 42.4%) were also identified in the lymphoid lineage (VAF 17.8%). SF3B1 VAF in CD3⁺ samples correlated with worse prognosis markers. No differences were observed in overall co-mutation burden; however, only myeloid-restricted SF3B1 mutations appeared to represent initiating events. p.K700E mutations (n = 12) were restricted to the myeloid lineage, whereas non-p.K700E mutations (n = 11) were predominantly detected in both myeloid and lymphoid lineages, suggesting multilineage involvement. Conclusions: Distinct mutational patterns and clonal progression mechanisms were observed for different SF3B1 mutation types and depending on the affected hematopoietic lineage. Our findings suggest that the SF3B1 VAF across different lineages may refine patient stratification beyond mutation type alone. Full article

Background/Objectives: Bud sports (somatic mutations) offer a quick way to develop new bougainvillea varieties by altering specific traits while keeping the desirable genetic background of the original cultivar. However, we still lack a comprehensive understanding of their genomic architecture and the molecular mechanisms behind their formation. This study aimed to characterize the population genomic characteristics of bud sports derived from the commercial variety Bougainvillea × buttiana ‘Miss Manila’. Methods: We employed genotyping by sequencing (GBS) on 39 accessions, including 27 bud sports and 12 conventional varieties. Population genomic analyses, such as principal component analysis (PCA), phylogenetic reconstruction, ADMIXTURE, and diversity statistics (π, He, Tajima’s D), were performed on 64,810 high-quality SNPs. Genome-wide scans for differentiation (FST) and selective sweeps (XP-CLR) were also conducted. Results: Bud sports showed significantly lower genetic diversity (π and He) than conventional varieties, which matches their clonal origin. PCA, phylogenetic, and ADMIXTURE analyses (optimal K = 4) revealed clear genetic differentiation and distinct population structures between the two groups. The bud sport population possessed fewer private alleles and a less negative Tajima’s D value. Genomic scans identified regions under selection in bud sports, with functional annotation pointed to genes involved in ubiquitin-mediated proteolysis and RNA transport. Notably, Bou_119143 (UDP-rhamnose rhamnosyltransferase 1) showed a high mutation frequency specifically in bud sports. Conclusions: We provide the first population-genomic evidence that bud sports of ‘Miss Manila’ are genetically distinct clonal lineages, shaped by somatic mutation and selection. These findings support bud sports as efficient sources for germplasm innovation. The identified genomic regions and candidate genes lay a foundation for future marker-assisted selection and molecular breeding in bougainvillea. Full article

Tilia cordata Mill. is a long-lived, ecologically important broadleaved tree species that maintains high genetic diversity despite habitat fragmentation and historical range shifts. In this study, we assessed genetic diversity, clonal structure, and population differentiation in six genetic conservation units (GCUs) in Lithuania using nuclear microsatellite markers. A total of 1109 individuals were successfully genotyped, revealing 979 unique multi-locus genotypes, with 17% of individuals assigned to clonal lineages. Clonal groups were generally small and spatially restricted, indicating localized vegetative regeneration. Genetic diversity was high across all populations, with similar levels of observed and expected heterozygosity, consistent with predominantly outcrossing reproduction. Juvenile cohorts exhibited slightly higher allelic richness and latent genetic potential compared to mature trees, suggesting effective regeneration and maintenance of genetic variation. Genetic differentiation among populations was low but significant (F_ST = 0.013; G″_ST = 0.051), with evidence of clustering corresponding to provenance regions. High gene flow (Nm ≈ 10) likely contributes to weak population structure, although regional differentiation persists. The results demonstrate that Lithuanian T. cordata populations retain a robust genetic framework, combining high within-population diversity with moderate structuring. These findings highlight the importance of conserving multiple GCUs and implementing genetic monitoring to ensure long-term population viability under changing environmental conditions. Full article

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is an emerging cause of invasive disease, yet contemporary genomic data from Canada remain scarce. We investigated 56 cases of invasive SDSE infection identified between 2018 and 2022 in two major tertiary care teaching hospitals in Toronto, Ontario, and characterized 49 corresponding isolates by whole-genome sequencing. Nearly three-quarters of infections were caused by the globally expanding ST20 emm type stG62647 lineage. Patients infected with this lineage were significantly older than those infected with non-ST20 lineages across both bloodstream and non-blood infections. Core-genome phylogenetic analysis revealed a highly clonal ST20 cluster, although two isolates had divergent emm types suggesting recombination at the emm locus. Non-ST20 lineages were numerically smaller and genetically more heterogeneous, including distinct sublineages within ST3 and ST34. All isolates were susceptible to β-lactams and vancomycin. Resistance to tetracycline, erythromycin, and clindamycin was detected in a subset of isolates and was associated with genes tetM, tetO, ermA, ermB, and msrD. Several antimicrobial resistance determinants were located on mobile genetic elements, including integrative and conjugative elements. Our findings provide a contemporary genomic view of invasive SDSE in Toronto, highlighting the dominance of the ST20 stG62647 lineage in agreement with recent global observations. Full article

Background/Objectives: Municipal wastewater treatment plants (WWTPs) act as reservoirs for antibiotic-resistant bacteria, which pose a threat to global public health. In this study, we used whole-genome sequencing (WGS) to characterize antibiotic resistance genes (ARGs) and their association with mobile genetic elements (MGEs) in five multidrug-resistant (MDR) Escherichia coli isolates from dewatered sludge cake samples collected from a municipal WWTP in Cheongju, Republic of Korea. Methods: Susceptibility to nine antibiotics was evaluated via disk diffusion assay. Among the isolates exhibiting multidrug resistance (MDR) to three or more antibiotic classes, five isolates were randomly selected for whole-genome sequencing using the Illumina NovaSeqX platform. Additionally, we compared the genomic structures of five WWTP isolates with 35 environmental E. coli isolates from South Korea deposited in the NCBI pathogen database. ARGs and MGEs, including plasmids, integrons, and insertion sequences (ISs), were detected in the genome assemblies. Results: ARGs were differentially distributed between chromosomal and plasmid-derived contigs. Efflux pump-related genes were predominantly located on the chromosome across all isolates, whereas several beta-lactamase genes (e.g., bla_TEM-30 and bla_TEM-33), fluoroquinolone, and tetracycline resistance genes were localized on putative plasmid contigs. Furthermore, we characterized specific MGEs associated with these ARGs, including a class 1 integron gene cassette (dfrA17–aadA5–qacEΔ1–sul1) and an IS-mediated module (mph(A)–mrx–IS6100). Core-genome multilocus sequence typing (cgMLST) revealed that these MDR isolates represented diverse genetic lineages rather than a single clonal cluster. Conclusions: The results from this study highlight the necessity of enhanced post-treatment management of wastewater byproducts and WGS-based surveillance to mitigate the environmental spread of MDR bacteria. Full article

Circulating tumour DNA (ctDNA) assays are increasingly applied in haematological malignancies for non-invasive genotyping, quantitative response assessment, measurable residual disease (MRD) detection, and relapse surveillance, often complementing bone marrow-based testing and, in selected scenarios, potentially reducing its frequency. Yet, translating ctDNA results into comparable clinical decisions across laboratories, platforms, and time remains challenging because ctDNA measurements are influenced by the definition of the measurand (for example, variant allele fraction versus mutant molecules per mL), pre-analytical variables, end-to-end workflow losses, and lineage-specific confounders such as clonal haematopoiesis of indeterminate potential (CHIP), therapy-related clonal haematopoiesis, and compartmental disease (marrow, plasma, cerebrospinal fluid, extramedullary sites). This review proposes a harmonisation framework for haematological ctDNA based on three linked concepts—metrological traceability, which connects reported values to reference systems with stated uncertainty, commutability, which ensures that reference materials behave like patient specimens across diverse workflows and fit-for-purpose reference materials that support calibration, and quality control, external quality assessment, and cut-off setting for intended uses such as early molecular response in large B-cell lymphoma, molecular MRD in acute myeloid leukaemia, and deep response monitoring in multiple myeloma. This framework is accompanied by harmonised CHIP-aware reporting rules for settings without matched cellular DNA and practical change-control/bridging strategies to preserve clinical decision thresholds when platforms or bioinformatic pipelines evolve. Full article

Metastatic colorectal cancer (mCRC) accounts for 90% of CRC-related mortality. This review synthesizes insights from comparative genomics tracing evolutionary trajectories from primary tumor to disseminated disease. Multi-region sequencing reveals metastatic seeding often occurs early—before clinical detection—challenging linear progression models. The metastatic bottleneck reduces clonal diversity while enriching for dissemination-competent traits including SMAD4 loss, PTEN inactivation and metabolic reprogramming. Organ-specific adaptation yields distinct molecular signatures: liver metastases exhibit Wnt hyperactivation and TGF-β-driven immune suppression; peritoneal tumors display mucinous features; brain metastases show HER2 enrichment. The immune microenvironment evolves toward immunosuppressive configurations, with Microsatellite instability high (MSI-H) tumors acquiring B2M or JAK1/2 mutations. Circulating tumor DNA (ctDNA) enables real-time tracking of clonal dynamics, detecting molecular residual disease months before radiographic progression. Therapeutic resistance follows predictable evolutionary trajectories—from RAS/BRAF mutations to EGFR ectodomain alterations, HER2/MET amplifications and lineage plasticity—with metastasis-specific mechanisms including microenvironmental protection and cellular dormancy. The clinical future lies in interception: leveraging liquid biopsies for early detection, targeting both tumor-intrinsic vulnerabilities and permissive metastatic niches and adapting therapy dynamically to anticipate resistance. Understanding this genomic odyssey is essential for transforming mCRC into a controllable chronic condition. Full article

Background: Acinetobacter baumannii (A. baumannii) is a formidable nosocomial pathogen and is classified by the World Health Organization (WHO) as a critical-priority pathogen, owing to its rapid evolution into extensively drug-resistant (XDR) and pan-drug-resistant (PDR) strains. Colistin remains one of the last-resort therapeutic options, although resistance rates are increasing in endemic regions such as Greece. In this study, we investigated the molecular basis of colistin resistance and characterized the clonal backgrounds of clinical XDR/PDR A. baumannii isolates collected between January and June 2022 from two tertiary-care hospitals in Thessaloniki, Northern Greece. Methods: We analyzed forty non-duplicate XDR/PDR clinical isolates. Antimicrobial susceptibility was determined using the VITEK 2 system, broth microdilution, and gradient diffusion methods. The lipid A biosynthesis genes (lpxA, lpxC, lpxD) and the pmrCAB operon were amplified by PCR and sequenced for all isolates. A representative subset of strains (n = 10/40) underwent multilocus sequence typing (MLST) according to the Pasteur MLST scheme. Results: All isolates proved colistin-resistant (MIC ≥ 4 µg/mL), and 95% were classified as PDR. Sequence analysis revealed multiple nonsynonymous mutations in the pmrCAB operon, with the PmrB A226V substitution predominating and extensive amino-acid changes observed in PmrC. In contrast, lpx genes exhibited limited protein-level variation, limited to lineage-associated polymorphisms (LpxC N287D, LpxD E117K). A novel six-nucleotide insertion in pmrB was identified in one isolate. MLST demonstrated a predominance of ST2 (International Clone 2), with single representatives of ST115 (IC2) and ST1 (IC1). Conclusions: In this cohort from Northern Greece, chromosomal mutations in the pmrCAB operon, within a predominantly ST2/IC2 background, were strongly associated with colistin resistance. These findings underscore the urgent need for continued molecular surveillance and targeted infection-control measures to limit further spread of PDR A. baumannii. Full article

Carbapenems are essential for the treatment of severe infections caused by Gram-negative bacteria, particularly in critically ill and immunocompromised patients. However, the global rise of carbapenem-resistant Enterobacterales (CRE), Pseudomonas aeruginosa, and Acinetobacter baumannii has significantly eroded their effectiveness, and the phenomenon is now recognized as a major public health threat. Resistance is driven by the complex and evolving interplay of enzymatic and non-enzymatic mechanisms, occurring within highly successful clonal lineages and mobile genetic platforms. This review summarizes advances since 2020 in the molecular basis of carbapenem resistance, integrating enzymatic mechanisms across Ambler classes A, B, C, and D with emerging non-enzymatic contributors, including porin remodeling, efflux pump upregulation, target-site alterations, and outer-membrane adaptations. Particular attention is given to adaptive genome dynamics, such as IS26-mediated gene amplification, plasmid multimerization, and heteroresistance, that generate unstable resistance phenotypes and complicate routine susceptibility testing. Newly introduced β-lactam/β-lactamase inhibitor combinations exert distinct selective pressures: ceftazidime–avibactam favors KPC Ω-loop variants and permeability defects, often restoring carbapenem susceptibility, whereas meropenem–vaborbactam and imipenem–relebactam resistance is driven mainly by porin loss and β-lactamase gene amplification. Cefiderocol resistance is multifactorial, frequently involving impaired siderophore uptake and heteroresistance, while sulbactam–durlobactam remains active against OXA-producing A. baumannii but is compromised by metallo-β-lactamases and PBP3 alterations. Carbapenem resistance is increasingly characterized by convergent, multi-layered adaptations that undermine both established and novel therapies. While high-level randomized evidence remains limited for some resistance mechanisms, emerging mechanistic, microbiological, and clinical data support the need for mechanism-aware diagnostics, repeated susceptibility assessment during therapy, and stewardship strategies informed by resistance biology. Integrating molecular context into routine practice will be critical to preserving emerging treatment options and limiting the global impact of carbapenem resistance. Full article