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"Ludwig, L."
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Mitochondrial localization of TIGAR under hypoxia stimulates HK2 and lowers ROS and cell death
The p53-inducible protein TIGAR (Tp53-induced Glycolysis and Apoptosis Regulator) functions as a fructose-2,6-bisphosphatase (Fru-2,6-BPase), and through promotion of the pentose phosphate pathway, increases NADPH production to help limit reactive oxygen species (ROS). Here, we show that under hypoxia, a fraction of TIGAR protein relocalized to mitochondria and formed a complex with hexokinase 2 (HK2), resulting in an increase in HK2 activity. Mitochondrial localization of TIGAR depended on mitochondrial HK2 and hypoxia-inducible factor 1 (HIF1α) activity. The ability of TIGAR to function as a Fru-2,6-BPase was independent of HK2 binding and mitochondrial localization, although both of these activities can contribute to the full activity of TIGAR in limiting mitochondrial ROS levels and protecting from cell death.
Journal Article
The survival of the city : living and thriving in an age of isolation
\"In Survival of the City, an urbanist and a public health expert join forces to explain where cities are right now and provide a prescription for a healthy future for them\"-- Provided by publisher.
Book
Astrocyte 3D culture and bioprinting using peptide functionalized hyaluronan hydrogels
Astrocytes play an important role in the central nervous system, contributing to the development of and maintenance of synapses, recycling of neurotransmitters, and the integrity and function of the blood-brain barrier. Astrocytes are also linked to the pathophysiology of various neurodegenerative diseases. Astrocyte function and organization are tightly regulated by interactions mediated by the extracellular matrix (ECM). Engineered hydrogels can mimic key aspects of the ECM and can allow for systematic studies of ECM-related factors that govern astrocyte behaviour. In this study, we explore the interactions between neuroblastoma (SH-SY5Y) and glioblastoma (U87) cell lines and human fetal primary astrocytes (FPA) with a modular hyaluronan-based hydrogel system. Morphological analysis reveals that FPA have a higher degree of interactions with the hyaluronan-based gels compared to the cell lines. This interaction is enhanced by conjugation of cell-adhesion peptides (cRGD and IKVAV) to the hyaluronan backbone. These effects are retained and pronounced in 3D bioprinted structures. Bioprinted FPA using cRGD functionalized hyaluronan show extensive and defined protrusions and multiple connections between neighboring cells. Possibilities to tailor and optimize astrocyte-compatible ECM-mimicking hydrogels that can be processed by means of additive biofabrication can facilitate the development of advanced tissue and disease models of the central nervous system.
Journal Article
Insulin receptor functionally enhances multistage tumor progression and conveys intrinsic resistance to IGF-1R targeted therapy
The type 1 insulin-like growth factor receptor (IGF-1R) tyrosine kinase is an important mediator of the protumorigenic effects of IGF-I/II, and inhibitors of IGF-1R signaling are currently being tested in clinical cancer trials aiming to assess the utility of this receptor as a therapeutic target. Despite mounting evidence that the highly homologous insulin receptor (IR) can also convey protumorigenic signals, its direct role in cancer progression has not been genetically defined in vivo, and it remains unclear whether such a role for IR signaling could compromise the efficacy of selective IGF-1R targeting strategies. A transgenic mouse model of pancreatic neuroendocrine carcinogenesis engages the IGF signaling pathway, as revealed by its dependence on IGF-II and by accelerated malignant progression upon IGF-1R overexpression. Surprisingly, preclinical trials with an inhibitory monoclonal antibody to IGF-1R did not significantly impact tumor growth, prompting us to investigate the involvement of IR. The levels of IR were found to be significantly up-regulated during multistep progression from hyperplastic lesions to islet tumors. Its functional involvement was revealed by genetic disruption of the IR gene in the oncogene-expressing pancreatic β cells, which resulted in reduced tumor burden accompanied by increased apoptosis. Notably, the IR knockout tumors now exhibited sensitivity to anti-IGF-1R therapy; similarly, high IR to IGF-1R ratios demonstrably conveyed resistance to IGF-1R inhibition in human breast cancer cells. The results predict that elevated IR signaling before and after treatment will respectively manifest intrinsic and adaptive resistance to anti-IGF-1R therapies.
Journal Article
Performance verification of the Abbott SARS-CoV-2 test for qualitative detection of IgG in Cali, Colombia
Adequate testing is critically important for control of the SARS-CoV-2 pandemic. Antibody testing is an option for case management and epidemiologic studies, with high specificity and variable sensitivity. However, characteristics of local populations may affect performance of these tests. For this reason, the National Institute of Health (INS) and regulatory agencies in Colombia require verification of diagnostic accuracy of tests introduced to the Colombian market.
We conducted a validation study of the Abbott SARS-CoV-2 test for qualitative detection of IgG using the Abbott Architect i2000SR. Participants and retrospective samples were included from patients with suspected SARS-CoV-2 infection, age ≥18 years, and ≥8 days elapsed since initiation of symptoms. Pre-pandemic plasma samples (taken before October 2019) were used as controls. We estimated the sensitivity, specificity and agreement (kappa) of the Abbott IgG test compared to the gold standard (RT-PCR).
The overall sensitivity was 83.1% (95% CI: 75.4-100). Sensitivity among patients with ≥14 days since the start of symptoms was 85.7%, reaching 88% in samples collected from patients with COVID-19 symptoms onset >60 days. Specificity was 100% and the kappa index of agreement was 0.804 (95% CI: 0.642-0.965).
Our findings show high sensitivity and specificity of the Abbott IgG test in a Colombian population, which meet the criteria set by the Colombian INS to aid in the diagnosis of COVID-19. Data from our patient groups also suggest that IgG response is detectable in a high proportion of individuals (88.1%) during the first two months following onset of symptoms.
Journal Article
Harnessing exDNA for precision exatecan delivery in cancer: a novel antibody-drug conjugate approach
Background
Current antibody-drug conjugates (ADCs) face limitations due to a lack of tumor-selective targets, inefficient internalization, and challenges in reaching tumors in challenging sites, ultimately limiting their therapeutic efficacy. We developed and characterized V66-exatecan, a novel ADC composed of V66, a humanized antibody with high affinity for extracellular DNA (exDNA), conjugated to exatecan via a cleavable linker. This ADC employs a dual-targeting mechanism based on exDNA and ENT2 transporter expression to enhance nuclear drug delivery and tumor specificity. This study evaluates its anti-tumor activity, mechanism of action, ability to treat challenging tumors, and safety profile.
Methods
To validate tumor selectivity, V66 or a control antibody were conjugated to a fluorescent tag and injected intravenously into tumor-bearing mice; biodistribution analysis demonstrated selective accumulation in tumors and nuclear localization within tumor cells. V66 was then conjugated to exatecan via a cleavable linker. In vitro assays across diverse cancer cell lines assessed cytotoxicity, DNA damage response (DDR) activation, and TOP1 degradation. In vivo efficacy was evaluated in xenograft models of triple-negative breast cancer (TNBC) and BRCA1/2-deficient tumors, including intracranial medulloblastoma. These models were used to assess tumor growth inhibition, survival benefit, and blood-brain barrier (BBB) permeability. Toxicity was assessed through a dose-escalation study, with analysis of hematologic parameters, histopathology of major organs, and liver and kidney function tests (ALT, AST, BUN, total protein) following short- and long-term treatment.
Results
V66-exatecan demonstrated potent anti-tumor activity in multiple cancer cell lines but not on healthy mouse primary fibroblasts, with EC
50
values in the low nanomolar range. It induced robust DDR signaling, TOP1 degradation, and bystander killing effects. BRCA1/2-deficient models exhibited enhanced penetration and sensitivity, with up to 17-fold lower EC
50
compared to BRCA-proficient controls. In vivo, V66-exatecan significantly inhibited tumor growth and extended survival in both TNBC and BRCA-mutant CNS tumors, including complete regressions and prolonged median survival in BRCA2-deficient models. Toxicology studies revealed no significant hematologic, renal, hepatic, or bone marrow toxicity, even at high or repeated doses.
Conclusions
V66-exatecan represents a next-generation of ADCs that overcomes key limitations of traditional platforms by exploiting exDNA-driven tumor selectivity and ENT2-mediated nuclear delivery. It demonstrates broad therapeutic efficacy and a favorable safety profile, supporting its potential for treating DDR-deficient and hard-to-reach tumors.
Journal Article
Broadly neutralizing human antibodies against dengue virus identified by single B cell transcriptomics
Eliciting broadly neutralizing antibodies (bNAbs) against the four dengue virus serotypes (DENV1-4) that are spreading into new territories is an important goal of vaccine design. To define bNAb targets, we characterized 28 antibodies belonging to expanded and hypermutated clonal families identified by transcriptomic analysis of single plasmablasts from DENV-infected individuals. Among these, we identified J9 and J8, two somatically related bNAbs that potently neutralized DENV1-4. Mutagenesis studies showed that the major recognition determinants of these bNAbs are in E protein domain I, distinct from the only known class of human bNAbs against DENV with a well-defined epitope. B cell repertoire analysis from acute-phase peripheral blood suggested that J9 and J8 followed divergent somatic hypermutation pathways, and that a limited number of mutations was sufficient for neutralizing activity. Our study suggests multiple B cell evolutionary pathways leading to DENV bNAbs targeting a new epitope that can be exploited for vaccine design.
Journal Article
Diversity of fungi obtained from bats captured in urban forest fragments in Sinop, Mato Grosso, Brazil
Abstract Bats are important for the homeostasis of ecosystems and serve as hosts of various microorganisms including bacteria, viruses, and fungi with pathogenic potential. This study aimed to isolate fungi from biological samples obtained from bats captured in the city of Sinop (state of Mato Grosso, Brazil), where large areas of deforestation exist due to urbanization and agriculture. On the basis of the flow of people and domestic animals, 48 bats were captured in eleven urban forest fragments. The samples were processed and submitted to microbiological cultures, to isolate and to identify the fungal genera. Thirty-four (70.83%) of the captured bats were positive for fungi; 18 (37.5%) and 16 (33.33%) of these bats were female and male, respectively. Penicillium sp., Scopulariopsis sp., Fusarium sp., Aspergillus sp., Alternaria sp., Cryptococcus sp., Trichosporon sp., and Candida sp., which may cause opportunistic infections, were isolated. The bat species with the highest number of fungal isolates was Molossus molossus: 21 isolates (43.8%). According to our results, bats captured in urban forest fragments in Sinop harbor pathogenic fungi, increasing the risk of opportunistic fungal infections in humans and domestic animals. Resumo Os morcegos apresentam grande importância na homeostasia dos ecossistemas e são hospedeiros de uma rica diversidade de micro-organismos como bactérias, vírus e fungos com potencial patogênico. Portanto, este estudo visou isolar fungos presentes em amostras biológicas de morcegos na cidade de Sinop - MT, que possui grandes áreas de desmatamento devido à urbanização e agricultura. Foram capturados 48 morcegos de diferentes espécies, em onze fragmentos florestais urbanos definidos de acordo com fluxo de pessoas e animais domésticos, para obtenção de amostras biológicas. Essas amostras foram processadas e submetidas aos cultivos microbiológicos, para isolamento e identificação dos gêneros dos fungos. Dos 48 morcegos, 34 (70,83%) foram positivos para pelos menos um gênero de fungo, sendo 18 (37,5%) fêmeas e 16 (33,33%) machos, e os gêneros isolados a partir das amostras biológicas foram Penicillium sp., Scopulariopsis sp., Fusarium sp., Aspergillus sp., Alternaria sp., Cryptococcus sp., Trichosporon sp. e Candida sp., que podem ser causadores de infecções oportunistas. Desse total, a espécie que apresentou maior positividade para pelo menos um gênero de fungo foi Molossus molossus com 21 (43,8%). Nossos resultados demonstram que os morcegos capturados nos fragmentos florestais urbanos na cidade de Sinop - MT, podem atuar como agentes veiculadores de fungos com potencial patogênico, aumentando assim o risco de exposição e aquisição de infecções fúngicas oportunistas por pessoas e animais domésticos.
Journal Article