Biology subjects

Frank, B.

Publications and source records attributed to Frank, B..

10 recordsLinked to original sources

bioRxiv2026

Histone neutralization protects the ischemic brain against stroke-associated pneumonia

Bacterial pneumonia aggravates ischemic stroke via mechanisms that still remain to be determined. In ischemic stroke patients and mice exposed to middle cerebral artery occlusion, we show that stroke-associated pneumonia markedly worsens clinical stroke outcome. In mice, pneumonia induced 3 days after stroke impaired neurological recovery and increased brain neutrophil infiltrates, blood-brain barrier breakdown, cerebral microvascular thrombosis, and progressive brain atrophy. The antibiotic amoxicillin only partially ameliorated pneumonia-associated neurological deficits and neutrophil infiltrates. Neutrophils were critical mediators of pneumonia-induced blood-brain barrier breakdown and microvascular thrombosis. Notably, administration of a neutralizing anti-histone antibody during pneumonia--unlike degradation or blockade of neutrophil extracellular trap formation or myeloperoxidase inhibition--restored long-term neurological recovery and prevented brain atrophy in stroke-associated pneumonia mice. This study identifies extracellular histones as key drivers of secondary inflammatory brain injury and establishes histone neutralization as a therapeutic strategy with an extended treatment window in the post-acute stroke phase. One Sentence SummaryNeutralizing extracellular histones reverses pneumonia-driven secondary brain injury and restores long-term recovery after ischemic stroke.

neuroscience↗

bioRxiv2025

White matter reorganization of motor and affective-motivational networks in pain-indifferent carriers of the R221W mutation

Congenital insensitivity to pain (CIP) due to the R221W mutation on the nerve growth factor gene results in reduced peripheral C-nociceptor density and behavioural indifference to painful stimuli. While functional neuroimaging has revealed altered cortical and sub-cortical pain processing in R221W carriers, structural white matter changes remain unexplored and may suggest an anatomical basis of symptoms. Heterozygous R221W carriers (n = 11) and age-, sex-, education-matched controls (n = 11) diffusion tensor imaging data were compared using fixel-based analysis, and complimentary edge and node analyses using graph theory, and network-based statistics. Whole-brain and region of interest (ROI) fixel-based analyses revealed significantly reduced fibre density and fibre-bundle cross-section in brainstem motor tracts of R221W carriers, encompassing the corticospinal pathways, corona radiata, external capsule, cerebellar peduncles, and pontine crossing (p < 0.05). Graph theory analysis of pain-processing ROIs demonstrated reduced local efficiency in right anterior cingulate cortex (ACC) and altered betweenness centrality in bilateral insula and left ACC of R221W carriers. Despite R221W carriers showing higher node degrees in the somatosensory cortex and ACC, these connections had reduced efficiency and integration with cortical network regions. Network-based statistics identified a possible compensatory subnetwork with stronger connectivity from right thalamus to left ACC and left insula in R221W carriers (p < 0.019). These findings suggest that congenitally reduced peripheral nociception could lead to abnormalities in the thalamocortical and motor efferent pathway, but not sensory afferent pathways. The combination of reduced brainstem motor tract integrity and altered cortical network efficiency, alongside potentially compensatory thalamo-cortical connectivity, could support a model of R221W CIP as motor under-reactivity rather than sensory insensitivity.

neuroscience↗

bioRxiv2024

Vimentin molecular linkages with nesprin-3 enhance nuclear deformation by cell geometric constraints

The nucleus is the organelle of the cell responsible for controlling protein expression, which has a direct effect on cellular biological functions. Here we show that the cytoskeletal protein vimentin plays an important role in increasing cell-generated forces transmitted to the cell nucleus, resulting in increased nuclear deformations in strongly polarized cells. Using micropatterned substrates to geometrically control cell shape in wild-type and vimentin-null cells, we show vimentin increases polarization and deformation of the cell nucleus. Loss of nesprin-3, which physically couples vimentin to the nuclear envelope, phenotypically copies the loss of vimentin, suggesting vimentin transmits forces to the cell nucleus through direct molecular linkages. Use of a fluorescence resonance energy transfer (FRET) sensor that binds to the nuclear envelope through lamin-A/C suggests vimentin increases the tension on the nuclear envelope. Our results indicate that nuclear shape and deformation can be modified by the vimentin cytoskeleton and its specific crosslinks to the cell nucleus.

biophysics↗

bioRxiv2024

Slit3 Fragments Orchestrate Neurovascular Expansion and Thermogenesis in Brown Adipose Tissue

Brown adipose tissue (BAT) is an evolutionary innovation that enables placental mammals to regulate body temperature through adaptive thermogenesis. Brown adipocytes are embedded within an intricate network of blood vessels and sympathetic nerves that support their development and thermogenic function. Cold exposure activates BAT thermogenesis through the coordinated induction of brown adipogenesis, angiogenesis, and sympathetic innervation. However, how these distinct processes are coordinated remains unclear. Here, we show that fragments of Slit guidance ligand 3 (Slit3) drive crosstalk among adipocyte progenitors, endothelial cells, and sympathetic nerves. We demonstrate that adipocyte progenitors secrete Slit3, which regulates both angiogenesis and sympathetic innervation in BAT and is essential for BAT thermogenesis in vivo. Proteolytic cleavage of Slit3 generates secreted Slit3-N and Slit3-C fragments, which bind distinct receptors to stimulate angiogenesis and sympathetic innervation, respectively. We identify Plxna1 as a previously unrecognized receptor for Slit3-C and show that it is essential for sympathetic innervation and cold-induced neurite expansion in BAT. Moreover, we introduce bone morphogenetic protein 1 (Bmp1) as the first Slit protease identified in vertebrates. In summary, this work establishes a mechanistic framework for the coordinated regulation of sympathetic innervation and angiogenesis to enhance thermogenic function. The co-regulation of neurovascular expansion by distinct Slit3 fragments offers a bifurcated yet harmonized mechanism to ensure a synchronized BAT response to environmental challenges. Finally, this study provides the first evidence that adipocyte progenitors regulate tissue innervation, revealing a previously unrecognized dimension of cellular interaction within adipose tissue.

physiology↗

bioRxiv2022

Peyers Patch B cells undergo cell death via neutrophil-released toxic DNA following sterile tissue injury

Lymphocyte contraction (LC) in central immune organs is a concomitant of sterile tissue injury, for example after stroke. Intestinal Peyers patches (PP) harbor large numbers of B cells, but how sterile tissue injury leads to LC in PP has not been explored. We observed rapid and macroscopically evident shrinkage of PP after stroke and myocardial infarction. Light-sheet fluorescence microscopy and flow cytometry revealed a strong reduction in the number of PP-resident B cells. Mechanistically, tissue injury triggered the activation of neutrophils that released B cell-toxic neutrophil extracellular traps (NETs) decorated with citrullinated histone-H3. Antibody-mediated or genetically induced neutrophil-loss, NETs-degradation or blockade of their generation completely reversed B cell loss and preserved the tissue architecture of PP. We also found NET-like elements in human post-stroke plasma. Hence, we propose that targeting NET-generation or -function counteracts post-injury B cell contraction in PP and thereby maintains immune homeostasis at mucosal barriers. In briefHigh numbers of B cells reside in the intestinal Peyers patches. Tuz et al. revealed that in response to sterile tissue injury, activated neutrophils release histone-decorated DNA into the circulation which induces B cell death. The loss of B cells results in the shrinkage of Peyers patches and reduced amounts of secretory IgA. HighlightsO_LIStroke and myocardial infarction induce the melting of Peyers patch C_LIO_LILight-sheet microscopy and cytometry revealed B cell loss in Peyers patch C_LIO_LIPost-injury activated neutrophils release NETs and trigger B cell death C_LIO_LIInhibition of NETs rescues B cell loss and degeneration of Peyers patch C_LI

immunology↗

bioRxiv2022

Topologically engineered antibodies and Fc-fusion proteins: a new class of multifunctional therapeutic candidates for SARS-CoV-2, cancer, and other disease

Traditional Y-shaped IgG topologies restrict conventional multispecific antibodies by imposing steric constraints that hinder target binding and stability. To overcome this, we engineered tetrahedral antibodies, a multispecific class that non-covalently self-assembles via two hinge-integrated collectrin-like domains (CLDs). This non-planar, tetrapartite architecture coordinates up to six unobstructed Fab, Fc, and extracellular domains. Parallel to the clinical translation of our dual-Fc anti-CD19/CD20 tetrahedral antibody for systemic lupus erythematosus (SLE), we evaluated an anti-SARS-CoV-2 candidate that exhibited in vivo efficacy in non-human primates. Furthermore, we demonstrate functional Fc{gamma}R binding cooperativity across the dual-Fc domains of anti-CD19/CD20 tetrahedral antibodies, while introducing an interface disulfide bond into the CLD dimer increases structural stability as evidenced by effectively abolishing CLD dynamic dissociation and resolving the dissociation equilibrium into discrete, stable quaternary states. These findings establish tetrahedral architectures as a robust, translatable multispecific platform.

molecular biology↗

bioRxiv2021

Mouse Antibodies with Activity Against the SARS-CoV-2 D614G and B.1.351 Variants

With the rapid spread of SARS-CoV-2 variants, including those that are resistant to antibodies authorized for emergency use, it is apparent that new antibodies may be needed to effectively protect patients against more severe disease. Differences between the murine and human antibody repertoires may allow for the isolation of murine monoclonal antibodies that recognize a different or broader range of SARS-CoV-2 variants than the human antibodies that have been characterized so far. We describe mouse antibodies B13 and O24 that demonstrate neutralizing potency against SARS-CoV-2 Wuhan (D614G) and B.1.351 variants. Such murine antibodies may have advantages in protecting against severe symptoms when individuals are exposed to new SARS-CoV-2 variants.

molecular biology↗

bioRxiv2021

Rigidifying a de novo enzyme increases activity and induces a negative activation heat capacity

Conformational sampling profoundly impacts the overall activity and temperature dependence of enzymes. Peroxidases have emerged as versatile platforms for high value biocatalysis owing to their broad palette of potential biotransformations. Here, we explore the role of conformational sampling in mediating a de novo peroxidases activity. We demonstrate that 2,2,2-triflouoroethanol (TFE) affects the equilibrium of enzyme conformational states, tending towards a more globally rigid structure. This is correlated with increases both stability and activity. Notably, these effects are concomitant with the emergence of curvature in the temperature-activity profile, trading off activity gains at ambient temperature with losses at high temperatures. We apply macromolecular rate theory (MMRT) to understand enzyme temperature dependence data. These data point to an increase in protein rigidity associated with a difference in the distribution of protein dynamics between the ground and transition state. We compare the thermodynamics of the de novo enzyme activity to those of a natural peroxidase, horseradish peroxidase. We find that the native enzyme resembles the rigidified de novo enzyme in terms of the thermodynamics of enzyme catalysis and the putative distribution of protein dynamics between the ground and transition state. The addition of TFE apparently causes C45 to behave more like the natural enzyme. Our data suggest robust, generic strategies for improving biocatalytic activity by manipulating protein rigidity; for functional de novo protein catalysts in particular, this can provide more enzyme-like catalysts without further rational engineering, computational redesign or directed evolution.

biochemistry↗

bioRxiv2020

Antiviral activity of plant juices and green tea against SARS-CoV-2 and influenza virus in vitro

Many plant juices, extracts and teas have been shown to possess antiviral activity. We here analyzed the virucidal activity of black chokeberry (Aronia melanocarpa), pomegranate (Punica granatum), and elderberry (Sambucus nigra) juice, as well as green tea (Camellia sinensis) against different respiratory viruses. We found that all tested plant derived products effectively inactivated influenza virus, whereas only chokeberry juice diminished SARS-CoV-2 and vaccinia virus infectivity. None of the products inactivated non-enveloped human adenovirus type 5. Thus, black chokeberry juice exerts virucidal activity against different enveloped viral pathogens under in vitro conditions. Whether application of virucidal juices or green tea as oral rinses may lower viral loads in the oral cavity in vivo remains to be evaluated.

microbiology↗

bioRxiv2017

Functional Genes That Distinguish Maize Phyllosphere Metagenomes in Drought and Well-Watered Conditions

The phyllosphere epiphytic microbiome is composed of microorganisms that colonize the external aerial portions of plants. Relationships of plant responses to specific microorganisms-both pathogenic and beneficial-have been examined, but the phyllosphere microbiome functional and metabolic profile responses are not well described. Changing crop growth conditions, such as increased drought, can have profound impacts on crop productivity. Also, epiphytic microbial communities provide a new target for crop yield optimization. We compared Zea mays leaf microbiomes collected under drought and well-watered conditions by examining functional gene annotation patterns across three physically disparate locations each with and without drought treatment, through the application of short read metagenomic sequencing. Drought samples exhibited different functional sequence compositions at each of the three field sites. Maize phyllosphere functional profiles revealed a wide variety of metabolic and regulatory processes that differed in drought and normal water conditions and provide key baseline information for future selective breeding.

microbiology↗