Biology subjects

Blank, F.

Publications and source records attributed to Blank, F..

4 recordsLinked to original sources

bioRxiv2025

Microbial Priming Enhances TLR7-Driven Myddosome Assembly Dynamics

Cells can modify their future behavior based on prior exposures, a phenomenon known as cellular adaptation. In innate immunity, such adaptive responses are critical for fine-tuning host defense, enabling trained immunity or tolerance. These states have been largely attributed to long-lasting epigenetic or metabolic reprogramming. Whether prior microbial encounters can rapidly lower receptor signaling thresholds to selectively enhance responsiveness of individual innate immune receptors remains unknown. Here, we identify a previously unrecognized, non-genetic form of cellular adaptation. We show that TLR4 activation by LPS, while inducing classical endotoxin tolerance, simultaneously primes macrophages for enhanced responses to subsequent activation of the RNA sensor TLR7. Because TLR4 and TLR7 use the same signaling machinery, this indicates that they are selectively reprogrammed in this process. TLR7 training requires type I interferons and is marked by a strong increase in Myddosome assemblies at endosomal membranes, without changes in TLR7 abundance or ligand uptake. These findings reveal that innate immune training can be rapidly encoded at the level of receptor-proximal signaling, linking microbial priming to enhanced nucleic acid immunity and potentially to TLR7-driven autoimmunity in genetically predisposed individuals. Short summaryLPS priming drives receptor-proximal immune adaptation in macrophages, inducing classical TLR4 endotoxin tolerance while simultaneously sensitizing the RNA sensor TLR7 by enhancing Myddosome nucleation at endosomal membranes. This compartment- and receptor specific reprogramming may link prior infection history to elevated risk of TLR7-driven autoimmunity.

cell biology↗

bioRxiv2025

Bemnifosbuvir and remdesivir inhibit tick-borne encephalitis virus infection in complementary in vitro and ex vivo disease models

The geographical distribution and incidence of tick-borne encephalitis (TBE) have steeply increased over the past decades, raising to represent a major health concern in Asia and Europe. Symptoms of TBE, caused by infections with tick-borne encephalitis virus (TBEV), range from mild, flu-like symptoms to severe neurological disease, often accompanied by long-term sequelae persisting for several years following pathogen encounter. While effective vaccines against TBEV are available, no antiviral drugs are currently approved and therapeutic options for patients suffering from TBE are limited to supportive measures. Compounds able to disrupt viral nucleic acid synthesis bear the potential of effectively limiting viral replication and spread. Seeking to fill the therapeutic gap, we evaluated the efficacy of a panel of approved and investigational antiviral compounds in containing TBEV infection. Combining several cell lines, human neural organoids and organotypic rat brain slice cultures, we found that the nucleoside analogs remdesivir and bemnifosbuvir efficiently limit viral replication. Through infectious virus quantification, immunofluorescence analysis and flow cytometry, we report significant, dose-dependent reduction of viral loads across all models used, with inhibition observed at low doses for both drugs. Notably, while we observed bemnifosbuvir to be well tolerated, we report important cytotoxicity of remdesivir when applied to human neural organoids. Our findings identify bemnifosbuvir and remdesivir as novel treatment strategies for TBE, providing an accessible and timely response to a clinical challenge of pressing concern.

microbiology↗

bioRxiv2023

Mpox virus spreads from cell-to-cell and leads to neuronal injury in human cerebral organoids

In 2022-23, the world experienced the largest recorded monkeypox virus (MPXV) outbreak outside of endemic regions. Remarkably, cases of neurological manifestations were reported, some of which fatal. MPXV DNA and MPXV-specific antibodies were detected in the cerebrospinal fluid of encephalitis-affected patients, suggesting neuroinvasive potential of MPXV. We explored the susceptibility of neural tissue to MPXV infection using human neural organoids (hNOs) exposed to a primary isolate belonging to clade IIb lineage. The virus efficiently replicates in hNOs as indicated by the exponential increase of infectious viral loads and the elevated frequency of MPXV-positive cells over time. Electron microscopy imaging revealed the presence of viral particles as well as perinuclear viral factories. We observed susceptibility of several cell types to the virus, including neural progenitor cells and neurons. Furthermore, we detected the presence of viral antigen in neurites and in foci of grouped cells distributed throughout the tissue. In line with this, we documented significantly more cell-associated than released infectious virus, suggesting viral spread by cell-to-cell contact. Using an mNeonGreen-expressing recombinant MPXV, we confirmed cell-associated virus transmission through live-cell imaging. While hNOs displayed no evident outer morphological changes upon infection, we detected the formation of beads in neurites, a phenomenon commonly associated with neurodegenerative disorders. Live-cell imaging further confirmed the recurrent formation of neuritic beads in neurons in the days following MPXV infection, with bead formation preceding neurite-initiated cell death. Notably, treatment of MPXV infected hNOs with the antiviral drug tecovirimat resulted in a significant reduction of infectious viral loads by several orders of magnitude. Taken together, our findings suggest viral manipulation of axonal transport driving neuronal degeneration and identify a mechanism potentially contributing to MPXV-mediated neuropathology that may have therapeutic implications.

microbiology↗

bioRxiv2023

An optogenetic method for the controlled release of single molecules

We developed a system for optogenetic release of single molecules in live cells. We confined soluble and transmembrane proteins to the Golgi apparatus via a photocleavable protein and released them by short pulses of light. Our method allows for the controlled delivery of functional proteins to cytosol and plasma membrane in amounts compatible with single molecule imaging, greatly simplifying access to single molecule microscopy of any protein in live cells. Furthermore, we could reconstitute cellular functions such as ion conductance by delivering BK and VRAC ion channels to the plasma membrane. Finally, we could induce NF-kB signaling in T-Lymphoblasts stimulated by IL-1 by controlled release of a signaling protein that had been knocked-out in the same cells. We observed light induced formation of functional inflammatory signaling complexes that could trigger IKK phosphorylation in single cells. We thus developed an optogenetic method for the reconstitution and investigation of cellular function at the single molecule level.

biophysics↗