Florian Ingo Schmidt

Florian Ingo Schmidt
University of Bonn | Uni Bonn · Institute of Innate Immunity

PhD

About

55
Publications
9,517
Reads
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1,830
Citations
Introduction
I am interested in infection biology, cell biology, and immunology. My recently established research group at the University of Bonn focusses on the underlying cell biology of antiviral responses of the innate immune system. To do so, we investigate the mechanistic details of inflammasome activation using custom-generated alpaca single-domain antibodies (VHHs). A comprehensive panel of VHHs will be used to perturb and visualize components of innate immune signaling and effector cascades.
Additional affiliations
February 2017 - present
University of Bonn
Position
  • Emmy Noether group leader
November 2016 - January 2017
Boston Children's Hospital
Position
  • PostDoc Position
August 2013 - November 2017
Whitehead Institute for Biomedical Research
Position
  • PostDoc Position
Education
September 2007 - October 2011
ETH Zurich
Field of study
  • Virology
October 2005 - September 2007
Technische Universität München
Field of study
  • Biochemistry
October 2002 - September 2005
Technische Universität München
Field of study
  • Biochemistry

Publications

Publications (55)
Article
Full-text available
Inflammasomes sense intracellular clues of infection, damage, or metabolic imbalances. Activated inflammasome sensors polymerize the adaptor ASC into micron-sized "specks" to maximize caspase-1 activation and the maturation of IL-1 cytokines. Caspase-1 also drives pyroptosis, a lytic cell death characterized by leakage of intracellular content to t...
Article
Full-text available
Purpose NLRC4-associated autoinflammatory disease (NLRC4-AID) is an autosomal dominant condition presenting with a range of clinical manifestations which can include macrophage activation syndrome (MAS) and severe enterocolitis. We now report the first homozygous mutation in NLRC4 (c.478G > A, p.A160T) causing autoinflammatory disease with immune d...
Preprint
Inflammasomes integrate cytosolic evidence of infection or damage to mount inflammatory responses. The inflammasome sensor NLRP1 is expressed in human keratinocytes and coordinates inflammation in the skin. We found that diverse stress signals converge on the activation of p38 kinases to initiate human NLRP1 inflammasome assembly: UV irradiation an...
Article
Longitudinal analyses of the innate immune system including earliest time points are essential to understand the immunopathogenesis and clinical course of COVID-19. Here, we performed a detailed characterization of natural killer cells in 205 patients (403 samples, day 2-41 after symptom onset) from four independent cohorts using single-cell transc...
Preprint
Full-text available
Pyrin is a cytosolic immune sensor that forms an inflammasome when bacterial virulence factors inhibit RhoA, triggering the release of inflammatory cytokines, including IL-1β. Gain of function mutations in the MEFV gene encoding Pyrin cause auto-inflammatory disorders, such as familial Mediterranean fever (FMF) and Pyrin associated auto-inflammatio...
Article
Full-text available
COVID-19 outbreak is the biggest threat to human health in recent history. Currently, there are over 1.5 million related deaths and 75 million people infected around the world (as of 22/12/2020). The identification of virulence factors which determine disease susceptibility and severity in different cell types remains an essential challenge. The se...
Article
Full-text available
SARS-CoV-2 evades most innate immune responses, but may still be vulnerable to some. Here, we systematically analyzed the impact of SARS-CoV-2 proteins on interferon (IFN) responses and autophagy. We show that SARS-CoV-2 proteins synergize to counteract antiviral immune responses. For example, Nsp14 targets the type I IFN receptor for lysosomal deg...
Article
Full-text available
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic continues to spread with devastating consequences. For passive immunization efforts, nanobodies have size and cost advantages over conventional antibodies. Here, we generated four neutralizing nanobodies that target the receptor-binding domain of the SARS-CoV-2 spike protein....
Article
Full-text available
Inflammasomes are supramolecular complexes that play key roles in immune surveillance. This is accomplished by the activation of inflammatory caspases, which leads to the proteolytic maturation of interleukin 1β (IL-1β) and pyroptosis. Here, we show that nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3)-...
Article
Full-text available
Members of the family of pyrin and HIN domain containing (PYHIN) proteins play an emerging role in innate immunity. While absent in melanoma 2 (AIM2) acts a cytosolic sensor of non-self DNA and plays a key role in inflammasome assembly, the γ-interferon-inducible protein 16 (IFI16) restricts retroviral gene expression by sequestering the transcript...
Article
Caspase-cleaved gasdermin D forms pores in cellular membranes, thus executing proinflammatory cell death by pyroptosis. Disulfiram — a drug used to treat chronic alcoholism — is now found to be an inhibitor of pore formation, which may therapeutically counteract exacerbated inflammation in sepsis and beyond.
Article
Full-text available
Compartmentalization of cellular signaling forms the molecular basis of cellular behavior. The primary cilium constitutes a subcellular compartment that orchestrates signal transduction independent from the cell body. Ciliary dysfunction causes severe diseases, termed ciliopathies. Analyzing ciliary signaling has been challenging due to the lack of...
Article
Full-text available
Compartmentalization of cellular signaling forms the molecular basis of cellular behavior. The primary cilium constitutes a subcellular compartment that orchestrates signal transduction independent from the cell body. Ciliary dysfunction causes severe diseases, termed ciliopathies. Analyzing ciliary signaling has been challenging due to the lack of...
Article
Full-text available
Compartmentalization of cellular signaling forms the molecular basis of cellular behavior. The primary cilium constitutes a subcellular compartment that orchestrates signal transduction independent from the cell body. Ciliary dysfunction causes severe diseases, termed ciliopathies. Analyzing ciliary signaling has been challenging due to the lack of...
Preprint
Full-text available
Compartmentalization of cellular signaling forms the molecular basis of cellular behavior. The primary cilium constitutes a subcellular compartment that orchestrates signal transduction independent from the cell body. Ciliary dysfunction causes severe diseases, termed ciliopathies. Analyzing ciliary signaling and function has been challenging due t...
Preprint
Full-text available
Signaling through the inflammasome is important for the inflammatory response. Low concentrations of intracellular K+ are associated with the specific oligomerization and activation of the NLRP3 inflammasome, a type of inflammasome involved in sterile inflammation. Subsequent to NLRP3 oligomerization, ASC protein binds and form oligomeric filaments...
Article
Objectives: Here we investigated a patient with inflammatory corneal intraepithelial dyskeratosis, mucosal inflammation, tooth abnormalities and, eczema to uncover the genetic and immunological basis of the disease. Methods: On suspicion of an autoinflammatory condition, Sanger sequencing of nucleotide-binding oligomerization domain-like, leucin...
Article
Rapid inflammatory responses to cytosolic threats are mediated by inflammasomes – large macromolecular signalling complexes that control the activation of the pro‐inflammatory cytokines IL‐1β and IL‐18, as well as cell death by pyroptosis. Different inflammasome sensors are activated by diverse direct and indirect signals, and subsequently nucleate...
Chapter
Our understanding of infection biology is based on experiments in which pathogen or host proteins are perturbed by small compound inhibitors, mutation, or depletion. This approach has been remarkably successful, as, for example, demonstrated by the independent identification of the endosomal membrane protein Niemann-Pick C1 as an essential factor f...
Article
The unique class of heavy chain-only antibodies, present in Camelidae, can be shrunk to just the variable region of the heavy chain to yield VHHs, also called nanobodies. About one-tenth the size of their full-size counterparts, nanobodies can serve in applications similar to those for conventional antibodies, but they come with a number of signatu...
Article
Inflammasomes are the central signaling hubs of the inflammatory response. They process cytosolic evidence of infection, cell damage, or metabolic disturbances, and elicit a pro-inflammatory response mediated by members of the interleukin-1 family of cytokines and pyroptotoic cell death. On the molecular level, this is accomplished by the sensor-nu...
Article
Zanoni et al. (2017) show that the LPS receptor CD14 promotes internalization of oxidized phospholipids, a hallmark of dying cells, triggering hyperactivation of dendritic cells and macrophages. Their findings reveal CD14 as a regulator of responses to infection and damage, relaying context-dependent signals that determine inflammatory cell fate de...
Article
Full-text available
CD47 is an antiphagocytic ligand broadly expressed on normal and malignant tissues that delivers an inhibitory signal through the receptor signal regulatory protein alpha (SIRPα). Inhibitors of the CD47-SIRPα interaction improve antitumor antibody responses by enhancing antibody-dependent cellular phagocytosis (ADCP) in xenograft models. Endogenous...
Article
Full-text available
New genetic tools allow the disruption of every single gene. Yet, we only have limited tools to target biological processes at the protein level. Alpaca nanobodies can modulate and visualize protein function in living cells. This article describes a functional screening approach that identifies nanobodies based on the phenotype they elicit when exp...
Article
The transcription and replication machinery of negative-stranded RNA viruses presents a possible target for interference in the viral life cycle. We demonstrate the validity of this concept through the use of cytosolically expressed single-domain antibody fragments (VHHs) that protect cells from a lytic infection with vesicular stomatitis virus (VS...
Article
Full-text available
IMPORTANCE Influenza virus strains can rapidly escape from protection afforded by seasonal vaccines or acquire resistance to available drugs. Additional ways to interfere with the virus life cycle are therefore urgently needed. The influenza virus nucleoprotein is one promising target for antiviral interventions. We have previously isolated alpaca-...
Data
NP mutation E375R abolishes αNP-VHH1 binding. αNP-VHH1 and Renilla luciferase fusions of influenza virus A/WSN/33 NP wild type (WT) or E375R or vesicular stomatitis virus N were transiently coexpressed in 293T cells. Cell lysates were incubated in 96-well plates coated with anti-HA antibody to capture the VHHs. (A) Activity of the copurified lucife...
Data
αNP-VHH1 stains NP in cells infected with WSN and PR8 strains. A549 cells were infected with influenza virus A/WSN/33 or A/PR/8/34 and harvested 6 h postinfection. Cells were fixed, permeabilized, stained with αNP-VHH1-Alexa Fluor 647, and analyzed by flow cytometry. Download
Article
Manipulation of proteins is key in assessing their in vivo function. Although genetic ablation is straightforward, reversible and specific perturbation of protein function remains a challenge. Single domain antibody fragments, such as camelid-derived VHHs, can serve as inhibitors or activators of intracellular protein function, but functional testi...
Article
Full-text available
Myeloid cells assemble inflammasomes in response to infection or cell damage; cytosolic sensors activate pro–caspase-1, indirectly for the most part, via the adaptors ASC and NLRC4. This leads to secretion of proinflammatory cytokines and pyroptosis. To explore complex formation under physiological conditions, we generated an alpaca single domain a...
Article
Inflammasomes are cytosolic caspase-1-activation complexes that sense intrinsic and extrinsic danger signals, and trigger inflammatory responses and pyroptotic cell death. Homotypic interactions among Pyrin domains and caspase recruitment domains (CARDs) in inflammasome-complex components mediate oligomerization into filamentous assemblies. Several...
Article
Full-text available
Author Summary The fungus Candida albicans is not only a commensal of the digestive system, but also a common cause of human opportunistic infections. Macrophages and dendritic cells can eliminate C. albicans by phagocytosis, a complex process that involves extensive membrane reorganization at the cell surface. The extent to which membrane lipids,...
Article
Full-text available
Perturbation of protein-protein interactions relies mostly on genetic approaches or on chemical inhibition. Small RNA viruses, such as influenza A virus, do not easily lend themselves to the former approach, while chemical inhibition requires that the target protein be druggable. A lack of tools thus constrains the functional analysis of flu-encode...
Article
Full-text available
ER-resident proteins destined for degradation are dislocated into the cytosol by components of the ER quality control machinery for proteasomal degradation. Dislocation substrates are ubiquitylated in the cytosol by E2 ubiquitin-conjugating/E3 ligase complexes. UBE2J1 is one of the well-characterized E2 enzymes that participate in this process. How...
Article
Poxvirus genome uncoating is a two-step process. First, cytoplasmic viral cores are activated and early viral genes are expressed. Next, cores are disassembled and the genomes released. This second step depends on an early viral factor(s) that has eluded identification for over 40 years. We used a large-scale, high-throughput RNAi screen directed a...
Article
Full-text available
Host cell entry of vaccinia virus, the prototypic poxvirus, involves a membrane fusion event delivering the viral core and two proteinaceous lateral bodies (LBs) into the cytosol. Uncoating of viral cores is poorly characterized, and the composition and function of LBs remains enigmatic. We found that cytosolic cores rapidly dissociated from LBs an...
Article
Recent studies have revealed new insights into the endocytosis of vaccinia virus (VACV). However, the mechanism of fusion between viral and cellular membranes remains unknown. We developed a microfluidic device with a cell-trap array for immobilization of individual cells, with which we analyzed the acid-dependent fusion of single virions. VACV par...
Article
Full-text available
Immobilisation of liposomes and cells is often a prerequisite for long-term observations. The most common immobilisation approaches rely on surface modifications, encapsulation in porous materials or trapping in microfluidic channels by means of hurdle-like structures. While these approaches are useful for larger mammalian cells, the immobilisation...
Conference Paper
We developed a microfluidic device that allows, for the first time, the kinetic investigation of the fusion of single vaccinia virions (VACVs) with single cells initiated by a fast low-pH trigger.
Article
To ensure spread from one cell to another, exocytosed vaccinia virions recruit cellular actin polymerization machinery to blast off from the cell surface on actin tails. Humphries et al. (2012) now show that the virus exploits clathrin to organize viral factors into a launch pad that facilitates efficient actin tail formation.
Article
The mechanisms used by viruses to enter and replicate within host cells are subjects of intense investigation. These studies are ultimately aimed at development of new drugs that interfere with these processes. Virus entry and infection are generally monitored by dispensing bulk virus suspensions on layers of cells without accounting for the fate o...
Article
Poxviruses are characterized by their large size, complex composition, and cytoplasmic life cycle. They produce two types of infectious particles: mature virions (MVs) and extracellular virions (EVs). Both MVs and EVs of vaccinia virus, the model poxvirus, take advantage of host cell endocytosis for internalization: they activate macropinocytosis-t...
Article
Full-text available
Vaccinia virus (VACV), the model poxvirus, produces two types of infectious particles: mature virions (MVs) and extracellular virions (EVs). EV particles possess two membranes and therefore require an unusual cellular entry mechanism. By a combination of fluorescence and electron microscopy as well as flow cytometry, we investigated the cellular pr...
Article
Full-text available
To enter host cells, vaccinia virus, a prototype poxvirus, can induce transient macropinocytosis followed by endocytic internalization and penetration through the limiting membrane of pinosomes by membrane fusion. Although mature virions (MVs) of the Western reserve (WR) strain do this in HeLa cells by activating transient plasma membrane blebbing,...
Article
Full-text available
The RNA-dependent RNA polymerase of influenza virus is a heterotrimer formed by the PB1, PB2, and PA subunits. Although PA is known to be required for polymerase activity, its precise role is still unclear. Here, we investigated the function of the N-terminal region of PA. Protease digestion of purified recombinant influenza virus A/PR/8/34 PA init...

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