UNIVERSITÄT ZU KÖLN

Scientists at the University of Cologne discover that the linear ubiquitin assembly complex (LUBAC) is essential for proper immune response and demonstrate the potential of targeted therapeutic interventions in managing immune dysregulation / publication in ‘Nature Immunology’

A team of researchers led by Dr Hirotsugu Oda at the University of Cologne’s CECAD Cluster of Excellence for Aging Research has discovered the role a specific protein complex plays in certain forms of immune dysregulation. The result may lead to new therapeutic approaches aimed at reducing autoinflammation and ‘repairing’ the immune systems of patients who suffer from a genetic dysfunction of this protein complex. The study ‘Biallelic human SHARPIN loss of function induces autoinflammation and immunodeficiency’ has been published in the journal Nature Immunology.

LUBAC, the linear ubiquitin assembly complex comprising the proteins HOIP, HOIL-1, and SHARPIN, has long been recognized for its critical role in maintaining immune homeostasis. Previous studies conducted on mouse models have elucidated the profound consequences of SHARPIN loss, leading to severe dermatitis due to excessive cell death of skin cells. However, the specific implications of SHARPIN deficiency in human health have remained elusive until now.

Press release

Researchers uncover intriguing parallels in plant and animal immune systems. Groups of proteins that are similar in both life forms rely on calcium levels to trigger an immune response / publication in ‘Cell Host & Microbe’.

A new study provides insights into how a family of immune proteins in plants confers disease resistance. The study builds on previous research by the same research group which highlighted the structural similarities of this protein family between plant and animal immune systems. The study led by Dr Takaki Maekawa at the University of Cologne’s Institute for Plant Sciences and the CEPLAS Cluster of Excellence on Plant Sciences was published in the journal Cell Host & Microbe under the title “Cytoplasmic calcium influx mediated by plant MLKLs confers TNL-triggered immunity”.

Press release

In February 2024, the Ising lab (Christina Ising, Jana Hollenbeck, Francesco Santarelli, Asmita Majumdar) together with Bernhard Schermer, Nephrolab, took part in the Cologne Children’s University. With support from the SFB 1403 and CECAD, they guided 12 kids from elementary school through their workshop called “Sauer macht lustig – oder?”. In this workshop, the kids learned about pH values and their meaning, measured pH values of several substances available in everbodies home and then experimentally found out that pH changes can lead to death of cells. The workshop was a great success and not only the participating children, but all organizers involved had an amazing afternoon.

SFB1403 goes second funding period

Keeping tissues healthy

CRC 1403 ‘Cell death in immunity, inflammation and diseases‘, which was established at the University of Cologne in 2020, will receive a total of around 12.6 million euros for a further four years.

The scientists of the Collaborative Research Centre 1403 are pursuing a multidisciplinary approach to provide answers to new questions in cell death research. Cell death is a fundamental biological process in multicellular organisms that is crucial to maintaining tissue functions, for example when they come into contact with and fight off pathogens. Recent research has shown that cells can choose between different types of regulated cell death, which have different effects on the surrounding tissue and trigger corresponding reactions in its cells. The aim of CRC 1403 is to understand the regulatory mechanisms as well as the physiological and pathological consequences of different types of cell death in the organism.

The speakers are Professor Dr Manolis Pasparakis from the Institute for Genetics and Professor Dr Hamid Kashkar (deputy spokesperson) from the Institute for Molecular Immunology (both of the University of Cologne). Not only genetics but also botany, dermatology, internal medicine and molecular immunology are involved in the 21 sub-projects. CRC 1403 is a cooperation between the University of Cologne and the Max Planck Institute for Plant Breeding Research, the Max Planck Institute for Biology of Ageing, as well as partners at the University of Bonn, the LMU Munich, the University of Freiburg and the German Rheumatism Research Centre Berlin (DRFZ). “We are very pleased that we can continue our interdisciplinary collaboration on the subject of cell death, immunity, inflammation and diseases. This additional funding will allow us to gain important insights into the mechanisms of cell death and immunity and to use them for a better understanding of the pathophysiology of inflammatory diseases,” said Professor Dr Manolis Pasparakis.

DFG press release

Following a long standing collaboration between Cell Death and Differentiation (CDD; www.nature.com/cdd) and ECDO, lasting over 20 years, with several pivotal members belonging to both communities, CDD & ECDO have decided to strengthen their link by establishing a new prize dedicated to the memory of an exceptional scientist Professor Jürg Tschopp that contributed to both CDD and ECDO. To this end The CDD Jürg Tschopp Award will be assigned and delivered at the annual ECDO Conferences, where an official representative of CDD will present a memorial plaque and a personal prize of 2000 euros directly to the winner.

Congratulations to Manolis Pasparakis for this excellenct award!

Inaugural Lecture of Prof. Dr. rer. nat. Henning Walczak

Inaugural Lecture of Prof. Dr. rer. nat. Henning Walczak, Professor of Biochemistry "Zelltod, Inflammation und Immunität: vom molekularen Verständnis zur medizinischen Anwendung" on March 27th, 6pm - 7:30 pmB

Billions of cells kill themselves in an adults every day. Programmed cell death is a self-protection mechanism: For example, it kicks in when cells are irreparably damaged.
Normally, the body produces new cells, so that cell death and cell proliferation are in balance. Disturbances in these mechanisms are considered to be decisive factors in the development of cancer and autoimmune diseases.
This is where the biochemist and cancer researcher Henning Walczak, who is investigating the role of various proteins as receptors in the control of cell death.
Such findings are the basis for new therapeutic approaches: If the suicide program, so-called apoptosis, can be activated in a targeted manner, cancer cells kill themselves without damaging surrounding cells.
At the same time, the exact molecular background of these effects is still the subject of research - in some cases, they can also work in reverse and lead to the spread of cancer.
With his appointment as Humboldt Professor at the University of Cologne, Henning Walczak is to conduct research according to the "from bench to bedside" approach (from the laboratory to the bedside), Henning Walczak will in particular bring preclinical and clinical research more closely together. With his relocation to cologne the interdisciplinary metabolism research will be expanded there.

News in 2022

Molecules boosting plant immunity identified

Two studies published in the journal Science by researchers at the Max Planck Institute for Plant Breeding Research in Cologne, Germany in collaboration with colleagues in China have discovered natural cellular molecules that drive critical plant immune responses. These compounds have all the hallmarks of being small messengers tailored by plants to turn on key defense-control hubs. Harnessing these insights may allow scientists and plant breeders to design molecules that make plants, including many important crop species, more resistant to disease.

World food production must double by 2050 in order to feed the anticipated extra 2 billion people living on earth by then. Boosting food production requires increases in the yields of many of our staple crops. To do so, strategies need to be in place to ensure that we can make plants more resistant to microscopic infectious agents, whilst also ensuring that food production is environmentally safe. Achieving this, in turn, requires a detailed understanding of the plant immune system – the defenses that plants mount when confronted with invading microorganisms. Now, in two landmark studies, scientists led by Jijie Chai and Jane Parker from the Max Planck Institute for Plant Breeding Research in Cologne and the University of Cologne, Germany, collaborating with Junbiao Chang’s group at Zhengzhou University in Zhengzhou and Zhifu Han and colleagues at Tsinghua University in Beijing, China, have identified two classes of molecules and determined their modes of action in mediating immune responses inside plant cells. Their findings pave the way for the design of bioactive small molecules that could allow researchers and plant growers to manipulate – and thereby boost – plant resistance against harmful microbes.

At a molecular level, a main immune strategy employed by plants involves proteins called nucleotide-binding leucine-rich repeat receptors, or NLRs for short. NLRs are activated by invading microorganisms and set in motion protective immune responses. These immune responses culminate in the so-called hypersensitive response, which involves restriction of pathogen growth and often strictly demarcated death of cells at the site of infection – akin to amputating a toe to ensure survival of the body.

One class of NLR proteins, those with so-called toll/interleukin-1 receptor (TIR) domains, which are termed TIR-NLRs (or TNLs), have been shown to relay signals to the downstream immune protein Enhanced Disease Susceptibility 1 (EDS1). Smaller TIR-containing proteins also feed signals into EDS1 to potentiate disease resistance. EDS1 functions as a control hub which, depending on the types of other proteins it interacts with, pushes plant cells to restrict pathogen growth or commit to cell death. Earlier work showed that TNL receptors and TIR proteins are actually pathogen-induced enzymes. Evidence suggested that these TIR enzymes produce a small messenger or messenger(s) that signal to EDS1 inside cells. However, the identities of the precise molecules generated by TNLs or TIRs that stimulate the different immune responses have remained elusive.

Parker and colleagues established that the two functional EDS1 modules leading to immunity or cell death can be triggered by pathogen-activated TNL enzymes inside plant cells. To identify the small molecules produced by TNLs or TIRs and that act upon EDS1, the Chai group reconstituted key components of the signaling pathway in insect cells, a system that allows production and purification of high amounts of molecules which can then be isolated and characterized. Using this approach, the authors discovered two different classes of modified nucleotide molecules produced by TNLs and TIRs. These compounds preferentially bound to and activated differentEDS1 sub-complexes. Hence, the authors demonstrate that different EDS1 sub-complexes recognize particular TIR-produced molecules, which function as information-carrying chemicals, to promote immune responses.

The TIR immune receptors and EDS1 hub proteins exist in many important crop species, such as rice and wheat, and Jijie Chai points out that “the identified TIR-catalyzed small molecules could be employed as general and natural immunostimulants to control crop diseases.” Jane Parker further remarks that “knowing the biochemical modes of action of these small molecules opens a whole new chapter on plant immunity signaling and disease management.”

Original research article:

Huang S., Jia, A., Song, W., Hessler, G., Meng, Y., Sun, Y., Xu, L., Laessle, H., Jirschitzka, J., Ma, S., Xiao, Y., Yu, D., Hou, J., Liu, R., Sun, H., Liu, X., Han, Z., Chang, J., Parker, P.E., Chai, J. (2022) Identification and receptor mechanism of TIR-catalyzed small molecules in plant immunity. Science DOI: 10.1126/science.abq3297

Jia, A., Huang, S,. Song, W., Wang, J., Meng, Y,. Sun, Y., Xu, L., Laessle, H., Jirschitzka, J., Hou, J., Zhang, T., Yu, W., Hessler, G., Li, E., Ma, S., Yu, D., Gebauer, J., Baumann, U., Liu, X., Han, Z., Chang, J., Parker, J.E., Chai, J. (2022) TIR-catalyzed ADP-ribosylation reactions produce signaling molecules for plant immunity. Science 10.1126/science.abq8180

Infection with SARS-CoV-2 causes severe inflammation of the lungs and other vital organs in some patients. Vaccines provide excellent protection against these severe courses of disease. Numerous studies have investigated the role of the so-called acquired immune response after SARS-CoV-2 vaccination and have shown that specific antibodies can be measured in the blood and that these then decrease over a period of months. However, to trigger a potent and long-lasting immune response, vaccines first need to activate the innate immune system, which reacts non-specifically to foreign virus or bacteria derived proteins. Until now, it was not known how exactly and for how long the novel mRNA vaccines stimulate cells of the innate immune system. In a new study performed with vaccinated individuals, researchers at the University Hospital of Cologne focus for the first time on the signaling pathways of these immune cells and their effect on the acquired immune response. The results have now been published in the renowned scientific journal "EMBO Molecular Medicine".

The rapid development of potent vaccines against SARS-CoV-2 has greatly contributed to the containment of the pandemic. Numerous studies have demonstrated protection against severe disease progression and a reduction in transmissions following vaccination. In particular, the potent mRNA vaccines that could be developed and produced very rapidly were an important milestone for this development. Since marketing and mass-distribution of these vaccines, it has been relatively well studied how long protective effects last via the activation of the acquired immune system. However, for a protective effect to be as long-lasting and potent as possible, it is first of all important to activate the innate immune system, which triggers the interaction of various immune cells required for an anti-viral memory function. In most conventional vaccines, so-called adjuvants are used for this purpose. These are additives that are supposed to stimulate cells of the innate immune system, such as macrophages. In the case of mRNA vaccines, these classical additives are missing and the mechanism by which immune cells are stimulated shortly after vaccination is not known. This is where the research of Dr. Jan Rybniker’s group is entering the stage. "We were able to show that mRNA vaccines stimulate blood derived macrophages by exploiting a highly specific signaling pathway. Once these pre-stimulated macrophages come into contact with the SARS-CoV-2 spike protein, pro-inflammatory messenger molecules are released, which are needed for the activation of immune cells of the acquired immune system." This pre-activation of the blood cells seems to represent a protective mechanism, by which inflammation only occurs in the spike protein-producing tissue and not systemically in the whole body. The inflammatory reaction is then most likely to happen locally in the lymph node, where blood cells are known to migrate to, speculates Dr. Rybniker who is head of the Infectious Diseases Research Laboratory at the University Hospital of Cologne and senior author of the paper. The highly specific response to the spike protein observed in the study is quite unusual for cells of the innate immune system. The responsible mechanism depends on several spike protein-binding receptors on the surface of the macrophages which activate an important regulatory protein called SYK. SYK then starts a pro-inflammatory cascade in the cells. Interestingly, the observed effects were particularly pronounced after the second vaccination. However, also the third vaccination (booster) was able to re-activate macrophages even months after the first two shots had been given. Macrophages circulating in the blood have a very short life span of only a few days. "Apparently, vaccination also leads to a memory function in these short-lived cells. This important finding is novel for mRNA vaccines. The underlying mechanism could also contribute to the strong protective effect we obtain with booster vaccinations," reports Dr. Sebastian Theobald, postdoctoral fellow at the University Hospital of Cologne and first author of the study.

The SYK signaling pathway and upstream receptor molecules described in the study have long been considered as putative and attractive mechanisms by which cells of the innate immune system could be stimulated in the context of vaccination. This theory can now be confirmed for mRNA vaccines, which have a very good safety profile. The results could be used to activate similar immunity-boosting mechanisms in a very targeted manner in future vaccinations, for example via appropriate adjuvants. "mRNA-based therapies and vaccines are on the rise. Therefore, it is pivotal to gather as much information as possible on the immune responses triggered by these constructs in order to fully exploit their potential" says Dr. Rybniker.

Interestingly, the SYK pathway also appears to play a role in severe COVID-19 disease. In a previous study, the group was already able to demonstrate similar effects on blood cells of COVID-19 patients. Therefore, SYK is also considered a potential therapeutic target for immunomodulatory therapies in severe COVID-19 infection - clinical trials with corresponding drugs are already underway.

These multifaceted and in-depth investigations were only possible with the help of several collaborative partners. "Our thanks therefore go to all the research groups and researchers who contributed to the success of the study. In particular, we would like to thank the numerous vaccinated individuals who provided us with their blood for the laboratory experiments," sais Dr. Rybniker. The study was funded by the German Research Foundation (DFG). In addition, the study was significantly supported by the Immunology Platform COVIM, a collaborative project for the determination and utilization of SARS-CoV-2 immunity. COVIM is part of the Network University Medicine (NUM). The network encompasses the entire German university medicine and promotes cooperative and structure-building projects in which as many university hospitals as possible should be involved.

EMBO Molecular Medicine: https://www.embopress.org/doi/10.15252/emmm.202215888

We are excited to welcome Dr. Hirotsugu Oda our new Junior Research Group Leader. Hiro started his lab in April 2022 and his project is focussingon the immunogenetic approach to unravel adaptive immune defects in human systemic autoinflammatory diseases. Welcome to the SFB 1403!!

Congratulations to the Team of Bernhard Röck (Garcia-Saez lab, Project A02), AI Developer Michael Vorndran, Pavana Lakshmi Vaddavalli (Schumacher Lab, CECAD), and Professor Ana Garcia-Saez form the Team “Cell ImAlging”. With their idea of high throughput detection and analysis of cell death from live-cell microscopy images, they entered the 'start-up your idea' competition organized by the Gateway Excellence Start-up Center of the University of Cologne.

Out of 28 innovative ideas, Cell ImAlging made it to the final with four other teams. Here, the team pitched their idea to a digital audience and a jury of experts, and won the first prize: €5,000 and support from experts in setting up the start-up.

Read more at the Gateway ESC and CECAD

We are excited to welcome Dr. Christina Ising our new Junior Research Group Leader. Christina started her lab in January 2022 and her project is focussing on Microglia pyroptosis in Alzheimer’s disease. Welcome to the SFB 1403!!

Junior Group Leader Position for Melanie Fritsch - Congratulations!

Congratulations to Dr. Melanie Fritsch for her new Junior Group Leaeder Position!! Melanie Fritsch did her PhD and Postdoc in Prof. Hamid Kashkars lab and worked on Project B01. Together with 2 fellow SFB 1403 members she was awarded the SFB 1403 tandem grant in 2021, to promote research cooperation of animal and plant cell death research.

Within the Cancer Research Center Cologne Essen (CCCE), four internal junior research groups have been established, two in Essen and two in Cologne. In addition, two external junior research groups have been established, one in Aachen and one in Bochum. Each junior research group consists of a group leader and two to four scientific or technical team members. The junior research groups are thematically associated with the four CCCE professors but work as scientifically independent teams.

She is the Team lead for „Translational Immunooncology“ at the Campus Cologne:
After obtaining her PhD from the University of Cologne in genetics, Melanie started a PostDoc in Cologne, focusing on the regulation of programmed cell death by the protease Caspase-8. Her CCCE junior research group will investigate the alteration of cell death machinery, which has traditionally been viewed as a central feature of malignant transformation and therapy resistance in cancer patients. Melanie’s team will study how the alteration of cell death machinery controls the immune surveillance of cancer and will particularly evaluate the use of novel compounds that modify cell death signaling to conceptionally set new accents in cellular immunotherapy. This will contribute to the development of innovative therapeutic strategies for the treatment of cancer. Next to her scientific work, Melanie is involved in various fields of civil activities on voluntary basis in the City of Cologne.

You can find more information here and here

Professor Dr. Hamid Kashkar appointed to W3 professorship in Molecular Immunology

Prof. Dr. Hamid Kashkar, previously at the Institute of Medical Microbiology, Immunology and Hygiene and at the research cluster CECAD as a research group leader, will receive a W3 professorship for Molecular Immunology at the Medical Faculty of the University of Cologne as of January 1, 2022. The newly established professorship is linked to the establishment of a dedicated facility at the Faculty of Medicine. Hamid Kashkar's research, entitled "Cell Death and Immunity", deals with the role of cellular death mechanisms in the pathogenesis of immune diseases and has a high radiance for Cologne as a research location. Prof. Hamid Kashkar is involved in several special research areas of the Faculty of Medicine and Mathematics and Natural Sciences. For example, Hamid Kashkar is project leader in the Collaborative Research Center (SFB) 1218 "Regulation of cellular function by mitochondria" (spokesperson: Prof. Elena Rugarli) as well as project leader in the recently established SFB 1530 "Elucidation and targeting of pathogenic mechanisms in B-cell neoplasia" (spokesperson: Prof. Michael Hallek). In addition, Hamid Kashkar is co-spokesperson of the SFB 1403 "Cell Death in Immunity, Inflammation and Disease" (spokesperson: Prof. Dr. Manolis Pasparakis) and is also involved in other collaborative project proposals of the University of Cologne. Decisive impetus for this was provided by the sustained support of the Center for Molecular Medicine Cologne (ZMMK), which accelerated his clinic-oriented and disease-relevant research. "I am very much looking forward to the establishment of an Institute of Molecular Immunology with the aim of advancing the discipline in research and teaching and to enable the training of young scientists in this increasingly important field," said Prof. Hamid Kashkar. "The institute will serve as a catalyst for the development of novel and targeted therapies for the treatment of immune diseases, infection and cancer," adds Professor Kashkar.

As an immunologist, Hamid Kashkar is interested in the impact of cell death on the immune system. Different forms of cell death release specific mediators that induce selective immune responses. Together with his research group, he was recently able to show that different types of cell death are molecularly linked to guarantee the death of a degenerated or infected cell. Caspase-8, a protein shear (protease), plays a central role in this process and dictates various tissue responses. The study

"Caspase-8 is the molecular switch for apoptosis, necroptosis and pyroptosis" was published in the prestigious journal Nature. Immunologist Kashkar's findings play an important role in understanding immunity to cancer and infection, including future therapeutic treatment options.

Born in Tehran, Iran, in 1968, Hamid Kashkar earned a Bachelor of Science degree in biology from Urmia University, Iran, in 1991. He then moved to the University of Cologne, Germany, and received his diploma in biology in 2000. In 2002, he received his PhD with Summa cum Laude in Biology/Genetics. He habilitated in Molecular Immunology in 2008 (award for the best habilitation) and was appointed apl Professor in 2015. From 2005 to 2010, he was a research group leader at the Cologne Institute of Medical Microbiology, Immunology and Hygiene (IMMIH). In 2011, Hamid Kashkar earned the Career Development Award at ZMMK and further qualified as an independent scientist. Since 2014, Hamid Kashkar has been conducting research as an independent research group leader at the CECAD Cluster of Excellence as well as at IMMIH.

Content contact:
Professor Dr. Hamid Kashkar
+49 221 478-84091
h.kashkar@uni-koeln.de

News in 2021

An Arabidopsis regulatory module controlling pathogen resistance triggered by cell-surface and intracellular receptors

Collaborative research led by the group of Thorsten Nürnberger at ZMBP (University of Tübingen) and Jane Parker (Dept. Plant-Microbe Interactions at MPIPZ Cologne) with colleagues at ZMBP and MPIPZ has identified a convergence point for defence signalling triggered by plant cell-surface (microbial pattern recognition) and intracellular (pathogen effector recognition) immune receptors. These two receptor systems use a regulatory node consisting of three proteins: EDS1, PAD4 and ADR1 to mobilize anti-pathogen defence pathways. The new findings provide an excellent lead to how and where inside host cells cell-surface and intracellular pathogen detection systems intersect to confer strong disease resistance.

Upon ligand perception, Arabidopsis cell-surface RLK pattern-recognition receptors interact with BAK1 to activate pattern-triggered immunity (PTI). RLKs have a partial requirement for the EDS1‑PAD4‑ADR1 node (grey dashed arrow). PTI conferred by PRR RLP23, following dimerization with RLKs BAK1 and SOBIR1, signals primarily through EDS1-PAD4-ADR1. Together with an important cytoplasmic kinase (PBL31), EDS1, PAD4 and ADR1 can be detected in close proximity to an SOBIR1/RLP23 complex at the plasma membrane before and after RLP23 elicitation, suggesting presence of pre-formed complexes ready for downstream signalling. Some RLP-triggered defences do not require EDS1-PAD4-ADR1 (black dashed arrow). Effector-triggered immunity (ETI) conferred by NLR receptors uses EDS1-PAD4-ADR1 and/or a related node consisting of EDS1-SAG101 and NRG1 (green arrows). This model further erodes a previously held strict distinction between PTI and ETI, and supports the concept that surveillance systems for pathogen disturbance outside and inside plant cells use overlapping machineries for disease resistance.

(MAMPs: Microbe associated molecular patterns; RLK: Receptor-like kinase; RLP: Receptor-like protein; BAK1: BRI1-associated receptor kinase; SOBIR1: Suppressor of BIR1 1; PBL31: PBS1-like 31; EDS1: Enhanced disease susceptibility 1; PAD4: Phytoalexin deficient 4; SAG101: Senescence-associated gene 101; NLR: Nucleotide-binding leucine-rich repeat; NRG1: N requirement gene 1; ADR1:Activate disease resistance 1; PTI: Pattern triggered immunity; ETI: Effector triggered immunity).

3 Projects of SFB 1403 Junior Scientists were funded

The SFB 1403 promotes interactions between plant an animal cell death research with tandem grants for small research projects with at scientists from both fields. The tandem grants fund new reach ides with proof of principle experiments in the field of cell death.

We are happy to announce that 3 Project were funded in 2021. Congratulations to:

• "Substrates of the potential Shigella effector protease NleC: Searching for conserved targets in mammal and plant immune pathways" by Dr. Sina Barghahn (Döhlemann Lab), Dr. Melanie Fritsch (Kashkar Lab), and Melissa Mantz (Huesgen Lab)
• "Definition of microscopic hallmarks of the Programmed Cell Death in plants" by Anna Kostina (Garcia-Saez lab)
• "The Role of RBOH and SO-dependent ROS production in Serendipita indica fungal-induced cell death phase during endophytic colonization of Arabidopsis roots" by Patricia Zecua and Besarta Thaqi

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New Publication in Science

An international research team led by the University of Bonn has identified and further developed novel antibody fragments against the SARS coronavirus-2. These "nanobodies" are much smaller than the classic antibodies used to treat US President Donald Trump, for example. They therefore penetrate the tissue better and can be produced more easily in larger quantities. The researchers at the University Hospital Bonn have also combined the nanobodies into potentially particularly effective molecules. These attack different parts of the virus simultaneously. The approach could prevent the pathogen from evading the active agent through mutations. The results are published in the journal Science.

Antibodies are an important weapon in the immune system's defense against infections. They bind to the surface structures of bacteria or viruses and prevent their replication. One strategy in the fight against disease is therefore to produce effective antibodies in large quantities and inject them into the patients. The outgoing US President Donald Trump probably owes his rapid recovery to this method. However, the antibodies used to treat him have a complex structure, do not penetrate very deeply into the tissue and may cause unwanted complications. Moreover, producing antibodies is difficult and time-consuming. They are therefore probably not suitable for widespread use.

Mass production in yeast or bacteria

"We focus on another group of molecules, the nanobodies," explains Dr. Florian Schmidt, who heads an Emmy Noether group on this promising new field of research at the University of Bonn's Institute of Innate Immunity. "Nanobodies are antibody fragments that are so simple that they can be produced by bacteria or yeast, which is less expensive."

However, the immune system produces an almost infinite number of different antibodies, and they all recognize different target structures. Only very few of them are for example capable of defeating the SARS coronavirus-2. Finding these antibodies is like searching for a single grain of sand on Germany's Baltic coast. "We first injected a surface protein of the coronavirus into an alpaca and a llama," Schmidt explains. "Their immune system then produces mainly antibodies directed against this virus. In addition to complex normal antibodies, llamas and alpacas also produce a simpler antibody variant that can serve as the basis for nanobodies."

A few weeks later, the researchers took a blood sample from the animals, from which they extracted the genetic information of produced antibodies. This "library" still contained millions of different construction plans. In a complex process, they extracted those that recognize an important structure on the surface of the coronavirus, the spike protein. "Altogether we obtained dozens of nanobodies, which we then analyzed further," explains Dr. Paul-Albert König, head of the Core Facility Nanobodies at the Medical Faculty of the University of Bonn and lead author of the study.

Four out of several million

Four molecules actually proved to be effective against the pathogen in cell cultures. "Using X-ray structures and electron microscopy analyses, we were furthermore able to show how they interact with the spike protein of the virus," explains König. This work was done in the research groups around Martin Hällberg (Karolinska Institutet, Sweden) and Nicholas Wu as well as Ian Wilson (Scripps Research Institute, USA). The spike protein is crucial for the infection: It acts like a velcro fastener with which the pathogen attaches to the attacked cell. Next, the velcro changes its structure: It discards the component that is important for attachment and mediates fusion of the virus envelope with the cell. "Nanobodies also appear to trigger this structural change before the virus encounters its target cell - an unexpected and novel mode of action," says König. "The change is likely to be irreversible; the virus is therefore no longer able to bind to host cells and infect them."

The researchers also exploit another major advantage of nanobodies over antibodies: Their simple structure allows straight forward combinations to form molecules that can be several hundred times more effective. "We have fused two nanobodies that target different parts of the spike protein," explains König. "This variant was highly effective in cell culture. Furthermore, we were able to show that this drastically reduces the probability of the virus to become resistant to the active agent through escape mutations." The researchers are convinced that the molecules may be developed into a novel and promising therapeutic option.

Dioscure Therapeutics, a spin-off of the University of Bonn, will test the nanobodies in clinical studies. The success of the project is mainly based on the excellent cooperation of the participating research groups at the University with national and international cooperation partners, emphasizes Florian Schmidt, who is also a member of the Immunosensation2 Cluster of Excellence at the University of Bonn.

Funding:

Institutions from Germany, Sweden and the USA were involved in the study. Diffraction data were collected at Stanford Synchrotron Radiation Lightsource (SSRL) and at the Advanced Photon Source (APS) at Argonne National Labs in the USA.

In Germany, the study was financially supported by the Medical Faculty of the University of Bonn, the German Research Foundation, the Klaus Tschira Boost Funds, the Federal Ministry of Education and Research, the Baden-Württemberg Foundation and the MWK Baden-Württemberg. In the USA, the Bill and Melinda Gates Foundation, the U.S. Department of Energy, the National Institutes of Health (NIH), the National Institute of General Medical Sciences (NIGMS) and the National Cancer Institute (NCI) funded the project, in Sweden the Swedish Research Council and the Knut and Alice Wallenberg Foundation.

The founders of the company Dioscure were supported by the enaCom Transfer Center at the University of Bonn providing a link between research and industry with its offers. As University of Bonn's IP Service Provider, PROvendis GmbH negotiates the commercialization contract with Dioscure.

News in 2020

For plant and animal immune systems the similarities go beyond sensing

University of Cologne and SFB 1403 researcher Takaki Maekawa and colleagues have discovered that plants have independently evolved a family of immune proteins that are strikingly similar to animals.

Although profoundly different in terms of physiology, habitat and nutritional needs, plants and animals are confronted with one shared existential problem: how to keep themselves safe in the face of constant exposure to harmful microorganisms. Mounting evidence suggests that plants and animals have independently evolved similar receptors that sense pathogen molecules and set in motion appropriate innate immune responses. Now, in a study just published in the journal Cell Host & Microbe, senior author Takaki Maekawa together with co-first authors Lisa K. Mahdi, Menghang Huang, Xiaoxiao Zhang and colleagues have discovered that plants have evolved a family of proteins that bear a striking resemblance to proteins called mixed lineage kinase domain-like proteins (MLKLs), which trigger cell death in vertebrates as part of the immune response. In uncovering and characterizing an important new family of plant immune proteins, the authors’ study, which involved collaboration with fellow SFB 1403 researchers Paul Schulze-Lefert, Jane Parker and Jijie Chai, provides intriguing new insights into how plants protect themselves from microbial invaders.   

Regulated cell death often accompanies immunity against infection in plants, animals and fungi. One pervasive theory suggests that highly localised cell death responses serve to strictly limit the spread of infection. Although starting from independent origins this shared response seems to also involve highly similar machinery: many proteins involved in cell death in different kingdoms of life contain a so-called HeLo domain, a bundle structure made up of four helices, which causes resistance and cell death by disturbing the integrity of cellular membranes or forming ion channels.  

Based on the similarities between animal and plant immune systems and on the key role played by HeLo domains in cell death, Maekawa hypothesised that plants might also contain other proteins with HeLo domains. Making use of bioinformatic and structural analysis, he and his team discovered a new family of HeLo domain-containing proteins that are widely shared among different plant species, indicating that they are important for plant physiology.

Maekawa termed the proteins plant MLKLs, and for further studies he focused on MLKLs expressed in the model plant Arabidopsis thaliana. He and his team isolated MLKL proteins from A. thaliana and determined that plant MLKLs possess the same overall protein architecture as their vertebrate counterparts and also assemble into tetramer, likely auto-inhibited, structures when they’re not active. Importantly, plant MLKLs also play a role in immunity, as plants in which genes encoding these proteins were mutated and thus non-functional were susceptible to pathogen infection.

Further investigation revealed additional similarities with vertebrate MLKLs: plant MLKLs are also trafficked to cellular membranes as part of their function, and activation of these proteins leads to cell death. Maekawa now aims to discover the molecular details underlying the function of plant MLKLs in immunity: “It will be exciting to uncover exactly how MLKLs are activated upon pathogen infection and how this activation is translated into effective plant protection.”  

During her PhD in the lab of Hamid Kashkar, Melanie Fritsch was working on the role of caspase-8 in the regulation of different mechanisms of cell death and their impact on the development of systemic inflammation. For her work she received the Helga Freyberg-Rüßman-Award. The Helga Freyberg-Rüßman-Prize is awarded to outstanding scientific achievements to young scientists by the "Kölner Gymnasial- und Stiftungsfonds" in cooperation with the medical faculty of the University of Cologne.

Congratulations to Melanie Fritsch!

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