Biology subjects

Jongerius, I.

Publications and source records attributed to Jongerius, I..

4 recordsLinked to original sources

bioRxiv2020

Molecular basis for B. pertussis interference with complement, coagulation, fibrinolytic and contact activation systems: The cryo-EM structure of the Vag8-C1 inhibitor complex

Complement, contact activation, coagulation, and fibrinolysis are serum protein cascades that need strict regulation to maintain human health. Serum glycoprotein, C1-inhibitor (C1-INH) is a key regulator (inhibitor) of serine proteases of all the above-mentioned pathways. Recently, an autotransporter protein, Virulence Associated Gene 8 (Vag8) produced by the whopping cough causing pathogen, Bordetella pertussis has been shown to bind and interfere with C1-INH function. Here we present the structure of Vag8: C1-INH complex determined using cryo-electron microscopy at 3.6 [A] resolution. The structure shows a unique mechanism of C1-INH inhibition not employed by other pathogens where Vag8 sequesters the Reactive Centre Loop of the C1-INH preventing its interaction with the target proteases. ImportanceThe structure 105 kDa protein complex is one of the smallest to be determined using cryo-electron microscopy at high resolution. The mechanism of disrupting C1-INH revealed by the structure is crucial to understand how pathogens by producing a single virulence factor can disturb several homeostasis pathways. Virulence mechanisms such as the one described here assume more importance given the emerging evidence about dysregulation of contact activation, coagulation and fibrinolysis leading to COVID-19 pneumonia.

microbiology↗

bioRxiv2020

Unravelling the effect of a potentiating anti-Factor H antibody on atypical hemolytic uremic syndrome associated factor H variants

The complement system plays an important role in our innate immune system. Complement activation results in clearance of pathogens, immune complex and apoptotic cells. The host is protected from complement-mediated damage by several complement regulators. Factor H (FH) is the most important fluid-phase regulator of the alternative pathway of the complement system. Heterozygous mutations in FH are associated with complement-related diseases such as atypical hemolytic uremic syndrome (aHUS) and age-related macular degeneration. We recently described an agonistic anti-FH monoclonal antibody that can potentiate the regulatory function of FH. This antibody could serve as a potential new drug for aHUS patients and alternative to C5 blockade by Eculizumab. However, it is unclear whether this antibody can potentiate FH mutant variants in addition to wild type FH. Here, the functionality and potential of the agonistic antibody in the context of pathogenic aHUS-related FH mutant proteins was investigated. The binding affinity of recombinant WT FH, and the FH variants, W1183L, V1197A, R1210C, and G1194D to C3b was increased upon addition of the potentiating antibody and similarly, the decay accelerating activity of all mutants is increased. The potentiating anti-FH antibody is able to restore the surface regulatory function of most of the tested FH mutants to WT FH levels. In conclusion, our potentiating anti-FH is broadly active and able to enhance both WT FH function as well as most aHUS-associated FH variants tested in this study.

immunology↗

bioRxiv2020

Bacterial immune evasion proteins: The therapeutic potential of CHIPS

Bacterial pathogens have evolved to secrete strong anti-inflammatory proteins that target the immune system. It was long speculated whether these virulence factors could serve as therapeutics in diseases in which abnormal immune activation plays a role. We adopted the secreted Chemotaxis Inhibitory Protein of Staphylococcus aureus (CHIPS) as a model virulence factor-based therapeutic agent for diseases in which C5aR1 stimulation plays an important role. We show that administration of CHIPS in human C5aR1 knock-in mice successfully dampens C5a mediated neutrophil migration during immune complex-initiated inflammation. Subsequent CHIPS toxicology studies in animal models were promising. However, during a small phase-I trial, healthy human volunteers showed adverse effects directly after CHIPS administration. Subjects showed clinical signs of anaphylaxis with mild leukocytopenia and increased C-reactive protein concentrations, suggesting an inflammatory response, which are believed to be related to the presence of relatively high circulating anti-CHIPS antibodies. Even though our data in mice shows CHIPS as a potential anti-inflammatory agent, safety issues in human subjects temper the use of CHIPS in its current form as a therapeutic candidate. The use of staphylococcal proteins, or other bacterial proteins, as therapeutics or immune-modulators in humans is severely hampered by pre-existing circulating antibodies.

microbiology↗

bioRxiv2017

Structural Design of Chimeric Antigens for Multivalent Protein Vaccines

The development of prophylactic vaccines against pathogenic bacteria is a major objective of the World Health Organisation. However, vaccine development is often hindered by antigenic diversity and the difficulties encountered manufacturing immunogenic membrane proteins. Here, we employed structure-based design as a strategy to develop Chimeric Antigens (ChAs) for subunit vaccines. ChAs were generated against serogroup B Neisseria meningitidis (MenB), the predominant cause of meningococcal disease in the Western hemisphere. MenB ChAs exploit the lipoprotein factor H binding protein (fHbp) as a molecular scaffold to display the immunogenic VR2 epitope from the integral membrane protein PorA. Structural analyses demonstrate fHbp is correctly folded and that PorA VR2 epitope adopts an immunogenic conformation. In mice, ChAs elicit antibodies directed against fHbp and PorA, with antibody responses correlating to protection against meningococcal disease. ChAs offer a novel approach for generating multivalent subunit vaccines, containing of epitopes from integral membrane proteins, whose composition can be selected to circumvent pathogen diversity.

molecular biology↗