Pathogens that cause respiratory infections spread through the air. They initially infect the mucosa of the upper respiratory tract, primarily the nose and throat. Persistent infection can lead to pneumonia and even to invasion into the bloodstream causing very serious diseases such as sepsis or meningitis. Our immune system plays an important role in pathogenesis and in protection.
Marien de Jonge, appointed professor of Infection and Immunity, is studying with his research group how the epithelial cells, the cells that are in direct contact with the outside world, and how the immune cells in the mucosal tissue behave after infection. This knowledge will contribute to better protection against respiratory infections and against pathogen transmission. Enhanced understanding of the immune responses in the respiratory tract will also improve and accelerate the diagnosis of respiratory tract infections.
Improving vaccines and vaccination
In addition, Marien de Jonge is studying alternatives to common routes of vaccination. Most vaccines are administered with a needle into the muscles, but vaccination via the skin or respiratory tract might provide much better immunity. De Jonge is looking at developing a vaccine administered through the nose for protection against pneumococcal bacteria, which can cause sepsis and meningitis in vulnerable groups.
The advantage of vaccination through the nose is that the vaccine immediately reaches the right place, which is the respiratory tract. This increases the chance of protection against infection and possibly blocks the transmission of pathogens, particularly important in respiratory infections. 'The vaccine against SARS-CoV-2 leads to good protection against serious illness, but people can still become infected and still transmit the virus. The same applies to pneumococci. With a nasal spray, we may be able to further improve protection," De Jonge said. Next year, a first clinical study in humans will start with this candidate pneumococcal vaccine.
In addition, De Jonge develops new techniques for better monitoring of the dynamics of inflammatory responses and investigating the potential for a new diagnostic method to detect the causative agent of lower respiratory tract infections in exhaled air.
Better prevention and diagnosis of infectious and inflammatory diseases is relevant not only in the Netherlands, but especially for people in low- and middle-income countries where many of these diseases occur. De Jonge said, ‘There is a strong need for better protection against infectious and inflammatory diseases, as these diseases are still a major cause of serious morbidity and mortality worldwide.’
Diagnostics and treatment
As head of the Medical Immunology Laboratory, Marien de Jonge is closely involved in patient care. There is an increasing demand for assessing the immunological status of patients with inflammatory and infection-related diseases. 'Our clinical colleagues need clear and reliable laboratory results for the correct diagnosis, because that's how the patient gets the most optimal treatment.’, De Jonge said. The LMI also conducts diagnostic laboratory tests for partners in the region and elsewhere in the Netherlands for specific areas of expertise, such as autoimmune-related inflammatory diseases and transplantation immunology.
De Jonge also teaches students in the Faculty of Medical Science and the Faculty of Science. 'In recent years, trust in science has declined. Here lies an enormous challenge for us as scientists. It is important that we explain how knowledge is gained, what the latest findings are and how insights can change. Furthermore, we need scientists to inspire students to gather, apply and transmit knowledge.
De Jonge, in short, deals with a diverse range of topics. And it will continue to be so in the coming years. 'That's because there is still a lot of unexplored territory regarding the interaction between infections and our immune system. My goal is to improve our understanding of how pathogens and humans interact’, he indicates. ‘In five years, I hope to have solved a small piece of that puzzle.’\
Marien de Jonge studied Biology at VU Amsterdam. He specialized in molecular microbiology and obtained his PhD at the University of Amsterdam in 2003, for research on meningococcal infection (title thesis: Opacity proteins of Neisseria meningitidis, structure-function relationship and vaccine potential). At the Paris Institut Pasteur, he studied infection mechanisms of Mycobacterium tuberculosis and the improvement of the BCG vaccine, after which he worked at Merck Sharpe & Dohme. In 2011, he joined Radboudumc, first as a senior researcher and then as head of the Laboratory of Pediatric Infectious Diseases. Since 2021, he is head of the Laboratory of Medical Immunology. De Jonge received grants from NWO, Horizon Europe, IMI and Eurostars, among others, and is president of the Royal Netherlands Society for Microbiology (KNVM). His appointment as professor is effective Aug. 1, 2023, for a five-year term.