Rijneveld infected mice with the bacterium Streptococcus pneumoniae. This bacterium causes more than 50% of all bacterial cases of pneumonia. The physician studied the inflammation process in the lungs during the infection. She found that two different proteins worked together to overcome the pneumonia.
The inflammatory responses were studied by examining mouse lungs for the presence of cytokines. The researcher also examined the number and type of inflammatory cells which migrated to the lungs during the infection. The production of cytokines in the lungs was found to be crucial for a good immune response to the bacterial infection.
In her research, Rijneveld used mice without the receptor for IL-1. The cytokine interleukin 1 (IL-1) is necessary for the immune response during the first phase of the pneumonia. The physician discovered that in addition to IL-1, TNF-alpha is also important for the survival of mice with bacterial pneumonia. If the cytokine tumour necrosis factor-a (TNF-alpha) is inhibited in ill mice without IL-1, all of these mice die.
Cytokines are small proteins which function as messenger molecules in the immune system. The cytokines coordinate the inflammatory response by recruiting the white blood cells to the invading bacteria. In this manner, IL-1 and TNF stimulate the inflammatory process and thus the attack on the bacteria.
Ultimately this knowledge about the inflammatory mechanisms can be used to develop new treatments. This is important because pneumonia is still the number five killer in the world today.
For further information please contact Anita Rijneveld (Academic Medical Centre, University of Amsterdam), tel. 31-20-566-9111, e-mail: a.w.rijneveld@amc.uva.nl . The doctoral thesis was defended on 9 May 2003. Ms Rijneveld's supervisors were Prof. T. van der Poll and Prof. P. Speelman.
The research was funded by the Netherlands Organisation for Scientific Research.