The dissertation shows that certain signal substances in the body, so-called cytokines, have the ability to stimulate the cells in bones to degenerate and that these cytokines are produced not only by white blood corpuscles but also by cells in the gums, so-called gum fibroblasts. The production of the cytokine interleukin-6 and its closest relatives, interleukin-11 and leukemia inhibitory factor, is stimulated by certain inflammatory cytokines and is inhibited by other anti-inflammatory cytokines from white blood corpuscles. The findings are important to our understanding of the interplay between local cells in the gums and white blood corpuscles immigrating from the blood that regulates the degradation of bone in diseases involving loosening of the teeth.
The skeleton of a healthy adult human is constantly being renewed, with some parts degrading and being replaced by new bone, on the one hand, to exchange old bone for new bone and, on the other hand, to adapt the structure of the bone to new loads. This occurs at a rate of about 10 percent of the entire bone tissue being replaced each year. In pathological conditions, the reconstruction process can be altered so that the degradation increases and the new growth cannot replace all the degenerated bone. This occurs, for example, in most of the bones in the bodies of patients afflicted with osteoporosis as a result of changes in the amounts of sex hormones. It also occurs locally in certain parts of the skeleton where inflammatory processes are underway. In patients with inflamed gums, the inflammation process can affect the replacement of the bone around the teeth in the jaws so that the bone is lost. The teeth will then become looser and looser until they fall outgum inflammation has led to loosening of the teeth.
In the same way, in patients with arthritic rheumatism, an inflammation can cause the bone in the joint to be lost, leaving the patient with pain and more and more limited joint function. Inflammation is also the cause of the loosening of certain implants in joints and in the skeleton.
The findings are significant for our understanding of how inflammation processes lead to the degradation of bone in diseases involving loosening of the teeth, arthritic rheumatism, and the loosening of prostheses in the skeleton.
On Friday, January 19, 2007, Py Palmqvist, Department of Odontology, Oral Cell Biology, Umeå University, will defend her dissertation titled Osteotropic Cytokines: Expression in Human Gingival Fibroblasts and Effects on Bone. The public defense will take place at 9:00 a.m. in Hall B, 9th floor, School of Dentistry. The external examiner is Professor Göran Andersson, Section for Pathology, Karolinska Institute, Huddinge Hospital. The main thesis supervisor is Ulf Lerner, Department of Odontology, Oral Cell Biology, Umeå University.