Matthias Bickel

A review of masticatory ability and efficiency

Masticatory function can be assessed by chewing tests and questionnaires or personal interviews. Whereas the chewing tests allow the assessment of masticatory efficiency with some objectivity, questionnaires help evaluate a persons subjective responses about chewing ability. Epidemiologic studies indicate a subjective decrease in chewing ability with increasing degree of tooth loss, a trend that was confirmed in the literature. Of interest was that the subjective measures of masticatory ability are often overrated when compared with the functional tests. Masticatory function is a patient factor rather than a parameter that prosthetic treatment can qualify. It depends on a variety of personal and subjective factors that can hardly be influenced by the practitioner. This article describes and discusses scientific sociophysiologic and biomedical approaches to evaluating masticatory function.

Soluble interleukin-1 receptor — reverse signaling in innate immunoregulation

Interleukin-1 (IL-1) is one of the most important proinflammatory cytokines, regulating immunological and inflammatory processes. It induces a very efficient and self-amplifying cytokine-network. The action of IL-1 must, therefore, be under tight control. Soluble IL-1 receptor was thought to be an efficient negative regulator of the IL-1 signaling system. However, recent studies in vitro and in vivo demonstrate that soluble IL-1 receptor can act as an agonist as well, inducing intracellular signaling events. This feature of soluble IL-1 receptor adds a new level of complexity to our understanding of ligand-receptor cross-talk and cell-to-cell communication.

Soluble IL‐1 receptor type I binds to human dermal fibroblasts and induces calcium flux

Soluble cytokine receptors appear to modify ligand concentrations by stabilizing ligands or by specifically inhibiting interactions of ligands with their membrane‐bound receptors. Here we describe a new function of the soluble interleukin‐1 receptor type I (IL‐1sR I). This receptor induced a transient rise of intracellular free calcium concentration in human dermal fibroblasts in a dose‐dependent fashion. Mobilization of calcium by IL‐1sR I was abolished in the presence of an equimolar concentration of IL‐1 receptor antagonist (IL‐1ra). Neutralizing antibodies against IL‐1β also abolished calcium mobilization stimulated with IL‐1sR I indicating that IL‐1β is involved. IL‐1sR I bound with high affinity (K d 1–2 nM) to the fibroblasts. In addition, IL‐1sR I enhanced expression of IL‐6 and IL‐8 mRNA. The observation that IL‐1sR I can act as a ligand and agonist for membrane IL‐1 extends the concept of the ligand‐receptor functions of both IL‐1 and IL‐1sR I and adds a new dimension to the cytokine network.

Autologous Versus Allogeneic T Cell-Stimulated IL-6 Production by Dermal Fibroblasts

T cells adhere to human dermal fibroblasts (HDF). This cellular interaction leads to a pronounced secretion of the proinflammatory cytokines IL-6 and IL-8 via a juxtacrine stimulation induced by HDF-associated IL-1. Upon stimulation, fibroblasts express various surface proteins such as MCH-I molecules, which may interact with corresponding receptors on T cells. The present study was conducted to further investigate the mechanism of this complex interaction with regard to the secretion of IL-6 in cocultures of T cells and HDF. IL-6 was time- and dose-dependently upregulated in such cocultures. Spatial separation of the cells by microporous membranes resulted in a 90% reduction of IL-6 secretion, but when cells had limited cell contact IL-6 secretion was increased again. Allogeneic cocultures of T cells and HDF showed increased capacity of IL-6 stimulation as compared to autologous cultures. Our results suggest that MHC-I/T cell receptor interaction modulates IL-6 secretion in allogeneic and autologous cocultures.