How to Use Synovial Immunohistology as a Tool for the Better Understanding of the Clinical Use of Different Antirheumatic Treatments

Introduction

Rheumatoid arthritis (RA) is a chronic disease characterized by inflammation of the synovium that outlines the inner cavity of synovial joints except for cartilage surfaces. It is a heterogeneous disease spanning several disease subsets with potential distinct pathogenic pathways. Several antirheumatic therapies are available today, either classic disease modifying antirheumatic drugs (DMARD) with a broad nonspecific immune modulation effect or modern biologicals, partly native human substances produced by gene technology that target specific molecule in the immune system. Despite this, it is still difficult to find the best treatment for each patient right from the beginning and still there are few complete remissions and limited effects in about 30% of the patients. A way to address this question is to better understand the mechanisms of action of each individual antirheumatic drug in distinct clinical settings. This might, in turn, lead to a better clinical use and hopefully to the discovery of good biomarkers for therapy response. However, this type of research is somewhat difficult in RA due to difficulties in investigating the site of active inflammation (ie, the inflamed synovium).

Abstract

Arthroscopy is a safe and reliable technique to obtain synovial biopsies for studies of the local inflammatory process in joint diseases such as rheumatoid arthritis. In this review we aimed to provide an overview on the use of this particular research tool in studies concerning mechanisms of action of distinct antirheumatic drugs. These studies contribute to identification of both new therapeutic targets and synovial biomarkers for prediction of disease outcome and therapy response. We conclude that further development and standardization as well as efforts to organize large synovial tissue biobanks are warranted.

Keywords

synovial biopsies, immunohistochemistry, anti rheumatic drugs, synovial biomarkers