Laboratory Findings in Osteoarthritis

Investigations of wear particles and selected cytokines in human osteoarthritic knee joints

Inflammation of the synovial membrane (synovitis) is considered to drive the process that leads to osteoarthritis. However, the relationships between the mediators of inflammation and the properties of wear particles are not fully understood. In this study, the levels of IL-6 and IL-8 were assessed in different grades of osteoarthritis to determine whether their concentrations in the synovial fluid correlate with specific characteristics of wear particles. This study has found that the size, adhesion and nano-surface roughness of wear particles have medium strong to strong correlations with IL-6 and IL-8. This study provided evidence that the characteristics of wear particles contain valuable information for grading the disease process and the need for further evaluation of the association of properties of wear particles and the inflammatory process.

Serological markers of erosive hand osteoarthritis

This review focuses on biomarkers in erosive hand osteoarthritis (EHOA), a subset of hand osteoarthritis (HOA), that primarily affects interphalangeal joints and is characterized by abrupt onset, severe pain and functional impairment, as well as signs of inflammation, in particular stiffness, swelling, erythema, paraesthesiae, and worse outcome. Inflammatory features and radiographic erosions are the main diagnostic hallmarks of this particular disease subset. As in other fields of OA, EHOA biomarkers can be classified as dry and soluble. Soluble biomarkers which are found in serum, synovial fluid and urine can be specific indicators of joint inflammation and degradation. With regard to inflammatory markers, C-reactive protein and myeloperoxidase have been found to be increased in EHOA, with respect to non-erosive HOA. All these markers have, moreover, been found to be correlated with disease activity. Another interesting marker linked to inflammation is hyaluronic acid, considered to be a marker of synovitis, which is frequently found in EHOA. The most useful cartilage markers in both erosive and non-erosive HOA, seems to be collagen (Coll) 2-1, Coll 2-1NO(2) and Col2-3/4C(short). Immunogenetic markers were also determined and an association between EHOA and a single nucleotide polymorphism on the gene encoding interleukin-1β was found in HLA and there was an increased frequency of HLA-B44 and HLA-DRB1*07 in EHOA.

High sensitivity C-reactive protein is associated with lower tibial cartilage volume but not lower patella cartilage volume in healthy women at mid-life

INTRODUCTION

Elevated serum high sensitivity C-reactive protein (hsCRP) has been reported in established osteoarthritis (OA). The aim of this study was to determine whether serum levels of hsCRP are associated with the variation in tibial and patella cartilage volumes in women without evidence of OA.

METHODS

Participants were recruited from a database established from the Australian electoral roll, and were aged 40 to 67 years, were not hysterectomized and had no significant knee pain or knee injury in the last 5 years. Tibial and patella cartilage volumes were measured from magnetic resonance imaging (MRI) of each woman's dominant knee and hsCRP measured in serum. Linear regression models were used to explore the major determinants of variation in both tibial and patella cartilage volume and to assess whether serum hsCRP made an independent contribution to variation in the volumes of cartilage in the two knee compartments.

RESULTS

The mean age of the 176 participants was 52.3 +/- 6.6 years. Compared with a standard model for tibial cartilage volume that included bone area, age, smoking and alcohol status, the addition of an hsCRP term made an independent negative contribution to variation in tibial cartilage volume, irrespective of whether body mass index (BMI) was included in the model or not. By contrast, using a similar approach, hsCRP did not contribute independently to variation in patella cartilage volume.

CONCLUSION

In asymptomatic women aged 40 to 67 years, serum hsCRP is independently negatively associated with the volume of tibial but not patella cartilage suggesting that subclinical inflammation may predispose to knee cartilage loss in the tibial compartment. This should be further assessed by a longitudinal study.