Saturday, December 27, 2014
Advanced Testing for Rheumatoid Arthritis
Vectra DA is an advanced blood test that helps you and your doctor to better understand your RA disease activity. Vectra DA can be used to measure the level of disease activity at a specific point in time and to track changes in disease activity over time. The more you and your doctor know about your RA, the better you can manage it.
Vectra DA measures the levels of 12 proteins in blood (also called biomarkers) that have been linked to RA disease activity in clinical studies. These 12 biomarkers are combined into a single score that indicates your current level of disease activity. The Vectra DA score can help you understand what's going on below the surface - beyond those signs and symptoms you and your doctor can see and feel. It does not replace your doctor's evaluation, but adds a precise, objective measure of the biology driving RA disease.
Vectra DA is intended for adults who have been diagnosed with RA. Over 100,000 people with RA have already been tested with Vectra DA, and new patients every day are getting a more comprehensive look at their RA disease activity with this advanced blood test.
The 12 Vectra DA biomarkers
VCAM-1 (vascular cell adhesion molecule-1) is an adhesion molecule expressed by endothelial and synovial cells. VCAM-1 may contribute to cellular recruitment to synovial tissue, as well as to cartilage invasion and destruction by fibroblasts. Vectra DA measures the soluble form of VCAM-1.12-15
EGF (epidermal growth factor) is a growth factor secreted by macrophages, fibroblasts, and endothelial cells in RA joint tissue. EGF is associated with proliferation and differentiation of stromal cells (fibroblasts, chondrocytes, endothelial cells) and can induce production of inflammatory mediators and proteinases in these cells. EGF may also modulate the hepatic acute-phase response.16-19
VEGF-A (vascular endothelial growth factor A) is a potent angiogenic growth factor and vascular permeability factor expressed by various synovial cells including fibroblasts and macrophages. VEGF-A promotes inflammation, fluid accumulation, and bone erosion.20-22
IL-6 (interleukin 6) is a cytokine produced by multiple cells, including leukocytes, fibroblasts, and skeletal cells in RA. IL-6 is a major driver of RA inflammation, cartilage degradation, bone erosion, and the hepatic acute-phase response.23-25
TNF-RI (tumor necrosis factor receptor, type 1) is a receptor for TNF-α that is expressed on the membranes of numerous cell types. TNF-RI-mediated signaling contributes to multiple effects of TNF-α, including induction of cell death. Vectra DA measures the soluble form, TNF-RI, which binds to and neutralizes TNF-α.26,27
MMP-1 (matrix metalloproteinase-1 or collagenase-1) is a collagen-degrading enzyme that contributes to cartilage destruction in RA, and to leukocyte invasion and angiogenesis in the synovial tissue.28
MMP-3 (matrix metalloproteinase-3 or stromelysin-1) is an enzyme that degrades glycosaminoglycan components of cartilage and also activates the collagenase MMP-1.29-31
YKL-40, or human cartilage glycoprotein 39, is secreted primarily by chondrocytes and differentiated macrophages. YKL-40 may promote chondrocyte and fibroblast proliferation and antagonize cartilage destruction. YKL-40 reactive T cells have been found in RA patients, suggesting that they may contribute to RA autoimmunity.32-36
Leptin is a hormone secreted by adipose tissue, synovial tissue, and bone. A satiety factor associated with obesity, leptin can also activate leukocytes and regulate bone remodeling.37-41
Resistin is also a hormone associated with the adipose tissue. Like leptin, it can be secreted by synovial tissue and bone and promotes inflammation and bone remodeling. Resistin has been associated with obesity and diabetes.42-45
SAA (serum amyloid) is a major acute-phase protein secreted by the liver in response to inflammation. Like CRP, elevated SAA may be associated with cardiovascular risk. SAA may also be produced by synovial fibroblasts and chondrocytes, and may induce proinflammatory activation of fibroblasts, macrophages, and T cells.46-50
CRP (C-reactive protein) is another major acute-phase protein secreted by the liver in response to inflammation. Elevated CRP levels are associated with an elevated risk of cardiovascular disease.51-54