Functional folate receptor beta-expressing macrophages in osteoarthritis synovium and their M1/M2 expression profiles

Abstract

The distribution and M1/M2 expression profiles of FR-β+ synovial macrophages were different between OA and RA synovial tissues. Thus, the findings underscore that the M1/M2 paradigm using surface markers FR-β and CD163 is an oversimplification of macrophage subsets. Functional FR-β present on OA synovial macrophages provides a potential tool for the diagnosis and treatment of OA.

Molecular Imaging of Folate Receptor β–Positive Macrophages during Acute Lung Inflammation

“…However, FRb 1 macrophages have been shown to express a mixed pattern of M1 and M2 markers in synovial tissue from patients with osteoarthritis and rheumatoid arthritis (33). Based on available data, it appears that the precise phenotype of FRb 1 myeloid cells may depend on the local microenvironment, as well as the activating stimulus.…”

Further evidence for the anti-inflammatory activity of oleocanthal: Inhibition of MIP-1α and IL-6 in J774 macrophages and in ATDC5 chondrocytes

“…These results are of particular interest since synovial macrophages are known to contribute to the pathogenic cascade that leads to OA and rheumatoid arthritis via the generation of inflammatory cytokines and reactive oxygen intermediates (Bondeson et al, 2006). Targeting macrophages using anti-inflammatory phytopharmaceuticals may, therefore, represent a strategy to alleviate synovitis and deleterious mediators in the synovial fluid (Tsuneyoshi et al, 2012). Besides macrophages, chondrocytes are also a promising target of antiinflammatory agents.…”

Antiinflammatory Activity of a Novel Folic Acid Targeted Conjugate of the mTOR Inhibitor Everolimus

“…So far, only the FR-α and FR-β isoforms have been conclusively shown to display receptor binding functionality, that is, the ability to bind/internalize physiological folates with high specificity (8). While FR-α is frequently overexpressed by cancer cells of epithelial origins (7,8), FR-β is mostly expressed in functional form by activated macrophages (and their monocyte precursors) during inflammatory episodes that can lead to irreversible tissue and joint damage (9,10). Thus, FR-β-expressing macrophages have emerged as a promising target for antibody-or ligand-mediated drug delivery to control local and systemic inflammation (11).…”