The low molecular weight fraction of human serum albumin upregulates COX2, prostaglandin E2, and prostaglandin D2 under inflammatory conditions in osteoarthritic knee synovial fibroblasts

Abstract

BackgroundThe ability to decrease inflammation and promote healing is important in the intervention and management of a variety of disease states, including osteoarthritis of the knee (OAK). Even though cyclooxygenase 2 (COX2) has an established pro-inflammatory role, evidence suggests it is also critical to the resolution that occurs after the initial activation phase of the immune response. In this study, we investigated the effects of the low molecular weight fraction of 5% human serum albumin (LMWF-5A), an agent that has proven to decrease pain and improve function in OAK patients after intra-articular injection, on the expression of COX2 and its downstream products, prostaglandins (PGs).MethodsFibroblast-like synoviocytes from the synovial membrane of OAK patients were treated with LMWF-5A or saline as a control with or without the addition of interleukin-1β (IL-1β) or tumor necrosis factor α (TNFα) to elicit an inflammatory response. Cells were harvested for RNA and protein at 2, 4, 8, 12, and 24 h, and media was collected at 24 h for analysis of secreted products. COX2 mRNA expression was determined by qPCR, and COX2 protein expression was determined by western blot analysis. Levels of prostaglandin E2 (PGE2) and prostaglandin D2 (PGD2) in the media were quantified by competitive ELISA.ResultsIn the presence of either IL-1β or TNFα, LMWF-5A increased the expression of both COX2 mRNA and protein, and this increase was significant compared to that observed with IL-1β- or TNFα-stimulated, saline-treated cells. Downstream of COX2, the levels of PGE2 were increased only in TNFα-stimulated, LMWF-5A-treated cells; however, in both IL-1β- and TNFα-stimulated cells, LMWF-5A increased the release of the anti-inflammatory prostaglandin PGD2.ConclusionLMWF-5A appears to trigger increased anti-inflammatory PG signaling, and this may be a primary component of its therapeutic mode of action in the treatment of OAK.

On the Mechanisms of Action of the Low Molecular Weight Fraction of Commercial Human Serum Albumin in Osteoarthritis

“…Synovial fluid contains inflammatory cytokines as well as inflammatory cells, and fibroblast-like synoviocytes isolated from OA patients are targets of the DAMP system to secrete such cytokines [46, 47]. As in PBMCs, LMWF5A stimulates the production of both COX-2 and prostaglandin E 2 when fibroblast-like synoviocytes are challenged with IL1-beta and, especially, TNF-alpha; more significantly, LMWF5A increases release of the anti-inflammatory prostaglandin PGD 2 , especially in response to TNF-alpha stimulation [48].…”

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“…Elevated PGD2 is considered to trigger anti-inflammatory cascade as it is spontaneously converted into 15-deoxy-Δ12, 14-prostaglandinJ2 (15d-PGJ2) which has been proven to be to anti-inflammatory by inhibition of NF-κB pathway. 33 , 34 Minami et al reported that PGD2 suppressed PGE2-induced allodynia, demonstrating an antinociceptive role of PGD2. 35 In line with our study, we observed the remarkable increases of serum PGE2 and PGI2 and an obvious decrease of serum PGD2 in the model group, and there were noticeable decreases of PGE2 and PGI2 and a prominent increase of PGD2 in the DLTH group, confirming that intra-articular DLTH therapy does ease arthritis pain at some levels.…”

LMWF-5A for the Treatment of Severe Osteoarthritis of the Knee: Integrated Analysis of Safety and Efficacy

“…The in vitro pharmacologic activity of LMWF-5A includes antiinflammatory effects through reduction of proinflammatory cytokine release (tumor necrosis factor-α and interferon-g), 9,11,29 vascular permeability in human retinal endothelial cells, 30 mobilization and differentiation of mesenchymal stem cells derived from bone marrow to tissue-specific cells, 31 protection of cells from apoptosis and autophagia, 31 and upregulation of both cyclooxygenase-2 messenger ribonucleic acid and cyclooxygenase-2 protein in human synovial fibroblasts, human normal and osteoarthritic chondrocytes, and peripheral blood monocytes, including the production of the anti-inflammatory prostaglandin D2 and its metabolite 15d-prostaglandin J2. 29,32 These mechanisms occur to a greater degree among patients with severe osteoarthritis and account for the observed benefit in this population of patients with Kellgren-Lawrence grade 4 osteoarthritis. 29,32 The anti-inflammatory activity of LMWF-5A on macrophages also suggests greater relief of symptoms for patients with greater macrophage-mediated inflammation.…”

“…29,32 These mechanisms occur to a greater degree among patients with severe osteoarthritis and account for the observed benefit in this population of patients with Kellgren-Lawrence grade 4 osteoarthritis. 29,32 The anti-inflammatory activity of LMWF-5A on macrophages also suggests greater relief of symptoms for patients with greater macrophage-mediated inflammation. Other authors have shown that the quantity of knee-related activated macrophages is associated with more severe knee pain and greater radiographic severity of osteoarthritis of the knee.…”