Differential ability of a thiazolidinedione PPARγ agonist to attenuate cytokine secretion in primary microglia and macrophage‐like cells

Abstract

Peroxisome proliferator-activated receptor gamma (PPARc) agonists are known to inhibit select pro-inflammatory changes in models of CNS and systemic inflammation. Recent reports suggest that these anti-inflammatory effects are due to mechanisms other than canonical nuclear receptormediated transcriptional alteration. Using primary microglia and the monocytic cell line, THP-1, we demonstrate that rosiglitazone, a PPARc-activating thiazolidinedione, decreases pro-inflammatory cytokine secretion as measured by ELISA. Cells were pre-treated with various thiazolidinediones, including rosiglitazone, prior to stimulation with lipopolysaccharide or phorbol 12-myristate 13-acetate (PMA) to stimulate cytokine production. Tumor necrosis factor alpha (TNFa) secretion was significantly inhibited in both primary microglia and THP-1 cells differentiated for 72 h in the presence of PMA to induce a macrophage-like phenotype. No reduction in TNFa secretion was observed in undifferentiated THP-1 cells with rosiglitazone pre-treatment. Electrophoretic mobility shift assay revealed no significant difference in PPARc activation between PMA-differentiated and undifferentiated THP-1 cells. When PMA-differentiated and undifferentiated THP-1 cells were treated with the irreversible PPARc antagonist, GW 9662, a significant, dose-dependent decrease in TNFa secretion was observed. These results suggest that the anti-inflammatory benefit of PPARc ligands occur independently of classical PPARc activation.

Anti-inflammatory Effects of Thiazolidinediones in Human Airway Smooth Muscle Cells

“…Our data show that the reduction of PPARg expression did not affect the ability of troglitazone to inhibit the IL-1b-induced release of IL-6 or VEGF from HASM cells (Figure 3). Other studies also suggest the existence of PPARg-independent anti-inflammatory effects of TZDs (15). These results are also consistent with data obtained by others using PPARg-deficient macrophages.…”

“…However, emerging evidence indicates that this class of drugs also has potent antiinflammatory effects. In vitro, these drugs inhibit the release of various cytokines from activated lymphocytes (12), monocytes (13), endothelial cells (14), microglia, and Phorbol 12-myristate 13-acetate-differentiated THP-1 cells (a human monocytic cell line) (15). In vivo, rosiglitazone and pioglitazone also effectively inhibit airway inflammation in various murine models of asthma (16,17).…”

The PPAR-γ Agonist, Darglitazone, Restores Acute Inflammatory Responses to Cerebral Hypoxia–Ischemia in the Diabeticob/obMouse

“…Various PPAR-g agonists have been shown to suppress the proinflammatory response mediated by microglia/macrophage after cerebral ischemic-reperfusion injury (Luo et al, 2006;Woster and Combs, 2007).…”

A novel cell line from spontaneously immortalized murine microglia

“…This in vitro model system provides a versatile tool, allowing direct application of exogenous stimulating or inhibiting agents to microglia, collection of secreted factors, and observation of microglial activities such as migration, proliferation and phagocytosis. In our laboratory, primary microglial cultures are routinely isolated from mixed cultures of neonatal mouse cerebral cortices and utilized to investigate responses to inflammatory stimuli as well as efficacy of anti-inflammatory agents (Dhawan et al, 2012; Floden et al, 2005; Nagamoto-Combs and Combs, 2010; Rojanathammanee et al, 2013; Sondag et al, 2009; Woster and Combs, 2007). However, isolation of primary microglia cultures requires a cumbersome procedure involving dissociation of brain tissue and 14 days of pre-culturing as a mixed cell population (Floden et al, 2005).…”