Small molecule activators of the Nrf2-HO-1 antioxidant axis modulate heme metabolism and inflammation in BV2 microglia cells

• Published in: Pharmacological research Vol. 76; pp. 132 - 148
• Main Authors: Foresti, Roberta, Bains, Sandip K., Pitchumony, Tamil Selvi, de Castro Brás, Lisandra E., Drago, Filippo, Dubois-Randé, Jean-Luc, Bucolo, Claudio, Motterlini, Roberto
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.10.2013; Elsevier
• Subjects: Animals; Antioxidants - metabolism; Bilirubin - metabolism; Biochemistry, Molecular Biology; BV2 microglia; Cell Line; Cell Survival - drug effects; Gene Expression Regulation - drug effects; Heme - metabolism; Heme Oxygenase-1 - genetics; Heme Oxygenase-1 - immunology; Heme Oxygenase-1 - metabolism; HO-1; Inflammation; Inflammation - drug therapy; Inflammation - immunology; Interferon-gamma - immunology; Life Sciences; Lipopolysaccharides - immunology; Mice; Microglia - cytology; Microglia - drug effects; Microglia - immunology; Microglia - metabolism; NF-E2-Related Factor 2 - immunology; NF-E2-Related Factor 2 - metabolism; Nrf2; Small molecule activators; Small Molecule Libraries - chemistry; Small Molecule Libraries - pharmacology; H; HO-1; INF-γ; LPS; SC; S; Nrf2; shRNA; BV2 microglia; ALAS 1; DMF; CA; PGE2; CAA; ISL; Inflammation; CoPP; ARE; CO-RMs; TNF-α; Heme metabolism; Keap-1; tBH; Small molecule activators; DHC; BVR; SnPPIX; sulforaphane; carbon monoxide-releasing molecules; small hairpin RNA; delta-aminolevulinate synthase 1; antioxidant responsive element; cobalt protoporphyrin IX; heme oxygenase-1; lipopolysaccharide; carnosol; interferon-γ; isoliquiritigenin; carnosic acid; Kelch-like ECH-associated protein-1; tumor necrosis factor alpha; 2,2-dihydroxychalcone; supercurcumin; hemin; tert-butyl hydroquinone; biliverdin reductase; HF-E2 p45-related factor 2; prostglandin E2; tin protoporphyrin IX; dimethyl fumarate; heme metabolism; small molecule activators; inflammation
• ISSN: 1043-6618; 1096-1186
• DOI: 10.1016/j.phrs.2013.07.010

The nuclear factor erythroid derived 2-related factor 2 (Nrf2) and the antioxidant protein heme oxygenase-1 (HO-1) are crucial components of the cellular stress response. These two systems work together to combat oxidative stress and inflammation and are attractive drug targets for counteracting different pathologies, including neuroinflammation. We aimed to identify the most effective Nrf2/HO-1 activators that modulate the inflammatory response in microglia cells. In the present study, we searched the literature and selected 56 compounds reported to activate Nrf2 or HO-1 and analyzed them for HO-1 induction at 6 and 24h and cytotoxicity in BV2 microglial cells in vitro. Approximately 20 compounds up-regulated HO-1 at the concentrations tested (5–20μM) with carnosol, supercurcumin, cobalt protoporphyrin-IX and dimethyl fumarate exhibiting the best induction/low cytotoxicity profile. Up-regulation of HO-1 by some compounds resulted in increased cellular bilirubin levels but did not augment the expression of proteins involved in heme synthesis (ALAS 1) or biliverdin reductase. Bilirubin production by HO-1 inducers correlated with their potency in inhibiting nitrite production after challenge with interferon-γ (INF-γ) or lipopolysaccharide (LPS). The compounds down-regulated the inflammatory response (TNF-α, PGE2 and nitrite) more strongly in cells challenged with INF-γ than LPS, and silencing HO-1 or Nrf2 with shRNA differentially affected the levels of inflammatory markers. These findings indicate that some small activators of Nrf2/HO-1 are effective modulators of microglia inflammation and highlight the chemical scaffolds that can serve for the synthesis of potent new derivatives to counteract neuroinflammation and neurodegeneration.