PDK1 in NF-κB signaling is a target of Xanthium strumarium methanolic extract-mediated anti-inflammatory activities.
BACKGROUND
Xanthium strumarium L. (Asteraceae) has traditionally been used to treat bacterial infections, nasal sinusitis, urticaria, arthritis, chronic bronchitis and rhinitis, allergic rhinitis, edema, lumbago, and other ailments. However, the molecular mechanisms by which this plant exerts its anti-inflammatory effects are poorly characterized. Here we studied the immunopharmacological activities of the methanolic extract of the aerial parts of this plant (Xs-ME) and validated its pharmacological targets.


METHODS
To evaluate the anti-inflammatory activity of Xs-ME, we employed lipopolysaccharide (LPS)-treated macrophages and an HCl/EtOH-induced mouse model of gastritis. We also used HPLC to identify the potentially active anti-inflammatory components of this extract. The molecular mechanisms of its anti-inflammatory activity were studied by kinase assays, reporter gene assays, immunoprecipitation analysis, and overexpression of target enzymes.


RESULTS
The production of nitric oxide (NO) and prostaglandin E2 (PGE2) were both suppressed by Xs-ME. Moreover, orally administered Xs-ME ameliorated HCl/EtOH-induced gastric lesions. Furthermore, this extract downregulated the expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 and reduced the nuclear levels of NF-κB. Signaling events upstream of NF-κB translocation, such as phosphorylation of AKT and the formation of PDK1-AKT signaling complexes, were also inhibited by Xs-ME. Moreover, Xs-ME suppressed the enzymatic activity of PDK1. Additionally, PDK1-induced luciferase activity and Akt phosphorylation were both inhibited by Xs-ME. We also identified the polyphenol resveratrol as a likely active anti-inflammatory component in Xs-ME that targets PDK1.


CONCLUSIONS
Xs-ME exerts anti-inflammatory activity in vitro and in vivo by inhibiting PDK1 kinase activity and blocking signaling to its downstream transcription factor, NF-κB.
Department of Genetic Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea; Department of Animal Science, Patuakhali Science and Technology University, Dumki, Patuakhali 8602, Bangladesh.
Muhammad Jahangir
MJ
Hossen
Department of Genetic Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Jae Youl
JY
Cho
Laboratory of Bio-informatics, Department of Multimedia Engineering, Dankook University, Republic of Korea. Electronic address: dr_dwkim@dankook.ac.kr.
Daewon
D
Kim
D064413:3-Phosphoinositide-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000302:isolation & purification / Q000494:pharmacology*; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D000431:Ethanol; D005756:Gastritis / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics / Q000517:prevention & control*; D057809:HEK293 Cells; D006801:Humans; D006851:Hydrochloric Acid; D018836:Inflammation Mediators / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D000432:Methanol / Q000737:chemistry*; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D010766:Phosphorylation; D008517:Phytotherapy; D035261:Plant Components, Aerial / Q000737:chemistry; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D010946:Plants, Medicinal; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D000067996:RAW 264.7 Cells; D015398:Signal Transduction / Q000187:drug effects*; D012997:Solvents / Q000737:chemistry*; D013997:Time Factors; D014162:Transfection; D031210:Xanthium / Q000737:chemistry*
D000893:Anti-Inflammatory Agents; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010936:Plant Extracts; D047428:Protein Kinase Inhibitors; D012997:Solvents; D009569:Nitric Oxide; D000431:Ethanol; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D064413:3-Phosphoinositide-Dependent Protein Kinases; C578564:Pdpk1 protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D015232:Dinoprostone; D006851:Hydrochloric Acid; D000432:Methanol
3-phosphoinositide-dependent kinase 1 (pdk1); Anti-inflammatory effect; Asteraceae; Nuclear factor-kappaB; Prostaglandin E(2); Resveratrol; Xanthium strumarium