A Polyphenol‐rich Pomegranate Fruit Extract Suppresses NF‐κB and IL‐6 Expression by Blocking the Activation of IKKβ and NIK in Primary Human Chondrocytes

Abstract

Pomegranate fruit extract (PE) rich in polyphenols have been shown to exert chondroprotective effects but the mechanism is not established. Here, we used an in vitro model of inflammation in OA to investigate the potential of PE to suppress IL-1β-stimulatedexpression of inflammatory cytokine IL-6, generation of reactive oxygen species (ROS) levels and investigated the mechanism of NF-κB inhibition by analyzing the activation of the kinases upstream of IκBα in primary human chondrocytes. Total and phosphorylated forms of kinases, and expression of IL-6 were determined at protein and mRNA levels by Western immunoblotting and Taqman assay respectively. DHR-123 staining estimated ROS generation. PE inhibited the mRNA and protein expression of IL-6, generation of ROS and inhibited the IL-1β-mediated phosphorylation of IKKβ, expression of IKKβ mRNA, degradation of IκBα, and activation and nuclear translocation of NF-κB/p65 in human chondrocytes. Importantly, phosphorylation of NF-κB-inducing kinase (NIK) was blocked by PE in IL-1β-treated human OA chondrocytes. Taken together, these data suggest that PE exerts the chondroprotective effect(s) by suppressing the production of IL-6 and ROS levels. Inhibition of NF-κB activation by PE was blocked via modulation of activation of upstream kinases in human OA chondrocytes.

Derivation of notochordal cells from human embryonic stem cells reveals unique regulatory networks by single cell‐transcriptomics

“…Efficiency of notochordal differentiation was analyzed by determining the percent positive cell population for the notochordal markers. Twenty thousand cells in each group were acquired using BD‐fluorescence‐activated cell sorting (FACS) Aria II (BD Biosciences) and data were analyzed using FlowJo software from Tree Star, Inc. (Ashland, OR) as described previously (Haseeb, Khan, Ashruf, & Haqqi, ; Khan, Ahmad, Ansari, & Haqqi, ).…”

“…(Ashland, OR) as described previously (Haseeb, Khan, Ashruf, & Haqqi, 2017;Khan, Ahmad, Ansari, & Haqqi, 2017).…”

Over-expression of nuclear factor-κB family genes and inflammatory molecules is related to chronic obstructive pulmonary disease

“…When the NF-κB signaling pathway is blocked, the expression of TNF-α and IL-6 is downregulated. 14 , 15 …”

Punica granatum L. Leaf Extract Attenuates Lung Inflammation in Mice with Acute Lung Injury

“…In this context, we recently demonstrated that the leaf hydroalcoholic extract obtained from pomegranate is anti-inflammatory as it inhibits TNF- α production and decreases neutrophil migration in a rat model of lipopolysaccharide- (LPS-) induced acute peritonitis [ 8 ]. Furthermore, Haseeb et al showed that the pomegranate fruit extract attenuates IL-6 production, reactive oxygen species, IL-1 β -mediated phosphorylation of the inhibitor of nuclear factor kappa-B kinase subunit beta (IKK β ), expression of IKK β mRNA, degradation of I κ B α , and the activation and nuclear translocation of NF- κ B/p65 in human chondrocytes [ 9 ].…”