The Acidic Fraction of Isatidis Radix Regulates Inflammatory Response in LPS-Stimulated RAW264.7 Macrophages through MAPKs and NF-κB Pathway

Abstract

Isatidis Radix, the dried root of Isatidis indigotica Fort, is a traditional heat-clearing and detoxicating herb, which has the antiviral and anti-inflammatory activity and immune regulation. It has been widely used to treat cold, fever, sore throat, mumps, and tonsillitis in clinics. A previous study demonstrated that the acidic fraction of Isatidis Radix (RIAF) had strong anti-inflammatory activity, but the mechanism of action was not well elucidated. Lipopolysaccharide- (LPS-) induced RAW264.7 cells were employed to observe the anti-inflammatory activity of RIAF. The level of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), nitric oxide (NO), prostaglandin E2 (PGE2), and interleukin-6 (IL-6) was determined by enzyme-linked immunosorbent assay kits. Western blot was performed to quantify the expression of extracellular signal-regulated kinase (ERK) 1/2, c-jun NH2-termianl kinase (JNK), p38, inducible NO synthetase (iNOS), cyclooxygenase (COX)-2, andnuclear factor-κB (NF-κB). Immunofluorescence assay and electrophoretic mobility shift assay (EMSA) were used to quantify the translocation and the binding-DNA activity of NF-κB. RIAF could inhibit the secretion of inflammatory cytokines (PGE2, IL-6, IL-1β, and NO, other than TNF-α) in a dose-dependent manner. Further investigation showed that the expression of iNOS and COX-2 induced by LPS were downregulated by treatment with RIAF. Meanwhile, data from the signal pathway exhibited that RIAF significantly suppressed the phosphorylation of ERK1/2, JNK, and p38 and reduced the translocation of NF-κB from the cytoplasm to nucleus, as well as the binding-DNA activity. The anti-inflammatory mechanism of action of RIAF was to reduce inflammation-associated gene expression (iNOS, COX-2, IL-1β, IL-6) by regulating the phosphorylation of the mitogen-activated protein kinases (MAPK) pathway and interventing the activation of the NF-κB pathway, which partly illustrated the basis of treatment of Isatidis Radix on cold, fever, sore throat, mumps, and tonsillitis in clinics.

ETAS®50 Attenuates SARS-CoV-2 Spike Protein-Induced IL-6 and IL-1β Production by Suppressing p44/42 MAPK and Akt Phosphorylation in Murine Primary Macrophages

“…In addition to NF-κB and JNK signaling, the activation of p44/42 MAPK and Akt signaling was observed to regulate the transcription of pro-inflammatory cytokines in macrophages. Indeed, it has been reported that a wide variety of herbal extracts and herbderived natural compounds exert anti-inflammatory effects on LPS-stimulated macrophage cell lines, such as RAW264.7 and U937, by suppressing either p44/42 MAPK signaling [37][38][39][40] or Akt signaling [41][42][43]. In this regard, we found that ETAS®50 co-treatment More importantly, ETAS®50 did not interfere with the basal phosphorylation of p44/42 MAPK and Akt in murine primary macrophages.…”

Standardized Extract of Asparagus officinalis Stem Attenuates SARS-CoV-2 Spike Protein-Induced IL-6 and IL-1β Production by Suppressing p44/42 MAPK and Akt Phosphorylation in Murine Primary Macrophages

“…In addition to NF-κB and JNK signaling, the activation of p44/42 MAPK and Akt signaling was observed to regulate the transcription of pro-inflammatory cytokines in macrophages. Indeed, it has been reported that a wide variety of herbal extracts and herb-derived natural compounds exert anti-inflammatory effects on LPS-stimulated macrophage cell lines, such as RAW264.7 and U937, by suppressing either p44/42 MAPK signaling [ 35 , 36 , 37 , 38 ] or Akt signaling [ 39 , 40 , 41 ]. In this regard, we found that EAS co-treatment suppressed S1-induced phosphorylation of p44/42 MAPK and Akt after 6 h of culture without affecting the degradation of IκBα degradation and nuclear translocation of NF-κB p65 subunit.…”

Inhibitory effect of Isatis tinctoria L. water extract on DNCB-induced atopic dermatitis in BALB/c mice and HaCaT cells

“…Isatis tinctoria L (PLG), the root of Isatis indigotica Fort, called “Panlamgeun,” has been used in traditional Chinese medicine for thousands of years to treat acute and chronic infections, various respiratory infections, and cancer [ 20 , 21 ]. PLG contains many compounds such as indigo, indigotin, indirubin, Epigoitrin, Adenosine, and L-Arginine [ 21 – 24 ].…”

“…Recently, nucleosides have been shown to be bioactive compounds associated with immunomodulatory, antiviral, and anti-inflammatory diseases [ 29 – 31 ]. In a previous study, PLG showed a pharmacological effect of inhibiting the activity of iNOS and COX-2, by suppressing the expression of the MAPK/NF-κB pathway in LPS-induced Raw264.7 cells [ 20 ]. PLG is known to be effective against inflammation, but the effect on anti-atopic skin inflammation has not yet been confirmed.…”