Emodin suppresses LPS-induced inflammation in RAW264.7 cells through a PPARγ-dependent pathway.

Inflammation is a defense and protective response to multiple harmful stimuli. Over and uncontrolled inflammation can lead to local tissues or even systemic damages and injuries. Actually, uncontrolled and self-amplified inflammation is the fundament of the pathogenesis of a variety of inflammatory diseases, including sepsis shock, acute lung injury and acute respiratory distress syndrome (ALI/ARDS). Our recent study showed that emodin, the main active component of Radix rhizoma Rhei, could significantly ameliorate LPS-induced ALI/ARDS in mice. However, its underlying signal pathway was not still very clear. Then, the aim of current study was to explore whether emodin could attenuate LPS-induced inflammation in RAW264.7 cells, and its involved potential mechanism. The mRNA and protein expression of ICAM-1, MCP-1 and PPARγ were measured by qRCR and western blotting, the production of TNF-α was evaluated by ELISA. Then, the phosphorylation of NF-κB p65 was also detected by western blotting. And NF-κB p65 DNA binding activity was analyzed by ELISA as well. Meanwhile, siRNA-PPARγ transfection was performed to knockdown PPARγ expression in cells. Our data revealed that LPS-induced the up-regulation of ICAM-1, MCP-1 and TNF-α, LPS-induced the down-regulation of PPARγ, and LPS-enhanced NF-κB p65 activation and DNA binding activity were substantially suppressed by emdoin in RAW264.7 cells. Furthermore, our data also figured out that these effects of emdoin were largely abrogated by siRNA-PPARγ transfection. Taken together, our results indicated that LPS-induced inflammation were potently compromised by emodin very likely through the PPARγ-dependent inactivation of NF-κB in RAW264.7 cells.

Matrine suppresses expression of adhesion molecules and chemokines as a mechanism underlying its therapeutic effect in CNS autoimmunity.

Experimental autoimmune encephalomyelitis (EAE) is a classical experimental model of multiple sclerosis (MS), an autoimmune disease of the central nervous system (CNS). Previous reports have suggested that matrine (MAT), a quinolizidine alkaloid derived from the herb Radix Sophorae Flave, could inhibit clinical EAE, but its mechanism of action is not clear. Our present study showed that MAT treatment resulted in dose-dependent reduction in neurological scores. Consistent with this observation, infiltration of inflammatory cells and demyelination in the CNS were also significantly suppressed. We further studied the mechanism underlying these effects of MAT by determining whether this treatment influences expression of molecules that are involved in the activation and migration of inflammatory cells. Our results showed that MAT significantly inhibited expression and production in the CNS of ICAM-1 and VCAM-1, key adhesive molecules, and CCL3 and CCL5, key chemokines, that attract inflammatory cells into the CNS. Furthermore, the TLR4/MD2 pathway, which plays an important role in the induction of Th1/Th17 cells in EAE, was also significantly inhibited. Together, our study not only demonstrates that MAT may be a novel therapeutic option for the treatment for MS, but also provides further information on mechanisms underlying the effect of MAT treatment.

Targeting CpG DNA to screen and isolate anti-sepsis fraction and monomers from traditional Chinese herbs using affinity biosensor technology.

Bacterial DNA/CpG DNA is recognized as a key molecule during the pathogenesis of sepsis. Therefore, preventing CpG DNA from binding to its receptor is considered as the most promising strategy. In the present experiments, Radix et Rhizoma Rhei had the highest CpG DNA-binding ability among the seventy-eight traditional Chinese herbs. After the isolation of silica gel chromatography and high performance liquid chromatography (HPLC) and evaluation with affinity biosensor, the active fraction was confirmed and named Fraction D. It was found that in vitro, Fraction D bound to both CpG DNA and lipid A with high affinity, and strongly inhibited LPS- and CpG DNA-induced TNF-alpha release from RAW264.7 cells in a dose-dependent manner. Furthermore, Fraction D reduced the expression of TLR9 mRNA up-regulated by CpG DNA. In vivo, Fraction D protected mice challenged with lethal heat-killed E. coli. Using HPLC method, two monomers with high affinity for CpG DNA were isolated and identified as rhein and emodin. Rhein could significantly reduce CpG DNA- and LPS-induced TNF-alpha release, but emodin only reduced CpG DNA-induced TNF-alpha release. Rhein in combination with emodin could play synergistic inhibitory effect on both CpG DNA and LPS-induced TNF-alpha release, which contributed to the bioactivity of Fraction D. In conclusion, we successfully established the platform to screen anti-CpG DNA components of traditional Chinese herbs using affinity biosensor technology, got active Fraction D from Radix et Rhizoma Rhei and determined rhein and emodin as the main bioactive ingredients in Fraction D.