The present study aimed to investigate the protective effects and underlying mechanisms of baicalin on imprinting control region mice infected with influenza A/FM/1/47 (H1N1) virus. Oral administration of baicalin into mice infected with H1N1 prevented death, increased the mean time to death and inhibited lung index and lung consolidation. Subsequently, fluorescence quantitative polymerase chain reaction was used to assess the mRNA expression of toll-like receptor 7 (TLR7) and myeloid differentiation primary response gene 88 (MYD88), and western blot analysis was used to determine the expression of phosphorylated nuclear factor κB (NF-κB)-P65 and c-jun/activator protein 1 (AP-1). An enzyme-linked immunosorbent assay was applied to test for the inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-1β and IL-6, in the lung tissue. The findings indicated that baicalin downregulated the mRNA expression of TLR7 and MYD88, significantly downregulated the protein expression of NF-κB-P65 and AP-1 and also inhibited the secretion of TNF-α, IL-1β and IL-6. In conclusion, baicalin effectively reduced the pathological damage and inflammation of the lungs by downregulating the TLR7/MYD88-mediated signaling pathway.

Baicalin is a flavonoid isolated from the root of Scutellaria baicalensis with anti-inflammatory, antioxidant and antiapoptotic pharmacological properties. However, the therapeutic effect of baicalin on rheumatoid arthritis (RA) is not completely understood. The present study aimed to explore the therapeutic potential and mechanisms underlying baicalin in collagen-induced arthritis (CIA) model rats. CIA was induced in male SD rats. The hind paw thickness and severity of joint injury were monitored to assess the onset of arthritis. At 28 days after the initial immunization, different doses of baicalin were administered once daily via oral gavage for 40 days. The radiologic and pathological alterations were examined using X-ray, and hematoxylin and eosin staining, respectively. ELISA was employed to measure the serum levels of proinflammatory cytokines. Reverse transcription-quantitative PCR and western blotting were conducted to determine the expression of toll-like receptor (TLR)2, myeloid differentiation factor 88 (MYD88) and NF-κB p65. Baicalin treatment noticeably alleviated radiographic and histologic abnormalities in the hind paw joints of CIA model rats in a dose-dependent manner. The serum levels of proinflammatory cytokines were significantly decreased in baicalin-treated CIA model rats compared with vehicle-treated CIA model rats. The mRNA expression levels of TLR2 and MYD88, as well as the protein expression levels of TLR2, MYD88 and NF-κB p65 were significantly decreased by baicalin treatment in the synovial tissue of CIA model rats and human RA fibroblast-like synoviocytes. The results suggested that baicalin may exert a beneficial effect on CIA, which may be mediated by inhibiting the TLR2/MYD88/NF-κB signaling pathway.

Abstract. This study was conducted to investigate the effects of quercetin on the expression of cyclin-dependent kinase (CDK4) mRNA and protein in A549 lung epithelial tumor cells infected by H1N1. First, the Thiazolyl Blue Tetrazolium Bromide (MTT) method was used to determine H1N1 virulence, quercetin cytotoxicity and inhibition of the cytopathic effect of H1N1 on A549 cells by quercetin. Subsequently, 100 TCID 50 H1N1 was used to infect A549 cells for 2 h prior to culture in maintenance media containing 10 mg̸l quercetin. After 4, 12, 24 and 48 h of culture, the cells were collected and total RNA and protein were extracted. Fluorescent quantitative polymerase chain reaction and western blot analysis were then performed to assess the expression of CDK4 mRNA and protein. The experiment demonstrated that the TCID 50 of H1N1 in A549 cells was 10 -4.75 , the maximum non-toxic concentration of quercetin in A549 cells was 30-60 mg̸l and the minimum effective concentration of quercetin for the inhibition of the H1N1 cytopathic effect on A549 cells was 10 mg/l. The results indicated that quercetin may significantly inhibit CDK4 mRNA and protein overexpression caused by H1N1 within 4-48 h. In conclusion, quercetin may protect against H1N1 infection by effectively reducing the mRNA and protein expression of CDK4 caused by H1N1 infection.

Lysyl oxidase (LOX) serves an important role in remodeling the extracellular matrix and angiogenesis in various types of cancer; however, whether LOX is involved in the pathogenesis of rheumatoid arthritis remains unknown. In order to investigate this in the present study, β-aminopropionitrile, an inhibitor of LOX, was injected intraperitoneally into rats with type II collagen-induced arthritis (CIA). Subsequently, synovial hyperplasia was examined by hematoxyl in and eosin staining, and the microvascular density (MVD) and expression levels of LOX, matrix metalloproteinase (MMP)-2 and MMP-9 in the synovial membrane and fluid were determined by immunohistochemistry and ELISA, respectively. The enzyme activity of LOX was evaluated by the Amplex Red Hydrogen Peroxide method. The results demonstrated an increased amount of rough synovial membranes, higher MVD in these membranes and more synovial cell layers in CIA rats compared with in the control rats. In addition, higher enzymatic activity of LOX and higher expression levels of MMP-2 and MMP-9 were revealed in CIA rats compared with in the control rats. Notably, β-aminopropionitrile inhibited paw swelling and the decreased the arthritis index, the MVD in the synovial membranes and the expression levels of MMP-2 and MMP-9. Furthermore, the expression level of LOX in the synovial membranes was positively associated with the MVD and the expression levels of MMP-2 and MMP-9, suggesting that LOX promotes synovial hyperplasia and angiogenesis and that LOX may be a potential therapeutic target for rheumatoid arthritis.

No abstract