Polydatin ameliorates Staphylococcus aureus-induced mastitis in mice via inhibiting TLR2-mediated activation of the p38 MAPK/NF-κB pathway.

Recent studies show that Polydatin (PD) extracted from the roots of Polygonum cuspidatum Sieb, a widely used traditional Chinese remedies, possesses anti-inflammatory activity in several experimental models. In this study, we investigated the anti-inflammatory effects of PD on Staphylococcus aureus-induced mastitis in mice and elucidated the potential mechanisms. In mice with S aureus-induced mastitis, administration of PD (15, 30, 45 mg/kg, ip) or dexamethasone (Dex, 5 mg/kg, ip) significantly suppressed the infiltration of inflammatory cells, ameliorated the mammary structural damage, and inhibited the activity of myeloperoxidase, a biomarker of neutrophils accumulation. Furthermore, PD treatment dose-dependently decreased the levels of TNF-α, IL-1ß, IL-6 and IL-8 in the mammary gland tissues. PD treatment also dose-dependently decreased the expression of TLR2, MyD88, IRAK1, IRAK4 and TRAF6 as well as the phosphorylation of TAK1, MKK3/6, p38 MAPK, IκB-α and NF-κB in the mammary gland tissues. In mouse mammary epithelial cells (mMECs) infected by S aureus in vitro, pretreatment with PD dose-dependently suppressed the upregulated pro-inflammatory cytokines and signaling proteins, and the nuclear translocation of NF-κB p65 and AP-1. A TLR2-neutralizing antibody mimicked PD in its suppression on S aureus-induced upregulation of MyD88, p-p38 and p-p65 levels in mMECs. PD (50, 100 µg/mL) affected neither the growth of S aureus in vitro, nor the viability of mMECs. In conclusion, PD does not exhibit antibacterial activity against S aureus, its therapeutic effects in mouse S aureus-induced mastitis depend on its ability to down-regulate pro-inflammatory cytokine levels via inhibiting TLR2-mediated activation of the p38 MAPK/NF-κB signaling pathway.

Cloning and expression profiling of the VLDLR gene associated with egg performance in duck (Anas platyrhynchos).

BACKGROUND: The very low density lipoprotein receptor gene (VLDLR), a member of the low density lipoprotein receptor (LDLR) gene family, plays a crucial role in the synthesis of yolk protein precursors in oviparous species. Differential splicing of this gene has been reported in human, rabbit and rat. In chicken, studies showed that the VLDLR protein on the oocyte surface mediates the uptake of yolk protein precursors into growing oocytes. However, information on the VLDLR gene in duck is still scarce. METHODS: Full-length duck VLDLR cDNA was obtained by comparative cloning and rapid amplification of cDNA ends (RACE). Tissue expression patterns were analysed by semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR). Association between the different genotypes and egg performance traits was investigated with the general linear model (GLM) procedure of the SAS® software package. RESULTS: In duck, two VLDLR transcripts were identified, one transcript (variant-a) containing an O-linked sugar domain and the other (variant-b) not containing this sugar domain. These transcripts share ~70 to 90% identity with their counterparts in other species. A phylogenetic tree based on amino acid sequences showed that duck VLDLR proteins were closely related with those of chicken and zebra finch. The two duck VLDLR transcripts are differentially expressed i.e. VLDLR-a is mainly expressed in muscle tissue and VLDLR-b in reproductive organs. We have localized the duck VLDLR gene on chromosome Z. An association analysis using two completely linked SNP sites (T/C at position 2025 bp of the ORF and G/A in intron 13) and records from two generations demonstrated that the duck VLDLR gene was significantly associated with egg production (P < 0.01), age of first egg (P < 0.01) and body weight of first egg (P < 0.05). CONCLUSIONS: Duck and chicken VLDLR genes probably perform similar function in the development of growing oocytes and deposition of yolk lipoprotein. Therefore, VLDLR could be a candidate gene for duck egg performance and be used as a genetic marker to improve egg performance in ducks.

[Expression of cyclin-dependent kinase 2-associated protein 1 in chicken embryos of different sexes].

To investigate the expression and functions of cyclin-dependent kinase 2-associated protein 1 (cdk2ap1) screened by suppression subtractive hybridization in chicken embryo development, a pair of primers was designed to amplify the cdk2ap1 fragment by RT-PCR and subsequently the fragment obtained was cloned into the plasmid pGEM-T. Sense and antisense probes labeled with digoxigenin were generated using SP6 and T7 RNA polymerases, respectively, and used to examine cdk2ap1 expression in chicken embryos of both sexes by whole-mount in situ hybridization. In both sexes, cdk2ap1 was expressed in the head mesenchyme, rhombencephalon, optic vesicles, spinal neural tube, and forelimb of 4.0-day-old embryos and the expression in males was significantly higher than that in females. In addition, in the genital ridge and hindlimb of the 4.0-day-old chicken embryo, cdk2ap1 was obviously expressed in the males but not in females. It is supposed that cdk2ap1 may play a role in the sexual differentiation and development of gonad of chicken embryo.