IFN-τ inhibits S. aureus-induced inflammation by suppressing the activation of NF-κB and MAPKs in RAW 264.7 cells and mice with pneumonia

Interferon-tau protects bovine endometrial epithelial cells against inflammatory injury by regulating the PI3K/AKT/β-catenin/FoxO1 signaling axis

Endometritis is one of the most common causes of infertility in dairy cows, and is histopathologically characterized by inflammation and damage of endometrial epithelium. Interferon-tau (IFN-τ) is a novel type I interferon secreted by ruminant trophoblast cells with low cytotoxicity even at high doses. Previous studies suggested that IFN-τ plays an important role in inflammation. However, the mechanisms whereby IFN-τ may modulate the inflammatory responses in the bovine endometrium are unknown. In the present study, primary bovine endometrial epithelial cells (BEEC) isolated from fresh and healthy uterine horns were used for in vitro studies. The integrity of BEEC was assessed by immunofluorescence staining for cytokeratin 18 (CK-18, a known epithelial marker). For the experiments, BEEC were stimulated with different concentrations of lipopolysaccharide (LPS; 0-20 µg/mL) for different times (0-24 h). Cell viability and apoptosis were assessed via CCK-8 and flow cytometry. In a preliminary study, we observed that compared with the control group without LPS, 10 µg/mL of LPS stimulation for 24 h induced apoptosis. In a subsequent study, 20 or 40 ng/mL of IFN-τ alleviated LPS-induced apoptosis. Relative to the LPS group, western blotting further revealed that IFN-τ inhibited the protein abundance of TLR4 and phosphorylated (p-) p65 (p-p65) and Bax/Bcl-2 ratio, suggesting that IFN-τ can protect BEEC against inflammatory injury. Furthermore, the protein abundance of p-phosphoinositide 3-kinase (p-PI3K), p-protein kinase B (p-AKT), p-glycogen synthase kinase-3β (p-GSK3β), β-catenin, and p-forkhead box O1 (p-FoxO1) was lower in the LPS group, whereas IFN-τ upregulated their abundance. The use of LY294002, a specific inhibitor of PI3K/AKT, attenuated the upregulation of p-PI3K, p-AKT p-GSK3β, β-catenin, and p-FoxO1 induced by IFN-τ, and also blocked the downregulation of TLR4, p-p65, and Bax/Bcl-2 ratio. This suggested that the inhibition of TLR4 signaling by IFN-τ was mediated by the PI3K/AKT pathway. Furthermore, compared with the LPS group, the β-catenin agonist SB216763 led to greater p-FoxO1 and lower p-p65 and cell apoptosis. In contrast, knockdown of β-catenin using small interfering RNA had the opposite effects. To explore the role of FoxO1 on the inhibition of TLR4 by IFN-τ, we employed LY294002 to inhibit the PI3K/AKT while FoxO1 was knocked down. Results revealed that the knockdown of FoxO1 blocked the upregulation of TLR4 and p-p65 induced by LY294002, and enhanced the inhibition of IFN-τ on TLR4, p-p65, and cell apoptosis. Overall, these findings confirmed that IFN-τ can protect endometrial epithelial cells against inflammatory injury via suppressing TLR4 activation through the regulation of the PI3K/AKT/β-catenin/FoxO1 axis. These represent new insights into the molecular mechanisms underlying the anti-inflammatory function of IFN-τ in BEEC, and also provide a theoretical basis for further studies on the in vivo application of IFN-τ to help prevent negative effects of endometritis.

Uterine Tissue Metabonomics Combined with 16S rRNA Gene Sequencing To Analyze the Changes of Gut Microbiota in Mice with Endometritis and the Intervention Effect of Tau Interferon

Endometritis is a common cow disease characterized by inflammation of endometrium, which leads to infertility or low fertility of cows and brings huge economic losses to the dairy industry. Tau interferon (IFN-τ) has many important biological functions, including an anti-inflammatory effect. The present study aimed to survey the effects of IFN-τ administration on gut microflora and body metabolism in mice with endometritis and to explore the potential relationship. The results indicated that IFN-τ obviously alleviated the damage and ultrastructural changes of mouse endometrium induced by Escherichia coli and enhanced tight junction protein's expression level. Through analysis by 16S rRNA gene sequencing, we found that IFN-τ, especially at 12 h, could regulate the composition of gut microbiota associated with Pediococcus, Staphylococcus, and Enterorhabdus in E. coli-induced mouse endometritis. Through histometabonomics, it was found that endometritis was related to 11 different metabolites and 4 potential metabolic pathways. These metabolites and metabolic pathways were major participants in metabolic pathways, cysteine and methionine metabolism, arachidonic acid metabolism, and pyrimidine metabolism. Correlation analysis of gut microbiota with uterine tissue metabolomics showed that changes in metabolic pathways might be affected by gut microbiota, such as Enterorhabdus in mouse endometritis. The above results indicated that the anti-inflammatory mechanism of IFN-τ might be reduction of the abundance of Enterorhabdus in the gut microbiota, affecting the expression level of important metabolites in uterine tissue and thus playing an anti-inflammatory role. IMPORTANCE The change in intestinal flora has been the focus of many disease studies in recent years, but the pathogenetic effect of interferon on endometritis is still unclear. The results of this study showed that IFN-τ alleviated the damage in mouse endometritis induced by E. coli and improved the endometrial tissue barrier. Its functional mechanism may be reduction of the abundance of Enterorhabdus in the intestinal microbiota, affecting the expression level of important metabolites in uterine tissue and thus playing an anti-inflammatory role.

NEK7-Mediated Activation of NLRP3 Inflammasome Is Coordinated by Potassium Efflux/Syk/JNK Signaling During Staphylococcus aureus Infection

Staphylococcus aureus (S. aureus) is a foodborne pathogen that causes severe diseases, such as endocarditis, sepsis, and bacteremia. As an important component of innate immune system, the NLR family pyrin domain-containing 3 (NLRP3) inflammasome plays a critical role in defense against pathogen infection. However, the cellular mechanism of NLRP3 inflammasome activation during S. aureus infection remains unknown. In the present study, we found that spleen tyrosine kinase (Syk) and c-Jun N-terminal kinase (JNK) were rapidly phosphorylated during S. aureus infection. Moreover, a Syk/JNK inhibitor and Syk/JNK siRNA not only reduced NLRP3 inflammasome-associated molecule expression at the protein and mRNA levels, apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC) speck formation, and interleukin-1β (IL-1β), and IL-18 release but also rescued the decreased NIMA-related kinase 7 (NEK7) expression level following suppression of the NEK7-NLRP3 interaction in macrophages. Interestingly, Syk/JNK phosphorylation levels and NLRP3 inflammasome-associated molecule expression were decreased by blockade of K⁺ efflux. Furthermore, activation of the NLRP3 inflammasome and a lower NEK7 protein level were found in vivo upon S. aureus infection. Taken together, our data indicated that S. aureus infection induces a K⁺ efflux/Syk/JNK/NEK7-NLRP3 signaling pathway and the subsequent activation of the NLRP3 inflammasome for the release of proinflammatory cytokines. This study expands our understanding of the basic molecular mechanism regulating inflammation and provides potential value for anti-infective drug development against S. aureus infection.

Temporal changes in the corpus luteum during early pregnancy reveal regulation of pathways that enhance steroidogenesis and suppress luteolytic mechanisms†

Although rescue of the corpus luteum (CL) is required for pregnancy, luteal function during maternal recognition of pregnancy remains largely unexplored. CL were collected from pregnant cattle on days 14, 17, 20, and 23, to encompass the maternal recognition of pregnancy period. Next-generation sequencing was used to profile mRNA abundance during this time, while tandem mass spectrometry and nanostring technology were used to profile proteins and miRNA, respectively. A total of 1157 mRNA were differentially abundant, while 27 miRNA changed, and 29 proteins tended to change. mRNA that increased were regulators of interferon signaling and DNA repair, while those that decreased were associated with luteolytic processes, such as calcium signaling and matrix metallopeptidase (MMP) signaling, indicating inhibition of these processes. One of these, MMP12, was regulated by prostaglandin F2A in vitro. mRNA that were maximally abundant on day 20 were primarily associated with immune processes. Two of these, C-C motif chemokine ligand 1 and NFKB inhibitor alpha, were regulated by interferon tau in vitro. MiRNA that increased were predicted to inhibit phosphatidylinositol signaling, while those that decreased may be negative regulators of steroidogenesis. One protein that was greater on day 20 than on day 14 was aldehyde dehydrogenase 1 family member A1 (ALDH1A1), which synthesizes retinoic acid. Pharmacological inhibition of this enzyme, or of retinoic acid receptor signaling, led to suppression of progesterone production in vitro. Overall, these data indicate that there are changes in the CL of pregnancy that are important for continued luteal function.

Diphenyl pyrimidine exhibits protective effect on Staphylococcus aureus pneumonia in rat model by targeting NLRP3 expression

Pneumonia is one of the most frequent disorder induced by S. aureus infection and accounts for 13.3% of the all the infections caused by staphylococcus. In the present study effect of diphenyl pyrimidine was investigated against Staphylococcus aureus (S. aureus) induced pneumonia in the rat model. The results demonstrated that diphenyl pyrimidine treatment of the rats effectively prevented S. aureus induced increase in mortality in dose-dependent manner. Diphenyl pyrimidine treatment inhibited histopathological changes in S. aureus infected rat lungs. Treatment of the rats with 1.25, 2.5, 5 and 10 mg/kg doses of diphenyl pyrimidine significantly (P < 0.05) reversed S. aureus infection induced increase in interleukin (IL)-1β, IL-18 and tumor necrosis factor (TNF)-α levels. Treatment with 1.25, 2.5, 5 and 10 mg/kg doses of diphenyl pyrimidine significantly (P < 0.05) reversed S. aureus infection induced increase nucleotide-binding domain and leucine-rich repeat containing (NLR) protein (NLRP3), apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) and caspase-1 protein expression in rat lungs in dose-dependent manner. The NLRP3, ASC and caspase-1 mRNA level in S. aureus infected rat pulmonary tissues was significantly (P < 0.05) reduced by diphenyl pyrimidine treatment in dose-dependent manner. Thus, diphenyl pyrimidine protects S. aureus-induced pneumonia through suppression of NLRP3 and inflammatory cytokine expression. Therefore, diphenyl pyrimidine can be of therapeutic importance for the treatment of S. aureus induced pneumonia.

Isoxanthanol alleviates Staphylococcus aureus induced chronic obstructive pulmonary disease in rat model through promotion of miR-145-5p expression

The present study was aimed to evaluate the isoxanthanol against Staphylococcus aureus chronic obstructive pulmonary disease (COPD) in rat model. The isoxanthanol decreased the parasitic load by almost 99% in the Staphylococcus aureus infected rats. It significantly (P < 0.05) decreased mortality rate of the rats, prevented pulmonary tissue damage and aggregation of inflammatory cytokines. In Staphylococcus aureus infected rats, isoxanthanol treatment inhibited production of interleukin-18, interleukin-1β and TNF-α significantly (P < 0.05) in the BALF and pulmonary tissues. Treatment of the Staphylococcus aureus-infected rats with isoxanthanol inhibited up-regulation of NLRP3, ASC and caspase-1 expression. In Staphylococcus aureus-infected rats the expression of miR-145-5p was remarkably increased on treatment with isoxanthanol. In summary, isoxanthanol prevents Staphylococcus aureus-induced COPD in rats through up-regulation of miR-145-5p and suppression of inflammatory cytokines. Therefore, isoxanthanol can be of therapeutic importance for the treatment of Staphylococcus aureus induced COPD.

Calming Cytokine Storm in Pneumonia by Targeted Delivery of TPCA-1 Using Platelet-Derived Extracellular Vesicles

Pneumonia can cause high morbidity and mortality because of uncontrolled inflammation in the lung tissue. Calming the cytokine storm may be one key to saving the life of patients with severe pneumonia. Here, inspired by the intrinsic affinity of platelets to the site of inflammation, we have engineered platelet-derived extracellular vesicles (PEVs) for pneumonia-targeted drug delivery. It is demonstrated that PEVs that are easily generated from the activated platelets can selectively target pneumonia in the mouse model with acute lung injury (ALI). By loading with [5-(p-fluorophenyl)-2-ureido]thiophene-3-carboxamide (TPCA-1), which can inhibit the production of inflammatory factors, the PEVs significantly improve therapeutic benefits by inhibiting the infiltration of pulmonary inflammatory cells and calming local cytokine storm compared with the free drug-treated group. Furthermore, we find that PEVs could serve as a broad platform that can selectively target various inflammatory sites, including chronic atherosclerotic plaque, rheumatoid arthritis, and wounds associated with skin.

MerTK negatively regulates Staphylococcus aureus induced inflammatory response via Toll-like receptor signaling in the mammary gland

Mastitis is the most commonly diagnosed infectious disease reducing milk yield and quality and is accompanied by mammary tissue damage in both humans and animals. Mastitis incurs welfare and economic costs as well as environmental concerns regarding treatment. Staphylococcus aureus (S. aureus) is a prevalent Gram-positive bacteria and a major cause of mastitis, however, pathogenesis of the intrinsic anti-inflammatory response in mammary tissues is still principally unknown. Our aim, in combatting the S. aureus induced inflammatory response in mammary tissues, was to elucidate the intrinsic anti-inflammatory role of MerTK signaling. Here, we demonstrate that Mer receptor tyrosine kinase (MerTK) regulates an intrinsic negative feedback to balance the over-reaction of the host defense system. S. aureus elicits toll-like receptors 2 and 6 (TLR2/TLR6) signaling pathways, subsequently recruiting TRAF6, whose ubiquitination is intricate to the downstream signaling including MAPKs and NF-κB. We observed that TLR2/TLR6 activation, in response to S. aureus, was concomitant with induced MerTK activation, leading to raised expression of suppressor of cytokine signaling 1 and 3 (SOCS1, SOCS3) in wild type mice mammary tissues and epithelial cells. Meanwhile, S. aureus infection in MerTK-/- mice showed significant increased phosphorylation of p65, IκBα, p38, JNK and ERK along with production of pro-inflammatory cytokines. Moreover, MerTK-/- evidently inhibited S. aureus induced phosphorylation of STAT1 and subsequent SOCS1/SOCS3 expression which are pivotal in the negative feedback mechanism for targeting TRAF6 to inhibit the TLR2/TLR6 mediated immune response. Taken together, our findings demonstrate the importance of MerTK in the regulation of the intrinsic feedback during the inflammatory response induced by S. aureus through STAT1/SOCS1/SOCS3 in mice mammary tissues and mice mammary epithelial cells (MMECs).

Gas6 negatively regulates the Staphylococcus aureus-induced inflammatory response via TLR signaling in the mouse mammary gland

Staphylococcus aureus (S. aureus)-induced mastitis is the most frequent, pathogenic, and prevalent infection of the mammary gland. The ligand growth arrest-specific 6 (Gas6) is a secretory protein that binds to and activates Tyro3, Axl, and MerTK receptors. This study explored the role of Gas6 in S. aureus-induced mastitis. Our results revealed that TLR receptors initiate the innate immune response in mammary gland tissues and epithelial cells and that introducing S. aureus activates TLR2 and TLR6 to drive multiple intracellular mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) pathways. Moreover, S. aureus also induces Gas6, which then activates the TAM receptor kinase pathway, which is related to the inhibition of TLR2- and TLR6-mediated inflammatory pathways through SOCS1 and SOCS3 induction. Gas6 absence alone was found to be involved in the downregulation of TAM receptor-mediated anti-inflammatory effects by inducing significantly prominent expression of TRAF6 and low protein and messenger RNA expression of SOCS1 and SOCS3. S. aureus-induced MAPK and NF-ĸB p65 phosphorylation were also dependent on Gas6, which negatively regulated the production of Pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) in S. aureus-treated mammary tissues and mammary epithelial cells. Our in vivo and in vitro study uncovered the Gas6-mediated negative feedback mechanism, which inhibits TLR2- and TLR6-mediated MAPK and NF-ĸB signaling by activating TAM receptor kinase (MerTK, Axl, and Tyro3) through the induction of SOCS1/SOCS3 proteins.

Baicalin tetrazole acts as anti-pneumocystis carinii pneumonia candidate in immunosuppressed rat model

The present study was aimed to synthesize and evaluate tetrazoles of baicalin against Pneumocystis carinii pneumonia in the rat model. Among the seven synthesized baicalin tetrazoles, one with trifloromethyl group in the aromatic ring was found to be most potent during the initial study. The mechanism of preventive effect of most potent compound 4c against Pneumocystis carinii pneumonia was investigated in detail. The compound 4c decreased the parasitic load by almost 99% in the rats. It significantly (P < 0.05) decreased mortality rate of the rats, prevented pulmonary tissue damage and aggregation of inflammatory cytokines. In Pneumocystis carinii infected rats compound 4c treatment inhibited production of interleukin-18, interleukin-1β and TNF-α significantly (P < 0.05) in the BALF and pulmonary tissues. Treatment of the pneumocystis carinii-infected rats with compound 4c inhibited up-regulation of mRNA expression corresponding NLRP3, ASC and caspase-1. The compound 4c treatment of the pneumocystis carinii-infected rats significantly (P < 0.02) suppressed the level of NLRP3 and ASC proteins. Moreover, the enhancement of caspase-1 activation by pneumocystis carinii-infection in rats was also suppressed by compound 4c. The results from present study demonstrate that compound 4c protects pneumocystis carinii induced pneumonia through suppression of inflammatory cytokines and NLRP3 activation. Therefore, compound 4c can be of therapeutic importance for the treatment of pneumocystis carinii induced pneumonia.

Selenium influences mmu-miR-155 to inhibit inflammation inStaphylococcus aureus-induced mastitis in mice

Mastitis, a major disease affecting dairy cows, is most commonly caused byStaphylococcus aureus(S. aureus).

Protective Effects of Interferon-tau Against Lipopolysaccharide-Induced Embryo Implantation Failure in Pregnant Mice

Interferon-tau (IFN-τ), a novel type I interferon, is produced by trophoblast cells in ruminants. Previous studies have confirmed that IFN-τ could induce immunological tolerance in humans and other species. However, there are few reports on whether IFN-τ has a protective effect on embryo implantation failure caused by excessive inflammation at the maternal-fetal interface. In our study, a mouse model of lipopolysaccharide (LPS)-induced implantation failure was successfully established, and we investigated the protective effects of IFN-τ. First, we showed that IFN-τ increased the number of implanted embryos in LPS-treated pregnant mice. Subsequently, quantitative real-time polymerase chain reaction (qPCR) and ELISA results showed that several inflammatory cytokines [IL-1β and tumor necrosis factor-alpha (TNF-α)] whose expression was upregulated by LPS were reversed by IFN-τ treatment. Furthermore, we performed Western blotting and found that IFN-τ restrained the LPS-induced phosphorylation of IκBα and NF-κB p65. Moreover, qPCR and immunohistochemistry analyses showed that IFN-τ decreased the LPS-induced expression of mouse major histocompatibility complex (MHC) class I genes (H-2K and H-2D) in LPS-treated pregnant mice. Taken together, these results suggest that IFN-τ has a protective effect in LPS-induced implantation failure by downregulating MHC class I genes expression and inhibiting the production of inflammatory cytokines.

Resveratrol alleviates Staphylococcus aureus pneumonia by inhibition of the NLRP3 inflammasome

Staphylococcus aureus (S. aureus) causes a wide variety of infections, including S. aureus pneumonia. Resveratrol, a natural polyphenolic compound contained in several plant species, exerts various activities, including anti-bacterial and pulmonary protective activities. The aim of the present study was to evaluate the protective effect of resveratrol on a murine model of S. aureus pneumonia and to elucidate the underlying mechanisms. It was found that resveratrol significantly reduced S. aureus-induced mortality, ameliorated lung injury and decreased cytokine levels in the bronchoalveolar lavage fluid and lung tissue of S. aureus infected-mice. In addition, reverse-transcription quantitative polymerase chain reaction and western blot assays showed that resveratrol markedly decreased the mRNA and protein expression of nucleotide-binding domain and leucine-rich repeat containing gene family pyrin domain containing 3 protein (NLRP3), apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain and caspase-1. These results demonstrated that resveratrol significantly alleviates S. aureus pneumonia in mice, the possible underlying mechanism of which is associated with the inhibition of the NLRP3 inflammasome. The present study suggested that resveratrol is a potentially useful agent for the treatment of S. aureus pneumonia and S. aureus-induced infectious diseases.

Geniposide attenuates Staphylococcus aureus-induced pneumonia in mice by inhibiting NF-κB activation

Staphylococcus aureus (S. aureus) is a major cause of pneumonia that often affects young and immunocompetent patients. Inflammation plays an important role in the development of S. aureus-induced pneumonia. Geniposide, a major iridoid glucoside component of gardenia fruit, has been reported to have anti-inflammatory and anti-oxidative effects. The purpose of this study was to investigate the protective effects of geniposide on S. aureus-induced pneumonia in mice. Lung histopathological changes were detected by hematoxylin-eosin (H&E) staining. Lung myeloperoxidase (MPO) activity, wet-to-dry (W/D) ratio, and inflammatory cytokine levels in bronchoalveolar lavage fluid (BALF) were measured. The results showed that S. aureus-induced lung histopathological changes were attenuated by geniposide. S. aureus-induced MPO activity and lung W/D ratio were inhibited by treatment of geniposide. Furthermore, the levels of TNF-α and IL-1β in the BALF were also suppressed by geniposide. In addition, geniposide significantly inhibited S. aureus-induced nuclear factor kappa B (NF-κB) activation. Taken together, these results showed that geniposide inhibited S. aureus-induced pneumonia in mice by inhibiting NF-κB signaling pathway. Geniposide might be used as a potential agent for the treatment of S. aureus-induced pneumonia.

Interferon-τ increases BoLA-I for implantation during early pregnancy in dairy cows

Interferon-τ (IFN-τ) signals pregnancy recognition in ruminants. We investigated the effects of IFN-τ produced by embryo trophoblastic cells (ETCs) on expression of bovine leukocyte antigen-I (BoLA-I), a bovine analogue of human MHC-I, in endometrial luminal epithelial cells (EECs) during early pregnancy in dairy cows. Expression of IFN-τ and BoLA-I was increased in endometrial tissues during early pregnancy. Expression of the anti-inflammatory cytokine IL-10 was increased in endometrial tissues, while expression of the pro-inflammatory cytokine IL-6 was decreased, indicating immunosuppression. Progesterone increased IFN-τ expression in EECs. IFN-τ increased p-STAT1 and p-STAT3 levels in EECs, but reduced TRAF3 levels. In addition, IFN-τ increased expression of BoLA-I and IL-10, but decreased expression of IL-6 in EECs. These results indicate that IFN-τ enables stable implantation in dairy cows by increasing expression of BoLA-I, and by immunosuppression mediated by increased IL-10 and decreased IL-6 expression.

Protective effects of tenuigenin on Staphylococcus aureus-induced pneumonia in mice

Pneumonia is the leading cause of death in infants and young children. Staphylococcus aureus (S.aureus) is one of the most important bacteria that leads to pneumonia. Tenuigenin (TGN), a major active component isolated from the root of the Chinese herb Polygala tenuifolia, has been known to have anti-inflammatory effect. In this study, we aimed to investigate the protective effects of TGN on S.aureus-induced pneumonia in mice. The results showed that TGN significantly attenuated S.aureus-induced lung histopathological changes. TGN also inhibited lung wet/dry (W/D) ratio, and inflammatory cytokines TNF-α and IL-1β production. Furthermore, S.aureus-induced NF-κB activation was significantly inhibited by the treatment of TGN. In conclusion, the results of this study showed that TGN protected against S.aureus-induced pneumonia by inhibiting NF-κB activation. TGN might be a potential agent in the treatment of pneumonia induced by S.aureus.

Polydatin reduces Staphylococcus aureus lipoteichoic acid-induced injury by attenuating reactive oxygen species generation and TLR2-NFκB signalling

Staphylococcus aureus (S. aureus) causes severe inflammation in various infectious diseases, leading to high mortality. The clinical application of antibiotics has gained a significant curative effect. However, it has led to the emergence of various resistant bacteria. Therefore, in this study, we investigated the protective effect of polydatin (PD), a traditional Chinese medicine extract, on S. aureus lipoteichoic acid (LTA)-induced injury in vitro and in vivo. First, a significant improvement in the pathological conditions of PD in vivo was observed, suggesting that PD had a certain protective effect on LTA-induced injury in a mouse model. To further explore the underlying mechanisms of this protective effect of PD, LTA-induced murine macrophages were used in this study. The results have shown that PD could reduce the NF-κB p65, and IκBα phosphorylation levels increased by LTA, resulting in a decrease in the transcription of pro-inflammatory factors, such as TNF-α, IL-1β and IL-6. However, LTA can not only activate NF-κB through the recognition of TLR2 but also increase the level of intracellular reactive oxygen species (ROS), thereby activating NF-κB signalling. We also detected high levels of ROS that activate caspases 9 and 3 to induce apoptosis. In addition, using a specific NF-κB inhibitor that could attenuate apoptosis, namely NF-κB p65, acted as a pro-apoptotic transcription factor in LTA-induced murine macrophages. However, PD could inhibit the generation of ROS and NF-κB p65 activation, suggesting that PD suppressed LTA-induced injury by attenuating ROS generation and TLR2-NFκB signalling.

Identification and Characterization of Staphylococcus aureus Strains with an Incomplete Hemolytic Phenotype

Staphylococcus aureus is a common pathogen causing both hospital and community-acquired infections. Hemolysin is one of the important virulence factors for S. aureus and causes the typical β-hemolytic phenotype which is called complete hemolytic phenotype as well. Recently, S. aureus with an incomplete hemolytic phenotype (SIHP) was isolated from clinical samples. To study the microbiologic characteristics of SIHP, the special hemolytic phenotype of SIHP was verified on the sheep blood agar plates supplied by different manufacturers. Expression of hemolysin genes hla, hlb, hlgC, and hld of SIHP was detected by qRT-PCR and it was showed that expression of hlb in SIHP was obviously increased compared to the control S. aureus strains with complete hemolytic phenotype (SCHP), while the expression of hla, hlgC, and hld in SIHP was significantly decreased. In addition, the α-hemolysin encoded by gene hla was decreased obviously in SIHP compared to SCHP by western blot. All 60 SIHP strains were identified to be the methicillin resistant S. aureus (MRSA), and moreover these SIHP strains all contains mecA gene. The virulence gene tst were all present in SIHP, and the intracellular survival ability of SIHP was much greater than that of the gene tst negative S. aureus. We also found that IL-2, IL-6, and IL-17A secreted in the supernatant of SIHP infected macrophages increased significantly compared to tst negative control strains infected ones. MLST analysis showed that all of SIHP strains were classified into ST5 clone. To our knowledge, this study firstly showed that SIHP strains are a kind of methicillin resistant strains which express β-hemolysin highly and possess a potential high virulence, and it was suggested that SIHP should be paid more attention in hospital.