Effects of Baicalin on piglet monocytes involving PKC-MAPK signaling pathways induced by Haemophilus parasuis

Baicalin Weakens the Virulence of Porcine Extraintestinal Pathogenic Escherichia coli by Inhibiting the LuxS/AI-2 Quorum-Sensing System

Porcine extraintestinal pathogenic Escherichia coli (ExPEC) is a pathogenic bacterium that causes huge economic losses to the pig farming industry and considerably threatens human health. The quorum sensing (QS) system plays a crucial role in the survival and pathogenesis of pathogenic bacteria. Hence, it is a viable approach to prevent ExPEC infection by compromising the QS system, particularly the LuxS/AI-2 system. In this study, we investigated the effects of baicalin on the LuxS/AI-2 system of ExPEC. Baicalin at concentrations of 25, 50, and 100 μg/mL significantly diminished the survival ability of ExPEC in hostile environments and could inhibit the biofilm formation and autoagglutination ability in ExPEC. Moreover, baicalin dose-dependently decreased the production of AI-2 and down-regulated the expression level of luxS in PCN033. These results suggest that baicalin can weaken the virulence of PCN033 by inhibiting the LuxS/AI-2 system. After the gene luxS was deleted, AI-2 production in PCN033 was almost completely eliminated, similar to the effect of baicalin on the production of AI-2 in PCN033. This indicates that baicalin reduced the production of AI-2 by inhibiting the expression level of luxS in ExPEC. In addition, the animal experiment further showed the potential of baicalin as a LuxS/AI-2 system inhibitor to prevent ExPEC infection. This study highlights the potential of baicalin as a natural quorum-sensing inhibitor for therapeutic applications in preventing ExPEC infection by targeting the LuxS/AI-2 system.

Baicalin Alleviate Apoptosis via PKC-MAPK Pathway in Porcine Peritoneal Mesothelial Cells Induced by Glaesserella parasuis

Glaesserella parasuis (GPS), a causative agent of Glässer’s disease, is thought to be the main fatal cause of peritonitis in swine, thus resulting in high mortality and morbidity and significant economic losses to the swine industry. However, the mechanisms of GPS infection-induced apoptosis and possible therapeutic pathway for GPS infection in peritonitis remain unclear. Baicalin has important biological functions during disease treatment, such as antiviral, bacterial inhibition, anti-apoptosis, and anti-inflammatory. However, whether baicalin has anti-apoptotic effects during the process of GPS infection in peritonitis is unclear. In the present study, the anti-apoptotic effect and mechanisms of baicalin in GPS infection-induced apoptosis were investigated in porcine peritoneal mesothelial cells (PPMC). The results showed that baicalin could inhibit the apoptosis rate occurrence of PPMC induced by GPS to various degrees and inhibit the expression of apoptosis-related genes and cleaved caspase-3. Meanwhile, baicalin significantly antagonized the expression of p-JNK, p-p38, and p-ERK induced by GPS in PPMC. These findings for the first time demonstrate that baicalin exerted the effect of antagonizing GPS induced apoptosis in PPMC by inhibiting the activation of the PKC-MAPK pathway and could be a therapeutic option in the management of GPS infection.

Reckoning apigenin and kaempferol as a potential multi-targeted inhibitor of EGFR/HER2-MEK pathway of metastatic colorectal cancer identified using rigorous computational workflow

In the past two decades, the treatment of metastatic colorectal cancer (mCRC) has been revolutionized as multiple cytotoxic, biological, and targeted drugs are being approved. Unfortunately, tumors treated with single targeted agents or therapeutics usually develop resistance. According to pathway-oriented screens, mCRC cells evade EGFR inhibition by HER2 amplification and/or activating Kras-MEK downstream signaling. Therefore, treating mCRC patients with dual EGFR/HER2 inhibitors, MEK inhibitors, or the combination of the two drugs envisaged to prevent the resistance development which eventually improves the overall survival rate. In the present study, we aimed to screen potential phytochemical lead compounds that could multi-target EGFR, HER2, and MEK1 (Mitogen-activated protein kinase kinase) using a computer-aided drug design approach that includes molecular docking, endpoint binding free energy calculation using MM-GBSA, ADMET, and molecular dynamics (MD) simulations. Docking studies revealed that, unlike all other ligands, apigenin and kaempferol exhibit the highest docking score against all three targets. Details of ADMET analysis, MM/GBSA, and MD simulations helped us to conclusively determine apigenin and kaempferol as potentially an inhibitor of EGFR, HER2, and MEK1 apigenin and kaempferol against mCRC at a systemic level. Additionally, both apigenin and kaempferol elicited antiangiogenic properties in a dose-dependent manner. Collectively, these findings provide the rationale for drug development aimed at preventing CRC rather than intercepting resistance.

Baicalin Protects Vascular Tight Junctions in Piglets During Glaesserella parasuis Infection

Glaesserella parasuis (G. parasuis) can cause Glässer's disease and severely affect swine industry worldwide. This study is an attempt to address the issue of the capability of G. parasuis to damage the vascular barrier and the effects of baicalin on vascular tight junctions (TJ) in order to investigate the interactions between the pathogen and the porcine vascular endothelium. Piglets were challenged with G. parasuis and treated with or without baicalin. The expressions of vascular TJ genes were examined using RT-PCR. The distribution patterns of TJ proteins were detected by immunofluorescence. The involved signaling pathways were determined by Western blot assays on related proteins. G. parasuis can downregulate TJ expression and disrupt the distribution of TJ proteins. Baicalin can alleviate the downregulation of vascular TJ mRNA, maintain the distribution, and prevent the abnormalities of TJ. These results provide ample evidence that baicalin has the capacity to protect vascular TJ damaged by G. parasuis through inhibiting PKC and MLCK/MLC pathway activation. As a result, baicalin is a promising candidate for application as a natural agent for the prevention and control of G. parasuis infection.

Baicalin enhances the proliferation and invasion of trophoblasts and suppresses vascular endothelial damage by modulating long non-coding RNA NEAT1/miRNA-205-5p in hypertensive disorder complicating pregnancy

AIM

Trophoblastic and vascular endothelial injuries were closely associated with the pathogenesis of hypertensive disorder complicating pregnancy (HDCP). The present study was designed to determine the functional role of baicalin in the proliferation and invasion of trophoblasts and vascular endothelial injury.

METHODS

Ang II was adopted to stimulate HTR-8/SVneo and human umbilical vein endothelial cells (HUVECs). Cell viability was examined by CCK-8 assay. Flow cytometry and TUNEL staining determined cell apoptosis. Invasive ability of HTR-8/SVneo cells was measured by transwell assay. In vitro angiogenesis of HUVECs was assessed by Tube formation assay. In addition, the production of reactive oxygen species (ROS) was determined by DCFH-DA staining. Furthermore, long non-coding RNA (lncRNA) NEAT1 and miRNA-205-5p levels were detected using real-time quantitative polymerase chain reaction and the binding relationship between lncRNA NEAT1 and miRNA-205-5p was verified by dual-luciferase reporter assay. Moreover, interactions among lncRNA NEAT1, miRNA-205-5p, and MMP9 or vascular endothelial growth factor (VEGF) were confirmed by RNA immunoprecipitation assay.

RESULTS

Baicalin visibly improved cell viability, reduced the apoptosis of Ang II-stimulated HTR-8/SVneo and HUVEC cells, and repressed overproduction of ROS. Additionally, baicalin promoted the invasion of Ang II-stimulated HTR-8/SVneo cells and induced a stronger in vitro angiogenesis of Ang II-stimulated HUVECs. What's more, baicalin upregulated lncRNA NEAT1 expression and downregulated miR-205-5p expression. LncRNA NEAT1 sponged miR-205-5p and inhibited the combination of miR-205-5p and MMP9 or VEGF.

CONCLUSIONS

Baicalin can facilitate the proliferation and invasion of trophoblasts and alleviate vascular endothelial damage by upregulating lncRNA NEAT1 to impede the interaction between miR-205-5p and MMP9 or VEGF.

Inhibition of Haemophilus parasuis by berberine and proteomic studies of its mechanism of action

Haemophilus parasuis is the main agent of Glässer's disease, which causes substantial losses in pig production. However, the pathogenic mechanism and virulence factors of H. parasuis have not been fully determined. In this study, berberine is shown to have a good therapeutic effect in vivo against H. parasuis; the minimal inhibitory concentration (MIC) in vitro was 2 μg/mL. Berberine inhibited H. parasuis adhesion to and invasion of PK-15 pig kidney cells. Proteomics studies of H. parasuis after berberine treatment identified a total of 97 differentially-expressed proteins; 35 upregulated and 62 downregulated. Bioinformatics analysis showed that berberine may inhibit the growth of H. parasuis by affecting outer membrane proteins, transferrins, and energy metabolism. This study provides a basis for the development of new antibacterial agents.

Protective Effects of Baicalin on Peritoneal Tight Junctions in Piglets Challenged with Glaesserella parasuis

Glaesserella parasuis (G. parasuis) causes inflammation and damage to piglets. Whether polyserositis caused by G. parasuis is due to tight junctions damage and the protective effect of baicalin on it have not been examined. Therefore, this study aims to investigate the effects of baicalin on peritoneal tight junctions of piglets challenged with G. parasuis and its underlying molecular mechanisms. Piglets were challenged with G. parasuis and treated with or without baicalin. RT-PCR was performed to examine the expression of peritoneal tight junctions genes. Immunofluorescence was carried out to detect the distribution patterns of tight junctions proteins. Western blot assays were carried out to determine the involved signaling pathways. Our data showed that G. parasuis infection can down-regulate the tight junctions expression and disrupt the distribution of tight junctions proteins. Baicalin can alleviate the down-regulation of tight junctions mRNA in peritoneum, prevent the abnormalities and maintain the continuous organization of tight junctions. Our results provide novel evidence to support that baicalin has the capacity to protect peritoneal tight junctions from G. parasuis-induced inflammation. The protective mechanisms of baicalin could be associated with inhibition of the activation of PKC and MLCK/MLC signaling pathway. Taken together, these data demonstrated that baicalin is a promising natural agent for the prevention and treatment of G. parasuis infection.

Pigs Overexpressing Porcine β-Defensin 2 Display Increased Resilience to Glaesserella parasuis Infection

As the causative agent of Glässer’s disease, Glaesserella (Haemophilus) parasuis has led to serious economic losses to the swine industry worldwide. Due to the low cross-protection of vaccines and increasing antimicrobial resistance of G. parasuis, it is important to develop alternative approaches to prevent G. parasuis infection. Defensins are host defense peptides that have been suggested to be promising substitutes for antibiotics in animal production, while porcine β-defensin 2 (PBD-2) is a potent antimicrobial peptide discovered in pigs. Our previous study generated transgenic (TG) pigs overexpressing PBD-2, which displayed enhanced resistance to Actinobacillus pleuropneumoniae. In this study, the antibacterial activities of PBD-2 against G. parasuis are determined in vitro and in the TG pig model. The concentration-dependent bactericidal activity of synthetic PBD-2 against G. parasuis was measured by bacterial counting. Moreover, after being infected with G. parasuis via a cohabitation challenge model, TG pigs overexpressing PBD-2 displayed significantly milder clinical signs and less severe gross pathological changes than their wild-type (WT) littermates. The TG pigs also exhibited alleviated lung and brain lesions, while bacterial loads in the lung and brain tissues of the TG pigs were significantly lower than those of the WT pigs. Additionally, lung and brain homogenates from TG pigs possessed enhanced antibacterial activity against G. parasuis when compared with those from the WT pigs. Altogether, these proved that overexpression of PBD-2 could also endow pigs with increased resilience to G. parasuis infection, which further confirmed the potential of using the PBD-2 coding gene to develop disease-resistant pigs and provided a novel strategy to combat G. parasuis as well.

The main bioactive compounds of Scutellaria baicalensis Georgi. for alleviation of inflammatory cytokines: A comprehensive review

Scutellaria baicalensis Georgi., a plant used in traditional Chinese medicine, has multiple biological activities, including anti-inflammatory, antiviral, antitumor, antioxidant, and antibacterial effects, and can be used to treat respiratory tract infections, pneumonia, colitis, hepatitis, and allergic diseases. The main active substances of S. baicalensis, baicalein, baicalin, wogonin, wogonoside, and oroxylin A, can act directly on immune cells such as lymphocytes, macrophages, mast cells, dendritic cells, monocytes, and neutrophils, and inhibit the production of the inflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α, and other inflammatory mediators such as nitric oxide, prostaglandins, leukotrienes, and reactive oxygen species. The molecular mechanisms underlying the immunomodulatory and anti-inflammatory effects of the active compounds of S. baicalensis include downregulation of toll-like receptors, activation of the Nrf2 and PPAR signaling pathways, and inhibition of the nuclear thioredoxin system and inflammation-associated pathways such as those of MAPK, Akt, NFκB, and JAK-STAT. Given that in addition to the downregulation of cytokine production, the active constituents of S. baicalensis also have antiviral and antibacterial effects, they may be more promising candidate therapeutics for the prevention of infection-related cytokine storms than are drugs having only antimicrobial or anti-inflammatory activities.

Compounds from Natural Sources as Protein Kinase Inhibitors

The advantage of natural compounds is their lower number of side-effects when compared to most synthetic substances. Therefore, over the past several decades, the interest in naturally occurring compounds is increasing in the search for new potent drugs. Natural compounds are playing an important role as a starting point when developing new selective compounds against different diseases. Protein kinases play a huge role in several diseases, like cancers, neurodegenerative diseases, microbial infections, or inflammations. In this review, we give a comprehensive view of natural compounds, which are/were the parent compounds in the development of more potent substances using computational analysis and SAR studies.

The effect of baicalin on microRNA expression profiles in porcine aortic vascular endothelial cells infected by Haemophilus parasuis

Glässer's disease, caused by Haemophilus parasuis (H. parasuis), is associated with vascular damage and vascular inflammation in pigs. Therefore, early assessment and treatment are essential to control the inflammatory disorder. MicroRNAs have been shown to be involved in the vascular pathology. Baicalin has important pharmacological functions, including anti-inflammatory, antimicrobial and antioxidant effects. In this study, we investigated the changes of microRNAs in porcine aortic vascular endothelial cells (PAVECs) induced by H. parasuis and the effect of baicalin in this model by utilizing high-throughput sequencing. The results showed that 155 novel microRNAs and 76 differentially expressed microRNAs were identified in all samples. Subsequently, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the target genes of the differentially expressed microRNAs demonstrated that regulation of actin cytoskeleton, focal adhesion, ECM-receptor interaction, bacterial invasion of epithelial cells, and adherens junction were the most interesting pathways after PAVECs were infected with H. parasuis. In addition, when the PAVECs were pretreated with baicalin, mismatch repair, peroxisome, oxidative phosphorylation, DNA replication, and ABC transporters were the most predominant signaling pathways. STRING analysis showed that most of the target genes of the differentially expressed microRNAs were associated with each other. The expression levels of the differentially expressed microRNAs were negatively co-regulated with their target genes' mRNA following pretreatment with baicalin in the H. parasuis-induced PAVECs using co-expression networks analysis. This is the first report that microRNAs might have key roles in inflammatory damage of vascular tissue during H. parasuis infection. Baicalin regulated the microRNAs changes in the PAVECs following H. parasuis infection, which may represent useful novel targets to prevent or treat H. parasuis infection.

The effects of baicalin on piglets challenged with Glaesserella parasuis

Glaesserella parasuis (G. parasuis) causes porcine vascular inflammation and damage. Baicalin is reported to have antioxidant and anti-inflammatory functions. However, whether baicalin protects piglets against G. parasuis challenge and the potential protective mechanism have not been investigated. Therefore, in this study, we comprehensively examined the protective efficacy of baicalin in piglets challenged with G. parasuis and the possible protective mechanism. Our results show that baicalin attenuated the release of the inflammation-related cytokines interleukin (IL) 1β, IL6, IL8, IL10, and tumour necrosis factor α (TNF-α) and reduced high mobility group box 1 (HMGB1) production and cell apoptosis in piglets infected with G. parasuis. Baicalin also inhibited the activation of the mitogen-activated protein kinase (MAPK) signalling pathway and protected piglets against G. parasuis challenge. Taken together, our data suggest that baicalin could protect piglets from G. parasuis by reducing HMGB1 release, attenuating cell apoptosis, and inhibiting MAPK signalling activation, thereby alleviating the inflammatory response induced by the bacteria. Our results suggest that baicalin has utility as a novel therapeutic drug to control G. parasuis infection.

Antibacterial effect of Blumea balsamifera DC. essential oil against Haemophilus parasuis

Haemophilus parasuis (H. parasuis), the cause of the Glasser's disease, is a potentially pathogenic gram-negative organism that colonizes the upper respiratory tract of pigs. The extraction of Blumea balsamifera DC., as a traditional Chinese herb, has shown great bacteriostatic effect against several common bacteria. To study the antibacterial effect on H. parasuis in vitro, this study evaluated the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Blumea balsamifera DC. essential oil (BBO) as well as morphological changes in H. parasuis treated with it. Furthermore, changes in expression of total protein and key virulence factors were also assessed. Results showed that the MIC and MBC were 0.625 and 1.25 μg/mL, respectively. As the concentration of BBO increased, the growth curve inhibition became stronger. H. parasuis cells were damaged severely after treatment with BBO for 4 h, demonstrating plasmolysis and enlarged vacuoles, along with broken cell walls and membranes. Total protein and virulence factor expression in H. parasuis was significantly downregulated by BBO. Taken together, these results indicated a substantial antibacterial effect of BBO on H. parasuis.

Epidemiological and PK/PD cutoff values determination and PK/PD-based dose assessment of gamithromycin against Haemophilus parasuis in piglets

Background

Gamithromycin is a macrolide approved for the treatment of bovine and swine respiratory diseases. Our study aims to establish the clinical breakpoint and optimum dose regimen for gamithromycin against Haemophilus parasuis in piglets.

Results

Gamithromycin was well absorbed and fully bioavailable (87.2–101%) after intramuscular and subcutaneous administrations. The MICs of gamithromycin for 192 clinical H. parasuis isolates ranged from 0.008 to 128 mg/L and the epidemiological cutoff (ECOFF) was calculated as 1.0 mg/L. A large potentiation effect of serum on in vitro susceptibility of gamithromycin was observed for H. parasuis, with broth/serum ratios of 8.93 for MICs and 4.46 for MBCs, respectively. The postantibiotic effects were 1.5 h (1 × MIC) and 2.4 h (4 × MIC), and the postantibiotic sub-MIC effects ranged from 2.7 to 4.3 h. Gamithromycin had rapid and concentration-dependent killing against H. parasuis, and the AUC_24h/MIC ratio correlated well with ex vivo efficacy (R² = 0.97). The AUC_24h/MIC targets in serum associated with bacteriostatic, bactericidal and eradication activities were 15.8, 30.3 and 41.2, respectively. The PK/PD-based population dose prediction indicated a probability of target attainment (PTA) for the current marketed dose (6 mg/kg) of 88.9% against H. parasuis. The calculated gamithromycin dose for a PTA ≥ 90% was 6.55 mg/kg. Based on Monte Carlo simulations, the PK/PD cutoff (CO_PD) was determined to be 0.25 mg/L.

Conclusion

The determined cutoffs and PK/PD-based dose prediction will be of great importance in gamithromycin resistance surveillance and serve as an important step in the establishment of optimum dose regimen and clinical breakpoints.

Pharmacokinetics of sodium baicalin following intravenous and intramuscular administration to piglets

The purpose of this study was to determine the pharmacokinetics of baicalin after intravenous and intramuscular administration of sodium baicalin at 50 mg/kg to piglets. Plasma baicalin levels were determined by high-performance liquid chromatography. The plasma concentration-time data of baicalin for both administration routes were best described by two-compartmental open model. The area under the plasma concentration-time curve and the elimination half-lives were 77.47 ± 6.14 µg/ml × h and 1.73 ± 0.16 hr for intravenous and 64.85 ± 5.67 µg/ml × h and 2.42 ± 0.15 hr for intramuscular administration, respectively. The apparent volume of distribution and body clearance were 1.63 ± 0.23 L/kg and 2.74 ± 0.30 L h^-1  kg^-1 for intravenous and 0.51 ± 0.10 L/kg and 0.78 ± 0.08 L h^-1  kg^-1 for intramuscular routes, respectively. An intramuscular injection of sodium baicalin in piglets resulted in rapid and complete absorption, with a mean maximal plasma concentration of 77.28 ± 7.40 µg/ml at 0.17 hr and a high absolute bioavailability of 83.73 ± 5.53%.

Baicalin modulates apoptosis via RAGE, MAPK, and AP-1 in vascular endothelial cells during Haemophilus parasuis invasion

Glässer’s disease, caused by Haemophilus parasuis, is a chronic disease related to an inflammatory immune response. Baicalin exerts important biological functions. In this study, we explored the protective efficacy of treatment with baicalin and the potential mechanism of activation of the MAPK signaling pathway in porcine aortic vascular endothelial cells (PAVECs) induced by H. parasuis. H. parasuis stimulated expression of receptor for advanced glycation end products, induced a significant increase in the level of protein kinase-α and protein kinase-δ phosphorylation, and significantly up-regulated ERK, c-Jun N-terminal kinase, and p38 phosphorylation in PAVECs. H. parasuis also up-regulated the levels of apoptotic genes (Bax, C-myc, and Fasl) and the expression levels of c-Jun and c-Fos, and induced S-phase arrest in PAVECs. However, treatment with baicalin inhibited expression of RAGE, suppressed H. parasuis-induced protein kinase-α and protein kinase-δ phosphorylation, reduced ERK, c-Jun N-terminal kinase, and p38 phosphorylation, down-regulated apoptotic genes (Bax, C-myc, and Fasl), attenuated phospho-c-Jun production from the extracellular to the nuclei, and reversed S-phase arrest in PAVECs. In conclusion, baicalin treatment inhibited the MAPK signaling pathway, thereby achieving its anti-inflammatory responses, which provides a new strategy to control H. parasuis infection.