Protective effect of Gö6976, a PKD inhibitor, on LPS/D: -GalN-induced acute liver injury in mice

Small Molecule Inhibitors of Protein Kinase D: Early Development, Current Approaches, and Future Directions

Now entering its fourth decade, research on the biological function, small molecule inhibition, and disease relevance of the three known isoforms of protein kinase D, PKD1, PKD2, and PKD3, has entered a mature development stage. This mini-perspective focuses on the medicinal chemistry that provided a structurally diverse set of mainly active site inhibitors, which, for a brief time period, moved through preclinical development stages but have yet to be tested in clinical trials. In particular, between 2006 and 2012, a rapid expansion of synthetic efforts led to several moderately to highly PKD-selective chemotypes but did not yet achieve PKD subtype selectivity or resolve general toxicity and pharmacokinetic challenges. In addition to cancer, other unresolved medical needs in cardiovascular, inflammatory, and metabolic diseases would, however, benefit from a renewed focus on potent and selective PKD modulators.

S-allyl cysteine, an active ingredient of garlic, attenuates acute liver dysfunction induced by lipopolysaccharide/ d-galactosamine in mouse: Underlying mechanisms

In the present study, beneficial effect of S-allyl cysteine (SAC) was evaluated in the lipopolysaccharide/d-galactosamine (LPS/d-Gal) model of acute liver injury (ALI). To mimic ALI, LPS and d-Gal (50 μg/kg and 400 mg/kg, respectively) were intraperitoneally administered and animals received SAC per os (25 or 100 mg/kg/d) for 3 days till 1 hour before LPS/d-Gal injection. Pretreatment of LPS/d-Gal group with SAC-lowered activities of alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase and partially reversed inappropriate alterations of hepatic oxidative stress- and inflammation-related biomarkers including liver reactive oxygen species, malondialdehyde, and hepatic activity of the defensive enzyme superoxide dismutase, ferric reducing antioxidant power (FRAP), toll-like receptor-4 (TLR4), cyclooxygenase 2, NLR family pyrin domain containing 3 (NLRP3), caspase 1, nuclear factor κB (NF-κB), interleukin 1β (IL-1β), IL-6, tumor necrosis factor-α, and myeloperoxidase activity. Additionally, SAC was capable to ameliorate apoptotic biomarkers including caspase 3 and DNA fragmentation. In summary, SAC can protect liver against LPS/d-Gal by attenuation of neutrophil infiltration, oxidative stress, inflammation, apoptosis, and pyroptosis which is partly linked to its suppression of TLR4/NF-κB/NLRP3 signaling.

Crocetin protects against fulminant hepatic failure induced by lipopolysaccharide/D-galactosamine by decreasing apoptosis, inflammation and oxidative stress in a rat model

Fulminant hepatic failure (FHF) is a clinical syndrome characterized by sudden and severe liver dysfunction. Apoptosis and inflammation are essential for the pathogenesis of FHF. Crocetin, the major component present in saffron, has been reported to possess anti-inflammatory and antioxidant functions; however, its role in FHF is poorly understood. The aim of this study was to explore the protective effects of crocetin against lipopolysac§§charide (LPS)/D-galactosamine (D-GalN)-induced FHF and the underlying mechanisms in a rat model. For the in vivo study, rats were assigned to the LPS/D-GalN group or to the crocetin pre-treatment+LPS/D- GalN group. Each group was then further divided according to the different LPS/D-GalN treatment times of 0, 6, 12 or 48 h. The results demonstrated that crocetin pre-treatment efficiently protected against LPS/D-GalN-induced FHF by improving liver tissue morphology, reducing total bilirubin generation and decreasing the activities of alanine transaminase and aspartate aminotransferase. Moreover, crocetin pre-treatment significantly decreased hepatocyte apoptosis, p53 mRNA expression and the expression of proteins in the caspase family and the Bcl-2 pro-apoptotic family following LPS/D-GalN treatment. Furthermore, crocetin also decreased the secretion of pro-inflammatory cytokines in the serum and in the liver via suppression of NF-κB activation, and also suppressed hepatic oxidative stress. In conclusion, crocetin protected against LPS/D-GalN-induced FHF and inhibited apoptosis, inflammation and oxidative stress. The underlying mechanisms may be related to the regulation of apoptotic proteins in the caspase family and the Bcl-2 family, as well as the modulation of NF-κB expression. Therefore, crocetin may be used as a novel therapy for preventing FHF.

Probiotic and hepatoprotective activity of lactobacillus isolated from Mongolian camel milk products

The improving-intestinal-microbial-balance properties of lactic acid bacteria (LAB) are well known. Thus, LAB could play a vital role in the pathogenesis of liver diseases. In the present study, 107 LAB strains were isolated from Mongolian camel milk products and identified to species, then screened for their probiotic properties. As a result, we identified 71 Lactobacillus bacteria belonging to 9 different species, and 36 Lactococcus bacteria belonging to 8 different species. Among them, six strains of LAB with strong tolerance and adhesion ability were further studied for their protective effect on acute liver injury induced by lipopolysaccharide (LPS)/D-galactosamine (D-GalN). These six strains of LAB were fed to mice for 7 weeks, and on the final day of the experiment, LPS/D-GalN were used to induce acute liver injury. After challenging, the degree of liver pathological changes, secretion of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum and liver, and the expression of tumour necrosis factor (TNF)-α and interleukin (IL)-6 in the liver and intestines were observed and quantified. The results showed that the degree of liver pathological changes in mice fed with the six LAB strains were relieved to varying degrees compared with the LPS/D-GalN-induced model group, and the expressions of AST, ALT, IL-6, and TNF-α factor were also significantly decreased. Moreover, the expression levels of these factors in mice pretreated with Lactobacillus paracasei subsp. paracasei WXD5 were significantly decreased compared with other experimental groups. This suggests the probiotic potential and pharmacological value of L. paracasei subsp. paracasei as a liver injury inhibitor in the intervention of inflammation-based liver disease.

Multiomics analysis profile acute liver injury module clusters to compare the therapeutic efficacy of bifendate and muaddil sapra

The pathogenesis of acute liver injury has been plagued by biologists and physicians. We know little about its therapeutic mechanism. Therefore, this study explored the mechanism of bifendate and muaddil sapra in the treatment of acute liver injury. Firstly, co-expression and cluster analysis of disease-related genes were carried out, and the Go function and KEGG pathway of modules and related genes were identified. Secondly, pivot analysis of modules can identify key regulators. On the other hand, based on the acute liver injury induced by CCl4, we use the combined analysis of proteomics and transcriptome to find therapeutic targets and related mechanisms of drugs. A total of 21 dysfunction modules were obtained, which were significantly involved in immune system, hepatitis and other related functions and pathways. Transcriptome analysis showed 117 targets for bifendate treatment, while 119 for muaddil sapra. Through exploring the mechanism, we found that the two drugs could modulate the module genes. Moreover, bifendate regulate the dysfunction module through ncRNA (SNORD43 and RNU11). Muaddil sapra can mediate dysfunction modules not only by regulating ncRNA (PRIM2 and PIP5K1B), but also by regulating TF (STAT1 and IRF8), thus having a wider therapeutic potential. On the other hand, proteome analysis showed that bifendate mainly regulated Rac2, Fermt3 and Plg, while muaddil sapra mainly regulated Sqle and Stat1. In addition, muaddil sapra regulates less metabolic related proteins to make them more effective. Overall, this study not only provides basic theory for further study of the complex pathogenesis of acute liver injury, but also provides valuable reference for clinical use of bifendate and muaddil sapra in the treatment of acute liver injury.

Hepatoprotective role of vardenafil against experimentally induced hepatitis in mice

Vardenafil is a selective phosphodiesterase-5 inhibitor used for erectile dysfunction treatment. The hepatoprotective role of vardenafil against acute hepatitis is not reported yet. Hence, this study aims to explore the protective role of vardenafil against concanavalin A (Con A) induced acute liver injury. Mice were pretreated with vardenafil (0.17 mg/kg/day) for seven consecutive days, and then subjected to a single IV injection of Con A. The results demonstrated that the vardenafil pretreatment significantly reduced the elevated serum levels of transaminases and alkaline phosphatase. Histopathological examination showed marked necrosis and inflammation in Con A-treated mice which was significantly ameliorated in vardenafil pretreated animals. Vardenafil pretreatment significantly alleviated the expression of nuclear factor kappa-B and inducible nitric oxide synthase in the hepatic tissue. Additionally, serum levels of nitric oxide and tumor necrosis factor-alpha were decreased in vardenafil pretreated animals compared to the Con A group. Therefore, our results demonstrate that vardenafil has hepatoprotective effect and this could be linked to decrease inflammatory mediators.

The protective mechanism of schisandrin A in d-galactosamine-induced acute liver injury through activation of autophagy

CONTEXT

The principal bioactive lignan of Schisandra chinensis fructus, commonly used for traditional Chinese medicine, is schisandrin A. Schisandrin A has been widely reported as being very effective for the treatment of liver disease. However, the mechanisms of its protective effects in liver remain unclear.

OBJECTIVE

To explore the hepatoprotective mechanisms of schisandrin A.

MATERIALS AND METHODS

d-Galactosamine (d-GalN)-induced liver injury in mice was used as a model. Schisandrin A was examined for its protective mechanisms using hematoxylin-eosin (HE) staining, enzyme-linked immunosorbent assay (ELISA), western blotting and real-time PCR (RT-PCR).

RESULTS

Aspartate amino-transferase (AST) and alanine transaminase (ALT) levels in the schisandrin A group were significantly decreased (p < 0.01) compared with those in the d-GalN-treated group. HE results showed that the pathological changes in hepatic tissue seen in the d-GalN-treated were reduced in the schisandrin A/d-GalN-treated group, with the morphological characteristics being close to those of the control (untreated) group. Western blotting results showed that schisandrin A can activate autophagy flux and inhibit progression of apoptosis. The immune function of the schisandrin A-pretreated group was assayed by flow cytometry. It was found that the mechanism may involve activated autophagy flux, inhibited apoptosis, and improved immunity in response to liver damage.

CONCLUSION

Our results show that the hepatoprotective mechanisms of schisandrin A may include activation of autophagy flux and inhibition of apoptosis. These results provide pharmacological evidence supporting its future clinical application.

Interferon-γ-induced PD-L1 surface expression on human oral squamous carcinoma via PKD2 signal pathway

Many cells located in the tumor microenvironment function to protect or promote the ability of tumor cells to escape immune destruction. Previous studies have shown that programmed death ligand-1 (PD-L1), a ligand of the B7 superfamily, is expressed on a series of human tumors and can inhibit anti-tumor immune responses. Interferon-γ (IFN-γ), a cytokine produced and secreted by inflammatory cells in the tumor microenvironment, is a main stimulator of PD-L1 expression in tumor cells. Making clear the mechanism of IFN-γ induced the expression of PD-L1 on tumor cells that is benefit to find a way to inhibit the function of PD-L1 and improve cancer cell-reactive immune responses. Herein, we have identified protein kinase D isoform 2 (PKD2) as an important regulator of PD-L1 expression on human oral squamous carcinoma cells induced by IFN-γ. IFN-γ induced the expression of PD-L1 and PKD2 in human oral squamous carcinoma Tca8113 in both time and dose dependent manner. The expression of PD-L1 was decreased significantly after PKD2 knockdown with shRNA/siRNA interference or PKD chemical inhibitor following induction with IFN-γ. The apoptosis of CD8(+) T cell which is induced by tumor cells via PD-1/PD-L1 pathway was significantly decreased, as a result, the anti-tumor effects of tumor antigen specific T cell were increased in vivo. Together, these data combined with our previous results, indicate PKD2 as an important target candidate for tumor biotherapy. Inhibition of PKD2 activation not only inhibits PD-L1 expression and promotes an anti-tumor effect, but also decreases drug resistance in chemotherapy.

Erythropoietin increases survival and attenuates fulminant hepatic failure injury induced by D-galactosamine/lipopolysaccharide in mice

BACKGROUND

Liver transplantation is the only therapy of proven benefit in fulminant hepatic failure (FHF). Lipopolysaccharide (LPS), d-galactosamine (GalN)-induced FHF is a well-established model of liver injury in mice. Erythropoietin has a powerful tissue-protective effect in animal models. The aim of this study was to investigate the effect and mechanism of recombinant human erythropoietin (rhEPO) administration in FHF mice.

METHODS

C57BL/6 (n=42) mice were studied in vivo in a fulminant model induced by GalN/LPS. rhEPO was administered 30 min after the induction of FHF. Serum liver enzymes and hepatic tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels were determined. Histologic analysis was performed, and apoptotic cells were identified by immunohistochemistry for caspase-3. Nuclear factor (NF)-κB and c-Jun-N-terminal kinase (JNK) activation were studied using Western blot analysis.

RESULTS

After the induction of FHF, all control mice died within 12 hr of GalN/LPS administration. However, 83% of mice that were administered rhEPO were alive 2 weeks later, and overall survival improved (Kaplan-Meier, P<0.001). The serum liver enzymes, hepatic TNF-α and IL-1β levels, liver histologic injury, and apoptotic hepatocytes were significantly reduced in FHF mice that were administered rhEPO compared with untreated mice. A significant decrease in hepatic NF-κB and JNK activation was noted in FHF rhEPO-treated mice compared with FHF untreated mice.

CONCLUSIONS

The administration of rhEPO brought about increased survival and attenuation of the hepatic injury. This was associated with decreased hepatic NF-κB and JNK activation and thus TNF-α and IL-1β levels. These findings have important implications for the potential use of rhEPO in FHF.