Effect of betulinic acid administration on TLR-9/NF-κB /IL-18 levels in experimental liver injury

Betulinic acid mitigates zearalenone-induced liver injury by ERS/MAPK/Nrf2 signaling pathways in mice

Zearalenone (ZEA) is a mycotoxin commonly found in cereals and feedstuffs, which can induce oxidative stress and inflammation to cause liver damage in humans and animals. Betulinic acid (BA) is extracted from pentacyclic triterpenoids of many natural plants and has anti-inflammatory, and anti-oxidation biological activities in many studies. However, the protective effect of BA on liver injury induced by ZEA has not been reported. Therefore, this study aims to explore the protective effect of BA on ZEA-induced liver injury and its possible mechanism. In the mice experiment, ZEA exposure increased the liver index and caused histopathological impairment, oxidative damage, hepatic inflammatory responses, and increased hepatocyte apoptosis. However, when combined with BA, it could inhibit the production of ROS, up-regulate the proteins expression of Nrf2 and HO-1 and down-regulate the expression of Keap1, and alleviate oxidative damage and inflammation in the liver of mice. In addition, BA could alleviate ZEA-induced apoptosis and liver injury in mice by inhibiting the endoplasmic reticulum stress (ERS) and MAPK signaling pathways. In conclusion, this study revealed the protective effect of BA on the hepatotoxicity of ZEA for the first time, providing a new perspective for the development of ZEA antidote and the application of BA.

Betulinic acid prevents liver fibrosis by binding Lck and suppressing Lck in HSC activation and proliferation

ETHNOPHARMACOLOGICAL RELEVANCE

Hypericum japonicum Thunb. ex Murray (Hypericaceae), named 'Tianjihuang' is a traditional Chinese medicine with hepatoprotective, antibacterial, and antitumour effects. Betulinic acid (BA) is its active constituent and has been found to have a number of biological effects, including antiviral, anti-inflammatory, and anti-malarial therapeutic properties. Non-alcoholic fatty liver disease and acute alcoholic liver injury have both been proven to benefit from BA. BA's effects and mechanism on liver fibrosis are still unknown.

AIM OF THE STUDY

The purpose of this study was to explore the influence of BA on lymphocyte-specific protein tyrosine kinase (Lck), a non-receptor Src family kinase, that reduces liver fibrosis by inhibiting the phosphorylation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathways through the interaction of Lck and SOCS1.

MATERIALS AND METHODS

A liver fibrosis model was established in vivo with CCl₄ using haematoxylin and eosin (HE) staining, Masson staining, immunohistochemical staining, and immunofluorescence staining. Hepatic stellate cells were induced with transforming growth factor (TGF)-β1 in vitro, using Western blotting, immunofluorescence staining, and a cell scratch assay.

RESULTS

In a CCl₄-induced mouse hepatic fibrosis model and in TGF-β1-activated HSC-T6 cells, BA markedly reduced fibrosis, as demonstrated by the dramatic downregulation of α-smooth muscle actin (α-SMA) and type I collagen alpha-1 (Col1α1) protein levels in vivo and in vitro. BA significantly suppressed the activity and expression of Lck in vitro. Overexpression of Lck may diminish the effect of BA on liver fibrosis. In vitro, BA also greatly increased the expression of suppressor of cytokine signalling 1 (SOCS1) while it considerably inhibited the expression of p-JAK and p-STAT1.

CONCLUSIONS

These findings suggest that BA promotes the expression of SOCS1 by the inhibiting the interaction between Lck and SOCS1, followed by the inhibition of JAK/STAT phosphorylation to prevent the progression of liver fibrosis. Therefore, BA could be used as a promising natural supplement for the treatment of liver fibrosis.

Interleukin-18 Binding Protein in Immune Regulation and Autoimmune Diseases

Natural soluble antagonist and decoy receptor on the surface of the cell membrane are evolving as crucial immune system regulators as these molecules are capable of recognizing, binding, and neutralizing (so-called inhibitors) their targeted ligands. Eventually, these soluble antagonists and decoy receptors terminate signaling by prohibiting ligands from connecting to their receptors on the surface of cell membrane. Interleukin-18 binding protein (IL-18BP) participates in regulating both Th1 and Th2 cytokines. IL-18BP is a soluble neutralizing protein belonging to the immunoglobulin (Ig) superfamily as it harbors a single Ig domain. The Ig domain is essential for its binding to the IL-18 ligand and holds partial homology to the IL-1 receptor 2 (IL-1R2) known as a decoy receptor of IL-1α and IL-1β. IL-18BP was defined as a unique soluble IL-18BP that is distinct from IL-18Rα and IL-18Rβ chain. IL-18BP is encoded by a separated gene, contains 8 exons, and is located at chr.11 q13.4 within the human genome. In this review, we address the difference in the biological activity of IL-18BP isoforms, in the immunity balancing Th1 and Th2 immune response, its critical role in autoimmune diseases, as well as current clinical trials of recombinant IL-18BP (rIL-18BP) or equivalent.

Betulinic acid-nucleoside hybrid prevents acute alcohol -induced liver damage by promoting anti-oxidative stress and autophagy

Alcoholic abuse is one of the most serious causes of liver diseases worldwide. Although detailed molecular pathogenesis of alcohol-induced liver damages remains elusive with intensive debates, it has been widely recognized that hepatic damage caused by free radicals generated from alcohol metabolism is one of the most critical factors for alcohol-induced liver diseases. Betulinic acid is a potent antioxidant with additional known pharmacological safety characteristics and minimal toxicity. However, poor solubility limited its usage. In this study, we assessed the efficacy of BAN, a betulinic acid and nucleoside hybrid with good water solubility, in reversing acute liver damages using an established alcohol overdose animal model. The results indicated that BAN is an extremely promising therapeutic agent against acute alcohol-induced liver damage. BAN effectively protects liver from alcohol damage by reducing serum ALT level by up to 47%, as well as liver oxidative stress indicated by significantly increased SOD, CAT, and GSH-Px levels. Moreover, hepatic FXR activation and a corresponding downstream anti-oxidative stress transcriptional cascade including Nrf2, HO-1, and NOQ1 induce the protective role of BAN. On the other hand, BAN administration also leads to increase cellular autophagy response, as indicated by the key ATG protein activation. We concluded that BAN, comparing with Betulinic acid, prevents acute alcohol-induced liver damages more effectively, with the dual mechanisms of neutralizing oxidative stress and promoting autophagy.

Transport Stress Induces Skin Innate Immunity Response in Hybrid Yellow Catfish (Tachysurus fulvidraco♀ × P. vachellii♂) Through TLR/NLR Signaling Pathways and Regulation of Mucus Secretion

The transport of live fish is a necessary step for commercial production. The skin of teleost fish is the first non-specific immune barrier against exogenous stimuli, and it plays an important protective role under transport stress. Thus, the aim of this study was to explore the skin responses to transport stress in hybrid yellow catfish (Tachysurus fulvidraco♀ × Pseudobagrus vachellii♂) through transcriptome and biochemical analyses. Water samples were collected during a simulated transport treatment. Biochemical indexes and/or gene expression in blood, skin, and mucus in fish in control groups and transport-stress groups (0 h, 2 h, 4 h, 8 h, 16 h) were assayed. The levels of total ammonia-nitrogen and nitrite-nitrogen in the water increased with increasing transport time. Comparison of skin transcriptomes between the control group and the group subjected to 16 h of transport revealed 1547 differentially expressed genes (868 up-regulated and 679 down-regulated). The results of the transcriptome analysis were validated by analyses of the expression levels of selected genes by qRT-PCR. The results indicated that the toll-like receptors and nod-like receptors signaling pathways mediate the skin's immune response to transport stress: tlr9, mfn2, and ikbke were significantly up-regulated and nfkbia and map3k7cl were significantly down-regulated under transport stress. With increasing transport time, lysozyme activity and the immunoglobulin M content in skin mucus first increased and then decreased. The number of mucous cells peaked at 8 h of transport stress, and then decreased. The mucus cells changed from types II and IV to types I, II, III, and IV. The amounts of red and white blood cells and the levels of hemoglobin and hematocrit first increased and then decreased during 16 h of transport stress. Together, the results showed that the skin responds to transport stress by activating the immune signaling pathway and regulating mucus secretion. These findings have important biological significance for selecting strains that tolerate transport, as well as economic significance for optimizing the transport conditions for scaleless fish.