Characterization of inflamin, the first member of a new family of snake venom proteins that induces inflammation

Investigations on the Changes of Serum Proteins in Rabbits after Trimeresurus stejnegeri Venom Injection via Mass Spectrometry-Based Proteomics

Purpose

There are few studies on protein phosphorylation in the process of snake poisoning. The purpose of this study was to investigate the toxic mechanism of Trimeresurus stejnegeri at the protein level by determining the differential expression of phosphorylated proteins in rabbits after poisoning using proteomics.

Methods

The Trimeresurus stejnegeri venom model in rabbits was established by intramuscular injection of 20 mg/kg venom. The serum was collected and the differential expression of phosphorylated proteins in the serum was determined by the iTRAQ technology, TiO2 enriched phosphorylated peptides, and the mass spectrometry analysis. The functional analysis was conducted using ClueGO software and the related mechanism was evaluated by the network analysis of biological interaction. The expression level of related proteins was determined by the Western blotting assay.

Results

Compared to the control group, 77 differentially expressed proteins were observed in the model group. These proteins were closely associated with the complement and agglomerate cascade signaling pathways, the HIF signaling pathway, the pentose phosphate pathway, and the cholesterol metabolism signaling pathway. According to the results of network analysis, TF and SCL16A1 were determined as the core proteins, which were identified by the Western blotting assay.

Conclusion

The present study provided valuable phosphorylation signal transduction resources for investigating the toxic mechanism and the therapies for Trimeresurus stejnegeri poisoning.

Naja kaouthia venom protein, Nk-CRISP, upregulates inflammatory gene expression in human macrophages

Cysteine-Rich Secretory Proteins (CRISP) are widespread in snake venoms and known to target ion channels. More recently, CRISPs have been shown to mediate inflammatory responses. Involvement of potential receptor in CRISP-induced inflammatory reactions, however, remains unknown. A CRISP protein named as Nk-CRISP, was isolated from the venom of Naja kaouthia. The molecular mass of the purified protein was found to be ~25 kDa and the primary sequence was determined by MALDI TOF-TOF. The involvement of this protein in proinflammatory effects were evaluated in THP-1 macrophage-like cells. Nk-CRISP treated cells induced up-regulation of several inflammatory marker genes in dose dependent manner. Toll like receptor 4 (TLR4)-myeloid differentiation factor 2 (MD2) complex are known to play crucial role in recognition of damage/pathogen-associated molecular patterns and activation of innate immune response. Therefore, we hypothesized that snake venom CRISP could also modulate the innate immune response via TLR4-MD2 complex. In-silico molecular docking study of cobra CRISP with TLR4-MD2 receptor complex reveals CRISP engages its cysteine-rich domain (CRD) to interact with complex. Inhibition of TLR4 signalling pathway using CLI-095 confirmed the role of TLR4 in Nk-CRISP induced inflammatory responses. Collectively, these findings imply that TLR4 initiates proinflammatory signalling following recognition of cobra CRISP and alteration of TLR4 receptor might improve or control CRISP induced inflammation.

Relationship between epithelial-to-mesenchymal transition and the inflammatory microenvironment of hepatocellular carcinoma

Epithelial-to-mesenchymal transition (EMT) is a complex process involving multiple genes, steps and stages. It refers to the disruption of tight intercellular junctions among epithelial cells under specific conditions, resulting in loss of the original polarity, order and consistency of the cells. Following EMT, the cells show interstitial cell characteristics with the capacity for adhesion and migration, while apoptosis is inhibited. This process is critically involved in embryogenesis, wound-healing, tumor invasion and metastasis. The tumor microenvironment is composed of infiltrating inflammatory cells, stromal cells and the active medium secreted by interstitial cells. Most patients with hepatocellular carcinoma (HCC) have a history of hepatitis virus infection. In such cases, major components of the tumor microenvironment include inflammatory cells, inflammatory factors and virus-encoded protein are major components. Here, we review the relationship between EMT and the inflammatory tumor microenvironment in the context of HCC. We also further elaborate the significant influence of infiltrating inflammatory cells and inflammatory mediators as well as the products expressed by the infecting virus in the tumor microenvironment on the EMT process.