Establishment, characterization and immortalization of a fibroblast cell line from the Chinese red belly toad Bombina maxima skin

The amphibian invitrome: Past, present, and future contributions to our understanding of amphibian immunity

Many amphibian populations are declining worldwide, and infectious diseases are a leading cause. Given the eminent threat infectious diseases pose to amphibian populations, there is a need to understand the host-pathogen-environment interactions that govern amphibian susceptibility to disease and mortality events. However, using animals in research raises an ethical dilemma, which is magnified by the alarming rates at which many amphibian populations are declining. Thus, in vitro study systems such as cell lines represent valuable tools for furthering our understanding of amphibian immune systems. In this review, we curate a list of the amphibian cell lines established to date (the amphibian invitrome), highlight how research using amphibian cell lines has advanced our understanding of the amphibian immune system, anti-ranaviral defence mechanisms, and Batrachochytrium dendrobatidis replication in host cells, and offer our perspective on how future use of amphibian cell lines can advance the field of amphibian immunology.

An Aerolysin-like Pore-Forming Protein Complex Targets Viral Envelope to Inactivate Herpes Simplex Virus Type 1

Because most of animal viruses are enveloped, cytoplasmic entry of these viruses via fusion with cellular membrane initiates their invasion. However, the strategies in which host cells counteract cytoplasmic entry of such viruses are incompletely understood. Pore-forming toxin aerolysin-like proteins (ALPs) exist throughout the animal kingdom, but their functions are mostly unknown. In this study, we report that βγ-crystallin fused aerolysin-like protein and trefoil factor complex (βγ-CAT), an ALP and trefoil factor complex from the frog Bombina maxima, directly blocks enveloped virus invasion by interfering with cytoplasmic entry. βγ-CAT targeted acidic glycosphingolipids on the HSV type 1 (HSV-1) envelope to induce pore formation, as indicated by the oligomer formation of protein and potassium and calcium ion efflux. Meanwhile, βγ-CAT formed ring-like oligomers of ∼10 nm in diameter on the liposomes and induced dye release from liposomes that mimic viral envelope. Unexpectedly, transmission electron microscopy analysis showed that the βγ-CAT-treated HSV-1 was visibly as intact as the vehicle-treated HSV-1, indicating that βγ-CAT did not lyse the viral envelope. However, the cytoplasmic entry of the βγ-CAT-treated HSV-1 into HeLa cells was totally hindered. In vivo, topical application of βγ-CAT attenuated the HSV-1 corneal infection in mice. Collectively, these results uncovered that βγ-CAT possesses the capacity to counteract enveloped virus invasion with its featured antiviral-acting manner. Our findings will also largely help to illustrate the putative antiviral activity of animal ALPs.

Establishing Cell Lines from Fresh or Cryopreserved Tissue from the Great Crested Newt (Triturus cristatus):A Preliminary Protocol

This study describes a successful protocol for establishing cell lines from the threatened Triturus cristatus in terms of collection, preparing, establishing, cryopreserving, thawing and quality checking. Different parameters such as media, media change, fresh vs. cryopreserved tissue and seeding density were tested to optimize culture conditions for this species. With fresh tissue, no considerable differences in the use of two different media were found, but with cryopreserved tissue, a combination of ITS (insulin/transferrin/selenite) and 2-mercaptoethanol had a positive effect on growth. Real-time measurements on the cell lines were used, for the first time in amphibian cells, to investigate the effect of different treatments such as media change with or without washing. Media change had a positive impact on the cells, whereas the effect was negative when combined with washing. It is concluded that establishment of cell lines is possible from the great crested newt, especially when using fresh tissue, but much more challenging if the tissue has been cryopreserved. Real-time measurement during cell culture is a useful tool to visualize the sensitivity of amphibian cells during different culture treatments.

Opposite response to hypoxia by breast cancer cells between cell proliferation and cell migration: A clue from microRNA expression profile

The majority of tumors possess the features of hypoxia. It is generally accepted that hypoxia is a negative prognostic factor for cancer. Low levels of oxygen are able to modify basic cell metabolism status. Elucidating the basic response, including cell proliferation and migration, to hypoxia by cancer cells is important for understanding the role of hypoxia in the development of cancer. In the present study, CoCl₂ stimulation was used to simulate hypoxia. A microRNA (miRNA/miR) array was used to systematically detect the changes in miRNA expression profiles. Following treatment with CoCl₂ for 12 h, 15 miRNAs were markedly upregulated and 10 miRNAs were markedly decreased compared with the control. After 24 h CoCl₂ incubation, 15 miRNAs were increased and 3 miRNAs were decreased compared with the control. Among them, 7 miRNAs were upregulated and 2 miRNAs were downregulated at 12 and 24 h following CoCl₂ stimulation. The potential roles of these miRNA were reviewed and it was identified that the majority of them are associated with cell proliferation and migration. Additional experiments demonstrated that CoCl₂ incubation inhibited the proliferation of MCF-7 cells but promoted cell migration. miR-491 may be a key miRNA for hypoxia-inhibited cell proliferation, as it was identified that hypoxia induced the downregulation of B-cell lymphoma-extra large in a miR-491-dependent manner. As the target of miR-302a, CXCR4 may be a key protein for hypoxia-promoted cell migration. In the present study, it was identified that in the early stage of hypoxia, cell proliferation was inhibited but cell migration was promoted. These results support the hypothesis that hypoxia may be a driving force for tumor cell escape from the primary tumor site to other organs, or other sites of the same organ.

A high concentration of DMSO activates caspase-1 by increasing the cell membrane permeability of potassium

Dimethyl sulfoxide (DMSO) is widely used in the laboratory and in clinical situations because it is soluble in both aqueous and organic media and can be used to treat many types of diseases. Thus, it is meaningful to assess the comprehensive and in-depth biological activities of DMSO. Here, we showed that a high concentration of DMSO induced pro-inflammatory cytokine interleukin-1β (IL-1β) secretion from the monocytic cell line THP-1. DMSO-induced IL-1β secretion was dependent on intracellular caspase-1 activation. Further study revealed that the activation of caspase-1 by DMSO relied on NLRP3 inflammasome formation. It is generally accepted that the NLRP3 inflammasome is activated by reactive oxygen species generation or potassium efflux; however, the common NLRP3 inflammasome trigger remains controversial. Here, we showed that although DMSO is a ROS scavenger, this chemical increases membrane permeability and potassium efflux, and the formation of the NLRP3 inflammasome reflects the increased membrane permeability and potassium efflux induced by DMSO. The present study reveals a new characteristic of DMSO, which should be considered when using this chemical in either the laboratory or the clinic.

Heat shock factor 2 is associated with the occurrence of lung cancer by enhancing the expression of heat shock proteins

Cancer is the leading cause of morbidity and mortality worldwide, particularly lung cancer. Heat shock proteins and their upstream heat shock factors are involved in the occurrence of cancer and have been widely researched. However, the role of heat shock factor 2 (HSF2) in lung cancer remains unclear. In the present study, expression levels of HSF2 in lung cancer tissues from 50 lung cancer patients were detected by reverse transcription quantitative polymerase chain reaction, and 76% (38/50) were upregulated compared with the matched normal tissues. This suggested possible involvement of HSF2 in lung cancer. To additionally investigate the role of HSF2 in lung cancer occurrence, a plasmid encoding HSF2 was constructed. HSF2 was over expressed in normal lung epithelial BEAS-2B cells and lung cancer A549 cells. The results showed that HSF2 overexpression promoted cell proliferation and cell migration in BEAS-2B and A549 cells. Additional experiments showed that the HSF2-induced cell proliferation and cell migration were dependent on induction of HSPs, particularly HSP27 and HSP90, as co-transfection of HSP27 small interfering RNA (siRNA) or HSP90 siRNA attenuated HSF2-induced cell growth and migration. In conclusion, the present study showed that HSF2 is aberrantly expressed in lung cancer, and it may be an upstream regulator of HSPs, which may strongly affect cell growth and cell migration. Additional studies are required to explain the detailed mechanism between lung cancer, HSF2, HSPs and other possible signaling pathways.

Interleukin-1β-mediated suppression of microRNA-101 and upregulation of enhancer of zeste homolog 2 is involved in particle-induced lung cancer

Lung cancer may be a result of complex factors. Small mineral particle is the well-known inducer of lung cancer. Previous study revealed the high morbidity of lung cancer in Xuan Wei in China, and the main cause of lung cancer is the use of smoky coal there. And it is generally accepted that chronic inflammation induced by small mineral particle may be a cause of lung cancer. But the relationship between chronic lung inflammation and lung cancer is largely unknown. In the present study, we found that silica particle was able to induce the secretion of interleukin-1β from a Xuan Wei lung cancer cell line, XWLC-05. At the same time, microRNA-101 (mir-101) was found to be downregulated by the treatment of silica particle. Interestingly, the interleukin 1 receptor antagonist and interleukin-1β antibody can reduce silica particle-induced downregulation of mir-101. Twenty-four Xuan Wei lung tumor tissues were collected to detect the expression level of mir-101 and enhancer of zeste homolog 2 (EZH2), which is the potential target of mir-101. The results showed that mir-101 was down-regulated and EZH2 were upregulated. Subsequently, the roles of mir-101 and EZH2 in tumor growth and progression in vitro were tested. Overexpression of mir-101 mimics was able to suppress the expression of EZH2 in XWLC-05 cells. And this resulted in the inhibited tumor cell growth and attenuated cell migration. The results in the present study showed that particle can induce the secretion of interleukin-1β. Interleukin-1β subsequently induces the downregulation of mir-101, which may result in the upregulated level of EZH2, and occurrence of lung cancer. We for the first time proposed the role interleukin-1β-mir-101-EZH2 axes in the particle-induced lung cancer. Further study may be needed to decipher the detailed mechanism involved.

Wild chrysanthemum extract prevents UVB radiation-induced acute cell death and photoaging

Wild chrysanthemum (Chrysanthemum indicum L.) is traditionally used in folk medicine as an anti-inflammatory agent. It is also used in the southwest plateau region of China to prevent ultraviolet-induced skin damage. However, the role and mechanism by which wild chrysanthemum prevents UV-induced skin damage and photoaging have never been investigated in vitro. In the present study, we found that aqueous extracts from wild chrysanthemum strongly reduced high-dose UVB-induced acute cell death of human immortalized keratinocytic HaCat cells. Wild chrysanthemum extract was also demonstrated to reduce low-dose UVB-induced expression of the photoaging-related matrix metalloproteinases MMP-2 and MMP-9. The ROS level elevated by UVB irradiation was strongly attenuated by wild chrysanthemum extract. Further study revealed that wild chrysanthemum extract reduced UVB-triggered ERK1/2 and p38 MAPK phosphorylation and their protective role, which is partially dependent on inhibiting p38 activation. These results suggest that wild chrysanthemum extract can protect the skin from UVB-induced acute skin damage and photoaging by reducing the intracellular reactive oxygen species (ROS) level and inhibiting p38 MAPK phosphorylation. The present study confirmed the protective role of wild chrysanthemum against UV-induced skin disorders in vitro and indicated the possible mechanism. Further study to identify the active components in wild chrysanthemum extract would be useful for developing new drugs for preventing and treating skin diseases, including skin cancer and photoaging, induced by UV irradiation.

Comprehensive transcriptome profiling and functional analysis of the frog (Bombina maxima) immune system

Amphibians occupy a key phylogenetic position in vertebrates and evolution of the immune system. But, the resources of its transcriptome or genome are still little now. Bombina maxima possess strong ability to survival in very harsh environment with a more mature immune system. We obtained a comprehensive transcriptome by RNA-sequencing technology. 14.3% of transcripts were identified to be skin-specific genes, most of which were not isolated from skin secretion in previous works or novel non-coding RNAs. 27.9% of transcripts were mapped into 242 predicted KEGG pathways and 6.16% of transcripts related to human disease and cancer. Of 39 448 transcripts with the coding sequence, at least 1501 transcripts (570 genes) related to the immune system process. The molecules of immune signalling pathway were almost presented, several transcripts with high expression in skin and stomach. Experiments showed that lipopolysaccharide or bacteria challenge stimulated pro-inflammatory cytokine production and activation of pro-inflammatory caspase-1. These frog's data can remarkably expand the existing genome or transcriptome resources of amphibians, especially immunity data. The entity of the data provides a valuable platform for further investigation on more detailed immune response in B. maxima and a comparative study with other amphibians.

Adenosine-5'-triphosphate (ATP) protects mice against bacterial infection by activation of the NLRP3 inflammasome

It has been established that Adenosine-5'-triphosphate (ATP) can activate the NLRP3 inflammasome. However, the physiological effect of extracellular ATP on NLRP3 inflammasome activation has not yet been investigated. In the present study, we found that ATP was indeed released during bacterial infection. By using a murine peritonitis model, we also found that ATP promotes the fight against bacterial infection in mice. ATP induced the secretion of IL-1β and chemokines by murine bone marrow-derived macrophages in vitro. Furthermore, the intraperitoneal injection of ATP elevated the levels of IL-1β and chemokines in the mouse peritoneal lavage. Neutrophils were rapidly recruited to the peritoneum after ATP injection. In addition, the effects on cytokine and chemokine secretion and neutrophil recruitment were markedly attenuated by the pre-administration of the caspase-1 inhibitor Ac-YVAD-cho. Ac-YVAD-cho also significantly attenuated the protective effect of ATP against bacterial infection. In the present study, we demonstrated a protective role for ATP during bacterial infection and this effect was related to NLRP3 inflammasome activation. Together, these results suggest a role for ATP in initiating the immune response in hosts suffering from infections.