Effects of electromagnetic fields on the metabolism of lubricin of rat chondrocytes

Electric field induced the changes in structure and function of human transforming growth factor beta receptor type I: from molecular dynamics to docking

The transforming growth factor beta (TGF-β) signaling pathway is believed to play essential roles in several physiological activities, including cancer. TGF-β receptor type I (TBR-I) is a key membrane receptor protein in the TGF-β signaling pathway, which relates to many intracellular biological effects. In recent years, cold atmospheric plasma (CAP) has been found to have promising prospects in selective anticancer therapy and has confirmed its essential role in the TGF-β signaling pathway. However, the ambiguous effect of CAP-induced electric field (EF) on TBR-I still limits the application of CAP in clinical therapy. Molecular dynamics is applied to assess the effect of EF on the structure of the extracellular domain of TBR-I using a series of indicators and methods, and then we discuss the ligand binding ability of TBR-I. Results show that moderate EF intensities' structural restraints may contribute to the structural stability and ligand-binding ability of TBR-I, but an EF higher than 0.1 V/nm will be harmful. What's more, EF induces a change in the docking interface of TBR-I, showing the conformation and position of special sequences of residues decide the ligand binding surface. The relevant results suggest that CAP-induced EF plays a crucial role in receptor-receptor interaction and provides significant guidelines for EF-related anticancer therapy.Communicated by Ramaswamy H. Sarma.

Reduction of Smad2 caused by oxidative stress leads to necrotic death of hypertrophic chondrocytes associated with an endemic osteoarthritis

OBJECTIVE

The occurrence and development of an endemic OA, Kashin-Beck disease (KBD), is closely related to oxidative stress induced by free radicals. The aim of the study was to find the key signalling molecules or pathogenic factors as a potential treatment strategy for KBD.

METHODS

Real-time PCR and western blotting were performed to detect the mRNA and protein expression levels in cells and tissues. Immunohistochemical staining was assayed in rat models and human samples obtained from children. The type of cell death was identified by annexin V and propidium iodide staining with flow cytometry.

RESULTS

Oxidative stress decreased levels of Smad2 and Smad3 in hypertrophic chondrocytes both in vitro and in vivo. In the cartilage of KBD patients, the expression of Smad2 and Smad3 proteins in the middle and deep zone was significantly decreased with an observed full deletion in the deep zone of some samples. Reduction of Smad2 protein induced necrotic death of hypertrophic chondrocytes, while reduction of Smad3 protein induced apoptosis. The reduction of Smad2 protein was not accompanied by Smad3 protein reduction in hypertrophic chondrocyte necrosis. Furthermore, the reduction of Smad2 also impaired the construction of tissue-engineered cartilage in vitro.

CONCLUSION

These studies reveal that oxidative stress causes necrosis of hypertrophic chondrocytes by downregulating Smad2 protein, which increases the pathogenesis of KBD cartilage. The importance of Smad2 in the development of KBD provides a new potential target for the treatment of KBD.

A review on the effects of extremely low frequency electromagnetic field (ELF-EMF) on cytokines of innate and adaptive immunity

Extremely low frequency electromagnetic field (ELF-EMF) is produced extensively in modern technologies. Numerous in vitro and in vivo studies have shown that ELF-EMF has both stimulatory and inhibitory effects on the immune system response. This review was conducted on effects of ELF-EMF on cytokines of innate and adaptive immunity. Mechanisms of ELF-EMF, which may modulate immune cell responses, were also studied. Physical and biological parameters of ELF-EMF can interact with each other to create beneficial or harmful effect on the immune cell responses by interfering with the inflammatory or anti-inflammatory cytokines. According to the studies, it is supposed that short-term (2-24 h/d up to a week) exposure of ELF-EMF with strong density may increase innate immune response due to an increase of innate immunity cytokines. Furthermore, long-term (2-24 h/d up to 8 years) exposure to low-density ELF-EMF may cause a decrease in adaptive immune response, especially in T_h1 subset.

Effect of a low-frequency pulsed electromagnetic field on expression and secretion of IL-1β and TNF-α in nucleus pulposus cells

Objective

To investigate changes in nucleus pulposus cell expression and secretion of interleukin (IL)-1β and tumour necrosis factor (TNF)-α following stimulation with a low-frequency (LF) pulsed electromagnetic field (PEMF).

Methods

Primary rat nucleus pulposus cells were isolated and cultured in vitro, followed by stimulation with LF-PEMFs at a frequency of 2 Hz and different intensities, ranging from 0.5–3.0 A/m. Cells were observed for morphological changes, and proliferation rates were measured by cell viability counts. Expression of IL-1β and TNF-α within the nucleus pulposus cells was measured using western blotting, and levels of IL-1β and TNF-α secreted in the culture media were measured using enzyme-linked immunosorbent assay.

Results

Stimulation of nucleus pulposus cells with LF-PEMFs did not appear to affect cell morphology or nucleus pulposus cell IL-1β and TNF-α expression levels. LF-PEMFs did not significantly affect cell proliferation, however, levels of IL-1β and TNF-α secreted into the culture media were found to be significantly reduced in an intensity-dependent manner.

Conclusion

Low-frequency PEMF stimulation may inhibit secretion of IL-1β and TNF-α in cultured nucleus pulposus cells.