LAUSR

Introduction Gossypol, a natural polyphenolic compound extracted from the cotton seed oil, have been reported to possess pharmacological properties via modulation of cell cycle and immune signalling pathway. However, whether gossypol has anti-inflammatory effects against phytohemagglutinin (PHA)-induced cytokine secretion in T lymphocytes through similar mechanism remains unclear. Material and methods Human T-cell leukaemia Jurkat cells were employed and cultured in the presence or absence of gossypol with or without PHA stimulation. The cell cycle was analysed by flow cytometry. The cytotoxicity was measured by evaluating lactate dehydrogenase (LDH) activity using LDH detecting kit. The protein expressions in Jurkat cell were analysed by Western blot assay. Total RNA from Jurkat cells were extracted and the gene-expressions were measured by real-time polymerase chain reaction technique. IL-2 levels were determined by an ELISA kit. Results and discussions Using the T lymphocytes Jurkat cell line, PHA exposure caused dramatically interleukin-2 (IL-2) mRNA expression as well as IL-2 secretion. All of these PHA-stimulated events were attenuated in a dose-dependent manner by pretreating with gossypol. However, gossypol did not show any in vitro cytotoxic effects at doses of 5–20 mM. As a possible mechanism underlying of gossypol action such as pronounced suppression of IL-2 release, we found robust decrease of PHA-induced phosphorylation of p38 and c-Jun N-terminal kinases (JNK) expressions after gossypol pretreatment, but not phosphorylation of extracellular signal-regulated kinase (ERK) expression. Furthermore, gossypol suppressed the Jurkat cells growth, which was associated with increased percentage of G1 phase and decreased fraction of G2 phase in flow cytometry test. Conclusion Gossypol exerts anti-inflammatory effects probably through partial attenuation of mitogen-activated protein kinase signalling and cell-cycle arrest in Jurkat cell.