Cytokine Expression and Glutamine Deficiency in Pulmonary Epithelial Cells Exposed to Mycoplasma pneumoniae

Abstract

Mycoplasma pneumoniae is one of the most frequent causes of respiratory disease. Glutamine consists of glutathione and its deficiency occurs during the periods of critical illness. Activation of Janus kinase (JAK)/Signal Transducers of Activated Transcription (STAT) has been involved in the expression of inflammatory cytokine IL‐8. The present study aims to investigate whether lipid‐associated membrane protein (LAMP) isolated from Mycoplasma pneumoniae induces IL‐8 expression with the activation of JAK/STAT, and whether glutamine deficiency aggravates LAMP‐induced IL‐8 induction in the human pulmonary epithelial A549 cells. As a result, LAMP increased IL‐8 expression in A549 cells, which was augmented in the absence of glutamine. LAMP‐induced activation of JAK2/STAT3 was potentiated in the cells cultured in the absence of glutamine. Glutamine supplementation inhibited JAK/STAT activation in the cells treated with LAMP and cultured in the absence of glutamine. The JAK2 inhibitor, AG490 inhibited LAMP‐induced activation of JAK/STAT3 and IL‐8 expression in A549 cells. In conclusion, LAMP of Mycoplasma pneumoniae induced IL‐8 expression mediated by JAK2/STAT3 activation in A549 cells. Glutamine deficiency augments LAMP‐induced signaling for IL‐8 expression in A549 cells. (LAMP is kindly provided from Drs. T. Shimizu and K. Kuwano, Kurume University School of Medicine, Japan)