Sosroseno W, Musa M, Ravichandran M, Fikri Ibrahim M, Bird P S, Seymour G J
Department of Oral Biology, School of Dental Sciences, Universiti Sains Malaysia, Kota Bharu, Malaysia.
Oral Microbiol Immunol. 2006 Dec;21(6):347-52. doi: 10.1111/j.1399-302X.2006.00300.x.
The aim of the present study was to determine the role of cyclic adenosine monophosphate (cAMP) on arginase activity in a murine macrophage cell line (RAW264.7 cells) stimulated with lipopolysaccharide (LPS) from Actinobacillus actinomycetemcomitans.
The cells were treated with A. actinomycetemcomitans LPS for 24 h. The effects of SQ22536 (an adenylyl cyclase inhibitor), ODQ (a guanylyl cyclase inhibitor), dibutyryl cAMP (a cAMP analog), 8-bromo cyclic guanosine monophosphate (a cGMP analog), forskolin (an adenylyl cylase activator), and cycloheximide (a protein synthesis inhibitor) on arginase activity in A. actinomycetemcomitans LPS-stimulated RAW264.7 cells were also determined. Arginase activity was assessed in LPS-stimulated cells in the presence of 3-isobutyl-1-methylxanthine (IBMX), siguazodan and rolipram [phosphodiesterase (PDE) inhibitors] as well as KT5720 [a protein kinase A (PKA) inhibitor].
Arginase activity in A. actinomycetemcomitans LPS-stimulated RAW264.7 cells was suppressed by SQ22536 but not ODQ. Enhancement of arginase activity was observed in the presence of cAMP analog or forskolin but not cGMP analog. Cycloheximide blocked arginase activity in the cells in the presence of cAMP analog or forskolin with or without A. actinomycetemcomitans LPS. IBMX augmented arginase activity in A. actinomycetemcomitans LPS-stimulated cells. Rolipram (a PDE4 inhibitor) increased the levels of arginase activity higher than siguazodan (a PDE3 inhibitor) in the antigen-stimulated cells. The effect of cAMP analog or forskolin on arginase activity in the presence or absence of A. actinomycetemcomitans LPS was blocked by the PKA inhibitor (KT5720).
The results of the present study suggest that A. actinomycetemcomitans LPS may stimulate arginase activity in murine macrophages (RAW264.7 cells) in a cAMP-PKA-dependent pathway.
本研究旨在确定环磷酸腺苷（cAMP）在受放线放线杆菌脂多糖（LPS）刺激的小鼠巨噬细胞系（RAW264.7细胞）中对精氨酸酶活性的作用。
细胞用放线放线杆菌LPS处理24小时。还测定了SQ22536（一种腺苷酸环化酶抑制剂）、ODQ（一种鸟苷酸环化酶抑制剂）、二丁酰cAMP（一种cAMP类似物）、8-溴环鸟苷单磷酸（一种cGMP类似物）、福斯可林（一种腺苷酸环化酶激活剂）和环己酰亚胺（一种蛋白质合成抑制剂）对受放线放线杆菌LPS刺激的RAW264.7细胞中精氨酸酶活性的影响。在存在3-异丁基-1-甲基黄嘌呤（IBMX）、西呱唑旦和咯利普兰[磷酸二酯酶（PDE）抑制剂]以及KT5720[一种蛋白激酶A（PKA）抑制剂]的情况下，评估LPS刺激细胞中的精氨酸酶活性。
SQ22536可抑制受放线放线杆菌LPS刺激的RAW264.7细胞中的精氨酸酶活性，但ODQ无此作用。在存在cAMP类似物或福斯可林时观察到精氨酸酶活性增强，但cGMP类似物无此作用。无论有无放线放线杆菌LPS，环己酰亚胺在存在cAMP类似物或福斯可林时均可阻断细胞中的精氨酸酶活性。IBMX可增强受放线放线杆菌LPS刺激细胞中的精氨酸酶活性。在抗原刺激的细胞中，咯利普兰（一种PDE4抑制剂）比西呱唑旦（一种PDE3抑制剂）使精氨酸酶活性水平升高得更多。PKA抑制剂（KT5720）可阻断cAMP类似物或福斯可林在有无放线放线杆菌LPS情况下对精氨酸酶活性的影响。
本研究结果表明，放线放线杆菌LPS可能通过cAMP-PKA依赖性途径刺激小鼠巨噬细胞（RAW264.7细胞）中的精氨酸酶活性。
