Al-Kofahi M, Becker F, Gavins F N E, Woolard M D, Tsunoda I, Wang Y, Ostanin D, Zawieja D C, Muthuchamy M, von der Weid P Y, Alexander J S
Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center - Shreveport, Shreveport, LA, USA.
Department for General and Visceral Surgery, University Hospital Muenster, Muenster, Germany.
Br J Pharmacol. 2015 Aug;172(16):4038-51. doi: 10.1111/bph.13194. Epub 2015 Jul 6.
The lymphatic system maintains tissue homeostasis by unidirectional lymph flow, maintained by tonic and phasic contractions within subunits, 'lymphangions'. Here we have studied the effects of the inflammatory cytokine IL-1β on tonic contraction of rat mesenteric lymphatic muscle cells (RMLMC).
We measured IL-1β in colon-conditioned media (CM) from acute (AC-CM, dextran sodium sulfate) and chronic (CC-CM, T-cell transfer) colitis-induced mice and corresponding controls (Con-AC/CC-CM). We examined tonic contractility of RMLMC in response to CM, the cytokines h-IL-1β or h-TNF-α (5, 10, 20 ng·mL(-1) ), with or without COX inhibitors [TFAP (10(-5) M), diclofenac (0.2 × 10(-5) M)], PGE2 (10(-5) M)], IL-1-receptor antagonist, Anakinra (5 μg·mL(-1) ), or a selective prostanoid EP4 receptor antagonist, GW627368X (10(-6) and 10(-7) M).
Tonic contractility of RMLMC was reduced by AC- and CC-CM compared with corresponding control culture media, Con-AC/CC-CM. IL-1β or TNF-α was not found in Con-AC/CC-CM, but detected in AC- and CC-CM. h-IL-1β concentration-dependently decreased RMLMC contractility, whereas h-TNF-α showed no effect. Anakinra blocked h-IL-1β-induced RMLMC relaxation, and with AC-CM, restored contractility to RMLMC. IL-1β increased COX-2 protein and PGE2 production in RMLMC.. PGE2 induced relaxations in RMLMC, comparable to h-IL-1β. Conversely, COX-2 and EP4 receptor inhibition reversed relaxation induced by IL-1β.
The IL-1β-induced decrease in RMLMC tonic contraction was COX-2 dependent, and mediated by PGE2 . In experimental colitis, IL-1β and tonic lymphatic contractility were causally related, as this cytokine was critical for the relaxation induced by AC-CM and pharmacological blockade of IL-1β restored tonic contraction.
淋巴系统通过单向淋巴流动维持组织内环境稳定，这种单向流动由亚单位“淋巴管节”内的强直性和阶段性收缩维持。在此，我们研究了炎性细胞因子白细胞介素 -1β（IL-1β）对大鼠肠系膜淋巴管平滑肌细胞（RMLMC）强直性收缩的影响。
我们检测了急性（AC-CM，葡聚糖硫酸钠诱导）和慢性（CC-CM，T细胞转移诱导）结肠炎小鼠结肠条件培养基（CM）及相应对照（Con-AC/CC-CM）中的IL-1β。我们研究了RMLMC对CM、细胞因子人IL-1β或人肿瘤坏死因子-α（TNF-α）（5、10、20 ng·mL⁻¹）的强直性收缩反应，同时加入或不加入环氧化酶抑制剂[三氟乙酸苯酯（TFAP，10⁻⁵ M）、双氯芬酸（0.2×10⁻⁵ M）]、前列腺素E2（PGE2，10⁻⁵ M）、IL-1受体拮抗剂阿那白滞素（5 μg·mL⁻¹）或选择性前列腺素EP4受体拮抗剂GW627368X（10⁻⁶和10⁻⁷ M）。
与相应对照培养基Con-AC/CC-CM相比，AC-CM和CC-CM降低了RMLMC的强直性收缩。在Con-AC/CC-CM中未检测到IL-1β或TNF-α，但在AC-CM和CC-CM中可检测到。人IL-1β浓度依赖性地降低RMLMC收缩力，而人TNF-α无此作用。阿那白滞素可阻断h-IL-1β诱导的RMLMC舒张，并且与AC-CM共同作用可恢复RMLMC的收缩力。IL-1β可增加RMLMC中COX-2蛋白表达和PGE2生成。PGE2诱导RMLMC舒张，其作用与h-IL-1β相当。相反，COX-2和EP4受体抑制可逆转IL-1β诱导的舒张。
IL-1β诱导的RMLMC强直性收缩降低依赖于COX-2，并由PGE2介导。在实验性结肠炎中，IL-1β与淋巴管强直性收缩存在因果关系，因为该细胞因子对AC-CM诱导的舒张至关重要，并且对IL-1β的药理阻断可恢复强直性收缩。
