Fang Cheng-Chung, Lai Ming-Nan, Chien Chiang-Ting, Hung Kuan-Yu, Tsai Chien-Chen, Tsai Tun-Jun, Hsieh Bor-Shen
Department of Emergency Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan, Republic of China.
Perit Dial Int. 2003 May-Jun;23(3):228-36.
Peritoneal fibrosis is a long-term complication following continuous ambulatory peritoneal dialysis (CAPD). Peritoneal fibroblasts may play an important role in peritoneal fibrosis. Up to now, the treatment of peritoneal fibrosis in patients with CAPD remains unsatisfactory. Pentoxifylline (PTX) is a xanthine derivative and is used in the treatment of peripheral vascular and cerebrovascular diseases. Several studies have demonstrated that PTX can ameliorate fibrosis of the skin, liver, and kidney.
To investigate the effect of PTX on in vitro growth and collagen synthesis of human peritoneal fibroblasts (HPFBs), and to evaluate the effects of PTX on silica-induced peritoneal fibrosis in vivo.
In the in vitro study, HPFBs were cultured from human omentum. The effect of PTX on the growth of serum-stimulated HPFBs was evaluated by MTT assay. The effect of PTX on the collagen synthesis of HPFB was measured by [3H]-proline incorporation. Expression of type I and type III collagen mRNA was evaluated by Northern blotting. The effects of PTX on matrix metalloproteinase (MMP) activity and cAMP level in HPFBs were measured by immunoassays. In the in vivo study, Wistar rats were randomly divided into five groups. All rats received intraperitoneal (IP) injection of silica suspension (250 mg/100 g body weight) on day 0. The rats of group 1 (control group) were injected with vehicle IP every day for 14 days. The rats of groups 2, 3, and 4 were injected with PTX (4 mg/100 g body weight) IP every day for 3, 7, and 14 days, respectively. The rats in group 5 received an intravenous infusion of PTX (8 mg/100 g body weight) every day for 7 days. On the 15th day after silica injection, all rats were sacrificed. Their parietal and visceral peritoneums were removed and processed for pathology, and the severity of fibrosis was measured and scored.
In vitro, PTX inhibited serum-stimulated HPFB growth (maximum was 93% at 1 mg PTX/mL) in a dose-dependent manner. Collagen synthesis by HPFB was reduced (47% at 1 mg PTX/mL), and collagen I and III mRNA expression in HPFBs was suppressed by PTX. The PTX did not affect the MMP (including MMP-1, MMP-8, and MMP-13) activities of HPFBs. The mechanism of PTX was through increasing cAMP by its phosphodiesterase inhibiting activity. In vivo, the severity of fibrosis was significantly reduced in groups 4 and 5 compared to group 1 (p < 0.05).
These results suggest that PTX can inhibit growth of and collagen synthesis by HPFBs in vitro. The fibrosis derived from silica-induced peritonitis in vivo was also ameliorated by PTX. Therefore, pentoxifylline may have the potential to be used to treat peritoneal fibrosis in patients on CAPD.
腹膜纤维化是持续性非卧床腹膜透析（CAPD）后的一种长期并发症。腹膜成纤维细胞可能在腹膜纤维化中起重要作用。到目前为止，CAPD患者腹膜纤维化的治疗仍不尽人意。己酮可可碱（PTX）是一种黄嘌呤衍生物，用于治疗外周血管和脑血管疾病。多项研究表明，PTX可改善皮肤、肝脏和肾脏的纤维化。
研究PTX对人腹膜成纤维细胞（HPFBs）体外生长和胶原合成的影响，并评估PTX对体内二氧化硅诱导的腹膜纤维化的作用。
在体外研究中，从人网膜培养HPFBs。通过MTT法评估PTX对血清刺激的HPFBs生长的影响。通过[3H]-脯氨酸掺入法测量PTX对HPFB胶原合成的影响。通过Northern印迹法评估I型和III型胶原mRNA的表达。通过免疫测定法测量PTX对HPFBs中基质金属蛋白酶（MMP）活性和cAMP水平的影响。在体内研究中，将Wistar大鼠随机分为五组。所有大鼠在第0天接受腹腔内（IP）注射二氧化硅悬浮液（250 mg/100 g体重）。第1组（对照组）大鼠每天腹腔注射赋形剂，共14天。第2、3和4组大鼠分别每天腹腔注射PTX（4 mg/100 g体重），持续3、7和14天。第5组大鼠每天静脉输注PTX（8 mg/100 g体重），持续7天。在注射二氧化硅后的第15天，处死所有大鼠。取出它们的壁层和脏层腹膜进行病理处理，并测量和评估纤维化的严重程度。
在体外，PTX以剂量依赖性方式抑制血清刺激的HPFBs生长（在1 mg PTX/mL时最大抑制率为93%）。PTX降低了HPFB的胶原合成（在1 mg PTX/mL时降低47%），并抑制了HPFBs中I型和III型胶原mRNA的表达。PTX不影响HPFBs的MMP（包括MMP-1、MMP-8和MMP-13）活性。PTX的作用机制是通过其磷酸二酯酶抑制活性增加cAMP。在体内，与第1组相比，第4组和第5组的纤维化严重程度显著降低（p < 0.05）。
这些结果表明，PTX在体外可抑制HPFBs的生长和胶原合成。PTX也改善了体内二氧化硅诱导的腹膜炎所致的纤维化。因此，己酮可可碱可能有潜力用于治疗CAPD患者的腹膜纤维化。
