The Effects of Systemic Infusion of Bradykinin on Experimental Peritoneal Fibrosis

ABSTRACT: Background. Bradykinin (BK) is a proinflammatory peptide that is involved in the inflammation and vascular regulation. Recent studies have indicated that stimulation of BK-B2 receptors may attenuate fibrosis in renal and liver injuries and it is also expressed on neutrophils.Objectives. The aim of this study is to investigate the expression of bradykinin-B2 receptors and to explore the effects of systemic infusion of bradykinin (BK) using histochemical and immunohistochemical methods in a rodent model of chlorhexidine gluconate-induced peritoneal fibrosis.Materials and Methods. In this experimental study, twenty-four male Sprague-Dawley rats (n=24) were divided into three groups; Control, Chlorhexidine Gluconate (CG) and Chlorhexidine Gluconate+Bradykinin treatment (CG+BK). All animals were euthanized at day 21 and peritoneal tissue samples were taken under anesthesia induced by 50 mg/kg s.c. sodium pentothal. Histological assessments were then performed using hematoxylin and eosin, Periodic Acid-Schiff staining; and antibodies against TGF-β1, MMP-2, PAI-1 and bradykinin-B2 (BK-B2) receptors.Results. Thickness of submesothelial layer, neovascularization, polimorphonuclear granulocytes and fibrosis increased in the CG+BK treatment group. While expression of TGF-β1, MMP-2 and PAI-1 was not significantly different than that of the CG group. Staining of BK-B2 receptors was up-regulated in the submesothelial compact zone of the CG+BK treatment group.Conclusions. The results of our study showed that the stimulation of BK-B2 receptors by systemic BK perfusion did not have any antifibrotic effects in the encapsulating peritoneal sclerosis rat models, and actually, it may even promote fibrosis by aggravating inflammation. KEY WORDS: peritoneal fibrosis, TGF-β1, MMP-2, PAI-1, BK-B2 receptors OZET: Bu calismanin amaci klorheksidin glukonat ile olusturulan rodent peritoneal fibrozis modelinde bradikinin-B2 reseptor ekspresyonunun arastirilmasi ve sistemik bradikinin infuzyonunun etkisinin histokimyasal ve immunhistokimyasal metodlarla ortaya konulmasidir. Bu deneysel calismada, 24 Sprague-Dawley cinsi rat 3 gruba ayrildi; Kontrol, Klorheksidin Glukonat (KG) ve Klorheksidin Glukonat + Bradikinin tedavisi (KG+BK). Kontrol grubunda ratlara gunluk serum fizyolojik (10 mL/kg i.p.) verildi. KG ve KG+BK gruplarinda peritoneal fibrozis, 3 hafta boyunca gunluk, 10mL/kg dozunda serum fizyolojik icinde cozulen %0.1 KG ve %15 etanol i.p. enjeksiyonlari ile olusturuldu. KG grubunda ratlara serum fizyolojik infuzyonu (0.25 µL/h) verilirken, KG+BK tedavisi grubunda ratlara 3 hafta boyunca ozmotik mini pompalar vasitasiyla serum fizyolojik icinde cozulmus bradikinin (100 ng/kg/min) subkutan verildi. Tum hayvanlar i.p. enjeksiyonlarinin 21. Gununde, onceki gece yiyecek ve su kesildikten sonra 50mg/kg s.c. sodyum pentotal anestezisi altinda sakrifiye edildi ve peritoneal ornekler alindi. Histolojik degerlendirme hematoksilen- eozin ve Periodik Acid-Schiff boyalari kullanilarak; immunhistolojik degerlendirme TGF-β1, MMP-2, PAI-1 ve bradikinin-B2 (BK-B2) reseptorleri antikorlari kullanilarak isik mikroskobisi altinda yapildi. Submezotelyal tabakanin kalinligi, neovaskularizasyon, polimorfonukleer granulositler ve fibrozis KG+BK tedavisi grubunda artmisken, TGF-β1, MMP-2 ve PAI-1 ekspresyonu KG grubuna kiyasla anlamli bir farklilik gostermedi. BK-B2 reseptor boyamasi KG+BK tedavi grubunda submezotelyal kompakt zonda artmisti. Calismamizin sonuclari sistemik BK perfuzyonu ile stimule edilen BK-B2 reseptorlerinin enkapsule peritoneal sklerozis rat modelinde herhangi bir antifibrotik etkilerinin olmadigini ve aslinda inflamasyonu daha da artirarak fibrozisi daha da artirabilecegini gostermektedir. ANAHTAR KELIMELER: bradikinin, klorheksidin glukonat, peritoneal fibrozis, TGF-β1, MMP-2, PAI-1, BK-B2 reseptorleri, rat