Berberine hydrochloride inhibits inflammation and fibrosis after canalicular laceration repair in rabbits

Abstract

Aims

This study was designed to investigate the molecular mechanisms underlying the anti-inflammatory and anti-fibrosis effects of Berberine hydrochloride (BBR) following canalicular laceration (CL) surgical repair.

Main methods

We used a rabbit CL model in this study. BBR and the control medicine were administered during and after the surgical operation. The degree of fibrosis in the canaliculi was evaluated using hematoxylin and eosin and Masson's trichrome staining 7 days after the operation. Inflammation inside the canaliculi was observed using a transcanalicular endoscope. Expression levels of inflammatory cell cytokines [tumor growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), intracellular adhesion molecule-I (ICAM-1), and interleukin-β1 (IL-1β)] were detected using immunohistochemistry. P38 and ERK1 phosphorylation and activation were determined using western blot analysis.

Key findings

The degree of inflammation and fibrosis were less in the BBR groups compared to Surgery group. The anti-inflammatory and anti-fibrosis effects of BBR were concentration-dependent. The levels of TGF-β1, CTGF, ICAM-1, and IL-1β were significantly lower in the BBR groups compared to Surgery group. BBR reduced the phosphorylation of P38 compared to Surgery group.

Significance

In conclusion, this study shows that BBR can reduce local fibrosis after CL surgical repair via its anti-inflammatory and anti-fibrosis effects.

Introduction

Canalicular laceration (CL) is a common ocular trauma [[1], [2], [3], [4]], and canalicular repair surgery is a classic method for treating CL [2,[5], [6], [7]]. Postoperative excessive fibrotic cell proliferation can lead to stenosis or even obstruction of lacrimal canaliculi, which can lead to diminished surgical outcomes. In cases of old CL (OCL), excessive fibrous cell proliferation is more likely to occur after the operation.

In recent years, improved surgical procedures and technologies have resulted in reduced fibrous cell proliferation and scar formation, which are commonly observed following one-stitch anastomosis through the skin and lacrimal stent intubation [2,5,6,[8], [9], [10], [11], [12], [13], [14]]. However, the displacement and defect of the broken end of the lacerated canaliculus, especially in the old scar between the broken ends of an OCL, can still lead to obstruction between the broken ends after the repair, affecting the patency of the lacrimal passage. The histopathological features of canalicular obstruction include non-specific inflammation associated with fibrosis [15]. Because the lacrimal duct space is small, lacrimal duct stenosis or even obstruction due to fibrous cell proliferation is common after lacrimal drainage system reconstruction and recanalization surgery, which result in failure of the surgical procedure. An increasing number of strategies to reduce fibrosis are clinically available, including anti-inflammatory medicines and lacrimal irrigation. Certain drugs, such as corticosteroids, can inhibit fibrinolytic activity and promote adhesion formation [16], which might contribute to a high incidence of anastomotic leaks. Corticosteroid eye drops can also increase intraocular pressure, which could increase the risk of steroid-induced glaucoma. It has been recognized that post-operative lacrimal irrigation in combination with anti-inflammatory medicines can effectively reduce inflammation, inhibit scar formation, and improve the anatomical success rate after lacrimal duct operation [17]. However, lacrimal irrigation is not suitable immediately following repair surgery, and some patients are often unable to be irrigated regularly due to personal or regional reasons. Thus, there is an urgent need to identify an effective anti-inflammatory and anti-fibrosis treatment strategy following lacrimal duct reconstruction and recanalization surgery.

Berberine (5,6-dihydro-9,10 dimethoxybenzo[g]-1,3-benzodioxolo [5,6-a]quinolizinium, BBR) is an isoquinoline alkaloid present in several plants, including berberidaceae, papapveraceae, ranunculacese, rutaceae, menispermaceous, and rhamnacease. BBR is a component of Traditional Chinese Medicine [18,19], and is characterized by diverse pharmacological effects. It was first used to treat intestinal inflammation because of its significant anti-microbial activity and anti-inflammatory effects [20,21]. In addition to its anti-inflammatory properties, BBR has been shown to have anti-bacterial, anti-viral, anti-proliferative, anti-fibrosis, anti-tumor, and anti-adhesion properties; BBR has been used in clinical research for the treatment of cancer, diabetes, cardiovascular disease, ocular trachoma, and uveitis [19,20,[22], [23], [24], [25], [26], [27], [28], [29], [30]].

Transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF) are important cytokines in tissue fibrosis associated with many diseases. TGF-β1 has been known to induce expression of extracellular matrix (ECM) proteins promote, the production of protease inhibitors, and prevent ECM enzymatic breakdown [31,32]. CTGF has been reported to promote the synthesis of TGF-β1 in the ECM [31]. The present study was designed to investigate the effects of BBR on the expression of these cytokines during fibrosis and inflammation after canalicular repair surgery using a rabbit model. We further determined if BBR could be used as a potential treatment strategy to prevent fibrous cell proliferation and scar formation after lacrimal duct surgery. We hypothesized that BBR reduces inflammation and fibrosis, and that these effects are related to the inhibition of TGF-β1 and CTGF, as well other inflammatory markers, such as intracellular adhesion molecule-1 (ICAM-1) and interleukin-1β (IL-1β). We further speculated that the underlying mechanism of BBR's effects is dependent on the inhibition of the P38 and ERK1 signaling pathways.