NADPH oxidase plays a crucial role in the activation of pancreatic stellate cells

Abstract

Activated pancreatic stellate cells (PSCs) play an important role in pancreatic fibrosis and inflammation, where oxidative stress is implicated in the pathogenesis. NADPH oxidase might be a source of reactive oxygen species (ROS) in the injured pancreas. This study aimed to clarify the expression and regulation of cell functions by NADPH oxidase in PSCs. PSCs were isolated from rat and human pancreas tissues. Expression of NADPH oxidase was assessed by reverse transcription-PCR and immunostaining. Intracellular ROS production was assessed using 2′,7′-dichlorofluorescin diacetate. The effects of diphenylene iodonium (DPI) and apocynin, inhibitors of NADPH oxidase, on key parameters of PSC activation were evaluated in vitro. In vivo, DPI (at 1 mg·kg body wt−1·day−1) was administered in drinking water to 10-wk-old male Wistar Bonn/Kobori rats for 10 wk and to rats with chronic pancreatitis induced by dibutyltin dichloride (DBTC). PSCs expressed key components of NADPH oxidase (p22phox, p47phox, NOX1, gp91phox/NOX2, NOX4, and NOX activator 1). PDGF-BB, IL-1β, and angiotensin II induced ROS production, which was abolished by DPI and apocynin. DPI inhibited PDGF-induced proliferation, IL-1β-induced chemokine production, and expression of α-smooth muscle actin and collagen. DPI inhibited transformation of freshly isolated cells to a myofibroblast-like phenotype. In addition, DPI inhibited the development of pancreatic fibrosis in Wistar Bonn/Kobori rats and in rats with DBTC-induced chronic pancreatitis. In conclusion, PSCs express NADPH oxidase to generate ROS, which mediates key cell functions and activation of PSCs. NADPH oxidase might be a potential target for the treatment of pancreatic fibrosis.

Isolation and characterization of islet stellate cells in rat

“…[13][14][15][16][17][18] The precise mechanisms underlying islet fibrosis are largely unknown, although the deposition of islet amyloid, activation of RAS and oxidative stress have all been implicated. 16,17,[28][29][30] Our demonstration of a specialized ISC population in rodent islets is consistent with an important role for these cells in islet fibrosis, in an analogous manner to that of classical PSCs in pancreatic fibrosis. 11,25,26 This proposal is supported by several recent studies suggesting that ISCs might play an important role in islet fibrosis in T2DM.…”

“…22 The diabetic environment provides numerous signals which could lead to stellate cell activation. Thus, previous studies using classical PSCs have demonstrated that hyperglycemia, 16,31 activation of the RAS, 32 oxidative stress, 17,30 platelet-derived growth factors, 33 and inflammatory cytokines 34 all enhance PSC activation and proliferation. The environment of the diabetic islet is characterized by the presence of the hyperglycemia [35][36][37] and oxidative stress, [38][39][40] as well as macrophage infiltration and increased expression of inflammatory molecules such as IL-1, IL-6, TNF-α, MCP-1, and MIP-1α.…”

“…11,25,26 This proposal is supported by several recent studies suggesting that ISCs might play an important role in islet fibrosis in T2DM. 16,20,21,29,30 For example, increased ISCs have been detected in pancreatic islets in patients with T2DM. Similarly, in several studies using different animal models of T2DM, treatments to suppress islet fibrosis and improve β-cell function were associated with significant reductions in the numbers of intraislet stellate cells.…”

NOX Enzymes and Pulmonary Disease

“…Other NOX isoforms that are reported to contribute to tissue fibrosis in nonpulmonary organ systems include NOX1 (4,75,112,139) and NOX2 (67,75,89,112,143). A p47 phox -requiring NOX isoform is required for the development of fibrosis in a murine lung-injury model that is inflammation dependent, and the observed protection in p47 phoxÀ=À mice is associated with enhanced neutrophilic inflammation and matrix metalloproteinase (MMP)-9 activity (70).…”

Apocynin decreases hydrogen peroxide and nirtate concentrations in exhaled breath in healthy subjects

“…Although therapeutic strategies focusing on the elimination of superoxide have been developed in animal models and in clinical cases, the effects of such reagents are still unclear [11,[30][31][32]. Therefore, in this study, we investigated whether inhalation of apocynin may influence hydrogen peroxide, nitrite and nitrate concentrations in airways in healthy subjects.…”