Fei Ling Wong's research while affiliated with National University of Singapore and other places

Hydrogen sulfide (H2S) is a naturally occurring gas with potent vasodilator activity. Cystathionine‐γ‐lyase (CSE) and cystathionine‐β‐synthase (CBS) utilize l‐cysteine as substrate to form H2S. Of these two enzymes, cystathionine‐γ‐lyase (CSE) is believed to be the key enzyme that forms H2S in the cardiovascular system. Whilst H2S has been reported to relax precontracted rat arteries in vitro and to lower blood pressure in the rat, its effect in an inflammatory condition such as acute pancreatitis has not previously been reported. In this paper, we report the presence of H2S synthesizing enzyme activity and CSE (as determined by mRNA signal) in the pancreas. Also, prophylactic, as well as therapeutic, treatment with the CSE inhibitor, DL‐propargylglycine (PAG), significantly reduced the severity of caerulein‐induced pancreatitis and associated lung injury, as determined by 1) hyperamylasemia [plasma amylase (U/L) (control, 1204±59); prophylactic treatment: placebo, 10635±305; PAG, 7904±495; therapeutic treatment: placebo, 10427±470; PAG, 7811±428; P<0.05 PAG c.f. placebo; n=24 animals in each group]; 2) neutrophil sequestration in the pancreas [pancreatic myeloperoxidase oxidase (MPO) activity (fold increase over control) (prophylactic treatment: placebo, 5.78±0.63; PAG, 2.97±0.39; therapeutic treatment: placebo, 5.48±0.52; PAG, 3.03±0.47; P<0.05 PAG c.f. placebo; n=24 animals in each group)]; 3) pancreatic acinar cell injury/necrosis; 4) lung MPO activity (fold increase over control) [prophylactic treatment: placebo, 1.99±0.16; PAG, 1.34±0.14; therapeutic treatment: placebo, 2.03±0.12; PAG, 1.41±0.97; P<0.05 PAG c.f. placebo; n=24 animals in each group]; and 5) histological evidence of lung injury. These effects of CSE blockade suggest an important proinflammatory role of H2S in regulating the severity of pancreatitis and associated lung injury and raise the possibility that H2S may exert similar activity in other forms of inflammation.

Earlier studies have shown that mice deficient in NK1 receptors or its ligand, substance P, are protected against acute pancreatitis and associated lung injury. In the current study, the protective effect of NK1 receptor blockage against acute pancreatitis and associated lung injury was investigated, using a specific receptor antagonist, CP-96345. Acute pancreatitis was induced in mice by intraperitoneal (i.p.) injections of caerulein. Substance P levels in plasma, pancreas, and lungs were found to be elevated in a caerulein dose-dependent manner. Mice treated with CP-96345, either prophylactically, or therapeutically, were protected against acute pancreatitis and associated lung injury as evident by attenuation in plasma amylase, pancreatic and pulmonary myeloperoxidase activities, and histological evidence of pancreatic and pulmonary injuries. Pulmonary microvascular permeability was also reduced as a result of CP-96345 treatment. These results point to a key role of NK1 receptors in acute pancreatitis and associated lung injury.

Acute pancreatitis is a common clinical condition. It is a disease of variable severity in which some patients experience mild, self-limited attacks while others manifest a severe, highly morbid, and frequently lethal attack. The exact mechanisms by which diverse etiological factors induce an attack are still unclear. It is generally believed that the earliest events in acute pancreatitis occur within acinar cells. Acinar cell injury early in acute pancreatitis leads to a local inflammatory reaction. If this inflammatory reaction is marked, it leads to a systemic inflammatory response syndrome (SIRS). An excessive SIRS leads to distant organ damage and multiple organ dysfunction syndrome (MODS). MODS associated with acute pancreatitis is the primary cause of morbidity and mortality in this condition. Recent studies have established the role played by inflammatory mediators in the pathogenesis of acute pancreatitis and the resultant MODS. At the same time, recent research has demonstrated the importance of acinar cell death in the form of apoptosis and necrosis as a determinant of pancreatitis severity. In this review, we will discuss about our current understanding of the pathophysiology of acute pancreatitis.