A Mini-Review on the Effect of Docosahexaenoic Acid (DHA) on Cerulein-Induced and Hypertriglyceridemic Acute Pancreatitis

Saikosaponin d protects pancreatic acinar cells against cerulein-induced pyroptosis through alleviating mitochondrial damage and inhibiting cGAS-STING pathway

Acute pancreatitis represents an inflammatory disease featuring pancreatic necrosis and inflammation. Inflammatory injury of pancreatic acinar cells (PACs) is critically involved in the initiation and progression of acute pancreatitis. Pyroptosis, a new kind of programmed cell death concomitant with a low-grade inflammatory reaction, plays a function in acute pancreatitis pathology. It is unclear whether saikosaponin d (SSd), a pharmacologically active natural product, could protect PACs by regulating pyroptosis. Here, we established a PAC injury model in vitro using cerulein to treat AR42J cells. SSd restored viability and proliferation and lowered the release of pancreatic enzymes and inflammatory interleukins in cerulein-treated AR42J cells. Cerulein-induced pyroptosis was evidenced by typical ultrastructural changes and NLRP3/caspase-1 activation in AR42J cells, but SSd attenuated cerulein-induced pyroptosis and inhibited NLRP3/caspase-1 pathway. Mechanically, SSd reduced mitochondrial damage and mtDNA release, and blocked cGAS-STING signaling in AR42J cells treated with cerulein, contributing to the inhibition of NLRP3-mediated pyroptosis. Furthermore, SSd abolished cerulein-elevated oxidative stress in AR42J cells, leading to the mitigation of mitochondrial damage and inhibition of cGAS-STING signaling and pyroptosis. In conclusion, SSd protected PACs against cerulein-induced pyroptosis by alleviating mitochondrial damage and inhibiting the cGAS-STING pathway, and it could be a therapeutic candidate for acute pancreatitis.

Pancreatic Ubap2 deletion regulates glucose tolerance, inflammation, and protection from cerulein-induced pancreatitis

Ubiquitin-binding associated protein 2 (UBAP2) is reported to promote macropinocytosis and pancreatic adenocarcinoma (PDAC) growth, however, its role in normal pancreatic function remains unknown. We addressed this knowledge gap by generating UBAP2 knockout (U2KO) mice under a pancreas-specific Cre recombinase (Pdx1-Cre). Pancreatic architecture remained intact in U2KO animals, but they demonstrated slight glucose intolerance compared to controls. Upon cerulein challenge to induce pancreatitis, U2KO animals had reduced levels of several pancreatitis-relevant cytokines, amylase and lipase in the serum, reduced tissue damage, and lessened neutrophil infiltration into the pancreatic tissue. Mechanistically, cerulein-challenged U2KO animals revealed reduced NF-κB activation compared to controls. In vitro promoter binding studies confirmed the reduction of NF-κB binding to its target molecules supporting UBAP2 as a new regulator of inflammation in pancreatitis and may be exploited as a therapeutic target in future to inhibit pancreatitis.

The role of high serum triglyceride levels on pancreatic necrosis development and related complications

BACKGROUND

The relevance of elevated serum triglyceride (TG) levels in the early stages of acute pancreatitis (AP) not induced by hypertriglyceridemia (HTG) remains unclear. Our study aims to determine the role of elevated serum TG levels at admission in developing pancreatic necrosis.

METHODS

We analyzed the clinical data collected prospectively from patients with AP. According to TG levels measured in the first 24 h after admission, we stratified patients into four groups: Normal TG (< 150 mg/dL), Borderline-high TG (150-199 mg/dL), High TG (200-499 mg/dL) and Very high TG (≥ 500 mg/dL). We analyzed the association of TG levels and other risk factors with the development of pancreatic necrosis.

RESULTS

A total of 211 patients were included. In the Normal TG group: 122, in Borderline-high TG group: 38, in High TG group: 44, and in Very high TG group: 7. Pancreatic necrosis developed in 29.5% of the patients in the Normal TG group, 26.3% in the Borderline-high TG group, 52.3% in the High TG group, and 85.7% in the Very high TG group. The trend analysis observed a significant association between higher TG levels and pancreatic necrosis (p = 0.001). A multivariable analysis using logistic regression showed that elevated TG levels ≥ 200 mg/dL (High TG and Very high TG groups) were independently associated with pancreatic necrosis (OR: 3.27, 95% CI - 6.27, p < 0.001).

CONCLUSIONS

An elevated TG level at admission ≥ 200 mg/dl is independently associated with the development of pancreatic necrosis. The incidence of pancreatic necrosis increases proportionally with the severity of HTG.

Ginsenoside Rg3 ameliorates acute pancreatitis by activating the NRF2/HO‑1‑mediated ferroptosis pathway

Acute pancreatitis (AP) is an inflammatory disorder that has been associated with systemic inflammatory response syndrome. Ginsenoside Rg3 is a major active component of Panax ginseng, which has been demonstrated to exert potent protective effects on hyperglycemia and diabetes. However, it remains to be determined whether Rg3 ameliorates AP. Thus, an in vitro AP cell model was established in the present study by exposing AR42J cells to cerulein (Cn). AR42J cell viability was increased in the Rg3‑treated group as compared with the Cn‑exposed group. Simultaneously, the number of dead AR42J cells was decreased in the Rg3‑treated group compared with the group treated with Cn only. Furthermore, following treatment with Rg3, the production of malondialdehyde (MDA) and ferrous ion (Fe2+) in the AR42J cells was reduced, accompanied by increased glutathione (GSH) levels. Western blot analysis revealed that the decrease in glutathione peroxidase 4 (GPX4) and cystine/glutamate transporter (xCT) levels induced by Cn were reversed by Rg3 treatment in the AR42J cells. Mice treated with Cn exhibited increased serum amylase levels, as well as increased levels of TNFα, IL‑6, IL‑1β, pancreatic MDA, reactive oxygen species (ROS) and Fe2+ production. Following Rg3 treatment, ROS accumulation and cell death were decreased in the pancreatic tissues compared with the AP group. Furthermore, in the pancreatic tissues of the AP model, the expression of nuclear factor‑erythroid factor 2‑related factor 2 (NRF2)/heme oxygenase 1 (HO‑1)/xCT/GPX4 was suppressed. In comparison, the NRF2/HO‑1/xCT/GPX4 pathway was activated in pancreatic tissues following Rg3 administration. Taken together, the present study, to the best of our knowledge, is the first to reveal a protective role for Rg3 in mice with AP by suppressing oxidative stress‑related ferroptosis and the activation of the NRF2/HO‑1 pathway.

Blood Purification for Hypertriglyceridemia-Induced Acute Pancreatitis: A Meta-analysis

OBJECTIVES

The purpose of our study is to investigate the efficacy and safety of blood purification (BP) therapy in hypertriglyceridemia-induced acute pancreatitis.

METHODS

We searched PubMed, Embase, Cochrane Library, and Web of Science databases for articles published.

RESULTS

The analysis included 13 studies with 934 patients (263 in BP group, 671 in control group). There was no difference in efficacy and safety between the BP group and the control group (all P > 0.05). Compared with conventional treatment, BP had shorter hospital stay (mean difference, -4.96; 95% confidence interval [CI], -8.81 to -1.11; P = 0.01) in the case of similar mortality and complications. Meanwhile, insulin treatment showed similar mortality to BP, but fewer local complications (odds risk, 2.18; 95% CI, 1.13-4.20; P = 0.02) and shorter hospital stay (mean difference, 5.46; 95% CI, 0.64-10.29; P = 0.03).

CONCLUSIONS

In the treatment of hypertriglyceridemia-induced acute pancreatitis, BP methods are effective in accelerating triglyceride level reduction and shortening hospital stay but do not affect the efficacy or reduce mortality significantly compared with conventional treatment. Insulin therapy has the same effect as BP but decreases incidence of complications and cost.

The role of comorbid hypertriglyceridemia and abdominal obesity in the severity of acute pancreatitis: a retrospective study

Background

The effect of comorbid hypertriglyceridemia (HTG) and abdominal obesity (AO) on acute pancreatitis (AP) remains unclear. The aim of this study was to explore the effect of comorbid HTG and AO and discuss which is the dominant disorder.

Methods

In this study, 1219 AP patients who presented with HTG or AO were stratified into four groups: non-HTG + non-AO, HTG + non-AO, non-HTG + AO, and HTG + AO.

Results

The 328 patients with comorbid HTG + AO were much younger (42.29 ± 11.77), mainly male (79.57%), and had higher TG levels, larger waist circumferences, and more past medical histories than the patients in the other three non-comorbid groups (P < 0.001). The comorbidity group developed more incidences of persistent organ failure and local complications (P < 0.05). Multivariate logistic regression analysis showed that AO (OR = 3.205, 95% CI = 1.570–6.544), mild HTG (OR = 2.746, 95% CI = 1.125–6.701), and moderate to very severe HTG (OR = 3.649, 95% CI = 1.403–9.493) were independent risk factors for persistent respiratory failure (P < 0.05). Age > 60 years (OR = 1.326, 95% CI = 1.047–1.679), AO (OR = 1.701, 95% CI = 1.308–2.212), diabetes mellitus (OR = 1.551, 95% CI = 1.063–2.261), mild HTG (OR = 1.549, 95% CI = 1.137–2.112), and moderate to very severe HTG (OR = 2.810, 95% CI = 1.926–4.100) were independent risk factors associated with local complications (P < 0.05). Moreover, HTG seemed to be more dangerous than AO. The higher the serum TG level was, the greater the likelihood of persistent respiratory failure and local complications.

Conclusions

Comorbid HTG and AO will aggravate the severity and increase the incidence of local complications of AP. HTG may play a dominant role of risk in the condition of comorbidity.

Chinese clinical trial registry

ChiCTR2100049566. Registered on 3^rd August, 2021. Retrospectively registered, https://www.chictr.org.cn/edit.aspx?pid=127374&htm=4.

Circ_UTRN ameliorates caerulein-induced acute pancreatitis in vitro via reducing inflammation and promoting apoptosis through miR-320-3p/PTK2 axis

OBJECTIVES

Circular RNAs (circRNAs) have been demonstrated to play important roles in acute pancreatitis (AP). Herein, this study aimed to investigate the role and mechanism of circRNAs utrophin (circ_UTRN) in AP.

METHODS

In vitro cultured rat pancreatic acinar cell line AR42J was exposed to caerulein (10 nmol/L) to mimic an AP cell model. The levels of circ_UTRN and microRNA (miR)-320-3p and protein tyrosine kinase 2 (PTK2) were examined using quantitative real-time polymerase chain reaction and Western blot assays. Cell apoptosis was analysed by flow cytometry and Western blot assays. ELISA was employed to detect the levels of tumour necrosis factor-α (TNF-α), IL-1β and IL-6. The binding interaction between miR-320-3p and circ_UTRN or PTK2 was verified using dual-luciferase reporter assay.

KEY FINDINGS

The expression of circ_UTRN was decreased by caerulein in pancreatic acinar cells, ectopic overexpression of circ_UTRN reduced inflammation and promoted apoptosis in caerulein-mediated pancreatic acinar cells. In a mechanical study, circ_UTRN served as a sponge of miR-320-3p, and miR-320-3p directly targeted PTK2. Rescue assay suggested that the promotion of apoptosis and inhibition of inflammation induced by circ_UTRN re-expression in caerulein-mediated pancreatic acinar cells were partially abolished by miR-320-3p overexpression or PTK2 knockdown. Besides that, miR-320-3p inhibition impaired caerulein-induced cell apoptosis arrest and inflammation via targeting PTK2.

CONCLUSIONS

Up-regulation of circ_UTRN in pancreatic acinar cells attenuates caerulein-evoked cell apoptosis arrest and inflammation enhancement via miR-320-3p/PTK2, suggesting that circ_UTRN/miR-320-3p/PTK2 axis might be engaged in caerulein-induced AP.

Baicalein alleviates pyroptosis and inflammation in hyperlipidemic pancreatitis by inhibiting NLRP3/Caspase-1 pathway through the miR-192-5p/TXNIP axis

OBJECTIVE

Hyperlipidemia is a main reason of pancreatitis. Baicalein can ameliorate the pathological manifestations of pancreatitis. This study evaluated underlying molecular mechanism of baicalein in hyperlipidemic pancreatitis (HP).

METHODS

HP rat model was successfully established and treated with baicalein. Amylase (AMY) activity and concentrations of triglyceride (TG) and total cholesterol (TC) were detected. Levels of pyroptosis-related proteins (GSDMD, IL-1β, IL-18) were detected by Western blot. Expressions of inflammatory factors (IL-6, TNF-α, IL-4) were detected by ELISA. Toxicity of baicalein on pancreatic acinar cells (PACs) was detected by MTT assay. HP cell model was established by 0.1 mM palmitic acid and CCK-8 stimulation. Target relation of miR-192-5p and TXNIP was predicted and verified by RNA22 v2 database and dual-luciferase reporter assay. Expressions of miR-192-5p and TXNIP were detected by RT-qPCR. Pyroptosis and inflammation in PACs were detected after baicalein treatment combined with silencing miR-192-5p or TXNIP overexpression. Protein levels of NLRP3/Caspase-1 pathway in vivo and vitro were detected.

RESULTS

Baicalein reduced concentrations of TG and TC, AMY activity, and pathological scores in HP rat model, reduced LDH activity, pyroptosis and alleviated inflammation in vivo and in vitro. Mechanically, miR-192-5p targeted TXNIP, and baicalein inhibited pyroptosis and inflammation by up-regulating miR-192-5p and down-regulating TXNIP. Silencing miR-192-5p or TXNIP overexpression partially abolished the anti-pyroptosis and anti-inflammatory effect of baicalein on PACs. Baicalein attenuated HP by inhibiting the NLRP3/Caspase-1 pathway.

CONCLUSION

Baicalein alleviated pyroptosis and inflammation in HP by inhibiting the NLRP3/Caspase-1 pathway through miR-192-5p upregulation and TXNIP inhibition.

Sleeve Gastrectomy Attenuates the Severity of Cerulein-Induced Acute Pancreatitis in Obese Rats

PURPOSE

Obesity is one of the most important risk factors for acute pancreatitis. Based on the effect of sleeve gastrectomy (SG) on improving body weight and blood lipids, we investigated whether SG is beneficial in improving pancreatitis in obese rats.

MATERIALS AND METHODS

Two studies were used to evaluate the effect of SG on the first onset of pancreatitis and acute episodes of recurrent pancreatitis in obese rats. A high-fat diet (HFD) for 8 weeks resulted in obesity in rats. Study 1: Obese rats were treated with SG and sham surgery. Pancreatitis was induced by intraperitoneal injection of cerulein at 6 weeks after surgery. The severity of pancreatitis was assessed by histological examination, cytokines, and infiltration of inflammatory cells. Study 2 performed the same procedure as in study 1, except that rats were intraperitoneally injected with a small dose of cerulein three times a week for 6 weeks before surgery to induce recurrent pancreatitis.

RESULTS

The body weight, food intake, and blood lipids of SG rats in study 1 and study 2 were significantly lower than those of sham rats during the 6 weeks after surgery. Compared with sham rats, SG rats in both studies had fewer inflammatory cytokines, inflammatory cell infiltration, and pathological injury in the pancreas after cerulein-induced acute pancreatitis.

CONCLUSION

SG reduces the severity of the first onset of pancreatitis and the seriousness of acute episodes of recurrent pancreatitis. The improvement of lipid metabolism and body weight by SG may play an important role in this effect.

miR-9 alleviated the inflammatory response and apoptosis in caerulein-induced acute pancreatitis by regulating FGF10 and the NF-κB signaling pathway

MicroRNAs (miRs) have been implicated in the development of acute pancreatitis (AP). However, the role and potential mechanism of miR-9 in AP progression remains unclear. Caerulein-treated AR42J cells were used as a cellular model of AP. Results revealed caerulein triggered an inflammatory response by promoting the secretion of inflammatory cytokines [tumor necrosis factor-α, interleukin (IL) 1β and IL-6], as evidenced by ELISA. Furthermore, caerulein-induced apoptosis was reported by flow cytometry and western blot assays. Additionally, miR-9 expression was downregulated by caerulein treatment, as demonstrated by reverse transcription quantitative PCR. However, miR-9 overexpression reduced the inflammatory response and apoptosis in caerulein-treated AR42J cells. miR-9 knockdown resulted in opposite effects. Furthermore, fibroblast growth factor (FGF) 10 was validated to be targeted via miR-9 by luciferase, RNA immunoprecipitation and RNA pull-down assays. Results demonstrated increased FGF10 expression in caerulein-treated AR42J cells and that FGF10 overexpression exacerbated the caerulein-induced inflammatory response and apoptosis, while its knockdown had the opposite effect. Additionally, FGF10 reversed the effect of miR-9 on caerulein-induced injury in AR42J cells. Results demonstrated that miR-9 inhibited the expression of the nuclear factor κB (NF-κB) pathway-related proteins by downregulating FGF10. As a result, miR-9 decreased inflammatory response and apoptosis in caerulein-treated AR42J cells by targeting FGF10 and blocking NF-κB signaling, suggesting that miR-9 may serve as a novel target for AP treatment.

Docosahexaenoic acid modulates oxidative stress and monoamines levels in brain of streptozotocin-induced diabetic rats

The prevalence of diabetes mellitus (DM) is increasing in many countries. A lower prevalence of DM type 2 and other glucose metabolism disorders was observed in populations consuming larger amounts of n-3 polyunsaturated fatty acids, existing mainly in fish. Docosahexaenoic acid (DHA) is an important signaling molecule required for the central nervous system continuous maintenance of brain functioning. The aim of this research is to highlight the role of DHA in controlling glycemic measures and modulating the oxidant/antioxidant status and levels of neurotransmitters in brains of diabetic rats. Diabetes was induced with a single s.c. injection of streptozotocin (STZ) (6.0 mg/0.5 ml/100 g body weight). Experimental male Wister rats (n=40) were randomly divided into four groups: control group, DHA, STZ-diabetic, and STZ + DHA. All rats were decapitated after 30 days to evaluate glucose and insulin levels, brain oxidative stress and also to estimate monoamines levels. DHA administration significantly improved fasting blood glucose and insulin levels compared to the DHA+STZ group and decreased 8-hydroxy-2'-deoxyguanosine level in their urine. In addition, DHA treatment to STZ-treated rats showed a decrease in malondialdehyde content and advanced oxidation protein product and significantly increased glutathione content in brains of DHA + STZ-treated rats, and decreased the level of monoamines in rat's brain. To conclude: DHA modulated the elevated oxidative stress and neurotransmitters levels, and also acetylcholinesterase activity in diabetic rat brain via enhancing insulin level in serum

Docosahexaenoic Acid Induces Expression of NAD(P)H: Quinone Oxidoreductase and Heme Oxygenase-1 through Activation of Nrf2 in Cerulein-Stimulated Pancreatic Acinar Cells

Oxidative stress is a major risk factor for acute pancreatitis. Reactive oxygen species (ROS) mediate expression of inflammatory cytokines such as interleukin-6 (IL-6) which reflects the severity of acute pancreatitis. The nuclear factor erythroid-2-related factor 2 (Nrf2) pathway is activated to induce the expression of antioxidant enzymes such as NAD(P)H: quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1) as a cytoprotective response to oxidative stress. In addition, binding of Kelch-like ECH-associated protein 1 (Keap1) to Nrf2 promotes degradation of Nrf2. Docosahexaenoic acid (DHA)—an omega-3 fatty acid—exerts anti-inflammatory and antioxidant effects. Oxidized omega-3 fatty acids react with Keap1 to induce Nrf2-regulated gene expression. In this study, we investigated whether DHA reduces ROS levels and inhibits IL-6 expression via Nrf2 signaling in pancreatic acinar (AR42J) cells stimulated with cerulein, as an in vitro model of acute pancreatitis. The cells were pretreated with or without DHA for 1 h and treated with cerulein (10⁻⁸ M) for 1 (ROS levels, protein levels of NQO1, HO-1, pNrf2, Nrf2, and Keap1), 6 (IL-6 mRNA expression), and 24 h (IL-6 protein level in the medium). Our results showed that DHA upregulates the expression of NQO1 and HO-1 in cerulein-stimulated AR42J cells by promoting phosphorylation and nuclear translocation of Nrf2. DHA increased interaction between Keap1 and Nrf2 in AR42J cells, which may increase Nrf2 activity by inhibiting Keap1-mediated sequestration of Nrf2. In addition, DHA-induced expression of NQO1 and HO-1 is related to reduction of ROS and IL-6 levels in cerulein-stimulated AR42J cells. In conclusion, DHA inhibits ROS-mediated IL-6 expression by upregulating Nrf2-mediated expression of NQO1 and HO-1 in cerulein-stimulated pancreatic acinar cells. DHA may exert positive modulatory effects on acute pancreatitis by inhibiting oxidative stress and inflammatory cytokine production by activating Nrf2 signaling in pancreatic acinar cells.

Synthesis of DHA/EPA Ethyl Esters via Lipase-Catalyzed Acidolysis Using Novozym® 435: A Kinetic Study

DHA/EPA ethyl ester is mainly used in the treatment of arteriosclerosis and hyperlipidemia. In this study, DHA+EPA ethyl ester was synthesized via lipase-catalyzed acidolysis of ethyl acetate (EA) with DHA+EPA concentrate in n-hexane using Novozym® 435. The DHA+EPA concentrate (in free fatty acid form), contained 54.4% DHA and 16.8% EPA, was used as raw material. A central composite design combined with response surface methodology (RSM) was used to evaluate the relationship between substrate concentrations and initial rate of DHA+EPA ethyl ester production. The results indicated that the reaction followed the ordered mechanism and as such, the ordered mechanism model was used to estimate the maximum reaction rate (Vmax) and kinetic constants. The ordered mechanism model was also combined with the batch reaction equation to simulate and predict the conversion of DHA+EPA ethyl ester in lipase-catalyzed acidolysis. The integral equation showed a good predictive relationship between the simulated and experimental results. 88–94% conversion yields were obtained from 100–400 mM DHA+EPA concentrate at a constant enzyme activity of 200 U, substrate ratio of 1:1 (DHA+EPA: EA), and reaction time of 300 min.

Comparison of Omega-3 Eicosapentaenoic Acid Versus Docosahexaenoic Acid-Rich Fish Oil Supplementation on Plasma Lipids and Lipoproteins in Normolipidemic Adults

Background: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have both shared and different cardiovascular effects, and commonly used fish oil supplements have considerably varied EPA/DHA ratios. Aims: We compared the effects of fish oil supplements with different EPA/DHA ratios on lipoprotein metabolism. Methods: In a double-blind, randomized cross-over study, normolipidemic adults (n = 30) consumed 12 g/day of EPA-rich (EPA/DHA: 2.3) or DHA-rich (EPA/DHA: 0.3) fish oil for 8-weeks, separated by an 8-week washout period. Results: Both fish oil supplements similarly lowered plasma TG levels and TG-related NMR parameters versus baseline (p < 0.05). There were no changes in plasma cholesterol-related parameters due to either fish oil, although on-treatment levels for LDL particle number were slightly higher for DHA-rich oil compared with EPA-rich oil (p < 0.05). Both fish oil supplements similarly altered HDL subclass profile and proteome, and down regulated HDL proteins related to inflammation, with EPA-rich oil to a greater extent. Furthermore, EPA-rich oil increased apoM abundance versus DHA-rich oil (p < 0.05). Conclusions: Overall, fish oil supplements with varied EPA/DHA ratios had similar effects on total lipids/lipoproteins, but differences were observed in lipoprotein subfraction composition and distribution, which could impact on the use of EPA versus DHA for improving cardiovascular health.

Docosahexaenoic Acid Inhibits Expression of Fibrotic Mediators in Mice With Chronic Pancreatitis

Background

Chronic pancreatitis (CP) is an irreversible progressive disease that destroys exocrine parenchyma, which are replaced by fibrous tissue. As pancreatic fibrosis is a key feature of CP, reducing fibrotic protein content in the pancreas is crucial for preventing CP. Studies suggest that NF-κB facilitates the expression of fibrotic mediators in pancreas and protein kinase C-δ (PKC-δ) regulates NF-κB activation in stimulated pancreatic acinar cells. Docosahexaenoic acid (DHA) is an omega-3 fatty acid having anti-inflammatory and anti-fibrotic effects. It has been shown to inhibit NF-κB activity in cerulein-stimulated pancreatic acinar cells which is a cellular model of CP. In the present study, we investigated if DHA inhibits expression of fibrotic mediators by reducing PKC-δ and NF-κB expression in mouse pancreatic tissues with CP.

Methods

For six weeks, mice were weekly induced for acute pancreatitis to develop CP. Furthermore, acute pancreatitis was induced by hourly intraperitoneal injections of cerulein (50 μg/kg × 7). Mice were administered DHA (10 μM) via drinking water before and after CP induction.

Results

Cerulein-induced pancreatic damages like decreased pancreatic weight/total body weight, leukocyte infiltration, necrosis of acinar cells, and vacuolization were found to be inhibited by DHA. Additionally, DHA inhibited cerulein-induced fibrotic mediators like alpha-smooth muscle actin and fibronectin in pancreas. DHA reduced expression of PKC-δ and NF-κB p65 in pancreatic tissues of cerulein-treated mice.

Conclusions

DHA may be beneficial in preventing CP by suppressing pancreatic expression of fibrotic mediators.

17-Oxo-docosahexaenoic acid induces Nrf2-mediated expression of heme oxygenase-1 in mouse skin in vivo and in cultured murine epidermal cells

Recently, growing attention has been given to new classes of bioactive lipid mediators derived from ω-3 polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), especially in the context of their role as endogenous signal modulators. One such molecule is 17-oxo-DHA, generated from DHA by the action of COX2 and a dehydrogenase. The redox-sensitive transcription factor, Nrf2 plays a key role in cellular stress responses. In the present study, the effects of 17-oxo-DHA on Nrf2-mediated expression of cytoprotective enzymes were examined in mouse skin in vivo and cultured murine epidermal JB6 cells. Topical application of 17-oxo-DHA markedly elevated the nuclear localization of Nrf2 and expression of heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase-1 in hairless mouse skin. In contrast to 17-oxo-DHA, the non-electrophilic metabolic precursor 17-hydroxy-DHA was a much weaker inducer of Nrf2 activation and its target protein expression. Likewise, 17-oxo-DHA significantly enhanced nuclear translocation and transcriptional activity of Nrf2 with concomitant upregulation of HO-1 expression in cultured JB6 cells. 17-Oxo-DHA was a much stronger inducer of Nrf2-mediated antioxidant response than its parent molecule, DHA. HO-1 expression was abolished in Nrf2 knockdown JB6 cells or embryo fibroblasts from Nrf2 knock out mice. 17-Oxo-DHA also markedly reduced the level of Keap1 protein by inducing ubiquitination. Mutation of Cys151 and Cys273 in Keap1 abrogated 17-oxo-DHA-induced ubiquitination and proteasome-mediated degradation of Keap1 as well as HO-1 expression, suggesting that these cysteine residues are putative sites for 17-oxo-DHA binding. Further, Keap1 degradation stimulated by 17-oxo-DHA coincided with accumulation of the autophagy substrate, p62/SQSTM1.