miRNA transcriptomics analysis shows miR-483-5p and miR-503-5p targeted miRNA in extracellular vesicles from severe acute pancreatitis-associated lung injury patients.

AIM: This study sought to identify potential biomarkers and miRNA-mRNA networks within extracellular vesicles (EVs) for detecting severe acute pancreatitis-associated lung injury (SAPALI). METHODS: Blood-derived EVs were isolated, and their miRNA transcriptomic profiles were comprehensively analyzed using miRBase v.21 database along with miRDeep2 tool to predict novel miRNAs. DEGseq R package was deployed for the identification of differentially expressed miRNAs (DEMs). Protein-protein interaction (PPI) networks were assembled using STRING and Cytoscape. A lung injury model was established using Lipopolysaccharide (LPS)-induced BEAS-2B cells, chosen for their respiratory epithelial origin and pertinent association with lung injury. The expression levels of targeted miRNA and associated proteins, TLR4, NF-κB mRNA were quantified via RT-PCR and Western Blot. Levels of IL-6, IL-1ß, TNF-α, and ROS were measured using designated kits. Dual-luciferase reporter assay was conducted to examine the interaction between miRNA and proteins. RESULTS: The comparisons between the SAPALI and the control group revealed 10 DEM, including miR-503-5p and miR-483-5p. The cytoHubba plugin in Cytoscape identified three principal miRNA-mRNA interactions: miR-483-5p with PTK2 and HDAC2; miR-28-5p with MAPK1, TP53BP1, SEMA3A; and miR-503-5p with PPP1CB, SEMA6D, EPHB2, UNC5B. The SAPALI model exhibited elevated miR-503-5p, HDAC2 and inflammatory markers, with a decline UNC5B, miR-483-5p and miR-28-5p. Transfection with miR-503-5p and miR-483-5p inhibitors increased the levels of their supposed binding proteins but not miR-28-5p inhibitor. The Dual-luciferase reporter gene assay identified the interaction of miR-503-5p with UNC5B, and miR-483-5p with HDAC2, but not miR-28-5p with TP53BP1. CONCLUSIONS: Our study maps miRNA-mRNA interactions in SAPALI, identifying miR-503-5p and miR-483-5p as critical regulatory miRNAs.

Adropin attenuates pancreatitis­associated lung injury through PPARγ phosphorylation­related macrophage polarization.

Acute pancreatitis (AP)­associated lung injury (ALI) is a critical complication of AP. Adropin is a regulatory protein of immune metabolism. The present study aimed to explore the immunomodulatory effects of adropin on AP­ALI. For this purpose, serum samples of patients with AP were collected and the expression levels of serum adropin were detected using ELISA. Animal models of AP and adropin knockout (Adro­KO) were constructed, and adropin expression in serum and lung tissues was investigated. The levels of fibrosis and apoptosis were evaluated using hematoxylin and eosin staining, Masson's staining and immunohistochemistry of in lung tissue. M1/M2 type macrophages in the lungs were detected using immunofluorescence staining, western blot analysis and reverse transcription­quantitative PCR. As shown by the results, adropin expression was decreased in AP. In the Adro­KO + L­arginine (L­Arg) group, macrophage infiltration, fibrosis and apoptosis were increased. The expression of peroxisome proliferator­ activated receptor γ (PPARγ) was downregulated, and the macrophages exhibited a trend towards M1 polarization in the Adro­KO + L­Arg group. Adropin exogenous supplement attenuated the levels of fibrosis and apoptosis in the model of AP. Adropin exogenous supplement also increased PPARγ expression by the regulation of the phosphorylation levels, which was associated with M2 macrophage polarization. On the whole, the findings of the present study suggest that adropin promotes the M2 polarization of lung macrophages and reduces the severity of AP­ALI by regulating the function of PPARγ through the regulation of its phosphorylation level.

Intestinal Microbiota - An Unmissable Bridge to Severe Acute Pancreatitis-Associated Acute Lung Injury.

Severe acute pancreatitis (SAP), one of the most serious abdominal emergencies in general surgery, is characterized by acute and rapid onset as well as high mortality, which often leads to multiple organ failure (MOF). Acute lung injury (ALI), the earliest accompanied organ dysfunction, is the most common cause of death in patients following the SAP onset. The exact pathogenesis of ALI during SAP, however, remains unclear. In recent years, advances in the microbiota-gut-lung axis have led to a better understanding of SAP-associated lung injury (PALI). In addition, the bidirectional communications between intestinal microbes and the lung are becoming more apparent. This paper aims to review the mechanisms of an imbalanced intestinal microbiota contributing to the development of PALI, which is mediated by the disruption of physical, chemical, and immune barriers in the intestine, promotes bacterial translocation, and results in the activation of abnormal immune responses in severe pancreatitis. The pathogen-associated molecular patterns (PAMPs) mediated immunol mechanisms in the occurrence of PALI via binding with pattern recognition receptors (PRRs) through the microbiota-gut-lung axis are focused in this study. Moreover, the potential therapeutic strategies for alleviating PALI by regulating the composition or the function of the intestinal microbiota are discussed in this review. The aim of this study is to provide new ideas and therapeutic tools for PALI patients.

The gut-lung axis in severe acute Pancreatitis-associated lung injury: The protection by the gut microbiota through short-chain fatty acids.

The role of gut microbiota in regulating the intestinal homeostasis, as well as the pathogenesis of severe acute pancreatitis-associated lung injury (PALI) is widely recognized. The bioactive functions of metabolites with small molecule weight and the detail molecular mechanisms of PALI mediated by "gut-lung axis" have gradually raised the attentions of researchers. Several studies have proved that short-chain fatty acids (SCFAs) produced by gut microbiome play crucial roles and varied activities in the process of PALI. However, relevant reviews reporting SCFAs in the involvement of PALI is lacking. In this review, we firstly introduced the synthetic and metabolic pathways of SCFAs, as well as the transport and signal transduction routes in brief. Afterwards, we focused on the possible mechanisms and clues of SCFAs to participate in the fight against PALI which referred to the inhibition of pathogen proliferation, anti-inflammatory effects, enhancement of intestinal barrier functions, and the maintenance and regulation of immune homeostasis via pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In addition, the latest reported pathological and physiological mechanisms of the gut-lung axis involved in PALI were reviewed. Finally, we summarized the potential therapeutic interventions of PALI by targeting SCFAs, including dietary fiber supplementation, direct supplementation of SCFAs/prebiotics/probiotics, and drugs administration, which is expected to provide new sights for clinical use in the future.

Captopril pretreatment protects the lung against severe acute pancreatitis induced injury via inhibiting angiotensin II production and suppressing Rho/ROCK pathway.

Acute pancreatitis (AP) usually causes acute lung injury, which is also known as acute pancreatitis associated lung injury (APALI). This study aimed to investigate whether captopril pretreatment was able to protect lung against APALI via inhibiting angiotensin II (Ang II) production and suppressing Rho/ROCK (Rho kinase) pathway in rats. Severe AP (SAP) was introduced to rats by bile-pancreatic duct retrograde injection of 5% sodium taurocholate. Rats were randomly divided into three groups. In the sham group, sham operation was performed; in the SAP group, SAP was introduced; in the pre-cpl + SAP group, rats were intragastrically injected with 5 mg/kg captopril 1 hour prior to SAP induction. Pathological examination of the lung and pancreas, evaluation of pulmonary vascular permeability by wet/dry ratio and Evans Blue staining, detection of serum amylase, Western blot assay for Ang II receptor type 1 (AT1), RhoA, ROCK (Rho kinase), and MLCK (myosin light chain kinase) were performed after the animals were sacrificed at 24 hours. After the surgery, characteristic findings of pancreatitis were observed, accompanied by lung injury. The serum amylase, Ang II, and lung expression of AT1, RhoA, ROCK, and MLCK increased dramatically in SAP rats. However, captopril pretreatment improved the histological changes, reduced the pathological score of the pancreas and lung, inhibited serum amylase and Ang II production, and decreased expression of AT1, RhoA, ROCK, and MLCK in the lung. These findings suggest that captopril pretreatment is able to protect the lung against APALI, which is, at least partially, related to the inhibition of Ang II production and the suppression of the Rho/ROCK pathway.

Hyperbaric oxygen preconditioning protects the lung against acute pancreatitis induced injury via attenuating inflammation and oxidative stress in a nitric oxide dependent manner.

This study aimed to investigate the protective effects of hyperbaric oxygen preconditioning (HBO-PC) on acute pancreatitis AP associated acute lung injury (ALI) and the potential mechanisms. Rats were randomly divided into sham group, AP group, HBO-PC + AP group and HBO-PC + L-NAME group. Rats in HBO-PC + AP group received HBO-PC once daily for 3 days, and AP was introduced 24 h after last HBO-PC. In HBO-PC + L-NAME group, L-NAME (40 mg/kg) was intraperitoneally injected before each HBO-PC. At 24 h after AP, the blood lipase and amylase activities were measured; the lung and pancreas were harvested for pathological examination; the bronchoalveolar lavage fluid was collected for the detection of lactate dehydrogenase (LDH) and proteins; inflammatory factors, superoxide dismutase (SOD) activity and malonaldehyde content were measured in the lung and blood; the Nrf2, SOD-1 and haem oxygenase-1 (HO-1) protein expression was measured in the lung. The lung nitric oxide (NO) and NO synthase activity increased significantly after HBO-PC. HBO-PC was able to reduce blood lipase and amylase activities, improve lung and pancreatic pathology, decrease LDH and proteins in BALF, inhibit the production of inflammatory factors, reduce malonaldehyde content and increase SOD activity in the lung and blood as well as increase protein expression of Nrf2, SOD-1 and HO-1 in the lung. However, L-NAME before HBO-PC significantly attenuated protective effects of HBO-PC. HBO-PC is able to protect the lung against AP induced injury by attenuating inflammation and oxidative stress in the lung via a NO dependent manner.

Caspase inhibitor zVAD-fmk protects against acute pancreatitis-associated lung injury via inhibiting inflammation and apoptosis.

BACKGROUND/OBJECTIVES: Pulmonary apoptosis is an important pathogenic mechanism of acute lung injury induced by many factors. This study aims to investigate whether the caspase inhibitor zVAD-fmk has a protective effect against lung injury in the severe acute pancreatitis model (SAP) in rats. METHODS: Seventy-two Sprague-Dawley rats were randomly divided into Sham, SAP, and SAP + zVAD-fmk groups. The SAP model was established by injection of 5% sodium taurocholate into the pancreatic duct. Animals were sacrificed at 3 h, 6 h, 12 h, and 24 h after operation and then HE staining analysis was performed to assess the lung injury. ELISA was used to detect the activity of myeloperoxidase (MPO) and the concentrations of tumor necrosis factor α (TNF-α) and interleukin 1ß (IL-1ß). Western blotting was used to detect the expression of cleaved caspase-3 in the lung tissues. RESULTS: Rats in SAP group showed obvious lung injury through pathologic examination. Pretreatment with zVAD-fmk significantly inhibited a post-SAP increase in the activation of MPO, TNF-α, IL-1ß, and caspase-3, and decreased lung injury induced by SAP as determined by the pathologic score. CONCLUSION: Our results suggest that apoptosis plays an important role in acute pancreatitis-associated lung injury (APALI), and inhibition of caspase activity may represent a new therapeutic approach for the treatment of APALI.

Dihydro-Resveratrol Ameliorates Lung Injury in Rats with Cerulein-Induced Acute Pancreatitis.

Acute pancreatitis is an inflammatory process originated in the pancreas; however, it often leads to systemic complications that affect distant organs. Acute respiratory distress syndrome is indeed the predominant cause of death in patients with severe acute pancreatitis. In this study, we aimed to delineate the ameliorative effect of dihydro-resveratrol, a prominent analog of trans-resveratrol, against acute pancreatitis-associated lung injury and the underlying molecular actions. Acute pancreatitis was induced in rats with repetitive injections of cerulein (50 µg/kg/h) and a shot of lipopolysaccharide (7.5 mg/kg). By means of histological examination and biochemical assays, the severity of lung injury was assessed in the aspects of tissue damages, myeloperoxidase activity, and levels of pro-inflammatory cytokines. When treated with dihydro-resveratrol, pulmonary architectural distortion, hemorrhage, interstitial edema, and alveolar thickening were significantly reduced in rats with acute pancreatitis. In addition, the production of pro-inflammatory cytokines and the activity of myeloperoxidase in pulmonary tissues were notably repressed. Importantly, nuclear factor-kappaB (NF-κB) activation was attenuated. This study is the first to report the oral administration of dihydro-resveratrol ameliorated acute pancreatitis-associated lung injury via an inhibitory modulation of pro-inflammatory response, which was associated with a suppression of the NF-κB signaling pathway.

The association between red blood cell distribution width and acute pancreatitis associated lung injury in patients with acute pancreatitis.

BACKGROUND: Red blood cell distribution width (RDW) that describes red blood cell volume heterogeneity is a common laboratory test. Our aim was to focus on the association between RDW and acute pancreatitis associated lung injury (APALI). METHODOLOGY: A total of 152 acute pancreatitis (AP) patients who conformed to the criteria were included in this study. The demographic data, medical histories and laboratory measures was obtained from each patient on admission, further, the medical histories and biological data were analyzed, retrospectively. RESULTS: Increased RDW at admission was observed in patients with APALI compared with the non-APALI groups. Our results exhibited that RDW was an independent risk factor for APALI after adjusting leukocyte, neutrophil percentage, random blood glucose (RBG), total bilirubin (TB) and total bile acid (TBA) (Crude model) (OR=2.671;CI 95% 1.145-6.230; P=0.023), further adjustment based on Crude model for sex and age did not attenuate the significantly high risk of APALI in patients with AP, RWD still remained a roles as an independent risk factor for APALI (OR=2.653;CI95 % 1.123-6.138; P=0.026). CONCLUSIONS: Our study demonstrate that RDW at admission is associated with APALI and should be considered as an underlying risk factor of APALI.

Cystathionine-gamma-lyase inhibitor attenuates acute lung injury induced by acute pancreatitis in rats.

INTRODUCTION: Acute pancreatitis (AP) is known to induce injuries to extrapancreatic organs. Because respiratory dysfunction is the main cause of death in patients with severe AP, acute pancreatitis-associated lung injury (APALI) is a great challenge for clinicians. This study aimed to investigate the potential role of hydrogen sulfide (H2S) in the pathogenesis of APALI. MATERIAL AND METHODS: Fifty-four SD rats were randomly divided into three groups: the AP group of rats that received injection of sodium deoxycholate into the common bile duct, the control group that underwent a sham operation, and the treatment group made by intraperitoneal injection of propargylglycine (PAG), an inhibitor of cystathionine-γ-lyase (CSE), into rats with AP. Histopathology of the lung was examined and the expression of CSE and TNF-α mRNA in lung tissue was detected by real-time polymerase chain reaction. The H2S level in the serum was detected spectrophotometrically. RESULTS: The serum concentration of H2S and CSE and TNF-α expression in the lung were increased in AP rats modeled after 3 h and 6 h than in control rats (p < 0.05). Intraperitoneal injection of PAG could reduce the serum concentration of H2S, reduce CSE and TNF-α expression, and alleviate the lung pathology (p < 0.05). CONCLUSIONS: Taken together, our findings suggest that the H2S/CSE system is crucially involved in the pathological process of APALI and represents a novel target for the therapy of APALI.

Melatonin attenuates acute pancreatitis-associated lung injury in rats by modulating interleukin 22.

AIM: To investigate whether therapeutic treatment with melatonin could protect rats against acute pancreatitis and its associated lung injury. METHODS: Seventy-two male Sprague-Dawley rats were randomly divided into three groups: the sham operation (SO), severe acute pancreatitis (SAP), and melatonin treatment (MT) groups. Acute pancreatitis was induced by infusion of 1 mL/kg of sodium taurocholate (4% solution) into the biliopancreatic duct. Melatonin (50 mg/kg) was administered 30 min before pancreatitis was induced, and the severity of pancreatic and pulmonary injuries was evaluated 1, 4 and 8 h after induction. Serum samples were collected to measure amylase activities, and lung tissues were removed to measure levels of mRNAs encoding interleukin 22 (IL-22) and T helper cell 22 (Th22), as well as levels of IL-22. RESULTS: At each time point, levels of mRNAs encoding IL-22 and Th22 were significantly higher (P < 0.001) in the MT group than in the SAP group (0.526 ± 0.143 vs 0.156 ± 0.027, respectively, here and throughout, after 1 h; 0.489 ± 0.150 vs 0.113 ± 0.014 after 4 h; 0.524 ± 0.168 vs 0.069 ± 0.013 after 8 h, 0.378 ± 0.134 vs 0.122 ± 0.015 after 1 h; 0.205 ± 0.041 vs 0.076 ± 0.019 after 4 h; 0.302 ± 0.108 vs 0.045 ± 0.013 after 8 h, respectively) and significantly lower (P < 0.001) in the SAP group than in the SO group (0.156 ± 0.027 vs 1.000 ± 0.010 after 1 h; 0.113 ± 0.014 vs 1.041 ± 0.235 after 4 h; 0.069 ± 0.013 vs 1.110 ± 0.213 after 8 h, 0.122 ± 0.015 vs 1.000 ± 0.188 after 1 h; 0.076 ± 0.019 vs 0.899 ± 0.125 after 4 h; 0.045 ± 0.013 vs 0.991 ± 0.222 after 8 h, respectively). The mean pathological scores for pancreatic tissues in the MT group were significantly higher (P < 0.01) than those for samples in the SO group (1.088 ± 0.187 vs 0.488 ± 0.183 after 1 h; 2.450 ± 0.212 vs 0.469 ± 0.242 after 4 h; 4.994 ± 0.184 vs 0.513 ± 0.210 after 8 h), but were significantly lower (P < 0.01) than those for samples in the SAP group at each time point (1.088 ± 0.187 vs 1.969 ± 0.290 after 1 h; 2.450 ± 0.212 vs 3.344 ± 0.386 after 4 h; 4.994 ± 0.184 vs 6.981 ± 0.301 after 8 h). The severity of SAP increased significantly (P < 0.01) over time in the SAP group (1.088 ± 0.187 vs 2.450 ± 0.212 between 1 h and 4 h after inducing pancreatitis; and 2.450 ± 0.212 vs 4.994 ± 0.184 between 4 and 8 h after inducing pancreatitis). CONCLUSION: Melatonin protects rats against acute pancreatitis-associated lung injury, probably through the upregulation of IL-22 and Th22, which increases the innate immunity of tissue cells and enhances their regeneration.

Protective effect of transplanted bone marrow-derived mesenchymal stem cells on pancreatitis-associated lung injury in rats.

Severe acute pancreatitis (SAP) is initiated by the premature activation of digestive enzymes within the pancreatic acinar cells, leading to self-digestion and inflammatory responses in pancreatic ductal cells, thus giving rise to systemic inflammatory response syndrome (SIRS). The most common and serious SIRS is pancreatitis-associated lung injury, and inflammatory mediators play an important role in its pathogenesis. Bone marrow-derived mesenchymal stem cells (MSCs) are differentiated into alveolar endothelial cells to replace the damaged alveolar endothelial cells and inhibit inflammatory response in the injured lung tissues. In this study, we aimed to investigate the therapeutic effect of bone marrow-derived MSCs in rats with pancreatitis-associated lung injury. Experimental SAP was induced by a retrograde injection of 5% sodium taurocholate into the biliopancreatic duct of 75 male Sprague-Dawley rats, which were divided into the SAP group (n=25), the MSC group (n=25) and the sham-operated group (n=25) to explore the pathology and function of lung tissues and the regulation of inflammatory mediators. Pulmonary edema was estimated by measuring water content in the lung tissues. Pulmonary myeloperoxidase (MPO) activity was detected using spectrophotometry. Serum amylase was detected using the Automatic Biochemistry Analyzer. Tumor necrosis factor-α (TNF-α) and substance P (SP) mRNA levels were determined by quantitative reverse transcriptase-polymerase chain reaction. Our results showed that serum amylase activity was significantly decreased in the MSC group compared to the SAP group. Pulmonary edema was significantly diminished (p<0.05) in the MSC group compared to the SAP group. Typical acute lung injury was observed in the SAP group, and the pathological changes were mild in the MSC group. The expression of TNF-α and SP mRNA in lung tissue was diminished in the MSC group compared to the SAP group. In conclusion, MSC transplantation attenuates pulmonary edema and inflammation, and reduces the mRNA expression of TNF-α and SP in pancreatitis-associated lung injury.