microRNA-542-5p protects against acute lung injury in mice with severe acute pancreatitis by suppressing the mitogen-activated protein kinase signaling pathway through the negative regulation of P21-activated kinase 1.

Severe acute pancreatitis (SAP) is a condition associated with high rates of mortality and lengthy hospital stays. In the current study, SAP mouse models were established in BALB/c wild-type and P21-activated kinase 1 (PAK1) knockdown mice with the objective of determining the expression of microRNA-542-5p (miR-542-5p) and the subsequent elucidation of the mechanism by which it influences acute lung injury (ALI) by mediating mitogen-activated protein kinase (MAPK) signaling and binding to PAK1. The targeting relationship between miR-542-5p and PAK1 was verified using the bioinformatics prediction website and by the means of a dual-luciferase reporter assay. Following the SAP model establishment, the mice were assigned into various groups with the introduction of different mimic and inhibitors in an attempt to investigate the effects involved with miR-542-5p on inflammatory reactions among mice with SAP-associated ALI. Our results indicated that PAK1 was targeted and negatively mediated by miR-542-5p. Mice with SAP-associated ALI exhibited an increased wet-to-dry weight ratio, myeloperoxidase activity, serum amylase activity, TNF-α, interleukin-1 beta (IL-1ß), and intercellular adhesion molecule-1 (ICAM-1) contents, p-p38MAPK, p-ERK1/2, and p-JNK protein levels as well as PAK1 positive expression, while decreased miR-542-5p levels were observed. Functionally, overexpression of miR-542-5p improves ALI in mice with SAP via inhibition of the MAPK signaling pathway by binding to PAK1.Based on the evidence from experimental models, miR-542-5p was shown to improve ALI among mice with SAP, while suggesting that the effect may be related to the inactivation of the MAPK signaling pathway and downregulation of PAK1 gene. Thus, miR-542-5p could serve as a promising target for ALI treatment.

MicroRNA-339-3p alleviates inflammation and edema and suppresses pulmonary microvascular endothelial cell apoptosis in mice with severe acute pancreatitis-associated acute lung injury by regulating Anxa3 via the Akt/mTOR signaling pathway.

Severe acute pancreatitis (SAP) is a disease with a high mortality. Patients with SAP may also be complicated with acute lung injury (ALI). So far the therapy for SAP-ALI is still limited. Emerging evidences demonstrate that microRNAs (miRs) could play a role in SAP-ALI. This study aims to define the role of miR-339-3p in SAP-ALI via Anxa3 through the Akt/mTOR signaling pathway. Ten mice were selected as sham group and 36 mice as model group which further assigned into different groups. Relationship between miR-339-3p and Anxa3 was detected by dual luciferase reporter gene assay. Levels of TNF-α, IL-6, and serum amylase (AMS) and myeloperoxidase (MPO) in lung tissues were determined by ELISA. Expression of related genes in pulmonary vascular endothelial cells (PMVECs) and lungs tissues was determined by Western blot analysis and RT-qPCR. Cell apoptosis was detected by flow cytometry and TUNEL. SAP-ALI mice had decreased survival rate, increased levels of TNF-α, IL-6, AMS, MPO, and Schmidt scores. miR-339-3p was poorly expressed in lung tissue of SAP-ALI mice while Anxa3 was reciprocal. Anxa3 was targeted by miR-339-3p. miR-339-3p inhibited the relative expression of the Akt/mTOR signaling pathway-related proteins, alleviated inflammation and edema of SAP-ALI mice, and suppressed apoptosis of PMVECs; Anxa3 exhibited opposite trends. In conclusion, overexpressed miR-339-3p could suppress Anxa3 to inhibit the Akt/mTOR signaling pathway, so as to decrease tissue edema, inflammation, and PMVEC apoptosis in SAP-ALI mice.

Proteolytic antigens interfere with endosome/lysosome fusion in epithelial cells.

The airway epithelial barrier function is important in maintaining the homeostasis in the body. A number of airway disorders are associated with the epithelial barrier dysfunction. The present study aims to elucidate a possible mechanism by which the proteolytic allergens compromise the epithelial barrier function. The airway epithelial cell line, RPMI 2650 cells (Rp cells) and kidney epithelial cell line, MDCK cells, were cultured to be monolayers and used as an in vitro epithelial barrier model. House dust mite antigen, Der P1 (Der) was used as an antigen that has the proteolytic property. The epithelial barrier permeability and transepithelial resistance (TER) were used as the indicators of epithelial barrier function. Both epithelial cell lines could endocytose Der in the culture. Some of the Der was transported across the epithelial barrier to the basal chambers of the Transwells without affecting the TER. The endocytic Der could suppress the expression of ubiquitin E3 lases A20 and further interfered with the fusion of endosome/lysosome in the epithelial cells. Mite antigen, Der, can interfere with the fusion of endosome/lysosome in epithelial cells to induce the epithelial barrier dysfunction.

Myosin VI contributes to maintaining epithelial barrier function.

BACKGROUND: Epithelial barrier dysfunction is associated with the pathogenesis of a number of immune inflammations; the etiology is not fully understood. The fusion of endosome/lysosome is a critical process in the degradation of endocytic antigens in epithelial cells. Recent reports indicate that myosin VI (myo6) is involved in the activities of endosomes. The present study aims to investigate the role of myo6 in epithelial barrier dysfunction. RESULTS: The endosome accumulation was observed in myo6-deficient Rmcs. More than 80% endosomes were fused with lysosomes in naïve Rmcs while less than 30% endosomes were fused with lysosomes in the myo6-deficient Rmcs. The myo6-deficient Rmc monolayers showed high permeability to a macromolecular antigen, ovalbumin, the latter still conserved the antigenicity, which induced strong T cell activation. CONCLUSIONS: We conclude that myo6 plays a critical role in the fusion of endosome/lysosome in Rmc epithelial cells. Deficiency of myo6 compromises the epithelial barrier function.

Integrin alphavbeta6 is involved in measles protein-induced airway immune suppression.

BACKGROUND AND AIMS: Measles infection causes immune suppression that contributes to morbidity and mortality of the patients; the mechanism is poorly understood. Regulatory T cells (Treg) play a critical role in immune suppression. Integrin alphavbeta6 (avb6) is associated with Treg's function. This study aims to investigate into the mechanism by which measles C protein (MVP)-induced avb6 contributes the generation of Tregs in the lung. METHOD: MVP was introduced to mouse lung by nasal drops. The expression of avb6 by lung tissue was examined by reverse transcription polymerase chain reaction and Western blotting. The development of tolerogenic dendritic cells (DC) and Tregs in the lung and their functions was examined by flow cytometry. The suppressor function of MVP-induced Tregs was examined by cell culture models. RESULTS: The exposure to MVP markedly increased the expression of avb6 in the lung epithelial cells. Administration of MVP significantly suppressed the levels of IL-4 and IFNγ as well as increases in Tregs in lung tissue. DCs captured the MVP in the lung and differentiate into tolerogenic DCs; the latter has the ability to induce Treg development in the lung. Activation of MVP-induced Tregs powerfully suppressed polarized CD4(+) T cells. CONCLUSIONS: Exposure to MVP can induce Treg development in the lung that plays an important role in the suppression of CD4(+) T cell function.

Overwhelming postsplenectomy infection due to Mycoplasma pneumoniae in an asplenic cirrhotic patient: case report.

BACKGROUND: Mycoplasma pneumoniae infection is usually self-limited, but some fulminant cases are fatal, even when occurring in previously healthy individuals. It can also be the cause of overwhelming postsplenectomy infection (OPSI). CASE PRESENTATION: We report a case of OPSI in a 41-year-old woman with hypersplenism associated with hepatitis B cirrhosis. We detected a significant Mycoplasma pneumoniae agglutination titer, but no evidence of infection with Chlamydia pneumoniae, Legionnella spp., or any other bacterial or fungal pathogens. She eventually died despite aggressive therapy. CONCLUSIONS: M. pneumoniae could be an underestimated cause of OPSI, and should be suspected in fulminant infectious cases in asplenic patients.

Dobutamine enhances alveolar fluid clearance in a rat model of acute lung injury.

Acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome (ARDS), remain leading factors for morbidity and mortality in critically ill patients. A significant aspect of ALI and ARDS is impaired alveolar fluid clearance (AFC). Improvements in therapies for these types of respiratory illnesses will require an understanding of the mechanisms that control AFC. The present study was designed to determine whether the administration of dobutamine decreases pulmonary edema and stimulates AFC in a rat model of lipopolysaccharide-induced lung injury. Adult male Sprague-Dawley rats were randomly divided into three groups: control, lipopolysaccharide, and lipopolysaccharide + dobutamine. The effect of dobutamine on AFC and the expression of aquaporin-1 and aquaporin-5 were examined. Lipopolysaccharide administration results in significant lung injury with impaired AFC, while dobutamine improves alveolar fluid reabsorption with elevation of aquaporin-1 and aquaporin-5. Our study indicates that dobutamine may enhance alveolar fluid reabsorption by increasing the expression of aquaporin-1 and aquaporin-5.

When to initialize enteral nutrition in patients with severe acute pancreatitis? A retrospective review in a single institution experience (2003-2013).

OBJECTIVE: The present retrospective study aimed to analyze the optimal time to initiate enteral nutrition (EN) in patients with severe acute pancreatitis at a single Chinese institution (China Medical University Hospital). METHODS: A total of 1196 patients with severe acute pancreatitis were admitted in the intensive care unit between November 2003 and June 2013; 1092 patients were selected and were divided into the early and delayed EN groups, according to their initial timing of EN. RESULTS: Five hundred sixty-six patients were administered with the delayed EN, and 526 with the early EN. Both groups had similar severity of pancreatic necrosis, but organ failure developed in 81% patients of the delayed EN group and 21% in the early EN group (P < 0.01). The numbers of septic necrosis and morbidity were significantly higher in the delayed EN group than in the early EN (P < 0.01). CONCLUSIONS: The early EN had significant benefits over the delayed EN in the decrease of organ failure and mortality; our findings suggested that the first 48 hours of administration in the intensive care unit was the optimal time to start EN.

Total enteral nutrition in prevention of pancreatic necrotic infection in severe acute pancreatitis.

OBJECTIVE: This study was designed to evaluate the effects of total enteral nutrition and total parenteral nutrition in prevention of pancreatic necrotic infection in severe acute pancreatitis. METHODS: One hundred seven patients were enrolled in the study between 2003 and 2007. In the first week of hospitalization, they were randomized to feeding by either total parenteral nutrition (54 patients) or total enteral nutrition (53 patients). All patients were concomitantly administered with sufficient prophylactic antibiotics. Computed tomographic scan and C-reactive protein level indicated a similar clinical severity in both groups. RESULTS: Eighty percent of the patients developed organ failure in the group with total parenteral nutrition, which was higher than that in the group with total enteral nutrition (21%). Eighty percent and 22% (P < 0.05) of the patients in the total parenteral nutrition and total enteral nutrition groups, respectively, underwent surgical intervention. The incidence of pancreatic septic necroses in the group with total enteral nutrition (23%) was lower than that in the group with total parenteral nutrition (72%, P < 0.05). Mortality in the total parenteral nutrition group (43%) was higher than in the total enteral nutrition group (11%, P < 0.05). CONCLUSION: Total enteral nutrition is better than total parenteral nutrition in the prevention of pancreatic necrotic infection in severe acute pancreatitis.