Acute Intoxication With Alcohol Reduces Trauma-Induced Proinflammatory Response and Barrier Breakdown in the Lung via the Wnt/β-Catenin Signaling Pathway

Abstract

BackgroundTrauma is the third leading cause of mortality worldwide. Upon admission, up to 50% of traumatized patients are acutely intoxicated with alcohol, which might lead to aberrant immune responses. An excessive and uncontrolled inflammatory response to injury is associated with damage to trauma-distant organs. We hypothesize that, along with inflammation-induced apoptosis, the activation of the Wnt/β-catenin signaling pathway would cause breakdown of the lung barrier and the development of lung injury after trauma. It remains unclear whether ethanol intoxication (EI) prior to trauma and hemorrhagic shock will attenuate inflammation and organ injury.MethodsIn this study, 14 male C57BL/6J mice were randomly assigned to two groups and exposed either to EtOH or to NaCl as a control by an oral gavage before receiving a femur fracture (Fx) and hemorrhagic shock, followed by resuscitation (THFx). Fourteen sham animals received either EtOH or NaCl and underwent surgical procedures without THFx induction. After 24 h, oil red O staining of fatty vacuoles in the liver was performed. Histological lung injury score (LIS) was assessed to analyze the trauma-induced RLI. Gene expression of Cxcl1, Il-1β, Muc5ac, Tnf, and Tnfrsf10b as well as CXCL1, IL-1β, and TNF protein levels in the lung tissue and bronchoalveolar lavage fluid were determined by RT-qPCR, ELISA, and immunohistological analyses. Infiltrating polymorphonuclear leukocytes (PMNLs) were examined via immunostaining. Apoptosis was detected by activated caspase-3 expression in the lung tissue. To confirm active Wnt signaling after trauma, gene expression of Wnt3a and its inhibitor sclerostin (Sost) was determined. Protein expression of A20 and RIPK4 as possible modulators of the Wnt signaling pathway was analyzed via immunofluorescence.ResultsSignificant fatty changes in the liver confirmed the acute EI. Histopathology and decreased Muc5ac expression revealed an increased lung barrier breakdown and concomitant lung injury after THFx versus sham. EI prior trauma decreased lung injury. THFx increased not only the gene expression of pro-inflammatory markers but also the pulmonary infiltration with PMNL and apoptosis versus sham, while EI prior to THFx reduced those changes significantly. EI increased the THFx-reduced gene expression of Sost and reduced the THFx-induced expression of Wnt3a. While A20, RIPK4, and membranous β-catenin were significantly reduced after trauma, they were enhanced upon EI.ConclusionThese findings suggest that acute EI alleviates the uncontrolled inflammatory response and lung barrier breakdown after trauma by suppressing the Wnt/β-catenin signaling pathway.

Age-related exacerbation of lung damage after trauma is associated with increased expression of inflammasome components

“…In a recent study applying this model, it was shown that aged mice had significantly lower total bone and callus volume, decreased share of callus per total bone volume, less trabecular structures as well as the reduction of the elastic limit (31), thus, our model of femoral fracture mimics the human situation. Furthermore, it was demonstrated that THFx induced an uncontrolled inflammatory response and lung barrier breakdown in young mice (33), findings that support our hypothesis. This study's results have the potential to guide future research and pre-clinical approaches for addressing these conditions in both younger and older populations.…”

“…Trauma is the leading cause of death and disability worldwide ( 35 ). In young mice, femoral fracture following pressure-controlled hemorrhagic shock can cause increased uncontrolled inflammation in the lungs as well as disruption of the pulmonary barrier ( 33 ), yet the current research has not fully explained the effects of aging on lung injury and the pulmonary inflammatory response after THFx. Our study aimed to investigate how aging influences the typical NF-κB signaling pathway as well as the expression of inflammasome components that mediate the lung inflammatory response after THFx.…”

“…To quantify the histopathological damage in the lungs, independent examiners assessed the lungs using the method described previously. Briefly, sections of lungs were examined for desquamation, dystelectasis/atelectasis, emphysema, congestion, interstitial thickness/infiltration with inflammatory cells, and bronchial exudate ( 33 , 34 ).…”

The Wnt/β-catenin pathway regulates inflammation and apoptosis in ventilator-induced lung injury

“…In the cytoplasm, axis inhibitor (AXIN), glycogen synthase kinase 3β (GSK-3β), and adenomatous polyposis coli (APC) jointly promote β-catenin ubiquitination and degradation, thereby inhibiting signaling [10]. The Wnt/β-catenin pathway is critical in lung development and repair [7,11,12], and its abnormal regulation is closely correlated with lung diseases progression, such as lung cancer, bronchopulmonary dysplasia, idiopathic pulmonary fibrosis (IPF), asthma, and acute respiratory distress syndrome (ARDS) [10,[13][14][15][16]. Its roles include regulating inflammation, oxidative stress, cell differentiation, and apoptosis [12,17,18].…”