Chloroquine relieves acute lung injury in rats with acute hemorrhagic necrotizing pancreatitis

Hypoxia drives murine neutrophil protein scavenging to maintain central carbon metabolism

Limiting dysfunctional neutrophilic inflammation while preserving effective immunity requires a better understanding of the processes that dictate neutrophil function in the tissues. Quantitative mass-spectrometry identified how inflammatory murine neutrophils regulated expression of cell surface receptors, signal transduction networks, and metabolic machinery to shape neutrophil phenotypes in response to hypoxia. Through the tracing of labeled amino acids into metabolic enzymes, proinflammatory mediators, and granule proteins, we demonstrated that ongoing protein synthesis shapes the neutrophil proteome. To maintain energy supplies in the tissues, neutrophils consumed extracellular proteins to fuel central carbon metabolism. The physiological stresses of hypoxia and hypoglycemia, characteristic of inflamed tissues, promoted this extracellular protein scavenging with activation of the lysosomal compartment, further driving exploitation of the protein-rich inflammatory milieu. This study provides a comprehensive map of neutrophil proteomes, analysis of which has led to the identification of active catabolic and anabolic pathways that enable neutrophils to sustain synthetic and effector functions in the tissues.

Erlotinib Protects LPS-Induced Acute Lung Injury in Mice by Inhibiting EGFR/TLR4 Signaling Pathway

Epidermal growth factor receptor (EGFR) has been reported to initiate the inflammatory response, but its activation in lipopolysaccharide (LPS)-induced murine model of acute lung injury (ALI) remains unclear. In this study, we investigated the role of EGFR in the LPS-induced murine model of ALI and explored whether its inhibitor erlotinib could affect the progression of lung injury. We first detected the phosphorylated EGFR (p-EGFR)/EGFR ratio at different time points after LPS stimulation, and then different concentrations of erlotinib were used to treat mice at 1 h before LPS stimulation and collected samples at the time point of the highest p-EGFR/EGFR ratio. Lung injury indicators were detected and compared among groups. EGFR and toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signal transduction factors, including p-EGFR, p-AKT, p-ERK1/2, p-p65, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), were measured with western blot. We found that the mice challenged with LPS suffered from the most serious lung injury at 24 h after LPS stimulation when the p-EGFR/EGFR ratio was relatively the highest. Erlotinib significantly diminished LPS-induced exudation of total cells, neutrophils, and proteins in BALF. Both the ELISA and western blot results showed that erlotinib attenuated the expression of TNF-α and IL-1β in LPS-induced ALI in mice. Inhibition of EGFR by erlotinib downregulated the expression of p-p65 protein level as well as blocked the activation of AKT and ERK1/2 signaling pathway. Taken together, erlotinib alleviated the LPS-induced ALI in a dose-dependent manner by suppressing EGFR activation and downregulating the NF-κB-mediated secretion of proinflammatory cytokines.

Enhanced Neutrophil Extracellular Trap Formation in Acute Pancreatitis Contributes to Disease Severity and Is Reduced by Chloroquine

Background: Neutrophil extracellular traps (NETs) are generated when activated neutrophils, driven by PAD4, release their DNA, histones, HMGB1, and other intracellular granule components. NETs play a role in acute pancreatitis, worsening pancreatic inflammation, and promoting pancreatic duct obstruction. The autophagy inhibitor chloroquine (CQ) inhibits NET formation; therefore, we investigated the impact of CQ mediated NET inhibition in murine models of pancreatitis and human correlative studies.

Methods: L-arginine and choline deficient ethionine supplemented (CDE) diet models of acute pancreatitis were studied in wild type and PAD4^−/− mice, incapable of forming NETs. Isolated neutrophils were stimulated to induce NET formation and visualized with fluorescence microscopy. CQ treatment (0.5 mg/ml PO) was initiated after induction of pancreatitis. Biomarkers of NET formation, including cell-free DNA, citrullinated histone H3 (CitH3), and MPO-DNA conjugates were measured in murine serum and correlative human patient serum samples.

Results: We first confirmed the role of NETs in the pathophysiology of acute pancreatitis by demonstrating that PAD4^−/− mice had decreased pancreatitis severity and improved survival compared to wild-type controls. Furthermore, patients with severe acute pancreatitis had elevated levels of cell-free DNA and MPO-DNA conjugates, consistent with NET formation. Neutrophils from mice with pancreatitis were more prone to NET formation and CQ decreased this propensity to form NETs. CQ significantly reduced serum cell-free DNA and citrullinated histone H3 in murine models of pancreatitis, increasing survival in both models.

Conclusions: Inhibition of NETs with CQ decreases the severity of acute pancreatitis and improves survival. Translating these findings into clinical trials of acute pancreatitis is warranted.

Chloroquine attenuates paraquat-induced lung injury in mice by altering inflammation, oxidative stress and fibrosis

Paraquat is one of the most extensively used herbicides and has high toxicity for humans and animals. However, there is no effective treatment for paraquat poisoning. The aim of the present study was to evaluate the effects of chloroquine on paraquat-induced lung injury in mice. Mice received a single intraperitoneal injection of paraquat and a daily intraperitoneal injection of the indicated dosages of chloroquine or dexamethasone. The histological changes, inflammation and oxidative stress in the lungs were examined at day 3, and the degree of pulmonary fibrosis was examined at day 28. H&E staining showed that chloroquine markedly attenuated lung injury induced by paraquat. In addition, the inflammatory responses induced by paraquat were inhibited after treatment with chloroquine, as indicated by the decreased number of leukocytes, the reduced levels of TNF-α, IL-1β and IL-6 in the bronchoalveolar lavage fluid, the reduced NO content, and downregulation of iNOS expression in lung tissues. No different effect was found between high-dose chloroquine and dexamethasone. Additionally, the treatment with chloroquine increased the activity of SOD and decreased the level of MDA in the lung tissues. The expressions of the anti-oxidative proteins, Nrf2, HO-1 and NQO1, were also upregulated by chloroquine treatment. The high-dose chloroquine was more effective than dexamethasone in its anti-oxidation ability. Finally, the results of Masson's staining illustrated that chloroquine markedly attenuated fibrosis in the paraquat-exposed lungs. Immunohistochemistry staining showed that the expressions of the pro-fibrotic proteins TGF-β and α-SMA were downregulated after treatment with chloroquine. In conclusion, chloroquine effectively attenuated paraquat-induced lung injury in mice.

Lung Inflammation Associated With Clinical Acute Necrotizing Pancreatitis in Dogs

Although dogs with acute necrotizing pancreatitis (ANP) can develop respiratory complications, there are no data describing lung injury in clinical cases of ANP in dogs. Therefore, we conducted a study to characterize lung injury and determine if pulmonary intravascular macrophages (PIMs) are induced in dogs with ANP ( n = 21) compared with control dogs ( n = 6). Two pathologists independently graded histologic sections of pancreas from clinical cases to characterize the severity of ANP (total scores of 3–10) compared with controls showing histologically normal pancreas (total scores of 0). Based on histological grading, lungs from dogs with ANP showed inflammation (median score, 1.5; range, 0–3), but the scores did not differ statistically from the control lungs (median score, 0.5; range, 0–2). A grid intersects-counting method showed an increase in the numbers of MAC387-positive alveolar septal mononuclear phagocyte profiles in lungs of dogs with ANP (ratio median, 0.0243; range, 0.0093–0.0734, with 2 outliers at 0.1523 and 0.1978) compared with controls (ratio median, 0.0019; range, 0.0017–0.0031; P < .0001). Only dogs with ANP showed labeling for von Willebrand factor in alveolar septal capillary endothelial cells, septal inflammatory cells, and alveolar macrophages. Toll-like receptor 4 and interleukin 6 were variably expressed in alveolar macrophages and septal inflammatory cells in lungs from both ANP and control dogs. Inducible nitric oxide synthase was detected in alveolar macrophages of dogs with ANP only. These data show that dogs with ANP have lung inflammation, including the recruitment of PIMs and expression of inflammatory mediators.

Chloroquine rescues A549 cells from paraquat-induced death

Paraquat (PQ) is a widely used herbicide associated with a high mortality rate, yet, there are no effective treatments for PQ poisoning. PQ may damage alveolar type II cells leading to moderate to severe acute respiratory distress syndrome (ARDS). The present study was undertaken to show that PQ causes alveolar type II (A549) cell death and to evaluate whether chloroquine (CQ) can protect A549 cells against PQ-induced cell death. The results showed that high concentrations of PQ resulted in toxicity, as indicated by a decrease in cell viability. More importantly, for the first time, CQ was found to improve cell viability of PQ treated A549 cells. Moreover, our data demonstrated that CQ increased lysosome-associated membrane protein-1, lysosome-associated membrane protein-2 and light chain-3 expressions, suggesting that the mechanism by which CQ rescues PQ-induced cytotoxicity may be through protection of the lysosomal membrane or up-regulation of autophagy. In conclusion, our study indicates that CQ may be used as a potential drug to rescue PQ-induced ARDS.

Correlation between serum levels of interleukin-6 and severity of acute pancreatitis

AIM: To assess the correlation between serum levels of interleukin (IL-6) and the severity of acute pancreatitis (AP).

METHODS: This study included 138 patients with severe AP (SAP), 126 with mild AP (MAP), and 150 healthy volunteers who underwent physical examination (control group). Serum levels of IL-6 in each group were detected and compared. The complications were recorded. The correlation between serum levels of IL-6 and Ranson score was analyzed, and the risk factors for the severity of AP were analyzed.

RESULTS: IL-6 level and Ranson score in the SAP group were both significantly higher than those in the MAP group and control group. IL-6 level and Ranson score in SAP patients with complications were significantly higher than those in SAP patients without complications (P < 0.05). Spearman correlation analysis showed that serum levels of IL-6 had a positive correlation with Ranson score. Using the severity of AP as the dependent variable, and age, gender, high Ranson score and high IL-6 level as the independent variables, we performed Logistic regression analysis and found that high IL-6 level was a risk factor for the severity of AP.

CONCLUSION: IL-6 is closely linked to the AP severity.