Xuebijing Injection Regulates Mitochondrial N-formyl Peptides/NLRP3 Inflammatory Pathway to Treat Severe Acute Pancreatitis in Rats / 中国实验方剂学杂志

ObjectiveTo investigate the therapeutic effect of Xuebijing injection （XBJ） on sodium taurocholate （Na-Tc）-induced severe acute pancreatitis （SAP） in rats. MethodForty rats were randomly assigned into 5 groups： sham operation group， SAP model group， and low-， medium-， and high-dose （4， 8， 12 mL·kg·d-1， respectively） XBJ groups. SAP model was established by retrograde injection of Na-Tc （1 mL·kg-1） into the biliary and pancreatic ducts. XBJ was injected intraperitoneally 3 days before and 0.5 h after modeling. The ascitic fluid volume and the pancreas weight-to-body weight ratio were measured. The pathological changes of pancreatic tissue were observed via hematoxylin-eosin （HE） staining. The protein levels of formyl peptide receptor 1 （FPR1） and nucleotide-binding oligomerization domain-like receptor 3 （NLRP3） in pancreatic tissue were detected by immunohistochemistry. Western blot was employed to determine the expression levels of NADH-ubiquinone oxidoreductase chains 1-6 （MT-ND1， MT-ND2， MT-ND3， MT-ND4， MT-ND5， and MT-ND6） in rat plasma. ResultCompared with sham operation group， the SAP model group showcased increased ascitic fluid volume and pancreas weight-to-body weight ratio （P<0.05）， serious lesions in pancreatic tissue， increased total pathological score （P<0.05）， and up-regulated protein levels of FPR1 and NLRP3 in pancreatic tissue （P<0.05）. The model group had lower MT-ND2 level （P<0.05） and higher MT-ND1， MT-ND3， and MT-ND6 levels in plasma （P<0.05） than the sham operation group， while MT-ND4 and MT-ND5 had no significant differences between the two groups. Compared with SAP model group， the XBJ treatment decreased ascitic fluid volume and pancreas weight-to-body weight ratio （P<0.01）， ameliorated pancreatic lesions， and down-regulated the protein levels of FPR1 and NLRP3 in pancreatic tissue （P<0.01）. The treatments， especially high-dose XBJ （P<0.01）， down-regulated the expression of MT-ND1 （P<0.01）， MT-ND3 （P<0.01）， MT-ND6 （P<0.01）， and MT-ND4 and did not change that of MT-ND5. ConclusionXBJ may antagonize partial mitochondrial N-formyl peptides and excessive inflammatory response mediated by FPR1/NLRP3 to treat SAP in rats.

Mitochondrial N-formyl peptides cause airway contraction and lung neutrophil infiltration via formyl peptide receptor activation.

Respiratory failure is a common characteristic of systemic inflammatory response syndrome (SIRS) and sepsis. Trauma and severe blood loss cause the release of endogenous molecules known as damage-associated molecular patterns (DAMPs). Mitochondrial N-formyl peptides (F-MITs) are DAMPs that share similarities with bacterial N-formylated peptides, and are potent immune system activators. Recently, we observed that hemorrhagic shock-induced increases in plasma levels of F-MITs associated with lung damage, and that antagonism of formyl peptide receptors (FPR) ameliorated hemorrhagic shock-induced lung injury in rats. Corroborating these data, in the present study, it was observed that F-MITs expression is higher in plasma samples from trauma patients with SIRS or sepsis when compared to control trauma group. Therefore, to better understand the role of F-MITs in the regulation of lung and airway function, we studied the hypothesis that F-MITs lead to airway contraction and lung inflammation. We observed that F-MITs induced concentration-dependent contraction in trachea, bronchi and bronchioles. However, pre-treatment with mast cells degranulator or FPR antagonist decreased this response. Finally, intratracheal challenge with F-MITs increased neutrophil elastase expression in lung and inducible nitric oxide synthase and cell division control protein 42 expression in all airway segments. These data suggest that F-MITs could be a putative target to treat respiratory failure in trauma patients.

Mitochondrial N-formyl peptides induce cardiovascular collapse and sepsis-like syndrome.

Fifty percent of trauma patients who present sepsis-like syndrome do not have bacterial infections. This condition is known as systemic inflammatory response syndrome (SIRS). A unifying factor of SIRS and sepsis is cardiovascular collapse. Trauma and severe blood loss cause the release of endogenous molecules known as damage-associated molecular patterns. Mitochondrial N-formyl peptides (F-MIT) are damage-associated molecular patterns that share similarities with bacterial N-formylated peptides and are potent immune system activators. The goal of this study was to investigate whether F-MIT trigger SIRS, including hypotension and vascular collapse via formyl peptide receptor (FPR) activation. We evaluated cardiovascular parameters in Wistar rats treated with FPR or histamine receptor antagonists and inhibitors of the nitric oxide pathway before and after F-MIT infusion. F-MIT, but not nonformylated peptides or mitochondrial DNA, induced severe hypotension via FPR activation and nitric oxide and histamine release. Moreover, F-MIT infusion induced hyperthermia, blood clotting, and increased vascular permeability. To evaluate the role of leukocytes in F-MIT-induced hypotension, neutrophil, basophil, or mast cells were depleted. Depletion of basophils, but not neutrophils or mast cells, abolished F-MIT-induced hypotension. Rats that underwent hemorrhagic shock increased plasma levels of mitochondrial formylated proteins associated with lung damage and antagonism of FPR ameliorated hemorrhagic shock-induced lung injury. Finally, F-MIT induced vasodilatation in isolated resistance arteries via FPR activation; however, F-MIT impaired endothelium-dependent relaxation in the presence of blood. These data suggest that F-MIT may be the link among trauma, SIRS, and cardiovascular collapse.