S1PR2 participates in intestinal injury in severe acute pancreatitis by regulating macrophage pyroptosis.

Background: Severe acute pancreatitis (SAP) is an inflammatory disorder affecting the gastrointestinal system. Intestinal injury plays an important role in the treatment of severe acute pancreatitis. In this study, we mainly investigated the role of S1PR2 in regulating macrophage pyroptosis in the intestinal injury of severe acute pancreatitis. Methods: The SAP model was constructed using cerulein and lipopolysaccharide, and the expression of S1PR2 was inhibited by JTE-013 to detect the degree of pancreatitis and intestinal tissue damage in mice. Meanwhile, the level of pyroptosis-related protein was detected by western blot, the level of related mRNA was detected by PCR, and the level of serum inflammatory factors was detected by ELISA. In vitro experiments, LPS+ATP was used to construct the pyroptosis model of THP-1. After knockdown and overexpression of S1PR2, the pyroptosis proteins level was detected by western blot, the related mRNA level was detected by PCR, and the level of cell supernatant inflammatory factors were detected by ELISA. A rescue experiment was used to verify the sufficient necessity of the RhoA/ROCK pathway in S1PR2-induced pyroptosis. Meanwhile, THP-1 and FHC were co-cultured to verify that cytokines released by THP-1 after damage could regulate FHC damage. Results: Our results demonstrated that JTE-013 effectively attenuated intestinal injury and inflammation in mice with SAP. Furthermore, we observed a significant reduction in the expression of pyroptosis-related proteins within the intestinal tissue of SAP mice upon treatment with JTE-013. We confirmed the involvement of S1PR2 in THP-1 cell pyroptosis in vitro. Specifically, activation of S1PR2 triggered pyroptosis in THP-1 cells through the RhoA/ROCK signaling pathway. Moreover, it was observed that inflammatory factors released during THP-1 cell pyroptosis exerted an impact on cohesin expression in FHC cells. Conclusion: The involvement of S1PR2 in SAP-induced intestinal mucosal injury may be attributed to its regulation of macrophage pyroptosis.

Corrigendum: Naringenin protects against acute pancreatitis-associated intestinal injury by inhibiting NLRP3 inflammasome activation via AhR signaling.

[This corrects the article DOI: 10.3389/fphar.2023.1090261.].

Early Predictors of Infected Pancreatic Necrosis in Severe Acute Pancreatitis: Implications of Neutrophil to Lymphocyte Ratio, Blood Procalcitonin Concentration, and Modified CT Severity Index.

BACKGROUND: Infected pancreatic necrosis (IPN) accounts for 30% mortality in severe acute pancreatitis (SAP). Early prediction of IPN occurrence is critical for prophylactic measures to be taken. This study aimed to evaluate the predicting value for IPN of combined markers at early stages of SAP. METHODS: The clinical records of 324 SAP patients admitted within 48 h after disease onset were retrospectively analyzed. As potential predictors, the neutrophil to lymphocyte ratio (NLR), blood procalcitonin (PCT) concentration on the 1st, 4th, and 7th day post admission, as well as modified computerized tomography severity index (MCTSI) on the 5-7th day post admission, were extracted. Correlations between these features with IPN were analyzed using logistic regression, and predictive values were estimated using the receiver operating characteristic curve analyses. RESULTS: NLR, PCT, body mass index, and MCTSI were significantly higher in the IPN group (p < 0.001) compared to the control, among which NLR, PCT, and MCTSI were identified as independent predictors for IPN in logistic regression model. Combination of these parameters yielded significant predicting values with an area under curve of 0.92, sensitivity of 97.2%, and specificity of 77.2% in receiver operating characteristic curve analysis. CONCLUSION: Combination of NLR, PCT, MCTSI might facilitate the prediction of IPN occurrence in SAP patients.

Naringenin protects against acute pancreatitis-associated intestinal injury by inhibiting NLRP3 inflammasome activation via AhR signaling.

Background: In this study, we examined the functions and mechanisms by which naringenin protects against SAP (severe acute pancreatitis)-related intestinal injury by modulating the AhR/NLRP3 signaling pathway. Material and methods: Fifteen healthy male C57BL/6 mice were randomly divided into SAP (n = 12) and normal (n = 3) groups. Mice in the SAP group received caerulein and lipopolysaccharide intraperitoneal injections and were then randomly assigned to the SAP, NAR, CH223191, and Dexamethasone (DEX) groups. Pathological changes in the pancreatic and intestinal mucosa were observed by Hematoxylin & Eosin (H&E) staining. In vitro, RAW264.7 cells were exposed to lipopolysaccharide and treated with naringenin. The levels of NLRP3, AhR, IL-1ß, TNF, and IL-6 in the SAP model and RAW264.7 cells were evaluated by enzyme-linked immunosorbent assay (ELISA), quantitative real-time PCR (qRT-PCR), western blot, and immunohistochemistry. The nuclear translocation of AhR was shown by immunofluorescence. AutoDockTools was used to predict the conformations of naringenin-AhR binding, and PyMol 2.4 was used to visualize the conformations. Results: Mouse pancreatic and intestinal injury was alleviated by treatment with naringenin. Naringenin inhibited the activation of the NLRP3 inflammasome and inhibited damage to intestinal tight junctions. Moreover, naringenin increased AhR nuclear translocation and activated the AhR pathway. Conclusion: Naringenin can reduce SAP-associated intestinal injury by inhibiting the activation of the NLRP3 inflammasome via the AhR signaling pathway.

Correlation Between Severity of Illness and Levels of Free Triiodothyronine, Interleukin-6, and Interleukin-10 in Patients with Acute Pancreatitis.

BACKGROUND Acute pancreatitis (AP) is a common acute abdominal disease. Rapid evaluation of the severity is important for AP prognosis and treatment. Free triiodothyronine (fT3) level is associated with the prognosis of AP patients. This study aimed to investigate the fT3 level in patients with acute pancreatitis; early warning signs of inflammation, including interleukin-6 (IL-6) and interleukin-10 (IL-10); and the correlation of fT3 level with illness severity. MATERIAL AND METHODS Enrolled AP patients (N=312) were divided into an SAP group (N=92) and a non-SAP group (N=220) according to the Revision of Atlanta classification. Blood or tissue samples and baseline clinical characteristics were recorded. The t test and chi-square test were used to evaluate differences between the 2 groups. Multivariate logistic regression analysis and receiver operating characteristic (ROC) curves were used to investigate protective factors. One-way repeated measures analysis of variance was used to evaluate the prognosis of SAP patients. RESULTS In our study, compared with APACHII score (AUC 0.829 [95% CIs 0.769-0.889]) and Ranson score (AUC 0.629 [95% CIs 0.542-0.715]), our predictive model (AUC 0.918 [95% CIs 0.875-0.961]) showed better prognostic performance in predicting poor patient outcomes. In the SAP group, changes in fT3 level were significantly associated with prognosis (P<0.05). CONCLUSIONS The predictive model can improve the diagnostic accuracy and prediction of the severity of disease. FT3 level could be used as an independent risk factor to predict the mortality of SAP patients.

[Mechanism of gasdermin D on intestinal injury in severe acute pancreatitis by mediating pyroptosis].

OBJECTIVE: To investigate the function of gasdermin D (GSDMD) in intestinal damage of mice with severe acute pancreatitis (SAP). METHODS: The healthy C57BL/6 mice were divided into four groups randomly, including normal saline (NS) group, small interfering RNA (siRNA)-NS group, SAP model group and siRNA-SAP group, with 6 mice in each group. The SAP mouse model was reproduced by intraperitoneal injection of caerulein 50 µg/kg combined with lipopolysaccharide (LPS) 10 mg/kg; the NS group was given the same amount of NS; in the siRNA-SAP group and siRNA-NS group, siRNA 50 mg/kg was injected through the tail vein three times before modeling or injection of NS. The blood of mice eyeball in each group was taken 12 hours after modeling, and serum interleukins (IL-1ß, IL-18) levels were detected by enzyme linked immunosorbent assay (ELISA). The mice were sacrificed to observe the general changes in abdominal cavity, the pancreas and ileum tissues were taken to observe the pathological changes under a light microscope. The expression of long-chain non-coding RNA uc.173 (lnc uc.173) was detected by reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemical method was used to detect the expression of tight junction proteins zonula occluden-1 (ZO-1) and Occludin in intestinal mucosal epithelial cells. Western blotting was used to detect the GSDMD protein expression level in the intestinal tissue. RESULTS: The serum levels of IL-1ß and IL-18 in the SAP model group were significantly higher than those in the NS group and the siRNA-NS group [IL-1ß (ng/L): 146.66±1.40 vs. 44.48±5.76, 81.49±10.75, IL-18 (ng/L): 950.47±177.09 vs. 115.43±16.40, 84.84±21.90, all P < 0.05]; and the levels of IL-1ß and IL-18 in the siRNA-SAP group were significantly lower than those in the SAP model group [IL-1ß (ng/L): 116.26±15.54 vs. 146.66±1.40, IL-18 (ng/L): 689.96±126.08 vs. 950.47±177.09, both P < 0.05]. General observation showed that there were no obvious abnormalities in the abdominal cavity of the mice in the NS and siRNA-NS groups; the mice in the SAP model group and the siRNA-SAP group had different degrees of edema and congestion in the intestine; compared with the SAP model group, the abnormalities in the siRNA-SAP group was significantly reduced. Under light microscope, there were no obvious changes in the pancreas and intestinal mucosa in the NS group and the siRNA-NS group; the pancreatic tissue of the SAP model group and the siRNA-SAP group had different degrees of edema, inflammatory cell infiltration, and lobular structure damage, and the intestinal mucosa was damaged to a certain degree, and the villi were broken to varying degrees, but the damage in the siRNA-SAP group was lighter. The results of RT-PCR showed that the expression of lnc uc.173 in the intestinal tissues of the model SAP group was significantly lower than that of the NS group and the siRNA-NS group (2-ΔΔCt: 0.26±0.12 vs. 1.01±0.37, 0.67±0.32, both P < 0.05), while the expression of lnc uc.173 in the siRNA-SAP group was significantly higher than that in the SAP model group (2-ΔΔCt: 0.60±0.39 vs. 0.26±0.12, P < 0.05). Immunohistochemistry showed that ZO-1 and Occludin proteins in the NS group were distributed along the epithelial cells of the intestinal mucosa, showing a strong expression; ZO-1 and Occludin expressions were significantly reduced in the SAP model group and siRNA-SAP group, but the expressions in the siRNA-SAP group was higher than that in the SAP model group. Western blotting showed that the expression level of GSDMD protein in the intestinal tissues of the SAP model group was significantly higher than that of the NS group and the siRNA-NS group [GSDMD protein (GSDMD-N/ß-actin): 1.99±0.46 vs. 1, 1.00±0.78, both P < 0.05]. Compared with the SAP model group, the expression of GSDMD protein in the siRNA-SAP group was significantly decreased [GSDMD protein (GSDMD-N/ß-actin): 1.42±0.42 vs. 1.99±0.46, P < 0.05]. CONCLUSIONS: The systemic inflammatory response and intestinal mucosal barrier damage of SAP mice may be related to the increase of GSDMD expression in intestinal tissues. GSDMD mediates cell pyrolysis to promote the release of inflammatory factors, cause intestinal injury, and down-regulate the expression of intestinal epithelial cell tight junction proteins such as ZO-1 and Occludin, resulting in intestinal mucosal damage.

Downregulating Gasdermin D Reduces Severe Acute Pancreatitis Associated with Pyroptosis.

BACKGROUND Intestinal injury plays a key role in the pathogenesis of severe acute pancreatitis (SAP). In this study, we investigated the protective function of downregulated Gasdermin D (GSDMD) in intestinal damage in a mouse model of severe acute pancreatitis (SAP). MATERIAL AND METHODS Twenty-four healthy male C57BL/6 mice were randomly divided into 4 groups - the NS group, the siRNA-NS group, the SAP group, and the siRNA-SAP group - with 6 mice in each group. SAP was induced in mice by intraperitoneal injection of caerulein and lipopolysaccharide. The pathological changes of pancreatic and the intestinal mucosa and the relative gene and protein expressions in each group were compared, and the levels of GSDMD and serum IL-1ß and IL-18 were evaluated after induction of the SAP model. RESULTS The mice in the SAP group were in more serious condition than those in the siRNA-SAP group, with various degrees of edema and hemorrhage in the intestinal tract. Under an optical microscope, the pathological changes of pancreatic tissue such as edema, inflammatory cell infiltration, and the damage of lobular structural were gradually increased in the SAP group and the siRNA-NS group. In addition, intestinal mucosal damage and intestinal villus breakage were found in the SAP group and the siRNA-NS group, and the latter was lighter than the former. Compared with the SAP group, the level of GSDMD protein expression in the siRNA-SAP group was lower, and the serum levels of IL-1ß and IL-18 were higher in the SAP group and siRNA-SAP group (P<0.05). Immunohistochemical analysis showed the occludin and ZO-1 proteins in the NS group had a strong brown linear signal, while the brown-positive signals were weaker in the siRNA-SAP group and the SAP group. CONCLUSIONS Downregulating GSDMD protein can reduce pancreatitis associated with pyroptosis.