Protective effects of HTD4010, a Reg3a/PAP-derived peptide, in a mouse model of hypertriglyceridemic acute pancreatitis: Involvement of TLR4/NF-kappa B

Involvement of circ_0029407 in Caerulein-Evoked Cytotoxicity in Human Pancreatic Cells via the miR-579-3p/TLR4/NF-κB Pathway

Acute pancreatitis (AP) is the most prevalent gastrointestinal inflammatory disease. Circular RNAs (circRNAs) are implicated in the development of AP. Here, we identified the precise action of circ_0029407 in AP development. Human pancreatic epithelial cells (HPECs) were stimulated with caerulein. Cell viability, proliferation, and apoptosis were gauged by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays, respectively. Circ_0029407, microRNA (miR)-579-3p, and toll-like receptor 4 (TLR4) were quantified by a qRT-PCR or western blot assay. Dual-luciferase reporter and RNA pull-down assays were performed to evaluate the direct relationship between miR-579-3p and circ_0029407 or TLR4. Our results indicated that circ_0029407 was markedly overexpressed in AP serum samples and caerulein-stimulated HPECs. Reduction of circ_0029407 attenuated caerulein-imposed HPEC damage by promoting cell proliferation and repressing cell apoptosis and inflammation. Mechanistically, circ_0029407 contained a miR-579-3p binding site, and miR-579-3p downregulation reversed the effect of circ_0029407 reduction on caerulein-imposed HPEC damage. TLR4 was identified as a direct and functional target of miR-579-3p, and TLR4 overexpression reversed the impact of miR-579-3p upregulation on attenuating caerulein-imposed HPEC damage. Moreover, circ_0029407 regulated the TLR4/nuclear factor NF-kappaB (NF-κB) signaling by acting as a competing endogenous RNA (ceRNA) for miR-579-3p. Our study suggests that circ_0029407 regulates caerulein-imposed cell injury in human pancreatic cells at least in part via the TLR4/NF-κB signaling pathway by functioning as a ceRNA for miR-579-3p.

Intraduodenal administration of Reg3g improves gut barrier function and mitigates hepatic steatosis in mice

Regenerating islet-derived protein 3 gamma (Reg3g), a gut peptide has been implicated in host defense and various physiological functions including metabolic regulation. Emerging evidence has demonstrated that peripheral administration of Reg3g results in improved glucose regulation as a gut hormone. In this study, we explored the therapeutic potential of Reg3g through intraduodenal infusion in mouse models of metabolic disorders. The objective of this study was to test the hypothesis that administered Reg3g into the intestinal lumen contributes to metabolic improvements by enhancing gut barrier function. Our mouse studies revealed that duodenal infusion of Reg3g reduces gut permeability and systemic endotoxemia. Studies with intestinal organoids supported the role of Reg3g in preserving cellular integrity and antioxidant gene expression under fructose-induced stress. Although Reg3g treatment results in little change to body weight, food intake, or glucose tolerance, Reg3g-treated mice exhibited reduced hepatic lipid accumulation along with the downregulation of lipogenic pathway genes. These data point toward the positive impact of Reg3g administration through intraduodenal infusion to regulate the intricate cross talk between gut barrier function and hepatic steatosis with the gut-liver axis.NEW & NOTEWORTHY This study shows that intraduodenal administration of the gut peptide, regenerating islet-derived protein 3 g (Reg3g), reduces hepatic lipid accumulation, improves gut barrier function, and lowers systemic endotoxemia in mouse models of metabolic disorders. These findings elucidate the therapeutic benefits of Reg3g administration into the gut.

Triglycerides: A Sensitizer but Not a Trigger for Hypertriglyceridemic Acute Pancreatitis

BACKGROUND

The incidence of hypertriglyceridemic acute pancreatitis (HTG-AP) is increasing. Although the guideline defines the diagnostic criteria as triglyceride (TG) greater than 11.3 mmol/L, there is actually no specific threshold. Many people with hypertriglyceridemia (HTG) or obvious chyloid blood do not develop acute pancreatitis (AP).

AIMS

To explore the role of HTG in the pathogenesis of AP.

METHODS

Thirty-six male SD rats were randomly assigned into normal control, AP, HTG, HTG-AP, low-dose fenofibrate and high-dose fenofibrate groups. Serum indices and cytokine levels in serum, and pathological changes in pancreatic tissues were observed. The expression levels of TLR4 and NF-κBp65 in pancreatic tissues were detected by immunohistochemistry and Western blot.

RESULTS

In normal rats, HTG alone did not induce AP. However, after establishing the HTG-AP model with Poloxam 407 and L-arginine, serum-free fatty acid and TG levels were positively correlated with the levels of lipase, amylase, IL-1β, IL-6, pancreatic inflammation scores, and the expressions of TLR4 and NF-κBp65 (all P < 0.001). Expressions of TLR4 and NF-κBp65 were significantly increased in the pancreatic tissues of HTG-AP rats. Fenofibrate effectively decreased TG levels in HTG-AP rats and reduced the expression of TLR4 and NF-κBp65 (all P < 0.001).

CONCLUSIONS

HTG does not directly cause AP, but rather increases the susceptibility to AP or aggravates the inflammatory response. It is more like a sensitizer of inflammation rather than an activator.