GV-971 prevents severe acute pancreatitis by remodeling the microbiota-metabolic-immune axis

Severe acute pancreatitis (SAP) is a life-threatening inflammatory condition with limited treatment options. The pathogenesis involves acinar cell death, immune cell infiltration, and the release of inflammatory mediators. Gut microbiota dysbiosis plays a significant role, exacerbating inflammation and contributing to systemic complications. Current treatments have limited efficacy, highlighting the urgent need for new therapeutic interventions. GV-971 (sodium oligomannate), approved for Alzheimer's disease, has shown promise in regulating gut microbiota. Given the role of gut dysbiosis in SAP, and similarities in immune dysfunction between neurodegenerative diseases and pancreatitis, the researchers explored GV-971's potential in treating SAP. This study investigates the protective effects of GV-971 against SAP, aiming to elucidate its mechanism of action through a comprehensive analysis involving microbiome sequencing, metabolomics, and immunology techniques.

Existing literature highlights the significant role of inflammation and gut microbiota dysbiosis in the pathogenesis of SAP. Studies have demonstrated the involvement of innate immune cells, such as macrophages and neutrophils, in the inflammatory response. The release of damage-associated molecular patterns (DAMPs) from damaged acinar cells triggers a cascade of inflammatory events. Intestinal dysfunction and alterations in gut microbiota composition further exacerbate the inflammatory process, leading to systemic complications and high mortality rates. While prebiotics and probiotics have shown some promise in modulating gut microbiota and attenuating inflammation, effective clinical drugs remain limited. Previous research on GV-971, an oligosaccharide derived from marine brown algae, has indicated its ability to regulate intestinal microbiota and reduce neuroinflammation, thus prompting the investigation of its potential application in SAP.

The study utilized several mouse models of SAP, including caerulein/lipopolysaccharide (LPS)-induced and L-arginine-induced models. Mice were pre-treated with GV-971 at varying doses for one week before SAP induction. The impact of GV-971 on SAP severity was assessed through various parameters, including mortality rates, serum levels of inflammatory cytokines (IL-6, IL-8), pancreatic morphology (H&E staining, Sirius red staining), and serum levels of lipase and amylase. To investigate the role of gut microbiota, 16S rRNA sequencing was performed on cecal contents to analyze the bacterial composition. Targeted metabolomics using UPLC-MS/MS was employed to identify differential metabolites in cecal contents. Mass cytometry was used to analyze peripheral and intestinal immune cell populations. Intestinal microbiota transplantation (IMT) experiments were conducted to assess the causal role of GV-971-modified microbiota. Macrophage depletion experiments were performed using clodronate liposomes to examine the role of macrophages in GV-971's protective effects. Finally, in vitro experiments using RAW 264.7 macrophages were conducted to investigate the effects of propionate and butyrate on macrophage polarization and MAPK pathway activation. RNA sequencing and Western blotting were used to explore the underlying molecular mechanisms.

GV-971 significantly reduced mortality and alleviated the severity of SAP in multiple mouse models. Treatment resulted in decreased serum levels of IL-6 and IL-8, reduced pancreatic inflammation and acinar cell death, and improved organ function (kidney and lung). GV-971 remodeled the gut microbiota, increasing the abundance of *Faecalibacterium* and other beneficial bacteria while decreasing potentially harmful bacteria such as *Pseudomonas* and *Melissococcus*. Metabolomics analysis showed increased levels of SCFAs, particularly propionate and butyrate, in GV-971-treated mice. IMT experiments demonstrated that GV-971-modified microbiota conferred protection against SAP. Macrophage depletion abolished GV-971's protective effects, highlighting the importance of macrophages in its mechanism of action. In vitro studies showed that propionate and butyrate inhibited LPS-induced macrophage M1 polarization and reduced the production of pro-inflammatory cytokines by inhibiting the MAPK signaling pathway. Mass cytometry revealed that GV-971 mitigated SAP-induced alterations in peripheral and intestinal immune cell populations, particularly by increasing regulatory T cells.

The findings demonstrate that GV-971 exerts its protective effect against SAP by modulating the microbiota-metabolic-immune axis. GV-971's impact on gut microbiota leads to increased production of SCFAs, which in turn inhibit macrophage M1 polarization and reduce inflammation. The study’s results support the growing body of evidence highlighting the crucial role of gut microbiota in the pathogenesis of inflammatory diseases. The findings suggest that manipulating gut microbiota composition and metabolism through targeted therapies could be a promising approach for treating SAP. The use of GV-971, already approved for another indication, offers a potential advantage for rapid translation into clinical practice. However, further investigation is needed to clarify the specific interactions between GV-971 and *Faecalibacterium*, and to determine whether the observed effects are specific to the mouse models used.

This study provides strong evidence for the therapeutic potential of GV-971 in preventing severe acute pancreatitis. The mechanism involves remodeling of the gut microbiota, leading to increased production of protective SCFAs that inhibit inflammation through the MAPK pathway. Further research should focus on clinical trials to evaluate the efficacy and safety of GV-971 in humans with SAP, as well as further mechanistic studies to fully elucidate the complex interactions within the microbiota-metabolic-immune axis.

The study was conducted using mouse models of SAP, which may not fully recapitulate the complexity of human disease. The specific mechanisms by which GV-971 alters gut microbiota and the precise interactions between SCFAs and immune cells require further investigation. The study primarily focused on male mice; thus, further research is needed to determine whether the findings are generalizable to female mice and humans.