A journey to and with the stars: The pancreatic stellate cell story.

The George E Palade Prize is the highest honour awarded by the International Association of Pancreatology, that recognises an individual who has made outstanding contributions to the understanding of the pancreas and pancreatic diseases. The 2023 Palade Prize was awarded to Professor Minoti Apte, University of New South Wales Sydney on September 16, 2023 during the Joint Meeting of the International Association of Pancreatology and the Indian Pancreas Club, held in Delhi, India. This paper summarises her Palade lecture wherein she reflects on her journey as a medical graduate, an academic and a researcher, with a particular focus on her team's pioneering work on pancreatic stellate cell biology and the role of these cells in health and disease. While there has been much progress in this field with the efforts of researchers worldwide, there is much still to be learned; thus it is a topic with ample scope for innovative research with the potential to translate into better outcomes for patients with pancreatic disease.

Fibroblast growth factor 21 ameliorates pancreatic fibrogenesis via regulating polarization of macrophages.

Chronic pancreatitis (CP) is a progressive, irreversible inflammatory and fibrotic disease. The characteristics of this disease are progressive inflammation, acinar atrophy and fibrosis. Numerous factors are involved in CP such as inflammation, and oxidative stress. Recently, it has been noted that fibroblast growth factor 21 (FGF-21) reduced the severity of acute pancreatitis in mice. However, whether FGF-21 has effects on CP remains unclear. Thus, the present study was undertaken to detect the effects of FGF-21 on l-arginine induced chronic pancreatitis/islet fibrosis in mice. We used l-arginine to create a CP model in C57BL/6 mice and treated these mice with FGF-21. Compared to normal mice, blood glucose and intra-peritoneal glucose tolerance test (IPGTT) revealed significant impairment in CP animal model. CP mice also had acinar atrophy, loss of pancreas morphology, inflammatory cells infiltration, extensive deposition of collagen, elevated -SMA expression, collagen I expression, serum amylase activity, MPO activity and MDA level. All these pathological changes were significantly improved by FGF-21 treatment. Moreover, FGF-21 ameliorated inflammatory state in the serum, pancreas and peritoneal macrophages of CP mice. Furthermore, we also found that FGF-21 could regulate differentiation of macrophages so as to improve pancreatic fibrogenesis in CP mice. Taken together, our study identifies the beneficial role of FGF-21 in CP and suggests that FGF-21 improves pancreatic fibrogenesis in CP via the mTOR pathway.

Pancreatic cancer: The microenvironment needs attention too!

The abundant stromal/desmoplastic reaction, a characteristic feature of a majority of pancreatic adenocarcinomas (PDAC), has only recently been receiving some attention regarding its possible role in the pathobiology of pancreatic cancer. It is now well established that the cells predominantly responsible for producing the collagenous stroma are pancreatic stellate cells (PSCs). In addition to extracellular matrix proteins, the stroma also exhibits cellular elements including, immune cells, endothelial cells and neural cells. Evidence is accumulating to indicate the presence of significant interactions between PSCs and cancer cells as well as between PSCs and other cell types in the stroma. The majority of research reports to date, using in vitro and in vivo approaches, suggest that these interactions facilitate local growth as well as distant metastasis of pancreatic cancer, although a recent study using animals depleted of myofibroblasts has raised some questions regarding the central role of myofibroblasts in cancer progression. Nonetheless, novel therapeutic strategies have been assessed, mainly in the pre-clinical setting, in a bid to interrupt stromal-tumour interactions and inhibit disease progression. The next important challenge is for the translation of such pre-clinical strategies to the clinical situation so as to improve the outcome of patients with pancreatic cancer.

Gut microbiota controls the development of chronic pancreatitis: A critical role of short-chain fatty acids-producing Gram-positive bacteria.

Chronic pancreatitis (CP) is a progressive and irreversible fibroinflammatory disorder, accompanied by pancreatic exocrine insufficiency and dysregulated gut microbiota. Recently, accumulating evidence has supported a correlation between gut dysbiosis and CP development. However, whether gut microbiota dysbiosis contributes to CP pathogenesis remains unclear. Herein, an experimental CP was induced by repeated high-dose caerulein injections. The broad-spectrum antibiotics (ABX) and ABX targeting Gram-positive (G+) or Gram-negative bacteria (G-) were applied to explore the specific roles of these bacteria. Gut dysbiosis was observed in both mice and in CP patients, which was accompanied by a sharply reduced abundance for short-chain fatty acids (SCFAs)-producers, especially G+ bacteria. Broad-spectrum ABX exacerbated the severity of CP, as evidenced by aggravated pancreatic fibrosis and gut dysbiosis, especially the depletion of SCFAs-producing G+ bacteria. Additionally, depletion of SCFAs-producing G+ bacteria rather than G- bacteria intensified CP progression independent of TLR4, which was attenuated by supplementation with exogenous SCFAs. Finally, SCFAs modulated pancreatic fibrosis through inhibition of macrophage infiltration and M2 phenotype switching. The study supports a critical role for SCFAs-producing G+ bacteria in CP. Therefore, modulation of dietary-derived SCFAs or G+ SCFAs-producing bacteria may be considered a novel interventive approach for the management of CP.