Significance of Eosinophils in Promoting Pancreatic malignancy

Several reports indicate that eosinophils are induced in chronic pancreatitis including patients with pancreatic malignancy. However, significance of eosinophilic pancreatitis (EP) is poorly understood and unexplored.

Accumulation and degranulation of eosinophils promote pancreatic fibrosis and malignancy.

Human pancreatic tissue biopsy samples including chronic pancreatitis (n=3), malignant (n=4), non-malignant (n=3), and normal (n=3) were used for H&E, anti-MBP staining, anti-tryptase staining, anti-IgE staining and Mason's trichrome staining.

We show induced eosinophils and degranulated eosinophils indicated by the presence of anti-MBP stained extracellular granules in the malignant pancreatic (pancreatic cancer) and non-malignant human pancreatic tissues. A comparable number of eosinophils were observed in non-malignant and malignant pancreatic tissue sections, but the sections differed in degranulated eosinophils and the presence of extracellular granules. Additionally, induced mast cells and tissue-specific IgE positive cells were also detected in the tissue sections of malignant pancreatitis patients compared to non-malignant human pancreatic patients. Tissue-specific IgE induction is critical for the degranulation of eosinophils and mast cells that may lead to increased accumulation of collagen in malignant compared to non-malignant human pancreatic tissue samples. We show a large number of anti-tryptase stained extracellular granules in the tissue sections of malignant pancreatic cancer patients. Both IgE and eosinophil major basic proteins (MBP) are reported for the activation and degranulation of mast cells in tissues.

Taken together, our investigation concludes that eosinophils and mast cells accumulation and degranulation are critical in promoting pancreatitis pathogenesis that may lead to the development of pancreatic fibrosis and malignancy.