Digital PCR-based detection of Cryptosporidium in Pancreatic Tissue and Saliva Samples of Cancer patients; Pancreatic cryptosporidiosis

Abstract

Introduction

Cryptosporidium spp. is a protozoan parasite known to cause gastrointestinal infections, particularly in immunocompromised individuals such as cancer patients. It typically infects the small intestine but has been reported in extraintestinal sites, including the biliary tract, and lungs. While Cryptosporidium has been implicated in the pathogenesis of several gastrointestinal cancers, there is very limited data its association with pancreatic ductal adenocarcinoma (PDAC). This study aimed to investigate the presence of Cryptosporidium in pancreatic tissue and saliva samples from PDAC patients using digital PCR (dPCR), a highly sensitive diagnostic tool, and to compare findings with those in distal cholangiocarcinoma (DCC) patients and healthy controls.

Methods

A total of 50 participants were enrolled, including 20 PDAC patients, 10 DCC patients, and 20 healthy controls. Pancreatic tissue and saliva samples were collected from PDAC and DCC patients, while only saliva was collected from healthy controls. DNA was extracted from all samples, and the presence of Cryptosporidium was investigated using both quantitative PCR (qPCR) and dPCR. Cancer patients were also analyzed for clinical findings and patients positive for Cryptosporidium spp. in saliva and tissue samples were evaluated clinically.

Results

Cryptosporidium DNA was detected by qPCR in the saliva of one DCC patient. In contrast, dPCR revealed Cryptosporidium spp. in the saliva of one PDAC and two DCC patients (one overlapping with qPCR), and in the pancreatic tissue of two PDAC patients (whose saliva was negative). No Cryptosporidium spp. was detected in the healthy control group. Although the differences between groups were not statistically significant, the presence of Cryptosporidium in pancreatic tissue was demonstrated for the first time using dPCR. Some positive patients showed respiratory symptoms or were asymptomatic, raising the possibility of subclinical or extraintestinal infection.

Conclusion

This study provides the first dPCR-based evidence of Cryptosporidium in pancreatic tissue, suggesting its potential for extraintestinal dissemination in cancer patients. The findings highlight the superiority of dPCR over qPCR for detecting low-abundance pathogens in clinical samples. Although no direct causal link with PDAC was established, the detection of Cryptosporidium in pancreatic tissues warrants further investigation into its potential role in pancreatic carcinogenesis.