A 50-year-old woman has colicky right upper quadrant pain for 5 days. She has nausea, but no vomiting or diarrhea. She is afebrile. There is marked tenderness of the right upper quadrant. The liver span is normal. An abdominal ultrasound shows calculi within the lumen of the gallbladder, and the gallbladder wall appears thickened. Intrahepatic and extrahepatic bile ducts appear normal. Which of the following mechanisms is most likely to play the greatest role in development of this disease?