A 52-year-old man presents with progressive fatigue, arthralgia of the 2nd and 3rd metacarpophalangeal joints, and hepatomegaly. Laboratory studies show transferrin saturation 58%, serum ferritin 1200 ng/mL, and low TIBC. Liver biopsy with Prussian blue staining reveals the pattern shown in the diagram. The iron granules marked **A** are predominantly localized to hepatocytes in a periportal distribution, with sparing of Kupffer cells. HFE genetic testing confirms C282Y homozygosity. Which of the following best explains the pathophysiology of iron deposition in this patient's liver?