Pathogenesis of small-intestinal mucosal lesions in chronic diarrhea of infancy: II. An electron microscopic study

Area of Science:

• Gastroenterology
• Pediatric Pathology
• Microbiology

Background:

• Protracted diarrhea in infants is a significant clinical challenge.
• The precise pathogenesis of this condition, particularly the role of bacterial interactions with the intestinal lining, remains incompletely understood.
• Electron microscopy offers a detailed view of cellular structures crucial for understanding mucosal damage.

Purpose of the Study:

• To investigate the ultrastructural changes in the jejunal mucosa of infants with protracted diarrhea.
• To correlate these ultrastructural findings with the presence of unidentified bacteria, both adherent and non-adherent.
• To identify novel cytopathic changes contributing to the
• sick mucosa
• syndrome.

Main Methods:

• Electron microscopy was used to examine jejunal biopsies from 10 infants with protracted diarrhea.
• Detailed ultrastructural analysis of enterocytes, intraepithelial lymphocytes, and lamina propria components was performed.
• The relationship between bacterial presence and observed mucosal pathology was assessed.

Main Results:

• Beyond known cupping and effacement, widespread enterocyte loss, including intraepithelial lymphocytes, into the lumen was observed.
• Cytopathological alterations within enterocytes and significant thickening of basal laminae were documented.
• Collagen deposition in the lamina propria, active phagolysis in macrophages, and reduced immunoglobulin in plasma cells were noted.

Conclusions:

• The study identified previously unreported cytopathic changes in the jejunal mucosa of infants with protracted diarrhea.
• These ultrastructural alterations, including basal lamina thickening and collagen deposition, may be linked to bacterial presence.
• Further identification of bacteria is needed to fully elucidate their role in the pathogenesis of the "sick mucosa" in infant chronic diarrhea.