Paneth cell

Overview

Diagram of intestinal immunology, highlighting Paneth cells.

Paneth cells are specialized cells located in the small intestine, particularly in the crypts of Lieberkühn. They play a crucial role in maintaining intestinal homeostasis and host defense. Paneth cells are one of the four principal cell types found in the epithelium of the small intestine, alongside enterocytes, goblet cells, and enteroendocrine cells.

Structure

Paneth cells are characterized by their location at the base of the intestinal crypts and their distinctive granules. These granules contain antimicrobial peptides and proteins, such as lysozyme, defensins, and phospholipase A2. The presence of these granules is a key feature that distinguishes Paneth cells from other intestinal epithelial cells.

Function

Paneth cells contribute to the innate immune system of the gut by secreting antimicrobial compounds that help control the microbial population in the intestine. This secretion is crucial for protecting the intestinal epithelium from pathogenic bacteria and maintaining a balanced gut microbiota.

Antimicrobial Peptides

The antimicrobial peptides secreted by Paneth cells include:

• Alpha-defensins: These peptides disrupt the membrane integrity of bacteria, leading to their death.
• Lysozyme: An enzyme that breaks down bacterial cell walls.
• Secretory phospholipase A2: An enzyme that hydrolyzes phospholipids in bacterial membranes.

Role in Intestinal Homeostasis

Paneth cells also play a role in regulating the stem cell niche in the intestinal crypts. They provide essential signals that support the proliferation and differentiation of intestinal stem cells.

Clinical Significance

Dysfunction or loss of Paneth cells has been associated with various intestinal disorders, including Crohn's disease and necrotizing enterocolitis. In these conditions, the impaired antimicrobial function of Paneth cells can lead to an imbalance in the gut microbiota and increased susceptibility to infection.

Related pages

• Intestinal epithelium
• Gut microbiota
• Crypts of Lieberkühn
• Innate immune system