Intestinal smooth muscle dysfunction develops postnatally in cystic fibrosis mice

Area of Science:

• Gastroenterology
• Developmental Biology
• Genetics

Background:

• Intestinal dysmotility is a known complication of cystic fibrosis (CF).
• The precise developmental timing and mechanisms of CF-related intestinal smooth muscle dysfunction remain unclear.
• Understanding these factors is crucial for managing CF gastrointestinal complications.

Purpose of the Study:

• To determine the developmental onset of circular smooth muscle dysfunction in the small intestine of CF mice.
• To investigate the role of CFTR in the development of intestinal smooth muscle dysfunction.

Main Methods:

• Utilized wild-type (WT) and CFTR knockout (CF) mice from postnatal day 5 (P5) to adulthood.
• Assessed circular smooth muscle contractile activity in response to cholinergic stimulation.
• Quantified bacterial overgrowth using 16S rRNA gene quantitative PCR (qPCR).
• Analyzed intestinal gene expression via RT-qPCR and measured prostaglandin E2 (PGE2) levels using enzyme immunoassay.

Main Results:

• CF circular smooth muscle function was normal at P5 but impaired by P7 and severely dysfunctional by P14.
• Bacterial overgrowth was evident in CF intestines by P4 and persisted into adulthood.
• Increased expression of phospholipase A2 genes (Pla2g4c, Pla2g5) and elevated PGE2 levels were observed in CF mice from P7 onwards.
• Decreased expression of prostaglandin degradative genes (Hpgd, Ptgr1) was noted in CF mice at later time points.

Conclusions:

• CFTR absence itself does not directly cause smooth muscle dysfunction.
• Intestinal smooth muscle dysfunction in CF develops postnatally between P7 and P14.
• Bacterial overgrowth and altered eicosanoid metabolism likely contribute to the observed dysmotility.