Inflammation of Mesenteric Adipose Tissue Correlates with Intestinal Injury and Disease Severity in Rats with Severe Acute Pancreatitis

Background: Visceral adipose tissue (VAT) is related to SAP prognosis. As a depot of VAT, mesenteric adipose tissue (MAT) resides between pancreas and gut, which might affect SAP and the secondary intestinal injury.

Aims: To investigate the changes of MAT in SAP.

Methods: 24 SD rats were randomly divided into four groups. 18 rats in SAP group were euthanized in time gradients (6 h, 24 h, and 48 h after modeling) and the others in control group. Blood samples and tissues of pancreas, gut, and MAT were taken for analysis.

Results: Compared to the control group, SAP rats appeared MAT inflammation, presenting higher mRNA expression of TNF-α and IL-6 and lower IL-10, and histological changes after 6 h of modeling, which became worse over time. Flow cytometry showed that B lymphocytes increased in MAT after 24 h of SAP modeling and lasted up to 48 h, earlier than the changes of T lymphocytes and macrophages. The intestinal barrier integrity was damaged after 6 h of modeling, presenting lower mRNA and protein expression of ZO-1 and occludin, higher serum levels of LPS and DAO, with pathological changes, which gradually aggravated after 24 h and 48 h. SAP rats had higher serum levels of inflammatory indicators and revealed histological inflammation of pancreas, the severity of which increased with the passage of modeling time.

Conclusion: MAT appeared inflammation in early-stage SAP, and became worse over time, with the same trend as the intestinal barrier injury and the severity of pancreatitis. B lymphocytes infiltrated early in MAT, which might promote the MAT inflammation.