The Essential Involvement of the Omentum in the Peritoneal Defensive Mechanisms During Intra-Abdominal Sepsis

Abstract

Although the abilities of the omentum to alleviate inflammation and prevent infection have been revealed over the past decades, the underlying mechanisms remain largely unelucidated. Here, we demonstrated that the mortality of mice exposed to cecal ligation and puncture (CLP) and omentectomy was remarkably increased compared to those treated with CLP alone. Moreover, the efficacy of the omentum was associated with an impairment in intraperitoneal bacterial clearance together with an increase in the expression of proinflammatory cytokines. Besides, in response to peritoneal infections, the size and quantity of the omental milky spots (MSs) were increased tremendously and they also support innate-like B1 cell responses and local IgM production in the peritoneal cavity. Furthermore, not only the migration but also the functional activities of neutrophils were diminished in the absence of the omentum. These data collectively show that the omentum contributes more to peritoneal immune responses during septic peritonitis than has heretofore been recognized. Thus, harnessing the function of MS-containing omentum to increase its protective effectiveness may exert important biological and therapeutic implications for the control of intra-abdominal infections.

Improvement of the sepsis survival rate by adenosine 2a receptor antagonists depends on immune regulatory functions of regulatory T-cells

“…The CLP mouse model was prepared as previously described ( 21 ). Mice were rendered unconscious using a gas anesthetic equipment and isoflurane.…”

“…As previously described, peritoneal cells were collected from PLF ( 21 ). To keep peritoneal cells active, ice-cold PBS is installed into the peritoneal cavity instead of sterile physiological saline.…”

“…As previously described, a modified procedure was used to measure the generation of reactive oxygen species (ROS) using flow cytometry ( 21 ). Briefly, at 24 hours post-CLP, peritoneal cells were collected.…”

The α7 Nicotinic Acetylcholine Receptor Agonist GTS-21 Improves Bacterial Clearance via Regulation of Monocyte Recruitment and Activity in Polymicrobial Septic Peritonitis

“…Septic peritonitis was induced by CLP as described previously (18,19). In brief, mice were anesthetized with isoflurane inhalation.…”

GPR183 Is Dispensable for B1 Cell Accumulation and Function, but Affects B2 Cell Abundance, in the Omentum and Peritoneal Cavity

“…The omentum is an immunologically active organ, which, e.g., supports T-dependent antibody responses [15,16]. Furthermore, it was recently shown that the organ plays a major role in the protection against cecal ligation and puncture-induced sepsis [17].…”