Intraperitoneal Injection of Bacterial Lipopolysaccharide in Mice to Study Systemic Immune Responses

Abstract

Source: Radulovic, K., et al. Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach. J. Vis. Exp. (2018)

This video demonstrates a step-by-step procedure for injecting lipopolysaccharide (LPS) into mice intraperitoneally to induce systemic inflammation.

Protocol

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Intraperitoneal Injection of lipopolysaccharide (LPS) to Mice
   1. Aspirate the LPS working solution in a 0.5 mL syringe with a 30 G needle in a laminar air flow.
   2. Weigh female C57Bl/6 mice (six to 10 weeks of age) and calculate the amount of LPS that will be injected: 10 µL (2 µg)/g body weight.
      NOTE: For example, if a mouse weighs 20 g, then 20 g x 10 µL = 200 µL LPS working solution needs to be injected.
   3. Handle the mouse gently but firmly and restrain the animal in one hand. Ensure that the animal is able to breathe normally but not to twist and turn during the restraint.
   4. Tilt the mouse nose slightly towards the floor to expose the abdomen for injection. Locate the midline of the abdomen and the injection place in the low abdomen left or right from the midline. Inject intraperitoneally (i.p.) phosphate-buffered saline (PBS) instead of LPS into control mice.
   5. With the free hand, inject the appropriate volume (the volume calculated in step 1.2) of the LPS working solution. Make sure that the needle has entered the peritoneal cavity as otherwise, mis-injections into the abdominal muscle layer may occur. Still, do not go too deep with the needle into the peritoneal cavity to avoid injuring inner organs located in that area.
   6. Return the animal carefully to the cage with up to 5 mice per cage.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
LPS Escherichia coli O111:B4	Invivogen, San Diego, CA, USA.	tlrl-eblps
Omnican 50 Single-use insulin syringe	B. Braun Melsungen, Melsungen, Germany	9151125