High fish oil diet promotes liver inflammation and activates the complement system

Area of Science:

• Immunology
• Nutrition Science
• Gastroenterology

Background:

• Diets rich in n-3 polyunsaturated fatty acids (n-3 PUFA) from fish oil (FO) show benefits in metabolic diseases but have conflicting roles in inflammatory conditions.
• Previous research indicated high FO diets promote myeloid cell differentiation, but effects on liver inflammation and complement activation were unknown.

Purpose of the Study:

• To investigate the impact of a high FO diet on liver inflammation and complement system activation in mice.
• To analyze the cellular and molecular changes in the liver following high FO diet consumption.

Main Methods:

• Mice were fed high FO and low-fat diets for 4 weeks.
• Techniques included ELISA, quantitative PCR, flow cytometry, and histology.
• Complement activity (CH50), complement protein levels, and immune cell infiltration were assessed.

Main Results:

• High FO diet induced liver inflammation without altering body or liver weight.
• Increased infiltration of T cells and myeloid cells (CD11b+ Gr-1+) was observed in the livers.
• Elevated levels of IL-1β and MCP-1 mRNA, complement activity (CH50), membrane attack complex, and complement proteins (C3, C4b, C1qb, factor B) were detected.
• Higher triglyceride levels in peripheral blood suggested potential lipotoxicity protection.

Conclusions:

• High FO intake activates the liver's complement system and promotes inflammation.
• Further research is needed to elucidate the precise mechanisms underlying these effects.