NCF4 dependent intracellular reactive oxygen species regulate plasma cell formation

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Genetic variants in NCF4, a component of NADPH oxidase 2 (NOX2), are linked to defective reactive oxygen species (ROS) production.
• Previous studies indicate a connection between impaired ROS production and increased autoantibody generation, specifically against collagen type II (COL2), leading to severe collagen-induced arthritis (CIA) in mice.

Purpose of the Study:

• To investigate the role of NCF4's intracellular ROS production in B cell function and autoimmune responses.
• To elucidate the specific mechanisms by which NCF4 mutations influence B cell differentiation and antibody production in the context of collagen-induced arthritis.

Main Methods:

• Utilized mice with a specific mutation (R58A) in the NCF4 subunit, affecting its lipid endosomal membrane binding.
• Assessed extracellular and intracellular ROS responses in B cells upon stimulation.
• Induced collagen-induced arthritis (CIA) via COL2 immunization and analyzed immune responses, including antibody levels, T cell activation, germinal center formation, and plasma cell differentiation.
• Employed chimeric B cell transfer experiments and in vitro cell culture models (LPS, CD40L, anti-IgM stimulation) to confirm B cell-intrinsic effects.

Main Results:

• The NCF4 R58A mutation impaired intracellular ROS production but not extracellular ROS responses.
• Mice with the NCF4 mutation developed severe CIA with elevated anti-COL2 antibody levels.
• Antigen presentation, autoreactive T cell activation, and germinal center formation remained unaffected.
• Plasma cell formation was significantly enhanced in mutated animals, with altered CXCR3/CXCR4 expression patterns.
• B cell transfer and in vitro experiments confirmed the B cell-intrinsic nature of enhanced plasma cell differentiation.

Conclusions:

• NCF4 plays a critical role in regulating the terminal differentiation of B cells into plasma cells via intracellular ROS production.
• Impaired intracellular ROS signaling due to NCF4 defects promotes enhanced autoantibody production and exacerbates autoimmune arthritis.