The role of complement inhibitors beyond controlling inflammation

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• The complement system, a key part of innate immunity, is tightly regulated by inhibitors to prevent self-damage.
• Recent discoveries have expanded the known family of complement regulators, revealing novel physiological functions.
• These regulators play roles in pathogen clearance, cell homeostasis, and disease processes like cancer.

Purpose of the Study:

• To review the current understanding of the physiological functions of four complement regulators: COMP, CSMD1, SUSD4, and CD59.
• To explore the dual roles of these regulators in cancer development and other cellular processes.
• To highlight the emerging importance of intracellular functions of complement proteins.

Main Methods:

• Literature review of existing research on complement system regulators.
• Analysis of studies investigating the roles of COMP, CSMD1, SUSD4, and CD59 in various biological contexts.
• Synthesis of findings related to complement activation, cancer biology, and intracellular signaling.

Main Results:

• COMP exhibits pro-oncogenic activity, while CSMD1 and SUSD4 function as tumor suppressors.
• CD59 deficiency causes hemolytic anemia, treatable with C5 inhibitors.
• Intracellular COMP protects cells from endoplasmic reticulum stress; intracellular CD59 is vital for insulin secretion.

Conclusions:

• Complement regulators possess diverse functions extending beyond immune modulation, including roles in cancer and cellular stress responses.
• The intracellular localization and functions of complement proteins are increasingly recognized as critical.
• Understanding these alternative functions is crucial for developing targeted complement-based therapies.