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Role of MBL-associated serine protease (MASP) on activation of the lectin complement pathway

Minoru Takahashi1, Shuichi Mori, Shiro Shigeta

  • 1Department of Immunology, Fukushima Medical University School of Medicine, Japan. minolta@fmu.ac.jp

Advances in Experimental Medicine and Biology
|September 26, 2007
PubMed

Insights

Mannose-binding lectin-associated serine proteases (MASPs) are crucial for complement activation. Mice lacking MASP-1/3 show impaired lectin pathway function and increased susceptibility to influenza virus.

Area of Science:

  • Immunology
  • Molecular Biology
  • Biochemistry

Background:

  • Mannose-binding lectin (MBL) and ficolins are pattern recognition molecules that initiate the lectin complement pathway.
  • MBL-associated serine proteases (MASPs), including MASP-1, MASP-2, and MASP-3, are essential components of this pathway.
  • MASP-2 cleaves C4 and C2, forming the C3 convertase, while MASP-1 can directly cleave C3 under certain conditions, and MASP-3's targets are still under investigation.

Purpose of the Study:

  • To investigate the physiological roles of MASPs in complement activation and host defense.
  • To elucidate the specific contributions of MASP-1, MASP-2, and MASP-3 to the lectin pathway.
  • To assess the impact of MASP deficiency on susceptibility to microbial infections, specifically influenza virus.

Main Methods:

  • Generation of MASP-deficient mouse models (MASP-2 deficient and MASP-1/MASP-3 deficient).
  • Assessment of complement activation by measuring C3 deposition on microbial surfaces (mannan and zymosan).
  • Evaluation of host defense against influenza virus in MASP-deficient mice.

Main Results:

  • Both MASP-2-deficient and MASP-1/MASP-3-deficient mice exhibited reduced C3 deposition on mannan and zymosan, indicating impaired lectin pathway activation.
  • MASP-1/MASP-3 deficiency led to increased susceptibility to influenza virus infection.
  • These findings suggest that MASP-1 and MASP-3 play significant roles in lectin pathway-mediated complement activation and antiviral defense.

Conclusions:

  • MASP-1 and MASP-3 are critical for efficient complement activation via the lectin pathway.
  • MASP-1/MASP-3 deficiency compromises host defense against influenza virus.
  • The study highlights the multifaceted roles of MASPs in innate immunity.

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