Go to JCI Insight
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Publication ethics
  • Publication alerts by email
  • Advertising
  • Job board
  • Contact
  • Clinical Research and Public Health
  • Current issue
  • Past issues
  • By specialty
    • COVID-19
    • Cardiology
    • Gastroenterology
    • Immunology
    • Metabolism
    • Nephrology
    • Neuroscience
    • Oncology
    • Pulmonology
    • Vascular biology
    • All ...
  • Videos
    • Conversations with Giants in Medicine
    • Video Abstracts
  • Reviews
    • View all reviews ...
    • Clinical innovation and scientific progress in GLP-1 medicine (Nov 2025)
    • Pancreatic Cancer (Jul 2025)
    • Complement Biology and Therapeutics (May 2025)
    • Evolving insights into MASLD and MASH pathogenesis and treatment (Apr 2025)
    • Microbiome in Health and Disease (Feb 2025)
    • Substance Use Disorders (Oct 2024)
    • Clonal Hematopoiesis (Oct 2024)
    • View all review series ...
  • Viewpoint
  • Collections
    • In-Press Preview
    • Clinical Research and Public Health
    • Research Letters
    • Letters to the Editor
    • Editorials
    • Commentaries
    • Editor's notes
    • Reviews
    • Viewpoints
    • 100th anniversary
    • Top read articles

  • Current issue
  • Past issues
  • Specialties
  • Reviews
  • Review series
  • Conversations with Giants in Medicine
  • Video Abstracts
  • In-Press Preview
  • Clinical Research and Public Health
  • Research Letters
  • Letters to the Editor
  • Editorials
  • Commentaries
  • Editor's notes
  • Reviews
  • Viewpoints
  • 100th anniversary
  • Top read articles
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Publication ethics
  • Publication alerts by email
  • Advertising
  • Job board
  • Contact
Complement as a multifaceted modulator of kidney transplant injury
Paolo Cravedi, Peter S. Heeger
Paolo Cravedi, Peter S. Heeger
View: Text | PDF | Corrigendum
Review Series

Complement as a multifaceted modulator of kidney transplant injury

  • Text
  • PDF
Abstract

Improvements in clinical care and immunosuppressive medications have positively affected outcomes following kidney transplantation, but graft survival remains suboptimal, with half-lives of approximately 11 years. Late graft loss results from a confluence of processes initiated by ischemia-reperfusion injury and compounded by effector mechanisms of uncontrolled alloreactive T cells and anti-HLA antibodies. When combined with immunosuppressant toxicity, post-transplant diabetes and hypertension, and recurrent disease, among other factors, the result is interstitial fibrosis, tubular atrophy, and graft failure. Emerging evidence over the last decade unexpectedly identified the complement cascade as a common thread in this process. Complement activation and function affects allograft injury at essentially every step. These fundamental new insights, summarized herein, provide the foundation for testing the efficacy of various complement antagonists to improve kidney transplant function and long-term graft survival.

Authors

Paolo Cravedi, Peter S. Heeger

×

Figure 1

Schematic representation of the complement cascade.

Options: View larger image (or click on image) Download as PowerPoint
Schematic representation of the complement cascade.
C1q,r,s cross-linkin...
C1q,r,s cross-linking of antibodies activates the classical pathway. Mannose-associated serine proteases (MASPs) bind to mannose motifs expressed on bacteria to activate complement via the MBL pathway. Subsequent cleavage and assembly of C4 and then C2 form the C4bC2b C3 convertase. C3 spontaneously binds to H2O, forming C3(H2O), which binds to cell surfaces and initiates factor B–dependent (fB-dependent) and fD-dependent assembly of the alternative pathway C3 convertase (C3bBb). The latter cleaves C3 into C3a and C3b, amplifying complement activation. Addition of a second C3b molecule to either C3 convertase forms the C5 convertase, which cleaves C5 into C5a and C5b. C5b, in conjunction with C6 to C9, comprises the MAC. C3b functions as an opsonin, whereas C3a and C5a have inflammatory and chemotactic properties. DAF (CD55) and MCP (CD46) are cell surface–expressed complement regulators that accelerate the decay of all surface-assembled C3 convertases, thereby limiting amplification of the downstream cascade. MCP and fH also have cofactor activity: in conjunction with soluble fI, they irreversibly cleave C3b to iC3b, thereby preventing re-formation of the C3 convertase. CD59 inhibits formation of the MAC.

Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)

Sign up for email alerts