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Updated: May 8, 2026
Murine Model of Epicutaneously-Induced Immunomodulation
Published on: June 24, 2025
Suppression of Th1 cytokine production by a peptide derived from C4b
Yuji Takeda1, Kenta Kaneda, Fumie Jimma
1Department of Environmental and Preventive Medicine, Hyogo College of Medicine, Mukogawa-cho 1-1, Nishinomiya, Hyogo, 663-8501, Japan.
Insights
A C4b-derived peptide, HP2, was identified as the active site inhibiting T-helper 1 (Th1) cytokine production. This discovery offers potential for developing new treatments for autoimmune diseases by modulating immune responses.
Area of Science:
- Immunology
- Complement System Biology
- T-cell Regulation
Background:
- The complement system plays a role in T-cell response regulation.
- The exact mechanism of C4b-induced immune tolerance is not fully understood.
- Monomeric C4b has been shown to inhibit CXCL10 production.
Purpose of the Study:
- To identify the active site of monomeric C4b responsible for immune modulation.
- To investigate the therapeutic potential of a C4b-derived peptide (HP2) in autoimmune conditions.
Main Methods:
- In vitro analysis of HP2's effect on CXCL10 production in human blood.
- In vivo study of HP2's impact on Th1/2 cytokine production in mouse spleens.
- Assessment of HP2's efficacy in an experimental mouse model of ulcerative colitis.
Main Results:
- HP2 effectively inhibited CXCL10 production in human blood.
- HP2 administration suppressed Th1 cytokines (IL-2, IFN-γ, TNF-α) in mice.
- HP2 treatment ameliorated colitis symptoms by modulating T-cell populations (down-regulating CD4(+)CD45RB(high) and up-regulating CD4(+)LAP/TGF-β1(+)).
Conclusions:
- The specific amino acid sequence in HP2 represents the active site of C4b for inhibiting Th1 cytokine production.
- These findings support the development of novel therapeutics targeting autoimmune responses.
Objectives:
The complement system has been proposed to play a significant role in the regulation of T-cell responses. However, the precise mechanism underlying C4-induced immune tolerance remains to be clarified. We recently reported that monomeric C4b inhibits CXCL10 production from blood cells. The purpose of this study was to verify the active site of monomeric C4b.
Materials And Methods:
We investigated the in vitro effects of a C4b-derived peptide (VPAGSARPVAFSVVPTAAA), named HP2 (highly homologous peptide 2), on the IFN-β-induced production of CXCL10 in human blood and the in vivo effects of the administration of HP2 on Th1/2 cytokine production in the spleen in mice. We also tested whether the administration of HP2 influences symptoms of experimentally induced ulcerative colitis in mice.
Results:
HP2 inhibited CXCL10 production in human blood, and the administration of HP2 significantly suppressed the production of Th1 cytokines, such as IL-2, IFN-γ, and TNF-α, in spleen cells isolated from mice. The administration of HP2 in the mice significantly improved the symptoms of colitis, with down-regulation of colitogenic CD4(+)CD45RB(high) T cells and up-regulation of CD4(+)LAP/TGF-β1(+) T cells.
Conclusion:
The amino acid sequence described above is suggested to be the active site in C4b for the inhibition of Th1 cytokine production. These results should contribute to the development of new drugs suppressing autoimmune responses.
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