A Novel Scavenging Peptide, MOP3, Attenuates Inflammation in Sepsis
Author(s):
Colleen Nofi; Monowar Aziz; Gaifeng Ma; Ping Wang
Background:
Sepsis is characterized by a dysregulated host immune response to infection. Milk fat globule-EGF factor VIII (MFG-E8) is an opsonin that promotes the clearance of apoptotic cells by macrophages to control hyperinflammation in sepsis. By contrast, extracellular cold-inducible RNA-binding protein (eCIRP), a novel alarmin, is elevated in serum and exaggerates inflammation in sepsis. Given the scavenging function of MFG-E8 and the lack of effective therapeutics in sepsis, this study aimed to determine the therapeutic potential of a novel, MFG-E8-derived oligopeptide 3 (MOP3) designed to bind and link eCIRP to the integrin receptor for clearance.
Hypothesis:
We hypothesize that through clearance of eCIRP, MOP3 protects against inflammation in sepsis.
Methods:
MOP3 was designed by screening for effective 15-amino acid (AA) long sequences from MFG-E8’s interaction site with eCIRP. These AAs were tagged with three additional AAs, “RGD”, known to interact with the integrin receptor and promote phagocytosis. Binding of MOP3 to recombinant murine (rm) CIRP and to the αvβ3-integrin receptor was quantified by Biacore analysis. Sepsis was induced in wild type mice through cecal ligation and puncture (CLP). Mice were treated with either MOP3 (10 μg/g BW) or vehicle through retro-orbital injection. After 20 hours, serum was collected and analyzed for inflammatory parameters by ELISA and calorimetric assays.
Results:
MOP3 demonstrated strong binding to rmCIRP and to the αvβ3-integrin receptor, with a KD 1.3 x10-8 M and a KD of 7.76 x 10-7 M, respectively. MOP3 treatment protected septic mice from systemic inflammation by significantly reducing serum IL-6 by 72% and TNF-α by 58%. MOP3 treatment also significantly reduced markers of tissue injury, including LDH by 54%, AST by 30%, and ALT by 22%. (Table)
| Sham | CLP+Vehicle | CLP+MOP3 | |
| Serum IL-6 (pg/mL) | 10.8 ± 6.7 | 2435 ± 596.6* | 688.3 ± 327# |
| Serum TNF-α (pg/mL) | 2.3 ± 0.8 | 42.6 ± 12.8* | 17.7 ± 4.7# |
| Serum LDH (IU/L) | 38.2 ± 5.7 | 322.7 ± 49.8* | 147.9 ± 30.9# |
| Serum AST (IU/L) | 35.9 ± 4.7 | 97.5 ± 8.3* | 68.2 ± 3.7*# |
| Serum ALT (IU/L) | 28.8 ± 3.3 | 54.7 ± 2.2* | 42.6 ± 2.5*# |
*p<0.05 vs. Sham, #p<0.05 vs. CLP+Vehicle by one-way ANOVA and SNK method, N=8-12 mice per group.
Conclusions:
By clearing eCIRP from circulation, MOP3 protects against systemic inflammation and tissue injury in sepsis. Given the advantages of synthetic peptides as therapeutics, MOP3 provides an exciting new treatment to attenuate inflammation and improve outcomes in sepsis.