Related Experiment Video
Updated: Feb 10, 2026
Subcellular Fractionation for ERK Activation Upon Mitochondrial-derived Peptide Treatment
Published on: September 25, 2017
A subset of five human mitochondrial formyl peptides mimics bacterial peptides and functionally deactivates human
Elzbieta Kaczmarek1, Carl J Hauser, Woon Yong Kwon
1From the Department of Surgery and Center for Vascular Biology Research (E.K.), Department of Surgery (C.J.H., L.C., N.S., L.E.O., C.H.C., K.I.), Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts; Department of Emergency Medicine (W.Y.K.), Seoul National University College of Medicine, Seoul, Republic of Korea; Massachusetts Institute of Technology (I.R., M.B.Y.), Cambridge, Massachusetts; and mAbDx, Inc (Y.C., M.M.), Eugene, Oregon.
Background:
Trauma causes inflammation by releasing mitochondria that act as Danger-Associated Molecular Patterns (DAMPs). Trauma also increases susceptibility to infection. Human mitochondria contain 13 N-formyl peptides (mtFPs). We studied whether mtFPs released into plasma by clinical injury induce neutrophil (PMN) inflammatory responses, whether their potency reflects their similarity to bacterial FPs and how their presence at clinically relevant concentration affects PMN function.
Methods:
N-terminal sequences of the 13 mtFPs were synthesized. Changes in human PMN cytosolic Ca concentration ([Ca]i) and chemotactic responses to mtFPs were studied. Sequence similarity of mtFPs to the canonical bacterial peptide f-Met-Leu-Phe (fMLF/fMLP) was studied using the BLOcks SUbstitution Matrix 62 (BLOSUM 62) system. The presence of mtFPs in plasma of trauma patients was assayed by Enzyme-linked immunosorbent assay (ELISA). The effects of the most potent mtFP (ND6) on PMN signaling and function were then studied at ambient clinical concentrations by serial exposure of native PMN to ND6, chemokines and leukotrienes.
Results:
Five mtFPs (ND6, ND3, ND4, ND5, and Cox 1) induced [Ca]i flux and chemotaxis in descending order of potency. Evolutionary similarity to fMLF predicted [Ca]i flux and chemotactic potency linearly (R = 0.97, R = 0.95). Chemoattractant potency was also linearly related to [Ca]i flux induction (R = 0.92). Active mtFPs appear to circulate in significant amounts immediately after trauma and persist through the first week. The most active mtFP, ND6, suppresses responses to physiologic alveolar chemoattractants (CXCL-1, leukotriene B4) as well as to fMLF where CXCL-1 and leukotriene B4 do not suppress N-formyl peptide receptor (FPR)-1 responses to mtFPs. Prior FPR-1 inhibition rescues PMN from heterologous suppression of CXCR-1 and BLT-1 by mtFPs.
Conclusion:
The data suggest mtFPs released by injured tissue may attract PMN to trauma sites while suppressing PMN responses to other chemoattractants. Inhibition of mtFP-FPR1 interactions might increase PMN recruitment to lung bacterial inoculation after trauma. These findings suggest new paradigms for preventing infections after trauma.
Level Of Evidence:
Therapeutic, Level IV.
Insights
Mitochondrial peptides (mtFPs) released after trauma attract neutrophils but suppress their response to other signals. Inhibiting mtFP-receptor interactions may prevent infections following injury.
Area of Science:
- Immunology
- Molecular Biology
- Trauma Research
Background:
- Trauma induces inflammation via mitochondria-released Danger-Associated Molecular Patterns (DAMPs).
- Mitochondria-derived peptides (mtFPs) are implicated in trauma-induced inflammation and infection susceptibility.
- Human mitochondria contain 13 distinct mtFPs with potential roles in immune responses.
Purpose of the Study:
- To investigate if mtFPs released by clinical injury trigger neutrophil (PMN) inflammatory responses.
- To determine if mtFP potency correlates with similarity to bacterial peptides.
- To assess the impact of clinically relevant mtFP concentrations on PMN function.
Main Methods:
- Synthesized N-terminal sequences of 13 human mtFPs.
- Measured human PMN cytosolic Ca2+ flux and chemotaxis in response to mtFPs.
- Assessed mtFP similarity to bacterial peptide fMLF using BLOSUM 62.
- Quantified mtFP levels in trauma patient plasma via ELISA.
- Studied the effects of the potent mtFP ND6 on PMN signaling and function.
Main Results:
- Five mtFPs, notably ND6, induced significant Ca2+ flux and chemotaxis in human PMNs.
- Evolutionary similarity to fMLF strongly predicted mtFP chemoattractant potency and Ca2+ flux induction.
- Active mtFPs circulate at clinically relevant levels post-trauma, persisting for at least a week.
- The potent mtFP ND6 suppressed PMN responses to chemoattractants like CXCL-1 and leukotriene B4, but not vice-versa.
- Inhibition of the N-formyl peptide receptor (FPR) 1 rescued PMN function from mtFP-induced suppression.
Conclusions:
- Trauma-released mtFPs may recruit PMNs to injury sites while simultaneously dampening responses to other chemoattractants.
- mtFP-FPR1 interaction inhibition could enhance PMN recruitment to bacterial infections post-trauma.
- These findings offer novel strategies for preventing infections in trauma patients.
More Related Videos
Related Concept Videos
02:43Peptide Bonds
01:33Peptide Identification Using Tandem Mass Spectrometry
This technique helps gather information regarding the protein from which the peptide was obtained and to study the peptides’ amino acid sequence. Identifying peptides from a complex mixture is an important component of the growing field of...
01:25Compounds Essential to Human Function
Inorganic Compounds Essential to Human Functioning
Inorganic compounds essential to human functioning include water, salts, acids, and bases. These compounds are inorganic, i.e., they do not have a carbon-hydrogen bond. Water...
02:16Comparing Mitochondrial, Chloroplast, and Prokaryotic Genomes
01:30Bacterial Signaling
02:59Animal Mitochondrial Genetics