Distinct toll-like receptor signaling in the salamander response to tissue damage.

Document Type

Article

Publication Date

6-1-2022

Publication Title

Developmental dynamics : an official publication of the American Association of Anatomists

Keywords

JMG, Animals, Inflammation, Ligands, Mammals, Mice, Pathogen-Associated Molecular Pattern Molecules, Signal Transduction, Toll-Like Receptors, Urodela

JAX Source

Dev Dyn 2022 Jun; 251(6):988-1003

Volume

251

Issue

6

First Page

988

Last Page

1003

ISSN

1097-0177

PMID

33797128

DOI

https://doi.org/10.1002/dvdy.340

Grant

GM103423, GM104318

Abstract

BACKGROUND: Efficient wound healing or pathogen clearance both rely on balanced inflammatory responses. Inflammation is essential for effective innate immune-cell recruitment; however, excessive inflammation will result in local tissue destruction, pathogen egress, and ineffective pathogen clearance. Sterile and nonsterile inflammation operate with competing functional priorities but share common receptors and overlapping signal transduction pathways. In regenerative organisms such as the salamander, whole limbs can be replaced after amputation while exposed to a nonsterile environment. In mammals, exposure to sterile-injury Damage Associated Molecular Patterns (DAMPS) alters innate immune-cell responsiveness to secondary Pathogen Associated Molecular Pattern (PAMP) exposure.

RESULTS: Using new phospho-flow cytometry techniques to measure signaling in individual cell subsets we compared mouse to salamander inflammation. These studies demonstrated evolutionarily conserved responses to PAMP ligands through toll-like receptors (TLRs) but identified key differences in response to DAMP ligands. Co-exposure of macrophages to DAMPs/PAMPs suppressed MAPK signaling in mammals, but not salamanders, which activate sustained MAPK stimulation in the presence of endogenous DAMPS.

CONCLUSIONS: These results reveal an alternative signal transduction network compatible with regeneration that may ultimately lead to the promotion of enhanced tissue repair in mammals.

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