DAMPs, PAMPs and alarmins: all we need to know about danger

Multicellular animals detect pathogens
via a set of receptors that recognize pathogen associated
molecular patterns (PAMPs). However,
pathogens are not the only causative agents of tissue
and cell damage: trauma is another one. Evidence
is accumulating that trauma and its associated
tissue damage are recognized at the cell level
via receptor-mediated detection of intracellular
proteins released by the dead cells. The term
“alarmin” is proposed to categorize such endogenous
molecules that signal tissue and cell damage.
Intriguingly, effector cells of innate and adaptive
immunity can secrete alarmins via nonclassical
pathways and often do so when they are activated
by PAMPs or other alarmins. Endogenous alarmins
and exogenous PAMPs therefore convey a similar
message and elicit similar responses; they can be
considered subgroups of a larger set, the damage associated
molecular patterns (DAMPs).