Rationale:
While thrombin is the key protease in thrombus formation, other coagulation proteases, such as fXa or activated protein C (aPC), independently modulate intracellular signaling via partially distinct receptors.
Objective:
To study the differential effects of fXa or fIIa inhibition on gene expression and inflammation in myocardial ischemia-reperfusion injury (IRI).
Methods and Results:
Mice were treated with a direct fIIa inhibitor (fIIai) or direct fXa inhibitor (fXai) at doses that induced comparable anticoagulant effects ex vivo and in vivo (tail bleeding assay and FeCl3-induced thrombosis). Myocardial IRI was induced via LAD ligation. We determined infarct size and in vivo aPC generation, analyzed gene expression by RNAseq, and performed immunoblotting and ELISA. The signaling-only 3K3A-aPC variant and inhibitory antibodies that blocked all or only the anticoagulant function of aPC were used to determine the role of aPC. Doses of fIIai and fXai that induced comparable anticoagulant effects resulted in a comparable reduction in infarct size. However, unbiased gene expression analyses revealed marked differences, including pathways related to sterile inflammation and inflammasome regulation. fXai but not fIIai inhibited sterile inflammation by reducing the expression of proinflammatory cytokines (IL-1beta, IL-6, and TNFalpha) as well as NF-κB and inflammasome activation. This anti-inflammatory effect was associated with reduced myocardial fibrosis 28 days post myocardial IRI. Mechanistically, in vivo aPC generation was higher with fXai than with fIIai. Inhibition of the anticoagulant and signaling properties of aPC abolished the anti-inflammatory effect associated with fXai, while inhibiting only the anticoagulant function of aPC had no effect. Combining 3K3A-aPC with fIIai reduced the inflammatory response, mimicking the fXai-associated effect.
Conclusions:
We showed that specific inhibition of coagulation via DOACs had differential effects on gene expression and inflammation, despite comparable anticoagulant effects and infarct sizes. Targeting individual coagulation proteases induces specific cellular responses unrelated to their anticoagulant effect.
Differential effects of isoflurane on excitatory and inhibitory synaptic inputs to thalamic neurones in vivo
