Key result
Platelet P2Y1 deficiency reduces LPS-induced pulmonary leukocyte recruitment by ~65% in mice.
Why the study?
Pharmacological P2Y1 receptor antagonists have limited use due to inadequate pharmacokinetics and inability to distinguish global versus cell-specific effects in vivo, necessitating a platelet-specific P2Y1 receptor knockout model to study inflammation.
Platelet-specific P2Y1 receptor deficiency significantly suppresses leukocyte and platelet recruitment during LPS-induced pulmonary inflammation, confirming the receptor's role in regulating inflammatory responses.
A role for the P2Y 1 receptor in inflammation has been established using a pharmacological approach over an acute 4 hour time span. However, nucleotide-structure P2Y 1 receptor antagonists have limited experimental use due to inadequate pharmacokinetics, and inability to decipher global versus cell specific effects in vivo . The creation of a conditional knock out (platelet) P2Y 1 transgenic mouse model was designed to overcome these restrictions. A homozygous P2Y 1 LoxP mouse colony was created using CRISPR/Cas9 technology, and crossed with a hemizygous P2Y 1 LoxP with PF4-cre to provide offspring that are homozygous for P2Y 1 LoxP flanked allele, and hemizygous for the PF4cre (platelet P2Y 1 -/- ) and offspring homozygous for P2Y 1 LoxP flanked allele, but non-carriers for PF4cre (control mice). Animals were intranasally administered LPS to induce pulmonary inflammation to assess the influence of phenotype on leukocyte recruitment. 24 hours post intranasal LPS administration; pulmonary neutrophil and platelet recruitment were significantly suppressed, despite the fact that neutrophils retained the ability to migrate to fMLP ex vivo . Circulating platelet and leukocyte numbers were not different between control and platelet P2Y 1 -/- animals. Tail bleeding times revealed the platelet P2Y 1 -/- mice had a severe bleeding phenotype. This is the first demonstration of a platelet specific P2Y 1 -/- mouse model to confirm the importance of platelet P2Y 1 receptors in the regulation of inflammatory responses with a 60-70% inhibition of leukocyte recruitment over an extended time period compared to previous pharmacological studies. platelet P2Y 1 -/- mice will help further elucidate the mechanisms by which P2Y 1 receptors regulate platelet activation during inflammation. Key Points Mice selectively deficient in the platelet P2Y 1 have suppressed leukocyte and platelet recruitment during inflammation. We provide a methodology to determine mechanistic relevance that is otherwise limited by pharmacological approaches.
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Pan et al. (2024) studied LPS-induced pulmonary inflammation. Platelet-specific P2Y1 receptor deficiency vs. Wild-type mice was evaluated on Pulmonary leukocyte recruitment at 24 hours post LPS administration (60-70% inhibition, p=<0.01). Platelet-specific P2Y1 receptor deficient mice exhibited a 60-70% inhibition of pulmonary leukocyte recruitment 24 hours after intranasal LPS administration compared to wild-type mice.
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