Tissue-autonomous pharmacological direction: how target expression landscapes convert balanced compounds into...

Area of Science:

• Pharmacology
• Systems Biology
• Genomics

Background:

• Multi-target drugs can exhibit opposing effects in different tissues, a phenomenon lacking a unifying predictive principle.
• Existing explanations focus on drug-specific mechanisms, failing to account for tissue-dependent directionality.

Purpose of the Study:

• To propose and validate a unifying principle, tissue-autonomous pharmacological direction (TAPD), for predicting drug effects across tissues.
• To introduce the Tissue Direction Index (TDI) as a metric integrating drug affinity and tissue-specific gene expression.

Main Methods:

• Formalized the TAPD principle using the Tissue Direction Index (TDI), a metric combining binding affinity and transcriptomic data.
• Applied the TDI to analyze metabolites from traditional Chinese botanical drugs, assessing their hemostatic direction shifts.
• Evaluated TAPD's relevance to existing drug classes like SERMs, NSAIDs, kinase inhibitors, and immunomodulators.

Main Results:

• Demonstrated substantial hemostatic direction shifts (4.6-fold Hemostatic Index change) for metabolites between gastrointestinal and brain tissues, driven by expression differences.
• Identified two metabolites that exhibited complete direction reversal of their pharmacological effect.
• Showcased TAPD as a complementary model to existing tissue-selective drug effect theories.

Conclusions:

• TAPD provides a predictive framework for understanding tissue-specific drug actions based on local target abundance.
• The TDI metric offers a quantitative approach to assess drug directionality across different tissue environments.
• TAPD has potential applications in drug repurposing, predictive toxicology, and personalized medicine.