Single-cell T-cell receptor repertoire profiling in dogs

Area of Science:

• Comparative oncology
• Immunogenomics
• Canine cancer research

Background:

• Spontaneous canine cancers serve as valuable models for human diseases.
• Tracking tumor-specific immune responses is essential for advancing cancer immunotherapy.
• Species-specific reagents for single-cell T cell receptor sequencing (scTCRseq) are needed for canine cancer models.

Purpose of the Study:

• To demonstrate the applicability of scTCRseq in companion dogs with cancer.
• To integrate scTCRseq with scRNA data in a canine cancer immunotherapy context.
• To characterize T cell receptor repertoires in healthy dogs and dogs with T cell lymphoma and melanoma.

Main Methods:

• Single-cell suspensions from PBMCs and lymph node aspirates were analyzed.
• Profiling involved dog-specific scTCRseq primers and single-cell RNA (scRNA) sequencing.
• V(D)J gene segments and T cell receptor clonotypes were identified and quantified.

Main Results:

• Over 77,000 V(D)J-expressing cells were detected, with thousands of unique clonotypes per sample.
• A high percentage of known functional TRAV, TRAJ, TRBV, and TRBJ gene segments were observed.
• Healthy dogs showed diverse repertoires, lymphomas had clonal repertoires, and melanoma dogs exhibited dominant clonotypes, primarily CD8+ T cells with activated phenotypes.

Conclusions:

• scTCRseq is applicable and valuable for canine cancer immunotherapy research.
• Distinct T cell receptor repertoire profiles correlate with cancer type and treatment.
• Identified T cell populations in melanoma suggest potential anti-tumor activity, warranting further investigation.