Comprehensive profiling of TCR and BCR repertoire of infiltrated lymphocytes in the mouse injured skeletal muscle

Abstract

Abstract Lymphocytes infiltrating to the injured skeletal muscle have been shown to play an important role in muscle regeneration. Site-specific infiltrating/expanding lymphocytes and its molecular features are potential resources for bioengineering such as a drug delivery system. Although some previous studies showed the accumulation of lymphocytes to the injured skeletal muscle, the actual frequency of distinct lymphocyte clones in situ is still unclear. Hence, a comprehensive picture of the lymphocyte repertoire has yet to be described in detail. To this end, we conducted a comprehensive profiling of TCR and BCR repertoire of infiltrating lymphocytes in the mouse injured skeletal muscle model by next-generation sequencing. In the TCR repertoire profiling, we found that the expression level of TCR transcripts contains unique CDR3 α and distinct population of CDR3 β were increased (7.6–17% and 6.7–15%) in infiltrating T cells in both of cardiotoxin- or cryo-injured skeletal muscle, whereas no clonal expansion of specific TCR α/β transcripts observed in control splenic T cells (<1% respectively). While in the BCR repertoire profiling, various transcripts of immunoglobulin kappa chains showed expansion in infiltrated fraction, despite the proportion of immunoglobulin heavy and lambda chain were remained similar to control splenic B cells. Together these data have allowed us to identify TCR/BCR candidates targeting injured skeletal muscles. Furthermore, we aim to utilize the T cells/B cells expressing high-affinity TCR/BCR for the drug delivery system, especially for large protein complexes.