ABSTRACT
Regulatory T cells (Tregs) are a subpopulation of T cells that are specialized in suppressing immune responses. Here we show that the arginine methyl transferase protein PRMT5 can complex with FOXP3 transcription factors in Tregs. Mice with conditional knock out (cKO) of PRMT5 expression in Tregs develop severe scurfy-like autoimmunity. In these PRMT5 cKO mice, the spleen has reduced numbers of Tregs, but normal numbers of Tregs are found in the peripheral lymph nodes. These peripheral Tregs that lack PRMT5, however, display a limited suppressive function. Mass spectrometric analysis showed that FOXP3 can be di-methylated at positions R27, R51, and R146. A point mutation of Arginine (R) 51 to Lysine (K) led to defective suppressive functions in human CD4 T cells. Pharmacological inhibition of PRMT5 by DS-437 also reduced human Treg functions and inhibited the methylation of FOXP3. In addition, DS-437 significantly enhanced the anti-tumor effects of anti-erbB2/neu monoclonal antibody targeted therapy in Balb/c mice bearing CT26Her2 tumors by inhibiting Treg function and induction of tumor immunity. Controlling PRMT5 activity is a promising strategy for cancer therapy in situations where host immunity against tumors is attenuated in a FOXP3 dependent manner.
Subject(s)
Antibodies, Monoclonal, Humanized/therapeutic use , Breast Neoplasms/therapy , Forkhead Transcription Factors/metabolism , Gene Knockout Techniques , Immunotherapy/methods , Protein-Arginine N-Methyltransferases/genetics , Protein-Arginine N-Methyltransferases/metabolism , Receptor, ErbB-2/immunology , Animals , Antibodies, Monoclonal, Humanized/pharmacology , Autoimmunity/genetics , Female , Forkhead Transcription Factors/genetics , HEK293 Cells , Humans , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Transgenic , Molecular Targeted Therapy/methods , Point Mutation , Receptor, ErbB-2/antagonists & inhibitors , T-Lymphocytes, Regulatory/metabolism , TransfectionABSTRACT
The present investigation determined the molecular structure and the pharmacokinetic and pharmacodynamic profiles of oral unfractionated heparin containing oral absorption enhancer sodium N-[8-(2-hydroxybenzoyl) amino]caprylate, salcaprozate sodium (SNAC) and assessed the safety and tolerability of the orally dosed heparin solid dosage form versus other routes. Sixteen healthy men were included in this single-dose, 3-way crossover, randomized, open-label study. Disaccharide compositional analysis was performed using capillary high-performance liquid chromatography with electrospray ionization mass spectrometry detection. The pharmacodynamics of heparin were obtained from analysis of plasma anti-factor Xa, anti-factor IIa, activated partial thromboplastin time, and total tissue factor pathway inhibitor data. The molecular weight properties and the disaccharide composition of orally administered unfractionated heparin/SNAC and parenterally administered unfractionated heparin are identical and consistent with the starting pharmaceutical standard heparin. Furthermore, the anti-factor Xa/anti-factor IIa ratio achieved is of approximately 1:1. This is the first true pharmacokinetic study to measure the chemical compositions of heparin administered by different routes.
