Preparation and in vitro evaluation of RITUXfab-decorated lipoplexes to improve delivery of siRNA targeting C1858T PTPN22 variant in B lymphocytes

Type 1 diabetes (T1D) and autoimmune diseases are the most common autoimmune endocrine disorders. The lack of a cure, if not hormone therapy replacement, emphasizes the need to identify more effective strategies for their personalized prevention and treatment. Among the genetic variants associated with T1D, the C1858T (Lyp) polymorphism of the protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene alters the function of T cells but also of B cells in innate and adaptive immunity. We previously exploited a novel personalized immunotherapeutic approach based on siRNA delivered by liposomes (lipoplexes) that selectively inhibit variant allele expression. In this manuscript, we functionalized and improved lipoplexes carrying siRNA for variant C1858T with Fab of Rituximab antibody (RituxFab-Lipoplex) to specifically target B lymphocytes in autoimmune conditions, such as T1D. RituxFab-Lipoplexes specifically bind to B lymphocytes of the human Rajii cell and of human PBMC of healthy donors than the not functionalized ones. RituxFab-Lipoplexes have a significant higher inhibitory effect on the function of B lymphocytes of T1D patients after unmethylated bacterial DNA CpG stimulation, particularly on total cell proliferation and IgM+ plasma cell differentiation. These results might opened new investigations of applicability of RituxFab-Lipoplexes on immunocytes that pathogenetically contribute to other autoimmune disorders.