San Raffaele Telethon Institute for Gene Therapy

Mechanisms of peripheral tolerance


Group Leader

Silvia Gregori


The development of novel approaches to control unwanted immune responses represents an ambitious goal in the management of immune-mediated diseases, including detrimental responses after protein/gene replacement therapies and in autoimmunity. Empowering the tolerogenic arm of the immune system would restore the immune balance leading to control of dysregulated immunity. The ability to modulate immune responses and promote tolerance makes regulatory cells, including T cells and dendritic cells (DCs), the cells of choice for the control of adverse immune responses. The research interests of the lab are i) to underpin the role of tolDCs in healthy and pathological conditions, ii) to identify the novel molecular mechanisms driving inflammatory/tolerogenic behavior of DCs and T cells, and iii) to dissect antigen-specific responses in patients undergoing protein replacement or gene therapy. The goal of our studies is to develop innovative and efficient tolerogenic approaches to circumvent adverse immune responses and (re)establish antigen-specific tolerance in immune-mediated diseases and in monogenic diseases after protein replacement therapy or gene therapy.

Research activity

The group focused its research on IL-10-secreting regulatory cells and contributed to the identification of DC-10, a subset of myeloid regulatory cells that are present in vivo and inducible in vitro (Gregori, Blood 2010; Amodio, Hematologia 2015; Comi, CMI 2020). DC-10 are tolerogenic DCs that secrete IL-10 and express HLA-G and ILT4, which render them inducers of type 1 T regulatory cells (Tr1) cells. We are currently defining the role of DC-10 in controlling immune responses in healthy and pathological conditions. Moreover, the group developed an innovative approach, based on Lentiviral Vector (LV)- mediated gene transfer to generate stable and effective human tolDCs suitable for cell-based approaches in autoimmune diseases and after protein/gene replacement therapies. One major hurdle in the development of cell and gene therapy approaches is indeed the induction of adverse immune responses elicited by the transgene itself and/or the vector-derived products, which may limit the overall efficacy of the therapy, especially in immunocompetent hosts. The knowledge generated by the deep characterization of the mechanisms underlying adverse immune responses to protein/gene replacement therapies (e.g., patients with lysosomal storage disorders undergoing enzyme protein replacement therapy or gene therapy) and in diseases due to tolerance breakdown (e.g., autoimmune diseases) will help developing novel approaches to circumvent detrimental immune responses and promote antigen-specific tolerance in protein replacement therapy and gene therapy.

The current Research Areas of our lab aim at:

  1. Studying the biology of regulatory cells and defining cell-based approaches to control unwanted immune responses in protein/gene replacement therapy and autoimmunity. The aims of this research area are i) to unravel the key molecular and cellular mechanisms modulating immune tolerance mediated by tolDCs and regulatory T cells (Tregs); ii) to identify novel targets controlling tolerogenic pathways; and iii) to generate stable and effective human tolDCs suitable for cell-based approaches. Our research is focused on IL-10-producing regulatory cells and on a peculiar myeloid cell-subset named DC-10. Our basic research studies aim at defining the role of DC-10 in promoting Tregs in pathological conditions (PoP conditions under investigation: Celiac Disease, autoimmune diseases, and male infertility), and at identifying new targeted strategies to restore tolerance by investigating the molecular mechanisms controlling inflammatory versus tolerogenic activity in DC-10, and DC-10-mediated priming of effector and Treg cells in healthy subjects and autoimmune patients. Our translational studies aim at developing innovative and effective tolDC-based approaches, by means of lentiviral vector (LV)-mediated gene transfer of tolerogenic factors to DCs or by targeting pro-tolerogenic pathways, with the final goal of modulating immune responses and promoting long-term tolerance via Treg induction in in protein/gene replacement therapies (PoP diseases include T1D, MPSIVA, and Pompe Disease) and autoimmunity
  2. Characterizing detrimental immune responses to protein replacement therapies and developing circumvention approaches. Protein replacement therapy is widely used as therapeutic treatment in monogenic diseases and LV-based gene therapy in vivo gave promising safety and efficacy results in pre-clinical animal models. However, in both settings immune responses directed towards recombinant proteins, vector-derived antigens, and transgenes may limit the efficacy of the therapies. We will dissect the presence, kinetic, and intensity of enzyme-specific immune responses in enzyme replacement therapy (ERT)-treated patients (PoP diseases MPSIVA, Pompe disease, and alpha-Mannosidases) and transgene-specific immune responses in pre-clinical settings (PoP diseases MPSI, MPSIVA, Pompe disease). With the aim of inducing antigen-specific tolerance and ensure long-term efficacy of the therapeutic proteins, we will also exploit novel tolDC-based approaches to circumvent adverse immune responses in the context of ERT or in vivo gene therapy.