TOLerogenic Potential of Hematopoietic Stem and Progenitor Cells and Inflammatory Bowel Disease

Inflammatory Bowel Disease (IBD) is a chronic inflammatory condition affecting the gastrointestinal tract, with Crohn's Disease (CD) and Ulcerative Colitis (UC) being the main types. The causes of IBD are complex and include immune dysregulation with activation of immune cells, release of inflammatory cytokines, and intestinal tissue damage. Despite significant advances in the treatment of pediatric IBD, a large unmet need for a definitive cure remains, and cell immunotherapy is under investigation. The investigators are specifically interested in refractory IBD, a chronic active condition requiring continuous treatment for symptom relief, with detrimental side effects. Despite the several treatment options currently available, 30% of pediatric IBD patients are refractory, and none of the existing treatments results in complete remission.

Interleukin 10 (IL-10) is an immunoregulatory cytokine associated with IBD pathogenesis and regulating gut homeostasis. Type 1 regulatory T (Tr1) cells produce IL-10 and their function is crucial for suppression of inflammation in IBD. The investigators recently published that antigen (Ag)-specific immune responses in Celiac Disease can be controlled via IL-10-producing Ag-presenting cells engineered to express a gliadin epitope, demonstrating that Ag-presenting cells can be manipulated to promote Tr1 cell differentiation.

Significant advances in the field of hematopoietic stem and progenitor cells (HSPCs) engineering and biology have been achieved. The development of protocols for ex-vivo manipulation and expansion of circulating (c)HSPCs and of mobilization-based chemotherapy-free approaches broadens the applicability of HSPC-based therapies to diseases for which HSPC transplantation is not the standard of care. A recent report showed that Tr1 cells can be promoted by immunogenic HSPC, which present Ags via HLA class II to CD4+ T cells in the bone marrow. This discovery opens new avenues for the development of approaches exploiting the Ag-presenting capacity and the tolerogenic potential of HSPCs to counteract inflammation in target tissues.

Based on these premises, with the final goal of developing a procedure for the induction of IL-10-mediated tolerance to control intestinal inflammation in refractory IBD pediatric patients, the investigators will:

• Investigate the type and frequency of inflammatory and regulatory immune cells, including IL-10-related regulatory cells, infiltrating the gut mucosa of IBD and non-IBD control patients. Results will indicate whether enforcement of the regulatory arm would benefit IBD patients. To this aim, it is necessary to collect and analyze intestinal tissue fragments from IBD and non-IBD control patients.
• Investigate the type and frequency of immune cells, including IL-10-related regulatory cells, circulating in the peripheral blood of IBD patients and non-IBD control patients. Results will indicate whether enforcement of the regulatory arm would benefit IBD patients. To this aim it is necessary to collect PB from IBD and non-IBD control patients.
• Characterize the presence, phenotype, and expansion potential of CD34+ HSPCs circulating in the peripheral blood of IBD patients. To this end, the investigators will collect peripheral blood from IBD patients, and i) assess the frequency, composition, and Ag-presenting potential of and ii) apply ex-vivo expansion and engineering protocols to CD34+ HSPC circulating in the peripheral blood of IBD patients. These results will be pivotal for assessing the feasibility of HSPC-based approaches to restore homeostasis in the intestinal tissue in refractory pediatric IBD.
• Evaluate the response to commensal-derived Ags (e.g., Bacteroides-derived peptides) of CD4+ T lymphocytes circulating by collecting the peripheral blood of IBD patients, non-IBD control patients, and healthy subjects as control. These results will indicate which Ag could be used for HSPC engineering and for inducing IL-10-producing regulatory T cells.
• Assess the ability of human HSPCs to promote Ag-specific Tr1 cells in vitro. To this end, selected IBD patients known to be responders commensal -derived Ags (as above) and peripheral blood will be collected at 1 year (6-18 months) follow-up. The investigators will engineer circulating HSPCs ex-vivo expanded from the peripheral blood of selected IBD patients and test for their ability to promote Ag-specific Tr1 cell upon in vitro culture with autologous CD4+ T cells.

Inclusion criteria

For all groups:

• Written informed consent from parent(s)/legal guardian(s);
• Sex: Males and Females;
• Age: ≥2 years and <18 years.

For study group 1:

• Subjects with suspected or confirmed IBD diagnosis.

For study group 2:

• Subjects with rectal bleeding w/o inflammatory disorders of the gastrointestinal tract.

For study group 3:

• Written consent for participation to TIGET09 study protocol;
• healthy subjects, without known immunodeficiencies, autoimmune, inflammatory or genetic diseases, undergoing genetic, hematological, hematochemical, or HLA compatibility screenings and participating in the TIGET09 study protocol (Title: "Collection of biological samples for the study of blood cells and their microenvironment, and for the development of novel therapeutic approaches for genetic diseases and cancer").

Exclusion criteria

For all groups:

• Refusal or inability of the parent(s) or legal guardian(s) to provide written informed consent;
• Age: <2 years and ≥18 years;
• Presence of any medical, psychiatric, or clinical condition that, in the opinion of the clinician, may interfere with participation in the study or interpretation of the study results;

For study group 1:

• patients without IBD diagnosis or suspect;

For study group 2:

• Subjects without rectal bleeding or with known inflammatory/autoimmune disorders of the gastrointestinal tract.

For all groups:

• Refusal or inability of the parent(s) or legal guardian(s) to provide written informed consent;
• Age: <2 years and ≥18 years;
• Presence of any medical, psychiatric, or clinical condition that, in the opinion of the clinician, may interfere with participation in the study or interpretation of the study results;

For study group 1:

• patients without IBD diagnosis or suspect;

For study group 2:

• Subjects without rectal bleeding or with known inflammatory/autoimmune disorders of the gastrointestinal tract.

For study group 3:

• Lack of written consent for participation to TIGET09 study protocol;
• patients belonging to study groups 1 and 2; patients with immunodeficiencies, autoimmune, inflammatory or genetic diseases;
• subjects with signs of systemic inflammation.