Mesenchymal Stem Cells from Mouse Hair Follicles Inhibit the Development of Type 1 Diabetes.

Mesenchymal stem cells (MSCs) are known for their immunosuppressive properties. Based on the demonstrated anti-inflammatory effect of mouse MSCs from hair follicles (moMSCORS) in a murine wound closure model, this study evaluates their potential for preventing type 1 diabetes (T1D) in C57BL/6 mice. T1D was induced in C57BL/6 mice by repeated low doses of streptozotocin. moMSCORS were injected intravenously on weekly basis. moMSCORS reduced T1D incidence, the insulitis stage, and preserved insulin production in treated animals. moMSCORS primarily exerted immunomodulatory effects by inhibiting CD4+ T cell proliferation and activation. Ex vivo analysis indicated that moMSCORS modified the cellular immune profile within pancreatic lymph nodes and pancreatic infiltrates by reducing the numbers of M1 pro-inflammatory macrophages and T helper 17 cells and upscaling the immunosuppressive T regulatory cells. The proportion of pathogenic insulin-specific CD4+ T cells was down-scaled in the lymph nodes, likely via soluble factors. The moMSCORS detected in the pancreatic infiltrates of treated mice presumably exerted the observed suppressive effect on CD4+ through direct contact. moMSCORS alleviated T1D symptoms in the mouse, qualifying as a candidate for therapeutic products by multiple advantages: non-invasive sampling by epilation, easy access, permanent availability, scalability, and benefits of auto-transplantation.

Development of Type 1 Diabetes in Mice Is Associated with a Decrease in IL-2-Producing ILC3 and FoxP3+ Treg in the Small Intestine.

Recent data indicate the link between the number and function of T regulatory cells (Treg) in the gut immune tissue and initiation and development of autoimmunity associated with type 1 diabetes (T1D). Since type 3 innate lymphoid cells (ILC3) in the small intestine are essential for maintaining FoxP3+ Treg and there are no data about the possible role of ILC3 in T1D pathogenesis, the aim of this study was to explore ILC3-Treg link during the development of T1D. Mature diabetic NOD mice had lower frequencies of IL-2-producing ILC3 and Treg in small intestine lamina propria (SILP) compared to prediabetic NOD mice. Similarly, in multiple low doses of streptozotocin (MLDS)-induced T1D in C57BL/6 mice, hyperglycemic mice exhibited lower numbers of ILC3, IL-2+ ILC3 and Treg in SILP compared to healthy controls. To boost T1D severity, mice were treated with broad-spectrum antibiotics (ABX) for 14 days prior to T1D induction by MLDS. The higher incidence of T1D in ABX-treated mice was associated with significantly lower frequencies of IL-2+ ILC3 and FoxP3+ Treg in SILP compared with mice without ABX treatment. The obtained findings show that the lower proportions of IL-2-expressing ILC3 and FoxP3+ Treg in SILP coincided with diabetes progression and severity.

Phenethyl ester of rosmarinic acid attenuates autoimmune responses during type 1 diabetes development in mice.

AIMS: Rosmarinic acid (RA) is a polyphenol that occurs in plants of the Lamiaceae family. Phenethyl ester of RA (PERA), a novel RA derivative, has been developed and evaluated in vivo in an animal model of type 1 diabetes (T1D). METHODS: T1D was induced in male C57BL/6 mice using multiple low doses of streptozotocin (STZ) administered intraperitoneally for 5 consecutive days. Intraperitoneal administration of PERA (2.5 mg/kg bw) began from the first STZ injection and continued for 20 days. KEY FINDINGS: PERA-treated mice exhibited lower incidence of T1D (monitored up to 38 days from the disease induction), and fluorescent histochemical analysis showed that their pancreatic islets expressed more insulin. PERA treatment significantly down-regulated the proportions of CD11b+ and CD11c+ myeloid cells in the immune cell infiltrates in the pancreatic islets early during T1D pathogenesis (on day 9 after T1D induction), while on day 15, PERA significantly reduced the proportions of CD11c+, CD8+, Th1 and Th17 cells. Simultaneously, it was found that the cells from the pancreatic infiltrates of PERA-treated mice produced significantly less reactive oxygen species than cells from the control group. SIGNIFICANCE: These findings suggest that PERA efficiently prevented T1D development in mice. Interestingly, PERA attenuated the inflammatory process in the islets through temporally specific interference with the innate and adaptive immune response and therefore shows great promise for further clinical evaluation as a novel T1D therapeutic.