Liraglutide prevents hyperglycemia-induced senescence and proinflammatory monocyte differentiation in CD34+ hematopoietic stem cells

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Italian Ministry of Health- Ricerca Finalizzata Background Diabetes mellitus (DM) is known to promote aberrant activation of immune cells that contribute to the onset and progression of chronic inflammation and atherosclerosis in DM patients (1). This phenomenon, termed 'trained immunity', appears to be initiated in hematopoietic stem/progenitor cells (HSPCs). In recent years, there has been great interest in investigating the pleiotropic effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs), including anti-inflammatory and immunological properties. We have recently demonstrated that HSPCs express the GLP-1R whose stimulation with the agonist liraglutide (LIRA) prevents oxidative stress and functional impairment induced by hyperglycemic conditions (HG) (2). On this basis, we hypothesized that LIRA treatment can also avert HG-induced senescence and proinflammatory myeloid differentiation of HSPCs. Purpose To evaluate senescence and inflammatory myeloid differentiation of CD34+ HSPCs after HG exposure in the presence or not of GLP1R agonist. Methods CD34+ HSPCs derived from cord blood of healthy donors were expanded in normal-glucose (NG; with 30 mM mannitol for osmotic control) or high-glucose (HG; 30 mM) and treated or not with LIRA (100nM) in serum-free medium plus cytokines (FLT3, SCF, IL3 and IL6) for up to 20 days. The expression of p21, p27, IL6, TNFα, and NFkB-p65 genes was assessed by qPCR. ROS production and CD34+ HSPC-derived monocyte subsets were evaluated by flow cytometry whereas cytokine secretion after LPS stimulation was measured by ELISA assay. Results LIRA treatment showed to significantly prevent the impairment of CD34+ HSPC proliferation as well as the upregulation of senescence-associated secretory phenotype (SASP) genes such as p21, p27, NFkB-p65, IL6, and TNFα in HG-CD34+ HSPCs when compared to HG cell alone (one-way ANOVA; p≤0.05). Interestingly, these pharmacological effects were associated with a significant reduction in HG-induced ROS production. Myeloid differentiation in vitro of HG-CD34+ HSPCs generated monocytes composed mainly of an inflammatory and highly reactive intermediate (CD14++CD16+) subpopulation characterized by higher LPS-induced release of IL6 and TNFα. LIRA treatment significantly prevented both the accumulation of intermediate (CD14++CD16+) monocyte subpopulation from differentiating HG-CD34+ HSPCs and their inflammatory phenotype (one-way ANOVA; p≤0.05). Conclusions These results demonstrate that HG exposure alters the differentiation program of CD34+ HSPCs towards more inflammatory immune cell components and suggest that GLP1R agonists are endowed with immunomodulatory properties that could be further developed and exploited for the treatment of immune system dysregulation in diabetes.