Hyperglycemic memory of innate immune cells promotes in vitro proinflammatory responses of human monocytes and murine macrophages
Ontology highlight
ABSTRACT: It has been well established that the presence of diabetes is accompanied by a chronic inflammatory state promoting various diabetes-associated complications. One potential driver of this enhanced inflammatory state in patients with diabetes is hyperglycemia. Even after blood glucose control is achieved, diabetes-associated complications persist, suggesting the presence of a “hyperglycemic memory.” Innate immune cells, critically involved in various complications associated with diabetes, can build nonspecific, immunological memory (trained immunity) via epigenetic regulation. We examine the potential involvement of hyperglycemia-induced trained immunity in promoting inflammation. Our results show that hyperglycemia induces a trained phenotype in vivo in mice and in vitro in human monocytes, representative by an increased TNF-a secretion after ex vivo stimulation with LPS. These effects were largely mediated by epigenetic changes controlled by the mixed lineage leukemia (MLL) family because treatment with the MLL inhibitor menin-MLL during the process of trained immunity acquisition repressed the proinflammatory phenotype. Collectively, our results identify a novel link between hyperglycemia and inflammation in innate immune cells that might explain the increased proinflammatory state during diabetes potentially contributing to the development of various diabetes-associated complications.
Project description:Hyperglycemia is the hallmark of diabetes mellitus that results in oxidative stress, endothelial dysfunction and vascular complications of diabetes. MicroRNAs (miRNAs) play a role in the development of endothelial dysfunction in diabetes, with potential application for the future therapy of diabetic vascular complications. However, there is a limited number of studies that characterize the miRNA profile of endothelial cells exposed to hyperglycemic condition. This study aimed to identify the miRNA profile of human umbilical vein endothelial cells (HUVEC) exposed to hyperglycemic state using RNA sequencing analysis.
Project description:Patients with long-duration diabetes develop cardiovascular complications resulting in highly increased mortality and complications which affect the kidneys, eyes and peripheral nerves associated with high morbidity. Among the diabetic complications, damage in the eye, diabetic retinopathy, is the most common microvascular complication of diabetes. Diabetic retinopathy is a leading cause of vision-loss globally. It is characterized by a number of different patho-mechanisms including changes in vascular permeability, capillary degeneration, and finally at a late stage overshooting formation of new blood vessels. This expression analysis focused on the use of different experimental models for Diabetes Mellitus and its complications (for a review see 1: Al-Awar et al: Experimental Diabetes Mellitus in Different Animal Models. J Diabetes Res. 2016; doi: 10.1155/2016/9051426). By that, we wanted to uncover the relative contributions of systemic hyperinsulinaemia and/or hyperglycemia to molecular regulations. The following models have been used: As insulinopenic, hyperglycemic model reflecting Type 1 diabetes, male STZ-Wistar rats (60mg/kg BW; i.p.) were used. Wistar rats without STZ injection served as non-diabetic controls. Male obese ZDF rats (Fa/Fa) were used as type-2 diabetes model characterized by persisting hyperglycemia and transient hyperinsulinemia. Male lean ZDF rats (Fa/-) served as non-diabetic controls. Male obese ZF rats (Fa/Fa) hyperglycemia were used reflecting euglycemia and severe insulin resistance. Male lean ZF rats (Fa/-) served as controls. ZDF and ZF rats were obtained in two genotypes, obese (genotype fa/fa) and lean littermates (genotype Fa/?). All rats were housed in standard cages under a normal light-dark cycle for 16 weeks. All animals had free access to food and water. ZF and Wistar rats received a standard chow (Ssniff R/M) and ZDF rats received Purina 5008 chow. A group size of n=8 were used for all study groups. Wistar rats were rendered type-1 like hyperglycemic and hypoinsulinemic via a single injection of streptocotocin (STZ, 60mg/kg; i.p.) at 7 weeks of age. Obese ZDF rats (fa/fa) develop spontaneously a type-2 diabetes phenotype with persisting hyperglycemia and transient hyperinsulinemia (hyperglycemic, hypoinsulinemic). Obese ZF rats (fa/fa) develop insulin resistance with permanent hyperinsulinemia without concomitant hyperglycemia and no overt diabetes phenotype. Non STZ treated Wistar rats, lean ZDF littermates (Fa/?), and lean ZF littermates (Fa/?) served as controls. All groups were kept for 12 weeks on respective conditions together with appropriate age-matched controls. Unbiased gene expression analysis was performed per group using Affymetrix gene arrays.
Project description:Endothelial cells and high glucose-induced endothelial dysfunction are the common origin of chronic diabetic complications such as retinopathy, nephropathy, and cardiomyopathy. Yet their common origins, the vascular manifestations of such complications are different. We examined the basal heterogeneity between microvascular endothelial cells (MECs) from the retina, kidneys, and heart, as well as their differential responses to hyperglycemia in diabetes. To this extent, we used a spatial transcriptomic approach to investigate gene expression differences across retinal, renal, and cardiac MECs in diabetic and non-diabetic mouse models. We further validated MEC heterogeneity in vitro using human retinal and cardiac MECs. We found that MECs from different target organs of major diabetic complications were transcriptomically distinct at the basal state and respond differently to hyperglycemia.
Project description:Innate immune memory, also called "trained immunity," is a metabolically and epigenetically regulated functional state of myeloid cells. This phenomenon is important for host defense, but also plays a role in various immune-mediated conditions. We found that exogenously administered sphingolipids and inhibition of enzymes involved in sphingolipid metabolism modulate trained immunity. In particular, we found that acid ceramidase, an enzyme that converts ceramide to sphingosine, is a potent regulator of trained immunity. We discovered that acid ceramidase regulates the expression of genes encoding histone-modifying enzymes, resulting in profound changes in the epigenetic landscape. We confirmed our findings by identifying single-nucleotide polymorphisms in the region of ASAH1, the gene encoding acid ceramidase, that are associated with the trained immunity cytokine response. Our findings reveal a novel immunomodulatory effect of sphingolipids, provide new insight into the metabolic regulation of trained immunity, and identify acid ceramidase as a therapeutic target to modulate it.
Project description:Neutrophils play an active role in acute and chronic inflammation by exhibiting functional heterogeneity. Besides beneficial role in acute infections to eliminate pathogens, neutrophils also contribute to pathogenesis of diseases associated with sterile inflammation including vascular disorders, autoimmune diseases, Type 2 diabetes (T2D) and cancers. During T2D, hyperglycemia constitutively activate neutrophils. In the context of T2D associated complications, we examined influence of high glucose, homocysteine and LPS representing effector molecules of hyperglycemia, thrombosis, and infection respectively on human neutrophil activation to identify distinct signaling pathways by quantitative phosphoproteomics approach.
Project description:Type 2 diabetes is an increasing pandemic health problem and leads to several late diabetic complications of organs including kidney and eye. Lowering elevated blood glucose levels is the typical therapeutic goal in clinical medicine. However, it is possible that hyperglycemia is only a symptom of diabetes but not the correct target to monitor, in order to prevent late diabetic complications. Instead, other diabetes-related alterations could be primary causes for late diabetic complications. Here, we studied the role of CaM Kinase II δ (CaMKIIδ) that is activated through diabetic metabolism. CaMKIIδ is expressed ubiquitously and might therefore affect several different organ systems. We crossed diabetic leptin receptor mutant mice to mice lacking CaMKIIδ globally. Remarkably, CaMKIIδ-deficient diabetic mice did not develop hyperglycemia. As potential underlying mechanisms, we found evidence for improved insulin sensing and increased glucose transport into skeletal muscle. Despite normoglycemia CaMKIIδ-deficient diabetic mice developed the full picture of diabetic nephropathy. In contrast, diabetic retinopathy was prevented. These data challenge the clinical concept of normalizing elevated high glucose levels in diabetes as a causative treatment strategy for late diabetic complications and call for a more detailed analysis of intracellular metabolites in different organs.
Project description:Trained innate immunity can be induced in human macrophages by microbial ligands, but it is unknown if exposure to endogenous alarmins such as cathelicidins can have similar effects. Previously, we demonstrated sustained protection against infection by the chicken cathelicidin-2 analog DCATH-2. Thus, we assessed the capacity of cathelicidins to induce trained immunity. PMA23 differentiated THP-1 (dTHP1) cells were trained with cathelicidin analogs for 24 hours, and restimulated after a 3-day rest period. DCATH-2 training of dTHP-1 cells amplified their proinflammatory cytokine response when restimulated with TLR2/4 agonists. Trained cells displayed a biased cellular metabolism towards mTOR-dependent aerobic glycolysis and long-chain fatty acid accumulation and augmented microbicidal activity. DCATH-2-induced trained immunity was inhibited by histone acetylase inhibitors, suggesting epigenetic regulation, and depended on caveolae/lipid raft-mediated uptake, MAPK p38 and purinergic signaling. To our knowledge, this is the first report of trained immunity by host defense peptides.
Project description:The hyperglycemic state in diabetes mellitus (DM) induces oxidative stress and inflammation, thus contributing to diabetic tissue damage and associated complications. Astaxanthin, a potent antioxidant carotenoid, has been investigated for its potential in preventing and managing diabetes across various species, but its effect on client-owned dogs is not well-studied. This study explored the impact of astaxanthin supplementation on canine DM using a proteomic approach. A total of 18 client-owned dogs were enrolled: 6 dogs with DM and 12 clinically healthy dogs. The diabetic dogs received their standard treatment regimen alongside daily oral supplementation of 12 mg of astaxanthin (1.5–2.4 mg/kg) for 90 days. Plasma samples were collected at the beginning and end of the study period for proteomic analysis. After astaxanthin supplementation, there were significant alterations in protein expression associated with the complement system, coagulation cascade, JAK-STAT signaling, and protein kinase C signaling, which all contribute to inflammation and oxidative stress. Astaxanthin demonstrated a protective effect against diabetes-associated complications, including insulin resistance, vascular dysfunction, nephropathy, and cardiac complications. These findings highlight the potential of astaxanthin as a complementary therapeutic agent for controlling DM in canines.
Project description:Hyperglycemia is a hallmark in prediabetes and type 2 diabetes mellitus (T2DM) which increases risk of micro and macrovascular complications such as diabetic retinopathy, diabetic nephropathy (microvascular complications), and peripheral vascular disease, cerebrovascular disease and cardiovascular diseases (macrovascular complications). Endothelial cells are affected in both cases. In this study, we investigated the miRNA expression changes in HUVECs during different glucose treatment (5mM, 10mM, 25mM and 40mM glucose) at various time intervals (6, 12, 24 and 48hrs). The results of miRNA microarray showed there is a correlation between hyperglycemia induced endothelial dysfunction and miRNA expression. In silico prediction showed that the following pathways: Regulation of actin cytoskeleton, PI3K-Akt signaling pathway, Apoptosis, Neurotrophin signaling pathway, and Insulin signaling pathway, were dysregulated during hyperglycemia. Majority of the pathways are related to apoptosis. 10 miRNAs (miR-26a-5p, -26b-5p, 29b-3p, 29c-3p, 125b-1-3p, -130b-3p, - 140-5p, -221-3p, -192-5p, and -320a,) showed increased expression with increasing concentration of glucose treatment. miR-26a-5p, -29b-3p, - 140-5p, -221-3p, and -192-5p are involves in endothelial apoptosis. Our study revealed miRNAs (miR-29b-3p and – 192-5p) with known mRNA targets (BCL2 and MCL1) showed expression pattern inversely correlating with their respective target mRNAs. Therefore these miRNAs could involve in the endothelial dysfunction due to hyperglycemia.
Project description:Diabetes is emerging as a severe global health problem that threatens health and increases socio-economic burden. Periodontal impairment is one of its well-recognized complication. The destruction of the periodontal defense barrier makes it easier for periodontal pathogens to invade in, triggering a greater inflammatory response, and causing secondary impairment. Macrophages are the major immune cells in periodontium, forming the frontier line of local innate immune barrier. Here, we explored the periodontal impairments and functional changes of macrophages under the diabetic and aging condition. Besides, we further explored the molecular mechanism of how the hyperglycemia and aging contributes to this pathogenesis. To test this, we used young and aged mice to build diabetic mice, and metformin treatment was applied to a group of them. We demonstrated that under hyperglycemia condition, macrophage functions, such as inflammatory cytokines secretion, phagocytosis, chemotaxis, and immune response were disturbed. Simultaneously, this condition elevated the local senescent cell burden and induced secretion of senescence-associated secretory phenotype (SASP). Meanwhile, we found that expressions of GSDMD and caspase-1 were upregulated in diabetic conditions, suggesting that the local senescent burden and systemic proinflammatory state during diabetes were accompanied by the initiation of pyroptosis. Furthermore, we found that the changes in aged condition were similar to those in diabetes, suggesting a hyperglycemia-induced pre-aging state. In addition, we show that metformin treatment alleviated and remarkably reversed these functional abnormalities. Our data demonstrated that diabetes initiated macrophage pyroptosis, which further triggered macrophage function impairments and gingival destructions. This pathogenesis could be reversed by metformin.