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A high glycemic burden drives functional and metabolic alterations of human monocytes in patients with type 1 diabetes

ABSTRACT: Diabetes mellitus is associated with serious long-term complications, including increased cardiovascular risk and a higher occurrence of infections. These diabetes-related complications are suggestive of altered responses of the innate immune system. Recent studies have shown that energy metabolism of monocytes is a crucial determinant of their functionality. Here we investigate whether metabolism and function of monocytes are changed in patients with diabetes and aim to identify diabetes-associated factors driving these alterations. Patients with type 1 diabetes (T1D) and healthy age-, sex- and BMI-matched nondiabetic controls were recruited and detailed characteristics related to disease status including diabetes duration and glycemic burden (HbA1c levels) were collected. Monocytes were isolated from peripheral blood to determine immune functionality, metabolic responses and to perform transcriptome analyses. Upon ex vivo stimulation with TLR-4 agonist LPS or TLR-2 agonist P3C, monocytes of patients with T1D secreted lower levels of various cytokines (TNFα, IL-1β and IL-1Ra) and had lower glycolytic rates in comparison to monocytes isolated from matched controls. Stratification based on HbA1c levels revealed that a lower cytokine secretion was coupled to a higher glycolytic rate of monocytes in patients with a higher glycemic burden. Gene expression signatures of circulating monocytes displayed an enhanced inflammatory expression pattern that was associated with this high glycemic burden. A high glycemic burden in patients with T1D promotes expression of inflammatory genes of monocytes in vivo and is coupled to an impaired relationship between metabolism and inflammatory function upon activation ex vivo.

ORGANISM(S): Homo sapiens

PROVIDER: GSE154609 | GEO | 2020/10/09

REPOSITORIES: GEO

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Project description:Both genetic and environmental factors are implicated in Type 1 Diabetes (T1D). Since environmental factors can trigger epigenetic changes, we hypothesized that variations in histone posttranslational modifications (PTMs) at the promoter/enhancer regions of T1D susceptible genes may be associated with T1D. We therefore evaluated histone PTM variations at known T1D susceptible genes in blood cells from T1D patients versus healthy non-diabetic controls, and explored their connections to T1D. We used the chromatin-immunoprecipitation-linked-to-microarray approach to profile key histone PTMs, including H3-lysine-4 trimethylation (H3K4me3), H3K27me3, H3K9me3, H3K9 acetylation (H3K9Ac) and H4K16Ac at genes within the T1D susceptible loci in lymphocytes, and H3K4me3, H3K9me2, H3K9Ac and H4K16Ac at the IDDM1 region in monocytes of T1D patients and healthy controls separately. We screened for potential variations in histone PTMs using computational methods to compare datasets from T1D and controls. Interestingly, we observed marked variations in H3K9Ac levels at the upstream regions of HLA-DRB1 and HLA-DQB1 within the IDDM1 locus in T1D monocytes relative to controls. Additional experiments with THP-1 monocytes demonstrated increased expression of HLA-DRB1 and HLA-DQB1 in response to interferon- and TNF-treatment that were accompanied by changes in H3K9Ac at the same promoter regions as that seen in the patient monocytes. These results suggest that the H3K9Ac status of HLA-DRB1 and HLA-DQB1, two genes highly associated with T1D, may be relevant to their regulation and transcriptional response towards external stimuli. Thus, the promoter/enhancer architecture and chromatin status of key susceptible loci could be important determinants in their functional association to T1D susceptibility. We evaluated histone PTM variations at known T1D susceptible genes in blood cells from T1D patients versus healthy non-diabetic controls, and explored their connections to T1D. We used the ChIP-chip approach to profile key histone PTMs, including histone H3K4me3, H3K27me3, H3K9me3, H3K9 acetylation (H3K9Ac) and H4K16Ac, at genes within the T1D susceptible loci in lymphocytes.

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A high glycemic burden drives functional and metabolic alterations of human monocytes in patients with type 1 diabetes

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