Glucocorticoid-induced Fingerprints on Visceral Adipose Tissue Transcriptome and Epigenome

Abstract

Context & Objective Chronic glucocorticoid (GC) overexposure, resulting from endogenous Cushing’s syndrome (CS) or exogenous GC therapy, causes several adverse outcomes, including persistent central fat accumulation associated with a low-grade inflammation. However, no previous multi-omics studies in visceral adipose tissue (VAT) from patients exposed to high levels of unsuppressed GC during active CS or after remission are available yet. Methods We employed a translational approach combining high-throughput data on endogenous CS patients and a reversible CS mouse model. We performed RNA-seq and ChIP-seq on histone modifications (H3K4me3, H3K27ac and H3K27me3) to identify persistent transcriptional and epigenetic signatures in VAT produced during active CS and maintained after remission. Results VAT dysfunction was associated with low-grade pro-inflammatory status, macrophage infiltration and extracellular matrix remodeling. Most notably, chronic hypercortisolism caused a persistent circadian rhythm disruption in VAT through core clock genes modulation. Importantly, changes in the levels of two histone modifications associated to gene transcriptional activation (H3K4me3 and H3K27ac) correlated with the observed differences in gene expression during active CS and after CS remission. Conclusion We identified for the first time, the persistent transcriptional and epigenetic signatures induced by hypercortisolism in VAT, providing a novel integrated view of molecular components driving the long-term VAT impairment associated with CS.

A unique gene expression signature in visceral adipose tissue identifies a high blood pressure group in patients with Cushing’s syndrome

“…Management of patients with CS and the thereof caused long-term complications are still a major challenge today [28, 47]. VAT taken as part of the adrenalectomy shows significant alterations in the transcriptome ( Figure 1 ) compared to non-CS patients, as previously reported [41, 48]. Consistent with previous studies, our study highlights the profound effects of chronic cortisol excess on adipose tissue gene expression.…”

“…In contrast to other studies, we did not observe a low-grade inflammation but rather a suppression of inflammatory and increased expression of antiinflammatory markers of macrophages and inflammation. The most common observation for inflammatory effects in the VAT of CS patients has been an increase in Cd11c (ITGAX) a marker for an increased proinflammatory state, which we did not observe in our patient cohort [41,52]. In our study we did, however, see a strong downregulation of inflammatory cytokines like Il6 (IL6) and Cxcl3 (CXCL3) as well as a downregulation of the inflammatory NFKB pathway and MAPK pathways.…”

“…To investigate the potential regulators of these DEG, we performed an epigenetic landscape in silico deletion analysis (LISA) [35]. Here we found that the most likely transcription factors regulating the DEGs were not the suspected cortisol activated transcription factors GR (NR3C1) or MR (NR3C2), but rather EGR3, TERC, CTCF, and the ESR1 (estrogen receptor), in line with previously published data sets (Figure S1B) [41].…”

“…In our follow-up visits 6 months after adrenalectomy due to adrenal CS, a difference in blood pressure was still found between CS subgroups CS High and CS Low , which may suggest an association of VAT RAS modulation and the persistence of glucocorticoid-induced hypertension. This could be either of epigenetic nature, as it has been previously reported that CS patients also show a changed epigenetic landscape or genetic nature exacerbated by the excess cortisol [41]. Here it was shown that markers for epigenetic gene activation (H3K27ac) and gene repression (H3K4me3) were altered during active CS.…”

Unique Gene Expression Signature in Periadrenal Adipose Tissue Identifies a High Blood Pressure Group in Patients With Cushing Syndrome

“…45 Here we found that the most likely transcription factors regulating the DEGs were not the suspected cortisol activated transcription factors GR (NR3C1) or MR (NR3C2), but rather EGR3 (Early Growth Response 3), TERC (Telomerase RNA Component), CTCF (CCCTC-Binding Factor), and the ESR1 (Estrogen Receptor), in line with previously published data sets (Figure S1B). 46 To further dissect the effects of active CS on adipose tissue. we performed an in silico cytometry approach (Cibersortx), to estimate the putative changes in cell populations.…”