Echocardiographic findings in acromegaly: prevalence of concentric left ventricular remodeling in a large single-center cohort

PURPOSE

Acromegaly is a rare disease and is associated with increased cardiovascular (CV) morbidity and mortality, especially in patients with uncontrolled disease. We aimed to analyze the prevalence and severity of cardiomyopathy and valvular heart disease in a large cohort of patients with a confirmed acromegaly diagnosis, at baseline and after treatment.

METHODS

We retrospectively reviewed an institutional approved database; 190 patients with confirmed acromegaly and follow-up data available (years 2006-2018). Patients with at least one baseline echocardiogram, were included. Demographic, disease control and echocardiogram variables were collected for analysis.

RESULTS

Of the 190 patients 110 (58%) had a baseline echocardiogram and 43 (39.1%) had at least one follow-up echocardiogram after surgical, medical or multimodal treatment. Baseline left ventricular hypertrophy (LVH) prevalence was 17.8% (64.7% concentric; 35.3% eccentric), diastolic and systolic dysfunction, and overt cardiomyopathy with heart failure were 15.8, 7.9, and 3.0%, respectively. Concentric remodeling of the left ventricle (LV) was noted in 31.4% of patients without LVH. Valve defects were found in 87.3% of patients (14.6% with significant valvular heart disease).

CONCLUSION

Early diagnosis of acromegaly and disease control should be attempted to prevent LVH/LV dysfunction and development of valvular heart disease. Concentric LV remodeling develops prior to obvious LV hypertrophy in almost a third of patients with acromegaly, which is a novel finding. Similar to other epidemiological studies, we found a high prevalence of LVH/LV dysfunction. Although possible, reversal of systolic and diastolic dysfunction is sporadic after treatment of acromegaly.

A209 ROLE OF SEROTONIN-AUTOPHAGY AXIS IN REGULATION OF EPITHELIAL CELL FUNCTION AND MICROBIOTA COMPOSITION IN GUT

Background

Serotonin (5-hydroxytryptamine; 5-HT), an enteric signalling molecule mainly produced by the enterochromaffin (EC) cells of the intestinal epithelium regulates various processes of the gut. Tryptophan hydroxylase 1 (Tph1) is the rate-limiting enzyme of 5-HT biosynthesis in EC cells. In inflammatory bowel disease (IBD) and experimental colitis, there are alterations in 5-HT content and microbiota composition in the gut. Previously we reported, Tph1-deficient (Tph1-/-) mice with reduced 5-HT in the gut exhibit reduced susceptibility to colitis. The mechanism by which 5-HT regulates colitis is unknown. Autophagy, a catabolic process regulates the function of intestinal epithelial cells (IECs), gut microbiota, and protects against intestinal inflammation. Both aberrant 5-HT signalling and autophagy is implicated in colitis. It is unclear whether they interact in regulation of production of pro-inflammatory cytokines from IECs and gut microbiota composition in relation to colitis. Our hypothesis is, an increase in 5-HT signalling inhibits autophagy in the IECs, which results in up-regulation of colitis by increasing the production of pro-inflammatory cytokines, and by selection for a more colitogenic microbiota.

Aims

To define the role of 5-HT-autophagy axis in the production of pro-inflammatory cytokines from IECs and gut microbiota composition in intestinal inflammation.

Methods

We investigated level of autophagy with or without 5% dextran sodium sulphate (DSS) in colons, mucosal scraping and IECs of Tph1-/- and their wild-type (WT) littermates. In addition, autophagy and proinflammatory cytokine production were investigated in human colonic epithelial cells (HT-29) following stimulation by 5-HT. We evaluated colitis and gut microbiota composition in WT, Tph1-/-, epithelial-specific autophagy gene Atg7 deficient (Atg7ΔIEC), and Atg7ΔIECTph1-/- (double knock out; DKO) mice.

Results

Tph1 -/- mice, with less 5-HT in the gut than WT mice following DSS administration exhibited an up-regulation of autophagy markers in the colon, mucosal scraping and IECs along with reduction of colitis severity. 5-HT treatment of HT-29 cells resulted in down-regulation of autophagy and upregulation of pro-inflammatory cytokine, IL-8. DKO mice exhibited increased severity of DSS-colitis, and altered microbiota composition compared to Tph1-/- mice.

Conclusions

These findings suggest, an increase in 5-HT in colitis inhibits autophagy in the IECs that contribute to alteration of the gut microbiota and disease severity. Blocking 5-HT signalling may promote autophagy in the IECs and alleviate the severity of colitis. Understanding the contribution of 5-HT in autophagy may identify new therapeutic target in IBD and other intestinal inflammatory conditions that exhibit dysregulated autophagy.

Funding Agencies

CAG, CIHR