Ryanodine Receptor Calcium Leak in Circulating B-Lymphocytes as a Biomarker in Heart Failure.

Abstract

BACKGROUND:

Advances in congestive heart failure (CHF) management depend on biomarkers for monitoring disease progression and therapeutic response. During systole, intracellular Ca2+ is released from the sarcoplasmic reticulum into the cytoplasm through type-2 ryanodine receptor/Ca2+ release channels. In CHF, chronically elevated circulating catecholamine levels cause pathological remodeling of type-2 ryanodine receptor/Ca2+ release channels resulting in diastolic sarcoplasmic reticulum Ca2+ leak and decreased myocardial contractility. Similarly, skeletal muscle contraction requires sarcoplasmic reticulum Ca2+ release through type-1 ryanodine receptors (RyR1), and chronically elevated catecholamine levels in CHF cause RyR1-mediated sarcoplasmic reticulum Ca2+ leak, contributing to myopathy and weakness. Circulating B-lymphocytes express RyR1 and catecholamine-responsive signaling cascades, making them a potential surrogate for defects in intracellular Ca2+ handling because of leaky RyR channels in CHF.

METHODS:

Whole blood was collected from patients with CHF, CHF following left-ventricular assist device implant, and controls. Blood was also collected from mice with ischemic CHF, ischemic CHF+S107 (a drug that specifically reduces RyR channel Ca2+ leak), and wild-type controls. Channel macromolecular complex was assessed by immunostaining RyR1 immunoprecipitated from lymphocyte-enriched preparations. RyR1 Ca2+ leak was assessed using flow cytometry to measure Ca2+ fluorescence in B-lymphocytes in the absence and presence of RyR1 agonists that empty RyR1 Ca2+ stores within the endoplasmic reticulum.

RESULTS:

Circulating B-lymphocytes from humans and mice with CHF exhibited remodeled RyR1 and decreased endoplasmic reticulum Ca2+ stores, consistent with chronic intracellular Ca2+ leak. This Ca2+ leak correlated with circulating catecholamine levels. The intracellular Ca2+ leak was significantly reduced in mice treated with the Rycal S107. Patients with CHF treated with left-ventricular assist devices exhibited a heterogeneous response.

CONCLUSIONS:

In CHF, B-lymphocytes exhibit remodeled leaky RyR1 channels and decreased endoplasmic reticulum Ca2+ stores consistent with chronic intracellular Ca2+ leak. RyR1-mediated Ca2+ leak in B-lymphocytes assessed using flow cytometry provides a surrogate measure of intracellular Ca2+ handling and systemic sympathetic burden, presenting a novel biomarker for monitoring response to pharmacological and mechanical CHF therapy.

• Authors: Alexander Kushnir, Gaetano Santulli, Steven R Reiken, Ellie Coromilas, Sarah J Godfrey, Danielle L Brunjes, Paolo C Colombo, Melana Yuzefpolskaya, Seth I Sokol, Richard N Kitsis, Andrew R Marks
• Journal: Circulation (Circulation) Vol. 138 Issue 11 Pg. 1144-1154 (09 11 2018) ISSN: 1524-4539 [Electronic] United States
• PMID: 29593014 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• RYR1 protein, human
• Ryanodine Receptor Calcium Release Channel
• S-107 compound
• Thiazepines
• ryanodine receptor 1, mouse
• Calcium
• Norepinephrine

Topics

• Aged
• Animals
• B-Lymphocytes (drug effects, metabolism)
• Calcium (blood)
• Calcium Signaling (drug effects)
• Case-Control Studies
• Disease Models, Animal
• Endoplasmic Reticulum (drug effects, metabolism)
• Female
• Heart Failure (blood, physiopathology, therapy)
• Heart-Assist Devices
• Humans
• Male
• Mice, Inbred C57BL
• Middle Aged
• Norepinephrine (blood)
• Ryanodine Receptor Calcium Release Channel (blood, drug effects)
• Thiazepines (pharmacology)
• Ventricular Function, Left