Gender-Dependent Alteration of Ca2+ and TNFα Signaling in db/ db Mice, an Obesity-Linked Type 2 Diabetic Model

Carmen Delgado; Ana-Maria Gomez; Magali Samia El Hayek; Gema Ruiz-Hurtado; Laetitia Pereira

doi:10.3389/fphys.2019.00040

Gender-Dependent Alteration of Ca²⁺ and TNFα Signaling in db/ db Mice, an Obesity-Linked Type 2 Diabetic Model

Front Physiol. 2019 Feb 7:10:40. doi: 10.3389/fphys.2019.00040. eCollection 2019.

Authors

Carmen Delgado¹, Ana-Maria Gomez², Magali Samia El Hayek², Gema Ruiz-Hurtado³, Laetitia Pereira²

Affiliations

¹ Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM)/CIBER-CV, Madrid, Spain.
² INSERM UMR-S 1180, University of Paris-Sud, University of Paris-Saclay, Châtenay-Malabry, France.
³ Cardiorenal Translational Laboratory, Institute of Research i+12, Hospital Universitario 12 de Octubre/CIBER-CV, Madrid, Spain.

Abstract

Cardiovascular complications are the primary death cause in type 2 diabetes, where inflammation can play a role. We, and others, have previously shown that, in diabetic cardiomyopathy, cardiac dysfunction is associated with Ca²⁺ mishandling. It is possible that diabetic cardiomyopathy differently affects men and women, as the latter present higher risk to develop heart failure and a higher plasmatic level of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNFα), than men. However, the gender-dependent regulation of Ca²⁺ signaling in diabetes and its relationship with TNFα signaling are still unclear. Here, we analyzed TNFα signaling pathway and its role in Ca²⁺ signaling dysfunction in male and female rodent models of type 2 diabetes linked to obesity (db/db mice) using confocal microscopy in freshly isolated cardiomyocytes. TNFα increased [Ca²⁺]_i transient amplitude and accelerated its decay without affecting SR Ca²⁺ load or Ca²⁺ spark frequency in cells from control mice. All TNFα effects on Ca²⁺ handling were prevented by the inhibition of the ceramidase and the phospholipase A2 (PLA2). While the plasmatic level of TNFα was similar in male and female db/db mice, only male db/db hearts over-expressed both TNFα converting enzyme (TACE) and the protective TNFα receptors 2 (TNF-R2). TNFα receptor 1 (TNF-R1) expression, involved in negative inotropic response of TNFα, was unchanged in both male and female db/db mice compared to controls. We found that male db/db mice cardiomyocytes presented a decrease in [Ca²⁺]_i transient amplitude associated to a drop of sarcoplasmic reticulum Ca²⁺ load, not seen in female db/db mice. Interestingly, sustained incubation with TNFα did not restored Ca²⁺ signaling alteration observed in male db/db mice but still induces an increase in Ca²⁺ spark frequency as seen in control littermates. In cardiomyocytes from female db/db mice, TNFα had no visible effects on Ca²⁺ handling. In conclusion, our study shows that the alteration of Ca²⁺ signaling and TNFα, seen in db/db mice, is gender specific presenting an increase in TNFα cardio-protective pathway in male mice.

Keywords: TNFα; calcium; db/db mice; diabetic cardiomyopathy; gender difference.