Inactivation of the immune receptor CD40 attenuates the development of cardiac hypertrophy in angiotensin-II induced hypertensive heart disease

Emerging evidence indicates that inflammatory activation is a crucial pathway in disease progression during HF. The co-stimulatory dyad CD40-CD40L is involved in pro-inflammatory activation of a wide range of immune and non-immune cells and plasma levels of soluble CD40L in HF patients are raised. Here we investigated whether CD40-CD40L interactions attenuate cardiac hypertrophy in hypertensive heart disease. CD40 knockout and wild type C57Bl6-J mice were treated with angiotensin II (AngII, 2.5 mg/kg/day) for 4 weeks. AngII-induced hypertension led to a significant increase in cardiac mass in Wt mice (+31%, P<0.01), but not in CD40 knockout mice (+10%, N.S.). Comparable changes were observed in diastolic wall thickness (echocardiography) and cardiomyocyte cross sectional area. To determine which CD40-TRAF interactions were involved, the effect of mutations in the intracellular TRAF binding domains of CD40 was investigated. Relative to mice with intact downstream CD40 signaling, disruption of TRAF2/3/5, TRAF6 or both binding sites was associated with reduced cardiac hypertrophy (cardiac mass -24% for CD40-TΔ2, -28% for CD40-TΔ6 and -26% in CD40-TΔ2/6; p<0.05). Reduced hypertrophy was not associated with a decline in immune cell infiltration (CD45+ cells) or collagen content. Although the exact mechanism remains to be elucidated the present findings indicate a role for the CD40 receptor in the development of cardiac hypertrophy.