Cytokines, interstitial collagen and ventricular remodelling in dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is associated with myocardial fibrosis, and proinflammatory cytokines may play a role in this.

N-terminal type I and III procollagen propeptides (PINP, PIIINP) and cross-linked telopeptide of type I collagen (ICTP) were measured from serum samples of 73 patients with DCM and 56 age and sex matched controls. Circulating cytokine levels were determined in DCM patients.

Serum levels of PINP and PIIINP were lower in patients than in controls (p<0.05 and p=0.001). In patients with DCM, the levels of PIIINP and ICTP correlated significantly with each other (p<0.01), and the proinflammatory cytokines, tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6), correlated positively with ICTP (p<0.001, p<0.05), PIIINP/PINP ratio (p<0.05, p<0.01) and left atrial size (p<0.01, p<0.05). Presence of atrial fibrillation was associated with lower serum PINP level and higher PIIINP/PINP ratio (p<0.05).

Our results suggest that interstitial myocardial collagen metabolism is altered in DCM patients and regulated by proinflammatory cytokines. These changes in collagen metabolism are associated with presence of atrial fibrillation, but do not reflect left ventricular remodelling. Treatment with beta-blockers and inhibitors of the renin angiotensin aldosterone system seem to effectively inhibit overall type I and III collagen syntheses.