Chlamydial infection and progression of carotid atherosclerosis in patients on regular haemodialysis

Abstract

Background: Recent findings have suggested a possible contribution of chlamydial infection to the pathogenesis of atherosclerosis in the general population. However, the role that chlamydial antibody status plays in atherosclerosis generation in haemodialysis (HD) patients remains uncertain.

Methods: We measured carotid artery intima medial thickness (IMT) over 4 years in 100 HD subjects (age: 58+/-10 years; time on HD: 13+/-7 years; male/female: 67/33) and examined potential associations between Chlamydia pneumoniae (Cp) antibody seropositivity and changes in carotid artery IMT.

Results: During 4 years, carotid artery IMT increased significantly from 0.62+/-0.13 to 0.73+/-0.12 mm (P< 0.01). IMT progression was significantly and positively correlated with age (r = 0.37, P<0.01), log-transformed C-reactive protein (CRP; r = 0.33, P<0.01) and log-transformed interleukin-6 (IL-6; r = 0.22, P<0.04), but inversely correlated with blood creatinine (r = -0.36, P<0.01) and albumin (r = -0.24, P<0.02). IMT increases were more prominent in patients positive for IgA antibodies (0.039+/- 0.022 mm/year, n = 52) compared with those without IgA antibodies (0.025+/-0.032 mm/year, n = 48) (P<0.01). IgA seropositivity did not accelerate IMT progression in patients with increased CRP (>0.11 mg/dl, n = 53), but significantly increased IMT to a greater extent in IgA-positive subjects than in IgA-negative subjects having lower CRP (</=0.11 mg/dl, n = 47) (0.017+/-0.024 vs 0.034+/- 0.021 mm/year; P = 0.01). Multivariate regression analysis revealed that serum creatinine, log-transformed CRP and IgA Cp seropositivity were independent risk factors for IMT progression (P<0.01). In contrast, IgG Cp antibody did not affect IMT progression or carotid plaque formation.

Conclusions: IMT progression is associated with inflammation and malnutrition. In addition, persistent chlamydial infection may be associated with IMT progression, but only in HD patients having low blood CRP.