Israel Medical Association Journal

Background: Systemic CD11b+ cells have been associated with several cardiac diseases, such as chronic heart failure.

Objectives: To assess the levels of circulating CD11b+ cells and pro-inflammatory cytokines in cardiomyopathy induced by chronic adrenergic stimulation.

Methods: Male Lewis rats were injected with low doses of isoproterenol (isoprel) for 3 months. Cardiac parameters were tested by echocardiography. The percentage of CD11b+ cells was tested by flow cytometry. The levels of inflammatory cytokines in the sera were determined by an inflammation array, and the expression levels of cardiac interleukin-1 (IL-1) receptors were analyzed by real-time polymerase chain reactions. Cardiac fibrosis and inflammation were determined by histological analysis.

Results: Chronic isoprel administration resulted in increased heart rate, cardiac hypertrophy, elevated cardiac peri-vascular fibrosis, reduced fractional shortening, and increased heart weight per body weight ratio compared to control animals. This clinical presentation was associated with accumulation of CD11b+ cells in the spleen with no concomitant cardiac inflammation. Cardiac dysfunction was also associated with elevated sera levels of IL-1 alpha and over expression of cardiac IL-1 receptor type 2.

Conclusions: CD11b+ systemic levels and IL-1 signaling are associated with cardiomyopathy induced by chronic adrenergic stimulation. Further studies are needed to define the role of systemic immunomodulation in this cardiomyopathy.

 

Background: Advanced glycation end products, formed by the non-enzymatic glycation of proteins with reducing sugars, are thought to play a pathogenetic role in the vascular complications of diabetes, uremia and atherosclerosis. β2-microglobulin is a major constituent of amyloid fibrils in dialysis-related amyloidosis. AGE[1]-modified β2m[2] has been found in amyloid deposits of long-term hemodialysis patients. AGE-modified β2m has also been shown to enhance chemotaxis and increase tumor necrosis factor-alpha and interleukin-1 beta secretion by circulating and tissue monocytes/macrophages.

Objectives: To investigate the effect of AGE-modified β2m and AGE-human serum albumin on TNF-α[3] and IL-1β[4] secretion by human peritoneal macrophages derived from patients on continuous ambulatory peritoneal dialysis.

Methods: Human PMØ[5] were isolated from peritoneal dialysis effluent of stable CAPD[6] patients and were incubated for 24 hours with AGE-modified β2m, β2m, AGE-HSA[7], HSA or lipopolysaccharide. TNF-α or IL-1β secretion was measured by enzyme-linked immunosorbent assay in cell-free culture supernatants.

Results: Both AGE-modified β2m and AGE-HSA significantly increased TNF-α and IL-1β secretion by human PMØ in a dose-dependent manner (50–200 μg/ml). In contrast, β2m or HSA had no such stimulatory effect on TNF-α secretion but had a small significant increase in IL-1β secretion.

Conclusions: AGE-modified β2m promotes in vitro TNF-α and IL-1β secretion by human PMØ of CAPD patients. Activation of these macrophages by AGE-modified β2m may be a contributory factor to the morphologic changes and altered permeability of the peritoneal membrane in long-term CAPD.