Steve E Calvano — Page 2

PubMed2002

Insulin-like growth factor binding protein-3 is upregulated in LPS-treated THP-1 cells.

BACKGROUND: Lipopolysaccharide (LPS) is a potent activator of human monocytic cells. We have determined that LPS stimulation of the human monocytic cell line, THP-1, results in an increased apoptotic rate. We hypothesized that cDNA expression array analysis could be used to identify target genes involved in the regulation of this process. METHODS: THP-1 cells (1 x 10(6)/mL) were stimulated with LPS (1 microg/mL) or vehicle control. Apoptosis was measured at 0, 24, 48, 72 and 96 h using propidium iodide staining and flow cytometry to determine the percentage of cells with hypodiploid DNA. At 16 h, the Atlas Human cDNA expression array system, containing probes for 205 genes related to apoptosis, was used to survey and quantify transcript expression. The experiment was performed in duplicate and the membranes were normalized to cytoplasmic beta-actin. Standard Western blotting was performed on the conditioned medium to correlate secreted protein expression with RNA expression. Pretreatment with insulin-like growth factor I (IGF-I) was performed to determine whether the effects of insulin-like growth factor binding protein-3 (IGFBP-3) on apoptosis were IGF-dependent. RESULTS: LPS stimulation of THP-1 cells resulted in a greater than 2-fold increase in the rate of apoptosis when compared to vehicle control. When the cDNA expression arrays were compared, there was a 500-fold increase in the expression of the IGFBP-3 transcript in the LPS-stimulated cells. Western blotting of culture medium verified an approximately 2-fold increase in secreted IGFBP-3. Pretreatment with IGF-I did not prevent the increase in apoptosis seen with LPS stimulation. CONCLUSIONS: THP-1 cell apoptosis is increased in response to LPS stimulation and is associated with a significant induction of IGFBP-3 mRNA and protein. IGFBP-3, which reportedly promotes apoptosis and modulates the bioavailability of the pro-survival insulin-like growth factor 1, may serve to regulate apoptosis in monocytic cells in an IGF-independent manner. These data further support the investigation of the role of the IGF axis in programmed cell death of immune cells.

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PubMed2002

Alterations in immunocyte tumor necrosis factor receptor and apoptosis in patients with congestive heart failure.

OBJECTIVE: To examine systemic immune cell proinflammatory receptor expression and apoptosis in patients with congestive heart failure (CHF). SUMMARY BACKGROUND DATA: Prior studies have demonstrated that CHF is associated with a chronic myocardial inflammatory state, including increased plasma proinflammatory cytokine and soluble receptor expression. By contrast, it has also been shown that tumor necrosis factor (TNF) receptor protein expression is decreased in the failing myocardium. However, no studies to date have examined systemic immune cell proinflammatory receptor expression or function as disease markers in patients with heart failure. METHODS: Twenty-nine patients were studied prospectively over an 8-month period at a single institution. One group (n = 16) had a history of clinical symptoms of CHF and moderate to severe left ventricular dysfunction. The second group (n = 13) consisted of patients who had coronary artery disease without symptoms of CHF and documented preservation of left ventricular function. Blood samples were analyzed for polymorphonuclear cell (PMN) and monocyte TNF and CD95 membrane-associated receptor expression, spontaneous and CD95 (Fas)-mediated PMN apoptosis, and plasma cytokine and soluble TNF receptor levels. Isolated PMNs were incubated for 6 hours with or without CH 11, a CD95 agonist. Propidium iodide/RNAase staining and flow cytometry was used to assess apoptosis, defined as PMNs expressing hypodiploid DNA (<2 n DNA). Membrane-associated TNF receptor and CD95 were also measured by flow cytometry. Plasma levels of TNF, interleukin (IL)-6, IL-10, and soluble TNF receptors 1 and 2 were quantified using enzyme-linked immunosorbent assay. RESULTS: Compared to patients without CHF, circulating PMN and monocyte TNF receptor levels were significantly decreased in patients with CHF. By contrast, PMN and monocyte CD95 expression was not significantly changed in patients with CHF versus those without CHF. Patients with CHF had a 60% decrease in spontaneous PMN apoptosis compared to patients without CHF, whereas no significant difference in CD95-mediated apoptosis was observed between the two groups. Pearson-product movement correlation of monocyte TNF receptor expression and spontaneous PMN apoptosis rates versus patients' ejection fraction was performed and was statistically significant. Plasma levels of soluble TNF receptor 2 (p75) were elevated in CHF patients versus patients without CHF, while there was no significant difference in soluble TNF receptor 1 (p55), TNF, IL-6, and IL-10 between the two groups. CONCLUSIONS: These data demonstrate a systemic alteration in immune cell phenotype and apoptosis in patients with CHF. These findings provide support for the concept that inflammatory mediators either contribute to myocardial dysfunction or are elaborated systemically by left ventricular compromise. This present study suggests that immune cell TNF receptor expression and diminished PMN apoptosis may serve as biologic markers of myocardial failure.

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