Thomas S. Parker

Tumor Necrosis Factor-α Mediates Cardiac Remodeling and Ventricular Dysfunction After Pressure Overload State

Background— Pressure overload is accompanied by cardiac myocyte apoptosis, hypertrophy, and inflammatory/fibrogenic responses that lead to ventricular remodeling and heart failure. Despite incomplete understanding of how this process is regulated, the upregulation of tumor necrosis factor (TNF)-&agr; after aortic banding in the myocardium is known. In the present study, we tested our hypothesis that TNF-&agr; regulates the cardiac inflammatory response, extracellular matrix homeostasis, and ventricular hypertrophy in response to mechanical overload and contributes to ventricular dysfunction. Methods and Results— C57/BL wild-type mice and TNF-knockout (TNF−/−) mice underwent descending aortic banding or sham operation. Compared with sham-operated mice, wild-type mice with aortic banding showed a significant increase in cardiac TNF-&agr; levels, which coincided with myocyte apoptosis, inflammatory response, and cardiac hypertrophy in week 2 and a significant elevation in matrix metalloproteinase-9 activity and impaired cardiac function in weeks 2 and 6. Compared with wild-type mice with aortic banding, TNF−/− mice with aortic banding showed attenuated cardiac apoptosis, hypertrophy, inflammatory response, and reparative fibrosis. These mice also showed reduced cardiac matrix metalloproteinase-9 activity and improved cardiac function. Conclusions— Findings from the present study have suggested that TNF-&agr; contributes to adverse left ventricular remodeling during pressure overload through regulation of cardiac repair and remodeling, leading to ventricular dysfunction.

Low lipid concentrations in critical illness : Implications for preventing and treating endotoxemia

OBJECTIVES To determine the prevalence and clinical significance of hypolipidemia found in critically ill patients, and whether the addition of a reconstituted lipoprotein preparation could inhibit the generation of tumor necrosis factor-alpha (TNF-alpha) in acute-phase blood taken from these patients. SETTING Surgical intensive care unit (ICU) of a large urban university hospital. DESIGN Prospective case series. PATIENTS A total of 32 patients with a variety of critical illnesses had lipid and lipoprotein concentrations determined. Six patients and six age- and gender-matched control subjects had whole blood in vitro studies of the effect of lipoprotein on lipopolysaccharide mediated TNF-alpha production. INTERVENTIONS Blood samples were drawn on admission to the ICU and over a subsequent 8-day period. MEASUREMENTS AND MAIN RESULTS Mean serum lipid and lipoprotein values obtained from patients within 24 hrs of transfer to the surgical ICU were extremely low: mean total cholesterol was 117 mg/dL (3.03 mmol/L), low-density lipoprotein cholesterol 71 mg/dL (1.84 mmol/L), and high-density lipoprotein cholesterol 25 mg/dL (0.65 mmol/L). Only the mean triglyceride concentration of 105 mg/dL (1.19 mmol/L), and the mean lipoprotein(a) concentration of 25 mg/dL (0.25 g/L) were within the normal range. During the first 8 days following surgical ICU admission, there were trends toward increasing lipid and lipoprotein concentrations that were significant for triglycerides and apolipoprotein B. Survival did not correlate with the lipid or lipoprotein concentrations, but patients with infections had significantly lower (p = .008) high-density lipoprotein cholesterol concentrations compared with noninfected patients. Lipopolysaccharide-stimulated production of TNF-alpha in patient and control blood samples was completely suppressed by the addition of 2 mg/mL of a reconstituted high-density lipoprotein preparation. CONCLUSIONS Patients who are critically ill from a variety of causes have extremely low cholesterol and lipoprotein concentrations. Correction of the hypolipidemia by a reconstituted high-density lipoprotein preparation offers a new strategy for the prevention and treatment of endotoxemia.

Relationship of hypolipidemia to cytokine concentrations and outcomes in critically ill surgical patients.

ObjectiveTo determine the relationship of hypolipidemia to cytokine concentrations and clinical outcomes in critically ill surgical patients. DesignConsecutive, prospective case series. SettingSurgical intensive care unit of an urban university hospital. PatientsSubjects were 111 patients with a variety of critical illnesses, for whom serum lipid, lipoprotein, and cytokine concentrations were determined within 24 hrs of admission to a surgical intensive care unit. Controls were 32 healthy men and women for whom serum lipid, lipoprotein, and cytokine concentrations were determined. InterventionsBlood samples were drawn on admission to the intensive care unit. Predetermined clinical outcomes including death, infection subsequent to intensive care unit admission, length of intensive care unit stay, and magnitude of organ dysfunction were monitored prospectively. Measurements and Main Results Measurements included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, apolipoproteins A-I and B, phospholipid, triglyceride, interleukin-6, interleukin-10, soluble interleukin-2 receptor, tumor necrosis factor-&agr;, and soluble tumor necrosis factor receptors p55 and p75. Mean serum lipid concentrations were extremely low: total cholesterol, 127 ± 52 mg/dL; low-density lipoprotein cholesterol, 75 ± 41 mg/dL; high-density lipoprotein cholesterol, 29 ± 15 mg/dL. Total, low-density lipoprotein, and high-density lipoprotein cholesterol concentrations and apolipoprotein concentrations inversely correlated with interleukin-6, soluble interleukin-2 receptor, and interleukin-10 concentrations, whereas the triglyceride concentration correlated positively with tumor necrosis factor soluble receptors p55 and p75. Clinical outcomes were related to whether the admission cholesterol concentration was above (n = 56) or below (n = 55) the median concentration of 120 mg/dL. Each of the clinical end points occurred between 1.9- and 3.5-fold more frequently in the very low cholesterol (<120 mg/dL) group. Nine patients (8%) died during the hospitalization. Seven of the nine patients who died had total cholesterol concentrations below the median concentration of 120 mg/dL. ConclusionsLow cholesterol and lipoprotein concentrations found in critically ill surgical patients correlate with interleukin-6, soluble interleukin-2 receptor, and interleukin-10 concentrations and predict clinical outcomes.

Plasmin catalyzes binding of lipoprotein (a) to immobilized fibrinogen and fibrin

Lipoprotein (a) [Lp(a)] is a plasma component whose concentration is related to the development of atherosclerosis, although the underlying mechanisms are not known. Lp(a) contains a unique structure, apolipoprotein (a), that shares partial homology with plasminogen. We now report that plasmin catalyzes the binding of Lp(a) to both immobilized fibrinogen and fibrin in a manner analogous to our previously reported studies with plasminogen. Plasmin treatment of immobilized fibrinogen induces a 3.7-fold increase in Lp(a) binding. Low density lipoprotein, molecules similar to Lp(a) but lacking apolipoprotein (a), bind poorly to immobilized fibrinogen and binding is not increased by plasmin. Trypsin but not neutrophil elastase also increases the binding of Lp(a) to fibrinogen. Lp(a) also complexes to plasmin-fibrinogen digests, and binding increases in proportion to the time of plasmin-induced fibrinogen degradation. Lp(a) binding is lysine-binding site dependent as it is inhibited by epsilon-aminocaproic acid. Lp(a) inhibits the binding of plasminogen to plasmin-modified immobilized fibrinogen, indicating that both molecules compete for similar lysine-binding sites. These findings demonstrate an affinity between Lp(a) and protease-modified fibrinogen or fibrin and thereby provide a potential mechanism to explain the association between thrombosis, coronary atherosclerosis, and increased blood concentrations of Lp(a).

The Relationships of Hypocholesterolemia to Cytokine Concentrations and Mortality in Critically Ill Patients with Systemic Inflammatory Response Syndrome

BACKGROUND Decreased concentrations of total cholesterol, lipoproteins, and lipoprotein cholesterols occur early in the course of critical illness. Low cholesterol concentrations correlate with high concentrations of cytokines such as interleukin (IL)-6 and IL-10, and may be due to decreased synthesis or increased catabolism of cholesterol. Low cholesterol concentrations have been associated clinically with several adverse outcomes, including the development of nosocomial infections. The study was performed to test the hypothesis that a low cholesterol concentration predicts mortality and secondarily predicts the development of organ dysfunction in critical surgical illness. METHODS A prospective study was undertaken of 215 patients admitted to a university surgical ICU with systemic inflammatory response syndrome (SIRS). Serial blood samples were collected within 24 h of admission, as well as on the morning of days 2, 4, and 7 of the ICU stay for as long as the patients were in the ICU. Demographic data and predetermined outcomes were noted. RESULTS One hundred nine patients had at least two samples drawn and form the population for analysis. Sixty-two of the patients had three samples obtained, whereas 42 patients had four samples obtained. By univariate analysis, non-survivors were more severely ill on admission (APACHE III), more likely to have been admitted to the ICU as an emergency, more likely to develop a nosocomial infection, and more likely to develop severe organ dysfunction (MODS) (all, p < 0.05). Death was associated on day 1 with increased concentrations of sIL2R, IL-6, IL-10, and sTNFR-p75 (all, p < 0.01), but there were initially no differences in serum lipid concentrations. However, by day 2, concentrations of IL-6, IL-10, and cholesterol had decreased significantly (all, p < 0.05) from day 1 in non-survivors but not in survivors; the difference in serum cholesterol concentration persisted to day 7 (p < 0.05). Persistently elevated concentrations of IL-6 and IL-10 were observed in patients who developed severe MODS. By logistic regression, increased APACHE III score, development of a nosocomial infection, and decreased cholesterol concentration were independently associated with mortality. CONCLUSIONS Decreased serum cholesterol concentration is an independent predictor of mortality in critically ill surgical patients. Repletion of serum lipids is a feasible therapeutic approach for the management of critical illness.

Three-Dimensional Culture of Mouse Renal Carcinoma Cells in Agarose Macrobeads Selects for a Subpopulation of Cells with Cancer Stem Cell or Cancer Progenitor Properties

The culture of tumor cell lines in three-dimensional scaffolds is considered to more closely replicate the in vivo tumor microenvironment than the standard method of two-dimensional cell culture. We hypothesized that our method of encapsulating and maintaining viable and functional pancreatic islets in agarose-agarose macrobeads (diameter 6-8 mm) might provide a novel method for the culture of tumor cell lines. In this report we describe and characterize tumor colonies that form within macrobeads seeded with mouse renal adenocarcinoma cells. Approximately 1% of seeded tumor cells survive in the macrobead and over several months form discrete elliptical colonies appearing as tumor cell niches with increasing metabolic activity in parallel to colony size. The tumor colonies demonstrate ongoing cell turnover as shown by BrdU incorporation and activated caspase-3 and TUNEL staining. Genes upregulated in the tumor colonies of the macrobead are likely adaptations to this novel environment, as well as an amplification of G(1)/S cell-cycle checkpoints. The data presented, including SCA-1 and Oct4 positivity and the upregulation of stem cell-like genes such as those associated with the Wnt pathway, support the notion that the macrobead selects for a subpopulation of cells with cancer stem cell or cancer progenitor properties.

Neutralization of Endotoxin by a Phospholipid Emulsion in Healthy Volunteers

BACKGROUND An approach to endotoxin (lipopolysaccharide [LPS]) blockade makes use of the ability of lipoproteins, via surface phospholipids, to bind and neutralize LPS. The aim of the present study was to determine whether the intravenous administration of a protein-free, phospholipid-rich emulsion is an effective method for neutralizing the effects of LPS in healthy persons. METHODS This was a double-blind, placebo-controlled study in 20 volunteers. Volunteers received Escherichia coli endotoxin (2 ng/kg) intravenously 2 h into a 6-h infusion of either emulsion (210 mg/kg) or placebo (Intralipid diluted 1 : 64). RESULTS The volunteers who received emulsion had a lower mean clinical score (P<.01), temperature (P<.05), pulse rate (P<.05), neutrophil count (P<.05), tumor necrosis factor- alpha level (P<.05), and interleukin-6 level (P<.05) than did the volunteers who received placebo. Response was related to serum phospholipid level. The greatest effects were observed in the volunteers achieving phospholipid levels of approximately 500 mg/dL or higher. CONCLUSION Phospholipid emulsion attenuates the clinical and laboratory effects associated with the administration of LPS in humans, suggesting a novel approach to the treatment of endotoxemia.

Deceased-donor kidney transplantation: improvement in long-term survival

BACKGROUND Despite marked improvement in short-term renal allograft survival rates (GSR) in recent years, improvement in long-term GSR remained elusive. METHODS We analysed the kidney transplant experience at our centre accrued over four decades to evaluate how short-term and long-term GSR had changed and to identify risk factors affecting graft survival. The study included 1476 adult recipients of a deceased-donor kidney transplant who were transplanted between 1963 and 2006 and who had received one of five distinct immunosuppressive protocols. RESULTS Five-year actual GSR steadily improved over the years as immunosuppressive therapy evolved (22-86%, P < 0.001) in spite of an increasing trend in the transplantation of higher-risk donor-recipient pairings. For those whose grafts functioned for the first year, subsequent 4-year GSR (5-year conditional GSR) also improved significantly (63-92%, P < 0.001). Acute rejection and delayed graft function (DGF) were the most significant risk factors for actual graft survival, while acute rejection was the only significant risk factor for conditional GSR. Use of kidneys from expanded-criteria donors (ECD) was not a risk factor, compared to the use of standard-criteria donor kidneys for either 5-year actual or conditional GSR. There was an impressive decline in the incidence of acute rejection events (77.4-5.8%, P < 0.001). While the DGF rate had decreased, it still remained high (68.7-38.5%, P < 0.001). CONCLUSIONS We found a significant improvement in both short-term and long-term GSR of deceased-donor kidney transplants over the last four decades. These improvements are most likely related to the decreased incidence of acute rejection episodes. Minimizing acute rejection events and preventing DGF could result in further improvement in the GSR. Our experience in the judicious use of ECD kidneys suggests that this source of kidneys could be expanded further.

Evaluation of 2 immunoassays for monitoring low blood levels of tacrolimus.

The objective of this study was to evaluate the analytical performance of 2 new tacrolimus immunoassays (Dade Dimension Xpand and Abbott ARCHITECT) for therapeutic drug monitoring as possible replacements for the current method in our laboratory, the Abbott IMx tacrolimus assay. Attending physicians at our institute desire to minimize calcineurin inhibitor therapy in kidney allograft recipients to prolong graft survival and improve the quality of life of their patients. Proposed future target trough levels of tacrolimus in whole blood are in the range of 2-4 ng/mL, which requires an assay with a limit of quantification (LOQ) below this range, ideally around 1 ng/mL (European Consensus Recommendation from the Committee on Tacrolimus Optimization). Method comparison analysis of the Dade and ARCHITECT assays showed good correlation to the IMx assay, with correlation coefficients of 0.94 and 0.96, respectively. Both assays reported tacrolimus concentrations lower on average than IMx as demonstrated by slopes of 0.83 (Dade) and 0.93 (ARCHITECT). LOQ for both Dade instruments tested was >4 ng/mL, whereas the LOQ for the ARCHITECT i2000 and i1000 instruments was 0.8 and 0.5 ng/mL, respectively (upper 95% confidence limit). Values reported from both Dade instruments were observed to shift over time, whereas the values on the IMx and ARCHITECT instruments were stable. The Abbott ARCHITECT Tacrolimus assay is a sensitive and precise assay that meets the new LOQ recommendation, 1 ng/mL, for monitoring tacrolimus in whole blood.

Cholesterol and Interkeukin-6 Concentrations Relate to Outcomes in Burn-Injured Patients

The goal of this study was to determine the relationship among lipid concentrations, cytokine concentrations, and clinical outcomes of burn patients. Twenty-eight patients admitted within 24 hours of burn injury, segregated based on burn size, had blood samples drawn 24 and 48 hours after burn injury and then weekly for 3 weeks. Measurements included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglyceride, interleukin (IL)-6, soluble IL-2 receptor, and soluble necrosis factor p55 and p75 receptors. Infection, length of stay (LOS), and survival were monitored. Cholesterol and lipoprotein concentrations decreased by at least 40% in patients with burns >20% total body surface area and inversely correlated with IL-6. Lower cholesterol and higher IL-6 values correlated with higher infection rates and longer LOS. IL-6 was the strongest predictor for LOS. In conclusion, outcomes after burn injury are related to low cholesterol and elevated IL-6 levels.