Richard A. Winchurch

Inhibition of apoptosis in polymorphonuclear neutrophils from burn patients.

Normal human polymorphonuclear neutrophils (PMN) undergo rapid apoptosis during in vitro culture. In contrast, apoptosis is inhibited in PMN from patients with severe burns. This inhibition is not an inherent property of the cells but is caused by thermolabile factors present in the plasma. Endotoxin and the proinflammatory cytokines interleukin‐1 (IL‐1), interleukin‐6 (IL‐6), and tumor necrosis factor‐alpha (TNF‐α) do not appear to be directly responsible. The ability of burn plasma to inhibit apoptosis was reduced by neutralizing antibodies to human granulocyte macrophage colony‐stimulating factor (GM‐CSF). GM‐CSF levels could not be detected in the burn plasma. However, the incubation of burn‐derived or normal leukocyte populations consisting primarily of PMN in burn plasma induced the production of GM‐CSF. The results suggest that activation of GM‐CSF synthesis by factor(s) in burn plasma may play a role in regulating inflammation by the inhibition of apoptosis.

HIV infection and aging: mechanisms to explain the accelerated rate of progression in the older patient.

Age is an important predictor of progression in HIV infections. Not only do older individuals develop AIDS more rapidly than younger persons, they die more quickly after developing an AIDS-defining illness. While the elderly have higher morbidity and mortality rates from viral and bacterial infections, the mechanism(s) responsible for the more rapid progression of HIV infection in older individuals has not been described. Our results demonstrate that the destruction of T cells in both young and old HIV infected patients progresses at the same rate. HIV 1-infected cells from older individuals do not appear more susceptible to immune mediated destruction. The more rapid progression appears due to an inability of older persons to replace functional T cells that are being destroyed. These findings suggest that improved survival in older HIV infected individuals will require more aggressive antiretroviral therapies as well as continued research to identify and preserve immune system elements that control the virus.

Translocation: Incidental phenomenon or true pathology?

OBJECTIVEnThis study was conducted to determine if reduction of early postburn endotoxemia influences the cytokine cascade, clinical manifestations of sepsis, and mortality rate.nnnSUMMARY BACKGROUND DATAnTranslocational endotoxemia has been demonstrated postburn in animals and humans. Endotoxin is known to induce the cytokine cascade, which leads to the clinical manifestations of sepsis. Whether reduction of postburn endotoxemia could influence the induction of cytokines has not been demonstrated.nnnMETHODSnIn a prospective, randomized study, 76 burn patients were given polymyxin intravenously or served as control subjects. Polymyxin B was given intravenously for 1 week postburn in doses designed to neutralize circulating endotoxemia.nnnRESULTSnIn the polymyxin group, there was a statistically significant reduction in the plasma endotoxin concentration. There was, however, no reduction in the sepsis score or the interleukin-6 levels, and no differences in mortality rates were seen between the two groups.nnnCONCLUSIONSnEarly postburn translocational endotoxemia can be treated with anti-endotoxin agents such as polymyxin B. This, however, does not influence the cytokine cascade or the mortality rate. The systemic inflammatory response syndrome is caused by cytokine induction from the injury and is unaffected by a reduction in the plasma endotoxin concentration.

Effect of anesthesia and surgery on plasma cytokine levels

Cytokines released in response to stress may have a profound impact on circulatory stability. There is no information on the effect of general anesthesia alone on plasma cytokine levels and little information on cytokine release following surgery. Plasma cytokine levels and hemodynamic parameters were measured during anesthesia and abdominal surgery under sterile and nonpyrogenic conditions in seven pigs anesthetized with ketamine and pentobarbital. Tumor necrosis factor (TNF) was measured by bioassay. Bioassays of low and high sensitivity were used to measure interleukin 6 (IL-6). Measurements were made sequentially during: (1) 4 hours observation with anesthesia alone; (2) 2 hours following laparotomy and traumatic intestinal manipulation (IM) sufficient to produce shock; and (3) after an intravenous bolus of 1 microgram/kg endotoxin as a positive control. Arterial blood pressure decreased following IM from 91.5 +/- 5.8 to 48.6 +/- 3.2 mm Hg, (mean +/- SE, P < .05), with no further change following endotoxin. Heart rate was unchanged during the experiment, and central venous pressure decreased after endotoxin (P < .05). There were no increases in TNF or IL-6 (using a low sensitivity assay) with anesthesia alone or following IM with shock, but both increased after endotoxin administration (P < .05); using a high sensitivity assay, IL-6 did not change during anesthesia alone but did increase fivefold following IM with shock (P < .05) and 50-fold following endotoxin administration (P < .05). We conclude that in a porcine model under sterile and nonpyrogenic conditions, prolonged anesthesia does not increase plasma cytokine levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased production of TGF-beta and Il-6 by aged spleen cells

Aging is accompanied by a progressive decline in immunity in every species that has been studied. Despite its ubiquity, the causes of immunosenescence are unknown. Transforming growth factor beta (TGF-beta) is a cytokine with potent immunosuppressive properties. Cells from aged mice produce increased levels of TGF-beta in vitro along with similar increases in interleukin 6 (Il-6), a cytokine which is immunosuppressive at elevated concentrations. Il-6 does not upregulate TGF-beta production, but high concentrations of Il-6 increase the percentage of cells expressing the TGF-beta receptor. Increased TGF-beta production and Il-6-induced upregulation of the TGF-beta receptor may be factors contributing to age-associated immunosuppression.

Reversal of Postburn Immunosuppression with Low-dose Polymyxin B

In a randomized study of 28 patients with thermal injury, polymyxin B was administered intravenously in small doses to attempt to block the immunosuppressive effects of endotoxin. When compared with controls, treated patients showed a reduction in septic complications and death, but this reduction is not statistically significant at this time. In vitro measurements of lymphocyte function, however, indicate a statistically significant improvement in the T helper to suppressor ratio, and in the lymphocyte responsiveness to a number of bacterial antigens.

The "in vitro skin test": a reliable and repeatable assay of immune competence in the surgical patient.

In vitroblast transformation of human peripheral lymphocytes was tested using standard skin test antigens, the mitogens PHA and Con A, and the mixed lymphocyte reaction. The study group included 15 patients with multiple trauma, 40 with major burns, six following cholecystectomies, six following aortic reconstruction, and 30 normal volunteer controls. Repeated skin testing may sensitive patients to candida and streptokinase-streptodornase (SKSD), and desensitize them to mumps antigen. Blast transformation in response to PPD did not correlate with the clinical status of the patients; similarly, blast transformation in response to stimulation by the mitogens PHA and Con A could not reliably predict the occurrence of septic complications. Reactivity in response to stimulation by the soluble antigens SKSD and mumps and in the one-way mixed lymphocyte reaction accurately predicted the clinical course of patients. This method of‘vitro skin testing“ is a reliable and repeatable method of monitoring the immunologic status of patients whose illness or injury requires longitudinal study

Regulation of Acute Phase Gene Expression Following Surgery and Endotoxin Administration in the Anesthetized Pig

BackgroundThe hepatic acute phase response (APR) reflects an organisms integrated response to stress. This APR results in augmented synthesis and secretion of specific procoagulants and antiproteases and a complementary decrease in the synthesis and secretion of several constitutive proteins, such as albumin. The cytokines tumor necrosis factor (TNF) or inter-leukin-6 (IL-6) have been identified as proximal mediators of the APR in response to endotoxin stress. The authors hypothesized that TNF, IL-6, or both would be the proximal mediators of the APR in response to anesthesia and surgical stress. MethodsThe effects of a standardized surgical stress on the APR in pigs under general anesthesia with sodium pentobarbital and ketamine hydrochloride was investigated. Acute phase gene transcription was assayed in nuclei from serial liver biopsies obtained before and after 2.5 h of surgical stress, and after endotoxin administration. Tumor necrosis factor and IL-6 mRNA levels in this liver tissue were examined by Northern blot hybridization, and simultaneous plasma levels of these cytokines were measured using bioassays. ResultsThe transcription rates of three positive acute phase genes—chymotrypsin inhibitor, inter-α-trypsin inhibitor and β-fibrinogen—increased seven-, six-, and twofold, respectively (P < 0.05), and the transcription rate of albumin, a negative acute phase gene, decreased to 34% of baseline (P < 0.01) during the 2.5 h of anesthesia and surgical stress. During this initial 2.5 h, plasma concentrations of TNF and IL-6 did not change. Hepatic IL-6 mRNA expression was never observed, and TNF mRNA expression was undetectable in six of seven pigs. Subsequent 10-μg/kg endotoxin administration caused 20-and 100-fold increases in plasma concentrations of TNF and IL-6, respectively (P < 0.01), and were associated with substantial hepatic expression of the TNF and IL-6 mRNAs. These increments in cytokines were not associated with any further increase in the acute phase gene transcription rates. Thus, the APR was initially regulated at the transcriptional level during surgical stress Independent of, and not augmentable by, an endotoxin-provoked increase in either plasma levels or hepatic mRNA expression of TNF or IL-6. ConclusionsSurgical stress induced hepatic acute phase gene transcription within 2.5 h in the absence of either systemic or local (hepatic) increases in TNF or IL-6. Subsequent endotoxin-induced Increases in TNF or IL-6 did not alter this surgical stress-induced acute phase gene transcription.

Ontogenic variation in acute lethality of cadmium in C57BL/6J mice

Susceptibility of C57BL/6J mice to the lethal effects of parenterally administered Cd declined as a function of age at exposure. The 7-day LD50 increased from 1.65 mg Cd/kg body wt in 7-day-old mice to 4.08 mg/kg in adult mice. Survival time following treatment with Cd also increased as a function of age. High constitutive concentrations of metallothionein, a transition metal-binding protein, in livers of young mice did not protect against the lethality of Cd. These results suggest that, in the mouse, the interaction between Cd and this metal-binding protein may be affected by age at exposure to this toxic metal.

Altered Organ Growth and Zinc and Copper Distribution in Endotoxin-Treated Neonatal Mice

ABSTRACT: Organ weights and the distribution of zinc and copper were compared in HLA/ICR mice that received intraperitoneal injections of 10 μg of Serratia marcescens lipopolysaccharide W or of sterile physiologic saline at 2 d of age. Between 5 and 28 d of age, body weight gains were similar in both groups. At 5 and 7 d of age, lipopolysaccharide W-treated mice had significantly lower thymus weights (p < 0.01). At 7 d of age, liver weight was significantly increased (p < 0.01) in lipopolysaccharide W-treated mice. Compared with tissue copper concentration in coeval saline-treated mice, lipopolysaccharide W treatment significantly increased copper concentration in thymus at 5 d of age (p < 0.05) and significantly decreased concentration of this metal in liver at 7 d of age (p < 0.05) and in spleen at 14 d of age (p < 0.05). Liver zinc concentration was significantly lower (p < 0.05) in 28-d-old mice that had received lipopolysaccharide W. When expressed on the basis of total organ burdens of zinc or copper, only the liver burden of zinc in 5-d-old lipopolysaccharide W-treated mice was significantly increased (p < 0.05). Lipopolysaccharide W treatment consistently decreased copper concentration in liver cytosol and the amounts of zinc and copper bound to metallothionein, a transition metal-binding protein, in liver cytosol. These effects of lipopolysaccharide W on organ size and metal distribution may contribute to the adverse effects that persist after endotoxin exposure in early life.