Early inflammatory response correlates with the severity of injury

OBJECTIVE

To determine if the early inflammatory response correlates with the severity of injury in a blunt trauma model in rats.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Research laboratory.

SUBJECTS

Male Sprague-Dawley rats, weighing 250 to 400 g.

INTERVENTIONS

Twenty-two male Sprague-Dawley rats were divided randomly into single hindlimb fracture, bilateral hindlimb fracture, and no fracture groups. At 90 mins, all animals underwent midline laparotomy and aspiration of blood from the inferior vena cava. Venous blood gas, plasma lactate, and plasma concentrations of tumor necrosis factor (TNF), prostaglandin F(6-keto-PGF1 alpha), and interleukin (IL)-6 were sampled. Statistical analysis was done via one-way analysis of variance and Scheffé post hoc analysis. In a second part of this experiment, the effect of hemorrhage on the release of IL-6 was evaluated. Animals in this group were compared with control and bilateral hindlimb fracture animals, using the Student's t-test.

MEASUREMENTS AND MAIN RESULTS

There were no significant differences in venous pH or base deficit among the groups. Oxygen saturation was significantly decreased in the bilateral hindlimb fracture group when compared with the control group. In the hemorrhage plus bilateral fracture group, oxygen saturation was significantly decreased when compared with the bilateral fracture group. lactate concentrations in plasma were increased in both fracture groups as well as the hemorrhaged groups. Plasma TNF concentrations were increased in the injured groups but there was no significant difference between single and bilateral hindlimb fracture groups. The 6-keto-PGF1 alpha concentrations were increased in both of the fracture groups when compared with the control group and there was a significant difference between single and bilateral hindlimb fracture groups. Similarly, circulating IL-6 concentrations were significantly higher in the bilateral fracture group than in the single fracture group; both fracture groups were significantly higher than the control group. Hemorrhaged animals had even higher IL-6 concentrations.

CONCLUSIONS

Plasma lactate and TNF concentrations were affected by injury, however their concentrations did not correlate with degree of injury. IL-6 concentrations were increased early postinjury and correlated with severity of injury. The 6-keto-PGF1 alpha concentrations in plasma also correlated with the severity of injury and this phenomenon may represent early endothelial activation which may be the source of IL-6 release.

Excretion of IL-6 by astronauts during spaceflight

Ascent to and living under the microgravity conditions found during spaceflight is an unfamiliar environment for humans. The adaptation to the space environment may be perceived by the body as a stress. On the ground, stress results in increased cytokine activity. The objective of this study was to determine whether spaceflight is associated with increased cytokine activity. The mean daily urinary interleukin-6 (IL-6) excretion rate was measured on 24-h urine pools collected from four payload crew members from 11 days before launch to 7 days after landing for a total of 27 days. In addition, in-flight data were obtained from two orbiter crew members. The experiment was conducted before, during, and after the 1991 9.5-day SLS-1 (Columbia) space shuttle mission. Dietary intake and urine output were monitored continuously for the 27-day period for the four payload crew. Results are as follows: 1) urinary IL-6 excretion and cortisol excretion were increased on the 1st day of spaceflight, suggesting an acute-phase response; 2) elevated levels of IL-6 were not found in the urine on any other days before or during flight; and 3) two of the subjects had markedly increased IL-6 excretion rates after landing.

Modulation of alpha 1-acid glycoprotein (AGP) gene induction following honey bee venom administration to adjuvant arthritic (AA) rats; possible role of AGP on AA development

Honey bee venom (HBV) administration to adjuvant arthritic (AA) rats resulted in a significant suppression of arthritis and in suppression of the hepatic acute phase alpha 1-acid glycoprotein (AGP) gene induction at the early stages of disease development. AGP administration in AA rats resulted in acceleration of arthritis development and in increase of severity and duration of the disease. IL-1, IL-6, tumour necrosis factor (TNF) and glucocorticoids alone are not responsible for the HBV-mediated AGP gene down-regulation. These results indicate that AGP gene expression in AA and HBV-treated AA rats involves the interaction of several factors, and that AGP plays a role for AA development in rats.

Transfer of the IL-6 gene into a human colorectal carcinoma cell line and consequent enhancement of tumor antigen expression

cDNA encoding the human IL gene (580 bp), inserted into a retroviral expression vector carrying neomycin resistance selective marker, was introduced into HT-29 human colon carcinoma cells by lipofection. Interleukin-6 activity was measured by ELISA and bioassay using B9 cells. Interleukin-6 secreted by transfected HT-29 cells was shown to be biologically active. The expression of the human tumor associated antigen CEA (carcinoembryonic antigen), HLA classes I and II, and ICAM-1 antigens in the transfected HT-29 cells were also analyzed by flow cytometry. Significant enhancement in the expression of CEA but not in the expression of HLA class I, HLA class II and ICAM-1 antigens, was observed in the transfected HT-29 cells as compared to the parental HT-29 cells. These results provide experimental evidence that enhancement of tumor antigen expression on tumor cells can be induced by IL-6 gene transfection, and suggest another potential role for the use of IL-6 gene transfer in the immunotherapy of human cancers.

C-reactive protein in patients with lymphatic filariasis: increased expression on lymphocytes in chronic lymphatic obstruction

Levels of C-reactive protein (CRP) were evaluated by enzyme immunoassay in patients infected with the filarial parasite Wuchereria bancrofti. Significantly elevated levels of CRP (P less than 0.001) were demonstrated in patients with chronic lymphatic pathology (CP; n = 18) compared to patients with asymptomatic microfilaremia (MF; n = 13) and normal volunteers (NV; n = 29). Serum levels of CRP showed an inverse correlation (rs = -0.37; P less than 0.05) with phosphocholine (PC)-containing filarial antigen that was present in the circulation of patients with bancroftian filariasis. Marked elevations in the percentage of CRP-binding lymphocytes were observed in patients with CP (mean = 44%; P less than 0.001) compared to those with MF (mean = 18%) or NV (mean = 3%). The increased percentage of surface CRP was not due to an abnormal change in major lymphocyte subset (CD5, CD4, CD8, or CD19). No significant correlation was noted between surface CRP and serum CRP; however, an inverse correlation was observed between surface CRP and PC-bearing circulating filarial Ag (rs = -0.64; P less than 0.001). Biosynthetic labeling and immunoprecipitation with anti-CRP antibodies indicated quantitative differences in the synthesis of CRP in patients with CP compared to MF and CP. Complexing of CRP with PC-containing Brugia malayi antigen (CRP-BmA) caused increased binding to normal lymphocytes (less than 8%), but not close to the extent seen in patients with CP (44%), suggesting de novo synthesis of CRP in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics of interleukin-2 and interleukin-6 synthesis following major mechanical trauma

Although it is known that mitogen-induced lymphocyte proliferation and interleukin-2 (IL-2) synthesis are depressed following mechanical trauma, it is not known whether these defects are due to high levels of circulating prostaglandin E2 released by macrophages, suppressor T-lymphocytes, and serum suppressive factors or due to intracellular defects in T-lymphocytes. Moreover, the kinetic of interleukin-6 (IL-6), a new multifunctional cytokine, following trauma is not known. To study this, highly purified T-cell cultures were prepared from 21 patients with major mechanical trauma on Days 3, 7, 10, 14, and 21 post-trauma and assayed for proliferative response to phytohemagglutinin, IL-2, and IL-6 synthesis. T-lymphocyte proliferation of patients was unaltered on all days post-trauma compared to that of healthy controls. Interleukin-2 synthesis of patients showed a significant (P less than 0.01) reduction ranging from 23% of control values on Day 3 to 40% on Day 21. Interleukin-6 synthesis in contrast was markedly increased (P less than 0.05) in the patient group on all days up to sixfold (Day 3) with a tendency toward normalization on Day 21. High levels of IL-6 correlated with the appearance of infectious complications in the post-traumatic course. These data indicate that the alterations in T-cell proliferation and IL-2 synthesis following major injury found in earlier studies are caused by different suppressor mechanisms. While T-cell proliferation is only decreased by extracellular components, IL-2 synthesis is suppressed mainly by an intracellular defect. The role of highly increased IL-6 levels and its effect on the immune response are so far unknown.