Metabolic responses to interleukin-1: centrally and peripherally mediated

In vitro characterization of PRRSV isolates with different in vivo virulence using monocyte-derived macrophages

The recent emergence of highly pathogenic porcine reproductive and respiratory syndrome virus 1 (PRRSV-1) strains has caused severe economic losses. The biological elements defining virulence and pathogenicity are still unclear. In vitro characteristics using natural target cells of PRRSV provide important information to understand the basis of virulence at the cellular level, and provide a mean to reduce animal experimentations to achieve this goal. Here, we compared PRRSV strains from two geographically different regions, with varying in vivo characteristics, in terms of their interactions with monocyte-derived macrophages (MDMs). The strains included Lena and BOR59 from Belarus, and ILI6 from Russia, as well as PR11 and PR40, both from Italy. As a reference, we used a cell culture-adapted version of Lelystad, LVP. MDMs were pre-treated with IFNγ, IL-4 or IFNβ, in order to understand responses in polarized and antiviral MDMs. In general, independent of the geographical origin, the strains with high virulence infected a higher percentage of MDMs and replicated to higher titers. These virulence-dependent differences were most pronounced when the MDMs had been treated with IFNβ. Differentiation between intermediate and low virulent PRRSV was difficult, due to variations between different experiments, but LVP differed clearly from all field strains. IFNα and IL-10 were not detected in any experiment, but PR40 induced TNF and IL-1β. Taken together, these results validate the MDM model to understand pathogenicity factors of PRRSV and confirm the importance of the escape from type I and II IFN-mediated effects for PRRSV virulence.

The Cancer Chemotherapy Drug Etoposide (VP-16) Induces Proinflammatory Cytokine Production and Sickness Behavior–like Symptoms in a Mouse Model of Cancer Chemotherapy–Related Symptoms

Cancer chemotherapy–related symptoms such as fatigue, malaise, loss of interest in social activities, difficulty concentrating, and changes in sleep patterns can lead to treatment delays, dose reductions, or termination and have a profound effect on the physical, psychosocial, and economic aspects of quality of life. Clinicians have long suspected that these symptoms are similar to those associated with “sickness behavior,” which is triggered by the production of the inflammatory cytokines IL-1β, TNF-α, and IL-6 by macrophages and other cells of the innate immune system in response to immune challenge. The p38 mitogen-activated protein kinase (p38 MAPK) plays a central role in the production of these cytokines and consequently the induction of sickness behavior. Several cancer chemotherapy drugs have been shown to activate p38 MAPK, but whether these drugs can also induce the production of inflammatory cytokines to cause sickness behavior is unknown. The aim of this study was to determine whether the cancer chemotherapy drug etoposide (VP-16), which is known to activate p38 MAPK, could induce inflammatory cytokine production by murine macrophages and sickness-like behaviors when injected into mice. VP-16 activated p38 MAPK and induced IL-6 production in murine macrophages in a p38 MAPK– dependent manner. VP-16 administration rapidly increased serum levels of IL-6 in healthy mice and induced sickness-like behaviors as evidenced by a decrease in food intake, body weight, hemoglobin level, and voluntary wheel-running activity. These findings support the idea that the induction of IL-1β, TNF-α, and IL-6 by cancer chemotherapy drugs underlies the fatigue and associated symptoms experienced by people undergoing cancer chemotherapy.

Exploration of the Contribution of Biobehavioral Variables to the Energy Expenditure of Preterm Infants

Variation in energy expended by preterm infants may be due to infant maturity and history of resolved acute lung disease (respiratory distress syndrome [RDS]) as well as growth, caloric intake, and activity. Indirect calorimetry was used in this exploratory, short-term longitudinal study to estimate energy expenditure (EE) from measures of inspired and expired O2 and CO2 .The sample included 35 assessments for 10 preterm infants (5 with and 5 without RDS history). Lung disease history (resolved RDS, no RDS diagnosis), weight gain (g/d) from the day on which birth weight had been regained to the study day, mean activity level, the number of the assessment (1 6), and the interaction of lung disease history and time were included in a linear mixed model for repeated measures. Time was an index of postconceptional and postnatal age; all 3 were highly correlated. Because of high correlation with weight gain, caloric intake was not included in the analytic model. Lung disease history, mean activity level, and time were significant contributors to EE. A more precise measure of medical status than absence or presence of lung disease history, evenly spaced repetitions of EE assessment, and exploration of contexts in which the infants exhibit a higher activity level are needed in a replication study with a larger sample.

Resuscitation volume in paediatric non-haemorrhagic blunt trauma

INTRODUCTION

Trauma is a major cause of paediatric morbidity and mortality, yet knowledge of fluid resuscitation is limited. Our objectives were to determine current practises in resuscitation volume (RV) administered to paediatric non-haemorrhagic (NH) blunt trauma patients and to identify fluid related complications.

METHODS

We examined data from 139 trauma patients 1-17 years of age with an injury severity score ≥ 12 resuscitated at a Trauma-designated Children's Hospital. Patients were separated into discreet groups based on ATLS age-dependent vital functions: toddler/preschooler (1-5 years), school age (6-12 years) and adolescent (13-17 years).

RESULTS

The median RV (total fluid intake-maintenance fluid intake) in ml/kg over the first 24h from the time of trauma by age was: 24 (IQR=19-47; 1-5 years); 26 (IQR=15-36; 6-12 years); and 22 (IQR=14-42; 13-17 years). The differences in RV/kg/24h following NH trauma was not significantly different between age groups (p=0.41). Urine output over the 24h ranged from 2.5 (IQR=1.9-3.3; lower age group) to 1.8 (IQR=1.2-2.4; upper age group) ml/kg/h; greater than the ATLS recommended age-dependent targets. Haematocrit was the only significant independent predictor of RV/kg/24h (p<0.001). Fluid-related complications attributable to RV were identified in 12% (n=17/139) of patients, and included ascites (8%; n=11/139) and/or pleural effusion(s) (9%; n=13/139). Patients with fluid-related complications received significantly more RV in ml/kg/24h (42, IQR=27-76) than those without complications (22, IQR=14-36; p=0.001).

CONCLUSIONS

The range of median RV administered to paediatric NH blunt trauma patients with ISS ≥ 12 was 22-26 ml/kg/24h. The RV administered was excessive based on high urine outputs and the presence of fluid-related complications. Further evaluation of RV triggers and endpoints used by paediatric traumatologists is required.

Application of clinical proteomics in diagnosis and management of trauma patients

Poly-trauma remains a medical entity with major implications, for patient's morbidity, mortality and healthcare economics. Advances in molecular medicine have improved diagnostic techniques in detecting devastating complication after major trauma. Patients at high risk of multiple organ dysfunction syndrome (MODS) or adult respiratory distress syndrome (ARDS), could be identified early, monitored and treated. Proteomics is the systematic evaluation of proteins produced by the cell under normal or pathological circumstances. Investigating protein production will allow us to identify and modify disease natural history and treatment. In this review, we summarise the proteomic methods currently applied in trauma research.

Cancer Chemotherapy-Related Symptoms: Evidence to Suggest a Role for Proinflammatory Cytokines

PURPOSE/OBJECTIVES

To provide an overview of the evidence that supports a role for the proinflammatory cytokines interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) in the etiology of cancer chemotherapy-related symptoms.

DATA SOURCES

Electronic nursing, psychology, and medicine databases; online meeting abstracts; and personal experimental observations.

DATA SYNTHESIS

Substantial evidence implicates the proinflammatory cytokines IL-1beta, TNF-alpha, and IL-6 in the etiology of chemotherapy-related anorexia, cachexia, anemia, pain, sleep disturbance, fatigue, and depression.

CONCLUSIONS

Further investigation into the role of these cytokines in the genesis of chemotherapy-related symptoms is warranted. The development of appropriate animal models likely will be key to understanding the relationship among cancer chemotherapy, proinflammatory cytokines, and symptoms.

IMPLICATIONS FOR NURSING

Nurses traditionally have been leaders in symptom management. The symptoms experienced by patients undergoing chemotherapy have a profound negative impact on quality of life and patients' ability to receive prescribed treatments. An understanding of potential mechanisms underlying the physiologic and behavioral consequences of chemotherapy administration will aid nurses in the development of interventions to effectively manage chemotherapy-related symptoms.

Minimal access colonic surgery: is it truly minimally invasive?

Laparoscopic colonic surgery has an established role in the management of both benign and malignant conditions. Proposed benefits from laparoscopic surgery include decreased pain, decreased metabolic disturbance to the patient and faster recovery. It is now generally accepted that pro-inflammatory mediators, including cytokines, are to a great extent responsible for the metabolic changes associated with injury and surgery, and that these metabolic changes are related to postoperative recovery. Cytokine levels in the serum are decreased after major laparoscopic colorectal surgery compared with open surgery. However, the cytokine concentration in abdominal drain fluid is the same independent of the size of the incision and these concentrations are far higher than those found in the serum suggesting that the peritoneal would from the surgery itself is more important to metabolic events than the skin wound used to access the abdominal cavity to perform the operation. When looked at critically in programmes where patients are optimally managed perioperatively, there appears to be minimal metabolic benefit from performing a major colonic resection using minimal access surgery. Thus, it appears that the wound is critical when the operation involves only minor peritoneal disruption, such as in laparoscopic cholecystectomy, but when large peritoneal defects are created, such as in major colorectal surgery, then the skin wound becomes irrelevant to metabolism and hence recovery. Thus, minimal access does not necessarily equate to minimal invasion and the terms should not be used interchangeably in the context of laparoscopic colorectal surgery.

Central nervous system interleukin-8 production following neck of femur fracture

AIM

To establish a proinflammatory cytokine profile of the cerebrospinal fluid (CSF) following trauma.

BACKGROUND

Trauma is associated with a postinjury syndrome consisting of loss of weight and nitrogen, pyrexia, anorexia and fatigue. It has been proposed that cytokines are pathophysiologically involved in this syndrome but the site of action of these is unclear. Previous work in head injury models, supported by animal work, has suggested that one important site of action is the central nervous system (CNS).

METHODS

Women who had sustained neck of femur fractures were enrolled (trauma group). CSF was collected at the time of spinal anaesthetic. Women undergoing elective lower limb surgery were recruited as controls. CSF and serum were assayed for Interleukin (IL) 1, 2, 4, 6, 8, 10, 12, interferon gamma, and tumour necrosis factor by cytometric bead array.

RESULTS

In the trauma group, IL-8 was elevated in the CSF but not in the serum, while IL-6 was elevated in the serum but not in the CSF. IL-1beta, associated with elevated IL-12, was also detected in the serum of three of 11 trauma patients but none of the nine controls. No other cytokines were consistently detected.

CONCLUSIONS

This study raises the possibility that IL-8, acting in the CNS, plays a role in the postinjury syndrome. It is unclear as to the mechanism by which CNS IL-8 is produced in trauma but a physiological role is supported by the known ability of the CNS to produce IL-8 and the presence of receptors for its action in the CNS.

Cytokines in patients with polytrauma

Patients with multiple injuries have alterations in hemodynamic, metabolic, and immune responses that largely are orchestrated by endogenous mediators referred to as cytokines. At the molecular level cytokines act as architects constructing a blueprint which ultimately will become the clinical "Big Picture"; however, the exact role and extent each cytokine has is still in question. In addition, the surface of research opportunities has nearly been scratched regarding the best way to control or manipulate the cytokine response in efforts to improve care for the trauma patient. Systemically organisms respond to injury regardless of the cause (hemorrhage, ischemia, reperfusion, fracture, and tissue damage) by attempting to restore homeostasis, which involves a coordination of the immune, cardiovascular, endocrine, and nervous systems. This systemic response can result in severe immunologic compromise that threatens the survival of patients with trauma. It seems that it is this balance or imbalance of cytokines, along with other associative factors, that controls the eventual clinical pathway a patient will take. Blood mediator concentrations often parallel the inflammatory process, and high levels of cytokines can be followed by severe organ dysfunction. Certain cytokine levels, such as the interleukins, can be used in predictive ways to correlate organ failure in multiply injured patients. Although much more research must be done, there is great promise in the study of cytokines through basic science research and clinical trials.

Effect of central administration of interleukin-1 receptor antagonist on protein synthesis in skeletal muscle, kidney, and liver during sepsis

Inflammatory cytokines may mediate the host response to infection via central nervous system (CNS), endocrine, and/or paracrine pathways. The purpose of the present study was to determine whether intracerebroventricular (ICV) infusion of interleukin-1 receptor antagonist (IL-1ra) influences the effects of sepsis on protein metabolism in peripheral organs (skeletal muscle, kidney, and liver). A constant ICV infusion of IL-1ra (100 microg/h) or saline was begun immediately before the induction of sepsis or sterile inflammation and continued for 5 days. ICV infusion of IL-1ra did not alter protein metabolism in animals with a sterile abscess. Sepsis reduced muscle weight, protein content, and rates of protein synthesis in gastrocnemius. ICV infusion of IL-1ra attenuated the sepsis-induced loss of muscle mass and protein and the inhibition of protein synthesis in gastrocnemius by augmenting the translational efficiency. Similar results were observed in kidney, with respect to kidney weight, total protein, rates of protein synthesis, and translational efficiency. However, central infusion of IL-1ra did result in a small (12%) increase in the renal RNA content in either sterile or septic abscess rats. In liver, ICV infusion of IL-1ra prevented the sepsis-induced inhibition of protein synthesis and reduction in translational efficiency. These results suggest that central administration IL-1ra can modulate protein metabolism in peripheral organs during sepsis by preventing the sepsis-induced defects in the translational efficiency.

Capsaicin-sensitive nerves regulate the metabolic response to abdominal sepsis

BACKGROUND

Both the systemic release of inflammatory mediators and activation of the neuroendocrine axis by sensory afferent nerves (SANs) have been implicated as initiators of the metabolic response to infection. In this study, we investigate the role of SANs as mediators of protein catabolism and the insulin-like growth factor (IGF) axis during abdominal sepsis using capsaicin (Cap) to selectively destroy nociceptive sensory axons.

METHODS

Four groups of male Sprague-Dawley rats were studied: Control, Control+Cap, Sepsis, and Sepsis+Cap. Rats were injected with Cap (75 mg/kg) on day 1 and (50 mg/kg) on day 2 to destroy SANs. Time-matched control and septic rats were pair-fed and injected with vehicle on the same schedule. Controls underwent sham laparotomy, while septic rats had a fecal-agar pellet inoculated with Escherichia coli and Bacteroides fragilis implanted in the peritoneal cavity. Blood and tissues were harvested 5 days after the induction of sepsis. Plasma IGF-I, IGFBP-1, and -3 were measured by radioimmunoassay and Western blot analysis. IGF-I, acid-labile subunit (ALS), IGFBP-1 and -3 mRNA levels were determined by Northern blot analysis.

RESULTS

Mortality was 40% in septic rats vs 0% in the sepsis+Cap group. Capsaicin had no effect on muscle mass, protein content, or the IGF system in control rats. However, sepsis-induced reductions in gastrocnemius mass (25%) and protein content (35%) were ameliorated by capsaicin. The sepsis-induced decrease in hepatic IGF-I mRNA and circulating IGF-I (26%), as well as the 4-fold increase in plasma IGFBP-1 and hepatic IGFBP-1 mRNA were prevented by capsaicin.

CONCLUSIONS

Capsaicin-sensitive nerves mediate mortality, the catabolism of skeletal muscle, and selected elements of the IGF system during abdominal sepsis. The results suggest an important role for nociceptive SANs and the neuroendocrine system in mediating the host response to abdominal infection.

From Cuthbertson to fast-track surgery: 70 years of progress in reducing stress in surgical patients

OBJECTIVE

To evaluate the evolution of knowledge concerning the stress response in surgical patients and to determine the therapeutic benefit of stress reduction therapy.

SUMMARY BACKGROUND DATA

The stress response in surgical patients is associated with tissue catabolism, organ failure, and prolonged recovery. Understanding the neural-hormonal basis for these events has stimulated efforts to attenuate these undesirable effects. A review of the results of these efforts is important for the application of stress reduction therapy and further improvement of surgical care.

METHODS

Medline was searched from 1980 to the present using the terms "stress response," "neural-hormonal response," "fast track surgery," and "outcome in surgical patients." These papers were reviewed along with historical information relating to early descriptions of metabolic and stress responses in surgical patients.

RESULTS

Improved understanding of the stress response in surgical patients has occurred over the past 70 years. Multiple examples of stress reduction associated with decreased morbidity and mortality are reported.

CONCLUSIONS

Reduction of stress in surgical patients has improved outcome. The use of stress reduction techniques will continue to expand and contribute to the improvement of future surgical care.

From Cuthbertson to fast-track surgery: 70 years of progress in reducing stress in surgical patients

OBJECTIVE

To evaluate the evolution of knowledge concerning the stress response in surgical patients and to determine the therapeutic benefit of stress reduction therapy.

SUMMARY BACKGROUND DATA

The stress response in surgical patients is associated with tissue catabolism, organ failure, and prolonged recovery. Understanding the neural-hormonal basis for these events has stimulated efforts to attenuate these undesirable effects. A review of the results of these efforts is important for the application of stress reduction therapy and further improvement of surgical care.

METHODS

Medline was searched from 1980 to the present using the terms "stress response," "neural-hormonal response," "fast track surgery," and "outcome in surgical patients." These papers were reviewed along with historical information relating to early descriptions of metabolic and stress responses in surgical patients.

RESULTS

Improved understanding of the stress response in surgical patients has occurred over the past 70 years. Multiple examples of stress reduction associated with decreased morbidity and mortality are reported.

CONCLUSIONS

Reduction of stress in surgical patients has improved outcome. The use of stress reduction techniques will continue to expand and contribute to the improvement of future surgical care.

Regulation of reticuloendothelial iron transporter MTP1 (Slc11a3) by inflammation

Acute and chronic inflammation cause many changes in total body iron metabolism including the sequestration of iron in phagocytic cells of the reticuloendothelial system. This change in iron metabolism contributes to the development of the anemia of inflammation. MTP1, the duodenal enterocyte basolateral iron exporter, is also expressed in the cells of the reticuloendothelial system (RES) and is likely to be involved in iron recycling of these cells. In this study, we use a lipopolysaccharide model of the acute inflammation in the mouse and demonstrate that MTP1 expression in RES cells of the spleen, liver, and bone marrow is down-regulated by inflammation. The down-regulation of splenic expression of MTP1 by inflammation was also observed in a Leishmania donovani model of chronic infection. The response of MTP1 to lipopolysaccharide (LPS) requires signaling through the LPS receptor, Toll-like receptor 4 (TLR4). In mice lacking TLR4, MTP1 expression is not altered in response to LPS. In addition, mice lacking tumor necrosis factor-receptor 1a respond appropriately to LPS with down-regulation of MTP1, despite hyporesponsiveness to tumor necrosis factor-alpha signaling, suggesting that this cytokine may not be required for the LPS effect. We hypothesize that the iron sequestration in the RES system that accompanies inflammation is because of down-regulation of MTP1.

Effect of prophylactic intracerebroventricular injection of methylprednisolone on nitrogen and catecholamine excretion in the urine after laparotomy in rats

BACKGROUND

This study was carried out to determine whether the prophylactic injection of glucocorticoid into the intracerebroventricular (i.c.v.) space reduced TNF-alpha and IL-1beta mRNA synthesis in the brain after laparotomy, resulting in a reduction of nitrogen excretion in the urine.

PATIENTS AND METHODS

Male SD rats (body wt., 225-250 g, n = 114) were catheterized into the i.c.v. space on day 0. On day 4, the rats were assigned to four groups: (1) Control, (2) laparotomy (Trauma), (3) intraperitoneal (i.p.) injection of methylprednisolone (MP) plus laparotomy (IPMP), and (4) i.c.v. injection of MP plus laparotomy (ICVMP). Either 3 or 24 h after surgery, the animals were sacrificed. TNF-alpha and IL-1beta mRNA levels in tissues, including the brain cortex and hypothalamus, were measured by RT-PCR. The amounts of nitrogen and catecholamine excretion in the 24-h urine were determined.

RESULTS

The i.p. injection of MP reduced TNF-alpha and IL-1beta mRNA levels in all the tissues 3 h after laparotomy compared with those of the Trauma group. The icv injection of MP prevented elevation of the TNF-alpha and IL-1beta mRNA levels in the brain (cortex, TNF-alpha, ICVMP 0.43 +/- 0.06, P < 0.05, vs Trauma; cortex, IL-1beta, ICVMP 0.25 +/- 0.09, P < 0.05, vs. Trauma; hypothalamus, TNF-alpha, ICVMP 0.31 +/- 0.04, P < 0.05, vs. Trauma; hypothalamus, IL-1beta, ICVMP 0.25 +/- 0.14, P < 0.05, vs. Trauma), but did not inhibit an increase in TNF-alpha and IL-1beta mRNA levels in the liver and skeletal muscle. Both nitrogen and catecholamine excretions in the urine were decreased by ip and by i.c.v. injection of MP compared to those of the Trauma group (nitrogen, ICVMP 559.3 +/- 52.0 mg/day, P < 0.05, vs. Trauma; catecholamine, ICVMP 13.8 +/- 1.8 microg/day, P < 0.05, vs. Trauma).

CONCLUSION

A reduction in TNF-alpha and IL-1beta mRNA synthesis in the brain due to prophylactic injection of MP into the icv space reduced the catabolic response after laparotomy.

Effects of serotonin synthesis blockade on interleukin-1 beta action in the brain of rats

The ability of the brain serotonergic system to mediate the effects of interleukin-1beta (IL-1beta) was investigated. Intracerebroventricular administration of IL-1beta induced a significant pyrogenic reaction, depression in social behaviour, loss of body weight and reduced food intake in rats. Pre-treatment with p-chlorphenylalanine, an inhibitor of serotonin synthesis, blocked the IL-1beta-induced decrease in food intake and loss of body weight, but failed to alter the temperature increase and the decrease in communicative activity.

Cytokines and the anorexia of infection: potential mechanisms and treatments

Anorexia during infection is thought to be mediated by immunoregulatory cytokines such as interleukins 1 and 6 and tumor necrosis factor. This article reviews the potential mechanisms of action by which these cytokines are thought to suppress food intake during infection and examines the proposition that blocking of cytokine activity might be one approach to improving food intake of the infected host.

Effect of fentanyl on morphine levels in the brain in rats receiving intracerebroventricular injection of TNF-alpha

Fentanyl citrate analgesia attenuates the excess nitrogen excretion in the urine and glucose production induced by trauma. On the other hand, intracerebroventricular injection of morphine stimulates excretion of stress hormones, such as catecholamines and corticosterone. Furthermore, morphine levels in the brain are increased during fasting and sepsis. The aims of this study were to determine whether intracerebroventricular injection of tumor necrosis factor-alpha (TNF-alpha) elevates morphine levels in the rat brain and whether prophylactic administration of fentanyl blocks metabolic responses induced by intracerebroventricular injection of TNF-alpha because of a reduction of morphine levels in the brain. Morphine levels in the brain were increased from 648 to 1,134 fmol/g at 30 min after intracerebroventricular injection of TNF-alpha (P < 0.05 vs. control). This increase was associated with an increase in stress hormones (corticosterone: 416.1 +/- 69.1 ng/ml, P < 0.05 vs. control; epinephrine: 3,778.3 +/- 681.3 pg/ml, P < 0.01 vs. control) and an enhancement of proteolysis (254.2 +/- 45.7 micromol Leu . kg-1 . h-1, P < 0.01 vs. control) and glucose production (7.5 +/- 0. 7 mg . kg-1 . min-1, P < 0.05 vs. control). Fentanyl reduced morphine levels in the brain to 624 fmol/g (not significant vs. control), resulting in a reduction of stress hormone levels in the plasma and blunted metabolic responses. In conclusion, prophylactic administration of fentanyl prevented an increase in morphine levels in the brain induced by intracerebroventricular injection of TNF-alpha, leading to a reduction in stress hormone levels and subsequent metabolic responses.

Metabolic response to severe injury

BACKGROUND

Severe injury is associated with a complex sequence of metabolic events. The accurate quantification of these changes and a developing understanding of their aetiology has been the product of much work by researchers over the past 60 years. An understanding of these phenomena is vital to the practising surgeon because of the plethora of new metabolic modulators threatening to become part of clinical practice.

METHODS

This review describes the clinical picture of the metabolic response to severe injury and then outlines modern understanding of the underlying processes.

RESULTS AND CONCLUSION

The need for further research before introduction of new technologies is emphasized.