Hassan A. Naama

Blocking prostaglandin E2 after trauma attenuates pro-inflammatory cytokines and improves survival.

Major injury leads to impaired immune responses and increases the risk of infectious complications. Following trauma, increased prostaglandin E2 (PGE2) levels may be important in immunodysregulation. We hypothesized that blocking PGE2 with NS-398, a selective COX-2 inhibitor, during the first 24 h after injury may modify the immune response and protect the host from a subsequent septic challenge. BALB/c mice were given NS-398 (10 mg/kg) immediately after injury, at 12, and at 24 h after sham injury or trauma (femur fracture and 40% hemorrhage). On day 7 after injury, splenic macrophages were evaluated for cytokine production and COX-2 mRNA. In a separate study mice were injured, then given 3 doses of NS-398. After 7 days, cecal ligation and puncture was performed and mice were followed for survival. Traumatized mice given NS-398 had a significant survival advantage compared with trauma mice alone (P < 0.001). Macrophages from traumatized mice showed increased COX-2 mRNA and proinflammatory cytokines compared with controls (P < 0.05), whereas treatment of injured mice with NS-398 significantly decreased proinflammatory cytokine production (P < 0.05) and COX-2 mRNA. Therefore NS-398 given within 24 h of injury suppressed PGE2 through inhibition of cyclooxygenase, in addition to decreasing proinflammatory cytokines, and providing a survival advantage to the host.

Trauma-induced alterations in macrophage function☆☆☆

BACKGROUND The juxtaposition of immune suppression and a hyperactive inflammatory response after injury represents a paradox in immune function. The aim of this study was to evaluate the delayed macrophage hypersecretion of inflammatory mediators in relation to functional macrophage defects. METHODS BALB/c mice were randomized to control or trauma (femur fracture plus 40% blood volume hemorrhage) groups. One and 7 days after injury, splenic macrophages were isolated and assayed for antigen presentation and the production of inflammatory mediators tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, prostaglandin E2, H2O2, and nitric oxide. RESULTS One day after injury, there were significantly diminished macrophage antigen presentation and decreased mean production of TNF-alpha, IL-6, and H2O2. In contrast, 7 days after injury, splenic macrophages produced significantly increased mean amounts of TNF-alpha, IL-6, prostaglandin E2, H2O2, and nitric oxide, with a persistent functional defect in antigen presentation. CONCLUSIONS This phasic response to trauma suggests a persistent state of macrophage dysregulation that may help explain the paradox of immune suppression, manifested by functional defects predisposing patients to increased infections, in the setting of inflammatory mediator hypersecretion, predisposing patients to the systemic inflammatory response syndrome/multiple organ dysfunction syndrome.

The effect of granulocyte-macrophage colony-stimulating factor on myeloid cells and its clinical applications

Granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) is a naturally occurring growth factor produced by several cell types in response to a variety of stimuli. GM‐CSF has potent stimulatory effects on the growth and maturation of hematopoietic cells and has profound effects on mature circulating effector cells. Clinical applications of GM‐CSF include ameliorating chemotherapy‐induced neutropenia and enhancing hematopoietic recovery after bone marrow transplantation. This review evaluates the effect of GM‐CSF on myeloid cells and its clinical applications.

Glucocorticoids mediate macrophage dysfunction in protein calorie malnutrition.

BACKGROUND In hospitalized patients protein calorie malnutrition substantially increases the incidence of infection and death. Protein calorie malnutrition results in significant macrophage dysfunction. Whether a primary nutrient deficit or elevated glucocorticoids levels mediate this dysfunction is unclear. The aim of this study was to evaluate the neuroendocrine response to protein calorie malnutrition and its effects on macrophage function. METHODS By use of a murine model of protein calorie malnutrition, mice were randomized to (1) a standard 24% casein diet (control), (2) protein-free diet (PFD), (3) PFD in adrenalectomized mice, (4) PFD plus the glucocorticoid receptor antagonist RU486 (10 mg/kg), or (5) a standard 24% casein diet plus a 50 mg corticosterone pellet implanted subcutaneously for 7 days. Mice were killed after 7 days, and body weight and serum albumin and corticosterone levels were measured. Peritoneal macrophages were obtained, and stimulated superoxide and interleukin-6 productions were measured. RESULTS Protein calorie malnutrition significantly impaired macrophage function and elevated serum glucocorticoid levels. Blocking the stress corticosterone response with adrenalectomy or using RU486 to block corticosterone receptors prevented the impairment of macrophage function without restoring nutritional indexes (body weight and serum albumin level). Administration of glucocorticoids via a subcutaneous pellet reproduced macrophage impairment without leading to nutritional deficits. CONCLUSIONS The neuroendocrine systemic response to protein calorie malnutrition with elevated serum corticosterone levels is a major determinant of macrophage dysfunction in protein calorie malnutrition.

Beneficial effect of enteral glycine in intestinal ischemia/reperfusion injury

It has been shown in vitro that glycine can protect renal tubules and hepatocytes from hypoxic injury. Glycine also attenuates ischemic injury in transplanted livers. The present study investigated the effect of enteral glycine in a murine model of ischemia/reperfusion injury of the small intestine. Mice (n = 12 in each group) were randomized to receive two gastric gavages of either a 20% glycine (Gly) or 23% balanced amino acid (AA) solution with a 6-hour interval between each gavage. One hour after the second gavage, mice underwent superior mesenteric artery clamping for 20 minutes. The clamp was then released for reperfusion. Another group of mice (n = 8) underwent a sham operation and served as additional control animals. Six hours after ischemia/reperfusion, the mice were killed in order to assess the intestinal injury (intestinal protein content, mucosal disaccharidase activity, and intestinal histologic findings) and the systemic consequences (bacterial translocation, serum interleukin-6, and lung myeloperoxidase activity). A second set of mice (n = 55) underwent identical gavages and ischemia/reperfusion and they were followed for survival. Compared to AA, enteral glycine administered prior to intestinal ischemia/reperfusion injury significantly preserved mucosal indices and intestinal histology and decreased lung myeloperoxidase activity. Survival was also significantly increased in animals receiving glycine compared to AA control mice. These data suggest that enteral glycine supplementation may be beneficial in attenuating intestinal ischemia/reperfusion injury and its related systemic effects in this murine model.

Regional treatment of hepatic micrometastasis by adenovirus vector-mediated delivery of interleukin-2 and interleukin-12 cDNAs to the hepatic parenchyma.

We hypothesize that adenovirus (Ad) vector-mediated delivery of the human interleukin-2 (IL-2) cDNA (AdIL2) or the murine IL-12 cDNA heterodimer (AdIL12) would produce high concentrations of cytokines in the local hepatic milieu to induce host responses sufficient to inhibit the growth of experimental colon carcinoma-derived hepatic metastases. Ad vectors administered intravenously, which is a route known to deliver >90% of the vector to the hepatic parenchyma, achieved significant levels of each cytokine locally, with minimal levels in the sera. To examine the therapeutic effect, the AdIL2 and AdIL12 vectors were evaluated in a hepatic metastasis model that was established by injecting 3 × 104 cells from the poorly immunogenic syngeneic C26 colon carcinoma cell line into the right lobe of the livers of BALB/c mice. Animals received AdIL2, AdIL12, or control virus (108 plaque-forming units each) intravenously for 2 days after tumor implantation, and tumor growth was compared with naive controls. The AdNull control tumors measured 116 ± 25 mm2 at 2 weeks. The control virus showed no significant antitumor effect. In marked contrast, both AdIL2 and AdIL12 vectors that were delivered regionally had significant antitumor effects, with AdIL2-treated animals having an average tumor size of 16 ± 8 mm2; AdIL12-treated tumors measured 6 ± 6 mm2 (P < .01, both compared with control). Both the AdIL2 and AdIL12 vectors provided a significant survival advantage by log-rank analysis (P < .01), but only AdIL12 translated into an increase in mean survival from 27 (naive control) to 37 days. To evaluate whether these antitumor effects were T-cell-mediated, splenocytes from AdIL2-treated, AdIL12-treated, and naive control groups were stimulated in vitro with γ-irradiated C26 tumor cells for 5 days and tested for C26 tumor cell cytolysis by an in vitro cytotoxicity assay. Splenocytes from both AdIL2- and AdIL12-treated animals showed a dose-dependent, T-cell-mediated, specific cytolysis of CT26 cells. AdIL12 and to a lesser extent AdIL2 induced natural killer cell activity, as determined by a dose-dependent increase in lysis of the natural killer-specific target cell YAC-1. Overall, these data suggest that regional Ad-mediated delivery of IL-2 and IL-12 cDNAs may be useful for local tumor control and may warrant further investigation as a potentially useful adjuvant for the treatment of hepatic micrometastasis.

Glucocorticoid blockade does not abrogate tumor-induced cachexia.

Cancer-induced cachexia is a common manifestation observed in patients with malignancies. Elevated levels of circulating glucocorticoids and interleukin-6 (IL-6) have been observed in cancer patients with cachexia and are implicated as major mediators in this process. The purpose of this study was to investigate the role of circulating glucocorticoid levels as primary mediators in cancer-induced cachexia. We evaluated whether inhibition of glucocorticoids with the receptor antagonist RU-486 could abrogate the detrimental wasting of muscle and adipose tissues seen in a well-characterized murine tumor-induced cachexia model. Mice (12/group) were randomized to control, tumor-bearing, control + vehicle, or tumor-bearing + glucocorticoid receptor antagonist groups. Circulating serum glucocorticoid and IL-6 levels were measured in addition to multiple body composition parameters, such as total body weight, lean body mass, and adipose content. The results of this study indicate a significant physiological alteration in the tumor-bearing host that causes severe and detrimental changes in body composition parameters. Regression analysis demonstrated a significant correlation between increased circulating glucocorticoid levels and alterations in body composition parameters. These observed defects were not abrogated with the administration of a glucocorticoid receptor antagonist. We therefore conclude that the untoward effects of tumor-induced cachexia are not mediated primarily by the peripheral effects of high circulating glucocorticoid levels but may involve a complex interaction with IL-6.

Serum leptin levels in acute protein deprivation.

BACKGROUND Protein energy malnutrition (PEM) induces a host neuroendocrine response, reflected by significant elevations in circulating glucocorticoid levels and associated with metabolic and immune dysfunction. Leptin regulates food intake and body mass and has a significant impact on the hypothalamic-pituitary-adrenal axis (HPA). We hypothesized that leptin may be altered by and may play an important role in regulating the effects of PEM. METHODS Female Balb/c mice were used. In experiment 1, mice were pair-fed either a protein-free (0% casein) or control (24% casein) diet for 7 days. In experiment 2, mice were implanted with either a placebo or corticosterone-releasing pellet and fed the control diet for 7 days. In experiment 3, adrenalectomized mice were pair-fed either the protein-free or control diet for 7 days. Serum corticosterone and leptin levels were measured in all experiments. RESULTS PEM caused significant reductions in food intake, body weight, and total body fat, but not lean body mass. Serum corticosterone and leptin levels were significantly greater in mice fed the protein-free diet. Subcutaneous implantation of a corticosterone pellet in mice fed the control diet resulted in a significantly elevated serum leptin level compared with placebo-implanted controls. Bilateral adrenalectomy partially blunted the increased serum leptin in PEM. CONCLUSIONS Leptin may be an important mediator of weight loss and decreased food intake in PEM. Elevated serum leptin in PEM may be secondary to elevated serum corticosterone, with other factors inherent in the host response to protein restriction also contributing to elevated serum leptin.

Boerhaave's syndrome

A 40-year-old man with a recent history of cocaine abuse presented to the emergency department complaining of the sudden onset 2 hours earlier of sharp, postemetic, midepigastric pain radiating to the back and left shoulder. The pain was pleuritic and gradually increasing in severity. Vital signs at presentation were blood pressure of 150/72, respiratory rate of 38, and temperature of 37.3°C. His oxygen saturation on room air was 96%. The patient was writhing in pain and tachypneic. He had decreased breath sounds on the left and tinkling sounds in the left lower lung fields. He had normal heart sounds and a firm, nontender, nondistended abdomen. Cervical emphysema was noted several hours after initial presentation. Laboratory studies, including serum electrolytes, complete blood count, and serum amylase, were normal. His ECG showed a sinus tachycardia without ischemic changes. An upright chest x-ray demonstrated a large left pleural effusion (A, white arrows). The diagnosis of Boerhaave’s syndrome was entertained. A subsequent hypaque swallow study demonstrated extravasation of contrast from a distal esophageal perforation confirming the diagnosis (B). An uncomplicated primary esophageal closure with intercostal flap coverage was immediately performed (4 hours from the time of initial presentation). A repeat hypaque swallow study performed on postoperative day 11 demonstrated closure of the esophageal leak (C). He was discharged on postoperative day 15. Six weeks after surgery, the patient was doing well. Spontaneous rupture of the esophagus was first described by Hermann Boerhaave in 1724. Dr. Boerhaave observed the lethal esophageal perforation at autopsy on Baron Johannes Wassenaar, who had died from esophageal perforation after self-induced emesis to relieve postprandial gastric discomfort.