Dysfunctional immune-privilege in morbid obesity: implications and effect of gastric bypass surgery.

BACKGROUND: Despite the epidemiological evidence linking obesity and cancer, there has never been a causal link. We believe the chronic inflammation present in obesity may predispose the obese to cancer through Fas-receptor over-expression and L-selectin under-expression in leukocytes, and elevated Fas ligand secretion in tumors affecting the morbidly obese. METHODS: Leukocytes from 25 patients having gastric bypass surgery were compared to 15 normal controls preoperatively and at 1, 3, 6, and 12 months postoperatively using flow cytometry to measure CD3, CD4, CD8, CD56, CD62 (L-selectin), CD69, and CD95 (Fas antigen) expression on T lymphocytes, B lymphocytes, natural killer cells, and neutrophils. RESULTS: The percentage of CD95 + T cells was significantly elevated from controls (69.4% vs 56%, P = 0.005). This difference persisted through 1 month postoperatively. Furthermore, expression of CD95 per cell, was significantly greater in these patients than that of the controls (80.2 vs 62.6 gmf, P = 0.018) preoperatively, and this continued to 1 month. Polymorphonuclear cells also displayed a similar elevation in CD95 gmf expression preoperatively (54.1 vs 40.7 gmf, P = 0.023) which normalized by 3 months. Natural killer cells did not display elevated numbers of CD95 gmf preoperatively, but they did experience a significant decline by 12 months. Additionally, there was significant reduction in the number of naiveT cells [(T cells without L-selectin (CD62L)], when compared to normals preoperatively (41.8% vs 51.3%, P = 0.001). There was no statistical difference between the postoperative patients and the controls by 3 months. CD69 was not different at baseline from controls in T or B cells, but there was a significant decrease by 12 months. CONCLUSION: The reduced expression of L-selectin combined with the elevated levels of CD95 suggests that morbid obesity predisposes patients to sites of immune privilege. This could be the mechanism for increased rates of cancer and wound infections seen in obesity. Surgically-induced weight loss eliminates these risk factors.

Effect of surgically-induced weight loss on leukocyte indicators of chronic inflammation in morbid obesity.

BACKGROUND: Recent evidence suggests that morbid obesity is a chronic inflammatory condition that may be associated with immune dysfunction. To test this hypothesis, we investigated several leukocyte cell surface markers of chronic inflammation and followed their response to surgically-induced weight loss. METHODS: 26 patients having Roux-en-Y gastric bypass (RYGBP) for morbid obesity (BMI > 40) were compared to 10 normal controls (BMI < 25). Relative monocyte and neutrophil frequencies and expression of the activation antigens CD11b (adhesion molecule), CD16 (Fc receptor), and CD62L (L-selectin), were evaluated by flow cytometry preoperatively and at 1, 3, 6 and 12 months after RYGBP. Cases served as their own controls but were also compared to non-obese controls. The results were statistically analyzed using Student's t-test and ANOVA for parametric values and Mann-Whitney along with Kruskal-Wallis ANOVA for nonparametric values. RESULTS: The control group had mean age 37 +/- 7.6 with mean 23 +/- 2.5 and no comorbidities. The mean age of the sample group was 40.36 +/- 13.7 with mean BMI 52 +/- 8.2. The neutrophil and monocyte relative frequencies of CD11b (monocytes and neutrophils), and CD16 (neutrophils only) were comparable to controls at baseline and did not change significantly with weight loss throughout the study period. However, a significant reduction of CD62L (L-selectin) expression was noted in monocytes and neutrophils at baseline (neutrophils 103 vs 240 gmf, p < 0.001) (monocytes 104 vs 246 gmf, P < 0.001) when compared to normal controls. Levels of L-selectin normalized by 6 months in both monocytes and neutrophils, and by 12 months had become abnormally elevated in monocytes (monocytes 391 gmf, P = 0.007); in neutrophils, there was an upward trend that did not reach significance. The expression of the LPS receptor CD14 in the study group was elevated significantly compared to controls at baseline (1129 vs 719 gmf, P = 0.004); this marker appeared to return to normal by 3 months. Monocyte CD14+/CD16+ subset percentage were also elevated significantly at baseline (14.3% vs 5.25%, P < 0.001), declined throughout the time period but was still significant at 1 year (8.8%, P < 0.001). Eosinophil percentages were elevated at baseline (3.3% obese vs 1.8% controls, P = 0.003) and remained so throughout the time period. CONCLUSION: Deficiencies in the immune system of morbidly obese individuals include elevated levels of eosinophils, monocyte CD14, and monocyte CD14+/CD16+ subsets, with depression of monocyte and neutrophil CD62L. These abnormal levels reverse rapidly with surgically-induced weight loss. RYGBP is not only a weight loss operation but also appears to be an immune restorative procedure.

The effect of obesity on neutrophil Fc receptors and adhesion molecules (CD16, CD11b, CD62L).

BACKGROUND: There is a large body of epidemiological data associating obesity with a wide variety of clinical disease processes, including cancer and wound infections. However, defining the specific defects of neutrophils has proved difficult and often contradictory. METHODS: 27 patients having gastric bypass surgery for obesity (BMI > 40) were compared with 10 normal controls (BMI < 26). Relative neutrophil frequencies and expression of the activation antigens CD11b (integrin adhesion molecule), CD16 (Fc receptor), and CD62L (L-selectin), were evaluated by flow cytometry. RESULTS: The study control group had a mean age of 37 +/- 7.6 yrs (range 30 to 57) with no significant health problems. Their mean BMI was 23 +/- 2.5 kg/m2 (range 21-26). The mean age of the sample group was 40.36 +/- 13.7 yrs (range 18 to 60) with a mean BMI of 52 +/- 8.2 kg/m2 (range 41 to 72). These patients had a large spectrum of diseases that afflict the morbidly obese, including hypertension (14), arthritis (10), exertional dyspnea (13), venous stasis (7), hypothyroidism (2), NIDDM (3), heart murmur (1), along with 8 smokers. The neutrophil frequency in the obese patients was comparable to the controls (control 49% vs obese 51%). Additionally, there was no apparent difference between obese and controls regarding CD11b or CD16 expression (424 vs 498 gmf) (267 vs 262 gmf). However, there was a significant reduction of CD62L (L-selectin) expression noted in the morbidly obese with respect to controls (102 vs 303 gmf, p < 0.001). An increased percentage of eosinophils when compared to controls (6.7% vs 1.73%, p < 0.001) was also observed. CONCLUSION: Discordant CD11b/CD62L levels, depressed levels of CD62L, and elevated eosinophil percentages support the hypothesis that a chronic inflammatory state exists in morbid obesity. Decreased levels of CD62L in the morbidly obese neutrophil pool possibly affect the neutrophil's ability to activate and migrate to sites of inflammation. This may play a role in the higher incidence of infectious complications seen in morbidly obese individuals.

Prostaglandin E2 receptors EP2 and EP4 are down-regulated in human mononuclear cells after injury.

BACKGROUND: Recent characterization of prostaglandin receptor subtypes shows that each is critical to cellular functions and operates through separate signaling pathways that may explain differing effects of prostanoids. This study aimed to determine whether prostaglandin receptors EP2 and EP4 are modulated after injury and to evaluate the effect of prostaglandin E(2) (PGE(2)) addition and blockade on EP receptor expression. METHODS: Peripheral blood mononuclear cells (PBMCs) isolated from 10 patients sustaining fracture or burn injury and 10 control subjects were stimulated with lipopolysaccharide +/- NS-398, an inhibitor of PGE(2) production. Samples were evaluated for production of PGE(2), tumor necrosis factor--alpha, and leukotriene B(4) as well as mRNA expression of EP receptors and COX-2. EP receptor expression was also evaluated after treating control PBMCs with PGE(2). RESULTS: PBMCs from injured patients exhibited significant increases in PGE(2) production and COX-2 mRNA compared with control subjects, and these increases were inhibited by NS-398. In contrast, EP2 and EP4 receptors were markedly down-regulated after injury and NS-398 restored expression to control levels. Decreased EP2 and EP4 receptor expression after injury was replicated by coincubation of PBMCs with PGE(2). CONCLUSIONS: Specific PGE(2) receptors are down-regulated after injury and NS-398 reverses this response. Furthermore, PGE(2) mediates EP2 and EP4 down-regulation. These data suggest that specific EP receptor subtypes may provide critical targets for augmenting the immune response after injury in humans.

NS-398 treatment after trauma modifies NF-kappaB activation and improves survival.

Prostaglandin E(2) (PGE(2)) production after trauma contributes to immune alterations that increase susceptibility to infections. We hypothesize that blocking PGE(2) with NS-398, a selective COX-2 inhibitor, will modulate this response and improve outcome. This study evaluated the effect of NS-398 given over 7 days on proinflammatory cytokines, intracellular signaling, and survival after a septic challenge. Balb/C mice (n = 8/group) were given 10 mg/kg NS-398 intraperitoneally over 7 days, starting after anesthesia or trauma (femur fracture + 40% hemorrhage). Four groups, anesthesia + vehicle (C), anesthesia + NS-398 (CN), trauma + vehicle (T), or trauma + NS-398 (TN), were studied. On Day 7 after trauma, mice were sacrificed, serum was collected, and splenic macrophages were evaluated for PGE(2), LTB(4), IL-6, TNF-alpha, and NO production. Additionally, macrophage COX-2 mRNA, IkappaB-alpha, and NF-kappaB were evaluated. In a separate study, mice (n = 10-11/group) were traumatized and given NS-398 over 7 days, and then cecal ligation and puncture (CLP) were performed. Mice were then followed for survival over 10 days (via log-rank test). NS-398 treatment of injured mice decreased PGE(2) production compared to T (3.9 +/- 0.3 vs 3.1 +/- 0.4 pg/microg protein), and significantly decreased IL-6, NO, and TNF-alpha production. NS-398 treatment also attenuated COX-2 mRNA levels and NF-kappaB activation. These cellular events correlate with a significant survival advantage in TN versus T mice after CLP. These data suggest that a specific COX-2 inhibitor not only suppresses PGE(2), but normalizes proinflammatory cytokines after trauma through changes that may partly be mediated via transcriptional events. This correlates with significantly increased survival in TN mice given a septic challenge and suggests that COX-2 inhibitors contribute to modulating the inflammatory response and improving survival after trauma.

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.

Fixed bit-rate image compression using a parallel-structure multilayer neural network.

Picture compression algorithms, using a parallel structure of neural networks, have recently been described. Although these algorithms are intrinsically robust, and may therefore be used in high noise environments, they suffer from several drawbacks: high computational complexity, moderate reconstructed picture qualities, and a variable bit-rate. In this paper, we describe a simple parallel structure in which all three drawbacks are eliminated: the computational complexity is low, the quality of the decompressed picture is high, and the bit-rate is fixed.

Allergen-stimulated leukotriene B4 and interleukin-8 levels in patients with asthma and allergic rhinitis-modulation by a lipid pathway inhibitor.

BACKGROUND: Leukotriene B4 (LTB4), a potent chemokinetic mediator for neutrophils, is enhanced by interleukin-8 (IL-8) and may play a key role in the inflammatory response of asthma. OBJECTIVE: The aim of the present study was to investigate whether zileuton, a 5-lipoxygenase antagonist known to inhibit LTB4 production and recruitment of eosinophils/neutrophils in bronchoalveolar fluid, could affect the production of LTB4 and IL-8 by allergen-stimulated peripheral blood mononuclear cells in vitro from patients with asthma and/or allergic rhinitis. METHODS: Peripheral blood mononuclear cells were isolated using Ficoll-Hypaque density gradient from 14 subjects (2 with asthma, 11 with asthma and allergic rhinitis, and 1 with allergic rhinitis) and were stimulated by selected allergens (grass, tree, mite, and mold) in the absence or presence of 1 and 10 microM of zileuton. Supernatants were collected and assayed for LTB4 and IL-8 levels using RIA and ELISA, respectively. RESULTS: Levels of LTB4 were significantly elevated in peripheral blood mononuclear cells stimulated with mold, grass, and tree compared with the unstimulated control group (P<.05). Levels of IL-8 were significantly elevated in all allergen-stimulated peripheral blood mononuclear cells, except mold, compared with the unstimulated control group (P<.05). Zileuton significantly reduced production of LTB4 by mold and tree-stimulated peripheral blood mononuclear cells. By contrast, no effect of zileuton on IL-8 production was observed in allergen-stimulated peripheral blood mononuclear cells. CONCLUSIONS: The zileuton-induced attenuation of LTB4 production by allergen-stimulated peripheral blood mononuclear cells from patients with asthma and/or allergic rhinitis occurs independently from the allergen-stimulated IL-8 production.

Late phase response during nasal challenge: effect of astemizole on leukotriene B4 levels.

Nasal provocation (NP) in allergic rhinitis patients can elicit a late phase inflammatory response in which interleukins (IL), leukotrienes (LT), and neutrophils have been implicated. Certain antihistamines have been shown to have anti-inflammatory properties. The objective was to determine whether astemizole at 10 mgs/day has any anti-inflammatory characteristics. We clinically evaluated 20 patients with allergic rhinitis and measured nasal IL-8 and LTB4 during NP with increasing doses of grass and ragweed antigen in a double-blind placebo-controlled fashion after a 4-week course of treatment. Clinical symptom scores for sneezing, pruritus, and rhinorrhea were evaluated. Nasal fluid was examined by ELISA and RIA for IL-8 and LTB4 levels along with neutrophil assessment before NP and at 3, 6, and 8 hours. Symptom scores for nasal sneezing, pruritus, rhinorrhea, and nasal LTB4 levels at 6 and 8 hours and IL-8 at 3, 6, and 8 hours were generally lower in astemizole-treated patients compared to those on placebo. Nasal IL-8 levels corresponded to LTB4 levels at diluent and at 6 hours in the placebo group (P = 0.01). The percentage of neutrophils correlated with LTB4 levels at baseline, coefficient = 0.76, P = 0.02 and at 6 hours, coefficient = 0.62, P = 0.035 in the placebo group. This study is the first to demonstrate an effect of astemizole during NP on IL-8 and LTB4 levels with a significant correlation of neutrophil numbers in untreated patients during the nasal late phase response.

Hormone and metabolic profiles in children and adolescents with type I diabetes mellitus.

Diurnal concentrations of glucose, the major regulatory hormones, and selected biochemistries were measured serially throughout a 25-h period in 38 healthy type I diabetic patients, 25 patients with acute ketoacidosis, and 20 normal subjects. Poor glucose control, meal intolerance, and hypercortisolemia were the dominant abnormalities in the healthy diabetic subjects. Ketonemia due to elevated plasma beta-hydroxybutyrate concentrations without ketonuria (nitroprusside reaction) was a frequent finding in a group of poorly controlled diabetic subjects. In the patients with acute ketoacidosis, the dominant abnormalities were overproduction of epinephrine and cortisol. High glucagon and growth hormone concentrations were documented in about one-half of these patients. We conclude that (1) the hyperglycemia, meal intolerance, and abnormal ketone body metabolism seen in these patients are caused by inadequacies in their insulin regimens; (2) ketone body underutilization contributes to diabetic ketosis; (3) epinephrine and cortisol overproduction are important components of acute ketoacidosis; and (4) the complex hormone-metabolic interactions in type I diabetes can best be explained by a multihormonal hypothesis with the primary defect being loss of beta-cell function.

Elevated plasma beta-hydroxybutyrate concentrations without ketonuria in healthy insulin-dependent diabetic patients.

Plasma beta-hydroxybutyrate (beta-OHB) concentrations and simultaneous urine tests for ketonuria (nitroprusside reaction) were evaluated every 4 h throughout a 24-h study in 10 healthy insulin-dependent diabetics who had poor control based on home urine tests and elevated hemoglobin A1C. Concurrent measurements of the major carbohydrate regulatory hormones were made in the diabetic group and in a control population of 20 age-matched subjects. In the diabetics, 73% of the beta-OHB measurements were elevated. Only 43% of the abnormal beta-OHB values were associated with ketonuria. The diabetic subjects also showed exaggerated diurnal patterns for plasma beta-OHB and cortisol. There were no significant differences for the other regulatory hormones in the diabetic and normal groups. We conclude that 1) abnormal plasma beta-OHB levels without ketonuria are prevalent in poorly controlled diabetics; 2) negative nitroprusside tests for ketonuria underestimate the presence of ketonemia due to increased beta-OHB concentrations; 3) both insulin deficiency and glucocorticoid excess may influence ketone body metabolism in insulin-dependent diabetic patients.

Direct, fixed-time kinetic assays for beta-hydroxybutyrate and acetoacetate with a centrifugal analyzer or a computer-backed spectrophotometer.

In the course of studying the control of blood glucose in juvenile onset diabetics, we developed convenient methods for determining beta-hydroxybutyrate and acetoacetate. Here we describe fixed-time, enzymic, reaction-rate procedures for directly measuring these organic acids with a centrifugal analyzer (Rotochem IIA/36) or a computer-backed spectrophotometer (Gilford 102 system). In either case, the method requires only 20 micro L of plasma; is rapid, accurate, and precise; and analytical recovery is quantitative. Data are presented comparing results obtained with both instruments. Metabolic acidosis can be rapidly assessed and monitored with these methods, as illustrated by an example.

Detection of creatine kinase BB isoenzyme in sera of patients undergoing aortocoronary bypass surgery.

Creatine kinase BB isoenzyme (CK-BB) was detected intraoperatively in 22 of 25 patients undergoing aortocoronary bypass surgery, both in the coronary sinus and in the mixed venous blood. In a group of 10 patients in whom selective intracavitary profound hypothermic arrest was used, CK-BB values were lower than in another group of 10 patients, in whom controlled ventricular fibrillation with moderate total body hypothermia was instituted. This latter group also had higher levels of CK-MB. Patients who developed acute myocardial infarction immediately prior to or during the surgical intervention had the highest CK-BB values. This enzyme appeared as early as 15 minutes after the institution of cardiopulmonary bypass and disappeared within 6 hours. It is considered that part of the BB isoenzyme in serum of patients undergoing heart surgery is of myocardial origin.