EndoCAb Levels Research Articles

An assessment of potential biomarkers of environment enteropathy and its association with age and microbial infections among children in Bangladesh.

Interventional studies targeting environment enteropathy (EE) are impeded by the lack of appropriate, validated, non-invasive biomarkers of EE. Thus, we aimed to validate the association of potential biomarkers for EE with enteric infections and nutritional status in a longitudinal birth cohort study. We measured endotoxin core antibody (EndoCab) and soluble CD14 (sCD14) in serum, and myeloperoxidase (MPO) in feces using commercially available enzyme-linked immunosorbent assay (ELISA) kits. We found that levels of serum EndoCab and sCD14 increase with the cumulative incidence of enteric infections. We observed a significant correlation between the fecal MPO level in the children at 24 months of age with the total number of bacterial and viral infections, the total number of parasitic infections, and the total number of diarrheal episodes and diarrheal duration. We observed that the levels of serum EndoCab, sCD14, and fecal MPO at 3 months of age were significantly associated with whether children were malnourished at 18 months of age or not. Biomarkers such as fecal MPO, serum EndoCab and sCD14 in children at an early age may be useful as a measure of cumulative burden of preceding enteric infections, which are predictive of subsequent malnutrition status and may be useful non-invasive biomarkers for EE.

Validation of endotoxin-core antibodies in dried blood spots as a measure of environmental enteropathy and intestinal permeability.

To validate a method for measuring endotoxin-core antibodies (EndoCAb) from dried blood spots (DBS)-drops of capillary whole blood collected and dried on filter paper-as an indicator of environmental enteropathy (EE) in infancy and early childhood. A commercially available enzyme immunoassay kit was adapted for use with DBS, with optimized steps for sample elution. Technical validation included analysis of linearity/recovery, precision and reliability, lower limit of detection, and correspondence between matched plasma and DBS samples. Validation in a field-based setting was implemented with samples from Peruvian infants (n = 82; age = 2-33 months) collected at two time points six months apart. A high correspondence between plasma and DBS levels of EndoCAb was observed (R2 = 0.93, P < .001). The lower limit of detection was found to be 0.01 GMU/mL. Interassay coefficient of variation (CV) was 10.9% and 8.06% for low and high controls, respectively. Mean intra-assay CVs were 3.22% and 1.83%, respectively. In a sample of Peruvian infants, EndoCAb levels increased with age as expected (P < .001). Age explained nearly 34.6% of the variance in EndoCAb across the sample. These findings demonstrate the validity and feasibility of measuring EndoCAb in remote field settings using minimally invasive DBS sampling.

Comparative evaluation of microbial translocation products (LPS, sCD14, IgM Endocab) in HIV-1 infected Indian individuals

BackgroundMicrobial translocation of lipopolysaccharides (LPS), soluble CD14 (sCD14) and IgM Endocab levels have been reported to be associated with disease progression in HIV-1 infection. In this longitudinal study, plasma levels of different microbially translocated products (LPS, sCD14, Endocab) was investigated in HIV-1 infected Indian Individuals stratified as Rapid (R), Viremic slow (VS), Slow progressors (S) and healthy controls. MethodTen healthy and twenty HIV-1 infected individuals were enrolled. Plasma levels of LPS, sCD14, Endocab was examined using commercially available Limulus Amebocyte assay and enzyme-linked immunosorbent assay (ELISA) enzyme linked immunosorbant assay. ResultsElevated levels of sCD14, IgM EndoCab and LPS were observed during HIV-1 infection compared to healthy controls. Rapid progressors had higher levels of sCD14, IgM EndoCab, LPS (median% 1553, 3596, 202.2) compared to viremic slow, slow progressors and healthy controls both at baseline and follow up visits. At baseline, LPS correlated positively with IgM Endocab and negatively with sCD14 levels while at follow-up, significant positive correlation was observed between IgM Endocab and sCD14 (IgM EndoCab r = 0.490, p = 0.05; sCD14 r = 0.051, p = 0.830). Plasma levels of sCD14 correlated positively with viral load in rapid, viremic slow and slow progressors while CD + T cell count correlated positively with sCD14 and IgM EndoCab levels in viremic slow and slow progressors. ConclusionOur findings indicate that elevated levels of sCD14, IgM EndoCab and LPS in HIV-1 infected individuals are strong predictors of disease progression and could be considered as candidate biomarkers for disease monitoring.

Alcohol use predicts elevation in inflammatory marker soluble CD14 in men living with HIV

ABSTRACTIndependently, HIV infection and heavy alcohol use increase microbial translocation (MT) of gut products into systemic circulation. MT and consequent immune response have been linked to chronic inflammation and a host of negative health outcomes in individuals living with HIV. However, previous research has not systematically investigated the immune correlates of heavy drinking specifically within the HIV-positive population. This pilot study investigated MT and immune activation as a function of alcohol use in 21 HIV-positive men who met NIAAA criteria for heavy drinking. Participants averaged 46.7 ± 8.5 (mean ± standard deviation) years of age, 12.2 ± 9.2 years since HIV diagnosis, 337 ± 158 CD4 nadir, and 643 ± 245 current CD4 count. All participants were virologically suppressed on antiretroviral therapy. Data on alcohol use and immune function were collected at baseline and three-month follow-up. Plasma concentrations of markers of MT and immune activation (lipopolysaccharide (LPS), soluble CD14 (sCD14), endotoxin core antibody immunoglobulin M (EndoCAb)) were measured using enzyme-linked immunosorbent assays. Generalized estimating equation models tested alcohol use variables as predictors of LPS, sCD14, and EndoCAb levels. Greater quantity and frequency of drinking significantly predicted higher sCD14 levels (p’s < .01). Conversely, longer duration of abstinence from alcohol significantly predicted lower sCD14 levels (p < .001). These results remained significant after controlling for age, HIV duration, smoking status, current CD4 count, CD4 nadir, and antiretroviral drug type. In addition, participants with ≥50% relative reduction in drinks per week showed a significant decrease (p < .05) in sCD14 from baseline to three-month follow-up. This pilot study provides preliminary evidence that heavy drinking may increase a key inflammatory marker in HIV-infected individuals with suppressed infection.

Chronic Endotoxemia in Subjects with Type-1 Diabetes Is Seen Much before the Onset of Microvascular Complications.

BackgroundLipopolysaccharide (LPS)/Endotoxin is hypothesized to play an important role in chronic inflammation associated with Type-1 diabetes (T1DM) and its complications. Endotoxin core antibodies (EndoCAb), LPS binding protein (LBP) and soluble CD14 (sCD14) act as modulators of LPS induced activation of innate immune system in vivo. For the present study we estimated the levels of LPS and its translocation markers in T1DM subjects with and without microvascular complications (MVC) and correlate them with clinical parameters of T1DM and serum inflammatory cytokine levels (TNF-α, IL-6, IL-1β and GM-CSF).MethodsA total of 197 subjects (64 normal glucose tolerance (NGT) subjects, 97 T1DM subjects without MVC and 36 with MVC) were included in this study and the levels of serum LPS, its translocation markers and cytokines measured by immunoassays.ResultsCompared to NGT, T1DM subjects (both with and without MVC) had significantly higher levels of LPS, reduced levels of LBP and EndoCAb along with significant increase in the levels of IL-1β, IL-6, TNF-α and GM-CSF (p<0.05). No significant change was seen in the levels of these biomarkers between T1DM subjects with and without MVC.ConclusionsDecreased levels of EndoCAb and LBP suggest sustained endotoxin activity in T1DM subjects even before the onset of microvascular complications.

Plasma endotoxin core antibody concentration and linear growth are unrelated in rural Malawian children aged 2-5 years.

BackgroundEnvironmental enteropathy is subclinical inflammation of the upper gastrointestinal tract associated with reduced linear growth in developing countries. Usually investigators have used biopsy or a dual sugar absorption test to assess environmental enteropathy. Such tests are time and resource intensive, restricting their utility as screening methods. Serum endotoxin core antibody (EndoCab) concentration is a potential indicator of intestinal inflammation and integrity, and thus may be useful to predict environmental enteropathy. We analyzed the association of serum EndoCab levels versus linear growth and lactulose-mannitol assay results in 2–5 year old rural Malawian children.MethodsThis was an observational study of 388 rural, asymptomatic Malawian children who had anthropometric measurements taken at least every 3 months since birth. In June and July 2011, dual sugar permeability tests were performed and serum samples were drawn for EndoCab assays. Pearson correlation, Student’s t test and multivariable linear regression were used to compare ln EndoCab concentrations with height-for-age z scores (HAZ) at time of sampling and 3 months later. Identical analysis was also performed for ln EndoCab versus measurements from dual sugar permeability testing performed in conjunction with serum sampling. In a subgroup of children with anthropometric data in the months prior to serum sampling, Pearson correlation was used to estimate the relationship between ln EndoCab and recent linear growth.ResultsLn EndoCab concentrations were not correlated with HAZ at time of measurement (B = −0.078, P = 0.14) nor change in HAZ over the subsequent 3 months HAZ (B = −0.018, P = 0.27). EndoCab concentration was not associated with %lactulose excretion (B < 0.001, P = 0.98) nor the lactulose:mannitol ratio (B = 0.021, P = 0.62). Subgroup analysis also did not reveal any significant association between EndoCab and recent growth.ConclusionEndoCab titers were not correlated with measurements of growth or intestinal permeability in rural pre-school aged Malawian children.

Association of microbial translocation biomarkers with clinical outcome in controllers HIV-infected patients

A proportion of patients who spontaneously control viral load (controllers) experienced clinical progression. We hypothesized that microbial translocation would independently determine the rate of disease progression in controllers. sCD14, lipopolysaccharide-binding protein (LBP) and EndoCab levels were assessed in 114 antiretroviral-naive patients with CD4(+) T cells above 500 cells/μl (including 63 controllers and 51 noncontrollers). The independent predictive value of these markers on time to progression to the combined endpoint of AIDS, non-AIDS event, initiation of combination antiretroviral therapy (cART) or CD4(+) cell count less than 500 cells/μl was assessed using a Cox regression model. Most of the patients progressed to a combined endpoint (60%). Clinical progression in controllers was significantly lower than in noncontrollers (P = 0.02). Controllers with lower than the median baseline CD4(+) T-cell count and higher than the median baseline viral load, sCD14 and EndoCab levels had a worse prognosis (P < 0.0001, P = 0.007, P = 0.05 and P = 0.012), while noncontrollers with higher than the median baseline LBP level also had a worse prognosis (P = 0.019). sCD14 and LBP increased and EndoCab decreased over time [from baseline (median values: 1486, 17604 ng/ml and 68 MMU/ml, respectively, to the date of event or the last determination (median values: 1663, 20230 ng/ml and 49 MMU/ml), respectively] in controllers (P = 0.04, 0.08 and 0.0006, respectively). Microbial translocation seems to be an important determinant of clinical progression in HIV-infected controllers independently of viremia. Measures to improve the intestinal mucosa damage or decrease translocation could influence the outcome in these patients.

Stunting is characterized by chronic inflammation in Zimbabwean infants.

BackgroundStunting affects one-third of children in developing countries, but the causes remain unclear. We hypothesized that enteropathy leads to low-grade inflammation, which suppresses the growth hormone-IGF axis and mediates stunting.MethodsWe conducted a case-control study of 202 HIV-unexposed Zimbabwean infants who were stunted (height-for-age Z-score (HAZ) <−2; cases) or non-stunted (HAZ >−0.5; controls) at 18 months. We measured biomarkers of intestinal damage (I-FABP), inflammation (CRP, AGP, IL-6) and growth hormone-IGF axis (IGF-1, IGFBP3) in infant plasma at 6 weeks and 3, 6, 12 and 18 months, and in paired maternal-infant plasma at birth. Adjusted mean differences between biomarkers were estimated using regression models. Multivariate odds ratios of stunting were estimated by logistic regression.ResultsAt birth, cases were shorter (median (IQR) HAZ −1.00 (−1.53, −0.08) vs 0.03 (−0.57, 0.62,); P<0.001) than controls and their mothers had lower levels of IGF-1 (adjusted mean difference (95%CI) −21.4 (−39.8, −3.1) ng/mL). From 6 weeks to 12 months of age, levels of CRP and AGP were consistently higher and IGF-1 and IGFBP3 lower in cases versus controls; IGF-1 correlated inversely with inflammatory markers at all time-points. I-FABP increased between 3–12 months, indicating extensive intestinal damage during infancy, which was similar in cases and controls. In multivariate analysis, higher log10 levels of CRP (aOR 3.06 (95%CI 1.34, 6.99); P = 0.008) and AGP (aOR 7.87 (95%CI 0.74, 83.74); P = 0.087) during infancy were associated with stunting. There were no associations between levels of I-FABP, IL-6, sCD14 or EndoCAb and stunting.ConclusionsStunting began in utero and was associated with low maternal IGF-1 levels at birth. Inflammatory markers were higher in cases than controls from 6 weeks of age and were associated with lower levels of IGF-1 throughout infancy. Higher levels of CRP and AGP during infancy were associated with stunting. These findings suggest that an extensive enteropathy occurs during infancy and that low-grade chronic inflammation may impair infant growth.

Markers of microbial translocation and risk of AIDS-related lymphoma

Depletion of gut-associated lymphocytes by HIV infection facilitates microbial translocation, which may contribute to non-Hodgkin lymphoma (NHL) risk via chronic immune activation and B-cell hyperstimulation. We therefore examined associations of four microbial translocation markers with subsequent NHL risk in a case-control study nested within four prospective cohort studies of HIV-infected individuals. Prediagnostic blood specimens for 56 NHL cases and 190 controls matched for age, sex, race, specimen type, cohort, and CD4 T-cell count were tested for the endotoxin lipopolysaccharide (LPS), antiendotoxin core antibody (EndoCab), LPS-binding protein (LBP), and soluble CD14 (sCD14). Elevated levels of sCD14 were associated with significantly increased NHL risk [odds ratio (OR) 2.72 (95% confidence interval [95% CI] 1.29-5.76)]. In subgroup analyses, elevated LPS levels were also associated with significantly increased NHL risk [OR 3.24 (95% CI 1.10-9.53)]. EndoCab and LBP levels were not associated with NHL risk. The association of sCD14 and LPS with NHL risk supports an etiologic role for gut microbial translocation in lymphomagenesis among HIV-infected individuals. Additional studies with larger sample sizes are needed to confirm these observations.

Increased Levels of Endotoxin Core Antibodies and Decreased Levels of sCD 14 Indicate Chronic Endotoxemia in Coronary Artery Disease (CURES-127)

Introduction: Endotoxin is hypothesized to play an important role in chronic inflammation associated with coronary artery disease (CAD). The activity of the endotoxin is determined by the relative levels of endotoxin core antibodies (EndoCab), LPS binding protein (LBP) and soluble CD14 (sCD14). Towards this end, we estimated EndoCab, LBP and sCD14 levels in subjects with CAD and correlated them with clinical parameters, serum hormones and cytokine levels. Methods: The study subjects were recruited from Chennai Urban Rural Epidemiology Study (CURES). Age and gender matched subjects with (n=46) and without (n=45) CAD were selected from Phase III of the study. The levels of serum lipopolysaccharide (LPS), EndoCab and its translocation markers (sCD14 and LBP) along with insulin, glucagon, adiponectin and leptin and pro-inflammatory cytokines such as TNF-α, IL-6 and IL-1β were measured by immuno-assays. Results: Quartile analysis showed significantly higher percentage of CAD subjects in the highest quartile of EndoCab (>26.6 EMU/ml) (CAD-24% Vs Controls 0%) and LPS (>65.05 EU/ml) (CAD-21% vs. Controls 4%), while a reverse trend was seen for sCD14 (>2198398.7 ng/ml) (CAD-1% vs. Control-24%) (p<0.01). LBP levels were not statistically different between the groups. While EndoCab levels showed positive association with LPS, LBP, sCD14, hsCRP, HOMA-IR and glucagon, sCD14 showed a negative association with most of these markers. Significant increase in the levels of pro inflammatory cytokines TNFα, IL-6 and IL-1β, was also observed in the CAD group when compared to the control. Conclusions: Significantly elevated levels of EndoCab and decreased levels of sCD14 indicate chronic endotoxin exposure in CAD subjects.

Effects of Decreased Preoperative Endotoxin Core Antibody Levels on Long-term Mortality After Coronary Artery Bypass Graft Surgery

Decreased preoperative levels of antiendotoxin core antibody (EndoCAb) in patients undergoing cardiac surgery with cardiopulmonary bypass are associated with increased long-term mortality. Observational study. Academic medical center. A total of 474 patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass. Preoperative serum IgM EndoCAb levels were determined, and established preoperative risk factors were assessed. Patients were assigned a risk score using a validated method. The primary end point was mortality. Statistical analysis used the Cox proportional hazards regression model with log EndoCAb as the predictor of interest and Parsonnet additive risk score as a covariate. Kaplan-Meier survival curves were generated to visually compare groups with high vs low EndoCAb levels. Forty-six deaths occurred in 5 years. Annual follow-up rates during the 5 years were 100%, 94%, 93%, 98%, and 98% for the 1-, 2-, 3-, 4-, and 5-year periods, respectively. Parsonnet additive risk score (hazard ratio, 1.07; 95% confidence interval [CI], 1.04-1.11; P < .001) and log EndoCAb (hazard ratio, 0.73; 95% CI, 0.53-0.99; P = .04) were independent predictors of long-term mortality in the final model. Kaplan-Meier analysis revealed that the preoperative EndoCAb level was significantly associated with mortality up to 5 years (P = .01 by log-rank test). Lower preoperative serum EndoCAb level is a significant predictor of long-term mortality independent of other known risk factors.

Endotoxin immunity and the developmentof the systemic inflammatory responsesyndrome in critically ill children

The systemic inflammatory response syndrome (SIRS) may be triggered by endotoxin. Humans have antibodies directed against the core of endotoxin (endotoxin core antibodies, EndoCAb) that appear to be protective following surgery and in sepsis. We hypothesised that children with elevated antibodies to endotoxin core would be less likely to develop SIRS in their initial period on intensive care. Because of the existing literature we defined two sub-groups according to the primary reason for ICU admission: infection and non-infection. We recruited 139 consecutive patients admitted to a paediatric intensive care unit (PICU) with more than one organ failure for longer than 12 h as part of another study. Patients were classified on admission to PICU as having an infectious or a non-infections diagnosis. The occurrence of SIRS within 48 h of admission was recorded along with detailed clinical and demographic data, EndoCAb concentration and the potential confounding variables C-reactive protein and mannose-binding lectin. In the 71 patients admitted without infection (primarily post-operative and head injured) IgG EndoCAb was significantly lower in patients who developed SIRS than those who did not (72 vs. 131 MU/ml), independent of potential confounding variables. In patients with infection there was no significant difference in IgG EndoCAb between children developing SIRS and those who did not (111 vs. 80 MU/ml). Head injured and post-operative patients admitted to PICU who develop early SIRS have significantly lower serum IgG EndoCAb levels than those who do not.

A descriptive study of the variation in baseline levels of anti-endotoxin core antibodies between US and UK populations

Low levels of naturally occurring antibodies to the core section of endotoxin (EndoCAb) have been shown to be predictors of poor outcome following major surgery. We performed a retrospective study comparing pre-operative levels in US surgical patients, UK surgical patients and healthy volunteers. Both IgM and IgG EndoCAb levels were higher in the US surgical patients when compared with the other groups (approximately twice as high in the case of IgG EndoCAb). This may reflect genetic or environmental variability between the patient groups, differences in the disease processes, the disparity in the delivery of health care between the two countries or degradation of the samples in transfer.

Lower endotoxin immunity predicts increased cognitive dysfunction in elderly patients after cardiac surgery.

Although coronary artery bypass graft surgery (CABG) improves the quality of life and functional capacity for numerous patients, many also exhibit impairment in cognitive function immediately after surgery. Although the etiology of this cognitive decline is multifactorial, the inflammatory response to the primary insult may modulate the extent of dysfunction. Patients with low preoperative levels of anti-endotoxin core antibody (EndoCAb) are more likely to experience adverse outcomes, suggesting that decreased immunity to endotoxin causes a heightened release of inflammatory mediators. We therefore sought to determine the association of decreased EndoCAb and the incidence of postoperative cognitive decline. EndoCAb levels were measured before surgery in 460 patients undergoing elective CABG. Cognitive function was measured preoperatively and 6 weeks postoperatively. Multivariable analysis accounted for the effects of age, Parsonnet score, sex, body mass index, baseline cognition, years of education, history of hypertension, bypass time, cross-clamp time, and number of grafts. At 6-week follow-up, 122 patients (36%) showed cognitive decline. Lower preoperative EndoCAb levels were associated with a greater incidence and severity of postoperative cognitive decline. The elderly with decreased endotoxin immunity are particularly susceptible to this decline (relative risk=1.97 for age >64). Reduced preoperative endotoxin immunity is a predictor of increased postoperative cognitive dysfunction in patients undergoing CABG, particularly in those >60 years old. Interventions that increase IgM EndoCAb levels might improve cognitive function after cardiac surgery.

Regional variation in anti-endotoxin core antibody levels in healthy and preoperative surgical populations

Endotoxin has a central role in sepsis and organ dysfunction after surgery. Levels of one of our natural defences against endotoxin, antibodies to endotoxin core (EndoCAb), are independent predictors of postoperative outcome [1]. There is a heterogeneity in EndoCAb levels between European and North American healthy donor populations that remains unexplained [2].

Intestinal Hypoperfusion Contributes to Gut Barrier Failure in Severe Acute Pancreatitis

Intestinal barrier failure and subsequent bacterial translocation have been implicated in the development of organ dysfunction and septic complications associated with severe acute pancreatitis. Splanchnic hypoperfusion and ischemia/reperfusion injury have been postulated as a cause of increased intestinal permeability. The urinary concentration of intestinal fatty acid binding protein (IFABP) has been shown to be a sensitive marker of intestinal ischemia, with increased levels being associated with ischemia/reperfusion. The aim of the current study was to assess the relationship between excretion of IFABP in urine, gut mucosal barrier failure (intestinal hyperpermeability and systemic exposure to endotoxemia), and clinical severity. Patients with a clinical and biochemical diagnosis of acute pancreatitis were studied within 72 hours of onset of pain. Polyethylene glycol probes of 3350 kDa and 400 kDa were administered enterally, and the ratio of the percentage of retrieval of each probe after renal excretion was used as a measure of intestinal macromolecular permeability. Collected urine was also used to determine the IFABP concentration (IFABP-c) and total IFABP (IFABP-t) excreted over the 24-hour period, using an enzyme-linked immunosorbent assay technique. The systemic inflammatory response was estimated from peak 0 to 72-hour plasma C-reactive protein levels, and systemic exposure to endotoxins was measured using serum IgM endotoxin cytoplasmic antibody (EndoCAb) levels. The severity of the attack was assessed on the basis of the Atlanta criteria. Sixty-one patients with acute pancreatitis (severe in 19) and 12 healthy control subjects were studied. Compared to mild attacks, severe attacks were associated with significantly higher urinary IFABP-c (median 1092 pg/ml vs. 84 pg/ml; P < 0.001) and IFABP-t (median 1.14 μg vs. 0.21 μg; P = 0.003). Furthermore, the control group had significantly lower IFABP-c (median 37 pg/ml; P = 0.029) and IFABP-t (median 0.06 μg; P = 0.005) than patients with mild attacks. IFABP correlated positively with the polyethylene glycol 3350 percentage retrieval ( r = 0.50; P < 0.001), CRP ( r = 0.51; P < 0.001), and inversely with serum IgM EndoCAb levels ( r = −0.32; P = 0.02). The results of this study support the hypothesis that splanchnic hypoperfusion contributes to the loss of intestinal mucosal integrity associated with a severe attack of pancreatitis. ( J Gastrointest Surg 2003;7:26–36.)

Methotrexate induces dose-dependent gut mucosal barrier dysfunction in an experimental animal model

MTX induces small bowel mucositis resulting in a dose-related increase in intestinal permeability. The disrupted gut mucosal barrier allows endotoxin translocation as evidenced by elevated endotoxin levels and falling EndoCAb levels with increasing MTX dose.

Endotoxin-neutralizing capacity of serum from cardiac surgical patients

Objective: To determine if endotoxin core antibody (EndoCAb) from the serum of cardiac surgical patients neutralizes endotoxin in an ex vivo biologic assay. Design: Prospective blinded cohort study. Setting: Academic medical center. Participants: Patients (n = 203) undergoing cardiac surgery. Interventions: Sera were obtained from patients preoperatively. Measurements and Main Results: EndoCAb levels were determined by enzyme-linked immunosorbent assay. Sera were incubated for 15 minutes at 37°C with varying concentrations of endotoxin from a clinically relevant bacterium (Escherichia coli serotype O18), then tested for the presence of endotoxin activity using the validated Limulus amebocyte lysate assay. Median (interquartile range) IgM and IgG EndoCAb levels were 118 median units (range, 31 to 259 median units) and 208 median units (range, 108 to 401 medium units). Increasing levels of IgM EndoCAb were associated with increased neutralization of endotoxin (p < 0.0001). Increasing levels of IgG EndoCAb were associated with increased neutralization of endotoxin (p < 0.0001). An additive effect of IgM and IgG EndoCAb levels on endotoxin neutralization was observed without evidence of synergistic or plateau effects. EndoCAb levels did not completely predict serum neutralization capacity. Conclusion: Anti-EndoCAbs of both classes (IgM and IgG) were able to neutralize lipopolysaccharide from a clinically relevant bacterium in an ex vivo model. Neither Igm nor IgG appeared to be more capable of neutralization in this model. These antibodies did not completely predict neutralization capacity; other endogenous factors in human serum must be capable of lipopolysaccharide neutralization. Copyright © 2001 by W.B. Saunders Company

ANTI-ENDOTOXIN NEUTRALIZING ACTIVITY OF SERUM IN PATIENTS PRIOR TO CARDIAC SURGERY

Introduction: Low preoperative serum Anti-Endotoxin Core Antibody (EndoCAb) levels have been shown to be an independent predictor of postoperative complications over and above the effects of known preoperative risk factors and total immunoglobulin levels. [1,2] We tested the hypothesis that higher EndoCAb levels are associated with a greater degree of neutralization of a common clinical serotype of E. coli endotoxin using a standard in vitro assay. Methods: Following IRB approval, patients undergoing CABG and/or valvular heart surgery were enrolled. A preoperative serum sample was obtained from these patients prior to anesthetic induction. Serum was assayed for IgG and IgM EndoCAb using a standard ELISA technique. [3] The endotoxin neutralization assay was conducted by incubating a serum sample with a known quantity of E. coli O18 endotoxin for 15 minutes at 37[degree sign]C. Residual endotoxin activity in the serum/endotoxin mixture was subsequently measured using the standard gel clot Limulus Amebocyte Lysate assay (Associates of Cape Cod, MA). Associations between IgG EndoCAb, IgM EndoCAb, and degree of neutralization were tested using logistic regression. Results: Serum samples from 203 patients were studied. EndoCAb levels were expressed as median units (MU) by convention and were (range, median, mean): IgM Class (12-1882, 118, 243), IgG Class (18-1232, 208, 271). There was a positive association between higher IgM EndoCAb level and greater endotoxin neutralization (OR 1.004 per MU increase, p<0.0001). There was a positive association between higher IgG EndoCAb level and greater endotoxin neutralization (OR 1.005 per MU increase, p<0.0001). These factors were additive in the model and there was no statistical evidence of a synergistic effect or of a "plateau" effect. Conclusions: Patients with elevated EndoCAB levels prior to surgery were shown to contain serum with more effective endotoxin neutralizing properties against the endotoxin from a common clinical isolate of E. coli. This finding may account in part for studies which have shown that low preoperative EndoCAB levels are associated with increased complications following cardiac surgery. [1,2] A randomized, blinded clinical trial is currently underway to determine if preoperative administration of EndoCAb to cardiac surgical patients results in improved postoperative outcome.

Relationship Between Preoperative Endotoxin Immune Status, Gut Perfusion, and Outcome From Cardiac Valve Replacement Surgery

Endotoxin is a powerful trigger of systemic inflammation. Since cardiac surgery exposes patients to endotoxemia, this study was set up to define the relationship between preoperative endogenous endotoxin immune status, gut perfusion, and outcome following cardiac valve replacement surgery. Observational study. University hospital. Fifty-nine consecutive patients undergoing cardiac valve replacement. Blood was assayed for IgG and IgM endotoxin core antibody (EndoCAb) levels preoperatively, immediately postoperatively, and at 4 h and 24 h postoperatively. Intraoperative gut mucosal perfusion was assessed using gastric tonometry. Complications were assessed for groups above and below the median EndoCAb value of a healthy population (100 median units micro/mL). Of the 59 patients, 12 developed at least one of a set of predefined complications. Of these 12, all had preoperative levels of IgM EndoCAb below 100 MU/mL (p<0.025). Eleven had IgG EndoCAb levels below 100 MU/mL (0.05<p<0.1). There was no relationship between the fall in gastric intramucosal pH and exposure to endotoxin as implied by the fall in unbound IgM EndoCAb levels, although the specificity of tonometry for predicting complications could be improved by considering the patient's preoperative EndoCAb status. Preoperative EndoCAb levels were related to poor outcome following cardiac surgery and may be used to improve the specificity of GI tonometry in predicting postoperative complications.