The effects of 3-hydroxybutyrate and glucose on human T cell responses to Candida albicans

Gut mycobiome dysbiosis after sepsis and trauma

BACKGROUND

Sepsis and trauma are known to disrupt gut bacterial microbiome communities, but the impacts and perturbations in the fungal (mycobiome) community after severe infection or injury, particularly in patients experiencing chronic critical illness (CCI), remain unstudied.

METHODS

We assess persistence of the gut mycobiome perturbation (dysbiosis) in patients experiencing CCI following sepsis or trauma for up to two-to-three weeks after intensive care unit hospitalization.

RESULTS

We show that the dysbiotic mycobiome arrays shift toward a pathobiome state, which is more susceptible to infection, in CCI patients compared to age-matched healthy subjects. The fungal community in CCI patients is largely dominated by Candida spp; while, the commensal fungal species are depleted. Additionally, these myco-pathobiome arrays correlate with alterations in micro-ecological niche involving specific gut bacteria and gut-blood metabolites.

CONCLUSIONS

The findings reveal the persistence of mycobiome dysbiosis in both sepsis and trauma settings, even up to two weeks post-sepsis and trauma, highlighting the need to assess and address the increased risk of fungal infections in CCI patients.

Effects of diabetes mellitus vs. in vitro hyperglycemia on select immune cell functions

Diabetes mellitus (DM), one of the commonest metabolic disorders, can impair the function of cells involved in cellular and/or humoral immunity. This study sought to define potential effects upon cell-mediated immune cells due to an acute hyperglycemic state (in vitro) for comparison against those that might be attributable to a diabetic phenotype itself. Peripheral blood mononuclear cells (PBMC) were isolated from ten diabetic patients (5 with Type I disease and 5 with Type II) and 10 healthy controls. The cells were then challenged with 1 of 3 different mitogens (concanavalin A, phytohemagglutinin, pokeweed mitogen) in the presence of differing glucose concentrations (0, 100, 200, 400, or 800 mg/dl), and proliferative responses assessed. Neutrophils (PMNC) from the blood samples, exposed to the same experimental conditions, were analyzed for respiratory burst activity using nitroblue tetrazolium. The results indicated that there was significant inhibition of the proliferative responses to mitogens among the stimulated PBMC and in respiratory burst activity among the PMNC obtained from the diabetic patients. However, these effects were not affected by either the added presence of increasing amounts of exogenous glucose, the type of diabetes the patients had, the length of time the patient had had the disease, or whether or not the patients had been receiving insulin treatments. In contrast, the PBMC from healthy individuals appeared to display dose-trend decreases in responsiveness to mitogens; interestingly, similar effects on their PMNC were not evident. It was thus concluded that in situ ongoing repeated hyperglycemic states caused changes in cells of the immune system that could have been caused by repeated "continuous" exposures to excess sugar. Further studies are needed to more clearly identify hyperglycemia (sugar)-sensitive targets on/in these cells that could contribute to the appearance of the diabetic immunodeficiency in these types of patients.

Clinical consequences of hyperglycemia during remission induction therapy for pediatric acute lymphoblastic leukemia

Hyperglycemia adversely affects outcome in adult patients with acute lymphoblastic leukemia (ALL), but its impact on children with this disease is unknown. We evaluated the relationship between hyperglycemia during remission induction therapy and clinical outcomes among pediatric patients with ALL. We reviewed the records of patients enrolled on four consecutive ALL protocols (Total Therapy protocols XIIIA, XIIIB, XIV and XV) at St Jude Children's Research Hospital from 1991 to 2007 and identified those who experienced hyperglycemia (glucose >or=200 mg per 100 ml) during remission induction. Complete remission (CR) rates at the end of induction, event-free survival (EFS), overall survival (OS), cumulative incidence of relapse and occurrence of infections were compared between those who did and did not experience hyperglycemia. Of 871 patients analyzed, 141 (16%) experienced hyperglycemia during remission induction. Patients with hyperglycemia were significantly older than the other patients (P<0.0001). There was no significant difference in CR rate (P=0.92), EFS (P=0.80), OS (P=0.28), cumulative incidence of relapse (P=0.59) or in the probability or types of infection between patients who did and did not experience hyperglycemia. Pediatric patients with or without hyperglycemia during remission induction for ALL have similar clinical outcome. Occurrence of hyperglycemia does not warrant alteration of the antileukemic regimen.

Intensive insulin therapy is associated with reduced infectious complications in burn patients

BACKGROUND

Intensive insulin therapy to control blood glucose levels has reduced mortality in surgical, but not medical, intensive care unit (ICU) patients. Control of blood glucose levels has also been shown to reduce morbidity in surgical ICU patients. There is very little data for use of intensive insulin therapy in the burn patient population. We sought to evaluate our experience with intensive insulin therapy in burn-injured ICU patients with regard to mortality, morbidity, and use of hospital resources.

STUDY DESIGN

Burn patients admitted to our American College of Surgeons verified burn center ICU from 7/1/2004 to 6/30/2006 were studied. An intensive insulin therapy protocol was initiated for ICU patients admitted starting 7/1/2005 with a blood glucose target of 100-140 mg/dL. The 2 groups of patients studied were control (7/1/2004 to 6/30/2005) and intensive insulin therapy (7/1/2005 to 6/30/2006). All glucose values for the hospitalization were analyzed. Univariate and multivariate analyses were performed.

RESULTS

Overall, 152 ICU patients admitted with burn injury were available for study. No difference in mortality was evident between the control and intensive insulin therapy groups. After adjusting for patient risk, the intensive insulin therapy group was found to have a decreased rate of pneumonia, ventilator-associated pneumonia, and urinary tract infection. In patients with a maximum glucose value of greater than 140 mg/dL, the risk for an infection was significantly increased (OR 11.3, 95% CI 4-32, P-value < .001). The presence of a maximum glucose value greater than 140 mg/dL was associated with a sensitivity of 91% and specificity of 62% for an infectious complication.

CONCLUSION

Intensive insulin therapy for burn-injured patients admitted to the ICU was associated with a reduced incidence of pneumonia, ventilator-associated pneumonia, and urinary tract infection. Intensive insulin therapy did not result in a change in mortality or length of stay when adjusting for confounding variables. Measurement of a blood glucose level greater than 140 mg/dL should heighten the clinical suspicion for the presence of an infection in patients with burn injury.

Effect of supplemental l-arginine on the function of T lymphocytes and the formation of advanced glycosylated end products in rats with streptozotocin-induced diabetes

OBJECTIVE

We investigated the effect of supplemental L-arginine on lymphocyte function in diabetes and its association with suppressed formation of advanced glycosylated end products (AGEs).

METHODS

For the in vivo study, rats with streptozotocin-induced (65 mg/kg of body weight, intravenously) diabetes were treated with or without 2% L-arginine or glycine (as a positive control) in drinking water for 8 wk. We then measured serum fructosamine concentrations and concanavalin A-induced proliferative ability of lymphocytes from these animals. For the in vitro study, AGEs derived from albumin were prepared by incubating D-glucose (200 mmol/L) and bovine serum albumin (100 mg/mL) at 37 degrees C for 2 wk in the presence or absence of L-arginine (0.1-10 mmol/L). These preparations were quantified for their bovine serum albumin--derived AGE content, and their effect on concanavalin A-induced proliferative activity of T lymphocyte from normal rats was measured.

RESULTS

Serum fructosamine concentrations were significantly higher in the diabetic rats than in the control rats (P<0.05) but were significantly lowered with L-arginine supplementation (P<0.05). The lower lymphocyte proliferation rate found in the diabetic rats was reversed by supplemental L-arginine (P<0.05). During the course of incubation of bovine serum albumin with D-glucose, the presence of L-arginine prevented the formation of bovine serum albumin-derived AGEs and attenuated their inhibitory effect on the rate of lymphocyte proliferation in a dose-dependent manner.

CONCLUSION

Supplemental L-arginine improved the function of T lymphocytes in diabetic rats in association with decreased formation of AGEs.

Influence of acute hyperglycemia in human sepsis on inflammatory cytokine and counterregulatory hormone concentrations

AIM: In human sepsis, a prominent component of the hypermetabolite is impaired glucose tolerance (IGT) and hyperglycemia. Elevations in plasma glucose concentration impair immune function by altering cytokine production from macrophages. We assessed the role of glucose in the regulation of circulating levels of insulin, glucagon, cortisol, IL-6 and TNF-α in human sepsis with normal or impaired glucose tolerance.

METHODS: According to the results of intravenous glucose tolerance test, forty patients were classified into two groups: control group (n = 20) and IGT group (n = 20). Plasma glucose levels were acutely raised in two groups and maintained at 15 mmol/L for 3 hours. Plasma insulin, glucagon and cortisol levels were measured by radioimmunoassay, the levels of TNF-α and IL-6 were detected by ELISA.

RESULTS: In IGT group, the fasting concentrations of plasma glucose, insulin, glucagon, cortisol, IL-6 and TNF-α levels were significantly higher than those in control group (P < 0.05). During clamp, the control group had a higher average amount of dextrose infusion than the IGT group (P < 0.01). In control group, plasma insulin levels rose from a basal value to a peak at an hour (P < 0.05) and maintained at high levels. Plasma glucagon levels descended from a basal value to the lowest level within an hour (P < 0.01) and low levels were maintained throughout the clamp. In IGT group, plasma insulin was more significantly elevated (P < 0.01), and plasma glucagon levels were not significantly declined. Plasma cortisol levels were not significantly changed in two groups. In control group, plasma IL-6 and TNF-α levels rose (P < 0.01) within 2 hours of the clamp and returned to basal values at 3 hours. In IGT group, increased levels of plasma cytokine lasted longer than in control group (3 hours vs. 2 hours, P < 0.05), and the cytokine peaks of IGT group were higher (P < 0.05) than those of control group.

CONCLUSION: Acute hyperglycemia pricks up hyperinsulinemia and increases circulating cytokine concentrations and these effects are more pronounced in sepsis with IGT. This suggests a potential modulation of immunoinflammatory responses in human sepsis by hyperglycemia.

Hyperglycemia exacerbates muscle protein catabolism in burn-injured patients

OBJECTIVE

The purpose of this study was to assess if hyperglycemia influences energy expenditure or the extent of muscle protein catabolism in severely burned adults.

DESIGN

Retrospective study.

SETTING

Burn intensive care unit at a university hospital.

PATIENTS

Adults with burns on >/=40% of their body surface area.

INTERVENTIONS

Simultaneous measurement of indirect calorimetry and leg net balance of phenylalanine (as an index of muscle protein catabolism). Patients were stratified by plasma glucose values at the time of metabolic measurements (i.e., normal, glucose at </=130 mg/dL; mild hyperglycemia, glucose at 130-200 mg/dL; severe hyperglycemia, glucose at >200 mg/dL).

MEASUREMENTS AND MAIN RESULTS

Normal (n = 9; plasma glucose, 109 +/- 13 mg/dL [mean +/- sd]), mildly hyperglycemic (n = 13l plasma glucose, 156 +/- 17 mg/dL), and severely hyperglycemic subjects (n = 7, glucose 231 +/- 32 mg/dL) were similar in age, body weight, extent of burn area, and daily caloric intake. Severe hyperglycemia was associated with significantly higher arterial concentrations of phenylalanine (normal, 0.079 +/- 0.027 micromol/L; severe hyperglycemia, 0.116 +/- 0.028; p <.05) and a significantly greater net efflux of phenylalanine from the leg (normal, -0.067 +/- 0.072 micromol.min(-1).100 mL(-1) leg volume; severe hyperglycemia, -0.151 +/- 0.080 micromol.min(-1).100 mL(-1) leg volume; p <.05). Resting energy expenditure and respiratory quotient were similar between patient groups.

CONCLUSIONS

These findings demonstrate an association between hyperglycemia and an increased rate of muscle protein catabolism in severely burned patients. This suggests a possible link between resistance of muscle to the action of insulin for both glucose clearance and muscle protein catabolism.

Association of hyperglycemia with increased mortality after severe burn injury

BACKGROUND

Hyperglycemia is commonly associated with the hypermetabolic stress response. However, persistent hyperglycemia may adversely affect wound healing and immunity. The purpose of this study was to assess any relationship between hyperglycemia and clinical outcome after severe burn injury.

METHODS

Survey of the medical records from January 1996 to July 1999 identified 58 pediatric patients with burns > or = 60% body surface. Patients were categorized as having poor glucose control (n = 33) if > or = 40% of all plasma glucose determinations were > or = 7.8 mmol/L (140 mg/dL) and compared with patients deemed to have adequate glucose control (n = 25) in whom > or = 40% of all glucose values were > or = 7.8 mmol/L.

RESULTS

Despite similar age, burn size, caloric intake, and frequency of wound infection, patients categorized with poor glucose control had a significantly greater incidence of positive blood cultures (positive blood cultures/length of stay days, 0.42 +/- 0.04 for hyperglycemia patients vs. 0.30 +/- 0.03 for normoglycemia patients; mean +/- SEM, p > or = 0.05). This finding was especially prominent for blood cultures positive for yeast. Hyperglycemia patients had significantly less percentage of skin graft take than did the normoglycemic patients (percent take/operative procedure, 64 +/- 9 for hyperglycemia patients vs. 88 +/- 5 for normoglycemia patients; p < 0.05). Nine patients (27%) with persistent hyperglycemia died compared with only one death (4%) in patients with adequate glucose control (p > or = 0.05).

CONCLUSION

This association between poor glucose control, bacteremia/fungemia, reduced skin graft take, and subsequent mortality in severely burned children may be related to a hyperglycemia-induced detriment in antimicrobial defense. Although this report fails to establish cause and effect, these findings suggest that aggressive maneuvers to normalize plasma glucose in critically injured patients may be warranted.