Up-regulation of Fas ligand (FasL) mRNA expression in peripheral blood mononuclear cells (PBMC) after major surgery

Sterile post-traumatic immunosuppression

After major trauma, the human immune system initiates a series of inflammatory events at the injury site that is later followed by suppression of local inflammation favoring the repair and remodeling of the damaged tissues. This local immune response involves complex interactions between resident cells such as macrophages and dendritic cells, soluble mediators such as cytokines and chemokines, and recruited cells such as neutrophils, monocytes and mesenchymal stromal cells. If of sufficient magnitude, these initial immune responses nevertheless have systemic consequences resulting in a state called post-traumatic immunosuppression (PTI). However, controversy exists regarding the exact immunological changes occurring in systemic compartments triggered by these local immune responses. PTI is one of the leading causes of post-surgical mortality and makes patients vulnerable to hospital-acquired infections, multiple organ failure and many other complications. In addition, hemorrhage, blood transfusion, immunesenescence and immunosuppressant drugs aggravate PTI. PTI has been intensively studied, but published results are frequently cloudy. The purpose of this review is to focus on the contributions made by different responsive modalities to immunosuppression following sterile trauma and to try to integrate these into an overall scheme of PTI.

Regulation of TRAIL-receptor expression by the ubiquitin-proteasome system

The tumor necrosis factor (TNF)-related apoptosis-inducing ligand- receptor (TRAIL-R) family has emerged as a key mediator of cell fate and survival. Ligation of TRAIL ligand to TRAIL-R1 or TRAIL-R2 initiates the extrinsic apoptotic pathway characterized by the recruitment of death domains, assembly of the death-inducing signaling complex (DISC), caspase activation and ultimately apoptosis. Conversely the decoy receptors TRAIL-R3 and TRAIL-R4, which lack the pro-apoptotic death domain, function to dampen the apoptotic response by competing for TRAIL ligand. The tissue restricted expression of the decoy receptors on normal but not cancer cells provides a therapeutic rational for the development of selective TRAIL-mediated anti-tumor therapies. Recent clinical trials using agonistic antibodies against the apoptosis-inducing TRAIL receptors or recombinant TRAIL have been promising; however the number of patients in complete remission remains stubbornly low. The mechanisms of TRAIL resistance are relatively unexplored but may in part be due to TRAIL-R down-regulation or shedding of TRAIL-R by tumor cells. Therefore a better understanding of the mechanisms underlying TRAIL resistance is required. The ubiquitin-proteasome system (UPS) has been shown to regulate TRAIL-R members suggesting that pharmacological inhibition of the UPS may be a novel strategy to augment TRAIL-based therapies and increase efficacies. We recently identified b-AP15 as an inhibitor of proteasome deubiquitinase (DUB) activity. Interestingly, exposure of tumor cell lines to b-AP15 resulted in increased TRAIL-R2 expression and enhanced sensitivity to TRAIL-mediated apoptosis and cell death in vitro and in vivo. In conclusion, targeting the UPS may represent a novel strategy to increase the cell surface expression of pro-apoptotic TRAIL-R on cancer cells and should be considered in clinical trials targeting TRAIL-receptors in cancer patients.

Uncontrolled sepsis: a systematic review of translational immunology studies in intensive care medicine

BACKGROUND

The design of clinical immunology studies in sepsis presents several fundamental challenges to improving the translational understanding of pathologic mechanisms. We undertook a systematic review of bed-to-benchside studies to test the hypothesis that variable clinical design methodologies used to investigate immunologic function in sepsis contribute to apparently conflicting laboratory data, and identify potential alternatives that overcome various obstacles to improve experimental design.

METHODS

We performed a systematic review of the design methodology employed to study neutrophil function (respiratory burst), monocyte endotoxin tolerance and lymphocyte apoptosis in the intensive care setting, over the past 15 years. We specifically focussed on how control samples were defined, taking into account age, gender, ethnicity, concomitant therapies, timing of sample collection and the criteria used to diagnose sepsis.

RESULTS

We identified 57 eligible studies, the majority of which (74%) used case-control methodology. Healthy volunteers represented the control population selected in 83% of studies. Comprehensive demographic data on age, gender and ethnicity were provided in ≤48% of case control studies. Documentation of diseases associated with immunosuppression, malignancy and immunomodulatory therapies was rare. Less than half (44%) of studies undertook independent adjudication for the diagnosis of sepsis while 68% provided microbiological data. The timing of sample collection was defined by highly variable clinical criteria. By contrast, surgical studies avoided many such confounders, although only one study in surgical patients monitored the study group for development of sepsis.

CONCLUSIONS

We found several important and common limitations in the clinical design of translational immunologic studies in human sepsis. Major elective surgery overcame many of these methodological limitations. The failure of adequate clinical design in mechanistic studies may contribute to the lack of translational therapeutic progress in intensive care medicine.

A comparative study of internal laser-assisted and conventional liposuction: a look at the influence of drugs and major surgery on laboratory postoperative values

BACKGROUND

Liposuction is a type of aesthetic surgery that has been performed on humans for decades. There is not much literature addressing the subject matter of pre- and post-surgery blood parameters, although this information is rather interesting. Documentation on patients who received laser-assisted liposuction treatment is particularly scarce. Until now, there has been no literature showing values of platelets, lymphocytes, and neutrophils after liposuction.

PURPOSE

The aim of the work is to analyze and interpret values of platelets, lymphocytes and neutrophils in patient blood before and after liposuction, a surgery in which an extraordinarily large amount of potent drugs are used. Moreover, the aim is to compare values changes in patients of conventional and laser-assisted liposuction.

MATERIAL AND METHODS

We evaluated standard blood samples in patients prior to and after liposuction. This paper covers the number of platelets, lymphocytes, and neutrophils. A total of 54 patients were examined. Moreover, we compared the change in postoperative values in laser-assisted liposuction patients with the change of values in conventional liposuction patients. A paired two-sided Student's t-test was used for statistical evaluation. P < 0.005 was acknowledged to be statistically significant.

RESULTS

Values of platelets were raised both in conventional and in laser-assisted liposuction patients, but this difference was statistically non-significant and levels of platelets were still normal and within the range of blood levels in healthy patients. Values of neutrophils rose by up to 79.49% ± 7.74% standard deviation (SD) and values of lymphocytes dropped by up to 12.68% ± 5.61% SD. The before/after variances of conventional tumescent local anesthesia liposuction and variations in laser-assisted liposuction were similar for all measured parameters; they also showed no statistically significant differences between before and after surgery. The mean value of total operation time without laser-assistance was 3 hours 42 minutes (± 57 minutes SD, range 2 hours 50 minutes to 5 hours 10 minutes). Surgeries with laser-assistance were on average 16 minutes shorter with a mean duration of 3 hours 26 minutes (± 45 minutes SD, range 2 hours 40 minutes to 4 hours 10 minutes). The difference was not statistically significant (P < 0.06). The mean value of aspirate volume for liposuctions performed without laser support was 2,618 mL (± 633.7 SD, range 700 mL to 3,500 mL). Mean aspirate volume for liposuctions with laser assistance was increased by up to 61 mL (2,677 mL ± 499.5 SD, range 1,800 mL to 3,500 mL). The difference was not statistically significant (P < 0.71).

CONCLUSION

We conclude that conventional liposuction and laser-assisted liposuction have a similar influence on platelets, lymphocytes, and neutrophils in patients. Moreover, laser-assisted liposuction seems to be less time consuming than conventional liposuction.

Change in mitochondrial membrane potential in peripheral blood lymphocytes, especially in natural killer cells, is a possible marker for surgical stress on the immune system

There is accumulating evidence that surgical stresses cause impairment of systemic immune responses, which may promote susceptibility to infection as well as growth of remnant cancer cells in cancer patients. Although alterations in numbers, populations, and functions of lymphocytes have been extensively studied to assess modulation of the immune system, the precise mechanisms of immunosuppression caused by surgical stresses have not been identified, nor have methods been developed to estimate the magnitude of surgical stresses on the immune system. In the present study, to evaluate the effects of surgical procedures on the immune system, the mitochondrial membrane potential (Delta Psi(m)) of peripheral blood lymphocytes (PBL) from 25 patients who underwent various types of operation was measured by flow cytometry using 3,3'-dihexiloxacarbocyanine iodide (DiOC(6)(3)) on the day before operation and on postoperative day (POD) 1, POD 3, and POD 7. The Delta Psi(m) in PBL, especially in natural killer (NK) cell population, was reduced after major surgery. In particular, the reduction of Psi Delta(m) in NK cells appeared to be proportional to the severity of the surgical procedures and reflected the impairment of cellular function. Interestingly, the Delta Psi(m) in NK cells was also negatively correlated with the level of plasma noradrenaline after major surgery, suggesting that the reduction of Delta Psi(m) in NK cells induced by surgical stresses may be mediated, at least in part, by the accompanying increase in plasma noradrenaline. Monitoring of Delta Psi(m) in PBL after operation may be one of the useful markers for estimating the magnitude of surgical stresses on the immune system.

Applications and limitations of blood eosinophilia for the diagnosis of acute cellular rejection in liver transplantation

This study evaluates the predictive value of the blood eosinophil count in the diagnosis of acute cellular rejection, its value as a marker of response to treatment, the diagnostic use in a subgroup of patients with normal transaminases and compares blood eosinophilia in patients with and without hepatitis C virus infection. A consecutive cohort of 101 liver transplant patients, 275 liver biopsies, and blood eosinophils recorded on the day or one day before biopsy were analyzed. An elevated eosinophil count has a positive predictive value for acute cellular rejection of 82%. A normal eosinophil count excludes moderate/severe rejection with a predictive value of 86%. The eosinophil count decreases in 69% of patients following treatment of acute cellular rejection with corticosteroids irrespective of treatment outcome. Acute cellular rejection in the presence of an elevated eosinophil count occurs significantly less often (p = 0.007) in patients with hepatitis C virus. An elevated eosinophil count is a valuable marker of acute cellular rejection. However, blood eosinophil levels should not be used to predict acute cellular rejection following treatment with corticosteroids. Blood eosinophilia, seen less often in patients with hepatitis C virus, may reflect an over-diagnosis of acute cellular rejection in these patients.

Mitochondrial membrane potential is reduced in peripheral natural killer cells following partial hepatectomy

The mechanism underlying immunosuppression after partial hepatectomy remains unclear. Hepatectomy induces lymphopenia, which is related to immunomodulation. The aim of this study was to determine whether peripheral blood lymphocytes (PBL) are susceptible to mitochondria-mediated apoptosis after hepatic resection. We compared the changes in mitochondrial membrane potential in lymphocytes from hepatectomized patients with metastatic liver tumor with the corresponding changes in lymphocytes from cholechystectomized patients, because changes in mitochondrial membrane potential have been reported to frequently occur during the early stages of apoptosis. Mitochondrial membrane potential, subpopulation, and apoptosis of lymphocytes were estimated with flow cytometry. Hepatectomy significantly (P<0.001) reduced postoperative mitochondrial membrane potential, while cholecystectomy slightly decreased it. Apoptosis of lymphocytes was increased on post-hepatectomy day, and this increase was correlated with the extent of mitochondrial membrane potential reduction. The major subset of lymphocytes with low mitochondrial membrane potential consisted of CD56(+) natural killer (NK) cells, and NK cell activity and cell counts significantly decreased after hepatectomy. Mitochondrial membrane potential of PBL was reduced after hepatectomy, and some lymphocytes underwent apoptosis through the mitochondrial pathway, which was one of the causes for lymphopenia. NK cells were more responsible for the decrease of mitochondrial membrane potential after hepatectomy than other lymphocytes, and the reduction in mitochondrial membrane potential in NK cells appeared to reflect modulation of the innate immune system.

Measurement of soluble Fas antigen and ligand in circulating serum and intra-abdominal or cerebrospinal fluid during gastrointestinal or cerebrovascular surgery

PURPOSE

Soluble Fas antigen (sFas) and ligand (sFasL), which are associated with apoptosis, have not been evaluated in gastrointestinal or cerebrovascular surgery. The aim of this study was to measure these substances in serum, intra-abdominal fluid, or cerebrospinal fluid, and to speculate a pathophysiologic role for Fas-FasL apoptosis in surgery.

MATERIALS AND METHODS

Arterial blood and intraabdominal or cerebrospinal fluid were collected at intervals from 27 gastrointestinal surgical patients, 10 cerebrovascular surgical patients, and 10 spinal anesthesia patients.

RESULTS

Serum sFas levels did not change during and after surgery. Intra-abdominal and cerebrospinal sFas levels were identical to and lower than those in serum. Serum sFasL levels did not change during surgery, but decreased after surgery. Intra-abdominal and cerebrospinal sFasL levels were higher than and identical to those in serum. In spinal anesthesia, cerebrospinal sFas and sFasL levels were lower than those in serum.

CONCLUSIONS

Serum sFasL decreases after surgery, whereas intra-abdominal or cerebrospinal sFasL increases, although sFas in each site does not change, suggesting redistribution of activated lymphocytes into local surgical wounds and induction of apoptosis in this site.

A central role for CD95 (Fas) in T-cell reactivity after injury

BACKGROUND

Recent findings indicate that severe injury primes the immune system for an enhanced and lethal proinflammatory cytokine response against bacterial-derived superantigens. This study asked whether this response to injury involves the CD95 (Fas) signaling pathway.

METHODS

To assess superantigen-mediated mortality, wild-type (WT) C57BL/6 and Fas-deficient C57BL/6 lpr (-/-) (lpr) mice underwent burn or sham injury and were challenged 2 hours later with staphylococcal enterotoxin B (SEB). Spleen cells from sham and burn WT or lpr mice were stimulated in vitro with SEB to assess injury effects on IL-2, TNF-alpha, and IFN-gamma production.

RESULTS

Lpr burn mice survived the SEB challenge (100% survival), while WT burn mice showed a high mortality (17% survival, P < 001, analysis of variance [ANOVA]). Sham lpr or WT mice suffered no mortality to the SEB challenge. In vitro studies demonstrated that burn lpr mice produced significantly less TNF-alpha, IFN-gamma, IL-2 than burn WT mice (P <.01, ANOVA). Burn injury markedly enhanced SEB-stimulated IFN-gamma production by WT spleen cells and CD8+ T cells, while this did not occur in SEB-stimulated lpr spleen cells.

CONCLUSIONS

These findings support the hypothesis that the CD95 (Fas) signaling pathway plays an integral role in the injury-induced enhanced and lethal T-cell reactivity against bacterial superantigens.

Glucocorticoid-induced, caspase-dependent organ apoptosis early after burn injury

Immune suppression and increased apoptotic loss of circulating lymphocytes have been reported after burn injury. However, little is known about the underlying mechanisms responsible for the increased apoptosis of lymphoid and parenchymal cells in solid organs and the role played by inflammatory mediators, such as tumor necrosis factor-alpha (TNF-alpha) and Fas ligand (FasL), as well as by glucocorticoids. To evaluate the role of endogenously produced glucocorticoids and FasL, mice subjected to a 20% steam burn were pretreated with a glucocorticoid receptor antagonist (mifepristone) or a neutralizing murine Fas fusion protein. Three and twenty-four hours after burn injury, histological analysis, caspase-3 activity, and in situ terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and phenotyping of lymphocyte populations for apoptosis were evaluated. Burn injury increased the number of apoptotic cells and caspase-3 activity in thymus and spleen, but not in other solid organs. Increased apoptosis was seen in several T and B cell populations from both thymus and spleen. Mifepristone pretreatment significantly reduced the apoptosis and caspase-3 activity after burn injury, whereas blocking FasL activity had only minimal effects. We conclude that corticosteroids, and not FasL, are primarily responsible for the increased caspase-3 activity and apoptosis in thymus and spleen cell populations early after burn injury.

Leucocyte activation markers in clinical practice

The response against tissue injury and infection begins with the early activation of molecular and cellular elements of the inflammatory and immune response. Severe tissue injury, necrosis, and infection induce imbalanced inflammation associated with leukocyte over-stimulation and excessive or dysregulated release of cellular mediators. Clinical and experimental studies have shown that these mediators are directly related to progressive post-injury complications. Persistent increased levels of pro-inflammatory mediators produce tissue injury. Excessive production and activity of anti-inflammatory mediators cause anergy and/or immune dysfunction with increased susceptibility to infection. Leukocyte activation is assessed by cell surface phenotype expression, cellular mediators determination, or by measuring functional responses using isolated cells. Potential routine clinical uses are: evaluation of severity and prognosis in critically ill patients, immunomonitoring of sepsis, and detection of tissue injury, necrosis, and infection. In practice, the determination of cellular activation markers is restricted by a limited number of automated methods and by the cost of reagents. The availability of flow cytometry and immunoassay automated systems can contribute to a wider use in practice. Here we review the immunopathophysiology of polymorphonuclear neutrophil, monocyte, macrophage, and lymphocyte activation in response to tissue injury and infection. In addition, laboratory methods for their determination, and clinical applications in practice, are discussed.

The influence of surgical stress on T cells: enhancement of early phase lymphocyte activation

For the control of postoperative infection, it may be important to understand the possible influences of surgical stress on the host immune system. To this end, we examined how the early phase of lymphocyte activation was affected in patients after major surgery (eight patients with esophageal carcinoma and six undergoing cardiac surgery) using a flow cytometric assay based on expression of the early activation antigen, CD69. Freshly isolated T cell in preoperative and postoperative samples did not express CD69. When peripheral blood mononuclear cells were stimulated in vitro, the expression of CD69 was greatly enhanced in both CD4 and CD8 T cells, compared with the preoperative samples. The proportion of de novo CD69-expressing cells in the CD4 subset was approximately 3 times (Postoperative Day 1) and 4 times (Postoperative Days 2, 3, 5, and 7) greater than those preoperatively, whereas the proportion of de novo CD69-expressing cells in the CD8 subset was approximately 1.5 times (Postoperative Days 2 and 5) and 2 times (Postoperative Day 3) greater than those preoperatively. The proportion of CD69+ cells was significantly greater in the CD4+ subset than in the CD8+ subset during the postoperative period.

IMPLICATIONS

Our results show that major surgical stress enhances the early phase of lymphocyte activation. The augmentation of activation was greater in CD4 (helper) T cells than in CD8 (cytotoxic) T cells.