Impaired monocyte IL-12 production before surgery as a predictive factor for the lethal outcome of postoperative sepsis

Early dynamic changes to monocytes following major surgery are associated with subsequent infections

Background

Post-operative infections are a common cause of morbidity following major surgery. Little is understood about how major surgery perturbs immune function leading to heightened risk of subsequent infection. Through analysis of paired blood samples obtained immediately before and 24 h following surgery, we evaluated changes in circulating immune cell phenotype and function across the first 24 h, to identify early immune changes associated with subsequent infection.

Methods

We conducted a prospective observational study of adult patients undergoing major elective gastrointestinal, gynecological, or maxillofacial surgery requiring planned admission to the post-anesthetic care unit. Patients were followed up to hospital discharge or death. Outcome data collected included mortality, length of stay, unplanned intensive care unit admission, and post-operative infections (using the standardized endpoints in perioperative medicine-core outcome measures for perioperative and anesthetic care criteria). Peripheral blood mononuclear cells were isolated prior to and 24 h following surgery from which cellular immune traits including activation and functional status were assessed by multi-parameter flow cytometry and serum immune analytes compared by enzyme-linked immunosorbent assay (ELISA).

Results

Forty-eight patients were recruited, 26 (54%) of whom developed a post-operative infection. We observed reduced baseline pre- and post-operative monocyte CXCR4 and CD80 expression (chemokine receptors and co-stimulation markers, respectively) in patients who subsequently developed an infection as well as a profound and selective post-operative increase in CD4+ lymphocyte IL-7 receptor expression in the infection group only. Higher post-operative monocyte count was significantly associated with the development of post-operative infection (false discovery rate < 1%; adjusted p-value = 0.001) with an area under the receiver operating characteristic curve of 0.84 (p < 0.0001).

Conclusion

Lower monocyte chemotaxis markers, higher post-operative circulating monocyte counts, and reduced co-stimulatory signals are associated with subsequent post-operative infections. Identifying the underlying mechanisms and therapeutics to reverse defects in immune cell function requires further exploration.

Systematic Review and Meta-Analysis: Association between Preoperative Ustekinumab and Surgical Complications in Crohn's Disease Patients

INTRODUCTION

The impact of ustekinumab (UST) therapy on surgical complications in patients with Crohn's disease (CD) remains controversial. The aim of this meta-analysis is to explore the link between these two.

METHODS

Databases (PubMed, Web of Science, Cochrane, and Springer Link) were searched until April 2022. Studies of CD patients who received UST and no UST prior to surgery (including no biological therapy, anti-tumor necrosis factor-α [anti-TNF-α] agent, and vedolizumab [VDZ]) were included. Primary outcomes included overall complications, infectious complications, and noninfectious complications.

RESULTS

Nine studies totaling 3,225 CD patients were enrolled; 332 patients received UST treatment. There was no evidence of difference in the overall complications (odds ratio [OR] = 0.84, p = 0.37, 95% confidence interval [CI] = [0.57-1.23], I2 = 40%) between CD patients who had UST treatment preoperatively and those who had no UST treatment. There was no evidence of a difference in infectious complications (OR = 1.15, p = 0.35, 95% CI = [0.86-1.53], I2 = 2%). Additionally, there was no significant evidence of difference between these groups in terms of noninfectious complications and death. Specifically, there was no evidence of difference in overall complications, infection complications (including wound complications, sepsis, abscess, and anastomotic leakage), and noninfection complications (ileus, readmission, and return to operation), compared with no biological therapy and anti-TNF-α agents. At the same time, no significant evidence of difference was discovered in the comparison of preoperative UST and VDZ therapy in terms of overall complications, infectious complications (sepsis and abscess), and noninfectious complications (intestinal obstruction, readmission, and recovery surgery).

CONCLUSION

In general, compared with other biological agents, preoperative use of UST in the treatment of CD patients is usually safe and does not increase surgical complications.

PMMA-Based Continuous Hemofiltration Modulated Complement Activation and Renal Dysfunction in LPS-Induced Acute Kidney Injury

Sepsis-induced acute kidney injury (AKI) is a frequent complication in critically ill patients, refractory to conventional treatments. Aberrant activation of innate immune system may affect organ damage with poor prognosis for septic patients. Here, we investigated the efficacy of polymethyl methacrylate membrane (PMMA)-based continuous hemofiltration (CVVH) in modulating systemic and tissue immune activation in a swine model of LPS-induced AKI. After 3 h from LPS infusion, animals underwent to PMMA-CVVH or polysulfone (PS)-CVVH. Renal deposition of terminal complement mediator C5b-9 and of Pentraxin-3 (PTX3) deposits were evaluated on biopsies whereas systemic Complement activation was assessed by ELISA assay. Gene expression profile was performed from isolated peripheral blood mononuclear cells (PBMC) by microarrays and the results validated by Real-time PCR. Endotoxemic pigs presented oliguric AKI with increased tubulo-interstitial infiltrate, extensive collagen deposition, and glomerular thrombi; local PTX-3 and C5b-9 renal deposits and increased serum activation of classical and alternative Complement pathways were found in endotoxemic animals. PMMA-CVVH treatment significantly reduced tissue and systemic Complement activation limiting renal damage and fibrosis. By microarray analysis, we identified 711 and 913 differentially expressed genes with a fold change >2 and a false discovery rate <0.05 in endotoxemic pigs and PMMA-CVVH treated-animals, respectively. The most modulated genes were Granzyme B, Complement Factor B, Complement Component 4 Binding Protein Alpha, IL-12, and SERPINB-1 that were closely related to sepsis-induced immunological process. Our data suggest that PMMA-based CVVH can efficiently modulate immunological dysfunction in LPS-induced AKI.

Preoperative TruCulture® whole blood cytokine response predicts post-operative inflammation in pancreaticoduodenectomy patients-A pilot cohort study

Major surgery is associated with substantial morbidity and mortality with early post-operative adverse events (POAE) occurring in 30% of patients within the first 30 days. The underlying pathogenesis is multifactorial, including immune dysfunction and increased inflammatory response to surgery. We investigated preoperative immune function by the TruCulture® whole blood technique in a cohort of patients undergoing pancreaticoduodenectomy (PD), hypothesizing that patients developing inflammatory POAE defined as leucocytosis, fever or high (above median) area under the curve (AUC) C-reactive protein (CRP) the first post-operative week would display perturbed preoperative immune function. Sixty-two adult patients were screened, 30 included and 11 excluded post-inclusion due to other surgical procedures than PD and post-operative complications directly attributed to surgery, leaving 19 patients for analysis of preoperative immune function. Patients developing leucocytosis (n = 5, 26%) had lower Toll-like receptor (TLR)-3-stimulated IL-12p40 and higher Candida Albicans (TLR1/2/4/6, Dectin-1)-stimulated TNF-α, compared to patients without leucocytosis (all P < .05). Patients developing fever (n = 7, 37%) had lower TLR7/8-stimulated IFN-γ and patients with high AUC CRP (n = 9, 47%) had lower TLR3-stimulated IFN-γ and IL-6 and lower TLR7/8-stimulated IL-10 (all P < .05), compared to patients without fever or low CRP, respectively. In conclusion, patients with inflammatory POAE displayed lower preoperative stimulated IL-12p40, IFN-γ, IL-6 and IL-10 and higher TNF-α response, compared to patients without inflammatory POAE. This finding suggests that TruCulture is a feasible immunologic screening tool in surgical patients, with a potential for preoperative identification of patients at increased risk for inflammatory POAE, allowing for risk-based intervention trials.

Post-operative complications in patients with a significant post-operative decrease in γδT cells

BACKGROUND

It has previously been shown that appropriate distribution of immune cells between different tissues and organs of the body is required for proper function of the immune system. Our previous work demonstrated that surgical trauma in mice induces γδT lymphocyte migration from peripheral blood to the peritoneal lymphoid organs. These described γδT cells have immunoregulatory activity as they suppress the cell-mediated immune response in vitro. We found a similar phenomenon in patients after different surgical operations. In the current study, we analyse post-operative complications in patients with a significant post-operative decrease in γδT cells.

METHODS

We investigated the percentage of γδT cells in peripheral blood of patients undergoing standard surgical procedures (gastric resection, colorectal resection, cholecystectomy and strumectomy) before and 3 days after the operation. The percentage of γδT cells was evaluated by the fluorescence-activated cell sorting cytofluorimeter. Patients were grouped based on the decrease of γδT cells. We compared the number of septic complications in patients with a large and small decrease in γδT cells.

RESULTS

After major surgery in the peritoneal cavity (gastric and colorectal surgery), in the group that had a large decrease in γδT cells we found significantly more septic complications than in the group of patients with small γδT decrease. That effect was not visible after less traumatic surgery.

CONCLUSION

Surgery results in a decreased percentage of γδT lymphocytes in the peripheral human blood which correlates with the number of septic complications. This observation may help to predict post-operative recovery after gastroabdominal surgery.

Surgical Stress Increases Circulating Low-Density Neutrophils Which May Promote Tumor Recurrence

BACKGROUND

Low-density neutrophils (LDN) have been shown to be increased in peripheral blood in patients with various diseases and closely related to immune-mediated pathology. However, the frequency and function of LDN in circulating blood of the patients following abdominal surgery have not been well understood.

METHODS

LDN were determined by CD66b(+) cells, which were copurified with mononuclear cells by density gradient preparations of peripheral blood of surgical patients. The effects of the purified LDN on T cell proliferation and tumor cell lysis were examined in vitro. Neutrophil extracellular traps (NETs) production was examined by extracellular nuclear staining.

RESULTS

The number of LDN with an immature phenotype is markedly increased in peripheral blood samples in patients after abdominal surgery. The frequency of LDN correlated positively with operative time and intraoperative blood loss. The purified LDN significantly suppressed the proliferation of autologous T cells stimulated with anti-CD3 mAb coated on plate and partially inhibited the cytotoxicity of lymphocytes activated with recombinant interleukin-2 against a human gastric cancer cell, OCUM-1. The LDN also produced NETs after short-term culture in vitro, which efficiently trap many OCUM-1. These results suggest that surgical stress recruits immunosuppressive LDN in the circulation in the early postoperative period.

CONCLUSIONS

The LDN may support the lodging of circulating tumor cells via NETs formation and inhibit T cell-mediated antitumor response in target organs, which may promote postoperative cancer metastases. Functional blockade of LDN might be an effective strategy to reduce tumor recurrence after abdominal surgery.

Biomarkers for Evaluating the Inflammation Status in Patients with Cancer

Inflammation can be a causative factor for carcinogenesis or can result from a consequence of cancer progression. Moreover, cancer therapeutic interventions can also induce an inflammatory response. Various inflammatory parameters are used to assess the inflammatory status during cancer treatment. It is important to select the most optimal biomarker among these parameters. Additionally, suitable biomarkers must be examined if there are no known parameters. We briefly reviewed the published literature for the use of inflammatory parameters in the treatment of patients with cancer. Most studies on inflammation evaluated the correlation between host characteristics, effect of interventions, and clinical outcomes. Additionally, the levels of C-reactive protein, albumin, lymphocytes, and platelets were the most commonly used laboratory parameters, either independently or in combination with other laboratory parameters and clinical characteristics. Furthermore, the immune parameters are classically examined using flow cytometry, immunohistochemical staining, and enzyme-linked immunosorbent assay techniques. However, gene expression profiling can aid in assessing the overall peri-interventional immune status. The checklists of guidelines, such as STAndards for Reporting of Diagnostic accuracy and REporting recommendations for tumor MARKer prognostic studies should be considered when designing studies to investigate the inflammatory parameters. Finally, the data should be interpreted after adjusting for clinically important variables, such as age and cancer stage.

Neuroimaging Findings in Sepsis-Induced Brain Dysfunction: Association with Clinical and Laboratory Findings

BACKGROUND

Incidence and patterns of brain lesions of sepsis-induced brain dysfunction (SIBD) have been well defined. Our objective was to investigate the associations between neuroimaging features of SIBD patients and well-known neuroinflammation and neurodegeneration factors.

METHODS

In this prospective observational study, 93 SIBD patients (45 men, 48 women; 50.6 ± 12.7 years old) were enrolled. Patients underwent a neurological examination and brain magnetic resonance imaging (MRI). Severity-of-disease scoring systems (APACHE II, SOFA, and SAPS II) and neurological outcome scoring system (GOSE) were used. Also, serum levels of a panel of mediators [IL-1β, IL-6, IL-8, IL-10, IL-12, IL-17, IFN-γ, TNF-α, complement factor Bb, C4d, C5a, iC3b, amyloid-β peptides, total tau, phosphorylated tau (p-tau), S100b, neuron-specific enolase] were measured by ELISA. Voxel-based morphometry (VBM) was employed to available patients for assessment of neuronal loss pattern in SIBD.

RESULTS

MRI of SIBD patients were normal (n = 27, 29%) or showed brain lesions (n = 51, 54.9%) or brain atrophy (n = 15, 16.1%). VBM analysis showed neuronal loss in the insula, cingulate cortex, frontal lobe, precuneus, and thalamus. Patients with abnormal MRI findings had worse APACHE II, SOFA, GOSE scores, increased prevalence of delirium and mortality. Presence of MRI lesions was associated with reduced C5a and iC3b levels and brain atrophy was associated with increased p-tau levels. Regression analysis identified an association between C5a levels and presence of lesion on MRI and p-tau levels and the presence of atrophy on MRI.

CONCLUSIONS

Neuronal loss predominantly occurs in limbic and visceral pain perception regions of SIBD patients. Complement breakdown products and p-tau stand out as adverse neuroimaging outcome markers for SIBD.

Hyporesponsiveness of natural killer cells and impaired inflammatory responses in critically ill patients

Background

To investigate natural killer (NK) cell activity, circulating cytokine level and peripheral blood mononuclear cell (PBMC) cytokine production status in critically ill patients.

Methods

Blood samples were collected <24 h after admission from 24 intensive care unit (ICU) patients and 24 age-, sex-, and body mass index (BMI)-matched healthy controls. Serum cytokine concentrations and cytokine production by PBMCs and lipopolysaccharide (LPS)-stimulated PBMCs were measured.

Results

The ICU group showed lower NK cell activity than the controls under all conditions and an absence of interferon (IFN)-γ. After adjusting for triglycerides, LDL- and HDL-cholesterol, and glucose, the ICU group exhibited lower serum levels of albumin and interleukin (IL)-12 and higher leukocyte counts and hs-CRP and IL-6 levels than the controls. Non-stimulated PBMCs from ICU patients secreted significantly greater amounts of IL-6 and IL-1β than the controls; however, the production of IL-6, TNF-α and IL-1β in response to LPS stimulation was significantly lower in the ICU group.

Conclusions

Significant reductions in NK cell activity and serum IL-12 level, an absence of serum IFN-γ, and decreased cytokine production from LPS-stimulated PBMCs indicate the hyporesponsiveness of NK cells and an impaired early phase inflammatory response in critically ill patients (ClinicalTrials.gov NCT02565589:). Retrospectively registered; October 1, 2015.

The Effect of Surgical Stress on Postoperative Tαβ and Tγδ Cell Distribution

BACKGROUND

It was previously shown that appropriate distribution of immune cells between different tissues and organs of the body is required for proper function of the immune system. Our previous experiments demonstrated that surgical trauma in mice induces Tγδ lymphocyte migration from peripheral blood to peritoneal lymphoid organs. Tγδ cells have regulatory activity as they suppress the cell-mediated immune response in vitro via TGF-β. In the current study, we aim to evaluate the influence of surgery on both Taβ and Tγδ lymphocyte distribution in patients that underwent operation.

MATERIALS AND METHODS

We investigated the percentage of Tαβ and Tγδ cells in peripheral blood of patients undergoing standard surgical procedures (gastric resection, colorectal resection, cholecystectomy, and strumectomy) before and 3 days after operation. The percentage of Tαβ and Tγδ cells was evaluated by FACS Canto II cytofluorimeter.

RESULTS

We showed that only major surgery located in the peritoneal cavity (gastric and colorectal surgery) decreases the percentage of Tγδ cells in peripheral blood as opposed to less traumatic surgery (strumectomy and cholecystectomy) which does not have such effect. However, significant reduction of Tγδ cells after operation was only observed in a group of patients that underwent gastrectomy. Additionally, we found that gastrectomy results in significant reduction of cumulative Tγδ CD4 and Tγδ CD25 lymphocyte counts.

CONCLUSION

Surgery results in decreased percentage of Tγδ lymphocytes in peripheral human blood, and this correlates with the severity and location of the surgical trauma. This observation may help to predict postoperative recovery after gastroabdominal surgery.

Role in proinflammatory response of YghJ, a secreted metalloprotease from neonatal septicemic Escherichia coli

Neonatal sepsis is the invasion of microbial pathogens into blood stream and is associated with a systemic inflammatory response with production and release of a wide range of inflammatory mediators. The increased serum levels of cytokines were found to correlate with the severity and mortality in course of sepsis. There have been no reports on the role of microbial proteases in stimulation of proinflammatory response in neonatal sepsis. We have identified YghJ, a secreted metalloprotease from a neonatal septicemic Escherichia coli (NSEC) isolate. The protease was partially purified from culture supernatant by successive anion and gel filtration chromatography. MS/MS peptide sequencing of the protease showed homology with YghJ. YghJ was cloned, expressed and purified in pBAD TOPO expression vector. YghJ was found to be proteolytically active against Methoxysuccinyl Ala-Ala-Pro-Met-p-nitroanilide oligopeptide substrate, but not against casein and gelatin. YghJ showed optimal activity at pH 7-8 and at temperatures 37-40°C. YghJ showed clear changes in cellular morphologies of Int407, HT-29 and HEK293 cells. YghJ stimulated the secretion of cytokines IL-1α, IL-1β and TNF-α in murine macrophages (RAW 264.7) and IL-8 from human intestinal epithelial cells (HT-29). YghJ also down-regulated the production of anti-inflammatory cytokines such as IL-10. YghJ is present in both septicemic (78%) and fecal E. coli isolates (54%). However, expression and secretion of YghJ is significantly higher among the septicemic (89%) than the fecal isolates (33%). This is the first study to show the role of a microbial protease, YghJ in triggering proinflammatory response in NSEC.

Inhibition of Extracellular Calcium Influx Results in Enhanced IL-12 Production in LPS-Treated Murine Macrophages by Downregulation of the CaMKKβ-AMPK-SIRT1 Signaling Pathway

Activated macrophages are the primary sources of IL-12, a key cytokine bridging innate and adaptive immunity. However, macrophages produce low amounts of IL-12 upon stimulation and the underlying regulatory mechanism remains unclear. In this study, we found a new calcium-dependent mechanism that controlled IL-12 production in LPS-treated murine macrophages. First, LPS was demonstrated to induce extracellular calcium entry in murine peritoneal macrophages and inhibition of calcium influx resulted in marked enhancement in IL-12 production. Then, withdrawal of extracellular calcium was found to suppress CaMKKβ and AMPK activation triggered by LPS while chemical inhibition or genetic knockdown of these two kinases augmented LPS induced IL-12 production. AMPK activation increased the NAD⁺/NADH ratio and activated Sirtuin 1 (SIRT1), a NAD⁺-dependent deacetylating enzyme and negative regulator of inflammation. Chemical inhibitor or siRNA of SIRT1 enhanced IL-12 release while its agonist suppressed IL-12 production. Finally, it was found that SIRT1 selectively affected the transcriptional activity of NF-κB which thereby inhibited IL-12 production. Overall, our study demonstrates a new role of transmembrane calcium mobilization in immunity modulation such that inhibition of calcium influx leads to impaired activation of CaMKKβ-AMPK-SIRT1 signaling pathway which lifts restriction on NF-κB activation and results in enhanced IL-12 production.

Surgical Trauma Leads to a Shorter Survival in a Murine Orthotopic Pancreatic Cancer Model

Background: Abdominal surgery is frequently followed by immune dysfunction usually lasting for several days. This is especially important in cases with tumour diseases as an intact immune function is essential in this situation. Therefore, we analysed the outcome of tumour-bearing mice in a mouse model of surgically induced immune dysfunction (SID). Methods: In male C57BL/6 mice, a pancreatic tumour was implanted orthotopically. Following tumour implantation, the model of SID was applied. The control groups were either laparotomised or underwent no surgical procedure. The survival rate was determined by observation for >60 days. The tumour growth progress was imaged by a 7-tesla small animal MRI. Results: On day 60 after tumour implantation, the survival rate in SID mice was reduced to 41%. In the laparotomised group, 81% of mice survived, while the control group had a survival rate of 75%. These differences were significant (SID vs. control: p < 0.02, and SID vs. laparotomy: p < 0.002). The tumour volume was not influenced by the degree of surgical trauma. Conclusion: In pancreatic cancer, the SID model is ideally suited to investigate the influence of SID on this tumour entity.

Cytokines in sepsis: potent immunoregulators and potential therapeutic targets--an updated view

Sepsis and septic shock are among the leading causes of death in intensive care units worldwide. Numerous studies on their pathophysiology have revealed an imbalance in the inflammatory network leading to tissue damage, organ failure, and ultimately, death. Cytokines are important pleiotropic regulators of the immune response, which have a crucial role in the complex pathophysiology underlying sepsis. They have both pro- and anti-inflammatory functions and are capable of coordinating effective defense mechanisms against invading pathogens. On the other hand, cytokines may dysregulate the immune response and promote tissue-damaging inflammation. In this review, we address the current knowledge of the actions of pro- and anti-inflammatory cytokines in sepsis pathophysiology as well as how these cytokines and other important immunomodulating agents may be therapeutically targeted to improve the clinical outcome of sepsis.

Chlorogenic acid attenuates high mobility group box 1 (HMGB1) and enhances host defense mechanisms in murine sepsis

Sepsis is a complex, multifactorial, rapidly progressive disease characterized by an overwhelming activation of the immune system and the countervailing antiinflammatory response. In the current study in murine peritoneal macrophages, chlorogenic acid suppressed endotoxin-induced high mobility group box 1 (HMGB1) release in a concentration-dependent manner. Administration of chlorogenic acid also attenuated systemic HMGB1 accumulation in vivo and prevented mortality induced by endotoxemia and polymicrobial sepsis. The mechanisms of action of chlorogenic acid included attenuation of the increase in toll-like receptor (TLR)-4 expression and suppression of sepsis-induced signaling pathways, such as c-Jun NH₂-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB, which are critical for cytokine release. The protection conferred by chlorogenic acid was achieved through modulation of cytokine and chemokine release, suppression of immune cell apoptosis and augmentation of bacterial elimination. Chlorogenic acid warrants further evaluation as a potential therapeutic agent for the treatment of sepsis and other potentially fatal systemic inflammatory disorders.

Serial increase of IL-12 response and human leukocyte antigen-DR expression in severe sepsis survivors

INTRODUCTION

Sepsis-induced immunosuppression may result in death. The mechanisms of immune suppression include loss of macrophage and monocyte expression of the major histocompatibility complex, increased anti-inflammatory cytokine expression and decreased expression of proinflammatory cytokines. In this study, we sought to determine the mechanisms of immune suppression in severe sepsis by repeated detection.

METHODS

We designed this prospective observational study to measure monocyte human leukocyte antigen (HLA)-DR expression, plasma cytokine levels and cytokine responses on days 1 and 7 in stimulated peripheral blood mononuclear cells (PBMCs) of healthy controls and patients with severe sepsis.

RESULTS

Of the 35 enrolled patients, 23 survived for 28 days and 12 died, 6 of whom died within 7 days. Plasma levels of IL-1β, IL-6, IL-10, IL-17, transforming growth factor (TGF)-β1 and TNF-α were higher, but plasma IL-12 level was lower in septic patients than those in controls. Day 1 plasma levels of IL-1β, IL-6, IL-10 and TGF-β1 in nonsurvivors were higher than those in survivors. Day 7 plasma IL-10 levels in nonsurvivors were higher than in survivors. IL-1β response was higher, but IL-12 and TNF-α responses were lower in septic patients than in controls. Day 1 IL-6 response was lower, but day 1 TGF-β1 response was higher in nonsurvivors than in survivors. Plasma IL-6 and IL-10 levels were decreased in survivors after 6 days. IL-6 response was decreased in survivors after 6 days, but IL-12 response was increased. Monocyte percentage was higher, but positive HLA-DR percentage in monocytes and mean fluorescence intensity (MFI) of HLA-DR were lower in septic patients than in controls. MFI of HLA-DR was increased in survivors after 6 days.

CONCLUSIONS

Monocyte HLA-DR expression and IL-12 response from PBMCs are restored in patients who survive severe sepsis.

Improved host defense against septic peritonitis in mice lacking MyD88 and TRIF is linked to a normal interferon response

The signaling adapters MyD88 and TRIF are engaged by TLRs and/or receptors of the IL-1 family and are considered important for innate immune responses that combat bacterial infections. Here, the consequences of a combined MyD88 and TRIF deficiency for the innate immune response against severe septic peritonitis was examined. We demonstrate that Myd88(-/-);Trif(Lps2/Lps2) mice had markedly reduced bacterial numbers in the peritoneal cavity and peripheral blood, indicating that bacterial clearance in this model is improved in the absence of MyD88/TRIF signals. Survival of Myd88(-/-); Trif(Lps2/Lps2) mice was improved significantly. The lack of MyD88/TRIF signaling prevented the excessive production of inflammatory cytokines and of IL-10. In contrast, Ifng mRNA was expressed at WT levels, and induction of Ifnb mRNA was reduced only by one-half. Consistent with these findings, numerous IFN-regulated genes, including p47 and p65 GTPases, as well as CXCL10, were expressed in a MyD88/TRIF-independent manner. In support of the in vivo data, Myd88(-/-); Trif(Lps2/Lps2) macrophages stimulated with live intestinal bacteria produced normal amounts of CXCL10. The production of p47 GTPases and CXCL10 in septic peritonitis was found to be dependent on the presence of IFNAR1, but not IFN-γ, indicating a normal induction of the type I IFN response in Myd88(-/-);Trif(Lps2/Lps2) mice, despite attenuated IFN-β production. Together, these results provide evidence that in severe septic peritonitis, the absence of MyD88 and TRIF balances the innate immune response in a favorable manner by attenuating deleterious responses such as excessive cytokine release, while leaving intact protective IFN responses.

Relationship between the cAMP levels in leukocytes and the cytokine balance in patients surviving gram negative bacterial pneumonia

Lipopolysaccharide-stimulated leukocytes secrete proinflammatory cytokines including tumor necrosis factor-α and interleukin-12. Over-activation of host defense systems may result in severe tissue damage and requires regulation. Granulocyte colony-stimulating factor and interleukin-10 are candidate cytokines for inducing tolerance to lipopolysaccharide re-stimulation. We compared cytokines secreted by lipopolysaccharide-stimulated blood cells from patients who had survived gram negative bacterial pneumonia (Pseudomonas aeruginosa, Escherichia coli or Proteus mirabilis, n = 26) and age-matched healthy volunteers (n = 18). Interleukin-12p70 and tumor necrosis factor-α expression was significantly lower in patients (p = 0.0039 and p<0.001) compared to healthy controls, while granulocyte colony-stimulating factor production was markedly higher in patients (p<0.001). Levels of interleukin-10 were comparable. Granulocyte colony-stimulating factor expression was inversely correlated with interleukin-12p70 (R = -0.71, p<0.001) and tumor necrosis factor-α (R = -0.64, p<0.001) expression; interleukin-10 showed no significant correlation. In unstimulated leukocytes from patients, cAMP levels were significantly raised (p = 0.020) and were correlated inversely with interleukin-12p70 levels (R = -0.81, p<0.001) and directly with granulocyte colony-stimulating factor (R = 0.72, p = 0.0020), matrix metalloproteinase-9 (R = 0.67, p = 0.0067) and interleukin-10 (R = 0.54, p = 0.039) levels. Our results demonstrate that granulocyte colony-stimulating factor production by lipopolysaccharide-stimulated leukocytes is a useful indicator of tolerance induction in surviving pneumonia patients and that measuring cAMP in freshly isolated leukocytes may also be clinically significant.

Immunosuppression following surgical and traumatic injury

Severe sepsis and organ failure are still the major causes of postoperative morbidity and mortality after major hepatobiliary pancreatic surgery. Despite recent progress in understanding the immune conditions of abdominal sepsis, the postoperative incidence of septic complications after major visceral surgery remains high. This review focuses on the clinical and immunological parameters that determine the risk of the development and lethal outcome of postoperative septic complication following major surgery and trauma. A review of the literature indicates that surgical and traumatic injury profoundly affects the innate and adaptive immune responses, and that a marked suppression in cell-mediated immunity following an excessive inflammatory response appears to be responsible for the increased susceptibility to subsequent sepsis. The innate and adaptive immune responses are initiated and modulated by pathogen-associated molecular-pattern molecules and by damage-associated molecular-pattern molecules through the pattern-recognition receptors. Suppression of cell-mediated immunity may be caused by multifaceted cytokine/inhibitor profiles in the circulation and other compartments of the host, excessive activation and dysregulated recruitment of polymorphonuclear neutrophils, induction of alternatively activated or regulatory macrophages that have anti-inflammatory properties, a shift in the T-helper (Th)1/Th2 balance toward Th2, appearance of regulatory T cells, which are potent suppressors of the innate and adaptive immune system, and lymphocyte apoptosis in patients with sepsis. Recent basic and clinical studies have elucidated the functional effects of surgical and traumatic injury on the immune system. The research studies of interest may in future aid in the selection of appropriate therapeutic protocols.

Psychological stress-induced, IDO1-dependent tryptophan catabolism: implications on immunosuppression in mice and humans

It is increasingly recognized that psychological stress influences inflammatory responses and mood. Here, we investigated whether psychological stress (combined acoustic and restraint stress) activates the tryptophan (Trp) catabolizing enzyme indoleamine 2,3-dioxygenase 1(IDO1) and thereby alters the immune homeostasis and behavior in mice. We measured IDO1 mRNA expression and plasma levels of Trp catabolites after a single 2-h stress session and in repeatedly stressed (4.5-days stress, 2-h twice a day) naïve BALB/c mice. A role of cytokines in acute stress-induced IDO1 activation was studied after IFNγ and TNFα blockade and in IDO1^−/− mice. RU486 and 1-Methyl-L-tryptophan (1-MT) were used to study role of glucocorticoids and IDO1 on Trp depletion in altering the immune and behavioral response in repeatedly stressed animals. Clinical relevance was addressed by analyzing IDO1 activity in patients expecting abdominal surgery. Acute stress increased the IDO1 mRNA expression in brain, lung, spleen and Peyer's patches (max. 14.1±4.9-fold in brain 6-h after stress) and resulted in a transient depletion of Trp (−25.2±6.6%) and serotonin (−27.3±4.6%) from the plasma measured 6-h after stress while kynurenine levels increased 6-h later (11.2±9.3%). IDO1 mRNA up-regulation was blocked by anti-TNFα and anti-IFNγ treatment. Continuous IDO1 blockade by 1-MT but not RU486 treatment normalized the anti-bacterial defense and attenuated increased IL-10 inducibility in splenocytes after repeated stress as it reduced the loss of body weight and behavioral alterations. Moreover, kynurenic acid which remained increased in 1-MT treated repeatedly stressed mice was identified to reduce the TNFα inducibility of splenocytes in vitro and in vivo. Thus, psychological stress stimulates cytokine-driven IDO1 activation and Trp depletion which seems to have a central role for developing stress-induced immunosuppression and behavioral alteration. Since patients showed Trp catabolism already prior to surgery, IDO is also a possible target enzyme for humans modulating immune homeostasis and mood.

High interleukin-12 production from stimulated peripheral blood mononuclear cells of type 2 diabetes patients

Sugar control is important in patients with sepsis. Interleukin (IL)-12 induces the polarization of CD4(+) T cells to the T helper 1 (Th1) phenotype. Regulatory T (T(reg)) cells are important in immunity and disease. The aim of this work is to determine whether hyperglycemia or insulin alters IL-12 response in peripheral mononuclear cells (PBMCs).

METHODS

The PBMCs from 15 type 2 diabetes mellitus (DM) patients and 13 healthy controls were used for cell analysis and culture with or without treatment by glucose and insulin or stimulation by lipopolysaccharide (LPS) for 1, 2, and 3 days.

RESULTS

The IL-12 level in the supernatant of LPS-stimulated PBMCs in the DM patients was significantly higher than that of healthy controls from day 1 to day 3. Kinetic IL-12 responses of LPS-stimulated PBMCs in the DM patients from day 1 to day 3 were significantly higher than that in healthy controls. The LPS-stimulated PBMCs under glucose treatment produced more IL-12 in DM patients but this did not happen in healthy controls. In DM patients, insulin could suppress IL-12 production from stimulated PBMCs but not with additional glucose treatment.

CONCLUSION

The PBMCs of LPS-treated DM patients produced more IL-12 than that of LPS-treated healthy controls did. Hyperglycemia influenced IL-12 response from PBMCs in DM patients to some degree during infection.

Reduced interleukin-12 release from stimulated monocytes in patients with sepsis after major cancer surgery

BACKGROUND

Major cancer surgery is a high-risk situation for sepsis in the post-operative period. The aim of this study was to assess the relation between the monocyte production of IL-12 and the development of post-operative sepsis in patients undergoing major cancer surgery.

METHODS

In 19 patients undergoing major cancer surgery, the production of cytokines by basal and lipolysaccharide (LPS)-stimulated monocytes was measured before and after (from day 1 to day 3 and day 7) surgery. Seven of them developed a post-operative sepsis. Ten healthy volunteers were used as controls for the assessment of pre-operative values.

RESULTS

Before surgery, the production of interleukin (IL)-12 p40 by LPS-stimulated monocytes was similar in the patients and the healthy volunteers. The production of IL-12 p40 by unstimulated monocytes was higher in the patients than in the healthy volunteers. IL-12 production did not differ between the septic and the non-septic patients. After surgery, the production of IL-12 p40 was dramatically reduced in the LPS-stimulated monocytes of the septic patients from day 1 to day 3, as compared with that of the non-septic patients. Before surgery, the production of IL-6, IL-10, and IL-1 receptor antagonist (IL-1ra) in the patients was significantly higher than that of the healthy volunteers for both stimulated and unstimulated monocytes. After surgery, the production of these cytokines by both stimulated and unstimulated monocytes of the septic patients was similar to that of the non-septic patients. Intragroup analysis showed significant changes for IL-6, IL-10, and IL-1ra under all conditions, with the exception of changes in unstimulated monocytes of septic patients that were not significant for IL-10 release.

CONCLUSION

After surgery, the septic patients showed drastic failure to up-regulate monocyte LPS-stimulated production of IL-12 p40.

Sepsis biomarkers: a review

INTRODUCTION

Biomarkers can be useful for identifying or ruling out sepsis, identifying patients who may benefit from specific therapies or assessing the response to therapy.

METHODS

We used an electronic search of the PubMed database using the key words "sepsis" and "biomarker" to identify clinical and experimental studies which evaluated a biomarker in sepsis.

RESULTS

The search retrieved 3370 references covering 178 different biomarkers.

CONCLUSIONS

Many biomarkers have been evaluated for use in sepsis. Most of the biomarkers had been tested clinically, primarily as prognostic markers in sepsis; relatively few have been used for diagnosis. None has sufficient specificity or sensitivity to be routinely employed in clinical practice. PCT and CRP have been most widely used, but even these have limited ability to distinguish sepsis from other inflammatory conditions or to predict outcome.

Ketamine inhibits maturation of bone marrow-derived dendritic cells and priming of the Th1-type immune response

BACKGROUND

Dendritic cells (DCs) play a key role as antigen-presenting cells and growing evidence suggests that DCs influence T-cell activation and regulate the polarity of the immune response. Ketamine has been reported to have immunomodulatory properties that affect immune cells, including macrophages and natural killer cells. However, the effect of ketamine on DCs has not been characterized. We examined the immunomodulation of DCs by ketamine.

METHODS

We used bone marrow-derived DCs induced by granulocyte-monocyte-colony stimulating factor and interleukin (IL)-4 from bone marrow and analyzed the expression of costimulatory molecules (CD40, CD80, and CD86), major histocompatibility complex class II molecules, and secretion of IL-12p40. Furthermore, we evaluated the immune response in mixed cell cultures of DCs and T cells and the contact hypersensitivity response in a whole animal.

RESULTS

Ketamine suppressed the expression of CD40, CD80, and major histocompatibility complex class II molecules in DCs. DCs treated with ketamine also secreted less IL-12p40 and displayed greater endocytosis. In mixed cell cultures with CD4+ T cells and DCs, ketamine-treated DCs showed less propensity to stimulate the proliferation of CD4+ T cells and the secretion of interferon from CD4+ T cells. Furthermore, ketamine-treated DCs impaired the induction of a cell-mediated immune response.

CONCLUSION

Our findings suggest that ketamine inhibits the functional maturation of DCs and interferes with DC induction of Th1 immunity in the whole animal. These novel findings provide new insight into the immunopharmacological role of ketamine.

Effect of a BIOcocktail on the Immune Response at the Early Postoperative Period in Mice

Since human subjects and laboratory animals may develop impaired immune response during surgery and the postoperative period, efforts have been made to preserve normal immune functions following surgery by the administration of nutritional supplements and probiotics. The present study was designed to examine the effect of a new nutritional supplement, BIOcocktail, on immune parameters in mice exposed to surgery. Forty mice were assigned to 4 groups containing 10 animals each. Two control groups (with and without subsequent sham laparotomy) were given tap water for 45 min every day for 2 weeks. The remaining 2 groups, with and without laparotomy, received BIOcocktail given orally for the same period of time. The proliferative response of splenic cells (splenocytes) stimulated with phytohemagglutinin (PHA), concanavalin A (Con A) and lipopolysaccharide (LPS) was determined by [3H]thymidine uptake. Cytokine levels were measured in splenocyte supernatants and sera using enzyme-linked immunosorbent assay (ELISA) kits. Natural killer cell activity of splenocytes was evaluated by 51Cr-release assay. Laparotomy, without BIOcocktail administration, was followed by a decreased proliferative response of splenocytes to PHA, Con A, and LPS and an increase in interleukin (IL)-6 serum level. In addition, a decreased secretion of IL-1beta, IL-12 and tumor necrosis factor (TNF)-alpha by the splenocytes was observed. Mice treated with BIOcocktail before laparotomy maintained a preoperative level of splenocyte proliferative response and serum concentrations of IL-12. It is concluded that BIOcocktail administered to mice for 2 weeks before operation resulted in the preservation of T- and B-cell proliferative response to mitogens and in the prevention of postoperative decrease in IL-12 serum level.

"Host tissue damage" signal ATP impairs IL-12 and IFNgamma secretion in LPS stimulated whole human blood

OBJECTIVE

Critical illness is associated with tissue damage, inflammation and the development of immune dysfunction. Leukocyte reprogramming occurs leading to insufficient production of pro-inflammatory cytokines upon subsequent stimulation. Cellular nucleotides released during tissue damage act via purinergic receptors to modulate immune function. We hypothesized that extracellular nucleotides in concentrations similar to those found near injured and ischemic tissues will modulate cytokine secretion.

DESIGN AND PARTICIPANTS

Bench study in 28 healthy human volunteers using standardized lipopolysaccharide (LPS) stimulated ex vivo whole blood cultures (ILCS).

SETTING

The Nepean Hospital Laboratories, University of Sydney.

INTERVENTIONS

Nucleotides ATP, ADP and other P2 purinergic receptor agonists ATPgammaS, BzATP, UTP and P1 agonist CV1808 were injected into the ILCS, and cultured for 6, 12 and 24 h as indicated.

MEASUREMENTS AND RESULTS

ATP (100 muM) reduced the LPS stimulated secretion of TNFalpha at 6 and 12 h, as well as IL-12(p70) and IFNgamma at 24 h of incubation. ADP, ATPgammaS, BzATP, and CV1808, but not UTP displayed IL-12(p70) and IFNgamma reducing effect similar to ATP. Higher ATP concentration (500 muM) had even more pronounced immunosuppressive effect. Nucleotides had variable effect on stimulated IL-10 secretion.

CONCLUSIONS

ATP and ADP at high-micromolar concentrations reduce secretion of the main Th1 cytokines TNFalpha, IL-12(p70) and IFNgamma in LPS stimulated human blood. As immune dysfunction associated with critical illness is characterized by decreased TNFalpha, IL-12 and IFNgamma production by leukocytes, extracellular nucleotides might contribute to its pathogenesis [corrected]

Postoperative serum attenuates LPS-induced release of TNF-alpha in orthopaedic surgery

Studies with ex vivo stimulation of whole blood samples from injured patients have revealed a diminished production capacity for a broad range of secretory products, including inflammatory cytokines. Recent interest has focused on the release of mediators in serum that depress the cell-mediated immune response following trauma. The involvement of the lipid mediator prostaglandin E2 (PGE2) has been assumed because it is a potent endogenous immunosuppressor. In the present study, we tested the hypothesis that inhibitory substances circulating in the patient's serum after a major musculoskeletal trauma might impair leukocyte function by evaluating the effect of such serum on cytokine release in a whole blood model. Six females and three males undergoing elective total hip replacement were included in the study. Ex vivo LPS-induced TNF-alpha and IL-10 were measured in whole blood sampled preoperatively and added serum taken before, at the end of operation, and at postoperative days 1 and 6 with saline as negative control. LPS induced significant releases of TNF-alpha and IL-10 in whole blood. Addition of preoperative, postoperative, and day-1 postoperative serum did not alter the LPS-induced release of TNF-alpha as compared to saline. In the presence of serum from postoperative day 6, however, the expression of TNF-alpha was significantly reduced as compared to saline and preoperative serum (p = 0.021 and 0.008, respectively). Neither of the serum samples altered the release of IL-10. PGE2 was significantly (p = 0.008) increased in serum at postoperative day 6 as compared to preoperative levels. In conclusion, these data show that at day 6 after major orthopaedic surgery, the patient serum contained activity that inhibited ex vivo LPS-induced TNF-alpha release. The potent TNF-alpha inhibitory activity found at day 6 after injury correlated with increased levels of PGE2 and indicates cell-mediated hyporesponsiveness to a second stimulus.

Clinical monitoring of innate cellular immunity of monocytes/macrophages by tumor necrosis factor alpha productivity in whole blood stimulated by lipopolysaccharide in patients with pancreatic cancer

OBJECTIVE

The aim of this study was to evaluate the tumor necrosis factor alpha (TNF-alpha) releasing capacity in whole blood stimulated by lipopolysaccharide (LPS) in patients with pancreatic cancer during the perioperative period, and before and after chemotherapy.

METHODS

The current study involved a total of 39 patients with pancreatic cancer (PC), who were further divided into a PC-Op group (n = 16, underwent pancreatectomy) and a PC-chemo group (n = 23, received chemotherapy). The control groups consisted of patients with hepatocellular carcinoma (n = 27, HCC group) and with benign diseases (n = 15, control group). Serial changes in TNF-alpha in whole blood stimulated by LPS were compared in various clinical settings.

RESULTS

Preoperative TNF-alpha levels in the PC-Op group were significantly lower than those in the HCC and control groups (P = 0.034). The TNF-alpha variable surgical index (s-index) was defined as the ratio of the preoperative TNF-alpha level to postoperative level in the PC-Op and HCC groups. Although the TNF-alpha s-index in the PC-Op group was significantly decreased on postoperative day 1 and recovered on postoperative day 3 (P < 0.002), there were no significant changes in the TNF-alpha s-index in the HCC group. The TNF-alpha variable chemotherapeutic index (c-index) was defined as the ratio of the TNF-alpha level before to that after chemotherapy in the PC-chemo group. The TNF-alpha c-index in all 7 patients was reduced to less than 0.3 until leukopenia appeared. Patients who had an increase in TNF-alpha production (TNF-alpha c-index >1.0) on day 3 or 7 after chemotherapy had significantly better cumulative survival than those with no increase (P < 0.033).

CONCLUSIONS

TNF-alpha production stimulated by LPS in the whole blood of patients with pancreatic cancer was low. Surgical stress and depressed immunocompetence might induce such profound decreases. A method of assessing the capability of leukocytes, particularly macrophages, to produce TNF-alpha could be useful for prognostis and for monitoring immunocompetence in patients with pancreatic cancer who have undergone chemotherapy.

Blood interleukin 12 as preoperative predictor of fatal postoperative sepsis after neoadjuvant radiochemotherapy

Introduction

The value of preoperative whole-blood interleukin (IL) 12 levels in predicting death from postoperative sepsis was evaluated, in patients stratified by underlying malignancy, neoadjuvant tumour treatment and surgical procedure.

Methods

Blood samples were collected from 1444 patients before major surgery. Whole blood was incubated with Escherichia coli lipopolysaccharide (LPS) and IL-12 production in supernatants was assessed by enzyme-linked immunosorbent assay. The prognostic impact of ability to synthesize IL-12 before surgery was investigated in patient subgroups with respect to sepsis-related mortality using multivariate binary logistic regression analysis.

Results

IL-12 synthesizing capability in patients who survived sepsis was significantly higher than that in patients who developed fatal sepsis (P = 0·006). In multivariate analysis only IL-12 was associated with a lethal outcome from postoperative sepsis (P = 0·006). The prognostic impact of IL-12 was evident in patients with underlying malignancy (P = 0·011) and in those who had undergone neoadjuvant tumour treatment (P = 0·008). When patients were analysed according to the type of neoadjuvant therapy, preoperative ability to synthesize IL-12 had a significant prognostic impact in patients who had neoadjuvant radiochemotherapy (P = 0·026), but not in those who had neoadjuvant chemotherapy.

Conclusion

IL-12 production after stimulation of whole blood with LPS appears to be useful for the preoperative assessment of risk of sepsis-related death after operation in patients who have undergone neoadjuvant radiochemotherapy.

[Indicators for early prediction of outcome in sepsis]

Sepsis is still a major cause of postoperative morbidity and mortality. Numerous biochemical indicators have been evaluated regarding their potential in predicting prognosis in sepsis. Generally, one must differentiate between indicators: those for preoperative detection of patients at risk for lethal sepsis and those for early prediction of lethal outcome of septic complications. The first include the analysis of mononuclear phagocyte interleukin (IL)-12-synthesizing capability. Reduced IL-12 levels were associated with higher lethality. Cytokine-associated gene polymorphisms such as the loss of monocyte HLA-DR expression and homozygotism for the tumor necrosis factor B2 allele have a place in preoperative risk evaluation, as they were associated with worse prognosis in sepsis. Among the most important biochemical indicators for early prediction of lethal outcome in sepsis are decreased L-selectin and elevated IL-18, IL-6, and PCT plasma concentrations. Increased nuclear factor kappaB activity in mononuclear phagocytes and elevated calcitonin gene-related protein plasma concentrations were associated with unfavourable prognosis.

Animal models of sepsis: setting the stage

Sepsis is a state of disrupted inflammatory homeostasis that is often initiated by infection. The development and progression of sepsis is multi-factorial, and affects the cardiovascular, immunological and endocrine systems of the body. The complexity of sepsis makes the clinical study of sepsis and sepsis therapeutics difficult. Animal models have been developed in an effort to create reproducible systems for studying sepsis pathogenesis and preliminary testing of potential therapeutic agents. However, demonstrated benefit from a therapeutic agent in animal models has rarely been translated into success in human clinical trials. This review summarizes the common animal sepsis models and highlights how results of recent human clinical trials might affect their use.

Increased levels of tumor necrosis factor-alpha and decreased levels of interleukin-12 p 70 in tracheal aspirates, within 2 hrs after birth, are associated with mortality among ventilated preterm infants

OBJECTIVE

To determine the association of antibacterial interleukin (IL)-12 p 70 levels as well as the pathogen-induced proinflammatory cytokine response in tracheal aspirate (TA) to respiratory failure and mortality among ventilated preterm infants.

DESIGN

A prospective observational clinical cohort study with measurements of cytokine levels and microbial cultures of TA from ventilated preterm neonates. Interleukin (IL)-1 beta, IL-8, IL-6, IL-10, IL-12 p 70, and tumor necrosis factor (TNF)-alpha were measured in TA within 2 hrs of birth, and comorbidity characteristics were recorded prospectively. The association between cytokine levels in TA and neonatal mortality was determined, with correction for comorbidity factors by means of multivariate stepwise logistic regression.

SETTING

A single tertiary neonatal intensive care unit at the University Hospital of Antwerp, Belgium.

PATIENTS

One hundred forty-one neonates born before a gestational age of 31 wks and who required ventilation were enrolled in the study; 31 (22%) died and 37 (26%) had airway colonization.

MEASUREMENTS AND MAIN RESULTS

The airway colonization rate was significantly greater among deceased neonates (45% vs. 21%; chi-square, 7.4; p=.007). Neonates who died had a significantly lower IL-12 p 70 cytokine level (6 pg/mL vs. 11 pg/mL; p<.05) in their TA. Neonates with a low IL-12 p 70 cytokine level had more pronounced respiratory failure (significantly higher oxygenation index, higher degree of radiologic respiratory distress syndrome, higher critical index for babies score, and more surfactant use). Multivariate analysis revealed that, after correction for severity of disease by critical index for babies score, the degree of intraventricular hemorrhage (odds ratio, 5.0 [95% confidence interval, 2.6-9.7]), low IL-12 p 70 levels (odds ratio, 4.9 [95% confidence interval, 2.1-11.7]), and high TNF-alpha levels in TA (odds ratio, 3.5 [95% confidence interval, 1.6-7.5]) were significantly associated with neonatal mortality.

CONCLUSIONS

Pathogen-induced excessive production of the proinflammatory cytokine TNF-alpha and lack of antibacterial IL-12 p 70 response in the TA are associated with increased neonatal mortality among ventilated preterm infants.

Surgical trauma and immunosuppression: pathophysiology and potential immunomodulatory approaches

BACKGROUND

Several studies indicate that organ failure is the leading cause of death in the postoperative phase after major surgery. An excessive inflammatory response followed by a dramatic depression of cell-mediated immunity after major surgery appears to be responsible for the increased susceptibility to subsequent sepsis. In view of this, most of the scientific and medical research has been directed towards measuring the progression and interrelationship of mediators after major surgery. Furthermore, the effect of those mediators on cell-mediated immune responses has been studied.

OBJECTIVE

This article focuses on the effect of surgical injury and blood loss on cell-mediated immune responses in experimental studies utilizing models of trauma and hemorrhagic shock. The findings from those experimental studies will also be correlated with data from surgical patients.

RESULTS

Recently, a gender-dimorphic immune and organ responsiveness in the susceptibility to and morbidity from shock, trauma, and sepsis has been found. Androgens have been shown to be responsible for the immunosuppression after trauma-hemorrhage in males. In contrast, female sex steroids exhibit immunoprotective properties after trauma and severe blood loss.

CONCLUSION

In view of these findings, clinically relevant therapeutic strategies have been developed using the testosterone receptor blocker flutamide and/or estrogen or agents with estrogenic effects, i.e., dehydroepiandrosterone, which might yield safe and useful therapeutic approaches for the treatment of immune depression in surgical patients.

INTERLEUKIN 12 AND INTERFERON-?? SYNTHETIC DEFICIENCY IS ASSOCIATED WITH DENDRITIC CELL CYTOPENIA AFTER CARDIAC SURGERY

Traumatic or inflammatory injury associates with deactivation of monocytes and impaired synthesis of proinflammatory cytokines. We conducted a prospective, observational study to test whether cardiac surgery additionally impaired dendritic and natural killer (NK) cell functions responsible for innate immune production of interleukin (IL)-12-dependent interferon (IFN)-gamma in response to bacteria or toll-like receptor agonists. Blood samples were taken just before induction of anesthesia and 24 h postoperatively. LPS- and fixed Staphylococcus aureus-inducible IFNgamma synthesis in whole blood culture after surgery was reduced to 5% of preoperative values (P < 0.001). Production of IL-12 p70, a critical inducer of IFNgamma in the innate immune response, was reduced to 30% of that produced by preoperative samples (P = 0.013). Circulating CD11c, DR myeloid dendritic cells (DC) that are known sources of IL-12 p70 in normal blood, declined to approximately 25% of presurgical numbers (P = 0.004). Experimental depletion of CD11c, but not CD14, cells from normal peripheral blood mononuclear cell (PBMC) similarly disabled Staphylococcus aureus Cowan 1 (SAC)-induced production of IL-12 p70 and IFNgamma. Consistent with SAC-induced IFNgamma expression in CD56 NK and NK-T cells, CD56 depletion ablated IFNgamma production in normal whole blood. However, repletion of IL-12 p70, IL-18, IL-15, and IL-23 in postoperative blood failed to restore presurgical levels of IFNgamma synthesis (P < 0.05). We conclude that DC cytopenia after major surgery is sufficient to explain postoperative IL-12 p70 and IFNgamma synthetic deficiency. In addition, postoperative blood became hyporesponsive to IFNgamma-inducing cytokines as a further contribution to IFNgamma insufficiency. The novel finding of DC cytopenia after major surgery may portend a lack of other immunologic functions provided by this potent accessory cell population.

Thrombin-mediated IL-10 up-regulation involves protease-activated receptor (PAR)-1 expression in human mononuclear leukocytes

Thrombin, the key enzyme of the coagulation cascade, exerts cellular effects through activation of the protease-activated receptors (PARs). Interleukin (IL)-10, besides its anti-inflammatory properties, is considered a major denominator of the immunosuppressive effect during human endotoxemia. We have recently shown that thrombin inhibits IL-12 production in human mononuclear cells and that such inhibition is accompanied by IL-10 up-regulation. To our knowledge, there are no data available to show that thrombin mediates IL-10 production by its interactions with PAR-1. We here report that human alpha-thrombin enhances IL-10 expression in human peripheral blood mononuclear cells and in established monocytic cell lines and that this up-regulation requires PAR-1 expression. The use of proteolytically inactive thrombin reveals that such enhancement requires thrombin proteolytic activity. Addition of PAR-1 agonist peptides, such as SFLLRN, results in a significant increase of IL-10 production. PAR-1 expression is required for thrombin-induced IL-10 production, as shown by experiments performed with antisense or sense PAR-1 oligonucleotides. Treatment with thrombin or SFLLRN of monocytic cell lines, such as U937 and Mono Mac-6, results in an increased IL-10 production. This suggests that the observed IL-10 up-regulation may be the result of a direct interaction with monocytes. The observation that thrombin-mediated up-regulation of IL-10 may require the expression of the PAR-1 receptor identifies a new, functional link between inflammation and coagulation. Our results may also contribute to better design therapeutic strategies to treat several disorders, characterized by the presence of inflammatory as well as coagulant responses.

High interleukin 12 and low interleukin 10 production after in vitro stimulation detected in sepsis survivors

OBJECTIVE

To evaluate viability of isolated peripheral blood mononuclear cells (PBMC) and production of cytokines in vitro after stimulation as prognostic factors for survival in sepsis patients.

DESIGN

Prospective study of the biological response of PBMC in the onset of severe sepsis.

SETTING

Research laboratory of molecular biology and immunology and university hospital ICU, Faculty of Medicine, Trakia University.

PATIENTS

Twenty-three patients meeting the criteria for severe sepsis, and 14 control subjects.

INTERVENTIONS

Isolated PBMC were stimulated in vitro with: C3-binding glycoprotein (C3bgp; 30 microg), lipopolysaccharide (30 microg), phytohemagglutinin (20 microg), pokeweed mitogen (30 microg), and dexamethasone (500 microg).

MEASUREMENTS AND RESULTS

We measured the levels of interleukins (IL) 6, 10, and 12 in culture supernatants. Stimulation with C3bgp and phytohemagglutinin led to significantly lower PBMC secretion of IL-6 in nonsurvivors than in survivors and healthy donors. Stimulation with C3bgp, lipopolysaccharide, and pokeweed mitogen considerably reduced IL-12 production in nonsurvivors. Stimulation with lipopolysaccharide and pokeweed mitogen caused immune cells in nonsurvivors to produce higher levels of IL-10 than in survivors. Survival of PBMC reduced viability for nonsurvivors' PBMC, both spontaneously and as induced by lipopolysaccharide or pokeweed mitogen.

CONCLUSIONS

The viability of PBMC at the onset of sepsis and enhanced production of IL-12 and diminished production of IL-10 after stimulation with all stimuli used may be a favorable prognostic factor in sepsis.

Pre-transplant elevations of interleukin-12 and interleukin-10 are associated with acute rejection after renal transplantation

BACKGROUND

Methods for predicting patients at higher risk for rejection before transplantation may help improve outcomes. We hypothesized that pre-transplant elevations of serum interleukin-12 (IL-12), a pro-inflammatory cytokine, would predict acute rejection, while pre-transplant IL-10, an immunoregulatory cytokine, would be down-regulated in patients subsequently experiencing acute rejection.

MATERIALS AND METHODS

Thirty patients experiencing acute rejection after cadaveric renal allograft transplantation and a control group of 30 patients, undergoing the same procedure but without the occurrence of rejection, were identified. Serum samples taken before transplantation from each patient were then analyzed quantitatively for IL-12 and IL-10 using ELISA assays.

RESULTS

The mean pre-transplant serum IL-12 level was higher in patients who subsequently underwent acute rejection vs. those who did not (181 +/- 143 pg/mL vs. 81.2 +/- 71.5 pg/mL, respectively, p = 0.007). Unexpectedly, pre-transplant serum IL-10 levels were also elevated in patients who underwent rejection (559 +/- 293 pg/mL vs. 332 +/- 163 pg/mL, respectively, p = 0.002). Multivariate analysis demonstrated that elevations of IL-12 and IL-10 were independent risk factors for rejection when adjusted for confounding variables.

CONCLUSIONS

Pre-transplant elevations of IL-12 and, unexpectedly, IL-10 are associated with acute rejection after cadaveric renal transplantation and may be useful in predicting which patients are at increased immunological risk at the time of transplantation. Further studies are necessary to assess the role of occult systemic inflammation in contributing to poor outcomes after transplantation.

Therapeutic effects of lysophosphatidylcholine in experimental sepsis

Sepsis represents a major cause of death in intensive care units. Here we show that administration of lysophosphatidylcholine (LPC), an endogenous lysophospholipid, protected mice against lethality after cecal ligation and puncture (CLP) or intraperitoneal injection of Escherichia coli. In vivo treatment with LPC markedly enhanced clearance of intraperitoneal bacteria and blocked CLP-induced deactivation of neutrophils. In vitro, LPC increased bactericidal activity of neutrophils, but not macrophages, by enhancing H(2)O(2) production in neutrophils that ingested E. coli. Incubation with an antibody to the LPC receptor, G2A, inhibited LPC-induced protection from CLP lethality and inhibited the effects of LPC in neutrophils. G2A-specific antibody also blocked the inhibitory effects of LPC on certain actions of lipopolysaccharides (LPS), including lethality and the release of tumor necrosis factor-alpha (TNF-alpha) from neutrophils. These results suggest that LPC can effectively prevent and treat sepsis and microbial infections.

[Role of the innate immune response in sepsis]

The innate immune system succeeds against the majority of infections before the adaptive immune system is activated. New findings contribute to a better understanding of the pathophysiology of sepsis and lead to the development of new therapeutic strategies. The innate immune system, being responsible for the first response to infections, can trigger adaptive immune responses in case the initial response is ineffective. Both arms of the immune system interact with each other, mainly via cell-cell-interactions but also by soluble factors, such as cytokines and chemokines. Two sub-populations of helper T-cells direct both balanced activation and inhibition of the two arms of the immune systems using specific patterns of cytokine release. Results obtained in new animal models of sepsis, taking a progressive growth of bacteria into account, have implied that existing knowledge has to be reanalyzed. The idea of sepsis as a mere "over-reaction to inflammation" has to be abandoned. Various so-called pattern recognition receptors (e.g. toll-like receptors, TLRs, NOD proteins) are located intracellularly or in the plasma membrane of innate immune cells and recognize certain patterns expressed exclusively by extracellular pathogens. Upon receptor engagement, intracellular signaling pathways lead to cellular activation, followed by release of various cytokines and anti-microbial substances. During the course of sepsis a cytokine shift towards increasing immune suppression occurs. The innate immune system also contributes to the migration of leukocytes in inflammed tissue, involving chemokines and adhesion molecules. Leukocytes also secrete the tissue factor leading to formation of thrombin. The environment in sepsis can cause disseminated intravascular coagulation (DIC), but at the same time thrombin triggers the release of chemokines and adhesion molecules through endothelial cells, which represents a positive feedback mechanism for innate immune responses. New therapeutic strategies for sepsis try to establish a well-balanced immune response. Intervention is accomplished through inhibition of inflammatory cytokines, their receptors or through activation of immunostimulatory responses.

Depressed interleukin-12-producing activity by monocytes correlates with adverse clinical course and a shift toward Th2-type lymphocyte pattern in severely injured male trauma patients

OBJECTIVE

To determine the effect of major trauma on the cytokine-producing activity of monocytes and CD4+ T cells in a homogeneous cohort of patients as well as to determine the relationship between monocyte and T-lymphocyte responses and clinical outcome.

SETTINGS

Surgical intensive care units of a trauma center and flow cytometry and experimental laboratories at a teaching hospital.

DESIGN

Prospective cohort clinical study with measurements of white cell cytokine-producing activity on days 2, 5, and 10 postinjury. The number of cytokine-producing CD14+ monocytes, CD4+, and CD8+ T cells were determined in whole blood using flow cytometry combined with the intracellular cytokine staining method. Basal and lipopolysaccharide-stimulated interleukin (IL)-12, tumor necrosis factor-alpha, IL-6, and IL-1alpha production by monocytes as well as basal and phorbol 12-myristate 13-acetate plus ionomycin-stimulated interferon-gamma, IL-4, and tumor necrosis factor-alpha production by T cells were determined on days 2, 5, and 10 postinjury and compared with similar measurements made in healthy control subjects.

PATIENTS

Twelve randomly selected black, male patients were enrolled in the study: mean injury severity score, 26; mean age, 35 yrs; mean Glasgow Coma Scale score, 13; systemic inflammatory response syndrome, 92%; sepsis, 42%; bronchial infection, 42%; and adult respiratory distress syndrome 25%.

MAIN RESULTS

After lipopolysaccharide stimulation, the number of IL-12-, tumor necrosis factor-alpha-, IL-1alpha-, and IL-6-producing CD14+ monocytes was 40% to 70% lower in trauma patients on postinjury days 2, 5, and 10 than in healthy control subjects. After phorbol 12-myristate 13-acetate stimulation, the number of IL-4-producing CD4+ cells increased three-fold in the trauma patients compared with healthy control subjects. In contrast, the number of interferon-gamma- or tumor necrosis factor-alpha-producing CD4+ and CD8+ T cells was not different between the patients and control subjects. The Th1/Th2 ratio was significantly lower in patients on all postinjury days than in the control subjects. A statistically significant inverse correlation was found between the number of IL-12-producing monocytes and IL-4-producing CD4+ T cells in trauma patients (p =.007, r2 =.47). This correlation was absent in control subjects. The degree of depressed capacity of monocyte IL-12 production on day 2 postinjury showed a statistically significant correlation with the development of adult respiratory distress syndrome, sepsis, or infections and also with the duration of systemic inflammatory response syndrome and sepsis.

CONCLUSIONS

Major trauma results in an early and marked decrease in monocyte cytokine-producing activity. The trauma-induced depression in IL-12 production by the mononuclear phagocyte system may promote T-cell commitment toward a Th2 pattern early after trauma. The appearance of the Th2 pattern is the result of elevated numbers of IL-4-producing cells without major alterations in T-cell interferon-gamma-producing capacity. The degree of alterations in monocyte and T-cell responses on day 2 postinjury correlates with the development of adverse clinical outcomes and the subsequent duration of the inflammatory response.

Peripheral mononuclear cell IL-10 and IL-12 production is not impaired in patients with advanced cancer and severe infection

We assessed whether interleukin (IL)-10 and IL-12 production of blood mononuclear cells (PBMC) after lipopolysaccharide (LPS 0.1 microgram/ml, 1.0 microgram/ml) or phytohemagglutinin (PHA 5 microgram/ml) stimulation in advanced cancer patients with severe infections (IA, n=10) differs from those without infection (AC,n =10) or healthy controls HC (n=10). PBMCs in IA produced statistically higher median IL-12 levels than those in HC; LPS 0.1 (P=0.05), LPS 1.0 (P=0.019) and PHA (P=0.024). IL-10 production was always higher in AC than in HC. Both the IL-10 (LPS 1.0; P=0.018) and IL-12 (LPS 0.1;P =0.046) production of PBMCs were significantly higher in IA than one month afterwards. In conclusion, the PBMC production of IL-10 and IL-12 in advanced cancer patients with or without infection was not impaired but rather enhanced compared to that of HC. One month after infection, however, PBMC production clearly decreased, suggesting a kind of hyporeactivity.

New concepts in sepsis

An estimated 750,000 cases of severe sepsis occur annually in the United States, and the mortality rate is about 30%. As a condition that disproportionately affects the elderly and is related to invasive and immunosuppressive healthcare, increases in the frequency of sepsis are anticipated. The complex pathophysiology of sepsis encompasses the interplay of pro- and anti-inflammatory mediators, activated circulating and resident inflammatory cells, disrupted coagulation, endothelial activation and injury, vasodilatation and vascular hyporesponsiveness to vasoactive mediators, cardiac dysfunction, and cellular dysoxia. Current management of severe sepsis includes eradication of infection through source control and antimicrobial therapy, aggressive and targeted shock resuscitation that includes fluid administration, correction of anemia, vasopressor support, modest inotropic therapy, infusion of human recombinant activated protein C to selected patients, and compulsive supportive care to manage organ dysfunction and to avoid complications.