Features of postoperative immune suppression are reversible with interferon gamma and independent of interleukin-6 pathways

OBJECTIVE The aim of this study was to evaluate the role of interleukin (IL)-6 pathways in postoperative immune suppression and to assess the reversibility of this phenomenon. BACKGROUND The postoperative period is characterized by increased IL-6 production and features of immune suppression. In vitro, IL-6 mediates anti-inflammatory effects through inhibition of interferon gamma (IFN-γ) pathways. The significance of the immunomodulatory effects of IL-6 in the clinical setting of postoperative immune suppression remains unclear. METHODS Patients over 45 years old undergoing elective surgery, involving the gastrointestinal tract, were recruited. IL-6 levels were assayed using an enzyme linked immunosorbent assay preoperatively, and at 24 and 48 hours. Peripheral blood mononuclear cells from healthy volunteers were cultured in perioperative serum and CD14Human Leukocyte Antigen-DR (HLA-DR) [monocyte HLA-DR (mHLA-DR)] geometric mean florescent intensity was measured in the presence and absence of IL-6 neutralizing antibody and recombinant IFN-γ. RESULTS Of the 108 patients, 41 developed a postoperative infection. The IL-6 levels increased 19-fold from the preoperative sample to 24 hours postoperatively (P < 0.0001). Higher IL-6 levels at 24 (P = 0.0002) and 48 hours (P = 0.003) were associated with subsequent postoperative infectious complications. mHLA-DR mean florescent intensity fell when healthy peripheral blood mononuclear cells were cultured with postoperative serum compared with preoperative serum (P = 0.008). This decrease was prevented by the presence of IFN-γ in the culture media, but not by the presence of IL-6-neutralizing antibody. CONCLUSIONS IL-6 levels increase after a major surgery and are associated with an increased susceptibility to postoperative infections. Serum obtained from postoperative patients induces an immunosuppressive response, reflected in reduced mHLA-DR levels, mediated through IL-6 independent pathways and is reversible with IFN-γ. These data may have therapeutic implications for the prevention of infection in patients undergoing major surgery

Systemic inflammatory response syndrome after major abdominal surgery predicted by early upregulation of TLR4 and TLR5

OBJECTIVES To study innate immune pathways in patients undergoing hepatopancreaticobiliary surgery to understand mechanisms leading to enhanced inflammatory responses and identifying biomarkers of adverse clinical consequences. BACKGROUND Patients undergoing major abdominal surgery are at risk of life-threatening systemic inflammatory response syndrome (SIRS) and sepsis. Early identification of at-risk patients would allow tailored postoperative care and improve survival. METHODS Two separate cohorts of patients undergoing major hepatopancreaticobiliary surgery were studied (combined n = 69). Bloods were taken preoperatively, on day 1 and day 2 postoperatively. Peripheral blood mononuclear cells and serum were separated and immune phenotype and function assessed ex vivo. RESULTS Early innate immune dysfunction was evident in 12 patients who subsequently developed SIRS (postoperative day 6) compared with 27 who did not, when no clinical evidence of SIRS was apparent (preoperatively or days 1 and 2). Serum interleukin (IL)-6 concentration and monocyte Toll-like receptor (TLR)/NF-κB/IL-6 functional pathways were significantly upregulated and overactive in patients who developed SIRS (P < 0.0001). Interferon α-mediated STAT1 phosphorylation was higher preoperatively in patients who developed SIRS. Increased TLR4 and TLR5 gene expression in whole blood was demonstrated in a separate validation cohort of 30 patients undergoing similar surgery. Expression of TLR4/5 on monocytes, particularly intermediate CD14CD16 monocytes, on day 1 or 2 predicted SIRS with accuracy 0.89 to 1.0 (areas under receiver operator curves). CONCLUSIONS These data demonstrate the mechanism for IL-6 overproduction in patients who develop postoperative SIRS and identify markers that predict patients at risk of SIRS 5 days before the onset of clinical signs

Perioperative blood transfusion is associated with a gene transcription profile characteristic of immunosuppression: a prospective cohort study

INTRODUCTION Blood transfusion in the perioperative period has frequently been associated with an excess of nosocomial infections. Whilst transfused whole blood induces specific host immune alteration that may predispose to nosocomial infections, the immunomodulating properties associated with leukodepleted blood remain incompletely understood. In this study, we explore the hypothesis that the transfusion of leukodepleted allogeneic blood during or following major gastrointestinal surgery is associated with an immunosuppressed phenotype, which may in turn predispose to postoperative infectious complications. METHODS Patients aged over 45 years undergoing scheduled inpatient major gastrointestinal surgery were recruited. Gene expression profiles of specific inflammatory genes were assayed from blood collected preoperatively, at 24 and at 48 hours after surgery. Genes were selected based on their ability to represent specific immune pathways. Gene expression was quantified using quantitative real-time polymerase chain reaction (qRT-PCR) to measure messenger RNA (mRNA) levels. Postoperative infections were documented using predefined criteria. RESULTS One hundred and nineteen patients were recruited. Fifteen (13%) patients required blood transfusion within 24 hours of surgery, 44 (37%) patients developed infections and 3 (2%) patients died prior to discharge. Patients receiving a blood transfusion were more likely to develop postoperative infections (P =0.02) and to have lower tumour necrosis factor alpha (TNFα), interleukin (IL)-12, IL-23 and RAR-related orphan receptor gamma T (RORγt) gene expression in the postoperative period (P <0.05). The TNFα/IL-10 mRNA ratio at 24 hours (P =0.0006) and at 48 hours (P =0.01) was lower in patients receiving a blood transfusion over this period. Multivariable analysis confirmed that these observations were independent of the severity of the surgical insult. CONCLUSIONS An association between an immunosuppressive pattern of gene expression and blood transfusion following major elective gastrointestinal surgery is described. This gene expression profile includes a reduction in the activity of innate immunity and T helper cell type 1 (Th1) and T helper cell type 17 (Th17) pathways in those patients receiving a blood transfusion. Blood transfusion was also associated with an excess of infectious complications in this cohort. A mechanistic link is suggested but not proven

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Levels of HLA-DR α-chain and Cathepsin S mRNA in response to GM-CSF and IFN-γ.

(A) HLA-DR α-chain mRNA levels from monocytes sorted from healthy PBMCs cultured in serum from the pre- or post-operative (24 hour) period, and following the addition of GM-CSF or IFN-γ to the post-operative serum; (B) CTSS mRNA levels from monocytes sorted from healthy PBMCs cultured in serum from the pre- or post-operative (24 hour) period, and following the addition of GM-CSF or IFN-γ to the post-operative serum. All data are collated from 3 independent experiments. mRNA levels are quantified using the 2^-δδCt methodology. All graphs are displayed as median with interquartile range. All P values were obtained by using Wilcoxon matched-pairs signed rank test.</p

Peri-operative mHLA-DR and IL-10 mRNA and protein levels.

(A) Whole blood monocyte mHLA-DR expression levels, quantified as antibodies per cell (Ab/C) measured pre-operatively and at 24 and 48 hours post-operatively. (B) Whole blood (PAXGene®) IL-10 mRNA levels, mRNA results expressed as a relative quantification ratio between IL-10 and the reference genes. (C) Citrated plasma IL-10 protein levels measured pre-operatively and at 24 and 48 hours post-operatively, quantified by ELISA. All graphs displayed as median and interquartile range. P values are a comparison of the pre-operative and post-operative values (24 and 48 hours) as well as between the post-operative values at 24 and 48 hours (Wilcoxon matched-pairs signed rank test).</p

Peri-operative IL-10 cytokine levels.

Citrated plasma IL-10 protein levels measured pre- and post-operatively (24 and 48 hours), quantified by ELISA. Graphs are displayed as median and interquartile range. P values are a comparison of the pre-operative and post-operative values (24 and 48 hours) as well as between the post-operative values at 24 and 48 hours (Wilcoxon matched-pairs signed rank test).</p

Peri-operative cytokine and transcription factor mRNA levels.

(A-B) IL-10 and TNFα Whole blood (PAXGene®) mRNA levels pre- and post-operatively (2, 24 and 48 hours); (C-H) IFN-γ, IL-12, T bet, Th17, IL-23, RORγt, and FOXP3 Whole blood (PAXGene®) mRNA levels pre- and post-operatively (24 and 48 hours). Graphs are displayed as median and interquartile range; mRNA levels are presented as a relative quantification ratio between the candidate and the reference genes. P values are a comparison with the pre-operative values (Wilcoxon matched-pairs signed rank test).</p

The response to clinically available immune stimulants GM-CSF and IFN-γ.

(A) Surface mHLA-DR expression (geometric mean fluorescent intensity (MFI)) of healthy donor PBMCs cultured in serum obtained from the pre- or post-operative (24 hour) period, and following the addition of increasing concentrations of GM-CSF to the post-operative serum; (B) Surface mHLA-DR expression (MFI) of healthy donor PBMCs cultured in serum obtained from the pre- or post-operative (24 hour) period, and following the addition of GM-CSF or IFN-γ to the post-operative serum; (C) Intra- and extra-cellular mHLA-DR expression (MFI), measured in PBMCs cultured in serum obtained from the pre- and post-operative (24 hour) period, and following the addition of GM-CSF or IFN-γ to the post-operative serum. All data are collated from 3 independent experiments. All graphs are displayed as median with interquartile range. All P values were obtained by using Wilcoxon matched-pairs signed rank test.</p