The Spleen Responds to Intestinal Manipulation but Does Not Participate in the Inflammatory Response in a Mouse Model of Postoperative Ileus

Electrical vagus nerve stimulation as a prophylaxis for SIRS and postoperative ileus

Abdominal surgery results in an activation of immune cells of the bowel wall and a consecutive cytokine and nitric oxide (NO) release leading to an inflammation of the muscularis externa and a bowel paralysis, the so-called postoperative ileus (POI). In addition to the local inflammation, major surgical trauma can also lead to a variable pronounced systemic inflammation up to its maximum variant, the systemic inflammatory response syndrome (SIRS), with hypotension, capillary leak and a breakdown of the intestinal barrier function followed by multi-organ dysfunction (MODS). Until now, neither for SIRS nor for POI, a prophylaxis or an evidence-based treatment exists. Since the pioneering work from Kevin Tracey and his group in the late 90s characterizing the role of the vagus nerve in inflammation and describing the cholinergic anti-inflammatory pathway (CAIP) for the first time, substantial efforts have been made in the research field of neuro-immune interactions. Today, the anti-inflammatory potential of vagus nerve stimulation is moving more and more into focus resulting in new therapeutic approaches. This review focuses on the role of the CAIP in the development of SIRS and POI. Furthermore, new therapeutic options like transcutaneous vagus nerve stimulation are highlighted.

Hyposplenism and Gastrointestinal Diseases: Significance and Mechanisms

BACKGROUND

Functional hyposplenism is a recognized complication of several gastroenterological disorders, including coeliac and inflammatory bowel diseases, and is believed to contribute to the increased infection risk seen in these disorders.

SUMMARY

The mechanisms of hyposplenism are poorly understood. In this article, we review possible mechanisms underlying development of functional hyposplenism and discuss implications for its management.

KEY MESSAGES

Identifying functional hyposplenism is important, as it may permit earlier recognition and treatment of serious infections through patient education and vaccination.

Effects of Prostaglandin E1 on Patients Undergoing Major Gastrointestinal Surgery

OBJECTIVE

The aim of this study was to investigate the clinical effects of prostaglandin E1 (PGE1) in patients who underwent surgery for gastrointestinal (GI) trauma, perforation, or obstruction.

BACKGROUND

PGE1 is thought to enhance intestinal blood supply and reduce GI complications during the postoperative period.

METHODS

The medical records of 889 patients undergoing major GI surgery were reviewed retrospectively. Propensity score matching was performed to adjust for any baseline differences. Clinical outcomes, including early GI function recovery, postoperative complications, and length of hospital stay, were evaluated in all patients. In 278 paired patients, selected nutritional, immunologic, and inflammatory variables were compared based on PGE1 administration.

RESULTS

After propensity score 1:1 matching, the baseline characteristics were similar for both groups. PGE1 was associated with prompt postoperative GI function recovery, including first bowel movement [2.6 ± 0.9 vs 3.1 ± 1.0 days after surgery in patients with and without PGE1 treatment, risk ratio 0.51, 95% confidence interval (CI) 0.41-0.65, P < 0.001] and first feeding within postoperative day 3 [179 (64.39%) vs 152 (54.68%); risk ratio 0.61, 95% CI 0.42-0.90, P = 0.012]. A lower overall postoperative complication rate, including infectious complications [45 (16.2%) vs 68 (24.5%); odds ratio 0.60, 95% CI 0.39-0.91, P = 0.010] and major complications [23 (8.3%) vs 48 (17.3%); odds ratio 0.43, 95% CI 0.26-0.73, P = 0.001], was noted in patients with PGE1 treatment than in patients without PGE1 treatment. Furthermore, the immunologic and inflammatory variable C-reactive protein on postoperative day 3 was reduced by PGE1 treatment (52.5 ± 36.4 vs 89.6 ± 42.4 mg/L; P = 0.037, t test).

CONCLUSIONS

PGE1 is associated with beneficial clinical effects, such as prompt postoperative GI function recovery and reduced overall postoperative complications after emergency GI surgery, which may be attributed to a reduced inflammatory response.

Role of surgical manipulation in lung inflammatory response in a model of lung resection surgery

OBJECTIVES

Lung resection surgery with one-lung ventilation leads to an inflammatory response. Surgical manipulation can play a key role in this response. Sevoflurane, a commonly used volatile anaesthetic, has a proven anti-inflammatory effect. Our main goal was to evaluate the segregated effect of surgical manipulation during lung resection surgery and the protective role of sevoflurane with regard to this response.

METHODS

Fifteen pigs underwent left thoracotomy for caudal lobectomy under general anaesthesia. The animals were divided into 3 groups: control, sevoflurane and sham. The animals in the sham group underwent left thoracotomy and one-lung ventilation over 120 min, without lobectomy. The animals in the sevoflurane group received anaesthetic maintenance with sevoflurane. The animals in the sham group and the control group received propofol during the procedure. Lung biopsies were collected before the procedure (left caudal lobe) and 24 h later (right mediastinal lobe and left upper lobe). The samples were stored to measure levels of inflammatory markers (IL-1, TNF-α and ICAM-1), apoptotic mediators (BAD, BAX, BCL-2 and Caspase-3), Syndecan-1, MicroRNAs 182, 145 and lung oedema.

RESULTS

Surgical manipulation increased the expression of inflammation (IL-1, TNF-α and ICAM-1) and proapoptotic mediators (BAX, BAD and Caspase-3). It also caused degradation of endothelial glycocalyx (Syndecan-1) and pulmonary oedema. Administration of sevoflurane reduced the elevation of inflammatory markers, degradation of glycocalyx and pulmonary oedema observed in the control group.

CONCLUSIONS

Surgical manipulation of the collapsed lung could increase the expression of inflammation and proapoptotic mediators and cause tissue damage in the form of pulmonary oedema. Sevoflurane could attenuate this molecular response and pulmonary oedema.

Establishing a biomarker for postoperative ileus in humans - Results of the BiPOI trial

AIMS

Postoperative ileus (POI) is a frequent complication after abdominal surgery, resulting from an inflammation of the muscularis externa (ME). So far no valid biomarker for occurrence, duration or intensity of POI exists. Extravasation of monocytes and neutrophils from blood circulating into the postoperative ME is well known as a hallmark of POI. In a previous study we demonstrated that a low abundant subset of TH1 cells, activated by IL-12, can be detected in the peripheral blood of a small subset of patients in response to abdominal surgery. The aim of the present study was to investigate if these specific TH1 cells, IL-12 or circulating leukocyte levels could act as a valid marker for POI occurrence.

MAIN METHODS

At different time points, blood samples of patients undergoing abdominal or extraabdominal surgery were collected. Serum levels of IL-12 or TH1 cells as well as neutrophils and monocytes were analyzed. Data were compared between both groups and correlated with clinical signs of POI.

KEY FINDINGS

Time until first flatus and defecation as well as solid food tolerances are delayed after abdominal compared to extraabdominal surgery. Circulating IL-12 levels and numbers of TH1 cells, neutrophils and monocytes did not differ between both groups.

SIGNIFICANCE

While previous experiments indicated that specific TH1 cells play a crucial role in POI dissemination, our present data from a larger human cohort demonstrate that they do not seem to be suitable to distinguish between abdominal and extraabdominal surgery. Furthermore neither TH1 cells nor leukocytes or serum IL-12 levels are appropriate biomarkers for POI in a clinical setting.