Local and systemic impacts of pleural oxygen exposure in thoracotomy

HIF activation enhances FcγRIIb expression on mononuclear phagocytes impeding tumor targeting antibody immunotherapy

BACKGROUND

Hypoxia is a hallmark of the tumor microenvironment (TME) and in addition to altering metabolism in cancer cells, it transforms tumor-associated stromal cells. Within the tumor stromal cell compartment, tumor-associated macrophages (TAMs) provide potent pro-tumoral support. However, TAMs can also be harnessed to destroy tumor cells by monoclonal antibody (mAb) immunotherapy, through antibody dependent cellular phagocytosis (ADCP). This is mediated via antibody-binding activating Fc gamma receptors (FcγR) and impaired by the single inhibitory FcγR, FcγRIIb.

METHODS

We applied a multi-OMIC approach coupled with in vitro functional assays and murine tumor models to assess the effects of hypoxia inducible factor (HIF) activation on mAb mediated depletion of human and murine cancer cells. For mechanistic assessments, siRNA-mediated gene silencing, Western blotting and chromatin immune precipitation were utilized to assess the impact of identified regulators on FCGR2B gene transcription.

RESULTS

We report that TAMs are FcγRIIbbright relative to healthy tissue counterparts and under hypoxic conditions, mononuclear phagocytes markedly upregulate FcγRIIb. This enhanced FcγRIIb expression is transcriptionally driven through HIFs and Activator protein 1 (AP-1). Importantly, this phenotype reduces the ability of macrophages to eliminate anti-CD20 monoclonal antibody (mAb) opsonized human chronic lymphocytic leukemia cells in vitro and EL4 lymphoma cells in vivo in human FcγRIIb+/+ transgenic mice. Furthermore, post-HIF activation, mAb mediated blockade of FcγRIIb can partially restore phagocytic function in human monocytes.

CONCLUSION

Our findings provide a detailed molecular and cellular basis for hypoxia driven resistance to antitumor mAb immunotherapy, unveiling a hitherto unexplored aspect of the TME. These findings provide a mechanistic rationale for the modulation of FcγRIIb expression or its blockade as a promising strategy to enhance approved and novel mAb immunotherapies.

Artificial pneumothorax suppresses postoperative inflammatory reaction in mediastinal tumor surgery

OBJECTIVE

The induction of artificial pneumothorax has many intraoperative advantages. However, few reports on the postoperative effects of artificial pneumothorax induction are available. In this study, we investigated the effect of artificial pneumothorax on postoperative clinical course in patients with mediastinal tumors.

METHODS

We retrospectively investigated the clinical courses of 89 patients who had undergone mediastinal tumor resection between January 2010 and December 2020. Sixty-five patients had undergone resection with artificial pneumothorax.

RESULTS

The tumor location significantly varied across patients. The proportion of patients in whom artificial pneumothorax was induced was higher among those having anterior mediastinal tumors. The number of ports and the total skin incision length were significantly higher in patients without artificial pneumothorax. The C-reactive protein level elevation on postoperative day 2 and pleural effusion at 24 h after surgery were significantly higher in patients without artificial pneumothorax. Furthermore, the albumin level reduction and hospital stay after surgery were significantly lower in patients with artificial pneumothorax. Multiple regression analysis showed that the use of artificial pneumothorax was an independent predictive factor of the C-reactive protein level elevation on postoperative day 2 and pleural effusion at 24 h after surgery. In patients without artificial pneumothorax, the operation time positively correlated with the C-reactive protein level (r = 0.646, P < 0.001).

CONCLUSIONS

Artificial pneumothorax suppressed the postoperative inflammatory response, pleural effusion, and albumin reduction, and shortened the hospital stay in patients undergoing mediastinal tumor surgery.

Comparison of short-term outcomes between transthoracic and robot-assisted transmediastinal radical surgery for esophageal cancer: a prospective study

Background

The present study aimed to assess the lower invasiveness of robot-assisted transmediastinal radical esophagectomy by prospectively comparing this procedure with transthoracic esophagectomy in terms of perioperative outcomes, serum cytokine levels, and respiratory function after surgery for esophageal cancer.

Methods

Patients who underwent a robot-assisted transmediastinal esophagectomy or transthoracic esophagectomy between April 2015 and March 2017 were included. The perioperative outcomes, preoperative and postoperative serum IL-6, IL-8, and IL-10 levels, and respiratory function measured preoperatively and at 6 months postoperatively were compared in patients with a robot-assisted transmediastinal esophagectomy and those with a transthoracic esophagectomy.

Results

Sixty patients with esophageal cancer were enrolled. The transmediastinal esophagectomy group had a significantly lower incidence of postoperative pneumonia (p = 0.002) and a significantly shorter postoperative hospital stay (p < 0.0002). The serum IL-6 levels on postoperative days 1, 3, 5, and 7 were significantly lower in the transmediastinal esophagectomy group (p = 0.005, 0.0007, 0.022, 0.020, respectively). In the latter group, the serum IL-8 level was significantly lower immediately after surgery and on postoperative day 1 (p = 0.003, 0.001, respectively) while the serum IL-10 level was significantly lower immediately after surgery (p = 0.041). The reduction in vital capacity, percent vital capacity, forced vital capacity, and forced expiratory volume at 1.0 s 6 months after surgery was significantly greater in the transthoracic esophagectomy group (p < 0.0001 for all four measurements).

Conclusions

Although further, large-scale studies are needed to confirm our findings, robot-assisted transmediastinal esophagectomy may confer short-term benefits in radical surgery for esophageal cancer.

Trial registration

This trial was registered in the UMIN Clinical Trial Registry (UMIN000017565 14/05/2015).

High-fat enteral nutrition reduces intestinal mucosal barrier damage after peritoneal air exposure

BACKGROUND

Peritoneal air exposure is needed in open abdominal surgery, but long-time exposure could induce intestinal mucosal barrier dysfunction followed by many postoperative complications. High-fat enteral nutrition can ameliorate intestinal injury and improve intestinal function in many gastrointestinal diseases. In the present study, we investigated the effect of high-fat enteral nutrition on intestinal mucosal barrier after peritoneal air exposure and the underlying mechanism.

METHODS

Male adult rats were administrated saline, low-fat or high-fat enteral nutrition via gavage before and after peritoneal air exposure for 3 h. Rats undergoing anesthesia without laparotomy received saline as control. Twenty four hours after surgery, samples were collected to assess intestinal mucosal barrier changes in serum D-lactate levels, intestinal permeability, intestinal tight junction protein ZO-1 and occludin levels, and intestinal histopathology. The levels of malondialdehyde and the activity of superoxide dismutase in the ileum tissue were also measured to assess the status of intestinal oxidative stress.

RESULTS

High-fat enteral nutrition significantly decreased the serum D-lactate level and increased the intestinal tight junction protein ZO-1 level when compared to the group treated with low-fat enteral nutrition (P < 0.05). Meanwhile, histopathologic findings showed that the intestinal mucosal injury assessed by the Chiu's score and the intestinal epithelial tight junction were also improved much more in the high-fat enteral nutrition-treated group (P < 0.05). In addition, the intestinal malondialdehyde level was lower, and the intestinal superoxide dismutase activity was higher in the high-fat enteral nutrition-treated group than that in the low-fat enteral nutrition-treated group (P < 0.05).

CONCLUSIONS

These results suggest that high-fat enteral nutrition could reduce intestinal mucosal barrier damage after peritoneal air exposure, and the underlying mechanism may be associated with its antioxidative action. Perioperative administration of high-fat enteral nutrition may be a promising intervention to preserve intestinal mucosal barrier function in open abdominal surgery.

A comparison of the effects of midazolam, propofol and dexmedetomidine on the antioxidant system: A randomized trial

Previous studies on the antioxidant activity of sedatives have predominantly been in vitro investigations that are lacking clinical data, resulting in conclusion without cogency. The aim of the present prospective, randomized study was to use single sedative drugs for anesthesia induction to compare their antioxidant properties. The effects on the antioxidant system of midazolam, propofol and dexmedetomidine were assessed using oxidative stress indicators and micronuclei (MN). Forty-nine patients undergoing esophageal cancer radical prostatectomy were selected. Midazolam, propofol and dexmedetomidine were used to induce anesthesia. Venous blood samples were obtained prior to and at 2 and at 24 h after surgery, and oxidative stress indicators were detected using the appropriate kits. The cytokinesis-block micronucleus cytome assay was executed and the frequencies of MN, nucleoplasmic bridges and nuclear buds were examined. It was found that the use of the three sedatives, respectively, led to a marked increase in the levels of free radical indicators at 2 h after surgery, which then decreased at 24 h after surgery. Furthermore, lower levels of oxidative stress were found following the use of propofol and dexmedetomidine compared with those following midazolam administration, and similar results were obtained regarding the level of MN. It is suggested that propofol and dexmedetomidine exhibit a superior antioxidant function to midazolam.

Positive end-expiratory pressure attenuates positional effect after thoracotomy

CONTEXT:

Thoracotomy is a common procedure. However, thoracotomy leads to lung atelectasis and deteriorates pulmonary gas exchange in operated side. Therefore, different positions with operated side lowermost or uppermost may lead to different gas exchange after thoracotomy. Besides, PEEP (positive end-expiratory pressure) influence lung atelectasis and should influence gas exchange.

AIMS:

The purpose of this study was to determine the physiological changes in different positions after thoracotomy. In addition, we also studied the influence of PEEP to positional effects after thoracotomy.

MATERIALS AND METHODS:

There were eight pigs in each group. Group I received left thoracotomy with zero end-expiratory pressure (ZEEP), and group II with PEEP; group III received right thoracotomy with ZEEP and group IV with PEEP. We changed positions to supine, LLD (left lateral decubitus) and RLD (right lateral decubitus) in random order after thoracotomy.

RESULTS:

PaO₂ was decreased after thoracotomy and higher in RLD after left thoracotomy and in LLD after right thoracotomy. PaO₂ in groups II and IV was higher than in groups I and III if with the same position. In group I and III, PaCO₂ was increased after thoracotomy and was higher in LLD after left thoracotomy and in RLD after right thoracotomy. In groups II and IV, there were no PaCO₂ changes in different positions after thoracotomy. Lung compliance (C_rs) was decreased after thoracotomy in groups I and III and highest in RLD after left thoracotomy and in LLD after right thoracotomy. In groups II and IV, there were no changes in C_rs regardless of the different positions.

CONCLUSION:

There were significant changes with regards to pulmonary gas exchange, hemodynamics and C_rs after thoracotomy. The best position was non-operated lung lowermost Applying PEEP attenuates the positional effects.

Peritoneal air exposure elicits an intestinal inflammation resulting in postoperative ileus

BACKGROUND

The pathogenesis of postoperative ileus (POI) is complex. The present study was designed to investigate the effects of peritoneal air exposure on the POI intestinal inflammation and the underlying mechanism.

METHODS

Sprague-Dawley rats were randomized into five groups (6/group): the control group, the sham group, and three exposure groups with peritoneal air exposure for 1, 2, or 3 h. At 24 h after surgery, we analyzed the gastrointestinal transit, the serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10, the myeloperoxidase activity, and the levels of TNF-α, IL-1β, IL-6, and IL-10 in the ileum and colon. The oxidant and antioxidant levels in the ileum and colon were analyzed by measuring malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC).

RESULTS

Peritoneal air exposure caused an air-exposure-time-dependent decrease in the gastrointestinal transit. The length of peritoneal air exposure is correlated with the severity of both systemic and intestinal inflammations and the increases in the levels of MDA, SOD, GSH-Px, and T-AOC.

CONCLUSIONS

The length of peritoneal air exposure is proportional to the degree of intestinal paralysis and the severity of intestinal inflammation, which is linked to the oxidative stress response.

Merits of non-invasive rat models of left ventricular heart failure

Heart failure (HF) is characterized as a limitation to cardiac output that prevents the heart from supplying tissues with adequate oxygen and predisposes individuals to pulmonary edema. Impaired cardiac function is secondary to either decreased contractility reducing ejection (systolic failure), diminished ventricular compliance preventing filling (diastolic failure), or both. To study HF etiology, many different techniques have been developed to elicit this condition in experimental animals, with varying degrees of success. Among rats, surgically induced HF models are the most prevalent, but they bear several shortcomings, including high mortality rates and limited recapitulation of the pathophysiology, etiology, and progression of human HF. Alternatively, a number of non-invasive HF induction methods avoid many of these pitfalls, and their merits in technical simplicity, reliability, survivability, and comparability to the pathophysiologic and pathogenic characteristics of HF are reviewed herein. In particular, this review focuses on the primary pathogenic mechanisms common to genetic strains (spontaneously hypertensive and spontaneously hypertensive heart failure), pharmacological models of toxic cardiomyopathy (doxorubicin and isoproterenol), and dietary salt models, all of which have been shown to induce left ventricular HF in the rat. Additional non-invasive techniques that may potentially enable the development of new HF models are also discussed.