Peritoneal acidosis mediates immunoprotection in laparoscopic surgery

Laparoscopic lavage in a purulent peritonitis model: impact on inflammatory proteins

BACKGROUND

Laparoscopic lavage is an effective, safe, and feasible treatment in patients with perforated diverticulitis with purulent peritonitis. Laparoscopic lavage was introduced without any detailed knowledge regarding the mechanisms of action. The aim of this study was to validate the reproducibility of an animal model of purulent peritonitis and to study the effect of laparoscopic lavage on inflammatory proteins in this model.

METHODS

Forty rats, divided into eight groups (n = 5) were operated. Six groups underwent cecal ligation and puncture (CLP) causing peritonitis and two groups underwent sham surgery. Three CLP and one sham group received laparoscopic lavage, while the remaining groups acted as time-matched controls. Samples of abdominal fluid and blood were collected after 1, 2 or 3 h and analyzed regarding 92 inflammatory proteins using Olink Target 96 Mouse exploratory panel.

RESULTS

Animals with peritonitis had higher levels of inflammatory proteins such as CCL3, IL17A and IL6 in abdominal fluid and serum compared to sham. The groups treated with laparoscopic lavage had lower levels of inflammatory proteins in both abdominal fluid and serum compared with untreated peritonitis groups, results were most distinct sampled after one hour.

CONCLUSION

Our animal model is reproducible, and mimics perforated diverticulitis with purulent peritonitis with increased levels of inflammatory proteins in abdominal fluid and serum. The levels of several inflammatory proteins were lower following laparoscopic lavage treatment perhaps indicating the physiological effect of laparoscopic lavage. This model can be used to further explore the mechanisms involved in peritonitis and laparoscopic lavage treatment.

The Simultaneous Deletion of pH-Sensing Receptors GPR4 and OGR1 (GPR68) Ameliorates Colitis with Additive Effects on Multiple Parameters of Inflammation

G protein-coupled receptors (GPRs), including pro-inflammatory GPR4 and ovarian cancer GPR1 (OGR1/GPR68), are involved in the pH sensing of the extracellular space and have been implicated in inflammatory bowel disease (IBD). Previous data show that a loss of GPR4 or OGR1 independently is associated with reduced intestinal inflammation in mouse models of experimental colitis. In the present manuscript, we investigated the impact of the simultaneous loss of GPR4 and OGR1 in animal models of IBD. To study the effects of combined loss of Gpr4 Ogr1 in IBD we used the well-established acute dextran sodium sulfate (DSS) and spontaneous Il10-/- murine colitis models. Disease severity was assessed using multiple clinical scores (e.g., body weight loss, disease activity score, murine endoscopic index of colitis severity (MEICS) and histological analyses). Real-time quantitative polymerase chain reaction (qPCR), Western blot, and flow cytometry were used to investigate changes in pro-inflammatory cytokines expression and immune cells infiltration. We found that a combined loss of GPR4 and OGR1 significantly reduces colon inflammation in IBD relative to single deficiencies as evidenced by reduced body weight loss, disease score, CD4/CD8 ratio, and Il1β, Il6, and Tnf in the colon. Similarly, in the II10 deficiency model, the inflammation was significantly ameliorated upon the simultaneous deletion of GPR4 and OGR1, evidenced by a reduction in the MEICS score, colon length, Tnf and Il1β measurements, and a decrease in the number of macrophages in the colon, as compared to single deletions. Importantly, hydroxyproline levels were decreased close to baseline in Il10-/- × Gpr4-/- × Ogr1-/- mice. Our findings demonstrate that the simultaneous loss of GRP4 and OGR1 functions exerts an additive effect on multiple parameters associated with colonic inflammation. These results further reinforce the hypothesis that chronic inflammatory acidosis is a driver of fibrosis and is dependent on GPR4 and OGR1 signaling. The inhibition of both GPR4 and OGR1 by pH-sensing receptor modulators may constitute as a potential therapeutic option for IBD, as both pH-sensing receptors appear to sustain inflammation by acting on complementary pro-inflammatory pathways.

Role of pH-sensing receptors in colitis

Low pH in the gut is associated with severe inflammation, fibrosis, and colorectal cancer (CRC) and is a hallmark of active inflammatory bowel disease (IBD). Subsequently, pH-sensing mechanisms are of interest for the understanding of IBD pathophysiology. Tissue hypoxia and acidosis-two contributing factors to disease pathophysiology-are linked to IBD, and understanding their interplay is highly relevant for the development of new therapeutic options. One member of the proton-sensing G protein-coupled receptor (GPCR) family, GPR65 (T-cell death-associated gene 8, TDAG8), was identified as a susceptibility gene for IBD in a large genome-wide association study. In response to acidic extracellular pH, GPR65 induces an anti-inflammatory response, whereas the two other proton-sensing receptors, GPR4 and GPR68 (ovarian cancer G protein-coupled receptor 1, OGR1), mediate pro-inflammatory responses. Here, we review the current knowledge on the role of these proton-sensing receptors in IBD and IBD-associated fibrosis and cancer, as well as colitis-associated cancer (CAC). We also describe emerging small molecule modulators of these receptors as therapeutic opportunities for the treatment of IBD.

Intraperitoneal insufflation of carbon dioxide rescues intestinal damage in an experimental murine model of colitis

OBJECTIVES

Necrotizing enterocolitis (NEC) is a severe neonatal surgical condition, associated with a prolonged pro-inflammatory state, leading to high mortality and morbidity rates. Carbon dioxide (CO2 ) insufflation during laparoscopy may have an anti-inflammatory effect. We aimed to evaluate the effects of CO2 -insufflation on experimental colitis.

METHODS

Acute colitis was induced in 6-week-old Balb/c mice by the administration of 2%-dextran sulfate-sodium (DSS) during 7 days (n = 45). On Day 4, two groups received intraperitoneal insufflation (duration: 30 mn, pressure: 5 mmHg) of CO2 ("DSS+CO2 ") or air ("DSS+air"). A group received no insufflation ("DSS"). Groups were compared for clinical severity using the disease activity index (DAI-body weight loss, stool consistency, and bleeding), histological severity (histopathological activity index, colon length, and ulcerations), colonic mucosecretion, and inflammation.

RESULTS

DAI was significantly decreased in DSS+CO2 group, compared to DSS (p < 0.0001) or DSS+air (p < 0.0001) groups. Colon length was increased in DSS+CO2 treated mice compared to DSS (p = 0.0002). The histopathological activity index was lower in DSS+CO2 (vs. DSS, p = 0.0059/vs. DSS+air, p = 0.0389), with decreased ulcerations (3.77 vs. 10.7, p = 0.0306), and persistent mucosecretion with increased mucin-secreting cells.

CONCLUSIONS

CO2 -insufflation attenuates DSS-induced colitis and improves both clinical and histological scores. Laparoscopy with CO2 insufflation represents a therapeutic anti-inflammatory strategy for NEC.

A major mechanism for immunomodulation: Dietary fibres and acid metabolites

Diet and the gut microbiota have a profound influence on physiology and health, however, mechanisms are still emerging. Here we outline several pathways that gut microbiota products, particularly short-chain fatty acids (SCFAs), use to maintain gut and immune homeostasis. Dietary fibre is fermented by the gut microbiota in the colon, and large quantities of SCFAs such as acetate, propionate, and butyrate are produced. Dietary fibre and SCFAs enhance epithelial integrity and thereby limit systemic endotoxemia. Moreover, SCFAs inhibit histone deacetylases (HDAC), and thereby affect gene transcription. SCFAs also bind to 'metabolite-sensing' G-protein coupled receptors (GPCRs) such as GPR43, which promotes immune homeostasis. The enormous amounts of SCFAs produced in the colon are sufficient to lower pH, which affects the function of proton sensors such as GPR65 expressed on the gut epithelium and immune cells. GPR65 is an anti-inflammatory Gα_s-coupled receptor, which leads to the inhibition of inflammatory cytokines. The importance of GPR65 in inflammatory diseases is underscored by genetics associated with the missense variant I231L (rs3742704), which is associated with human inflammatory bowel disease, atopic dermatitis, and asthma. There is enormous scope to manipulate these pathways using specialized diets that release very high amounts of specific SCFAs in the gut, and we believe that therapies that rely on chemically modified foods is a promising approach. Such an approach includes high SCFA-producing diets, which we have shown to decrease numerous inflammatory western diseases in mouse models. These diets operate at many levels - increased gut integrity, changes to the gut microbiome, and promotion of immune homeostasis, which represents a new and highly promising way to prevent or treat human disease.

New Therapeutic Approach for Intestinal Fibrosis Through Inhibition of pH-Sensing Receptor GPR4

BACKGROUND

Patients suffering from inflammatory bowel diseases (IBDs) express increased mucosal levels of pH-sensing receptors compared with non-IBD controls. Acidification leads to angiogenesis and extracellular matrix remodeling. We aimed to determine the expression of pH-sensing G protein-coupled receptor 4 (GPR4) in fibrotic lesions in Crohn's disease (CD) patients. We further evaluated the effect of deficiency in Gpr4 or its pharmacologic inhibition.

METHODS

Paired samples from fibrotic and nonfibrotic terminal ileum were obtained from CD patients undergoing ileocaecal resection. The effects of Gpr4 deficiency were assessed in the spontaneous Il-10-/- and the chronic dextran sodium sulfate (DSS) murine colitis model. The effects of Gpr4 deficiency and a GPR4 antagonist (39c) were assessed in the heterotopic intestinal transplantation model.

RESULTS

In human terminal ileum, increased expression of fibrosis markers was accompanied by an increase in GPR4 expression. A positive correlation between the expression of procollagens and GPR4 was observed. In murine disease models, Gpr4 deficiency was associated with a decrease in angiogenesis and fibrogenesis evidenced by decreased vessel length and expression of Edn, Vegfα, and procollagens. The heterotopic animal model for intestinal fibrosis, transplanted with terminal ileum from Gpr4-/- mice, revealed a decrease in mRNA expression of fibrosis markers and a decrease in collagen content and layer thickness compared with grafts from wild type mice. The GPR4 antagonist decreased collagen deposition. The GPR4 expression was also observed in human and murine intestinal fibroblasts. The GPR4 inhibition reduced markers of fibroblast activation stimulated by low pH, notably Acta2 and cTgf.

CONCLUSIONS

Expression of GPR4 positively correlates with the expression of profibrotic genes and collagen. Deficiency of Gpr4 is associated with a decrease in angiogenesis and fibrogenesis. The GPR4 antagonist decreases collagen deposition. Targeting GPR4 with specific inhibitors may constitute a new treatment option for IBD-associated fibrosis.

Severe portal and systemic acidosis during CO2-laparoscopy compared to helium or gasless laparoscopy and laparotomy in a rodent model: an experimental study

BACKGROUND AND AIMS

This experimental study assesses the influence of different gases and insufflation pressures on the portal, central-venous and peripheral-arterial pH during experimental laparoscopy.

METHODS

Firstly, 36 male WAG/Rij rats were randomized into six groups (n = 6) spontaneously breathing during anaesthesia: laparoscopy using carbon dioxide or helium at 6 and 12 mmHg, gasless laparoscopy and laparotomy. 45 and 90 min after setup, blood was sampled from the portal vein, vena cava and the common femoral artery with immediate blood gas analysis. Secondly, 12 animals were mechanically ventilated at physiological arterial pH during 90 min of laparotomy (n = 6) or carbon dioxide laparoscopy at 12 mmHg (n = 6) with respective blood gas analyses.

RESULTS

Over time, in spontaneously breathing rats, carbon dioxide laparoscopy caused significant insufflation pressure-dependent portal acidosis (pH at 6 mmHg, 6.99 [6.95-7.04] at 45 min and 6.95 [6.94-6.96] at 90 min, pH at 12 mmHg, 6.89 [6.82-6.90] at 45 min and 6.84 [6.81-6.87] at 90 min; p < 0.05) compared to laparotomy (portal pH 7.29 [7.23-7.30] at 45 min and 7.29 [7.20-7.30] at 90 min; p > 0.05). Central-venous and peripheral-arterial acidosis was significant but less severely reduced during carbon dioxide laparoscopy. Laparotomy, helium laparoscopy and gasless laparoscopy showed no comparable acidosis in all vessels. Portal and central-venous acidosis during carbon dioxide laparoscopy at 12 mmHg was not reversible by mechanical hyperventilation maintaining a physiological arterial pH (pH portal 6.85 [6.84-6.90] (p = 0.004), central-venous 6.93 [6.90-6.99] (p = 0.004), peripheral-arterial 7.29 [7.29-7.31] (p = 0.220) at 90 min; Wilcoxon-Mann-Whitney test).

CONCLUSION

Carbon dioxide laparoscopy led to insufflation pressure-dependent severe portal and less severe central-venous acidosis not reversible by mechanical hyperventilation.

The "Dark Side" of Pneumoperitoneum and Laparoscopy

Laparoscopic surgery has been one of the most common procedures for abdominal surgery at pediatric age during the last few decades as it has several advantages compared to laparotomy, such as shorter hospital stays, less pain, and better cosmetic results. However, it is associated with both local and systemic modifications. Recent evidence demonstrated that carbon dioxide pneumoperitoneum might be modulated in terms of pressure, duration, temperature, and humidity to mitigate and modulate these changes. The aim of this study is to review the current knowledge about animal and human models investigating pneumoperitoneum-related biological and histological impairment. In particular, pneumoperitoneum is associated with local and systemic inflammation, acidosis, oxidative stress, mesothelium lining abnormalities, and adhesion development. Animal studies reported that an increase in pressure and time and a decrease in humidity and temperature might enhance the rate of comorbidities. However, to date, few studies were conducted on humans; therefore, this research field should be further investigated to confirm in experimental models and humans how to improve laparoscopic procedures in the spirit of minimally invasive surgeries.

Robotically assisted laparoscopic radical prostatectomy induces lower tissue trauma than radical retropubic prostatectomy

To compare tissue trauma between Retropubic Radical Prostatectomy and Robotically Assisted Laparoscopic Radical Prostatectomy by inflammatory mediators. Serum samples from 40 patients submitted to RALP and 20 patients submitted to RRP were withdrawn at four different time points. The cytokines IL-4, IL-8, IL-6, IL-1B, IL-10 and TNF-α were detected using ELISA/Multiplex assays and xMAP-Luminex®. With both techniques, IL-10 and IL-6 were higher in T4 than in T1-T3 (p = 0.001). IL-10 and IL-6 were higher in T4 in open surgery than in robotic surgery (p = 0.000 and p = 0.001, respectively). Compared with both groups, IL-6 and IL-10 were higher in T4 in open surgery than in robotic surgery. Thus, we can postulate that RALP causes less tissue trauma than classical RRP, as indicated by the more limited increase in inflammatory mediators such as IL-6 and IL-10.

Does Helium Pneumoperitoneum Reduce the Hyperinflammatory Response in Septic Animals during Laparoscopy?

Background/Aim. An exacerbated reaction to peritoneal infection and attendant surgical procedures is characterized by an intense hyperinflammatory state, the magnitude of which is proportional to the severity of tissue injury. Laparoscopy generates lower levels of tissue damage compared with open surgery and should induce less pronounced immune responses. The aim of this study was to determine whether laparoscopy assisted by helium rather than carbon dioxide pneumoperitoneum would induce an attenuated inflammatory state in septic animals. Materials and Methods. Thirty-two Wistar rats were divided randomly into four equal groups, two of which were submitted to carbon dioxide or helium pneumoperitoneum-assisted laparoscopic cecal ligation and puncture (CLP) induced sepsis and subsequent abdominal lavage. Two control groups were submitted to identical laparoscopic procedures with carbon dioxide or helium as insufflator gas but without CLP. After 24 hours, serum levels of tumor necrosis factor alpha (TNF-α), interleukins 1 and 6 (IL-1 and IL-6, respectively), and cortisol were determined.

The impact of the rs8005161 polymorphism on G protein-coupled receptor GPR65 (TDAG8) pH-associated activation in intestinal inflammation

Background

Tissue inflammation in inflammatory bowel diseases (IBD) is associated with a decrease in local pH. The gene encoding G-protein-coupled receptor 65 (GPR65) has recently been reported to be a genetic risk factor for IBD. In response to extracellular acidification, proton activation of GPR65 stimulates cAMP and Rho signalling pathways. We aimed to analyse the clinical and functional relevance of the GPR65 associated single nucleotide polymorphism (SNP) rs8005161.

Methods

1138 individuals from a mixed cohort of IBD patients and healthy volunteers were genotyped for SNPs associated with GPR65 (rs8005161, rs3742704) and galactosylceramidase (rs1805078) by Taqman SNP assays. 2300 patients from the Swiss IBD Cohort Study (SIBDC) were genotyped for rs8005161 by mass spectrometry based SNP genotyping. IBD patients from the SIBDC carrying rs8005161 TT, CT, CC and non-IBD controls (CC) were recruited for functional studies. Human CD14+ cells were isolated from blood samples and subjected to an extracellular acidic pH shift, cAMP accumulation and RhoA activation were measured.

Results

In our mixed cohort, but not in SIBDC patients, the minor variant rs8005161 was significantly associated with UC. In SIBDC patients, we observed a consistent trend in increased disease severity in patients carrying the rs8005161-TT and rs8005161-CT alleles. No significant differences were observed in the pH associated activation of cAMP production between IBD (TT, CT, WT/CC) and non-IBD (WT/CC) genotype carriers upon an acidic extracellular pH shift. However, we observed significantly impaired RhoA activation after an extracellular acidic pH shift in IBD patients, irrespective of the rs8005161 allele.

Conclusions

The T allele of rs8005161 might confer a more severe disease course in IBD patients. Human monocytes from IBD patients showed impaired pH associated RhoA activation upon an acidic pH shift.

Electronic supplementary material

The online version of this article (10.1186/s12876-018-0922-8) contains supplementary material, which is available to authorized users.

Intestinal Activation of pH-Sensing Receptor OGR1 [GPR68] Contributes to Fibrogenesis

BACKGROUND AND AIMS

pH-sensing ovarian cancer G-protein coupled receptor-1 [OGR1/GPR68] is regulated by key inflammatory cytokines. Patients suffering from inflammatory bowel diseases [IBDs] express increased mucosal levels of OGR1 compared with non-IBD controls. pH-sensing may be relevant for progression of fibrosis, as extracellular acidification leads to fibroblast activation and extracellular matrix remodelling. We aimed to determine OGR1 expression in fibrotic lesions in the intestine of Crohn's disease [CD] patients, and the effect of Ogr1 deficiency in fibrogenesis.

METHODS

Human fibrotic and non-fibrotic terminal ileum was obtained from CD patients undergoing ileocaecal resection due to stenosis. Gene expression of fibrosis markers and pH-sensing receptors was analysed. For the initiation of fibrosis in vivo, spontaneous colitis by Il10-/-, dextran sodium sulfate [DSS]-induced chronic colitis and the heterotopic intestinal transplantation model were used.

RESULTS

Increased expression of fibrosis markers was accompanied by an increase in OGR1 [2.71 ± 0.69 vs 1.18 ± 0.03, p = 0.016] in fibrosis-affected human terminal ileum, compared with the non-fibrotic resection margin. Positive correlation between OGR1 expression and pro-fibrotic cytokines [TGFB1 and CTGF] and pro-collagens was observed. The heterotopic animal model for intestinal fibrosis transplanted with terminal ileum from Ogr1-/- mice showed a decrease in mRNA expression of fibrosis markers as well as a decrease in collagen layer thickness and hydroxyproline compared with grafts from wild-type mice.

CONCLUSIONS

OGR1 expression was correlated with increased expression levels of pro-fibrotic genes and collagen deposition. Ogr1 deficiency was associated with a decrease in fibrosis formation. Targeting OGR1 may be a potential new treatment option for IBD-associated fibrosis.

Robot-assisted laparoscopic cystectomy with intracorporeal urinary diversion vs. open mini-laparotomy cystectomy: evaluation of surgical inflammatory response and immunosuppressive ability of CO2-pneumoperitoneum in an experimental porcine study

OBJECTS

To compare surgical inflammatory response (SIR) after radical cystectomy (RC) in a porcine model using minimal invasive techniques. Additionally we aimed to investigate the potential immunosuppressive ability of preoperative CO₂-pneumoperitoneum (CO₂P).

MATERIALS AND METHODS

Forty female landrace pigs were randomized to five groups: Three intervention groups all having a cystectomy and an ileal conduit either done by robot-assisted laparoscopic technique with intracorporeal urinary diversion (RALC) or an open mini-laparotomy with or without prior CO₂P (OMC ± CO₂P). Two control sham groups with or without prior CO₂P (S ± CO₂P). Serum samples were obtained preoperatively, immediately postoperative, 24, 48 and 72 hours postoperatively, and the inflammatory mediators CRP, Haptoglobin, Ceruloplasmin, Albumin, Cortisol, IL-4, IL-6, IL-12 and IFN-α were measured.

RESULTS

Operative time was significantly longer in RALC compared to open groups (OMC ± CO₂P) (p's < .0001). CRP and Haptoglobin levels were significantly higher for surgical intervention groups (SIG) compared to controls 24, 48 and 72 hours postoperatively (p's < .001). At 48 hours, CRP was higher for RALC vs OMC + CO₂P (p = .029). At 72 hours, Haptoglobin was higher for RALC vs open groups (p's < .024). Ceruloplasmin, cortisol, albumin, IL-4, IL-6, IL-12 and IFN-α, revealed no significant differences between SIG.

CONCLUSIONS

No major differences were found between RALC and OMC regarding the degree of tissue trauma quantified by inflammatory markers. Thirty minutes of CO_2-insufflation preoperative appears to have a transient immunosuppressive effect of the innate postoperative SIR, whereas prolonged CO₂P apparently diminishes this effect.

Neurodevelopment impact of CO2-pneumoperitoneum in neonates: experimental study in a rat model

BACKGROUND

Laparoscopy is becoming more common in neonates. However, concerns remain about the impact of the carbon-dioxide (CO₂)-insufflation over the neonatal brain. We aim to evaluate the peripheral (serum) and central (cerebrospinal fluid [CSF]) cytokine response after neonatal CO₂-pneumoperitoneum and its impact over neurodevelopmental milestones acquisition and long-term behavioral outcomes.

MATERIALS AND METHODS

Rats were subjected to a systematic assessment of neurodevelopmental milestones between postnatal day 1 (PND 1) and PND 21. At PND 10, neonatal rats were anesthetized, mechanically ventilated, and exposed to different pressures and times of abdominal CO₂-insufflation. Immediately after pneumoperitoneum, corticosterone was analyzed in serum. Twenty-four hours after intervention, serum and CSF were collected to assess inflammatory response (interleukin [IL]-10, IL-1β, tumor necrosis factor [TNF]-α, and interferon [IFN]-γ). In adulthood, animals from each group were submitted to several tests to assess different behavioral domains (locomotion, anxiety, mood, and cognition).

RESULTS

The antiinflammatory cytokine IL-10 was significantly increased in CSF in CO₂-insufflated groups, with no other significant changes in the other biomarkers. Acquisition of neurodevelopmental milestones was maintained in all studied groups. No significant differences were observed in adult behavior in the different CO₂-insufflation conditions.

CONCLUSIONS

Neonatal CO₂-pneumoperitoneum does not seem to have any negative impact on neurodevelopment or induce behavioral alterations in adulthood. Minimally invasive surgery results in a central antiinflammatory profile, and further studies on the functional consequences of these phenomena are needed.

Evaluation of robot-assisted laparoscopic versus open cystectomy and effect of carbon dioxide-pneumoperitoneum on histopathological findings in ureteroenteric anastomoses: results from an experimental randomized porcine study

OBJECTIVE

The aim of this study was to investigate the histopathology of ureteroenteric anastomoses (UEAs) after radical cystectomy (RC) with an ileal conduit in a porcine model using different surgical techniques. The study also evaluated the potential anti-inflammatory effect of preoperative carbon dioxide-pneumoperitoneum (CO₂P).

MATERIALS AND METHODS

Forty female Danish Landrace pigs were randomized to four groups: three intervention groups [open surgery ± prior CO₂P and robot-assisted laparoscopic cystectomy (RALC)], all subjected to RC and an ileal conduit, and one control group. After euthanization, UEAs were harvested and histopathologically evaluated.

RESULTS

Five pigs were excluded from the study owing to postoperative complications. Operating room time and clamping of the right and left ureters were significantly longer in the robotic than in the open groups (p < .01). Inflammatory infiltration grade of the left ureter was significantly higher in RALC (p = .032). No statistically significant difference was observed between the open groups receiving prior CO₂P or not.

CONCLUSIONS

Results showed a statistically significant higher inflammatory infiltration grade of the left ureter in RALC, emphasizing the importance of using meticulous techniques when mobilizing the left ureter using the robot. It was not possible to conclude with certainty whether CO₂P could constitute an anti-inflammatory agent for local inflammation.

Hypoxia Positively Regulates the Expression of pH-Sensing G-Protein-Coupled Receptor OGR1 (GPR68)

BACKGROUND & AIMS

A novel family of proton-sensing G-protein-coupled receptors, including ovarian cancer G-protein-coupled receptor 1 (OGR1) (GPR68) has been identified to play a role in pH homeostasis. Hypoxia is known to change tissue pH as a result of anaerobic glucose metabolism through the stabilization of hypoxia-inducible factor-1α. We investigated how hypoxia regulates the expression of OGR1 in the intestinal mucosa and associated cells.

METHODS

OGR1 expression in murine tumors, human colonic tissue, and myeloid cells was determined by quantitative reverse-transcription polymerase chain reaction. The influence of hypoxia on OGR1 expression was studied in monocytes/macrophages and intestinal mucosa of inflammatory bowel disease (IBD) patients. Changes in OGR1 expression in MonoMac6 (MM6) cells under hypoxia were determined upon stimulation with tumor necrosis factor (TNF), in the presence or absence of nuclear factor-κB (NF-κB) inhibitors. To study the molecular mechanisms involved, chromatin immunoprecipitation analysis of the OGR1 promoter was performed.

RESULTS

OGR1 expression was significantly higher in tumor tissue compared with normal murine colon tissue. Hypoxia positively regulated the expression of OGR1 in MM6 cells, mouse peritoneal macrophages, primary human intestinal macrophages, and colonic tissue from IBD patients. In MM6 cells, hypoxia-enhanced TNF-induced OGR1 expression was reversed by inhibition of NF-κB. In addition to the effect of TNF and hypoxia, OGR1 expression was increased further at low pH. Chromatin immunoprecipitation analysis showed that HIF-1α, but not NF-κB, binds to the promoter of OGR1 under hypoxia.

CONCLUSIONS

The enhancement of TNF- and hypoxia-induced OGR1 expression under low pH points to a positive feed-forward regulation of OGR1 activity in acidic conditions, and supports a role for OGR1 in the pathogenesis of IBD.

Changes in macrophage function modulated by the lipid environment

Macrophages (Mφs) play a critical role in the defense against pathogens, orchestrating the inflammatory response during injury and maintaining tissue homeostasis. During these processes, macrophages encounter a variety of environmental conditions that are likely to change their gene expression pattern, which modulates their function. In this study, we found that murine Mφs displayed two different subpopulations characterized by differences in morphologies, expression of surface markers and phagocytic capacity under non-stimulated conditions. These two subpopulations could be recapitulated by changes in the culture conditions. Thus, Mφs grown in suspension in the presence of serum were highly phagocytic, whereas subtraction of serum resulted in rapid attachment and reduced phagocytic activity. The difference in phagocytosis between these subpopulations was correlated with the expression levels of FcγR. These two cell subpopulations also differed in their responses to LPS and the expression of surface markers, including CD14, CD86, scavenger receptor A1, TLR4 and low-density lipoprotein receptor. Moreover, we found that the lipid/cholesterol content in the culture medium mediated the differences between these two cell subpopulations. Thus, we described a mechanism that modulates Mφ function depending on the exposure to lipids within their surrounding microenvironment.

Effects of carbon dioxide pneumoperitoneum on postoperative adhesion formation and oxidative stress in a rat cecal abrasion model

INTRODUCTION

It is claimed that CO2 pneumoperitoneum (CP) is less adhesiogenic than laparotomy. Our aim in this study was to investigate the local oxidative stress responses and related adhesion formation resulting from exposure to CP.

METHODS

Forty-five rats were randomised into six groups. Group 1 underwent laparotomy only; in group 2, 6 mmHg CP was performed for 60 min; in group 3, the same procedure was carried out using 12 mmHg CP; in group 4, laparotomy and cecal-peritoneal abrasion were performed; in group 5, 6 mmHg CP was performed for 60 min, followed by laparotomy and cecal-peritoneal abrasion; in group 6, the same procedure was carried out using 12 mmHg CP. Groups 1, 2 and 3 were sacrificed immediately and used only for biochemical examination. The other groups were sacrificed on the 14th postoperative day.

RESULTS

The total adhesion scores, thickness, quantity, extent and type of adhesions decreased steadily in groups 4, 5 and 6 (p < 0.05). The median values for neutrophil and monocyte infiltration, and for capillary and fibroblast proliferation decreased steadily in groups 4, 5 and 6 (p < 0.05). CAT, SOD and GSHPx levels decreased significantly in line with increasing pressure in groups 1, 2 and 3. SOD and GSHPx levels were similar in groups 4, 5 and 6, while CAT levels decreased with increasing pressure in groups 4, 5 and 6.

CONCLUSION

It was found that CP is associated with less adhesion formation than laparotomy in the presence of similar antioxidant levels. The reduced adhesion formation is probably caused by a decreased inflammatory response.

G Protein-coupled pH-sensing Receptor OGR1 Is a Regulator of Intestinal Inflammation

BACKGROUND

A novel family of proton-sensing G protein-coupled receptors, including OGR1, GPR4, and TDAG8, was identified to be important for physiological pH homeostasis and inflammation. Thus, we determined the function of proton-sensing OGR1 in the intestinal mucosa.

MTEHODS

OGR1 expression in colonic tissues was investigated in controls and patients with IBD. Expression of OGR1 upon cell activation was studied in the Mono Mac 6 (MM6) cell line and primary human and murine monocytes by real-time PCR. Ogr1 knockout mice were crossbred with Il-10 deficient mice and studied for more than 200 days. Microarray profiling was performed using Ogr1 and Ogr1 (WT) residential peritoneal macrophages.

RESULTS

Patients with IBD expressed higher levels of OGR1 in the mucosa than non-IBD controls. Treatment of MM6 cells with TNF, led to significant upregulation of OGR1 expression, which could be reversed by the presence of NF-κB inhibitors. Kaplan-Meier survival analysis showed a significantly delayed onset and progression of rectal prolapse in female Ogr1/Il-10 mice. These mice displayed significantly less rectal prolapses. Upregulation of gene expression, mediated by OGR1, in response to extracellular acidification in mouse macrophages was enriched for inflammation and immune response, actin cytoskeleton, and cell-adhesion gene pathways.

CONCLUSIONS

OGR1 expression is induced in cells of human macrophage lineage and primary human monocytes by TNF. NF-κB inhibition reverses the induction of OGR1 expression by TNF. OGR1 deficiency protects from spontaneous inflammation in the Il-10 knockout model. Our data indicate a pathophysiological role for pH-sensing receptor OGR1 during the pathogenesis of mucosal inflammation.

Oxidative stress in multi-port and single-port cholecystectomy

BACKGROUND

This study was designed to analyze and compare plasma levels of 8-isoprostane (8-epiPGF2α), a biomarker of lipid peroxidation, and uric acid (UA), a marker of the antioxidant status, in standard laparoscopic (LC) and laparoendoscopic single-site cholecystectomy (LSSC).

MATERIALS AND METHODS

Forty patients with noncomplicated cholelithiasis were randomized to undergo either LSSC (n = 20) or LC (n = 20). The patients had body mass index <30, American Society of Anesthesiologists score I or II, and no previous upper gastrointestinal surgery. Blood samples were taken preoperatively and 6 h and 24 h postoperatively. Levels of 8-epiPGF2α were determined using enzyme-linked immunosorbent assay, whereas levels of UA were calculated using automated analyzer.

RESULTS

No significant differences were observed in operative data among the groups. Levels of 8-epiPGF2α were significantly higher in LSSC compared with LC at 6 h (P = 0.003) and 24 h (P < 0.001). 8-epiPGF2α levels showed significant changes over time in LC (LSSC: P = 0.720, LC: P < 0.001). UA levels were significantly higher in LC compared with LSSC, 24 h postoperatively (P = 0.021). No significant changes over time in the UA levels in both groups (LSSC: P = 0.056, LC: P = 0.205).

CONCLUSIONS

LSSC is associated with increased oxidative stress compared with LC. Further studies are needed to confirm these results.

Lethal effect of a hyperthermic CO₂ pneumoperitoneum on gastric cancer cells

OBJECTIVES

We investigated the lethal effect of a hyperthermic CO₂ pneumoperitoneum on gastric cancer cells. This could form the theoretical basis for further studies of the feasibility and safety of inflating hyperthermic CO₂ in the abdominal cavity of gastric cancer patients during laparoscopy.

METHODS

An in vitro hyperthermic CO₂ pneumoperitoneum experimental model was built, where gastric cancer cell line SGC-7901 cells were grouped according to temperature. Cytotoxicity was detected using a cell counting kit; apoptosis was detected by Annexin V-FITC/PI flow cytometry and Hoechst 33342/PI fluorescent microscopy. Morphological alterations were observed by transmission electron microscopy. Invasion and migration were detected by a scratch test and by transwell migration, respectively.

RESULTS

Cytotoxicity assays showed that a hyperthermic CO₂ pneumoperitoneum significantly inhibited the proliferation of SGC-7901 cells (P<0.05); it also significantly induced apoptosis of SGC-7901 cells (P<0.05). Morphological observations showed that the cell membrane and nucleus had an apoptotic phenotype. The invasiveness and migration ability of the gastric cancer cells subjected to hyperthermic CO₂ were significantly reduced.

CONCLUSIONS

A hyperthermic CO₂ pneumoperitoneum had a lethal effect on gastric cancer SGC-7901 cells by inhibiting their invasion and migration, and by inducing apoptosis.

Perioperative advantages of modified laparoscopic vs open splenectomy and azygoportal disconnection

AIM: To investigate perioperative outcomes in patients undergoing modified laparoscopic splenectomy or open splenectomy and azygoportal disconnection for portal hypertension.

METHODS: This study included 44 patients who underwent modified laparoscopic splenectomy and azygoportal disconnection (MLSD) and 71 who underwent open procedures for portal hypertension. Blood samples were collected before surgery and on days 1, 3, and 7 after surgery. Markers of liver and renal function, C-reactive protein (CRP), interleukin-6 (IL-6), and procalcitonin (PCT) were measured, and perioperative variables were compared between the two groups.

RESULTS: The modified laparoscopic group showed significantly better and faster recovery, better liver and renal function, and fewer complications than the open group. CRP, IL-6, and PCT concentrations on postoperative days 1, 3, and 7 were significantly lower in the modified laparoscopic group than in the open group.

CONCLUSION: MLSD was associated with lower inflammatory immune responses, less impairment of liver and renal function, and faster and better recovery.

To perform operative procedures in an optimized local atmosphere: can it reduce post-operative adhesion formation?

BACKGROUND

Adhesion formation is a major problem following abdominal surgery as it creates a considerable economic burden in addition to an increased risk for complications. In the present study, an effort was made to reduce post-operative adhesion formation by creating an artificial atmosphere within and around the abdominal cavity during an open surgical procedure.

METHODS

82 Wistar male rats (Clr:WI) (200 gr, 7 weeks) were randomized into two groups. The abdominal cavity of the control group was exposed to the normal atmosphere of the operating-theatre during surgery (21% O₂, 21 °C, 40-47% relative humidity (RH)), while the abdominal cavity of the study group was exposed to an artificial atmosphere during surgery (3-6% O₂, >75% CO₂, 95-100% RH, 37 °C). Adhesion induction consisted of a laparotomy along linea-alba, four lesions in the anterior abdominal-wall, blood from the tail vein dripped inside the abdominal cavity and exposure to the atmosphere around the wound by use of self-retaining retractors. In addition, a liquid-sample for quantitative bacteriologic cultivation and bacterial load (CFU/ml) calculation was taken just before closure. After 3 weeks the abdominal cavity was scored for the extent, tenacity and severity of adhesions before the rats were euthanized. The two-sample-Wilcoxon-rank-sum test was used in the analysis.

RESULTS

Highly significant differences in postoperative total adhesion score, extent-, severity- and tenacity-score were found (P < 0.01). No differences were found between the two groups regarding mean bacterial load (P > 0.05).

CONCLUSIONS

The rats exposed to the warmed and humidified artificial atmosphere consisting of more than 75% carbon dioxide and 3-4% oxygen during surgery had more severe and more post-operative adhesions compared to the rats that were exposed to the ambient air during surgery.

Regulation of inflammation by extracellular acidification and proton-sensing GPCRs

Under ischemic and inflammatory circumstances, such as allergic airway asthma, rheumatoid arthritis, atherosclerosis, and tumors, extracellular acidification occurs due to the stimulation of anaerobic glycolysis. An acidic microenvironment has been shown to modulate pro-inflammatory or anti-inflammatory responses, including cyclooxygenase-2 (COX-2) expression, prostaglandin synthesis, and cytokine expression, in a variety of cell types, and thereby to exacerbate or ameliorate inflammation. However, molecular mechanisms underlying extracellular acidic pH-induced actions have not been fully understood. Recent studies have shown that ovarian cancer G protein-coupled receptor 1 (OGR1)-family G protein-coupled receptors (GPCRs) can sense extracellular pH or protons, which in turn stimulates intracellular signaling pathways and subsequent diverse cellular responses. In the present review, I discuss extracellular acidic pH-induced inflammatory responses and related responses in inflammatory cells, such as macrophages and neutrophils, and non-inflammatory cells, such as smooth muscle cells and endothelial cells, focusing especially on proton-sensing GPCRs.

Identification of macrophage genes responsive to extracellular acidification

OBJECTIVE

A low pH microenvironment is a characteristic feature of inflammation loci and affects the functions of immune cells. In this study, we investigated the effect of extracellular acidification on macrophage gene expression.

METHODS

RAW264.7 macrophages were incubated in neutral (pH 7.4) or acidic (pH 6.8) medium for 4 h. Global mRNA expression levels were determined using Affymetrix genechips.

RESULTS

The mRNA expressions of 353 macrophage genes were significantly modified after incubation in acidic medium; 193 were up-regulated and 160 down-regulated. Differentially regulated genes were grouped into 13 classes based on the functions of the corresponding protein products. Pathway analysis revealed that differentially expressed genes are enriched in pathways related to inflammation and immune responses. Quantitative real-time PCR analysis confirmed that the expressions of CXCL10, CXCL14, IL-18, IL-4RA, ABCA1, CCL4, IL-7R, CXCR4, TLR7, and CCL3 mRNAs were regulated by extracellular acidification.

CONCLUSION

The results of this study provide insights into the effects of acidic extracellular environments on macrophage gene expression.

Evaluation of exposure properties after injection of nanosuspensions and microsuspenions into the intraperitoneal space in rats

In the present paper, BA99 and AC88 were used as model compounds for intraperitoneal (i.p.) administration to Sprague-Dawley rats. A major problem for the compounds, like many others newly developed pharmaceutical drugs, is the poor solubility in water. To solve solubility related problems, development of nanosuspensions is an attractive alternative. Both compounds are suitable for nanosuspensions, using the milling approach. After 2 weeks in freezer, the nanoparticles aggregated to form particles in the 400-2000 nm interval. However, following a 20 s ultrasonication step, the original particle sizes (about 200 nm) were obtained. Adding 5% mannitol before the samples were frozen abolished aggregation. It is also possible to freeze-dry the nanosuspension in the presence of 5% mannitol and re-disperse the formulation in water. Nanosuspensions of both compounds were injected i.p. to rats at 5 and 500 µmoL/kg. At the low dose, also a microsuspension was administered. I.p. administration resulted in overall improved C(max) for both AC88 and BA99 compared to s.c. and oral administration. I.p. is the preferred route of administration of tolerable drugs when a fast onset of action is desired and when a significant first passage metabolism occurs. The net charge of the active molecule appeared to affect the absorption kinetics. In the present work, the neutral molecule was favored over the negatively charged one.

Effect of surgical procedures on prostate tumor gene expression profiles

Current surgical treatment of prostate cancer is typically accomplished by either open radical prostatectomy (ORP) or robotic-assisted laparoscopic radical prostatectomy (RALRP). Intra-operative procedural differences between the two surgical approaches may alter the molecular composition of resected surgical specimens, which are indispensable for molecular analysis and biomarker evaluation. The objective of this study is to investigate the effect of different surgical procedures on RNA quality and genome-wide expression signature. RNA integrity number (RIN) values were compared between total RNA samples extracted from consecutive LRP (n=11) and ORP (n=24) prostate specimens. Expression profiling was performed using the Agilent human whole-genome expression microarrays. Expression differences by surgical type were analyzed by Volcano plot analysis and gene ontology analysis. Quantitative reverse transcription (RT)-PCR was used for expression validation in an independent set of LRP (n=8) and ORP (n=8) samples. The LRP procedure did not compromise RNA integrity. Differential gene expression by surgery types was limited to a small subset of genes, the number of which was smaller than that expected by chance. Unexpectedly, this small subset of differentially expressed genes was enriched for those encoding transcription factors, oxygen transporters and other previously reported surgery-induced stress-response genes, and demonstrated unidirectional reduction in LRP specimens in comparison to ORP specimens. The effect of the LRP procedure on RNA quality and genome-wide transcript levels is negligible, supporting the suitability of LRP surgical specimens for routine molecular analysis. Blunted in vivo stress response in LRP specimens, likely mediated by CO(2) insufflation but not by longer ischemia time, is manifested in the reduced expression of stress-response genes in these specimens.

Temporal differences in the development of organ dysfunction based on two different approaches to induce experimental intra-abdominal hypertension in swine

BACKGROUND

Intra-abdominal hypertension [IAH] occurs frequently among critically ill patients and is associated with increased mortality and organ failure. Two porcine models of IAH that cause abdominal compartment syndrome [ACS] with organ dysfunction were created. We investigated whether the two methods used to create IAH - CO2 pneumoperitoneum or adding volume to the intra-abdominal space - exerted different impacts on the temporal development of organ dysfunction.

METHODS

Twenty-four 40-kg female pigs were allocated to four groups: 25 mmHg IAH with CO2 pneumoperitoneum (n = 8), >20 mmHg IAH caused by addition of volume (n = 8), and two corresponding sham groups (each n = 4). The two sham groups were later pooled into one control group (n = 8). The animals were monitored for 12 h. Repeated serial measurements were taken of group differences over time and analyzed using analysis of variance.

RESULTS

Thirty-eight percent of the animals (n = 3) in each intervention group died near the end of the 12-h experiment. Both intervention groups experienced kidney impairment: increased creatinine concentration (P <0.0001), anuria (P = 0.0005), hyperkalemia (P <0.0001), decreased abdominal perfusion pressure, and decreased dynamic lung compliance. CO2 pneumoperitoneum animals developed hypercapnia (P <0.0001) and acidosis (P <0.0001).

CONCLUSIONS

Both methods caused ACS and organ dysfunction within 12 h. Hypercapnia and acidosis developed in the CO2 pneumoperitoneum group.

Tumor necrosis factor expression is ameliorated after exposure to an acidic environment

BACKGROUND

It has been well established that laparoscopic surgery presents several clinical benefits, including reduced pain and a shorter hospital stay. These effects have been associated with a decrease in the inflammatory response. Previous studies have demonstrated that reduced inflammation after laparoscopic surgery is the product of carbon dioxide insufflation, which decreases peritoneal pH. The objective of this study was to investigate the cellular and molecular mechanisms responsible for the reduced response after exposure to acidic environments.

MATERIALS AND METHODS

A murine macrophage line (J744) was incubated in culture medium at pH 6.0 or pH 7.4 for 3 h at 37°C. Then, cells were stimulated with lipopolysaccharide (LPS) at pH 7.4, the expression of TNF-α (qRT-PCR or enzyme-linked immunosorbent assay (ELISA) and intracellular pH were measured. In addition, CD14 and Toll-like receptor 4 expression and NF-κB nuclear translocation were analyzed.

RESULTS

A significant decrease in LPS-induced TNF-α expression levels was observed in cells pre-incubated at pH 6.0 in comparison with cells at neutral pH conditions. This decrease in TNF-α levels was not associated with a reduction in cell surface expression of CD14 and Toll-like receptor 4. Exposure to an extracellular acidic environment resulted in a reduction of IκB phosphorylation and NF-κB nuclear translocation, secondary to a significant drop in cytosolic pH.

CONCLUSIONS

These observations provide a potential mechanism for the reduced expression of TNF-α after exposure to low extracellular pH, which may be related to acidification after CO(2) insufflation during laparoscopic surgery. In addition, extracellular acidic pH environments could emerge as an important regulator of macrophage function.

Extracellular low pH modulates phosphatidylserine-dependent phagocytosis in macrophages by increasing stabilin-1 expression

Microenvironmental acidosis is a common feature of inflammatory loci, in which clearance of apoptotic cells is necessary for the resolution of inflammation. Although it is known that a low pH environment affects immune function, its effect on apoptotic cell clearance by macrophages has not been fully investigated. Here, we show that treatment of macrophages with low pH medium resulted in increased expression of stabilin-1 out of several receptors, which are known to be involved in PS-dependent removal of apoptotic cells. Reporter assays showed that the -120/-1 region of the mouse stabilin-1 promoter was a low pH-responsive region and provided evidence that extracellular low pH mediated transcriptional activation of stabilin-1 via Ets-2. Furthermore, extracellular low pH activated JNK, thereby inducing translocation of Ets-2 into the nucleus. When macrophages were preincubated with low pH medium, phagocytosis of phosphatidylserine-exposed red blood cells and phosphatidylserine-coated beads by macrophages was enhanced. Blockade of stabilin-1 in macrophages abolished the enhancement of phagocytic activity by low pH. Thus, our results demonstrate that a low pH microenvironment up-regulates stabilin-1 expression in macrophages, thereby modulating the phagocytic capacity of macrophages, and suggest roles for stabilin-1 and Ets-2 in the maintenance of tissue homeostasis by the immune system.

Factors associated with the mediastinal spread of cervical necrotizing fasciitis

BACKGROUND

We conducted a study to determine factors associated with the occurrence of mediastinitis in patients hospitalized for cervical necrotizing fasciitis (CNF).

METHODS

We reviewed the medical records of 130 consecutive patients in an intensive care unit (ICU) who were hospitalized with a diagnosis of CNF. Two radiologists reviewed cervical and thoracic computed tomography (CT) scans to determine the source and extension of the infection in each patient.

RESULTS

Among the cohort of 130 patients with CNF, 37 (28%) had mediastinitis at the time of their admission (which in 13 cases was superior, or above the aortic arch, and in 24 cases inferior). Cervical necrotizing fasciitis complicated by mediastinitis resulted in a longer stay in the ICU than did CNF without mediastinitis, of a mean of 29 days (range, 18 to 39 days) versus 14 days (range, 9 to 19) days, respectively (p<0.0001). Multivariate analysis revealed that the presence of mediastinitis was associated with oral intake of glucocorticoids before admission (odds ratio [OR], 2.17; range, 0.99 to 4.76), a pharyngeal focus of CNF (OR, 2.17; range, 1.04 to 4.53), or gas seen on an initial CT scan (OR, 4.49; range, 2.15 to 9.38). Both a pharyngeal focus of fasciitis and the presence of gas were strong independent predictors of inferior mediastinitis (OR, 15.1; range, 4.9 to 46.4; p<0.0001).

CONCLUSIONS

The present study is the first to describe three independent factors associated with extension of cervical fasciitis to the thoracic cavity, including glucocorticoid intake before admission, and confirms previous reports of a high incidence of mediastinitis in patients with CNF.

Evaluation of serum cytokine release in response to hand-assisted, laparoscopic, and open surgery in a porcine model

BACKGROUND

Although the immunologic benefits of laparoscopic surgery have been established, effects from hand-assisted (HA) surgery have not been investigated thoroughly. We hypothesized that the HA approach maintains the immunologic advantage of laparoscopic surgery compared with the open (O) approach.

METHODS

Six O, HA, and laparoscopic (L) transabdominal left nephrectomies were performed on pigs. Blood samples were taken preoperatively, perioperatively, and postoperatively, and serum interleukin-6 and C-reactive protein levels were measured.

RESULTS

At 24 hours after surgery, interleukin-6 levels were significantly higher in the O group vs the HA and L groups (82.2 vs 37.5 and 29.9 pg/mL, respectively; P < .05). Similar trends were seen at all time periods for both IL-6 and C-reactive protein. No significant differences in postoperative cytokine levels were detected between the HA and L groups.

CONCLUSIONS

The HA approach mimics the immunologic effects of laparoscopic surgery. These data suggest that the HA technique resulted in a reduced systemic immune activation in the early perioperative period when compared with open surgery. In addition to clinical benefits of minimal access, the HA approach also may afford patients an immunologic advantage over laparotomy.

A prospective case-control study of the local and systemic cytokine response after laparoscopic versus open colonic surgery

BACKGROUND

There is a sequential, high concentration cytokine response after major abdominal surgery. The magnitude of this response has been directly linked to postoperative metabolic derangement, ileus, adhesions, and oncological outcomes. We aimed to compare the local and systemic cytokine response in laparoscopic and open colonic surgery and relate this to postoperative recovery parameters.

METHODS

Using a prospectively collected patient database, we compared a Study Group (n = 50) of patients undergoing elective laparoscopic colonic resection with a Control Group (n = 25) of patients undergoing equivalent open colonic surgery within an ERAS program. Patients were matched for age, gender, BMI, ASA, Cr Possum, side of resection, diagnosis, and histologic stage. Plasma and peritoneal fluid concentrations of IL-6, IL-8, IL-10, and TNFα were measured at 20-24 h after surgery. The Surgical Recovery Score was determined pre-operatively and at 3, 7, 30, and 60 d postoperatively. All data were prospectively collected, and a priori definitions were used for discharge parameters, complications, and complication severity.

RESULTS

Peritoneal fluid IL-6 concentration was lower after laparoscopic surgery. There were no significant differences in the other cytokines measured, or in any postoperative recovery outcomes. Significant correlations were found between cytokine levels and discharge criteria achievement, day stay, postoperative complications, and the Surgical Recovery Score.

CONCLUSION

With the exception of a lower peritoneal IL-6 level, the systemic and peritoneal cytokine response at 20-24 h is similar after laparoscopic versus open colonic resection within an ERAS program, with corresponding equivalent rates of postoperative recovery.

Extracellular acidification stimulates IL-6 production and Ca(2+) mobilization through proton-sensing OGR1 receptors in human airway smooth muscle cells

The asthmatic airway has been shown to be an acidic environment that may be involved in the pathophysiological features of asthma. However, the mechanism by which an acidic pH modulates the cellular activities involved in the asthmatic airway remains elusive. Here, we characterized acidic pH-induced actions in human airway smooth muscle cells (ASMCs). Extracellular acidification stimulates the mRNA expression and protein production of IL-6, a proinflammatory cytokine, in association with the phosphorylation of extracellular signal-regulated kinase (ERK) and p38MAPK, reflecting the activation of the enzymes. Acidification-induced cytokine production was inhibited by inhibitors of ERK and p38MAPK. Acidification also increased intracellular Ca(2+) concentration, which was accompanied by cell rounding, most likely reflecting contraction. In ASMCs, OGR1 is expressed at by far the highest levels among proton-sensing G protein-coupled receptors. The knockdown of OGR1 and G(q/11) protein with their specific small interfering RNAs and an inhibition of G(q/11) protein with YM-254890 attenuated the acidification-induced actions. We conclude that extracellular acidification stimulates IL-6 production and Ca(2+) mobilization through proton-sensing OGR1 receptors/G(q/11) proteins in human ASMCs.

The humoral response after laparoscopic versus open colorectal surgery: a meta-analysis

BACKGROUND

The local and systemic humoral response after colorectal surgery is thought to affect postoperative recovery. It is commonly claimed that laparoscopic surgery elicits a diminished inflammatory response than equivalent open surgery. Despite these claims, the evidence is conflicting. Therefore, we aimed to systematically review the results from randomized controlled clinical trials comparing the humoral response associated with laparoscopic versus open colorectal surgery.

MATERIALS AND METHODS

A high-sensitivity search was conducted independently by two of the authors with no language restriction. Studies were identified from the Cochrane Central Register of Controlled Trials (CENTRAL/CCTR), Cochrane Library, Medline (January 1966 to January 2009), PubMed (1950 to January 2009), and Embase (1947 to January 2009). Relevant meeting abstracts and reference lists were manually searched. Data analysis was performed using Review Manager ver. 5.0.

RESULTS

Thirteen randomized controlled trials were included. Meta-analysis demonstrated a significantly higher serum IL-6 on d 1 after open colorectal resection for neoplasia (n = 97) compared with laparoscopic resection (n = 76, P = 0.0008) without significant heterogeneity. Data for plasma IL-6 were heterogeneous, with no apparent difference between groups. No other significant differences were identified, and there were not enough data on local peritoneal humoral factors to allow meta-analysis.

CONCLUSION

Open colorectal resection for neoplasia is associated with higher postoperative serum levels of IL-6 on d 1 than equivalent laparoscopic surgery. The aetiology and clinical significance of this finding is uncertain, and further studies are required to elucidate any differences in the local humoral response which may be more clinically relevant in surgery for this indication.

Peritoneal changes due to laparoscopic surgery

Background

Laparoscopic surgery has been incorporated into common surgical practice. The peritoneum is an organ with various biologic functions that may be affected in different ways by laparoscopic and open techniques. Clinically, these alterations may be important in issues such as peritoneal metastasis and adhesion formation.

Methods

A literature search using the Pubmed and Cochrane databases identified articles focusing on the key issues of laparoscopy, peritoneum, inflammation, morphology, immunology, and fibrinolysis.

Results

Laparoscopic surgery induces alterations in the peritoneal integrity and causes local acidosis, probably due to peritoneal hypoxia. The local immune system and inflammation are modulated by a pneumoperitoneum. Additionally, the peritoneal plasmin system is inhibited, leading to peritoneal hypofibrinolysis.

Conclusion

Similar to open surgery, laparoscopic surgery affects both the integrity and biology of the peritoneum. These observations may have implications for various clinical conditions.

Peritoneal inflammatory response of natural orifice translumenal endoscopic surgery (NOTES) versus laparoscopy with carbon dioxide and air pneumoperitoneum

BACKGROUND

The immunologic and physiologic effects of natural orifice translumenal endoscopic surgery (NOTES) versus traditional surgical approaches are poorly understood. Previous investigations have shown that NOTES and laparoscopy share similar inflammatory cytokine profiles except for a possible late-phase tissue necrosis factor-alpha (TNF-alpha) depression with NOTES. The local peritoneal reaction and immunomodulatory influence of pneumoperitoneum agents in NOTES also are not known and may play an important role in altering the physiologic insult induced by NOTES.

METHODS

In this study, 51 animals were divided into four study groups, which respectively underwent abdominal exploration via transgastric NOTES using room air (AIR) or carbon dioxide (CO(2)) or via laparoscopy (LX) using AIR or CO(2) for pneumoperitoneum. Laparotomy and sham surgeries were additionally performed as control conditions. Measurements of TNF-alpha, interleukin-1beta (IL-1beta), and IL-6 were performed for peritoneal fluid collected after 0, 2, 4, and 6 h and on postoperative days (PODs) 1, 2, and 7.

RESULTS

Of the 45 animals assessed, 6 were excluded because of technical operative complications. The findings showed that LX-CO(2) generated the most pronounced response with all three inflammatory markers. However, no significant differences were detected between LX-CO(2) and either NOTES group at these peak points. No differences were encountered between NOTES-CO(2) and NOTES-AIR. Subgroup comparisons showed significantly higher levels of TNF-alpha and IL-6 with NOTES-CO(2) than with LX-AIR on POD 1 (p = 0.022) and POD 2 (p = 0.002). The LX-CO(2) subgroup had significantly higher levels of TNF-alpha than the LX-AIR subgroup at 4 h (p = 0.013) and on POD 1 (p = 0.021). No late-phase TNF-alpha depression occurred in the NOTES animals.

CONCLUSION

The local inflammatory reaction to NOTES was similar to that with traditional laparoscopy, and the previously described late-phase systemic TNF-alpha depression in serum was not reproduced. At the peritoneal level, NOTES is no more physiologically stressful than laparoscopy. Furthermore, regardless of which gas was used, the role of the pneumoperitoneum agent did not affect the cytokine profile after NOTES, suggesting that air pneumoperitoneum is adequate for NOTES.

The transient receptor potential vanilloid-1 channel in thermoregulation: a thermosensor it is not

The development of antagonists of the transient receptor potential vanilloid-1 (TRPV1) channel as pain therapeutics has revealed that these compounds cause hyperthermia in humans. This undesirable on-target side effect has triggered a surge of interest in the role of TRPV1 in thermoregulation and revived the hypothesis that TRPV1 channels serve as thermosensors. We review literature data on the distribution of TRPV1 channels in the body and on thermoregulatory responses to TRPV1 agonists and antagonists. We propose that two principal populations of TRPV1-expressing cells have connections with efferent thermoeffector pathways: 1) first-order sensory (polymodal), glutamatergic dorsal-root (and possibly nodose) ganglia neurons that innervate the abdominal viscera and 2) higher-order sensory, glutamatergic neurons presumably located in the median preoptic hypothalamic nucleus. We further hypothesize that all thermoregulatory responses to TRPV1 agonists and antagonists and thermoregulatory manifestations of TRPV1 desensitization stem from primary actions on these two neuronal populations. Agonists act primarily centrally on population 2; antagonists act primarily peripherally on population 1. We analyze what roles TRPV1 might play in thermoregulation and conclude that this channel does not serve as a thermosensor, at least not under physiological conditions. In the hypothalamus, TRPV1 channels are inactive at common brain temperatures. In the abdomen, TRPV1 channels are tonically activated, but not by temperature. However, tonic activation of visceral TRPV1 by nonthermal factors suppresses autonomic cold-defense effectors and, consequently, body temperature. Blockade of this activation by TRPV1 antagonists disinhibits thermoeffectors and causes hyperthermia. Strategies for creating hyperthermia-free TRPV1 antagonists are outlined. The potential physiological and pathological significance of TRPV1-mediated thermoregulatory effects is discussed.

Perforin expression in peripheral blood lymphatic cells of patients subjected to laparoscopic or open cholecystectomy

Perforin-(P-) related characteristics of cytotoxic T lymphocytes and natural killer cells were investigated in peripheral blood of patients subjected to open (OC; n = 23) or laparoscopic cholecystectomy (LC; n = 21) and healthy controls (n = 20). Blood samples were obtained preoperatively and 24 hours after the surgeries, and the data were correlated with the intensity of cholestasis and concomitant inflammation, determined by functional hepatic tests. Postoperative differences were found to be minimal: OC decreased only the percentage of CD56⁺ cells, while LC decreased the fraction of CD8⁺P⁺ cells and augmented the mean fluorescence intensity of P in CD56 cells. Patients elected for OC had, however, higher preoperative numbers of total P⁺, CD3⁺P⁺, and CD4⁺P⁺ cells than patients elected for LC and healthy controls, while both groups of patients, preoperatively, had lower fraction of CD16⁺P⁺ and CD56⁺P⁺ cells. These changes were in high correlation with blood concentrations of CRP, AP, and ALT, emphasizing the link between the preoperative cholestasis and inflammation and P-dependent cytotoxic mechanisms.

Involvement of proton-sensing TDAG8 in extracellular acidification-induced inhibition of proinflammatory cytokine production in peritoneal macrophages

Extracellular acidification inhibited LPS-induced TNF-alpha protein production, which was associated with an inhibition of TNF-alpha mRNA expression, in mouse peritoneal macrophages. The LPS-induced cytokine production was also inhibited by G(s) protein-coupled receptor agonists prostaglandin E(1) and isoproterenol. Among OGR1 family proton-sensing GTP-binding regulatory protein-coupled receptors, TDAG8, OGR1, and G2A are expressed in the cells. The inhibitory action by acidic pH on TNF-alpha production was significantly attenuated in macrophages from TDAG8(Tp/Tp) mice but not in those from OGR1(geo/geo) mice. Moreover, small interfering RNA specific to TDAG8, but not to G2A, clearly attenuated the acidification-induced inhibition of TNF-alpha production. On the other hand, the down-regulation or deficiency of TDAG8 hardly affected prostaglandin E(1)- or isoproterenol-induced actions. LPS-induced IL-6 production was also inhibited by extracellular acidification in a manner that was sensitive to TDAG8 expression. The acidic pH-induced inhibitory action on the cytokine production was significantly reversed either by a small interfering RNA specific to G(s) proteins or by a protein kinase A (PKA)-specific inhibitor H89. Indeed, a PKA-specific cAMP derivative inhibited LPS-induced cytokine production. Moreover, acidification induced cAMP accumulation in a TDAG8-specific way. We conclude that TDAG8, at least partly, mediates the extracellular acidification-induced inhibition of proinflammatory cytokine production through the G(s) protein/cAMP/PKA signaling pathway in mouse macrophages.

CO(2) pneumoperitoneum prolongs survival in an animal model of peritonitis compared to laparotomy

BACKGROUND

The advantages of laparoscopic surgery have been well documented. However, the impact of pneumoperitoneum on sepsis sequelae is still equivocal. This study aimed to evaluate the effect of CO(2) pneumoperitoneum, applied under different pressures and exposure times, on sepsis cascade and mortality.

MATERIAL AND METHODS

In 42 New Zealand rabbits, peritonitis was induced by the cecum ligation and puncture model. After 12 h, the animals were randomized in seven groups: a control group, four groups with pneumoperitoneum (10-15 mmHg for 60-180 min), and two groups with laparotomy (for 60 and 180 min). Blood samples were collected before cecum ligation and puncture, 12 h later and 1, 3, and 6 h after pneumoperitoneum desufflation or abdominal trauma closure to evaluate bacteremia, endotoxemia, white blood cells count, C-reactive protein, and procalcitonin levels. Furthermore, the mortality time was recorded in all animals.

RESULTS

Bacteremia and endotoxemia were induced in all groups. Endotoxemia levels were significantly more elevated in the group where pneumoperitoneum was performed under 15 mmHg for 180 min compared with all other groups at 1 and 3 h after pneumoperitoneum desufflation (P < 0.05), except when compared with the group where pneumoperitoneum was performed under 10 mmHg for 180 min. White blood cell and C-reactive protein levels showed similar trends for all groups. However, serum procalcitonin reached statistically higher levels (P < 0.05) in groups with laparotomy compared with groups with pneumoperitoneum and with the control group at 6 h. Survival was lower in the laparotomy groups compared with the pneumoperitoneum groups and with the control group (P < 0.05).

CONCLUSIONS

In the presence of peritonitis, CO(2) pneumoperitoneum applied in clinically standard pressures, even for extended time intervals, reduces the severity of sepsis and prolongs survival.

Carbon dioxide inhalation causes pulmonary inflammation

The aim of this study was to assess whether one of the most common poisons of cellular respiration, i.e., carbon dioxide, is proinflammatory. CO(2) is naturally present in the atmosphere at the level of 0.038% and involved in numerous cellular biochemical reactions. We analyzed in vitro the inflammation response induced by exposure to CO(2) for 48 h (0-20% with a constant O(2) concentration of 21%). In vivo mice were submitted to increasing concentrations of CO(2) (0, 5, 10, and 15% with a constant O(2) concentration of 21%) for 1 h. The exposure to concentrations above 5% of CO(2) resulted in the increased transcription (RNase protection assay) and secretion (ELISA) of proinflammatory cytokines [macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, MIP-2, IL-8, IL-6, monocyte chemoattractant protein-1, and regulated upon activation, normal T cell expressed, and, presumably, secreted (RANTES)] by epithelial cell lines HT-29 or A549 and primary pulmonary cells retrieved from the exposed mice. Lung inflammation was also demonstrated in vivo by mucin 5AC-enhanced production and airway hyperreactivity induction. This response was mostly mediated by the nuclear translocation of p65 NF-kappaB, itself a consequence of protein phosphatase 2A (PP2A) activation. Short inhibiting RNAs (siRNAs) targeted toward PP2Ac reversed the effect of carbon dioxide, i.e., disrupted the NF-kappaB activation and the proinflammatory cytokine secretion. In conclusion, this study strongly suggests that exposure to carbon dioxide may be more toxic than previously thought. This may be relevant for carcinogenic effects of combustion products.

The comparative effects of pneumoperitoneum on apoptosis and p53 expression in gastrointestinal organs

BACKGROUND

Laparoscopic surgical techniques have been increasingly preferred to classic laparotomy by surgeons since 1987. The pneumoperitoneum is often used to facilitate the intra-abdominal field, but it carries the risk of its ischemic potential and has differences [l2]of metabolic, inflammatory, and infectious consequences, depending on the pressure set and kind of gas used. However, the mechanisms related with the cell injury observed after laparoscopy are still unknown. The aim of this study was to evaluate the effects of different pressures of CO(2) on apoptosis and p53 expression in small and large intestines and the stomach.

MATERIALS AND METHODS

In total, 30 Sprague-Dawley male rats were used in the study. CO(2) is insufflated into the intra-abdominal cavity through a angiocatheter cannule by an insufflator set at two different pressures of 10 and 20 mm Hg during 60 minutes. In the control group, the cannule was inserted into the intra-abdominal cavity without any other surgical procedure and no gas was insufflated. After 60 minutes, the rats were sacrificed and a laparotomy was performed. The small and large intestines and stomach were excised. The samples were histologically processed and an immunohistochemical analysis was performed.

RESULTS

The results of the study revealed that the number of apoptotic cells in intra-abdominal organs we studied increased in proportion to the CO(2) pressure level. However, the p53 expression was detected only in the stomach.

CONCLUSIONS

Our study showed that the number of apoptotic cells rises in parallel to the increase in intra-abdominal pressure following the CO(2) pneumoperitoneum in rat large and small intestine and stomach. Although the apoptosis was activated by the p53 pathway in the stomach, it was not so in the large and small intestine.

Immunologic parameters during NOTES compared with laparoscopy in a randomized blinded porcine trial

BACKGROUND

It remains unclear if the natural orifice translumenal endoscopic surgery (NOTES) technique is less invasive than laparoscopy. Serum interleukins and peritoneal cellular response have been utilized to support the immunologic difference between open and laparoscopic surgery. We hypothesized that there would be no difference between cytokine levels during NOTES or laparoscopic peritoneoscopy.

METHODS

Twelve pigs were assigned to NOTES or standard laparoscopy with permuted block randomization. Each group underwent 90 min of diagnostic peritoneoscopy using CO(2) for laparoscopy and air for NOTES pneumoperitoneum. Blood draws were obtained at baseline, at procedure end, and on postoperative days (POD) 1, 2, and 7. Quantification of cytokines (IL-1b and TNF-alpha) was performed with a Duo Set Porcine enzyme-linked immunosorbent assay (ELISA). Laboratory results were captured by a technician blinded to the research question, and data analysis was performed by an investigator blinded to the procedure using t-test and repeated measures linear model. The study was approved by the institutional animal care and use committee (IACUC).

RESULTS

All procedures were successfully completed. One NOTES animal succumbed to hemorrhagic gastritis (day 3). All other animals thrived to POD 14, with no gross infections at necropsy. Animals undergoing laparoscopy had lower mean arterial pH than NOTES animals (p < 0.001). Serum and intraperitoneal white blood cell (WBC) counts were similar between the groups. Mean interleukin-1b levels at baseline, at the end of the procedure and at 48 h did not differ (0.50 and 0.31; p = 0.65). TNF-alpha levels did not differ at baseline or procedure end but increased in the NOTES group on POD 1, persisting to POD 7. Tumor necrosis factor-alpha (TNF-alpha) decreased in the laparoscopy group (p = 0.005).

CONCLUSION

Cytokines and WBC did not differ between laparoscopic and NOTES groups during the initial 24 h. These findings do not currently support the assumption that NOTES is less invasive than laparoscopy. The late TNF-alpha elevation contradicts other studies and requires further examination.