Peritoneal Cytokine Research Articles

A Prospective Case-Control Study of the Local and Systemic Cytokine Response After Laparoscopic Versus Open Colonic Surgery

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. 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. 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. 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.

Early Detection of Anastomotic Leakage After Elective Low Anterior Resection

BackgroundColorectal anastomotic leakage is a serious complication leading to major postoperative morbidity and mortality. In the present study, we investigated the early detection of anastomotic leakage before its clinical presentation. MethodFifty-six patients with rectal cancer were included prospectively in this study. All patients underwent elective low anterior resection. Peritoneal samples were collected from the abdominal drains at the first, third, and fifth days postoperatively for bacteriological study (quantitative cultures for both aerobes and anaerobes) and cytokines (IL-6, IL-10, TNF) measurement. Patients were divided into two groups: those without symptomatic or clinical evidence of anastomotic leakage (AL; group 1) and those with clinical evidence of AL (group 2). Study variables included hospital stay, wound infection, operative time, blood loss, height of anastomosis, intraperitoneal cytokines, and microbiological study of peritoneal fluid. ResultClinically evident AL occurred in eight patients (14.3%) and diagnosed postoperatively on median day 6. Intraperitoneal bacterial colonization and cytokine levels were significantly higher in patients with clinical evidence of AL. Wound infection was significantly higher in anastomotic leakage group. The hospital stay for the patients with anastomotic leakage was significantly longer than those without AL (14 ± 1.41 vs. 5.43±0.89 days). A significant difference among two groups was observed regarding operative time, blood loss, blood transfusion, and height of the anastomosis. ConclusionThe peritoneal cytokines levels and intraperitoneal bacterial colonization might be an additional diagnostic tool that can support the decision making of surgeons for early detection of anastomotic leak in colorectal surgery.

Impact of microbial tolerance in persistent secondary Klebsiella pneumoniae peritonitis

Purpose and methodsMicrobial tolerance represents a diminished pro-inflammatory response following repeated stimulation by a host of pathogen-associated molecular patterns (PAMPs) of varying origins. Toll-like receptors (TLRs) have been centrally implicated in the development of tolerance. The purpose of this study was to investigate the impact of tolerance in a previously described murine model.C57BL/6 mice were pretreated intraperitoneally with phosphate buffered saline (PBS), heat-killed Klebsiella 2×108 CFU (hkKlebsiella), LPS 10mg/kg (LPS 10), or BLP 10mg/kg (BLP 10). Following pretreatment, peritonitis was induced 24h later using 103 intraperitoneal Klebsiella CFU. Peritoneal concentrations of TNF-α, IL-10 and nitric oxide (NO), as well as characteristic cell patterns, were determined. Long-term consequences of microbial tolerance were assessed by measuring survival and weight-loss. ResultsFollowing in vitro stimulation with Klebsiella 105 and 103 CFU, TNF-α and IL-10 secretion were diminished in macrophages harvested from mice pretreated with hkKlebsiella, LPS 10 and BLP 10. Pretreated animals had significantly lower bacterial counts. Conversely, local NO levels were elevated. Survival was not different between the groups. ConclusionPretreatment with TLR ligands induced microbial tolerance, with reduced peritoneal cytokine concentrations and enhanced early bacterial clearance. However, this did not translate into improved survival.

Peritoneal Cytokines Predict Mortality after Surgical Treatment of Secondary Peritonitis in the Rat

The study aimed to analyze if peritoneal cytokine levels can predict survival in an experimental model for peritonitis. Early identification of patients most at risk for adverse outcomes would facilitate the decision for aggressive therapy in order to maximally exploit their chance for survival. Peritonitis was induced by intraperitoneal injection of a feces/bacteria mixture in 175 rats. Surgical debridement was performed after 1 hour. Abdominal fluid samples were taken after 24 and 72 hours for the measurement of interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-alpha. Surviving animals were sacrificed after 5 days and correlations between cytokine levels and survival were analyzed. Altogether, 60 animals died prematurely, 12 before the first sampling of cytokines. So, 48 nonsurvivors and 115 survivors were analyzed. Peritoneal cytokine levels were much higher (p < 0.0001) in nonsurvivors than in survivors. At 24 hours there were strong correlations between cytokine levels, especially between IL-6 and IL-10 (r = 0.93). Peritoneal cytokines at 24 hours also discriminated between animals dying within the next 24 hours and those dying later. A strongly (p < 0.0001) increased mortality was observed if IL-6, IL-10, or TNF-alpha levels exceeded 2, 1, or 0.2 ng/mL, respectively. Receiver operating characteristic curves were promising for all 3, but IL-10 showed the best characteristics, with an area under the curve of 0.94 and 67% sensitivity at 95% specificity, obtained at a cut-off value of 1.26 ng/mL. These data should generate renewed interest to examine the peritoneal cytokines as early markers for adverse outcomes in patients with secondary peritonitis. Possibly, combinations of peritoneal cytokines with other markers can lead to much needed, reliable early prediction of disease severity.

Warming and Humidification of Insufflation Carbon Dioxide in Laparoscopic Colonic Surgery

We aimed to test the hypothesis that warming and humidification of insufflation CO2 would lead to reduced postoperative pain and improved recovery by reducing peritoneal inflammation in laparoscopic colonic surgery. Warming and humidification of insufflation gas is thought be beneficial in laparoscopic surgery, but evidence in prolonged laparoscopic procedures is lacking. We used a multicenter, double-blinded, randomized controlled design. The Study Group received warmed (37 degrees C), humidified (98% RH) insufflation carbon dioxide, and the Control Group received standard gas (19 degrees C, 0% RH). Anesthesia and analgesia were standardized. Intraoperative oesophageal temperature was measured at 15 minutes intervals. At the conclusion of surgery, the primary surgeon was asked to rate camera fogging on a Likert scale. Postoperative opiate usage was determined using Morphine Equivalent Daily Dose (MEDD), and pain was measured using visual analogue scores. Peritoneal and plasma cytokine concentrations were measured at 20 hours postoperatively. Postoperative recovery was measured using defined discharge and complication criteria, and the Surgical Recovery Score. Eighty-two patients were randomized, with 41 in each arm. Groups were well matched at baseline. Intraoperative core temperature was similar in both groups. Median camera fogging score was significantly worse in the Study group (4 vs. 2, P = 0.040). There were marginal differences in pain scores, but no significant differences were detected in MEDD usage, cytokine concentrations, or any recovery parameters measured. Warming and humidification of insufflation CO2 does not attenuate the early inflammatory cytokine response, and confers no clinically significant benefit in laparoscopic colonic surgery.

Systemic and peritoneal inflammatory response after laparoscopic-assisted gastrectomy and the effect of inflammatory cytokines on adhesion of gastric cancer cells to peritoneal mesothelial cells

There still remain concerns over the potential for peritoneal metastasis after laparoscopic surgery. We designed this trial to investigate the effects of the inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) on the interaction between gastric cancer cells and mesothelial cells, and to evaluate differences in both the peritoneal and systemic cytokine (IL-1β and TNF-α) concentrations after laparoscopic and conventional surgical approaches, thus offering another possible advantage of laparoscopic procedures for treatment of gastric cancer. A reproducible human in vitro assay was developed to study adhesion of SGC-7901 and MKN-45 human gastric cancer cells to monolayers of primary cultured human peritoneal mesothelial cells (HPMCs). Tumor cell adhesion to a mesothelial monolayer was assessed after preincubation of the monolayer with IL-1β and TNF-α using flow cytometry. Expression of adhesion molecules (ICAM-1, VCAM-1, and CD44) and their counterparts (LFA-1 and VLA-4) was investigated by real-time polymerase chain reaction (PCR) immunocytochemical staining. Furthermore, the proinflammatory cytokines IL-1β and TNF-α were measured perioperatively in peritoneal drain fluid and in serum by enzyme immunoassay. Preincubation of the mesothelial monolayer with IL-1β and TNF-α resulted in enhanced tumor cell adhesion of SGC-7901 and MKN-45 cells. Mesothelial cells showed significant enhancement of expression of ICAM-1, VCAM-1, and CD44 after stimulation with IL-1β and TNF-α. Meanwhile their counterparts (LFA-1, VLA-4, and CD44) were identified in gastric cancer cells. The level of IL-1β in peritoneal drain fluid and in serum perioperatively in the laparoscopy-assisted gastrectomy group was lower than in the conventional open gastrectomy group, whereas there were no significant differences between the laparoscopic-assisted distal gastrectomy (LADG) and conventional open distal gastrectomy(CODG) groups with respect to TNF-α. The presented results prove that IL-1β and TNF-α are significant stimulating factors in gastric cancer cell adhesion in vitro and may therefore partly account for local tumor recurrence and peritoneal metastasis in vivo. Owing to less impact on the postoperative abdominal regional and systemic immune responses, laparoscopic surgery not only shows clinically relevant advantages but also causes less effect of inflammatory factors on local recurrence and peritoneal metastasis of gastric cancer than conventional operations. Thus, we offer another possible advantage of laparoscopic procedures for treatment of gastric cancer.

The Complement System Facilitates Clearance ofEnterococcus faeciumduring Murine Peritonitis

Infections with multidrug-resistant enterococci are a growing problem worldwide. Little is known about the host defense against enterococcal diseases. In vitro studies have demonstrated an important role played by complement proteins in neutrophil-mediated phagocytosis. In this study, we investigated the importance of complement in an in vivo model of Enterococcus faecium peritonitis. Peripheral neutrophils and peritoneal macrophages were incubated with E. faecium that had been preincubated with decomplemented or normal plasma, and phagocytosis and killing were examined. E. faecium peritonitis was induced in C57BL/6 mice rendered complement deficient by intraperitoneal injection with cobra venom factor (CVF) and in complement 3 (C3) knockout mice. The course of the infection was compared with that in saline control and wild-type mice, respectively, at several time points up to 48 h after infection. Opsonization by complement enhanced phagocytosis by neutrophils and macrophages. CVF-treated and C3 knockout mice were severely hampered in clearing E. faecium from all organs and tissues under study (peritoneal fluid, blood, lungs, and liver). Higher peritoneal cytokine and chemokine levels were measured in decomplemented mice, whereas no differences in systemic or peritoneal cell kinetics were detected. Complement deficiency severely hampers the clearance of E. faecium peritonitis and subsequent systemic infection.

Correlation between symptoms of pain and peritoneal fluid inflammatory cytokine concentrations in endometriosis

Endometriosis affects 10–20% of women during reproductive age and is a common cause of infertility and pain leading to work absenteeism and reduced quality of life.The objective of this study was to investigate the association between the presence and concentration of interleukin-8 (IL-8), RANTES, osteoprotegerin (OPG), pregnancy-associated plasma protein A (PAPP-A), tumour necrosis factor-α (TNF-α), midkine and glycodelin in the peritoneal fluid (PF) and the intensity of pain reported by patients undergoing laparoscopy in our clinic. They rated their pain during menstruation, intercourse and lower abdominal using a visual analogue scale. During laparoscopy, PF was aspirated. Pain scores were correlated to the concentration of the above substances in the PF and to the stage of endometriosis. Endometriosis was histologically confirmed in 41 of 68 participating women; 27 without such evidence were considered as controls. TNF-α and glycodelin correlated positively with the level of menstrual pain. For IL-8, RANTES, OPG and PAPP-A no correlation between their PF concentration and the menstrual pain scores was observed. Patients with severe dysmenorrhoea had increased PF cytokine and marker levels; the difference was significant for TNF-α and glycodelin when compared with the other patients (no or moderate pain). TNF-α and glycodelin may thus play a role in endometriosis and the severity of menstrual pain.

Randomized clinical trial of the effect of glucocorticoids on peritoneal inflammation and postoperative recovery after colectomy

Recent data have suggested a relationship between postoperative fatigue and the peritoneal cytokine response after surgery. The aim of this study was to test the hypothesis that preoperative administration of glucocorticoids before surgery would decrease fatigue and enhance recovery, by reducing the peritoneal production of cytokines. In a double-blind randomized controlled study, patients undergoing elective, open colonic resection were administered 8 mg dexamethasone or normal saline. Patients were treated within an enhanced recovery after surgery programme. Primary outcomes were cytokine levels in peritoneal drain fluid and fatigue as measured by the Identity-Consequence Fatigue Scale (ICFS). Baseline parameters were similar for 29 patients in the dexamethasone group and 31 in the placebo group. Patients who received dexamethasone had lower ICFS scores on days 3 and 7. Dexamethasone was associated with significantly lower peritoneal fluid interleukin (IL) 6 and IL-13 concentrations on day 1, and these correlated with changes in the ICFS score. There was no significant increase in adverse events in the dexamethasone group. Preoperative administration of dexamethasone resulted in a significant reduction in early postoperative fatigue, associated with an attenuated early peritoneal cytokine response. Peritoneal production of cytokines may therefore be important in postoperative recovery. ACTRN12607000066482 (http://www.anzctr.org.au/).

Early Identification of Infectious Complications in Bariatric Surgery by the Determination of Peritoneal and Systemic Cytokines

Obesity has become a global epidemic and bariatric surgery is one of the therapeutic tools to deal with it. Postoperative complications can occur, such as staple line dehiscence and anastomotic leaks, leading to increased patient mortality. The diagnosis of these complications is frequently difficult. The objective of the present study was to determine whether peritoneal and systemic cytokines could early detect those complications. All patients who underwent open Roux-en-Y gastric bypass from February 2007 to August 2008 were prospectively evaluated. Blood and peritoneal effluent from the drain were collected for the determination of cytokine levels. We also evaluated the clinical signs and the leukograms of the patients. A total of 107 obese patients were studied. Ninety patients had no complications; 17 had at least one infectious complication which include five cases of staple line dehiscence. Until the third postoperative day, the vital signs and the leukogram did not predict the onset of infectious complications, but the cytokines (interleukin-1beta and interleukin-6) were early markers of these complications. Cytokines are good predictors of poor postoperative evolution in bariatric surgery since peritoneal cytokines diagnose better these infectious complications even before changes in blood count and before the occurrence of clinical manifestations.

Intraperitoneal Vascular Endothelial Growth Factor C Level Is Related to Peritoneal Dialysis Ultrafiltration

Background: Local inflammation and neovascularization have a negative influence on peritoneal dialysis (PD). Patients with higher peritoneal transport have higher interleukin-6 (IL-6) and vascular endothelial growth factor-A (VEGF-A) levels in their dialysate. However, the relationship of other members of the VEGF family, such as VEGF-C, to peritoneal transport or ultrafiltration (UF) is yet to be studied. Methods: Peritoneal cytokine and growth factor levels were determined during the peritoneal equilibration test (PET). Ultrafiltration, peritoneal clearance and residual renal function were also considered. Results: Forty-two PD patients were enrolled. They had been on PD for at least 1 month and free of peritonitis for at least 1 month prior to the study. Patients with high or high average PET had higher dialysate IL-6 and VEGF-C. Dialysate IL-6 and VEGF-C correlated negatively with PET and UF. Conclusions: Dialysate VEGF-C is related to higher transport rate and poorer UF. The role of VEGF-C in PD deserves further study.

CR04 *DOUBLE BLIND RANDOMISED CONTROLLED TRIAL OF THE INFLUENCE OF GLUCOCORTICOIDS ON POST‐OPERATIVE RECOVERY FOLLOWING COLECTOMY

Introduction: Post‐operative fatigue (POF) is an important indicator of recovery after major surgery. Recent data have suggested a relationship between the post‐operative peritoneal cytokine response and development of POF. Glucocorticoids decrease the production of cytokines and thus we hypothesised that administration of dexamethasone to patients undergoing colonic surgery may decrease peritoneal cytokine production and POF.Aim: To assess the influence of 8 mg of pre‐op IV Dexamethasone on peritoneal cytokine and POF in patients undergoing elective colonic surgery. Method: In a double blinded RCT, 70 consecutive patients undergoing elective, open colonic resection were administered 8 mg I.V. Dexamethasone or saline (Placebo) prior to surgery. All patients were treated within a structured Enhanced Recovery After Surgery program.Results: After exclusions there were 31 patients in the Placebo group and 29 in the Dex group. At baseline there were no differences in the age, ASA, BMI or CR‐POSSUM scores. Dexamethasone was associated with a significant reduction in Interleukin‐6 (IL‐6) and IL‐13 in the peritoneum and IL‐6 and IL‐8 in plasma. Subsequently, patients in the Dex group had lesser POF and fatigue impact scores at days 3 and 7. Patients in the Dex group had less post‐op nausea and vomiting. There was no significant increase in complications.Conclusion: Preoperative Dexamethasone administration is associated with a significantly diminished post‐operative pro‐inflammatory reaction which is associated with clinical benefits in POF and its impact. This intervention may be an effective method of improving outcomes for patients undergoing major colonic surgery within a multimodal enhanced peri‐operative care pathway.

Peritoneal macrophages are important for the early containment of Enterococcus faecium peritonitis in mice

The increasing incidence of infections with multi-drug resistant Enterococcus faecium necessitates studies to increase knowledge on the pathogenesis of these infections. In this study, the contribution of peritoneal macrophages during E. faecium peritonitis was investigated. In an ex vivo setting, peritoneal macrophages harvested from C57BL/6 mice were responsive to, and able to phagocytose and kill, E. faecium. In vivo, peritoneal macrophages were depleted by intraperitoneal injection of clodronate-encapsulated liposomes, prior to inducing E. faecium peritonitis. Depletion of resident peritoneal macrophages caused a clear delay in peritoneal clearance of E. faecium with increased systemic dissemination. Mice depleted of peritoneal macrophages were able to recruit macrophages and neutrophils to the peritoneal cavity after infection, comparable to control mice. Furthermore, increased levels of peritoneal cytokines and chemokines were found in mice depleted of peritoneal macrophages. This study indicates that peritoneal macrophages are important in the early containment of E. faecium peritonitis and for the regulation of the inflammatory response.

Microbial tolerance in secondary peritonitis is dose dependent

Local microbial tolerance was investigated in a murine model of peritonitis. Peritoneal bacterial burden and inflammatory cytokine concentrations were determined at different times, within 48 h after infection. Peritoneal macrophages were harvested from naïve mice or from mice 48 h after infection and underwent ex vivo stimulation with different concentrations of Klebsiella. Cytokine secretion was determined in the supernatants. Peritoneal bacteria concentrations, remained relatively steady between 24 h (median: 5.04 log CFU) and 48 h (median: 5.19 log CFU) after infection. Peritoneal cytokine concentrations peaked early but were already diminished at 48 h after infection, despite persistent high bacteria levels. Macrophages, harvested from naïve mice responded vigorously to ex vivo stimulation with 10 5 CFU and 2 × 10 8 CFU Klebsiella. Cells harvested from animals 48 h after infection, were unresponsive to an ex vivo stimulation with 10 5 CFU Klebsiella, but fully responded to 10 8 CFU. Persistent intraabdominal bacterial infection induced dose dependent microbial tolerance in peritoneal macrophages.

Correlation between symptoms of pain and peritoneal fluid inflammatory cytokine concentrations in endometriosis

Correlation between symptoms of pain and peritoneal fluid inflammatory cytokine concentrations in endometriosis

Clinical effects of laparotomy with perioperative continuous peritoneal lavage and postoperative hemofiltration in patients with severe acute pancreatitis

BackgroundThe elevated serum and peritoneal cytokine concentrations responsible for the systemic response syndrome (SIRS) and multiorgan failure in patients with severe acute pancreatitis lead to high morbidity and mortality rates. Prompted by reports underlining the importance of reducing circulating inflammatory mediators in severe acute pancreatitis, we designed this study to evaluate the efficiency of laparotomy followed by continuous perioperative peritoneal lavage combined with postoperative continuous venovenous diahemofiltration (CVVDH) in managing critically ill patients refractory to intensive care therapy. As the major clinical outcome variables we measured morbidity, mortality and changes in the Acute Physiology and Chronic Health Evaluation (APACHE II) score and cytokine concentrations in serum and peritoneal lavage fluid over time.MethodsFrom a consecutive group of 23 patients hospitalized for acute pancreatitis, we studied 6 patients all with Apache II scores ≥19, who underwent emergency surgery for acute complications (5 for an abdominal compartment syndrome and 1 for septic shock) followed by continuous perioperative peritoneal lavage and postoperative CVVDH. CVVDH was started within 12 hours after surgery and maintained for at least 72 hours, until the multiorgan dysfunction syndrome improved. Samples were collected from serum, peritoneal lavage fluid and CVVDH dialysate for cytokine assay. Apache II scores were measured daily and their association with cytokine levels was assessed.ResultsAll six patients tolerated CVVDH well, and the procedure lasted a mean 6 days (range, 3-12). Five patients survived and one died of Acinetobacter infection after surgery (mortality rate 16.6%). The mean APACHE II score was ≥ 19 (range 19-22) before laparotomy and decreased significantly during peritoneal lavage and postoperative CVVDH (P = 0.013 by matched-pairs Students t-test). The decrease in cytokine concentrations in serum and lavage fluid was associated with the decrease in APACHE II scores and high interleukin 6 (IL-6) and tumor necrosis factor (TNF) concentrations in the hemofiltrate.ConclusionIn critically ill patients with abdominal compartment syndrome, septic shock or high APACHE II scores related to severe acute pancreatitis, combining emergency laparotomy with continuous perioperative peritoneal lavage followed by postoperative CVVHD effectively reduces the local and systemic cytokines responsible for multiorgan dysfunction syndrome thus improving patients' outcome.

Deficiency of Immunophilin FKBP52 Promotes Endometriosis

Endometriosis is a common gynecological disease that affects approximately 10% of women of childbearing age. It is characterized by endometrial growth outside the uterus and often results in inflamed lesions, pain, and reduced fertility. Although heightened estrogenic activity and/or reduced progesterone responsiveness are considered to be involved in the etiology of endometriosis, neither the extent of their participation nor the underlying mechanisms are clearly understood. Heterogeneous uterine cell types differentially respond to estrogen and progesterone (P(4)). P(4), primarily acting via its nuclear receptor (PR), activates gene transcription and impacts many reproductive processes. Deletion of Fkbp52, an immunophilin cochaperone for PR, results in uterine-specific P(4) resistance in mice, creating an opportunity to study the unique aspects of P(4) signaling in endometriosis. Here we explored the roles of FKBP52 in this disease using Fkbp52(-/-) mice. We found that the loss of FKBP52 encourages the growth of endometriotic lesions with increased inflammation, cell proliferation, and angiogenesis. We also found remarkable down-regulation of FKBP52 in cases of human endometriosis. Our results provide the first evidence corroborated by genetic studies in mice for a potential role of an immunophilin cochaperone in the etiology of human endometriosis. This investigation is highly relevant for clinical application, particularly because P(4) resistance is favorably indicated in endometriosis and other gynecological diseases.

Neutrophils Are Essential for Rapid Clearance ofEnterococcus faeciumin Mice

A progressive increase in infections with multiresistant Enterococcus faecium has been reported, especially in cancer patients and neutropenic patients. Despite its increasing importance as a nosocomial pathogen, knowledge of the pathogenesis of E. faecium infections is highly limited. In this study, we investigated the role of neutrophils during peritonitis with subsequent bacteremia caused by E. faecium. Therefore, we depleted neutrophils by intraperitoneal injections of monoclonal antibody RB6-8C5. Mice were followed for 5 days, and the enterococcal outgrowth and inflammatory response were compared between neutropenic mice and immunoglobulin G-injected control mice. Neutropenic mice demonstrated a severe delay in enterococcal clearance from all cultured organs (peritoneal fluid, blood, and lung and liver tissue). In particular, neutropenic mice remained bacteremic for up to 3 days, whereas all nonneutropenic mice had cleared the bacteria from circulation by 2 days. Furthermore, neutropenic mice displayed elevated peritoneal cytokine and chemokine levels 1 day after the infection and attracted fewer macrophages into the peritoneal cavity. In the circulation, a prolonged elevation of tumor necrosis factor alpha, interleukin-6, and the acute-phase proteins serum amyloid A and complement 3 were measured in neutropenic mice. In conclusion, attraction of neutrophils to the primary site of E. faecium infection is important for a rapid clearance of this bacterium, thereby attenuating a systemic inflammatory response.

12/15-Lipoxygenase Regulates the Inflammatory Response to Bacterial Products In Vivo

The peritoneal macrophage (Mphi) is the site of greatest 12/15-lipoxygenase (12/15-LOX) expression in the mouse; however, its immunoregulatory role in this tissue has not been explored. Herein, we show that 12/15-LOX is expressed by 95% of resident peritoneal CD11b(high) cells, with the remaining 5% being 12/15-LOX(-). 12/15-LOX(+) cells are phenotypically defined by high F4/80, SR-A, and Siglec1 expression, and enhanced IL-10 and G-CSF generation. In contrast, 12/15-LOX(-) cells are a dendritic cell population. Resident peritoneal Mphi numbers were significantly increased in 12/15-LOX(-/-) mice, suggesting alterations in migratory trafficking or cell differentiation in vivo. In vitro, Mphi from 12/15-LOX(-/-) mice exhibit multiple abnormalities in the regulation of cytokine/growth factor production both basally and after stimulation with Staphylococcus epidermidis cell-free supernatant. Resident adherent cells from 12/15-LOX(-/-) mice generate more IL-1, IL-3, GM-CSF, and IL-17, but less CCL5/RANTES than do cells from wild-type mice, while Staphylococcus epidermidis cell-free supernatant-elicited 12/15-LOX(-/-) adherent cells release less IL-12p40, IL-12p70, and RANTES, but more GM-CSF. This indicates a selective effect of 12/15-LOX on peritoneal cell cytokine production. In acute sterile peritonitis, 12/15-LOX(+) cells and LOX products were cleared, then reappeared during the resolution phase. The peritoneal lavage of 12/15-LOX(-/-) mice showed elevated TGF-beta1, along with increased immigration of monocytes/Mphi, but decreases in several cytokines including RANTES/CCL5, MCP-1/CCL2, G-CSF, IL-12-p40, IL-17, and TNF-alpha. No changes in neutrophil or lymphocyte numbers were seen. In summary, endogenous 12/15-LOX defines the resident MPhi population and regulates both the recruitment of monocytes/Mphi and cytokine response to bacterial products in vivo.

Strain and model dependent differences in inflammatory cell recruitment in mice.

The objective of this study was to determine genetic differences in inflammation in these distinct inbred mouse strains. Peritoneal leukocyte recruitment, matrix metalloproteinases and cytokines were quantified in A/J, 129/svJ, C57BL/6J, using thioglycollate or biomaterial implants as inflammatory stimuli. In response to thioglycollate, A/J had significant decreases compared to C57BL/6J in both neutrophil (86 %) and macrophage (62 %) recruitment, and 129/svJ had a significant (43 %) decrease compared to C57BL/6J in macrophage recruitment. The reduced leukocyte recruitment corresponded to reduced matrix metalloproteinase-9. In the bioimplant model, 129/svJ had a 2-fold increase in neutrophil and macrophage recruitment compared to C57BL/6J, and the increased leukocyte recruitment corresponded to elevated cytokines, monocyte inhibitory protein-2 and monocyte chemoattractant protein-1, in the lavage compared to the values for C57BL/6J. Not only was leukocyte recruitment strain dependent, but the three strains had marked differences in metalloproteinases and cytokine response. In addition, there were model specific differences in the metalloproteinase and cytokine response to the two inflammatory stimuli. Thus, inflammatory cell recruitment is genetically determined and stimulus specific and may determine the susceptibility to complex diseases.