Lymphatic thoracic duct ligation modulates the serum levels of IL-1beta and IL-10 after intestinal ischemia/reperfusion in rats with the involvement of tumor necrosis factor alpha and nitric oxide

Impact of Thoracic Duct Resection on Long-Term Survival After Esophagectomy: Individual Patient Data Meta-analysis

BACKGROUND

Radical esophagectomy, including thoracic duct resection (TDR), has been proposed to improve regional lymphadenectomy and possibly reduce the risk of locoregional recurrence. However, because of its impact on immunoregulation, some authors have expressed concerns about its possible detrimental effect on long-term survival. The purpose of this review was to assess the influence of TDR on long-term survival.

PATIENTS AND METHODS

PubMed, MEDLINE, Scopus, and Web of Science databases were searched through 15 March 2024. Overall survival (OS), cancer specific survival (CSS), and disease-free survival (DFS) were primary outcomes. Restricted mean survival time difference (RMSTD), risk ratio (RR), standardized mean difference (SMD), and 95% confidence intervals (CI) were used as pooled effect size measures. The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) methodology was employed to evaluate the certainty of evidence.

RESULTS

The analysis included six studies with 5756 patients undergoing transthoracic esophagectomy. TDR was reported in 49.1%. Patients' ages ranged from 27 to 79 years and 86% were males. At 4-year follow-up, the multivariate meta-analysis showed similar results for the comparison noTDR versus TDR in term of OS [- 0.8 months, 95% confidence interval (CI) - 3.1, 1.3], CSS (0.1 months, 95% CI - 0.9, 1.2), and DFS (1.5 months, 95% CI - 2.6, 5.5). TDR was associated with a significantly higher number of harvested mediastinal lymph nodes (SMD 0.57, 95% CI 0.01-1.13) and higher risk of postoperative chylothorax (RR = 1.32; 95% CI 1.04-2.23). Anastomotic leak and pulmonary complications were comparable.

CONCLUSIONS

TDR seems not to improve long-term OS, CSS, and DFS regardless of tumor stage. Routine TDR should not be routinely recommended during esophagectomy.

Does Thoracic Duct Ligation at the Time of Esophagectomy Impact Long-Term Survival? An Individual Patient Data Meta-Analysis

Background: Thoracic duct ligation (TDL) during esophagectomy has been proposed to reduce the risk of postoperative chylothorax. Because of its role in immunoregulation, some authors argued that it had an unfavorable TDL effect on survival. The aim of this study was to analyze the effect of TDL on overall survival (OS). Methods: PubMed, MEDLINE, Scopus, and Web of Science were searched through December 2023. The primary outcome was 5-year OS. The restricted mean survival time difference (RMSTD), hazard ratios (HRs), and 95% confidence intervals (CI) were used as pooled effect size measures. The GRADE methodology was used to summarize the certainty of the evidence. Results: Five studies (3291 patients) were included. TDL was reported in 54% patients. The patients' age ranged from 49 to 69, 76% were males, and BMI ranged from 18 to 26. At the 5-year follow-up, the combined effect from the multivariate meta-analysis is -3.5 months (95% CI -6.1, -0.8) indicating that patients undergoing TDL lived 3.5 months less compared to those without TDL. TDL was associated with a significantly higher hazard for mortality at 12 months (HR 1.54, 95% CI 1.38-1.73), 24 months (HR 1.21, 95% CI 1.12-1.35), and 28 months (HR 1.14, 95% CI 1.02-1.28). TDL and noTDL seem comparable in terms of the postoperative risk for chylothorax (RR = 0.66; p = 0.35). Conclusions: In this study, concurrent TDL was associated with reduced 5-year OS after esophagectomy. This may suggest the need of a rigorous follow-up within the first two years of follow-up.

Anti-inflammatory and antioxidant effects of the nanocomposite Fullerol decrease the severity of intestinal inflammation induced by gut ischemia and reperfusion

Intestinal ischemia is a vascular emergency that arises when blood flow to the intestine is compromised. Reperfusion is necessary to restore intestinal function but might lead to local and systemic inflammatory responses and bacterial translocation, with consequent multiple organ dysfunction syndrome (MODS). During reperfusion occurs production of reactive oxygen species. These species contribute to intestinal injury through direct toxicity or activation of inflammatory pathways. Fullerol is a nanacomposite which has been shown to act as reactive oxygen species and reactive nitrogen species (RNS) scavengers. Thus, our aim was to evaluate whether Fullerol confer anti-inflammatory activity during intestinal ischemia and reperfusion (IIR). Intestinal ischemia was induced by total occlusion of the superior mesenteric artery. Groups were treated with vehicle or Fullerol 10 min before reperfusion. Mice were euthanized after 6 h of reperfusion, and small intestines were collected for evaluation of plasma extravasation, leukocyte influx, cytokine production and histological damage. Bacterial translocation to the peritoneal cavity and reactive oxygen and nitrogen species production by lamina propria cells were also evaluated. Our results showed that treatment with Fullerol inhibited bacterial translocation to the peritoneal cavity, delayed and decreased the lethality rates and diminished neutrophil influx and intestinal injury induced by IIR. Reduced severity of reperfusion injury in Fullerol-treated mice was associated with blunted reactive oxygen and nitrogen species production in leukocytes isolated from gut lamina propria and decreased production of pro-inflammatory mediators. Thus, the present study shows that Fullerol is a potential therapy to treat inflammatory bowel disorders associated with bacterial translocation, such as IIR.

The potential protective effect of modafinil in intestinal ischemic reperfusion-induced in rats

OBJECTIVE

Intestinal ischemia reperfusion (IR) is a pathophysiologic process that leads to oxidative stress and acute inflammatory responses. Understanding the mechanisms explaining this inflammation is essential to developing therapeutic strategies. Therefore, the purpose of this study was to evaluate the protective outcome of modafinil (Mod) against intestinal damages caused by intestinal IR injury.

METHODS/MATERIALS

Fourty adult Male Wistar rats were randomly divided into four groups: sham control group; intestinal IR group; Mod pre-treated IR group and Mod post-treated IR group. Mod in a dose of 10 mg/kg was injected intraperitoneally once daily for 7 days pre or post IR treatment.

RESULTS

Mod significantly attenuated the IR induced elevations in intestinal malondialdehyde (MDA), nitric oxide (NO), tumor necrosis factor alpha (TNF-α), interleukin 1-β (IL-1β) and P-glycoprotein (P-gp) levels, caspase-3 activity. However, a significant increase in TAC was reported as compared with the IR group but its post-treated IR group was highly protective. Mod post-treatment down-regulated the IR induced cyclo-oxygenase-2 (COX-2) over-expression. Distorted mucosa with loss of surface epithelial cells, epithelial separation oedematous lamina propria and inflammatory cellular infiltration detected by histopathological examination of intestinal tissue, were markedly ameliorated by Mod post-treatment. On the other hand, Mod pre-treatment showed less protection against intestinal IR in rats.

CONCLUSION

Current study suggests that Mod post-treatment ameliorated intestinal damages, so it can be considered a potential therapeutic agent to protect against the major clinical challenge of intestinal injury resulting from IR.

Prophylactic thoracic duct ligation is associated with poor prognosis and regional lymph node relapse in esophageal squamous cell carcinoma

OBJECTIVES

The ligation of thoracic duct interrupts the normal lymphatic circulation. Whether the ligation of thoracic duct would affect tumor recurrence and patient survival is unclear.

METHODS

The correlations between prophylactic thoracic duct ligation (PLG) and prognosis were examined in patients with esophageal squamous cell carcinoma. Patients who received Ivor Lewis or McKeown esophagectomy with systemic lymph node dissection and R0 resection between 2003 and 2013 in Sun Yat-sen University Cancer Center were included in the study.

RESULTS

A total number of 473 and 462 were included in the PLG group and non-prophylactic thoracic duct ligation (NPLG) group, respectively. The PLG group had a lower 5-year survival rate (48.2% vs 61.6%, P < .001). After a 1:1 propensity score matching, 874 cases (437 pairs) were included and the survival analysis showed that PLG was associated with worse 5-year cumulative survival of 48.6% vs 61.6% in those patients without ligation (P < .001). The multivariate analysis revealed that PLG was an independent factor for poor prognosis after esophagectomy (hazard ratio, HR = 1.56; 95% confidence interval, 95% CI, 1.26-1.93, P < .001). Additionally, PLG was associated with regional lymph node relapse (P = .015).

CONCLUSIONS

PLG should not be performed routinely if no sign of thoracic duct rupture or tumor invasion were identified.

Thoracic Duct Resection During Esophagectomy Does Not Contribute to Improved Prognosis in Esophageal Squamous Cell Carcinoma: A Propensity Score Matched-Cohort Study

PURPOSE

Esophagectomy with extended lymphadenectomy remains the mainstay of treatment for localized esophageal squamous cell carcinoma (ESCC). Thoracic duct (TD) resection has been recommended as part of extended lymphadenectomy, although its merits are unclear. The aim of this two-institutional, matched-cohort study is to clarify whether TD resection improves prognosis in esophagectomy for ESCC.

PATIENTS AND METHODS

In this two-institutional, matched-cohort study of 399 patients with ESCC who underwent McKeown esophagectomy between 2010 and 2014, the primary outcomes were overall survival (OS), disease-free survival (DFS), and cause-specific survival (CSS). Secondary outcomes were perioperative results and recurrence patterns.

RESULTS

Based on a propensity score, 122 TD-resected or 122 TD-preserved patients in all stages were selected (median follow-up 4.5 years). The 5-year OS, DFS, and CSS rates in the TD-resected versus TD-preserved groups were 49% versus 60%, 53% versus 57%, and 58% versus 70%, respectively, without any significant differences. Operative time for the thoracic procedure was significantly longer and the number of retrieved mediastinal nodes was significantly higher in the TD-resected group (P = 0.009 and 0.005, respectively). The rates of chylothorax and left recurrent laryngeal nerve (RLN) palsy were significantly higher in the TD-resected group (P = 0.041 and 0.018, respectively). There were no significant differences in rates of local or distant metastases between the two groups.

CONCLUSIONS

TD resection does not contribute to improve OS, DFS, or CSS in ESCC but increases incidence of chylothorax and left RLN palsy. Prophylactic TD resection should be avoided in esophagectomy for ESCC.

Regional distribution of transpulmonary pressure

The pressure across the lung, so-called transpulmonary pressure (P_L), represents the main force acting toward to provide lung movement. During mechanical ventilation, P_L is provided by respiratory system pressurization, using specific ventilator setting settled by the operator, such as: tidal volume (V_T), positive end-expiratory pressure (PEEP), respiratory rate (RR), and inspiratory airway flow. Once P_L is developed throughout the lungs, its distribution is heterogeneous, being explained by the elastic properties of the lungs and pleural pressure gradient. There are different methods of P_L calculation, each one with importance and some limitations. Among the most known, it can be quoted: (I) direct measurement of P_L; (II) elastance derived method at end-inspiration of P_L; (III) transpulmonary driving pressure. Recent studies using pleural sensors in large animal models as also in human cadaver have added new and important information about P_L heterogeneous distribution across the lungs. Due to this heterogeneous distribution, lung damage could happen in specific areas of the lung. In addition, it is widely accepted that high P_L can cause lung damage, however the way it is delivered, whether it's compressible or tensile, may also further damage despite the values of P_L achieved. According to heterogeneous distribution of P_L across the lungs, the interstitium and lymphatic vessels may also interplay to disseminate lung inflammation toward peripheral organs through thoracic lymph tracts. Thus, it is conceivable that juxta-diaphragmatic area associated strong efforts leading to high values of P_L may be a source of dissemination of inflammatory cells, large molecules, and plasma contents able to perpetuate inflammation in distal organs.

Novel strategies for the treatment of acute pancreatitis based on the determinants of severity

Acute pancreatitis (AP) is a common disease for which a specific treatment remains elusive. The key determinants of the outcome from AP are persistent organ failure and infected pancreatic necrosis. The prevention and treatment of these determinants provides a framework for the development of specific treatment strategies. The gut-lymph concept provides a common mechanism for systemic inflammation and organ dysfunction. Acute and critical illness, including AP, is associated with intestinal ischemia and drastic changes in the composition of gut lymph, which bypasses the liver to drain into the systemic circulation immediately proximal to the major organ systems which fail. The external diversion of gut lymph and the targeting of treatments to counter the toxic elements in gut lymph offers novel approaches to the prevention and treatment of persistent organ failure. Infected pancreatic necrosis is increasingly treated with less invasive techniques, the mainstay of which is drainage, both endoscopic and percutaneous. Further improvements will occur with the strategies to accelerate liquefaction and through a fundamental re-design of drains, both of which will increase drainage efficacy. The determinants of severity and outcome in patients admitted with AP provide the basis for innovative treatment strategies. The priorities are to translate the gut-lymph concept to clinical practice and to improve the design and active use of drains for infected complications of AP.

Lymphatic deletion of calcitonin receptor-like receptor exacerbates intestinal inflammation

Lymphatics play a critical role in maintaining gastrointestinal homeostasis and in the absorption of dietary lipids, yet their roles in intestinal inflammation remain elusive. Given the increasing prevalence of inflammatory bowel disease, we investigated whether lymphatic vessels contribute to, or may be causative of, disease progression. We generated a mouse model with temporal and spatial deletion of the key lymphangiogenic receptor for the adrenomedullin peptide, calcitonin receptor-like receptor (Calcrl), and found that the loss of lymphatic Calcrl was sufficient to induce intestinal lymphangiectasia, characterized by dilated lacteals and protein-losing enteropathy. Upon indomethacin challenge, Calcrl^fl/fl/Prox1-CreER^T2 mice demonstrated persistent inflammation and failure to recover and thrive. The epithelium and crypts of Calcrl^fl/fl/Prox1-CreER^T2 mice exhibited exacerbated hallmarks of disease progression, and the lacteals demonstrated an inability to absorb lipids. Furthermore, we identified Calcrl/adrenomedullin signaling as an essential upstream regulator of the Notch pathway, previously shown to be critical for intestinal lacteal maintenance and junctional integrity. In conclusion, lymphatic insufficiency and lymphangiectasia caused by loss of lymphatic Calcrl exacerbates intestinal recovery following mucosal injury and underscores the importance of lymphatic function in promoting recovery from intestinal inflammation.

Calcium glycerophosphate preserves transepithelial integrity in the Caco-2 model of intestinal transport

AIM: To assess the direct effects of ischemia on intestinal epithelial integrity. Furthermore, clinical efforts at mitigating the effect of hypoperfusion on gut permeability have focused on restoring gut vascular function.

METHODS: We report that, in the Caco-2 cell model of transepithelial transport, calcium glycerophosphate (CGP), an inhibitor of intestinal alkaline phosphatase F3, has a significant effect to preserve transepithelial electrical resistance (TEER) and to attenuate increases in mannitol flux rates during hypoxia or cytokine stimulation.

RESULTS: The effect was observable even at concentrations as low as 1 μmol/L. As celiac disease is also marked by a loss of gut epithelial integrity, the effect of CGP to attenuate the effect of the α-gliadin peptide 31-55 was also examined. In this instance, CGP exerted little effect of preservation of TEER, but significantly attenuated peptide induced increase in mannitol flux.

CONCLUSION: It appears that CGP treatment might synergize with other therapies to preserve gut epithelial integrity.

Mesenteric lymph diversion abrogates 5-lipoxygenase activation in the kidney following trauma and hemorrhagic shock

BACKGROUND

Early acute kidney injury (AKI) following trauma is associated with multiorgan failure and mortality. Leukotrienes have been implicated both in AKI and in acute lung injury. Activated 5-lipoxygenase (5-LO) colocalizes with 5-LO-activating protein (FLAP) in the first step of leukotriene production following trauma and hemorrhagic shock (T/HS). Diversion of postshock mesenteric lymph, which is rich in the 5-LO substrate of arachidonate, attenuates lung injury and decreases 5-LO/FLAP associations in the lung after T/HS. We hypothesized that mesenteric lymph diversion (MLD) will also attenuate postshock 5-LO-mediated AKI.

METHODS

Rats underwent T/HS (laparotomy, hemorrhagic shock to a mean arterial pressure of 30 mm Hg for 45 minutes, and resuscitation), and MLD was accomplished via cannulation of the mesenteric duct. Extent of kidney injury was determined via histology score and verified by urinary neutrophil gelatinase-associated lipocalin assay. Kidney sections were immunostained for 5-LO and FLAP, and colocalization was determined by fluorescence resonance energy transfer signal intensity. The end leukotriene products of 5-LO were determined in urine.

RESULTS

AKI was evident in the T/HS group by derangement in kidney tubule architecture and confirmed by neutrophil gelatinase-associated lipocalin assay, whereas MLD during T/HS preserved renal tubule morphology at a sham level. MLD during T/HS decreased the associations between 5-LO and FLAP demonstrated by fluorescence resonance energy transfer microscopy and decreased leukotriene production in urine.

CONCLUSION

5-LO and FLAP colocalize in the interstitium of the renal medulla following T/HS. MLD attenuates this phenomenon, which coincides with pathologic changes seen in tubules during kidney injury and biochemical evidence of AKI. These data suggest that gut-derived leukotriene substrate predisposes the kidney and the lung to subsequent injury.

Lymphatic pump manipulation mobilizes inflammatory mediators into lymphatic circulation

Lymph stasis can result in edema and the accumulation of particulate matter, exudates, toxins and bacteria in tissue interstitial fluid, leading to inflammation, impaired immune cell trafficking, tissue hypoxia, tissue fibrosis and a variety of diseases. Previously, we demonstrated that osteopathic lymphatic pump techniques (LPTs) significantly increased thoracic and intestinal duct lymph flow. The purpose of this study was to determine if LPT would mobilize inflammatory mediators into the lymphatic circulation. Under anesthesia, thoracic or intestinal lymph of dogs was collected at resting (pre-LPT), during four minutes of LPT, and for 10 min following LPT (post-LPT), and the lymphatic concentrations of interleukin-2 (IL-2), IL-4, IL-6, IL-10, interferon- γ, tissue necrosis factor α,  monocyte chemotactic protein-1 (MCP-1), keratinocyte chemoattractant, superoxide dismutase (SOD) and nitrotyrosine (NT) were measured. LPT significantly increased MCP-1 concentrations in thoracic duct lymph. Further, LPT increased both thoracic and intestinal duct lymph flux of cytokines and chemokines as compared with their respective pre-LPT flux. In addition, LPT increased lymphatic flux of SOD and NT. Ten minutes following cessation of LPT, thoracic and intestinal lymph flux of cytokines, chemokines, NT and SOD were similar to pre-LPT, demonstrating that their flux was transient and a response to LPT. This re-distribution of inflammatory mediators during LPT may provide scientific rationale for the clinical use of LPT to enhance immunity and treat infection.

The effects of n-3 PUFA and intestinal lymph drainage on high-mobility group box 1 and Toll-like receptor 4 mRNA in rats with intestinal ischaemia-reperfusion injury

The aim of the present study was to investigate the impacts of n-3 PUFA and lymph drainage (D) on intestinal ischaemia-reperfusion (I/R) injury in rats. A total of forty-eight Sprague-Dawley male rats were randomly divided into three groups (n 16): normal diet (N), enteral nutrition (EN) and EN plus n-3 PUFA. Each group was further divided into lymph drainage (I/R+D) and non-drainage (I/R) sub-groups (n 8). After 5 d with different nutrition regimens, the rats were subjected to 60 min ischaemia by clamping the superior mesenteric artery, followed by 120 min reperfusion. At the same time, the rats in the I/R+D sub-groups were treated with intestinal lymph drainage for 180 min. Organs were harvested and we detected the cytokine, endotoxin, and expression of Toll-like receptor (TLR) 4 mRNA and its endogenous ligand high-mobility group box 1 (HMGB1). We found that the serum levels of HMGB1, inflammatory cytokine and endotoxin in the three I/R+D sub-groups were significantly lower than those in the N (I/R) and EN (I/R) sub-groups (P < 0·05). The activation of NF-κB and the expression of HMGB1 and TLR4 mRNA significantly increased in the jejunum, ileum, liver and lung after intestinal I/R injury, but notably lower in the I/R+D groups than those in I/R (P < 0·05). The injury degree and HMGB1 expression were decreased in the n-3 PUFA group than in the N and EN groups. We preliminarily concluded that nutrition with n-3 PUFA and/or intestinal lymph drainage may reduce HMGB1 and inflammatory cytokine in serum and lymph and inhibit the expression and signal transmission of TLR4 mRNA, thereby alleviating intestinal I/R injury in rats.

Cross-transfusion of postshock mesenteric lymph provokes acute lung injury

OBJECTIVE

Substantial investigation has implicated mesenteric lymph as the mechanistic link between gut ischemia/reperfusion (I/R) and distant organ injury. Specifically, lymph diversion prevents acute lung injury (ALI) in vitro, and bioactive lipids and proteins isolated from postshock mesenteric lymph (PSML) maintain bioactivity in vitro. However, Koch's postulates remain to be satisfied via direct cross-transfusion into a naïve animal. We therefore hypothesized that real time cross-transfusion of postshock mesenteric lymph provokes acute lung injury.

METHODS

One set of Sprague-Dawley rats (lymph donors) was anesthetized, with the mesenteric lymph ducts cannulated and exteriorized to drain freely into a siliconates plastic cup; concurrently, a second group of rats ( lymph recipients) was anesthetized, with a cannula inserted into the animal's right internal jugular vein. Blood was removed from the donor rats to induce hemorrhagic shock (MAP of 35 mmHg × 45 min). The recipient rats were positioned 10 cm below the plastic cup, which emptied into the jugular vein cannula. Thus, mesenteric lymph from the shocked donor rat was delivered to the recipient rat at the rate generated during shock and the subsequent 3 h of resuscitation.

RESULTS

Neutrophil (PMN) accumulation in the lungs was substantially elevated in the postshock lymph cross-transfusion group compared to both sham lymph cross-transfusion and instrumented control (MPO: 9.42 ± 1.55 versus 2.81 ± 0.82 U/mg lung tissue in postshock versus sham lymph cross-transfusion, n = 6 in each group, P = 0.02). Additionally, cross-transfusion of PSML induced oxidative stress in the lung (0.21 ± 0.03 versus 0.10 ± 0.01 micromoles MDA per mg lung tissue in lymph cross-transfusion versus instrumented control, n = 6 in each group, P = 0.046). Furthermore, transfusion of PSML provoked lung injury (BAL protein 0.77 ± 0.18 versus 0.15 ± 0.02 mg/mL protein in BALF, postshock versus sham lymph cross-transfusion, n = 6 in each group, P = 0.004).

CONCLUSION

Cross-transfusion of PSML into a naïve animal leads to PMN accumulation and provokes ALI. These data provide evidence that postshock agents released into mesenteric lymph are capable of provoking distant organ injury.

Effects of ischemia and reperfusion on P2X2 receptor expressing neurons of the rat ileum enteric nervous system

PURPOSE

We investigated the effects of ischemia/reperfusion in the intestine (I/R-i) on purine receptor P2X2-immunoreactive (IR) neurons of the rat ileum.

METHODS

The superior mesenteric artery was occluded for 45 min with an atraumatic vascular clamp and animals were sacrificed 4 h later. Neurons of the myenteric and submucosal plexuses were evaluated for immunoreactivity against the P2X2 receptor, nitric oxide synthase (NOS), choline acetyl transferase (ChAT), calbindin, and calretinin.

RESULTS

Following I/R-i, we observed a decrease in P2X2 receptor immunoreactivity in the cytoplasm and surface membranes of neurons of the myenteric and submucosal plexuses. These studies also revealed an absence of calbindin-positive neurons in the I/R-i group. In addition, the colocalization of the P2X2 receptor with NOS, ChAT, and calretinin immunoreactivity in the myenteric plexus was decreased following I/R-i. Likewise, the colocalization between P2X2 and calretinin in neurons of the submucosal plexus was also reduced. In the I/R-i group, there was a 55.8% decrease in the density of neurons immunoreactive (IR) for the P2X2 receptor, a 26.4% reduction in NOS-IR neuron, a 25% reduction in ChAT-IR neuron, and a 47% reduction in calretinin-IR neuron. The density of P2X2 receptor and calretinin-IR neurons also decreased in the submucosal plexus of the I/R-i group. In the myenteric plexus, P2X2-IR, NOS-IR, ChAT-IR and calretinin-IR neurons were reduced in size by 50%, 49.7%, 42%, and 33%, respectively, in the I/R-i group; in the submucosal plexus, P2X2-IR and calretinin-IR neurons were reduced in size by 56% and 72.6%, respectively.

CONCLUSIONS

These data demonstrate that ischemia/reperfusion of the intestine affects the expression of the P2X2 receptor in neurons of the myenteric and submucosal plexus, as well as density and size of neurons in this population. Our findings indicate that I/R-i induces changes in P2X2-IR enteric neurons that could result in alterations in intestinal motility.

Intestinal lymph-borne factors induce lung release of inflammatory mediators and expression of adhesion molecules after an intestinal ischemic insult

BACKGROUND

Intestinal ischemia and reperfusion (I/R) is a documented cause of acute lung injury (ALI) and systemic inflammation. We previously reported that obstruction of thoracic lymphatic flow during intestinal I/R blunts pulmonary neutrophil recruitment and microvascular injury and decreases the systemic levels of tumor necrosis factor. Here, we consider the existence of a gut-lung axis promoting the induction of systemic inflammation, whereby drained intestinal lymph stimulates lung expression of adhesion molecules and matrix components and generation of inflammatory mediators.

MATERIAL AND METHODS

Upon administration of anesthesia, male Wistar rats were subjected to occlusion of the superior mesenteric artery for 45 min, followed by 2 h of intestinal reperfusion (I/R); groups of rats were subjected to I/R with or without thoracic lymphatic duct ligation immediately before the procedure. The non-manipulated rats were used to investigate basal parameters.

RESULTS

Obstruction of thoracic lymphatic flow before intestinal I/R decreased the ability of cultured lung tissue explants to release IL-1β, IL-10, and VEGF. In contrast, lymphatic obstruction normalized the elevated lung expression of PECAM-1 caused by intestinal I/R. On the other hand, lung E-selectin expression was significantly reduced, whereas fibronectin expression and collagen synthesis were not affected. Lymph levels of LTB(4) and TXB(2) were found to be significantly increased.

CONCLUSIONS

These data suggest that lymph factors drained from the intestine during ischemic trauma stimulate the lung to generate inflammatory mediators and alter the expression of adhesion molecules. Disturbances in lung homeostasis mediated by lymph might contribute to the spread of inflammatory processes, thereby accounting for the systemic inflammation induced by intestinal I/R.

Lymph duct ligation during ischemia/reperfusion prevents pulmonary dysfunction in a rat model with ω-3 polyunsaturated fatty acid and glutamine

OBJECTIVE

The release of injurious factors into the mesenteric lymph from the ischemic intestine has been shown to contribute to lung injury and systemic inflammation after severe injury. We studied the effects of lung injury and systemic inflammatory reaction after intestinal ischemia/reperfusion and mesenteric lymph duct ligation with different nutritional statuses.

METHODS

Rats (n = 72) were fed with a normal diet or received one of three diets (enteral nutrition, glutamine, or ω-3 polyunsaturated fatty acid) that were isocaloric and isonitrogenous. After 7 d, rats were subjected to 60 min of intestinal ischemia, ischemia plus mesenteric lymph duct ligation, or sham procedures. After 3 d of ischemia, the lymph nodes, lung, intestinal, liver, and blood were harvested and analyzed.

RESULTS

In the different groups, lung injury, including levels of myeloperoxidase, nitric oxide, nitric oxide synthase, and the index of alveolar apoptosis, were partly prevented by mesenteric lymph duct ligation (P < 0.05). Likewise, the rats with ischemia/reperfusion, but not those with duct ligation plus ischemia/reperfusion, had a significant increase in intestinal permeability and decreased mucosal thickness. The serum cytokine and endotoxin concentrations were also lower in the lymph duct ligation groups, although there was no significant difference between lymph duct ligation and sham procedure. The lung and intestinal injuries were attenuated in the groups fed with glutamine and ω-3 polyunsaturated fatty acid.

CONCLUSION

These results indicate that lymph duct ligation prevents lung injury, a systemic inflammation reaction, and gut-barrier dysfunction. Enteral glutamine and ω-3 polyunsaturated fatty acid modified the gut inflammation, prevented lung injury, and attenuated the systemic inflammation reaction.

Gastrointestinal lymphatics in health and disease

Lymphatics perform essential transport and immune regulatory functions to maintain homeostasis in the gastrointestinal (GI) system. Although blood and lymphatic vessels function as parallel and integrated systems, our understanding of lymphatic structure, regulation and functioning lags far behind that of the blood vascular system. This chapter reviews lymphatic flow, differences in lymphangiogenic and hemangiogenic factors, lymphatic fate determinants and structural features, and examines how altered molecular signaling influences lymphatic function in organs of the GI system. Innate errors in lymphatic development frequently disturb GI functioning and physiology. Expansion of lymphatics, a prominent feature of GI inflammation, may also play an important role in tissue restitution following injury. Destruction or dysregulation of lymphatics, following injury, surgery or chronic inflammation also exacerbates GI disease activity. Understanding the physiological roles played by GI lymphatics is essential to elucidating their underlying contributions to forms of congenital and acquired forms of GI pathology, and will provide novel approaches for therapy.

Tumor necrosis factor is not associated with intestinal ischemia/reperfusion-induced lung inflammation

Intestinal ischemia-reperfusion (I/R) injury may cause acute systemic and lung inflammation. Here, we revisited the role of TNF-alpha in an intestinal I/R model in mice, showing that this cytokine is not required for the local and remote inflammatory response upon intestinal I/R injury using neutralizing TNF-alpha antibodies and TNF ligand-deficient mice. We demonstrate increased neutrophil recruitment in the lung as assessed by myeloperoxidase activity and augmented IL-6, granulocyte colony-stimulating factor, and KC levels, whereas TNF-alpha levels in serum were not increased and only minimally elevated in intestine and lung upon intestinal I/R injury. Importantly, TNF-alpha antibody neutralization neither diminished neutrophil recruitment nor any of the cytokines and chemokines evaluated. In addition, the inflammatory response was not abrogated in TNF and TNF receptors 1 and 2-deficient mice. However, in view of the damage on the intestinal barrier upon intestinal I/R with systemic bacterial translocation, we asked whether Toll-like receptor (TLR) activation is driving the inflammatory response. In fact, the inflammatory lung response is dramatically reduced in TLR2/4-deficient mice, confirming an important role of TLR receptor signaling causing the inflammatory lung response. In conclusion, endogenous TNF-alpha is not or minimally elevated and plays no role as a mediator for the inflammatory response upon ischemic tissue injury. By contrast, TLR2/4 signaling induces an orchestrated cytokine/chemokine response leading to local and remote pulmonary inflammation, and therefore disruption of TLR signaling may represent an alternative therapeutic target.

Claude H. Organ, Jr. memorial lecture: splanchnic hypoperfusion provokes acute lung injury via a 5-lipoxygenase-dependent mechanism

Postinjury multiple organ failure (MOF) is the net result of a dysfunctional immune response to injury characterized by a hyperactive innate system and a suppressed adaptive system. Acute lung injury (ALI) is the first clinical manifestation of organ failure, followed by renal and hepatic dysfunction. Circulatory shock is integral in the early pathogenesis of MOF, and the gut has been invoked as the motor of MOF. Mesenteric lymph is recognized as the mechanistic link between splanchnic ischemia/reperfusion and distant organ dysfunction, but the specific mediators remain to be defined. Current evidence suggests the lipid fraction of postshock mesenteric lymph is central in the etiology of ALI. Specifically, our recent work suggests that intestinal phospholipase A2 generated arachidonic acid and its subsequent 5-lipoxygenase products are essential in the pathogenesis of ALI. Proteins conveyed via postshock mesenteric lymph also may have an important role. Elucidating these mediators and the timing of their participation in pulmonary inflammation is critical in translating our current knowledge to new therapeutic strategies at the bedside.

Emerging roles of lymphatics in inflammatory bowel disease

The mobilization and recruitment of blood and lymphatic vasculatures are widely described in inflammatory bowel diseases (IBDs). Although angiogenesis contributes to intense gut inflammation, it remains unclear whether and when lymphangiogenesis amplifies or protects in IBD. The prolonged maintenance of lymphatic (over blood vessels) in inflammation indicates that lymphatic-blood vessel interactions may regulate IBD pathogenesis and restitution. Although lymphatic expansion helps to restore fluid balance and clear cytokines and immune cells, lymphatic failure results in accumulation of these factors and exacerbates IBD. Lymphatic obstruction and remodeling may impair lymphatic pumping, leading to repeated rounds of lymphangiogenesis. Early descriptions of Crohn's disease and ulcerative colitis describe colon lymphatic congestion, remodeling, expansion, and many other features that are recapitulated in experimental IBD and also by intestinal lymphatic obstruction, supporting lymphangitis as a cause and consequence of IBD. Growth factors, cytokines, gut flora, Toll receptors, and leukocytes all regulate inflammation and gut lymphatic remodeling in IBD. This review summarizes the importance of lymphatics and lymphangiogenesis in IBD etiology that may be useful in diagnosis and therapy of gut inflammation.

Lung inflammation is induced by renal ischemia and reperfusion injury as part of the systemic inflammatory syndrome

INTRODUCTION

Ischemia and reperfusion injury (IRI) are mainly caused by leukocyte activation, endothelial dysfunction and production of reactive oxygen species. Moreover, IRI can lead to a systemic response affecting distant organs, such as the lungs.

AIM

The objective was to study the pulmonary inflammatory systemic response after renal IRI.

METHODS

Male C57Bl/6 mice were subjected to 45 min of bilateral renal ischemia, followed by 4, 6, 12, 24 and 48 h of reperfusion. Blood was collected to measure serum creatinine and cytokine concentrations. Bronchoalveolar lavage fluid (BALF) was collected to determine the number of cells and PGE(2) concentration. Expressions of iNOS and COX-2 in lung were determined by Western blot. Gene analyses were quantified by real time PCR.

RESULTS

Serum creatinine increased in the IRI group compared to sham mainly at 24 h after IRI (2.57 +/- 0.16 vs. 0.43 +/- 0.07, p < 0.01). The total number of cells in BAL fluid was higher in the IRI group in comparison with sham, 12 h (100 x 10(4) +/- 15.63 vs. 18.1 x 10(4) +/- 10.5, p < 0.05) 24 h (124 x 10(4) +/- 8.94 vs. 23.2 x 10(4) +/- 3.5, p < 0.05) and 48 h (79 x 10(4) +/- 15.72 vs. 22.2 x 10(4) +/- 4.2, p < 0.05), mainly by mononuclear cells and neutrophils. Pulmonary COX-2 and iNOS were up-regulated in the IRI group. TNF-alpha, IL-1beta, MCP-1, KC and IL-6 mRNA expression were up-regulated in kidney and lungs 24 h after renal IRI. ICAM-1 mRNA was up-regulated in lungs 24 h after renal IRI. Serum TNF-alpha, IL-1beta and MCP-1 and BALF PGE(2) concentrations were increased 24 h after renal IRI.

CONCLUSION

Renal IRI induces an increase of cellular infiltration, up-regulation of COX-2, iNOS and ICAM-1, enhanced chemokine expression and a Th1 cytokine profile in lung demonstrating that the inflammatory response is indeed systemic, possibly leading to an amplification of renal injury.

Nitric oxide mediates lung vascular permeability and lymph-borne IL-6 after an intestinal ischemic insult

Acute lung injury following intestinal I/R depends on neutrophil-endothelial cell interactions and on cytokines drained from the gut through the lymph. Among the mediators generated during I/R, increased serum levels of IL-6 and NO are also found and might be involved in acute lung injury. Once intestinal ischemia itself may be a factor of tissue injury, in this study, we investigated the presence of IL-6 in lymph after intestinal ischemia and its effects on human umbilical vein endothelial cells (HUVECs) detachment. The involvement of NO on the increase of lung and intestinal microvascular permeability and the lymph effects on HUVEC detachment were also studied. Upon anesthesia, male Wistar rats were subjected to occlusion of the superior mesenteric artery during 45 min, followed by 2-h intestinal reperfusion. Rats were treated with the nonselective NO synthase (NOS) inhibitor L-NAME (N(omega)-nitro-L-arginine methyl ester) or with the selective inhibitor of iNOS aminoguanidine 1 h before superior mesenteric artery occlusion. Whereas treatment with L-NAME during ischemia increased both IL-6 levels in lymph and lung microvascular permeability, aminoguanidine restored the augmented intestinal plasma extravasation due to ischemia and did not induce IL-6 in lymph. On the other hand, IL-6 and lymph of intestinal I/R detached the HUVECs, whereas lymph of ischemic rats upon L-NAME treatment when incubated with anti-IL-6 prevented HUVEC detachment. It is shown that the intestinal ischemia itself is sufficient to increase intestinal microvascular permeability with involvement of iNOS activation. Intestinal ischemia and absence of constitutive NOS activity leading to additional intestinal stress both cause release of IL-6 and increase of lung microvascular permeability. Because anti-IL-6 prevented the endothelial cell injury caused by lymph at the ischemia period, the lymph-borne IL-6 might be involved with endothelial cell activation. At the reperfusion period, this cytokine does not seem to be modulated by NO.

Intestinal ischemia/reperfusion injury: defining the role of the gut microbiome

Intestinal ischemia/reperfusion (I/R) injury initiates a systemic inflammatory response syndrome with a high associated mortality rate. Early diagnosis is essential for reducing surgical mortality, yet current clinical biomarkers are insufficient. Metabonomics is a novel strategy for studying intestinal I/R, which may be used as part of a systems approach for quantitatively analyzing the intestinal microbiome during gut injury. By deconvolving the mammalian–microbial symbiotic relationship systems biology thus has the potential for personalized risk stratification in patients exposed to intestinal I/R. This review describes the mechanism of intestinal I/R and explores the essential role of the intestinal microbiota in the initiation of systemic inflammatory response syndrome. Furthermore, it analyzes current and future approaches for elucidating the mechanism of this condition.

Melatonin protects liver from intestine ischemia reperfusion injury in rats

AIM: To investigate the protective effect of melatonin on liver after intestinal ischemia-reperfusion injury in rats.

METHODS: One hundred and fifty male Wistar rats, weighing 190-210 g, aged 7 wk, were randomly divided into melatonin exposure group, alcohol solvent control group and normal saline control group. Rats in the melatonin exposure group received intraperitoneal (IP) melatonin (20 mg/kg) 30 min before intestinal ischemia-reperfusion (IR), rats in the alcohol solvent control group received the same concentration and volume of alcohol, and rats in the normal saline control group received the same volume of normal saline. Serum samples were collected from each group 0.5, 1, 6, 12, and 24 h after intestinal IR. Levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured with an auto-biochemical analyzer. Serum TNF-α was tested by enzyme-linked immunosorbent assay (ELISA). Malondialdehyde (MDA) in liver was detected by colorimetric assay. Pathological changes in liver and immunohistochemical straining of ICAM-1 were observed under an optical microscope.

RESULTS: The levels of ALT measured at various time points after intestinal IR in the melatonin exposure group were significantly lower than those in the other two control groups (P < 0.05). The serum AST levels 12 and 24 h after intestinal IR and the ICAM-1 levels (%) 6, 12 and 24 h after intestinal IR in the melatonin exposure group were also significantly lower than those in the other two control groups (P < 0.05).

CONCLUSION: Exotic melatonin can inhibit the activity of ALT, AST and TNF-α, decrease the accumulation of MDA, and depress the expression of ICAM-1 in liver after intestinal IR injury, thus improving the liver function.

Effects of prone and supine position on oxygenation and inflammatory mediator in a hydrochloric acid-induced lung dysfunction in rats

PURPOSE

To compare the effectiveness of mechanical ventilation of supine versus prone position in hydrochloric acid (HCl)-induced lung dysfunction.

METHODS

Twenty, adult, male, Wistar-EPM-1 rats were anesthetized and randomly grouped (n=5 animals per group) as follows: CS-MV (mechanical ventilation in supine position); CP-MV (mechanical ventilation in prone position); bilateral instillation of HCl and mechanical ventilation in supine position (HCl+S); and bilateral instillation of HCl and mechanical ventilation in prone position (HCl+P). All groups were ventilated for 180 minutes. The blood partial pressures of oxygen and carbon dioxide were measured in the time points 0 (zero; 10 minutes before lung injury for stabilization), and at the end of times acid injury, 60, 120 and 180 minutes of mechanical ventilation. At the end of experiment the animals were euthanized, and bronchoalveolar lavages (BALs) were taken to determine the contents of total proteins, inflammatory mediators, and lungs wet-to-dry ratios.

RESULTS

In the HCl+P group the partial pressure of oxygen increased when compared with HCl+S (128.0+/-2.9 mmHg and 111.0+/-6.7 mmHg, respectively) within 60 minutes. TNF-alpha levels in BAL do not differ significantly in the HCl+P group (516.0+/-5.9 pg/mL), and the HCl+S (513.0+/-10.6 pg/mL).

CONCLUSION

The use of prone position improved oxygenation, but did not reduce TNF-alpha in BAL upon lung dysfunction induced by HCl.

Mesenteric lymphatic ducts ligation decreases the degree of gut-induced lung injury in a portal vein occlusion and reperfusion canine model

BACKGROUND

Whether the mesenteric lymphatic system could serve as a route of transport by which gut-derived inflammatory mediators contribute to the induction of remote organ injuries is uncertain. We therefore made a gut-induced lung injury canine model by portal vein occlusion and reperfusion (PV O/R) and studied the role of mesenteric lymphatic ducts ligation (ML) to gut-induced lung injury with this model.

MATERIAL AND METHODS

Eighteen mongrel dogs were divided into control, PV O/R, and PV O/R + ML groups. Cytokines and endotoxin levels in the portal vein and lymph from thoracic duct in different groups were tested. The permeability, myeloperoxidase activity, and histopathological investigation of intestine and lung were evaluated.

RESULTS

Cytokines and endotoxin levels in the portal vein were significantly increased in experimental groups compared with control group (P < 0.05), and that in the lymph from thoracic duct were significantly increased in PV O/R group compared with control and PV O/R + ML group (P < 0.05). Lung permeability and MPO activity in PV O/R group were significantly higher than those in control and PV O/R + ML group (P < 0.05); intestinal permeability in experimental groups were significantly higher with respect to control group. The lung injury score in PV O/R group was significantly higher than those in control and PV O/R + ML group (P < 0.05) and the intestinal injury scores in experimental groups were significantly higher than control group (P < 0.05).

CONCLUSIONS

The gut-induced lung injury canine model made by PV O/R is successful, and mesenteric lymphatic ducts ligation decreases the degree of gut-induced lung injury in this model.

Lymphatics and lymph in acute lung injury

PURPOSE OF REVIEW

Lymph flow will be discussed as part of the drainage and fluid balance of lung tissue and abdomen as well as a qualitative analysis of inflammatory processes.

RECENT FINDINGS

Measurement of lung lymph is still a technical challenge. Mechanical ventilation and positive end-expiratory pressure impede lung lymph flow by increased intrathoracic pressure and increased central venous pressure. Positive end-expiratory pressure may thus enhance edema formation of the lung. Inflammatory spread from abdomen to the lung via the lymphatic system has been shown in a number of experimental studies. Ligation or diversion of the thoracic duct has been proposed to blunt the effects of noxious stimuli mediated by lymphatics to the lungs. Lymphatics have a major role on abdominal fluid balance while draining extravascular fluid accumulation and edema, especially during sepsis. Mechanical ventilation with high airway pressure increases abdominal edema (ascites) and spontaneous breathing protects from edema formation.

SUMMARY

Lymph flow measurements are still a difficult task to perform; however, new results show an important function in the fluid balance of the lung and abdomen. Inflammatory spread may occur from the lung to the periphery by the blood stream and from the abdomen to the lung by lymph flow.

Lymphatic-borne IL-1beta and the inducible isoform of nitric oxide synthase trigger the bronchial hyporesponsiveness after intestinal ischema/reperfusion in rats

Intestinal I/R (i-I/R) is an insult associated to further adult respiratory distress syndrome and multiple organ failure. This study was designed to evaluate the repercussions of i-I/R on bronchial reactivity to the cholinergic agent methacholine. Anesthetized rats were subjected to superior mesenteric artery occlusion (45 min) and killed after clamp release and defined intestinal reperfusion periods (30 min, 2, 4, or 24 h). Intestinal I/R caused a progressive bronchial hyporesponsiveness (BHR) that was maximal upon 2 h but reverted within 24 h of intestinal reperfusion. The BHR observed at 2-h i-I/R was prevented by NOS inhibitors (N-L-nitroarginine methyl ester and aminoguanidine) or the KATP channel blocker glibenclamide. Moreover, 2-h i-I/R increased the pulmonary iNOS mRNA expression, a fact prevented by lymphatic thoracic duct ligation. The methacholine reactivity of 2-h i-I/R bronchial segments incubated with NOS inhibitors or glibenclamide was similar to that of naive tissues. In vivo blockade of IL-1beta receptors or lymphatic duct ligation before 2-h i-I/R both abolished BHR. Incubation of naive bronchial segments with lymph collected from 2-h i-I/R rats determined BHR, an effect fully preventable by ex vivo blockade of IL-1beta receptors. Incubation of naive bronchial segments with IL-1beta, but not with IL-10 or TNF-alpha, significantly induced BHR that was prevented by N-L-nitroarginine methyl ester. Our data suggest that a gut ischemic insult generates IL-1beta that, upon reperfusion, travels through the lymph into the lungs. In this tissue, IL-1beta would stimulate the generation of NO that orchestrates the ensuing BHR for which the opening of KATP channels seems to play a pivotal role.