Interleukin-6 changes deformability of neutrophils and induces their sequestration in the lung

Association of Acute Systemic Inflammation with Patient-Centric Postoperative Pulmonary Complications After Elective Cardiac Surgery

BACKGROUND

Postoperative pulmonary complications (PPCs) occur frequently after cardiac surgery. Absolute postoperative values of biomarkers of inflammation (interleukin [IL]-6, IL-8, and tumor necrosis factor-alpha [TNF-α]) and alveolar epithelial injury (soluble receptor for advanced glycation end-products [sRAGE]) have been associated with hypoxia and prolonged ventilation. However, relationships between these biomarkers and PPCs, contextualized to preoperative inflammation and perioperative lung injury risk factors, are uncertain. We aimed to determine associations between perioperative increases in biomarkers of inflammation and alveolar epithelial injury with a patient-centric PPC definition in adult cardiac surgical patients, accounting for the influence of intraoperative risk factors for lung injury.

METHODS

Adults undergoing elective cardiac surgery were eligible for this observational cohort study. Blood concentrations of IL-6, IL-8, TNF-α, and sRAGE were collected after anesthesia induction (baseline) and on postoperative day 1 (POD 1). The primary outcome was the occurrence of moderate or severe PPCs, graded using a validated scale, in POD 0 to 7. We estimated the association between POD 1 IL-6, IL-8, TNF-α, and sRAGE concentrations and moderate/severe PPC presence using separate logistic regression models for each biomarker, adjusted for baseline biomarker values and risk factors for postoperative lung injury (age, baseline PaO2/FiO2, left ventricle ejection fraction [LVEF], procedural type, cardiopulmonary bypass duration, and transfusions). Covariables were chosen based on relevance to lung injury and unadjusted between-group differences among patients with versus without PPCs. The secondary outcome was postoperative ventilation duration, which was log-transformed and analyzed using linear regression, adjusted using the same variables as the primary outcome.

RESULTS

We enrolled 204 patients from 2016 to 2018. Biomarkers were analyzed in 2023 among 175 patients with complete data. In adjusted analyses, POD 1 IL-8 and IL-6 were significantly associated with moderate/severe PPCs. The odds ratio (OR) for developing a PPC for every 50 pg/mL increase in POD 1 IL-8 was 7.19 (95% confidence interval [CI], 2.13-28.53, P = .003) and 1.42 (95% CI, 1.13-1.93, P = .01) for every 50 pg/mL increase in POD 1 IL-6. In adjusted analyses, postoperative ventilation duration was significantly associated with POD 1 sRAGE; each 50 pg/mL increase in sRAGE was associated with a 25% (95% CI, 2%-52%, P = .03) multiplicative increase in hours of ventilation. TNF-α was not significantly associated with PPCs or ventilation duration.

CONCLUSIONS

Acute systemic inflammation is significantly associated with PPCs after elective cardiac surgery in adults when taking into consideration preoperative inflammatory burden and perioperative factors that may influence postoperative lung injury.

Neutrophil Homeostasis and Emergency Granulopoiesis: The Example of Systemic Juvenile Idiopathic Arthritis

Neutrophils are key pathogen exterminators of the innate immune system endowed with oxidative and non-oxidative defense mechanisms. More recently, a more complex role for neutrophils as decision shaping cells that instruct other leukocytes to fine-tune innate and adaptive immune responses has come into view. Under homeostatic conditions, neutrophils are short-lived cells that are continuously released from the bone marrow. Their development starts with undifferentiated hematopoietic stem cells that pass through different immature subtypes to eventually become fully equipped, mature neutrophils capable of launching fast and robust immune responses. During severe (systemic) inflammation, there is an increased need for neutrophils. The hematopoietic system rapidly adapts to this increased demand by switching from steady-state blood cell production to emergency granulopoiesis. During emergency granulopoiesis, the de novo production of neutrophils by the bone marrow and at extramedullary sites is augmented, while additional mature neutrophils are rapidly released from the marginated pools. Although neutrophils are indispensable for host protection against microorganisms, excessive activation causes tissue damage in neutrophil-rich diseases. Therefore, tight regulation of neutrophil homeostasis is imperative. In this review, we discuss the kinetics of neutrophil ontogenesis in homeostatic conditions and during emergency myelopoiesis and provide an overview of the different molecular players involved in this regulation. We substantiate this review with the example of an autoinflammatory disease, i.e. systemic juvenile idiopathic arthritis.

COVID-19 Usurps Host Regulatory Networks

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes coronavirus disease 2019 (COVID-19). SARS-CoV-2 binds the angiotensin-converting enzyme 2 (ACE2) on the cell surface and this complex is internalized. ACE2 serves as an endogenous inhibitor of inflammatory signals associated with four major regulator systems: the renin-angiotensin-aldosterone system (RAAS), the complement system, the coagulation cascade, and the kallikrein-kinin system (KKS). Understanding the pathophysiological effects of SARS-CoV-2 on these pathways is needed, particularly given the current lack of proven, effective treatments. The vasoconstrictive, prothrombotic and pro-inflammatory conditions induced by SARS-CoV-2 can be ascribed, at least in part, to the activation of these intersecting physiological networks. Moreover, patients with immune deficiencies, hypertension, diabetes, coronary heart disease, and kidney disease often have altered activation of these pathways, either due to underlying disease or to medications, and may be more susceptible to SARS-CoV-2 infection. Certain characteristic COVID-associated skin, sensory, and central nervous system manifestations may also be linked to viral activation of the RAAS, complement, coagulation, and KKS pathways. Pharmacological interventions that target molecules along these pathways may be useful in mitigating symptoms and preventing organ or tissue damage. While effective anti-viral therapies are critically needed, further study of these pathways may identify effective adjunctive treatments and patients most likely to benefit.

Neutropenia During Tocilizumab Treatment Is Not Associated with Infection Risk in Systemic or Polyarticular-course Juvenile Idiopathic Arthritis

OBJECTIVE

To determine whether neutropenia is associated with increased risk for infection in patients with systemic juvenile idiopathic arthritis (sJIA) and polyarticular-course juvenile idiopathic arthritis (pcJIA) treated with tocilizumab (TCZ).

METHODS

Data up to Week 104 from 2 phase III trials of intravenous TCZ in sJIA (n = 112; ClinicalTrials.gov, NCT00642460) and pcJIA (n = 188; ClinicalTrials.gov, NCT00988221) were pooled. Worst common toxicity criteria grade and lowest observed absolute neutrophil count (ANC) were identified for each patient. Associations between patient characteristics and lowest observed ANC were tested using univariate regression analysis. Infection and serious infection rates per 100 patient-years (PY) in periods associated with grades 1/2 and 3/4 neutrophil counts were compared with rates associated with normal neutrophil counts.

RESULTS

ANC decreased to grade ≥ 3 in 25.0% and 5.9% of sJIA and pcJIA patients, respectively, and decreases were transient. Young age (p = 0.047) and methotrexate use (p = 0.012) were positively associated with neutropenia in patients with sJIA but not in patients with pcJIA. The rate of serious infections in patients with sJIA (10.9/100 PY; 95% CI 6.8-16.5) tended to be higher than in patients with pcJIA (5.2/100 PY; 95% CI 3-8.5). No increase in rates of serious or nonserious infections was observed during periods of neutropenia in either trial.

CONCLUSION

Patients with JIA treated with TCZ experienced transient neutropenia that was not associated with an increased number of infections.

Myeloperoxidase-derived 2-chlorofatty acids contribute to human sepsis mortality via acute respiratory distress syndrome

Sepsis-associated acute respiratory distress syndrome (ARDS) is characterized by neutrophilic inflammation and poor survival. Since neutrophil myeloperoxidase (MPO) activity leads to increased plasma 2-chlorofatty acid (2-ClFA) levels, we hypothesized that plasma concentrations of 2-ClFAs would associate with ARDS and mortality in subjects with sepsis. In sequential consenting patients with sepsis, free 2-ClFA levels were significantly associated with ARDS, and with 30-day mortality, for each log increase in free 2-chlorostearic acid. Plasma MPO was not associated with either ARDS or 30-day mortality but was correlated with 2-ClFA levels. Addition of plasma 2-ClFA levels to the APACHE III score improved prediction for ARDS. Plasma 2-ClFA levels correlated with plasma levels of angiopoietin-2, E selectin, and soluble thrombomodulin. Endothelial cells treated with 2-ClFA responded with increased adhesion molecule surface expression, increased angiopoietin-2 release, and dose-dependent endothelial permeability. Our results suggest that 2-ClFAs derived from neutrophil MPO-catalyzed oxidation contribute to pulmonary endothelial injury and have prognostic utility in sepsis-associated ARDS.

Immunotoxicity of β-Diketone Antibiotic Mixtures to Zebrafish (Danio rerio) by Transcriptome Analysis

Fluoroquinolones and tetracyclines are known as β-diketone antibiotics (DKAs) because of bearing a diketone group in their molecular structure. DKAs are the most widely used antibiotics to prevent generation of disease in humans and animals and to suppress bacterial growth in aquaculture. In recent years, overuse of DKAs has caused serious environmental risk due to their pseudo-persistence in the environment, even though their half-lives are not long. So far, no reports were concerned with the joint immunotoxicity of DKAs. Herein, we reported on the immunotoxicity of DKAs on zebrafish after a 3-month DKAs exposure using transcriptomic techniques. According to transcriptome sequencing, 10 differentially expressed genes were screened out among the genes related to KEGG pathways with high enrichment. The identified 7 genes showed to be consistent between RNA-seq and qRT-PCR. Due to DKAs exposure, the content or activity for a series of immune-related biomarkers (Complement 3, lysozyme, IgM and AKP) showed the inconsistent changing trends as compared with the control group. Histopathological observations showed that the number of goblet cells increased sharply, the columnar epithelial cells swelled, the nucleus became slender in intestinal villi, and numerous brown metachromatic granules occurred in spleens of DKAs-exposed groups. Overall, both detection of biomarkers and histopathological observation corroborated that chronic DKAs exposure could result in abnormal expression of immune genes and enzymes, and variable levels of damage to immune-related organs. These complex effects of DKAs may lead to zebrafish dysfunction and occurrence of diseases related to the immune system.

The inflammatory sequelae of aortic balloon occlusion in hemorrhagic shock

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a hemorrhage control and resuscitative adjunct that has been demonstrated to improve central perfusion during hemorrhagic shock. The aim of this study was to characterize the systemic inflammatory response associated and cardiopulmonary sequelae with 30, 60, and 90 min of balloon occlusion and shock on the release of interleukin 6 (IL-6) and tumor necrosis factor alpha.

MATERIALS AND METHODS

Anesthetized female Yorkshire swine (Sus scrofa, weight 70-90 kg) underwent a 35% blood volume-controlled hemorrhage followed by thoracic aortic balloon occlusion of 30 (30-REBOA, n = 6), 60 (60-REBOA, n = 8), and 90 min (90-REBOA, n = 6). This was followed by resuscitation with whole blood and crystalloid over 6 h. Animals then underwent 48 h of critical care with sedation, fluid, and vasopressor support.

RESULTS

All animals were successfully induced into hemorrhagic shock without mortality. All groups responded to aortic occlusion with a rise in blood pressure above baseline values. IL-6, as measured (picogram per milliliter) at 8 h, was significantly elevated from baseline values in the 60-REBOA and 90-REBOA groups: 289 ± 258 versus 10 ± 5; P = 0.018 and 630 ± 348; P = 0.007, respectively. There was a trend toward greater vasopressor use (P = 0.183) and increased incidence of acute respiratory distress syndrome (P = 0.052) across the groups.

CONCLUSIONS

REBOA is a useful adjunct in supporting central perfusion during hemorrhagic shock; however, increasing occlusion time and shock results in a greater IL-6 release. Clinicians must anticipate inflammation-mediated organ failure in post-REBOA use patients.

Effects of IL-6 and IL-6 blockade on neutrophil function in vitro and in vivo

OBJECTIVES

Reports on the regulation of neutrophil function by IL-6 are often conflicting. Therapeutic inhibition of IL-6 in RA is associated with occasional neutropenia, but the mechanisms underlying this observation are poorly understood. This study investigated interactions between IL-6, the anti-IL-6 receptor agent tocilizumab (TCZ) and neutrophils in vitro and in vivo.

METHODS

Neutrophils were isolated from healthy controls and incubated in vitro with pharmacologically relevant concentrations of IL-6 or TCZ. Neutrophils were also isolated from RA patients, including a cohort following TCZ therapy. Apoptosis was measured by annexin V/propidium iodide (PI) flow cytometry; phagocytosis was measured by incubating apoptotic neutrophils with THP-1-derived macrophages; chemotaxis was measured using cell migration through hanging-cell inserts towards IL-8 and cell surface proteins, including adhesion molecules CD11b (αMβ2 integrin) and CD62L (L-selectin) were measured by flow cytometry.

RESULTS

IL-6 (10-100 ng/ml) did not affect the rate of neutrophil apoptosis, priming of the respiratory burst or adhesion molecule expression nor act as a neutrophil chemoattractant. However, IL-6 enhanced signal transducer and activator of transcription 3 (STAT3) activation and neutrophil migration towards IL-8. TCZ in vitro did not induce apoptosis or phagocytosis of neutrophils, nor did it have a significant effect upon apoptosis or cell surface molecule expression. Neutrophil functions in ex vivo neutrophils from RA patients receiving TCZ treatment were unaffected.

CONCLUSION

Therapeutic blockade of IL-6, while inducing a transient neutropenia, does not directly affect neutrophil functions associated with host defence. TCZ-associated neutropenia cannot be explained by direct induction of apoptosis by TCZ, induction of apoptosis following depletion of IL-6, nor increased phagocytosis of neutrophils.

Blood specimen biomarkers of inflammation, matrix degradation, angiogenesis, and cardiac involvement: a future useful tool in assessing clinical outcomes of COPD patients in clinical practice?

Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation that is not fully reversible; this airflow limitation is both progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gasses. COPD is undoubtedly an umbrella term, and it seems unlikely that all patients with COPD have the same underlying disease processes; thus, there is a need for differential treatment of different subgroups. A potential solution is to find modifiable biomarkers that can assist in drug development and distinguish subgroups of COPD. With the exception of lung function tests, there are currently no well-validated biomarkers or surrogate endpoints that can be used to establish the efficacy of a drug for COPD. This article discusses biomarkers of inflammation (fibrinogen, C-reactive protein, pulmonary and activation-regulated chemokine/CC-chemokine ligand-18, serum surfactant protein D, interleukin (IL)-6, IL-8 and tumor necrosis factor α, complement factor C5a), angiogenesis factors as a part of the pathogenetic aspect in this disease (vascular endothelial growth factor, angiogenin, and IL-8), and matrix degradation biomarkers. Troponin and natriuretic peptides are presented as biomarkers of cardiac involvement in the light of COPD comorbidities. Trials based on research on known clinical variables such as FEV1, BODE, and 6MWT in combination with biomarkers from lung and blood specimens will probably clarify part of the prognosis and natural history of the disease. This will also represent an additional step in COPD phenotyping and new treatment possibilities.

Serum proinflammatory cytokine levels and white blood cell differential count in patients with different degrees of severity of acute alcoholic pancreatitis

Several studies suggest that cytokines and neutrophils play an important role in the pathogenesis of acute pancreatitis (AP). The AIM OF THE STUDY was to assess the systemic release of proinflammatory cytokines and WBC (white blood cells) count with differential in patients with acute alcoholic pancreatitis (AAP) and to characterize the differences between patients with mild and severe forms of the disease.

MATERIAL AND METHODS

Thirty-five patients with the mild form of acute alcoholic pancreatitis (MAAP) were compared to 11 patients with severe acute alcoholic pancreatitis (SAAP). Serum levels of IL-6, IL-8, IL-12p40 and WBC differential count were measured every second day during the first week after admission.

RESULTS

During the course of the study, the average level of IL-6 was significantly (p<0.05) higher in patients with SAAP than in patients with the mild form of the disease (MAAP). Serum levels of IL-8 and IL-12p40 on admission were higher in patients with SAAP than in patients with MAAP but the difference was not statistically significant. Of all the types of WBCs, neutrophils were significantly (p<0.05) elevated the entire time in SAAP patients when compared to patients with MAAP on 5th and 7th day from admission to hospital.

CONCLUSIONS

Patients with SAAP had significantly higher proinflammatory cytokine IL-6 levels and neutrophil counts than patients with MAAP. The results suggest that proliferation and overstimulation of this subset of leukocytes might contribute to the development of the systemic inflammatory response in patients with SAAP.

Color of meconium and interleukin-6

OBJECTIVE

To test the hypothesis that the color of meconial fluid is associated with inflammatory biomarkers, by determining C-reactive protein (CRP) and Interleukin-6 (IL-6) in serum from the umbilical cord.

METHODS

In this prospective study, the authors selected 30 newborns with meconium-stained amniotic fluid (MSAF): 14 with green/brown 656 R color and 16 with brown/cinnamon 654 R color, and 20 newborns which showed clear amniotic fluid without MSAF (non-MSAF); all newborns were from mothers without risk factors for neonatal sepsis.

RESULTS

IL-6 concentration from umbilical cord blood, [median of 12.9 pg/mL (interquartile range {IQR} 8.7-31.0)] of MSAF-green/brown 656 R increased significantly (p < 0.05) when compared with IL-6 concentration, [median of 9.2 pg/mL (IQR 7.2-12.2)] of newborns with clear amniotic fluid and without meconium. CRP from MSAF-green/brown 656 R was median of 0.5 mg/mL (IQR 0.0-2.7), and median of 1.0 mg/mL (IQR 0.0-5.5) from clear amniotic fluid, without meconium.

CONCLUSIONS

Significant association was found between MSAF-green/brown 656 R and increase in IL-6, with normal CRP values.

Interleukin-6 mediates pulmonary vascular permeability in a two-hit model of ventilator-associated lung injury

To test the hypothesis that interleukin-6 (IL-6) contributes to the development of ventilator-associated lung injury (VALI), IL-6-deficient (IL6(-/-)) and wild-type control (WT) mice received intratracheal hydrochloric acid followed by randomization to mechanical ventilation (MV + IT HCl) or spontaneous ventilation (IT HCl). After 4 hours, injury was assessed by estimation of lung lavage protein concentration and total and differential cell counts, wet/dry lung weight ratio, pulmonary cell death, histologic inflammation score (LIS), and parenchymal myeloperoxidase (MPO) concentration. Vascular endothelial growth factor (VEGF) concentration was measured in lung lavage and homogenate, as IL-6 and stretch both regulate expression of this potent mediator of permeability. MV-induced increases in alveolar barrier dysfunction and lavage VEGF were attenuated in IL6(-/-) mice as compared with WT controls, whereas tissue VEGF concentration increased. The effects of IL-6 deletion on alveolar permeability and VEGF concentration were inflammation independent, as parenchymal MPO concentration, LIS, and lavage total and differential cell counts did not differ between WT and IL6(-/-) mice following MV + IT HCl. These data support a role for IL-6 in promoting VALI in this two-hit model. Strategies to interfere with IL-6 expression or signaling may represent important therapeutic targets to limit the injurious effects of MV in inflamed lungs.

Markers of early disease and prognosis in COPD

COPD is a complex disease with multiple pathological components, which we unfortunately tend to ignore when spirometry is used as the only method to evaluate the disorder. Additional measures are needed to allow a more complete and clinically relevant assessment of COPD. The earliest potential risk factors of disease in COPD are variations in the genetic background. Genetic variations are present from conception and can determine lifelong changes in enzyme activities and protein concentrations. In contrast, measurements in blood, sputum, exhaled breath, broncho-alveolar lavage, and lung biopsies may vary substantially over time. This review explores potential markers of early disease and prognosis in COPD by examining genetic markers in the α₁-antitrypsin, cystic fibrosis transmembrane conductance regulator (CFTR), and MBL-2 genes, and by examining the biochemical markers fibrinogen and C-reactive protein (CRP), which correlate with degree of pulmonary inflammation during stable conditions of COPD. Chronic lung inflammation appears to contribute to the pathogenesis of COPD, and markers of this process have promising predictive value in COPD. To implement markers for COPD in clinical practice, besides those already established for the α₁-antitrypsin gene, further research and validation studies are needed.

Particulate matter air pollution exposure promotes recruitment of monocytes into atherosclerotic plaques

Epidemiologic studies have shown an association between exposure to ambient particulate air pollution <10 microm in diameter (PM(10)) and increased cardiovascular morbidity and mortality. We previously showed that PM(10) exposure causes progression of atherosclerosis in coronary arteries. We postulate that the recruitment of monocytes from the circulation into atherosclerotic lesions is a key step in this PM(10)-induced acceleration of atherosclerosis. The study objective was to quantify the recruitment of circulating monocytes into vessel walls and the progression of atherosclerotic plaques induced by exposure to PM(10). Female Watanabe heritable hyperlipidemic rabbits, which naturally develop systemic atherosclerosis, were exposed to PM(10) (EHC-93) or vehicle by intratracheal instillation twice a week for 4 wk. Monocytes, labeled with 5-bromo-2'-deoxyuridine (BrdU) in donors, were transfused to recipient rabbits as whole blood, and the recruitment of BrdU-labeled cells into vessel walls and plaques in recipients was measured by quantitative histological methodology. Exposure to PM(10) caused progression of atherosclerotic lesions in thoracic and abdominal aorta. It also decreased circulating monocyte counts, decreased circulating monocytes expressing high levels of CD31 (platelet endothelial cell adhesion molecule-1) and CD49d (very late antigen-4 alpha-chain), and increased expression of CD54 (ICAM-1) and CD106 (VCAM-1) in plaques. Exposure to PM(10) increased the number of BrdU-labeled monocytes adherent to endothelium over plaques and increased the migration of BrdU-labeled monocytes into plaques and smooth muscle underneath plaques. We conclude that exposure to ambient air pollution particles promotes the recruitment of circulating monocytes into atherosclerotic plaques and speculate that this is a critically important step in the PM(10)-induced progression of atherosclerosis.

Chronic obstructive pulmonary disease: a chronic systemic inflammatory disease

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation in both the airways causing airway obstruction and the lung tissues causing emphysema. The disease is induced by inhalation of noxious gasses and particulate matter resulting in a chronic persistent inflammatory response in the lung, and the extent of the inflammatory reaction correlates with the severity of the disease. This chronic inflammatory response in the lung is also associated with a significant systemic inflammatory response with downstream adverse clinical health effects. The systemic response in COPD is associated with mortality, specifically cardiovascular mortality. This review describes the nature of the systemic inflammatory response in COPD and the clinical manifestations associated with the systemic response, with a focus on the potential mechanisms for these adverse health effects.

Peroxisome proliferator-activated receptors ligands and ischemia-reperfusion injury

Peroxisome proliferator-activated receptors (PPARs) belong to a subfamily of transcription nuclear factors. Three isoforms of PPARs have been identified: alpha, beta/delta and gamma, encoded by different genes and distributed in various tissues. They play important roles in metabolic processes like regulation of glucose and lipid redistribution. They also have anti-atherogenic, anti-inflammatory as well as antihypertensive functions. There is good evidence that ligands of PPARs reduce tissue injury associated with ischemia and reperfusion. The potential utility of PPAR ligands in ischemia and reperfusion will be discussed in this review.

C-reactive Protein As a Predictor of Prognosis in Chronic Obstructive Pulmonary Disease

RATIONALE

Patients with chronic obstructive pulmonary disease (COPD) have an ongoing systemic inflammation, which can be assessed by measuring serum C-reactive protein (CRP).

OBJECTIVE

To determine whether increased serum CRP in individuals with airway obstruction predicts future hospitalization and death from COPD.

METHODS

We performed a cohort study with a median of 8-yr follow-up of 1,302 individuals with airway obstruction selected from the ongoing Copenhagen City Heart Study.

MEASUREMENTS AND MAIN RESULTS

We measured serum CRP at baseline, and recorded COPD admissions and deaths as outcomes. During follow-up, 185 (14%) individuals were hospitalized due to COPD and 83 (6%) died of COPD. Incidences of COPD hospitalization and COPD death were increased in individuals with baseline CRP > 3 mg/L versus < or = 3 mg/L (log rank: p < 0.001). After adjusting for sex, age, FEV(1)% predicted, tobacco consumption, and ischemic heart disease, the hazard ratios for hospitalization and death due to COPD were increased at 1.4 (95% confidence interval, 1.0-2.0) and 2.2 (1.2-3.9) in individuals with baseline CRP > 3 mg/L versus < or = 3 mg/L. After close matching for FEV(1)% predicted and adjusting for potential confounders, baseline CRP was, on average, increased by 1.2 mg/L (analysis of variance: p = 0.002) and 4.1 mg/L (p = 0.001) in those who were subsequently hospitalized or died of COPD, respectively. The absolute 10-yr risks for COPD hospitalization and death in individuals with CRP above 3 mg/L were 54 and 57%, respectively, among those older than 70 yr with a tobacco consumption above 15 g/d and an FEV(1)% predicted of less than 50.

CONCLUSIONS

CRP is a strong and independent predictor of future COPD outcomes in individuals with airway obstruction.

High Vaccine Efficacy against Shigellosis of Recombinant NoninvasiveShigellaMutant That ExpressesYersiniaInvasin

Live attenuated Shigella vaccines elicit protective immune responses, but involve a potential risk of inducing a strong inflammatory reaction. The bacterial invasiveness that is crucial for Ag delivery causes inflammatory destruction of infected epithelial cells and proinflammatory cell death of infected macrophages. In this study, the noninvasive Shigella mutant DeltaipaB was equipped with Yersinia invasin protein, which has been shown to mediate bacterial invasion and targeting to M cells located in follicle-associated epithelium. Invasin-expressing DeltaipaB (DeltaipaB/inv) was internalized into epithelial cells and retained in the intraphagosomal space. DeltaipaB/inv did not induce necrotic cell death of infected macrophages nor cause symptomatic damage after intranasal vaccination of mice. DeltaipaB/inv was safer and more effective than the conventional live vaccine, DeltavirG. Infection by DeltaipaB/inv caused polymorphonuclear neutrophil infiltration in the lung, but did not induce production of large amounts of proinflammatory cytokines. We concluded that the low experimental morbidity and high vaccine efficacy of DeltaipaB/inv are primarily based on high protective immune responses, which may be enhanced by the polymorphonuclear neutrophil infiltration unaccompanied by tissue injury.

Flow cytometric method for enumeration and characterization of newly released polymorphonuclear leukocytes from the bone marrow using 5'-bromo-2'-deoxyuridine

Inflammation accelerates polymorphonuclear leukocyte (PMN) release from the bone marrow, and these PMNs are implicated in inappropriate tissue injury. We have previously developed a method using 5'-bromo-2'-deoxyuridine (BrdU) to study PMN kinetics using an immunocytochemical grading system of PMN on cytospin slides. The aim of this study was to develop a flow cytometric method to quantify the number of positively stained PMN and grade the intensity of staining for the transit time calculation of PMN through the marrow. Dividing myeloid progenitors in the marrow of rabbits were labeled with a pulse dosage of intravenous BrdU. BrdU-labeled PMN (PMN(BrdU)) were detected in the circulation using a FITC-conjugated anti-BrdU monoclonal antibody. The PMN(BrdU) were assigned to five groups according to their FITC intensity, and the transit times of PMN at different stages of development in the marrow were calculated. Results were compared using parallel immunocytochemical analysis of the same samples. In control animals, PMN(BrdU) in the circulation peaked at 72 h after BrdU labeling with 36.0% of PMN labeled. In normal rabbits, the transit times of PMN through the mitotic pool (49.5 +/- 4.2 h) and maturation pool (65.5 +/- 3.1 h) correlated well with immunocytochemical analysis and previously published values. Using this method, we demonstrated that exposure to air pollution particles accelerates the release of PMN(BrdU) from the marrow. We conclude that a flow cytometric approach for identifying BrdU-labeled leukocytes provides an objective and accurate method for studying leukocyte kinetics and behavior.

The female intestine is more resistant than the male intestine to gut injury and inflammation when subjected to conditions associated with shock states

Having documented that proestrus female rats are more resistant to shock-induced acute gut and hence lung injury than male rats, we tested the hypothesis that the female gut is more resistant to injury and produces less of an inflammatory response than the male gut when exposed to conditions associated with shock states (hypoxia and acidosis) utilizing the ex vivo Ussing chamber system. Ileal mucosal membranes harvested from normal male and female rats mounted in Ussing chamber systems were exposed to normoxia or 40 min of hypoxia at a normal pH (pH 7.3) or acidosis (pH 6.8). Cytokine and nitric oxide levels in the serosal compartment of the Ussing chamber were measured at the end of the 3-h experimental period to assess the immunoinflammatory response, whereas FITC-dextran (mol wt 4,300) was employed to assess barrier function. Histomorphological changes were used to quantitate gut mucosal injury. Hypoxia, acidosis, or hypoxia plus acidosis was associated with a significant increase in proinflammatory cytokine production [interleukin (IL)-6, tumor necrosis factor, and macrophage inflammatory protein (MIP)-2] by the male compared with the female intestinal segments. In contrast, the female gut manifested a higher anti-inflammatory response (nitric oxide and IL-10) and improved intestinal barrier function as well as less evidence of mucosal injury than the male intestinal segments. Administration of estradiol or the testosterone receptor antagonist, flutamide, to male rats abrogated the increase in gut injury and the increased IL-6 and MIP-2 response observed after hypoxia plus acidosis. These results suggest that gender differences in the ex vivo intestinal response to stresses, such as hypoxia and acidosis, exist and that the administration of estradiol or blockade of the testosterone receptor to male rats mitigates these gender differences.

Neutrophil responses to Mycobacterium tuberculosis infection in genetically susceptible and resistant mice

The role of neutrophils in tuberculosis (TB) resistance and pathology is poorly understood. Neutrophil reactions are meant to target the offending pathogen but may lead to destruction of the host lung tissue, making the defending cells an enemy. Here, we show that mice of the I/St strain which are genetically susceptible to TB show an unusually high and prolonged neutrophil accumulation in their lungs after intratracheal infection. Compared to neutrophils from more resistant A/Sn mice, I/St neutrophils display an increased mobility and tissue influx, prolonged lifespan, low expression of the CD95 (Fas) apoptotic receptor, relative resistance to apoptosis, and an increased phagocytic capacity for mycobacteria. Segregation genetic analysis in (I/St x A/Sn)F2 hybrids indicates that the alleles of I/St origin at the chromosome 3 and 17 quantitative trait loci which are involved in the control of TB severity also determine a high level of neutrophil influx. These features, along with the poor ability of neutrophils to restrict mycobacterial growth compared to that of lung macrophages, indicate that the prevalence of neutrophils in TB inflammation contributes to the development of pathology, rather than protection of the host, and that neutrophils may play the role of a "Trojan horse" for mycobacteria.

Immune mechanisms in the pathogenesis of bronchiolitis obliterans syndrome after lung transplantation

Lung transplantation is recognized as the only viable treatment option in a variety of end-stage pulmonary diseases. However, the long-term survival after lung transplantation is limited by the development of obliterative bronchiolitis, and its clinical correlate bronchiolitis obliterans syndrome (BOS), which is considered to represent chronic lung allograft rejection. Histopathologically, BOS is an inflammatory process that leads to fibrous scarring of the terminal and respiratory bronchioles and subsequent total occlusion of the airways. The specific etiology and pathogenesis of BOS are not well understood. The current premise is that BOS represents a common lesion in which different inflammatory insults such as ischemia-reperfusion, rejection, and infection can lead to a similar histological and clinical outcome. However, the low incidence of BOS in non-transplanted individuals and the observation that early development of BOS is predicted by the frequency and severity of acute rejection episodes indicate that alloimmune-dependent mechanisms play a crucial role in the pathogenesis of BOS. The evidence presented in this review indicates that BOS is the result of humoral and cellular immune responses developed against major histocompatibility complex molecules expressed by airway epithelial cells of the lung allograft. This process is aggravated by alloimmune-independent mechanisms such as ischemia-reperfusion and infection. Currently, treatment of BOS is frequently unsuccessful. Therefore, a better understanding of the immunopathogenesis of BOS is of paramount importance toward improving long-term patient and graft survival after lung transplantation.

Renal protection strategies in the perioperative period

The development of acute renal failure (ARF) in the perioperative period continues to be a vexing condition associated with high morbidity and mortality rates which have been unchanged for several decades. In this article I briefly review recent research categorizing pathogenesis of ARF and mechanisms of recovery. Once ARF is established, its maintenance phase is dependent on several mechanisms that interact with cellular integrity. The main focus of the article is on assessing clinical and experimental interventions to prevent ARF. Unfortunately, existing pharmacological and other interventions show a rather limited efficacy in preventing ARF.

Effect of relocating to areas of reduced atmospheric particulate matter levels on the human circulating leukocyte count

A high level of atmospheric particulate matter induces an increase in circulating polymorphonuclear leukocyte (PMN) counts and an increase in serum inflammatory cytokine levels. The particulate level in Antarctica is extremely low compared with that in industrial countries. We hypothesized that this low level would reduce circulating leukocyte counts and serum inflammatory cytokine levels in people visiting Antarctica from industrial countries. The number density of particulates with aerodynamic diameters of <10.0 μm was measured in Japan and in Antarctica during the 41st Japanese Antarctic Research Expedition. Circulating leukocyte counts, granulocyte colony-stimulating factor and interleukin-6 levels, and pulmonary function were determined at regular intervals in 39 expedition members. The particulate number density was <1% of that measured in Japan. Total leukocytes, segmented and band-formed PMN, monocyte counts, and serum interleukin-6 levels decreased in Antarctica compared with the initial values measured in Japan. Pulmonary function parameters did not change except for maximal voluntary ventilation. Particulate matter levels had more significant effects on segmented PMN, band-formed PMN, and monocyte counts than cigarette smoking and the type of work. Exposure to reduced atmospheric particulates is considered to be a major factor for decreasing circulating leukocyte counts and serum cytokine levels.

Ischemic acute renal failure: An inflammatory disease?

Inflammation plays a major role in the pathophysiology of acute renal failure resulting from ischemia. In this review, we discuss the contribution of endothelial and epithelial cells and leukocytes to this inflammatory response. The roles of cytokines/chemokines in the injury and recovery phase are reviewed. The ability of the mouse kidney to be protected by prior exposure to ischemia or urinary tract obstruction is discussed as a potential model to emulate as we search for pharmacologic agents that will serve to protect the kidney against injury. Understanding the inflammatory response prevalent in ischemic kidney injury will facilitate identification of molecular targets for therapeutic intervention.

Cholestatic interleukin-6-deficient mice succumb to endotoxin-induced liver injury and pulmonary inflammation

Circulating and hepatic interleukin (IL)-6 levels are strongly increased during clinical and experimental cholestasis. Cholestatic liver injury is associated with increased susceptibility to endotoxin-induced toxicity. To determine the role of IL-6 herein, extrahepatic cholestasis was induced by bile duct ligation (BDL) in IL-6-gene deficient (IL-6(-/-)) and normal (IL-6(+/+)) mice. BDL elicited increased levels of hepatic IL-6 mRNA and protein in normal mice. Hepatocellular injury 2 weeks after BDL was similar in IL-6(-/-) and IL-6(+/+) mice as demonstrated by clinical chemistry and histopathology. Administration of endotoxin to cholestatic mice 2 weeks after BDL was associated with enhanced cytokine release, severe liver damage, and death when compared with sham-operated mice. Effects of endotoxin were largely similar in sham-operated IL-6(-/-) and IL-6(+/+) mice, but cholestatic IL-6(-/-) mice were more susceptible to the toxic effects of endotoxin, as reflected by increased cytokine release, more profound liver injury and lung inflammation, and higher mortality. Although endogenous IL-6 is not important in the development of liver injury after experimentally induced obstructive jaundice, this cytokine plays an important role in decreasing hypersensitivity to endotoxin in cholestatic mice.

Pentoxifylline reduces acute lung injury in chronic endotoxemia

BACKGROUND

Pentoxifylline (PTX) attenuates end-organ injury in models of sepsis and hemorrhage. PTX is thought to act by inhibiting phosphodiesterase, thus increasing cAMP and decreasing tumor necrosis factor-alpha (TNF-alpha) synthesis. The effects of PTX on neutrophil and endothelial cell adhesion molecules and, ultimately, organ injury in a chronic endotoxemia model have not been studied. We hypothesized that continuous infusion of PTX reduces acute lung injury (ALI) caused by chronic lipopolysaccharide (LPS) exposure.

MATERIALS AND METHODS

Male Sprague-Dawley rats were given continuous infusion of LPS, PTX + LPS combined, or saline (sham) by implantable pumps. Neutrophil CD11b expression, lung histopathology, lung intercellular adhesion molecule-1 (ICAM-1) expression assessed by immune staining, serum TNF-alpha, serum interleukin-6 (IL-6), and bronchoalveolar lavage (BAL) IL-8 were evaluated at different time points. Lung injury was graded in a blinded fashion from 0 (normal) to 4 (severe) for interstitial inflammation, neutrophil infiltration, congestion, and edema. Total lung injury score (TLIS) was calculated by adding listed categories. White cell count in the peripheral blood and in the BAL was also performed.

RESULTS

Animals treated with PTX + LPS showed a significant reduction in lung injury score, a marked decrease in ICAM-1 expression, and a significant decrease in IL-8 levels in the BAL and serum IL-6 levels when compared with LPS-treated animals.

CONCLUSIONS

Continuous infusion of PTX reduces ALI caused by chronic endotoxemia. The effect seems to be a result of decreased expression of endothelial and epithelial ICAM-1 and modulation of proinflammatory cytokine synthesis.

Splenectomy attenuates intestinal ischemia-reperfusion-induced acute lung injury

BACKGROUND/PURPOSE

Intestinal ischemia-reperfusion (IIR) induced acute lung injury (ALI) has been documented. Kupffer cell blockage with gadolinium chloride (GdCl(3)) has been shown to attenuate IIR-induced ALI. However, the effects of splenic monocytes/macrophages on IIR-induced ALI has not been studied previously. In the current study, the authors aimed to investigate the role of splenectomy in IIR-induced ALI.

METHODS

Forty-eight rats were divided randomly into 6 groups as follows: SHAM, SHAM + KCB, SHAM + SPLN, IIR, IIR + KCB, IIR + SPLN. Two hours of ischemia and 1 hour of reperfusion has been applied by clipping the SMA. GdCl3 was given 24 hours before experiment. Splenectomy was done just before SMA clipping. Lung levels of tumor necrosis-factor (TNF), interleukin (IL)-6, myeloperoxidase (MPO), and malondialdehyde (MDA) were assayed biochemically. Lung leukosequestration was determined by counting PMNLs histologically. Kruskal-Wallis and Mann-Whitney U tests were done; P values less than.003 were considered significant.

RESULTS

Polimorphonuclear leukocyte (PMNL) counts and biochemical parameters in the IIR group were significantly higher than the other groups (P <.003). When compared with IIR group, PMNL counts and biochemical parameters were significantly decreased in the IIR+KCB and IIR+SPLN groups, respectively (P <.003). However, they were still significantly higher than their sham-operated controls (P <.003).

CONCLUSIONS

This study documents that splenectomy attenuates ALI as well as Kupffer cell blockage. Spleen, an important component of mononuclear phagocytic system as liver Kupffer cells, might play an important role in the IIR-induced ALI.

Do peritoneal macrophages play an essential role in the progression of acute pancreatitis in rats?

INTRODUCTION

Macrophages are considered to play an essential role in the events leading to systemic inflammatory response. Some are known to reside in the peritoneal cavity but there are no reports defining the participation of peritoneal macrophages (PMs) in the progression of acute pancreatitis.

AIM

To clarify the role of PMs in the progression of acute pancreatitis.

METHODOLOGY

Acute pancreatitis was induced in rats from which macrophages other than PMs were greatly depleted, and in rats greatly depleted of macrophages including PMs. Macrophages were depleted by the injection of liposome encapsulated dichloromethylene bisphosphonate. After the induction of acute pancreatitis, local pancreatic inflammation, intraperitoneal inflammation and lung injury were compared between the 2 groups.

RESULTS

Local pancreatic inflammation did not differ between the 2 groups. However, intraperitoneal inflammation was clearly improved by the depletion of PMs. Serum cytokine level and lung injury were also improved by the depletion of PMs.

CONCLUSION

Peritoneal macrophages extend inflammation from the pancreas to the peritoneal cavity and subsequently induce lung injury in acute pancreatitis. Peritoneal macrophages play an essential role in the systemic inflammatory response and the progression of acute pancreatitis in the rat.

Differential effects of mechanical ventilatory strategy on lung injury and systemic organ inflammation in mice

Patients with acute respiratory distress syndrome are at increased risk for developing multiorgan system dysfunction. The goal of this study was to establish an in vivo murine model to assess the differential effects of ventilation-protective strategies on the development of acute lung injury and systemic organ inflammation. C57B/6 mice were randomized to mechanical ventilation (MV) with conventional, high (17 ml/kg) or protective, low (6 ml/kg) tidal volume (VT) after intratracheal hydrochloric acid or no intervention. Mean arterial pressure was continuously monitored during MV and did not differ between groups. After 4 h, lung injury was assessed by measurement of wet/dry lung weight, lung lavage protein concentration and cell count, and histology. Concentration of IL-6, TNF-alpha, VEGF, and VEGF receptor-2 (VEGFR2) was measured in lung, liver, kidney, and heart. Results were compared with control, spontaneously breathing mice. Lung injury and altered pulmonary cytokine expression were not detected after MV of healthy mice with low or high VT. Although MV did not significantly alter IL-6 or TNF-alpha in systemic organs, VEGF concentration significantly increased in liver and kidney. After acid aspiration, mice ventilated with high VT manifested lung injury and increased IL-6 and VEGFR2 in lung, liver, and kidney, whereas VEGF increased only in liver and kidney. MV with low VT after acid aspiration attenuated lung injury, both IL-6 and VEGFR2 expression in lung and systemic organs, and hepatic, but not renal, increased VEGF. Our data suggest that MV strategy has differential effects on systemic inflammatory changes and thus may selectively predispose to systemic organ dysfunction.

Effects of acute hypoxia and lipopolysaccharide on nitric oxide synthase-2 expression in acute lung injury

The potential role of nitric oxide synthase-2 (NOS2) in acute lung injury (ALI) has gained increasing attention. This study evaluates the effects of hypoxia, an important feature of ALI, on NOS2 expression in a rat model of ALI caused by exposure to hypoxia and LPS. Exposure to hypoxia alone had no effect on the expression of NOS2 in rat lungs. LPS treatment resulted in a significant increase in NOS2 in the lungs, which was further enhanced by concomitant exposure to hypoxia. Immunohistochemical analysis and in situ hybridization showed no changes in the expression of NOS2 in lung resident cells under any conditions. The increase in NOS2 levels is mainly due to the influx of NOS2-expressing inflammatory cells. By morphologic analysis, these inflammatory cells were identified as neutrophils, lymphocytes, and monocytes. In vitro experiments of lung epithelial and endothelial cell lines showed no detectable expression of NOS2 with any of the treatments. In a macrophage cell line, LPS-induced NOS2 expression was not affected by the concomitant exposure to hypoxia. In conclusion, LPS increases NOS2 expression in rat lungs through the recruitment of NOS2-producing leukocytes. Simultaneous exposure to LPS and hypoxia results in a greater influx of inflammatory cells that further enhances NOS2 expression.

Reciprocal activation of leukocyte-endothelial adhesion molecules in acute coronary syndromes

BACKGROUND

The acute coronary syndromes are associated with an intense inflammatory response and sustained leukocyte activation. This inflammatory state has been correlated with an adverse prognosis, but the source of this inflammation remains controversial, with evidence that it may arise either from the coronary vasculature or from the systemic endothelium.

METHODS

Levels of soluble cell adhesion molecules, and of their respective monocyte cell surface ligands, were measured in the peripheral serum of 21 patients presenting with acute coronary syndromes. Soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1 were measured by enzyme linked immunosorbent assay and expression of the monocyte integrins CD11b (Mac-1) and CD49d (VLA-4) was measured by direct immunofluorescence using flow cytometry.

RESULTS

High levels of the monocyte receptor CD11b (531 vs. 345 MFI, P<0.01), and its soluble intercellular adhesion molecule-1 (329 vs. 232 ng/ml, P<0.01), were noted in patients with acute coronary syndromes compared to healthy controls.

CONCLUSIONS

Reciprocal activation of monocyte receptor ligands and endothelial adhesion molecules was found in the peripheral blood of patients with acute coronary syndromes. This may indicate a coordinated state of pro-inflammatory upregulation with widespread activation of both leukocytes and endothelium and suggests a systemic rather than local source for inflammation in acute coronary disease.

Respiratory damage in children exposed to urban pollution

Southwest Metropolitan Mexico City (SWMMC) children are chronically exposed to complex mixtures of air pollutants. In a cross-sectional arm of our study, we investigated the association between exposure to SWMMC atmosphere and nasal abnormalities, hyperinflation, and interstitial markings assessed by chest X-rays, lung function changes, several serum cytokines, and endothelin-1 in 174 children aged 5-17 years vs. 27 control children residents in low-polluted areas. Control children had no nasal lesions, and only one child showed an abnormal chest X-ray. SWMMC children exhibited nasal abnormalities (22%), hyperinflation (67%), interstitial markings (49%), and a mild restrictive pattern by spirometry (10%). Interstitial markings were associated with a decrease in predicted values of FEF(25-75), FEF(75), and the FEV(1)/FVC ratio. Boys had a higher probability of developing interstitial markings with age (P = 0.004). Blood smear findings included toxic granulations in neutrophils and schistocytes. SWMMC children had more serum IL10 and IL6 and less IL8 than controls. In a longitudinal arm of our study, we found a significant seasonal drop in FVC and FEV(1) associated with a 6-month period of high ozone and PM(10) levels. Our data strongly suggest that a lifelong exposure to urban air pollution causes respiratory damage in children. Moreover, a cytokine network becomes imbalanced, with a shift towards upregulation of anti-inflammatory cytokines. Consequently, these children are potentially at risk for developing chronic lung disease and other systemic effects later in life.

Role of cytokines in photodynamic therapy-induced local and systemic inflammation

Photodynamic therapy (PDT) of tumour results in the rapid induction of an inflammatory response that is considered important for the activation of antitumour immunity, but may be detrimental if excessive. The response is characterised by the infiltration of leucocytes, predominantly neutrophils, into the treated tumour. Several preclinical studies have suggested that suppression of long-term tumour growth following PDT using Photofrin((R)) is dependent upon the presence of neutrophils. The inflammatory pathways leading to the PDT-induced neutrophil migration into the treated tumour are unknown. In the following study, we examined, in mice, the ability of PDT using the second-generation photosensitiser 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH) to induce proinflammatory cytokines and chemokines, as well as adhesion molecules, known to be involved in neutrophil migration. We also examined the role that these mediators play in PDT-induced neutrophil migration. Our studies show that HPPH-PDT induced neutrophil migration into the treated tumour, which was associated with a transient, local increase in the expression of the chemokines macrophage inflammatory protein (MIP)-2 and KC. A similar increase was detected in functional expression of adhesion molecules, that is, E-selectin and intracellular adhesion molecule (ICAM)-1, and both local and systemic expression of interleukin (IL)-6 was detected. The kinetics of neutrophil immigration mirrored those observed for the enhanced production of chemokines, IL-6 and adhesion molecules. Subsequent studies showed that PDT-induced neutrophil recruitment is dependent upon the presence of MIP-2 and E-selectin, but not on IL-6 or KC. These results demonstrate a PDT-induced inflammatory response similar to, but less severe than obtained with Photofrin((R)) PDT. They also lay the mechanistic groundwork for further ongoing studies that attempt to optimise PDT through the modulation of the critical inflammatory mediators.

Endogenous IL-17 as a mediator of neutrophil recruitment caused by endotoxin exposure in mouse airways

We have previously demonstrated that administration of the recently described cytokine IL-17 in rat airways in vivo recruits and activates neutrophils locally. In the current study, we examined whether endogenous IL-17 is involved in mediating neutrophil recruitment caused by endotoxin exposure in mouse airways. Our in vivo data show that local endotoxin exposure causes the release of free, soluble IL-17 protein 6 h later. Systemic pretreatment with a neutralizing anti-IL-17 Ab almost completely inhibits neutrophil recruitment 24 h, but not 6 h, after endotoxin exposure in the airways. Pretreatment with neutralizing anti-IL-6 and anti-macrophage inflammatory protein (MIP)-2 Abs inhibits neutrophil recruitment caused by local endotoxin exposure and IL-17, respectively. Our in vitro data show that endotoxin exposure stimulates the release of soluble IL-17 protein in T lymphocytes harvested from lung and spleen, respectively, and that this cytokine release requires coculture with airway macrophages. Intracellular IL-17 protein is detected in T lymphocytes from spleen but not in airway macrophages after coculture and stimulation of these two cell types. Finally, anti-IL-17 does not alter endotoxin-induced release of IL-6 and MIP-2 from T lymphocytes and airway macrophages in coculture. In conclusion, our results indicate that endotoxin exposure causes the release of IL-17 from T lymphocytes and that this cytokine release requires the presence of macrophages. Once released, endogenous IL-17 acts in part by inducing local release of neutrophil-mobilizing cytokines such as IL-6 and MIP-2, from nonlymphocyte, nonmacrophage cells, and this contributes to recruitment of neutrophils in the airways. These IL-17-related mechanisms constitute potential targets for pharmacotherapy against exaggerated neutrophil recruitment in airway disease.

Interleukin-6 and interferon-gamma gene polymorphisms in the development of bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

A number of genetic polymorphisms have been shown to regulate the production and secretion of tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, interferon (IFN)-gamma, interleukin (IL)-6, and IL-10. Several of these genetic polymorphisms have been shown to be associated with either acute or chronic rejection of kidney, liver, and heart allografts and with development of allograft fibrosis after lung transplantation. The aim of this study was to assess the effect of these genetic polymorphisms on the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation.

METHODS

Genetic polymorphisms were detected by means of polymerase chain reaction in 93 lung allograft recipients for functional polymorphisms in the TNF-alpha (-308), TGF-beta1 (+869 and +915), IL-6 (-174), IFN-gamma (+874), and IL-10 (-1082, -819, and -592) genes. Then, a correlation between BOS development and the presence of these cytokine genotypes was determined using Kaplan-Meier actuarial analysis.

RESULTS

A significant correlation was detected between the presence of high-expression polymorphisms of the IL-6 and IFN-gamma genes and BOS development after lung transplantation (P =0.045 and 0.039, respectively). Also, patients with high-expression polymorphisms in both genes developed BOS significantly earlier than patients with low-expression polymorphisms in one or both genes, suggesting a synergistic effect of the alleles during BOS pathogenesis (P =0.016). No correlation was detected between polymorphisms of the TNF-alpha, TGF-beta1, and IL-10 genes and development of BOS after lung transplantation.

CONCLUSIONS

The presence of high-expression polymorphisms at position -174 of the IL-6 gene and position +874 of the IFN-gamma gene significantly increases the risk for BOS development after lung transplantation.