The mechanism of mononuclear cell infiltration in oral lichen planus: the role of cytokines released from keratinocytes

To clarify the pathogenesis of oral lichen planus (OLP), we investigated the roles of keratinocytes (KC) in mononuclear cell infiltration. When peripheral blood mononuclear cells (PBMC) obtained from healthy donors were cultured in the presence of culture supernatants of KC separated from the noninflamed gingivae (Nor-KC) and cheek mucosae of patients with OLP (OLP-KC), the number of migrated PBMC across monolayered human umbilical vein endothelial cells (HUVEC) were increased to about 1.3-fold and 1.5-fold of the control level, respectively, with increases of the expression of CD11a, CD11b, CD18, and CD49d on PBMC and intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and endothelial-leukocyte adhesion molecule-1 on HUVEC. The number of migrated PBMC was reduced to about 60% of the control level by pretreatment of PBMC with anti-CD11a or anti-CD18 MAb and reduced to about 70% by pretreatment of HUVEC with anti-CD54 MAb. The pretreatment of PBMC with genistein, H-7, wortmannin, or exoenzyme C3 decreased the migrated PBMC by about 70 to 90%. In agreement with these results, the culture supernatants of OLP-KC up-regulated tyrosine phosphorylation of 62-kDa, 70-kDa, and 102-kDa proteins, phosphatidylinositol-3 kinase, and protein kinase C activities and activated Rho protein level more so than did those of Nor-KC. Additionally, actin reorganization with the formation of membrane ruffles and lamellipodia was distinctly induced by the culture supernatants of OLP-KC. These results indicate that cytokines generated by KC transduce their signals in PBMC, up-regulating the expression of cell surface adhesion molecules and migration activity with reorganization of actin filaments.

Distinct effects of systemic infusion of G-CSF vs. IL-6 on lung and liver inflammation and injury in hemorrhagic shock

Production of pro-inflammatory cytokines, such as granulocyte colony-stimulating factor (G-CSF) and interleukin-6 (IL-6) occurs at multiple tissue sites in hemorrhagic shock (HS), resulting in elevated circulating plasma levels. The current study was designed to test the hypothesis that circulating G-CSF and IL-6 contribute to polymorphonuclear neutrophilic granulocyte (PMN)-mediated inflammation and organ injury in HS. Sprague-Dawley rats were subjected to decompensated HS (mean arterial blood pressure = 40 mm Hg for 2.5 h), followed by resuscitation with lactated Ringer's solution with or without G-CSF (3 microg/kg) or IL-6 (3 microg/kg). Animals were killed 4 h after resuscitation, and their lungs and livers were assessed quantitatively for PMN infiltration, organ injury, and activation of NF-kappaB and signal transducer and activator or transcription (STAT) 3. Infusion of G-CSF during resuscitation increased PMN infiltration into the lungs by 2.4-fold (P < 0.01) compared with animals resuscitated with lactated Ringer's solution alone. Increased PMN infiltration was accompanied by interstitial edema and pneumocyte swelling, resulting in a 42% increase in lung alveolar wall cross-sectional surface area (P < 0.01) and a 3.7-fold increase in Stat3 activity (P < 0.01). G-CSF infusion did not affect PMN infiltration into the liver and was accompanied by a 68% decrease in focal hepatocellular necrosis (P < 0.01). Infusion of IL-6, in contrast, dramatically decreased inflammation and injury in both the lung and liver; the anti-inflammatory effects of IL-6 may be mediated, in part, by down-modulation of nuclear factor (NF)-kappaB activity. Thus, circulating G-CSF and IL-6 have opposing effects on PMN recruitment and injury in the lung in HS while both protect against hepatic necrosis. The beneficial effect of these cytokines on liver injury in HS appears to be independent of PMN recruitment.

Evidence for protective and antioxidant properties of rutin, a natural flavone, against ethanol induced gastric lesions

This study was designed to determine the ulcer-protecting effects of rutin, a natural flavone, against gastric lesions induced by 50% ethanol, the experimental model related to lesion pathogenesis with production of reactive species. The possible involvement of sulphydryl compounds (SH), neutrophil infiltration, and the capacity of this flavone to restrain the oxidative process produced in the gastric tissue were also investigated. The levels of thiobarbituric acid (TBA, as index of lipid peroxidation), the myeloperoxidase activity (MPO, as a marker of neutrophil infiltration), the content of mucosal sulphydryls (SH) groups and the activity of glutathione peroxidase (GSH-Px, an important antioxidant enzyme) were determined. Pretreatment with the highest dose of rutin (200 mg/kg), 120 min before 50% ethanol, resulted in the most effective necrosis prevention. TBA reactive substances in the gastric mucosa, were increased by ethanol injury, and this increase was inhibited by the administration of 200 mg/kg of rutin. However, the flavonoid was not able to modify the ethanol-induced neutrophil infiltrate expressed as myeloperoxidase activity. Exposure of the gastric mucosa to 50% ethanol induced a significant diminution in gastric non-protein SH content; this parameter also was not modified by the treatment with rutin. GSH-Px activity decreased in the gastric mucosa after ethanol-treatment. In contrast, rutin at all tested doses induced a significant increase in this enzymatic activity, higher than in control group. These results suggest that the gastroprotective effect of rutin in this experimental model appears through an anti-lipoperoxidant effect, and also by enhancement of the anti-oxidant enzymatic (GSH-Px) activity.

Terbutaline prevents circulatory failure and mitigates mortality in rodents with endotoxemia

Septic shock is characterized by a decrease in systemic vascular resistance. Nevertheless, regional increases in vascular resistance can occur that may predispose mammals to organ dysfunction, including the acute respiratory distress syndrome. In the host infected by endotoxin (lipopolysaccharide, LPS), the expression and release of proinflammatory tumor necrosis factor-alpha (TNFalpha) rapidly increases, and this cytokine production is regulated by agents elevating cyclic AMP. In this report, we present evidence that terbutaline, a beta2-agonist, inhibits TNFalpha production and enhances interleukin-10 (IL-10) release in the anesthetized rat treated with LPS. In addition, an overproduction of nitric oxide (NO, examined by its metabolites nitrite/nitrate) by inducible NO synthase (iNOS, examined by western blot analysis) is attenuated by pretreatment of LPS rats with terbutaline. Overall, pretreatment of rats with terbutaline attenuates the delayed hypotension and prevents vascular hyporeactivity to norepinephrine. In addition, pretreatment of mice with terbutaline also improves the survival in a model of severe endotoxemia. The infiltration of polymorphonuclear neutrophils into organs (e.g., lung and liver) from the surviving LPS mice treated with terbutaline was reduced almost to that seen in the normal controls. These findings suggest that the inhibition of TNFalpha and NO (via iNOS) production as well as the increment of IL-10 production contribute to the beneficial effect of terbutaline in animals with endotoxic shock.

A novel synthetic anti-acute pancreatitis agent, IS-741

A novel synthetic drug, IS-741, inhibited cell adhesion in vitro and neutrophil in vivo. Thus, IS-741 inhibited the magnification of pancreatic lesion as well as progression to multiple organ failure in acute pancreatitis models. Furthermore, IS-741 at identical plasma concentrations equally improved the survival rates in animals of various species with severe acute pancreatitis. Based on these observations, it was considered that IS-741 inhibited tissue destruction by neutrophil after inhibiting neutrophil infiltration into the pancreas or other important organs in acute pancreatitis. It was also considered that IS-741 demonstrated various anti-acute pancreatitis effects by interrupting a vicious cycle of inflammation. Therefore, IS-741 is expected to become a useful drug for treating acute pancreatitis and multiple organ failure in clinical settings.

The novel carboxamide derivative IS-741 reduces neutrophil chemoattractant production by bronchoalveolar macrophages in rats with cerulein-induced pancreatitis complicated by sepsis

BACKGROUND/AIMS

The priming mechanism of macrophages to secrete cytokines in acute pancreatitis is important for remote organ failure following septic complication. The effects of novel carboxamide derivative, IS-741, on neutrophil chemoattractant production by bronchoalveolar macrophages were studied in rats with cerulein-induced pancreatitis complicated by sepsis.

METHODS

Pancreatitis was induced by four intramuscular injections of cerulein (50 microg/kg at 1-hour intervals). Pancreatitis rats were injected intraperitoneally with 10 mg/kg of lipopolysaccharide (LPS) 6 h following the first cerulein injection as a septic challenge. Pancreatitis rats received a continuous intravenous injection of IS-741 (3 mg/kg/h) 30 min before the septic challenge.

RESULTS

Intense mononuclear cell infiltration and lung hemorrhage occurred in untreated pancreatitis rats complicated with sepsis, but hemorrhage was not seen in septic pancreatitis rats receiving a continuous intravenous injection of IS-741 shortly before sepsis induction. The IS-741-treated rats had lower serum concentrations of cytokine-induced neutrophil chemoattractant (CINC), as well as fewer the pulmonary neutrophils and infiltrates immunoreactive for CINC or Mac-1 (CD11b/CD18).

CONCLUSION

The novel carboxamide derivative IS-741 reduced CINC production by bronchoalveolar macrophages and effectively prevented pancreatitis-associated lung injury following the septic challenge.

[Cigarette smoke-induced acute airway impairment]

Cigarette smoking has been implicated in many pulmonary disorders, including chronic bronchitis and chronic obstructive lung disease. Cigarette smoking is associated with increased airway responsiveness. Acute exposure to cigarette smoke increases airway responsiveness in a dose-dependent manner. A superoxide is involved in airway hyper-responsiveness induced by cigarette smoke, perhaps by direct toxic action. Cigarette smokers have increased numbers of neutrophils present in their lower respiratory tract. Acute exposure to cigarette smoke initiates a superoxide-dependent mechanism that, through NF-kappa B activation and IL-8 expression, induces infiltration of neutrophils into the airways in vivo. The alveolar macrophage is one potential source of NF-kappa B activation and IL-8 production after acute exposure to cigarette smoke. Manipulation of NF-kappa B by antioxidants in vivo may be useful in limiting biologic processes such as pro-inflammatory cytokine production, which may lead to neutrophil accumulation in the lung.

Lipoxin A(4) analogues inhibit leukocyte recruitment to Porphyromonas gingivalis: a role for cyclooxygenase-2 and lipoxins in periodontal disease

The potential involvement of the inducible cyclooxygenase isoform (COX-2) and the role of novel lipid mediators were investigated in the pathogenesis of periodontal disease. Crevicular fluids from localized juvenile periodontitis (LJP) patients contained prostaglandin (PG)E(2) and 5-lipoxygenase-derived products, leukotriene B(4), and the biosynthesis interaction product, lipoxin (LX)A(4). Neutrophils from peripheral blood of LJP patients, but not from asymptomatic donors, also generated LXA(4), suggesting a role for this immunomodulatory molecule in periodontal disease. To characterize host responses of interest to periodontal pathogens, Porphyromonas gingivalis was introduced within murine dorsal air pouches. In the air pouch cavity, P. gingivalis elicited leukocyte infiltration, concomitant with elevated PGE(2) levels in the cellular exudates, and upregulated COX-2 expression in infiltrated leukocytes. In addition, human neutrophils exposed to P. gingivalis also upregulated COX-2 expression. Blood borne P. gingivalis gave significant increases in the murine tissue levels of COX-2 mRNA associated with both heart and lungs, supporting a potential role for this oral pathogen in the evolution of systemic events. The administration of metabolically stable analogues of LX and of aspirin-triggered LX potently blocked neutrophil traffic into the dorsal pouch cavity and lowered PGE(2) levels within exudates. Together, these results identify PMN as an additional and potentially important source of PGE(2) in periodontal tissues. Moreover, they provide evidence for a novel protective role for LX in periodontitis, limiting further PMN recruitment and PMN-mediated tissue injury that can lead to loss of inflammatory barriers that prevent systemic tissue invasion of oral microbial pathogens.

Effect of D-002 on acetic acid-induced colitis in rats at single and repeated doses

D-002 is a natural mixture of higher aliphatic primary alcohols purified from beeswax, with mild anti-inflammatory and effective antiulcer effects experimentally proved. Furthermore, it reduces leukotriene (LTB(4)) in the exudate of carrageenan-induced pleurisy and has a protective effect on the pre-ulcerative phase of carrageenan-induced colonic ulceration in the guinea pig. This study was conducted to determine the effect of D-002 on acetic acid-induced colitis in rats at single and repeated doses. In a first series, D-002 was orally administered at 25 and 50 mg kg(-1), 24 h before the induction of colitis, meanwhile, in a second series, it was administered 24 h after the induction of colitis. Two other series (III and IV) examined the protective and therapeutic effect of D-002 administered for 7 days at the same doses, before or after colitis induction. Significant reductions in wet weight, macroscopic injury, polymorphonuclear infiltration and wall thickness were observed in colonic mucosa of D-002-treated animals compared with controls in both protective and therapeutic alternatives. It is concluded that D-002 was effective to protect or prevent the damage associated to acetic acid-induced colitis.

Cadmium-induced acute hepatic injury is exacerbated in human interleukin-8 transgenic mice

It is reported repeatedly that severe hepatocellular necrosis along with infiltration of neutrophils occurs after acute cadmium exposure. Neutrophils, which migrate by the gradient of chemoattractants such as interleukin-8, are believed to play an important role in inflammation at the damaged sites. To investigate whether neutrophils aggravate or repair the liver injury induced by cadmium, we checked the hepatotoxic effects of cadmium on human interleukin-8 transgenic mice (hIL-8Tg), which overexpressed IL-8 and displayed an inability of neutrophil migration resulting from both the lack of chemotactic gradient and the downregulation of l-selectin on the surface of neutrophils. A significantly lower survival rate was observed in hIL-8Tg compared with wild-type mice after subcutaneous administration of cadmium. Evident liver injury characterized by abrupt increases in plasma GOT and GPT levels was found in hIL-8Tg at 18 h after cadmium administration. Histological examinations, including H & E staining and esterase staining, revealed the infiltration of numerous neutrophils into the damaged liver tissues in wild-type mice, and the inhibition of the neutrophil migration into the liver as well as enhanced hepatocellular necrosis in hIL-8Tg. Peripheral white blood cell and polymorphonuclear cell counts increased and reached their peaks at 12 h after cadmium administration in wild-type mice, whereas the increase in blood leukocyte counts was delayed in hIL-8Tg. There was no significant difference in the amounts of cadmium accumulated in liver and kidneys between wild-type mice and hIL-8Tg. In conclusion, an acute cadmium hepatotoxic effect was exacerbated in hIL-8Tg resulting from inhibited neutrophil migration, suggesting that migrated neutrophils can prevent aggravation of liver injury by acute cadmium administration.

New approaches to the management of COPD

Airflow limitation in COPD is a result partially of bronchospasm, but it is also caused by a reduction in airway caliber, the number of small airways, airway collapse because of loss of connective tissue support, excess mucus in the airways, and edema of the airway wall. Structural changes also occur because of long-term destruction of interstitial connective tissue, including elastin. Therefore, in addition to the traditional aim of reversing bronchospasm with bronchodilators, disease-modifying approaches are being investigated. The enzyme neutrophil elastase is implicated in the induction of bronchial disease causing structural changes in lungs, impairment of mucociliary clearance, and impairment of host defenses. The precise mechanism pathway of neutrophil elastase is uncertain, but the effects of influencing the pathway in order to slow disease progression are being investigated. Oxidants may also have a role in the development of COPD, with increased levels activating airway cells and cytokine production.

Effect of San-Ao-Tang on immediate and late airway response and leukocyte infiltration in asthmatic guinea pigs

San-Ao-Tang (SAT), a traditional Chinese medicines, has been used to treat patients with the bronchial asthma for several centuries. However, the therapeutic mechanisms of this Chinese medicine are still far from clear. To understand the mechanism of antiasthmatic property of SAT, a guinea pig model of allergic asthma was used to investigate the effects of SAT on Dermatophagoides pteronyssinus-induced immediate and late asthmatic responses and airway inflammation. Our results showed that administration of SAT (10 g/kg) extracts significantly inhibited the antigen induced immediate asthmatic responses (IAR) in actively sensitized guinea pig. Examination of bronchoalveolar lavage fluid (BALF) revealed that SAT significantly inhibited the increase in neutrophil in the airway at 1, 2, 4, 6, 8 hr after antigen challenge. Histopathologic examination showed SAT suppressed the neutrophil infiltration into lung tissue. These results suggest that the antiasthmatic effect of SAT be mainly due to its bronchodilator effect and its ability to inhibit the neutrophil into the airway. The precise mechanism of action of SAT in asthma remains to be elucidated.

Acute exposure to diesel exhaust increases IL-8 and GRO-alpha production in healthy human airways

We have previously demonstrated that short-term exposure to diesel exhaust (DE) for 1 h induced a marked leukocytic infiltration in the airways of healthy human volunteers involving neutrophils, lymphocytes, and mast cells along with increases in several inflammatory mediators. We hypothesized that the leukocyte infiltration and the various inflammatory responses induced by DE were mediated by enhanced chemokine and cytokine production by resident cells of the airway tissue and lumen. To investigate this, 15 healthy human volunteers were exposed to diluted DE and air on two separate occasions for 1 h each in an exposure chamber. Fiberoptic bronchoscopy was performed 6 h after each exposure to obtain endobronchial biopsies and bronchial wash (BW) cells. Using reverse transcriptase/polymerase chain reaction enzyme-linked immunosorbent assay (RT-PCR ELISA), a novel and sensitive technique to quantify relative amounts of cytokine mRNA gene transcripts, and immunohistochemical staining with computer-assisted image analysis to quantify expression of cytokine protein in the bronchial tissue, we have demonstrated that DE enhanced gene transcription of interleukin-8 (IL-8) in the bronchial tissue and BW cells along with increases in IL-8 and growth-regulated oncogene-alpha (GRO-alpha) protein expression in the bronchial epithelium, and an accompanying trend toward an increase in IL-5 mRNA gene transcripts in the bronchial tissue. There were no significant changes in the gene transcript levels of interleukin-1B (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interferon gamma (IFN-gamma), and granulocyte macrophage colony-stimulating factor (GM-CSF) either in the bronchial tissue or BW cells after DE exposure at this time point. These observations suggest an underlying mechanism for DE-induced airway leukocyte infiltration and offer a possible explanation for the association observed between ambient levels of particulate matter and various respiratory health outcome indices noted in epidemiological studies.

An in vivo approach showing the chemotactic activity of leukotriene B(4) in acute renal ischemic-reperfusion injury

Neutrophil migration protects the body against foreign invasion. Sequestration and activation of neutrophils, however, require stringent regulation because they may also cause tissue damage by the release of lysosomal enzymes and reactive oxygen species. The activity of various chemoattractants [e.g., leukotriene B(4) (LTB(4)), interleukin-8, and complements] has been documented by in vitro assays, whereas in vivo data have been limited mostly to histology. To examine in an in vivo model the chemotactic activity and subsequent tissue infiltration and the role of a specific chemoattractant, LTB(4), we used a rat renal ischemia-reperfusion injury model. Fluorescence-labeled Chinese hamster ovary (CHO) cells stably expressing the LTB(4) receptor (CHO-BLT) were able to accumulate along with neutrophils in the postischemic kidney, in contrast to vector control CHO cells. Furthermore, LTB(4) antagonists that protect against the decrease in renal function and diminish the tissue myeloperoxidase activity also led to the marked decrease in the number of CHO-BLT cells and neutrophils. Thus, LTB(4) alone appears sufficient to cause cells to migrate into postischemic tissues, and its dominant role in reperfusion injury has been demonstrated. The utilization of transfectants to pinpoint the role of LTB(4) in these in vivo experiments suggests their potential use with other ligands and/or in other pathological conditions.

Migration of CD18-deficient neutrophils in vitro: evidence for a CD18-independent pathway induced by IL-8

Neutrophils isolated from a child with severe leukocyte adhesion deficiency 1 (LAD1) had a complete absence of expression of the CD11/CD18 beta2 integrin family of adhesion molecules, and were shown to be deficient in the in vitro adhesion and migration properties. However, we found that interleukin-8 (IL8), a potent chemoattractant for neutrophils, and sputum sol phase induced these LAD1 neutrophils to migrate through an endothelial cell layer in vitro, and confirmed that this migration was CD18-independent. These findings add to evidence of CD18-independent mechanisms of neutrophil recruitment, in particular neutrophil infiltration into the lungs, where IL8 may be an important recruitment factor.

Attenuation of cadmium-induced liver injury in senescent male fischer 344 rats: role of Kupffer cells and inflammatory cytokines

In the previous study we showed that senescent male Fischer 344 rats were resistant to Cd-induced hepatotoxicity compared with young-adult rats. In the present study we investigated the role of Kupffer cells and inflammatory cytokines in this effect of aging. The phagocytic activity of Kupffer cells, determined as the removal of carbon from blood, was stimulated by the administration of a hepatotoxic dose of Cd (3 mg/kg sc) in young-adult (5 months) rats but not in old (28 months) rats. Hepatic concentrations of interleukin (IL)-1beta and cytokine-induced neutrophil chemoattractant (CINC), but not of tumor necrosis factor-alpha or IL-6, were elevated in young rats treated with Cd. In old rats, however, the increase in IL-1beta produced by Cd was not statistically significant and the increase in CINC was much lower than in young-adult rats. Pretreatment with gadolinium chloride or cyclosporin A inhibited the elevations in hepatic cytokines and attenuated Cd-induced liver damage, assessed on the basis of serum alanine aminotransferase and sorbitol dehydrogenase activities. Cd-induced hepatotoxicity in the different treatment groups correlated well with hepatic levels of CINC (r = 0.98, p < 0.001) but not with those of IL-1beta. The results suggest that (1) Kupffer cell activation is essential for inflammatory liver damage from Cd, (2) IL-1beta and CINC are important mediators of the inflammatory response induced by Cd, and (3) the attenuation of Cd-induced liver injury in senescent rats is caused by an impairment in Kupffer cell activation, leading to a lower production of CINC and less inflammatory liver injury.

Increased expression of cyclooxygenase 2 mediates oil fly ash-induced lung injury

We have previously shown that in vitro exposure to the combustion-derived ambient air pollutant residual oil fly ash (ROFA) induces the expression of prostaglandin H synthase 2 (COX2) in human airway epithelial cells. To determine the role of prostaglandins and COX2 expression in ROFA-induced lung injury in vivo, we have examined the effect of intratracheal ROFA instillation on COX2 expression, prostaglandin synthesis, and indices of pulmonary injury and inflammation in adult Sprague-Dawley rats. ROFA treatment induced a marked increase in the level of prostagladin E2 (PGE2) recovered in the bronchoalveolar lavage fluid (BALF), which was effectively decreased by pretreating the animals with the specific COX2 inhibitor NS398. Immunohistochemical analyses of rat airways showed concomitant expression of COX2 in the proximal airway epithelium of rats treated with ROFA. Increases in BALF protein, but not interleukin 6 (IL-6) increases or ROFA-induced polymorphonuclear neutrophils (PMN) influx into the airway, were blunted by administration of NS398 prior to ROFA instillation. These data demonstrate that prostaglandins mediate lung injury induced by exposure to ROFA and implicate increased expression of COX2 as a mechanism that contributes to the toxicity of metal-laden ambient particulate matter.

Effects of lipopolysaccharide priming on acute ischemic brain injury

BACKGROUND AND PURPOSE

Infection has been implicated as a stroke risk factor. Activation and infiltration of polymorphonuclear neutrophils (PMNs) after cerebral ischemia may contribute to ischemic brain injury. This study was conducted to investigate how enhanced postischemic PMN infiltration by lipopolysaccharide (LPS) altered the acute ischemic outcomes.

METHODS

LPS (0.05 mg/kg SC) or vehicle was given to Long-Evans male rats 24 hours before ischemia. Focal cerebral ischemia was induced by temporary ligation of the right middle cerebral artery and both common carotid arteries for 45 minutes. Animals were killed 6 and 24 hours after reperfusion to determine the extent of PMN infiltration (myeloperoxidase assay), brain edema (wet-dry weight method), and vascular injury (fluorescein isothiocyanate-conjugated dextran extravasation). The infarct volumes were measured on the basis of TTC stain 24 hours after ischemia.

RESULTS

LPS had little effect on body temperature or peripheral white count but substantially enhanced PMN infiltration into the ischemic right middle cerebral artery cortex on the basis of myeloperoxidase activity (6 hours: control, 0 U/g; LPS, 0.186+/-0. 025 U/g; 24 hours: control, 0.185+/-0.025 U/g; LPS, 0.290+/-0.040 U/g; P<0.001) and morphological studies. The extent of vascular injury defined by the extravasation of fluorescein isothiocyanate-conjugated dextran into the ischemic tissue (6 hours: control, 3.11+/-0.41 microliter/mg protein; LPS, 0.48+/-0.16 microliter/mg protein; 24 hours: control, 1.77+/-0.23 microliter/mg protein; LPS, 0. 90+/-0.19 microliter/mg protein; P<0.001) and brain edema determined by the brain water content (6 hours: control, 84.77+/-1.63%; LPS, 82. 09+/-1.25%; 24 hours: control, 89.40+/-0.43%; LPS, 87.88+/-0.58%; P<0.01) were paradoxically reduced by LPS priming. LPS-primed rats also had smaller infarct volumes (control, 135+/-5 mm(3); LPS, 108+/-12 mm(3); P<0.05).

CONCLUSIONS

Enhanced postischemic PMN infiltration is anticipated to facilitate ischemic brain injury. Contrary to this expectation, results from the present study suggest that an increase in postischemic PMN infiltration after LPS priming was not detrimental. These findings challenge the notion that postischemic PMN infiltration is uniformly deleterious.

Vascular endothelial growth factor attenuates trauma-induced injury in rats

Endothelial dysfunction and loss of nitric oxide (NO) is an integral part of the initiation and maintenance of the inflammatory process such as that occurring in traumatic shock, and is considered responsible for much of the trauma induced microvascular injury. We investigated the effects of a vascular endothelial growth factor (VEGF) in a rat model of traumatic shock. Pentobarbital-anaesthetized rats subjected to Noble-Collip drum trauma developed a shock state characterized by marked hypotension and a 93% mortality rate with a mean survival time of 108+/-10 min in 14 rats. Accompanying these effects was a significant degree of endothelial dysfunction and a markedly elevated intestinal myeloperoxidase (MPO) activity. Treatment with 125 microg kg(-1) VEGF administered intravenously 18 h pre-trauma, increased survival rate to 67% (P<0.01), and prolonged survival time to 252+/-24 min in 12 rats (P<0.01). VEGF also significantly preserved the endothelium-dependent relaxation to ACh indicating a preservation of endothelium-derived NO. Our results indicate that endothelial dysfunction with its accompanying loss of NO plays an important role in tissue injury associated with trauma, and that preservation of NO is beneficial in traumatic shock. The mechanisms of the protective effect of VEGF in trauma involves preservation of eNOS function and diminished neutrophil accumulation resulting in reduced neutrophil-mediated tissue injury. British Journal of Pharmacology (2000) 129, 71 - 76

N-bisphosphonates cause gastric epithelial injury independent of effects on the microcirculation

BACKGROUND

Nitrogen-containing bisphosphonates have been shown to be effective for the treatment of osteoporosis and Paget's disease of bone. Unfortunately, these drugs also have the capacity to irritate the upper gastrointestinal mucosa. In this study we investigated the ability of alendronate and pamidronate to directly damage the gastric epithelium and attempted to determine whether these drugs caused injury through gastric microcirculatory alterations.

METHODS

An ex vivo gastric chamber model was used. Effects of topically applied alendronate and pamidronate on transmucosal potential difference and epithelial integrity (histology) were determined. Also, the effects of agents capable of preventing microvascular injury in the stomach (PGE2 and two nitric oxide donors) were examined for their ability to prevent gastric injury induced by the two N-bisphosphonates.

RESULTS

Alendronate and pamidronate caused a concentration-dependent decrease in transmucosal potential difference, widespread epithelial injury and infiltration of neutrophils into the mucosa. PGE2 and the two nitric oxide donors did not prevent the changes in potential difference or the epithelial injury, but did reduce neutrophil infiltration. Significant release of PGE2 into the lumen was observed following application of the two bisphosphonates, but neither drug altered mucosal blood flow.

CONCLUSIONS

These results suggest that these N-bis- phosphonates directly damage the gastric epithelium independent of actions on the microvasculature.

The immune system and the effects of non-volatile anesthetics on neutrophil transmigration through endothelial cell monolayers

Inflammation represents the consequence of capillary dilation with accumulation of fluid and transmigration of leukocytes into the surrounding tissue. Leukocytes play a major role in the defense system of the body against invading microorganisms. This defense system has a non-specific branch consisting of granulocytes and macrophages and a specific branch of lymphocytes. Granulocytes release cytotoxic compounds from their intracellular granules into their local environment when encountering microorganisms. This random destruction happens rapidly, but it may also harm healthy tissue of the body. Leukocytes patrol the body by circulating through the blood and lymphatic system ensuring a continuous surveillance which is a prerequisite for an efficient defense. Upon tissue damage and inflammation, leukocytes are recruited from the blood to sites of injury, and this trafficking displays exquisite specificity. In the late 1890 s, Metchnikoff noted the power of certain blood cells to move towards microorganisms and ingest them. In fact, leukocytes adhere to the endothelium of the blood vessels, and subsequently leave the circulation by transmigration through the intercellular junctions of the endothelial cell monolayer. Transmigration is driven by chemoattractants, a process known as diapedesis. Reversible adherence of leukocytes to the endothelium, basement membranes, and other surfaces is an essential event in the establishment of inflammation, whose molecular basis is beginning to be understood. Inflammation may become chronic in many pathophysiologic processes and disease states. In long-term mechanically ventilated critically ill patients, non-volatile anesthetics are needed over a prolonged time period. Perioperative infections are a major cause of morbidity and mortality in critically ill patients. Therefore, the influence of non-volatile anesthetics and opioid agents on the immune system is of high interest. After presentation of the different effectors of the immune system and their fluxes through the body, the aim of this review is to propose a general model of leukocyte transmigration through endothelial cell monolayers. It emphasizes in which way different non-volatile anesthetic drugs may affect the non-specific branch of the immune system, i.e. the leukocyte transmigration through endothelial cell monolayers.

Tetrandrine ameliorates ischaemia-reperfusion injury of rat myocardium through inhibition of neutrophil priming and activation

1. We have previously shown that tetrandrine (TTD), a bisbenzyltetrahydroiosquinoline isolated from the Chinese herb Stephania tetrandra, inhibits neutrophil adhesion, Mac-1 expression, and reactive oxygen species (ROS) production. To examine whether inhibition of neutrophil function may confer upon TTD the ability to prevent myocardial ischaemia-reperfusion (MI/R) injury, experiments were performed on rats subjected to coronary ligation followed by reperfusion for induction of MI/R injury. 2. Intravenous administration of TTD (0.1 and 1.0 mg kg-1) 15 min prior to coronary ligation completely prevented MI/R-associated mortality. TTD pretreatment also significantly reduced MI/R-induced ventricular tachyarrhythmia, myocardial infarct size, and neutrophil infiltration. 3. However, TTD pretreatment did not influence mean arterial blood pressure, heart rate, or product of pressure-rate, indicating that TTD extenuated MI/R through mechanisms independent of modulating haemodynamics or myocardial oxygen demand. 4. Peripheral blood neutrophils were isolated for ex vivo examination of shape change and Mac-1 upregulation of neutrophils, two sensitive indicators of proinflammatory priming, as well as N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced adhesion and ROS production, parameters commonly used for the assessment of neutrophil activation. 5. Neutrophils from MI/R animals showed significant shape change and Mac-1 upregulation, both of which were prevented by TTD-pretreatments. On the other hand, fMLP-induced adhesion and ROS production of neutrophils were markedly enhanced by MI/R but diminished in TTD-pretreated animals. 6. These data suggest that the protective effect of TTD against MI/R injury can be accounted for by inhibition of neutrophil priming and activation, thereby abolishing subsequent infiltration and ROS production that cause MI/R injury.

Leukotrienes are involved in leukocyte recruitment induced by live Histoplasma capsulatum or by the beta-glucan present in their cell wall

1. The inflammatory cell influx towards the peritoneal cavity in mice inoculated i.p. with live or dead Histoplasma capsulatum or with its subcellular preparations was studied. We also evaluated the effects of dexamethasone (Dexa) or MK886, an inhibitor of leukotriene (LT) biosynthesis, on the recruitment of leukocytes. 2. Live yeast form of fungus (LYH) induced an increase in neutrophils (NE) which was highest 4 to 24 h after inoculation. Mononuclear cell (MN) migration beginning at 24 h with a gradual increase over 48 and 168 h, and an eosinophil (EO) recruitment occurs between 24 and 48 h. 3. NE and EO recruitment induced by dead mycelial form of fungus (DMH) was greater than that observed for dead yeast form of fungus (DYH). A similar leukocyte migration pattern was seen after i.p. injection of the alkali-insoluble fraction (F1) from DYH (F1Y) and F1 from DMH (F1M) this being more active than former. The difference in concentration of beta-glucan in DYH and DMH could explain the different inflammatory capacity exhibited by the two forms of H. capsulatum. 4. LT seems to be the principal mediator of leukocyte migration in response to LYH, DYH or DMH or to beta-glucan. However, other mediators appear to contribute to NE and EO migration since the treatment with Dexa was more effective in inhibiting cell migration than MK886. Complement dependent leukocyte migration may participate in this recruitment. Treatment with MK886 completely abolished MN cell migration, indicating its dependence on the presence of LT.

Protective effect of liver ischemic preconditioning on liver and lung injury induced by hepatic ischemia-reperfusion in the rat

This study evaluates whether preconditioning could modulate the injurious effects of tumor necrosis factor (TNF) on liver and lung following hepatic ischemia-reperfusion (I/R) by inhibiting hepatic postischemic TNF release. The inhibition of hepatic TNF release from Kupffer cells with gadolinium chloride (GdCl(3)) previous to ischemia maintained TNF at control levels, attenuating the increases in transaminases, vascular permeability, and edema associated with hepatic I/R injury. TNF addition reverted this beneficial effect, indicating the implication of the TNF released mainly from Kupffer cells in hepatic I/R injury. Preconditioning prevented hepatic TNF increases, thus attenuating the liver injury, while TNF addition abolished the benefits of preconditioning. Inhibition of nitric oxide (NO) synthesis abolished the effect of preconditioning, whereas GdCl(3) addition avoided the injurious effect of NO inhibition. In addition, NO administration before I/R offered similar results to those found in preconditioning, while TNF addition abolished the benefits of NO. Thus, the effect of preconditioning on TNF release after hepatic I/R is mediated by NO. Inhibition of hepatic TNF release from Kupffer cells with GdCl(3) prevented both the increase in plasma TNF and the injurious effect in lung seen after hepatic I/R, and these effects were reverted with TNF addition. Preconditioning resulting in reduced hepatic TNF levels prevented the systemic TNF release, thus reducing the lung damage following hepatic I/R. However, TNF addition abolished the protective effect of preconditioning on lung injury. These findings indicate that preconditioning attenuates hepatic postischemic TNF release from Kupffer cells, thus probably reducing the liver and lung injury following hepatic I/R, and that this effect of preconditioning is mediated by NO.

Rapid, fluorescence-based assay for microtiter plates to test drug influences on neutrophil transmigration through endothelial cell monolayers

Investigation of drug interactions between blood cells and endothelium is of high interest. The current study describes the development of a rapid fluorescence-based leukocyte transmigration system through endothelial cell monolayers for investigation of drug influences. To test the new assay, endothelial cells were cultured on microporous filters, pore size 3.0 microm, in 96-well-plates. Freshly isolated neutrophils were seeded on endothelial cell monolayers and transmigrated cells were measured after incubation for three hours. Migration of non-stimulated neutrophils through non-stimulated endothelial cell monolayer was used as control and set as 100%. The influence of the non-steroidal anti-inflammatory drug diclofenac was investigated. Assay precision tests were done using intraassay (within-day variability) and interassay (day-to-day variability) controls. Transmigration rate was decreased to 53 +/- 6.8% SD (diclofenac 0.7 microg/mL). Different concentrations showed a dose dependent effect (0.07 microg/mL: 97 +/- 9.5%, 7 microg/mL: 37 +/- 4.7%). Analysis of assay accuracy of the new 96-well-sized transmigration assay showed reliable results (coefficient of variation: intraassay 8.2 %; interassay 11.8%). In conclusion, this new, rapid, and sample saving 96-well-microtiter transmigration assay allows examination of drug influence on neutrophil migration through endothelial cell monolayers. Moreover, this assay can also be used for other cell-cell interactions.

Lipoxin A4 and aspirin-triggered 15-epi-LXA4 inhibit tumor necrosis factor-alpha-initiated neutrophil responses and trafficking: novel regulators of a cytokine-chemokine axis relevant to periodontal diseases

The impact of lipoxin A4 (LXA4) and aspirin-triggered-lipoxins (ATL) was investigated in tumor necrosis factor (TNF alpha)-initiated neutrophil (PMN) responses in vitro and in vivo using LX analogs that are metabolically more stable. At nanomolar levels, the LXA4 and ATL analog 15 R/S-methyl-LXA4 each blocked TNF alpha-stimulated IL-1 beta release by isolated human PMN in vitro. These LXA4-ATL actions were time- and concentration-dependent. The TNF alpha-induced IL-1 beta gene expression was also regulated by 15 R/S-methyl-LXA4. In addition, 15 R/S-methyl-LXA4 added to murine air pouches dramatically inhibited TNF alpha-stimulated leukocyte trafficking in vivo, as well as altered the appearance of both macrophage inflammatory peptide-2 and IL-1 beta and concomitantly stimulated IL-4 in pouch exudates. These findings from in vitro and in vivo experiments indicate that both LXA4 and ATL are regulators of TNF alpha-directed neutrophil actions and stimulate IL-4 in exudates and thus regulate mediators that are held to play an important role in the pathogenesis of periodontal disease.

Oral contraceptives that contain ethinyl estradiol (0.035 mg) and cyproterone acetate (2 mg) inhibit leukocyte transmigration through endothelial cell monolayers

OBJECTIVE

To investigate the influence of ethinyl estradiol and cyproterone acetate in oral contraceptives on leukocyte migration through endothelial cell monolayers.

DESIGN

Experimental in vitro prospective study.

SETTING

An academic research laboratory.

INTERVENTION(S)

Endothelial cells were cultured on microporous membranes to produce monolayers. Polymorphonuclear leukocytes were used in a previously described migration assay (n = 7). The amount of untreated polymorphonuclear leukocytes that migrated through untreated endothelial cell monolayers was used as a control and set at 100%. In addition, a leukocyte adhesion assay was used.

MAIN OUTCOME MEASURE(S)

Leukocyte adhesion to and transmigration through endothelial cell monolayers.

RESULT(S)

Ethinyl estradiol and cyproterone acetate inhibited the migration of polymorphonuclear leukocytes through endothelial cell monolayers significantly (67% +/- 6.4%) when both cell types were treated to simulate in vivo conditions. The adhesion assay produced similar results.

CONCLUSION(S)

Ethinyl estradiol and cyproterone acetate were identified as potent inhibitors of leukocyte migration through endothelial cell monolayers.

Effects of ethanol on neutrophil recruitment and lung host defense in nitric oxide synthase I and nitric oxide synthase II knockout mice

BACKGROUND

Ethanol (ETOH) inhibits Escherichia coli endotoxin [lipopolysaccharide (LPS)]-mediated induction of nitric oxide (NO) synthase (NOS) transcription and translation in macrophages and neutrophils [polymorphonuclear (PMN) cells] within the lung. ETOH also inhibits PMN recruitment into the lung and enhances NOS I-mediated production of NO. The contribution of the individual NOS isozymes to ETOH-mediated suppression of the host defense response to lung infection has not been defined.

METHODS

We evaluated the role of constitutive NOS I and NOS II in ETOH-mediated inhibition of PMN recruitment into the lung and ETOH-mediated suppression of lung clearance of inhaled Klebsiella pneumonia (K. pneumoniae) in female, homozygous transgenic mice deficient in the genes for NOS I (nNOS-KO) or NOS II (iNOS-KO) and their wild-type controls (WT).

RESULTS

Four hours after intratracheal administration of LPS or aerosol inhalation of K. pneumoniae, the lung content of PMNs obtained by bronchoalveolar lavage from WT mice was significantly reduced when compared with that obtained from the lungs of nNOS-KO and iNOS-KO mice. Pretreatment of WT mice with the NOS II inhibitor L-N6-iminoethyllysine (L-NIL; 10 mg/kg, i.p.) or with the NOS I inhibitor 7-nitroindazole (7-NI) (10, 25, or 40 mg/kg, i.p.) 30 min before LPS administration enhanced the lung content of PMNs recoverable by bronchoalveolar lavage. However, pretreatment of iNOS-KO with L-NIL did not affect lung recruitment of PMNs. Moreover, administration of 25 or 40 mg/kg, i.p. of 7-NI to nNOS-KO mice resulted in death of all the animals within 10 min. Pretreatment of nNOS-KO with 7-NI (10 mg/kg) did not affect LPS-stimulated PMN recruitment. Pretreatment of mice with ETOH (4.5 g/kg, i.p.) produced a greater inhibition of LPS-stimulated lung recruitment of PMNs in iNOS-KO mice than in WT mice. In contrast, pretreatment of nNOS-KO with ETOH produced little inhibition of LPS-stimulated lung recruitment of PMNs when compared with that measured in WT mice. Finally, 4 hr after aerosol inhalation of K. pneumoniae, lung clearance of this bacteria was enhanced in iNOS-KO when compared with WT and inhibited in nNOS-KO when compared with WT mice. ETOH-mediated suppression of lung clearance of K. pneumoniae was unaffected in nNOS-KO mice and enhanced in the iNOS-KO mice, when compared with that obtained in WT mice. ETOH-stimulated the production of NOS I-derived nitrate and nitrite production by rat brain and lung and inhibited LPS-induced NOS II mRNA, protein, and production of nitrate and nitrite anion. Finally, inhibition of NOS I and NOS I deletion inhibited the in vivo metabolism of ETOH.

CONCLUSIONS

We conclude that constitutive NOS I is involved in protection of the lung from stressor-induced lung injury. NOS I within the PMNs may limit PMN recruitment into the lung. Speculatively, NOS II-derived NO may also limit PMN-induced lung damage at the expense of a slower clearance of the bacterial burden.

Effects of calcitonin gene-related peptide on tissue survival, blood flow and neutrophil recruitment in experimental skin flaps

Local administration of calcitonin gene-related peptide (CGRP) has been shown to improve tissue survival in surgical skin flaps. Moreover, topical CGRP has been demonstrated to exert anti-inflammatory effects in different animal models of skin inflammation. The aim of the present study was to establish whether systemic treatment with low doses of CGRP may improve survival and reduce neutrophil accumulation in surgical skin flaps. Using a well-established dorsal skin-flap model in the rat, we found that intraperitoneal (i.p.) pretreatment with low doses of CGRP dose-dependently increased flap survival. Thus, in untreated animals flap survival at day 7 after surgery was 42%, as compared to 44%, 60%, 69% and 73% survival after a single preoperative i.p. injection of 10(-15), 10(-12), 10(-9) and 10(-6) mol CGRP, respectively (P < 0.05 versus control for the three highest doses). The three effective doses had no detectable effects on either flap blood flow (laser Doppler) or mean arterial blood pressure. On the other hand, 5 x 10(-9) mol CGRP i.p. significantly reduced the marked surgery-induced accumulation of flap myeloperoxidase (a marker for neutrophil recruitment) without affecting the circulating neutrophil count. Taken together, our findings demonstrate that low systemic doses of CGRP can cause a major improvement in skin-flap survival in the rat, possibly via inhibition of surgically induced neutrophil recruitment.

Effect of anti-C5a antibody on blood-lung and blood-brain barrier in rabbits after decompression

The complement activation product C5a may be an important mediator of tissue injury after decompression stress. This study investigated whether the administration of anti-C5a antibody may reduce changes after decompression in the lung and in the brain. Two groups of rabbits were used; one receiving anti-C5a monoclonal antibody (n = 7) and the other receiving a sham antibody as control (n = 7) before pressure exposure. Five rabbits (4 in the anti-C5a group and 1 in the control group) died during the 2-h observation period postdive due to massive bubbling. Polymorphonuclear leukocyte (PMN) infiltration of lung tissue and pulmonary edema was observed, but this accumulation was unaffected by anti-C5a pretreatment. However, a significant positive correlation was observed between PMN accumulation and survival time postdive. Brain-specific gravity was lower for the group treated with anti-C5a antibody compared to the control group. Further, it was lower for those rabbits that died early compared to the ones that survived the 2-h period. This study was unable to prove a protective effect on the blood-brain and blood-lung barrier by injecting anti-C5a antibody. A possible beneficial effect of anti-C5a antibody may be masked by the mechanical damage caused by the gas bubbles.