Vascular changes play a role in the pathogenesis of necrotizing enterocolitis in asphyxiated newborn pigs.

Necrotizing enterocolitis (NEC) is the most common acquired gastrointestinal emergency in neonates. We have developed an animal model of NEC in asphyxiated newborn pigs and investigated the effects of asphyxia on blood flow in superior mesenteric artery and abdominal aorta, cardiovascular data, arterial acid-base and blood gas parameters, and endothelial cytoskeletal structure in mesenteric microvasculature. Anesthetized, mechanically ventilated newborn pigs were included in two groups: piglets underwent severe asphyxia, and sham-operated control animals. A cardiovascular and metabolic failure developed in asphyxiated piglets approximately 1 h after the induction: severe hypotension and bradyarrhythmia were seen and significant reductions of the blood flow were measured in the superior mesenteric artery and abdominal aorta during the critical phase. Rearrangement of cytoskeletal actin structure corresponding to enhanced vascular permeability was seen with bodipy phallacidin in mesenterial endothelium of asphyxiated piglets after a 24-h recovery period. In conclusion, severe vasomotor changes during asphyxia may result in mesenteric endothelial dysfunction implicated in increased vascular permeability, edema formation, and development of NEC in asphyxiated piglets.

Primary lymphoedema associated with xanthomatosis, vaginal lymphorrhoea and intestinal lymphangiectasia.

Primary lymphoedema associated with chylous reflux is a very rare clinical entity. We report a 3-year-old girl with unilateral lymphoedema, xanthomatosis and vaginal lymphorrhoea. Biopsy also revealed intestinal lymphangiectasia. This paper also presents a brief review of the literature and draws attention to the significance of the xanthomatous eruption in the diagnosis of a chylous reflux.

4-(2-Aminoethyl)benzenesulfonyl fluoride attenuates tumor-necrosis-factor-alpha-induced blood-brain barrier opening.

The effect of serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF) was investigated on the prevention of tumor-necrosis-factor-alpha (TNF-alpha)-induced blood-brain barrier opening. TNF-alpha (10,000 IU) was injected intracarotidly to newborn pigs pretreated with 0, 2.4, 4.8, 9.6 and 19.2 mg/kg AEBSF (n = 6 in each group). AEBSF dose-dependently inhibited the TNF-alpha-induced increase in the blood-brain barrier permeability for sodium fluorescein (MW = 376) in all of the five brain regions examined, while only 19.2 mg/kg AEBSF could significantly (P < 0.05) decrease the change in Evan's blue-albumin (MW = 67,000) transport in two regions. In conclusion, AEBSF attenuates vasogenic brain edema formation.

Intracarotid tumor necrosis factor-alpha administration increases the blood-brain barrier permeability in cerebral cortex of the newborn pig: quantitative aspects of double-labelling studies and confocal laser scanning analysis.

Tumor necrosis factor-alpha (TNF-alpha) plays a crucial role in the pathogenesis of the central nervous system infections. The aim of the present study was to analyze quantitatively the changes in the blood-brain barrier (BBB) permeability after the intracarotid injection of TNF-alpha. Recombinant human TNF-alpha was injected into the left internal carotid artery of anesthetized newborn pigs (n = 48) in the doses of 0, 1000, 10 000 and 100 000 IU, respectively. Before, as well as 1, 2, 4, 8, and 16 h after the challenge, the extravasation of a small (sodium fluorescein (SF), mw 376), and a large (Evan's blue-albumin (EBA), mw 67 000) tracer was determined concomitantly by spectrophotometry in the cerebral cortex of the animals. There was a time- and dose-dependent increase in BBB permeability both for SF and EBA; however, significant (P < 0.05) BBB opening for albumin only developed 2 h after the challenge. In the morphological study the same excitable tracers, identical experimental protocol and groups were used. Cryostat sections of brain tissue were viewed for optical sectioning with a confocal laser scanning microscope equipped with an argon/krypton ion laser. A diffuse BBB opening for SF and a moderate perivascular extravasation for EBA were found in the cortices of TNF-alpha-treated animals. We conclude that significant increases in intravascular TNF-alpha-concentration during neonatal infections may result in vasogenic brain edema formation.

Serine protease inhibitors block priming of monocytes for enhanced release of superoxide.

Monocytes freshly isolated from human blood produced large amounts of superoxide when triggered by phorbol ester. After monocytes were cultured for 18-24 hr in endotoxin-free, non-adherent conditions, they produced low amounts of superoxide. Addition of lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), or platelet-activating factor (PAF) at the beginning of culture 'primed' the monocytes, causing them to maintain a high superoxide response for at least 96 hr. Also, in response to LPS, monocytes secreted TNF-alpha. The ability of LPS, IFN-gamma, TNF-alpha or PAF to maintain the high superoxide response was blocked by addition of inhibitors of serine proteases, either 4-(2-aminoethyl)-benzenesulphonyl fluoride (AEBSF) or 3,4-dichloroisocoumarin. AEBSF was most effective at 200 microns, and required 6 hr for maximum effect. AEBSF did not affect phorbol-triggered superoxide release by unprimed monocytes. AEBSF did not affect cell viability, nor did it interfere with the TNF-alpha secretion in response to LPS. An analogue of AEBSF that lacked ability to inhibit proteases did not affect monocyte responses. 3,4-Dichloroisocoumarin blocked priming at a low concentration, 1 microM. We conclude that activity of a monocyte serine protease is required to maintain the high superoxide response in monocytes primed with LPS, IFN-gamma, TNF-alpha, or PAF.

Elastase given intracisternally opens blood-brain barrier in newborn piglets.

The effect of elastase on the blood-brain barrier (BBB) permeability was intravitally studied by fluorescence photomacroscope using the open cranial window technique in newborn piglets. Eleven animals (group 1) were given intracisternal injection of porcine elastase (1.0 micrograms), while 7 piglets served as controls (group 2). Elastase administration resulted in spotty sodium fluorescein (MW 376 daltons) extravasations in pial venules in all animals of group 1 78 +/- 4 min (mean +/- SEM) after the challenge, and in a 2-fold increase (p < 0.05) in brain sodium fluorescein uptake both in occipital cortex and white matter. The concentration of elastase-alpha 1-proteinase inhibitor complex increased significantly (p < 0.05) in cerebrospinal fluid samples in group 1, 2 and 4 h after the injection, while it did not change in sera. A significant pleocytosis and leukocytosis was also seen in group 1, while there was no change in laboratory data and BBB remained tight in group 2. BBB permeability changes during neonatal meningitis may be caused, at least partially, by elastase.

Escherichia coli 0111 B4 lipopolysaccharide given intracisternally induces blood-brain barrier opening during experimental neonatal meningitis in piglets.

Neonatal bacterial meningitis remains a life-threatening infection, and severe neurologic sequelae may be left in survivors as well. The goal of the study was to develop and characterize a porcine model of the disease with intravital observation of the permeability changes in cerebral microvessels. Eighteen newborn piglets were given doses of 0 ng (group 1), 20 ng (group 2), and 200 ng (group 3) of Escherichia coli 0111 B4 endotoxin (LPS) intracisternally (n = 6 in each group). Cardiovascular parameters were without changes, but a compensated metabolic acidosis occurred in group 3 4 h after LPS injection. Using the open cranial window technique combined with fluorescence excitation, there was no blood-brain barrier leakage in pial-arachnoid microvessels for sodium fluorescein during the 4 h of experiments in group 1 piglets, whereas spotty extravasations occurred in group 2 and in group 3 after the LPS injections (70.5 +/- 10.5 and 55.2 +/- 4.1 min, respectively, mean +/- SEM). A dose-dependent increase in sodium fluorescein uptake in brain regions examined (parietal and occipital cortex, cerebellum, and periventricular white matter) was also found by fluorescence spectrophotometry. LPS-treated piglets had developed pleocytosis. Four h after the challenge, the white blood cell counts in cerebrospinal fluid were (mean +/- SD): group 1, 8.2 +/- 7.6 microL-1; group 2, 453 +/- 703 microL-1; and group 3, 1 027 +/- 620 microL-1, respectively, whereas there was no change in white blood cell count of peripheral blood samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Recombinant human tumor necrosis factor alpha constricts pial arterioles and increases blood-brain barrier permeability in newborn piglets.

Tumor necrosis factor alpha (TNF alpha) plays a significant role in the pathogenesis of central nervous system infections. We investigated the effect of intracisternal injection of recombinant human TNF alpha (50-50,000 IU) on pial vasoreactivity and blood-brain barrier permeability in newborn piglets. The cytokine administration resulted in arterial vasoconstrictions, blood-brain barrier opening for Na-fluorescein (mol. wt. 376 Da) and increased Na-fluorescein uptake in brain regions examined (parietal and occipital cortex, cerebellum, pons/medulla, periventricular white matter) in a dose-dependent manner. TNF alpha may be involved in the pathophysiology of neonatal brain injuries.

Endotoxin-stimulated human macrophages produce a factor that induces polymorphonuclear leucocyte infiltration and is distinct from interleukin-1, tumour necrosis factor alpha and chemotactic factors.

Previously we reported that rabbit macrophages (M phi) in the presence of nanogram quantities of endotoxin (LPS) release factors that induce polymorphonuclear leucocyte (PMNL) infiltration into the skin of rabbits following i.d. injection. The predominant factor was a de novo synthesized protein of 45,000 MW on gel filtration that was distinguishable from IL-1 but not from TNF alpha. Here we examined human monocytes, in vitro monocyte-derived M phi and peritoneal M phi for the production of an analogous protein. Upon stimulation with LPS, they all rapidly (6 hr) produced a factor(s) that caused PMNL accumulation in the skin of rabbits when injected i.d. This activity, referred to as PMNL-recruiting activity (PRA), was heat labile and its production was blocked by cycloheximide. By Sephadex-G100 chromatography the major PRA of cultured M phi or peritoneal M phi had a molecular weight (MW) of 45,000-60,000. The active fractions were free of IL-1 (less than 0.2 U/ml) and Superose-12 FPLC chromatography separated the peak of PRA, which eluted at 45,000 MW, from TNF alpha, eluting at 20,000 MW. The peak PRA was not neutralized by antisera to IL-1 alpha, IL-1 beta, TNF alpha, IL-6 or GM-CSF, indicating that it was distinct from these cytokines. The major PRA did not induce the migration of PMNL in vitro in a filter chemotaxis assay. In contrast to the M phi, the major PRA produced by LPS-stimulated monocytes eluted at 15,000-20,000 MW, contained IL-1 activity and was neutralized by antisera to IL-1 alpha and IL-1 beta. Monocytes from a few donors also produced the 45,000-60,000 MW PRA simultaneously. We conclude that human peritoneal M phi and in vitro monocyte-derived M phi exposed to LPS secrete a protein of 45,000-60,000 MW, which is a potent inducer of PMNL infiltration but is distinct from IL-1, TNF alpha, IL-6, GM-CSF and PMNL chemotactic factors.

An endotoxin-induced factor distinct from interleukin-1 and tumour necrosis factor alpha produced by the THP-1 human macrophage line stimulates polymorphonuclear leukocyte infiltration in vivo.

Endotoxin and gram-negative bacteria induce vigorous inflammatory reactions. Our previous work showed that rabbit macrophages (M phi) incubated with endotoxin produce a 45,000 dalton protein that recruited polymorphonuclear leukocytes (PMNL) into the skin of rabbits. This factor was separated from interleukin-1 (IL-1) but could not be unequivocally distinguished from rabbit tumour necrosis factor (TNF alpha). Here we have examined the human M phi cell line, THP-1, for the production of an analogous protein. After exposure to phorbol diester the THP-1 cells assumed the characteristic M phi phenotype and function. During 6 hours of culture with LPS these M phi released a factor(s) that caused PMNL recruitment into the skin of rabbits when injected intradermally, measured using 51Cr-labelled blood leukocytes. This activity, referred to as PMNL recruiting activity (PRA), was heat labile, and its production was blocked by cycloheximide, suggesting that this is most likely a de novo synthesized protein. Sephadex-G 100 and Superose-12 FPLC chromatography indicated a molecular weight in the 45,000-65,000 dalton range. The active fractions were free of IL-1 activity (less than 0.2 U/ml), and Superose-12 chromatography separated the peak of PRA, which eluted around 45,000 daltons, from TNF alpha eluting at 20,000 daltons. The peak PRA was not neutralized by antiserum to IL-1 alpha, IL-1 beta TNF alpha, IL-6, and granulocyte-macrophage colony-stimulating factor (GMCSF), indicating that it was distinct immunologically from these cytokines. The major PRA did not induce migration of rabbit or human PMNLs in vitro in a Boyden chamber chemotaxis assay, although peaks of chemotactic activity and weak PMNL recruitment in vivo were detected in fractions eluting around 15,000 daltons and 800 daltons. The generation of PRA by a human M phi cell line is analogous to that reported previously with rabbit M phi. Here we extend these observations to a human M phi system and confirm that this molecule is distinct from several other M phi cytokines and M phi chemotactic factors with inflammatory properties.

Synergy between tumour necrosis factor alpha and interleukin-1 in the induction of polymorphonuclear leukocyte migration during inflammation.

Endotoxin is a potent inflammatory stimulus and induces polymorphonuclear leukocyte (PMNL) infiltration into tissues. Macrophage (M phi) derived IL-1 has been proposed as a mediator of this response. TNF alpha is also produced by M phi s in response to endotoxin and both IL-1 and TNF enhance PMNL adhesion to vascular endothelium in vitro. We investigated the activity of recombinant human IL-1 alpha, IL-1 beta, and TNF alpha in inducing PMNL infiltration into the skin of rabbits using a quantitative 51Cr labelled blood leukocyte assay. IL-1 alpha and IL-1 beta induced progressive PMNL accumulation, the 50% maximal response being induced by approximately equal to 20 units. In comparison, TNF alpha even at 100,000 U, induced only mild PMNL accumulations, although IL-1 alpha and TNF alpha were similarly active in inducing PMNL adherence to human umbilical vein endothelium. The human TNF alpha preparation was pyrogenic and induced acute, transient neutropenia in rabbits upon i.v. infusion, IL-1 alpha, IL-1 beta and TNF alpha are often secreted simultaneously by M phi s, therefore we investigated their action in combination. The combination of IL-1 alpha with IL-1 beta was nearly additive in inducing PMNL accumulation, i.e., 87% of predicted result based on the sum of the responses to individual components. The combination of TNF alpha with either IL-1, each in submaximal doses, resulted in 65-125% greater than the additive response. No such effect was observed when these monokines were injected in combination with PMNL chemotactic stimuli. These results indicate a complex interaction between inflammatory monokines in the regulation of PMNL accumulation in vivo.

Role for macrophage products in endotoxin-induced polymorphonuclear leukocyte accumulation during inflammation.

Endotoxins (lipopolysaccharide, LPS) released by Gram-negative bacteria induce acute inflammation with polymorphonuclear leukocyte (PMNL) infiltration. The mechanism of PMNL accumulation appears to be complement-independent and is not well understood. Here, we report investigation of the factors which may mediate LPS-induced PMNL accumulation in the pleural cavity and skin of rabbits. The intrapleural injection of 50 ng of Escherichia coli 0111 LPS caused the appearance in the exudate fluid of an activity which, upon intradermal injection induced PMNL accumulation in the skin, as measured by a 51Cr-labeled leukocyte assay and which was confirmed histologically. This activity preceded by 30 minutes the massive influx of PMNL into the pleural cavity. 125I-labeled LPS, gel filtration chromatography, limulus amebocyte lysate assays, and polymyxin B allowed distinction between reactions in the skin attributable to LPS and reactions due to the effect of this "PMNL infiltration-inducing activity." Pleural macrophages cultured for 3 to 6 hours with 3 to 30 ng/ml of LPS also released factors which induced PMNL infiltration into the skin. Sephadex G-100 chromatography of LPS-induced pleural exudate fluid or of supernatants from LPS-stimulated macrophage cultures yielded identical elution profiles, with one major peak of PMNL infiltration-inducing activity at an apparent molecular weight of 45,000 and a minor peak at 14,000 to 18,000. Only the low molecular weight fraction contained interleukin 1 activity. Lipid A was required for the secretion of these factors by macrophages. The LPS shed by killed E. coli also induced macrophage production of PMNL infiltration-inducing activity. The activity was sensitive to pronase, and its production was inhibited by an inhibitor of protein synthesis (cycloheximide). The active factors did not induce PMNL chemotaxis, aggregation, or chemiluminescence in vitro indicating that the activity was not C5a. We conclude that PMNL infiltration induced by LPS and perhaps by Gram-negative bacteria, may be mediated in part by the secretion from tissue macrophages of factors which can recruit PMNLs from the blood. The most active of these (approximately equal to 45,000 daltons) lacks interleukin-1 or PMNL chemotactic activity.

Presence of cytochrome b-245 in NADPH oxidase preparations from human neutrophils.

The composition of NADPH oxidase purified by Red Sepharose chromatography of extracts from human neutrophil membranes was investigated. In contrast to that was recently reported by others, the enzyme isolated according to this procedure contained a high concentration of cytochrome b-245 and little FAD. The results reinforce the belief that cytochrome b-245 is a major component of the NADPH oxidase and plays a fundamental role in the formation of O2-by neutrophils.