Purification of permeability factors mediating increased vascular response in cutaneous Arthus-type inflammation

Postlaminectomy adhesion of the cauda equina. Changes of postoperative vascular permeability of the equina in rats

STUDY DESIGN

The authors evaluated the vascular permeability changes of the cauda equina after lumbar laminectomy in rats.

OBJECTIVES

To clarify the early vascular responses in postlaminectomy adhesive arachnoiditis.

SUMMARY OF BACKGROUND DATA

Laminectomy-induced cauda equina adhesion has been visualized by postoperative serial magnetic resonance imaging in humans. In laminectomized rats, fibrinous exudation was apparent among the adhered cauda equina. To date, there has been no report of substantial changes in vascular permeability in the cauda equina after lumbar laminectomy.

METHODS

Wistar rats laminectomized from L5-L6 were used for four studies; 1) Evans blue albumin tracer study; 2) horseradish peroxidase tracer study; 3) lanthanum tracer study; and 4) fluoroscein isothiocyanate-dextran (molecular weights: 20K, 70K, and 150K) tracer study. Untreated rats were used as controls.

RESULTS

1) In the laminectomized (L5-L6) area, the cauda equina tended to conglomerate from 3 hours after surgery; this was relatively resolved by 6 weeks. Extravascular leakage of Evans blue albumin in the cauda equina appeared at 3 hours after surgery and reached a plateau at 24 hours; it mostly disappeared by 6 weeks. At 24 hours after surgery, the extent of Evans blue albumin extravasation was seen in one or more levels adjacent to the laminectomized area. Evans blue albumin leakage and cauda equina adhesion started to appear in nearly a same phase after laminectomy, followed by a plateau of vascular permeability facilitating complete cauda equina adhesion by 24 hours after surgery. The restoration of Evans blue albumin leakage was noted 1 week after surgery, and tended to precede recovery of the cauda equina adhesion; 2) in the laminectomy group, Horseradish peroxidase penetrated from the lumen to the extracellular space beyond the basal laminae of the endothelial cells. Numerous horseradish peroxidase-labeled vesicles in the endothelial cells were found; 3) There was a significant increase in lanthanum distribution in the endothelial cytoplasm at the laminectomized levels. Lanthanum filled the interendothelial clefts beyond the tight junction, but did not penetrate through the perivascular basal laminae; 4) Fluoroscein isothiocyanate-dextran (20K, 70K, 150K) permeability increased in the laminectomy group, but there was no difference in extravasation of fluoroscein isothiocyanate-dextran, irrespective of the molecular weight.

CONCLUSION

Laminectomy consistently induced an increase in vascular permeability in the cauda equina, an increase of vesicular transport in the endothelial cell, and opening of the tight junction early after laminectomy, suggesting breakdown of the blood nerve barrier in the cauda equina. The accelerated permeability may enhance cauda equina adhesion.

Purification and characterization of a chymotrypsin-like enzyme (protease-S) in thermally injured rat skin

Protease-S was extracted from thermally injured rat skin, and partially purified by column chromatography using Sephadex G-50, CM-Sephadex (A-50), Sephadex G-75 gel filtration. The optimum pH of this enzyme was 8.6--8.8, and the molecular weight determined by Sephadex G-75 gel filtration was approximately 30 000. This enzyme is active on the N-acetyl-L-tyrosine ethyl ester, N-succinyl-L-phenylalanine-p-nitroanilide (of chymotrypsin substrate) but not N-tosyl-L-arginine methyl ester, N-benzoyl-L-arginine-p-nitroanilide. Also, protease-S was completely inhibited by diisopropylfluorophosphate (1 mM) or phenylmethylsulfonylfluoride (10 micrometer), and N-tosyl-L-phenylalanine chloromethylketone (1 mM). These results are very similar to those obtained with bovine chymotrypsin. But the enzyme is not identical with the chymotrypsin-like proteases in mast cells and leukocyte granules. When proteases-S was measured during the inflammatory reaction in vivo, maximal activity was found after 8 h, at the end of inflammation.

A protease-like permeability factor in the guinea pig skin. 1. Partial purification and characterization

A permeability factor was extracted in a latent form from guinea pig skin and separated by ammonium sulfate fractionation into the pseudoglobulin fraction (30--50% saturation). The activation of the latent form of the permeability factor seemed to be caused in the desalting step by gel filtration with Sephadex G-50. The factor was partially purified by streptomycin treatment and column chromatography using hydroxyapatite, diethylaminoethyl cellulose and Sephadex G-75, in this order. Gel filtration showed that its molecular weight was approx. 35000. Its permeability activity was heat stable at 61 degrees C for 60 min at neutral pH, resistant at pH 5--10 and at ionic strengths from deionized water to 1 M NaCl at 4 degrees C. Its activity was transient and suppressed by guinea pig serum, but insensitive to an anti-histamic agent (triprolidine). Furthermore, its permeability activity was inhibited by diisopropylfluorophosphate, soybean trypsin inhibitor and leupeptin, and completely adsorbed by soybean trypsin inhibitor affinity column. These findings suggested that the permeability factor was a serine-type protease.

Characterization of a chemotactic factor (leucoegresin) for polymorphonuclear leucocytes from thermal skin site

A chemotactic factor for PMN leucocytes was extracted in the pseudoglobulin fraction of burned skin lesions in rabbits and then highly purified by chromatography using Sephadex G-50, DEAE-Sephadex A-50 and CM-Sephex C-50 in this order. Chemotactic activity was estimated by a modification of Boyden's method during the process of purification. This factor was a protein free of nucleic acid and its molecular weight was approximately 140000 when measured by gel filtration. Its activity was relatively heat-stable. Agar immunoelectrophoresis and immunodiffusion using goat antiserum against rabbit serum and against rabbit IgG revealed that this factor shared at least some antigenic determinants with rabbit IgG. Intradermal injection of this factor induced pronounced PMN leucocyte emigration at the site of venules, but did not increase vascular permeability. These observations reasonably confirmed that this factor was indistinguishable from leucoegresin isolated from active Arthus site in rabbits; and it was called burn leucoegresin. The amount of burn leucoegresin, obtained from one burned site showing maximal PMN leucocyte emigration, was smaller than that of Arthus leucoegresin from one active Arthus site showing maximal PMN leucocyte emigration, in accordance with less pronounced PMN leucocyte emigration in burn site.

Endothelial contraction induced by histamine-type mediators: an electron microscopic study

Previous work has shown that endogenous chemical mediators, of which histamine is the prototype, increase the permeability of blood vessels by causing gaps to appear between endothelial cells. In the present paper, morphologic and statistical evidence is presented, to suggest that endothelial cells contract under the influence of mediators, and that this contraction causes the formation of intercellular gaps. Histamine, serotonin, and bradykinin were injected subcutaneously into the scrotum of the rat, and the vessels of the underlying cremaster muscle were examined by electron microscopy. To eliminate the vascular collapse induced by routine fixation, in one series of animals (including controls) the root of the cremaster was constricted for 2-4 min prior to sacrifice, and the tissues were fixed under conditions of mild venous congestion. Electron micrographs were taken of 599 nuclei from the endothelium of small blood vessels representing the various experimental situations. Nuclear deformations were classified into four types of increasing tightness (notches, foldsl closing folds, and pinches. In the latter the apposed surfaces of the nuclear membrane are in contact). It was found that: (1) venous congestion tends to straighten the nuclei in al groups; (2) mediators cause a highly significant increase in the number of pinches (P < 0.001), also if the vessels are distended by venous congestion; (3) fixation without venous congestion causes vascular collapse. The degree of endothelial recoil, as measured by nuclear pinches, is very different from that caused by mediators (P < 0.001). (4) Pinched nuclei are more frequent in leaking vessels, and in cells adjacent to gaps (P < 0.001); (5) mediators also induce, in the endothelium, cytoplasmic changes suggestive of contraction, and similar to those of contracted smooth muscle; (6) there is no evidence of pericyte contraction under the conditions tested. Occasional pericytes appeared to receive fine nerve endings. Various hypotheses to explain nuclear pinching are discussed; the only satisfactory explanation is that which requires endothelial contraction.