[Trypsin-induced leukostasis: granulocyte migration in airspaces]. / Leucostase induite à la trypsine: migration de granulocytes dans les espaces aériens.

Injection of trypsin triggers the delayed appearance of a lung emphysema. Classically, emphysema is attributed to elastase, more particularly to leucocyte elastase. Indeed the acute phase of this experiment is characterized by a granulocyte sequestration within the lung microvessels in diverse species. We also found granulocytes within the terminal airspaces; this fact implies a granulocyte extravasation and directed migration. In order to evaluate this airspace invading by granulocytes during trypsin induced-vascular leucostasis, we washed the lung in cats since this species develop leucocytosis easily. One lobe only was washed for avoiding to harvest the cells present in the trachea and the main bronchi. This study was designed in several parts: (1) the lungs were washed in normal condition and several months later when trypsin was given; (2) in a kinetic experiment, 3 lavages were made consecutively a day either in normal condition or under trypsin treatment; (3) the lung was washed one day after trypsin administration. The granulocytes, and among them the neutrophils particularly, increased in number or in percentage transiently within the terminal airspaces under trypsin treatment; these granulocytes found within the airspaces are about 20% of the lung granulocytes.

The trypsin-induced leucostasis which leads to emphysema in the hamster is not due to contaminating endotoxins.

Intravenous injection of trypsin in the rat induces early lung leucostasis and emphysema of delayed onset. This report confirms that this emphysema is not rat-specific and that the leucostasis is not related to the presence of contaminating endotoxin in the trypsin. In hamsters (n = 37), leucostasis did not occur when they were injected with heat-treated trypsin, but numerous granulocytes were sequestered in the vessels of hamsters receiving a fresh solution of trypsin. In these hamsters, the number of granulocytes harvested by lavage increased significantly (1.87 x 10(6) per ml, P < 0.001) compared with hamsters injected with either heat-denatured trypsin (0.89) or saline (0.86), or compared with controls (0.86). Emphysema was inconstantly observed in hamsters 6 or 12 weeks after injection with trypsin for 1 h. It was frequently (17/20) present and always (20/20) well developed (intercept + 180 per cent) in the 2-h perfused hamsters whose lungs were abnormally heterogeneous (index + 100 per cent) relative to the seven controls and to the nine saline-injected hamsters. The efficiency of trypsin in triggering emphysema (percentage of hamsters having abnormal values of intercept) was dependent on the time of perfusion. This form of experimental emphysema is thus considered to be due to an endotoxin-independent leucostasis.

Parenteral administration of trypsin triggers lung emphysema.

Eight weeks after a single intravenous injection of trypsin, more than half of 26 treated rats showed pulmonary emphysema, as demonstrated by a significant increase of the mean linear intercept (MLI = 107 microns) in comparison with 11 controls (69 +/- 15 microns) (mean +/- SD). As observed 56 days after the injection, the intraperitoneal administration of trypsin (24 rats) also leads to lung emphysema (MLI = 101-106 microns), as does endotracheal instillation of elastase (13 rats), (MLI = 108 microns). The intraperitoneal administration of trypsin in animals constitutes a model close to human pathology with which lung alterations in acute pancreatitis may be studied. Having no elastolytic properties, trypsin cannot directly induce emphysema. The observation of a pulmonary leucostasis in eight rats sacrificed early after the trypsin injection suggested that leucocyte trapping and activation are important for the genesis of this trypsin-triggered emphysema.

Experimental emphysema following one intravenous infusion of trypsin.

This study was undertaken to investigate the effects of a deficit in protease inhibitor (AT) induced by intravenously administered trypsin on the development of elastase-induced emphysema. Rats receiving a perfusion of trypsin (4.5 mg/kg body wt) intravenously (TIV rats) or one instillation of elastase (92 IU/subject) into the trachea (ELAS rats) were compared with rats receiving both trypsin and elastase (TIVELAS rats). Compared with 8 sham-injected rats, the serum AT activity of 14 TIV rats decreased slightly (5.5%) 150 min after the beginning of the perfusion. In six other TIV rats sacrificed early after the perfusion, a granulocyte sequestration with edema and vascular thrombi demonstrated early lung injury. Anatomical studies of lung and determination of the mean linear intercept (MLI) were carried out 56 days after the administration of the enzymes. Emphysema was confirmed by a significant (P less than .001) MLI increase (about 150 microns) in 22/24 TIV, 20/21 ELAS, and 21/21 TIVELAS rats in comparison with 40 control rats (78 microns). These similar results of the treated rats show that trypsin did not worsen elastase-induced emphysema and also indicate that trypsin given intravenously alone induces emphysema as does elastase when introduced into the airways. The AT activity decrease consequent to proteolysis by trypsin and pulmonary leucostasis may contribute to this trypsin-triggered emphysema.

[Quantimetry and lung heterogeneity in hamsters (Mesocricetus auratus) treated with endotracheal or intrapleural infusion of elastase. Individual and contralateral variations]. / Quantimétrie et hétérogénéité pulmonaires du hamster (Mesocricetus auratus) traité à l'élastase par voie aérienne ou intrapleurale. Variations individuelles et controlatérales.

Intrapleural administration of elastase was found to induce pulmonary emphysema identical to that seen after an endotracheal instillation of elastase in 33% of cats and 14% of rats given the treatment [15]. This experiment was repeated using hamsters, a species extremely sensitive to elastolytic factors reaching the lung via the airways. Linear intercept measurements (Lm) demonstrated no evidence of emphysema or alveolar dilatation four weeks after an intrapleural infusion of elastase, whereas quantified lung heterogeneity reached 40%, i.e., twice the control value; 17% of treated hamsters exhibited a statistically significant increase in heterogeneity of the right or left lung. These findings suggest that occurrence of alveolar dilatation after administration of a protease is dependent on access of the enzyme to the lung; if the enzyme fails to access the lung, abnormal lung heterogeneity may develop: this anomaly reflects a strong statistical likelihood of a disease state with or without concomitant emphysema, as was found in other species under identical conditions.

[Experimental emphysema following intravenous injection of trypsin]. / Emphysème expérimental consécutif à une injection intraveineuse de trypsine.

The injection of trypsin provokes a decrease of the circulating antiproteases. Its effect on an elastase-induced emphysema is negligible. Paradoxically, emphysema is quantitatively demonstrated in rats treated with trypsin alone: an influx of polymorphonuclear leucocytes into the lung is observed during the acute phase of experiment.

[Pulmonary emphysema induced by elastase: influence of the dose and effect of added collagenase]. / Emphysème pulmonaire induit à l'élastase: influence de la dose et incidence d'une collagénase ajoutée.

The endotracheal deposition of pancreatic porcine elastase (EPP) at 40 u X kg-1 body weight provokes a typical pulmonary emphysema (alveoli disruption) in rats. This emphysema is significant (p less than 0.001) when quantitatively compared to a placebo (100% increase of the mean linear intercept, ILM). The EPP-treated lungs are very heterogeneous and the size of the alveoli vary as much as 30% versus 19% in controls. The emphysema is more effective at a 80 u X kg-1 dose and the individual disparities are reduced (dose effect). When bacterial collagenase (200 u X kg-1 body weight) is added to EPP, the pulmonary abnormalities (disruptions, ILM) are in no way increased (no enzymatic synergy, repair by collagenesis?). In contrast, alveolar dilation is slightly reduced 8 weeks after enzyme administration (p less than 0.05): EPP is not altered in vitro by collagenase and despite several hypothesis, the moderating effect of collagenase in vivo still remains unexplained. This result suggests that the joint presence of several proteases is not necessarily an aggravating factor in the etiopathogenesis of emphysema.