Hyaluronan (HA) blocks inhaled porcine pancreatic elastase-induced bronchoconstriction in sheep with airway hypersensitivity to Ascaris suum antigen. Since elastases from other species may display different catalytic properties compared to the human enzyme, we tested the efficacy of HA on human neutrophil elastase (HNE)-induced airway responses. We measured pulmonary resistance in allergic sheep before and after inhalation of HNE alone and after pretreatment with a 150 kD-HA (LKDHA; 3 and 15 mg), or a 300 kD-HA (HKDHA; 6, 7.5, and 15 mg). HKDHA (3 mg) was given either 0.5, 4, or 8 h before HNE challenge; LKDHA (15 mg) and HKDHA (6, 7.5, and 15 mg) were given 8 h before challenge. HNE caused an acute bronchoconstriction which was blocked by 3 mg LKDHA given 0.5 or 4 h before challenge. LKDHA (3 mg) given 8 h before challenge was ineffective, but protection was achieved by increasing the dose to 15 mg. When HKDHA at 6, 7.5, and 15 mg was given 8 h before challenge a dose-dependent inhibition of the HNE-induced airway response was observed. We conclude that HA inhibits HNE-induced airway responses and that within the range of 150-300 kD, dose rather than molecular weight may be the most important determinant of pretreatment time resulting in a protective effect.
"A decreased concentration of HA and its major transmembrane glycoprotein receptor, CD44, has been shown to increase unwanted human neutrophil elastase activity (32–34) and also to promote leukocyte extravasation and formation of pro-inflammatory cytokines (35,36). In the present study, the concentration of HA in plasma was increased 90 min after thrombin infusion, at which time liver blood flow and cardiac output were decreased. "
[Show abstract][Hide abstract] ABSTRACT: Hyaluronan (HA) is a component of the extracellular matrix in lung tissue and is normally present at low concentrations in blood. HA is rapidly cleared from blood by the liver. Increased concentrations of plasma HA have been found in patients with acute respiratory distress syndrome (ARDS). We investigated changes in HA levels in plasma, bronchoalveolar lavage fluid (BALF), and lung, and their relationship to pretreatment with a leukocyte elastase inhibitor in a rat model of ARDS.
Rats were randomly assigned to three groups: control, thrombin, and thrombin plus elastase inhibitor. By use of a radiometric assay, HA was measured in lungs, BALF, and plasma. Tissue samples from the lungs were stained for HA and examined microscopically. Liver circulation and cardiac output were monitored using radiolabeled microspheres.
Infusion of thrombin produced a pronounced increase in wet weight to dry weight ratio, and relative lung water content. This increase was blunted by a leukocyte elastase inhibitor. A decrease in lung HA and increases in both BALF and plasma HA were found. The leukocyte elastase inhibitor counteracted not only the decrease in lung tissue HA, but also the increase in plasma HA. Histologically, there was decreased HA-staining of peribronchial and perivascular areas in the injured rat lung. Decreased liver perfusion was observed after infusion of thrombin.
The decrease in lung HA may be involved in the development of pulmonary edema in this ARDS model, and leukocyte elastase may be one cause of this decrease. In addition, an elevated plasma HA level may be an indicator of lung injury.
Upsala journal of medical sciences 03/2012; 117(1):1-9. DOI:10.3109/03009734.2011.622812 · 1.98 Impact Factor
"While our laboratory has concentrated on the use of HA to treat emphysematous lung injury, other investigators have demonstrated a beneficial effect of this agent in animal models of airway hyperreactivity. When aerosolized HA was given to sheep, it significantly reduced bonchoconstriction due to inhalation of either neutrophil or pancreatic elastase (Scuri et al 2001; Scuri and Abraham 2003). In both cases, increasing the molecular weight of HA enhanced its effectiveness. "
[Show abstract][Hide abstract] ABSTRACT: Hyaluronan (HA), a long-chain polysaccharide, is currently being evaluated as a potential therapeutic agent for a number of inflammatory disorders. The effect of HA on inflammation appears to be related to its molecular size, with larger polysaccharide chains having anti-inflammatory activity and smaller ones having proinflammatory properties. This dichotomous behavior is particularly relevant to the work of our laboratory on an aerosolized preparation of HA to treat pulmonary emphysema. The breakdown of inhaled HA into smaller fragments could possibly induce an inflammatory reaction in the lung that counteracts any beneficial effect. Consequently, the proposed therapeutic use of HA will require development of treatment strategies aimed at minimizing its proinflammatory activity.
International Journal of COPD 02/2007; 2(3):283-8. · 3.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bronchial tissue kallikrein is the major kininogenase activity in the airways of asthmatic subjects. The relationship of IgE-mediated events to its release and/or activation is unknown, however, and is the subject of this report. Seven subjects with mild atopic asthma underwent endobronchial challenge with relevant aeroallergen. Baseline pre-allergen lavage and sequential post-challenge lavages were collected over an approximate 10-minute time course. Individual aliquots were analyzed separately and compared with saline control lavages performed in a separate lobe. In five of the seven subjects, an increase in tissue kallikrein activity, measured by cleavage of the synthetic substrate Val-Leu-Arg-pNA, was identified in the post-challenge lavages. The antigenic identity of the enzymatic activity was confirmed as a tissue kallikrein in each case by immunoblotting. Tissue kallikrein activity was highly correlated with the appearance of immunoreactive histamine and kinin (p = 0.0001). High molecular weight kininogen influx and cleavage was detected in the post-challenge samples by immunoblotting and paralleled the detection of kinin in BAL fluid. Two of the subjects, despite clinical profiles similar to those of the five positive responders, failed to react to endobronchial challenge. Saline control lavages contained detectable kallikrein, kinin, and histamine in two subjects; in each case, however, this was significantly less than in the post-allergen samples. The results demonstrate a close association between immediate type hypersensitivity events in the lower airway and the appearance of active kallikrein, kininogen substrate, and the liberation of kinin.
The American review of respiratory disease 05/1992; 145(4 Pt 1):900-5. DOI:10.1164/ajrccm/145.4_Pt_1.900 · 10.19 Impact Factor
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