Both smoking and asthma are associated with inflammatory changes in the lung, which may be suppressed with the help of exogenous anti-inflammatory drugs or by the endogenous defense system. Lipocortin-1 (LC-1; annexin-1) is an anti-inflammatory protein present in respiratory tract secretions. We report an inverse correlation between extracellular LC-1 concentration and the bronchoconstrictor prostaglandin (PG) D2 [n = 15, Spearman rank correlation coefficient (rS) = -0.597, P < 0.05] in bronchoalveolar lavage fluid (BALF) from allergic asthmatic patients, together with positive correlations between extracellular LC-1 per milliliter BALF and the prostacyclin (PGI2) metabolite 6-keto-PGF1 alpha (n = 15, rS = 0.480, P < 0.05) and between LC-1 per milliliter BALF and concentration of histamine causing a 20% decrease in forced expired volume in 1 s (n = 15, rS = 0.720, P < 0.01) in these subjects. We found no significant difference between the LC-1 concentration in BALF from nonsmoking asthmatic patients who were receiving inhaled glucocorticoid therapy (2 x 100 micrograms beclomethasone 4 times/day for 2.5 yr; median 186 ng LC-1/mg albumin; n = 6) and those who were not (median 126 ng LC-1/mg albumin; n = 12), perhaps because inhaled drugs deposit predominantly in central airways, which are poorly represented in bronchoalveolar lavage. Both asthmatic and healthy volunteers who smoked had higher levels of LC-1 in their BALF than did their nonsmoking counterparts (e.g., asthmatic smokers, median 317 ng LC-1/mg albumin, n = 10; asthmatic nonsmokers, median 162 ng LC-1/mg albumin, n = 18; P < 0.05), perhaps because smokers' lungs contain more alveolar macrophages, cells that release LC-1. We observed a positive correlation between BALF LC-1 and bronchoalveolar lavage cell number (n = 16, rS = 0.821, P < 0.001). Increased extracellular LC-1 may be part of a protective response of the lung to inflammatory insult. Regulation of prostanoid levels might be one mechanism by which LC-1 suppresses inflammation.
The role of platelet activating factor (PAF) in endotoxic shock was investigated in anaesthetized pigs receiving 5 micrograms/kg E. coli endotoxin (LPS) into the superior mesenteric artery over a 60 min period. Concentrations of PAF and tumor necrosis factor (TNF) were measured in blood obtained from the superior mesenteric vein and aorta before, during and 60 min after the LPS infusion. The effect of 4 mg/kg of BN 52021, a PAF receptor antagonist, given as a bolus injection 5 min prior to LPS infusion and/or PAF administration into the superior mesenteric vein was studied on systemic and regional hemodynamic variables. Eight of the 17 animals infused with LPS died within 30 min after start of LPS, while the other 9 survived the experimental period of 3 h, though in a shock state. In survivors, PAF concentration in both superior mesenteric vein and aorta increased twenty-fold at 30 min of endotoxaemia, but rapidly returned back towards normal values. No changes in PAF release, but a marked rise in TNF production were measured in non-survivors. Exogenous administration of PAF (0.01 micrograms/kg) produced similar hemodynamic effects as observed in survivors. BN 52021 markedly reduced the effects of PAF on arterial blood pressure for over 1 h. Treatment with BN 52021 (4 mg/kg), injected 5 min prior to LPS infusion, failed to exert any effect on the surviving rate. However, in survivors all circulatory and laboratory parameters studied were improved after treatment with BN 52021. PAF release observed during LPS infusion in survivors may play a role in the development of shock; however, its role in the rapid death seems to be negligible. Present results clearly demonstrate that endotoxin shock is not crucially dependent on one class of mediators.
We developed an in vitro organ bath method to measure permeability and contractility simultaneously in murine intestinal segments. To investigate whether permeability and contractility are correlated and influenced by mucosal damage owing to inflammation, BALB/c mice were exposed to a 10% dextran sulphate sodium (DSS) solution for 8 days to induce colitis. The effect of pharmacologically induced smooth muscle relaxation and contraction on permeability was tested in vitro. Regional permeability differences were observed in both control and 10% DSS-treated mice. Distal colon segments were less permeable to 3H-mannitol and 14C-PEG 400 molecules compared with proximal colon and ileum. Intestinal permeability in control vs. 10% DSS mice was not altered, although histologic inflammation score and IFN-gamma pro-inflammatory cytokine levels were significantly increased in proximal and distal colon. IL-1beta levels were enhanced in these proximal and distal segments, but not significantly different from controls. Any effect of pharmacologically induced contractility on intestinal permeability could not be observed. In conclusion, intestinal permeability and contractility are not correlated in this model of experimentally induced colitis in mice. Although simultaneous measurement in a physiological set-up is possible, this method has to be further validated.
