Glucose, K⁺, and Albumin Concentrations in the Alveolar Milieu of Normal Humans and Pulmonary Sarcoidosis Patients

Abstract

Some properties of the alveolar epithelial barrier during transalveolar transport of water and solutes were studied in normal humans and patients with sarcoidosis by means of the transalveolar capillary concentration gradients of various solutes. A total of 9 normal control subjects (Group A) and 60 sarcoidosis patients, 52 with an evolving disease (Group B) and 8 recovered (Group C), underwent bronchoalveolar lavage (BAL). The second aliquot of fluid was used to measure urea, glucose, potassium, and albumin, which were also investigated in plasma. Urea was used to determine the volume of alveolar epithelial lining fluid (AELF volume). Results are expressed as the ratio of solute concentration in AELF over that in plasma (A/P ratio). In Group A there were clear concentration gradients of glucose, potassium, and albumin between the AELF and plasma, as the A/P ratios of glucose, potassium, and albumin were 0.02 +/- 0.006 (mean +/- SEM), 3.2 +/- 0.34, and 0.04 +/- 0.008, respectively. In Group B the A/P ratios of glucose (0.21 +/- 0.02, p less than 0.001) and albumin (0.17 +/- 0.02, p less than 0.001) were significantly increased but that of potassium remained unchanged (2.9 +/- 0.2). The A/P ratios of these various solutes were independent of chest x-ray typing. The albumin but not the glucose A/P ratio was correlated with the percentage of lymphocytes recovered from BAL (p less than 0.02); however, there was no correlation between the albumin A/P ratio and the CD4+/CD8+ T lymphocyte ratio. In group C there was a striking contrast between the albumin A/P ratio, which was normal, and the glucose A/P ratio, which was clearly elevated despite a normal lymphocyte count.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum Clara cell protein (CC16), a marker of the integrity of the air-blood barrier in sarcoidosis

“…However, the presence of nonselective leaks or a transcellular transport, even if very unlikely, cannot be completely ruled out [43]. As previously reported, it was found that the modifications of albumin in BALF were well correlated with the intensity of the alveolitis [4,5,8]. An even better correlation with the percentage of lymphocytes in BALF was found for CC16 in serum.…”

“…These cells may damage the pulmonary tissue, in particular the alveolar-capillary barrier, leading to a decrease of the lung function and/or a loss of the gas-exchange capacity. Another consequence of the alteration of the air-blood barrier integrity is its increased permeability to solutes and proteins [3,4] which is commonly estimated by the elevation of plasma proteins such as albumin in bronchoalveolar lavage fluid (BALF) [4][5][6][7][8][9][10].…”

Phagocytosis of unopsonized Pseudomonas aeruginosa by murine macrophages is a two-step process requiring glucose.

“…Bronchial fluid has diminishingly low levels ofglucose present under normal conditions (6). The predilection of P. aeruginosa for lower airway disease in patients with cystic fibrosis might be explained in part by the unique dependency upon glucose for MO-mediated ingestion of this particular bacterial species.…”

“…These studies used "mature" M4s and demonstrated that the receptor for unopsonized P. aeruginosa is absolutely dependent upon glucose for ingestion in distinction to the other better characterized phagocytic receptors. Glucose is present in diminishingly low concentrations in bronchial fluid (6). The propensity of P. aeruginosa to cause pulmonary infections in patients with cystic fibrosis might be explained by this unique dependency upon glucose for MO-mediated ingestion.…”

Proteomic Analysis of Bronchoalveolar Lavage Fluid Obtained from Rats Exposed to Formaldehyde

“…Several lung inflammatory conditions may accumulate and activate immune and inflammatory cells, which may damage the pulmonary tissue, in particular the alveolarcapillary barrier, leading to its dysfunction and to an increase in its permeability to solutes and plasma proteins. 37,38) Another down-regulated protein, PLUNC, is a small and secreted protein, which is expressed in the oropharynx and upper airways of humans, mice, and rats. 39,40) Secreted PLUNC has been detected in bronchial mucus and nasal secretions, and is up-regulated after irritation of the airway.…”