Objective: Macroscopically, tissue hydration in nasal polyps seems to be a phenomenon of unknown etiology. As the macromolecular composition of extracellular matrix (ECM) determines to a large extent tissue hydration, which in turn determines tissue volume, we investigated ECM components in nasal polyps (NP) in comparison to nasal mucosa of the inferior turbinate (TM) and sinus mucosa from patients with chronic sinusitis without polyps (CS).
Material and methods: The following parameters were determined: (i) the dry weight of freeze-dried NP, TM and CS; (ii) the total protein content (Bio-Rad Protein Assay) of the tissue; (iii) the quality of proteins, using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE); (iv) the amount of albumin, using nephelometry; and (v) the amount of hyaluronic acid, using a chemical method: deaminative hydrolysis with carbazole.
Results: In 20 NP we found a significantly elevated total protein content compared to TM (n = 20) and CS (n = 15), referred to 0.1 g dry of tissue. In SDS-PAGE of NP (n = 20) a protein band at approximately 70 kDa, representing albumin, dominated, in comparison to TM. The amount of albumin was significantly increased in NP compared to CS and TM. In contrast, the amount of the glycosaminoglycan, hyaluronic acid, was not elevated in NP or CS.
Conclusion: Albumin was significantly increased in NP and CS, possibly as a result of inflammatory plasma exudation mechanisms. Hyaluronic acid seems to play no role in the tissue hydration of NP.