Effects of hyaluronidase (HYAL) treatment on bleomycin-induced inflammation in the lung. At day 8 after bleomycin treatment (4 U/kg/0.1 mL NaCl 0.9%) in the lungs of C57Bl/6 mice, animals were treated with intranasal inoculation (i.n.) once with 16 U HYAL or phosphate buffered saline (PBS) and inflammatory cells recovered 96 h after. (A) Neutrophils numbers in the bleomycin-inoculated lung were not altered by HYAL (P = 0.406). However, (B) mononuclear cells were significantly increased by HYAL treatment (P = 0.045). Values represent means ± standard error of mean (SEM).; n = 5, by t test (C) transforming growth factor (TGF)-β is increased by bleomycin but reduced by HYAL treatment. TGF-β was measured in supernatant of lung tissue homogenate by ELISA. Values represent means ± SEM; n = 5, P = 0.0024 compared to bleomycin, P < 0.0001 compared to PBS, by t test. (D) The picrosirius morphometric analysis corresponding to the area occupied by the fibres were determined by digital densitometry recognition and expressed as a percentage of the total area of the field. Values represent means ± SEM; n = 10; P = 0.010 compared to PBS treated, using t test. (E) Acid-soluble collagen in the supernatant of lung tissue homogenate, assayed by Sircol. Values represent means ± SEM; n = 10; P = 0.010 compared to PBS, by t test. (F, G) Photomicrographs of representative lung sections obtained from mice inoculated with bleomycin and treated with PBS or with HYAL. In (F) tissues were stained with haematoxylin and eosin in order to investigate inflammatory cells accumulation and in (G) with Picrosirius to determine the collagen content. The histological analyses were single-blinded. Original magnifications = 100x.