Anti-inflammatory properties and expression in selected organs of canine interleukin-1ß splice variant 1.

The IL-1ß gene can be also be spliced with the intron 4 retention; the result is a IL-1ß splice variant 1 (IL-1ßsv1), which was significantly up-regulated in failing myocardium of dogs suffering from chronic degenerative valvular disease (CDVD). Expression of IL-1ßsv1 was assessed, at both RNA and protein levels, in organs affected by heart failure, namely, kidneys, liver, and lungs from 35 dogs suffering chronic degenerative valvular disease (CDVD) and in 20 disease free control dogs. IL-1ßsv1 RNA was detected in the dogs from both groups. In the CDVD group, the highest RNA and protein IL-1ßsv1 levels were observed in lungs, followed, in that order, by the liver and kidneys. IL-1ßsv1 protein was found in the cytoplasm of hepatocytes and IL-1ßsv1-overexpressing DH82 cells. In lungs, IL-1ßsv1 was localized in the cytoplasm and in the nuclei of bronchiolar epithelial and smooth-muscle cells. Cytoplasmic and nuclear IL-1ßsv1 expression was observed in macrophages, and a strong nuclear signal was detected in epithelial cells of the alveolar sacs. Following lipopolysaccharide (LPS) stimulation, overexpression of IL-1ßsv1 in DH82 cells decreased the pro-inflammatory response. Our results indicate that IL-1ßsv1 is constitutively expressed in both normal tissues and in tissues from cases of heart failure. The presence of IL-1ßsv1 in tissues exposed to invading agents and its anti-inflammatory activity in DH82 cells may point to its immunomodulatory role in vivo.

Matrix metalloproteinase 9/neutrophil gelatinase associated lipocalin/tissue inhibitor of metalloproteinasess type 1 complexes are localized within cardiomyocytes and serve as a reservoir of active metalloproteinase in porcine female myocardium.

Matrix metalloproteinase 9 (MMP-9) is crucial for physiological tissue repair and pathophysiological myocardial remodeling. The regulation of its functioning has been shown to be mediated by formation of complexes with tissue inhibitor of metalloproteinases 1 (TIMP-1) and neutrophil gelatinase associated lipocalin (NGAL). We investigated the mRNA and protein expression of MMP-9, TIMP-1 and NGAL, the formation of complexes, their gelatinolytic activity and cellular localization in left ventricle (LV) from 10 female pigs with induced systolic heart failure (HF), 5 control pigs, and a woman with severe HF. The MMP-9, TIMP-1 and NGAL mRNA in LV did not differ between diseased and healthy pigs. In all pigs MMP-9, TIMP-1 and NGAL proteins were present in LV as high molecular weight (HMW) complexes (115, 130, 170 and 220 kDa), and no monomers were found. A 80 and 115 kDa gelatinolytically active bands were present in all LV homogenates. A 130-kDa active band was seen only in LV from pigs with severe HF. Similar results were found in the explanted heart of a female patient with severe HF. The incubation of the homogenates of porcine LV at 37°C resulted in appearance of 88 kDa active band, which was accompanied by a decreased intensity of HMW bands. The incubation of the homogenates of porcine LV (depleted of active MMP-9) with trypsin generated 80 and 115 kDa active bands. Immunohistochemistry revealed the presence of MMP-9 in the cytoplasm of porcine cardiomyocytes, but not in cardiofibroblasts. Our data suggest that MMP-9 originates from cardiomyocytes, forms the gelatinolytically inactive complexes with TIMP-1 and NGAL, present in normal and failing myocardium, likely serving as a reservoir of active MMP-9. Further studies are needed to elucidate the role of these HMW complexes in the extracellular matrix remodeling during the progression of HF, which presence should be considered when developing efficient strategies inhibiting myocardial matrix metalloproteinases.