Inhibition of tumor necrosis factor-alpha-induced RANTES secretion by alkaline protease in A549 cells

Bergamot (Citrus bergamia Risso) fruit extracts and identified components alter expression of interleukin 8 gene in cystic fibrosis bronchial epithelial cell lines

Background

Cystic fibrosis (CF) airway pathology is a fatal, autosomal, recessive genetic disease characterized by extensive lung inflammation. After induction by TNF-α, elevated concentrations of several pro-inflammatory cytokines (i.e. IL-6, IL-1β) and chemokines (i.e. IL-8) are released from airway epithelial cells. In order to reduce the excessive inflammatory response in the airways of CF patients, new therapies have been developed and in this respect, medicinal plant extracts have been studied. In this article we have investigated the possible use of bergamot extracts (Citrus bergamia Risso) and their identified components to alter the expression of IL-8 associated with the cystic fibrosis airway pathology.

Methods

The extracts were chemically characterized by ¹H-NMR (nuclear magnetic resonance), GC-FID (gas chromatography-flame ionization detector), GC-MS (gas chromatography-mass spectrometry) and HPLC (high pressure liquid chromatography). Both bergamot extracts and main detected chemical constituents were assayed for their biological activity measuring (a) cytokines and chemokines in culture supernatants released from cystic fibrosis IB3-1 cells treated with TNF-α by Bio-Plex cytokine assay; (b) accumulation of IL-8 mRNA by real-time PCR.

Results

The extracts obtained from bergamot (Citrus bergamia Risso) epicarps contain components displaying an inhibitory activity on IL-8. Particularly, the most active molecules were bergapten and citropten. These effects have been confirmed by analyzing mRNA levels and protein release in the CF cellular models IB3-1 and CuFi-1 induced with TNF-α or exposed to heat-inactivated Pseudomonas aeruginosa.

Conclusions

These obtained results clearly indicate that bergapten and citropten are strong inhibitors of IL-8 expression and could be proposed for further studies to verify possible anti-inflammatory properties to reduce lung inflammation in CF patients.

Characterization of TNF receptor subtype expression and signaling on pulmonary endothelial cells in mice

TNF plays a crucial role in the pathogenesis of acute lung injury. However, the expression profile of its two receptors, p55 and p75, on pulmonary endothelium and their influence on TNF signaling during lung microvascular inflammation remain uncertain. Using flow cytometry, we characterized the expression profile of TNF receptors on the surface of freshly harvested pulmonary endothelial cells (PECs) from mice and found expression of both receptors with dominance of p55. To investigate the impact of stimulating individual TNF receptors, we treated wild-type and TNF receptor knockout mice with intravenous TNF and determined surface expression of adhesion molecules (E-selectin, VCAM-1, ICAM-1) on PECs by flow cytometry. TNF-induced upregulation of all adhesion molecules was substantially attenuated by absence of p55, whereas lack of p75 had a similar but smaller effect that varied between adhesion molecules. Selective blockade of individual TNF receptors by specific antibodies in wild-type primary PEC culture confirmed that the in vivo findings were due to direct effects of TNF receptor inhibition on endothelium and not other cells (e.g., circulating leukocytes). Finally, we found that PEC surface expression of p55 dramatically decreased in the early stages of endotoxemia following intravenous LPS, while no change in p75 expression was detected. These data demonstrate a crucial in vivo role of p55 and an auxiliary role of p75 in TNF-mediated adhesion molecule upregulation on PECs. It is possible that the importance of the individual receptors varies at different stages of pulmonary microvascular inflammation following changes in their relative expression.

Immunohistochemical study of matrix metalloproteinases-2 and -9, macrophage inflammatory protein-2 and tissue inhibitors of matrix metalloproteinases-1 and -2 in normal, purulonecrotic and fungal infected equine corneas

OBJECTIVE

Determine the effects of matrix metalloproteinases (MMPs)-2, -9, macrophage inflammatory protein-2 (MIP-2), tissue inhibitors of matrix metalloproteinase (TIMP)-1 and -2 by immunohistochemical expression in fungal affected and purulonecrotic corneas.

PROCEDURE

Paraffin-embedded equine corneal samples; normal (n = 9), fungal affected (FA; n = 26), and purulonecrotic without fungi (PN; n = 41) were evaluated immunohistochemically for MMP-2, -9, MIP-2, TIMP-1 and -2. The number of immunoreactive inflammatory cells was counted and statistics analyzed. Western blot was performed to detect MMP-2, MMP-9, TIMP-1 and TIMP-2 proteins.

RESULTS

Matrix metalloproteinases-2, -9, MIP-2, TIMP-1 and -2 immunoreactivity was identified in corneal epithelium of normal corneas, and in corneal epithelium, inflammatory cells, keratocytes, and vascular endothelial cells of both FA and PN samples. Inflammatory cell immunoreactivity was significantly higher in FA and PN samples than in the normal corneas. There was positive correlation between MMP-2 and MIP-2, MMP-9 and MIP-2, and MMP-9 and TIMP-1 in inflammatory cell immunoreactivity in FA samples. There was positive correlation between MMP-9 and MIP-2, MMP-9 and TIMP-2, MIP-2 and TIMP-1, and MIP-2 and TIMP-2 in inflammatory cell immunoreactivity in PN samples. Western blot confirmed the presence of all four proteins in equine corneal samples.

CONCLUSION

Increased immunoreactivity of MMP-2 and -9 in FA and PN samples is indirectly related to MIP-2 through its role in neutrophil chemo-attraction. Tissue inhibitors of matrix metalloproteinase-1 and TIMP-2 are up-regulated in equine purulonecrotic and fungal keratitis secondary to MMP-2 and MMP-9 expression. The correlation between MMPs -2 and -9, MIP-2, TIMPs -1 and -2 suggests that these proteins play a specific role in the pathogenesis of equine fungal keratitis.

Interaction of a novel form of Pseudomonas aeruginosa alkaline protease (aeruginolysin) with interleukin-6 and interleukin-8

Pseudomonas aeruginosa secretes several proteases considered as important virulence factors. In this report we present data indicating that two key proinflammatory cytokines, interleukin-6 (IL-6) and IL-8, are substrates for pseudolysin (elastase) and aeruginolysin (alkaline protease). While IL-6 was totally digested by both proteases, a long form of IL-8 (IL-8-77) was first rapidly processed into a 72-residue form with enhanced chemokine activity, then very slowly degraded. Interestingly, aeruginolysin bearing two additional residues at the N-terminus (Leu-Lys-aeruginolysin) in the absence of calcium degraded both IL-6 and IL-8-72 far more efficiently than the shorter form of the enzyme.