The influence of nanoporous anodic aluminum oxide on the initial adhesion of Streptococcus mitis and mutans.

The use of nanoscale surface modifications offers a possibility to regulate the bacterial adherence behavior. The aim of this study was to evaluate the influence of nanoporous anodic aluminum oxide of different pore diameters on the bacterial species Streptococcus mitis and Streptococcus mutans. Nanoporous anodic aluminum oxide (AAO) surfaces with an average pore diameter of 15 and 40 nm, polished pure titanium and compact aluminum oxide (alumina) samples as reference material were investigated. S. mitis and mutans were evaluated for initial adhesion and viability after an incubation period of 30 and 120 min. After 30 min a significantly reduced growth of S. mitis and mutans on 15 nm samples compared to specimens with 40 nm pore diameter, alumina and titanium surfaces could be observed (p < .001). Even after 120 min incubation there was a significant difference between the surfaces with 15 nm pore diameter and the remaining samples (p < .001). AAO surfaces with a small pore diameter have an inhibitory effect on the initial adhesion of S. mitis and mutans. The use of such pore dimensions in the area of the implant shoulder represents a possibility to reduce the adhesion behavior of these bacterial species.

The anti-inflammatory effect of low-dose radiation therapy involves a diminished CCL20 chemokine expression and granulocyte/endothelial cell adhesion.

BACKGROUND AND PURPOSE: Low-dose radiotherapy (LD-RT) is known to exert an anti-inflammatory effect, however, the underlying molecular mechanisms are not fully understood. The manipulation of polymorphonuclear neutrophil (PMN) function and/or recruitment may be one mechanism. Chemokines contribute to this process by creating a chemotactic gradient and by activating integrins. This study aimed to characterize the effect of LD-RT on CCL20 chemokine production and PMN/endothelial cell (EC) adhesion. MATERIAL AND METHODS: The EC line EA.hy.926 was irradiated with doses ranging from 0 to 3 Gy and was co-cultured with PMNs from healthy donors either by direct cell contact or separated by transwell membrane chambers. CXCL8, CCL18, CCL20 chemokine and tumor necrosis factor-(TNF-)alpha cytokine levels in supernatants were determined by ELISA and adhesion assays were performed. The functional impact of the cytokines transforming growth factor-(TGF-)beta(1) and TNF-alpha and of the intercellular adhesion molecule-(ICAM-)1 on CCL20 expression was analyzed by using neutralizing antibodies. RESULTS: As compared to CXCL8 and CCL18, CCL20 chemokine secretion was found to be exclusively induced by a direct cell-cell contact between PMNs and EA.hy.926 ECs in a TNF-alpha-dependent, but ICAM-1-independent manner. Furthermore, irradiation with doses between 0.5 and 1 Gy resulted in a significant reduction of CCL20 release which was dependent on TGF-beta(1) (p < 0.01). The decrease of CCL20 paralleled with a significant reduction in PMN/EA.hy.926 EC adhesion (p < 0.001). CONCLUSION: The modulation of CCL20 chemokine expression and PMN/EC adhesion adds a further facet to the plethora of mechanisms contributing to the anti-inflammatory efficacy of LD-RT.

Expression and regulation of CCL18 in synovial fluid neutrophils of patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is characterized by the recruitment of leukocytes and the accumulation of inflammatory mediators within the synovial compartment. Release of the chemokine CCL18 has been widely attributed to antigen-presenting cells, including macrophages and dendritic cells. This study investigates the production of CCL18 in polymorphonuclear neutrophils (PMN), the predominant cell type recruited into synovial fluid (SF). Microarray analysis, semiquantitative and quantitative reverse transcriptase polymerase chain reaction identified SF PMN from patients with RA as a novel source for CCL18 in diseased joints. Highly upregulated expression of other chemokine genes was observed for CCL3, CXCL8 and CXCL10, whereas CCL21 was downregulated. The chemokine receptor genes were differentially expressed, with upregulation of CXCR4, CCRL2 and CCR5 and downregulation of CXCR1 and CXCR2. In cell culture experiments, expression of CCL18 mRNA in blood PMN was induced by tumor necrosis factor alpha, whereas synthesis of CCL18 protein required additional stimulation with a combination of IL-10 and vitamin D3. In comparison, recruited SF PMN from patients with RA were sensitized for CCL18 production, because IL-10 alone was sufficient to induce CCL18 release. These results suggest a release of the T cell-attracting CCL18 by PMN when recruited to diseased joints. However, its production is tightly regulated at the levels of mRNA expression and protein synthesis.

Extravasation into synovial tissue induces CCL20 mRNA expression in polymorphonuclear neutrophils of patients with rheumatoid arthritis.

OBJECTIVE: Examination of expression of the chemokine macrophage inflammatory protein-3a (CCL20/Mip-3alpha) in blood polymorphonuclear neutrophils (PMN) and synovial fluid (SF) PMN of patients with rheumatoid arthritis (RA). METHODS: Paired samples of blood PMN and SF PMN were obtained from 11 patients with RA. In addition, SF was prepared from 9 patients with osteoarthritis (OA) and 10 patients with juvenile idiopathic arthritis (JIA). PMN were isolated via density centrifugation to a purity of 98%. Total RNA was isolated and the expression of CCL20 was determined by reverse transcription-polymerase chain reaction (RT-PCR) and quantitative real-time PCR. In some experiments blood PMN obtained from healthy donors were stimulated with individual SF of patients with RA. For quantitative considerations, CXCL8, CCL20, interleukin 1, and tumor necrosis factor-alpha (TNF-alpha) levels were determined in SF by ELISA. RESULTS: In SF of RA patients CCL20 and CXCL8 levels were elevated, up to 7.5 ng/ml and 23.6 ng/ml, respectively. No significant level of either chemokine was found in SF of patients with JIA and OA. CCL20 mRNA was undetectable in blood PMN of all patients with RA. In SF PMN, CCL20 mRNA was found in 6/11 RA patients. Expression of CCL20 mRNA in 5/6 SF PMN samples was observed in the absence of detectable TNF-alpha levels in SF. Cell culture experiments, however, confirmed the ability of TNF-alpha in SF to induce CCL20 mRNA expression in blood PMN. Notably, expression of CCL20 was also found in PMN after stimulation with SF lacking TNF-alpha. CONCLUSION: Recruitment of PMN to the synovial microenvironment induces expression of CCL20 mRNA independent of the concentrations of TNF-alpha accumulating in SF of patients with RA.

The induction of TGF-beta(1) and NF-kappaB parallels a biphasic time course of leukocyte/endothelial cell adhesion following low-dose X-irradiation.

BACKGROUND AND PURPOSE: Low-dose radiotherapy (LD-RT) is known to exert an anti-inflammatory effect, but the knowledge of the underlying molecular mechanisms is still scarce. The authors have recently reported that transforming growth factor beta 1 (TGF-beta(1)) essentially contributes to a reduced endothelial adhesion of mononuclear cells (PBMC) following LD-RT. Furthermore, TGF-beta(1) secretion was associated with the induction of the transcription factor nuclear factor kappa B (NF-kappaB). However, the time course of adhesion, TGF-beta(1) expression, and NF-kappaB activity following LD-RT has not been thoroughly investigated yet. MATERIAL AND METHODS: The human EA.hy.926 endothelial cell line (EA.hy.926 EC) was grown to 95% confluence. Immediately after stimulation with the pro-inflammatory cytokine tumor necrosis factor alpha (TNF-alpha), EA.hy.926 EC were irradiated with single doses ranging from 0.3 up to 3 Gy. Adhesion assays were performed 4, 12, and 24 h after irradiation. Nuclear extracts and culture supernatants were harvested after 4, 8, 12, 20, 24, 30, and 40 h. NF-kappaB DNA-binding activity was analyzed by electrophoretic mobility shift assays (EMSA) and TGF-beta(1) secretion by enzyme-linked immunosorbent assay (ELISA). The functional impact of TGF-beta(1) on the course of leukocyte/EC adhesion was analyzed by neutralizing TGF-beta(1) in parallel with stimulation/irradiation of the EA.hy.926 EC. RESULTS: 4 and 24 h after irradiation of EA.hy.926 EC in the dose range between 0.3 and 0.7 Gy, a reduced adhesion of PBMC compared to nontreated controls could be observed. However, 12 h after irradiation a relative maximum of adhesion (up to 30% increase) was seen at a dose of 0.3 Gy. TGF-beta(1) secretion and NF-kappaB DNA-binding activity displayed a similar biphasic kinetics of induction with a relative minimum 12 h after irradiation. Neutralization of TGF-beta(1) activity restored adhesion at 4 and 24 h after LD-RT of EA.hy.926 EC, but it did not influence leukocyte adhesion 12 h after irradiation. CONCLUSION: LD-RT of stimulated human EA.hy.926 EC is followed by a biphasic time course of NF-kappaB activity and an increased secretion of TGF-beta(1). The kinetics shows peak levels at 4-8 h and 24-30 h after LD-RT and results in a biphasic leukocyte/EC adhesion profile.