Streptococcus cristatus attenuates Fusobacterium nucleatum-induced cytokine expression by influencing pathways converging on nuclear factor-κB.

We previously reported that Streptococcus cristatus, an oral commensal, was able to downregulate the interleukin-8 (IL-8) response to Fusobacterium nucleatum, a putative oral pathogen in oral epithelial cells. The aim of this study was to extend the understanding of how S. cristatus regulates cytokine expression in oral epithelial cells on a broad basis, and investigate whether the modulation of a Toll-like receptor (TLR) pathway was involved in this process. KB and TERT-2 cells were co-cultured with F. nucleatum and S. cristatus, either alone or in combination. Total RNA was extracted and pathway-specific focused microarrays were used to profile the transcriptional responses of various cytokine genes and those related to TLR-mediated signal transduction. Reverse transcription-polymerase chain reactions (RT-PCR) and protein assays were performed to confirm the microarray results for selected genes. We found that exposure to either S. cristatus or F. nucleatum alone led to distinct changes in cytokine expression patterns. Fusobacterium nucleatum induced a greater number of gene expression changes than S. cristatus (15% vs. 4%, respectively). The presence of S. cristatus with F. nucleatum attenuated the expression of a number of inflammatory cytokines, and upregulated several anti-inflammatory mediators. The RT-PCR confirmed the messenger RNA attenuation of IL-1α, tumor necrosis factor-α and IL-6 by S. cristatus. Profiling of TLR-signaling-related genes revealed that S. cristatus most significantly impacted the downstream pathways, especially nuclear factor-κB, rather than altering TLRs and their adaptors and interacting proteins. Our data suggest that S. cristatus may attenuate the epithelial proinflammatory cytokine response to F. nucleatum by influencing pathways converging on nuclear factor-κB.

Influence of serum on interaction of Porphyromonas gingivalis ATCC 33277 and Aggregatibacter actinomycetemcomitans Y4 with an epithelial cell line.

BACKGROUND AND OBJECTIVE: The purpose of this study was to investigate the influence of serum on the interaction of periodontal pathogens with epithelial cells using an epithelial cell line (KB cells). This is important because serum is a key component of gingival crevicular fluid and may influence inflammatory responses in epithelial cells exposed to periodontal pathogens. MATERIAL AND METHODS: Porphyromonas gingivalis ATCC 33277 and Aggregatibacter actinomycetemcomitans Y4 were co-cultured with KB cells either with or without the addition of up to 10% human serum or 50 mg/mL human serum albumin. The numbers of free-floating, adherent and intracellular bacteria were determined up to 18 h after exposure of the epithelial cells to the pathogens. Additionally, the concentrations of interleukin (IL)-6 and IL-8 produced by the epithelial cells in response to exposure to the bacteria were determined. RESULTS: Serum and human serum albumin reduced the number of internalized A. actinomycetemcomitans Y4 organisms in the epithelial cells, increased the levels of IL-6 and IL-8 in the supernatants of infected cells (those with internalized A. actinomycetemcomitans) and influenced non-infected epithelial cells. Increased IL-6 and IL-8 concentrations were also detected in the supernatants of KB cells infected with P. gingivalis ATCC 33277. Interleukin-6 and IL-8 were detectable after addition of serum, probably as a result of inhibition of the activity of P. gingivalis cysteine proteinases by serum. CONCLUSION: Serum promotes the release of the cytokines IL-6 and IL-8 by epithelial cells. This mechanism is influenced by periodontal pathogens and may maintain clinical periodontal inflammation.

Porphyromonas gingivalis survives within KB cells and modulates inflammatory response.

BACKGROUND/AIMS: The purpose of the study was to investigate the intracellular survival of Porphyromonas gingivalis as a possible mechanism for maintaining periodontitis. METHODS: P. gingivalis strains, the strain ATCC 33277 and seven clinical isolates, were co-cultured with KB cells. The number of intracellular bacteria was determined up to 3 days after infection. In addition, the numbers of KB cells per well, the concentrations of the cytokines interleukin-1beta (IL-1beta), IL-6, IL-8 and tumour necrosis factor-alpha (TNF-alpha) and the arginine-specific amidolytic activity were measured. The 16S rRNA of P. gingivalis and the mRNA expression of IL-1beta, IL-6, IL-8, TNF-alpha and rgpA were also determined. RESULTS: All the P. gingivalis strains studied were able to survive within KB cells. In contrast to the reduced values of colony-forming units at day 3, equal and higher levels of 16S rRNA were seen in comparison to day 0. Arginine-specific amidolytic activity declined in all samples during infection. Expression of mRNA for rgpA was not found after infection of KB cells by P. gingivalis strains. IL-8 was detectable in all samples 2 days after infection with P. gingivalis strains. Principal components analysis underlined a correlation between the arginine-specific amidolytic activity 1 h after infection and both the released IL-8 and the mRNA expression of IL-8. Associations were found between the cultivable numbers of intracellular P. gingivalis and the mRNAs of IL-1, IL-6 and TNF-alpha at the day of infection. CONCLUSION: The results indicate survival of P. gingivalis within epithelial cells, possibly in a non-cultivable stage. Invasion into cells modulates the virulence properties of P. gingivalis as well as the inflammatory response of the cells.

Stress-activated protein kinase/Jun N-terminal kinase is required for interleukin (IL)-1-induced IL-6 and IL-8 gene expression in the human epidermal carcinoma cell line KB.

The cytokine interleukin-1 (IL-1) is a major inflammatory hormone which activates a broad range of genes during inflammation. The signaling mechanisms triggered by IL-1 include activation of several distinct protein kinase systems. The stress-activated protein kinase (SAPK), also termed Jun N-terminal kinase (JNK), is activated particularly strongly by the cytokine. In an attempt to delineate its role in activation of gene expression by IL-1, we inhibited the IL-1-induced SAPK/JNK activity by stable overexpression of either a catalytically inactive mutant of SAPKbeta (SAPKbeta(K-R)) or antisense RNA to SAPKbeta in human epidermal carcinoma cells. A detailed analysis of signal transduction in those cells showed that activation of neither NFkappaB nor p38 mitogen-activated protein kinase was affected, suggesting that we achieved specific blockade of the SAPK/JNK. In untransfected and vector-transfected KB cells, IL-1 induced a strong increase in expression of IL-6 and IL-8 mRNA, along with the synthesis of high amounts of the proteins. In two KB cell clones stably overexpressing the mutant SAPKbeta(K-R), and three clones stably overexpressing antisense RNA to SAPKbeta, expression of IL-6 and IL-8 in response to IL-1 was strongly reduced at both the mRNA and protein level. These data indicate that the SAPK/JNK pathway provides an indispensable signal for IL-1-induced expression of IL-6 and IL-8.

Opposing effects of ultraviolet B irradiation on interleukin-1 receptor antagonist and interleukin-1 alpha messenger RNA expression in a human epidermoid carcinoma cell line.

Interleukin-1 receptor antagonist (IL-1RA) is a cytokine that acts to antagonize IL-1 activity without agonist function. The expression of IL-1RA has been reported in many cell types, including the keratinocyte that covers the outer most part of the skin. However the modulation of IL-1RA by ultraviolet B (UVB), which is the most biologically active UV, has not been reported yet. We therefore selected a keratinocyte cell line with a cytokine-producing profile similar to that of keratinocytes and tested the effect of UVB on its ability to produce IL-1RA mRNA. IL-1RA mRNA was constitutively expressed in the cell line and began to be suppressed by 3 h after the UVB irradiation with 100 mJ/cm2. The level of IL-1RA expression became lowest by 16 h after the irradiation with 100 mJ/cm2. Simultaneously, IL-1 alpha mRNA started to increase by 1 h and peaked by 3-16 h after the irradiation with 10-100 mJ/cm2. The differential expression of IL-1 alpha and IL-1RA mRNA following exposure to a high dose (100 mJ/cm2) of UVB may markedly potentiate the role of IL-1 in UV-induced inflammation.

Relationship between cellular glutathione level and susceptibility to LAK killing in human pharyngeal carcinoma cell line.

We examined the relationship between cellular glutathione (GSH) level and susceptibility to lymphokine-activated killer (LAK) cell-mediated cytolysis in KB human pharyngeal carcinoma cells. Treatment of KB cells with D,L-buthionine-S,R-sulfoximine (BSO), a gamma-glutamyl cysteine synthetase blocker, resulted in decreased total intracellular GSH levels associated with increased susceptibility to LAK killing. In contrast, treatment with oxothiazolidine-4-carboxylate (OTZ, a precursor of cysteine), which is known to increase cellular GSH level, decreased the susceptibility of KB cells to LAK killing. Both agents had no effects on binding frequency of KB cells to LAK cells. These results suggest that intracellular GSH in tumor cells play a protective role against LAK mediated cytolysis, specially in the post-binding killing phase.

Characterization of a new monoclonal antibody F4 detecting cell surface epitope and P-glycoprotein in drug-resistant human tumor cell lines.

Using viable adriamycin resistant human ovarian carcinoma cells 2780AD and colchicine resistant human oral epidermoid carcinoma cells KB-24 as the immunogen in primary and subsequent i.p. immunizations, followed by i.v. boostings with crude plasma membranes of 2780AD, KB-24, Chinese hamster lung cells resistant to vincristine DC-3F/VCRd-5L, and resistant to daunorubicin DC-3F/DMXX, we have generated a new murine monoclonal antibody (McAb), designated F4, of IgG1 isotype. McAb F4 reacted strongly with a cell surface epitope of drug resistant cells and insignificantly with their drug sensitive counterparts. Cell surface localization of F4 epitope was determined by immunofluorescence and laser scanning confocal imaging system. Results obtained from immunoprecipitation and immunoblot analyses using F4 and mdr1 P-glycoprotein specific McAb JSB-1 demonstrated the reactivity of P-glycoprotein with F4. These results along with those obtained from competitive binding-inhibition, chemical modification, and enzyme hydrolysis, revealed that McAb F4 detects an extracellular epitope of P-glycoprotein, and is different from other major McAbs directed against P-glycoprotein, e.g. C219, MRK16, JSB-1, HYB-241 and C494. Deduced from the putative structure of mdr1 protein and its orientation in cell membrane, it is proposed that F4 epitope is localized in or near the 3rd, and/or 6th extracellular transmembrane loops of P-glycoprotein.

[Establishing three dimensional tumors in vitro and the reaction of the lymphokine-activated killer cells (LAK) to the three dimensional tumors]. / Etablierung dreidimensionaler Tumoren in vitro und Wirkung von lymphokin-aktivierten Killer (LAK)-Zellen auf die dreidimensionalen Tumoren.

In this study, we attempted to develop a technique, by which three-dimensional tumors were produced from two cultured head and neck tumor cell lines (Hep2, KB) and a colon adenocarcinoma cell line (HT29) using fibrinogen, thrombin, and double layered agar system. The three-dimensional tumor was large enough to perform the histologic study, which showed no significant histologic difference in comparison with the histologic findings of the xenografted tumor on nude mice. Furthermore, we applied this assay model to evaluate the antitumor effect of lymphokine activated killer (LAK) cells on the three-dimensional tumor produced by the technique. When tumor cells were cocultured with LAK cells, the damage of the three-dimensional structure due to the degeneration of tumor cells was observed. These findings suggest that the three-dimensional tumor may be useful to evaluate the antitumor effect of LAK cells in term of head and neck solid tumors.

KB cells for antinuclear antibody determination: comparison with HEp-2 cells and the Crithidia luciliae assay.

Fifty-seven sera from 53 patients were assayed simultaneously on KB and HEp-2 cells and compared with regard to pattern and titer. Additionally, KB cell fluorescent antinuclear antibody (FANA) titer and pattern in 310 sera from 194 patients were compared with regard to the presence of antinative DNA antibodies (anti-nDNA ab) as determined by the Crithidia luciliae assay. Sixty-five percent (37/57) of the sera had the same titer on both KB and HEp-2 cells; the remainder had higher titers using KB cells. Regression analysis yielded a highly significant, unbiased correlation between the substrates. Forty-four percent (25/57) of these sera gave identical patterns on both substrates, another 25 of the 57 sera (44%) gave different patterns on the two substrates and 12% (7/57) could not be compared because they were negative on HEp-2 cells. KB cells detected positive FANA in 30 of 30 (100%) diagnosed cases of systemic lupus erythematosus; HEp-2 cells detected 29/30 (97%). From the standpoint of sensitivity, these data indicate a slight advantage to the use of KB over HEp-2 cells. Seventeen percent (53/310) of the sera were positive for anti-nDNA ab. The highest percentage of these positive sera occurs at reciprocal FANA titers between 320 and 1280. No association was found between KB FANA patterns and a positive Crithidia luciliae assay.