Effects of smoking on the ex vivo cytokine production in periodontitis.

BACKGROUND AND OBJECTIVE: Smoking is associated with increased severity of periodontitis. The underlying mechanisms of this phenomenon are not well understood. The purpose of the present study was to compare the monocyte-derived T cell directing (Th1/Th2) response and pro-inflammatory cytokine production in ex vivo whole blood cell cultures (WBCC) of smoking and non-smoking chronic periodontitis patients. MATERIAL AND METHODS: Venous blood was collected from 29 periodontitis patients (18 non-smokers and 11 smokers) receiving supportive periodontal treatment, and diluted 10-fold for WBCC. The WBCC were stimulated for 18 h with Neisseria meningitidis lipo-oligosaccharide (LOS) or Porphyromonas gingivalis sonic extract (Pg-SE). The production of the T cell directing cytokines interleukin (IL)-12 p40 and IL-10, as well as the pro-inflammatory cytokines IL-1beta, IL-6 and IL-8, was measured in the culture supernatants. RESULTS: After LOS stimulation of WBCC, smokers showed a lower IL-12 p40/IL-10 ratio than non-smokers (P < 0.05). Interleukin-1beta production was significantly lower in smokers compared with non-smokers after stimulation with either LOS or Pg-SE (P < 0.05). Interleukin-6 and IL-8 production was similar in WBCC from both smokers and non-smokers, for both LOS and Pg-SE. CONCLUSION: A more pronounced Th2 response in smoking periodontitis patients may be related to increased severity of the disease.

Activation of toll-like receptors 2 and 4 by gram-negative periodontal bacteria.

BACKGROUND/AIMS: Periodontitis is a chronic infectious disease associated with a gram-negative subgingival microflora. Bacterial components stimulate, among other receptors, Toll-like receptor (TLR) 2 and/or TLR4. Accumulating evidence indicates that both qualitatively and quantitatively distinct immune responses result from the triggering of TLR2 as compared to TLR4 triggering. The aim was to study the interaction of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Tannerella forsythensis, Prevotella intermedia, Prevotella nigrescens, Fusobacterium nucleatum and Veillonella parvula with TLR2 and TLR4. We investigated all known serotypes (K(-), K1-K6) of P. gingivalis and A. actinomycetemcomitans serotype a-e strains for their potency to stimulate cytokine production. METHODS: Human embryonic kidney (HEK) cells, stably transfected with CD14, CD14-TLR2, or CD14-TLR4 and whole blood were stimulated with bacterial sonicates. Cytokine production (interleukin-6, -8, -10 and -12) was measured in the supernatant by enzyme-linked immunosorbent assay. RESULTS: All test bacteria stimulated HEK-CD14-TLR2, but only A. actinomycetemcomitans and V. parvula stimulated HEK-CD14-TLR4. No differences were found in the activation of HEK-CD14-TLR2/4, or cytokine production in whole blood between serotypes of P. gingivalis and A. actinomycetemcomitans. CONCLUSION: Gram-negative periodontal bacteria predominantly stimulated TLR2, which may be of importance for the Th1/Th2 cell orientation of the immune response in periodontitis.

Peripheral and central regulation of IL-6 gene expression in endotoxin-treated rats.

The distribution of IL-6 mRNA in the rat brain was studied by in situ hybridization using 35S-labelled oligonucleotides. The mRNA encoding IL-6 was found in hippocampus, hypothalamus, cerebellum as well as in other brain areas. Microscopic analyses revealed both neuronal and glial cell localization of the mRNA. Subsequently, Northern blot analyses were performed with RNA isolated from spleen, adrenals, pituitary gland, hypothalamus, hippocampus and cerebellum of rats injected intraperitoneally with a non toxic dose of LPS. A rapid induction of the IL-6 mRNA was observed in the peripheral organs, whereas no change in IL-6 transcripts could be measured in the brain. It is concluded that the local synthesis and release of IL-6 in pituitary and adrenal gland might be involved in the activation of the HPA axis following an endotoxin challenge.

Effect of various centrally acting drugs on the efflux of dopamine metabolites from the rat brain.

The influence of chlorpromazine, haloperidol, morphine, chloral hydrate, gamma-butyrolactone, probenecid, kainic acid, oxotremorine, pargyline, yohimbine, (+)-amphetamine, and cocaine on the efflux rate of 3,4-dihydroxyphenylacetic acid (DOPAC) from four brain areas was studied. All drugs studied except pargyline and morphine had an effect on the transport of DOPAC and homovanillic acid (HVA) from the brain. Nine drugs inhibited the efflux of DOPAC and HVA, whereas (+)-amphetamine stimulated this transport. These data suggest that most centrally acting drugs can interfere with the elimination of 3,4-dihydroxyphenylethylamine (DA or dopamine) metabolites from the brain. These effects are heterogeneously distributed throughout the brain and are probably related to indirect nonspecific drug effects. This implies that drug-induced changes in DA metabolite concentrations, especially when these changes are slight to moderate, cannot directly be translated to changes in the production rate of these metabolites. By studying five control groups, we concluded that formation and transport of DOPAC are not synchronized in the various brain areas.