Nicotine effects on polymorphonuclear cell apoptosis and lipopolysaccharide-induced monocyte functions. A possible role in periodontal disease?

Apoptosis provides a mechanism for clearance of unwanted cells in a variety of situations in which programmed or physiological cell death occurs; but the premature death of defensive cells could promote infection, inflammation and concomitant disease. We detected high values of apoptosis in polymorphonuclear cells (PMN) elicited from crevicular sulci of smokers affected by adult periodontitis. To learn more about the effects of nicotine on the periodontal environment, we studied its ability to modulate the apoptosis of two phagocytic lines, PMN and mononuclear cells, which are continuously recruited from gingival vessels to prevent or control plaque extension. Brief exposure of PMN to nicotine concentrations ranging from 0.01 to 0.3% shortened, in a dose-dependent relationship, the lag culture time required to observe at fluorescent microscopy the morphological traces of apoptosis. These observations were confirmed by specific tools of apoptosis: DNA fragmentation on gel electrophoresis and expression of the apoptosis-signaling receptor Fas/Apo-1. The apoptotic effect excited by nicotine on these first line defensive cells may be an important feature of the pathogenesis of periodontal disease. As for mononuclear leukocytes, nicotine was unable to induce apoptotic modifications on cells observed up to 72 h culture time, but the drug inhibited IL-1beta release and procoagulant activity (PCA) expression. The conflicting role played by these lipopolysaccharide (LPS)-induced monocyte functions in the inflammatory process is a further intrigue in the mechanism by which nicotine compromises the oral health.

Increased macrophage procoagulant activity but normal endothelial thrombomodulin in rabbits fed an atherogenic diet.

We have studied the procoagulant activity (PCA) of blood and spleen mononuclear phagocytes and the thrombomodulin activity of aortic segments in rabbits fed an atherogenic diet for 6 weeks as compared to rabbits fed a standard diet. Blood monocytes expressed negligible basal PCA (i.e., PCA measured immediately after cell isolation) both in treated and control rabbits. PCA induced by endotoxin in vitro was not different in the two groups. In contrast, dietary treatment resulted in a significant increase in the basal PCA of spleen cells (p less than 0.01). Moreover, the latter produced significantly more PCA than control cells (p less than 0.002) in response to endotoxin in vitro. The thrombomodulin activity associated with aortic endothelium was not different in the two groups of animals despite the presence of visible fatty streaks on the aortic endothelium of treated rabbits. When rabbits were given a single injection of endotoxin, spleen mononuclear phagocytes harvested 60 min after the injection from treated animals expressed three times more PCA (p less than 0.01) than did cells from controls. In all instances PCA was identified as tissue factor. Endotoxin injection did not affect the thrombomodulin activity of thoracic aorta from both control and diet groups. It is suggested that dietary fats may cause early functional changes in mononuclear phagocytes that lead to an increased PCA production both in vivo and in vitro. These data may be relevant to an understanding of the role of monocytes-macrophages in the pathogenesis of atherosclerosis.

[Biological effects of the combined action of laser radiation and hematoporphyrin on a strain of Salmonella typhimurium (TA 100)]. / Effetti biologici della azione combinata radiazione laser ed ematoporfirina su un ceppo di Salmonella typhimurium (TA 100).

The AA. have studied biological effects of Laser radiation and Haematoporphyrin (HPD) on Salmonella typhimurium TA 100 strain. Their results do not show a growth of letal effect that they demonstrated on antecedent trials, only dependent from Laser radiation. Nome mutagenetic effect was demonstrated. They think that HPD is not capable of binding or penetrating in bacterial cell owing to complexity of bacterial capsule and wall; therefore HPD can not increase Laser radiation effect, though its photodynamic action.

[Biological effects of laser radiation and methylene blue on a strain of Salmonella typhimurium (TA 100) (II)]. / Effetti biologici della azione radiazione laser e bleu di metilene su un ceppo di Salmonella typhimurium (TA 100)--(NOTA II).

In this second note, the AA. have studied biological effect of laser radiation and methylene blue on Salmonella typhimurium TA 100 strain with greatest susceptibility for mutagenetic agents. Their results show a biological effect of laser radiation, of methylene blue like to those obtained for TA 1538 strain, nevertheless greatest susceptibility of TA 100 strain because carrier of plasmid.

[Biological effects of the combined action of laser radiation and methylene blue on a strain of Salmonella typhimurium (TA 1538) (I)]. / Effetti biologici della azione combinata radiazione laser e bleu di metilene su un ceppo di Salmonella typhimurium (TA 1538)--(NOTA I).

The AA. have studied biological effects of laser radiation and methylene blue (MB) on Salmonella typhimurium TA 1538 strain. Their results show low lethal effect of laser radiation directly proportional to administered dose. This effect is more evident in the only MB treatment. Lethal effect persisted, although non directly proportional with combined treatment laser and MB. Some treatments have not demonstrated mutagenetic effect. A new set of trials they are making on Salmonella typhimurium TA 100 strain with plasmid pK M 101 that give to strain greatest susceptibility for mutagenetic agents.