Yvon Roche

Effects of quinolones on interleukin 1 production in vitro by human monocytes

The new quinoline derivative antibiotics (quinolones), pefloxacin and ciprofloxacin at concentrations higher than 50 micrograms/ml inhibit the PHA response of the human mononuclear leukocytes in vitro. Since monocytes have been shown to be accessory cells for the activation of lymphocytes by mitogens, we investigated the effects of pefloxacin and ciprofloxacin on extracellular interleukin 1 (IL-1) and cell-associated IL-1 from lipopolysaccharide-stimulated human monocytes. Pefloxacin and ciprofloxacin decreased the extracellular IL-1 in a dose-dependent manner, while cell-associated IL-1 was not altered. These effects were observed even after a short period of incubation (1 or 2 h). No inhibitory activity against purified IL-1 or IL-2 could be demonstrated in the dialyzed supernatants from pefloxacin- or ciprofloxacin-treated monocytes. Neither pefloxacin nor ciprofloxacin modified the biological activity of preformed IL-1. The decrease of extracellular IL-1 induced by pefloxacin and ciprofloxacin could, in part, account for the observed decrease in the proliferative response of human mononuclear leukocytes to phytohemagglutinin, as extracellular IL-1 and proliferative response were positively correlated (at various concentrations of pefloxacin and ciprofloxacin). The decrease in extracellular IL-1 was not associated with any alteration in the expression of the HLA-DR antigen on the monocytes membrane. These data suggested that pefloxacin and ciprofloxacin could antagonize IL-1 production and release by lipopolysaccharide-stimulated monocytes. These quinolones could be interesting tools to study the production, processing, transport and release from the monocytes of IL-1.

Synovial chondromatosis of the temporomandibular joint possibly secondary to trauma. A case report.

A histologically confirmed case of synovial chondromatosis of the temporomandibular joint associated with a glenoid fossa callus is described. The lesion appeared 6 years after trauma to the chin. Conservative surgical treatment without excision of the synovial membrane or meniscus but including arthroplasty of both the eminence and the lateral side of the glenoid fossa was successful. The possible role of trauma in the etiology of synovial chondromatosis is discussed.

Enhancement of interleukin 2 production by quinolone-treated human mononuclear leukocytes

Previous studies have shown that lectin-induced human mononuclear leukocyte (MNL) proliferation was influenced by quinoline derivative antibiotics (quinolones), depending on both the dose and the antimicrobial agent used. Since the production of interleukin-2 (IL-2) is known to be involved in the proliferation of immune cells, we investigated the effects of three quinolones: ciprofloxacin (Cip), ofloxacin (Ofl) and pefloxacin (Pef) on IL-2 production in vitro by phytohemagglutinin (PHA)-stimulated human MNL. IL-2 activity in the supernatants of PHA-stimulated MNL was found to be enhanced by quinolones in a dose- and time-dependent manner. Increased IL-2 activity was observed using Cip, Ofl or Pef at therapeutically achievable blood concentrations (5-10 micrograms/ml). Since at these concentrations the PHA-induced proliferative response of MNL was not impaired by quinolones, the increased recovered IL-2 activity was not related to a decreased absorption of IL-2 by activated MNL. At high antibiotic concentrations (25 micrograms/ml), the enhanced IL-2 activity might be related (i) to increased accumulation resulting from the decreased proliferation induced by the quinolones at these concentrations, and (ii) to a true increased IL-2 production by the cells. In fact, an increased IL-2 recovery in presence of quinolones was always observed after blocking the cell cycle by mitomycin C, and was therefore independent of DNA-synthesis. Furthermore, the expression of IL-2 receptors was not modified by Cip, Ofl or Pef. These data show that quinolones increased IL-2 synthesis by MNL and suggest the potential usefulness of these antibiotics, not only as antimicrobial agents, but also as modulators of immune responses.

Antibiotics and Suppression of Lymphocyte Response in Vitro: Protection by Thiol Compounds

Treatment with antibiotics may have a direct effect on both bacterial virulence as well as host defense systems. Indeed several antimicrobial agents are known to affect immunological responses significantly (10). Certain antibiotics can suppress lymphocyte function in vitro (1,6). The present investigation was undertaken to evaluate the effects of two antibiotic families, macrolides and new quinoline carboxylic acid derivatives on mitogen-stimulated human peripheral blood mononuclear leucocyte (MNL) responses. We demonstrated that erythromycin, spiramycin, ciprofloxacin, pefloxacin and ofloxacin suppressed significantly lymphocyte transformation. In a second part, we evaluated the effects of thiol compounds as antioxidant agents, essentially 2-Mercaptoethanol (2-ME) on protection of the depressed immune response induced by high antibiotic concentrations. Our results clearly showed that 2-ME can partially protect the lymphocyte proliferation depressed by these antibiotics.

The use of position screws as an alternative to plating in segmental Le Fort I osteotomies

Abstract The successful correction of dentofacial deformities with orthognathic surgery is dependent in part on effective stabilization of the repositioned bone segments. Stabilization of the Le Fort I osteotomy is often achieved by rigid skeletal fixation using titanium plates. 1–3 These plates are generally placed along the nasal apertures and on the zygomatic buttresses. When segmental maxillary osteotomies are performed, however, plating the anterior segments in the paranasal regions can be difficult, depending on the relationship between the segments. To prevent this difficulty, we have adopted the use of titanium bone screws as an alternative to plating in this region.