Combination of midazolam and a cyclooxygenase-2 inhibitor inhibits lipopolysaccharide-induced interleukin-6 production in human peripheral blood mononuclear cells

Dexmedetomidine inhibits LPS-induced inflammatory responses through peroxisome proliferator-activated receptor gamma (PPARγ) activation following binding to α2 adrenoceptors

Over the past decade, dexmedetomidine (DEX) has been found to possess an anti-inflammatory effect. However, the local anti-inflammatory mechanism of DEX has not been fully clarified. Some intracellular inflammatory pathways lead to negative feedback during the inflammatory process. The cyclooxygenase (COX) cascade synthesizes prostaglandins (PGs) and plays a key role in inflammation, but is known to also have anti-inflammatory properties through an alternative route of a PGD₂ metabolite, 15-deoxy-delta-12,14-prostaglandin J₂ (15d-PGJ₂), and its receptor, peroxisome proliferator-activated receptor gamma (PPARγ). Therefore, we hypothesized that DEX inhibits LPS-induced inflammatory responses through 15d-PGJ₂ and/or PPARγ activation, and evaluated the effects of DEX on these responses. The RAW264.7 mouse macrophage-like cells were pre-incubated with DEX, followed by the addition of LPS to induce inflammatory responses. Concentrations of TNFα, IL-6, PGE₂, and 15d-PGJ₂ in the supernatants of the cells were measured, and gene expressions of PPARγ and COX-2 were evaluated in the cells. Furthermore, we evaluated whether a selective α₂ adrenoceptor antagonist, yohimbine or a selective PPARγ antagonist, T0070907, reversed the effects of DEX on the LPS-induced inflammatory responses. DEX inhibited LPS-induced TNFα, IL-6, and PGE₂ productions and COX-2 mRNA expression, and the effects of DEX were reversed by yohimbine. On the other hand, DEX significantly increased 15d-PGJ₂ production and PPARγ mRNA expression, and yohimbine reversed these DEX's effects. Furthermore, T0070907 reversed the anti-inflammatory effects of DEX on TNFα and IL-6 productions in the cells. These results suggest that DEX inhibits LPS-induced inflammatory responses through PPARγ activation following binding to α₂ adrenoceptors.

Possible immunosuppressive effects of drug exposure and environmental and nutritional effects on infection and vaccination

A variety of drugs which are not primarily considered to be immunosuppressive agents have been described to modulate the humoral and cellular immune response in humans or animals. Thereby they may have an influence on the effectiveness and possible side effects of vaccines. This mini review lists some of the different substance classes and also some of endogeneous, infectious, nutritional, and environmental influences with suspected capability to interfere with immunizations. Studies in most cases focused on substances with known immunosuppressive functions, but there is growing evidence for immunomodulatory effects also of commonly used drugs with wide distribution. In particular combinations of those antiproliferative and antiphlogistic side effects of different substance classes have not been studied in detail but may substantially interfere with the development of a functional humoral and cellular immune response. The drugs of importance include antipyretics, anticoagulants, tranquilizers, and substances influencing lipid metabolism but also commonly used drugs of abuse like alcohol or cannabinoids. Additional substances of environmental, nutritional, or microbiological origin may also play a role but their combinatory/synergistic effects have been disregarded so far due to the lack of systematic data and the complex study designs necessary to elucidate those complex epidemiologic questions.