murabutide and Shock--Septic

Certain immunopharmacological activities of muramyl peptides have been associated with inflammatory and undesirable side-effects typically observed following the administration of the prototype molecule muramyl dipeptide. This activity is now demonstrated not to be linked to a direct activation of inflammatory processes in endothelial cells. Neither MDP nor other structural derivatives were able to induce inflammatory cytokines release or E-selectin gene expression in cultured human umbilical vein endothelial cells. However, oral administration of muramyl peptides has been reported to induce certain biological effects, including the downregulation of anamnestic, antigen-specific IgE responses, which are not observed following parenteral administration. We elaborate on these findings and extend them to show the efficacy of a new muramyl peptide in suppressing polyclonally induced serum IgE levels in anti-IgD-treated mice. The comparative effects of muramyl peptides, selected for clinical development, on the induction of cytokines in human whole blood are then presented at the level of mRNA accumulation and protein secretion. Moreover, the cytokine profile induced in vitro and in vivo by the combination of the safe immunostimulant, Murabutide, with interferon-alpha is examined. This combination reveals a selective and beneficial synergistic activity and induces anti-inflammatory cytokines in the absence of synergistic toxicity. The potential and the implications for the use of a therapeutic combination of an immunostimulant with a cytokine are discussed.

Topics: Acetylmuramyl-Alanyl-Isoglutamine; Adjuvants, Immunologic; Animals; Cell Adhesion Molecules; Cells, Cultured; E-Selectin; Endothelium; Female; Humans; Inflammation; Interferon-alpha; Male; Mice; Receptors, Cytokine; Shock, Septic

Pretreatment of animals with the adjuvant muramyl dipeptide enhances both the production of circulating tumor necrosis factor and the sensitivity to the lethal effect of a lipopolysaccharide (LPS) challenge. The present study examined the capacity of various adjuvant muramyl dipeptide derivatives to potentiate responsiveness to LPS administration. Cytokine levels in serum were determined at various time intervals after LPS administration by bioassays and immunoassays; the cytokines examined were tumor necrosis factor, interleukin-1, interleukin-6, and gamma interferon. The time course of cytokine response was not modified by the pretreatment, but most of the levels were strongly enhanced. However, of the four compounds which were found to be potent priming agents, only two caused an increased sensitivity to LPS lethality, showing that elevated titers of cytokines in serum were not correlated with host sensitization. Interestingly, previous studies have shown that these two compounds also display neurobiological properties, implying a possible role of the central nervous system in LPS lethality. However, two hydrophilic derivatives with low activity as priming agents were capable of decreasing the toxicity of LPS when given after the challenge in galactosamine-sensitized mice. These results illustrate the diversity of responses elicited by immunological priming. They raise unanswered questions on the importance of endogenous mediators in the pathophysiological alterations during toxic shock.

Topics: Acetylmuramyl-Alanyl-Isoglutamine; Animals; Cytokines; Drug Synergism; Female; Galactosamine; Interferon-gamma; Interleukin-1; Interleukin-6; Lipopolysaccharides; Mice; Mice, Inbred C3H; Shock, Septic; Triglycerides; Tumor Necrosis Factor-alpha