Recently, it was demonstrated that gamma-cyclodextrins (gamma-CDs) greatly accelerates transfer of hydrophobic pyrene-labeled and other fluorescent phospholipid derivatives from vesicles to cells in culture (). To understand better the characteristics of this process, we studied the interaction of gamma-CD with pyrene-labeled phosphatidylcholines (PyrPCs) using a variety of physical methods. Either one or both of the acyl chains of PC was labeled with a pyrene moiety (monoPyrPCs and diPyrPCs, respectively), and the length of the labeled chain(s) varied from 4 to 14 carbons. Fluorescent binding assays showed that the association constant decreases strongly with increasing acyl chain length. PyrPC/gamma-CD stoichiometry was 1:2 for the shorter chain species, but changed to 1:3 when the acyl chain length exceeded 8 (diPyrPCs) or 10 (monoPyrPCs) carbons. The activation energy for the formation of diPyr(10)PC/gamma-CD complex was high, i.e., +92 kJ/mol, indicating that the phospholipid molecule has to fully emerge from the bilayer before complex formation can take place. The free energy, enthalpy, and entropy of transfer of monoPyrPC from bilayer to gamma-CD complex were close to zero. The absorption, Fourier transform infrared, and fluorescence spectral measurements and lifetime analysis indicated that the pyrene moiety lies inside the CD cavity and is conformationally restricted, particularly when the labeled chain is short. The acyl chains of a PyrPC molecule seem to share a CD cavity rather than occupy different ones. The present data provide strong evidence that the ability of gamma-CD to enhance intermembrane transfer of pyrene-labeled phospholipids is based on the formation of stoichiometric complexes in the aqueous phase. This information should help in designing CD derivatives that are more efficient lipid carriers then those available at present.

Endotoxins, classical activators of innate immune cells, induce systemic inflammation designated by increased microvascular permeability, and, not so infrequently, circulatory shock, organ dysfunction, and death. Vascular endothelial growth factor (VEGF), besides being an endothelial‐cell mitogen, is a strong vascular permeability factor. This study demonstrates that peripheral blood mononuclear cells (PBMNCs) from healthy volunteers cultured in serum‐free medium in the absence of any stimulus release VEGF continuously into culture media. Physiological endotoxin concentrations stimulate this VEGF secretion in a dose‐dependent manner, representing an induction of de novo VEGF production, as an induction of the expression of the major 3.7‐kb VEGF mRNA transcripts was observed, and the release of VEGF was blocked by cycloheximide. Reverse transcription‐polymerase chain reaction also verified the expression of the four VEGF transcripts. Interferon‐α, a modulator of the immune system and an inhibitor of angiogenesis, inhibited VEGF release dose dependently. We conclude that endotoxin promotes VEGF production in PBMNCs. Circulating and emigrating VEGF‐producing PBMNCs may enhance the shift to angiogenic phenotype in a variety of infectious and inflammatory disorders as well as in cancer. VEGF‐producing PBMNCs may be a novel mechanism of tissue edema in systemic inflammation. Inhibition of VEGF production in PBMNCs may be one of the mechanisms of interferon‐α action.

who have recovered from yersinia arthritis show enhanced TNF production, which may be regulated at the level of monocyte adhesion.

Possession of CD14 (-159)T allele does not increase risk of ReA but may increase susceptibility of female patients to development of chronic SpA.