Inhibition of alanyl-aminopeptidase on CD4+CD25+ regulatory T-cells enhances expression of FoxP3 and TGF-beta1 and ameliorates acute colitis in mice.

Inhibitors of alanyl-aminopeptidase e.g. phebestin increase the expression of transforming growth factor (TGF)-beta1 in mononuclear cells. We investigated whether phebestin also produced this effect in CD4+CD25+ T-cells and whether phebestin-treated CD4+CD25+ T-cells were capable of ameliorating acute colitis in mice. The suppressive activity of mouse CD4+CD25+ T-cells was assessed in vitro by co-culture with splenocytes. mRNA expression associated with the suppressive phenotype was determined in vitro and in vivo. The in vivo role of phebestin-exposed CD4+CD25+ T-cells was studied in sodium dextran sulfate-induced acute colitis in mice. The proliferation of activated effector T-cells or splenocytes in vitro was inversely correlated with the number of CD4+CD25+ T-cells. Phebestin pre-treatment substantially enhanced the suppressive activity of these cells and increased expression levels of TGF-beta1 and FoxP3. Furthermore, transfer of CD4+CD25+ T-cells exposed to phebestin for a short time ex vivo significantly reduced the mouse colitis disease activity index. We conclude that aminopeptidase inhibitors support the suppressive activity as well as TGF-beta1 and FoxP3 expression of natural regulatory T-cells.

Pathology, diagnosis and pathogenesis of AA amyloidosis.

Amyloid is defined as a proteinaceous tissue deposit that shows a typical green birefringence in polarised light after staining with Congo red, the presence of non-branching linear fibrils of indefinite length with an approximate diameter of 10-12 nm and a distinct X-ray diffraction pattern consistent with Pauling's model of a cross-beta fibril. Approximately 45% of generalised amyloidoses are secondary or reactive (AA) amyloidosis. Among the causes of AA amyloidosis are rheumatic diseases, idiopathic diseases, inherited diseases, infectious diseases and malignant tumours. Recent decades have provided significant advances in our understanding of the pathology and pathogenesis of AA amyloidosis. Its pathogenesis is multifactorial involving many variables such as primary structure of the precursor protein, acute phase response, the presence of non-fibril proteins (e.g. amyloid P component, apolipoprotein E, glycosaminoglycans, proteoglycans and basement membrane proteins), receptors, lipid metabolism and proteases. Study of the pathogenesis of AA amyloidosis has provided many insights into the nature of conformational diseases, which may help in the understanding of other members of this particularly heterogeneous group of diseases, such as Alzheimer's disease and transmissible spongiform encephalopathies.