Ex vivo modulation of response to prednisolone in childhood acute lymphoblastic leukaemia

Activation of endogenous anti-inflammatory mediator cyclic AMP attenuates acute pyelonephritis in mice induced by uropathogenic Escherichia coli

The pathogenesis of pyelonephritis caused by uropathogenic Escherichia coli (UPEC) is not well understood. Here, we show that besides UPEC virulence, the severity of the host innate immune response and invasion of renal epithelial cells are important pathogenic factors. Activation of endogenous anti-inflammatory mediator cAMP significantly attenuated acute pyelonephritis in mice induced by UPEC. Administration of forskolin (a potent elevator of intracellular cAMP) reduced kidney infection (ie, bacterial load, tissue destruction); this was associated with attenuated local inflammation, as evidenced by the reduction of renal production of proinflammatory mediators, renal infiltration of inflammatory cells, and renal myeloperoxidase activity. In primary cell culture systems, forskolin not only down-regulated UPEC-stimulated production of proinflammatory mediators by renal tubular epithelial cells and inflammatory cells (eg, monocyte/macrophages) but also reduced bacterial internalization by renal tubular epithelial cells. Our findings clearly indicate that activation of endogenous anti-inflammatory mediator cAMP is beneficial for controlling UPEC-mediated acute pyelonephritis in mice. The beneficial effect can be explained at least in part by limiting excessive inflammatory responses through acting on both renal tubular epithelial cells and inflammatory cells and by inhibiting bacteria invasion of renal tubular epithelial cells.

Circumvention of glucocorticoid resistance in childhood leukemia

In this study, we determined if in vitro resistance to prednisolone and dexamethasone could be circumvented by cortivazol or methylprednisolone, or reversed by meta-iodobenzylguanidine in pediatric lymphoblastic and myeloid leukemia. As there were strong correlations between the LC50 values (drug concentration inducing 50% leukemic cell kill, LCK) of the different glucocorticoids and median prednisolone/methylprednisolone, prednisolone/dexamethasone and prednisolone/cortivazol LC50 ratios did not differ between the leukemia subtypes, we conclude that none of the glucocorticoids had preferential anti-leukemic activity. Meta-iodobenzylguanidine however, partially reversed glucocorticoid resistance in 19% of the lymphoblastic leukemia samples.

Transcriptome analysis of age-, gender- and diet-associated changes in murine thymus

The loss of thymic function with age may be due to diminished numbers of T-cell progenitors and the loss of critical mediators within the thymic microenvironment. To assess the molecular changes associated with this loss, we examined transcriptomes of progressively aging mouse thymi, of different sexes and on caloric-restricted (CR) vs. ad libitum (AL) diets. Genes involved in various biological and molecular processes including transcriptional regulators, stress response, inflammation and immune function significantly changed during thymic aging. These differences depended on variables such as sex and diet. Interestingly, many changes associated with thymic aging are either muted or almost completely reversed in mice on caloric-restricted diets. These studies provide valuable insight into the molecular mechanisms associated with thymic aging and emphasize the need to account for biological variables such as sex and diet when elucidating the genomic correlates that influence the molecular pathways responsible for thymic involution.

Cyclic AMP-regulated exocytosis of Escherichia coli from infected bladder epithelial cells

The superficial bladder epithelium is a powerful barrier to urine and also serves as a regulator of bladder volume, which is achieved by apical exocytosis of specialized fusiform vesicles during distension of the bladder. We report that type 1 fimbriated uropathogenic Escherichia coli (UPEC) circumvents the bladder barrier by harboring in these Rab27b/CD63-positive and cAMP-regulatable fusiform vesicles within bladder epithelial cells (BECs). Incorporation of UPEC into BEC fusiform compartments enabled bacteria to escape elimination during voiding and to re-emerge in the urine as the bladder distended. Notably, treatment of UPEC-infected mice with a drug that increases intracellular cAMP and induces exocytosis of fusiform vesicles reduced the number of intracellular E. coli.