Biomedical subjects

Addolorata Pisconti

Publications and source records attributed to Addolorata Pisconti.

7 recordsLinked to original sources

PubMed2006

TNF-alpha downregulates eNOS expression and mitochondrial biogenesis in fat and muscle of obese rodents.

Obesity is associated with chronic low-grade inflammation. Thus, at metabolically relevant sites, including adipose tissue and muscle, there is abnormal production of proinflammatory cytokines such as TNF-alpha. Here we demonstrate that eNOS expression was reduced, with a concomitant reduction of mitochondrial biogenesis and function, in white and brown adipose tissue and in the soleus muscle of 3 different animal models of obesity. The genetic deletion of TNF receptor 1 in obese mice restored eNOS expression and mitochondrial biogenesis in fat and muscle; this was associated with less body weight gain than in obese wild-type controls. Furthermore, TNF-alpha downregulated eNOS expression and mitochondrial biogenesis in cultured white and brown adipocytes and muscle satellite cells of mice. The NO donors DETA-NO and SNAP prevented the reduction of mitochondrial biogenesis observed with TNF-alpha. Our findings demonstrate that TNF-alpha impairs mitochondrial biogenesis and function in different tissues of obese rodents by downregulating eNOS expression and suggest a novel pathophysiological process that sustains obesity.

Adenosine Triphosphate↗

PubMed2006

Follistatin induction by nitric oxide through cyclic GMP: a tightly regulated signaling pathway that controls myoblast fusion.

The mechanism of skeletal myoblast fusion is not well understood. We show that endogenous nitric oxide (NO) generation is required for myoblast fusion both in embryonic myoblasts and in satellite cells. The effect of NO is concentration and time dependent, being evident only at the onset of differentiation, and direct on the fusion process itself. The action of NO is mediated through a tightly regulated activation of guanylate cyclase and generation of cyclic guanosine monophosphate (cGMP), so much so that deregulation of cGMP signaling leads to a fusion-induced hypertrophy of satellite-derived myotubes and embryonic muscles, and to the acquisition of fusion competence by myogenic precursors in the presomitic mesoderm. NO and cGMP induce expression of follistatin, and this secreted protein mediates their action in myogenesis. These results establish a hitherto unappreciated role of NO and cGMP in regulating myoblast fusion and elucidate their mechanism of action, providing a direct link with follistatin, which is a key player in myogenesis.

Animals↗

PubMed2006

Impaired interleukin-12-dependent T-cell functions during aging: role of signal transducer and activator of transcription 4 (STAT4) and suppressor of cytokine signaling 3 (SOCS3).

Interleukin (IL)-12 is the major inducer of T helper cell (Th) 1-type responses. Despite a higher IL-12 production, phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC), as well as CD4(+) or CD8(+) T cells from elderly donors released interferon (IFN)-gamma amounts similar to those observed in young controls, and underwent only a slight increase in IFN-gamma production after IL-12 costimulation. These findings were not due to an age-related reduction in IL-12 receptor expression. Interestingly, no difference in PHA-triggered signal transducer and activator of transcription 4 (STAT4) phosphorylation between young and elderly donors was found, and a significant IL-12-induced STAT4 activation occurred only in PHA-preactivated cells from the younger group. The age-related defect in IL-12 signaling was STAT4-restricted as it did not involve the p38 mitogen-activated protein kinase (MAPK) pathway. Finally, suppressor of cytokine signaling 3 (SOCS3) expression was significantly higher in unstimulated cells from elderly individuals, and it did not diminish after cell stimulation. These results indicate that a defective STAT4 activation, likely dependent on elevated SOCS3 levels, is involved in the impaired IL-12-dependent T-cell functions with aging.

Aged↗

PubMed2004

Mitochondrial biogenesis by NO yields functionally active mitochondria in mammals.

We recently found that long-term exposure to nitric oxide (NO) triggers mitochondrial biogenesis in mammalian cells and tissues by activation of guanylate cyclase and generation of cGMP. Here, we report that the NO/cGMP-dependent mitochondrial biogenesis is associated with enhanced coupled respiration and content of ATP in U937, L6, and PC12 cells. The observed increase in ATP content depended entirely on oxidative phosphorylation, because ATP formation by glycolysis was unchanged. Brain, kidney, liver, heart, and gastrocnemius muscle from endothelial NO synthase null mutant mice displayed markedly reduced mitochondrial content associated with significantly lower oxygen consumption and ATP content. In these tissues, ultrastructural analyses revealed significantly smaller mitochondria. Furthermore, a significant reduction in the number of mitochondria was observed in the subsarcolemmal region of the gastrocnemius muscle. We conclude that NO/cGMP stimulates mitochondrial biogenesis, both in vitro and in vivo, and that this stimulation is associated with increased mitochondrial function, resulting in enhanced formation of ATP.

Adenosine Triphosphate↗

PubMed2004

Activation of acid sphingomyelinase and its inhibition by the nitric oxide/cyclic guanosine 3',5'-monophosphate pathway: key events in Escherichia coli-elicited apoptosis of dendritic cells.

Depletion of dendritic cells (DCs) via apoptosis contributes to sepsis-induced immune suppression. The mechanisms leading to DC apoptosis during sepsis are not known. In this study we report that immature DCs undergo apoptosis when treated with high numbers of Escherichia coli. This effect was mimicked by high concentrations of LPS. Apoptosis was accompanied by generation of ceramide through activation of acid sphingomyelinase (A-SMase), was prevented by inhibitors of this enzyme, and was restored by exogenous ceramide. Compared with immature DCs, mature DCs expressed significantly reduced levels of A-SMase, did not generate ceramide in response to E. coli or LPS, and were insensitive to E. coli- and LPS-triggered apoptosis. However, sensitivity to apoptosis was restored by addition of exogenous A-SMase or ceramide. Furthermore, inhibition of A-SMase activation and ceramide generation was found to be the mechanism through which the immune-modulating messenger NO protects immature DCs from the apoptogenic effects of E. coli and LPS. NO acted through formation of cGMP and stimulation of the cGMP-dependent protein kinase. The relevance of A-SMase and its inhibition by NO/cGMP were confirmed in a mouse model of LPS-induced sepsis. DC apoptosis was significantly higher in inducible NO synthase-deficient mice than in wild-type animals and was significantly reduced by treatment ex vivo with NO, cGMP, or the A-SMase inhibitor imipramine. Thus, A-SMase plays a central role in E. coli/LPS-induced DC apoptosis and its inhibition by NO, and it might be a target of new therapeutic approaches to sepsis.

Animals↗

PubMed2004

Nitric oxide confers therapeutic activity to dendritic cells in a mouse model of melanoma.

Susceptibility of dendritic cells (DCs) to tumor-induced apoptosis reduces their efficacy in cancer therapy. Here we show that delivery within exponentially growing B16 melanomas of DCs treated ex vivo with nitric oxide (NO), released by the NO donor (z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO), significantly reduced tumor growth, with cure of 37% of animals. DETA-NO-treated DCs became resistant to tumor-induced apoptosis because DETA-NO prevented tumor-induced changes in the expression of Bcl-2, Bax, and Bcl-xL; activation of caspase-9; and a reduction in the mitochondrial membrane potential. DETA-NO also increased DC cytotoxic activity against tumor cells and DC ability to trigger T-lymphocyte proliferation. All of the effects of DETA-NO were mediated through cGMP generation. NO and NO-generating drugs may therefore be used to increase the anticancer efficacy of DCs.

Animals↗

PubMed2002

APC-dependent impairment of T cell proliferation in aging: role of CD28- and IL-12/IL-15-mediated signaling.

The age-related impairment of phytohaemagglutinin (PHA)-triggered peripheral blood mononuclear cell (PBMC) proliferation was paralleled by an expansion of CD28 (-) T lymphocytes with a poor capacity to undergo lectin-induced blastogenesis. However, both CD28 (-) and CD28 (+) T cells isolated from aged individuals exhibited a significant reduction of proliferative response to PHA in comparison with young controls, this implies that the CD28-mediated signaling is not the only defective pathway in the elderly. Thus, PBMC or T cell subsets plus monocytes from aged donors were stimulated with PHA and assayed for the production of, or the response to cytokines known to regulate T cell functions. Results can be so summarized: (i). interleukin (IL)-2 as well as IL-10 release was unaffected by age; (ii). in both groups of subjects, IL-15 concentrations were similar to those spontaneously released by PBMC; (iii). surprisingly, IL-12 p70 and IL-12 p40 production by PBMC was markedly increased in the aged group; (iv) in spite of this finding and of the experimental outcome that IFN-gamma synthesis was almost completely dependent on IL-12. PBMC from old individuals did not release higher amounts of IFN-gamma in comparison with young controls; (v). moreover, only a slight increase in IFN-gamma production was observed in PBMC cultures from the aged group as a result of IL-12 and/or IL-15 costimulation; (vi) at the same time, even though IL-12 as well as IL-15 were necessary for an efficient T cell proliferation, the addition of exceeding doses of cytokines proved to be ineffective in enhancing the proliferative outcome of PBMC or of both CD28 (+) and CD28 (-) T cells in the aged group. Taken together, the data outline the role of CD28 and IL-12/IL-15 signaling impairment in T cell proliferative deficiency during senescence.

Adult↗