The immune system undergoes a process of profound remodelling during aging, referred to as immunosenescence, and characterized by complex modifications of several components. In this review, we discuss recent developments and observations regarding the generation of T cells in the thymus during aging and longevity, and the regulation and maintenance of peripheral blood lymphocytes. The generation of new T cells is indeed crucial to maintain a functional immune system, and is a fundamental step to avoid unsuccessful aging, thus reaching longevity in good health. Mechanisms will be described that are related to the production and maintenance of those lymphocytes defined "recent thymic emigrants", and to the detection of the so called "T cell receptor rearrangement excision circles (TREC)", along with the presence in the periphery of naive and memory T cells, that can be influenced and regulated by several different mechanisms. Several strategies aimed at improving thymic functionality are currently receiving a growing interest, and some of them are based on molecules that are produced by, and/or act on immune cells. Data on the possible use of these molecules, including cytokines like interleukin (IL)-7, IL-15 and keratinocyte growth factor, to restore thymic function are reviewed and discussed.

Both HIV infection per se and antiretroviral drugs might contribute to oxidative stress and mitochondrial dysfunctions. In this study we assess zidovudine, stavudine and didanosine on U937 and CEM cell lines. All these drugs induced apoptosis and increased intracellular hydrogen peroxide but not superoxide anions. The addition of acetyl-l-carnitine (ALC) was able to prevent the pro-oxidant effect of the drugs tested. Supplementation with ALC, deficient in certain cohorts of HIV-infected individuals, especially on high active antiretroviral therapy regimen, has been associated with favourable effects. These data suggest that one of these effects could be a direct anti-oxidant action.

Until now, the simultaneous analysis of several parameters during apoptosis, including DNA content and mitochondrial membrane potential (ΔΨ), has not been possible because of the spectral characteristics of the commonly used dyes. Using polychromatic flow cytometry based upon multiple laser and UV lamp excitation, we have characterized cells with different ΔΨ during apoptosis.

We have analyzed the anti- or pro-oxidant effects of the flavonoid quercetin (QU) by evaluating, in U937 cell line, hydrogen peroxide (H2O2), superoxide anion reduced glutathione (GSH) content, mitochondrial membrane potential, DNA content, phosphatidylserine exposure on the outer face of the plasma membrane and cell viability. Polychromatic flow cytometry was used to evaluate in the same cells several functional parameters. For short periods of treatment QU exerted an anti-oxidant effect (decrease in H2O2 levels), whereas for long periods it showed a pro-oxidant activity (increase in ). In these conditions, GSH content was reduced, and this correlated with a lack of anti-oxidant activity of QU, which in turn could be correlated with proapoptotic activity of this molecule. Thus, QU can exert different effects (anti-/prooxidant) depending on exposure times and oxidative balance, and in particular on stores of GSH.

BACKGROUND:Damage to mitochondria (mt) is a major side effect of highly active antiretroviral therapy (HAART) that includes a nucleoside reverse transcriptase inhibitor (NRTI). Such damage is associated with the onset of lipodystrophy in HAART-treated HIV+ patients. To further investigate mt changes during this syndrome, we analysed the expression of mtRNA in adipocytes from lipodystrophic HIV+ patients taking NRTI-containing HAART and compared it with similar cells from healthy individuals. MATERIALS AND METHODS:Total RNA was extracted from adipocytes collected from different anatomical locations of 11 HIV+ lipodystrophic patients and seven healthy control individuals. RNA was reverse transcribed and Taqman-based real-time PCR was used to quantify three different mt transcripts (ND1, CYTB and ND6 gene products). mtRNA content was normalized versus the housekeeping transcript L13. RESULTS:ND1, CYTB and ND6 expression was significantly reduced in HIV+ lipodystrophic patients. HIV+ men and women did not differ in a statistically significant way regarding the levels of ND1 and ND6, whereas the opposite occurred for CYTB. CONCLUSIONS:Lipodystrophy following treatment with NRTI-containing HAART is associated with a decrease in adipose tissue mtRNAs.