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The pathophysiology of diverticular disease (DD) is not well outlined. Recent studies performed on the DD human ex vivo model have shown the presence of a predominant transmural oxidative imbalance whose origin remains unknown. Considering the central role of mitochondria in oxidative stress, the present study evaluates their involvement in the alterations of DD clinical phenotypes. Colonic surgical samples of patients with asymptomatic diverticulosis, complicated DD, and controls were analyzed. Electron microscopy, protein expression, and cytofluorimetric analyses were performed to assess the contribution of mitochondrial oxidative stress. Functional muscle activity was tested on cells in response to contractile and relaxant agents. To assess the possibility of reverting oxidative damages, N-acetylcysteine was tested on an in vitro model. Compared with the controls, DD tissues showed a marketed increase in mitochondrial number and fusion accompanied by the altered mitochondrial electron transport chain complexes. In SMCs, the mitochondrial mass increase was accompanied by altered mitochondrial metabolic activity supported by a membrane potential decrease. Ulteriorly, a decrease in antioxidant content and altered contraction-relaxation dynamics reverted by N-acetylcysteine were observed. Therefore, the oxidative stress-driven alterations resulted in mitochondrial impairment. The beneficial effects of antioxidant treatments open new possibilities for tailored therapeutic strategies that have not been tested for this disease.

Mitochondria-associated membranes (MAMs) are subdomains of the endoplasmic reticulum (ER) that interact with mitochondria. This membrane scrambling between ER and mitochondria appears to play a critical role in the earliest steps of autophagy. Recently, lipid microdomains, i.e. lipid rafts, have been identified as further actors of the autophagic process. In the present work, a series of biochemical and molecular analyses has been carried out in human fibroblasts with the specific aim of characterizing lipid rafts in MAMs and to decipher their possible implication in the autophagosome formation. In fact, the presence of lipid microdomains in MAMs has been detected and, in these structures, a molecular interaction of the ganglioside GD3, a paradigmatic "brick" of lipid rafts, with core-initiator proteins of autophagy, such as AMBRA1 and WIPI1, was revealed. This association seems thus to take place in the early phases of autophagic process in which MAMs have been hypothesized to play a key role. The functional activity of GD3 was suggested by the experiments carried out by knocking down ST8SIA1 gene expression, i.e., the synthase that leads to the ganglioside formation. This experimental condition results in fact in the impairment of the ER-mitochondria crosstalk and the subsequent hindering of autophagosome nucleation. We thus hypothesize that MAM raft-like microdomains could be pivotal in the initial organelle scrambling activity that finally leads to the formation of autophagosome.

Huntington's disease (HD) is a genetic neurodegenerative disease characterized by an exceedingly high number of contiguous glutamine residues in the translated protein, huntingtin (Htt). The primary site of cell toxicity is the nucleus, but mitochondria have been identified as key components of cell damage. The present work has been carried out in immortalized lymphocytes from patients with HD. These cells, in comparison with lymphoid cells from healthy subjects, displayed: i) a redistribution of mitochondria, forming large aggregates; ii) a constitutive hyperpolarization of mitochondrial membrane; and iii) a constitutive alteration of mitochondrial fission machinery, with high apoptotic susceptibility. Moreover, mitochondrial fission molecules, e.g., protein dynamin-related protein 1, as well as Htt, associated with mitochondrial raft-like microdomains, glycosphingolipid-enriched structures detectable in mitochondria. These findings, together with the observation that a ceramide synthase inhibitor and a raft disruptor are capable of impairing the peculiar mitochondrial remodeling in HD cells, suggest that mitochondrial alterations occurring in these cells could be due to raft-mediated defects of mitochondrial fission/fusion machinery.

Background: Highly active antiretroviral therapy (HAART) has largely reduced the occurrence of AIDS-related diseases and death in HIV-infected patients. However, HAART produces serious side effects mainly attributed to mitochondrial toxicity., Methods: To elucidate the molecular basis of HAART-related dysfunctions, we analysed the mitochondrial proteome of peripheral blood mononuclear cells from HIV-infected patients using two-dimensional gel electrophoresis and MALDI-TOF/TOF mass spectrometry. Proteomic analysis was performed on HIV patients who were either treatment-naive or under HAART therapy including zidovudine or stavudine as nucleoside reverse transcriptase inhibitors (NRTIs)., Results: As compared to healthy donors, HAART-treated HIV-infected patients exhibited decreased levels of mitochondrial enzymes associated with energy production as well as mitochondrial chaperones. Moreover, significant alterations in the mitochondria-cytoskeleton network were observed. Notably, most of these changes were already detectable in untreated HIV carriers and persisted or worsened after HAART, indicating that relevant mitochondrial alterations were initially caused by HIV infection. Finally, in vitro experiments aimed at validating the proteomic results showed that down-regulation of the mitochondrial chaperone prohibitin is a causative event in NRTI-induced mitochondrial damage., Conclusions: Our results indicate a major role of HIV infection in the mitochondrial toxicity of HAART-treated patients and identify novel candidate markers for assessing the risk of HIV- and HAART-related pathologies.

Cardiolipin (CL) has recently been shown to provide an anchor and an essential activating platform for caspase-8 on mitochondria. We hypothesize that these platforms may correspond to "raft-like" microdomains, which have demonstrated to be detectable on mitochondrial membrane of cells undergoing apoptosis. The role for CL in "raft-like" microdomains could be to anchor caspase-8 at contact sites between inner and outer membranes, facilitating its self-activation, Bid cleavage and apoptosis execution. The role played by "raft-like" microdomains in the apoptotic program could introduce a new task in the pathogenetic studies on human diseases associated with cardiolipin dismetabolism.

Plasma membrane lipid rafts have been considered as a sort of "chamber", where several subcellular activities, including CD95/Fas-mediated pro-apoptotic signaling, can take place. Recently, we demonstrated that, after CD95/Fas triggering, raft-like microdomains could be detected in mitochondrial membranes. The mitochondrion appears as a dynamic and subcompartmentalized organelle in which microdomains might act as controllers of apoptosis-associated fission that results in the release of apoptogenic factors. Here, we hypothesize that some "small" mitochondria, possibly derived from their fission process, can reach the nuclear envelope and strictly interact with this. Mitochondria could act as a signaling "device" contributing to molecular trafficking of molecules, including raft-like components, during apoptosis.

Mitoptosis was described as a sort of mitochondrial death program. It could be associated with both necrosis and apoptosis, although degenerating mitochondria are also found in autophagic vacuoles. It was demonstrated that several molecules might contribute to the remodeling and rearrangement of mitochondrial membranes, leading to mitochondria rupture and disruption. Here, we hypothesize that, at least in T cells, two main pathways of mitoptosis can occur: an inner membrane mitoptosis (IMM), in which only the internal matrix and cristae are lost while the external mitochondrial envelope remains unaltered, and an outer membrane mitoptosis (OMM) where only swollen internal cristae are detected as remnants. We suggest that the study of these processes could provide useful insights not only to the field of cell death but also to the study of the pathogenic mechanisms of mitochondria-associated human diseases.

Galectins have emerged as a novel family of immunoregulatory proteins implicated in T cell homeostasis. Recent studies showed that galectin-1 (Gal-1) plays a key role in tumor-immune escape by killing antitumor effector T cells. Here we found that Gal-1 sensitizes human resting T cells to Fas (CD95)/caspase-8-mediated cell death. Furthermore, this protein triggers an apoptotic program involving an increase of mitochondrial membrane potential and participation of the ceramide pathway. In addition, Gal-1 induces mitochondrial coalescence, budding, and fission accompanied by an increase and/or redistribution of fission-associated molecules h-Fis and DRP-1. Importantly, these changes are detected in both resting and activated human T cells, suggesting that Gal-1-induced cell death might become an excellent model to analyze the morphogenetic changes of mitochondria during the execution of cell death. This is the first association among Gal-1, Fas/Fas ligand-mediated cell death, and the mitochondrial pathway, providing a rational basis for the immunoregulatory properties of Gal-1 in experimental models of chronic inflammation and cancer.

It has been demonstrated that HIV protease inhibitors (Pls) are able to inhibit apoptosis of both infected and uninfected T cells. It was hypothesized that the mechanisms underlying this effect are associated with a specific activity of these drugs against mitochondrial modifications occurring in the execution phase of apoptosis. In this work, we investigated the activity of PIs towards the early changes occurring in mitochondrial membrane potential in freshly isolated uninfected human T lymphocytes sensitized to CD95/Fas-induced physiological apoptosis via pre-exposure to HIV envelope protein gp120. The results obtained clearly indicate that PIs are capable of hindering early morphogenetic changes bolstering T cell apoptosis, that is, cell polarization and mitochondrial hyperpolarization. The target effect on mitochondria appeared to be characterized by a specific activity of Pls in the maintenance of their homeostasis either in intact cells or in cell-free systems, that is, isolated mitochondria. Pls seem to act as boosters of mitochondrial defense mechanisms, including modulation of endogenous uncouplers. These results add new insights in the field of PI mitochondrial toxicity mechanisms and pharmacological perspectives for the use of these drugs in the control of immune system homeostasis.