Mitoprotective Clinical Strategies in Type 2 Diabetes and Fanconi Anemia Patients: Suggestions for Clinical Management of Mitochondrial Dysfunction

Advanced Analysis and Validation of a microRNA Signature for Fanconi Anemia

Some years ago, we reported the generation of a Fanconi anemia (FA) microRNA signature. This study aims to develop an analytical strategy to select a smaller and more reliable set of molecules that could be tested for potential benefits for the FA phenotype, elucidate its biochemical and molecular mechanisms, address experimental activity, and evaluate its possible impact on FA therapy. In silico analyses of the data obtained in the original study were thoroughly processed and anenrichment analysis was employed to identify the classes of genes that are over-represented in the FA-miRNA population under study. Primary bone marrow mononuclear cells (MNCs) from sixFA patients and sixhealthy donors as control samples were employed in the study. RNAs containing the small RNA fractions were reverse-transcribed and real-time PCR was performed in triplicate using the specific primers. Experiments were performed in triplicate.The in-silico analysis reported six miRNAs as likely contributors to the complex pathological spectrum of FA. Among these, three miRNAs were validated by real-time PCR. Primary bone marrow mononuclear cells (MNCs) reported a significant reduction in the expression level of miRNA-1246 and miRNA-206 in the FA samples in comparison to controls.This study highlights several biochemical pathways as culprits in the phenotypic manifestations and the pathophysiological mechanisms acting in FA. A relatively low number of miRNAs appear involved in all these different phenotypes, demonstrating the extreme plasticity of the gene expression modulation. This study further highlights miR-206 as a pivotal player in regulatory functions and signaling in the bone marrow mesenchymal stem cell (BMSC) process in FA. Due to this evidence, the activity of miR-206 in FA deserves specific experimental scrutiny. The results, here presented, might be relevant in the management of FA.

Failure to repair endogenous DNA damage in β-cells causes adult-onset diabetes in mice

Age is the greatest risk factor for the development of type 2 diabetes mellitus (T2DM). Age-related decline in organ function is attributed to the accumulation of stochastic damage, including damage to the nuclear genome. Islets of T2DM patients display increased levels of DNA damage. However, whether this is a cause or consequence of the disease has not been elucidated. Here, we asked if spontaneous, endogenous DNA damage in β-cells can drive β-cell dysfunction and diabetes, via deletion of Ercc1, a key DNA repair gene, in β-cells. Mice harboring Ercc1-deficient β-cells developed adult-onset diabetes as demonstrated by increased random and fasted blood glucose levels, impaired glucose tolerance, and reduced insulin secretion. The inability to repair endogenous DNA damage led to an increase in oxidative DNA damage and apoptosis in β-cells and a significant loss of β-cell mass. Using electron microscopy, we identified β-cells in clear distress that showed an increased cell size, enlarged nuclear size, reduced number of mature insulin granules, and decreased number of mitochondria. Some β-cells were more affected than others consistent with the stochastic nature of spontaneous DNA damage. Ercc1-deficiency in β-cells also resulted in loss of β-cell function as glucose-stimulated insulin secretion and mitochondrial function were impaired in islets isolated from mice harboring Ercc1-deficient β-cells. These data reveal that unrepaired endogenous DNA damage is sufficient to drive β-cell dysfunction and provide a mechanism by which age increases the risk of T2DM.

Mitigating the pro-oxidant state and melanogenesis of Retinitis pigmentosa: by counteracting mitochondrial dysfunction

Retinitis pigmentosa (RP) is a group of mitochondrial diseases characterized by progressive degeneration of rods and cones leading to retinal loss of light sensitivity and, consequently, to blindness. To date, no cure is available according to the clinical literature. As a disease associated with pigmentation-related, pro-oxidant state, and mitochondrial dysfunction, RP may be viewed at the crossroads of different pathogenetic pathways involved in adverse health outcomes, where mitochondria play a preeminent role. RP has been investigated in a number of experimental and clinical studies aimed at delaying retinal hyperpigmentation by means of a number of natural and synthetic antioxidants, as well as mitochondrial cofactors, also termed mitochondrial nutrients (MNs), such as alpha-lipoic acid, coenzyme Q10 and carnitine. One should consider that each MN plays distinct-and indispensable-roles in mitochondrial function. Thus, a logical choice would imply the administration of MN combinations, instead of individual MNs, as performed in previous studies, and with limited, if any, positive outcomes. A rational study design aimed at comparing the protective effects of MNs, separately or in combinations, and in association with other antioxidants, might foresee the utilization of animal RP models. The results should verify a comparative optimization in preventing or effectively contrasting retinal oxidative stress in mouse RP models and, in prospect, in human RP cases.

Friedreich Ataxia: current state-of-the-art, and future prospects for mitochondrial-focused therapies

Friedreich's Ataxia is an autosomal recessive genetic disease causing the defective gene product, frataxin. A body of literature has been focused on the attempts to counteract frataxin deficiency and the consequent iron imbalance, in order to mitigate the disease-associated pro-oxidant state and clinical course. The present mini review is aimed at evaluating the basic and clinical reports on the roles and the use of a set of iron chelators, antioxidants and some cofactors involved in the key mitochondrial functions. Extensive literature has focused on the protective roles of iron chelators, coenzyme Q10 and analogs, and vitamin E, altogether with varying outcomes in clinical studies. Other studies have suggested mitoprotective roles for other mitochondrial cofactors, involved in Krebs cycle, such as alpha-lipoic acid and carnitine, involved in acyl transport across the mitochondrial membrane. A body of evidence points to the strong antioxidant properties of these cofactors, and to their potential contribution in mitoprotective strategies in Friedreich's Ataxia clinical evolution. Thus, we suggest the rationale for planning combination strategies based on the 3 mitochondrial cofactors and of some antioxidants and iron binders as mitoprotective cocktails in Friedreich Ataxia patients, calling attention to clinical practitioners of the importance to implement clinical trials.

Potential roles of mitochondrial cofactors in the adjuvant mitigation of proinflammatory acute infections, as in the case of sepsis and COVID-19 pneumonia

BACKGROUND

The mitochondrial cofactors α-lipoic acid (ALA), coenzyme Q10 (CoQ10) and carnitine (CARN) play distinct and complementary roles in mitochondrial functioning, along with strong antioxidant actions. Also termed mitochondrial nutrients (MNs), these cofactors have demonstrated specific protective actions in a number of chronic disorders, as assessed in a well-established body of literature.

METHODS

Using PubMed, the authors searched for articles containing information on the utilization of MNs in inflammatory disorders as assessed from in vitro and animal studies, and in clinical trials, in terms of exerting anti-inflammatory actions.

RESULTS

The retrieved literature provided evidence relating acute pathologic conditions, such as sepsis and pneumonia, with a number of redox endpoints of biological and clinical relevance. Among these findings, both ALA and CARN were effective in counteracting inflammation-associated redox biomarkers, while CoQ10 showed decreased levels in proinflammatory conditions. MN-associated antioxidant actions were applied in a number of acute disorders, mostly using one MN. The body of literature assessing the safety and the complementary roles of MNs taken together suggests an adjuvant role of MN combinations in counteracting oxidative stress in sepsis and other acute disorders, including COVID-19-associated pneumonia.

CONCLUSIONS

The present state of art in the use of individual MNs in acute disorders suggests planning adjuvant therapy trials utilizing MN combinations aimed at counteracting proinflammatory conditions, as in the case of pneumonia and the COVID-19 pandemic.

Re-definition and supporting evidence toward Fanconi Anemia as a mitochondrial disease: Prospects for new design in clinical management

Fanconi anemia (FA) has been investigated since early studies based on two definitions, namely defective DNA repair and proinflammatory condition. The former definition has built up the grounds for FA diagnosis as excess sensitivity of patients’ cells to xenobiotics as diepoxybutane and mitomycin C, resulting in typical chromosomal abnormalities. Another line of studies has related FA phenotype to a prooxidant state, as detected by both in vitro and ex vivo studies. The discovery that the FA group G (FANCG) protein is found in mitochondria (Mukhopadhyay et al., 2006) has been followed by an extensive line of studies providing evidence for multiple links between other FA gene products and mitochondrial dysfunction. The fact that FA proteins are encoded by nuclear, not mitochondrial DNA does not prevent these proteins to hamper mitochondrial function, as it is recognized that most mitochondrial proteins are of nuclear origin. This body of evidence supporting a central role of mitochondrial dysfunction, along with redox imbalance in FA, should lead to the re-definition of FA as a mitochondrial disease. A body of literature has demonstrated the beneficial effects of mitochondrial cofactors, such as α-lipoic acid, coenzyme Q10, and carnitine on patients affected by mitochondrial diseases. Altogether, this re-definition of FA as a mitochondrial disease and the prospect use of mitochondrial nutrients may open new gateways toward mitoprotective strategies for FA patients. These strategies are expected to mitigate the mitochondrial dysfunction and prooxidant state in FA patients, and potentially protect transplanted FA patients from post-transplantation malignancies.