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Neurodegenerative diseases, such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Multiple Sclerosis (MS), and Huntington’s disease (HD), although distinct in their clinical manifestations, share a common hallmark: a disrupted neuroinflammatory environment orchestrated by dysregulation of neuroglial intercellular communication. Neuroglial crosstalk is physiologically ensured by extracellular mediators and by the activity of connexins (Cxs), the forming proteins of gap junctions (Gjs) and hemichannels (HCs), which maintain intracellular and extracellular homeostasis. However, accumulating evidence suggests that Cxs can also act as pathological pore in neuroinflammatory conditions, thereby contributing to neurodegenerative phenomena such as synaptic dysfunction, oxidative stress, and ultimately cell death. This review explores mechanistic insights of Cxs-mediated intercellular communication in the progression of neurodegenerative diseases and discusses the therapeutic potential of targeting Cxs to restore cellular homeostasis.

Neural stem cells (NSCs) are defined by their self-renewal capacity and multipotent differentiation potential, making them essential for nervous system development and for the maintenance of adult brain homeostasis. Although confined to the subventricular zone and the subgranular zone of the hippocampus in adulthood, NSCs preserve a functional capacity for neurogenesis and tissue regeneration. This regenerative potential becomes particularly important in neuropathological conditions, where tissue damage is often accompanied by neuroinflammation and oxidative stress. Within this hostile microenvironment, NSCs have to cope with inflammatory mediators and reactive oxygen species that can affect their survival, proliferation, and cellular differentiation. NSCs also are actively modulated by diverse molecular pathways in response to stress conditions promoting stemness or stem cell exhaustion. Therefore, understanding the crosstalk between neuroinflammatory and oxidative stress in NSCs fate is crucial for elucidating the mechanisms of neurogenesis and homeostasis recovery and for designing therapeutic strategies.

Glioblastoma (GBM) is one of the deadliest tumors due to its high aggressiveness and resistance to standard therapies, resulting in a dismal prognosis. This lethal tumor carries out metabolic reprogramming in order to modulate specific pathways, providing metabolites that promote GBM cells proliferation and limit the efficacy of standard treatments. Indeed, GBM remodels glucose metabolism and undergoes Warburg effect, fuelling glycolysis even when oxygen is available. Moreover, recent evidence revealed a rewiring in nucleotide, lipid and iron metabolism, resulting not only in an increased tumor growth, but also in radio- and chemo-resistance. Thus, while on the one hand metabolic reprogramming is an advantage for GBM, on the other hand it may represent an exploitable target to hamper GBM progression. Lately, a number of studies focused on drugs targeting metabolism to uncover their effects on tumor proliferation and therapy resistance, demonstrating that some of these are effective, in combination with conventional treatments, sensitizing GBM to radiotherapy and chemotherapy. However, GBM heterogeneity could lead to a plethora of metabolic alterations among subtypes, hence a metabolic treatment might be effective for proneural tumors but not for mesenchymal ones, which are more aggressive and resistant to conventional approaches. This review explores key mechanisms of GBM metabolic reprogramming and their involvement in therapy resistance, highlighting how metabolism acts as a double-edged sword for GBM, taking into account metabolic pathways that seem to offer promising treatment options for GBM.

Background Follicular thyroid cancer (FTC) is a prevalent form of differentiated thyroid cancer, whereas anaplastic thyroid cancer (ATC) represents a rare, fast-growing, undifferentiated, and highly aggressive tumor, posing significant challenges for eradication. Ferroptosis, an iron-dependent cell death mechanism driven by the excessive production of reactive oxygen species and subsequent lipid peroxidation, emerges as a promising therapeutic strategy for cancer. It has been observed that many cancer cells exhibit sensitivity to ferroptosis, while some other histotypes appear to be resistant, by counteracting the metabolic changes and oxidative stress induced by iron overload. Methods Here we used human biopsies and in vitro approaches to analyse the effects of iron-dependent cell death. We assessed cell proliferation and viability through MTT turnover, clonogenic assays, and cytofluorimetric-assisted analysis. Lipid peroxidation assay and western blot were used to analyse molecular mechanisms underlying ferroptosis modulation. Two distinct thyroid cancer cell lines, FTC-133 (follicular) and 8505C (anaplastic), were utilized. These cell lines were exposed to ferroptosis inducers, Erastin and RSL3, while simulating an iron overload condition using ferric ammonium citrate. Results Our evidence suggests that FTC-133 cell line, exposed to iron overload, reduced their viability and showed increased ferroptosis. In contrast, the 8505C cell line seems to better tolerate ferroptosis, responding by modulating CD71, which is involved in iron internalization and seems to have a role in resistance to iron overload and consequently in maintaining cell viability. Conclusions The differential tolerance to ferroptosis observed in our study may hold clinical implications, particularly in addressing the unmet therapeutic needs associated with ATC treatment, where resistance to ferroptosis appears more pronounced compared to FTC.

Glioblastoma (GBM) represents an aggressive brain tumor, characterized by intra- and inter-tumoral heterogeneity and therapy resistance, leading to unfavourable prognosis. An increasing number of studies pays attention on the regulation of ferroptosis, an iron-dependent cell death, as a strategy to reverse drug resistance in cancer. However, the debate on whether this strategy may have important implications for the treatment of GBM is still ongoing. In the present study, we used ferric ammonium citrate and erastin to evaluate ferroptosis induction effects on two human GBM cell lines, U-251 MG, with proneural characteristics, and T98-G, with a mesenchymal profile. The response to ferroptosis induction was markedly different between cell lines, indeed T98-G cells showed an enhanced antioxidant defence, with increased glutathione levels, as compared to U-251 MG cells. Moreover, using bioinformatic approaches and analysing publicly available datasets from patients’ biopsies, we found that GBM with a mesenchymal phenotype showed an up-regulation of several genes involved in antioxidant mechanisms as compared to proneural subtype. Thus, our results suggest that GBM subtypes differently respond to ferroptosis induction, emphasizing the significance of further molecular studies on GBM to better discriminate between various tumor subtypes and progressively move towards personalized therapy.

Accumulating evidence sustains glial cells as critical players during central nervous system (CNS) development, homeostasis and disease. Olfactory ensheathing cells (OECs), a type of specialized glia cells sharing properties with both Schwann cells and astrocytes, are of critical importance in physiological condition during olfactory system development, supporting its regenerative potential throughout the adult life. These characteristics prompted research in the field of cell-based therapy to test OEC grafts in damaged CNS. Neuroprotective mechanisms exerted by OEC grafts are not limited to axonal regeneration and cell differentiation. Indeed, OEC immunomodulatory properties and their phagocytic potential encourage OEC-based approaches for tissue regeneration in case of CNS injury. Herein we reviewed recent advances on the immune role of OECs, their ability to modulate CNS microenvironment via bystander effects and the potential of OECs as a cell-based strategy for tissue regeneration.

Glioblastoma (GBM) is among the deadliest cancers, characterized by poor prognosis and median survival of 12–15 months post-diagnosis. Despite aggressive therapeutic regimens, GBM treatment is still an unmet clinical need due to heterogeneity, recurrencies, and resistance. Metabolic reshaping is emerging as a critical mechanism supporting cell proliferation and sustaining chemoresistance. In this study, we explored metabolic changes induced by chemotherapy in temozolomide (TMZ)-sensitive and TMZ-resistant GBM cell lines. We found that purine levels were altered in sensitive versus resistant GBM cells, highlighting a critical role of guanosine and inosine metabolism. By using a mesenchymal-like GBM zebrafish model, we uncovered dysregulated pathways involved in purine metabolism, with a downregulation of catabolic processes. Our data indicate that combined treatment with TMZ plus guanosine and inosine increased cytotoxicity, enhancing chemotherapy effectiveness in TMZ-resistant cells. These effects correlated with alterations in mitochondrial dynamics and activity. Specifically, the combinatorial effectiveness of TMZ with guanosine and inosine was linked to Mitofusin-2 overexpression, enhancing mitochondrial fusion, typically associated with a better prognosis. Therefore, our findings suggest that purine metabolism is involved in the metabolic rewiring of TMZ-resistant cells, suggesting guanosine and inosine as potential adjuvant treatments to improve the cytotoxicity effects of chemotherapy in resistant GBM.

Recent investigations into radiation-induced side effects have focused on understanding the physiopathological consequences of irradiation on late-responding tissues like the spinal cord, which can lead to chronic progressive myelopathy. Proton therapy, an advanced radiation treatment, aims to minimize damage to healthy tissues through precise dose deposition. However, challenges remain, particularly regarding the variation in dose distribution, characterized by maximum deposition at the end of the proton range, known as the distal fall-off of a spread-out Bragg peak. This variation is critical for nearby organs at risk. In this preliminary study, we evaluated the effects of proton irradiation on the neuronal cell population in mouse spinal cord by comparing two positions of the particle range dose deposition profile. We irradiated the spinal cords at the entrance and the distal edge of the spread-out Bragg peak with a single proton dose. Results showed changes in the expression of synaptophysin, a presynaptic protein crucial for synaptic plasticity. Our findings suggest that examining early radiation-induced physiopathological effects on late-responding tissues can provide valuable insights into neuronal plasticity, informing clinical treatment planning for proton beam positioning.

Background Tobacco smoking is the leading cause of preventable death and disease worldwide, with over 8 million annual deaths attributed to cigarette smoking. This study investigates the impact of cigarette smoke and heated tobacco products (HTPs) on microglial function, focusing on toxicological profiles, inflammatory responses, and oxidative stress using ISO standard and clinically relevant conditions of exposure. Methods We assessed cell viability, reactive oxygen species (ROS) production, lipid peroxidation, mitochondrial function, unfolded protein response, and inflammation in human microglial cells (HMC3) exposed to cigarette smoke, HTP aerosol or nicotine. Results Our findings show that cigarette smoke significantly reduces microglial viability, increases ROS formation, induces lipid peroxidation, and reduces intracellular glutathione levels. Cigarette smoke also alters the expression of genes involved in mitochondrial dynamics and biogenesis, leading to mitochondrial dysfunction. Additionally, cigarette smoke impairs the unfolded protein response, activates the NF-κB pathway, and induces a pro-inflammatory state characterized by increased TNF and IL-18 expression. Furthermore, cigarette smoke causes DNA damage and decreases the expression of the aging marker Klotho β. In contrast, HTP, exhibited a lesser degree of microglial toxicity, with reduced ROS production, lipid peroxidation, and mitochondrial dysfunction compared to conventional cigarettes. Conclusion These results highlight the differential toxicological profile of cigarette smoke and HTP on microglial cells, suggesting a potential harm reduction strategy for neurodegenerative disease for smokers unwilling or unable to quit.

Background Connexin 43 (CX43) is a hemichannel (HC)- and gap junction (GJ)-forming protein that mediates the exchange of small molecules between the intracellular and extracellular environments, as well as intercellular communication. In addition to this canonical role, recent studies have shown that its functions range from transcriptional regulation to intracellular homeostasis. The ability of CX43 to translocate into mitochondria suggests its involvement in energy metabolism. However, the functions of mitochondrial CX43 (mt-CX43) in neural cells remain unexplored. Methods Our study investigated the expression and localisation of mt-CX43 through western blot and immunofluorescence analyses in four immortalised human glioma cell lines: T98-G, A-172, CCF-STTG1, and U-87 MG. Additionally, targeted metabolomic analysis was conducted to assess changes in key metabolic pathways. Results Basal CX43 expression and extracellular stress factors, particularly cell density and extracellular pH fluctuations, significantly modulated the mitochondrial localisation of CX43. Inhibition of the heat shock protein 90 (HSP90) chaperone system by geldanamycin (GA) resulted in a marked reduction in mt-CX43, suggesting an import mechanism involving HSP90 and the translocase of the outer membrane (TOM) complex. In addition, the assessment of key metabolites revealed increased purine biosynthesis in T98-G cells exposed to GA treatment, characterised by lower basal CX43 expression and reduced mt-CX43 levels under stress conditions. Conversely, U-87 MG cells exhibited a stable NAD + /NADH ratio and a significant increase in NADH levels, indicating a metabolic shift towards a more resilient state. Conclusions Our results suggest that mt-CX43 serves as a multifunctional regulator of metabolic adaptation and stress response in glioma cell lines. Our results extend the role of mt-CX43 as an essential factor in cellular metabolic plasticity, providing new insights into the modulation of metabolic imbalances and mitochondrial dysfunction. Plain english summary Connexin 43 (CX43) is a multifunctional protein known for its canonical role in forming hemichannels and gap junctions, which mediate the exchange of signals and small molecules. Although this pore-forming function occurs primarily at the plasma membrane, CX43 is also localised within mitochondria, suggesting a role in cellular adaptation to energy demands and environmental stress. In this study, we investigated the role of mitochondrial CX43 (mt-CX43) in glioma cell lines. We found that mt-CX43 levels vary depending on cell density and extracellular pH. Furthermore, the import of CX43 into mitochondria requires a transport system involving heat shock protein 90 (HSP90). Inhibition of this system with geldanamycin caused a consistent reduction in mt-CX43, which was associated with alterations in mitochondrial structure and metabolic pathways, including purine metabolism and NADH turnover. Our findings suggest that mt-CX43 is required for cellular adaptation to metabolic stress and that modulating mt-CX43 may represent a novel strategy to disrupt tumour survival mechanisms and improve glioma treatment.