Biology subjects

Maffei, M.

Publications and source records attributed to Maffei, M..

10 recordsLinked to original sources

bioRxiv2026

Differential impact of FLASH and conventional radiotherapy on a pivotal metabolic organ: White Adipose Tissue

BACKGROUNDSubcutaneous white adipose tissue (scWAT), a key metabolic and endocrine organ, is inevitably exposed during radiotherapy (RT). While RT is a cornerstone of cancer treatment, its efficacy is limited by toxicity to surrounding healthy tissues. Ultra-high dose rate (FLASH) RT has emerged as a promising modality capable of preserving tumor control while reducing normal tissue damage - the so-called FLASH effect. Clinical evidence indicates that childhood exposure to conventional (CONV) RT is associated with long-term dysmetabolism and WAT dysfunction. However, the impact of FLASH-RT on WAT has not been investigated. AIMTo compare the effects of FLASH- and CONV-RT on adipocyte function and scWAT homeostasis, and to identify molecular and structural changes associated with each modality. METHODSWe evaluated the effects of FLASH- and CONV-RT on adipocytes and scWAT using a dedicated linear accelerator capable of delivering both modalities. Experiments were performed in the human SGBS preadipocyte/adipocyte cell line and in a mouse model subjected to proximal hind limb irradiation, with analyses conducted 70 days post-exposure. RESULTSRT impaired adipogenic differentiation in a dose-dependent manner, with a relative sparing effect of FLASH at 4-8 Gy. Mature adipocytes exhibited radioresistance, with protection by FLASH at 8 Gy. In vivo, both regimens reduced fat mass without affecting body weight, with greater loss following CONV-RT. Transcriptomic profiling of scWAT revealed inflammatory and neurodegenerative signatures after CONV-RT, whereas FLASH-RT induced minimal transcriptional changes. Histological and ultrastructural analyses confirmed increased cellular damage, vacuolization, lipid spill-over, and reduced PLIN1 expression, predominantly in CONV-treated mice. CONCLUSIONSWAT homeostasis is sensitive to conventional RT, whereas FLASH-RT better preserves tissue structure and function, with implications for long-term metabolic health in cancer survivors.

physiology↗

bioRxiv2025

Localized FLASH Radiotherapy Reduces Long-Term Skin and Muscle Damage While Preserving Systemic Homeostasis

Radiotherapy (RT) is a cornerstone treatment for nearly 50% of cancer patients, but its curative potential and safe dosing are constrained by cumulative toxicity to surrounding healthy tissues. Delivering RT at ultra-high dose rates (FLASH-RT) represents a transformative strategy, as it appears to maintain tumor control, while sparing normal tissue. Melanoma is among the most radioresistant tumors, and skin and muscle are invariably exposed during RT, also in case of deep seated tumors. Here, we compared electron FLASH-RT and conventional RT (CONV-RT) in melanoma-bearing and naive mice assessing tumor control, tissue integrity, and systemic homeostasis over the medium to long term. Both modalities achieved comparable tumor suppression. However, CONV-RT induced persistent skin damage, dermal fibrosis, muscle dysfunction and systemic inflammatory-metabolic alterations, while FLASH-RT largely spared normal tissue and systemic balance. Bulk RNA sequencing revealed striking differences: FLASH induced minimal transcriptional disruption in skin and muscle, whereas CONV-RT triggered thousands of differentially expressed genes, including massive activation of fibrosis, inflammation, cell death-related pathways in skin, and broad dysregulation of genes linked to muscle function, remodeling and the unfolded protein response. Histological and ultrastructural analyses corroborated the findings, showing reduced immune infiltration in the skin and preserved tissue architecture both in skin and muscle following FLASH. In conclusion our study not only confirms the protective nature of FLASH but also provides novel mechanistic insights into the cascade linking local injury to systemic dysfunction under CONV-RT, reinforcing the translational potential of FLASH to expand the therapeutic window of radiotherapy. One Sentence SummaryComparative analysis of FLASH and conventional radiotherapy in a murine model of melanoma and naive mice - Therapeutical efficacy, local and systemic effects.

physiology↗

bioRxiv2025

Succinate Modulation as a Novel Mechanism Underlying the Effects of Intermittent Fasting on Brain Function and Metabolism in Diet-Induced Obesity

Obesity significantly impacts the central nervous system (CNS), increasing risks of neuropsychiatric disorders and dementia. Intermittent fasting (IF) shows promise for improving peripheral and CNS health, but its mechanisms are unclear. Using a diet-induced obesity mouse model (10 weeks high fat diet (HFD), then 4 weeks intervention), we compared HFD, HFD-IF, ad libitum control chow (CC), and CC-IF groups. Switching to CC or IF reduced body weight, fat mass, and improved glucose tolerance. Notably, CC-IF uniquely enhanced exploration and reduced anxiety-like behavior. Transcriptomics revealed HFD-induced hippocampal neuroinflammation, while metabolomics identified a specific succinate signature in CC-IF mice: plasma concentration decreased while liver and brown adipose tissue (BAT) levels increased. Succinate supplementation mimicked CC-IF metabolic and behavioral benefits and reduced hippocampal inflammation. These findings suggest that regulating plasma succinate and its metabolism in liver and BAT may represent a novel mechanism underlying the metabolic, neuroinflammatory, and behavioral improvements induced by IF.

neuroscience↗

bioRxiv2022

Relevance of the viral Spike protein/cellular Estrogen Receptor-α interaction for endothelial-based coagulopathy induced by SARS-CoV-2

Severe coagulopathy has been observed at the level of the microcirculation in several organs including lungs, heart and kidneys in patients with COVID-19, and in a minority of subjects receiving the SARS-CoV-2 vaccine. Various mechanisms have been implicated in these effects, including increases in circulating neutrophil extracellular traps, excessive inflammation, and endothelial dysfunction. Even if a correlation between infection by SARS-CoV-2 and upregulation of coagulation cascade components has been established in the lung, no direct proofs have been yet provided about the transcriptional machinery controlling the expression of these factors. Recent results obtained by us reported a novel transcriptional function of the SARS-CoV-2 Spike (S) viral protein involving a direct protein-protein interaction with the human Estrogen Receptor- (ER). Given the implications of ER in the control of key effectors in the coagulation cascade, we hypothesized that S-protein might increase the pro-coagulation activity of endothelial cells via the transcriptional activity of the ER, thus justifying the enhanced risk of thrombosis. To assess this, we tested the effects of S-protein on the expression of Tissue Factor (TF) and the overall procoagulation activity in a human endothelial cell line and confirmed this finding by overexpressing S-protein by gene transfer in mice. We then designed and tested two-point mutations in the S2 S-protein sequence that abolished the pro-coagulation function of S-protein in vitro and in vivo, without compromising its immunogenicity. In addition to reveal a new potential transcriptional function of S-protein, these results inspire the design of new vaccines with lower risk of thrombogenesis. Indeed, while the benefit/risk ratio remains overwhelming in favor of COVID-19 vaccination, our results shed light on the causal mechanisms of some rare anti-SARS-CoV-2 vaccine adverse events, and are thus essential for current and future vaccination and booster campaigns.

cell biology↗

bioRxiv2021

The nuts and bolts of SARS-CoV-2 Spike Receptor Binding Domain heterologous expression

COVID-19 is a highly infectious disease caused by a newly emerged coronavirus (SARS-CoV-2) that has rapidly progressed into a pandemic. This unprecedent emergency has stressed the significance of developing effective therapeutics to fight current and future outbreaks. The receptor-binding domain (RBD) of the SARS-CoV-2 surface Spike protein is the main target for vaccines and represents a helpful "tool" to produce neutralizing antibodies or diagnostic kits. In this work, we provide a detailed characterization of the native RBD produced in three major model systems: Escherichia coli, insect and HEK-293 cells. Circular dichroism, gel filtration chromatography and thermal denaturation experiments indicated that recombinant SARS-CoV-2 RBD proteins are stable and correctly folded. In addition, their functionality and receptor-binding ability were further evaluated through ELISA, flow cytometry assays and bio-layer interferometry.

biochemistry↗

bioRxiv2021

COVID-eVax, an electroporated plasmid DNA vaccine candidate encoding the SARS-CoV-2 Receptor Binding Domain, elicits protective immune responses in animal models of COVID-19

The COVID-19 pandemic caused by the {beta}-coronavirus SARS-CoV-2 has made the development of safe and effective vaccines a critical global priority. To date, four vaccines have already been approved by European and American authorities for preventing COVID-19 but the development of additional vaccine platforms with improved supply and logistics profiles remains a pressing need. Here we report the preclinical evaluation of a novel COVID-19 vaccine candidate based on the electroporation of engineered, synthetic cDNA encoding a viral antigen in the skeletal muscle, a technology previously utilized for cancer vaccines. We constructed a set of prototype DNA vaccines expressing various forms of the SARS-CoV-2 Spike (S) protein and assessed their immunogenicity in animal models. Among them, COVID-eVax - a DNA plasmid encoding a secreted monomeric form of SARS-CoV-2 S protein RBD - induced the most potent anti-SARS-CoV-2 neutralizing antibody responses (including against the current most common variants of concern) and a robust T cell response. Upon challenge with SARS-CoV-2, immunized K18-hACE2 transgenic mice showed reduced weight loss, improved pulmonary function and significantly lower viral replication in the lungs and brain. COVID-eVax conferred significant protection to ferrets upon SARS-CoV-2 challenge. In summary, this study identifies COVID-eVax as an ideal COVID-19 vaccine candidate suitable for clinical development. Accordingly, a combined phase I-II trial has recently started in Italy.

immunology↗

bioRxiv2021

Regulation of Src tumor activity by its N-terminal intrinsically disordered region

The membrane anchored Src tyrosine kinase is involved in numerous pathways and its deregulation is involved in human cancer. Our knowledge on Src regulation relies on crystallography, which revealed intramolecular interactions to control active Src conformations. However, Src contains a N-terminal intrinsically disordered unique domain (UD) whose function remains unclear. Using NMR, we reported that UD forms an intramolecular fuzzy complex involving a conserved region with lipid-binding capacity named Unique Lipid Binding Region (ULBR), which could modulate Src membrane anchoring. Here we show that the ULBR is essential for Srcs oncogenic capacity. ULBR inactive mutations inhibited Src transforming activity in NIH3T3 cells and in human colon cancer cells. It also reduced Src-induced tumor development in nude mice. An intact ULBR was required for MAPK signaling without affecting Src kinase activity nor sub-cellular localization. Phospho-proteomic analyses revealed that, while not impacting on the global tyrosine phospho-proteome in colon cancer cells, this region modulates phosphorylation of specific membrane-localized tyrosine kinases needed for Src oncogenic signaling, including EPHA2 and Fyn. Collectively, this study reveals an important role of this intrinsically disordered region in malignant cell transformation and suggests a novel layer of Src regulation by this unique region via membrane substrate phosphorylation.

cancer biology↗

bioRxiv2019

NGF-mediated photoablation of nociceptors reduces pain behavior in mice

Nerve growth factor (NGF) and its receptors TrkA and p75 play a key role in the development and function of peripheral nociceptive neurons. Here we describe novel technology to selectively photoablate TrkA positive nociceptors through delivery of a phototoxic agent coupled to an engineered NGF ligand and subsequent near infrared (NIR) illumination. We demonstrate that this approach allows for on demand and localized reversal of pain behaviors in mouse models of acute, inflammatory, neuropathic and joint pain. To target peripheral nociceptors we generated a SNAP-tagged NGF derivative, NGFR121W that binds to TrkA/p75 receptors but does not provoke signaling in TrkA positive cells or elicit pain behaviors in mice. NGFR121W-SNAP was coupled to the photosensitizer IRDye(R)700DX phthalocyanine (IR700) and injected subcutaneously. Following NIR illumination of the injected area, behavioral responses to nociceptive mechanical and sustained thermal stimuli, but not innocuous stimuli, were substantially reduced. Similarly, in models of inflammatory, osteoarthritic and neuropathic pain, mechanical hypersensitivity was abolished for three weeks following a single treatment regime. We demonstrate that this loss of pain behavior coincides with the retraction of neurons from the skin which then re-innervate the epidermis after 3 weeks corresponding with the return of mechanical hypersensitivity. Thus NGFR121W-SNAP-mediated photoablation is a minimally invasive approach to reversibly silence nociceptor input from the periphery, and control pain and hypersensitivity to mechanical stimuli.

neuroscience↗

bioRxiv2017

Control of mechanical pain hypersensitivity through ligand-targeted photoablation of TrkB positive sensory neurons

SummaryMechanical allodynia is a major symptom of neuropathic pain whereby innocuous touch evokes severe pain. Here we identify a population of peripheral sensory neurons expressing TrkB that are both necessary and sufficient for producing pain from light touch after nerve injury. Mice in which TrkB-Cre expressing neurons are ablated are less sensitive to the lightest touch under basal conditions, and fail to develop mechanical allodynia in a model of neuropathic pain. Moreover, selective optogenetic activation of these neurons after nerve injury evokes marked nociceptive behavior. Using a phototherapeutic approach based upon BDNF, the ligand for TrkB, we perform molecule-guided laser ablation of these neurons and achieve long-term retraction of TrkB positive neurons from the skin and pronounced reversal of mechanical allodynia across multiple types of neuropathic pain. Thus we identify the peripheral neurons which transmit pain from light touch and uncover a novel pharmacological strategy for its treatment.\n\nHighlightsO_LITrkB+ neurons detect light touch under basal conditions\nC_LIO_LITrkB+ neurons convey mechanical allodynia in neuropathic pain states\nC_LIO_LIA photosensitizing derivative of BDNF allows for photoablation of TrkB+ neurons\nC_LIO_LIBDNF-guided photoablation reverses allodynia in multiple types of neuropathic pain\nC_LI

neuroscience↗

bioRxiv2017

Molecule guided laser ablation as a novel therapeutic strategy to control itch.

Itch is a major symptom of many chronic skin diseases that can exacerbate inflammation by provoking excessive scratching and causing skin damage. Here we develop a novel technology to control itch through molecular guided delivery of a phototoxic agent and near infrared (IR) illumination of the skin. Exploiting the selective binding of the pruritogen Interleukin-31 to itch sensing cells, we generate an engineered IL31SNAP ligand derivative (IL31K138A-SNAP) that binds to cells but does not evoke signaling or provoke scratching when injected in vivo. Conjugation of IL31K138A-SNAP to the photosensitizer IRDye(R)700DX phthalocyanine (IR700) and injection of the skin results in long-term reversal of scratching behavior evoked by IL31 upon near IR illumination. We further develop a topical preparation of IL31 K138A-SNAP-IR700 that strikingly, reverses behavioral and dermatological indicators in mouse models of Atopic Dermatitis (AD) and the genetic skin disease Familial Primary Localized Cutaneous Amyloidosis (FPLCA). We demonstrate that this therapeutic effect results from selective retraction of itch sensing neurons in the skin, breaking the cycle of itch and disruption of the skins barrier function. Thus, molecule guided photoablation is a powerful new technology for controlling itch and treating inflammatory skin diseases.

neuroscience↗