Type 1 diabetes (T1D) arises from autoimmune-mediated destruction of insulin-producing β cells, driven in part by endoplasmic reticulum (ER) stress and chronic unfolded protein response (UPR). We previously found that mesencephalic astrocyte-derived neurotrophic factor (MANF), an ER stress-regulating protein with protective and immunomodulatory roles, is essential for mouse and human β cell survival and proliferation. To assess the therapeutic potential of elevated endogenous MANF, we generated β cell-specific transgenic MANF-overexpressing mice and induced diabetes using multiple low-dose streptozotocin (MLDS) injections. In this study, we demonstrate that elevated MANF levels protected against MLDS-induced hyperglycemia, preserved β cell mass, enhanced proliferation, and reduced β cell DNA damage responses and islet lymphocyte infiltration. Transcriptomic profiling of MANF-overexpressing islets revealed downregulation of genes linked to ER and oxidative stress, inflammation, immune responses, antigen presentation, and p53-mediated senescence. Immunophenotyping further showed a reduction in CD4+ T cells in pancreatic lymph nodes. Mechanistically, elevated MANF suppressed MLDS-induced terminal UPR markers, including DNA damage inducible transcript 3 (Ddit3) and thioredoxin-interacting protein (TXNIP) expression, whereas MANF deficiency elevated their expression in β cells. Collectively, these findings identify MANF as a dual-acting therapeutic target that alleviates β cell stress and reduces immunogenicity in T1D.

[This corrects the article DOI: 10.1016/j.bbih.2025.101149.].

Modelling of human neurological diseases uses a plethora of ever-more sophisticated methods and approaches. For Huntington’s disease (HD), which affects specific neuronal types and circuits in the brain, this has meant the use of both neurotoxic compounds and various animal models of different complexity, ranging from rodents to non-primate ones. Genetic models are classified based on the use of specific constructs including gene including gene fragments, full-length, knock-out and knock-in models. In this review, we will discuss the available animal models for HD, highlighting their pros and cons in studying the neuropathology, behavioural alterations, and biological mechanisms that prevail in HD and during the disease progression. We also highlight present knowledge gaps and difficulties to fully recapitulate the human disease. At the end we will further elaborate on current outstanding questions in HD research that warrant further studies using both animal models and patient data. This may help to guide future research and increase the translational relevance of the models to solve key questions and pave the way for better treatment options and design of drugs to alleviate the course of HD.

Non-invasive delivery of brain therapeutics is a key challenge for treating neurodegenerative diseases. Here, we discovered a novel carboxy (C)-terminal fragment of cerebral dopamine neurotrophic factor (C-CDNF) that protects dopamine (DA) and motoneurons (MNs) in rodent models of Parkinsons disease (PD) and amyotrophic lateral sclerosis (ALS). C-CDNF retains the same structure as CDNF and similarly to CDNF regulates cell stress pathways but unorthodoxly enters cultured neurons and passes through the blood-brain barrier. In vivo, intracranially or peripherally delivered C-CDNF improves motor deficits, protects DA neurons, and restores motor behavior in a rat model of PD. Subcutaneous C-CDNF also protects MNs and reduces microglial activation in an ALS model. Based on our findings, beginning C-CDNF treatment soon after diagnosis is anticipated to delay progression of PD and ALS, thereby improving treatment outcome. Thus, systemic delivery of C-CDNF should simplify the administration of protein-based therapeutics to patients while reducing treatment risk and financial burden for patients and families. ### Competing Interest Statement LY, MA, MS and MHV own the patent rights and are inventors in C-CDNF-related patent applications

Inflammation in multiple sclerosis leads to chronic activation of a cellular stress mechanism, the unfolded protein response (UPR), which is thought to both exacerbate neuroinflammation and prevent regenerative tissue responses such as remyelination. The UPR-modulating protein MANF has shown great promise for attenuating chronic UPR activation and enhancing tissue regeneration in various disease models but does not reach the CNS when given peripherally. We utilized C-MANF, a C-terminal fragment of MANF, and showed that subcutaneous administration of C-MANF promoted motor function recovery and tissue regeneration in a mouse model of autoimmune demyelination. We demonstrated that C-MANF suppresses neuroinflammatory activation and facilitates the recovery of oligodendrocytes after demyelination, while reducing long-term activation of the UPR. Furthermore, we showed that C-MANF enhances myelination of primary OPCs in culture, that promotion of remyelination in cerebellar organotypic slice cultures is dependent on UPR-modulation, and that exogenously applied C-MANF suppresses chronic activation of all three UPR pathways in oligodendroglia. Finally, we showed that demyelination in MANF-deficient brains leads to extensive neuroinflammation and CNS degeneration, implicating UPR modulation by MANF as a key component in tissue responses to demyelination. Altogether, we show that UPR modulation with C-MANF is a promising new therapeutic approach for treating neuroinflammatory demyelination.

Chondroitin sulfate proteoglycans (CSPGs) are inhibitory molecules deposited in the extracellular matrix of lesions in multiple sclerosis (MS). CSPGs maintain ongoing inflammatory processes and prevent oligodendrocyte progenitor cell (OPC) differentiation, resulting in impaired remyelination and chronic pathology in MS. Here, we profile low-molecular weight protamine (LMWP) as a small, positively charged peptide that binds to the negatively charged inhibitory sections of CSPGs. We show that LMWP overcomes CSPG inhibition of OPC differentiation and increases remyelination following toxin-based focal demyelination. Moreover, LMWP ameliorates disease progression in experimental autoimmune encephalomyelitis (EAE) model. LMWP is blood brain barrier-penetrant, and peripheral administration in EAE mice results in significantly lowered concentrations of serum neurofilament light-chain. Additionally, tissue analyses show increased myelin thickness and a reduction in axonal degeneration with LMWP treatment in EAE mice, supporting its role as a neuroprotective compound. Finally, LMWP reduces microgliosis and fibrosis in EAE, most likely, favoring tissue repair. Thus, LMWP supports remyelination as well as neuroprotection resulting in a promising strategy for the treatment of demyelinating disease, such as MS.

Cerebral dopamine neurotrophic factor (CDNF) and its close structural relative, mesencephalic astrocyte-derived neurotrophic factor (MANF), are proteins with neurotrophic properties. CDNF protects and restores the function of dopamine (DA) neurons in rodent and non-human primate (NHP) toxin models of Parkinson's disease (PD) and therefore shows promise as a drug candidate for disease-modifying treatment of PD. Moreover, CDNF was found to be safe and to have some therapeutic effects on PD patients in phase 1/2 clinical trials. However, the mechanism underlying the neurotrophic activity of CDNF is unknown. In this study, we delivered human CDNF (hCDNF) to the brain using an adeno-associated viral (AAV) vector and demonstrated the neurotrophic effect of AAV-hCDNF in an acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. AAV-hCDNF resulted in the expression of hCDNF in the striatum (STR) and substantia nigra (SN), and no toxic effects on the nigrostriatal pathway were observed. Intrastriatal injection of AAV-hCDNF reduced motor impairment and partially alleviated gait dysfunction in the acute MPTP mouse model. In addition, gene therapy with AAV-hCDNF had significant neuroprotective effects on the nigrostriatal pathway and decreased the levels of interleukin 1beta (IL-1β) and complement 3 (C3) in glial cells in the acute MPTP mouse model. Moreover, AAV-hCDNF reduced C/EBP homologous protein (CHOP) and glucose regulatory protein 78 (GRP78) expression in astroglia. These results suggest that the neuroprotective effects of CDNF may be mediated at least in part through the regulation of neuroinflammation and the UPR pathway in a mouse MPTP model of PD in vivo.

Canopy Homolog 2 (CNPY2) is an endoplasmic reticulum (ER) localized protein belonging to the CNPY gene family. We show here that CNPY2 is protective against ER stress induced by tunicamycin in neuronal cells. Overexpression of CNPY2 enhanced, while downregulation of CNPY2 using shRNA expression, reduced the viability of neuroblastoma cells after tunicamycin. Likewise, recombinant CNPY2 increased survival of cortical neurons in culture after ER stress. CNPY2 reduced the activating transcription factor 6 (ATF6) branch of ER stress and decreased the expression of CCAT/Enhancer-Binding Protein Homologous Protein (CHOP) involved in cell death. Immunostaining using mouse brain sections revealed that CNPY2 is expressed by cortical and striatal neurons and is co-expressed with the transcription factor, COUPTF-interacting protein 2 (CTIP2). In transgenic N171-82Q mice, as a model for Huntington’s disease (HD), the number of CNPY2-immunopositive neurons was increased in the cortex together with CTIP2. In the striatum, however, the number of CNPY2 decreased at 19 weeks of age, representing a late-stage of pathology. Striatal cells in culture were shown to be more susceptible to ER stress after downregulation of CNPY2. These results demonstrate that CNPY2 is expressed by corticostriatal neurons involved in the regulation of movement. CNPY2 enhances neuronal survival by reducing ER stress and is a promising factor to consider in HD and possibly in other brain diseases.

The electrochemical analysis is one of the most popular implementations of a dopamine-sensing brain implant. Its performance depends significantly on the interaction between the dopamine molecule and the working electrode. Carbon nanofiber is an allotrope of carbon nanotube and is effective in increasing the contact surface with dopamine molecules. Considering its simple fabrication protocols using photolithography, physical vapor deposition, and electrochemical deposition, this material is suitable for in-vivo implementation. COMSOL simulation confirms that carbon nanofiber implementation increases the redox current while maintaining its linearity to the user-controlled dopamine concentration.

The role of front-end electrode sensors for dopamine-detection brain implants is significant for the entire measurement process. The electrode material determines the sensitivity, selectivity, and longevity of the implant. Carbon-based electrode induces better dopamine adsorption due to π-interaction. We tested carbon fiber microelectrode (CFME) on a set of dopamine solution concentrations (1 mM to 0.01 mM) to determine its limit of detection and its reliability for quantitative analysis. The raw signal is processed using ∆Σ-converter and the concentration is estimated using a linear regression technique. The wireless feature is incorporated with a triple-band antenna at frequencies of 402, 902, and 2450 MHz for data communications, wireless power transmission, and switching control.

Huntington’s disease (HD) is a progressive inherited neurological disease characterized by the degeneration of basal ganglia and the accumulation of mutant huntingtin (mHtt) aggregates in specific brain areas. Currently, there is no treatment for halting the progression of HD. Cerebral dopamine neurotrophic factor (CDNF) is a novel endoplasmic reticulum located protein with neurotrophic factor properties that protects and restores dopamine neurons in rodent and non-human primate models of Parkinson’s disease. Our recent study showed that CDNF improves motor coordination and protects NeuN positive cells in a Quinolinic acid toxin rat model of HD. Here we have investigated the effect of chronic intrastriatal CDNF administration on behavior and mHtt aggregates in the N171-82Q mouse model of HD. Data showed that CDNF did not significantly decrease the number of mHtt aggregates in most brain regions studied. Notably, CDNF significantly delayed the onset of symptoms and improved motor coordination in N171-82Q mice. Furthermore, CDNF increased BDNF mRNA level in hippocampus in vivo in the N171-82Q model and BDNF protein level in cultured striatal neurons. Collectively our results indicate that CDNF might be a potential drug candidate for the treatment of HD.

The existent pre-clinical models of Parkinson's disease do not simultaneously recapitulate severe degeneration of dopamine neurons and the occurrence of alpha-synuclein (aSyn) aggregation in one study system. In this study, we injected aSyn pre-formed fibrils (PFF) and 6-hydroxydopamine (6-OHDA) unilaterally into the striatum of C57BL/6 wild-type male mice at an interval of 2 weeks to induce aggregation of aSyn protein and trigger the loss of dopamine neurons simultaneously in one model and studied the behavioural effects of the combination in these mice. 6-OHDA was tested at three different doses, and 2 μg of 6-OHDA combined with PFF-induced aSyn aggregation was found to produce the most optimal disease phenotype. At 14 weeks timepoint, mice injected with a combination of PFF and 6-OHDA sustained significant damage to the nigrostriatal pathway and exhibited aSyn-positive aggregation. Our data suggest that the neurons that formed large aSyn aggregates were particularly vulnerable to 6-OHDA-induced degeneration. We also demonstrate the manifestation of a relatively aggressive pathology in 2- to 4-month-old mice, as compared to younger 7- to 9-week-old ones. Furthermore, cerebral dopamine neurotrophic factor (CDNF) administered intrastriatally rescued dopamine neurons and motor behaviour of the animals to some extent from 6-OHDA toxicity. However, no such effect could be seen in the novel 6-OHDA + PFFs combination model. For the first time, we demonstrate the combined effect of PFF and 6-OHDA simultaneously in one model. We further discuss the scope for further optimizing this combination model to develop it as a promising pre-clinical platform for drug screening and development.

Abstract Amyotrophic lateral sclerosis is a progressive neurodegenerative disease that affects motor neurons in the spinal cord, brainstem and motor cortex, leading to paralysis and eventually to death within 3–5 years of symptom onset. To date, no cure or effective therapy is available. The role of chronic endoplasmic reticulum stress in the pathophysiology of amyotrophic lateral sclerosis, as well as a potential drug target, has received increasing attention. Here, we investigated the mode of action and therapeutic effect of the endoplasmic reticulum-resident protein cerebral dopamine neurotrophic factor in three preclinical models of amyotrophic lateral sclerosis, exhibiting different disease development and aetiology: (i) the conditional choline acetyltransferase-tTA/TRE-hTDP43-M337V rat model previously described; (ii) the widely used SOD1-G93A mouse model; and (iii) a novel slow-progressive TDP43-M337V mouse model. To specifically analyse the endoplasmic reticulum stress response in motor neurons, we used three main methods: (i) primary cultures of motor neurons derived from embryonic Day 13 embryos; (ii) immunohistochemical analyses of spinal cord sections with choline acetyltransferase as spinal motor neuron marker; and (iii) quantitative polymerase chain reaction analyses of lumbar motor neurons isolated via laser microdissection. We show that intracerebroventricular administration of cerebral dopamine neurotrophic factor significantly halts the progression of the disease and improves motor behaviour in TDP43-M337V and SOD1-G93A rodent models of amyotrophic lateral sclerosis. Cerebral dopamine neurotrophic factor rescues motor neurons in vitro and in vivo from endoplasmic reticulum stress-associated cell death and its beneficial effect is independent of genetic disease aetiology. Notably, cerebral dopamine neurotrophic factor regulates the unfolded protein response initiated by transducers IRE1α, PERK and ATF6, thereby enhancing motor neuron survival. Thus, cerebral dopamine neurotrophic factor holds great promise for the design of new rational treatments for amyotrophic lateral sclerosis.

N6-Methyladenosine (m6A) is the most common mRNA base modification in eukaryotes. Methylation of adenosine residues to m6A contributes to the regulation of splicing, transport, stability, and translation of mRNA and two main classes of enzymes regulate it. The formation of m6A is catalysed by a methyltransferase complex containing methyltransferase-like 3 (METTL3), METTL14, and Wilms’ tumour 1-associated protein (WTAP) as well as monomeric METTL16. Demethylation of m6A is catalysed by the fat mass and obesity-associated protein FTO and the RNA demethylase AlkB homolog 5 (ALKBH5). The m6A mRNA methylation dysregulation occurs in the nervous system and in Parkinson’s disease (PD), but it remains poorly studied. Moreover, the role of m6A mRNA methylation in neuronal survival, neuroprotection, and neuroregeneration is unclear. We have earlier used high-throughput virtual screening of large compound libraries and identified four unique small-molecule ligands that activate m6A mRNA methylation by binding to the METTL3/14/WTAP complex and enhancing the binding of the methylation substrate SAM to nanomolar concentrations. Following this, we now discovered that two methyltransferase activators at 10 nM concentrations supported the survival and protected dopamine (DA) neurons in culture in growth factor deprivation and 6-hydroxydopamine (6-OHDA) neurotoxin models. In contrast, METTL3/14 inhibitor STM2457 triggered death of DA neurons. For clinical translation we also tested the most efficient compound C4 on induced pluripotent stem cell-derived human DA neurons and in animal model of Parkinson’s disease (PD). C4 compound protected human DA neurons from 6-OHDA-induced cell death and increased neurite outgrowth and the number of processes demonstrating that it has both neuroprotective and neurorestorative properties. METTL3/14 activator C4 improved motor behaviour and protected DA neurons and their fibres faster and much more efficiently than GDNF in the rat 6-OHDA model of PD. These are the first specific activators of METTL3/14/WTAP and first demonstration that m6A regulators can protect and regenerate neurons. These data demonstrate that m6A mRNA methylation is a novel pathway regulating neuronal survival and regeneration.

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER)-located protein with cytoprotective effects in neurons and pancreatic β cells in vitro and in models of neurodegeneration and diabetes in vivo. However, the exact mode of MANF action has remained elusive. Here, we show that MANF directly interacts with the ER transmembrane unfolded protein response (UPR) sensor IRE1α, and we identify the binding interface between MANF and IRE1α. The expression of wild-type MANF, but not its IRE1α binding-deficient mutant, attenuates UPR signaling by decreasing IRE1α oligomerization; phosphorylation; splicing of Xbp1, Atf6, and Txnip levels; and protecting neurons from ER stress-induced death. MANF-IRE1α interaction and not MANF-BiP interaction is crucial for MANF pro-survival activity in neurons in vitro and is required to protect dopamine neurons in an animal model of Parkinson’s disease. Our data show IRE1α as an intracellular receptor for MANF and regulator of neuronal survival.

Parkinson's disease (PD) is characterized by the loss of nigrostriatal dopamine (DA) neurons and the presence of alpha-synuclein (αSyn)-positive Lewy body (LB) pathology. In this study, we attempted to recapitulate both these features in a novel in vitro model for PD. To achieve this, we combined the αSyn pre-formed fibril (PFF)-seeded LB-like pathology with 6-hydroxydopamine (6-OHDA)-induced mitochondrial toxicity in mouse embryonic midbrain cultures. To pilot the model for therapeutics testing, we assessed the effects of cerebral dopamine neurotrophic factor (CDNF) on αSyn aggregation and neuron survival. PFF-seeded pathology did not lead to DA neuron loss even with the highest dose of PFFs. The combination of PFFs and 6-OHDA did not trigger additional neurodegeneration or LB-like pathology and instead presented DA neuron loss to a similar extent as with 6-OHDA only. CDNF did not affect the PFF-seeded αSyn pathology or the DA neuron survival in the combination model but showed a trend toward neuroprotection in the 6-OHDA-only cultures.

In Parkinson's disease (PD), dopamine neurons degenerate in the Substantia Nigra, and there is a reduction of dopamine in the caudate-putamen. The diagnosis of PD is principally clinical, although specific investigations (such as PET scans) can help the differential diagnosis from other forms of parkinsonism. A brain implant that enables continuous dopamine monitoring would be helpful for Parkinson's disease patients. We address an RFID-based solution for data transmission and power transfer that facilitate the implementation of a fully implantable and batteryless brain implant. The wireless operation takes place on three frequency bands of 402, 902, and 2400 MHz for data telemetry, power transfer, and switching control, respectively.

In this paper and presentation, we will focus on different aspects of backscattering-based wireless communication and power transfer to small biomedical implants. We will present three different antenna topologies for data and power transfer through tissue, in vitro and in vivo studies on implantable intracranial pressure (ICP) sensors and give insight and analysis on wireless link reliability in tissue environment. We will also present radio frequency identification (RFID) -based implant platform and communication method. Moreover, we will focus on differences and challenges of in vivo environment compared to laboratory phantoms and tissue models. In our studies, different types of implantable antennas have been tested to investigate reliability, accuracy and sensitivity of the brain implants: a hybrid near field-far field system with a piezoresistive sensor for ICP monitoring, a UHF band spilt-ring resonator system and LC tank based miniature implantable antenna. This paper will present these implant antennas and wireless power transfer in tissue environment present in human head.