Hydrogen sulfide slows down progression of experimental Alzheimer's disease by targeting multiple pathophysiological mechanisms

A novel NIR fluorescent probe for visualizing hydrogen sulfide in Alzheimer's disease

Alzheimer's disease (AD) represents a devastating form of neurodegeneration, hallmarked by a relentless erosion of memory and cognitive faculties. One key player in this complex pathology is hydrogen sulfide (H2S), a gaseous neurotransmitter that is highly concentrated in the brain. Its fluctuating levels have been compellingly linked to the onset and progression of AD. Despite the availability of numerous fluorescent probes for detecting H2S, targeted imaging of this neurotransmitter within AD models remains underexplored. To bridge this gap, we have engineered an innovative near-infrared (NIR) "turn-on" fluorescent probe, designated as probe 1. Crafted around a dicyanoisophorone scaffold, the probe incorporates a strategic methoxy modification to facilitate a bathochromic spectral shift. Impressively, upon binding with H2S, probe 1 exhibited a robust 46-fold enhancement in fluorescence at a wavelength of 680 nm. We successfully deployed this probe to visualize both exogenous and endogenous H2S in living cells and zebrafish. Further, our pathogenic investigations have corroborated that diminished H2S levels are intricately linked to an escalation in amyloid plaque formation. Most crucially, we employed probe 1 to capture real-time images of H2S concentrations within the hippocampal tissue of AD mouse models. This revealed a significant depletion in H2S levels, thereby underscoring the probe's immense potential as an effective tool for the diagnosis and prevention of Alzheimer's disease.

Dual-Mode Ce-MOF Nanozymes for Rapid and Selective Detection of Hydrogen Sulfide in Aquatic Products

Increasing concern over the safety of consumable products, particularly aquatic products, due to freshness issues, has become a pressing issue. Therefore, ensuring the quality and safety of aquatic products is paramount. To address this, a dual-mode colorimetric-fluorescence sensor utilizing Ce-MOF as a mimic peroxidase to detect H2S was developed. Ce-MOF was prepared by a conventional solvothermal synthesis method. Ce-MOF catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by hydrogen peroxide (H2O2) to produce blue oxidized TMB (oxTMB). When dissolved, hydrogen sulfide (H2S) was present in the solution, and it inhibited the catalytic effect of Ce-MOF and caused the color of the solution to fade from blue to colorless. This change provided an intuitive indication for the detection of H2S. Through steady-state dynamic analysis, the working mechanism of this sensor was elucidated. The sensor exhibited pronounced color changes from blue to colorless, accompanied by a shift in fluorescence from none to light blue. Additionally, UV-vis absorption demonstrated a linear correlation with the H2S concentration, ranging from 200 to 2300 µM, with high sensitivity (limit of detection, LOD = 0.262 μM). Fluorescence intensity also showed a linear correlation, ranging from 16 to 320 µM, with high selectivity and sensitivity (LOD = 0.156 μM). These results underscore the sensor's effectiveness in detecting H2S. Furthermore, the sensor enhanced the accuracy of H2S detection and fulfilled the requirements for assessing food freshness and safety.

Protein Oxidative Modifications in Neurodegenerative Diseases: From Advances in Detection and Modelling to Their Use as Disease Biomarkers

Oxidation-reduction post-translational modifications (redox-PTMs) are chemical alterations to amino acids of proteins. Redox-PTMs participate in the regulation of protein conformation, localization and function, acting as signalling effectors that impact many essential biochemical processes in the cells. Crucially, the dysregulation of redox-PTMs of proteins has been implicated in the pathophysiology of numerous human diseases, including neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. This review aims to highlight the current gaps in knowledge in the field of redox-PTMs biology and to explore new methodological advances in proteomics and computational modelling that will pave the way for a better understanding of the role and therapeutic potential of redox-PTMs of proteins in neurodegenerative diseases. Here, we summarize the main types of redox-PTMs of proteins while providing examples of their occurrence in neurodegenerative diseases and an overview of the state-of-the-art methods used for their detection. We explore the potential of novel computational modelling approaches as essential tools to obtain insights into the precise role of redox-PTMs in regulating protein structure and function. We also discuss the complex crosstalk between various PTMs that occur in living cells. Finally, we argue that redox-PTMs of proteins could be used in the future as diagnosis and prognosis biomarkers for neurodegenerative diseases.

An Aggregation-Induced Fluorescence Probe for Detection H2S and Its Application in Cell Imaging

Monitoring hydrogen sulfide (H2S) in living organisms is very important because H2S acts as a regulator in many physiological and pathological processes. Upregulation of endogenous H2S concentration has been shown to be closely related to the occurrence and development of tumors, atherosclerosis, neurodegenerative diseases and diabetes. Herin, a novel fluorescent probe HND with aggregation-induced emission was designed. Impressively, HND exhibited a high selectivity, fast response (1 min) and low detection limit (0.61 μM) for H2S in PBS buffer (10 mM, pH = 7.42). Moreover, the reaction mechanism between HND and H2S was conducted by Job's plot, HR-MS, and DFT. In particular, HND was successfully employed to detect H2S in HeLa cells.

A structural optimized fluorescent probe for monitoring hydrogen sulfide in cells and zebrafish

In this work, we reported a fluorescent probe Fur-SH, a derivative of benzofuranone, which was used to detect H2S in living cells and zebrafish. Based on the three structural characteristics of the probe, the effects of different structural modifications on the optical properties of the fluorophore were compared. Then, the fluorophore Fur-OH was synthesized by modifying diethylamino group with benzofuranone as the main skeleton. With 2,4-dinitrofluorobenzene as the recognition group and diethylamino as the electron donor, the push-pull electron effect occurred with nitro group, which led to fluorescence quenching, and an openable fluorescent probe Fur-SH was formed. The probe Fur-SH (λex = 510 nm; λem = 570 nm) had the advantages of smaller full width at half maxima, rapid response (5 min) and wide pH window. The quantitative properties of the probe were excellent, reaching saturation at 50 equivalents of substrate. The probe Fur-SH showed high sensitivity to H2S, with LOD of 48.9 nM and LOQ of 50 nM. At present, the probe Fur-SH had been applied to fluorescence imaging of MCF-7 cells and zebrafish. By comparing the effects of different structures on the optical properties of fluorophores, this work was expected to be helpful to the development of fluorescent probes in the future.

Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

Hydrogen Sulfide Responsive Phototherapy Agents: Design Strategies and Biological Applications

Hydrogen sulfide (H2S) is one of the critical gasotransmitters, which play important roles in regular physiological processes, especially in vital signaling pathways. However, fluctuations in endogenous H2S concentration can be linked to serious health problems, such as neurodegenerative diseases, cancer, diabetes, inflammation, cardiovascular diseases, and hypertension. Thus, it has attracted a great deal of attention in therapeutic applications, specifically in the field of phototherapy. Photodynamic therapy (PDT) and photothermal therapy (PTT) are two subclasses of phototherapy, which utilize either reactive oxygen species (ROS) or local temperature increase upon irradiation of a photosensitizer (PS) to realize the therapeutic action. Phototherapies offer unique advantages compared to conventional methods; thus, they are highly promising and popular. One of the design principles followed in new generation PSs is to build activity-based PSs, which stay inactive before getting activated by disease-associated stimuli. These activatable PSs dramatically improve the selectivity and efficacy of the therapy. In this review, we summarize small molecule and nanomaterial-based PDT and PTT agents that are activated selectively by H2S to initiate their cytotoxic effect. We incorporate single mode PDT and PTT agents along with synergistic and/or multimodal photosensitizers that can combine more than one therapeutic approach. Additionally, H2S-responsive theranostic agents, which offer therapy and imaging at the same time, are highlighted. Design approaches, working principles, and biological applications for each example are discussed in detail.

Fluorescent dyes based on rhodamine derivatives for bioimaging and therapeutics: recent progress, challenges, and prospects

Since their inception, rhodamine dyes have been extensively applied in biotechnology as fluorescent markers or for the detection of biomolecules owing to their good optical physical properties. Accordingly, they have emerged as a powerful tool for the visualization of living systems. In addition to fluorescence bioimaging, the molecular design of rhodamine derivatives with disease therapeutic functions (e.g., cancer and bacterial infection) has recently attracted increased research attention, which is significantly important for the construction of molecular libraries for diagnostic and therapeutic integration. However, reviews focusing on integrated design strategies for rhodamine dye-based diagnosis and treatment and their wide application in disease treatment are extremely rare. In this review, first, a brief history of the development of rhodamine fluorescent dyes, the transformation of rhodamine fluorescent dyes from bioimaging to disease therapy, and the concept of optics-based diagnosis and treatment integration and its significance to human development are presented. Next, a systematic review of several excellent rhodamine-based derivatives for bioimaging, as well as for disease diagnosis and treatment, is presented. Finally, the challenges in practical integration of rhodamine-based diagnostic and treatment dyes and the future outlook of clinical translation are also discussed.

Transcriptomic Analyses of Neurotoxic Astrocytes Derived from Adult Triple Transgenic Alzheimer's Disease Mice

Neurodegenerative diseases such as Alzheimer's disease have been classically studied from a purely neuronocentric point of view. More recent evidences support the notion that other cell populations are involved in disease progression. In this sense, the possible pathogenic role of glial cells like astrocytes is increasingly being recognized. Once faced with tissue damage signals and other stimuli present in disease environments, astrocytes suffer many morphological and functional changes, a process referred as reactive astrogliosis. Studies from murine models and humans suggest that these complex and heterogeneous responses could manifest as disease-specific astrocyte phenotypes. Clear understanding of disease-associated astrocytes is a necessary step to fully disclose neurodegenerative processes, aiding in the design of new therapeutic and diagnostic strategies. In this work, we present the transcriptomics characterization of neurotoxic astrocytic cultures isolated from adult symptomatic animals of the triple transgenic mouse model of Alzheimer's disease (3xTg-AD). According to the observed profile, 3xTg-AD neurotoxic astrocytes show various reactivity features including alteration of the extracellular matrix and release of pro-inflammatory and proliferative factors that could result in harmful effects to neurons. Moreover, these alterations could be a consequence of stress responses at the endoplasmic reticulum and mitochondria as well as of concomitant metabolic adaptations. Present results support the hypothesis that adaptive changes of astrocytic function induced by a stressed microenvironment could later promote harmful astrocyte phenotypes and further accelerate or induce neurodegenerative processes.

Integration of genome-wide association studies (GWAS) and microbiome data highlights the impact of sulfate-reducing bacteria on Alzheimer's disease

BACKGROUND

observational studies have indicated that gut microbiome dysbiosis was associated with Alzheimer's disease (ad). However, the results are largely inconsistent and it remains unknown whether the association is causal in nature.

METHODS

leveraging observational studies and genome-wide association studies (GWAS) on the gut microbiome in ad patients, we pooled the microbiome data (N = 1,109) to screen the microbiota significantly altered in ad patients and then conducted Mendelian randomisation (MR) study to determine the causal associations between altered microbiota (N = 18,340) and ad using two different ad GWAS datasets (N = 63,926 and N = 472,868) using the inverse variance-weighted (IVW) method.

RESULTS

the combined effect sizes from observational studies showed that 8 phyla, 18 classes, 22 orders, 37 families, 78 genera and 109 species significantly changed in ad patients. Using the MR analysis, we found that two classes, one order, one family and one genus were suggestively associated with ad consistently in two different GWAS datasets. Both observational studies and MR analysis simultaneously showed that Desulfovibrionales (order) and Desulfovibrionaceae (family), which were mainly implicated in dissimilatory sulfate reduction, were significantly associated with an elevated risk of ad.

CONCLUSIONS

our findings demonstrated that the abundance of sulfate-reducing bacteria was increased in ad patients, which was causally linked to an increased risk of ad. Further efforts are warranted to clarify the underlying mechanisms, which will provide new insight into the prevention and treatment of ad.

The Role of Hydrogen Sulfide in Regulation of Cell Death following Neurotrauma and Related Neurodegenerative and Psychiatric Diseases

Injuries of the central (CNS) and peripheral nervous system (PNS) are a serious problem of the modern healthcare system. The situation is complicated by the lack of clinically effective neuroprotective drugs that can protect damaged neurons and glial cells from death. In addition, people who have undergone neurotrauma often develop mental disorders and neurodegenerative diseases that worsen the quality of life up to severe disability and death. Hydrogen sulfide (H₂S) is a gaseous signaling molecule that performs various cellular functions in normal and pathological conditions. However, the role of H₂S in neurotrauma and mental disorders remains unexplored and sometimes controversial. In this large-scale review study, we examined the various biological effects of H₂S associated with survival and cell death in trauma to the brain, spinal cord, and PNS, and the signaling mechanisms underlying the pathogenesis of mental illnesses, such as cognitive impairment, encephalopathy, depression and anxiety disorders, epilepsy and chronic pain. We also studied the role of H₂S in the pathogenesis of neurodegenerative diseases: Alzheimer's disease (AD) and Parkinson's disease (PD). In addition, we reviewed the current state of the art study of H₂S donors as neuroprotectors and the possibility of their therapeutic uses in medicine. Our study showed that H₂S has great neuroprotective potential. H₂S reduces oxidative stress, lipid peroxidation, and neuroinflammation; inhibits processes associated with apoptosis, autophagy, ferroptosis and pyroptosis; prevents the destruction of the blood-brain barrier; increases the expression of neurotrophic factors; and models the activity of Ca²⁺ channels in neurotrauma. In addition, H₂S activates neuroprotective signaling pathways in psychiatric and neurodegenerative diseases. However, high levels of H₂S can cause cytotoxic effects. Thus, the development of H₂S-associated neuroprotectors seems to be especially relevant. However, so far, all H₂S modulators are at the stage of preclinical trials. Nevertheless, many of them show a high neuroprotective effect in various animal models of neurotrauma and related disorders. Despite the fact that our review is very extensive and detailed, it is well structured right down to the conclusions, which will allow researchers to quickly find the proper information they are interested in.

The Ying and Yang of Hydrogen Sulfide as a Paracrine/Autocrine Agent in Neurodegeneration: Focus on Amyotrophic Lateral Sclerosis

Ever since its presence was reported in the brain, the nature and role of hydrogen sulfide (H2S) in the Central Nervous System (CNS) have changed. Consequently, H2S has been elected as the third gas transmitter, along with carbon monoxide and nitric oxide, and a number of studies have focused on its neuromodulatory and protectant functions in physiological conditions. The research on H2S has highlighted its many facets in the periphery and in the CNS, and its role as a double-faced compound, switching from protective to toxic depending on its concentration. In this review, we will focus on the bell-shaped nature of H2S as an angiogenic factor and as a molecule released by glial cells (mainly astrocytes) and non-neuronal cells acting on the surrounding environment (paracrine) or on the releasing cells themselves (autocrine). Finally, we will discuss its role in Amyotrophic Lateral Sclerosis, a paradigm of a neurodegenerative disease.

Hydrogen sulfide signalling in neurodegenerative diseases

The gaseous neurotransmitter hydrogen sulfide (H2 S) exerts neuroprotective efficacy in the brain via post-translational modification of cysteine residues by sulfhydration, also known as persulfidation. This process is comparable in biological impact to phosphorylation and mediates a variety of signalling events. Unlike conventional neurotransmitters, H2 S cannot be stored in vesicles due to its gaseous nature. Instead, it is either locally synthesized or released from endogenous stores. Sulfhydration affords both specific and general neuroprotective effects and is critically diminished in several neurodegenerative disorders. Conversely, some forms of neurodegenerative disease are linked to excessive cellular H2 S. Here, we review the signalling roles of H2 S across the spectrum of neurodegenerative diseases, including Huntington's disease, Parkinson's disease, Alzheimer's disease, Down syndrome, traumatic brain injury, the ataxias, and amyotrophic lateral sclerosis, as well as neurodegeneration generally associated with ageing.

Elevated plasma sulfides are associated with cognitive dysfunction and brain atrophy in human Alzheimer's disease and related dementias

Emerging evidence indicates that vascular stress is an important contributor to the pathophysiology of Alzheimer's disease and related dementias (ADRD). Hydrogen sulfide (H2S) and its metabolites (acid-labile (e.g., iron-sulfur clusters) and bound (e.g., per-, poly-) sulfides) have been shown to modulate both vascular and neuronal homeostasis. We recently reported that elevated plasma sulfides were associated with cognitive dysfunction and measures of microvascular disease in ADRD. Here we extend our previous work to show associations between elevated sulfides and magnetic resonance-based metrics of brain atrophy and white matter integrity. Elevated bound sulfides were associated with decreased grey matter volume, while increased acid labile sulfides were associated with decreased white matter integrity and greater ventricular volume. These findings are consistent with alterations in sulfide metabolism in ADRD which may represent maladaptive responses to oxidative stress.

Reactive Sulfur Species Omics Analysis in the Brain Tissue of the 5xFAD Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder whereby oxidative stress augmentation results in mitochondrial dysfunction and cell death by apoptosis. Emerging evidence indicates that reactive sulfur species (RSS), such as glutathione hydropersulfide (GSSH), is endogenously produced, functions as potent antioxidants, and regulate redox signaling through the formation of protein polysulfides. However, the relationship between RSS and AD pathogenesis is not fully understood. In this study, we analyzed endogenous RSS production in the brain tissue of a familial AD model (5xFAD) mouse using multiple RSS-omics approaches. Memory impairment, increased amyloid plaques, and neuroinflammation have been confirmed in 5xFAD mice. Quantitative RSS omics analysis revealed that the total polysulfide content was significantly decreased in the brains of 5xFAD mice, whereas there was no significant difference in the levels of glutathione, GSSH, or hydrogen sulfide between wild-type and 5xFAD mice. In contrast, a significant decline in the protein polysulfide status was observed in the brains of 5xFAD mice, suggesting that RSS production and subsequent redox signaling might be altered during the onset and progression of AD. Our findings have important implications for understanding the significance of RSS in the development of preventive and therapeutic strategies for AD.

Protective Roles of Hydrogen Sulfide in Alzheimer's Disease and Traumatic Brain Injury

The gaseous signaling molecule hydrogen sulfide (H₂S) critically modulates a plethora of physiological processes across evolutionary boundaries. These include responses to stress and other neuromodulatory effects that are typically dysregulated in aging, disease, and injury. H₂S has a particularly prominent role in modulating neuronal health and survival under both normal and pathologic conditions. Although toxic and even fatal at very high concentrations, emerging evidence has also revealed a pronounced neuroprotective role for lower doses of endogenously generated or exogenously administered H₂S. Unlike traditional neurotransmitters, H₂S is a gas and, therefore, is unable to be stored in vesicles for targeted delivery. Instead, it exerts its physiologic effects through the persulfidation/sulfhydration of target proteins on reactive cysteine residues. Here, we review the latest discoveries on the neuroprotective roles of H₂S in Alzheimer's disease (AD) and traumatic brain injury, which is one the greatest risk factors for AD.

The BDNF-TrkB signaling pathway is partially involved in the neuroprotective effects of hydrogen sulfide in Parkinson's disease

Recent studies have demonstrated that hydrogen sulfide (H₂S) has a neuroprotective effect in neurodegenerative diseases. It is possible that this effect is supported by brain-derived neurotrophic factor (BDNF). Our aim is to examine the effects of H₂S on neural damage in Parkinson's disease (PD) and to reveal the role of the BDNF-TrkB pathway in its possible effect. PD model was created with 1-methyl-phenyl-1,2,3,6-tetrahydropyridine (MPTP). C57BL/6 breed male mice were randomly divided into six groups: control, K252a, MPTP, MPTP + K252a, MPTP + NaHS, and MPTP + NaHS + K252a. TrkB receptor antagonist K252a and sodium hydrosulfide (NaHS) as a H₂S donor were administered intraperitoneally. An increase was observed in the motor behavior tests in MPTP group, but NaHS treatment shortened the time spent on the balance beam and pole tests. It was also noticed that the BDNF-pathway played a role in the shortening of this period. Mice that received NaHS were found to have less MPTP-induced cellular damage. A positive effect of BDNF was also detected in the protection of these neurons. BDNF levels in the SN were significantly increased in MPTP group, compared to control group. Tissue CBS levels decreased in the groups that received K252a, compared to MPTP group. The findings of the present study display that the BDNF-TrkB pathway partially plays a role in the protective effect of H₂S in the experimental mouse model of PD. This effect is probably due to changes in intracellular signaling pathways, rather than TrkB receptor expression.

The Role of Gasotransmitter-Dependent Signaling Mechanisms in Apoptotic Cell Death in Cardiovascular, Rheumatic, Kidney, and Neurodegenerative Diseases and Mental Disorders

Cardiovascular, rheumatic, kidney, and neurodegenerative diseases and mental disorders are a common cause of deterioration in the quality of life up to severe disability and death worldwide. Many pathological conditions, including this group of diseases, are based on increased cell death through apoptosis. It is known that this process is associated with signaling pathways controlled by a group of gaseous signaling molecules called gasotransmitters. They are unique messengers that can control the process of apoptosis at different stages of its implementation. However, their role in the regulation of apoptotic signaling in these pathological conditions is often controversial and not completely clear. This review analyzes the role of nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) in apoptotic cell death in cardiovascular, rheumatic, kidney, and neurodegenerative diseases. The signaling processes involved in apoptosis in schizophrenia, bipolar, depressive, and anxiety disorders are also considered. The role of gasotransmitters in apoptosis in these diseases is largely determined by cell specificity and concentration. NO has the greatest dualism; scales are more prone to apoptosis. At the same time, CO, H₂S, and SO₂ are more involved in cytoprotective processes.

Advances of H2S in Regulating Neurodegenerative Diseases by Preserving Mitochondria Function

Neurotoxicity is induced by different toxic substances, including environmental chemicals, drugs, and pathogenic toxins, resulting in oxidative damage and neurodegeneration in mammals. The nervous system is extremely vulnerable to oxidative stress because of its high oxygen demand. Mitochondria are the main source of ATP production in the brain neuron, and oxidative stress-caused mitochondrial dysfunction is implicated in neurodegenerative diseases. H2S was initially identified as a toxic gas; however, more recently, it has been recognized as a neuromodulator as well as a neuroprotectant. Specifically, it modulates mitochondrial activity, and H2S oxidation in mitochondria produces various reactive sulfur species, thus modifying proteins through sulfhydration. This review focused on highlighting the neuron modulation role of H2S in regulating neurodegenerative diseases through anti-oxidative, anti-inflammatory, anti-apoptotic and S-sulfhydration, and emphasized the importance of H2S as a therapeutic molecule for neurological diseases.

Hydrogen Sulphide-Based Therapeutics for Neurological Conditions: Perspectives and Challenges

Central nervous system (CNS)-related conditions are currently the leading cause of disability worldwide, posing a significant burden to health systems, individuals and their families. Although the molecular mechanisms implicated in these disorders may be varied, neurological conditions have been increasingly associated with inflammation and/or impaired oxidative response leading to further neural cell damages. Therefore, therapeutic approaches targeting these defective molecular mechanisms have been vastly explored. Hydrogen sulphide (H₂S) has emerged as a modulator of both inflammation and oxidative stress with a neuroprotective role, therefore, has gained interest in the treatment of neurological disorders. H₂S, produced by endogenous sources, is maintained at low levels in the CNS. However, defects in the biosynthetic and catabolic routes for H₂S metabolism have been identified in CNS-related disorders. Approaches to restore H₂S availability using H₂S-donating compounds have been recently explored in many models of neurological conditions. Nonetheless, we still need to elucidate the potential for these compounds not only to ameliorate defective biological routes, but also to better comprehend the implications on H₂S delivery, dosage regimes and feasibility to successfully target CNS tissues. Here, we highlight the molecular mechanisms of H₂S-dependent restoration of neurological functions in different models of CNS disease whilst summarising current administration approaches for these H₂S-based compounds. We also address existing barriers in H₂S donor delivery by showcasing current advances in mediating these constrains through novel biomaterial-based carriers for H₂S donors.

Tacrine-Based Hybrids: Past, Present, and Future

Alzheimer's disease (AD) is a neurodegenerative disorder which is characterized by β-amyloid (Aβ) aggregation, τ-hyperphosphorylation, and loss of cholinergic neurons. The other important hallmarks of AD are oxidative stress, metal dyshomeostasis, inflammation, and cell cycle dysregulation. Multiple therapeutic targets may be proposed for the development of anti-AD drugs, and the "one drug-multiple targets" strategy is of current interest. Tacrine (THA) was the first clinically approved cholinesterase (ChE) inhibitor, which was withdrawn due to high hepatotoxicity. However, its high potency in ChE inhibition, low molecular weight, and simple structure make THA a promising scaffold for developing multi-target agents. In this review, we summarized THA-based hybrids published from 2006 to 2022, thus providing an overview of strategies that have been used in drug design and approaches that have resulted in significant cognitive improvements and reduced hepatotoxicity.

Dual-mode biosensing platform for sensitive and portable detection of hydrogen sulfide based on cuprous oxide/gold/copper metal organic framework heterojunction

Hydrogen sulfide (H2S) can not only be regarded as a critical gas signal transduction substance, but also its excess levels can lead to a range of diseases. Currently, the accurate analysis combined with electrochemical (EC) or photothermal (PT) technology for H2S in a complex biological system remains a significant challenge. Herein, an endogenous H2S-triggered heterojunction cuprous oxide/gold/copper metal organic framework (Cu2O/Au/HKUST-1) nanoprobe is designed for dual-mode EC- second near-infrared (NIR-II)/PT analysis in tumor cells with high sensitivity and simplicity. Dual-mode EC quantification - PT is achieved through "off-on" mode of EC and PT signals based on electronic transfer and biosynthesis via an in situ sulfuration reaction. Under the optimum conditions, the EC quantification mode for trace H2S exhibits a wide linear range and an excellent limit of detection of 0.1 μM. More importantly, the dual-mode can display the selective detection of trace H2S in living tumor cells because of the specific interaction between copper ion and H2S. These results provide a new EC-PT promising biosensing platform for noninvasive intelligent detection of H2S in living tumor cells.

Best Medicine for Dementia: The Life-Long Defense of the Brain

This review deals with an unwelcome reality about several forms of dementia, including Alzheimer's disease- that these dementias are caused, in part or whole, by the aging of the vasculature. Since the vasculature ages in us all, dementia is our fate, sealed by the realit!ies of the circulation; it is not a disease with a cure pending. Empirically, cognitive impairment before our 7th decade is uncommon and considered early, while a diagnosis in our 11th decade is late but common in that cohort (>40%). Projections from earlier ages suggest that the prevalence of dementia in people surviving into their 12th decade exceeds 80%. We address the question why so few of many interventions known to delay dementia are recognized as therapy; and we try to resolve this few-and-many paradox, identifying opportunities for better treatment, especially pre-diagnosis. The idea of dementia as a fate is resisted, we argue, because it negates the hope of a cure. But the price of that hope is lost opportunity. An approach more in line with the evidence, and more likely to limit suffering, is to understand the damage that accumulates with age in the cerebral vasculature and therefore in the brain, and which eventually gives rise to cognitive symptoms in late life, too often leading to dementia. We argue that hope should be redirected to delaying that damage and with it the onset of cognitive loss; and, for each individual, it should be redirected to a life-long defense of their brain.

Multiple Actions of H2S-Releasing Peptides in Human β-Amyloid Expressing C. elegans

Alzheimer's disease (AD) is a debilitating progressive neurodegenerative disorder characterized by the loss of cognitive function. A major challenge in treating this ailment fully is its multifactorial nature, as it is associated with effects like deposition of Aβ plaques, oxidative distress, inflammation of neuronal cells, and low levels of the neurotransmitter acetylcholine (ACh). In the present work, we demonstrate the design, synthesis, and biological activity of peptide conjugates by coupling a H₂S-releasing moiety to the peptides known for their Aβ antiaggregating properties. These conjugates release H₂S in a slow and sustained manner, due to the formation of self-assembled structures and delivered a significant amount of H₂S within Caenorhabditis elegans. These conjugates are shown to target multiple factors responsible for the progression of AD: notably, we observed reduction in oxidative distress, inhibition of Aβ aggregation, and significantly increased ACh levels in the C. elegans model expressing human Aβ.

Hydrogen Sulfide (H2S) Signaling as a Protective Mechanism against Endogenous and Exogenous Neurotoxicants

In view of the significant role of H₂S in brain functioning, it is proposed that H₂S may also possess protective effects against adverse effects of neurotoxicants. Therefore, the objective of the present review is to discuss the neuroprotective effects of H₂S against toxicity of a wide spectrum of endogenous and exogenous agents involved in the pathogenesis of neurological diseases as etiological factors or key players in disease pathogenesis. Generally, the existing data demonstrate that H₂S possesses neuroprotective effects upon exposure to endogenous (amyloid β, glucose, and advanced-glycation end-products, homocysteine, lipopolysaccharide, and ammonia) and exogenous (alcohol, formaldehyde, acrylonitrile, metals, 6-hydroxydopamine, as well as 1-methyl-4-phenyl- 1,2,3,6- tetrahydropyridine (MPTP) and its metabolite 1-methyl-4-phenyl pyridine ion (MPP)) neurotoxicants. On the one hand, neuroprotective effects are mediated by S-sulfhydration of key regulators of antioxidant (Sirt1, Nrf2) and inflammatory response (NF-κB), resulting in the modulation of the downstream signaling, such as SIRT1/TORC1/CREB/BDNF-TrkB, Nrf2/ARE/HO-1, or other pathways. On the other hand, H₂S appears to possess a direct detoxicative effect by binding endogenous (ROS, AGEs, Aβ) and exogenous (MeHg) neurotoxicants, thus reducing their toxicity. Moreover, the alteration of H₂S metabolism through the inhibition of H₂S-synthetizing enzymes in the brain (CBS, 3-MST) may be considered a significant mechanism of neurotoxicity. Taken together, the existing data indicate that the modulation of cerebral H₂S metabolism may be used as a neuroprotective strategy to counteract neurotoxicity of a wide spectrum of endogenous and exogenous neurotoxicants associated with neurodegeneration (Alzheimer's and Parkinson's disease), fetal alcohol syndrome, hepatic encephalopathy, environmental neurotoxicant exposure, etc. In this particular case, modulation of H₂S-synthetizing enzymes or the use of H₂S-releasing drugs should be considered as the potential tools, although the particular efficiency and safety of such interventions are to be addressed in further studies.

Functionalization strategies of polymeric nanoparticles for drug delivery in Alzheimer’s disease: Current trends and future perspectives

Alzheimer’s disease (AD), the most common form of dementia, is a progressive and multifactorial neurodegenerative disorder whose primary causes are mostly unknown. Due to the increase in life expectancy of world population, including developing countries, AD, whose incidence rises dramatically with age, is at the forefront among neurodegenerative diseases. Moreover, a definitive cure is not yet within reach, imposing substantial medical and public health burdens at every latitude. Therefore, the effort to devise novel and effective therapeutic strategies is still of paramount importance. Genetic, functional, structural and biochemical studies all indicate that new and efficacious drug delivery strategies interfere at different levels with various cellular and molecular targets. Over the last few decades, therapeutic development of nanomedicine at preclinical stage has shown to progress at a fast pace, thus paving the way for its potential impact on human health in improving prevention, diagnosis, and treatment of age-related neurodegenerative disorders, including AD. Clinical translation of nano-based therapeutics, despite current limitations, may present important advantages and innovation to be exploited in the neuroscience field as well. In this state-of-the-art review article, we present the most promising applications of polymeric nanoparticle-mediated drug delivery for bypassing the blood-brain barrier of AD preclinical models and boost pharmacological safety and efficacy. In particular, novel strategic chemical functionalization of polymeric nanocarriers that could be successfully employed for treating AD are thoroughly described. Emphasis is also placed on nanotheranostics as both potential therapeutic and diagnostic tool for targeted treatments. Our review highlights the emerging role of nanomedicine in the management of AD, providing the readers with an overview of the nanostrategies currently available to develop future therapeutic applications against this chronic neurodegenerative disease.

Exogenous hydrogen sulfide restores CSE and CBS but no 3-MST protein expression in the hypothalamus and brainstem after severe traumatic brain injury

Hydrogen sulfide (H₂S) is a gasotransmitter endogenously synthesized by cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS), and 3-mercaptopiruvate sulfurtransferase (3-MST) enzymes. H₂S exogenous administration prevents the development of hemodynamic impairments after traumatic brain injury (TBI). Since the hypothalamus and the brainstem highly regulate the cardiovascular system, this study aimed to evaluate the effect of NaHS subchronic treatment on the changes of H₂S-sythesizing enzymes in those brain areas after TBI and in physiological conditions. For that purpose, animals were submitted to a lateral fluid percussion injury, and the changes in CBS, CSE, and 3-MST protein expression were measured by western blot at days 1, 2, 3, 7, and 28 in the vehicle group, and 7 and 28 days after NaHS treatment. After severe TBI induction, we found a decrease in CBS and CSE protein expression in the hypothalamus and brainstem; meanwhile, 3-MST protein expression diminished only in the hypothalamus compared to the Sham group. Remarkably, i.p. daily injections of NaHS, an H₂S donor, (3.1 mg/kg) during seven days: (1) restored CBS and CSE but no 3-MST protein expression in the hypothalamus at day 28 post-TBI; (2) reestablished only CSE in brainstem 7 and 28 days after TBI; and (3) did not modify H₂S-sythesizing enzymes protein expression in uninjured animals. Mainly, our results show that the NaHS effect on CBS and CSE protein expression is observed in a time- and tissue-dependent manner with no effect on 3-MST expression, which may suggest a potential role of H₂S synthesis in hypothalamus and brainstem impairments observed after TBI.

Biological activity and molecular docking studies of some N-phenylsulfonamides against cholinesterases and carbonic anhydrase isoenzymes

In this research, a series of N-phenylsulfonamide derivatives (1-12) were designed, synthesized and investigated for their inhibitory potencies against carbonic anhydrase isoenzymes I, II and IX (hCA I, hCA II, and hCA IX) and cholinesterases (ChE), namely, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). These compounds, whose inhibition potentials were evaluated for the first time, were characterized by spectroscopic techniques (¹ H- and ¹³ C NMR and FT-IR). CA isoenzyme inhibitors are significant therapeutic targets, especially owing to their preventive/activation potential in the therapy processes of some diseases such as cancer, osteoporosis, and glaucoma. On the other hand, Cholinesterase inhibitors are valuable molecules with biological importance that can be employed in the therapy process of Alzheimer's patients. The results showed that the tested molecules had enzyme inhibition activities ranging from 9.7 to 93.7 nM against these five metabolic enzymes. Among the tested molecules, the methoxy and the hydroxyl group-containing compounds 10, 11, and 12 exhibited more enzyme inhibition activities when compared to standard compounds acetazolamide (AAZ), sulfapyridine, and sulfadiazine for CA isoenzymes and neostigmine for ChE, respectively. Of these three molecules, compound 12, which had a hydroxyl group in the para position in the aromatic ring, was determined to be the most active molecule against all enzymes. In silico work, molecular docking has also shown similar results and consistent with the experimental data in the study. As a result, we can say that some of the tested molecules might be used as promising inhibitor candidates for further studies on this topic.

Eustachian tube insufflation with thermal water: Effectiveness in the treatment of pediatric otitis media with effusion

PURPOSE

Otitis media with effusion (OME) is the most common ear disease in childhood. The hearing loss associated with OME impacts on children's language development and behavior. Eustachian tube insufflation are among possible treatments for OME, but data regarding their effectiveness are scarce. The aim of this investigation was to analyze the effect of inhalatory thermal therapy and Eustachian tube insufflation in a consecutive cohort of pediatric patients with OME.

MATERIALS AND METHODS

Seventy-four pediatric patients referred for OME to the thermal medical center "La Contea" (Battaglia Terme, Padova, Italy) were considered. Data from tympanometry and pure tone audiometry performed immediately before (T0), at the end of treatment (T1) and at a follow-up control (T2) were analyzed.

RESULTS

Data from 148 ears were available. The pressure values of tympanometry significantly improved from T0 to T1 (p = 0.0001), and further improvement was recorded at T2, when 60.8% of patients had normal tympanograms. A significant gain of the air-conduction threshold in the T0-T2 interval was observed (p = 0.0001). At otoscopy, a significant reduction of tympanic membranes with fluid or air-fluid levels presence (p < 0.00001) and a significant increase of normal tympanic membranes (p = 0.0001) were found.

CONCLUSION

Eustachian tube insufflation represented a well-tolerated and effective treatment in children with OME. Further investigations should deepen these results in randomized, double-blind settings, possibly with long-term follow-up periods. A quality-of-life and cost-effectiveness evaluation of this treatment approach for pediatric OME could be helpful for public health decision-making.

A novel long excitation/emission wavelength fluorophore as platform utilized to construct NIR probes for bioimaging and biosensing

Near-infrared (NIR) fluorophores, especially dicyano-based fluorophores and xanthene-based hemicyanines, have beenput high expectation in bioimaging application due to their excellent optical properties. However, they suffer from inherentshortagessuch as short excitation/emission wavelength (less than 700 nm) or small Stokes shift (20-50 nm). Herein, we constructed a novel NIR dicyano-based fluorophore (DCO-HBTN). Toourknowledge, it is the first reported dicyano-based fluorophore of which the excitation/emission wavelength is more than 650 nm and Stokes shift is more than 100 nm. To demonstrate the feasibility of our efforts, we developed two NIR fluorescent probes (Probe-Cys and Probe-H₂S) based on the fluorophore, Probe-Cys displayed good selective and highly sensitive (LOD = 0.28 μM) recognition of Cys over Hcy and GSH, which was used to visualize endogenous Cys in tumor tissue. Probe-H₂S exhibited an. excellent specific and sensitive (LOD = 0.11 μM) response to H₂S, which was applied in monitoring H₂S releasing from the prodrug in vitro and in vivo.

Can dietary patterns prevent cognitive impairment and reduce Alzheimer's disease risk: exploring the underlying mechanisms of effects

Alzheimer's disease (AD) is one of the fastest growing cognitive decline-related neurological diseases. To date, effective curative strategies have remained elusive. A growing body of evidence indicates that dietary patterns have significant effects on cognitive function and the risk of developing AD. Previous studies on the association between diet and AD risk have mainly focused on individual food components and specific nutrients, and the mechanisms responsible for the beneficial effects of dietary patterns on AD are not well understood. This article provides a comprehensive overview of the effects of dietary patterns, including the Mediterranean diet (MedDiet), dietary approaches to stop hypertension (DASH) diet, Mediterranean-DASH diet intervention for neurological delay (MIND), ketogenic diet, caloric restriction, intermittent fasting, methionine restriction, and low-protein and high-carbohydrate diet, on cognitive impairment and summarizes the underlying mechanisms by which dietary patterns attenuate cognitive impairment, especially highlighting the modulation of dietary patterns on cognitive impairment through gut microbiota. Furthermore, considering the variability in individual metabolic responses to dietary intake, we put forward a framework to develop personalized dietary patterns for people with cognitive disorders or AD based on individual gut microbiome compositions.

Signaling Integration of Hydrogen Sulfide and Iron on Cellular Functions

Significance: Hydrogen sulfide (H₂S) is an endogenous signaling molecule, regulating numerous physiological functions from vasorelaxation to neuromodulation. Iron is a well-known bioactive metal ion, being the central component of hemoglobin for oxygen transportation and participating in biomolecule degradation, redox balance, and enzymatic actions. The interplay between H₂S and iron metabolisms and functions impacts significantly on the fate and wellness of different types of cells. Recent Advances: Iron level in vivo affects the production of H₂S via nonenzymatic reactions. On the contrary, H₂S quenches excessive iron inside the cells and regulates the redox status of iron. Critical Issues: Abnormal metabolisms of both iron and H₂S are associated with various conditions and diseases such as iron overload, anemia, oxidative stress, and cardiovascular and neurodegenerative diseases. The molecular mechanisms for the interactions between H₂S and iron are unsettled yet. Here we review signaling links of the production, metabolism, and their respective and integrative functions of H₂S and iron in normalcy and diseases. Future Directions: Physiological and pathophysiological importance of H₂S and iron as well as their therapeutic applications should be evaluated jointly, not separately. Future investigation should expand from iron-rich cells and tissues to the others, in which H₂S and iron interaction has not received due attention. Antioxid. Redox Signal. 36, 275-293.

Sequential detection of H2S and HOBr with a novel lysosome-targetable fluorescent probe and its application in biological imaging

Understanding the complex relationship between active small molecules is of great significance in various physiological processes. Herein, we present the design and synthesis of a sequential responsive Lysosome-Naphthalene imide-Azido (lyso-NP-N₃) reporter for probing the H₂S and HOBr within organelle (lysosome) in living cells. Probe lyso-NP-N₃ exhibited high selectivity and sensitivity towards H₂S (LOD = 23.5 nM) and HOBr (LOD = 254 nM). Additionally, lyso-NP-N₃ possessed an excellent lysosome targeting ability and was utilized to visualize the exogenous/endogenous H₂S and HOBr in RAW 264.7, Hela and HepG2 cells. Facilitated by this sequentially activated mechanism, the probe was successfully applied to confirm that the reported scavenger of HOBr, N-acetyl-L-cysteine (NAC) mainly relied on its metabolite H₂S to eliminate excess HOBr, thereby playing the role of cell regulation and protection. These results establish the crosstalk between H₂S and HOBr in lysosome and provide a promising tool to study metabolite interactions.

Two simple but effective turn-on benzothiazole-based fluorescent probes for detecting hydrogen sulfide in real water samples and HeLa cells

Two simple turn-on fluorescent probes, containing a benzothiazole and the 2,4-dinitrobenzenesulfonyl group, were designed for detecting H₂S. Two probes exhibited good selectivity and high sensitivity, which were applied to detect the H₂S in real water samples. Probe P2 with a positive charge had better solubility than probe P1 in water; therefore, probe P2 was successfully applied to detect both the endogenous and exogenous H₂S in lysosomes of living HeLa cells.

Dietary protein and amino acid restriction: Roles in metabolic health and aging-related diseases

The prevalence of obesity is a worldwide phenomenon in all age groups and is associated with aging-related diseases such as type 2 diabetes, as well metabolic and cardiovascular diseases. The use of dietary restriction (DR) while avoiding malnutrition has many profound beneficial effects on aging and metabolic health, and dietary protein or specific amino acid (AA) restrictions, rather than overall calorie intake, are considered to play key roles in the effects of DR on host health. Whereas comprehensive reviews of the underlying mechanisms are limited, protein restriction and methionine (Met) restriction improve metabolic health and aging-related neurodegenerative diseases, and may be associated with FGF21, mTOR and autophagy, improved mitochondrial function and oxidative stress. Circulating branched-chain amino acids (BCAAs) are inversely correlated with metabolic health, and BCAAs and leucine (Leu) restriction promote metabolic homeostasis in rodents. Although tryptophan (Trp) restriction extends the lifespan of rodents, the Trp-restricted diet is reported to increase inflammation in aged mice, while severe Trp restriction has side effects such as anorexia. Furthermore, inadequate protein intake in the elderly increases the risk of muscle-centric health. Therefore, the restriction of specific AAs may be an effective and executable dietary manipulation for metabolic and aging-related health in humans, which warrants further investigation to elucidate the underlying mechanisms.

The regulatory role of MiR-203 in oxidative stress induced cell injury through the CBS/H2S pathway

Hydrogen Sulfide (H2S) mediates biological effects in a variety of ways. Due to its strong reducing potential, H2S has been recognized to have an important role in oxidative stress induced hypoxia. It has been reported that H2S production and miRNA can mutually regulate each other. H2S is produced by the catalytic activity of cystathionine-β-synthase (CBS), which is under the regulation of miRNAs. In this study, we used target gene prediction software, and identified miR-203 as a potential regulator of CBS. We verified this finding using an oxygen and glucose deprivation (OGD) hypoxia cell model in SH-SY5Y cells and pMIR-REPORT™ luciferase miRNA expression reporter vector. Furthermore, transfecting SH-SY5Y cells with miRNA agomir (agonist) and antagomir (antagonist) by lipofectamin RNAiMAX, we further validated miR-203 as a direct regulator of CBS. We also found that miR-203 protects from cell injury by regulating lipid peroxidation, cell apoptosis, and mitochondrial membrane potential. These findings suggest that while over-expression of miR-203 can aggravate OGD induced cell injury, inhibition of miR-203 can protect against OGD induced cell injury. Based on our data and that of others, we propose that miR-203 may regulate oxidative stress induced cell injury by regulating CBS expression and adjusting the levels of H2S production.

A Novel Hydrogen Sulfide Donor Reduces Pilocarpine-Induced Status Epilepticus and Regulates Microglial Inflammatory Profile

Although epilepsy is one of the most common neurologic disorders, there is still a lack of effective therapeutic drugs for it. Recently, we synthesized a novel hydrogen sulfide (H₂S) donor, which is found to reduce seizures in animal models effectively. But it remains to be determined for its mechanism. In the present study, we found that the novel H₂S donor could reduce pilocarpine-induced seizures in mice. It alleviated the epileptic behavior, the hippocampal electroencephalography (EEG) activity of seizures, and the damage of hippocampal neurons in status epilepticus mice. In addition, the novel H₂S donor could reduce microglial inflammatory response. It not only reduced the upregulation of pro-inflammatory markers [inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2)] in status epilepticus mice, but also increased the levels of microglial anti-inflammatory marker arginase-1 (Arg-1). In lipopolysaccharide-treated microglia BV2 cells, administration of the H₂S donor also significantly reduced the lipopolysaccharide-induced upregulation of the expression of the pro-inflammatory markers and increased the expression of the anti-inflammatory markers. Thus, the novel H₂S donor regulates microglial inflammatory profile in status epilepticus mice and in vitro. These results suggested that the novel H₂S donor can reduce seizures and regulate microglial inflammatory profile, which may be a novel mechanism and potential therapeutic strategy of the H₂S donor anti-seizures.

H2S Donors and Their Use in Medicinal Chemistry

Hydrogen sulfide (H2S) is a ubiquitous gaseous signaling molecule that has an important role in many physiological and pathological processes in mammalian tissues, with the same importance as two others endogenous gasotransmitters such as NO (nitric oxide) and CO (carbon monoxide). Endogenous H2S is involved in a broad gamut of processes in mammalian tissues including inflammation, vascular tone, hypertension, gastric mucosal integrity, neuromodulation, and defense mechanisms against viral infections as well as SARS-CoV-2 infection. These results suggest that the modulation of H2S levels has a potential therapeutic value. Consequently, synthetic H2S-releasing agents represent not only important research tools, but also potent therapeutic agents. This review has been designed in order to summarize the currently available H2S donors; furthermore, herein we discuss their preparation, the H2S-releasing mechanisms, and their -biological applications.

A phenothiazine-based turn-on fluorescent probe for the selective detection of hydrogen sulfide in food, live cells and animals

In this work, a phenothiazine-based fluorescent probe (PR) has been developed for the selective detection of hydrogen sulfide (H₂S) in biosystems and monitoring H₂S produced in the food spoilage process. The nucleophilic attack of H₂S on the CC double bond of PRvia a Michael addition interdicted the ICT process to trigger 34-fold enhancement of the fluorescence emission. PR featured high selectivity and sensitivity (1.8 μM), low cytotoxicity and reliability at physiological pH. "Naked-eye" monitoring of H₂S produced in the food spoilage process using PR was successfully accomplished. The preliminary fluorescence imaging studies showed that PR is suitable for the visualization of exogenous and endogenous H₂S in living cells and live animals. Moreover, PR has been successfully applied to the visualization of H₂S generation in an inflammation model. The results indicated that PR is an effective tool to monitor H₂S production in the fields of biomedicine and food safety.

ROS-Induced mtDNA Release: The Emerging Messenger for Communication between Neurons and Innate Immune Cells during Neurodegenerative Disorder Progression

One of the most striking hallmarks shared by various neurodegenerative diseases, including Parkinson’s disease, Alzheimer’s disease and amyotrophic lateral sclerosis, is microglia-mediated and astrocyte-mediated neuroinflammation. Although inhibitions of both harmful proteins and aggregation are major treatments for neurodegenerative diseases, whether the phenomenon of non-normal protein or peptide aggregation is causally related to neuronal loss and synaptic damage is still controversial. Currently, excessive production of reactive oxygen species (ROS), which induces mitochondrial dysfunction in neurons that may play a key role in the regulation of immune cells, is proposed as a regulator in neurological disorders. In this review, we propose that mitochondrial DNA (mtDNA) release due to ROS may act on microglia and astrocytes adjacent to neurons to induce inflammation through activation of innate immune responses (such as cGAS/STING). Elucidating the relationship between mtDNA and the formation of a pro-inflammatory microenvironment could contribute to a better understanding of the mechanism of crosstalk between neuronal and peripheral immune cells and lead to the development of novel therapeutic approaches to neurodegenerative diseases.

Synthesis and preliminary exploration of a NIR fluorescent probe for the evaluation of androgen dependence of prostate cancer

PURPOSE

Castration resistance prostate cancer patients showing resistance to the androgen deprivation therapy always have low five-year survival rate and worse prognosis. A responsive NIR fluorescent probe was designed to report the androgen dependence and monitor the development of castration resistance for prostate cancer.

METHODS

Intratumoral H₂S in prostate cancer was closely related to castration resistance. A H₂S-responsive NIR probe (HM) was developed as a dependent indicator to report the androgen dependence of prostate cancer. The specificity of HM to H₂S and the influence of normal intracellular substrates to the response between H₂S and HM were determined. Cell/in vivo animal imaging were performed on PC-3 and LnCAP cell/tumor bearing mice, which presented with androgen independence and androgen dependence, respectively.

RESULTS

When HM responded to H₂S, strong fluorescence at 770 nm could be rapidly turned on in 5 min with the stokes shift as large as 200 nm. The recognition between HM and H₂S showed high specificity. Neither other common substrates showed capacity to turn on HM's fluorescence, nor their existence demonstrated competition. The fluorescence intensity was linearly dependent to the H₂S concentration and the limited of detection was 0.15 μM. When HM was applied to PC-3/LNCaP prostate cancer cell and tumor, the intracellular and intratumoral H₂S could be clearly imaged and monitored.

CONCLUSION

HM showing obvious fluorescent behaviors in androgen dependence and independence prostate tumor, which could work as an indicator to reported the androgen dependence of prostate cancer and monitor the development of castration resistance.

Oxidative stress-A direct bridge to central nervous system homeostatic dysfunction and Alzheimer's disease

Neurologists have highly observed a frequent increasing number of elderly patients with Alzheimer's disease (AD) without any relevant evidence of any genetic or known AD-linked predisposing factors in the past few years. Those patients are characterized by continuous and irreversible neuron cells loss along with declined cognitive functions. Numerous studies have suggested that the exaggerated release of reactive oxygen species (ROS) within the brain may develop late-onset neurodegenerative disorders, especially AD-neuroinflammatory type. However, the central nervous system is vitally linked with whole-brain chemical integrity and its related healthy state, the cascade by which ROS may result in AD's development has not been highly justified or even maintained. It is widely known that the brain consumes a vast amount of oxygen and is characterized by being rich in lipid polyunsaturated fatty acids content, explaining why it is a prone region to oxidative stress (OS) and ROS damage. The formed OS-AD cytoskeletal protein aggregates can be considered a main predisposing factor for amyloid-beta (Aβ) hallmarks precipitation. Herein, this review aims to provide a detailed information on how oxidative stress can play a pathogenic role in activating damage-associated molecular patterns (DAMPs)-related toll-like receptor-4 inflammatory (TLR-4) cascades resulting in the deposition of Aβ hallmarks in brain tissues ending with irreversible cognitive dysfunction. It also explains how microglia can be activated via ROS, which may significantly release several pro-inflammatory cascades ending with general brain atrophy. Furthermore, different types of suggested antioxidant therapies will be discussed to combat AD-related pathological disorders and hallmarks.

Peripubertal Bisphenol A Exposure Imparts Detrimental Age-Related Changes in Body Composition, Cognition, and Hydrogen Sulfide Production Capacities

Aims: Peripubertal endocrine disruption has immediate and lifelong consequences on health, cognition, and lifespan. Disruption comes from dietary, environmental, and pharmaceutical sources. The plasticizer Bisphenol A (BPA) is one such endocrine disrupting chemical. However, it is unclear whether peripubertal BPA exposure incites long-lasting physiological, neuro-cognitive, and/or longevity-related metabolic impairments. Catabolism of cysteine via transsulfuration enzymes produces hydrogen sulfide (H2S), a redox-modulating gasotransmitter causative to endocrine and metabolic homeostasis and improved cognitive function with age. As thyroid hormone (TH) regulates hepatic H2S production and BPA is a TH receptor antagonist, we hypothesized that BPA exposure during peripubertal development impairs metabolic and neuro-cognitive/behavioral endpoints in aged mice, in part, due to altered peripheral and/or localized H2S production and redox status. Results: To test this, male C57BL/6J mice at 5 weeks of age were orally exposed daily for 5 weeks to 250 μg BPA/kg, defined as low dose group (LD BPA), or 250 mg BPA/kg, defined as high dose group (HD BPA). Both LD and HD BPA exposure decreased lean mass and increased fat mass accompanied by decreased serum total TH at advanced ages. In addition, LD BPA had an anxiogenic effect whereas HD BPA caused cognitive deficits. Notably, HD BPA disrupted tissue-specific H2S production capacities and/or protein persulfidation, with the former negatively correlated with memory deficits and oxidative stress. Innovation and Conclusion: These findings provide a potential mechanism of action for acute and long-term health impacts of BPA-induced peripubertal endocrine disruption and bolster the need for improved monitoring and limitation of adolescent BPA exposure.

c-Jun N-Terminal Kinases in Alzheimer's Disease: A Possible Target for the Modulation of the Earliest Alterations

Given the highly multifactorial origin of Alzheimer's disease (AD) neuropathology, disentangling and orderly knowing mechanisms involved in sporadic onset are arduous. Nevertheless, when the elements involved are dissected into smaller pieces, the task becomes more accessible. This review aimed to describe the link between c-Jun N-terminal Kinases (JNKs), master regulators of many cellular functions, and the early alterations of AD: synaptic loss and dysregulation of neuronal transport. Both processes have a role in the posterior cognitive decline observed in AD. The manuscript focuses on the molecular mechanisms of glutamatergic, GABA, and cholinergic synapses altered by the presence of amyloid-β aggregates and hyperphosphorylated tau, as well as on several consequences of the disruption of cellular processes linked to neuronal transport that is controlled by the JNK-JIP (c-jun NH2-terminal kinase (JNK)-interacting proteins (JIPs) complex, including the transport of AβPP or autophagosomes.

Hydrogen Sulfide Actions in the Vasculature

Hydrogen sulfide (H2 S) is a small, gaseous molecule with poor solubility in water that is generated by multiple pathways in many species including humans. It acts as a signaling molecule in many tissues with both beneficial and pathological effects. This article discusses its many actions in the vascular system and the growing evidence of its role to regulate vascular tone, angiogenesis, endothelial barrier function, redox, and inflammation. Alterations in some disease states are also discussed including potential roles in promoting tumor growth and contributions to the development of metabolic disease. © 2021 American Physiological Society. Compr Physiol 11:1-22, 2021.

Hydrogen sulfide and mesenchymal stem cells-extracted microvesicles attenuate LPS-induced Alzheimer's disease

Both hydrogen sulfide (H2 S) and mesenchymal stem cells (MSCs) extracted microvesicles (MVs) are potent anti-inflammatory molecules. They play an essential role in lowering the production of tumor necrosis factor-alpha (TNF-α). The latter could strongly stimulate MiR-155 that contributes to neurodegeneration and Alzheimer's disease (AD). miR-155 could repress the expression of inositol 5-phosphatase-1 (SHIP-1) leading eventually to activation of Akt kinase and neurofibrillary development in AD. The current study was conducted to evaluate the role of miR-155 in a rat model of lipopolysaccharide (LPS)-induced AD and to investigate the effect of using MVs and H2 S that were given either separately or combined in regulating pro-inflammatory signaling. Thirty female Wistar albino rats aged 6 months to 1 year were equally divided into five groups; control group, LPS-induced AD group, LPS + MVs group, LPS + NaHS group, and LPS + MVs and NaHS group. The increased miR-155 level was associated with decreased SHIP-1 level and positively correlated with TNF-α. In addition, treatment with MVs and/or NaHS resulted in attenuation of inflammation, decreasing miR-155, pAkt levels, and downregulation of apoptosis along with improvement of the hippocampal and cortical histopathological alterations. LPS enhanced production of malondialdehyde (MDA) and reduced glutathione (GSH) levels indicating oxidative stress-induced neural damage, whereas MVs and NaHS could mitigate oxidative damage and accelerate antioxidant capacity via increasing catalase enzyme. In conclusion, downregulation of TNF-α, miR-155, and pAkt and increased SHIP-1 could improve the neuro-inflammatory state and cognitive function of LPS-induced Alzheimer's disease.

Superoxide-responsive fluorogenic molecular probes for optical bioimaging of neurodegenerative events in Alzheimer's disease

Since oxidative stress has been recognized as a major factor contributing to the progression of several neurodegenerative disorders, reactive oxygen species (ROS) including superoxide have received great attention as a representative molecular marker for the diagnosis of Alzheimer's disease (AD). Here, superoxide-sensitive fluorogenic molecular probes, benzenesulfonylated resorufin derivatives (BSRs), were newly devised for optical bioimaging of oxidative events in neurodegenerative processes. BSRs, fluorescence-quenched benzenesulfonylated derivatives of resorufin, were designed to recover their fluorescence upon exposure to superoxide through a selective nucleophilic uncaging reaction of the benzenesulfonyl cage. Among BSRs, BSR6 presented the best sensitivity and selectivity to superoxide likely due to the optimal reactivity matching between the nucleophilicity of superoxide and its electrophilicity ascribed to the highly electron-withdrawing pentafluoro-substitution on the benzenesulfonyl cage. Fluorescence imaging of inflammatory cells and animal models presented the potential of BSR6 for optical sensing of superoxide in vitro and in vivo. Furthermore, microglial cell (Bv2) imaging with BSR6 enabled the optical monitoring of intracellular oxidative events upon treatment with an oxidative stimulus (amyloid beta, Aβ) or the byproduct of oxidative stress (4-hydroxynonenal, HNE).

Exercise renovates H2S and Nrf2-related antioxidant pathways to suppress apoptosis in the natural ageing process of male rat cortex

Ageing is a complex biological process that increases the probability of disease and death, which affects the organs of all species. The accumulation of oxidative damage in the brain contributes to a progressive loss of cognitive functions or even declined the energy metabolism. In this study, we tested the effects of exercise training on the apoptosis, survival, and antioxidant signaling pathways in the cerebral cortex of three age groups of male rats; 3, 12, and 18 months. We observed that H₂S and the expression of Nrf2-related antioxidant pathways declined with age and increased after exercise training. IGF1R survival pathway was less increased in middle-aged rats; however, significantly increased after exercise training. The expression of mitochondrial-dependent apoptotic pathway components, such as Bak, cytochrome C, and caspase 3 in the ageing control group, were much higher than those of the exercise training groups. This study demonstrated that exercise training could reduce the apoptosis and oxidative stress that accrues throughout ageing, which causes brain damage.

The Role of Protein Persulfidation in Brain Aging and Neurodegeneration

Hydrogen sulfide (H₂S), originally considered a toxic gas, is now a recognized gasotransmitter. Numerous studies have revealed the role of H₂S as a redox signaling molecule that controls important physiological/pathophysiological functions. The underlying mechanism postulated to serve as an explanation of these effects is protein persulfidation (P-SSH, also known as S-sulfhydration), an oxidative posttranslational modification of cysteine thiols. Protein persulfidation has remained understudied due to its instability and chemical reactivity similar to other cysteine modifications, making it very difficult to selectively label. Recent developments of persulfide labeling techniques have started unraveling the role of this modification in (patho)physiology. PSSH levels are important for the cellular defense against oxidative injury, albeit they decrease with aging, leaving proteins vulnerable to oxidative damage. Aging is one of the main risk factors for many neurodegenerative diseases. Persulfidation has been shown to be dysregulated in Parkinson's, Alzheimer's, Huntington's disease, and Spinocerebellar ataxia 3. This article reviews the latest discoveries that link protein persulfidation, aging and neurodegeneration, and provides future directions for this research field that could result in development of targeted drug design.