Са2+- and NF-κB-dependent generation of NO in the photosensitized neurons and satellite glial cells

The Role of Hydrogen Sulfide in iNOS and APP Localization and Expression in Neurons and Glial Cells Under Traumatic Effects: An Experimental Study with Bioinformatics Analysis and Biomodeling

Hydrogen sulfide (H2S) donors are emerging as promising candidates for neuroprotective agents. However, H2S-dependent neuroprotective mechanisms are not yet fully understood. We have demonstrated that an H2S donor (sodium sulfide, Na2S) reduces the expression of inducible NO synthase (iNOS) and amyloid-beta precursor protein (APP) in damaged neural tissue at 24 h and 7 days following traumatic brain injury (TBI). The application of aminooxyacetic acid (AOAA), an inhibitor of cystathionine β-synthase (CBS), produced the opposite effect. Seven days after TBI, iNOS expression was observed not only in the cytoplasm but also in some neuronal nuclei, while APP was exclusively localized in the cytoplasm and axons of damaged neurons. It was also shown that iNOS and APP were present in the cytoplasm of mechanoreceptor neurons (MRNs) in the crayfish, in axons, as well as in certain glial cells 8 h after axotomy. Na2S and AOAA had opposing effects on axotomized MRNs and ganglia in the ventral nerve cord (VNC). Multiple sequence alignments revealed a high degree of identity among iNOS and APP amino acid residues in various vertebrate and invertebrate species. In the final stage of this study, biomodeling identified unique binding sites for H2S, hydrosulfide anion (HS-), and thiosulfate (S2O32-) with iNOS and APP.

The Role of Hydrogen Sulfide in the Localization and Expression of p53 and Cell Death in the Nervous Tissue in Traumatic Brain Injury and Axotomy

Traumatic brain injury (TBI) is one of the leading causes of disability and death worldwide. It is characterized by various molecular-cellular events, with the main ones being apoptosis and damage to axons. To date, there are no clinically effective neuroprotective drugs. In this study, we examined the role of hydrogen sulfide (H2S) in the localization and expression of the key pro-apoptotic protein p53, as well as cell death in the nervous tissue in TBI and axotomy. We used a fast donor (sodium sulphide, Na2S) H2S and a classic inhibitor (aminooxyacetic acid, AOAA) of cystathionine β-synthase (CBS), which is a key enzyme in H2S synthesis. These studies were carried out on three models of neurotrauma in vertebrates and invertebrates. As a result, it was found that Na2S exhibits a pronounced neuroprotective effect that reduces the number of TUNEL-positive neurons and glial cells in TBI and apoptotic glia in axotomy. This effect could be realized through the Na2S-dependent decrease in the level of p53 in the cells of the nervous tissue of vertebrates and invertebrates, which we observed in our study. We also observed the opposite effect when using AOAA, which indicates the important role of CBS in the regulation of p53 expression and death of neurons and glial cells in TBI and axotomy.

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 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.

The localization of the photosensitizer determines the dynamics of the secondary production of hydrogen peroxide in cell cytoplasm and mitochondria

Photodynamic therapy (PDT) is based on the production of the cytotoxic reactive oxygen species (ROS) by light irradiation of a photosensitizer dye in the presence of molecular oxygen. Along with photochemical ROS production, it becomes evident that PDT induces massive secondary production of ROS which is registered long after the irradiation is completed. We created cell lines of human epidermoid carcinoma with the cytoplasmic and mitochondrial localization of protein sensor HyPer sensitive to hydrogen peroxide to compare its concentration in two cellular compartments. The lag-period between irradiation and accumulation of hydrogen peroxide in cells was registered; its duration was dose-dependent and increased up to 80 min when lowering the exposition dose from 50 to 15 J/cm². We have shown that localization of the photosensitizer determines the spatiotemporal pattern of the cell response to PDT: secondary hydrogen peroxide accumulation in cell cytoplasm induced by photodynamic treatment with lysosome-localized phtalocyianine Photosens occurs several minutes prior to that in mitochondria; on the contrary, membranotropic arylcyanoporphyrazine dye leads to massive mitochondrial hydrogen peroxide production followed by its cytoplasmic accumulation. We hypothesize that photosensitizers with various physicochemical properties and intracellular localization can trigger different patterns not only of primary but also secondary ROS production leading to different cell fate outcomes.