News Insights into the Host-Parasite Interactions of Amyloodiniosis in European Sea Bass: A Multi-Modal Approach

Amyloodiniosis is a disease resulting from infestation by the ectoparasitic dinoflagellate Amyloodinium ocellatum (AO) and is a threat for fish species such as European sea bass (ESB, Dicentrarchus labrax), which are farmed in lagoon and land-based rearing sites. During the summer, when temperatures are highest, mortality rates can reach 100%, with serious impacts for the aquaculture industry. As no effective licensed therapies currently exist, this study was undertaken to improve knowledge of the biology of AO and of the host-parasite relationship between the protozoan and ESB, in order to formulate better prophylactic/therapeutic treatments targeting AO. To achieve this, a multi-modal study was performed involving a broad range of analytical modalities, including conventional histology (HIS), immunohistochemistry (IHC) and confocal laser scanning microscopy (CLSM). Gills and the oro-pharyngeal cavity were the primary sites of amyloodiniosis, with hyperplasia and cell degeneration more evident in severe infestations (HIS). Plasmacells and macrophages were localised by IHC and correlated with the parasite burden in a time-course experimental challenge. CLSM allowed reconstruction of the 3D morphology of infecting trophonts and suggested a protein composition for its anchoring and feeding structures. These findings provide a potential starting point for the development of new prophylactic/therapeutic controls.

Implementing Complementary Approaches to Shape the Mechanism of α-Synuclein Oligomerization as a Model of Amyloid Aggregation

The aggregation of proteins into amyloid fibers is linked to more than forty still incurable cellular and neurodegenerative diseases such as Parkinson’s disease (PD), multiple system atrophy, Alzheimer’s disease and type 2 diabetes, among others. The process of amyloid formation is a main feature of cell degeneration and disease pathogenesis. Despite being methodologically challenging, a complete understanding of the molecular mechanism of aggregation, especially in the early stages, is essential to find new biological targets for innovative therapies. Here, we reviewed selected examples on α-syn showing how complementary approaches, which employ different biophysical techniques and models, can better deal with a comprehensive study of amyloid aggregation. In addition to the monomer aggregation and conformational transition hypothesis, we reported new emerging theories regarding the self-aggregation of α-syn, such as the alpha-helix rich tetramer hypothesis, whose destabilization induce monomer aggregation; and the liquid-liquid phase separation hypothesis, which considers a phase separation of α-syn into liquid droplets as a primary event towards the evolution to aggregates. The final aim of this review is to show how multimodal methodologies provide a complete portrait of α-syn oligomerization and can be successfully extended to other protein aggregation diseases.

A Study on the Alleviating Effects of N-phthaloyl-γ-Aminobutyric Acid (P-GABA) on the Behavioral, Histopathological and Biochemical Adverse Effects of Sleep Deprivation in Zebrafish (Danio rerio)

Background: Sleep is defined as a reversible behavioural state of perceptual disconnection from insensitivity to the environment that facilitates the interaction of physiological and behavioural processes. Sleep Deprivation (S.D.) is defined as a decrease in sleeping duration below the recommended minimum, which has been linked to learning and memory problems. Aim: The primary objective of this work was to determine the effect of P-GABA on metabolic parameters, behavioural changes, whole-body cortisol, and brain histology in light-induced sleep-deprived zebrafish, as well as the optimal dose of P-GABA neutralizing undesirable effects. Methodology: The present study was conducted for ten days, consisting of three days in a row of sleep deprivation and seven days of treatment with P-GABA. The current investigation used six fishes in a group (n=6). Group 1: Control ; Group 2: 24h Total SD ; Group 3: 48h Total SD ; Group 4: 72h Total SD ; Group 5: 24h Total SD + P-GABA (100 mg/L) ; Group 6: 48h Total SD + P-GABA (100 mg/L) ;Group 7: 72h Total SD + P-GABA (100 mg/L) Results: The current study provides scientific data demonstrating the positive effects of P-GABA in treating sleep deprivation and associated cognitive impairment. To test if P-GABA treatment can alleviate the cognitive and memory impairment caused by S.D., we established non-toxic concentrations and treated the zebrafish with a safe dose of 100mg/L. The use of P-GABA increased cognitive performance in the T-maze, demonstrating that it has a favourable effect in a sleep-deprivation condition. The SD group exhibited neutrophil infiltration, and this S.D fish treated with P-GABA at a concentration of 100 mg/L demonstrated a moderate reduction in neuronal cell degeneration compared to controls. The levels of biochemical parameters during sleep deprivation and treatment phase with P-GABA were checked. It was evident from the results that the SOD, CAT and GPX levels in the S.D groups were drastically decreased, whereas treatment with P-GABA could show a significant increase in the levels of biochemical parameters. In contrast to the control group, zebrafish subjected to sleep deprivation showed enhanced AChE activity in the brain. The results of the P-GABA indicated an anti-AChE profile, which corresponds to improved memory parameters in zebrafish, as observed in the NTT and T-maze tests. When comparing the sleep-deprived fish to the control group, the MDA level, which indicates lipid peroxidation, was higher. Treatment with P-GABA considerably reduced the amount of MDA produced compared to the amount produced in sleep-deprived fish. The cortisol levels gradually increased in the single row 24h, 48h, and 72h sleep deprived groups. There was a gradual decrease in cortisol levels in the groups that received P-GABA treatment. The levels of neurotransmitters were seen to be decreased in the sleep-deprived groups when compared with the control. Upon treatment with P-GABA, the neurotransmitters were restored to near normal. Conclusion: This study showed that P-GABA counteracts cognitive performance decrease and anxiety increase resulting from sleep deprivation through a mechanism implying mitigation of brain oxidative stress and regulation of AChE activity.

Develop an efficient and specific AAV-based labeling system for Muller glia in mice

Cell degeneration in the retina leads to several ocular diseases and vision loss. Considerable research efforts focus on reprogramming Muller glia (MG) into functional cells to rescue vision as a promising therapeutic strategy, although whether MG can convert into functional amacrine cells, bipolar cells, retinal ganglia cells (RGCs), rods or cones in mammals remains controversial. The broad applicability of tracking MG differentiation thus presents a need for improved labeling efficiency and specificity. Here, we compared AAV-based labeling strategies with conventional lineage-tracking by crossing transgenic mouse lines. We found that reporter expression was weak and not MG-specific in mGFAP-Cre transgenic mice. Different AAV serotypes showed a range of efficiency and specificity in labeling MG, leading us to optimize a human GFAP-Cre reporter system packaged in the AAV9 serotype with the WPRE (WPRE, woodchuck hepatitis virus post-transcriptional regulatory element) removed. The hGFAP-Cre-ΔWPRE reporter could label 20-73.8% MGs, with non-specific RGC labeling rates ranging from 0-0.08% at doses of 1 × 108 to 1010 vector genomes (vg) per eye, an approximate 40-fold reduction compared with the AAV9-hGFAP-Cre-WPRE labeling system. The AAV9-hGFAP-Cre-ΔWPRE system thus represents a highly efficient and specific labeling system for Muller glia, providing a valuable tool for tracking cell fate in vivo.

Polydopamine nanoparticles attenuate retina ganglion cell degeneration and restore visual function after optic nerve injury

Background Oxidative stress contributes to retina ganglion cells (RGCs) loss in variety of ocular diseases, including ocular trauma, ocular vein occlusion, and glaucoma. Scavenging the excessed reactive oxygen species (ROS) in retinal neurovascular unit could be beneficial to RGCs survival. In this study, a polydopamine (PDA)-based nanoplatform is developed to protect RGCs. Results The PDA nanoparticles efficiently eliminate multi-types of ROS, protect endothelia and neuronal cells from oxidative damage, and inhibit microglia activation in retinas. In an optic nerve crush (ONC) model, single intravitreal injection of PDA nanoparticles could significantly attenuate RGCs loss via eliminating ROS in retinas, reducing the inflammatory response and maintaining barrier function of retinal vascular endothelia. Comparative transcriptome analysis of the retina implied that PDA nanoparticles improve RGCs survival probably by altering the expression of genes involved in inflammation and ROS production. Importantly, as a versatile drug carrier, PDA nanoparticles could deliver brimonidine (a neuroprotection drug) to synergistically attenuate RGCs loss and promote axon regeneration, thus restore visual function. Conclusions The PDA nanoparticle-based therapeutic nanoplatform displayed excellent performance in ROS elimination, providing a promising probability for treating retinal degeneration diseases. Graphical Abstract

The Selective Loss of Purkinje Cells Induces Specific Peripheral Immune Alterations

The progression of neurodegenerative diseases is reciprocally associated with impairments in peripheral immune responses. We investigated different contexts of selective neurodegeneration to identify specific alterations of peripheral immune cells and, at the same time, discover potential biomarkers associated to this pathological condition. Consequently, a model of human cerebellar degeneration and ataxia -the Purkinje Cell Degeneration (PCD) mouse- has been employed, as it allows the study of different processes of selective neuronal death in the same animal, i.e., Purkinje cells in the cerebellum and mitral cells in the olfactory bulb. Infiltrated leukocytes were studied in both brain areas and compared with those from other standardized neuroinflammatory models obtained by administering either gamma radiation or lipopolysaccharide. Moreover, both myeloid and lymphoid splenic populations were analyzed by flow cytometry, focusing on markers of functional maturity and antigen presentation. The severity and type of neural damage and inflammation affected immune cell infiltration. Leukocytes were more numerous in the cerebellum of PCD mice, being located predominantly within those cerebellar layers mostly affected by neurodegeneration, in a completely different manner than the typical models of induced neuroinflammation. Furthermore, the milder degeneration of the olfactory bulb did not foster leukocyte attraction. Concerning the splenic analysis, in PCD mice we found: (1) a decreased percentage of several myeloid cell subsets, and (2) a reduced mean fluorescence intensity in those myeloid markers related to both antigen presentation and functional maturity. In conclusion, the selective degeneration of Purkinje cells triggers a specific effect on peripheral immune cells, fostering both attraction and functional changes. This fact endorses the employment of peripheral immune cell populations as concrete biomarkers for monitoring different neuronal death processes.

NADPH Oxidase and Epidermal Growth Factor Receptor Are Promising Targets of Phytochemicals for Ultraviolet-Induced Skin Carcinogenesis

The skin acts as the primary defense organ that protects the body from the external environment. Skin cancer is one of the most common cancers in the world. Skin carcinogenesis is usually caused by cell degeneration due to exposure to ultraviolet (UV) radiation, which causes changes in various signaling networks, disrupting the homeostasis of single skin cells. In this review, we summarize the roles of nicotinamide adenine dinucleotide phosphate oxidase (NOX) and epidermal growth factor receptor (EGFR) in UV-induced skin carcinogenesis. Furthermore, we describe the crosstalk that exists between NOX, EGFR, and protein tyrosine phosphatase κ and its oncogenic downstream signaling pathways. Chemoprevention is the use of chemical compounds to recover the healthy status of the skin or delay cancer development. Current evidence from in vitro and in vivo studies on chemopreventive phytochemicals that target NOX, EGFR, or both, as major regulators of skin carcinogenesis will also be discussed.

Stem Cell Differentiation Stage Factors (SCDSFs) Taken from Zebrafish Embryo During Organogenesis and Their Role as Epigenetics Regulators Able to Reverse Neurosensory Hearing Loss

Hearing dysfunctions can be classified by type, degree, configuration, time of onset, aetiology, and finally, consequences on speech development. They can be divided into conductive, mixed, central types and sensorineural. Conductive hearing loss (CHL) results from interference with the mechanical transmission of sound through the external and middle ear; it can be congenital, as a consequence of anatomic abnormalities, but it can commonly be acquired following middle ear inflammatory pathologies. Sensorineural hearing loss (SNHL) results from failure to transduce vibrations to neural impulses in the cochlean and is a consequence of an irreversible damage to the differentiated cells which make up the organ of hearing and the acoustic paths at various levels. Mixed hearing loss involves a combination of these two types in the same ear. Studies in neuroscience field have shown that the prevention of cell degeneration is only possible if all the factors taken at the different stages of stem cells’ multiplication and differentiation are administered together. We have demonstrated this in a recent study on the ability of SCDSFs to prevent neurodegeneration in hippocampal cells of the CA1 zone in mice. This study confirms previous findings demonstrating that early developmental zebrafish embryo extracts could act as a modulator of senescence in human mesenchymal stem cells (hMSC) isolated from many adult tissues. These findings have open a promising way for the approaches promoting the rejuvenation and regeneration of different tissues, by-passing stem cell transplantation. In the present clinical trial we have used SCDSFs to study the possible reversion of neurosensory hearing loss, until now considered an irreversible condition.