Immunohistochemistry of the Gut-Associated Lymphoid Tissue (GALT) in African Bonytongue (Heterotis niloticus, Cuvier 1829).

Heterotis niloticus is a basal teleost, belonging to the Osteoglossidae family, which is widespread in many parts of Africa. The digestive tract of H. niloticus presents similar characteristics to those of higher vertebrates, exhibiting a gizzard-like stomach and lymphoid aggregates in the intestinal lamina propria. The adaptive immune system of teleost fish is linked with each of their mucosal body surfaces. In fish, the gut-associated lymphoid tissue (GALT) is generally a diffuse immune system that represents an important line of defense against those pathogens inhabiting the external environment that can enter through food. The GALT comprises intraepithelial lymphocytes, which reside in the epithelial layer, and lamina propria leukocytes, which consist of lymphocytes, macrophages, granulocytes, and dendritic-like cells. This study aims to characterize, for the first time, the leukocytes present in the GALT of H. niloticus, by confocal immuno- fluorescence techniques, using specific antibodies: toll-like receptor 2, major histocompatibility complex class II, S100 protein, serotonin, CD4, langerin, and inducible nitric oxide synthetase. Our results show massive aggregates of immune cells in the thickness of the submucosa, arranged in circumscribed oval-shaped structures that are morphologically similar to the isolated lymphoid follicles present in birds and mammals, thus expanding our knowledge about the intestinal immunity shown by this fish.

Expression of Antimicrobic Peptide Piscidin1 in Gills Mast Cells of Giant Mudskipper Periophthalmodon schlosseri (Pallas, 1770).

The amphibious teleost Giant mudskipper (Periophthalmodon schlosseri, Pallas 1770) inhabit muddy plains and Asian mangrove forests. It spends more than 90% of its life outside of the water, using its skin, gills, and buccal-pharyngeal cavity mucosa to breathe in oxygen from the surrounding air. All vertebrates have been found to have mast cells (MCs), which are part of the innate immune system. These cells are mostly found in the mucous membranes of the organs that come in contact with the outside environment. According to their morphology, MCs have distinctive cytoplasmic granules that are released during the degranulation process. Additionally, these cells have antimicrobial peptides (AMPs) that fight a variety of infections. Piscidins, hepcidins, defensins, cathelicidins, and histonic peptides are examples of fish AMPs. Confocal microscopy was used in this study to assess Piscidin1 expression in Giant Mudskipper branchial MCs. Our results demonstrated the presence of MCs in the gills is highly positive for Piscidin1. Additionally, colocalized MCs labeled with TLR2/5-HT and Piscidin1/5-HT supported our data. The expression of Piscidin1 in giant mudskipper MCs highlights the involvement of this peptide in the orchestration of teleost immunity, advancing the knowledge of the defense system of this fish.

Relationship between Immune Cells, Depression, Stress, and Psoriasis: Could the Use of Natural Products Be Helpful?

Psoriasis is one of the most widespread chronic inflammatory skin diseases, affecting about 2%-3% of the worldwide adult population. The pathogenesis of this disease is quite complex, but an interaction between genetic and environmental factors has been recognized with an essential modulation of inflammatory and immune responses in affected patients. Psoriatic plaques generally represent the clinical psoriatic feature resulting from an abnormal proliferation and differentiation of keratinocytes, which cause dermal hyperplasia, skin infiltration of immune cells, and increased capillarity. Some scientific pieces of evidence have reported that psychological stress may play a key role in psoriasis, and the disease itself may cause stress conditions in patients, thus reproducing a vicious cycle. The present review aims at examining immune cell involvement in psoriasis and the relationship of depression and stress in its pathogenesis and development. In addition, this review contains a focus on the possible use of natural products, thus pointing out their mechanism of action in order to counteract clinical and psychological symptoms.

Evaluation of antioxidant, antiinflammatory, and gastroprotective properties of Rubus fruticosus L. fruit juice.

The juice of R. fruticosus (RFJ) fruits grown in Sicily was analysed for polyphenol compounds and tested to evaluate in vitro antioxidant and in vivo antiinflammatory and gastroprotective effects. RFJ, containing mainly anthocyanins, such as cyanidin derivatives, significant amounts of phenolic acids, and smaller amounts of flavonoids, showed significant antioxidant activity in DPPH (2,2-diphenyl-1-picrylhydrazyl radical) (4,147.194 ± 17.199 mg trolox equivalent [TE]/100 ml), TE antioxidant capacity (8,312.444 ± 43.055 mg TE/100 ml), ferric reducing antioxidant power (2,177.830 ± 21.015 mg TE/100 ml), oxygen radical absorbance capacity (95,377.674 ± 616.194 µmol TE/100 ml juice), and ß-carotene bleaching (72% ± 4.58) assay. In vivo studies showed that RFJ inhibit significantly the carrageenan-induced paw oedema (63-71%) in rats and possess antiinflammatory effects particularly significant in association with phenylbutazone (94-96%). In addition, RFJ pretreatment was able to prevent the ethanol-induced ulcerogenic effect in rats. All in vivo results were corroborated by histopathological observations and are in good agreement with antioxidant activity, confirming the relationships between biological effects observed and radical scavenging properties of RFJ.

Light and electron microscopic observations on retinal neurons of red-tail shark (Epalzeorhynchos bicolor H. M. Smith, 1931).

The structure of photoreceptors (PR) and the arrangement of neurons in the retina of red-tail shark were investigated using light and electron microscopy. The PR showed a mosaic arrangement and included double cones, single cones (SC), and single rods. Most cones occur as SC. The ratio between the number of cones and rods was 3:1.39 (±0.29). The rods were tall that reached the pigmented epithelium. The outer plexiform layer (OPL) showed a complex synaptic connection between the horizontal and photoreceptor terminals that were surrounded by Müller cell processes. Electron microscopy showed that the OPL possessed both cone pedicles and rod spherules. Each rod spherule consisted of a single synaptic ribbon within the invaginating terminal endings of the horizontal cell (hc) processes. In contrast, the cone pedicles possessed many synaptic ribbons within their junctional complexes. The inner nuclear layer consisted of bipolar, amacrine, Müller cells, and hc. Müller cells possessed intermediate filaments and cell processes that can reach the outer limiting membrane and form connections with each other by desmosomes. The ganglion cells were large multipolar cells with a spherical nucleus and Nissl' bodies in their cytoplasm. The presence of different types of cones arranged in a mosaic pattern in the retina of this species favors the spatial resolution of visual objects. RESEARCH HIGHLIGHTS: This is the first study demonstrating the structure and arrangement of retinal neurons of red-tail shark using light and electron microscopy. The current study showed the presence of different types of cones arranged in a mosaic pattern that may favor the spatial resolution of visual objects in this species. The bipolar, amacrine, Müller, and horizontal cells could be demonstrated.

Immunohistochemical Characterization of Langerhans Cells in the Skin of Three Amphibian Species.

The amphibian taxon includes three orders that present different morphological characteristics: Anura, Caudata, and Apoda. Their skin has a crucial role: it acts as an immune organ constituting a physical, chemical, immunological, and microbiological barrier to pathogen insult and conducts essential physiological processes. Amphibians have developed specialized features to protect the vulnerable skin barrier, including a glandular network beneath the skin surface that can produce antimicrobial and toxic substances, thus contributing to the defense against pathogens and predators. This study aims to characterize Langerhans cells in the skin of Lithobates catesbeianus (order: Anura; Shaw, 1802), Amphiuma means (order: Caudata; Garden, 1821), and Typhlonectes natans (order: Apoda; Fischer, 1880) with the following antibodies: Langerin/CD207 (c-type lectin), Major Histocompatibility Complex (MHC)II, and Toll-like receptor (TLR)2 (expressed by different types of DCs). Our results showed Langerhans cells positive for Langerin CD/207 in the epidermis of the three species; moreover, some antigen-presenting cells (APCs) in the connective tissue expressed TLR2 and MHCII. The distribution of the Langerhans cells is very similar in the three amphibians examined, despite their different habitats. A greater knowledge of the amphibian immune system could be useful to better understand the phylogeny of vertebrates and to safeguard amphibians from population declines. Furthermore, the similarities between amphibians' and human skin concerning immunological features may be useful in both biology and translational medicine.

Immunohistochemistry of the nasal cavity-associated lymphoid tissue in the dolphin (Stenella coeruleoalba, Meyen 1833).

The striped dolphin (Stenella coeruleoalba) is a medium-sized pelagic dolphin with a single external nasal opening (blowhole) located in the rostral and dorsal regions of the skull. The nasal cavity is divided into three sections: the olfactory, respiratory, and vestibular areas. The surface epithelium lining the regio vestibularis is the first tissue in the nose to be directly affected by environmental antigens. Cetaceans have a significant amount of mucosa-associated lymphoid tissue (MALT) located throughout their bodies. The lymphoid tissue found in the nasal mucosa is known as nose- or nasopharynx-associated lymphoid tissue (NALT). NALT has not yet been studied in dolphins, but it has been identified and documented in humans and laboratory rodents. This study utilized toll-like receptor 2 (TLR2), CD4, Langerin/CD207, and inducible nitric oxide synthase to characterize, for the first time, immune cells in the mucosal regio vestibularis of the S. coeruleoalba nasal cavity using confocal microscopy immunofluorescence techniques. The findings revealed scattered immune cells immunoreactive to the tested antibodies, present in both the epithelial tissue lining the nasal cavity vestibulum and the underlying connective tissue. This study enhances our comprehension of the immune system of cetaceans. RESEARCH HIGHLIGHTS: This study provides new insights into NALT in S. coeruleoalba. This research deepens the knowledge of the skin of cetaceans.

Coelomocytes of the Oligochaeta earthworm Lumbricus terrestris (Linnaeus, 1758) as evolutionary key of defense: a morphological study.

Metazoans have several mechanisms of internal defense for their survival. The internal defense system evolved alongside the organisms. Annelidae have circulating coelomocytes that perform functions comparable to the phagocytic immune cells of vertebrates. Several studies have shown that these cells are involved in phagocytosis, opsonization, and pathogen recognition processes. Like vertebrate macrophages, these circulating cells that permeate organs from the coelomic cavity capture or encapsulate pathogens, reactive oxygen species (ROS), and nitric oxide (NO). Furthermore, they produce a range of bioactive proteins involved in immune response and perform detoxification functions through their lysosomal system. Coelomocytes can also participate in lithic reactions against target cells and the release of antimicrobial peptides. Our study immunohistochemically identify coelomocytes of Lumbricus terrestris scattered in the epidermal and the connective layer below, both in the longitudinal and in the smooth muscle layer, immunoreactive for TLR2, CD14 and α-Tubulin for the first time. TLR2 and CD14 are not fully colocalized with each other, suggesting that these coelomocytes may belong to two distinct families. The expression of these immune molecules on Annelidae coelomocytes confirms their crucial role in the internal defense system of these Oligochaeta protostomes, suggesting a phylogenetic conservation of these receptors. These data could provide further insights into the understanding of the internal defense system of the Annelida and of the complex mechanisms of the immune system in vertebrates.

Expression and function of toll-like receptor 2 in vertebrate.

Toll-like receptors (TLRs) are essential for identifying and detecting pathogen-associated molecular patterns (PAMPs) produced by a variety of pathogens, including viruses and bacteria. Since TLR2 is the only TLR capable of creating functional heterodimers with more than two other TLR types, it is very important for vertebrate immunity. TLR2 not only broadens the variety of PAMPs that it can recognize but has also the potential to diversify the subsequent signaling cascades. TLR2 is ubiquitous, which is consistent with the wide variety of tasks and functions it serves. Immune cells, endothelial cells, and epithelial cells have all been found to express TLR2. This review aims to gather currently available information about the preservation of this intriguing immunological molecule in the phylum of vertebrates.

Association between neuropeptides and mucins in Crohn's disease mucous cells.

Crohn's disease (CD) and ulcerative colitis (UC) are both inflammatory bowel diseases (IBD). Unlike UC, which is limited to the mucosa of the colon, CD inflammation is characterized by chronic mucosal ulcerations affecting the entire gastrointestinal tract. Goblet cells (GCs) can be found in some lining epithelia, particularly in the respiratory and digestive tracts. GCs represent the main source of mucin that are the significant components of the mucus layer; hypertrophy of GCs and an increase in mucin production are observed in many enteric infections. The cytoplasm of goblet cells may also contain neuropeptides, such as serotonin, that can be altered in inflammatory bowel disease (IBD). The defense system of the gut is represented by the intestinal mucosal barrier, its protective function is strictly connected to the regulation of the mucus layer and the coordination of the neuro-immune response. Paraformaldehyde-fixed intestinal tissues, obtained from fifteen patients with Crohn's disease, were analyzed by immunostaining for MUC2, MUC4, 5-HT, and VAChT. This study aims to define the link between neuropeptides and mucins in mucous cells and their involvement in the inflammation process. Our results showed in mucous cells of Crohn's disease (CD) patients a high expression of MUC4 and a decrease in the expression of vesicular acetylcholine transporter (VAChT) demonstrating the presence of an inflammatory state.

Morpho-structural adaptations of the integument in different aquatic organisms.

The integument acts as a barrier to protect the body from harmful pathogenic infectious agents, parasites, UV rays, trauma, and germs. The integument of invertebrates and vertebrates are structurally different: while invertebrates usually have a simple monolayer epidermis frequently covered by mucus, cuticles, or mineralized structures, vertebrates possess a multilayered epidermis with several specialized cells. This study aims to describe by morphological, histological, and immunohistochemical analyses, the morpho-structural adaptations throughout evolution of the integument of gastropod Aplysia depilans (Gmelin, 1791), ascidian Styela plicata (Lesuer, 1823), myxine hagfish Eptatretus cirrhatus (Forster, 1801) and teleost Heteropneustes fossilis (Bloch, 1794) for the first time, with special reference to sensory epidermal cells. Different types of cells could be identified that varied according to the species; including mucous cells, serous glandular cells, clavate cells, club cells, thread cells, and support cells. In all integuments of the specimens analyzed, sensory solitary cells were identified in the epidermis, immunoreactive to serotonin and calbindin. Our study provided an essential comparison of integuments, adding new information about sensory epidermal cells phylogenetic conservation and on the structural changes that invertebrates and vertebrates have undergone during evolution.

Chemical analysis, biological and therapeutic activities of Olea europaea L. extracts.

The Olea europaea L. is a very well-known and widely used plant, especially for its nutritional qualities. Its extracts from leaves and fruits are widely used in contrasting and preventing various pathologies. In this review, the collected data highlight important chemical analyses and biological effects of this plant extracts. It exhibits cholesterol-lowering, hypoglycemic, cytotoxic, antibacterial, neuroprotective, antioxidant, anti-inflammatory and hypotensive activities. The results show that extracts from O. europaea could be used as a food additive in the supplementary treatment of many diseases.

Localization of vasoactive intestinal peptide and toll-like receptor 2 immunoreactive cells in endostyle of urochordate Styela plicata (Lesueur, 1823).

The endostyle is the first component of the ascidian digestive tract, it is shaped like a through and is located in the pharynx's ventral wall. This organ is divided longitudinally into nine zones that are parallel to each other. Each zone's cells are physically and functionally distinct. Support elements are found in zones 1, 3, and 5, while mucoproteins secreting elements related to the filtering function are found in zones 2, 4, and 6. Zones 7, 8, and 9, which are located in the lateral dorsal section of the endostyle, include cells with high iodine and peroxidase concentrations. Immunohistochemical technique using the following antibodies, Toll-like receptor 2 (TLR-2) and vasoactive intestinal peptide (VIP), and lectin histochemistry (WGA-wheat-germagglutinin), were used in this investigation to define immune cells in the endostyle of Styela plicata (Lesueur, 1823). Our results demonstrate the presence of immune cells in the endostyle of S. plicata, highlighting that innate immune mechanisms are highly conserved in the phylogeny of the chordates. RESEARCH HIGHLIGHTS: Immune cells positive to TLR-2 and VIP in the endostyle of Styela plicata. Expression of WGA in several zones of endostyle. Use of comparative biology to improve the knowledge about immunology in ascidians.

Rodlet cells in kidney of goldfish (Carassius auratus, Linnaeus 1758): A light and confocal microscopy study.

Rodlet cells (RCs) have always been an enigma for scientists. RCs have been given a variety of activities over the years, including ion transport, osmoregulation, and sensory function. These cells, presumably as members of the granulocyte line, are present only in teleosts and play a role in the innate immune response. RCs are migratory cells found in a variety of organs, including skin, vascular, digestive, uropoietic, reproductive, and respiratory systems, and present distinct physical properties that make them easily recognizable in tissues and organs. The development of RCs can be divided into four stages: granular, transitional, mature, and ruptured, having different morphological characteristics. Our study aims to characterize the different stages of these cells by histomorphological and histochemical techniques. Furthermore, we characterized these cells at all stages with peroxidase and fluorescence immunohistochemical techniques using different antibodies: S100, tubulin, α-SMA, piscidin, and for the first time TLR-2. From our results, the immunoreactivity of these cells to the antibodies performed may confirm that RCs play a role in fish defense mechanisms, helping to expand the state of the art on immunology and immune cells of teleosts.

Role of Serotonin in the Maintenance of Inflammatory State in Crohn's Disease.

Crohn's disease (CD) is a chronic intestinal inflammation considered to be a major entity of inflammatory bowel diseases (IBDs), affecting different segments of the whole gastrointestinal tract. Peripheral serotonin (5-HT), a bioactive amine predominantly produced by gut enterochromaffin cells (ECs), is crucial in gastrointestinal functions, including motility, sensitivity, secretion, and the inflammatory response. These actions are mediated by a large family of serotonin receptors and specialized serotonin transporter (SERT) located on a variety of cell types in the gut. Several studies indicate that intestinal 5-HT signaling is altered in patients with inflammatory bowel disease. Paraformaldehyde-fixed intestinal tissues, obtained from fifteen patients with Crohn's disease were analyzed by immunostaining for serotonin, Langerin/CD207, and alpha-Smooth Muscle Actin (α-SMA). As controls, unaffected (normal) intestinal specimens of seven individuals were investigated. This study aimed to show the expression of serotonin in dendritic cells (DCs) and myofibroblast which have been characterized with Langerin/CD207 and α-SMA, respectively; furthermore, for the first time, we have found the presence of serotonin in goblet cells. Our results show the correlation between different types of intestinal cells in the maintenance of the inflammatory state in CD linked to the recall of myofibroblasts.

Immune System and Psychological State of Pregnant Women during COVID-19 Pandemic: Are Micronutrients Able to Support Pregnancy?

The immune system is highly dynamic and susceptible to many alterations throughout pregnancy. Since December 2019, a pandemic caused by coronavirus disease 19 (COVID-19) has swept the globe. To contain the spread of COVID-19, immediate measures such as quarantine and isolation were implemented. These containment measures have contributed to exacerbate situations of anxiety and stress, especially in pregnant women, who are already particularly anxious about their condition. Alterations in the psychological state of pregnant women are related to alterations in the immune system, which is more vulnerable under stress. COVID-19 could therefore find fertile soil in these individuals and risk more severe forms. Normally a controlled dietary regimen is followed during pregnancy, but the use of particular vitamins and micronutrients can help counteract depressive-anxiety states and stress, can improve the immune system, and provide an additional weapon in the defense against COVID-19 to bring the pregnancy to fruition. This review aims to gather data on the impact of COVID-19 on the immune system and psychological condition of pregnant women and to assess whether some micronutrients can improve their psychophysical symptoms.

Confocal Characterization of Intestinal Dendritic Cells from Myxines to Teleosts.

Dendritic cells (DCs) are antigen-presenting cells (APCs) that regulate the beginning of adaptive immune responses. The mechanisms of tolerance to antigens moving through the digestive tract are known to be regulated by intestinal DCs. Agnatha and Gnathostoma are descendants of a common ancestor. The Ostracoderms gave rise to Cyclostomes, whereas the Placoderms gave rise to Chondrichthyes. Sarcopterygii and Actinopterygii are two evolutionary lines of bony fishes. Brachiopterygii and Neopterygii descend from the Actinopterygii. From Neopterygii, Holostei and Teleostei evolved. Using immunohistochemistry with TLR-2, Langerin/CD207, and MHC II, this study aimed to characterize intestinal DCs, from myxines to teleosts. The findings reveal that DCs are positive for the antibodies tested, highlighting the presence of DCs and DC-like cells phylogenetically from myxines, for the first time, to teleosts. These findings may aid in improving the level of knowledge about the immune system's evolution and these sentinel cells, which are crucial to the body's defense.

Immunogenicity, effectiveness, safety and psychological impact of COVID-19 mRNA vaccines.

In December 2019, a new single-stranded RNA coronavirus, SARS-CoV-2, appeared in China and quickly spread around the world leading to a pandemic. Infection with SARS-CoV-2 generates symptoms ranging from asymptomatic to severe, occasionally requiring hospitalization in intensive care units, and, in more severe cases, leading to death. Scientists and researchers around the world have made a real race against time to develop various vaccines to slow down and stop the spread of the virus. In addition to conventional viral vector vaccines, new generation mRNA vaccines, BNT152b2 (Comirnaty) and mRNA-1273 (Spikevax), have been developed respectively by Pfizer/BioNTech and Moderna. These vaccines act on immune cells to induce an immune response with the production of specific antibodies against Spike protein of SARS-CoV-2, and to stimulate the differentiation of T and B memory cells. The objective of this review is to provide a detailed picture of the validity of these new vaccines and the safety of vaccination. Not only was the immunogenic effect of mRNA vaccines evaluated, but also the psychosocial impact they had on the population. The data collected show that this type of vaccine can also be an excellent candidate for future treatment and eradication of possible new pathologies with viral and non-viral etiology.

Confocal Identification of Immune Molecules in Skin Club Cells of Zebrafish (Danio rerio, Hamilton 1882) and Their Possible Role in Immunity.

The immune system of a fish has cellular and molecular defense mechanisms that are substantially retained throughout the evolution of vertebrates. The innate immune system provides biological processes, such as phagocytosis and mechanical barriers, to implement an efficient defensive response after exposure to chemical or biological contaminants, pollutants, and contact with parasites, germs, and pathogens. Club cells (CCs) are widespread in the skin of Ostariophysi. After a predator attack or exposure to toxins and parasites, these cells can produce alarming substances. Given their effectiveness against viruses, parasites, and common skin lesions, recent studies have suggested that CCs are a component of the immune system. This study aims to immunohistochemically characterize the CCs for the first time in the skin of zebrafish, using mitogen-activated protein kinase (MAPK) p38, Toll-like receptor (TLR)2, Piscidin1, and inducible nitric oxide synthase (iNOS) peptides involved in the function of all types of vertebrate immune cells. According to our analysis, the intermediate layer of the epidermis exhibited rounded, oval, and elongated CCs, with central acidophilic cytoplasm and a spherical basophilic nucleus, that are positive to the antibodies tested. Our results may confirm that CCs could be involved in the immune function, increasing our knowledge of the immune system of teleosts.

Detecting Intestinal Goblet Cells of the Broadgilled Hagfish Eptatretus cirrhatus (Forster, 1801): A Confocal Microscopy Evaluation.

The fish intestine operates as a complicated interface between the organism and the environment, providing biological and mechanical protections as a result of a viscous layer of mucus released by goblet cells, which serves as a barrier against bacteria, viruses, and other pathogens, and contributes to the functions of the immune system. Therefore, goblet cells have a role in preserving the health of the body by secreting mucus and acting as sentinels. The ancient jawless fish broadgilled hagfish (Eptatretus cirrhatus, Forster, 1801) has a very basic digestive system because it lacks a stomach. By examining the presence, localization, and co-localization of 5-HT, TLR2, iNOS, and Piscidin1, this study intends to provide insight into the potential immune system contributions arranged by the gut goblet cells of broadgilled hagfish. Our results characterize intestinal goblet cells of broadgilled hagfish, for the first time, with the former antibodies, suggesting the hypothesis of conservation of the roles played by these cells also in primitive vertebrates. Moreover, this study deepens the knowledge about the still little-known immune system of hagfish.