Neurotoxic stimulation alters prosaposin levels in the salivary systems of rats.

Prosaposin (PSAP), a potent neurotrophic factor, is found in neuronal and non-neuronal tissues and various biological fluids. Neuropathological conditions often alter PSAP production in neural tissues. However, little is known about its alterations in non-neural tissues, particularly in the salivary glands, which are natural reservoirs of various neurotrophic factors. In this study, we explored whether neurotoxic stimulation by kainic acid (KA), a glutamate analog, altered PSAP levels in the salivary system of rats. The results revealed that KA injection did not alter total saliva production. However, KA-induced neurotoxic stimulation significantly increased the PSAP level in the secreted saliva but decreased it in the serum. In addition, KA-induced elevated immunoreactivities of PSAP and its receptors have been observed in the granular convoluted tubule (GCT) cells of the submandibular gland (SMG), a major salivary secretory organ. Indeed, a large number of PSAP-expressing immunogold particles were observed in the secretory granules of the SMG. Furthermore, KA-induced overexpression of PSAP was co-localized with secretogranin in secretory acini (mostly in GCT cells) and the ductal system of the SMG, suggesting the release of excess PSAP from the salivary glands into the oral cavity. In conclusion, the salivary system produces more PSAP during neurotoxic conditions, which may play a protective role in maintaining the secretory function of the salivary glands and may work in distant organs.

Tracking of Prosaposin, a Saposin Precursor, in Rat Testis.

We tracked prosaposin (PSAP), a trophic factor, using an antibody specific to its proteolytic portion and an antibody to sortilin that traffics PSAP only to the lysosome. Immunostaining revealed that PSAP was distributed mainly on the basal side of seminiferous tubules, where many Sertoli cells and pachytene spermatocytes contained PSAP and its distribution differed depending on the stage of the spermatogenic cycle. The PSAP-sortilin complex was sorted to large lysosomes in the basal cytoplasm of Sertoli cells, where it may be processed into saposins. In contrast, in the thinner apical cytoplasm of Sertoli cells, PSAP in small lysosomes was transported to the apical side around sperm heads or into the lumen for secretion. The results of in situ hybridization analyses suggested that immature tubular cells in young animals produce PSAP to self-stimulate proliferation. However, in adults, not only Sertoli cells but also pachytene spermatocytes produce and secrete PSAP around germ cells or into the tubular lumen to stimulate cell proliferation or differentiation in a paracrine or autocrine manner. In summary, PSAP is not only a precursor of lysosomal enzymes but also a pivotal trophic factor in organogenesis in the immature testis and spermatogenesis in the mature testis.

Administration of prosaposin-derived neurotrophic factor to neural tube defects facilitates regeneration and restores neurological functions.

Neural tube defects (NTDs) cause fetal and pediatric deaths or lifelong neurological disabilities. No effective treatment is currently available for NTDs. We attempted to elucidate the pathogenesis of NTDs and propose a therapeutic strategy. Intra-amniotic treatment with prosaposin-derived 18-mer peptide (PS18) protected the spinal cord from secondary damage and rescued neurological function in an established chicken model of spina bifida aperta (SBA), the severe type of NTDs. PS18 promoted the formation of a neuroectodermal covering over the defective neural tube within 24-h after treatment, enhanced the regeneration/restoration process, and decreased apoptotic activity in the developing spinal cord. PS18 reduced the SBA wound and almost completely formed the spinal cord. SBA chicks that received PS18 exhibited relatively normal walking and sensorimotor responses, and reduced pain-associated behavior in postnatal life. In conclusion, PS18 is a promising therapeutic agent for NTDs and may be useful for treating other types of spinal cord injuries.

A comprehensive design for prevention and management of COVID-19 in a tertiary medical institution in Bangladesh.

INTRODUCTION: Containment of the further spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and reducing fatality due to coronavirus disease 19 (COVID-19) represent a pressing challenge to global health services. Here, we present a management blueprint for both the containment of SARS-CoV-2 and treatment of COVID-19 through a comprehensive approach. METHODOLOGY: A cohort of 130 consecutive patients identified as positive for SARS-CoV-2 by testing of nasal swab by polymerase chain reaction were managed at a peripheral city of Bangladesh between 1 April and 31 May, 2020. Based on their clinical status, 64 of them were initially selected for isolation (Isolation Group) and 66 recommended for hospitalization (Hospital Group) as per the direction of the "Central COVID-19 Control" Center. Both groups of patients were allocated to receive standard of care management and oxygen inhalation, and intensive care unit management as and when necessary. Based on the conditions of the COVID-19 patients, there was an active system of patients being transferred from the "Isolation Group" to "Hospital Group" and vice versa. RESULTS: Twelve patients of the "Isolation Group" were transferred to the hospital, as they exhibited symptoms of deterioration. Four patients of the "Hospital Group" died during the observation period of two months in the intensive care unit. However, there has been no fatality among the patients of the "Isolation Group". CONCLUSIONS: The concept of "Isolation" and "Hospital Management" with the participation of the community seems to be an effective management strategy for COVID-19 in developing countries.

The expression of prosaposin and its receptors, GRP37 and GPR37L1, are increased in the developing dorsal root ganglion.

Prosaposin (PSAP), a highly conserved glycoprotein, is a precursor of saposins A-D. Accumulating evidence suggests that PSAP is a neurotrophic factor, as well as a regulator of lysosomal enzymes. Recently, the orphan G-protein-coupled receptors GPR37 and GPR37L1 were recognized as PSAP receptors, but their functions have not yet been clarified. In this study, we examined the distribution of PSAP and its receptors in the dorsal root ganglion (DRG) during development using specific antibodies, and showed that PSAP accumulates primarily in lysosomes and is dispersed throughout the cytoplasm of satellite cells. Later, PSAP colocalized with two receptors in satellite cells, and formed a characteristic ring shape approximately 8 weeks after birth, during a period of rapid DRG development. This ring shape, which was only observed around larger neurons, is evidence that several satellite cells are synchronously activated. We found that sortilin, a transporter of a wide variety of intracellular proteins containing PSAP, is strongly localized to the inner side of satellite cells, which contact the neuronal surface. These findings suggest that PSAP and GPR37/GPR37L1 play a role in activating both satellite and nerve cells.

Inhibition of low-density lipoprotein uptake by Helicobacter pylori virulence factor CagA.

Helicobacter pylori (H. pylori) infection mainly causes gastroduodenal diseases, including chronic gastritis, peptic ulcer disease and gastric cancer. In recent years, several studies have demonstrated that infection with H. pylori, especially strains harboring the virulence factor CagA (cytotoxin-associated gene A), contribute to the development of non-gastric systemic diseases, including hypercholesterolemia and atherosclerotic cardiovascular diseases. However, mechanisms underlying this association has not been defined. In this study, we carried out a large-scale genetic screen using Drosophila and identified a novel CagA target low-density lipoprotein receptor (LDLR), which aids in the clearance of circulating LDL. We showed that CagA physically interacted with LDLR via its carboxy-terminal region and inhibited LDLR-mediated LDL uptake into cells. Since deficiency of LDLR-mediated LDL uptake has been known to increase plasma LDL and accelerate atherosclerosis, our findings may provide a novel mechanism for the association between infection with CagA-positive H. pylori and hypercholesterolemia leading to atherosclerotic cardiovascular diseases.

Reply to "Ivermectin Treatment May Improve the Prognosis of Patients With COVID-19" / Respuesta a "El tratamiento con ivermectina puede mejorar el pronóstico de los pacientes con COVID-19"

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Reply to "Ivermectin Treatment May Improve the Prognosis of Patients With COVID-19" / Respuesta a "El tratamiento con ivermectina puede mejorar el pronóstico de los pacientes con COVID-19"

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Prosaposin, a neurotrophic factor, protects neurons against kainic acid-induced neurotoxicity.

Prosaposin (PS) is the precursor of four sphingolipid activator proteins, saposin A-D. PS is both a precursor protein and a neuroprotective factor, and is up-regulated in response to excitotoxicity induced by kainic acid (KA), a glutamate analogue. Excess glutamate release induces neuropathological disorders such as ischemia and seizure. Our group's research revealed that PS immunoreactivity (IR) increased significantly in the hippocampal and cortical neurons on day 3 after KA injection, and high PS levels were maintained even after 3 weeks. The increase in PS, but not saposins, as detected by immunoblotting, suggests that the increase in PS-IR after KA injection was not caused by an increase in saposins acting as lysosomal enzymes after neuronal damage but, rather, by an increase in PS as a neurotrophic factor to improve neuronal survival. An 18-mer peptide (PS18) derived from the PS neurotrophic region significantly protected hippocampal neurons against KA-induced destruction. Furthermore, parvalbumin-positive GABAergic inhibitory interneurons and their axons exhibited intense PS expression. These results suggest that axonally transported PS protects damaged hippocampal pyramidal neurons from KA-induced neurotoxicity. Further in vitro studies that include the transfection of the PS gene will help with clarifying the mechanisms underlying the transport and secretion of PS.

Prosaposin in the rat oviductal epithelial cells.

Prosaposin (PSAP) has two forms: a precursor and a secreted form. The secreted form has neurotrophic, myelinotrophic, and myotrophic properties. The precursor form is a precursor protein of saposins A-D. Although the distribution of PSAP in male reproductive organs is well known, its distribution in female reproductive organs, especially in the oviduct, is unclear. Immunoblots and immunohistochemistry of oviducts showed that oviductal tissues contain PSAP proteins, and a significant increase in PSAP was observed in the estrus-metestrus phase compared to the diestrus-proestrus phase in the ampulla. To identify PSAP trafficking in cells, double-immunostaining was performed with antibodies against PSAP in combination with sortilin, mannose 6 phosphate receptor (M6PR), or low-density lipoprotein receptor-related protein 1 (LRP1). PSAP and sortilin double-positive reactions were observed near the nuclei, as well as in the apical portion of microvillous epithelial cells, whereas these reactions were only observed near the nuclei of ciliated epithelial cells. PSAP and M6PR double-positive reactions were observed near the nuclei of microvillous and ciliated epithelial cells. PSAP and M6PR double-positive reactions were also observed in the apical portion of microvillous epithelial cells. PSAP and LRP1 double-positive reactions were observed in the plasma membrane and apical portion of both microvillous and ciliated epithelial cells. Immunoelectron staining revealed PSAP immunoreactive small vesicles with exocytotic features at the apical portion of microvillous epithelial cells. These findings suggest that PSAP is present in the oviductal epithelium and has a pivotal role during pregnancy in providing an optimal environment for gametes and/or sperm in the ampulla.

Expression of the G protein-coupled receptor (GPR) 37 and GPR37L1 in the mouse digestive system.

G protein-coupled receptor (GPR) 37 and GPR37L1 are known to modulate the dopaminergic neuron activity, and recently, they are identified as candidate prosaposin receptors. Intercellular prosaposin is proteolytically processed into four saposins, each of which acts as a sphingolipid hydrolase activator in the lysosome. In contrast, extracellular prosaposin exerts a trophic effect on neurons via GPR37 and GPR37L1. In this study, the expression patterns of GPR37 and GPR37L1 in the mouse digestive system were examined immunohistochemically. The islets of Langerhans of the pancreas showed intense immunoreactivity for GPR37 and GPR37L1. Weak immunoreactivity for GPR37 and GPR37L1 was found in the nerve plexuses of the esophagus and small and large intestines. Colocalization of GPR37 and tyrosine hydroxylase immunoreactivity was observed in the neuron of the nerve plexus of the large intestine. This study suggests the possibility that prosaposin affects the function of islet-secreting cells. Also, the expression of GPR37 and GPR37L1 in the nerve plexus suggests that prosaposin exerts a trophic effect not only in the central nervous system, but also in the enteric nervous system.

Prosaposin and its receptors GRP37 and GPR37L1 show increased immunoreactivity in the facial nucleus following facial nerve transection.

Neurotrophic factor prosaposin (PS) is a precursor for saposins A, B, C, and D, which are activators for specific sphingolipid hydrolases in lysosomes. Both saposins and PS are widely contained in various tissues. The brain, skeletal muscle, and heart cells predominantly contain unprocessed PS rather than saposins. PS and PS-derived peptides stimulate neuritogenesis and increase choline acetyltransferase activity in neuroblastoma cells and prevent programmed cell death in neurons. We previously detected increases in PS immunoactivity and its mRNA in the rat facial nucleus following facial nerve transection. PS mRNA expression increased not only in facial motoneurons, but also in microglia during facial nerve regeneration. In the present study, we examined the changes in immunoreactivity of the PS receptors GPR37 and GPR37L1 in the rat facial nucleus following facial nerve transection. Following facial nerve transection, many small Iba1- and glial fibrillary acidic protein (GFAP)-positive cells with strong GPR37L1 immunoreactivity, including microglia and astrocytes, were observed predominately on the operated side. These results indicate that GPR37 mainly works in neurons, whereas GPR37L1 is predominant in microglia or astrocytes, and suggest that increased PS in damaged neurons stimulates microglia or astrocytes via PS receptor GPR37L1 to produce neurotrophic factors for neuronal recovery.

Ivermectin Treatment May Improve the Prognosis of Patients With COVID-19 / El tratamiento con ivermectina puede mejorar el pronóstico de los pacientes con COVID-19

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Suppression of GABAergic transmission in the spinal dorsal horn induces pain-related behaviour in a chicken model of spina bifida.

Spina bifida aperta (SBA), one of the most common congenital malformations, causes various neurological disorders. Pain is a common complaint of patients with SBA. However, little is known about the neuropathology of SBA-related pain. Because loss of g-aminobutyric acid GABAergic neurons in the spinal cord dorsal horn is associated with pain, we hypothesised the existence of crosstalk between SBA-related pain and alterations in GABAergic transmission in the spinal cord. Therefore, we investigated the kinetics of GABAergic transmission in the spinal cord dorsal horn in a chicken model of SBA. Neonatal chicks with SBA exhibited various pain-like behaviours, such as an increased number of vocalisations with elevated intensity (loudness) and frequency (pitch), reduced mobility, difficulty with locomotion, and escape reactions. Furthermore, the chicks with SBA did not respond to standard toe-pinching, indicating disruption of the spinal cord sensorimotor networks. These behavioural observations were concomitant with loss of GABAergic transmission in the spinal cord dorsal horn. We also found apoptosis of GABAergic neurons in the superficial dorsal horn in the early neonatal period, although cellular abnormalisation and propagation of neuro-degenerative signals were evident at middle to advanced gestational stages. In conclusion, ablation of GABAergic neurons induced alterations in spinal cord neuronal networks, providing novel insights into the pathophysiology of SBA-related pain-like complications.

Age- and sex-associated changes in prosaposin and its receptors in the lacrimal glands of rats.

Prosaposin, a saposin precursor, is a potent neurotrophic factor found in several tissues and various biological fluids. Saposin-deficient patients have different ophthalmic disorders, indicating a relationship between ocular health and prosaposin. However, there is little information about prosaposin on the ocular surface. Because ocular functions are diverse and depend on age and sex, we examined whether prosaposin and its receptors, G protein-coupled receptor 37 (GPR37) and GPR37L1, are expressed in the major ocular glands, the extra orbital lacrimal gland (ELG), and harderian gland (HG) of rats and whether sex and aging affect their expression. Immunohistochemical analyses revealed that prosaposin and its receptors were expressed in the ELGs and HGs of rats, although their expression varied based on the type of gland, age, and sex. Prosaposin, GPR37, and GPR37L1 were expressed in the basolateral membranes and cytoplasm of acinar cells of the ELGs, and their immunoreactivities were higher in female rats of menopausal age than age-matched male rats. However, such age- and sex-related differences in the immunoreactivities of prosaposin, GPR37, and GPR37L1 were not observed in the HGs. Triple immunofluorescence labelling revealed that prosaposin, GPR37, and GPR37L1 were co-localised in the acinar and ductal cells in the ELGs, although the degrees of colocalization varied according to the age and sex of the rats. Together, the present results showed that prosaposin and its receptors were expressed in the major ocular glands of rats, and their immunoreactivities to the ELGs differed considerably with age and sex.

Prosaposin and its receptors are differentially expressed in the salivary glands of male and female rats.

Salivary glands produce various neurotrophins that are thought to regulate salivary function during normal and pathological conditions. Prosaposin (PSAP) is a potent neurotrophin found in several tissues and various biological fluids and may play roles in the regulation of salivary function. However, little is known about PSAP in salivary glands. As the functions of salivary glands are diverse based on age and sex, this study examines whether PSAP and its receptors, G protein-coupled receptor 37 (GPR37) and GPR37L1, are expressed in the salivary glands of rats and whether sex and aging affect their expression. Immunohistochemical analysis revealed that PSAP and its receptors were expressed in the major salivary glands of rats, although their expression varied considerably based on the type of gland, acinar cells, age and sex. In fact, PSAP, GPR37 and GPR37L1 were predominantly expressed in granular convoluted tubule cells of the submandibular gland and the intensity of their immunoreactivity was higher in young adult female rats than age-matched male rats, which was more prominent at older ages (mature adult to menopause). On the other hand, weak PSAP, GPR37 and GPR37L1 immunoreactivity was observed mainly in the basal layer of mucous cells of the sublingual gland. Triple label immunofluorescence analysis revealed that PSAP, GPR37 and GPR37L1 were co-localized in the basal layer of acinar and ductal cells in the major salivary glands. The present findings indicate that PSAP and its receptors, GPR37 and GPR37L1, are expressed in the major salivary glands of rats and their immunoreactivities differ considerably with age and sex.