Search Results (64)

Aquaporin 1 is a membrane water channel protein, which was studied here in spiny dogfish (Squalus acanthias) osmoregulatory tissues using a variety of techniques. The cloning of aquaporin 1 (AQP1) in the spiny dogfish identified a splice variant version of the mRNA/protein (AQP1SV1/AQP1SV1). Polymerase chain reaction (PCR) in a range of tissues showed AQP1 to be expressed at very high levels in the rectal gland with ubiquitous mRNA expression at lower levels in other tissues. Northern blotting showed that AQP1 had a mRNA size of 5.3 kb in kidney total RNA. The level of AQP1 mRNA was significantly lower in the rectal glands of fish acclimated to 120% seawater (SW; vs. 75% SW (p = 0.0007) and 100% SW (p = 0.0025)) but was significantly higher in those fish in the kidney (vs. 100% SW (p = 0.0178)) and intestine (vs. 75% SW (p= 0.0355) and 100% SW (p = 0.0285)). Quantitative PCR determined that AQP1SV1 mRNA levels were also significantly lower in the rectal glands of both 120% (p = 0.0134) and 100% SW (p = 0.0343) fish in comparison to 75% SW-acclimated dogfish. Functional expression in Xenopus oocytes showed that AQP1 exhibited significant apparent membrane water permeability (p = 0.000008–0.0158) across a range of pH values, whereas AQP1SV1 showed no similar permeability. Polyclonal antibodies produced against AQP1 (AQP1 and AQP1/2 antibodies) and AQP1SV1 had bands at the expected sizes of 28 kDa and 24 kDa, respectively, as well as some other banding. The weak AQP1 antibody and the stronger AQP1/2 antibody exhibited staining in the apical membranes of rectal gland secretory tubules, particularly towards the periphery of the gland. In the gill, the AQP1/2 antibody in particular showed staining in secondary-lamellar pavement-cell basal membranes, and in blood vessels and connective tissue in the gill arch. In the spiral valve intestine side wall and valve flap, the AQP1/2 antibody stained muscle tissue and blood vessel walls and, after tyramide signal amplification, showed some staining in the apical membranes of epithelial cells at the ends of the luminal surface of epithelial folds. In the rectum/colon, there was also some muscle and blood vessel staining, but the AQP1 and AQP1/2 antibodies both stained a layer of cells at the base of the surface epithelium. In the kidney convoluted bundle zone, all three antibodies stained bundle sheath membranes to variable extents, and the AQP1/2 antibody also showed staining in the straight bundle zone bundle sheath. In the kidney sinus zone, the AQP1/2 antibody stained the apical membranes of late distal tubule (LDT) nephron loop cells most strongly, with the strongest staining in the middle of the LDT loop and in patches towards the start of the LDT loop. There was also a somewhat less strong staining of segments of the first sinus zone nephron loop, particularly in the intermediate I (IS-I) tubule segment. Some tubules appeared to show no or only low levels of staining. The results suggest that AQP1 plays a role in rectal gland fluid secretion, kidney fluid reabsorption and gill pavement-cell volume regulation and probably a minor role in intestinal/rectal/colon fluid absorption. Full article

Hemolytic anemias (HAs) encompasses a heterogeneous group of disorders with either congenital or acquired etiologies. We present a complex case of a 27-year-old woman with hemolytic anemia of multifactorial origin, involving both inherited RBC membrane defects and multiple autoimmune comorbidities. Genetic testing identified heterozygous variants in SPTA1 and SBDS, consistent with carrier status for hereditary elliptocytosis and Shwachman–Diamond syndrome. The patient was also diagnosed with Caspr2-positive Isaacs syndrome, systemic lupus erythematosus, seronegative antiphospholipid syndrome, and anti-aquaporin-4 antibody-positive optic neuritis. Despite extensive immunosuppressive and immunotherapic treatment and splenectomy, the clinical course was marked by recurrent hemolytic crises, thrombotic complications, and progressive neurological involvement, ultimately leading to death. Our experience highlights the challenges posed by the diagnosis and management of HAs, underlining the relevance of a multidisciplinary and personalized approach. Full article

Extracellular vesicles (EVs) have a key role in intercellular communication. We hypothesized that EVs are biomarkers of nephropathy or kidney allograft rejection. We screened patients with chronic kidney disease (CKD) and kidney transplant (KT) recipients. We measured the urine and plasma levels of total EVs overall and EV subpopulations (positive for podocalyxin, aquaporin-1, CD133, CD144, CD19, CD3, CD16, CD56, or CD41). We included 92 patients with CKD, 70 KT recipients, and 33 healthy volunteers. In CKD, the total urine EV concentration was correlated positively with the estimated glomerular filtration rate (eGFR), but none of the subpopulations was identified as a potential biomarker of nephropathy. Among the KT recipients, 30 had good allograft function and 40 had allograft disease (13 with antibody-mediated rejections (ABMR), 12 with T-cell-mediated rejection (TCMR), and 15 with allograft dysfunction). Patients with ABMR had low plasma levels of EVs derived from B-cells, T-cells, and endothelium (p = 0.003, 0.009, and 0.005, respectively). Patients with TCMR had a low urine level of EVs derived from endothelium (p = 0.05). EVs derived from B-cells, T-cells, and endothelium might be biomarkers of kidney allograft rejection. However, we did not identify biomarkers of nephropathy in CKD. Full article

To clarify T-cell responses in myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), we cultured the peripheral blood mononuclear cells of 24 patients with MOGAD and 20 with aquaporin-4 (AQP4) antibody-positive neuromyelitis optica spectrum disorders (NMOSD), and those of 17 healthy controls (HCs), in the presence of fourteen MOG peptides covering the full-length MOG, five AQP4 peptides, two myelin basic protein peptides, or two proteolipid protein peptides. Then, we measured T-cell activation markers, such as cell surface CD69 and the intracellular production of granulocyte–macrophage colony-stimulating factor (GM-CSF) and interferon-γ in CD4-positive T-cells, with a flow cytometer. The expression of CD69 in response to MOG p16–40 and MOG p181–205 was significantly higher (Stimulation Index > 2) in MOGAD than in HCs. Also, CD69 for AQP4 p21–40, AQP4 p211–230, and MOG p166–190 were significantly increased in NMOSD than in HCs. Intracellular GM-CSF production responding to MOG p16–40 was significantly higher in MOGAD than in HCs (p < 0.05), although intracellular interferon-γ was not elevated. None of the responses to the other peptides were different between the groups. The present study showed subtle CD4-positive T-cell activation elicited by some MOG peptides alone in patients with MOGAD. Further studies of cytokines or other stimulation and alternative assay markers and metrics are needed to delineate the immunopathological roles of T-cells in MOGAD. Full article

Background/Objectives: Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune-related neurological disease that primarily affects the optic nerve and spinal cord. According to current international consensus guidelines for NMOSD, confirming the presence of aquaporin-4 immunoglobulin G antibody (AQP4-IgG) is one of the most important diagnostic criteria because AQP4-IgG is a significant diagnostic biomarker of NMOSD. Several assays are currently available for detecting AQP4-IgG, including cell-based assays (CBAs) and enzyme-linked immunosorbent assays (ELISAs). However, each assay has certain disadvantages, including insufficient sensitivity and specificity, the need for sophisticated techniques, and semi-quantitative results. Methods: We developed a fully automated chemiluminescent enzyme immunoassay (CLEIA) to detect AQP4-IgG (AQP4-CLEIA). This assay utilizes the recombinant antigen purified from the newly generated AQP4-M23 stably expressing Chinese hamster ovary cell line and an anti-AQP4 monoclonal antibody as a calibrator. Results: In analytical performance studies, the assay demonstrates good precision and linearity over the entire measurement range. Moreover, this assay showed no high-dose hook effect and interference from endogenous substances. In clinical validation studies, patients with AQP4-IgG positive NMOSD, multiple sclerosis, or myelin oligodendrocyte glycoprotein antibody-associated disorder and healthy individuals were tested. A cutoff value of 10.0 U/mL was determined by receiver operating characteristic curves based on the results of a microscopic live CBA. The sensitivity and specificity for AQP4-IgG-positive NMOSD were 97.0% and 100.0%, respectively, at the cutoff value. Conclusions: The results suggest that AQP4-CLEIA is a convenient automated method for measuring AQP4-IgG titers in hospitals and clinical laboratories, offering an effective alternative to the gold-standard CBA. Full article

The sequence of Aquaporin 12 (AQP12) cDNA was amplified from spiny dogfish (Squalus acanthias) cDNAs using degenerate PCR, followed by 5′ and 3′ RACE PCR. The AQP12 nucleotide sequence had an open reading frame of 300 amino acids, which included one or more N-glycosylation sites. Degenerate and tissue PCRs revealed that AQP12 is expressed at the highest levels in the liver, followed by the pyloric stomach and the esophagus/cardiac stomach, with a small amount potentially present in the eye. A polyclonal antibody was made using a peptide from the derived amino acid sequence. Western blotting with the antibody showed faint banding around the size expected (33 kDa) by the 300 amino acid protein. A few more intense bands were seen at around 40 kDa and larger sizes. Immunohistochemistry in cardiac stomach tissue sections showed staining in a few sporadic paneth-like secretory cells along the surface of the epithelium. High-magnification imaging showed that the AQP12 staining was located in the membrane of secretory granules in the apical pole of the cells. This localization is reminiscent of the AQP12 localization in pancreatic acinar cells, where it is found in the membrane of zymogen granules containing digestive enzymes. Full article

Background and Clinical Significance: Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune demyelinating disorder of the central nervous system, characterized by the presence of aquaporin-4 (AQP4) antibodies and a high relapse rate. We provide information about the diagnosis, unusual symptoms, and treatment of a paediatric patient with NMOSD. Case Presentation: A 14-year-old girl was hospitalized for weakness and paraesthesia of the lower limbs (LL). The patient underwent detailed investigations and was diagnosed with NMOSD and cryptogenic organizing pneumonia. Initial treatment with methylprednisolone and prednisone yielded a favourable response. Therapy with mycophenolate was initiated. However, the patient experienced two more relapses, prompting the use of rituximab therapy with a favourable outcome and a two-year relapse-free follow-up period. Conclusions: Patients with NMOSD may have multisystemic inflammation, including organs outside the central nervous system. Our case report highlights a case of NMOSD, pulmonary involvement, and unusual adverse reactions to rituximab. Full article

Little information is available on how rhizosphere bacteria affect abscisic acid (ABA) levels in plants and whether these bacterial effects are associated with improved plant water status. In this study, we tested the hypothesis that the stimulation of plant growth may be associated with the ability of ABA to increase the hydraulic conductivity of roots through the up-regulation of aquaporin. To do this, we studied the effect of bacteria capable of producing ABA on a barley mutant deficient in this hormone. Measurements of hydraulic conductivity of the ABA-deficient barley mutant Az34 showed that its tissues exhibited a reduced ability to conduct water, which correlated with lower ABA content in plants. The inoculation of Bacillus subtilis IB-22 stimulated the growth of both the mutant and its parent variety. Also, under the influence of bacteria, the ABA content in plants increased, and the increase was more significant in the mutant. This effect was accompanied by an increase in hydraulic conductivity in the roots of the ABA-deficient mutant, and immunolocalization using antibodies against PIP2;1 and PIP2;2 aquaporins revealed an increase in their abundance. Thus, the results obtained support the hypothesis about the importance of a sufficiently high ABA content in plants to maintain the abundance of aquaporins, hydraulic conductivity and the growth of barley plants. Full article

This literature review looks at Sjogren’s Syndrome (SS), a chronic autoimmune disorder affecting exocrine glands, particularly the lacrimal and salivary glands. SS manifests as ocular and oral dryness, with severe complications like visual dysfunction and corneal perforation, as well as systemic implications, such as interstitial lung disease and lymphoma. This review explores the use of tear film biomarkers to diagnose SS, emphasizing the significance of their identification in aiding clinical diagnosis and differentiation from other diseases. This study identified and analyzed 15 papers, encompassing 1142 patients and employing various tear sample collection methods. Tear biomarkers were categorized by function and explored in-depth. Categories include (1) antimicrobials, antivirals, and antifungals; (2) components of immune regulation; (3) components that regulate metabolic processes; and (4) inflammatory markers. Noteworthy findings include the potential diagnostic values of tear lysozyme, lactoferrin, dinucleoside polyphosphates, cathepsin, defensin, antibodies, epidermal fatty acid-binding protein, HLA-DR, ADAM10, aquaporin 5, and various miRNAs and mRNAs. Overall, our understanding of SS tear film composition is enhanced, providing valuable insights into the pathogenesis of SS and offering a foundation for future diagnostic and therapeutic advancements in autoimmune conditions affecting the ocular surface. Full article

Spermatozoon volume regulation is an essential determinant of male fertility competence in mammals and oviparous fishes. In mammals, aquaporin water channels (AQP3, -7 and -8) have been suggested to play a role in spermatozoon cell volume regulatory responses in the hypotonic female oviduct. In contrast, the ejaculated spermatozoa of marine teleosts, such as the gilthead seabream (Sparus aurata), experience a high hypertonic shock in seawater, initially resulting in an Aqp1aa-mediated water efflux, cell shrinkage and the activation of motility. Further regulatory recovery of cell volume in post-activated spermatozoa is mediated by Aqp4a in cooperation with the Trpv4 Ca²⁺ channel and other ion channels and transporters. Using a paralog-specific antibody, here, we show that seabream spermatozoa also express the aquaglyceroporin AQP3 ortholog Aqp3a, which is highly accumulated in the mid posterior region of the spermatozoon flagella, in a similar pattern to that described in mouse and human sperm. To investigate the role of Aqp3a in seabream sperm motility, we used a recently developed AQP3 antagonist (DFP00173), as well as the seabream Aqp3a-specific antibody (α-SaAqp3a), both of which specifically inhibit Aqp3a-mediated water conductance when the channel was heterologously expressed in Xenopus laevis oocytes. Inhibition with either DFP00173 or α-SaAqp3a did not affect sperm motility activation but did impair the spermatozoon motion kinetics at 30 s post activation in a dose-dependent manner. Interestingly, in close resemblance to the phenotypes of AQP3-deficient murine sperm, electron microscopy image analysis revealed that both Aqp3a inhibitors induce abnormal sperm tail morphologies, including swelling and angulation of the tail, with complete coiling of the flagella in some cases. These findings suggest a conserved role of Aqp3a as an osmosensor that regulates cell volume in fish spermatozoa under a high hypertonic stress, thereby controlling the efflux of water and/or solutes in the post-activated spermatozoon. Full article

Conventional rodent neuromyelitis optica spectrum disorder (NMOSD) models using patient-derived immunoglobulin G (IgG) are potentially affected by the differences between the human and rodent aquaporin-4 (AQP4) extracellular domains (ECDs). We hypothesized that the humanization of AQP4 ECDs would make the rodent model lesions closer to human NMOSD pathology. Humanized-AQP4-expressing (hAQP4) rats were generated using genome-editing technology, and the human AQP4-specific monoclonal antibody (mAb) or six patient-derived IgGs were introduced intraperitoneally into hAQP4 rats and wild-type Lewis (WT) rats after immunization with myelin basic protein and complete Freund’s adjuvant. Human AQP4-specific mAb induced astrocyte loss lesions specifically in hAQP4 rats. The patient-derived IgGs also induced NMOSD-like tissue-destructive lesions with AQP4 loss, demyelination, axonal swelling, complement deposition, and marked neutrophil and macrophage/microglia infiltration in hAQP4 rats; however, the difference in AQP4 loss lesion size and infiltrating cells was not significant between hAQP4 and WT rats. The patient-derived IgGs bound to both human and rat AQP4 M23, suggesting their binding to the shared region of human and rat AQP4 ECDs. Anti-AQP4 titers positively correlated with AQP4 loss lesion size and neutrophil and macrophage/microglia infiltration. Considering that patient-derived IgGs vary in binding sites and affinities and some of them may not bind to rodent AQP4, our hAQP4 rat is expected to reproduce NMOSD-like pathology more accurately than WT rats. Full article

Triple-negative breast cancer (TNBC) remains one of the most challenging subtypes since it is initially characterized by the absence of specific biomarkers and corresponding targeted therapies. Advances in methodology, translational informatics, genomics, and proteomics have significantly contributed to the identification of therapeutic targets. The development of innovative treatments, such as antibody–drug conjugates and immune checkpoint inhibitors, alongside chemotherapy, has now become the standard of care. However, the quest for biomarkers defining therapy outcomes is still ongoing. Peroxiporins, which comprise a subgroup of aquaporins, which are membrane pores facilitating the transport of water, glycerol, and hydrogen peroxide, have emerged as potential biomarkers for therapy response. Research on peroxiporins reveals their involvement beyond traditional channeling activities, which is also reflected in their cellular localization and roles in cellular signaling pathways. This research on peroxiporins provides fresh insights into the mechanisms of therapy resistance in tumors, offering potential avenues for predicting treatment outcomes and tailoring successful TNBC therapies. Full article

Objective: Neuromyelitis optica (NMO) and neuromyelitis optica spectrum disorder (NMOSD) are autoimmune-mediated central nervous system disorders distinguished by the presence of serum aquaporine-4 IgG antibody (AQP4-Ab). The clinical panel comprises severe optic neuritis (ON) and transverse myelitis, which can result in incomplete recovery and a high risk of recurrence. Methods: This study aimed to evaluate the visual outcomes of three patients with severe acute ON in NMOSD that was non-responsive to intravenous methylprednisolone (IVMP), who received plasma exchange therapy (PLEX). We included three patients (P1, P2 and P3) with severe acute ON who had no improvement after IVMP treatment and were admitted to the ophthalmology department at the Emergency University Hospital Bucharest from January 2022 to September 2023. All three patients with ON were diagnosed in accordance with the criteria described by the Optic Neuritis Treatment Trial. All the subjects were experiencing their first attack. Results: The mean recruitment age was 35.3 ± 7.71. All patients were seropositive for the AQP4 antibody. All patients were tested for serum myelin oligodendrocyte glycoprotein (MOG) antibody but only one showed a positive test (P3). Lesions visible in orbital MRI indicated the involvement of retrobulbar, canalicular and/or intracranial segments. All three subjects had no response or incomplete remission after an IVMP protocol (5 days of 1000 mg intravenous methylprednisolone in sodium chloride 0.9%). The mean time from onset of optic neuritis to PLEX was 37.6 days. The PLEX treatment protocol comprised five cycles of plasma exchange treatment over 10 days, with a plasma exchange session every other day. An amount of 1 to 1.5 volumes of circulating plasma were dialyzed for 2–4 h. At 1 month after the completion of PLEX therapy, BCVA and VF parameters were improved in all three patients. Conclusion: The treatment of ON remains subject to debate and is somewhat controversial. Plasma exchange must be considered as a rescue therapy when IVMP is insufficient for AQP4-ON patients. This study revealed that PLEX treatment effectively improves the visual outcomes of patients experiencing their first attack of severe acute isolated ON after high-dose IVMP treatment. This study suggests that PLEX may be associated with improved visual outcomes in NMOSD acute optic neuritis. Full article

Various vaccines have been developed in response to the SARS-CoV-2 pandemic, and the safety of vaccines has become an important issue. COVID-19 vaccine-related central nervous system inflammatory demyelinating diseases (CNS IDDs) have been reported recently. We present one case of AstraZeneca vaccine-related myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease and a literature review of another 78 patients published from January 2020 to October 2022. Patients were divided into three vaccine types (viral vector, mRNA, and inactivated vaccines) for further analyses. Among 79 patients with COVID-19 vaccine-related CNS IDDs, 49 (62%) cases received viral vector vaccines, 20 (25.3%) received mRNA vaccines, and 10 (12.7%) received inactivated vaccines. Twenty-seven cases (34.2%) were confirmed with autoantibodies, including fifteen patients (19%) with anti-MOG, eleven (13.9%) with anti-aquaporin 4 (AQP4), and one (1.3%) with both antibodies. Significantly, more males developed CNS IDDs post viral vector vaccines compared to mRNA and inactivated vaccines. Patients receiving mRNA vaccines were older than those receiving other types. Furthermore, mRNA and inactivated vaccines correlated more with anti-AQP4 antibodies, while viral vector vaccines showed higher MOG positivity. This research suggests potential associations between COVID-19 vaccine-related CNS IDDs and gender, age, and autoantibodies, contingent on vaccine types. Protein sequence analysis implies similarities between the S protein and AQP4/MOG. Further studies may elucidate the mechanisms of CNS IDDs, aiding vaccine selection for specific types. Full article

Optic neuritis (ON) is the most common cause of vision loss in young adults. It manifests as acute or subacute vision loss, often accompanied by retrobulbar discomfort or pain during eye movements. Typical ON is associated with Multiple Sclerosis (MS) and is generally mild and steroid-responsive. Atypical forms are characterized by unusual features, such as prominent optic disc edema, poor treatment response, and bilateral involvement, and they are often associated with autoantibodies against aquaporin-4 (AQP4) or Myelin Oligodendrocyte Glycoprotein (MOG). However, in some cases, AQP4 and MOG antibodies will return as negative, plunging the clinician into a diagnostic conundrum. AQP4- and MOG-seronegative ON warrants a broad differential diagnosis, including autoantibody-associated, granulomatous, and systemic disorders. These rare forms need to be identified promptly, as their management and prognosis are greatly different. The aim of this review is to describe the possible rarer etiologies of non-MS-related and AQP4- and MOG-IgG-seronegative inflammatory ON and discuss their diagnoses and treatments. Full article