Dormancy regulator Prunus mume DAM6 promotes ethylene-mediated leaf senescence and abscission.

Leaf senescence and abscission in autumn are critical phenological events in deciduous woody perennials. After leaf fall, dormant buds remain on deciduous woody perennials, which then enter a winter dormancy phase. Thus, leaf fall is widely believed to be linked to the onset of dormancy. In Rosaceae fruit trees, DORMANCY-ASSOCIATED MADS-box (DAM) transcription factors control bud dormancy. However, apart from their regulatory effects on bud dormancy, the biological functions of DAMs have not been thoroughly characterized. In this study, we revealed a novel DAM function influencing leaf senescence and abscission in autumn. In Prunus mume, PmDAM6 expression was gradually up-regulated in leaves during autumn toward leaf fall. Our comparative transcriptome analysis using two RNA-seq datasets for the leaves of transgenic plants overexpressing PmDAM6 and peach (Prunus persica) DAM6 (PpeDAM6) indicated Prunus DAM6 may up-regulate the expression of genes involved in ethylene biosynthesis and signaling as well as leaf abscission. Significant increases in 1-aminocyclopropane-1-carboxylate accumulation and ethylene emission in DEX-treated 35S:PmDAM6-GR leaves reflect the inductive effect of PmDAM6 on ethylene biosynthesis. Additionally, ethephon treatments promoted autumn leaf senescence and abscission in apple and P. mume, mirroring the changes due to PmDAM6 overexpression. Collectively, these findings suggest that PmDAM6 may induce ethylene emission from leaves, thereby promoting leaf senescence and abscission. This study clarified the effects of Prunus DAM6 on autumn leaf fall, which is associated with bud dormancy onset. Accordingly, in Rosaceae, DAMs may play multiple important roles affecting whole plant growth during the tree dormancy induction phase.

Evolutionary analysis of tonoplast intrinsic proteins (TIPs) unraveling the role of TIP3s in plant seed development.

Tonoplast intrinsic proteins (TIPs) are crucial in facilitating the transportation of water and various small solutes across biological membranes. The evolutionary path and functional roles of TIPs is poorly understood in plants. In the present study, a total of 976 TIPs were identified in 104 diverse species and subsequently studied to trace their lineage-specific evolutionary path and tissue-specific function. Interestingly, TIPs were found to be absent in lower forms such as algae and fungi and they evolved later in primitive plants like bryophytes. Bryophytes possess a distant class of TIPs, denoted as TIP6, which is not found in higher plants. The aromatic/arginine (ar/R) selectivity filter found in TIP6 of certain liverworts share similarity with hybrid intrinsic protein (HIP), suggesting an evolutionary kinship. As plants evolved to more advanced forms, TIPs diversified into five different sub-groups (TIP1 to TIP5). Notably, TIP5 is a sub-group unique to angiosperms. The evolutionary history of the TIP subfamily reveals an interesting observation that the TIP3 subgroup has evolved within seed-bearing Spermatophyta. Further, TIPs exhibit tissue-specific expression that is conserved within various plant species. Specifically, the TIP3s were found to be exclusively expressed in seeds. Quantitative PCR analysis of TIP3s showed gradually increasing expression in soybean seed developmental stages. The expression of TIP3s in different plant species was also found to be gradually increasing during seed maturation. The results presented here address the knowledge gap concerning the evolutionary background of TIPs, specifically TIP3 in plants, and provide valuable insights for a deeper comprehension of the functions of TIPs in plants.

Aquaporins in the Cornea.

The cornea is an avascular, transparent tissue that allows light to enter the visual system. Accurate vision requires proper maintenance of the cornea's integrity and structure. Due to its exposure to the external environment, the cornea is prone to injury and must undergo proper wound healing to restore vision. Aquaporins (AQPs) are a family of water channels important for passive water transport and, in some family members, the transport of other small molecules; AQPs are expressed in all layers of the cornea. Although their functions as water channels are well established, the direct function of AQPs in the cornea is still being determined and is the focus of this review. AQPs, primarily AQP1, AQP3, and AQP5, have been found to play an important role in maintaining water homeostasis, the corneal structure in relation to proper hydration, and stress responses, as well as wound healing in all layers of the cornea. Due to their many functions in the cornea, the identification of drug targets that modulate the expression of AQPs in the cornea could be beneficial to promote corneal wound healing and restore proper function of this tissue crucial for vision.

Regional variances depict a unique glial-specific inflammatory response following closed-head injury.

Mild traumatic brain injuries (mTBI) constitute a significant health concern with clinical symptoms ranging from headaches to cognitive deficits. Despite the myriad of symptoms commonly reported following this injury, there is still a lack of knowledge on the various pathophysiological changes that occur. Preclinical studies are at the forefront of discovery delineating the changes that occur within this heterogeneous injury, with the emergence of translational models such as closed-head impact models allowing for further exploration of this injury mechanism. In the current study, male rats were subjected to a closed-head controlled cortical impact (cCCI), producing a concussion (mTBI). The pathological effects of this injury were then evaluated using immunoflourescence seven days following. The results exhibited a unique glial-specific inflammatory response, with both the ipsilateral and contralateral sides of the cortex and hippocampus showing pathological changes following impact. Overall these findings are consistent with glial changes reported following concussions and may contribute to subsequent symptoms.

A high-throughput yeast approach to characterize aquaporin permeabilities: Profiling the Arabidopsis PIP aquaporin sub-family.

Introduction: Engineering membrane transporters to achieve desired functionality is reliant on availability of experimental data informing structure-function relationships and intelligent design. Plant aquaporin (AQP) isoforms are capable of transporting diverse substrates such as signaling molecules, nutrients, metalloids, and gases, as well as water. AQPs can act as multifunctional channels and their transport function is reliant on many factors, with few studies having assessed transport function of specific isoforms for multiple substrates. Methods: High-throughput yeast assays were developed to screen for transport function of plant AQPs, providing a platform for fast data generation and cataloguing of substrate transport profiles. We applied our high-throughput growth-based yeast assays to screen all 13 Arabidopsis PIPs (AtPIPs) for transport of water and several neutral solutes: hydrogen peroxide (H2O2), boric acid (BA), and urea. Sodium (Na+) transport was assessed using elemental analysis techniques. Results: All AtPIPs facilitated water and H2O2 transport, although their growth phenotypes varied, and none were candidates for urea transport. For BA and Na+ transport, AtPIP2;2 and AtPIP2;7 were the top candidates, with yeast expressing these isoforms having the most pronounced toxicity response to BA exposure and accumulating the highest amounts of Na+. Linking putative AtPIP isoform substrate transport profiles with phylogenetics and gene expression data, enabled us to align possible substrate preferences with known and hypothesized biological roles of AtPIPs. Discussion: This testing framework enables efficient cataloguing of putative transport functionality of diverse AQPs at a scale that can help accelerate our understanding of AQP biology through big data approaches (e.g. association studies). The principles of the individual assays could be further adapted to test additional substrates. Data generated from this framework could inform future testing of AQP physiological roles, and address knowledge gaps in structure-function relationships to improve engineering efforts.

Black odorous water concentrating by forward osmosis: rejection performance of characteristic pollutants based on cation exchange.

This study aimed to investigate pollutant concentration and nitrogen interception characteristics of a forward osmosis (FO) process for concentrating black odorous water. The membrane cell was operated in active layer facing feed solution (AL-FS) mode with aquaporin (AQP) as the membrane material and NaCl solution as the draw solution (DS). The organic pollutants (COD), TP, NH+4-N, NO-3-N, TN, Fe and Mn in black odorous water were concentrated non-intermittently for 24 h, and their interception characteristics were investigated. The results showed that the average interception rates of COD, TP, NO- 3-N, TN, Fe and Mn were 97.2%, 98.0%, 58.7%, 54.3%, 61.8% and 60.0%, respectively, while the average interception rate of NH+4-N was only 1.27%-3.47%. To explore the characteristics of nitrogen interception, a comparison was conducted between AQP membrane and thin film composite (TFC) membrane. Because the surface electronegativity of AQP membrane was stronger than that of TFC, the effect of cation exchange on ammonia nitrogen interception was more serious with AQP membrane. With NaCl solution as DS, the reverse osmosis flux of Na+ was (0.53 ± 0.02 mol·m-2·h-1), which was significantly higher than that of Cl- (0.29 ± 0.03 mol·m-2·h-1) (P < 0.05). The interception effect of AQP membrane on TN was related to the proportion of NH+4-N in TN. The pretreatment of black odorous water by aeration could transform part of NH+4-N into NO-3-N, and reduce the negative effect of cation exchange effect on nitrogen interception. The TN interception rate increased from 54.3% to 66.1%.

Analysis on Changes of Aquaporin and Intestinal Flora in a Rat Model with Spleen-Yin Deficiency Syndrome / 中国实验方剂学杂志

ObjectiveTo investigate the effects of spleen-Yin deficiency on gastrointestinal absorption， water metabolism and intestinal flora in rats with spleen-Yin deficiency syndrome. MethodA rat model of spleen-Yin deficiency syndrome was established by using the composite factors， including irregular meat and vegetable diet， weight-bearing fatigue swimming and gavage with warm-heat injury-Yin drugs. The changes of body weight， food intake， water intake and duration of swimming in the blank and model groups were observed. Hematoxylin-eosin（HE） staining was used to observe the histopathological damage of the stomach and colon. Urinary excretion rate of D-xylose was determined by phloroglucinol method. The content of gastrin（GAS） in serum was determined by enzyme-linked immunosorbent assay（ELISA）. The relative expression levels of vasoactive intestinal peptide（VIP）， aquaporin 3（AQP3） and AQP4 in gastric tissues were detected by Western blot. The relative mRNA expression levels of VIP， AQP3 and AQP4 in gastric tissues were detected by Real-time fluorescence quantitative polymerase chain reaction（Real-time PCR）， and the changes of intestinal flora were analyzed by 16S rDNA sequencing. ResultCompared with the blank group， the results of general physical signs showed that the body weight and food intake of rats in the model group were significantly decreased， the water intake was significantly increased（P<0.05， P<0.01）， and the duration of swimming was significantly decreased（P<0.01）. Pathological examination results showed that in the mucosa of gastric tissues of rats in the model group appeared to be misaligned， the mucosa of colonic tissues could be seen to be obviously thinned or mutilated， and the epithelial cells appeared to be necrotic or even exfoliated. Compared with the blank group， the urinary D-xylose excretion rate of rats in the model group was significantly decreased（P<0.01）， and the serum GAS content was significantly decreased（P<0.05）. Compared with the blank group， Western blot results showed that the relative expression level of VIP protein in gastric tissues of rats in the model group was significantly decreased， while the relative expression levels of AQP4 and AQP3 proteins were significantly increased（P<0.01）. Compared with the blank group， Real-time PCR results showed that the relative expression level of VIP mRNA in gastric tissues of rats in the model group was significantly decreased（P<0.01）， and the relative mRNA expression levels of AQP3 and AQP4 were significantly increased（P<0.05， P<0.01）. Compared with the blank group， the results of intestinal flora analysis showed that the number of operational taxonomic units（OTUs） and α-diversity increased and β-diversity decreased significantly in the model group， the abundance of Porphyromonadaceae was increased significantly， and the abundance of Oscillibacter_ruminantium was decreased significantly（P<0.05）. Spearman correlation analysis showed that Porphyromonadaceae was significantly positively correlated with AQP4 protein level， while Oscillibacter_ruminantium was significantly positively correlated with VIP protein level， and negatively correlated with AQP3 and AQP4 protein levels（P<0.05）. Linear discriminant analysis effect size（LEfSe） analysis results showed that there were significant differences in a variety of intestinal bacteria between groups， and the intestinal bacteria of the model group were significantly enriched in the phylum/order/family/genus of Elusimicrobia， Betaproteobacteria， Burkholderiales， Sutterellaceae and Parasutterella（P<0.05）. ConclusionSpleen-Yin deficiency syndrome can weaken the digestion and absorption capacity of gastrointestinal tract， and cause the disturbance of water metabolism and intestinal flora. AQP4， AQP3 and VIP protein levels of gastric mucosa are closely related to Porphyromonadaceae and Oscillibacter_ruminantium. And AQP4， AQP3 and VIP may be involved in the regulation of intestinal flora in order to affect the physiological function of spleen governing transportation and transformation.

Aconiti Lateralis Radix Praeparata-Cinnamomi Cortex Combination Alleviates Slow Transit Constipation due to Yang Deficiency in Rats via Regulating VIP/cAMP/PKA/AQP Pathway in Colon / 中国实验方剂学杂志

ObjectiveTo investigate the effect and mechanism of Aconiti Lateralis Radix Praeparata-Cinnamomi Cortex in regulating the intestinal function in the rat model of slow transit constipation （STC） due to yang deficiency via the vasoactive intestinal peptide （VIP）/cathelicidin antimicrobial peptide （cAMP）/protein kinase A （PKA）/aquaporin （AQP） pathway. MethodSD rats were randomized into 6 groups （n=6）， including a control group， a model group， high-， medium-， and low-dose Aconiti Lateralis Radix Praeparata-Cinnamomi Cortex groups， and a prucalopride group. Other groups except the control group were treated with loperamide hydrochloride combined with ice water by gavage for the modeling of STC due to yang deficiency. The number of fecal pellets， time to the first black stool defecation， fecal water content， intestinal propulsion rate， and score of fecal properties were recorded in each group. At the end of the treatment， the colon was stained with hematoxylin-eosin （HE） to reveal the histopathological changes and Alcian blue/periodic acid-Schiff （AB-PAS） to reveal the secretion of colonic mucus. The enzyme-linked immunosorbent assay （ELISA） was employed to measure the level of VIP in the serum. The mRNA level of AQP in the colon was measured by polymerase chain reaction （Real-time PCR）. Immunohistochemical staining was performed to observe the expression of AQPs in the colon and kidney tissues. Western blot was performed to determine the protein levels of cAMP， PKA， and VIP in the colon tissue. ResultCompared with the control group, the model group had longer time to the first black stool defecation, reduced fecal pellets and water content, reduced Bristol Stool Form Scale score and intestinal propulsion rate, and constipation aggravated（P<0.01）. Moreover, increased the intestinal lesions, reduced the mucus secretion, reduce the serum VIP level, up-regulated the expression levels of AQP1 in the colon and kidney tissues, inhibited the expression of AQP3 and AQP9（P<0.01）., and down-regulated the protein levels of cAMP, PKA, and VIP in the colon tissue. Compared with the model group， the high-dose Aconiti Lateralis Radix Praeparata-Cinnamomi Cortex group had shortened time to the first black stool defecation， increased fecal pellets and water content， increased Bristol Stool Form Scale score and intestinal propulsion rate， and alleviated constipation symptoms. Moreover， high-dose Aconiti Lateralis Radix Praeparata-Cinnamomi Cortex reduced the intestinal lesions， increased the mucus secretion， elevated the serum VIP level（P<0.01）.， down-regulated the expression levels of AQP1 in the colon and kidney tissues， promoted the expression of AQP3 and AQP9（P<0.05，P<0.01）， and up-regulated the protein levels of cAMP， PKA， and VIP in the colon tissue. The medium- and low-dose groups had weaker effect than the high-dose group（P<0.01）. ConclusionHigh-dose Aconiti Lateralis Radix Praeparata-Cinnamomi Cortex can improve the intestinal motility and balance the intestinal water and fluid metabolism by up-regulating the VIP/cAMP/PKA/AQP pathway， thereby mitigating the constipation symptoms in the rat model of slow transit constipation due to yang deficiency.

Role of Aquaporins in Heart Failure from Theory of Cardiac and Renal Coordination / 中国实验方剂学杂志

Heart failure refers to a group of clinical syndromes caused by structural or functional abnormalities of the heart that lead to impaired ejection or filling of the ventricles. The traditional Chinese medicine （TCM） theory of cardiac and renal coordination holds that the kidney governs water and plays a key role in maintaining the balance of fluid metabolism. Therefore， the treatment of water retention in heart failure can start from the heart and kidney. The basic pathogenesis of heart failure is kidney deficiency， blood stasis， and water stagnation， and the therapies including dredging the heart and kidneys， warming yang and excreting water， tonifying kidneys and activating blood， and dredging meridians and collaterals. Aquaporins （AQPs）， the key molecular basis of water metabolism， are involved in the pathogenesis of water retention in heart failure together with the arginine vasopressin system （AVP）， renin-angiotensin-aldosterone system （RAAS）， and diuretic resistance. Studies have shown that herbal medicines that regulate the heart and kidney can alleviate water retention in heart failure by targeting AQPs， thereby delaying or even reversing the progression of heart failure. This paper expounds the TCM name and pathogenesis of heart failure from the theory of cardiac and renal coordination， the role of AQPs in the pathogenesis of water retention in heart failure， and the modern connotation of the therapy of tonifying heart and kidney for heart failure， aiming to provide ideas for the prevention and treatment of water retention in heart failure by TCM.

RG100204, A Novel Aquaporin-9 Inhibitor, Reduces Septic Cardiomyopathy and Multiple Organ Failure in Murine Sepsis.

Sepsis is caused by systemic infection and is a major health concern as it is the primary cause of death from infection. It is the leading cause of mortality worldwide and there are no specific effective treatments for sepsis. Gene deletion of the neutral solute channel Aquaporin 9 (AQP9) normalizes oxidative stress and improves survival in a bacterial endotoxin induced mouse model of sepsis. In this study we described the initial characterization and effects of a novel small molecule AQP9 inhibitor, RG100204, in a cecal ligation and puncture (CLP) induced model of polymicrobial infection. In vitro, RG100204 blocked mouse AQP9 H2O2 permeability in an ectopic CHO cell expression system and abolished the LPS induced increase in superoxide anion and nitric oxide in FaO hepatoma cells. Pre-treatment of CLP-mice with RG100204 (25 mg/kg p.o. before CLP and then again at 8 h after CLP) attenuated the hypothermia, cardiac dysfunction (systolic and diastolic), renal dysfunction and hepatocellular injury caused by CLP-induced sepsis. Post-treatment of CLP-mice with RG100204 also attenuated the cardiac dysfunction (systolic and diastolic), the renal dysfunction caused by CLP-induced sepsis, but did not significantly reduce the liver injury or hypothermia. The most striking finding was that oral administration of RG100204 as late as 3 h after the onset of polymicrobial sepsis attenuated the cardiac and renal dysfunction caused by severe sepsis. Immunoblot quantification demonstrated that RG100204 reduced activation of the NLRP3 inflammasome pathway. Moreover, myeloperoxidase activity in RG100204 treated lung tissue was reduced. Together these results indicate that AQP9 may be a novel drug target in polymicrobial sepsis.

Seawater immersion exacerbates the pathological changes caused by incisive corneal injury in rabbit eyes.

Background: Seawater immersion complicates injuries suffered during maritime conflicts and eye injury is one of most common injuries on the battlefield. This study aimed to delineate the pathophysiological changes in the cornea after corneal injury combined with seawater immersion. Methods: The left eye of New Zealand White rabbits was injured with firecracker and a 3-mm long whole-layer incision in the center of the cornea parallel to the corneal limbus, followed by seawater immersion. The right eye was used as a control. The histology of the cornea and the inflammatory cytokine/chemokine levels in the aqueous humor were examined on days 1 and 7 after injury. The protein levels of aquaporin 1, 3, and 5 were assessed by immunohistochemical staining 7 days after injury. The expression and activation of nuclear factor κB (NF-κB) were examined by Western blot analysis. Results: Seawater immersion exacerbated penetrating explosive injury caused progressive tissue damage of the cornea and ocular inflammation, with drastic increases in the expression of cytokines/chemokines in the aqueous humor, which was mediated by the upregulation and activation of NF-κB. Furthermore, corneal protein levels of aquaporin 1, 3, and 5 were significantly increased after incisive injury and seawater immersion. Conclusions: These data demonstrated that the combination of incisive injury and seawater immersion is a dangerous situation and effective care strategies should be developed for the management of such maritime injuries.

Genome-Wide Identification and Expression Analyses of the Aquaporin Gene Family in Passion Fruit (Passiflora edulis), Revealing PeTIP3-2 to Be Involved in Drought Stress.

Aquaporins (AQPs) in plants can transport water and small molecules, and they play an important role in plant development and abiotic stress response. However, to date, a comprehensive study on AQP family members is lacking. In this study, 27 AQP genes were identified from the passion fruit genome and classified into four groups (NIP, PIP, TIP, SIP) on the basis of their phylogenetic relationships. The prediction of protein interactions indicated that the AQPs of passion fruit were mainly associated with AQP family members and boron protein family genes. Promoter cis-acting elements showed that most PeAQPs contain light response elements, hormone response elements, and abiotic stress response elements. According to collinear analysis, passion fruit is more closely related to Arabidopsis than rice. Furthermore, three different fruit ripening stages and different tissues were analyzed on the basis of the transcriptome sequencing results for passion fruit AQPs under drought, high-salt, cold and high-temperature stress, and the results were confirmed by qRT-PCR. The results showed that the PeAQPs were able to respond to different abiotic stresses, and some members could be induced by and expressed in response to multiple abiotic stresses at the same time. Among the three different fruit ripening stages, 15 AQPs had the highest expression levels in the first stage. AQPs are expressed in all tissues of the passion fruit. One of the passion fruit aquaporin genes, PeTIP3-2, which was induced by drought stress, was selected and transformed into Arabidopsis. The survival rate of transgenic plants under drought stress treatment is higher than that of wild-type plants. The results indicated that PeTIP3-2 was able to improve the drought resistance of plants. Our discovery lays the foundation for the functional study of AQPs in passion fruit.

Signaling Mechanisms and Pharmacological Modulators Governing Diverse Aquaporin Functions in Human Health and Disease.

The aquaporins (AQPs) are a family of small integral membrane proteins that facilitate the bidirectional transport of water across biological membranes in response to osmotic pressure gradients as well as enable the transmembrane diffusion of small neutral solutes (such as urea, glycerol, and hydrogen peroxide) and ions. AQPs are expressed throughout the human body. Here, we review their key roles in fluid homeostasis, glandular secretions, signal transduction and sensation, barrier function, immunity and inflammation, cell migration, and angiogenesis. Evidence from a wide variety of studies now supports a view of the functions of AQPs being much more complex than simply mediating the passive flow of water across biological membranes. The discovery and development of small-molecule AQP inhibitors for research use and therapeutic development will lead to new insights into the basic biology of and novel treatments for the wide range of AQP-associated disorders.

Genome-Wide Characterization of Aquaporins (aqps) in Lateolabrax maculatus: Evolution and Expression Patterns During Freshwater Acclimation.

Aquaporin (aqp) proteins are a group of small integral membrane proteins that play crucial roles as pore channels for the transport of water and other small solutes across the cell membrane. In our study, we identified 17 aqp genes from the spotted sea bass (Lateolabrax maculatus) genomic database. Gene organization, motif distribution, and selection pressure analyses were performed to investigate their evolutionary characteristics. The aqp mRNA displayed tissue-specific expression pattern in ten selected tissues of healthy spotted sea bass. To investigate the potential involvement of spotted sea bass aqps in osmoregulation, the expression profiles of aqp genes in gills were examined during freshwater (FW) acclimation using qRT-PCR. The mRNA level of aqp3a was dramatically induced during 1-3 day of the FW transition period (77-fold and 15-fold upregulated on 1 day and 3 day than in the control group), indicating that aqp3a may play an important hypo-osmoregulatory role in spotted sea bass. In addition, the expression levels of aqp1aa, aqp1ab, aqp3b, aqp7, and aqp9b increased to various degrees at 1 day after transferring to FW, suggesting their potential involvement in the FW acclimation process. Our study provides a valuable foundation for future studies aimed at uncovering the specific roles of aqp genes during salinity acclimation in spotted sea bass and other teleost species.

Autoantibodies Against the Complement Regulator Factor H in the Serum of Patients With Neuromyelitis Optica Spectrum Disorder.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system (CNS), characterized by pathogenic, complement-activating autoantibodies against the main water channel in the CNS, aquaporin 4 (AQP4). NMOSD is frequently associated with additional autoantibodies and antibody-mediated diseases. Because the alternative pathway amplifies complement activation, our aim was to evaluate the presence of autoantibodies against the alternative pathway C3 convertase, its components C3b and factor B, and the complement regulator factor H (FH) in NMOSD. Four out of 45 AQP4-seropositive NMOSD patients (~9%) had FH autoantibodies in serum and none had antibodies to C3b, factor B and C3bBb. The FH autoantibody titers were low in three and high in one of the patients, and the avidity indexes were low. FH-IgG complexes were detected in the purified IgG fractions by Western blot. The autoantibodies bound to FH domains 19-20, and also recognized the homologous FH-related protein 1 (FHR-1), similar to FH autoantibodies associated with atypical hemolytic uremic syndrome (aHUS). However, in contrast to the majority of autoantibody-positive aHUS patients, these four NMOSD patients did not lack FHR-1. Analysis of autoantibody binding to FH19-20 mutants and linear synthetic peptides of the C-terminal FH and FHR-1 domains, as well as reduced FH, revealed differences in the exact binding sites of the autoantibodies. Importantly, all four autoantibodies inhibited C3b binding to FH. In conclusion, our results demonstrate that FH autoantibodies are not uncommon in NMOSD and suggest that generation of antibodies against complement regulating factors among other autoantibodies may contribute to the complement-mediated damage in NMOSD.

Human Cord Blood Derived Unrestricted Somatic Stem Cells Restore Aquaporin Channel Expression, Reduce Inflammation and Inhibit the Development of Hydrocephalus After Experimentally Induced Perinatal Intraventricular Hemorrhage.

Intraventricular hemorrhage (IVH) is a severe complication of preterm birth associated with cerebral palsy, intellectual disability, and commonly, accumulation of cerebrospinal fluid (CSF). Histologically, IVH leads to subependymal gliosis, fibrosis, and disruption of the ependymal wall. Importantly, expression of aquaporin channels 1 and 4 (AQP1 and AQP4) regulating respectively, secretion and absorption of cerebrospinal fluids is altered with IVH and are associated with development of post hemorrhagic hydrocephalus. Human cord blood derived unrestricted somatic stem cells (USSCs), which we previously demonstrated to reduce the magnitude of hydrocephalus, as having anti-inflammatory, and beneficial behavioral effects, were injected into the cerebral ventricles of rabbit pups 18 h after glycerol-induced IVH. USSC treated IVH pups showed a reduction in ventricular size when compared to control pups at 7 and 14 days (both, P < 0.05). Histologically, USSC treatment reduced cellular infiltration and ependymal wall disruption. In the region of the choroid plexus, immuno-reactivity for AQP1 and ependymal wall AQP4 expression were suppressed after IVH but were restored following USSC administration. Effects were confirmed by analysis of mRNA from dissected choroid plexus and ependymal tissue. Transforming growth factor beta (TGF-ß) isoforms, connective tissue growth factor (CTGF) and matrix metalloprotease-9 (MMP-9) mRNA, as well as protein levels, were significantly increased following IVH and restored towards normal with USSC treatment (P < 0.05). The anti-inflammatory cytokine Interleukin-10 (IL-10) mRNA was reduced in IVH, but significantly recovered after USSC injection (P < 0.05). In conclusion, USSCs exerted anti-inflammatory effects by suppressing both TGF-ß specific isoforms, CTGF and MMP-9, recovered IL-10, restored aquaporins expression towards baseline, and reduced hydrocephalus. These results support the possibility of the use of USSCs to reduce IVH consequences in prematurity.

Corrigendum: Perivascular Unit: This Must Be the Place. The Anatomical Crossroad Between the Immune, Vascular and Nervous System.

[This corrects the article DOI: 10.3389/fnana.2020.00017.].

Modern trends in diuretics development.

Diuretics are the first-line therapy for widespread cardiovascular and non-cardiovascular diseases. Traditional diuretics are commonly prescribed for treatment in patients with hypertension, edema and heart failure, as well as with a number of kidney problems. They are diseases with high mortality, and the number of patients suffering from heart and kidney diseases is increasing year by year. The use of several classes of diuretics currently available for clinical use exhibits an overall favorable risk/benefit balance. However, they are not devoid of side effects. Hence, pharmaceutical researchers have been making efforts to develop new drugs with a better pharmacological profile. High-throughput screening, progress in protein structure analysis and modern methods of chemical modification have opened good possibilities for identification of new promising agents for preclinical and clinical testing. In this review, we provide an overview of the medicinal chemistry approaches toward the development of small molecule compounds showing diuretic activity that have been discovered over the past decade and are interesting drug candidates. We have discussed promising natriuretics/aquaretics/osmotic diuretics from such classes as: vasopressin receptor antagonists, SGLT2 inhibitors, urea transporters inhibitors, aquaporin antagonists, adenosine receptor antagonists, natriuretic peptide receptor agonists, ROMK inhibitors, WNK-SPAK inhibitors, and pendrin inhibitors.

Caveolin-1 Regulates Perivascular Aquaporin-4 Expression After Cerebral Ischemia.

Edema is a hallmark of many brain disorders including stroke. During vasogenic edema, blood-brain barrier (BBB) permeability increases, contributing to the entry of plasma proteins followed by water. Caveolae and caveolin-1 (Cav-1) are involved in these BBB permeability changes. The expression of the aquaporin-4 (AQP4) water channel relates to brain swelling, however, its regulation is poorly understood. Here we tested whether Cav-1 regulates AQP4 expression in the perivascular region after brain ischemia in mice. We showed that Cav-1 knockout mice had enhanced hemispheric swelling and decreased perivascular AQP4 expression in perilesional and contralateral cortical regions compared to wild-type. Glial fibrillary acidic protein-positive astrocytes displayed less branching and ramification in Cav-1 knockout mice compared to wild-type animals. There was a positive correlation between the area of perivascular AQP4-immunolabelling and branch length of Glial fibrillary acidic protein-positive astrocytes in wild-type mice, not seen in Cav-1 knockout mice. In summary, we show for the first time that loss of Cav-1 results in decreased AQP4 expression and impaired perivascular AQP4 covering after cerebral ischemia associated with altered reactive astrocyte morphology and enhanced brain swelling. Therapeutic approaches targeting Cav-1 may provide new opportunities for improving stroke outcome. SIGNIFICANCE STATEMENT: Severe brain edema worsens outcome in stroke patients. Available treatments for stroke-related edema are not efficient and molecular and cellular mechanisms are poorly understood. Cellular water channels, aquaporins (AQPs), are mainly expressed in astrocytes in the brain and play a key role in water movements and cerebral edema, while endothelial caveolins have been suggested to play a role in vasogenic edema. Here we used an integrative approach to study possible interaction between AQP4 and caveolin-1 (Cav-1) after stroke. Absence of Cav-1 was associated with perivascular changes in AQP4 expression and enhanced brain swelling at 3 days after cerebral ischemia. The present work indicates a direct or indirect effect of Cav-1 on perivascular AQP4, which may lead to novel edema therapy.

Mirror-Image Lesions in Sequential Relapses of AQP4-Positive Neuromyelitis Optica Spectrum Disorder.

A 25 year-old Nigerian woman with aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (NMOSD) presented with a 6 week history of nausea, vomiting, and refractory hiccups; as well as progressive lower extremity sensory loss, weakness, saddle anesthesia, and urinary incontinence. She had experienced her first NMOSD relapse seven years prior with bilateral lower extremity weakness and area postrema syndrome. After pulse steroids and plasma exchange she made a complete neurologic recovery and was started on azathioprine. An initial aquaporin-4 (AQP4) antibody ELISA test was positive, but three subsequent tests were negative and repeat MRI brain showed resolution of T2/FLAIR signal abnormalities with the exception of a right thalamic lesion and a left medullary lesion. Azathioprine was discontinued after 1 year and she was lost to follow-up. With her second relapse, she had new lesions in her left thalamus and right medulla-a mirror image of the thalamic and medullary lesions associated with her first relapse. In addition, an MRI spine demonstrated a new longitudinally extensive transverse myelitis from T7 to L1 with edematous expansion of the cord. Her serum AQP4 antibody test using a cell-based assay was strongly positive. NMOSD lesions are typically associated with brain regions with high density of the AQP4 channel. These areas include optic nerves, hypothalamus, and the diencephalic and brainstem tissues that surround the cerebral aqueduct and third and fourth ventricles. Previous studies have demonstrated that those with relapsing NMOSD have a predilection for recurrence in the same neuroanatomical region as their first episode. We hypothesize, using data from prior pathologic and epidemiologic studies, that mirror image lesions, where the same anatomic sites are affected on the contralateral side of the brain or spinal cord, may appear in subsequent attacks due to (i) areas of high remaining AQP4 density and/or (ii) local compromise of astrocyte or blood-brain barrier (BBB) function that persists after the initial inciting attack.