Albumin Permeability Research Articles

Mussel-inspired graphene oxide-based mixed matrix membranes for improving permeability and antifouling property

A multi-functional bio-inspired graphene oxide (GO) nanosheet was prepared firstly by successively modifying GO nanosheets with polydopamine (GO-PDA) and lysine (GO-PDA-LYS). Subsequently, the modified GO-blended polyvinylidene fluoride (PVDF) (PVDF/(GO-PDA-LYS)) MMMs were fabricated via non-solvent induced phase separation (NIPS) method. The presence of biomimetic GO-based nanosheets with good compatibility further improves the hydrophilicity of MMMs and endows them with favorable antifouling and antibacterial properties. The resultant MMMs show a competitive rejection rate (95.2%) of bovine serum albumin (BSA) and high pure water permeability of 850 L m-2h−1 bar−1, which is 7 times higher than that of the original PVDF membrane, as well as a high flux recovery ratio of over 80%. Moreover, the results of the Raman spectroscopy demonstrate that GO-PDA-LYS nanosheets are more evenly dispersed on the membrane surface than GO or GO-PDA nanosheets due to their better compatibility, thereby further improving antifouling and antibacterial performance of MMMs. This multi-functional biomimetic GO-PDA-LYS nanosheet provides new insights into an effective strategy for synchronously enhancing the water permeability, antifouling and antibacterial performance of MMMs.

Flat ultrafiltration PAN/BNE membranes with temperature-responsive performance obtained by modification with “smart” PVA copolymer

The ultrafiltration (UF) composite polyacrylonitrile (PAN)/ butadiene–acrylonitrile elastomer (BNE) membrane obtained by the phase inversion method was modified with temperature sensitivity by physicochemical immobilization of hydrophobically modified poly(vinyl alcohol) (HMPVA). HMPVA was prepared by partial acetalization of poly(vinyl alcohol) (PVA) with a molar mass of 75000 g/mol, resulting in a temperature-sensitive copolymer with a phase transition temperature (Ttr) of 40.2oC. Modification of the membranes was performed by introducing aqueous HMPVA solutions of different concentrations into the membrane structure, followed by its immobilization by cross-linking with glutaraldehyde. The composition, technological and structural characteristics of the membranes before and after the modification were investigated. Scanning electron microscopy (SEM) and barodynamic determinations were used in the typical UF operating pressure range (0–0.5 MPa), evaluating permeability (J, l/m2.h) and rejection (R, %) of water and albumin as a calibrant (molecular mass ~76 kDa). Temperature-sensitive HMPVA in the membrane structure optimizes the energy and material efficiency of the membrane process, including membrane service life and maintenance.

Dexmedetomidine alleviates high glucose-induced podocyte damage by inhibiting EDA2R

Purpose: To investigate the effect and mechanism of action of dexmedetomidine (Dex) on podocyte injury.
 Methods: Cells were incubated with high glucose (50 mM) to induce a podocyte injury model in vitro. Cell viability, apoptosis, the expression of related protein related in podocyte injury and albumin permeability were evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT), flow cytometry, western blot and Transwell assays.
 Results: Dex administration enhanced HG-induced cell viability and the relative protein expression of Bcl-2, but reduced the HG-induced relative protein level of Bax and apoptosisrate in podocytes (p < 0.05). Besides, Dex incubation compensated HG-induced relative protein expressions of nephrin and podocin in podocytes but did the reverse with regard to relative protein expression of desmin and albumin permeability (p < 0.05). Moreover, Dex treatment resulted in a decrease in ectodysplasin A2 receptor (EDA2R) expression in HG-induced podocytes. The level of EDA2R was upregulated by the transfection of overexpression plasmid containing the EDA2R sequences. Overexpression of EDA2R reversed Dex-induced increase in cell viability, apoptosis, expression of nephrin, podocin and desmin, as well as albumin permeability in HG-stimulated podocytes (p < 0.05).
 Conclusion: Dex ameliorates HG-induced podocyte injury via inhibition of EDA2R, indicating that Dex is a potential alternative drug for the treatment of podocyte injury.

Fabrication of Gd2O3/PSF Membranes via Aqueous Phase Inversion Method

This study aimed to investigate the effect of Gadolinium oxide (Gd2O3) concentration (0.5%, 1%, and 2%) on the performance of polysulfone (PSF) membrane. The membranes were fabricated by a common phase inversion method. The performance of membranes was determined based on pure water flux, bovine serum albumin (BSA) permeation test. These fabricated membranes were characterized by FTIR and contact angle measurements. The highest BSA rejection was 53%. The optimum membrane (2 % wt Gd2O3 /17 % wt PSF) in this study was determined by PSF 17% which successfully exhibited 53% rejection with filtrate flux for about 8.7 L/m2.h at a pressure of 10 bar.

Permeation of albumin through the skin depending on its concentration and the substrate used in simulated conditions in vivo

ObjectiveMany drugs applied to the skin with a systemic effect do not have a therapeutic effect, due to the barrier posed by the complex structure of the skin. To counteract this, absorption promoters are often added to the drug formulation. The use of albumin as an effective drug carrier is increasingly being addressed. Albumin, a natural, non-toxic polymer, can target drugs to specific cells and extend their biological half-life. This study was designed to trace the permeation of albumin after topical administration to the skin as a potential carrier of therapeutic substances. Materials and methodsFour dermal formulations based on different polymers were prepared: methyl cellulose, sodium alginate, hypromellose and chitosan with methyl cellulose, obtaining final concentrations of albumin of 2%, 1.5% and 1%. The permeation of albumin through the skin was examined under simulated in vivo conditions. ResultsMost albumin permeated from the methylcellulose-based hydrogel. Depending on the concentration of albumin, permeation profiles were plotted and permeation rate constant and AUC(0–24 h) were calculated. ConclusionMethylcellulose was the optimal polymer for albumin release, whereas hypromellose was the least favorable. The concentration of albumin influences the amount and rate of permeation of this protein. The optimal concentration was 10 mg/g, from which the most albumin penetrated and the fastest. Human skin appeared to be more permeable to albumin than pig skin. However, the similar permeation profile through both membranes successfully allows the use of pig skin to track and evaluate the permeation of therapeutic substances with systemic effects.

Enhancement of cGMP-dependent pathway activity ameliorates hyperglycemia-induced decrease in SIRT1-AMPK activity in podocytes: Impact on glucose uptake and podocyte function

Hyperglycemia significantly decreases 3′,5′-cyclic guanosine monophosphate (cGMP)-dependent pathway activity in the kidney. A well-characterized downstream signaling effector of cGMP is cGMP-dependent protein kinase G (PKG), exerting a wide range of downstream effects, including vasodilation and vascular smooth muscle cells relaxation. In podocytes that are exposed to high glucose concentrations, crosstalk between the protein deacetylase sirtuin 1 (SIRT1) and adenosine monophosphate-dependent protein kinase (AMPK) decreased, attenuating insulin responsiveness and impairing podocyte function. The present study examined the effect of enhancing cGMP-dependent pathway activity on SIRT1-AMPK crosstalk in podocytes under hyperglycemic conditions. We found that enhancing cGMP-dependent pathway activity using a cGMP analog was associated with increases in SIRT1 protein levels and activity, with a concomitant increase in the degree of AMPK phosphorylation. The beneficial effects of enhancing cGMP-dependent pathway activity on SIRT1-AMPK crosstalk also included improvements in podocyte function. Based on our findings, we postulate an important role for SIRT1-AMPK crosstalk in the regulation of albumin permeability in hyperglycemia that is strongly associated with activity of the cGMP-dependent pathway.

Prostanoid receptors in hyperfiltration-mediated glomerular injury: Novel agonists and antagonists reveal opposing roles for EP2 and EP4 receptors.

Increased fluid-flow shear stress (FFSS) contributes to hyperfiltration-induced podocyte and glomerular injury resulting in progression of chronic kidney disease (CKD). We reported that increased FFSS in vitro and in vivo upregulates PGE2 receptor EP2 (but not EP4 expression), COX2-PGE2 -EP2 axis, and EP2-linked Akt-GSK3β-β-catenin signaling pathway in podocytes. To understand and use the disparities between PGE2 receptors, specific agonists, and antagonists of EP2 and EP4 were used to assess phosphorylation of Akt, GSK3β and β-catenin in podocytes using Western blotting, glomerular filtration barrier function using in vitro albumin permeability (Palb ) assay, and mitigation of hyperfiltration-induced injury in unilaterally nephrectomized (UNX) mice at 1 and 6 months. Results show an increase in Palb by PGE2 , EP2 agonist (EP2AGO ) and EP4 antagonist (EP4ANT ), but not by EP2 antagonist (EP2ANT ) or EP4 agonist (EP4AGO ). Pretreatment with EP2ANT blocked the effect of PGE2 or EP2AGO on Palb . Modulation of EP2 and EP4 also induced opposite effects on phosphorylation of Akt and β-Catenin. Individual agonists or antagonists of EP2 or EP4 did not induce significant improvement in albuminuria in UNX mice. However, treatment with a combination EP2ANT + EP4AGO for 1 or 6 months caused a robust decrease in albuminuria. EP2ANT + EP4AGO combination did not impact adaptive hypertrophy or increased serum creatinine. Observed differences between expression of EP2 and EP4 on the glomerular barrier highlight these receptors as potential targets for intervention. Safe and effective mitigating effect of EP2ANT + EP4AGO presents a novel opportunity to delay the progression of hyperfiltration-associated CKD as seen in transplant donors.

Effect of Sericin Additive on Cellulose Acetate Membrane Morphology and Protein Rejection

Cellulose acetate (CA) membranes are synthesized for filtration purpose. The hydrophilic sericin macromolecule is blended with CA to analyze the enhancement of protein rejection. Increase in hydrophilicity, water permeation and protein rejection was studied by using contact angle, pure water flux (PWF) and Bovine serum albumin (BSA) permeation respectively. Surface modification was examined using SEM and AFM. The results show the homogenous blending of sericin in CA matrix and effective fabrication of membranes. In order to gauge the efficiency of casted membranes in protein filtration and separation, water flux and protein rejection were studied. The concentration of sericine protein was altered in CA polymeric solution that imparts variable properties to fabricated membrane samples. Increment in wt% of sericine up to 7.5 in polymer dope solution, enhances BSA rejection to the limit of 96%. The amino linkages between sericine and the BSA of feed resulted in the holding of protein by sericine, which leads to low permeation of BSA via CA-Sericine membrane M4.

PTEN-induced kinase 1 deficiency alters albumin permeability and insulin signaling in podocytes.

Alterations of insulin signaling in diabetes are associated with podocyte injury, proteinuria, and renal failure. Insulin stimulates glucose transport to cells and regulates other intracellular processes that are linked to cellular bioenergetics, such as autophagy, gluconeogenesis, fatty acid metabolism, and mitochondrial homeostasis. The dysfunction of mitochondrial dynamics, including mitochondrial fusion, fission, and mitophagy, has been observed in high glucose-treated podocytes and renal cells from patients with diabetes. Previous studies showed that prolonged hyperglycemia is associated with the development of insulin resistance in podocytes, and high glucose-treated podocytes exhibit an increase in mitochondrial fission and decrease in markers of mitophagy. In the present study, we found that deficiency of the main mitophagy protein PTEN-induced kinase 1 (PINK1) significantly increased albumin permeability and hampered glucose uptake to podocytes. We suggest that PINK1 inhibition impairs the insulin signaling pathway, in which lower levels of phosphorylated Akt and membrane fractions of the insulin receptor and glucose transporter-4 were observed. Moreover, PINK1-depleted podocytes exhibited lower podocin and nephrin expression, thus identifying a potential mechanism whereby albumin leakage increases under hyperglycemic conditions when mitophagy is inhibited. In conclusion, we found that PINK1 plays an essential role in insulin signaling and the maintenance of proper permeability in podocytes. Therefore, PINK1 may be a potential therapeutic target for the treatment or prevention of diabetic nephropathy.

PD21-02 NOVEL MECHANISMS OF INJURY IN MEMBRANOUS NEPHROPATHY

You have accessJournal of UrologyCME1 May 2022PD21-02 NOVEL MECHANISMS OF INJURY IN MEMBRANOUS NEPHROPATHY Qi Zhang, Paolo Cravedi, Astgik Petrosyan, Valentina Villani, Roger De Filippo, Laura Perin, and Stefano Da Sacco Qi ZhangQi Zhang More articles by this author , Paolo CravediPaolo Cravedi More articles by this author , Astgik PetrosyanAstgik Petrosyan More articles by this author , Valentina VillaniValentina Villani More articles by this author , Roger De FilippoRoger De Filippo More articles by this author , Laura PerinLaura Perin More articles by this author , and Stefano Da SaccoStefano Da Sacco More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002559.02AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Primary membranous nephropathy (MN) is a leading cause of nephrotic syndrome in adults worldwide due to the deposition of anti-podocyte-anlibodies against in the glomerular subepithelial space. While complement deposition is thought to play a crucial pathogenic role, the exact effector mechanism of complement in MN is unclear due to the lack of in vitro and in vivo systems that recapitulate human disease. We have developed a novel glomerulus-on-a-chip system (GOAC) using human primary podocytes and glomerular endothelial cells (GEC) and assessed functional response to human MN serum, role of Membrane-attack-complex (MAC) formation and C3a/C3aR1 signaling in MN pathogenesis. METHODS: GOACs were cultured with serum containing either anti-PLA2R+ or THSD7A+ MN patients; sera from healthy individuals were used as control. Functional response was assessed by albumin permeability assay to evaluate permselectivity. Role of MAC and C3a/C3aR1 signaling pathway was assessed by immunofluorescence and functional analysis while mechanisms of action were explored by PCR arrays, Western Blotting and immunostaining. Results were confirmed in vitro using podocytes on which C3aR1 was silenced and in vivo using THSD7A induced MN in balb/c mice. RESULTS: Following exposure to sera from MN patients, we have confirmed deposition of human lgG on podocytes and formation of MAC complex, accompanied by albumin leakage. MAC inhibition did not prevent albumin leakage while GOAC supplemented with C3aR1 antagonists as well as GOAC using podocytes in which C3aR1 was silenced were able to prevent glomerular filtration damage and albumin leakage. Efficacy of C3aR1 antagonists in preventing proteinuria was confirmed in vivo, substantiating our findings. CONCLUSIONS: We have successfully developed a glomerulus-on-a-chip system that closely mimics the GFB structure and provides a powerful tool for studying renal regenerative and disease mechanisms in proteinuric diseases. Using a combination of in vitro and in vivo models, we showed that C3a/C3aR signaling plays a dominant role in complement-mediated MN pathogenesis. Source of Funding: GOFARR Fund NIH NIDDK RO1 © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e361 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Qi Zhang More articles by this author Paolo Cravedi More articles by this author Astgik Petrosyan More articles by this author Valentina Villani More articles by this author Roger De Filippo More articles by this author Laura Perin More articles by this author Stefano Da Sacco More articles by this author Expand All Advertisement PDF DownloadLoading ...

Protective effects of tadalafil on damaged podocytes in an adriamycin-induced nephrotic syndrome model

Podocyte injury is responsible for nephrotic syndrome. Previously, we found that tadalafil, a phosphodiesterase 5 inhibitor, might have protective effects on podocytes. Here, we investigated the effects of tadalafil in a nephrotic syndrome model and human podocyte cells.We divided adriamycin (ADR)-induced nephrotic syndrome model rats into the following groups: control + vehicle, control + tadalafil, ADR + vehicle, and ADR + tadalafil. The tadalafil-treated groups were orally administered 10 mg/kg tadalafil for 2 weeks. Renal parameters were measured. Immunohistology and immunofluorescence assays of glomerular injury were performed. Human primary podocytes were treated with or without tadalafil, and ADR. Cell viability and permeability assays were performed.ADR + vehicle exhibited severe proteinuria compared with control + vehicle and control + tadalafil. ADR + tadalafil attenuated proteinuria compared with ADR + vehicle. Wilms’ tumor 1 (WT1) immunostaining revealed that the number of WT1-positive cells was decreased by ADR; however, this decrease was prevented by ADR + tadalafil. In human podocytes, tadalafil increased the viability of ADR-treated cells, which was abrogated by KT5823, a cGMP-dependent protein kinase (PKG) inhibitor. Moreover, tadalafil prevented albumin permeability in ADR-treated cells. ADR treatment alone increased the permeability of albumin compared with the control.Tadalafil might inhibit kidney injury progression by preventing damage to podocytes and dysfunction of the glomerular filtration barrier.

Hypothyroidism-Related Cardiac Tamponade

Thyroid dysfunction is a common incidental finding among healthy individuals. It can affect various organs of the body, including the heart. Among many other heart complications, it can lead to pericardial effusion by causing increased permeability of albumin across the pericardial membrane that leads to exudative pericardial effusion. In hypothyroidism, the fluid collection process occurs over a period of months, giving enough time for the pericardial membrane to stretch and accommodate the fluid within itself without causing any symptoms. Eventually, the pericardial membrane stretches to its maximum capacity and has no room to accommodate any more fluid, resulting in cardiac tamponade in the patients. Patients with hypothyroidism-related cardiac tamponade usually remain asymptomatic or present with atypical symptoms such as bradycardia and a normal heart rate or high blood pressure, and the diagnosis comes into light only when patients present to the hospital with hemodynamic instability. In these cases, echocardiography successfully detects large pericardial effusion with collapsed cardiac chambers. To treat hypothyroidism-related cardiac tamponade, treating the underlying condition has been very successful in the majority of the asymptomatic patients, but pericardiocentesis is required in emergencies to relieve symptoms of patients presenting with hemodynamic instability.We believe hypothyroidism-related cardiac tamponade is a preventable condition if detected and treated in outpatient settings by family physicians. This will prevent occurrence of various complications arising from hypothyroidism, including pericardial effusion. This will lead to a better quality of life among patients with the added benefit of reduced health care burden due to reduced frequency of hospital admissions of acutely ill patients.

Designing of a novel polyvinylidene fluoride/TiO2/UiO-66-NH2 membrane with photocatalytic antifouling properties using modified zirconium-based metal-organic framework.

Novel polyvinylidene fluoride/TiO2/UiO-66-NH2 (PVDF/TiUN) membranes were produced by the delay phase separation method via introducing the TiO2/UiO-66-NH2 (TiUN) nanocomposite into PVDF casting solution. Interconnection of TiO2 and UiO-66-NH2 improved photocatalysis capacity and endowed PVDF/TiUN membranes with self-cleaning capability. Quantitative measurements showed that, firstly, PVDF/TiUN membranes exhibited improved photodegradation kinetics and efficiency (up to 88.1%) to Rhodamine B (RhB). Secondly, the performances of bovine serum albumin (BSA) rejection and permeation of PVDF/TiUN membranes outperformed those of other check samples, indicating enhanced hydrophilicity. Thirdly, rejection rate of BSA reached a breathtaking 98.14% and flux recovery ratio (FRR) of BSA reached a breathtaking 95.37%. Thus, given their excellent anti-contamination property and separation performance, the PVDF/TiUN membrane is very likely to be a novel water treatment membrane.

Evans blue dye as an indicator of albumin permeability across a brain endothelial cell monolayer in vitro.

An increase in the brain endothelial (BEnd) cell permeability of blood albumin is often seen as an early sign of blood-brain barrier (BBB) disruption and can precede increases in the BEnd permeability of small molecules and other plasma proteins in the course of brain disease. Therefore, Evans blue dye (EBD), an albumin-binding fluorescent tracer that is simple to detect and quantify, has been widely utilized for studying BEnd permeability during BBB disruption. Here, we investigated whether EBD is a suitable indicator of albumin permeability across mouse BEnd cell monolayers, alone or cocultured with mouse cortical astrocytes, in an in-vitro permeability assay; given the strong affinity of EBD for albumin, we further asked whether EBD can affect albumin permeability and vice versa. Albumin and EBD readily crossed membrane cell culture inserts with pore diameters of no less than 1 µm in the absence of a cellular barrier, and their permeability was substantially reduced when the membranes were overlaid with a monolayer of BEnd cells. In line with albumin binding, the BEnd permeability of EBD was substantially reduced by the presence of albumin. While EBD at an EBD-to-albumin ratio similar to those typically used in in vivo BBB experiments had little effect on the BEnd permeability of albumin, a much higher concentration of EBD augmented the BEnd permeability of albumin. In conclusion, we investigated the use of EBD as an indicator of albumin permeability in vitro, explored some of its drawbacks and further demonstrated that EBD at the concentration used in vivo does not affect albumin permeability.

Role of Klotho in Hyperglycemia: Its Levels and Effects on Fibroblast Growth Factor Receptors, Glycolysis, and Glomerular Filtration.

Hyperglycemic conditions (HG), at early stages of diabetic nephropathy (DN), cause a decrease in podocyte numbers and an aberration of their function as key cells for glomerular plasma filtration. Klotho protein was shown to overcome some negative effects of hyperglycemia. Klotho is also a coreceptor for fibroblast growth factor receptors (FGFRs), the signaling of which, together with a proper rate of glycolysis in podocytes, is needed for a proper function of the glomerular filtration barrier. Therefore, we measured levels of Klotho in renal tissue, serum, and urine shortly after DN induction. We investigated whether it influences levels of FGFRs, rates of glycolysis in podocytes, and albumin permeability. During hyperglycemia, the level of membrane-bound Klotho in renal tissue decreased, with an increase in the shedding of soluble Klotho, its higher presence in serum, and lower urinary excretion. The addition of Klotho increased FGFR levels, especially FGFR1/FGFR2, after their HG-induced decrease. Klotho also increased levels of glycolytic parameters of podocytes, and decreased podocytic and glomerular albumin permeability in HG. Thus, we found that the decrease in the urinary excretion of Klotho might be an early biomarker of DN and that Klotho administration may have several beneficial effects on renal function in DN.

Mechanical Ventilation Exacerbates Poly (I:C) Induced Acute Lung Injury: Central Role for Caspase-11 and Gut-Lung Axis.

BackgroundThe mechanisms by which moderate tidal volume ventilation (MTV) exacerbates preexisting lung injury are unclear. We hypothesized that systemic endotoxemia via the gut-lung axis would lead to non-canonical and canonical inflammasome activation and pyroptosis in a two-hit model involving polyinosinic-polycytidylic acid (Poly(I:C)), a synthetic analog of dsRNA and MTV and that this would associate with acute lung injury (ALI).MethodsAnesthetized mice were administered Poly(I:C) intratracheally and then 6 h later, they were mechanically ventilated for 4 h with otherwise non-injurious MTV (10ml/kg). Changes in intestinal and alveolar capillary permeability were measured. Further documentation of ALI was assessed by evans blue albumin permeability, protein and IL-1 family concentration in bronchoalveolar lavage fluid (BALF) or plasma, and histopathology in cohorts of wildtype (WT), whole body genetically ablated caspase-11 (caspase-11-/-), caspase-1/caspase-11 double knockout (caspase-1/11-/-), gasdermin D (GSDMD)-/-, nucleotide-binding domain leucine-rich repeat-containing protein 3 (NLRP3)-/- and advanced glycosylation end product-specific receptor (RAGE) -/- mice.ResultsNon-injurious MTV exacerbated the mild lung injury associated with Poly(I:C) administration. This included the disruption of alveolar-capillary barrier and increased levels of interleukin (IL)-6, high mobility group proteins 1 (HMGB-1), IL-1β in BALF and IL-18 in plasma. Combined (Poly(I:C)-MTV) injury was associated with increase in gastrointestinal permeability and endotoxin in plasma and BALF. Poly(I:C)-MTV injury was sensitive to caspase-11 deletion with no further contribution of caspase-1 except for maturation and release of IL-18 (that itself was sensitive to deletion of NLRP3). Combined injury led to large increases in caspase-1 and caspase-11. Genetic ablation of GSDMD attenuated alveolar-capillary disruption and release of cytokines in combined injury model.ConclusionsThe previously noted exacerbation of mild Poly(I:C)-induced ALI by otherwise non-injurious MTV is associated with an increase in gut permeability resulting in systemic endotoxemia. The gut-lung axis resulted in activation of pulmonary non-canonical (cytosolic mediated caspase-11 activation) and canonical (caspase-1) inflammasome (NLRP3) mediated ALI in this two-hit model resulting in GSDMD sensitive alveolar capillary barrier disruption, pyroptosis (alveolar macrophages) and cytokine maturation and release (IL-1β; IL-18). Pharmacologic strategies aimed at disrupting communication between gut and lung, inhibition of inflammasomes or GSDMD in pyroptosis may be useful in ALI.

Protective effects of klotho on palmitate-induced podocyte injury in diabetic nephropathy.

The anti-aging gene, klotho, has been identified as a multi-functional humoral factor and is implicated in multiple biological processes. However, the effects of klotho on podocyte injury in diabetic nephropathy are poorly understood. Thus, the current study aims to investigate the renoprotective effects of klotho against podocyte injury in diabetic nephropathy. We examined lipid accumulation and klotho expression in the kidneys of diabetic patients and animals. We stimulated cultured mouse podocytes with palmitate to induce lipotoxicity-mediated podocyte injury with or without recombinant klotho. Klotho level was decreased in podocytes of lipid-accumulated obese diabetic kidneys and palmitate-treated mouse podocytes. Palmitate-treated podocytes showed increased apoptosis, intracellular ROS, ER stress, inflammation, and fibrosis, and these were significantly attenuated by klotho administration. Klotho treatment restored palmitate-induced downregulation of the antioxidant molecules, Nrf2, Keap1, and SOD1. Klotho inhibited the phosphorylation of FOXO3a, promoted its nuclear translocation, and then upregulated MnSOD expression. In addition, klotho administration attenuated palmitate-induced cytoskeleton changes, decreased nephrin expression, and increased TRPC6 expression, eventually improving podocyte albumin permeability. These results suggest that klotho administration prevents palmitate-induced functional and morphological podocyte injuries, and this may indicate that klotho is a potential therapeutic agent for the treatment of podocyte injury in obese diabetic nephropathy.

Neutrophil extracellular traps are associated with altered human pulmonary artery endothelial barrier function

Introduction: Acute respiratory response syndrome (ARDS) leads to increased permeability of the endothelial-epithelial barrier, which in turn promotes edema formation and hypoxemic respiratory failure. Although activated neutrophils are thought to play a significant role in mediating ARDS, at present the contribution of neutrophil extracellular traps (NETs) to lung endothelial barrier function is unclear. Methods: To clarify their role, we co-cultured in vitro NETs induced by phorbol myristate acetate (PMA)–activated neutrophils with lung endothelial cell monolayers and examined the barrier function of lung endothelial cells by immunofluorescence microscopy and albumin permeability in a double-chamber culture method. Results: Co-culture with stimulated neutrophils increased the albumin permeability of the human pulmonary artery endothelial cell (HPAEC) monolayer and altered cytoskeleton F-actin and vascular endothelial-cadherin in cell-cell junctions. Hyperpermeability to albumin and histological alterations were prevented by inhibition of NET formation with peptidyl arginine deiminase inhibitor or a neutrophil elastase inhibitor and were also prevented by increased degradation of NET structure with DNase. Conclusion: This in vitro experiment shows that altered HPAEC barrier function and increased albumin permeability are caused by the direct effect of PMA-induced NETs and their components. NET formation may be involved in the increased vascular permeability of the lung, which is a common feature in ARDS of various etiologies. These insights may help generate novel approaches for medical interventions.

Fucoidan- and carrageenan-based biosynthetic poly(vinyl alcohol) hydrogels for controlled permeation

Since the permeation of the inflammatory cytokines into hydrogel scaffolds has been shown to cause dysfunction of encapsulated cells, appropriate design strategies to circumvent this are essential. In the present work, it was hypothesized that highly crosslinked PVA-fucoidan and PVA-carrageenan hydrogels can control permeation of the trefoil-shaped inflammatory cytokine IL-1β while allowing the permeation of the globular protein albumin. PVA, fucoidan, and carrageenans were functionalized with methacrylate groups and the functionalized polymers were co-crosslinked by UV photopolymerization. The resultant hydrogels were characterized physicochemically and the release of fucoidan and carrageenans was quantified by developing a colorimetric assay, which was validated by XPS analysis. The permeability characteristics of the hydrogels were evaluated using bovine serum albumin (BSA), IgG, and IL-1β. The results demonstrated an increase in hydrogel swelling through the incorporation of the polysaccharides with minimal overall mass loss. The release studies showed hydrogel stability, where the formulations exhibited ~43% retention of fucoidan and ~60–80% retention of carrageenans consistently up to 7 days. The permeation data revealed very low permeation of IgG and IL-1β through the hydrogels, with <1% permeation after 24 h, while allowing >6% permeation of BSA. These data indicate that such hydrogels can be used as the basis for cytokine-protective implantable devices for clinical applications.

Evaluation of an octyl group-modified Alaska pollock gelatin-based surgical sealant for prevention of postoperative adhesion

Postoperative adhesion can lead to an increase in the number of surgeries required, longer operation times, and high medical costs, resulting in the quality of life of the patient being lowered. To address these clinical problems, we developed a surgical sealant with anti-adhesion properties for the prevention of postoperative adhesion following application to the large intestine surface. The developed sealant was composed of octyl (C8) group-modified Alaska pollock-derived gelatin (C8-ApGltn) and a poly(ethylene)glycol-based 4-armed crosslinker (4S-PEG) (C8-ApGltn/4S-PEG sealant). Hydrophobic modification of the ApGltn molecule with C8 groups effectively enhanced both the burst strength on the large intestine surface and the bulk modulus. An in vitro anti-adhesion test indicated that cured C8-ApGltn/4S-PEG sealant adhered to the large intestine surface showed low adhesive strength compared with commercial anti-adhesion film. Besides, cured C8-ApGltn/4S-PEG sealant effectively inhibited albumin permeation and penetration of L929 fibroblasts. In vivo experiments using a rat peritoneal anti-adhesion model showed that C8-ApGltn/4S-PEG sealant acted as a sealing barrier on the target cecum surface and also provided an anti-adhesion barrier to prevent postoperative adhesion between the peritoneum and cecum. C8-ApGltn/4S-PEG sealant showed sufficient cytocompatibility and biodegradability and therefore has potential for use in gastroenterological surgery.