Adjuvant comprising nano-aluminum hydroxide pickering emulsion with polysialic acid for enhanced vaccination.

The expression of polysialic acid (polySia) on the neuronal cell adhesion molecule (NCAM) is called NCAM-polysialylation, which is strongly related to the migration and invasion of tumor cells and aggressive clinical status. During the NCAM polysialylation process, polysialyltransferases (polySTs), such as polysialyltransferase IV (ST8SIA4) or polysialyltransferase II (ST8SIA2), can catalyze the addition of CMP-sialic acid (CMP-Sia) to the NCAM to form polysialic acid (polySia). In this study, the docking models of polysialyltransferase IV (ST8Sia4) protein and different ligands were predicted using Alphafold 3 and DiffDock servers, and the prediction accuracy was further verified using the NMR experimental spectra of the interactions between polysialyltransferase domain (PSTD), a crucial peptide domain in ST8Sia4, and a different ligand. This combination strategy provides new insights into a quick and effective screening for inhibitors of tumor cell migration.

Chronic psychological stress is a major cause of various psychiatric disorders, such as depression and anxiety; however, the pathophysiological features of these disorders remain largely unknown. Polysialic acid (PSA), a linear homopolymer of α2-8-linked sialic acid residues, binds to the neural cell adhesion molecule (NCAM) and is involved in cell-to-cell interactions during neural cell migration and neurite outgrowth. Decreased PSA and PSA-NCAM expression have been observed in the brains of patients with psychiatric disorders. Nevertheless, the relationship between psychological stress and PSA has not been clarified. Thus, we examined whether chronic social defeat stress (cSDS), a well-established psychosocial stress model in rodents, affects PSA levels in the male mouse brain. Male C57BL/6J mice were exposed to social defeat stress for 10 consecutive days, after which their whole brains were collected. PSA and NCAM protein levels in the hippocampus and prefrontal cortex were analyzed by western blotting. In addition, we measured the expression of genes involved in PSA metabolism by real-time quantitative PCR analysis. Exposure to cSDS decreased PSA and NCAM protein levels in the hippocampus, but not in the prefrontal cortex. We also found that the expression of genes involved in removing sialic acid from NCAM, such as neuraminidase 3 and 4, was significantly elevated in the hippocampus of mice exposed to cSDS. We provide evidence showing that psychosocial stress disrupts PSA metabolism in adult mice brains. These findings advance our understanding of the mechanisms underlying the onset of stress-related psychiatric disorders.

Moraxella bovis is a majoretiologicagent for infectious bovine keratoconjunctivitis (IBK), commonly knownas bovine pink eye. IBK has been a major economic burden to the cattleand dairy industries due to its economic and welfare impacts on affectedcattle herds. Antimicrobial treatment of acute IBK infections is oftenchallenging. Vaccine formulations widely used in industry have poorefficacy for the prevention of IBK. Capsular polysaccharides of somebacterial pathogens are important epidemiological markers and aresuccessfully used in vaccines for humans. Currently, there are limiteddata demonstrating the presence of capsular polysaccharides in M. bovis. In this study, we show by genomic analysisthat a broad selection of M. bovis strainsobtained from the eyes of cattle harbor a gene cluster for expressingcapsular polysaccharides. The isolates potentially express eithera chondroitin-like polysaccharide or an α(2–8) polysialicacid. We isolated a polysaccharide from cultures of a well-studiedmodel strain for IBK, the Epp63 strain, structurally identical tocapsule α(2–8) polysialic acid of the human pathogens Escherichia coli K1 and Neisseriameningitidis Group B. The gene cluster in M. bovis Epp63 encodes a polysialyltransferase similarto other bacterial polysialyltransferases. Other M.bovis strains analyzed in this study possess a genehomologous to that of bacterial chondroitin synthase. We isolateda capsular polysaccharide from M. bovis genotypes 1 and 2 that has the repeat unit identical to nonsulfatedchondroitin. These findings provide a tool for the study of M. bovis IBK pathogenesis that could lead to approachesfor better control of the disease.

Deep vein thrombosis (DVT) is a serious medical condition that can lead to life-threatening complications. Conventional or nanotechnology-based antithrombotic therapies frequently lead to incomplete thrombolysis and may result in DVT recurrence. Emerging evidence highlights that the persistent neutrophil extracellular traps (NETs) scaffold synergistically interacts with reactive oxygen species overproduction and inflammatory cascades, collectively compromising thrombus resolution and establishing a prothrombotic microenvironment for recanalization failure. Hence, in response to this pathomechanism, a bismuth (Bi)-based nanoplatform (PSA@Bi-TNK-HCQ; PBTH) was constructed. PBTH nanoparticles (NPs) were delivered in a targeted manner to activated endothelial cells via polysialic acid (PSA) and enabled thrombus visualization through dual-energy computed tomography imaging. Therapeutically, a dual-drug antithrombotic effect was achieved through the breakdown of fibrin by tenecteplase (TNK) and the inhibition of NET structures by hydroxychloroquine (HCQ). This mechanistically complementary approach showed superior thrombolytic performance in vivo compared to monotherapy, with a residual thrombus rate of 18.7%. Furthermore, the multienzyme-like activities of PBTH NPs restored endothelial function by mitigating oxidative stress damage and inflammation, thereby preventing thrombus recurrence and pulmonary embolism. The vicious cycle of NET-mediated thrombosis-associated immune dysregulation, a locally abnormal thrombotic microenvironment, and endothelial dysfunction was ultimately broken. This work provides a promising two-pronged approach to the treatment of DVT by increasing the effectiveness of thrombolysis while reducing the risk of reocclusion.Graphical Supplementary InformationThe online version contains supplementary material available at 10.1186/s12951-025-03864-3.

B cell malfunction is implicated in the pathogenesis of systemic lupus erythematosus (SLE) through the release of proinflammatory cytokines and the production of autoreactive antibodies. RNA N6-methyladenosine (m6A) is the predominant post-transcriptional RNA modification that has been reported to control various biological processes. Whether RNA m6A alteration and m6A reader protein YTHDF1 contribute to B cell activation and terminal B cell differentiation in SLE has not been fully demonstrated. Here we observed that SLE peripheral B cell subsets, activated B cells and differentiated plasma cells (PCs) had abnormally elevated levels of YTHDF1, the deficit of which attenuated PC differentiation both in vitro and in mouse models that have been immunized with keyhole limpet hemocyanin (KLH) or N-propionyl polysialic acid (NP-KLH). Utilizing RNA sequencing, RNA immunoprecipitation, m6A immunoprecipitation and other functional experiments, we have identified and described a PC-promoting role of YTHDF1. YTHDF1 binds to the m6A-marked 3' untranslated region of transcription factor IRF4 messenger RNA to enhance its stability, thereby facilitating PC differentiation. Depletion of YTHDF1 hindered the differentiation of PCs, reduced the generation of autoantibodies and ameliorated the lupus-like phenotypes in an imiquimod-treated mouse model. Overall, this study highlights a distinct role of YTHDF1 in promoting PC differentiation through the direct regulation of IRF4 in an m6A-dependent manner and identifies YTHDF1 as a potential target for the treatment of SLE.

Harnessing engineered adaptive nanoparticles to modulate macrophages for treating corneal alkali burns.

Sialic acids are widely distributed monosaccharides in the central nervous system (CNS), where they are predominantly found as terminal sialic acid residues, as well as in di-, oligo-, and polysialic forms on the glycocalyx, collectively contributing to the development, resilience, and long-term integrity of the CNS. Harnessing sialic acid–binding immunoglobulin-like lectin (Siglec) receptors by α2.8-linked polysialic acids has been shown to modulate immune responses. In this study, murine and human monocytes were exposed to α2.8-linked low molecular weight polysialic acid (α2.8-polySIA) in vitro, followed by phenotypic, functional, and transcriptomic analyses using flow cytometry and RNA sequencing; therapeutic efficacy was assessed in mice with experimental autoimmune encephalomyelitis (EAE), a pre-clinical model of multiple sclerosis (MS). Here, we report that α2.8-polySIA inhibits toll-like receptor-induced phenotypical and functional maturation of murine and human monocytes into pro-inflammatory effector cells equipped with operational antigen-presenting machinery. Moreover, RNA sequencing analyses revealed a shift towards a regulatory phenotype in human myeloid cells exposed to α2.8-polySIA. Finally, therapeutic treatment with α2.8-polySIA led to a milder disease course in EAE mice. Thus, by tuning myeloid cell phenotype in vivo, the therapeutic application of polysialic acid may offer a novel approach to modulate myeloid-driven inflammation in CNS autoimmunity.

Glycosylation regulates immune and neural functions within the central nervous system (CNS), yet biomaterials rarely leverage glycans due to their structural complexity. Polysialic acid (PSA), comprising α2,8-linked sialic acid residues, is a promising candidate owing to its potent immunomodulatory interactions with inhibitory Siglec receptors. Systematic screening of multiple sialic acid derivatives identifies PSA as uniquely effective in inducing anti-inflammatory polarization of bone marrow-derived macrophages (BMDMs). Based on these findings, an injectable microporous annealed particle (MAP) scaffold presenting PSA covalently via its reducing end (MAP-PSA) is engineered, recapitulating physiological glycan orientation. MAP-PSA exhibits robust mechanical properties, stable glycan immobilization, and resistance to enzymatic degradation. Using ischemic stroke as a CNS injury model, MAP-PSA significantly reduces neutrophil infiltration and inflammatory activation while enhancing reparative macrophage and microglial phenotypes. These immunomodulatory effects persist into subacute stages, characterized by sustained reductions in inflammation and enhanced microglial homeostasis. Overall, MAP-PSA scaffolds demonstrate a novel therapeutic paradigm for CNS injuries such as stroke, with translational potential for broader neuroinflammatory and regenerative applications.

Recovery following ischemic stroke remains limited due to insufficient neural regeneration. Polysialic acid (PSA), a glycan prominently expressed during neural development, modulates neural progenitor cell (NPC) plasticity and migration, but its therapeutic potential in biomaterial-based stroke therapies remains underexplored. In this study, microporous annealed particle (MAP) scaffolds conjugated with PSA (PSA-MAP) were engineered to regulate NPC fate and promote neural tissue regeneration after stroke. PSA-MAP increased the presence of Sox2-positive progenitor cells within infarct and peri-infarct regions and elevated axonal content (NF200) in the lesion, while astrocytic and vascular coverage were not detectably changed at this early stage. In addition, 3D NPC cultures in MAP showed that tethered PSA alters NPC behavior over time, with reduced progenitor marker expression and PSA-dependent shifts in morphology, consistent with progression away from a progenitor state. Together, these data identify a glycan-forward, neuro-first repair route in which PSA-MAP enhances early neural regeneration without requiring concomitant angiogenic expansion, establishing PSA-MAP as a targeted biomaterial approach for endogenous neural repair after ischemic stroke.

Polysialic-emodin self-assembled nanoparticles synergize with PD-1 inhibitors to enhance tumor immunotherapy.

Glioblastoma (GBM) is a highly aggressive brain tumor marked by invasive growth and therapy resistance. Tumor cells adapt to hostile conditions, such as hypoxia and nutrient deprivation, by activating survival mechanisms including autophagy and metabolic reprogramming. Among GBM-associated changes, hypersialylation, particularly, the aberrant expression of polysialic acid (PSA), has been linked to increased plasticity, motility, and immune evasion. PSA, a long α2,8-linked sialic acid polymer typically attached to the NCAM, is abundant in the embryonic brain and re-expressed in cancers, correlating with poor prognosis. Here, we investigated how PSA expression was regulated in GBM cells under nutrient-limiting conditions. Serum starvation induced a marked increase in PSA-NCAM, driven by upregulation of the polysialyltransferase ST8SiaIV and an autophagy-dependent recycling of sialic acids from degraded glycoproteins. Inhibition of autophagy or sialidases impaired PSA induction, and PSA regulation appeared dependent on p53 function. Immunohistochemical analysis of GBM tissues revealed co-localization of PSA and LC3, particularly around necrotic regions. In conclusion, we identified a novel mechanism by which GBM cells sustain PSA-NCAM expression via autophagy-mediated sialic acid recycling under nutrient stress. This pathway may enhance cell migration, immune escape, and stem-like properties, offering a potential therapeutic target in GBM.

Study of binding specificity and affinity of multimeric aptamers to trisialic acid and engineering of aptamer bio-dots for detecting polysialic acid on cell surfaces.

Neu1 sialidase regulates heterospecific social interaction in zebrafish via D1 dopamine receptor.

Engineering affinity-matured variants of an anti-polysialic acid monoclonal antibody with superior cytotoxicity-mediating potency.

Sialylation is a modification process involving the addition of sialic acid residues to the termini of glycoproteins and glycolipids in mammalian cells. Sialylation serves as a crucial checkpoint inhibitor of the complement and immune systems, particularly within the central nervous system (CNS), including the retina. Complement factor H (FH), complement factor properdin (FP), and sialic acid-binding immunoglobulin-like lectin (SIGLEC) receptors of retinal mononuclear phagocytes are key players in regulating the complement and innate immune systems in the retina by recognizing sialic acid (Sia) residues. Intact retinal sialylation prevents any long-lasting and excessive complement or immune activation in the retina. However, sialylated glycolipids are reduced in the CNS with aging, potentially contributing to chronic inflammatory processes in the retina. Particularly, genetically induced hyposialylation in mice leads to age-related, complement factor C3-mediated retinal inflammation and bipolar cell loss. Notably, most of the gene transcript pathways enriched in the mouse retina, following genetically induced hyposialylation, are also involved in age-related macular degeneration (AMD). Interestingly, intravitreal application of polysialic acid (polySia) controlled the innate immune responses in the mouse retina by blocking mononuclear phagocyte reactivity, inhibiting complement activation, and protecting against vascular damage in two different humanized SIGLEC-11 animal models. Accordingly, a polySia polymer conjugate has entered clinical phase II/III testing in patients with geographic atrophy secondary to AMD. Thus, hyposialylation or dysfunctional sialylation should be considered as an age-related contributor to inflammatory retinal diseases, such as AMD. Consequently, sialic acid-based biologics could provide novel therapies for complement-related retinal diseases.

Mucopolysaccharidoses (MPS) are lysosomal storage diseases caused by defects in catabolism of glycosaminoglycans. MPS I, II, III, and VII, which are associated with lysosomal accumulation of heparan sulphate (HS), manifest with neurological deterioration and currently lack effective treatments. We report that neuraminidase 1 (NEU1) activity is drastically reduced in brain tissues of patients with neurological MPS and mouse models but not in neurological lysosomal disorders without HS storage. Accumulated HS disrupts the lysosomal multienzyme complex of NEU1 with cathepsin A, β-galactosidase (GLB1), and glucosamine-6-sulfate sulfatase (GALNS), leading to NEU1 deficiency and partial GLB1 and GALNS deficiencies in cortical tissues and induced pluripotent stem cell-derived (iPSC-derived) cortical neurons of patients with neurological MPS. Increased sialylation of N-linked glycans in brains of patients with MPS and mice implicated insufficient processing of sialylated glycans, except for polysialic acid. Correction of NEU1 activity in MPS IIIC mice by lentiviral (LV) gene transfer ameliorated previously identified hallmarks of the disease, including memory impairment, behavioral traits, and reduced levels of excitatory synapse markers VGLUT1 and PSD95. Overexpression of NEU1 also restored levels of VGLUT1/PSD95-positive puncta in cortical iPSC-derived MPS IIIA neurons. Our results demonstrate that HS-induced secondary NEU1 deficiency and aberrant sialylation of brain glycoproteins constitute what we believe is a novel pathological pathway in the neurological MPS spectrum crucially contributing to CNS pathology.

Safety concerns about general anesthetics (GA), such as desflurane (a commonly used gaseous anesthetic agent), arose from studies documenting neural cell death and behavioral changes after early-life exposure to anesthetics and compounds with related modes of action. Neural stem cells (NSCs) can recapitulate most critical events during central nervous system (CNS) development in vivo and, therefore, represent a valuable in vitro model for evaluating potential desflurane-induced developmental neurotoxicity. In this study, NSCs harvested from the hippocampus of a gestational day 80 monkey brain were applied to explore the temporal relationships between desflurane exposures and neural stem cell health, proliferation, differentiation, and viability. At clinically relevant doses (5.7%), desflurane exposure did not result in significant changes in NSC viability [lactate dehydrogenase (LDH) release] and NSC proliferation profile/rate by Cell Cycle Assay, in both short term (3h) and prolonged (24h) exposure groups. However, when monkey NSCs were guided to differentiate into neural cells (including neurons, astrocytes, and oligodendrocytes), and then exposed to desflurane (5.7%), no significant changes were detected in LDH release after a 3-h exposure, but a significant elevation in LDH release into the culture medium was observed after a 24-h exposure. Desflurane (24h)-induced neural damage was further supported by increased expression levels of multiple cytokines, e.g., G-CSF, IL-12, IL-9, IL-10, and TNF-α compared with the controls. Additionally, our immunocytochemistry and flow cytometry data demonstrated a remarkable attenuation of differentiated neurons as evidenced by significantly decreased numbers of polysialic acid neural cell adhesion molecule (PSA-NCAM)-positive cells in the desflurane-exposed (prolonged) cultures. Our data suggests that at the clinically relevant concentration, desflurane did not induce NSC damage/death, but impaired the differentiated neuronal cells after prolonged exposure. Collectively, PSA-NCAM could be essential for neuronal viability. Desflurane-induced neurotoxicity was primarily associated with the loss of differentiated neurons. Changes in the neuronal specific marker, PSA-NCAM, may help understand the underlying mechanisms associated with anesthetic-induced neuronal damage. These findings should be helpful/useful for the understanding of the diverse effects of desflurane exposure on the developing brain and could be used to optimize the usage of these agents in the pediatric setting.

Polysialic acid (polySia), a glycoepitope critical for neural development and plasticity, remains difficult to quantify owing to its structural complexity. Here, we present a highly sensitive sandwich enzyme-linked immunosorbent assay (ELISA) utilizing novel probes to measure polySia expression. Using this method, we quantified polySia levels in mouse brain samples across various developmental and aging stages. Notable age-related changes were observed, particularly in neuroplastic regions such as the hippocampus and olfactory bulb, where polySia levels increased at 12 months, potentially reflecting resilience mechanisms against brain aging. Elevated polySia levels in blood samples were also detected in both a schizophrenia mouse model and human patients, with a notable male preponderance. In contrast, no significant changes were observed in patients with chronic inflammatory demyelinating polyneuropathy. These findings, enabled by the novel probes, highlight a potential role for polySia in brain aging and neuropsychiatric disorders, offering new insights into developmental and disease mechanisms and supporting its utility as a diagnostic biomarker for brain impairments.

The complexes of negatively charged polysaccharides with lipid vesicles have been shown to have applications in medicine, bioremediation, water purification, and construction of nano-biosensors. This article presents research on the formation of these complexes based on the interactions between three types of liposomes, DOPC liposomes (which contain a lipid bilayer in the liquid-disordered (Ld) state), RAFT liposomes (which contain liquid-ordered (Lo) lipid raft domains surrounded by lipids in the Ld state) and SPH-CHL liposomes (which contain a lipid bilayer in the Lo state), and two selected anionic polysaccharides, polysialic acid (PSA) and polygalacturonic acid (PGA). The analysis was conducted using a toluidine blue (TB) probe and the absorption spectroscopy technique. In contrast to DOPC and SPH-CHL liposomes, binding of negatively charged PSA or PGA chains to RAFT liposomes induced a TB absorption maximum shift from 630 nm to 560 nm. The obtained results indicate that toluidine blue can be applied for monitoring the formation of these nano-complexes, and that the boundaries between Ld/Lo domains within membranes in RAFT liposomes can significantly enhance the binding affinity of negatively charged polysaccharides to the lipid bilayer surface. The observed metachromatic shift in TB absorption suggests that negatively charged PSA and PGA chains interact with the Ld/Lo boundaries within RAFT liposome membranes.