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BACKGROUND: The etiology of steroid-resistant nephrotic syndrome, which manifests as FSGS, is not completely understood. Aberrant glycosylation is an often underestimated factor for pathologic processes, and structural changes in the glomerular endothelial glycocalyx have been correlated with models of nephrotic syndrome. Glycans are frequently capped by sialic acid (Sia), and sialylation's crucial role for kidney function is well known. Human podocytes are highly sialylated; however, sialylation's role in podocyte homeostasis remains unclear. METHODS: We generated a podocyte-specific sialylation-deficient mouse model (PCmas-/- ) by targeting CMP-Sia synthetase, and used histologic and ultrastructural analysis to decipher the phenotype. We applied CRISPR/Cas9 technology to generate immortalized sialylation-deficient podocytes (asialo-podocytes) for functional studies. RESULTS: Progressive loss of sialylation in PCmas-/- mice resulted in onset of proteinuria around postnatal day 28, accompanied by foot process effacement and loss of slit diaphragms. Podocyte injury led to severe glomerular defects, including expanded capillary lumen, mesangial hypercellularity, synechiae formation, and podocyte loss. In vivo, loss of sialylation resulted in mislocalization of slit diaphragm components, whereas podocalyxin localization was preserved. In vitro, asialo-podocytes were viable, able to proliferate and differentiate, but showed impaired adhesion to collagen IV. CONCLUSIONS: Loss of cell-surface sialylation in mice resulted in disturbance of podocyte homeostasis and FSGS development. Impaired podocyte adhesion to the glomerular basement membrane most likely contributed to disease development. Our data support the notion that loss of sialylation might be part of the complex process causing FSGS. Sialylation, such as through a Sia supplementation therapy, might provide a new therapeutic strategy to cure or delay FSGS and potentially other glomerulopathies.
Assuntos
Glomerulosclerose Segmentar e Focal/patologia , Podócitos/patologia , Ácidos Siálicos/metabolismo , Animais , Proliferação de Células , Sobrevivência Celular , Modelos Animais de Doenças , Glomerulosclerose Segmentar e Focal/fisiopatologia , Glicosilação , Humanos , Camundongos , Modelos Animais , Sensibilidade e EspecificidadeRESUMO
Polysialic acid is a glycan modification of the neural cell adhesion molecule (NCAM) produced by the polysialyltransferases ST8SIA2 and ST8SIA4. Polysialic acid has been detected in multiple sclerosis plaques, but its beneficial or adverse role in remyelination is elusive. Here, we show that, despite a developmental delay, myelination at the onset and during cuprizone-induced demyelination was unaffected in male Ncam1-/- or St8sia2-/- mice. However, remyelination, restoration of oligodendrocyte densities, and motor recovery after the cessation of cuprizone treatment were compromised. Impaired differentiation of NCAM- or ST8SIA2-negative oligodendrocyte precursors suggested an underlying cell-autonomous mechanism. In contrast, premature differentiation in ST8SIA4-negative cultures explained the accelerated remyelination previously observed in St8sia4-/- mice. mRNA profiling during differentiation of human stem cell-derived and primary murine oligodendrocytes indicated that the opposing roles of ST8SIA2 and ST8SIA4 arise from sequential expression. We also provide evidence that potentiation of ST8SIA2 by 9-cis-retinoic acid and artificial polysialylation of oligodendrocyte precursors by a bacterial polysialyltransferase are mechanisms to promote oligodendrocytic differentiation. Thus, differential targeting of polysialyltransferases and polysialic acid engineering are promising strategies to advance the treatment of demyelinating diseases.SIGNIFICANCE STATEMENT The beneficial or adverse role of polysialic acid (polySia) in myelin repair is a long-standing question. As a modification of the neural cell adhesion molecule (NCAM), polySia is produced by the polysialyltransferases ST8SIA2 and ST8SIA4. Here we demonstrate that NCAM and ST8SIA2 promote oligodendrocyte differentiation and myelin repair as well as motor recovery after cuprizone-induced demyelination. In contrast, ST8SIA4 delays oligodendrocyte differentiation, explaining its adverse role in remyelination. These opposing roles of the polysialyltransferases are based on different expression profiles. 9-cis-retinoic acid enhances ST8SIA2 expression, providing a mechanism for understanding how it supports oligodendrocyte differentiation and remyelination. Furthermore, artificial polysialylation of the cell surface promotes oligodendrocyte differentiation. Thus, boosting ST8SIA2 and engineering of polySia are promising strategies for improving myelin repair.
Assuntos
Antígeno CD56/biossíntese , Diferenciação Celular/fisiologia , Bainha de Mielina/metabolismo , Oligodendroglia/metabolismo , Sialiltransferases/biossíntese , Animais , Células Cultivadas , Doenças Desmielinizantes/metabolismo , Células-Tronco Embrionárias/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Atividade Motora/fisiologia , Molécula L1 de Adesão de Célula Nervosa , Distribuição Aleatória , Ácidos Siálicos/biossínteseRESUMO
The negatively charged nonulose sialic acid (Sia) is essential for murine development in vivo. In order to elucidate the impact of sialylation on differentiation processes in the absence of maternal influences, we generated mouse embryonic stem cell (mESC) lines that lack CMP-Sia synthetase (CMAS) and thereby the ability to activate Sia to CMP-Sia. Loss of CMAS activity resulted in an asialo cell surface accompanied by an increase in glycoconjugates with terminal galactosyl and oligo-LacNAc residues, as well as intracellular accumulation of free Sia. Remarkably, these changes did not impact intracellular metabolites or the morphology and transcriptome of pluripotent mESC lines. Moreover, the capacity of Cmas-/- mESCs for undirected differentiation into embryoid bodies, germ layer formation and even the generation of beating cardiomyocytes provides first and conclusive evidence that pluripotency and differentiation of mESC in vitro can proceed in the absence of (poly)sialoglycans.
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Camadas Germinativas/metabolismo , Células-Tronco Embrionárias Murinas/metabolismo , Miócitos Cardíacos/metabolismo , N-Acilneuraminato Citidililtransferase/deficiência , Células-Tronco Pluripotentes/metabolismo , Ácidos Siálicos/metabolismo , Amino Açúcares/metabolismo , Animais , Diferenciação Celular , Linhagem Celular , Embrião de Mamíferos , Corpos Embrioides/citologia , Corpos Embrioides/metabolismo , Efeito Fundador , Galactose/metabolismo , Expressão Gênica , Camadas Germinativas/citologia , Glicoconjugados/metabolismo , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Células-Tronco Embrionárias Murinas/citologia , Miócitos Cardíacos/citologia , N-Acilneuraminato Citidililtransferase/genética , Células-Tronco Pluripotentes/citologia , TranscriptomaRESUMO
BACKGROUND: Lower extremity tendinopathy is a common sports injury, but it can also affect non-athletes. Because tendinopathy is difficult to treat and has negative effects on the ability to work and quality of life, development of preventive interventions is important. The first step in the Van Mechelen prevention model is to determine the extent of the problem. The primary aim of this study was to determine the incidence and prevalence of lower extremity tendinopathy in a Dutch general practice population. The secondary aim was to investigate possible associated factors. METHODS: A cross-sectional study was performed in a Dutch general practice. Using International Classification of Primary Care codes, the electronic patient files were searched to identify cases of adductor tendinopathy, greater trochanteric pain syndrome, jumper's knee, Achilles tendinopathy, and plantar fasciopathy in 2012. The tendinopathy patients were compared to the general practice population regarding age, gender, use of medication, and comorbidity using 95% confidence intervals. RESULTS: The prevalence and incidence rates of lower extremity tendinopathy found in this study were 11.83 and 10.52 per 1000 person-years. Lower extremity tendinopathy was more prevalent among older patients. No differences between tendinopathy patients and the general practice population were found regarding gender, use of medication, or comorbidity. CONCLUSIONS: In this cross-sectional study in a Dutch general practice, the prevalence and incidence rates of lower extremity tendinopathy were 11.83 and 10.52 per 1000 person-years. Lower extremity tendinopathy deserves a higher place in locomotor system research to develop preventive interventions.
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Medicina Geral/métodos , Extremidade Inferior/lesões , Vigilância da População , Tendinopatia/diagnóstico , Tendinopatia/epidemiologia , Adolescente , Adulto , Idoso , Estudos Transversais , Feminino , Medicina Geral/tendências , Humanos , Incidência , Extremidade Inferior/patologia , Masculino , Pessoa de Meia-Idade , Países Baixos/epidemiologia , Vigilância da População/métodos , Prevalência , Estudos Retrospectivos , Tendinopatia/terapia , Adulto JovemRESUMO
BACKGROUND: Optimizing transitional care by practicing family-centered care might reduce unplanned events for patients who undergo major abdominal cancer surgery. However, it remains unknown whether involving family caregivers in patients' healthcare also has negative consequences for patient safety. This study assessed the safety of family involvement in patients' healthcare by examining the cause of unplanned events in patients who participated in a family involvement program (FIP) after major abdominal cancer surgery. METHODS: This is a secondary analysis focusing on the intervention group of a prospective cohort study conducted in the Netherlands. Data were collected from April 2019 to May 2022. Participants in the intervention group were patients who engaged in a FIP. Unplanned events were analyzed, and root causes were identified using the medical version of a prevention- and recovery-information system for monitoring and analysis (PRISMA) that analyses unintended events in healthcare. Unplanned events were compared between patients who received care from family caregivers and patients who received professional at-home care after discharge. A Mann-Whitney U test was used to analyze data. RESULTS: Of the 152 FIP participants, 68 experienced an unplanned event and were included. 112 unplanned events occurred with 145 root causes since some unplanned events had several root causes. Most root causes of unplanned events were patient-related factors (n = 109, 75%), such as patient characteristics and disease-related factors. No root causes due to inadequate healthcare from the family caregiver were identified. Unplanned events did not differ statistically (interquartile range 1-2) (p = 0.35) between patients who received care from trained family caregivers and those who received professional at-home care after discharge. CONCLUSION: Based on the insights from the root-cause analysis in this prospective multicenter study, it appears that unplanned emergency room visits and hospital readmissions are not related to the active involvement of family caregivers in surgical follow-up care. Moreover, surgical follow-up care by trained family caregivers during hospitalization was not associated with increased rates of unplanned adverse events. Hence, the concept of active family involvement by proficiently trained family caregivers in postoperative care appears safe and feasible for patients undergoing major abdominal surgery.
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PURPOSE: Interactions with tumor-associated microglia and macrophages (TAM) are critical for glioblastoma progression. Polysialic acid (polySia) is a tumor-associated glycan, but its frequency of occurrence and its prognostic value in glioblastoma are disputed. Through interactions with the opposing immune receptors Siglec-11 and Siglec-16, polySia is implicated in the regulation of microglia and macrophage activity. However, due to a nonfunctional SIGLEC16P allele, SIGLEC16 penetrance is less than 40%. Here, we explored possible consequences of SIGLEC16 status and tumor cell-associated polySia on glioblastoma outcome. EXPERIMENTAL DESIGN: Formalin-fixed paraffin-embedded specimens of two independent cohorts with 70 and 100 patients with newly diagnosed glioblastoma were retrospectively analyzed for SIGLEC16 and polySia status in relation to overall survival. Inflammatory TAM activation was assessed in tumors, in heterotypic tumor spheroids consisting of polySia-positive glioblastoma cells and Siglec-16-positive or Siglec-16-negative macrophages, and by exposing Siglec-16-positive or Siglec-16-negative macrophages to glioblastoma cell-derived membrane fractions. RESULTS: Overall survival of SIGLEC16 carriers with polySia-positive tumors was increased. Consistent with proinflammatory Siglec-16 signaling, levels of TAM positive for the M2 marker CD163 were reduced, whereas the M1 marker CD74 and TNF expression were increased, and CD8+ T cells enhanced in SIGLEC16/polySia double-positive tumors. Correspondingly, TNF production was elevated in heterotypic spheroid cultures with Siglec-16-expressing macrophages. Furthermore, a higher, mainly M1-like cytokine release and activating immune signaling was observed in SIGLEC16-positive as compared with SIGLEC16-negative macrophages confronted with glioblastoma cell-derived membranes. CONCLUSIONS: Collectively, these results strongly suggest that proinflammatory TAM activation causes the better outcome in patients with glioblastoma with a functional polySia-Siglec-16 axis.
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Glioblastoma , Lectinas Semelhantes a Imunoglobulina de Ligação ao Ácido Siálico , Humanos , Glioblastoma/patologia , Ativação de Macrófagos , Estudos RetrospectivosRESUMO
CONTEXT: Several studies have been conducted to better understand the effect of load on the Achilles tendon structure. However, the effect of a high cumulative load consisting of repetitive cyclic movements, such as those that occur during the running of a marathon, on Achilles tendon structure is not yet clear. Clinicians, coaches, and athletes will benefit from knowledge about the effects of a marathon on the structure of the Achilles tendon. OBJECTIVE: To investigate the short-term response of the Achilles tendon structure to running a marathon. DESIGN: Case series (prospective). SETTING: Sports medicine centers. PATIENTS OR OTHER PARTICIPANTS: Ten male nonelite runners who ran in a marathon. MAIN OUTCOMES MEASURE(S): Tendon structure was assessed before and 2 and 7 days after a marathon using ultrasound tissue characterization (UTC), an imaging tool that quantifies tendon organization in 4 echo types (I-IV). Echo type I represents the most stable echo pattern, and echo type IV, the least stable. RESULTS: At 7 days postmarathon, both the insertional and midportion structure changed significantly. At both sites, the percentage of echo type II increased (insertion P < .01; midportion P = .02) and the percentages of echo types III and IV decreased (type III: insertion P = .01; midportion P = .02; type IV: insertion P = .01; midportion P < .01). Additionally, at the insertion, the percentage of echo type I decreased (P < .01). CONCLUSIONS: We observed the effects of running a marathon on the Achilles tendon structure 7 days after the event. Running the marathon combined with the activity performed shortly thereafter might have caused the changes in tendon structure. This result emphasizes the importance of sufficient recovery time after running a marathon to prevent overuse injuries.
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Tendão do Calcâneo/anatomia & histologia , Resistência Física/fisiologia , Corrida/fisiologia , Tendão do Calcâneo/diagnóstico por imagem , Tendão do Calcâneo/lesões , Adulto , Idoso , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fatores de Tempo , UltrassonografiaRESUMO
The negatively charged sugar sialic acid (Sia) occupies the outermost position in the bulk of cell surface glycans. Lack of sialylated glycans due to genetic ablation of the Sia-activating enzyme CMP-sialic acid synthase (CMAS) resulted in embryonic lethality around day 9.5 post coitum (E9.5) in mice. Developmental failure was caused by complement activation on trophoblasts in Cmas-/- implants and was accompanied by infiltration of maternal neutrophils at the fetal-maternal interface, intrauterine growth restriction, impaired placental development, and a thickened Reichert's membrane. This phenotype, which shared features with complement receptor 1-related protein Y (Crry) depletion, was rescued in E8.5 Cmas-/- mice upon injection of cobra venom factor, resulting in exhaustion of the maternal complement component C3. Here we show that Sia is dispensable for early development of the embryo proper but pivotal for fetal-maternal immune homeostasis during pregnancy, i.e., for protecting the allograft implant against attack by the maternal innate immune system. Finally, embryos devoid of cell surface sialylation suffered from malnutrition due to inadequate placentation as a secondary effect.