Short-chain fatty acid on blood-brain barrier and glial function in ischemic stroke.

Stroke is the second most common cause of death and one of the most common causes of disability worldwide. The intestine is home to several microorganisms that fulfill essential functions for the natural and physiological functioning of the human body. There is an interaction between the central nervous system (CNS) and the gastrointestinal system that enables bidirectional communication between them, the so-called gut-brain axis. Based on the gut-brain axis, there is evidence of a link between the gut microbiota and the regulation of microglial functions through glial activation. This interaction is partly due to the immunological properties of the microbiota and its connection with the CNS, such that metabolites produced by the microbiota can cross the gut barrier, enter the bloodstream and reach the CNS and significantly affect microglia, astrocytes and other cells of the immune system. Studies addressing the effects of short-chain fatty acids (SCFAs) on glial function and the BBB in ischemic stroke are still scarce. Therefore, this review aims to stimulate the investigation of these associations, as well as to generate new studies on this topic that can clarify the role of SCFAs after stroke in a more robust manner.

Mortality burden of cardiovascular disease attributable to ambient PM2.5 exposure in Portugal, 2011 to 2021.

BACKGROUND: Exposure to high levels of environmental air pollution causes several health outcomes and has been associated with increased mortality, premature mortality, and morbidity. Ambient exposure to PM2.5 is currently considered the leading environmental risk factor globally. A causal relationship between exposure to PM2.5 and the contribution of this exposure to cardiovascular morbidity and mortality was already demonstrated by the American Heart Association. METHODS: To estimate the burden of mortality attributable to environmental risk factors, a comparative risk assessment was performed, considering a "top-down" approach. This approach uses an existing estimate of mortality of the disease endpoint by all causes as a starting point. A population attributable fraction was calculated for the exposure to PM2.5the overall burden of IHD and stroke was multiplied by the PAF to determine the burden attributable to this risk factor. The avoidable burden was calculated using the potential impact fraction (PIF) and considering the WHO-AQG 2021 as an alternative scenario. RESULTS: Between 2011 and 2021, the ambient exposure to PM2.5 resulted in a total of 288,862.7 IHD YLL and a total of 420,432.3 stroke YLL in Portugal. This study found a decreasing trend in the mortality burden attributable to PM2.5 exposure, for both males and females and different age-groups. For different regions of Portugal, the same trend was observed in the last years. The mortality burden attributable to long-term exposure to PM2.5 was mainly concentrated in Lisbon Metropolitan Area, North and Centre. Changes in the exposure limits to the WHO recommended value of exposure (WHO-AQG 2021) have a reduction in the mortality burden due to IHD and stroke attributable to PM2.5 exposure, in Portugal. CONCLUSION: Between 2011 and 2021, approximately 22% and 23% of IHD and stroke deaths were attributable to PM2.5 exposure. Nevertheless, the mortality burden attributable to cardiovascular diseases has been decreasing in last years in Portugal. Our findings provide evidence of the impact of air pollution on human health, which are crucial for decision-making, at the national and regional level.

An online qualitative study exploring wants and needs for a cooking programme during pregnancy in the UK and Ireland.

BACKGROUND: Optimal maternal nutrition is associated with better pregnancy and infant outcomes. Culinary nutrition programmes have potential to improve diet quality during pregnancy. Therefore, this research aimed to understand the experiences of cooking and the wants and needs of pregnant women regarding a cooking and food skills programme in the United Kingdom (UK) and Republic of Ireland (ROI). METHODS: Online focus group discussions with pregnant women and those who had experienced a pregnancy in the UK or ROI were conducted between February and April 2022. Two researchers conducted a thematic analysis. Seven focus groups with ROI participants (n = 24) and six with UK participants (n = 28) were completed. RESULTS: Five themes were generated. These were (1) cooking during pregnancy: barriers, motivators and solutions; (2) food safety, stress and guilt; (3) need for cooking and food skills programmes and desired content; (4) programme structure; (5) barriers and facilitators to programme participation. Overall, there was support for a programme focusing on broad food skills, including planning, food storage, using leftovers and to manage pregnancy-specific physiological symptoms such as food aversions. Participants emphasised the importance of inclusivity for a diverse range of people and lifestyles for programme design and content. CONCLUSIONS: Current findings support the use of digital technologies for culinary nutrition interventions, potentially combined with in-person sessions using a hybrid structure to enable the development of a support network.

Bacillus Calmette-Guérin (BCG)-Induced Protection in Brain Disorders.

The Bacille Calmette-Guerin (BCG) vaccine is one of the most widely used vaccines in the world for the prevention of tuberculosis. Its immunological capacity also includes epigenetic reprogramming, activation of T cells and inflammatory responses. Although the main usage of the vaccine is the prevention of tuberculosis, different works have shown that the effect of BCG can go beyond the peripheral immune response and be linked to the central nervous system by modulating the immune system at the level of the brain. This review therefore aims to describe the BCG vaccine, its origin, its relationship with the immune system, and its involvement at the brain level.

Antagonistic effects of a COX1/2 inhibitor drug in human HepG2 cells exposed to an environmental carcinogen.

Understanding interactions between legacy and emerging environmental contaminants has important implications for risk assessment, especially when mutagens and carcinogens are involved, whose critical effects are chronic and therefore difficult to predict. The current work aimed to investigate potential interactions between benzo[a]pyrene (B[a]P), a carcinogenic polycyclic aromatic hydrocarbon and legacy pollutant, and diclofenac (DFC), a non-steroidal anti-inflammatory drug and pollutant of emerging concern, and how DFC affects B[a]P toxicity. Exposure to binary mixtures of these chemicals resulted in substantially reduced cytotoxicity in human HepG2 cells compared to single-chemical exposures. Significant antagonistic effects were observed in response to high concentrations of B[a]P in combination with DFC at IC50 and ⅕ IC50. While additive effects were found for levels of intracellular reactive oxygen species, antagonistic mixture effects were observed for genotoxicity. B[a]P induced DNA strand breaks, γH2AX activation, and micronuclei formation at ½ IC50 concentrations or lower, whereas DFC induced only low levels of DNA strand breaks. Their mixture caused significantly lower levels of genotoxicity by all three endpoints compared to those expected based on concentration additivity. In addition, antagonistic mixture effects on CYP1 enzyme activity suggested that the observed reduced genotoxicity of B[a]P was due to its reduced metabolic activation as a result of enzymatic inhibition by DFC. Overall, the findings further support the growing concern that co-exposure to environmental toxicants and their non-additive interactions may be a confounding factor that should not be neglected in environmental and human health risk assessment.

The ATR inhibitor ceralasertib potentiates cancer checkpoint immunotherapy by regulating the tumor microenvironment.

The Ataxia telangiectasia and Rad3-related (ATR) inhibitor ceralasertib in combination with the PD-L1 antibody durvalumab demonstrated encouraging clinical benefit in melanoma and lung cancer patients who progressed on immunotherapy. Here we show that modelling of intermittent ceralasertib treatment in mouse tumor models reveals CD8+ T-cell dependent antitumor activity, which is separate from the effects on tumor cells. Ceralasertib suppresses proliferating CD8+ T-cells on treatment which is rapidly reversed off-treatment. Ceralasertib causes up-regulation of type I interferon (IFNI) pathway in cancer patients and in tumor-bearing mice. IFNI is experimentally found to be a major mediator of antitumor activity of ceralasertib in combination with PD-L1 antibody. Improvement of T-cell function after ceralasertib treatment is linked to changes in myeloid cells in the tumor microenvironment. IFNI also promotes anti-proliferative effects of ceralasertib on tumor cells. Here, we report that broad immunomodulatory changes following intermittent ATR inhibition underpins the clinical therapeutic benefit and indicates its wider impact on antitumor immunity.

HBM4EU E-waste study: Assessing persistent organic pollutants in blood, silicone wristbands, and settled dust among E-waste recycling workers in Europe.

E-waste recycling is an increasingly important activity that contributes to reducing the burden of end-of-life electronic and electrical apparatus and allows for the EU's transition to a circular economy. This study investigated the exposure levels of selected persistent organic pollutants (POPs) in workers from e-waste recycling facilities across Europe. The concentrations of seven polychlorinated biphenyls (PCBs) and eight polybrominated diphenyl ethers (PBDEs) congeners were measured by GC-MS. Workers were categorized into five groups based on the type of e-waste handled and two control groups. Generalized linear models were used to assess the determinants of exposure levels among workers. POPs levels were also assessed in dust and silicone wristbands (SWB) and compared with serum. Four PCB congeners (CB 118, 138, 153, and 180) were frequently detected in serum regardless of worker's category. With the exception of CB 118, all tested PCBs were significantly higher in workers compared to the control group. Controls working in the same company as occupationally exposed (Within control group), also displayed higher levels of serum CB 180 than non-industrial controls with no known exposures to these chemicals (Outwith controls) (p < 0.05). BDE 209 was the most prevalent POP in settled dust (16 µg/g) and SWB (220 ng/WB). Spearman correlation revealed moderate to strong positive correlations between SWB and dust. Increased age and the number of years smoked cigarettes were key determinants for workers exposure. Estimated daily intake through dust ingestion revealed that ΣPCB was higher for both the 50th (0.03 ng/kg bw/day) and 95th (0.09 ng/kg bw/day) percentile exposure scenarios compared to values reported for the general population. This study is one of the first to address the occupational exposure to PCBs and PBDEs in Europe among e-waste workers through biomonitoring combined with analysis of settled dust and SWB. Our findings suggest that e-waste workers may face elevated PCB exposure and that appropriate exposure assessments are needed to establish effective mitigation strategies.

Prospective validation of an equation based on plasma cystatin C for monitoring the glomerular filtration rate in children treated with cisplatin or ifosfamide for cancer.

We recently proposed an equation to estimate the glomerular filtration rate (GFR) in children with cancer based on plasma cystatin C and serum creatinine levels together with body weight (the "CysPed equation"). The current clinical study reports a prospective evaluation of this equation in 18 children treated by nephrotoxic chemotherapy. The CysPed equation resulted in less bias and greater precision compared to two equations previously proposed equations by Schwartz, with or without plasma cystatin C. Moreover, the decrease in GFR due to chemotherapy was clearly identified by the CysPed equation. This equation may be used to monitor the renal function in childhood cancer units.

Configurations of mother-child and father-child attachment relationships as predictors of child language competence: An individual participant data meta-analysis.

An individual participant data meta-analysis was conducted to test pre-registered hypotheses about how the configuration of attachment relationships to mothers and fathers predicts children's language competence. Data from seven studies (published between 1985 and 2014) including 719 children (Mage : 19.84 months; 51% female; 87% White) were included in the linear mixed effects analyses. Mean language competence scores exceeded the population average across children with different attachment configurations. Children with two secure attachment relationships had higher language competence scores compared to those with one or no secure attachment relationships (d = .26). Children with two organized attachment relationships had higher language competence scores compared to those with one organized attachment relationship (d = .23), and this difference was observed in older versus younger children in exploratory analyses. Mother-child and father-child attachment quality did not differentially predict language competence, supporting the comparable importance of attachment to both parents in predicting developmental outcomes.

Acolhimento de pessoas com deficiência auditiva na Atenção Primária à Saúde no município de Criciúma, Santa Catarina / Reception of the hearing impaired in Primary Health Care in the municipality of Criciúma, Santa Catarina

As pessoas com deficiência auditiva (DA) possuem barreiras a serem descontruídas quando o assunto é acesso aos serviços de saúde. Estas se dão devido à dificuldade na comunicação, falta de profissionais qualificados, ausência de intérprete da Língua Brasileira de Sinais (LIBRAS) dentre outros aspectos. O objetivo deste trabalho é analisar o acolhimento dos indivíduos com surdez na Atenção Primária em Saúde (APS). Trata-se de um estudo de métodos mistos com triangulação concomitante por meio de um estudo descritivo e quantitativo. O estudo foi realizado nas Unidades Básicas de Saúde (UBS) do município de Criciúma ­ Santa Catarina, participaram os gerentes das unidades de saúde, cirurgiões dentistas, enfermeiros e médicos. Foram entrevistados 43 profissionais de saúde de 44 UBS diferentes do município, dos quais os resultados apontaram frágeis condições de acolhimento e atendimento humanizado das pessoas com DA que procuram as unidades básicas de saúde. A comunicação predominante é de forma verbal e na maioria das vezes, conta com a presença de um familiar durante as consultas para facilitar essa comunicação. Alguns profissionais afirmaram que o DA não possui atendimento humanizado, inclusivo e resolutivo, e que os programas de capacitação deixariam os atendimentos mais humanizados. Em suma, existem inúmeras barreiras no acolhimento dos pacientes com DA na APS, sendo necessária a aprimoração das práticas para que seja desenvolvido um atendimento inclusivo, humanizado, acolhedor e integral.

The person with hearing loss (AD) has barriers to be deconstructed regarding access to health services. These are due to the difficulty in communication, lack of qualified professionals, and absence of interpreters of Brazilian Sign Language, among other aspects. This study aims to analyze the reception of individuals with deafness in Primary Health Care (PHC). This is a mixed methods study with concomitant triangulation through descriptive and quantitative analysis. The study was conducted in the Basic Health Units (BHU) of the municipality of Criciúma - Santa Catarina, with the participation of managers of health units, dental surgeons, nurses, and physicians. Participants were 43 health professionals from 44 different BHUs in the city, of which the results showed fragile conditions of reception and humanized care of people with AD who seek basic health units. The predominant communication is verbal and, in most cases, relies on the presence of a family member during the consultations to facilitate this communication. Some professionals stated that the DA lacks humanized, inclusive and resolutive care and that the training programs would make the care more humanized. In short, there are numerous barriers in the reception of patients with AD in PHC, and it is necessary to improve practices so that inclusive, humanized, welcoming, and integral care is developed.

Development and validation of predictive equations for spirometry in Portuguese children.

Background: There are no data on lung function reference values for Portuguese children, and the contribution from the Portuguese data set in the Global Lung Function Initiative (GLI) is scant. Objectives: We aimed to estimate new up-to-date reference values for Portuguese children by fitting a multivariable regression model to a general population sample. Further, we intended to assess the external validity of the obtained reference values and to compare them to the GLI reference values. Methods: A random sample of 858 children from 20 primary schools were screened by health questionnaire, physical examination, and spirometry. Spirometric parameters recorded were FVC, FEV1, and FEF25-75. Multiple regression models were used to derive reference equations. Results: Overall, 481 children, aged between 7 and 12 years, 267 boys (55.5%), were included. Boys had higher values for FVC and FEV1 than girls (P < .05). The strongest correlation was found for FVC with height (r = 0.71 for boys and 0.70 for girls), while the lowest correlation was observed in both sexes for FEF25-75 with age (r = 0.23). Height was the most significant predictor of FVC, FEV1, and FEF25-75 in our models. Weight and body mass index were not significant predictors for boys but had a significant effect on girls' equations for all spirometry parameters. Compared to obtained reference equations with GLI, they performed better for FVC in boys, FEV1 in girls, and FEF25-75 in both boys and girls. Conclusion: We offer up-to-date reference values of spirometry for Portuguese children that can be used in clinical practice and research.

Evaluation of the Potential Impact of In Silico Humanization on VHH Dynamics.

Camelids have the peculiarity of having classical antibodies composed of heavy and light chains as well as single-chain antibodies. They have lost their light chains and one heavy-chain domain. This evolutionary feature means that their terminal heavy-chain domain, VH, called VHH here, has no partner and forms an independent domain. The VHH is small and easy to express alone; it retains thermodynamic and interaction properties. Consequently, VHHs have garnered significant interest from both biotechnological and pharmaceutical perspectives. However, due to their origin in camelids, they cannot be used directly on humans. A humanization step is needed before a possible use. However, changes, even in the constant parts of the antibodies, can lead to a loss of quality. A dedicated tool, Llamanade, has recently been made available to the scientific community. In a previous paper, we already showed the different types of VHH dynamics. Here, we have selected a representative VHH and tested two humanization hypotheses to accurately assess the potential impact of these changes. This example shows that despite the non-negligible change (1/10th of residues) brought about by humanization, the effect is not drastic, and the humanized VHH retains conformational properties quite similar to those of the camelid VHH.

Frequency-encoded two-photon excited fluorescence microscopy.

Two-photon excited fluorescence (2PEF) microscopy is the most popular non-linear imaging method of biomedical samples. State-of-the art 2PEF microscopes use multiple detectors and spectral filter sets to discriminate different fluorophores based on their distinct emission behavior (emission discrimination). One drawback of 2PEF is that fluorescence photons outside the filter transmission range are inherently lost, thereby reducing the imaging efficiency and speed. Furthermore, emission discrimination of different fluorophores may fail if their emission profiles are too similar. Here, we present an alternative 2PEF method that discriminates fluorophores based on their excitation spectra (excitation discrimination). For excitation we use two lasers of different wavelengths (ω1, ω2) resulting in excitation energies at 2ω1, 2ω2, and the mixing energy ω1+ω2. Both lasers are frequency encoded (FE) by an intensity modulation at distinct frequencies while all 2PEF emission is collected on a single detector. The signal is fed into a lock-in-amplifier and demodulated at various frequencies simultaneously. A customized nonnegative matrix factorization (NNMF) then generates fluorescence images that are free of cross talk. Combining FE-2PEF with multiple detectors has the potential to enable the simultaneous imaging of an unprecedented number of fluorophores.

How to use human biomonitoring in chemical risk assessment: Methodological aspects, recommendations, and lessons learned from HBM4EU.

One of the aims of the European Human Biomonitoring Initiative, HBM4EU, was to provide examples of and good practices for the effective use of human biomonitoring (HBM) data in human health risk assessment (RA). The need for such information is pressing, as previous research has indicated that regulatory risk assessors generally lack knowledge and experience of the use of HBM data in RA. By recognising this gap in expertise, as well as the added value of incorporating HBM data into RA, this paper aims to support the integration of HBM into regulatory RA. Based on the work of the HBM4EU, we provide examples of different approaches to including HBM in RA and in estimations of the environmental burden of disease (EBoD), the benefits and pitfalls involved, information on the important methodological aspects to consider, and recommendations on how to overcome obstacles. The examples are derived from RAs or EBoD estimations made under the HBM4EU for the following HBM4EU priority substances: acrylamide, o-toluidine of the aniline family, aprotic solvents, arsenic, bisphenols, cadmium, diisocyanates, flame retardants, hexavalent chromium [Cr(VI)], lead, mercury, mixture of per-/poly-fluorinated compounds, mixture of pesticides, mixture of phthalates, mycotoxins, polycyclic aromatic hydrocarbons (PAHs), and the UV-filter benzophenone-3. Although the RA and EBoD work presented here is not intended to have direct regulatory implications, the results can be useful for raising awareness of possibly needed policy actions, as newly generated HBM data from HBM4EU on the current exposure of the EU population has been used in many RAs and EBoD estimations.

Involvement of Brazilian adolescents in home cooking: An exploratory analysis (EVA-JF Study).

OBJECTIVE: The aim of this study was to investigate the involvement of Brazilian adolescents in home cooking, estimating its associations with sex and socioeconomic status. METHODS: This cross-sectional study involved a probabilistic sample of 14- to 19-y-olds enrolled in 29 public schools in the municipality of Juiz de Fora, MG, Southeast Brazil (n = 835). To assess involvement in home cooking, a 12-question questionnaire was used. The content was based on the Brazilian Food Guide, which encourages the acquisition, development, and sharing of culinary skills. Pearson's χ test and Poisson regression models were carried out, without and with adjustments. RESULTS: Most of the adolescents did not usually participate in meal planning (61%), and in the choice/purchase of food and culinary ingredients (67%). Boys were less likely to know how to cook "from scratch", positively self-evaluate their culinary skills, enjoy cooking, wish to learn more about cooking and meal preparation, and to participate frequently in the planning and preparation of meals. Belonging to a lower socioeconomic status represented a greater probability of preparing meals alone for the family. CONCLUSIONS: We verified an alarming prevalence of adolescents with behaviors unaligned with Brazilian Food Guide recommendations; that is, most of them, especially boys, were not involved in home cooking. Adolescence may present a window of opportunity for the development of culinary skills, resulting in long-term benefits for the population's diet quality. Furthermore, to change a historical pattern that overloads women's daily lives, it is necessary to encourage, from an early age, the presence of boys in the kitchen.

Ultra-processed foods in institutional food services: what are diners eating?

Introduction. Frequent use of ultra-processed foods (UPF) leads to poor health outcomes, and the population must avoid their consumption. Objective. To assess the occurrence of ultra-processed foods (UPFs) in culinary lunch menus from various institutional food services. Materials and methods. Over one month, the five institutional food services analyzed served 1,128 culinary preparations; and a total of 3,863 ingredients were classified according to the extent and purpose of processing using the NOVA classification system. Associations between the occurrence of UPFs and the type, size, and management of food service establishments were analyzed. Five institutional food services in three municipalities (Bauru, Limeira, and Campinas), Brazil. Results. We found 8.4 % up to 12.6 % UPF ingredients used in culinary preparations. The highest frequency of UPFs was associated with private cafeterias (p = 0.002). Most UPFs were part of the recipe or the main ingredient in protein dishes and desserts (p < 0.05) and in university and hospital food services, respectively. UPF use was associated with food service size and type of management (p ≤ 0.003) and was more prevalent in protein dishes (p = 0.003) and large-size institutional food services (28.8 %). Self-managed units (p = 0.03) also use high amounts of UPFs in protein dishes (20.3 %). Conclusions. The presence of UPF rounded 10%; the validity of this value needs further studies. There are no comparative data in the scientific literature regarding the use of these ingredients in institutional food service culinary preparations. Therefore, it is necessary to stimulate reflection to promote healthy food habits and adequate nutrition for diners(AU)

Introducción. El uso frecuente de alimentos ultraprocesados (UPF) conduce a complicaciones de salud, y la población debe evitar su consumo. Objetivo. Evaluar la presencia de alimentos ultraprocesados (UPFs) en los menús de almuerzos de diversos servicios de alimentación institucionales. Materiales y métodos. Durante un mes, los cinco servicios de alimentación institucionales analizados sirvieron 1.128 preparaciones culinarias; y se clasificaron un total de 3.863 ingredientes según el alcance y el propósito del procesamiento, utilizando el sistema de clasificación NOVA. Se analizaron las asociaciones entre la ocurrencia de UPFs y el tipo, tamaño y gestión de los establecimientos de servicio de alimentos. Cinco servicios institucionales de alimentación en tres municipios (Bauru, Limeira y Campinas), Brasil. Resultados. Se encontró entre un 8,4 % hasta un 12,6 % de ingredientes UPF utilizados en las preparaciones culinarias. La mayor frecuencia de UPF se asoció a cafeterías privadas (p = 0,002). La mayoría de los UPFs formaban parte de la receta o eran el ingrediente principal en platos proteicos y postres (p < 0,05) y en los servicios de alimentación universitarios y hospitalarios, respectivamente. El uso de UPFs se asoció con el tamaño del servicio de alimentación y el tipo de gestión (p≤ 0,003) y fue más frecuente en platos proteicos (p = 0,003) y servicios de alimentación institucional de gran tamaño (28,8 %). Las unidades autogestionadas (p = 0,03) también utilizan altas cantidades de UPF en platos proteicos (20,3 %). Conclusiones. La presencia de UPF ronda el 10 %; la validez de este valor necesita más estudios. No existen datos comparativos en la literatura científica sobre el uso de estos ingredientes en las preparaciones culinarias de los servicios de alimentación institucional. Por ello, es necesario estimular la reflexión para promover hábitos alimentarios saludables y una adecuada nutrición de los comensales(AU)

Household food insecurity before and during COVID-19 pandemic and its association with perceived stress: population-based studies.

The growing prevalence of food insecurity observed in the last years, has been favored by the COVID-19 pandemic, leading to mental health issues, such as stress. We aim to analyze the prevalence of household food insecurity before and during the COVID-19 pandemic and its association with perceived stress. We analyzed data from two population-based studies conducted in 2019 and 2020-2021 in the municipality of Criciúma, State of Santa Catarina, Southern Brazil. Food insecurity and perceived stress were assessed with the Brazilian Food Insecurity Scale and the Perceived Stress Scale. The covariables were sex, age, skin color, schooling level, income, job status, marital status, household crowding, overweight, and diet quality. Crude and adjusted associations between food insecurity and perceived stress were assessed using Poisson regression. A total of 1,683 adult individuals were assessed. Prevalence of food insecurity was 25.8% in 2019, decreasing to 21.6% in 2020. Prevalence of perceived stress was about 38% for both years. Before the pandemic, food insecurity increased the prevalence of perceived stress by 29% (PR = 1.29; 95%CI: 1.02; 1.63), but no association was found during COVID-19. We found a worrying prevalence of food insecurity before and after de pandemic, nonetheless food insecurity and perceived stress were associated only in 2019. An assessment of these aspects after COVID-19 is needed to ensure basic life rights for all.

Human septins organize as octamer-based filaments and mediate actin-membrane anchoring in cells.

Septins are cytoskeletal proteins conserved from algae and protists to mammals. A unique feature of septins is their presence as heteromeric complexes that polymerize into filaments in solution and on lipid membranes. Although animal septins associate extensively with actin-based structures in cells, whether septins organize as filaments in cells and if septin organization impacts septin function is not known. Customizing a tripartite split-GFP complementation assay, we show that all septins decorating actin stress fibers are octamer-containing filaments. Depleting octamers or preventing septins from polymerizing leads to a loss of stress fibers and reduced cell stiffness. Super-resolution microscopy revealed septin fibers with widths compatible with their organization as paired septin filaments. Nanometer-resolved distance measurements and single-protein tracking further showed that septin filaments are membrane bound and largely immobilized. Finally, reconstitution assays showed that septin filaments mediate actin-membrane anchoring. We propose that septin organization as octamer-based filaments is essential for septin function in anchoring and stabilizing actin filaments at the plasma membrane.