Expression and Localization Profiles of Tight Junction Proteins in Immune Cells Depend on Their Activation Status.

The ability of the immune system to combat pathogens relies on processes like antigen sampling by dendritic cells and macrophages migrating through endo- and epithelia or penetrating them with their dendrites. In addition, other immune cell subtypes also migrate through the epithelium after activation. For paracellular migration, interactions with tight junctions (TJs) are necessary, and previous studies reported TJ protein expression in several immune cells. Our investigation aimed to characterize, in more detail, the expression profiles of TJ proteins in different immune cells in both naïve and activated states. The mRNA expression analysis revealed distinct expression patterns for TJ proteins, with notable changes, mainly increases, upon activation. At the protein level, LSR appeared predominant, being constitutively present in naïve cell membranes, suggesting roles as a crucial interaction partner. Binding experiments suggested the presence of claudins in the membrane only after stimulation, and claudin-8 translocation to the membrane occurred after stimulation. Our findings suggest a dynamic TJ protein expression in immune cells, implicating diverse functions in response to stimulation, like interaction with TJ proteins or regulatory roles. While further analysis is needed to elucidate the precise roles of TJ proteins, our findings indicate important non-canonical functions of TJ proteins in immune response.

Knock-out of dipeptidase CN2 in human proximal tubular cells disrupts dipeptide and amino acid homeostasis and para- and transcellular solute transport.

AIM: Although of potential biomedical relevance, dipeptide metabolism has hardly been studied. We found the dipeptidase carnosinase-2 (CN2) to be abundant in human proximal tubules, which regulate water and solute homeostasis. We therefore hypothesized, that CN2 has a key metabolic role, impacting proximal tubular transport function. METHODS: A knockout of the CN2 gene (CNDP2-KO) was generated in human proximal tubule cells and characterized by metabolomics, RNA-seq analysis, paracellular permeability analysis and ion transport. RESULTS: CNDP2-KO in human proximal tubule cells resulted in the accumulation of cellular dipeptides, reduction of amino acids and imbalance of related metabolic pathways, and of energy supply. RNA-seq analyses indicated altered protein metabolism and ion transport. Detailed functional studies demonstrated lower CNDP2-KO cell viability and proliferation, and altered ion and macromolecule transport via trans- and paracellular pathways. Regulatory and transport protein abundance was disturbed, either as a consequence of the metabolic imbalance or the resulting functional disequilibrium. CONCLUSION: CN2 function has a major impact on intracellular amino acid and dipeptide metabolism and is essential for key metabolic and regulatory functions of proximal tubular cells. These findings deserve in vivo analysis of the relevance of CN2 for nephron function and regulation of body homeostasis.

A Colonic Organoid Model Challenged with the Large Toxins of Clostridioides difficile TcdA and TcdB Exhibit Deregulated Tight Junction Proteins.

BACKGROUND: Clostridioides difficile toxins TcdA and TcdB are responsible for diarrhea and colitis. Lack of functional studies in organoid models of the gut prompted us to elucidate the toxin's effects on epithelial barrier function and the molecular mechanisms for diarrhea and inflammation. METHODS: Human adult colon organoids were cultured on membrane inserts. Tight junction (TJ) proteins and actin cytoskeleton were analyzed for expression via Western blotting and via confocal laser-scanning microscopy for subcellular localization. RESULTS: Polarized intestinal organoid monolayers were established from stem cell-containing colon organoids to apply toxins from the apical side and to perform functional measurements in the organoid model. The toxins caused a reduction in transepithelial electrical resistance in human colonic organoid monolayers with sublethal concentrations. Concomitantly, we detected increased paracellular permeability fluorescein and FITC-dextran-4000. Human colonic organoid monolayers exposed to the toxins exhibited redistribution of barrier-forming TJ proteins claudin-1, -4 and tricellulin, whereas channel-forming claudin-2 expression was increased. Perijunctional F-actin cytoskeleton organization was affected. CONCLUSIONS: Adult stem cell-derived human colonic organoid monolayers were applicable as a colon infection model for electrophysiological measurements. The TJ changes noted can explain the epithelial barrier dysfunction and diarrhea in patients, as well as increased entry of luminal antigens triggering inflammation.

Solving the Puzzle: Molecular Research in Inflammatory Bowel Diseases.

Inflammatory bowel disease (IBD) encompasses chronic idiopathic relapsing and remitting gastrointestinal autoimmune diseases characterized by chronic inflammatory disorders of complex etiology, posing clinical challenges due to their often therapy-refractory nature [...].

Myelin barrier breakdown, mechanical hypersensitivity, and painfulness in polyneuropathy with claudin-12 deficiency.

BACKGROUND: The blood-nerve and myelin barrier shield peripheral neurons and their axons. These barriers are sealed by tight junction proteins, which control the passage of potentially noxious molecules including proinflammatory cytokines via paracellular pathways. Peripheral nerve barrier breakdown occurs in various neuropathies, such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and traumatic neuropathy. Here, we studied the functional role of the tight junction protein claudin-12 in regulating peripheral nerve barrier integrity and CIDP pathogenesis. METHODS: Sections from sural nerve biopsies from 23 patients with CIDP and non-inflammatory idiopathic polyneuropathy (PNP) were analyzed for claudin-12 and -19 immunoreactivity. Cldn12-KO mice were generated and subjected to the chronic constriction injury (CCI) model of neuropathy. These mice were then characterized using a battery of barrier and behavioral tests, histology, immunohistochemistry, and mRNA/protein expression. In phenotype rescue experiments, the proinflammatory cytokine TNFα was neutralized with the anti-TNFα antibody etanercept; the peripheral nerve barrier was stabilized with the sonic hedgehog agonist smoothened (SAG). RESULTS: Compared to those without pain, patients with painful neuropathy exhibited reduced claudin-12 expression independently of fiber loss. Accordingly, global Cldn12-KO in male mice, but not fertile female mice, selectively caused mechanical allodynia associated with a leaky myelin barrier, increased TNFα, decreased sonic hedgehog (SHH), and loss of small axons accompanied by reduced peripheral myelin protein 22 (Pmp22). Other barriers and neurological functions remained intact. The Cldn12-KO phenotype could be rescued either by neutralizing TNFα with etanercept or stabilizing the barrier with SAG, which both also upregulated the Schwann cell barrier proteins Cldn19 and Pmp22. CONCLUSION: These results point to a critical role for claudin-12 in maintaining the myelin barrier presumably via Pmp22 and highlight restoration of the hedgehog pathway as a potential treatment strategy for painful inflammatory neuropathy.

Macromolecule Translocation across the Intestinal Mucosa of HIV-Infected Patients by Transcytosis and through Apoptotic Leaks.

Based on indirect evidence, increased mucosal translocation of gut-derived microbial macromolecules has been proposed as an important pathomechanism in HIV infection. Here, we quantified macromolecule translocation across intestinal mucosa from treatment-naive HIV-infected patients, HIV-infected patients treated by combination antiretroviral therapy, and HIV-negative controls and analyzed the translocation pathways involved. Macromolecule permeability was quantified by FITC-Dextran 4000 (FD4) and horseradish peroxidase (HRP) flux measurements. Translocation pathways were addressed using cold inhibition experiments. Tight junction proteins were characterized by immunoblotting. Epithelial apoptosis was quantified and translocation pathways were further characterized by flux studies in T84 cell monolayers using inducers and inhibitors of apoptosis and endocytosis. In duodenal mucosa of untreated but not treated HIV-infected patients, FD4 and HRP permeabilities were more than a 4-fold increase compared to the HIV-negative controls. Duodenal macromolecule permeability was partially temperature-dependent and associated with epithelial apoptosis without altered expression of the analyzed tight junction proteins. In T84 monolayers, apoptosis induction increased, and both apoptosis and endocytosis inhibitors reduced macromolecule permeability. Using quantitative analysis, we demonstrate the increased macromolecule permeability of the intestinal mucosa in untreated HIV-infected patients. Combining structural and mechanistic studies, we identified two pathways of increased macromolecule translocation in HIV infection: transcytosis and passage through apoptotic leaks.

Physical activity promotion in daycare centres in Germany: study protocol for a cross-sectional survey within the BeweKi study.

INTRODUCTION: In Germany, a total of 92.2% of children between the age of 3 and school entry age attend daycare centres. Therefore, daycare centres are a suitable setting to promote physical activity among children. Yet, there is a lack of knowledge on the promotion of physical activity in daycare centres with regards to different structures and concepts, culture/policies/practices and the characteristics of directors and pedagogical staff of daycare centres in Germany. The aim of this study is to investigate (a) the status quo, as well as (b) the fostering and hindering conditions (barriers and facilitators) of physical activity promotion in daycare centres in Germany. METHODS AND ANALYSIS: The cross-sectional study will collect data from November 2022 to February 2023. For the sample, about 5500 daycare centres will be drawn from an address database available through the German Youth Institute (DJI) and invited to the survey. From each daycare centre a director and a pedagogical staff member will be asked to fill in a standardised self-administered questionnaire. The survey explores characteristics of the daycare centre and the implementation of physical activity promotion, for example, the extent and form of physical activity promotion, the use and size of indoor and outdoor area, structural conditions such as personal and financial resources, personal attitudes towards physical activity promotion, demographic characteristics of pedagogical staff, structural daycare centre's characteristics such as proportion of children from socioeconomic disadvantaged groups. In addition, micro-geographical data on socioeconomic and infrastructural environment of the daycare centres will be included in the data set. ETHICS AND DISSEMINATION: The study has been received and approved by the Commissioner for Data Protection of the Robert Koch Institute and by the Ethics Committee of Alice Salomon Hochschule Berlin, University of Applied Sciences. Results will be disseminated through publications and presentations to scientific community and stakeholders.

Proteolytic Activity of the Paracaspase MALT1 Is Involved in Epithelial Restitution and Mucosal Healing.

The paracaspase MALT1 is a crucial regulator of immune responses in various cellular contexts. Recently, there is increasing evidence suggesting that MALT1 might represent a novel key player in mucosal inflammation. However, the molecular mechanisms underlying this process and the targeted cell population remain unclear. In this study, we investigate the role of MALT1 proteolytic activity in the context of mucosal inflammation. We demonstrate a significant enrichment of MALT1 gene and protein expression in colonic epithelial cells of UC patients, as well as in the context of experimental colitis. Mechanistically we demonstrate that MALT1 protease function inhibits ferroptosis, a form of iron-dependent cell death, upstream of NF-κB signaling, which can promote inflammation and tissue damage in IBD. We further show that MALT1 activity contributes to STAT3 signaling, which is essential for the regeneration of the intestinal epithelium after injury. In summary, our data strongly suggests that the protease function of MALT1 plays a critical role in the regulation of immune and inflammatory responses, as well as mucosal healing. Understanding the mechanisms by which MALT1 protease function regulates these processes may offer novel therapeutic targets for the treatment of IBD and other inflammatory diseases.

Oncogenic signaling is coupled to colorectal cancer cell differentiation state.

Colorectal cancer progression is intrinsically linked to stepwise deregulation of the intestinal differentiation trajectory. In this process, sequential mutations of APC, KRAS, TP53, and SMAD4 enable oncogenic signaling and establish the hallmarks of cancer. Here, we use mass cytometry of isogenic human colon organoids and patient-derived cancer organoids to capture oncogenic signaling, cell phenotypes, and differentiation states in a high-dimensional single-cell map. We define a differentiation axis in all tumor progression states from normal to cancer. Our data show that colorectal cancer driver mutations shape the distribution of cells along the differentiation axis. In this regard, subsequent mutations can have stem cell promoting or restricting effects. Individual nodes of the cancer cell signaling network remain coupled to the differentiation state, regardless of the presence of driver mutations. We use single-cell RNA sequencing to link the (phospho-)protein signaling network to transcriptomic states with biological and clinical relevance. Our work highlights how oncogenes gradually shape signaling and transcriptomes during tumor progression.

ZO-1 Guides Tight Junction Assembly and Epithelial Morphogenesis via Cytoskeletal Tension-Dependent and -Independent Functions.

Formation and maintenance of tissue barriers require the coordination of cell mechanics and cell-cell junction assembly. Here, we combined methods to modulate ECM stiffness and to measure mechanical forces on adhesion complexes to investigate how tight junctions regulate cell mechanics and epithelial morphogenesis. We found that depletion of the tight junction adaptor ZO-1 disrupted junction assembly and morphogenesis in an ECM stiffness-dependent manner and led to a stiffness-dependant reorganisation of active myosin. Both junction formation and morphogenesis were rescued by inhibition of actomyosin contractility. ZO-1 depletion also impacted mechanical tension at cell-matrix and E-cadherin-based cell-cell adhesions. The effect on E-cadherin also depended on ECM stiffness and correlated with effects of ECM stiffness on actin cytoskeleton organisation. However, ZO-1 knockout also revealed tension-independent functions of ZO-1. ZO-1-deficient cells could assemble functional barriers at low tension, but their tight junctions remained corrupted with strongly reduced and discontinuous recruitment of junctional components. Our results thus reveal that reciprocal regulation between ZO-1 and cell mechanics controls tight junction assembly and epithelial morphogenesis, and that, in a second, tension-independent step, ZO-1 is required to assemble morphologically and structurally fully assembled and functionally normal tight junctions.

How much do adults sit? Results from the German Health Update (GEDA 2019/2020-EHIS).

Background: Sedentary behaviour is increasingly perceived as a risk factor for the development of diseases and for increased mortality. In particular, increased time spent sitting in combination with low physical activity seems to have negative health consequences. Methods: In the nationwide cross-sectional study German Health Update (GEDA 2019/2020-EHIS), the indicator 'sitting' was captured by the self-report of the participants. Results: For at least eight hours a day, 16.7% of women and 22.3% of men sit: Men more often than women, younger persons more often than older persons and the proportion increases significantly from the low to the high education group. Similarly, about one fifth of adults in Germany sit for at least four hours a day and do not engage in physical activity in their leisure time. Conclusion: The results indicate that preventive measures are needed to reduce time spent sitting and increase physical activity.

Tight junction channels claudin-10b and claudin-15: Functional mapping of pore-lining residues.

Although functional and structural models for paracellular channels formed by claudins have been reported, mechanisms regulating charge and size selectivity of these channels are unknown in detail. Here, claudin-15 and claudin-10b cation channels showing high-sequence similarity but differing channel properties were analyzed. Mutants of pore-lining residues were expressed in MDCK-C7 cells. In claudin-15, proposed ion interaction sites (D55 and E64) conserved between both claudins were neutralized. D55N and E64Q substitutions decreased ion permeabilities, and D55N/E64Q had partly additive effects. D55N increased cation dehydration capability and decreased pore diameter. Additionally, residues differing between claudin-15 and -10b close to pore center were analyzed. Claudin-10b-mimicking W63K affected neither assembly nor function of claudin-15 channels. In contrast, in claudin-10b, corresponding (claudin-15b-mimicking) K64W and K64M substitutions disturbed integration into tight junction and slightly altered relative permeabilities for differently sized monovalent cations. Removal of claudin-10b-specific negative charge (D36A substitution) was without effect. The data suggest that a common tetra-aspartate ring (D55/D56) in pore center of claudin-15/-10b channels directly attracts cations, while E64/D65 may be at least partly shielded by W63/K64. Charge at position W63/K64 affects assembly and properties for claudin-10b but not for claudin-15 channels. Our findings add to the mechanistic understanding of the determinants of paracellular cation permeability.

MicroRNA-21-5p functions via RECK/MMP9 as a proalgesic regulator of the blood nerve barrier in nerve injury.

Both nerve injury and complex regional pain syndrome (CRPS) can result in chronic pain. In traumatic neuropathy, the blood nerve barrier (BNB) shielding the nerve is impaired-partly due to dysregulated microRNAs (miRNAs). Upregulation of microRNA-21-5p (miR-21) has previously been documented in neuropathic pain, predominantly due to its proinflammatory features. However, little is known about other functions. Here, we characterized miR-21 in neuropathic pain and its impact on the BNB in a human-murine back translational approach. MiR-21 expression was elevated in plasma of patients with CRPS as well as in nerves of mice after transient and persistent nerve injury. Mice presented with BNB leakage, as well as loss of claudin-1 in both injured and spared nerves. Moreover, the putative miR-21 target RECK was decreased and downstream Mmp9 upregulated, as was Tgfb. In vitro experiments in human epithelial cells confirmed a downregulation of CLDN1 by miR-21 mimics via inhibition of the RECK/MMP9 pathway but not TGFB. Perineurial miR-21 mimic application in mice elicited mechanical hypersensitivity, while local inhibition of miR-21 after nerve injury reversed it. In summary, the data support a novel role for miR-21, independent of prior inflammation, in elicitation of pain and impairment of the BNB via RECK/MMP9.

Human duodenal organoid-derived monolayers serve as a suitable barrier model for duodenal tissue.

Usually, duodenal barriers are investigated using intestinal cell lines like Caco-2, which in contrast to native tissue are limited in cell-type representation. Organoids can consist of all intestinal cell types and are supposed to better reflect the in vivo situation. Growing three-dimensionally, with the apical side facing the lumen, application of typical physiological techniques to analyze the barrier is difficult. Organoid-derived monolayers (ODMs) were developed to overcome this. After optimizing culturing conditions, ODMs were characterized and compared to Caco-2 and duodenal tissue. Tight junction composition and appearance were analyzed, and electrophysiological barrier properties, like paracellular and transcellular barrier function and macromolecule permeability, were evaluated. Furthermore, transcriptomic data were analyzed. ODMs had tight junction protein expression and paracellular barrier properties much more resembling the originating tissue than Caco-2. Transcellular barrier was similar between ODMs and native tissue but was increased in Caco-2. Transcriptomic data showed that Caco-2 expressed fewer solute carriers than ODMs and native tissue. In conclusion, while Caco-2 cells differ mostly in transcellular properties, ODMs reflect trans- and paracellular properties of the originating tissue. If cultured under optimized conditions, ODMs possess reproducible functionality, and the variety of different cell types makes them a suitable model for human tissue-specific investigations.

MarvelD3 Is Upregulated in Ulcerative Colitis and Has Attenuating Effects during Colitis Indirectly Stabilizing the Intestinal Barrier.

In inflammatory bowel disease (IBD), the impaired intestinal barrier is mainly characterized by changes in tight junction protein expression. The functional role of the tight junction-associated MARVEL protein MARVELD3 (MD3) in IBD is yet unknown. (i) In colon biopsies from IBD patients we analyzed MD3 expression and (ii) in human colon HT-29/B6 cells we studied the signaling pathways of different IBD-relevant cytokines. (iii) We generated a mouse model with intestinal overexpression of MD3 and investigated functional effects of MD3 upregulation. Colitis, graded by the disease activity index, was induced by dextran sodium sulfate (DSS) and the intestinal barrier was characterized electrophysiologically. MD3 was upregulated in human ulcerative colitis and MD3 expression could be increased in HT-29/B6 cells by IL-13 via the IL13Rα1/STAT pathway. In mice DSS colitis, MD3 overexpression had an ameliorating, protective effect. It was not based on direct enhancement of paracellular barrier properties, but rather on regulatory mechanisms not solved yet in detail. However, as MD3 is involved in regulatory functions such as proliferation and cell survival, we conclude that the protective effects are hardly targeting the intestinal barrier directly but are based on regulatory processes supporting stabilization of the intestinal barrier.

From 3D to 2D: Harmonization of Protocols for Two-dimensional Cultures on Cell Culture Inserts of Intestinal Organoids from Various Species.

In the expanding field of intestinal organoid research, various protocols for three- and two-dimensional organoid-derived cell cultures exist. Two-dimensional organoid-derived monolayers are used to overcome some limitations of three-dimensional organoid cultures. They are increasingly used also in infection research, to study physiological processes and tissue barrier functions, where easy experimental access of pathogens to the luminal and/or basolateral cell surface is required. This has resulted in an increasing number of publications reporting different protocols and media compositions for organoid manipulation, precluding direct comparisons of research outcomes in some cases. With this in mind, here we describe a protocol aimed at the harmonization of seeding conditions for three-dimensional intestinal organoids of four commonly used research species onto cell culture inserts, to create organoid-derived monolayers that form electrophysiologically tight epithelial barriers. We give an in-depth description of media compositions and culture conditions for creating these monolayers, enabling also the less experienced researchers to obtain reproducible results within a short period of time, and which should simplify the comparison of future studies between labs, but also encourage others to consider these systems as alternative cell culture models in their research. Graphic abstract: Schematic workflow of organoid-derived monolayer generation from intestinal spheroid cultures. ECM, extracellular matrix; ODM, organoid-derived monolayer.

Claudin-10a Deficiency Shifts Proximal Tubular Cl- Permeability to Cation Selectivity via Claudin-2 Redistribution.

BACKGROUND: The tight junction proteins claudin-2 and claudin-10a form paracellular cation and anion channels, respectively, and are expressed in the proximal tubule. However, the physiologic role of claudin-10a in the kidney has been unclear. METHODS: To investigate the physiologic role of claudin-10a, we generated claudin-10a-deficient mice, confirmed successful knockout by Southern blot, Western blot, and immunofluorescence staining, and analyzed urine and serum of knockout and wild-type animals. We also used electrophysiologic studies to investigate the functionality of isolated proximal tubules, and studied compensatory regulation by pharmacologic intervention, RNA sequencing analysis, Western blot, immunofluorescence staining, and respirometry. RESULTS: Mice deficient in claudin-10a were fertile and without overt phenotypes. On knockout, claudin-10a was replaced by claudin-2 in all proximal tubule segments. Electrophysiology showed conversion from paracellular anion preference to cation preference and a loss of paracellular Cl- over HCO3- preference. As a result, there was tubular retention of calcium and magnesium, higher urine pH, and mild hypermagnesemia. A comparison with other urine and serum parameters under control conditions and sequential pharmacologic transport inhibition, and unchanged fractional lithium excretion, suggested compensative measures in proximal and distal tubular segments. Changes in proximal tubular oxygen handling and differential expression of genes regulating fatty acid metabolism indicated proximal tubular adaptation. Western blot and immunofluorescence revealed alterations in distal tubular transport. CONCLUSIONS: Claudin-10a is the major paracellular anion channel in the proximal tubule and its deletion causes calcium and magnesium hyper-reabsorption by claudin-2 redistribution. Transcellular transport in proximal and distal segments and proximal tubular metabolic adaptation compensate for loss of paracellular anion permeability.

Dissection of Barrier Dysfunction in Organoid-Derived Human Intestinal Epithelia Induced by Giardia duodenalis.

BACKGROUND & AIMS: The protozoa Giardia duodenalis is a major cause of gastrointestinal illness worldwide, but underlying pathophysiological mechanisms remain obscure, partly due to the absence of adequate cellular models. We aimed at overcoming these limitations and recapitulating the authentic series of pathogenic events in the primary human duodenal tissue by using the human organoid system. METHODS: We established a compartmentalized cellular transwell system with electrophysiological and barrier properties akin to duodenal mucosa and dissected the events leading to G. duodenalis-induced barrier breakdown by functional analysis of transcriptional, electrophysiological, and tight junction components. RESULTS: Organoid-derived cell layers of different donors showed a time- and parasite load-dependent leak flux indicated by collapse of the epithelial barrier upon G. duodenalis infection. Gene set enrichment analysis suggested major expression changes, including gene sets contributing to ion transport and tight junction structure. Solute carrier family 12 member 2 and cystic fibrosis transmembrane conductance regulator-dependent chloride secretion was reduced early after infection, while changes in the tight junction composition, localization, and structural organization occurred later as revealed by immunofluorescence analysis and freeze fracture electron microscopy. Functionally, barrier loss was linked to the adenosine 3',5'-cyclic monophosphate (cAMP)/protein kinase A-cAMP response element-binding protein signaling pathway. CONCLUSIONS: Data suggest a previously unknown sequence of events culminating in intestinal barrier dysfunction upon G. duodenalis infection during which alterations of cellular ion transport were followed by breakdown of the tight junctional complex and loss of epithelial integrity, events involving a cAMP/protein kinase A-cAMP response element-binding protein mechanism. These findings and the newly established organoid-derived model to study G. duodenalis infection may help to explore new options for intervening with disease and infection, in particular relevant for chronic cases of giardiasis.

Change in sports activity and walking and cycling for transport since the COVID-19 pandemic - Results of the GEDA 2021 study.

Background: Physical activity is a significant health promotion behaviour. COVID-19 pandemic mitigation measures, such as reducing social contact, closing sports facilities and working from home offices, may make it more difficult to engage in regular physical activity. Methods: The data collected between July and October 2021 from the nationally representative study German Health Update (GEDA 2021) were used. The activity behaviour is described by the change in the amount of sports activity as well as the amount of physical active transport (walking/cycling) since the beginning of the COVID-19 pandemic. The sample comprises 2,985 participants aged 18 and older. Results: A quarter of the population reduced their sports activity compared to before the COVID-19 pandemic, while 12% increased their sports activity and 38% reported no change. In terms of physical active transport, it shows that 15% reduced the amount, 17% increased it and 55% maintained it. Compared to younger adults, older adults were more likely to maintain their activity behaviour rather than reduce or increase it. Conclusion: Even before the pandemic, physical inactivity was common among the population. The high proportion of adults who reduced their sports activity during the pandemic underlines the need for effective measures to promote physical activity.