Phloretin enhances remyelination by stimulating oligodendrocyte precursor cell differentiation.

Failure of remyelination underlies the progressive nature of demyelinating diseases such as multiple sclerosis. Why endogenous repair mechanisms frequently fail in these disorders is poorly understood. However, there is now evidence indicating that this is related to an overly inflammatory microenvironment combined with the intrinsic inability of oligodendrocyte precursor cells (OPCs) to differentiate into mature myelinating cells. Previously, we found that phloretin, a flavonoid abundantly present in apples and strawberries, reduces neuroinflammation by driving macrophages toward an antiinflammatory phenotype. Here, we show that phloretin also markedly stimulates remyelination in ex vivo and in vivo animal models. Improved remyelination was attributed to a direct impact of phloretin on OPC maturation and occurred independently from alterations in microglia function and inflammation. We found, mechanistically, that phloretin acts as a direct ligand for the fatty acid sensing nuclear receptor peroxisome proliferator-activated receptor gamma, thereby promoting the maturation of OPCs. Together, our findings indicate that phloretin has proregenerative properties in central nervous system disorders, with potentially broad implications for the development of therapeutic strategies and dietary interventions aimed at promoting remyelination.

Safety and outcomes of thrombolytic therapy in patients with pulmonary embolism and thrombocytopenia: A systematic review.

Thrombolysis is an established therapeutic modality for patients with high-risk (and some selected intermediate-risk) pulmonary embolism (PE) with hemodynamic instability. Physicians sometimes experience cases where both a high-risk PE and thrombocytopenia coexist. Although thrombocytopenia of <  100 × 103/mm3 is considered a contraindication in patients with ischemic stroke, the safety and outcomes of thrombolysis in patients with acute PE and thrombocytopenia are unknown. This systemic review aimed to pool data on the safety and outcomes of thrombolysis use in patients with PE and platelet count less than 150 × 103/mm3. Patients' demographics, clinical characteristics, management, type of thrombolytic therapy, and outcomes were extracted and analyzed. Of 283 articles identified through the systematic search, 11 case reports fulfilled the inclusion criteria. The mean age of the patients was 52.27 years, and 54.5% were women. The median platelet level before thrombolysis was 65.50 × 103/mm3. Before thrombolysis was initiated, the lowest and highest platelet levels were 29 × 103/mm3 and 105 × 103/mm3, respectively. Alteplase was used in 10 patients and urokinase in one patient. One patient who had a massive PE died of aspiration pneumonia. Interestingly, no thrombocytopenia-related complications were reported. This systematic review highlights the potential benefits and safety of thrombolysis in patients with acute PE in the context of thrombocytopenia. Nevertheless, data available in the literature concerning this topic are scarce and limited to case reports. More extensive studies on the use of thrombolysis in patients with PE and thrombocytopenia are desperately needed. Systematic review registration: The protocol has been registered in the International Prospective Register of Systematic Reviews (PROSPERO): CRD42021286415.

Assessing the effect of nicotine dose in cigarette smoking on sleep quality.

BACKGROUND: While several studies assessed the relation between cigarette smoking and sleep, there are still very few studies assessing the effect of nicotine in cigarette smoking on sleep. AIM: This study aimed to compare higher vs lower nicotine levels in cigarette smoking on sleep quality. METHODS: We used data from the recently released dataset for the Randomized Trial of Reduced-Nicotine Standards for Cigarettes. We included three groups in the current study: the least nicotine concentration (i.e., 0.4 mg/g), a moderate nicotine concentration (i.e., 5.2 mg/g), and the highest nicotine concentration (i.e., 15.8 mg/g). For each participant, we included data regarding baseline and the last follow up at 6 weeks, where we compared insomnia, sleep problems, and awakening at night, in addition to different depression and affect scores. RESULTS: A total of 360 patients were included in this study, with a mean age of 42.4 (±13.4) years. For the three nicotine groups (i.e., 0.4 mg/g, 5.2 mg/g, and 15.8 mg/g), we included 119 (33%), 122 (34%), and 119 (33%) participants. Among the high-nicotine-dose group, the number of participants who had worsened sleep was significantly higher than the number of those who had improved sleep (p = 0.01) after 6 weeks of consumption, where 37 (31%) had worsened sleep score after 6 weeks while only 19 (16%) had improved score compared with baseline. CONCLUSION: While previous studies established a relation either between cigarette smoking and sleep or between nicotine patches and sleep, the present study is the first to establish that higher nicotine doses in cigarettes were associated with more sleep disturbances.

Assessment of final-year medical students' performance in diagnosing critical findings on chest X-ray.

PURPOSE: Due to the recently emerging shortage in medical staff during the novel corona virus pandemic, several countries have rushed their undergraduate medical students into the emergency department. The accuracy of diagnosing critical findings on X-rays by senior medical students is not well assessed. In this study, we aim to assess the knowledge and accuracy of undergraduate final-year medical students in diagnosing life-threatening emergency conditions on chest x-ray. METHOD: This is a cross-sectional nationwide survey across all medical schools in Jordan. Through an electronic questionnaire, participants were sequentially shown a total of six abnormal X-rays and one normal. For each X-ray, participants were asked to choose the most likely diagnosis, and to grade the degree of self-confidence regarding the accuracy of their answer in a score from 0 (not confident) to 10 (very confident). RESULTS: We included a total of 530 participants. All participants answered at least six out of seven questions correctly, out of them, 139 (26.2%) participants answered all questions correctly. Pneumoperitoneum was the highest correct answer (93.8%), whereas flail chest was the least correctly answered case with only 310 (58.5%) correct answers. Regarding self-confidence for each question, 338 participants (63.8%) reported very high overall self-confidence level. Answers related to tension pneumothorax had the highest confidence level. CONCLUSION: Senior Jordanian medical students showed good knowledge with high confidence levels in diagnosing life-threatening conditions on chest x-rays, supporting their incorporation in the emergency department during pandemics and confirming the reliability of information they can extract.

Wild gorillas as a potential reservoir of Leishmania major.

Vector-borne parasites of the genus Leishmania are responsible for severe human diseases. Cutaneous leishmaniasis, a common form of the disease, is most often caused by the transmission of Leishmania major to humans by female phlebotomine sand flies. Apes are increasingly being seen as a source of zoonotic diseases, including malaria and rickettsiosis. To examine whether gorillas harbor Leishmania species, we screened fecal samples from wild western lowland gorillas (Gorilla gorilla gorilla) in Cameroon for the presence of these pathogens. Of 91 wild gorilla fecal samples, 12 contained Leishmania parasites, and 4 contained phlebotomine sand fly vectors. The molecular identity was determined by running 3 different polymerase chain reaction tests for detection of L. major. Next, fluorescence in situ hybridization was performed to visualize L. major parasites in fecal samples from the gorillas. Both promastigote and amastigote forms of the parasite were found. This work strongly suggests that wild gorillas carry pathogenic Leishmania parasites.

Looking in apes as a source of human pathogens.

Because of the close genetic relatedness between apes and humans, apes are susceptible to many human infectious agents and can serve as carriers of these pathogens. Consequently, they present a serious health hazard to humans. Moreover, many emerging infectious diseases originate in wildlife and continue to threaten human populations, especially vector-borne diseases described in great apes, such as malaria and rickettsiosis. These wild primates may be permanent reservoirs and important sources of human pathogens. In this special issue, we report that apes, including chimpanzees (Pan troglodytes), bonobos (Pan paniscus), gorillas (Gorilla gorilla and Gorilla beringei), orangutans (Pongo pygmaeus and Pongo abelii), gibbons (Hylobates spp., Hoolock spp. and Nomascus spp) and siamangs (Symphalangus syndactylus syndactylus and Symphalangus continentis), have many bacterial, viral, fungal and parasitic species that are capable of infecting humans. Serious measures should be adopted in tropical forests and sub-tropical areas where habitat overlaps are frequent to survey and prevent infectious diseases from spreading from apes to people.

Impact of liver biopsy on the decision to treat patients with chronic hepatitis B genotype D virus infection.

OBJECTIVES: Patients with chronic hepatitis B virus (HBV) may exhibit significant liver pathology despite alanine aminotransferase (ALT) and HBV DNA levels below the cutoff values advised by treatment guidelines. We evaluated candidacy for HBV therapy when baseline histopathological changes are taken into consideration. METHODS: Clinical, biochemical, serological, virological, and histopathological (METAVIR score) data of 117 patients with HBeAg-negative chronic HBV genotype D were collected and analyzed. RESULTS: Significant pathology (≥F2 and/or ≥A2) and fibrosis (≥F2 ± ≥A2) were found in 73 (62.4%) and 59 (50.4%) patients, respectively. Based on HBV DNA (>2,000 IU/ml) and ALT levels >2 × 40 U/l (the standard cutoff value), only 31 (26.5%) patients were candidates for therapy. This increased to 58 (49.6%) patients when the new ALT cutoff values (30 U/l for males, and 19 U/l for females) were applied. Relying on either ≥F2 and/or A ≥2 or ≥F2 ± ≥A2 increases the treatment candidacy to 73 (62.4%) and 59 (50.4%) patients, respectively. Also, when compared with standard ALT cutoff values, applying both new ALT cutoff values with either significant pathology or fibrosis increases treatment candidacy to 28 (23.9%) and 42 (35.9%) patients, respectively. CONCLUSION: Liver pathology is more reliable than ALT and HBV DNA in the decision to treat patients with HBeAg-negative chronic HBV genotype D.

Cortactin is in a complex with VE-cadherin and is required for endothelial adherens junction stability through Rap1/Rac1 activation.

Vascular permeability is mediated by Cortactin (Cttn) and regulated by several molecules including cyclic-adenosine-monophosphate, small Rho family GTPases and the actin cytoskeleton. However, it is unclear whether Cttn directly interacts with any of the junctional components or if Cttn intervenes with signaling pathways affecting the intercellular contacts and the cytoskeleton. To address these questions, we employed immortalized microvascular myocardial endothelial cells derived from wild-type and Cttn-knock-out mice. We found that lack of Cttn compromised barrier integrity due to fragmented membrane distribution of different junctional proteins. Moreover, immunoprecipitations revealed that Cttn is within the VE-cadherin-based adherens junction complex. In addition, lack of Cttn slowed-down barrier recovery after Ca2+ repletion. The role of Cttn for cAMP-mediated endothelial barrier regulation was analyzed using Forskolin/Rolipram. In contrast to Cttn-KO, WT cells reacted with increased transendothelial electrical resistance. Absence of Cttn disturbed Rap1 and Rac1 activation in Cttn-depleted cells. Surprisingly, despite the absence of Cttn, direct activation of Rac1/Cdc42/RhoA by CN04 increased barrier resistance and induced well-defined cortical actin and intracellular actin bundles. In summary, our data show that Cttn is required for basal barrier integrity by allowing proper membrane distribution of junctional proteins and for cAMP-mediated activation of the Rap1/Rac1 signaling pathway.

Rapamycin rescues loss of function in blood-brain barrier-interacting Tregs.

In autoimmunity, FOXP3+ Tregs skew toward a proinflammatory, nonsuppressive phenotype and are, therefore, unable to control the exaggerated autoimmune response. This largely affects the success of autologous Treg therapy, which is currently under investigation for autoimmune diseases, including multiple sclerosis (MS). There is a need to ensure in vivo Treg stability before successful application of Treg therapy. Using genetic fate-mapping mice, we demonstrate that inflammatory, cytokine-expressing exFOXP3 T cells accumulate in the CNS during experimental autoimmune encephalomyelitis. In a human in vitro model, we discovered that interaction with inflamed blood-brain barrier endothelial cells (BBB-ECs) induces loss of function by Tregs. Transcriptome and cytokine analysis revealed that in vitro migrated Tregs have disrupted regenerative potential and a proinflammatory Th1/17 signature, and they upregulate the mTORC1 signaling pathway. In vitro treatment of migrated human Tregs with the clinically approved mTORC1 inhibitor rapamycin restored suppression. Finally, flow cytometric analysis indicated an enrichment of inflammatory, less-suppressive CD49d+ Tregs in the cerebrospinal fluid of people with MS. In summary, interaction with BBB-ECs is sufficient to affect Treg function, and transmigration triggers an additive proinflammatory phenotype switch. These insights help improve the efficacy of autologous Treg therapy of MS.

Pyridoxamine Limits Cardiac Dysfunction in a Rat Model of Doxorubicin-Induced Cardiotoxicity.

The use of doxorubicin (DOX) chemotherapy is restricted due to dose-dependent cardiotoxicity. Pyridoxamine (PM) is a vitamin B6 derivative with favorable effects on diverse cardiovascular diseases, suggesting a cardioprotective effect on DOX-induced cardiotoxicity. The cardioprotective nature of PM was investigated in a rat model of DOX-induced cardiotoxicity. Six-week-old female Sprague Dawley rats were treated intravenously with 2 mg/kg DOX or saline (CTRL) weekly for eight weeks. Two other groups received PM via the drinking water next to DOX (DOX+PM) or saline (CTRL+PM). Echocardiography, strain analysis, and hemodynamic measurements were performed to evaluate cardiac function. Fibrotic remodeling, myocardial inflammation, oxidative stress, apoptosis, and ferroptosis were evaluated by various in vitro techniques. PM significantly attenuated DOX-induced left ventricular (LV) dilated cardiomyopathy and limited TGF-ß1-related LV fibrotic remodeling and macrophage-driven myocardial inflammation. PM protected against DOX-induced ferroptosis, as evidenced by restored DOX-induced disturbance of redox balance, improved cytosolic and mitochondrial iron regulation, and reduced mitochondrial damage at the gene level. In conclusion, PM attenuated the development of cardiac damage after DOX treatment by reducing myocardial fibrosis, inflammation, and mitochondrial damage and by restoring redox and iron regulation at the gene level, suggesting that PM may be a novel cardioprotective strategy for DOX-induced cardiomyopathy.

Impact of High Salt-Intake on a Natural Gut Ecosystem in Wildling Mice.

The mammalian holobiont harbors a complex and interdependent mutualistic gut bacterial community. Shifts in the composition of this bacterial consortium are known to be a key element in host health, immunity and disease. Among many others, dietary habits are impactful drivers for a potential disruption of the bacteria-host mutualistic interaction. In this context, we previously demonstrated that a high-salt diet (HSD) leads to a dysbiotic condition of murine gut microbiota, characterized by a decrease or depletion of well-known health-promoting gut bacteria. However, due to a controlled and sanitized environment, conventional laboratory mice (CLM) possess a less diverse gut microbiota compared to wild mice, leading to poor translational outcome for gut microbiome studies, since a reduced gut microbiota diversity could fail to depict the complex interdependent networks of the microbiome. Here, we evaluated the HSD effect on gut microbiota in CLM in comparison to wildling mice, which harbor a natural gut ecosystem more closely mimicking the situation in humans. Mice were treated with either control food or HSD and gut microbiota were profiled using amplicon-based methods targeting the 16S ribosomal gene. In line with previous findings, our results revealed that HSD induced significant loss of alpha diversity and extensive modulation of gut microbiota composition in CLM, characterized by the decrease in potentially beneficial bacteria from Firmicutes phylum such as the genera Lactobacillus, Roseburia, Tuzzerella, Anaerovorax and increase in Akkermansia and Parasutterella. However, HSD-treated wildling mice did not show the same changes in terms of alpha diversity and loss of Firmicutes bacteria as CLM, and more generally, wildlings exhibited only minor shifts in the gut microbiota composition upon HSD. In line with this, 16S-based functional analysis suggested only major shifts of gut microbiota ecological functions in CLM compared to wildling mice upon HSD. Our findings indicate that richer and wild-derived gut microbiota is more resistant to dietary interventions such as HSD, compared to gut microbiota of CLM, which may have important implications for future translational microbiome research.

Effects of Recombinant IL-13 Treatment on Gut Microbiota Composition and Functional Recovery after Hemisection Spinal Cord Injury in Mice.

In recent years, the gut-central nervous system axis has emerged as a key factor in the pathophysiology of spinal cord injury (SCI). Interleukin-13 (IL-13) has been shown to have anti-inflammatory and neuroprotective effects in SCI. The aim of this study was to investigate the changes in microbiota composition after hemisection injury and to determine whether systemic recombinant (r)IL-13 treatment could alter the gut microbiome, indirectly promoting functional recovery. The gut microbiota composition was determined by 16S rRNA gene sequencing, and correlations between gut microbiota alterations and functional recovery were assessed. Our results showed that there were no changes in alpha diversity between the groups before and after SCI, while PERMANOVA analysis for beta diversity showed significant differences in fecal microbial communities. Phylogenetic classification of bacterial families revealed a lower abundance of the Bacteroidales S24-7 group and a higher abundance of Lachnospiraceae and Lactobacillaceae in the post-SCI group. Systemic rIL-13 treatment improved functional recovery 28 days post-injury and microbiota analysis revealed increased relative abundance of Clostridiales vadin BB60 and Acetitomaculum and decreased Anaeroplasma, Ruminiclostridium_6, and Ruminococcus compared to controls. Functional assessment with PICRUSt showed that genes related to glyoxylate cycle and palmitoleate biosynthesis-I were the predominant signatures in the rIL-13-treated group, whereas sulfolactate degradation super pathway and formaldehyde assimilation-I were enriched in controls. In conclusion, our results indicate that rIL-13 treatment promotes changes in gut microbial communities and may thereby contribute indirectly to the improvement of functional recovery in mice, possibly having important implications for the development of novel treatment options for SCI.

Fatty acid desaturation by stearoyl-CoA desaturase-1 controls regulatory T cell differentiation and autoimmunity.

The imbalance between pathogenic and protective T cell subsets is a cardinal feature of autoimmune disorders such as multiple sclerosis (MS). Emerging evidence indicates that endogenous and dietary-induced changes in fatty acid metabolism have a major impact on both T cell fate and autoimmunity. To date, however, the molecular mechanisms that underlie the impact of fatty acid metabolism on T cell physiology and autoimmunity remain poorly understood. Here, we report that stearoyl-CoA desaturase-1 (SCD1), an enzyme essential for the desaturation of fatty acids and highly regulated by dietary factors, acts as an endogenous brake on regulatory T-cell (Treg) differentiation and augments autoimmunity in an animal model of MS in a T cell-dependent manner. Guided by RNA sequencing and lipidomics analysis, we found that the absence of Scd1 in T cells promotes the hydrolysis of triglycerides and phosphatidylcholine through adipose triglyceride lipase (ATGL). ATGL-dependent release of docosahexaenoic acid enhanced Treg differentiation by activating the nuclear receptor peroxisome proliferator-activated receptor gamma. Our findings identify fatty acid desaturation by SCD1 as an essential determinant of Treg differentiation and autoimmunity, with potentially broad implications for the development of novel therapeutic strategies and dietary interventions for autoimmune disorders such as MS.

Sodium perturbs mitochondrial respiration and induces dysfunctional Tregs.

FOXP3+ regulatory T cells (Tregs) are central for peripheral tolerance, and their deregulation is associated with autoimmunity. Dysfunctional autoimmune Tregs display pro-inflammatory features and altered mitochondrial metabolism, but contributing factors remain elusive. High salt (HS) has been identified to alter immune function and to promote autoimmunity. By investigating longitudinal transcriptional changes of human Tregs, we identified that HS induces metabolic reprogramming, recapitulating features of autoimmune Tregs. Mechanistically, extracellular HS raises intracellular Na+, perturbing mitochondrial respiration by interfering with the electron transport chain (ETC). Metabolic disturbance by a temporary HS encounter or complex III blockade rapidly induces a pro-inflammatory signature and FOXP3 downregulation, leading to long-term dysfunction in vitro and in vivo. The HS-induced effect could be reversed by inhibition of mitochondrial Na+/Ca2+ exchanger (NCLX). Our results indicate that salt could contribute to metabolic reprogramming and that short-term HS encounter perturb metabolic fitness and long-term function of human Tregs with important implications for autoimmunity.

Relationship of the lumbar lordosis angle to the abdominal aortic bifurcation and inferior vena cava confluence levels.

The objective of this study is to determine the relationship of the variations of the lumbar lordosis angle (LLA) to the aortic bifurcation level and inferior vena cava (IVC) confluence level using CT angiography. A retrospective study was conducted using the data available on abdominopelvic CT angiography scans. The LLA, the level and angle of bifurcation of the aorta, the level and angle of confluence of the IVC were identified using multiplanar and 3D reconstruction. Linear regression models were fitted to the data. We interpreted 181 scans for 181 individuals having a mean age of 55 years (18-89). The most common site of aortic bifurcation was at L4-L5 disc space (34.8%) and that of vena confluence was at the upper of L5 (29.3%). The mean LLA was 34.65° (13°-77°). The mean aortic bifurcation angle was 47.43° (17°-100°) and the mean IVC confluence angle was 71.86° (30°-120°). The positions of the aortic bifurcation and venous confluence levels showed a proximal shift with an increasing LLA P < 0.001. This study showed that the level of bifurcation of the aorta and the level of confluence of the IVC may vary with the variations of the LLA.

Vitiligo-Like Lesions in a Patient with Metastatic Breast Cancer Treated with Cyclin-Dependent Kinase (CDK) 4/6 Inhibitor: A Case Report and Literature Review.

BACKGROUND: Cyclin-dependent kinase (CDK) 4/6 inhibitors have revolutionized the treatment landscape of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer, with an impressive efficacy and safety profile. Cytopenia is the main adverse event, which is both predictable and manageable. Here, we report a case of CDK4/6 inhibitor-induced vitiligo-like lesions. Vitiligo or vitiligo-like lesions are a rare adverse event; only a few cases are reported in the literature. CASE PRESENTATION: A 71-year-old female patient was diagnosed initially with early-stage right breast cancer (HR+/HER2-) and was treated with breast-conserving surgery followed by chemotherapy, radiotherapy, and hormonal therapy. A few years later, she developed metastatic disease to the hilar lymph nodes, and to multiple skeletal sites, including the left scapula, left shoulder, left iliac bone, and dorsal vertebrae, for which she was treated with ribociclib and letrozole. While on treatment, she developed hypopigmented lesions involving both hands, feet, and face, which were described as vitiligo-like lesions. CONCLUSION: CDK4/6 inhibitor-induced vitiligo is a rare and unpredictable adverse event. This case report highlights the rarity of this adverse event, the dilemma related to the optimal treatment, and decisions related to continuation, holding, or switching CDK4/6 inhibitors.

High-Salt Diet Induces Depletion of Lactic Acid-Producing Bacteria in Murine Gut.

Dietary habits are amongst the main factors that influence the gut microbiome. Accumulating evidence points to the impact of a high-salt diet (HSD) on the composition and function of the intestinal microbiota, immune system and disease. In the present study, we thus investigated the effects of different NaCl content in the food (0.03%/sodium deficient, 0.5%/control, 4% and 10% NaCl) on the gut microbiome composition in mice. The bacterial composition was profiled using the 16S ribosomal RNA (rRNA) gene amplicon sequencing. Our results revealed that HSD led to distinct gut microbiome compositions compared to sodium-deficient or control diets. We also observed significant reduction in relative abundances of bacteria associated with immuno-competent short-chain fatty acid (SCFA) production (Bifidobacterium, Faecalibaculum, Blautia and Lactobacillus) in HSD-fed mice along with significant enrichment of Clostridia, Alistipes and Akkermansia depending on the sodium content in food. Furthermore, the predictive functional profiling of microbial communities indicated that the gut microbiota found in each category presents differences in metabolic pathways related to carbohydrate, lipid and amino acid metabolism. The presented data show that HSD cause disturbances in the ecological balance of the gastrointestinal microflora primarily through depletion of lactic acid-producing bacteria in a dose-dependent manner. These findings may have important implications for salt-sensitive inflammatory diseases.

Dissecting the role of CSF2RB expression in human regulatory T cells.

Colony stimulating factor 2 receptor subunit beta (CSF2RB; CD131) is the common subunit of the type I cytokine receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-3 and IL-5. Interestingly, FOXP3+ regulatory T cells (Tregs), which play a pivotal role in prevention of autoimmunity have been demonstrated to highly overexpress CSF2RB and genome-wide association studies (GWAS) identified CSF2RB as being linked to autoimmune diseases like multiple sclerosis (MS). However, the exact biological role of CD131 in human Tregs has not been defined yet. Here we investigated CD131 importance on Treg phenotype and function in a broad range of in vitro studies. Although we could not recognize a specific function of CSF2RB; CD131 in human Tregs, our data show that CD131 expression is vastly restricted to Tregs even under stimulatory conditions, indicating that CD131 could aid as a potential marker to identify Treg subpopulations from pools of activated CD4+ T cells. Importantly, our analysis further demonstrate the overexpression of CSF2RB in Tregs of patients with autoimmune diseases like MS and systemic lupus erythematosus (SLE) in comparison to healthy controls, thereby indicating that CSF2RB expression in Tregs could serve as a potential novel biomarker for disease.

Lack of adducin impairs the stability of endothelial adherens and tight junctions and may be required for cAMP-Rac1-mediated endothelial barrier stabilization.

Adducin (Add) is an actin binding protein participating in the stabilization of actin/spectrin networks, epithelial junctional turnover and cardiovascular disorders such as hypertension. Recently, we demonstrated that Add is required for adherens junctions (AJ) integrity. Here we hypothesized that Add regulates tight junctions (TJ) as well and may play a role in cAMP-mediated barrier enhancement. We evaluated the role of Add in MyEnd cells isolated from WT and Add-Knock-Out (KO) mice. Our results indicate that the lack of Add drastically alters the junctional localization and protein levels of major AJ and TJ components, including VE-Cadherin and claudin-5. We also showed that cAMP signaling induced by treatment with forskolin and rolipram (F/R) enhances the barrier integrity of WT but not Add-KO cells. The latter showed no junctional reorganization upon cAMP increase. The absence of Add also led to higher protein levels of the small GTPases Rac1 and RhoA. In vehicle-treated cells the activation level of Rac1 did not differ significantly when WT and Add-KO cells were compared. However, the lack of Add led to increased activity of RhoA. Moreover, F/R treatment triggered Rac1 activation only in WT cells. The function of Rac1 and RhoA per se was unaffected by the total ablation of Add, since direct activation with CN04 was still possible in both cell lines and led to improved endothelial barrier function. In the current study, we demonstrate that Add is required for the maintenance of endothelial barrier by regulating both AJ and TJ. Our data show that Add may act upstream of Rac1 as it is necessary for its activation via cAMP.