Profiling the microbiome of oral and genital mucosal surfaces in Behçet's disease.

Almost 90% of Behçet's patients present with oral and/or genital ulcers which influence the disease outcome. We hypothesised that the dysregulation of the oral and genital microbiome, coupled with dysregulation of the immune response, contributes to the aetiopathogenesis of Behçet's Disease (BD) and drives disease activation. METHOD: 152 BD patient samples; 70 matched oral and genital samples plus 12 unmatched samples (Female: Male, 58:12; mean age, 42 ± 13.9: 39.3 ± 10.3) to profile microbial community high-throughput sequencing of the microbiome using 16 s rRNA sequencing targeting the V1/V2 and V3/V4 hyper variable regions were used and results reviewed in relation to disease severity, Work and Social Adjustment Scale (WSAS) outcomes and medication. RESULTS: Alpha and beta diversity were significantly decreased in genital compared to oral samples; p value<0.05. However, grouping the samples as to whether ulceration was present was not significant. Escherichia-Shigella was the only Amplicon Sequence Variants (ASVs) in the V1/V2 region that was shared between the oral mucosa with ulcer (O_U) and genital mucosa with ulcer (G_U) groups. This was in contrast to the V3/V4 region which indicated that Lachnospiraceae, Saccharimonadales, and Coriobacteriales were shared between the O_U and G_U groups. In addition, gender had no impact on the bacterial abundance in V1/V2 analysis of the oral and genital samples. V3/V4 analysis of genital samples demonstrated that Lactobacilli and Gardnerella were significantly increased in females (20 times) compared to the males in samples; p-adj <0.05. Interestingly in BD patients, Rothia which is commonly found in the mouth was present in both oral and genital samples. Streptococci were significantly increased while Veillonella significantly decreased in the presence of oral ulceration in the BD cohort. The clinical phenotype had no effect on V1/V2 and V3/V4 on the bacterial abundance of oral samples. However, medication e.g. colchicine had a significant effect on the oral microbial abundance (V1/V2; P = 0.020, V3/V4; P = 0.003). There was no relationship between colchicine and the presence/absence of genital ulcers. BD patients with active disease had higher WSAS scores, and their bacterial abundance differed significantly from the non-active BD patients (ADONIS, R2 = 0.05, p value =0.029). CONCLUSION: The presence of the microbes Streptococcus, Veillonella, Gardnerella, Lactobacillus, Atopobium, Peptoniphilus, Corynebacterium and Staphylococcus may provide early evidence of BD patients are with active disease.

Behçet's patients' response to COVID-19 vaccination.

Immune hyperstimulation by SARS-CoV2 results in multi-system involvement with consequent organ damage not dissimilar to Behçet's Disease (BD). Management of BD includes immunosuppressive medication, which led to concerns that; firstly, SARS-CoV-2 would stimulate BD activity, thrombin, clotting times, TPO antibodies, and the effectiveness and duration of the COVID-19 vaccines' response in this potentially vulnerable group. The main objectives of this study were: to assess BD patients' immune response to the COVID-19 vaccines based on age, gender, disease activity, BD phenotype, and immunomodulatory medication compared to healthy control participants by measuring anti-spike IgG levels. Further to evaluate the effect of the COVID-19 vaccines on T and B cells, immunoglobulins, thrombophilia, thyroid function and COVID-19 antibody production. Patients on immunosuppressive medication had a reduced immune response to COVID-19 vaccines. -Also, patients over 40 years and with the neurologic BD phenotype had lower responses. mRNA COVID-19 vaccines were more effective and had fewer side effects compared to conventional COVID-19 vaccines.

Gastrointestinal dysmotility complicating Behçet's syndrome: description of a newly recognised clinical phenotype.

OBJECTIVES: Gastrointestinal dysmotility may arise in a variety of auto-immune and auto-inflammatory diseases and hitherto has not been described in Behçet's syndrome (BS). METHODS: We present data on a cohort of seven patients under our care who presented with symptoms of and investigations compatible with an immune associated disorder of gastrointestinal motility, or enteric neuropathy. RESULTS: We describe the clinical features and investigation results. We undertook a trial of a novel treatment in the disease, apheresis, and noted a response not only to the enteric neuropathy but also to the systemic features of the disease, despite previous maximal immunosuppressive therapy in most cases. CONCLUSIONS: Gastrointestinal dysmotility may arise in BS and is effectively treated by apheresis. The mechanism by which this response is made immunologically requires to be elucidated in future studies.

The impact of the COVID-19 pandemic on patients with Behçet's syndrome within the framework of Maslow's hierarchy of needs: implications for patient empowerment in national or global emergencies.

OBJECTIVES: The aim of this online survey was to assess the impact of the COVID-19 pandemic on patients with Behçet's syndrome (BS) using Maslow's hierarchy of needs. METHODS: Sixty-eight BS patients from the UK completed an online questionnaire that covered three components of Maslow's hierarchy of needs regarding Physiological needs (sleep, food, mobility), Safety needs (employment, health), Social needs (relationships), personal precautions and main concerns regarding COVID-19. RESULTS: The patients received a letter from the NHS (66.2%) advising shielding. Health concerns were addressed using Tele-medicine by telephone consultations and e-mails to access BS specialists during lockdown (44.1%; 27.9%). In addition, patients also obtained information through official government and Behçet corporate health web pages related to Behçet's disease for self-empowerment. During lockdown, their weekly working hours were reduced (26.65±13.86 vs. 20.79±17.94) (p=0.017) and the employment rate was decreased (32.6% vs. 26.7%) in comparison to pre-lockdown. Moreover, the reduction in frequency of exercise per week (4.39±1.94 vs. 3.71±2.26) and healthy food consumption (73.5 % vs. 47.1%) per week were also reported (p=0.007; p=0.001, respectively). Furthermore, patients experienced sleeping less (54.4%) and feeling lonely (66.1%). CONCLUSIONS: Using Maslow's hierarchy of needs provided a framework for reviewing the quality of basic needs in patients' life during lockdown. These needs are required for healthy social lives and the deprivation should be considered while considering healthcare planning. Since lockdown appeared to have a negative influence on patients' lives and disease management in the framework of patient-centred, the empowerment of patients gained importance at this point.

Does decision tree analysis predict oral ulcer activity-related factors in patients with Behçet's syndrome?

OBJECTIVES: The study aimed to identify the interactions among treatment protocols and oral ulcer activity related factors in patients with Behçet's syndrome (BS) using the Classification and Regression Tree (CART) algorithm. METHODS: In this cross-sectional study, 979 patients with BS were included from16 centres in Turkey, Jordan, Brazil and the United Kingdom. In the CART algorithm, activities of oral ulcer (active vs. inactive), genital ulcer (active vs. inactive), cutaneous involvement (active vs. inactive), musculoskeletal involvement (active vs. inactive), gender (male vs. female), disease severity (mucocutaneous and musculoskeletal involvement vs. major organ involvement), smoking habits (current smoker vs. non-smoker), tooth brushing habits (irregular vs. regular), were input variables. The treatment protocols regarding immunosuppressive (IS) or non-IS medications were the target variable used to split from parent nodes to purer child nodes in the study. RESULTS: In mucocutaneous and musculoskeletal involvement (n=538), the ratio of IS use was higher in patients with irregular toothbrushing (ITB) habits (27.1%) than in patients with regular toothbrushing (RTB) habits (14.2%) in oral ulcer activity. In major organ involvement (n=441), male patients with ITB habits were more likely treated with IS medications compared to those with RTB habits (91.6% vs. 77.6%, respectively). CONCLUSIONS: Male BS patients on IS who have major organ involvement and oral ulcer activity with mucocutaneous and musculoskeletal involvement have irregular toothbrushing habits. Improved oral hygiene practices should be considered to be an integral part for implementing patient empowerment strategies for BS.

A cross-sectional study on activity impairment in primary Sjogren's syndrome.

OBJECTIVE: The aim of this cross-sectional study was to show relations between activity impairment and salivary gland involvement for patient empowerment in primary Sjogren's syndrome (pSS). METHODS: In the study, 86 patients with pSS were included. The data were collected through clinical examinations and a questionnaire regarding Work Productivity and Activity Impairment (WPAI), EULAR Sjogren's syndrome patient-reported index (ESSPRI) and Oral Health Impact Profile-14 (OHIP-14). Relations were analysed by using mediation and moderation analyses. In simple mediation analysis, an independent variable (X) influences outcome variable (Y) through a mediator variable (M) whereas a moderator variable (W) affects the direction of the relationship between the dependent (Y) and independent variables (X). RESULTS: Increases in ESSPRI-Dryness score (X) (p = 0.0189) and OHIP-14 score (M) (p = 0.0004) were associated with the poor WPAI activity impairment score (Y) in the first mediation analysis. The WPAI activity impairment score was mediated by the elevated ESSPRI-Fatigue score (X) (p = 0.03641) and low U-SFR (M) (p = 0.0000) in the second mediation analysis. In addition, ESSPRI-Pain score (W) was the significant moderator for WPAI activity impairment (Y) in patients without hyposalivation in the moderation analysis (p = 0.0010). CONCLUSION: WPAI activity impairment was affected by both ESSPRI-Dryness with OHRQoL and ESSPRI-Fatigue with SFR in glandular involvement.

The assessment of presenteeism and activity impairment in Behçet's syndrome and recurrent aphthous stomatitis: a multicentre study.

OBJECTIVE: To evaluate key factors for presenteeism and activity impairment in multinational patients with Behçet's syndrome (BS) and recurrent aphthous stomatitis (RAS). METHODS: In this cross-sectional study, 364 BS patients from Jordan, Brazil, the United Kingdom and Turkey and 143 RAS patients from the United Kingdom and Turkey were included. The Work Productivity Activity Impairment (WPAI) scale was used for presenteeism and activity impairment. Mediation analyses were performed to evaluate both direct and indirect causal effects. RESULTS: Presenteeism score was higher in active patients with genital ulcers and eye involvement as well as patients with comorbidities and current smokers than the others in BS (P < 0.05). In RAS, presenteeism score was elevated by oral ulcer activity in the direct path (P = 0.0073) and long disease duration as a mediator in the indirect path (P = 0.0191). Patients with active joint involvement had poor scores in absenteeism, presenteeism, overall impairment and activity impairment compared with those of inactive patients (P < 0.05). Using mediation analysis, the activity impairment score was directly mediated by joint activity (P = 0.0001) and indirectly mediated through oral ulcer-related pain in BS (P = 0.0309). CONCLUSION: In BS, presenteeism was associated with disease activity, presence of comorbidities and being a current smoker, whereas in RAS, presenteeism was associated with oral ulcer activity and increased length of the disease. Moreover, activity impairment was adversely affected by joint activity and oral ulcer related pain in BS. Patients need to be empowered by using appropriate treatment strategies in their working environment and daily life.

Behçet's syndrome in children and young people in the United Kingdom and the Republic of Ireland: a prospective epidemiological study.

OBJECTIVES: To define the incidence and prevalence of Behçet's syndrome (BS) in children and young people (CYP) up to the age of 16 years in the United Kingdom (UK) and Republic of Ireland (ROI). METHODS: A prospective epidemiological study was undertaken with the support of the British Paediatric Surveillance Unit (BPSU) and the British Society of Paediatric Dermatologists (BSPD). Consultants reported anonymised cases of BS seen. A follow-up study at one year examined progression of disease and treatment. RESULTS: Over a two-year period, 56 cases met the International Criteria for Behçet's Disease. For children under 16 years of age, the two-year period prevalence estimate was 4.2 per million (95% CI: 3.2, 5.4) and the incidence was 0.96 per million person years (95% CI: 0.66, 1.41). Mucocutaneous disease was the most common phenotype (56/100%), with ocular (10/56; 17.9%), neurological (2/56; 3.6%) and vascular involvement (3/56; 5.4%) being less common. Median age at onset was 6.34 years and at diagnosis was 11.72 years. There were slightly more female than male children reported (32/56; 55.6%). The majority of cases (85.7%) were white Caucasian. Apart from genital ulcers, which were more common in females, there were no significant differences in frequency of manifestations between male or females, nor between ethnicities. Over 83% of cases had three or more non-primary care healthcare professionals involved in their care. CONCLUSION: BS is extremely rare in CYP in the UK and ROI and most have mucocutaneous disease. Healthcare needs are complex, and coordinated care is key.

KIR3DL1/S1 Allotypes Contribute Differentially to the Development of Behçet Disease.

Behçet disease is a chronic, relapsing-remitting autoinflammatory syndrome with a strong HLA-B*51 association. In this paper, we describe a human cohort of 267 individuals with Behçet disease and 445 matched controls from a tertiary referral center in the U.K. HLA-B*51 was confirmed as a genetic risk factor in this group (p = 0.0006, Bonferroni-Dunn correction for multiple testing [Pc] = 0.0192, odds ratio [OR] 1.92, 95% confidence interval [CI] 1.33-2.76). KIR3DL1/S1 allele-level analysis indicated that low-expressing KIR3DL1/S1 alleles in combination with KIR3DS1 increased the risk of developing Behçet disease (KIR3DL1LOW/KIR3DS1: p = 0.0004, Pc = 0.0040, OR 2.47, 95% CI 1.43-4.25), whereas high-expressing KIR3DL1/S1 alleles in combination with a null-expressing KIR3DL1 reduced the risk of disease (KIR3DL1HIGH/KIR3DL1NULL: p = 0.0035, Pc = 0.0350, OR 0.53, 95% CI 0.33-0.87). Behçet disease can manifest as a purely mucocutaneous disease or can involve other organ systems such as the eyes. In the U.K. cohort studied in this study, KIR3DL1LOW/KIR3DS1 increased the risk of ophthalmic disease (p = 1.2 × 10-5, OR 3.92, 95% CI 2.06-7.47), whereas KIR3DL1HIGH/KIR3DL1NULL reduced the risk of having purely mucocutaneous disease (p = 0.0048, OR 0.45, 95% CI 0.25-0.81). To our knowledge, this is the first analysis of KIR3DL1/S1 allelic variation in Behçet disease and may provide insight into the pathogenic role of HLA-B*51 and its interaction with KIR3DL1/S1.

Induction of p53 in keratinocyte cultures treated with Behçet's patient sera.

BACKGROUND: Behçet's disease (BD) is a rare, multisystem vasculitis disease characterized by recurrent orogenital ulcerations with its etiology remained unclear. The transcription factor p53 has been reported to be upregulated in some autoimmune diseases, such as lupus erythematosus, dermatomyositis, and psoriasis. However, little is known about its alteration in BD. METHODS: Keratinocyte cultures of both skin and oral origins were treated sera of 18 Behcet patients for 24 hours and analyzed by indirect immunofluorescence for p53 expression. The specificity of p53 expression was confirmed by siRNA-mediated p53 knockdown and the serum IgG removal studies. The expression of p53 levels was quantitatively analyzed with ImageJ. RESULTS: It was shown that the expression of p53 is increased in skin and oral keratinocyte cell lines, in both the nucleus and cytoplasm of cells treated with patient sera compared to controls. Either p53 knockdown or IgG removal results in a reduction of p53 levels relative to cells treated with patient sera without p53 knockdown or IgG depletion. CONCLUSIONS: This in vitro study provides the first evidence that BD sera can induce the p53 expression in keratinocytes that may have implications in Behcet pathogenesis.

2018 update of the EULAR recommendations for the management of Behçet's syndrome.

Several new treatment modalities with different mechanisms of action have been studied in patients with Behçet's syndrome (BS). The aim of the current effort was to update the recommendations in the light of these new data under the auspices of the European League Against Rheumatism (EULAR) Standing Committee for Clinical Affairs. A task force was formed that included BS experts from different specialties including internal medicine, rheumatology, ophthalmology, dermatology, neurology, gastroenterology, oral health medicine and vascular surgery, along with a methodologist, a health professional, two patients and two fellows in charge of the systematic literature search. Research questions were determined using a Delphi approach. EULAR standardised operating procedures was used as the framework. Results of the systematic literature review were presented to the task force during a meeting. The former recommendations were modified or new recommendations were formed after thorough discussions followed by voting. The recommendations on the medical management of mucocutaneous, joint, eye, vascular, neurological and gastrointestinal involvement of BS were modified; five overarching principles and a new recommendation about the surgical management of vascular involvement were added. These updated, evidence-based recommendations are intended to help physicians caring for patients with BS. They also attempt to highlight the shortcomings of the available clinical research with the aim of proposing an agenda for further research priorities.

Management of major organ involvement of Behçet's syndrome: a systematic review for update of the EULAR recommendations.

Objective: To assess the efficacy and safety of treatment modalities for major organ involvement of Behçet's syndrome (BS), in order to inform the update of the EULAR recommendations for the management of BS. Methods: A systematic literature review of all randomized controlled trials, controlled clinical trials, or open label trials assessing eye, vascular, nervous system or gastrointestinal system involvement of BS was performed. If controlled trials were not available for answering a specific research question, uncontrolled studies or case series were also included. Results: We reviewed the titles and abstracts of 3927 references and 161 studies met our inclusion criteria. There were only nine randomized controlled trials. Observational studies with IFN-α and monoclonal anti-TNF antibodies showed beneficial results for refractory uveitis. Meta-analysis of case-control studies showed that immunosuppressives decreased the recurrence rate of deep vein thrombosis significantly whereas anticoagulants did not. CYC and high dose glucocorticoids decreased mortality in pulmonary arterial aneurysms and postoperative complications in peripheral artery aneurysms. Beneficial results for gastrointestinal involvement were obtained with 5-ASA derivatives and AZA as first line treatment and with thalidomide and/or monoclonal anti-TNF antibodies in refractory cases. Observational studies for nervous system involvement showed improved outcome with immunosuppressives and glucocorticoids. Meta-analysis of case-control studies showed an increased risk of developing nervous system involvement with ciclosporin-A. Conclusion: The majority of studies related to major organ involvement that informed the updated EULAR recommendations for the management of BS were observational studies.

Why are Behçet's disease patients always exhausted?

OBJECTIVES: Patients with Behçet's disease (BD) constantly complain of fatigue and many have problems with poor sleep. This ultimately has a major impact on all aspects of normal living. To attempt to understand this, Artificial Intelligence (AI) was used to identify potential biomarkers. These were alpha-melanocyte stimulating hormone (α-MSH), vasoactive intestinal peptide (VIP) and some inflammatory cytokines. We assessed the association of fatigue, quality of sleep and disease activity with circulating concentration of α-MSH, VIP and inflammatory cytokines. METHODS: There were 127 participants, 97 BD patients, and 30 healthy controls (HC). All completed the Multi-Dimensional Assessment of Fatigue questionnaire (MAF) and the Pittsburgh Sleep Quality Index (PSQI) on the day of their clinical assessment. Enzyme-linked immunosorbent assays (ELISA) were used to evaluate the serum concentrations of α-MSH, VIP and cytokines (IL-1ß, IL-6, IL-10, and TNF-α). RESULTS: 64% of BD patients experienced high fatigue scores, and 63% had poor quality of sleep. When BD and HC were compared the MAF and PSQI scores as well as the serum concentrations of α-MSH, VIP, and IL-6 were significantly higher in BD (p values were: 0.001, 0.001, 0.001, 0.004 and 0.036, respectively). Both α-MSH and IL-6 had significant impact on MAF and PSQI. Interestingly, VIP had a significant influence on PSQI and disease activity, but not on MAF. CONCLUSIONS: A better understanding of these complex clinical and biochemical interactions between α-MSH, VIP and IL-6 might lead to the development of novel approaches to manage fatigue and sleep disorders as well as disease activity in BD patients.

The influence of oral health and psycho-social well-being on clinical outcomes in Behçet's disease.

This study was designed to investigate the association of oral ulceration and oral health factors, together with psycho-social well-being in Behçet's disease (BD), and to clarify the importance of psycho-social support of patients in the overall management of BD. The study comprised of a cohort of 146 BD patients (mean age ± SD = 39.65 ± 13.20) and 20 recurrent aphthous stomatitis (RAS) patients (mean age ± SD = 42.32 ± 11.32). Oral ulcer severity score (OUSS), Behçet's disease current activities form (BDCAF), hospital anxiety and depression scale (HADS), and the work and social adjustment scale (WSAS) were investigated. Oral health risk factors were also included. The analysis of variance, regression, and factor analysis were used to scrutinise the data. Almost 73% of patients were at high caries risk in BD and RAS groups. Thirty-nine percent of BD and forty percent of RAS had a score of BPE3 (probing depth 3.5-5.5 mm). Regression analysis revealed that OUSS and WSAS had a positive impact to increase the BDCAF score in BD patients (ß = 0.395, P = 0.001; ß = 0.240, P = 0.019), respectively. Dental health, periodontal health, anxiety, depression, and WSAS variables had strong loadings by factor analysis based on gender and at the time of present and absent of oral ulceration. The main oral ulcer characteristics that had significant influences on the total of oral health quality of life by 68.6% were: size, duration, ulcer-free period, and pain. The results highlighted the significant influence of oral ulceration, patients' oral health, diet, and psycho-social well-being as multi-factorial causes on increasing disease activity in BD patients.

Behçet's syndrome and health-related quality of life: influence of symptoms, lifestyle and employment status.

OBJECTIVES: Behçet's syndrome (BS) is a chronic multisystemic disorder. The complex pattern of BS symptoms can effect negatively on patients' quality of life. The aim of this study is to evaluate the influence of BS symptoms, oral health related lifestyles and employment status on Health Related Quality of Life (HRQoL). METHODS: A questionnaire was mailed to a cohort of 641 adult members of the Behçet's Syndrome Society (BSS) and patients attending a Behçet's syndrome centre in the UK. Respondents gave information on socio-demographic characteristics, disease duration, current symptoms, symptom control, health related lifestyle, diet, smoking and alcohol, employment status and quality of life (the EQ-5D index). RESULTS: 315 out of 426 BS participants (Males: Females=136:179) were recruited. BS symptoms and EQ-5D score model (R=0.67 and R2=0.45) and standardised coefficients for symptoms were; arthropathy (-0.336), headache (-0.227), neurological problems (-0.135), pathergy reaction (-0.119) and skin lesions (-0.107) in decreasing order. This finding was similar to a 2009 study of the same cohort. Regression analysis of tobacco consumption revealed that tobacco use was a risk factor for decreasing the EQ-5D score (beta value = - 0.72, p=0.001). Using an effective mouthwash has a positive impact on HRQoL (beta value= 0.149 and p=0.012). The mean EQ-5D in patients who continued in employment and who were not receiving benefits was better compared to other sub groups. CONCLUSIONS: BS symptoms, employment status, a healthy lifestyle combined with a good oral health have a significant impact on the HRQoL of BS patients.

Facial biometrics of peri-oral changes in Crohn's disease.

Crohn's disease is a chronic relapsing and remitting inflammatory condition which affects any part of the gastrointestinal tract. In the oro-facial region, patients can present peri-oral swellings which results in severe facial disfigurement. To date, assessing the degree of facial changes and evaluation of treatment outcomes relies on clinical observation and semi-quantitative methods. In this paper, we describe the development of a robust and reproducible measurement strategy using 3-D facial biometrics to objectively quantify the extent and progression of oro-facial Crohn's disease. Using facial laser scanning, 32 serial images from 13 Crohn's patients attending the Oral Medicine clinic were acquired during relapse, remission, and post-treatment phases. Utilising theories of coordinate metrology, the facial images were subjected to registration, regions of interest identification, and reproducible repositioning prior to obtaining volume measurements. To quantify the changes in tissue volume, scan images from consecutive appointments were compared to the baseline (first scan image). Reproducibility test was performed to ascertain the degree of uncertainty in volume measurements. 3-D facial biometric imaging is a reliable method to identify and quantify peri-oral swelling in Crohn's patients. Comparison of facial scan images at different phases of the disease revealed precisely profile and volume changes. The volume measurements were highly reproducible as adjudged from the 1% standard deviation. 3-D facial biometrics measurements in Crohn's patients with oro-facial involvement offers a quick, robust, economical and objective approach for guided therapeutic intervention and routine assessment of treatment efficacy on the clinic.

Characterising sources of PM2·5 exposure for school children with asthma: a personal exposure study across six cities in sub-Saharan Africa.

BACKGROUND: Air pollution is the second largest risk to health in Africa, and children with asthma are particularly susceptible to its effects. Yet, there is a scarcity of air pollution exposure data from cities in sub-Saharan Africa. We aimed to identify potential exposure reduction strategies for school children with asthma living in urban areas in sub-Saharan Africa. METHODS: This personal exposure study was part of the Achieving Control of Asthma in Children in Africa (ACACIA) project. Personal exposure to particulate matter (PM) was monitored in school children in six cities in sub-Saharan Africa (Blantyre, Malawi; Durban, South Africa; Harare, Zimbabwe; Kumasi, Ghana; Lagos, Nigeria; and Moshi, Tanzania). Participants were selected if they were aged 12-16 years and had symptoms of asthma. Monitoring was conducted between June 21, and Nov 26, 2021, from Monday morning (approximately 1000 h) to Friday morning (approximately 1000 h), by use of a bespoke backpack with a small air pollution monitoring unit with an inbuilt Global Positioning System (GPS) data logger. Children filled in a questionnaire detailing potential sources of air pollution during monitoring and exposures were tagged into three different microenvironments (school, commute, and home) with GPS coordinates. Mixed-effects models were used to identify the most important determinants of children's PM2·5 (PM <2·5 µm in diameter) exposure. FINDINGS: 330 children were recruited across 43 schools; of these, 297 had valid monitoring data, and 1109 days of valid data were analysed. Only 227 (20%) of 1109 days monitored were lower than the current WHO 24 h PM2·5 exposure health guideline of 15 µg/m3. Children in Blantyre had the highest PM2·5 exposure (median 41·8 µg/m3), whereas children in Durban (16·0 µg/m3) and Kumasi (17·9 µg/m3) recorded the lowest exposures. Children had significantly higher PM2·5 exposures at school than at home in Kumasi (median 19·6 µg/m3vs 14·2 µg/m3), Lagos (32·0 µg/m3vs 18·0 µg/m3), and Moshi (33·1 µg/m3vs 23·6 µg/m3), while children in the other three cities monitored had significantly higher PM2·5 exposures at home and while commuting than at school (median 48·0 µg/m3 and 43·2 µg/m3vs 32·3 µg/m3 in Blantyre, 20·9 µg/m3 and 16·3 µg/m3vs 11·9 µg/m3 in Durban, and 22·7 µg/m3 and 25·4 µg/m3vs 16·4 µg/m3 in Harare). The mixed-effects model highlighted the following determinants for higher PM2·5 exposure: presence of smokers at home (23·0% higher exposure, 95% CI 10·8-36·4), use of coal or wood for cooking (27·1%, 3·9-56·3), and kerosene lamps for lighting (30·2%, 9·1-55·2). By contrast, 37·2% (95% CI 22·9-48·2) lower PM2·5 exposures were found for children who went to schools with paved grounds compared with those whose school grounds were covered with loose dirt. INTERPRETATION: Our study suggests that the most effective changes to reduce PM2·5 exposures in these cities would be to provide paving in school grounds, increase the use of clean fuel for cooking and light in homes, and discourage smoking within homes. The most efficient way to improve air quality in these cities would require tailored interventions to prioritise different exposure-reduction policies in different cities. FUNDING: UK National Institute for Health and Care Research.

Non-junctional human desmoglein 3 acts as an upstream regulator of Src in E-cadherin adhesion, a pathway possibly involved in the pathogenesis of pemphigus vulgaris.

E-cadherin, a classical cadherin, is an adhesion receptor in adherens junctions and has important functions in cell-cell adhesion and cell signalling. Recently we reported that a desmosomal cadherin, desmoglein 3 (Dsg3), an autoantigen in pemphigus vulgaris (PV), associates with E-cadherin and activates Src, which results in tyrosine phosphorylation of adherens junction proteins. However, the nature of such an interaction and its role in cell-cell adhesion remain unclear. In this report, we provide direct evidence that it is the detergent-soluble, non-desmosomal Dsg3 that regulates the activity of Src and its association with E-cadherin in adherens junction formation. Modulation of Dsg3 levels, either by Dsg3 silencing or over-expression, alters Src activity and its association with E-cadherin. Dsg3 silencing caused retardation of calcium-induced E-cadherin junction assembly and a reduction of desmosomal protein expression. Furthermore, we provide evidence that this signalling pathway is involved, at least in part, in the pathophysiology of pemphigus. Along with the reduced expression of Dsg3, loss and disruption of E-cadherin and a concomitant decreased pSrc signalling was identified in the basal keratinocytes surrounding the blisters in PV. These findings suggest a novel function for Dsg3 in the control of E-cadherin-Src signalling and cell-cell adhesion.

Desmoglein 3 acting as an upstream regulator of Rho GTPases, Rac-1/Cdc42 in the regulation of actin organisation and dynamics.

Desmoglein 3 (Dsg3), a member of the desmoglein sub-family, serves as an adhesion molecule in desmosomes. Our previous study showed that overexpression of human Dsg3 in several epithelial lines induces formation of membrane protrusions, a phenotype suggestive of Rho GTPase activation. Here we examined the interaction between Dsg3 and actin in detail and showed that endogenous Dsg3 colocalises and interacts with actin, particularly the junctional actin in a Rac1-dependent manner. Ablation of Rac1 activity by dominant negative Rac1 mutant (N17Rac1) or the Rac1 specific inhibitor (NSC23766) directly disrupts the interaction between Dsg3 and actin. Assembly of the junctional actin at the cell borders is accompanied with enhanced levels of Dsg3, while inhibition of Dsg3 by RNAi results in profound changes in the organisation of actin cytoskeleton. In accordance, overexpression of Dsg3 results in a remarkable increase of Rac1 and Cdc42 activities and to a lesser extent, RhoA. The enhancements in Rho GTPases are accompanied by the pronounced actin-based membrane structures such as lamellipodia and filopodia, enhanced rate of actin turnover and cell polarisation. Together, our results reveal an important novel function for Dsg3 in promoting actin dynamics through regulating Rac1 and Cdc42 activation in epithelial cells.