Scoping Review of Clinical Presentations and Outcomes in Patients with Concomitant COVID-19 Infection and Acute Mesenteric Ischaemia.

OBJECTIVES: COVID-19 infection confers an increased risk of coagulation dysfunction (1) predisposing to thromboembolism in many anatomical sites including the gastrointestinal tract (GIT) (2). This study investigates the clinical presentation and outcome in patients presenting with concurrent COVID-19 infection and gastrointestinal tract ischaemia. Furthermore, differentiation and comparisons are drawn between those with arterial and venous aetiology for mesenteric ischaemia. METHODS: A systematic search was undertaken on EMBASE, PubMed, and MEDLINE. Two independent reviewers screened titles, abstracts, and full-text articles according to the inclusion criteria and extracted relevant data. Data analyses were conducted using Excel®. RESULTS: Forty-one studies were included in the data analyses, yielding 44 patients. Twenty-six patients had mesenteric arterial occlusion, sixteen patients had mesenteric venous occlusion, and two patients had both arterial and venous mesenteric occlusion. All patients had concurrent COVID-19 infection. The survival rate in patients with arterial aetiology was 38.5% in contrast to 68.8% in patients with venous aetiology. Twelve patients (29.3%) experienced respiratory symptoms in the community before the onset of gastrointestinal symptoms, and five (12.2%) developed gastrointestinal symptoms during their inpatient stay for COVID-19 pneumonitis. CONCLUSIONS: Acute mesenteric ischaemia presents a clinical challenge to diagnose due to its non-specific symptoms. Concurrent COVID-19 infection with its predominant respiratory symptoms adds a further challenge in recognising the non-specific symptoms of mesenteric ischaemia. Our study draws attention to the increased thromboembolic risk posed by COVID-19 infection and the need for a high index of suspicion to aid prompt diagnosis and management of acute mesenteric ischaemia, even in the post-pandemic era.

Epigallocatechin-3-gallate protects sepsis-induced myocardial dysfunction by inhibiting the nuclear factor-κB signaling pathway.

Sepsis-induced myocardial dysfunction (SIMD) has become one of the most lethal complications of sepsis, while the treatment was limited by a shortage of pertinent drugs. Epigallocatechin-3-gallate (EGCG) is the highest content of active substances in green tea, and its application in cardiovascular diseases has broad prospects. This study was conducted to test the hypothesis that EGCG was able to inhibit lipopolysaccharide (LPS) induced myocardial dysfunction and investigate the underlying molecular mechanisms. The cardiac systolic function was assessed by echocardiography. The cardiomyocyte apoptosis was determined by TUNEL staining. The expression of inflammatory factors and apoptosis-related protein, cardiac markers were examined by Western Blot and qRT-PCR. EGCG effectively improve LPS-induced cardiac function damage, enhance left ventricular systolic function, and restore myocardial cell vitality. It can effectively inhibit the upregulation of TLR4 expression induced by LPS and inhibit IκB α/NF- κB/p65 signaling pathway, thereby inhibiting cardiomyocyte apoptosis and improving myocarditis. In conclusion, EGCG protects against SIMD through anti-inflammatory and anti-apoptosis effects; it was mediated by the inhibition of the TLR4/NF-κB signal pathway. Our results demonstrated that EGCG might be a possible medicine for SIMD prevention and treatment.

Improving the Knowledge and Competency of UK Foundation Doctors in Nasogastric Tube Placement: A National Study.

Objective This study aims to improve foundation doctors' knowledge of guidelines for confirming nasogastric (NG) tube position and to enhance their confidence and competency in NG tube placement. Methods A three-part educational approach was designed, which included an educational leaflet and allowed the assessment of a participant's knowledge of guidelines pertaining to NG tube positioning before and after education. This educational leaflet and accompanying pre- and post-learning assessments were distributed among NHS Foundation Trusts in the UK between January 2022 and June 2022. All participants were foundation doctors in the UK. Those who had entered further training after the completion of their foundation training, at the time of assessment distribution, were excluded. Results A total of 173 participants completed this assessment. We found a significant increase in confidence among participants following the education (p<0.05). There was also a significant improvement in objective knowledge of guidelines on NG tube position confirmation following education (p<0.05). Conclusions Current knowledge on NG tube positioning is lacking among foundation doctors, but this can be significantly improved with simple educational leaflets. Furthermore, many participants felt that more training is needed, and this topic should be included in an essential teaching program.

Causal relationship between aspirin consumption and heart failure: a Mendelian randomization study.

AIMS: This study aimed to investigate the causal association of aspirin consumption with the risk of heart failure. METHODS: Our study included a total of 218 208 individuals, with 23 397 cases of heart failure. Genetic summary data on the association between single-nucleotide polymorphisms (SNPs) and aspirin consumption were obtained from a large-scale genome-wide association study involving 462 933 individuals, of which 61 702 people were taking aspirin. After the exclusion of critical confounding factors, we assessed the final and independent association between the aspirin consumption and the risk of heart failure using 3 two-sample Mendelian randomization (MR) methods-inverse variance weighted (IVW), weighted-median, and MR-Egger regression. Sensitivity analyses and directionality test were employed to further validate the stability of the results. RESULTS: After excluding the SNPs that exhibited associations with potential confounders and harmonizing the data, a total of 32 SNPs were finally selected for MR analysis from the initially identified 60 SNPs that displayed strong associations with the exposure. The results of the main method (IVW) showed a significant positive association between aspirin use and the occurrence of heart failure (OR [odds ratio]: 1.085; 95% CI [confidence interval]: 1.015-1.161; P = 0.017), although other methods did not showed statistically significant results (MR-Egger, OR: 1.211, 95% CI: 0.842-1.21, P = 0.896; weighted-median, OR: 1.087, 95% CI: 0.983-1.202, P = 0.105). Heterogeneity test, the MR-Egger intercept, and the funnel plot did not reveal any evidence of heterogeneity (Cochran's Q statistic = 29.263; P = 0.556) or horizontal pleiotropy (intercept = 0.007; P = 0.319). The 'leave-one-out' analysis indicated that no individual SNP exerted a dominant influence on the main estimate. Directionality test confirmed the accuracy of the causal relationship between exposure and outcome direction in our data. CONCLUSIONS: Our results support a potential positive causal relationship between aspirin consumption and the occurrence of heart failure.

Association between CZT­SPECT myocardial blood flow and coronary stenosis: A cross­sectional study.

The association between the quantitative and semi-quantitative parameters of myocardial blood flow obtained using cadmium-zinc-telluride single photon emission computed tomography (CZT-SPECT) and coronary stenosis remains unclear. Therefore, the objective of the present study was to evaluate the diagnostic value of two parameters obtained using CZT-SPECT in patients with suspected or known coronary artery disease. A total of 24 consecutive patients who underwent CZT-SPECT and coronary angiography within 3 months of each other were included in the study. To evaluate the predictive ability of the regional difference score (DS), coronary flow reserve (CFR), and the combination thereof for positive coronary stenosis at the vascular level, receiver operating characteristic (ROC) curves were plotted and the area under the curves (AUCs) were calculated. Comparisons of the reclassification ability for coronary stenosis between different parameters were assessed by calculating the net reclassification index (NRI) and the integrated discrimination improvement (IDI). The 24 participants (median age: 65 years; range: 46-79 years; 79.2% male) included in this study had a total of 72 major coronary arteries. When stenosis ≥50% was defined as the criteria for positive coronary stenosis, the AUCs and the 95% confidence interval (CI) for regional DS, CFR, and the combination of the two indices were 0.653 (CI, 0.541-0.766), 0.731 (CI, 0.610-0.852) and 0.757 (CI, 0.645-0.869), respectively. Compared with single DS, the combination of DS and CFR increased the predictive ability for positive stenosis, with an NRI of 0.197-1.060 (P<0.01) and an IDI of 0.0150-0.1391 (P<0.05). When stenosis ≥75% was considered as the criteria, the AUCs were 0.760 (CI, 0.614-0.906), 0.703 (CI, 0.550-0.855), and 0.811 (CI, 0.676-0.947), respectively. Compared with DS, CFR had an IDI of -0.3392 to -02860 (P<0.05) and the combination of DS and CFR also enhanced the predictive ability, with an NRI of 0.0313-1.0758 (P<0.01). In conclusion, both regional DS and CFR had diagnostic values for coronary stenosis, but the diagnostic abilities differed in distinguishing between different degrees of stenosis, and the efficiency was improved with a combination of DS and CFR.

Statin initiation and risk of incident kidney disease in patients with diabetes.

BACKGROUND: The role of statin therapy in the development of kidney disease in patients with type 2 diabetes mellitus (DM) remains uncertain. We aimed to determine the relationships between statin initiation and kidney outcomes in patients with type 2 DM. METHODS: Through a new-user design, we conducted a multicentre retrospective cohort study using the China Renal Data System database (which includes inpatient and outpatient data from 19 urban academic centres across China). We included patients with type 2 DM who were aged 40 years or older and admitted to hospital between Jan. 1, 2000, and May 26, 2021, and excluded those with pre-existing chronic kidney disease and those who were already on statins or without follow-up at an affiliated outpatient clinic within 90 days after discharge. The primary exposure was initiation of a statin. The primary outcome was the development of diabetic kidney disease (DKD), defined as a composite of the occurrence of kidney dysfunction (estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73 m2 and > 25% decline from baseline) and proteinuria (a urinary albumin-to-creatinine ratio ≥ 30 mg/g and > 50% increase from baseline), sustained for at least 90 days; secondary outcomes included development of kidney function decline (a sustained > 40% decline in eGFR). We used Cox proportional hazards regression to evaluate the relationships between statin initiation and kidney outcomes, as well as to conduct subgroup analyses according to patient characteristics, presence or absence of dyslipidemia, and pattern of dyslipidemia. For statin initiators, we explored the association between different levels of lipid control and outcomes. We conducted analyses using propensity overlap weighting to balance the participant characteristics. RESULTS: Among 7272 statin initiators and 12 586 noninitiators in the weighted cohort, statin initiation was associated with lower risks of incident DKD (hazard ratio [HR] 0.72, 95% confidence interval [CI] 0.62-0.83) and kidney function decline (HR 0.60, 95% CI 0.44-0.81). We obtained similar results to the primary analyses for participants with differing patterns of dyslipidemia, those prescribed different statins, and after stratification according to participant characteristics. Among statin initiators, those with intensive control of high-density lipoprotein cholesterol (LDL-C) (< 1.8 mmol/L) had a lower risk of incident DKD (HR 0.51, 95% CI 0.32-0.81) than those with inadequate lipid control (LDL-C ≥ 3.4 mmol/L). INTERPRETATION: For patients with type 2 DM admitted to and followed up in academic centres, statin initiation was associated with a lower risk of kidney disease development, particularly in those with intensive control of LDL-C. These findings suggest that statin initiation may be an effective and reasonable approach for preventing kidney disease in patients with type 2 DM.

Optical-Concentrating Solar Distillation Based on Three-Dimensional Copper Foam Cubes Coated with CuS Nanoparticles and Agarose Gel.

Solar distillation by interfacial evaporation is a promising method for relieving the freshwater crisis. However, the solar-to-water generation rate inside an enclosed system is usually lower than the solar-to-vapor evaporation rate in an open system due to the lower mass transfer rate. In this work, we demonstrate high rate solar distillation based on a three-dimensional copper foam (CF) cube, which offers five surfaces for absorbing direct and reflected sunlight to achieve optical concentration. The CF surface was first oxidized into black CuO and then dip-coated with a mixture of CuS nanoparticles (CuSNPs) and agarose gel (AG) for enhancing near-infrared (NIR) absorption and water transport. The open interconnected pores within the CF cube provide a large surface area for evaporation and steam escape. In an open space, the CuSNPs/AG-coated oxidized CF cube with the five surfaces illuminated by sunlight can achieve the solar-to-vapor evaporation rate equal to 5.83 kg m-2 h-1. When the same CF cube was placed in an enclosed distillation chamber with the five chamber surfaces illuminated by sunlight, the solar-to-water generation rate is equal to 4.14 kg m-2 h-1, which is 5.34 times higher than the case with only the top chamber surface illuminated. Lastly, when real seawater was used for distillation, although the solar-to-water generation rate was decreased by about 30%, the distillation efficiency was consistent after repeated cycles and no obvious salt accumulation was observed on the light absorbing surface. This work presents an efficient and reliable method of optical concentration for enhancing the solar distillation rate in an enclosed system.

Extracellular vesicles in osteoarthritis of peripheral joint and temporomandibular joint.

Osteoarthritis (OA) is a disabling disease with significant morbidity worldwide. OA attacks the large synovial joint, including the peripheral joints and temporomandibular joint (TMJ). As a representative of peripheral joint OA, knee OA shares similar symptoms with TMJ OA. However, these two joints also display differences based on their distinct development, anatomy, and physiology. Extracellular vesicles (EVs) are phospholipid bilayer nanoparticles, including exosomes, microvesicles, and apoptotic bodies. EVs contain proteins, lipids, DNA, micro-RNA, and mRNA that regulate tissue homeostasis and cell-to-cell communication, which play an essential role in the progression and treatment of OA. They are likely to partake in mechanical response, extracellular matrix degradation, and inflammatory regulation during OA. More evidence has shown that synovial fluid and synovium-derived EVs may serve as OA biomarkers. More importantly, mesenchymal stem cell-derived EV shows a therapeutic effect on OA. However, the different function of EVs in these two joints is largely unknown based on their distinct biological characteristic. Here, we reviewed the effects of EVs in OA progression and compared the difference between the knee joint and TMJ, and summarized their potential therapeutic role in the treatment of OA.

Bouveret Syndrome: A Rare Case and Review of the Literature.

Bouveret syndrome is a subtype of gallstone ileus, wherein a calculus becomes entrapped in the duodenum via a cholecystocolic fistula, leading to gastric outlet obstruction. Due to the non-specific symptoms the patients present with, a diagnosis is reliant on computed tomography (CT), magnetic resonance imaging (MRI) or direct endoscopic visualisation. We report a case of Bouveret syndrome and review current literature, outlining the aetiopathogenesis and management strategies of this condition.

Chronic Pain as a Complication in Open Inguinal Hernia Repair: A Retrospective Study of Consenting Practice in a Single Centre.

Introduction Inguinal hernia repair is one of the most commonly performed procedures in general surgery in the United Kingdom. Chronic pain as a long-term postoperative complication of this procedure has been extensively documented in the literature. However, this complication is often undisclosed during the consenting process. This omission impairs the patients' informed decision-making process. The Montgomery v Lanarkshire Health Board case, in 2015, changed the way in which patient consent is viewed legally. This has made proper consent practices more important to surgeons undertaking procedures. Aim The objective is to assess if there has been an improvement in consenting practices by comparing consent forms from 2015 (the year of the Montgomery ruling) and 2019, specifically in regard to the risk of chronic groin pain following open inguinal hernia repair with mesh. Methods This was a retrospective review of patients who underwent open inguinal hernia repair using a prosthetic mesh in 2015 and 2019. The medical records were retrieved on the trust's electronic medical record system using the patient's hospital number. The following parameters were obtained: patient demographics, preoperative clinic letters, operation notes and consent forms. The clinic letters and consent forms were systematically reviewed for any mention of chronic groin pain. Results In 2015 and 2019, 163 and 56 open inguinal hernia repairs with mesh were performed, respectively. The median age of patients was 63 (28-88) and 64.5 (19-88) in the respective years. Throughout both years there was a predominance in male patients, and the majority of cases were performed on an elective basis. Consent for chronic pain was present in 60.7% and 62.5% of cases in 2015 and 2019, respectively (p=0.055). Conclusion Despite the importance of adequate consenting practice, we found no significant improvement in consenting practice for chronic pain following open inguinal hernia repair in the four years following the Montgomery ruling.

Do carers of adolescents at first episode psychosis have distinctive psychological needs? A pilot exploration.

BACKGROUND: Carers of patients experiencing first episode psychosis (FEP) are at an increased risk of mental and physical health problems themselves. However, little is known about how the psychological needs of carers may differ between those caring for an adolescent versus an adult who has FEP. AIMS: This pilot study aimed to explore any differences in the psychological needs of carers caring for adolescents versus adults with FEP. METHODS: We surveyed 254 carers of 198 FEP patients (34 carers of adolescents of 24 FEP adolescent patients). Carers completed self-report measures of anxiety, depression, burnout, subjective burden, coping, and key illness beliefs. The sample was divided according to whether the patient was under (adolescent) or over (adult) age 18, and analysed using mixed model logistic regressions. RESULTS: Compared to the carers of adult patients, carers of adolescents were more than twice as likely (12% vs. 30%) to experience overall burnout syndrome (all three domains), and to develop it much quicker (19.4 vs. 10.1 months). They were also more likely to adopt behavioural disengagement avoidance as a form of coping. However, there was no difference between carers in terms of anxiety, depression, beliefs and subjective burden. For carers of adolescents, burnout was independently predicted by: a negative belief about the consequences of psychosis for the adolescent patient and an incoherent understanding of the patient's mental health. CONCLUSIONS: If our findings can be replicated in a larger sample, then Rapid-Onset-Burnout-Syndrome (ROBS) is a particular problem in carers of adolescents at FEP, suggesting a need for routine screening and possible prophylactic intervention. Carers of adolescent's use of behavioural escape coping maybe also require early intervention. Theoretically, consideration could be given to the development of an adolescent sub-branch to the cognitive model of caregiving.

Clinicopathological Factors Affecting Lymph Node Yield and Positivity in Left-Sided Colon and Rectal Cancers.

Background Colorectal cancer (CRC) is a significant cause of cancer-related deaths worldwide and is the third most common cause of cancer deaths in the UK. The status of lymph node metastasis is a key factor for predicting the prognosis of a patient's CRC. Aims This study aimed to analyze the demographics of left-sided colonic and rectal cancers at a single institution. We looked closely at the correlation between patient age and various histological factors. We tried to find any significant difference in lymph node yield (LNY) between laparoscopic surgery (LS) and open surgery (OS). We aimed to identify any statistical correlation between LNY and lymph node positivity (LNP) with other patient, surgical and histopathological features. Methodology This is a retrospective, non-interventional review of consecutive patients who underwent left-sided colonic and rectal cancer resections over a three-year period between 01 April 2018 and 31 March 2021. Descriptive and inferential statistical analyses were used. Chi-squared / Fisher exact test was used on a categorical scale between two or more groups and non-parametric setting for qualitative data analysis. Results A total of 102 patients were included in the study. No statistical correlation was found between the age of the patient with the LNY, LNP, location of the tumor, type, and urgency of the operation. LNY ranged between one and 43 nodes (median (interquartile range (IQR)) 17, 8). There was no statistically significant difference in LNY between laparoscopic surgery (LS) and open surgery (OS) (p=0.1449). Significant statistical correlation was identified between LNP and completeness of resection (CoR) (p=0.039), vascular invasion (VI) (p<0.001), perineural invasion (PI) (p<0.001), and circumferential resectional margin involvement (CRMI) (p=0.039). Discussion LNY and LNP are important prognostic indices in colorectal cancer. Patient age, tumor location, the urgency of surgery, and consultant experience did not significantly impact the LNY. Our study showed a positive correlation between LNP and CRMI, VI and PI comparable to literature. Contrary to other studies, we found no statistical significance between LS vs. OS and LNY. Whether 12 nodes per patient is an appropriate level remains controversial.

AMP-dependent kinase inhibits oxidative stress-induced caveolin-1 phosphorylation and endocytosis by suppressing the dissociation between c-Abl and Prdx1 proteins in endothelial cells.

Caveolin-1 is the primary structural component of endothelial caveolae that is essential for transcellular trafficking of albumin and is also a critical scaffolding protein that regulates the activity of signaling molecules in caveolae. Phosphorylation of caveolin-1 plays a fundamental role in the mechanism of oxidant-induced vascular hyper permeability. However, the regulatory mechanism of caveolin-1 phosphorylation remains unclear. Here we identify a previously unexpected role for AMPK in inhibition of caveolin-1 phosphorylation under oxidative stress. A pharmacological activator of AMPK, 5-amino-4-imidazole carboxamide riboside (AICAR), inhibited oxidative stress-induced phosphorylation of both caveolin-1 and c-Abl, which is the major kinase of caveolin-1, and endocytosis of albumin in human umbilical vein endothelial cell. These effects were abolished by treatment with two specific inhibitors of AICAR, dipyridamole, and 5-iodotubericidin. Consistently, knockdown of the catalytic AMPKα subunit by siRNA abolished the inhibitory effect of AICAR on oxidant-induced phosphorylation of both caveolin-1 and c-Abl. Pretreatment with specific c-Abl inhibitor, imatinib mesylate, and knock down of c-Abl significantly decreased the caveolin-1 phosphorylation after H2O2 exposure and abolished the inhibitory effect of AICAR on the caveolin-1 phosphorylation. Interestingly, knockdown of Prdx-1, an antioxidant enzyme associated with c-Abl, increased phosphorylation of both caveolin-1 and c-Abl and abolished the inhibitory effect of AICAR on the caveolin-1 phosphorylation. Furthermore, co-immunoprecipitation experiment showed that AICAR suppressed the oxidant-induced dissociation between c-Abl and Prdx1. Overall, our results suggest that activation of AMPK inhibits oxidative stress-induced caveolin-1 phosphorylation and endocytosis, and this effect is mediated in part by stabilizing the interaction between c-Abl and Prdx-1.

Diazeniumdiolate-doped poly(lactic-co-glycolic acid)-based nitric oxide releasing films as antibiofilm coatings.

Nitric oxide (NO) releasing films with a bilayer configuration are fabricated by doping dibutyhexyldiamine diazeniumdiolate (DBHD/N2O2) in a poly(lactic-co-glycolic acid) (PLGA) layer and further encapsulating this base layer with a silicone rubber top coating. By incorporating pH sensitive dyes within the films, pH changes in the PLGA layer are visualized and correlated with the NO release profiles (flux vs. time). It is demonstrated that PLGA acts as both a promoter and controller of NO release from the coating by providing protons through its intrinsic acid residues (both end groups and monomeric acid impurities) and hydrolysis products (lactic acid and glycolic acid). Control of the pH changes within the PLGA layer can be achieved by adjusting the ratio of DBHD/N2O2 and utilizing PLGAs with different hydrolysis rates. Coatings with a variety of NO release profiles are prepared with lifetimes of up to 15 d at room temperature (23 °C) and 10 d at 37 °C. When incubated in a CDC flow bioreactor for a one week period at RT or 37 °C, all the NO releasing films exhibit considerable antibiofilm properties against gram-positive Staphylococcus aureus and gram-negative Escherichia coli. In particular, compared to the silicone rubber surface alone, an NO releasing film with a base layer of 30 wt% DBHD/N2O2 mixed with poly(lactic acid) exhibits an ∼98.4% reduction in biofilm biomass of S. aureus and ∼99.9% reduction for E. coli at 37 °C. The new diazeniumdiolate-doped PLGA-based NO releasing coatings are expected to be useful antibiofilm coatings for a variety of indwelling biomedical devices (e.g., catheters).

Carboxyl-ebselen-based layer-by-layer films as potential antithrombotic and antimicrobial coatings.

A carboxyl-ebselen-based layer-by-layer (LbL) film was fabricated by alternatively assembling carboxyl-ebselen immobilized polyethylenimine (e-PEI) and alginate (Alg) onto substrates followed by salt annealing and cross-linking. The annealed films exhibiting significantly improved stability are capable of generating nitric oxide (NO) from endogeneous S-nitrosothiols (RSNOs) in the presence of a reducing agent. The NO generation behaviors of different organoselenium species in solution phase are compared and the annealing mechanism to create stable LbL films is studied in detail. An LbL film coated polyurethane catheter is capable of generating physiological levels of NO from RSNOs even after blood soaking for 24 h, indicating potential antithrombotic applications of the coating. Further, the LbL film is also demonstrated to be capable of reducing living bacterial surface attachment and killing a broad spectrum of bacteria, likely through generation of superoxide (O(2)(·-)) from oxygen. This type of film is expected to have potential application as an antithrombotic and antimicrobial coating for different biomedical device surfaces.

Mesoporous silica templated biolabels with releasable fluorophores for immunoassays.

A novel class of fluorescent immuno-biolabeling systems with extremely high F/P ratio (approximately 1000-6000) were prepared by combining the template method and layer-by-layer (LbL) technique. Labels were constructed by loading organic dye fluorescein diacetate (FDA) molecules onto hollow periodic mesoporous organosilica (H-PMO) particles followed by ployelectrolyte encapsulation and antibody attachment. The labeling systems were stimuli-responsive to the addition of concentrated NaOH with the loaded dye molecules being released and detected in a well-controlled manner. When applied in sandwich immunoassays, results indicated that the biolabels were immuno-active and generated an optimal signal that was approximately 50 times higher than the conventional dye labelled antibody system.

Suppression of Fas-FasL-induced endothelial cell apoptosis prevents diabetic blood-retinal barrier breakdown in a model of streptozotocin-induced diabetes.

Diabetic macular edema, resulting from increased microvascular permeability, is the most prevalent cause of vision loss in diabetes. The mechanisms underlying this complication remain poorly understood. In the current study, diabetic vascular permeability (blood-retinal barrier breakdown) is demonstrated to result from a leukocyte-mediated Fas-FasL-dependent apoptosis of the retinal vasculature. Following the onset of streptozotocin-induced diabetes, FasL expression was increased in rat neutrophils (P<0.005) and was accompanied by a simultaneous increase in Fas expression in the retinal vasculature. Static adhesion assays demonstrated that neutrophils from diabetic, but not control, rats induced endothelial cell apoptosis in vitro (P<0.005). The latter was inhibited via an antibody-based FasL blockade (P<0.005). In vivo, the inhibition of FasL potently reduced retinal vascular endothelial cell injury, apoptosis, and blood-retinal barrier breakdown (P<0.0001) but did not diminish leukocyte adhesion to the diabetic retinal vasculature. Taken together, these data are the first to identify leukocyte-mediated Fas-FasL-dependent retinal endothelial cell apoptosis as a major cause of blood-retinal barrier breakdown in early diabetes. These data imply that the targeting of the Fas-FasL pathway may prove beneficial in the treatment of diabetic retinopathy.