Retrospective validation of MetaSystems' deep-learning-based digital microscopy platform with assistance compared to manual fluorescence microscopy for detection of mycobacteria

This study aimed to validate Metasystems' automated acid-fast bacilli (AFB) smear microscopy scanning and deep-learning-based image analysis module (Neon Metafer) with assistance on respiratory and pleural samples, compared to conventional manual fluorescence microscopy (MM). Analytical parameters were assessed first, followed by a retrospective validation study. In all, 320 archived auramine-O-stained slides selected non-consecutively [85 originally reported as AFB-smear-positive, 235 AFB-smear-negative slides; with an overall mycobacterial culture positivity rate of 24.1% (77/320)] underwent whole-slide imaging and were analyzed by the Metafer Neon AFB Module (version 4.3.130) using a predetermined probability threshold (PT) for AFB detection of 96%. Digital slides were then examined by a trained reviewer blinded to previous AFB smear and culture results, for the final interpretation of assisted digital microscopy (a-DM). Paired results from both microscopic methods were compared to mycobacterial culture. A scanning failure rate of 10.6% (34/320) was observed, leaving 286 slides for analysis. After discrepant analysis, concordance, positive and negative agreements were 95.5% (95%CI, 92.4%-97.6%), 96.2% (95%CI, 89.2%-99.2%), and 95.2% (95%CI, 91.3%-97.7%), respectively. Using mycobacterial culture as reference standard, a-DM and MM had comparable sensitivities: 90.7% (95%CI, 81.7%-96.2%) versus 92.0% (95%CI, 83.4%-97.0%) (P-value = 1.00); while their specificities differed 91.9% (95%CI, 87.4%-95.2%) versus 95.7% (95%CI, 92.1%-98.0%), respectively (P-value = 0.03). Using a PT of 96%, MetaSystems' platform shows acceptable performance. With a national laboratory staff shortage and a local low mycobacterial infection rate, this instrument when combined with culture, can reliably triage-negative AFB-smear respiratory slides and identify positive slides requiring manual confirmation and semi-quantification.

IMPORTANCE

This manuscript presents a full validation of MetaSystems' automated acid-fast bacilli (AFB) smear microscopy scanning and deep-learning-based image analysis module using a probability threshold of 96% including accuracy, precision studies, and evaluation of limit of AFB detection on respiratory samples when the technology is used with assistance. This study is complementary to the conversation started by Tomasello et al. on the use of image analysis artificial intelligence software in routine mycobacterial diagnostic activities within the context of high-throughput laboratories with low incidence of tuberculosis.

Mind and skin: Exploring the links between inflammation, sleep disturbance and neurocognitive function in patients with atopic dermatitis

Atopic dermatitis (AD) is a chronic, pruritic and inflammatory, dry skin condition with many known comorbidities. These include airway disease, food allergies, atopic eye disease and autoimmune conditions. Furthermore, there is often significant sleep disturbance as well as increased psychological distress and mental health problems. Severe AD therefore often has a significant impact on the quality of life of both patients and their families. In this review we discuss recent findings on the putative links between AD, its association with itch, sleep disturbance and neuropsychiatric morbidity, including the role of inflammation in these conditions. Itch was thought to predominantly drive sleep disruption in AD. We now understand changes in sleep influence immune cell distribution and the associated inflammatory cytokines, which suggests a bidirectional relationship between AD and sleep. We also increasingly recognize inflammation as a key driver in psychological symptoms and disorders. The link between cutaneous, systemic and possible brain inflammation could at least in part be driven by the sleep deprivation and itch-driven neuronal proliferation seen in AD.

Gordonia sputi-associated bloodstream infection in a renal transplant patient with chronic indwelling central venous catheter: a case report and literature review

Introduction

Although rare, human infections caused by Gordonia spp. have been reported, especially within the immunocompromised population and those with long-term indwelling devices. We report a case of Gordonia spp. bacteraemia in a renal transplant patient and present a literature review on microbiological identification methods of this organism.

Case Presentation

A 62-year-old female renal transplant recipient admitted to hospital with a 2-month history of dry cough and fevers occurring weekly when receiving electrolyte replacement infusions via a Groshong line. Over 2 weeks, blood cultures repeatedly isolated a Gram-positive bacillus solely in aerobic bottles, and this was initially reported as Rhodococcus spp. by the local microbiology laboratory. Chest computed tomography (CT) showed multiple ground-glass lung opacities suggestive of septic pulmonary emboli. As central line-associated bloodstream infection was suspected, empirical antibiotics were initiated and the Groshong line was removed. The Gram-positive bacillus was later confirmed by the reference laboratory as Gordonia sputi via 16S rRNA sequencing. Vancomycin and ciprofloxacin for a duration of 6 weeks were completed as targeted antimicrobial therapy. After treatment, the patient remained symptom-free with marked improvement on repeat CT chest imaging.

Conclusion

This case illustrates the challenges surrounding identification of Gordonia spp. and other aerobic actinomycetes. 16S rRNA gene sequencing may be a preferred identification method, especially when initial workup of a weakly acid-fast organism fails to make an identification or shows discrepant results using traditional diagnostic modalities.

Non-biologic systemic treatments for atopic dermatitis: Current state of the art and future directions

Atopic dermatitis (AD) is a prevalent chronic inflammatory skin condition with an unpredictable clinical course, associated with a significant impact on quality of life. The pathophysiology of AD involves a complex interplay between impaired skin barrier function, immune dysregulation, genetic susceptibility and environmental factors. Advances in understanding of the immunological mechanisms that underpin AD have heralded the recognition of multiple novel therapeutic targets to bolster the systemic treatment armamentarium for patients with severe AD. This review examines current and future directions of non-biologic systemic treatments for AD, with a focus on their mechanism of action, efficacy and safety, and the key considerations to help inform treatment decisions. We summarize new developments in small molecule systemic therapies which have the potential to further advance our management of AD in this new era of precision medicine.

Biomarkers associated with the development of comorbidities in patients with atopic dermatitis: A systematic review

Biomarkers associated with the development of comorbidities in atopic dermatitis (AD) patients have been reported, but have not yet been systematically reviewed. Seven electronic databases were searched, from database inception to September 2021. English language randomized controlled trials, prospective and retrospective cohort, and case-control studies that investigated the association between a biomarker and the development of comorbidities in AD patients were included. Two authors independently screened the records for eligibility, one extracted all data, and critically appraised the quality of studies and risk of bias. Fifty six articles met the inclusion criteria, evaluating 146 candidate biomarkers. The most frequently reported biomarkers were filaggrin mutations and allergen specific-IgE. Promising biomarkers include specific-IgE and/or skin prick tests predicting the development of asthma, and genetic polymorphisms predicting the occurrence of eczema herpeticum. The identified studies and biomarkers were highly heterogeneous, and associated with predominately moderate-to-high risk of bias across multiple domains. Overall, findings were inconsistent. High-quality studies assessing biomarkers associated with the development of comorbidities in people with AD are lacking. Harmonized datasets and independent validation studies are urgently needed.

The effects of systemic immunomodulatory treatments on COVID-19 outcomes in patients with atopic dermatitis: Results from the global SECURE-AD registry

BACKGROUND

Limited data are available on the effects of systemic immunomodulatory treatments on COVID-19 outcomes in patients with atopic dermatitis (AD).

OBJECTIVE

To investigate COVID-19 outcomes in patients with AD treated with or without systemic immunomodulatory treatments, using a global registry platform.

METHODS

Clinicians were encouraged to report cases of COVID-19 in their patients with AD in the Surveillance Epidemiology of Coronavirus Under Research Exclusion for Atopic Dermatitis (SECURE-AD) registry. Data entered from 1 April 2020 to 31 October 2021 were analysed using multivariable logistic regression. The primary outcome was hospitalization from COVID-19, according to AD treatment groups.

RESULTS

442 AD patients (mean age 35.9 years, 51.8% male) from 27 countries with strongly suspected or confirmed COVID-19 were included in analyses. 428 (96.8%) patients were treated with a single systemic therapy (n = 297 [67.2%]) or topical therapy only (n = 131 [29.6%]). Most patients treated with systemic therapies received dupilumab (n = 216). Fourteen patients (3.2%) received a combination of systemic therapies. Twenty-six patients (5.9%) were hospitalized. No deaths were reported. Patients treated with topical treatments had significantly higher odds of hospitalization, compared with those treated with dupilumab monotherapy (odds ratio (OR) 4.65 [95%CI 1.71-14.78]), including after adjustment for confounding variables (adjusted OR (aOR) 4.99 [95%CI 1.4-20.84]). Combination systemic therapy which did not include systemic corticosteroids was associated with increased odds of hospitalization, compared with single agent non-steroidal immunosuppressive systemic treatment (OR 8.09 [95%CI 0.4-59.96], aOR 37.57 [95%CI 1.05-871.11]). Hospitalization was most likely in patients treated with combination systemic therapy which included systemic corticosteroids (OR 40.43 [95%CI 8.16-207.49], aOR 45.75 [95%CI 4.54-616.22]).

CONCLUSIONS

Overall, the risk of COVID-19 complications appears low in patients with AD, even when treated with systemic immunomodulatory agents. Dupilumab monotherapy was associated with lower hospitalization than other therapies. Combination systemic treatment, particularly combinations including systemic corticosteroids, was associated with the highest risk of severe COVID-19.

Atopic dermatitis and risk of autoimmune conditions: Population-based cohort study

BACKGROUND

Atopic dermatitis (AD) is associated with immune dysregulation, but epidemiologic data on the pattern of autoimmune comorbidity in people with AD are limited.

OBJECTIVE

We sought to determine the risk of autoimmune conditions in people newly diagnosed with AD.

METHODS

Retrospective cohort analysis (January 2009 to December 2018), using the UK-based Oxford-Royal College of General Practitioners Research and Surveillance Centre primary care database. We compared baseline prevalence and incidence after diagnosis of autoimmune conditions in 173,709 children and adults with new-onset AD and 694,836 age-, sex-, and general practitioner practice-matched controls. Outcomes were a composite of any autoimmune condition (Crohn disease, ulcerative colitis, celiac disease, pernicious anemia, type 1 diabetes, autoimmune hypothyroidism, Graves disease, psoriatic arthritis, rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, Sjögren syndrome, vitiligo, alopecia areata, and multiple sclerosis) and each individual autoimmune condition.

RESULTS

Preexisting autoimmune conditions were more common in people diagnosed with AD compared to controls (composite 5.8% vs 4.3%). Excluding people with preexisting autoimmune disease, there was an association between AD and incidence of new-onset autoimmune disease (composite adjusted hazard ratio [aHR] 1.28; 95% confidence interval [CI] 1.23-1.34). Risk was highest for more severe AD (aHR 1.99; 95% CI 1.77-2.23) than moderate AD (aHR 1.33; 95% CI 1.19-1.49) or mild AD (aHR 1.22; 95% CI 1.16-1.28). People with AD were at significantly increased risk of developing psoriatic arthritis, Sjögren syndrome, Crohn disease, vitiligo, alopecia areata, pernicious anemia, ulcerative colitis, rheumatoid arthritis, and hypothyroidism (aHR range 1.17-2.06), but not other autoimmune conditions.

CONCLUSION

People with AD have an increased risk of multiple autoimmune conditions, especially those with more severe AD.

The power and potential of BIOMAP to elucidate host-microbiome interplay in skin inflammatory diseases

The two most common chronic inflammatory skin diseases are atopic dermatitis (AD) and psoriasis. The underpinnings of the remarkable degree of clinical heterogeneity of AD and psoriasis are poorly understood and, as a consequence, disease onset and progression are unpredictable and the optimal type and time-point for intervention are as yet unknown. The BIOMAP project is the first IMI (Innovative Medicines Initiative) project dedicated to investigating the causes and mechanisms of AD and psoriasis and to identify potential biomarkers responsible for the variation in disease outcome. The consortium includes 7 large pharmaceutical companies and 25 non-industry partners including academia. Since there is mounting evidence supporting an important role for microbial exposures and our microbiota as factors mediating immune polarization and AD and psoriasis pathogenesis, an entire work package is dedicated to the investigation of skin and gut microbiome linked to AD or psoriasis. The large collaborative BIOMAP project will enable the integration of patient cohorts, data and knowledge in unprecedented proportions. The project has a unique opportunity with a potential to bridge and fill the gaps between current problems and solutions. This review highlights the power and potential of BIOMAP project in the investigation of microbe-host interplay in AD and psoriasis.

The epidemiology of eczema in children and adults in England: A population-based study using primary care data

BACKGROUND

Whilst eczema is a common inflammatory skin condition, we lack contemporary estimates of disease incidence and prevalence across the lifespan.

OBJECTIVE

To estimate the incidence and prevalence of eczema in children and adults in England and variation by sociodemographic factors (sex, socio-economic status, ethnicity, and geography).

METHODS

We used the Royal College of General Practitioners Research and Surveillance Centre primary care research database of 3.85 million children and adults registered with participating general practitioner practices between 2009 and 2018 inclusive. Eczema incidence was defined as the first-ever diagnosis of eczema recorded in the primary care record, and eczema prevalence was defined as fulfilment of criteria for active eczema (two eczema records appearing in the primary care record within any one-year period).

RESULTS

Eczema incidence was highest in infants younger than 1 year (15.0 per 100 person-years), lowest in adults aged 40-49 (0.35 p/100 person-years), and increased from middle age to a second smaller peak in people 80 years or older (0.79 p/100 person-years). Eczema prevalence was highest in children aged 2 (16.5%) and lowest in adults aged 30-39 (2.8%). Eczema incidence was higher in male infants (<2) and male adults older than 70; for all other ages, incidence was higher in females. Eczema was more common in Asian and black ethnic groups than in people of white ethnicity. Higher socio-economic status was associated with a greater incidence of eczema in infants younger than 2, but the reverse was seen for all other age groups. Both incidence and prevalence of eczema were greater in urban settings and in North-West England.

CONCLUSIONS AND CLINICAL RELEVANCE

Eczema has a bimodal distribution across the lifespan. We observed differences in incidence and prevalence of eczema by ethnicity, geography, sex, and socio-economic status, which varied in magnitude throughout life.

Patterns and trends in eczema management in UK primary care (2009-2018): A population-based cohort study

Background

Despite the high disease burden of eczema, a contemporary overview of the patterns and trends in primary care healthcare utilization and treatment is lacking.

Objective

To quantify primary care consultations, specialist referrals, prescribing, and treatment escalation, in children and adults with eczema in England.

Methods

A large primary care research database was used to examine healthcare and treatment utilization in people with active eczema (n = 411,931). Management trends and variations by age, sex, socioeconomic status, and ethnicity were described from 2009 to 2018 inclusive.

Results

Primary care consultation rates increased from 87.8 (95% confidence interval [95% CI] 87.3–88.3) to 112.0 (95% CI 111.5–112.6) per 100 person‐years over 2009 to 2018. Specialist referral rates also increased from 3.8 (95% CI 3.7–3.9) to 5.0 (95% CI 4.9–5.1) per 100 person‐years over the same period. Consultation rates were highest in infants. Specialist referrals were greatest in the over 50s and lowest in people of lower socioeconomic status, despite a higher rate of primary care consultations. There were small changes in prescribing over time; emollients increased (prescribed to 48.5% of people with active eczema in 2009 compared to 51.4% in 2018) and topical corticosteroids decreased (57.3%–52.0%). Prescribing disparities were observed, including less prescribing of potent and very potent topical corticosteroids in non‐white ethnicities and people of lower socioeconomic status. Treatment escalation was more common with increasing age and in children of non‐white ethnicity.

Conclusion and clinical relevance

The management of eczema varies by sociodemographic status in England, with lower rates of specialist referral in people from more‐deprived backgrounds. There are different patterns of healthcare utilization, treatment, and treatment escalation in people of non‐white ethnicity and of more‐deprived backgrounds.

Epidemiology and management of atopic dermatitis in England: an observational cohort study protocol

INTRODUCTION

Atopic dermatitis (AD) is one of the most common inflammatory skin conditions in both children and adults. Despite this, contemporary descriptions of the incidence, prevalence and current management of the condition in the UK are lacking.

METHODS AND ANALYSIS

We will perform a series of retrospective studies using a large population-based cohort derived from the Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) network database to explore two key research themes: AD epidemiology and AD management.In the epidemiology theme, we will describe the incidence and prevalence of AD in children and adults in England from 2009 to 2018 inclusive. We will stratify findings by age, national Index of Multiple Deprivation (IMD), ethnicity, urban-rural environment and geographic location; and explore independent associations of these features with AD in multivariable models.In the management theme, we will explore healthcare utilisation and treatment in people with AD. Regarding healthcare utilisation, we will evaluate rates of AD-associated primary care visits and specialist dermatology referrals in people with AD. Rates will be stratified by age, gender, socioeconomic IMD quintile and ethnicity. We will describe contemporary treatment by estimating prescribing rates across medication classes used in AD (emollients, topical corticosteroids by potency, topical calcineurin inhibitors, topical antimicrobials, antihistamines, oral corticosteroids and systemic immunomodulatory therapies) overall, and by age and sociodemographic groupings. We will also examine trends in prescribing over the study period. In people first diagnosed with AD during the study period, we will describe differences in treatment escalation by sociodemographic factors using time-to-event analysis.

ETHICS AND DISSEMINATION

The Health Research Authority decision tool classed this a study of 'usual practice', ethics approval was not required. Study approval was granted by the RCGP RSC Study Approval Committee. Results will be disseminated through peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT03823794.

Feasibility of a school-based exercise intervention for children with intellectual disability to reduce cardio-metabolic risk

BACKGROUND

People with intellectual disabilities (ID) are at increased risk of secondary health conditions, reduced quality of life and life expectancy. Children with ID demonstrate low levels of physical activity in association with a higher prevalence of obesity, a modifiable risk factor associated with secondary health conditions including type 2 diabetes and cardiovascular disease. Despite this, physical activity interventions addressing weight and weight-related complications in this population are limited. This study aimed to establish the feasibility of a school-based group exercise intervention for children with moderate to severe ID.

METHODS

A single-arm intervention study was used to establish the feasibility of a 16-week exercise intervention. Children attending a School for Specific Purposes in Sydney, Australia, participated in two 30-min exercise sessions per week across the intervention period in addition to their regular physical education class. Each exercise session was 60% aerobically based, 20% strength based and 20% targeted towards fundamental movement skill development. We used two facilitation strategies to assist the delivery of the intervention, including the implementation of a variety of communication resources and promotion of social interaction. Feasibility was assessed through recruitment rates, program retention, adverse effects, attendance, group size feasibility and non-compliance. Anthropometric measures included height (m), weight (kg) and waist circumference (cm; umbilicus), with body mass index (BMI) and waist-to-height ratios (WtHR) used to determine cardio-metabolic risk. Aerobic capacity was assessed using the submaximal 6-min walk test (6-MWT). Intensity of physical activity sessions was measured through the use of tri-axial accelerometers and compared to physical activity recommendations.

RESULTS

Ten children aged between 9 and 13 years completed the 16-week intervention, with a 55% recruitment rate, 91% program retention, 86% attendance and with no adverse effects reported. Sessions commenced as 1:1 supervisor to child ratios before progressing to established small groups of 2:7 (supervisor : child). Children spent 38.4% (11.5 min) of each session in moderate to vigorous physical activity (MVPA), equating to 20% of their MVPA recommended daily physical activity levels (twice per week). There was a significant change in weight across the intervention period, with a trend towards increased weight between mid-intervention and 3-month follow-up time points. There were no significant changes in child BMI, WtHR or aerobic capacity.

CONCLUSIONS

A school-based group exercise intervention for children with moderate to severe ID is feasible and safe, with high retention rates and physical activity participation. No significant improvements in body composition or aerobic capacity were determined. The present study demonstrates that engaging children with moderate-severe ID in school-based group exercise is feasible to assist in physical activity participation.

Delays in the diagnosis and treatment of bone and joint tuberculosis in the United Kingdom

Aims

Tuberculosis (TB) infection of bones and joints accounts for 6.7% of TB cases in England, and is associated with significant morbidity and disability. Public Health England reports that patients with TB experience delays in diagnosis and treatment. Our aims were to determine the demographics, presentation and investigation of patients with a TB infection of bones and joints, to help doctors assessing potential cases and to identify avoidable delays.

Patients and Methods

This was a retrospective observational study of all adults with positive TB cultures on specimens taken at a tertiary orthopaedic centre between June 2012 and May 2014. A laboratory information system search identified the patients. The demographics, clinical presentation, radiology, histopathology and key clinical dates were obtained from medical records.

Results

A total of 31 adult patients were identified. Their median age was 37 years (interquartile range (IQR): 29 to 53); 21 (68%) were male; 89% were migrants. The main sites affected were joints (10, 32%), the spine (8, 26%) and long bones (6, 19%); 8 (26%) had multifocal disease. The most common presenting symptoms were pain (29/31, 94%) and swelling (26/28, 93%). ‘Typical’ symptoms of TB, such as fever, sweats and weight loss, were uncommon. Patients waited a median of seven months (IQR 3 to 13.5) between the onset of symptoms and referral to the tertiary centre and 2.3 months (IQR 1.6 to 3.4.)) between referral and starting treatment. Radiology suggested TB in 26 (84%), but in seven patients (23%) the initial biopsy specimens were not sent for mycobacterial culture, necessitating a second biopsy. Rapid Polymerase Chain Reaction-based testing for TB using Xpert MTB/RIF was performed in five patients; 4 (80%) tested positive for TB. These patients had a reduced time between the diagnostic biopsy and starting treatment than those whose samples were not tested (median eight days versus 36 days, p = 0.016).

Conclusion

Patients with bone and joint TB experience delays in diagnosis and treatment, some of which are avoidable. Maintaining a high index of clinical suspicion and sending specimens for mycobacterial culture are crucial to avoid missing cases. Rapid diagnostic tests reduce delays and should be performed on patients with radiological features of TB. Cite this article: Bone Joint J 2018;100-B:119–24.

Prophylaxis in real life scenarios

Prophylaxis has become the standard mantra of care for those individuals with severe haemophilia A and B. Primary prophylaxis is advocated to prevent the occurrence of symptomatic acute spontaneous haemarthroses and to preserve joint structure and function. Typically, twice or thrice weekly infusions of factor VIII or IX concentrates are integral to this treatment approach. Secondary prophylaxis is initiated after the relentless cycle of progressive joint damage has been triggered by prior haemarthroses and is intended to preserve existing joint health by preventing additional spontaneous bleeding events. Event-driven prophylaxis involves the administration of clotting factor concentrates to prevent acute traumatic bleeds, which are anticipated to occur in association with surgical or physical trauma. This regimen enhances the effectiveness of primary or secondary prophylaxis protocols or on-demand approaches to replacement therapy. Besides the marked reduction in the so-called annual bleed rate, prophylaxis regimens frequently increase personal self-confidence to embark on a more active and physical lifestyle; however, in reality, prophylaxis must be individualized in accordance with bleeding phenotypes, with the unique pharmacokinetic profile of administered replacement clotting factor concentrates, with the specific clinical scenario, and with the degree of intensity anticipated for any physical activity. The introduction of extended half-life replacement products will also influence how these prophylaxis regimens will be accomplished. The following scenarios will discuss how prophylaxis regimens can be implemented to protect the individual from developing spontaneous and activity-induced acute bleeding complications and to maintain an improved quality of life.

Stable rAAV-mediated transduction of rod and cone photoreceptors in the canine retina

Recombinant adeno-associated virus (rAAV) vectors are attractive candidates for the treatment of inherited and acquired retinal disease. Although rAAV vectors are well characterized in rodent models, a prerequisite to their clinical application in human patients is the thorough evaluation of their efficacy and safety in intermediate animal models. In this study, we describe rAAV-2-mediated expression of GFP reporter gene in retinal cells following local vector delivery in dogs. Subretinal delivery of rAAV.CMV.GFP was performed unilaterally in eight normal dogs from 6 weeks of age. The area of retinal transduction was maximized by the optimization of surgical techniques for subretinal vector delivery by pars-plana vitrectomy and the use of fine-gauge subretinal cannulae to create multiple retinotomies. rAAV-2 vectors mediated efficient stable reporter gene expression in photoreceptors and retinal pigment epithelial cells. We found efficient transduction of cone photoreceptors in addition to rods in both the canine retina and after subretinal vector delivery in another intermediate animal model, the feline retina. GFP expression in dogs was confined to the area of the retinal bleb and was sustained in cells at this site for at least 18 months. Electroretinography demonstrated a modest reduction in global rod-mediated retinal function following subretinal delivery of rAAV.CMV.GFP. Three of the eight animals developed delayed-onset intraocular inflammation, in two cases associated with a serum antibody response to GFP protein. We conclude that rAAV-2 vectors mediate efficient sustained transgene expression in rod and cone photoreceptors following subretinal delivery in this intermediate animal model. The possibility of adverse effects including intraocular immune responses and reduced retinal function requires further investigation prior to clinical applications in patients.

Distribution of OX2 antigen and OX2 receptor within retina

PURPOSE

OX2 is a member of the immunoglobulin superfamily expressed on a broad range of tissues including neurons of the central and peripheral nervous systems, thymocytes, and endothelium. The recently identified OX2 receptor (OX2R) is restricted to the surfaces of myeloid lineage cells, including microglia. Functional data have implicated the OX2-OX2R interaction as a myeloid downregulatory signal. The purpose of this study was to determine the distribution and extent of expression of OX2 and its receptor within the retina, a tissue developed to restrain immune-mediated inflammatory damage.

METHODS

OX2 and OX2R monoclonal antibodies (mAbs) were used to determine OX2 and OX2R protein expression, respectively, by flow cytometry of isolated myeloid-derived cells from normal and inflamed rat retina and by immunohistochemistry of serial sections of rat retina. For comparison, distribution of OX2 was documented using species-specific monoclonal antibodies in mouse and human retina. No OX2R mAbs are available for mouse or human detection.

RESULTS

OX2 was expressed on retinal vascular endothelium and glial fibrillary acidic protein (GFAP)-negative neurons in retina and optic nerve and on a subpopulation of CD45(+) perivascular and juxtavascular cells. Within normal retina, OX2R was not detected on myeloid-derived cells. During experimental autoimmune uveoretinitis (EAU), expression of both OX2 and OX2R was noted on infiltrating leukocytes.

CONCLUSIONS

Taking these results of the distribution of OX2 in normal and OX2R in inflamed retina with other functional data of OX2-OX2R interaction, it is suggested that the OX2-OX2R interaction has the potential to contribute to a novel pathway that suppresses and limits immunologic inflammatory damage within the retina.

IFN-gamma and LPS-mediated IL-10-dependent suppression of retinal microglial activation

PURPOSE

Human retinal microglia (MG) express constitutively major histocompatability complex (MHC) class II molecules and have thus been highlighted as potential immunocompetent antigen-presenting cells (APCs). This study was undertaken to characterize microglial expression of coaccessory molecules and the functional changes in antigen expression, cytokine production, migration, and phagocytosis after proinflammatory stimulation.

METHODS

Fresh donor retinal MG were obtained and isolated using a percoll density gradient technique. Phenotypic characteristics used for isolating rodent microglia were applied and modified. Coaccessory molecule expression and intracellular cytokine production were assessed using three-color flow cytometric analysis in both freshly isolated and interferon (IFN)gamma-lipopolysaccharide (LPS)-stimulated MG. Using five-millimeter retinal explants in culture, microglial migratory behavior, changes in cell surface antigen expression and phagocytic activity were documented.

RESULTS

MG could be clearly defined by the flow cytometric phenotype CD45low CD11b+ MHC class II+ CD86low CD40low. Freshly isolated MG showed mannose receptor-mediated uptake of dextran-FITC. MG migrated from explants, were adherent, and upregulated MHC class II expression. After IFNgamma-LPS stimulation of single-cell suspension of MG isolates, MHC class II expression was reduced, with an increase occurring in MG intracellular interleukin (IL)-10 and IL-10 production. Microglial migration from explants was reduced after IFNgamma-LPS stimulation.

CONCLUSIONS

These results highlight both phenotypic and behavioral characteristics that support an antigen-processing and -presenting capability of freshly isolated MG. However, proinflammatory stimulation with IFNgamma-LPS induces an IL-10-mediated downregulation of cell surface antigen expression and loss of migratory and phagocytic activity. Therefore, although equipped to act as APCs, MG are able to rapidly modulate their own function and behavior and as a result may have the potential to limit inflammation.

Fas-Fas ligand-mediated apoptosis within aqueous during idiopathic acute anterior uveitis

PURPOSE

Despite ocular immune privilege, (auto)immune-mediated acute anterior uveitis (AAU) is relatively common. However, although relapses of AAU are usually self-limiting, possible regulatory mechanisms remain undefined in humans. Experimentally, Fas-Ligand (FasL)-mediated apoptosis of Fas+ inflammatory cells contributes to the immune privilege within the anterior chamber and provides an explanation for the success of corneal allograft transplantation. Therefore, whether such mechanisms regulate the immune response in AAU was investigated.

METHODS

Aqueous and peripheral blood samples from consecutive patients presenting with idiopathic AAU were obtained with consent. Leukocytic phenotype was analyzed by flow cytometry, and apoptosis was determined by both flow cytometry and TdT-dUTP terminal nick-end labeling analysis. Presence of soluble Fas and FasL was determined by western blot analysis and enzyme-linked immunosorbent assay and compared with control aqueous from patients undergoing cataract surgery. The ability of the aqueous to induce apoptosis in a Fas+ Jurkat cell line was also determined.

RESULTS

During AAU aqueous-infiltrating Fas+ cells included CD3+ T cells and granulocytes, whereas FasL+ cells comprised predominantly of non-CD3+ T cells. Higher levels of functional soluble FasL were found in aqueous of AAU patients than in normal aqueous, capable of inducing apoptosis in 68.9% +/- 7.6% of Fas+ lymphoid cells. Compared with peripheral blood, the CD4+ T cells infiltrate within aqueous showed significantly increased CD69 and CD25(IL-2r) expression. Flow cytometric analysis of aqueous showed that 9.32% +/- 1.2% of infiltrating non-granulocyte CD45+ cells were apoptotic, confirmed as T cells on subsequent three-color flow cytometric analysis.

CONCLUSIONS

Taken together with published experimental data, the present study provides evidence for FasL-mediated apoptotic cell death contributing to the local immune regulation of ocular inflammatory disease and provides a mechanism to account for the self-limiting clinical course of AAU.

Instrument performance in bone density testing at five Australian centres

AIMS

To assess the in vitro precision and accuracy of bone mineral densitometry (BMD) within and between locations at five Australian centres.

METHODS

Using a multicentre reliability study the accuracy and short- and long-term precision of dual-energy X-ray absorptiometry (DXA) in vitro was compared on five instruments. Measures were performed using pencil beam mode on four Hologic QDR-2000 densitometers and one Hologic QDR-1000/W (Hologic Inc, Waltham, MA).

RESULTS

Short-term precision of bone mineral density measurement was less than 0.5% for spine phantoms (n = 10 for each centre, mean intrasite coefficient of variation [CV] 0.39 +/- 0.09% [SD]) and for hip phantoms (n = 10 for each centre, mean intrasite coefficient of variation [CV] 0.34 +/- 0.10% [SD]). Between-centre measurement (n = 10 for each phantom) of a single spine phantom and a single hip phantom (specified mineral contents-58.5 g and 38.6 g, respectively) revealed ranges of bone mineral content of 57.7-58.1 g (all-point CV = 0.52%) and 37.1-37.8 g (all-point CV = 0.70%), respectively. When results from pairs of machines were compared there were statistically different mean BMD results for the majority of the ten possible pairings for both spine and hip measurements. Each study centre measured in vitro stability of phantom BMD measurements over a one year period (n = 45-283, median 157 for spine; and n = 0-262, median 38, for hip); CVs ranged from 0.38 to 0.53% for the spine measurements and from 0.38 to 0.54% for the hip measurements. The mean all-point accuracy of the spine phantom measurements was 99.1% and the hip phantom measurements was 96.7%.

CONCLUSIONS

Across a number of instruments DXA demonstrates in vitro all-point precision of 0.5% for the spine phantom and 0.7% for the hip phantom. The instrument demonstrates accuracy of greater than 99% at the spine and 96% at the hip. This finding has clinical, research and quality control implications.

Effect of colony-stimulating factors on number and function of circulating monocytes in normal dogs

Recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) and recombinant canine granulocyte colony-stimulating factor (rcG-CSF) were administered to normal dogs, and effect on monocyte number and function was evaluated. rhuGM-CSF, administered for 14 days, induced a 2.5-fold increase in monocyte counts on day 3. Leukocytes increased two-fold after 1 day. Counts peaked on day 11, then declined, approaching pretreatment counts by day 15. On day 7, in vivo monocyte cytostasis activity was significantly enhanced, and declined on day 14. rcG-CSF induced a 4.5-fold increase in monocyte counts on day 3. Leukocyte counts increased three-fold after 1 day. Increased counts were maintained for 69 days, at which time treatment was discontinued. There was no effect of rcG-CSF on in vivo monocyte cytostasis activity on days 7 and 14.