Capillary leak syndrome was associated with more severe multisystem inflammatory syndrome in children during the COVID-19 pandemic

AIM

This population-based study investigated the occurrence of capillary leak syndrome (CLS) in children with multisystem inflammatory syndrome in children (MIS-C), associated with COVID-19. We also examined associations between CLS and MIS-C disease severity.

METHODS

All eligible individuals aged 0-18 years, who were diagnosed with MIS-C in Skåne, southern Sweden, from 1 April 2020 to 31 July 2021, were studied. They were all included in the Pediatric Rheumatology Quality Register and clinical and laboratory data were compared between patients with and without CLS.

RESULTS

We included 31 patients (61% male) with MIS-C in the study. The median age at diagnosis was 10.6 years (range 1.99-17.15) and 45% developed CLS. All six patients who required intensive care had CLS. Patients with CLS also had a higher incidence of reduced cardiac function, measured as low ejection fraction. The CLS group exhibited significantly higher C-reactive protein values (p < 0.001) and N-terminal pro-B-type natriuretic peptide levels (p < 0.001), as well as lower platelet counts (p = 0.03), during the first week of treatment. Individuals with CLS also received more intense immunosuppression.

CONCLUSION

CLS was a common complication of MIS-C in our study and these patients had a more severe disease course that required more intensive treatment.

Synovial monocytes contribute to chronic inflammation in childhood-onset arthritis via IL-6/STAT signalling and cell-cell interactions

Introduction

Monocytes are key effector cells in inflammatory processes. We and others have previously shown that synovial monocytes in childhood-onset arthritis are activated. However, very little is known about how they contribute to disease and attain their pathological features. Therefore, we set out to investigate the functional alterations of synovial monocytes in childhood-onset arthritis, how they acquire this phenotype, and whether these mechanisms could be used to tailorize treatment.

Methods

The function of synovial monocytes was analysed by assays believed to reflect key pathological events, such as T-cell activation-, efferocytosis- and cytokine production assays using flow cytometry in untreated oligoarticular juvenile idiopathic arthritis (oJIA) patients (n=33). The effect of synovial fluid on healthy monocytes was investigated through mass spectrometry and functional assays. To characterize pathways induced by synovial fluid, we utilized broad-spectrum phosphorylation assays and flow cytometry, as well as inhibitors to block specific pathways. Additional effects on monocytes were studied through co-cultures with fibroblast-like synoviocytes or migration in transwell systems.

Results

Synovial monocytes display functional alterations with inflammatory and regulatory features, e.g., increased ability to induce T-cell activation, resistance to cytokine production following activation with LPS and increased efferocytosis. In vitro, synovial fluid from patients induced the regulatory features in healthy monocytes, such as resistance to cytokine production and increased efferocytosis. IL-6/JAK/STAT signalling was identified as the main pathway induced by synovial fluid, which also was responsible for a majority of the induced features. The magnitude of synovial IL-6 driven activation in monocytes was reflected in circulating cytokine levels, reflecting two groups of low vs. high local and systemic inflammation. Remaining features, such as an increased ability to induce T-cell activation and markers of antigen presentation, could be induced by cell-cell interactions, specifically via co-culture with fibroblast-like synoviocytes.

Conclusions

Synovial monocytes in childhood-onset arthritis are functionally affected and contribute to chronic inflammation, e.g., via promoting adaptive immune responses. These data support a role of monocytes in the pathogenesis of oJIA and highlight a group of patients more likely to benefit from targeting the IL-6/JAK/STAT axis to restore synovial homeostasis.

The risk of depression and anxiety is not increased in individuals with juvenile idiopathic arthritis - results from the south-Swedish juvenile idiopathic arthritis cohort

BACKGROUND

Children with chronic diseases are reported to have increased risk of psychiatric comorbidity. Few studies have investigated this risk in juvenile idiopathic arthritis (JIA), with conflicting results. We performed a population-based, longitudinal cohort study of the risk of depression and anxiety in south-Swedish patients with juvenile arthritis.

METHODS

The south-Swedish JIA cohort (n = 640), a population-based cohort with validated JIA diagnosis 1980 - 2010 and comparators, a reference group of 3200 individuals free from JIA, matched for sex, year of birth and residential region, was used. Data on comorbid diagnosis with depression or anxiety were obtained from the Skåne Healthcare Register, containing all healthcare contacts in the region, from 1998 to 2019. We used Cox proportional models for the calculation of hazard ratios.

RESULTS

During the study period, 1998 to 2019, 93 (14.5%) of the individuals in the JIA group were diagnosed with depression, and 111 (17.3%) with anxiety. Corresponding numbers among the references was 474 (14.8%) with depression and 557 (17.4%) with anxiety. Hazard ratio for depression was 1.1 (95% CI 0.9 - 1.5) in females and 0.8 (95% CI 0.5 - 1.4) in males, and for anxiety 1.2 (95% CI 0.9 - 1.5) in females and 0.6 (95% CI 0.4 - 1.1) in males. There were no statistically significant hazard ratios when analyzing subgroups of JIA patients with long disease duration or treatment with disease-modifying antirheumatic drugs.

CONCLUSIONS

Individuals with JIA do not have any statistically increased risk of being diagnosed with depression or anxiety compared to matched references.

Uveitis associated with juvenile arthritis: a continued cohort study 40 years after uveitis onset

BACKGROUND

A third follow-up study, mean 40.7 years after uveitis onset, of a cohort originally consisting of 55 Swedish patients with uveitis associated with juvenile arthritis.

METHOD

A retrospective study of the patients' ophthalmic medical records. The results were compared to those of the same cohort previously studied at mean 7.2 and 24.0 years after uveitis onset. In the present follow-up study, 30 of the original 55 patients consented to participate. Of these, 26 had ophthalmic medical records that were reviewed.

RESULTS

In the 30 participants, active uveitis was seen in 43.4%, cataracts in 66.6% and glaucoma in 40.0%. When comparing data from previous follow-ups of the same cohort, a total of 61.8% were reported to have had cataracts at any of the three follow-ups, 29.0% had glaucoma or ocular hypertension and 12.7% had severe visual impairment in both eyes. At mean 40.7 years after uveitis onset 20% of patients in the original uveitis cohort were deceased. In 4 of the 11 deceased individuals, rheumatic disease was stated as the main cause of death, and in 3 it was considered a contributory factor in the patients deaths.

CONCLUSIONS

Uveitis associated with juvenile arthritis can be active into midlife and possibly longer. Ocular complications and visual loss increased up to 40 years after uveitis diagnosis. The mortality rate of this cohort was higher than that of a corresponding Swedish population. Lifelong ophthalmic check-ups are probably necessary for patients diagnosed with this type of uveitis.

POS0951 SERUM PROTEIN RESPONSE TO A SINGLE HIGH-INTENSITY INTERVAL TRAINING BOUT – COMPARISON BETWEEN INDIVIDUALS WITH SPONDYLOARTHRITIS AND HEALTHY CONTROLS

Background

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease affecting mainly the axial skeleton. To decrease the risk of cardiovascular comorbidity, aerobic training is recommended as a part of disease management in patients with axSpA. High-intensity interval training (HIIT) interventions are, in addition to other recommended treatments, believed to positively affect the disease activity (1). However, the knowledge about the acute effects of HIIT on the inflammatory process at the molecular level is less studied. Understanding the acute HIIT effects on cytokines and additional serum proteins in axSpA is important for further long-term HIIT interventions and recording of the effect of HIIT on the axSpA disease profile.

Objectives

To study the acute effects on serum proteins, such as cytokines, myokines, and inflammatory- and bone-related proteins, in response to a single bout of HIIT, and to compare the levels between baseline and post-HIIT in patients with axSpA and healthy controls (HC).

Methods

The pilot study included twenty-one participants (10 female, 11 male), mean (SD) age 40 (7) years, ten with axSpA, and eleven age and sex matched HC, who performed a single HIIT on a cycle ergometer consisting of 4x4 minutes interval (90% heart rate, HR-max) with three minutes active rest in between (70% of HR-max). Disease activity (BASDAI, 0-10) in patients with axSpA was 1.6 (0.8). Health status EuroQol (EQ5D, 0-1) were 0.87 (0.11) for axSpA, and 0.93 (0.10) for HC. The groups were well matched with no difference in baseline data for weight, BMI, EQ5D, blood pressure or aerobic capacity.

Blood samples were taken before (baseline) and one hour after the single HIIT. The following serum proteins were analyzed on a Luminex MAGPIX System (Luminex corporation, Austin, TX USA): Interleukin (IL)-6, IL-17, IL-18, TNFαAGPIX System (Luminex corporatiosteoprotegerin, osteocalcin, osteopontin, and FGF-23. A three-way analysis of variance (ANOVA) was used to detect differences between groups, between sexes, and before and after a HIIT bout in a 2(group)*2(sex)*2(time) design. For main effects or interactions significant at p≤0.05, simple effect t-tests were used to determine the specific effects.

Results

A group main effect (p=0.048) showed that the serum level of IL-6 was increased one hour after the HIIT session primarily in the HC, 0.4 pg/ml (SD±0.4) at baseline vs. post-HIIT 1.8 (2.0). The concentration of the cytokines/chemokine IL-17, IL-18, TNFα group main effect (p=0.048) showed that the serum level of IL-6 was increased one hour after the HIIT session primarily in30) in VEGF-A showed that the axSpA group had significantly lower VEGF-A at baseline, 159 pg/ml (138) vs 326 (184) in the control group (which might be due to anti-inflammatory medication). A sex main effect (p=0.029) was observed from baseline to post-HIIT for the bone hormone osteocalcin, with a more pronounced decrease of serum osteocalcin in women with axSpA, 14.0 ng/ml (8.3) vs. post HIIT 13.2 (6.9). Moreover, the level of the multifunctional protein osteopontin was significantly lower (sex main effect, p=0.021) in women, 10.7 ng/ml (7.0) vs. men 20.4 (10.1), post-HIIT.

Conclusion

This pilot study shows that one bout of HIIT influences the expression of proteins involved in inflammation and metabolism, and that sex is an important factor in the response to HIIT. The results should be followed up in longer intervention studies including higher numbers of participants.

References

[1]Sveaas, S. H. et al. (2019). High intensity exercise for 3 months reduces disease activity in axial spondyloarthritis (axSpA): a multicentre randomised trial of 100 patients. British journal of sports medicine, 54(5), 292-297.

Disclosure of Interests

Åsa Andersson: None declared, Emma Haglund Consultant of: Novartis, Emma Berthold: None declared, Elisabeth Mogard Consultant of: Novartis, Anna Torell: None declared, M Charlotte Olsson: None declared

Neutrophils Lose the Capacity to Suppress T Cell Proliferation Upon Migration Towards Inflamed Joints in Juvenile Idiopathic Arthritis

Neutrophils are highly abundant in synovial fluid of rheumatic inflamed joints. In oligoarticular juvenile idiopathic arthritis (JIA), synovial fluid neutrophils have impaired effector functions and altered phenotype. We hypothesized that these alterations might impact the immunoregulatory interplay between neutrophils and T cells. In this study we analyzed the suppressive effect of neutrophils, isolated from blood and synovial fluid of oligoarticular JIA patients, on CD4⁺ T cells activated by CD3/CD28 stimulation. JIA blood neutrophils suppressed T cell proliferation but synovial fluid neutrophils from several patients did not. The loss of T cell suppression was replicated in an in vitro transmigration assay, where healthy control neutrophils migrated into synovial fluid through transwell inserts with endothelial cells and synoviocytes. Non-migrated neutrophils suppressed proliferation of activated CD4⁺ T cells, but migrated neutrophils had no suppressive effect. Neutrophil suppression of T cells was partly dependent on reactive oxygen species (ROS), demonstrated by impaired suppression in presence of catalase. Migrated neutrophils had reduced ROS production compared to non-migrated neutrophils. A proteomic analysis of transwell-migrated neutrophils identified alterations in proteins related to neutrophil ROS production and degranulation, and biological processes involving protein transport, cell-cell contact and inflammation. In conclusion, neutrophils in synovial fluid of children with JIA have impaired capacity to suppress activated T cells, which may be due to reduced oxidative burst and alterations in proteins related to cell-cell contact and inflammation. The lack of T cell suppression by neutrophils in synovial fluid may contribute to local inflammation and autoimmune reactions in the JIA joint.

Population-based study of multisystem inflammatory syndrome associated with COVID-19 found that 36% of children had persistent symptoms

Aim

Our aim was to describe the outcomes of multisystem inflammatory syndrome in children (MIS‐C) associated with COVID‐19.

Methods

This national, population‐based, longitudinal, multicentre study used Swedish data that were prospectively collected between 1 December 2020 and 31 May 2021. All patients met the World Health Organization criteria for MIS‐C. The outcomes 2 and 8 weeks after diagnosis are presented, and follow‐up protocols are suggested.

Results

We identified 152 cases, and 133 (87%) participated. When followed up 2 weeks after MIS‐C was diagnosed, 43% of the 119 patients had abnormal results, including complete blood cell counts, platelet counts, albumin levels, electrocardiograms and echocardiograms. After 8 weeks, 36% of 89 had an abnormal patient history, but clinical findings were uncommon. Echocardiogram results were abnormal in 5% of 67, and the most common complaint was fatigue. Older children and those who received intensive care were more likely to report symptoms and have abnormal cardiac results.

Conclusion

More than a third (36%) of the patients had persistent symptoms 8 weeks after MIS‐C, and 5% had abnormal echocardiograms. Older age and higher levels of initial care appeared to be risk factors. Structured follow‐up visits are important after MIS‐C.

Identification of novel autoantigens as potential biomarkers in juvenile idiopathic arthritis associated uveitis

BACKGROUND

Many children with juvenile idiopathic arthritis (JIA) have autoantibodies, targeting nuclear components (anti-nuclear antibodies, ANA). ANA in JIA is associated with uveitis, an eye inflammation which may cause permanent vision impairment if not detected and treated. However, ANA-testing is neither specific nor sensitive enough to be a clinically reliable predictor of uveitis risk, and the precise autoantigens targeted by ANA in JIA are largely unknown. If identified, specific autoantibodies highly associated with uveitis could be used as biomarkers to facilitate identification of JIA patients at risk.

METHODS

Antibodies from six ANA-positive, oligoarticular JIA patients, with and without uveitis, were explored by two large-scale methods: (1) screening against 42,100 peptides on an autoimmunity profiling planar array, and (2) immunoprecipitations from cell lysates with antigen identification by mass spectrometry. Three hundred thirty-five peptide antigens, selected from proteins identified in the large-scale methods and the scientific literature were investigated using a bead-based array in a cohort of 56 patients with oligoarticular- or RF-negative polyarticular JIA, eight of which were having current or previous uveitis.

RESULTS

In the planar array, reactivity was detected against 332 peptide antigens. The immunoprecipitations identified reactivity towards 131 proteins. Only two proteins were identified by both methods. In the bead-based array of selected peptide antigens, patients with uveitis had a generally higher autoreactivity, seen as higher median fluorescence intensity (MFI) across all antigens, compared to patients without uveitis. Reactivity towards 17 specific antigens was significantly higher in patients with uveitis compared to patients without uveitis. Hierarchical clustering revealed that patients with uveitis clustered together.

CONCLUSION

This study investigated autoantigens in JIA and uveitis, by combining two exploratory methods and confirmation in a targeted array. JIA patients with current or a history of uveitis had significantly higher reactivity towards 17 autoantigens and a generally higher autoreactivity compared to JIA patients without uveitis. Hierarchical clustering suggests that a combination of certain autoantibodies, rather than reactivity towards one specific antigen, is associated with uveitis. Our analysis of autoantibodies associated with uveitis in JIA could be a starting point for identification of prognostic biomarkers useful in JIA clinical care.

Synovial fluid neutrophils in oligoarticular juvenile idiopathic arthritis have an altered phenotype and impaired effector functions

Background

Neutrophils are the most prevalent immune cells in the synovial fluid in inflamed joints of children with oligoarticular juvenile idiopathic arthritis (JIA). Despite this, little is known about neutrophil function at the site of inflammation in JIA and how local neutrophils contribute to disease pathogenesis. This study aimed to characterize the phenotype and function of synovial fluid neutrophils in oligoarticular JIA.

Methods

Neutrophils obtained from paired blood and synovial fluid from patients with active oligoarticular JIA were investigated phenotypically (n = 17) and functionally (phagocytosis and oxidative burst, n = 13) by flow cytometry. In a subset of patients (n = 6), blood samples were also obtained during inactive disease at a follow-up visit. The presence of CD206-expressing neutrophils was investigated in synovial biopsies from four patients by immunofluorescence.

Results

Neutrophils in synovial fluid had an activated phenotype, characterized by increased CD66b and CD11b levels, and most neutrophils had a CD16^hi CD62L^lowaged phenotype. A large proportion of the synovial fluid neutrophils expressed CD206, a mannose receptor not commonly expressed by neutrophils but by monocytes, macrophages, and dendritic cells. CD206-expressing neutrophils were also found in synovial tissue biopsies. The synovial fluid neutrophil phenotype was not dependent on transmigration alone. Functionally, synovial fluid neutrophils had reduced phagocytic capacity and a trend towards impaired oxidative burst compared to blood neutrophils. In addition, the effector functions of the synovial fluid neutrophils correlated negatively with the proportion of CD206⁺ neutrophils.

Conclusions

Neutrophils in the inflamed joint in oligoarticular JIA were altered, both regarding phenotype and function. Neutrophils in the synovial fluid were activated, had an aged phenotype, had gained monocyte-like features, and had impaired phagocytic capacity. The impairment in phagocytosis and oxidative burst was associated with the phenotype shift. We speculate that these neutrophil alterations might play a role in the sustained joint inflammation seen in JIA.

Children with oligoarticular juvenile idiopathic arthritis have skewed synovial monocyte polarization pattern with functional impairment-a distinct inflammatory pattern for oligoarticular juvenile arthritis

BACKGROUND

Juvenile idiopathic arthritis (JIA) is an umbrella term of inflammatory joint diseases in children. Oligoarthritis is the most common form in the Western world, representing roughly 60% of all patients. Monocytes and macrophages play an important role in adult arthritides, but their role in oligoarticular JIA is less studied. Polarization highly influences monocytes' and macrophages' effector functions, broadly separated into pro-inflammatory M1 or anti-inflammatory M2 phenotypes. Here, we set out to investigate the polarization pattern and functional aspects of synovial monocytes in oligoarticular juvenile idiopathic arthritis (JIA).

METHODS

Paired synovial fluid, blood samples (n = 13), and synovial biopsies (n = 3) were collected from patients with untreated oligoarticular JIA. Monocytes were analyzed for polarization markers by flow cytometry and qPCR. Effector function was analyzed by a phagocytosis assay. Polarization of healthy monocytes was investigated by stimulation with synovial fluid in vitro. Monocyte/macrophage distribution, polarization, and mRNA expression were investigated in biopsies by immunohistochemistry, immunofluorescence, and in situ hybridization.

RESULTS

Children with oligoarticular JIA have polarized synovial fluid monocytes of a specific M1(IFNγ)/M2(IL-4)-like pattern. This was evidenced by increased surface expression of CD40 (p < 0.001), CD86 (p < 0.001), and CD206 (p < 0.001), but not CD163, as compared to paired circulating monocytes. Additionally, polarization was extensively explored at the mRNA level and synovial fluid monocytes differentially expressed classical markers of M1(IFNγ)/M2(IL-4) polarization compared to circulating monocytes. Synovial fluid monocytes were functionally affected, as assessed by reduced capacity to phagocytose (p < 0.01). Synovial fluid induced M2 markers (CD16 and CD206), but not M1 (CD40) or CD86 in healthy monocytes and did not induce cytokine production. Single and co-expression of surface CD40 and CD206, as well as mRNA expression of IL-10 and TNF, was observed in monocytes/macrophages in synovial biopsies.

CONCLUSION

Children with untreated oligoarticular JIA have similar and distinct synovial fluid monocyte polarization pattern of mixed pro- and anti-inflammatory features. This pattern was not exclusively a result of the synovial fluid milieu as monocytes/macrophages in the synovial membrane show similar patterns. Our study highlights a distinct polarization pattern in oligoarticular JIA, which could be utilized for future treatment strategies.

Outcome in juvenile idiopathic arthritis: a population-based study from Sweden

BACKGROUND

As the treatment arsenal for children with juvenile idiopathic arthritis (JIA) has expanded during the last decades, follow-up studies are needed on children diagnosed in the era of biological treatment to evaluate if this has improved the outcome. Our aim was to study the epidemiology and outcome of JIA in southern Sweden using a population-based cohort of children with a validated diagnosis of JIA collected over 9 years.

METHODS

Potential cases of JIA between 2002 and 2010 were collected after a database search, using the ICD codes M08-M09. The study area was Skåne, the southernmost county of Sweden (population 1.24 million; 17.6% aged < 16 years). The JIA diagnosis was validated and subcategorized through medical record review based on the criteria defined by the International League of Associations for Rheumatism (ILAR). Parameters on disease activity and pharmacologic treatment were recorded annually until the end of the study period (December 31, 2015).

RESULTS

In total, 251 cases of JIA were confirmed. The mean annual incidence rate for JIA was estimated to be 12.8/100,000 children < 16 years, with the highest age-specific annual incidence at the age of 2 years (36/100,000). Oligoarthritis was the largest subgroup (44.7%), and systemic JIA was the smallest subgroup (2.8%). Methotrexate was the most common disease-modifying anti-rheumatic drug prescribed (60.6%). Tumor necrosis factor alpha inhibitors were used as treatment for 23.9% of the children. Only 40.0% of the follow-up years, with a median follow-up time of 8 years, were free of arthritis or uveitis. Uveitis occurred in 10.8% of the children (8.0% chronic uveitis), and the need for joint corrective orthopedic surgery was 9.2%.

CONCLUSIONS

The incidence of JIA in this well-defined, population-based cohort is slightly lower than in previously published studies from Scandinavia. The need for orthopedic surgery and the presence of uveitis are diminished compared to studies with patients diagnosed more than 20 years ago. Children with JIA however still experience disease activity more than 50% of the time. In conclusion, we still have long-term challenges in the care for children with JIA, in spite of state-of-the-art treatment.

Circulating complexes between tumour necrosis factor-alpha and etanercept predict long-term efficacy of etanercept in juvenile idiopathic arthritis

Aim

The relationship between tumour necrosis factor‐alpha (TNF‐α) and drug survival had not been studied in juvenile idiopathic arthritis (JIA), and there were no laboratory tests to predict the long‐term efficacy of biological drugs for JIA. We studied whether serum levels of TNF‐α, free or bound to etanercept, could predict long‐term efficacy of etanercept in children with JIA.

Methods

We included 41 biologic‐naïve patients with JIA who started treatment with etanercept at Skåne University Hospital between 1999 and 2010. Serum taken at the start of treatment and at the six‐week follow‐up were analysed for TNF‐α and the long‐term efficacy of etanercept was assessed using the drug survival time.

Results

Levels of TNF‐α increased significantly at the six‐week follow‐up, and this was almost exclusively comprised of TNF‐α in complex with etanercept. The increase in TNF‐α showed a dose‐dependent correlation to long‐term drug survival (p < 0.01).

Conclusion

Increasing levels of circulating TNF‐α at treatment initiation predicted long‐term efficacy of etanercept in children with JIA, which may have been due to different pathophysiological mechanisms of inflammation. Our result may provide a helpful clinical tool, as high levels of circulating TNF‐α/etanercept complexes could be used as a marker for the long‐term efficacy of etanercept.

Continuation of TNF blockade in patients with inflammatory rheumatic disease. An observational study on surgical site infections in 1,596 elective orthopedic and hand surgery procedures

BACKGROUND

Increased infection risk in inflammatory rheumatic diseases may be due to inflammation or immunosuppressive treatment. The influence of tumor necrosis factor (TNF) inhibitors on the risk of developing surgical site infections (SSIs) is not fully known. We compared the incidence of SSI after elective orthopedic surgery or hand surgery in patients with a rheumatic disease when TNF inhibitors were continued or discontinued perioperatively.

PATIENTS AND METHODS

We included 1,551 patients admitted for elective orthopedic surgery or hand surgery between January 1, 2003 and September 30, 2009. Patient demographic data, previous and current treatment, and factors related to disease severity were collected. Surgical procedures were grouped as hand surgery, foot surgery, implant-related surgery, and other surgery. Infections were recorded and defined according to the 1992 Centers for Disease Control definitions for SSI. In 2003-2005, TNF inhibitors were discontinued perioperatively (group A) but not during 2006-2009 (group B).

RESULTS

In group A, there were 28 cases of infection in 870 procedures (3.2%) and in group B, there were 35 infections in 681 procedures (5.1%) (p = < 0.05). Only foot surgery had significantly more SSIs in group B, with very low rates in group A. In multivariable analysis with groups A and B merged, only age was predictive of SSI in a statistically significant manner.

INTERPRETATION

Overall, the SSI rates were higher after abolishing the discontinuation of anti-TNF perioperatively, possibly due to unusually low rates in the comparator group. None of the medical treatments analyzed, e.g. methotrexate or TNF inhibitors, were significant risk factors for SSI. Continuation of TNF blockade perioperatively remains a routine at our center.

cis-acting elements in human immunodeficiency virus type 1 RNAs direct viral transcripts to distinct intranuclear locations

Two distinct intranuclear locations were identified for alternatively spliced RNA transcripts expressed from the pNL4-3 infectious molecular clone of human immunodeficiency virus (HIV) type 1. Multiply spliced HIV RNA encoding tat was detected within the nucleus in large clusters; immunostaining and colocalization studies using laser-scanning confocal microscopy revealed that these structures contained the non-small nuclear ribonucleoprotein RNA processing factor, SC35. In contrast, unspliced gag RNA was detected in much smaller granules distributed throughout the nucleus, with little or no association with SC35-containing granules. Analyses of nuclear RNA expressed from recombinant plasmids encoding gag (pCMVgag-2) alone or tat (pCMVtat-2) alone revealed distributions corresponding to those obtained with pNL4-3, indicating that expression within the context of the HIV provirus was not required for the distinct RNA locations detected for these transcripts. The presence of unspliced gag RNA in small granules was confirmed in infections of H9 T-lymphocytic cells, indicating that gag localization was not restricted to transient expression systems. The intranuclear distribution of gag RNA was dependent on specific RNA sequences. Deletion of a portion of the gag gene of pCMVgag-2, containing a cis-repressing inhibitory region, resulted in redirection of unspliced gag RNA from small granules into large SC35-containing clusters. The addition of the Rev-responsive element, RRE, to the deleted pCMVgag-2 construct resulted in RNA transcripts which were no longer associated with SC35. We also identified a cellular intron, rabbit beta-globin-intervening sequence 2 (IVS-2) which, when introduced into pCMVgag-2, redirected unspliced gag RNA into SC35-containing granules and permitted rev-independent Gag expression. These findings suggest that redirecting intranuclear RNA localization may influence gene expression. Color micrographs from this article are available for view at http//128.231.216.2/lmmhome.htm.

Rapid induction of apoptosis by cell-to-cell transmission of human immunodeficiency virus type 1

The kinetics of human immunodeficiency virus type 1 (HIV-1)-induced cell death were investigated in cell-to-cell and cell-free models of virus transmission. Cocultivation of HIV-1 chronically infected H9 donor cells with uninfected H9 recipient cells resulted in rapid induction of programmed cell death. Within 8 h, apoptotic chromatin condensation was identified by histologic staining. In addition, many single cells with apoptotic nuclei were observed, indicating that stable cell fusion was not a requirement for apoptosis to occur. By 12 to 18 h of coculture, a DNA fragmentation ladder characteristic of apoptosis was detected by agarose gel electrophoresis. Quantitation of apoptosis by measurement of nuclear DNA content revealed that at least 20 to 30% of the nuclei were undergoing apoptosis by 24 h after cocultivation. The appearance of condensed nuclei and fragmented DNA occurred as HIV reverse transcription was completed, and it was not inhibited by zidovudine, suggesting that induction of apoptosis did not require new HIV replication. Soluble CD4 inhibited apoptosis, demonstrating that Env-CD4 interactions were required for apoptosis. In contrast to that in cell-to-cell transmission, apoptosis in cell-free HIV infections was markedly inefficient and was not observed until 70 to 90 h after infections were initiated. These findings indicate that HIV-1 induction of programmed destruction of the nucleus is initiated at the time of cell-cell cocultivation by a mechanism which requires CD4-Env interactions but not new HIV replication.

Detection of mycoplasma contaminations by the polymerase chain reaction

The polymerase chain reaction (PCR) has been used for the general detection of Mollicutes. 25 Mycoplasma and Acholeplasma species were detected including important contaminants of cell cultures such as M. orale, M. arginini, M. hyorhinis, M. fermentans, A. laidlawii and additional human and animal mycoplasmas. PCR reactions were performed using a set of nested primers defined from conserved regions of the 16S rRNA gene. The detection limit was determined to be 1 fg mycoplasma DNA, which is equivalent to 1-2 genome copies of the 16S rRNA coding region. The identity of the amplification products was confirmed by agarose gel electrophoresis and restriction enzyme analysis. DNA from closely and distantly related micro-organisms did not give rise to specific amplification products. The method presented here offers a much more sensitive, specific and rapid assay for the detection of mycoplasmas than the existing ones.

Antigen capture ELISA using a monoclonal antibody for the detection of Mycoplasma bovis in milk

An enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (mAb) was developed to detect Mycoplasma (M.) bovis in milk samples from cattle. With this procedure, 1 x 10(5) colony forming units per ml (cfu/ml) milk were routinely detectable. No cross-reactions to other bovine mycoplasma species were observed. Both the sensitivity of 80.6% and the specificity of 94.9% are sufficient for its use in diagnosis of clinical mastitis. The sensitivity could be increased by 10% after introduction of 48-hour pre-incubation of samples. This allowed recognition of cows shedding M. bovis amounts of 10(3) cfu/ml in their milk, which is typical for subclinical cases. Screening of milk samples by means of this antigen capture ELISA has advantages over culture methods in terms of speed and potential to monitor large herds, thereby permitting early culling of infected animals to reduce transmission of the pathogen to non-infected animals.

Comparison of various diagnostic methods for the detection of Mycoplasma bovis

Mycoplasma bovis, the main causative agent of mycoplasmal mastitis, arthritis and pneumonia in cattle, causes considerable economic losses. Veterinary hygiene measures would be most effective if introduced at an early stage, especially the culling of cows shedding the pathogen for the control of mastitis. It is therefore crucial to ensure that diagnostic methods are available which can perform rapid and specific detection of the agent at acceptable costs. Six different detection methods have been compared and evaluated in terms of performance parameters and suitability for routine diagnosis. Conventional M. bovis isolation and identification from culture is the only technique used for routine diagnosis at present. However, this process is rather laborious and time-consuming, and final results are available only after several days. Enzyme-linked immunosorbent assay (ELISA) techniques can be used to screen for M. bovis antibodies or antigens in clinically-diseased animals. Detection of the agent in subclinical cases was accomplished in pre-incubated samples by an antigen capture ELISA involving a monoclonal antibody. Whole-cell protein patterns generated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis were used to identify and classify field isolates. Nucleic acid hybridizations using probes of defined specificity were conducted both as filter dot blot assay and in solution with ribosomal ribonucleic acid as the target. The latter was found to be potentially suitable for the screening of biological samples, although problems due to high background and reduced specificity remained. Finally, the presence of M. bovis cells in culture supernatant and in milk samples was demonstrated using the polymerase chain reaction. This procedure is potentially superior to all others currently available, due to its high sensitivity, specificity and speed. However, a number of practical problems must be solved prior to full-scale introduction of this technique for routine diagnosis.

Preparation and characterization of monoclonal antibodies against Mycoplasma bovis

Monoclonal antibodies (mabs) against Mycoplasma (M.) bovis were prepared for use in diagnosis of bovine mastitis. From the original 32 hybridomas actively secreting mabs against M. bovis, 6 stable lines were cloned. Two of them, Mb 5D8 and Mb 4F6, recognized M. bovis antigens of estimated molecular weights of 33 and 26 kDa, respectively. They showed no cross-reaction to other bovine mycoplasmas, thus rendering them useful for specific detection of this pathogen. All mabs investigated cross-reacted with M. agalactiae which is known to be closely related to M. bovis, but does not occur in cattle. Two other mabs, Mb 5D4 and Mb 1F6, exhibited further cross-reactions to a number of bovine mycoplasma species. Finally, mabs Mb 5D5 and Mb 2G5 reacted with all mycoplasmas tested. The possibility that they recognized constituents of the broth culture medium is discussed.

Human-immunodeficiency-virus-type-1-encoded Vpu protein is phosphorylated by casein kinase II

Vpu as a human-immunodeficiency-virus-type-1-encoded 81-amino-acid integral-membrane protein was expressed in Escherichia coli using the inducible ptrc promoter of an ATG fusion vector. Recombinant Vpu is associated with membranes of E. coli and could be partially solubilized by detergents. Recombinant Vpu was phosphorylated in vitro with purified porcine casein kinase II (CKII) as well as with a CKII-related protein kinase found in cytoplasmic extracts of human and hamster cells. Recombinant Vpu associated with E. coli membranes has turned out to be the best substrate for in vitro phosphorylation with CKII. This reaction can be inhibited by heparin and the ATP analogue 5,6-dichloro-1-(beta-D-ribofuranosyl)benzimidazole (DRB), both known to be potent inhibitors of CKII. Radiolabelled gamma ATP and gamma GTP were used as phosphate donors in vitro phosphorylation of recombinant Vpu. In vivo phosphorylation of Vpu in HIV-1-infected H9 cells was also inhibited by DRB. We concluded therefrom that the Vpu protein is phosphorylated by the ubiquitous CKII in HIV-1-infected human host cells. Two seryl residues in the sequence of Vpu (position 52 and 56) correspond to the consensus S/TXXD/E for CKII. These potential phosphorylation sites are located within a well-conserved dodecapeptide of Vpu (residues 47-58), which is found in different HIV-1 strains as well as in a Vpu-like protein of SIVCPZ. Monoclonal and polyclonal antibodies directed against two different epitopes of Vpu were used for immunoprecipitation of Vpu from HIV-1-infected cells and for detection of Vpu in Western blot analyses. Vpu from HIV-1-infected cells as well as recombinant Vpu expressed in E. coli were determined by SDS/PAGE using 6 M urea to be 9 kDa, which corresponds to the calculated molecular mass of Vpu.