Muscle metabolites, detected in urine by proton spectroscopy, correlate with disease damage in juvenile idiopathic inflammatory myopathies

OBJECTIVE

To assess for novel markers of muscle damage using urinary muscle metabolites by 1H magnetic resonance spectroscopy in patients with juvenile idiopathic inflammatory myopathy (IIM).

METHODS

Creatine (Cr), choline (Cho), betaine (Bet), glycine (Gly), trimethylamine oxide (TMAO), and several other metabolites were measured in first morning void urine samples from 45 patients with juvenile IIM and from 35 healthy age-matched controls, and correlated with measures of myositis disease activity and damage. Urinary metabolite to age-adjusted creatinine (Cn) ratios were examined.

RESULTS

Age-adjusted initial Cr:Cn, Cho:Cn, Bet:Cn, Gly:Cn, and TMAO:Cn ratios were higher in patients with juvenile IIM than controls (P < 0.01). Cr:Cn ratios showed significant correlations with physician-assessed global disease damage (Spearman rs = 0.37; P = 0.01), Steinbrocker functional class (rs = 0.35; P = 0.02), serum Cr (rs = 0.72; P = 0.001), and lactate dehydrogenase (rs = 0.34; P = 0.03) levels. Cho:Cn (rs = 0.3; P = 0.05), Gly:Cn (rs = 0.33; P = 0.03), and TMAO:Cn (rs = 0.36; P = 0.02) ratios showed a significant correlation with serum aldolase levels. Cho:Cn ratios also showed a significant correlation with aspartate aminotransferase levels (rs = 0.35; P = 0.02). A linear regression model was used to evaluate the factors influencing urinary Cr:Cn ratios in the 43 patients with data sets available at the initial visit. The regression model explained 73% of the variation in Cr:Cn ratios. The most significant factor was the physician-assessed global disease damage (R2 = 0.50, P = 0.015).

CONCLUSION

Urinary Cr:Cn, Cho:Cn, Bet:Cn, Gly:Cn, and TMAO:Cn ratios are elevated in juvenile IIM and Cr:Cn correlates strongly with global disease damage. The Cr:Cn ratio may have potential utility as a marker of myositis disease damage.

Normal scores for nine maneuvers of the Childhood Myositis Assessment Scale

OBJECTIVE

To document and evaluate the scores that normal, healthy children achieve when performing 9 maneuvers of the Childhood Myositis Assessment Scale (CMAS).

METHODS

A total of 303 healthy children, 4-9 years of age, were scored as they performed 9 CMAS maneuvers. The data were then evaluated to determine whether normal scores for some maneuvers are age and sex dependent.

RESULTS

All children were able to achieve maximum possible scores for the supine to prone, supine to sit, floor sit, floor rise, and chair rise maneuvers. All but 2 4-year-olds achieved a maximum possible score for the arm raise/duration maneuver. Performance of the head lift and sit-up maneuvers varied significantly, depending primarily on age. Children in all age groups had less difficulty performing the leg lift than the head lift or sit-up.

CONCLUSION

The normative data generated by this study are of value for interpreting the serial CMAS scores of children with idiopathic inflammatory myopathies.

Walking ability and its relationship to lower-extremity muscle strength in children with idiopathic inflammatory myopathies

OBJECTIVE

To describe gait deficits and their association with lower-extremity muscle strength in children with juvenile idiopathic inflammatory myopathies (IIM).

DESIGN

Cross-sectional, descriptive study.

SETTING

Clinical research center.

PARTICIPANTS

Consecutive sample of 25 ambulatory children diagnosed with juvenile IIM.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Manual muscle test (MMT) of bilateral hip flexor, extensor, and abductor; knee extensor; and ankle plantarflexor strength, all measured on a 0- to 10-point scale and summary strength measures. Video-based movement analysis to determine walking speed; gait cycle time; right and left step time; stride length; right and left step length; and stance, swing, and double-limb support phase durations.

RESULTS

Walking speed (1.03+/-0.27 m/s) was reduced because of shortened stride lengths (1.03+/-0.21 m) more than prolonged gait cycle times (1.05+/-0.22s). Walking speed highly correlated with the number of muscle groups weaker than grade 7 out of 10 (r=-.89) and the strength of the hip flexors (r=.85).

CONCLUSIONS

Lower-extremity strength measures, including MMT scores of individual muscle groups and the number of weak muscle groups, were predictive of gait limitations in children with juvenile IIM.

Validation and clinical significance of the Childhood Myositis Assessment Scale for assessment of muscle function in the juvenile idiopathic inflammatory myopathies

OBJECTIVE

To examine the measurement characteristics of the Childhood Myositis Assessment Scale (CMAS) in children with juvenile idiopathic inflammatory myopathy (juvenile IIM), and to obtain preliminary data on the clinical significance of CMAS scores.

METHODS

One hundred eight children with juvenile IIM were evaluated on 2 occasions, 7-9 months apart, using various measures of physical function, strength, and disease activity. Interrater reliability, construct validity, and responsiveness of the CMAS were examined. The minimum clinically important difference (MID) and CMAS scores corresponding to various degrees of physical disability were estimated.

RESULTS

The intraclass correlation coefficient for 26 patients assessed by 2 examiners was 0.89, indicating very good interrater reliability. The CMAS score correlated highly with the Childhood Health Assessment Questionnaire (C-HAQ) score and with findings on manual muscle testing (MMT) (r(s) = -0.73 and 0.73, respectively) and moderately with physician-assessed global disease activity and skin activity, parent-assessed global disease severity, and muscle magnetic resonance imaging (r(s) = -0.44 to -0.61), thereby demonstrating good construct validity. The standardized response mean was 0.81 (95% confidence interval 0.53, 1.09) in patients with at least 0.8 cm improvement on a 10-cm visual analog scale for physician-assessed global disease activity, indicating strong responsiveness. In bivariate regression models predicting physician-assessed global disease activity, MMT remained significant in models containing the CMAS (P = 0.03) while the C-HAQ did not (P = 0.4). Estimates of the MID ranged from 1.5 to 3.0 points on a 0-52-point scale. CMAS scores corresponding to no, mild, mild-to-moderate, and moderate physical disability, respectively, were 48, 45, 39, and 30.

CONCLUSION

The CMAS exhibits good reliability, construct validity, and responsiveness, and is therefore a valid instrument for the assessment of physical function, muscle strength, and endurance in children with juvenile IIM. Preliminary data on MID and corresponding levels of disability should aid in the clinical interpretation of CMAS scores when assessing patients with juvenile IIM.

Fitness as a determinant of the oxygen uptake/work rate slope in healthy children and children with inflammatory myopathy

There is evidence that the slope of the change in oxygen uptake accompanying changes in work rate (delta VO2/delta W). during moderate incremental exercise is influenced by fitness (peak VO2). We set out to determine whether delta VO2/delta W was related to fitness in a group of healthy children and in children with juvenile dermatomyositis (JDM), a condition associated with decreased peak VO2. We also hypothesized that delta VO2/delta would be significantly decreased in children with JDM compared to healthy children.

METHODS

Twelve children (2 boys) with JDM, mean age 11.6 +/- 3.6 yrs, and 20 healthy children (4 boys), mean age 11.3 +/- 2.9 years, performed an incremental exercise test using a cycle ergometer. delta VO2/delta W below the anaerobic threshold was analyzed using linear regression. Correlations between peak VO2 and delta VO2/delta W were calculated, and differences between the JDM and healthy groups were analyzed using independent t-tests.

RESULTS

The delta VO2/delta W was significantly correlated with peak VO2 for children with JDM (r = 0.71, p < 0.01), healthy children (r = 0.53, p < 0.01), and all children combined (r = 0.78, p < 0.001). The delta VO2/delta W (7.4 +/- 1.4 vs. 10.8 +/- 1.2 ml O2.min-1.watt-1) and peak oxygen uptake (VO2peak) (19.2 +/- 5.0 vs. 31.4 +/- 7.2 ml O2.kg-1, min-1) were significantly lower in children with JDM than in healthy children, respectively (all p < or = 0.001).

CONCLUSION

Fitness is significantly related to delta VO2/delta W in healthy children and those with JDM. Children with JDM have a significantly lower delta VO2/delta W than healthy children. Further study is needed to identify specific factors influencing delta VO2/delta W.

International consensus on preliminary definitions of improvement in adult and juvenile myositis

OBJECTIVE

To use a core set of outcome measures to develop preliminary definitions of improvement for adult and juvenile myositis as composite end points for therapeutic trials.

METHODS

Twenty-nine experts in the assessment of myositis achieved consensus on 102 adult and 102 juvenile paper patient profiles as clinically improved or not improved. Two hundred twenty-seven candidate definitions of improvement were developed using the experts' consensus ratings as a gold standard and their judgment of clinically meaningful change in the core set of measures. Seventeen additional candidate definitions of improvement were developed from classification and regression tree analysis, a data-mining decision tree tool analysis. Six candidate definitions specifying percentage change or raw change in the core set of measures were developed using logistic regression analysis. Adult and pediatric working groups ranked the 13 top-performing candidate definitions for face validity, clinical sensibility, and ease of use, in which the sensitivity and specificity were >/=75% in adult, pediatric, and combined data sets. Nominal group technique was used to facilitate consensus formation.

RESULTS

The definition of improvement (common to the adult and pediatric working groups) that ranked highest was 3 of any 6 of the core set measures improved by >/=20%, with no more than 2 worse by >/=25% (which could not include manual muscle testing to assess strength). Five and 4 additional preliminary definitions of improvement for adult and juvenile myositis, respectively, were also developed, with several definitions common to both groups. Participants also agreed to prospectively test 6 logistic regression definitions of improvement in clinical trials.

CONCLUSION

Consensus preliminary definitions of improvement were developed for adult and juvenile myositis, and these incorporate clinically meaningful change in all myositis core set measures in a composite end point. These definitions require prospective validation, but they are now proposed for use as end points in all myositis trials.

Preliminary core sets of measures for disease activity and damage assessment in juvenile systemic lupus erythematosus and juvenile dermatomyositis

OBJECTIVE

To identify preliminary core sets of outcome variables for disease activity and damage assessment in juvenile systemic lupus erythematosus (JSLE) and juvenile dermatomyositis (JDM).

METHODS

Two questionnaire surveys were mailed to 267 physicians from 46 different countries asking each member to select and rank the response variables used when assessing clinical response in patients with JSLE or JDM. Next, 40 paediatric rheumatologists from 34 countries met and, using the nominal group technique, selected the domains to be included in the disease activity and damage core sets for JSLE and JDM.

RESULTS

A total of 41 response variables for JSLE and 37 response variables for JDM were selected and ranked through the questionnaire surveys. In the consensus conference, domains selected for both JSLE and JDM activity or damage core sets included the physician and parent/patient subjective assessments and a global score tool. Domains specific for JSLE activity were the immunological tests and the kidney function parameters. Concerning JDM, functional ability and muscle strength assessments were indicated for both activity and damage core sets, whereas serum muscle enzymes were included only in the activity core set. A specific paediatric domain called 'growth and development' was introduced in the disease damage core set for both diseases and the evaluation of health-related quality of life was advised in order to capture the influence of the disease on the patient lifestyle.

CONCLUSIONS

We developed preliminary core sets of measures for disease activity and damage assessment in JSLE and JDM. The prospective validation of the core sets is in progress.

HLA-DQA1 is not an apparent risk factor for microchimerism in patients with various autoimmune diseases and in healthy individuals

OBJECTIVE

Microchimeric cells have been identified in lesions and peripheral blood of patients with systemic sclerosis (SSc) and idiopathic inflammatory myopathies (IIM), and HLA-DQA1*0501 is a risk factor for these diseases in some populations. Furthermore, DQA1*0501 has been associated with T lymphocyte microchimerism in SSc. To better define the strength of this association, we assessed the relationship among DQA1 alleles and microchimerism.

METHODS

DNA from whole peripheral blood or magnetically sorted T cells was tested for microchimeric cells by polymerase chain reaction of the Y chromosome or of HLA-Cw in 87 SSc patients, 28 juvenile IIM patients, and 88 healthy controls. Thirty-seven mother-son pairs were also analyzed for microchimerism and DQA1*0501.

RESULTS

We were unable to demonstrate that DQA1*0501 is associated with microchimerism in T lymphocytes or in whole peripheral blood DNA in patients with SSc or juvenile IIM or in healthy individuals. In the 37 mother-son pairs, we were unable to demonstrate an association of DQA1*0501 with microchimerism in peripheral blood DNA or T lymphocytes, and compatibility between the donor's and recipient's HLA alleles did not influence microchimerism in the recipient.

CONCLUSION

These data suggest that HLA-DQA1 alleles do not appear to play a role in the persistence of microchimerism in the peripheral blood or T lymphocytes of patients with selected autoimmune diseases or in healthy individuals.

Defining Clinical Improvement in Adult and Juvenile Myositis

The lack of consensus regarding outcome measures and trial design issues in the idiopathic inflammatory myopathies (IIM) is inhibiting the conduct and interpretation of clinical trials. To begin to address these problems, a multispecialty group of over 70 adult and pediatric neurologists, rheumatologists, rehabilitation medicine physicians, statisticians, and patient support group leaders, called the International Myositis Outcome Assessment Collaborative Study Group (IMACS), is engaged in developing consensus on the assessment of disease activity and damage for myositis clinical trials. As part of this ongoing international effort, members of this group met in November 2001 at a work-shop entitled "Defining Clinical Improvement in Adult and Juvenile Myositis." A goal of the work-shop was to review current data on the validity and responsiveness of the recently published proposed preliminary core set measures for disease outcome assessment in clinical trials for myositis and to define the degree of change in each core set measure that is clinically meaningful. Despite differences in the clinical presentations, natural history and responses to therapy between adult onset and juvenile onset myositis, expert specialists in these diseases came to a consensus that the amount of improvement that is clinically meaningful in each core measure is the same for adult and juvenile myositis. For the domains of muscle strength and physical function, a minimum of 15% improvement is clinically significant, whereas for the physician and patient global assessments, as well as the extramuscular assessment, a minimum of 20% improvement is considered clinically meaningful, and for serum levels of muscle associated enzymes, at least 30% improvement is needed to be clinically important. This workshop is the first of several planned to develop multidisciplinary, international consensus on the conduct and reporting of IIM clinical trials.

Outcome assessment in the adult and juvenile idiopathic inflammatory myopathies

Through the recent efforts of multi-center collaborative study groups, a number of measures have been developed and partially validated to assess disease activity, disease damage, and health-related quality of life in adult and juvenile patients with IIM. Preliminary core set domains and core set measures of activity and damage have also been developed for adult and juvenile patients with myositis. Validated definitions of improvement and disability should be forthcoming in the next few years. These extraordinary developments will enable much-needed standardization in the assessment of the IIM, particularly in therapeutic and other clinical research studies. Despite this substantial progress, there is a need to develop more sensitive measures to assess IIM disease activity and damage, to further validate the existing tools, to define their performance characteristics in various IIM subgroups, to develop improved imaging techniques that are also quantitative, and to validate activation markers as surrogate measures. The ongoing cooperation of multiple specialists with expertise in these disorders, combined with emerging novel technologies, should continue to enhance the assessment of myositis. Improved clinical care and more rapid development of new therapies for patients with myositis will be the ultimate gains realized from these efforts.

Neopterin and quinolinic acid are surrogate measures of disease activity in the juvenile idiopathic inflammatory myopathies

OBJECTIVE

We evaluated the utility of neopterin and quinolinic acid (QUIN) as surrogate measures of disease activity in juvenile idiopathic inflammatory myopathies (IIMs).

METHODS

Plasma and first morning void urine samples were measured for neopterin and QUIN using commercial ELISA, HPLC, or gas chromatography-mass spectrometry in 45 juvenile IIM patients and 79 healthy controls. Myositis disease activity assessments were obtained.

RESULTS

Plasma and urine neopterin and QUIN concentrations were increased in juvenile IIM patients compared with healthy controls (P <0.017). Urine neopterin and QUIN highly correlated with each other (r(s) = 0.73; P <0.0001). Urine neopterin and QUIN correlated moderately with myositis disease activity assessments, including physician and parent global activity assessments, muscle strength testing, functional assessments (Childhood Myositis Assessment Scale, Childhood Health Assessment Questionnaire), skin global activity, and edema on magnetic resonance imaging (r(s) = 0.42-0.62; P <0.05), but generally not with muscle-associated enzymes in serum. Urine neopterin or QUIN, in combination with either serum lactate dehydrogenase (LD) or aspartate aminotransferase (AST), significantly predicted global disease activity (R(2) =0.40-0.56; P <0.002), and both were more sensitive to change than these serum enzymes (standardized response means, -0.41 to -0.48).

CONCLUSIONS

Urinary neopterin and QUIN are candidate measures of disease activity in juvenile IIM patients and add significantly to the prediction of global disease activity in combination with serum LD or AST values. Measurement of these markers in first morning void urine specimens appears to be as good as, or possibly better than, measurements of their concentrations in plasma.

Differences in idiopathic inflammatory myopathy phenotypes and genotypes between Mesoamerican Mestizos and North American Caucasians: ethnogeographic influences in the genetics and clinical expression of myositis

OBJECTIVE

As part of a larger, worldwide study of the ethnogeography of myositis, we evaluated the clinical, serologic, and immunogenetic features of Mestizo (Mexican and Guatemalan) and North American Caucasian patients with idiopathic inflammatory myopathy (IIM).

METHODS

Clinical manifestations, autoantibodies, HLA-DRB1 and DQA1 alleles, and immunoglobulin Gm/Km allotypes were compared between 138 Mestizos with IIM and 287 Caucasians with IIM, using the same classification criteria and standardized questionnaires.

RESULTS

IIM in Mestizo patients was characterized by a higher proportion of dermatomyositis (69% of adult Mestizos versus 35% of adult Caucasians; P < 0.001) and anti-Mi-2 autoantibodies (30% versus 7% of adults, respectively, and 32% versus 4% of children, respectively; P < 0.01). Genetic risk factors also differed in these populations. Whereas Mestizos had no HLA risk factors for IIM, HLA-DRB1*0301, the linked allele DQA1*0501, and DRB1 alleles sharing the first hypervariable region motif (9)EYSTS(13) were major risk factors in Caucasian patients with IIM. Furthermore, different HLA-DRB1 and DQA1 alleles were associated with anti-Mi-2 autoantibodies (DRB1*04 and DQA1*03 in Mestizos and DRB1*07 and DQA1*02 in Caucasians). Immunoglobulin gamma-chain allotypes Gm(1), Gm(17) (odds ratio for both 11.3, P = 0.008), and Gm(21) (odds ratio 7.3, P = 0.005) and kappa-chain allotype Km(3) (odds ratio 7.3, P = 0.005) were risk factors for IIM in Mestizos; however, no Gm or Km allotypes were risk or protective factors in Caucasians. In addition, Gm and Km phenotypes were unique risk factors (Gm 1,3,17 5,13,21 and Gm 1,17 23 21 and Km 3,3) or protective factors (Km 1,1) for the development of myositis and anti-Mi-2 autoantibodies (Gm 1,2,3,17 23 5,13,21) in adult Mestizos.

CONCLUSION

IIM in Mesoamerican Mestizos differs from IIM in North American Caucasians in the frequency of phenotypic features and in the immune-response genes predisposing to and protecting from myositis and anti-Mi-2 autoantibodies at 4 chromosomal loci. These and other data suggest the likelihood that the expression of IIM is modulated by different genes and environmental exposures around the world.

Decreased aerobic capacity in children with juvenile dermatomyositis

OBJECTIVE

To determine whether patients with juvenile dermatomyositis (DM) have limited aerobic capacity compared with healthy controls.

METHODS

Fourteen juvenile DM patients with inactive to moderately active, stable disease (age range 7-17 years) and 14 age- and sex-matched controls performed a maximal exercise test using a cycle ergometer. Oxygen uptake and power were measured at peak exercise (VO(2peak) and W(peak), respectively) and at anaerobic threshold (AT and W(AT)). Juvenile DM disease activity and damage were also assessed.

RESULTS

Patients with juvenile DM had significantly reduced VO(2peak) (19.6 ml O(2)/kg/minute in juvenile DM versus 31.1 ml O(2)/kg/minute in controls), peak heart rate (166 versus 184 beats per minute), W(peak) (1.6 versus 2.7 watts/kg), AT (11.1 versus 18.0 ml O(2)/kg/minute) and W(AT) (0.6 versus 1.4 watts/kg), compared to controls (P <or= 0.05 for each). Aerobic exercise parameters correlated with physician global disease activity and damage, T1-weighted magnetic resonance imaging, and Childhood Myositis Assessment Scale scores (r(s) = 0.58 - 0.82, P <or= 0.05).

CONCLUSION

Patients with juvenile DM with a range of disease activity have a decreased aerobic and work capacity compared to healthy children. Aerobic exercise limitation in juvenile DM correlates best with measures of disease damage (global damage assessment, T1-weighted magnetic resonance imaging, and disease duration). Aerobic exercise testing may be valuable in the assessment of physical endurance, and aerobic training may be indicated as part of the therapeutic regimen in myositis patients with inactive to moderately active, stable disease.

Persistent maternally derived peripheral microchimerism is associated with the juvenile idiopathic inflammatory myopathies

OBJECTIVE

Fetal cells have been demonstrated in the active lesions of adult women with systemic sclerosis. Because the juvenile idiopathic inflammatory myopathies (JIIM) share clinical and histopathological features with systemic sclerosis and graft-vs-host disease, we explored the possibility that maternal cells persist and play a role in the pathogenesis of JIIM.

METHODS

DNA samples extracted from peripheral blood of 28 JIIM patients (14 females, 14 males) and 23 healthy controls were assessed for microchimerism by the HLA Cw polymerase chain reaction method. HLA Cw alleles from eight mothers and three healthy siblings of JIIM patients were also examined.

RESULTS

A microchimeric allele was identified in 19 of 26 JIIM patients whose data were able to be interpreted, compared with two of 21 healthy controls (P<0.001). Subjects with microchimerism ranged in age from 4 to 28 yr. In eight cases in which maternal peripheral blood was available, the additional Cw allele present in the patients was confirmed to be identical to a maternal allele. Three healthy siblings of JIIM patients did not have evidence of a microchimeric Cw allele.

CONCLUSION

Maternal cells can persist in the peripheral blood of their children up to three decades after birth, and are found in a higher proportion in JIIM patients compared with controls. These findings, with other data, suggest that maternal cells may be involved in the immunopathogenesis of JIIM.

Proposed preliminary core set measures for disease outcome assessment in adult and juvenile idiopathic inflammatory myopathies

In order to develop a preliminary core set of disease outcome measures for use in clinical trials of idiopathic inflammatory myopathies (IIM), we evaluated those measures used in previous trials, assessed the validation of published instruments and discussed these at an international consensus conference. The initial proposals were further refined by a multidisciplinary group of adult and paediatric specialists experienced in IIM using the Delphi method. The proposed preliminary core set of disease activity measures consists of five domains: physician and patient/parent global assessments of disease activity; muscle strength; physical function; serum activity of muscle enzymes; and an assessment tool to capture extra-skeletal muscle disease activity. The group recommended further development of a core set of disease damage measures for assessment of persistent changes in anatomy, pathology and function of at least 6 months' duration. The group recommended that patient-reported outcomes should include generic health-related quality of life assessments using the Medical Outcomes Study 36-item Short Form (SF-36) health survey in adult IIM patients and a validated quality of life instrument for paediatric patients. We propose the core set of outcome measures as a minimum group of assessments to include in all IIM therapeutic studies. The use of this core set should assist in standardizing outcome measurement and in optimizing therapeutic trials in myositis.

Autologous stem cell transplantation for pediatric rheumatic diseases

The National Institute of Allergy and Infectious Disease, National Institutes of Health, convened a workshop entitled The Next Step: Protocol Development for Autologous Stem Cell Transplantation for Pediatric Rheumatic Disease, June 2000, co-chaired by Drs. Karyl Barron and Carol Wallace. The goal of the workshop was to focus on the scientific rationale for stem cell transplantation therapy in the pediatric diseases, unique aspects of this therapy in the pediatric rheumatic diseases, transplantation issues and options, regulatory issues, and development of a DNA repository for these diseases.

Juvenile dermatomyositis presenting with anasarca: A possible indicator of severe disease activity

Juvenile dermatomyositis is a rare autoimmune disease characterized by inflammation of the muscle, skin, and other organs. Although localized edema is a common feature of juvenile dermatomyositis, generalized edema has been reported infrequently. We describe a patient with juvenile dermatomyositis presenting with anasarca and note that generalized edema has been associated with severe disease activity.

Validation of the Childhood Health Assessment Questionnaire in the juvenile idiopathic myopathies. Juvenile Dermatomyositis Disease Activity Collaborative Study Group

OBJECTIVE

To examine the validity of the Childhood Health Assessment Questionnaire (CHAQ) in patients with juvenile idiopathic inflammatory myopathy (IIM).

METHODS

One hundred fifteen patients were enrolled in a multicenter collaborative study, during which subjects were assessed twice, 7-9 months apart. Physical function was measured using the CHAQ. Internal reliability was assessed using adjusted item-total correlations and item endorsement rates. Construct validity was assessed by comparing predicted and actual correlations of the CHAQ with other measures of physical function and disease activity. Responsiveness was assessed by calculating effect size (ES) and standardized response mean (SRM) in a group of a priori defined "improvers."

RESULTS

Item-total correlations were high (rs range = 0.35-0.81), suggesting all items were related to overall physical function. Manual muscle testing and the Childhood Myositis Assessment Scale correlated moderate to strongly with the CHAQ (r = -0.64 and -0.75, both p < 0.001). Moderate correlations were also seen with the physician global assessment of disease activity (rs = 0.58, p < 0.001), parent global assessment of overall health (rs = -0.65, p < 0.001), Steinbrocker function class (rs = 0.69, p < 0.001), and global skin activity (rs = 0.40, p < 0.001), while global disease damage and skin damage had low correlations (rs = 0.13 and 0.07, p > or =0.17). Responsiveness of the CHAQ was high, with ES = 1.05 and SRM = 1.20.

CONCLUSION

In this large cohort of patients with juvenile IIM, the CHAQ exhibited internal reliability, construct validity, and strong responsiveness. We conclude that the CHAQ is a valid measure of physical function in juvenile IIM, appropriate for use in therapeutic trials, and potentially in the clinical care of these patients.

Chimeric cells of maternal origin in juvenile idiopathic inflammatory myopathies. Childhood Myositis Heterogeneity Collaborative Group

We identified maternal microchimerism by fluorescence in-situ hybridisation in magnetically-separated CD4 or CD8 peripheral blood cells of eight of nine male patients with juvenile idiopathic inflammatory myopathy, compared with two of nine healthy male controls. We also found maternal microchimerism in inflammatory lesions (one skin sample and nine muscle biopsy samples) of all ten patients examined, compared with two of ten biopsy samples from patients with other muscle disorders. These results suggest that maternal cells may be involved in the pathogenesis of juvenile idiopathic inflammatory myopathy.

Update on the genetics of the idiopathic inflammatory myopathies

A number of lines of investigation suggest that, as is likely the case for other autoimmune diseases, the idiopathic inflammatory myopathies (IIM) develop as a result of specific environmental exposures in genetically susceptible individuals. Current data imply that multiple genes are involved in the etiology of these complex disorders. Targeted gene studies and whole genome approaches have begun to identify several genetic risk factors for autoimmune diseases, but the rarity and heterogeneity of the IIM have limited our knowledge of their associated genes. Current findings suggest that human leukocyte antigen (HLA) genes on chromosome 6, particularly HLA DRB1*0301 and the linked allele DQA1*0501, have the strongest associations with all clinical forms of IIM in white patients. Different HLA alleles, however, may confer risk or protection for myositis in distinct ethnic, serologic, and environmental exposure groups. Non-HLA genetic risk factors, which have been documented for other autoimmune diseases, are now being identified for the IIM. These include polymorphic genes encoding immunoglobulin heavy chains (defined by serologic markers known as Gm allotypes), cytokines and their receptors, and certain proteins that accumulate in the myocyte vacuoles of inclusion body myositis patients. Selected allelic polymorphisms of interleukin-1 receptor antagonist variable number tandem repeats and genes for tumor necrosis factor alpha and interleukin-1 alpha also have recently been associated with IIM. The pathogenic bases for the differences among the many clinically, pathologically and immunologically defined syndromes known as the IIM will be elucidated through a better understanding of the multiple genes that define risks for their development, as well as through investigations of gene-gene and gene-environment interactions.

Postlicensure safety surveillance for varicella vaccine

CONTEXT

Since its licensure in 1995, the extensive use of varicella vaccine and close surveillance of the associated anecdotal reports of suspected adverse effects provide the opportunity to detect potential risks not observed before licensure because of the relatively small sample size and other limitations of clinical trials.

OBJECTIVES

To detect potential hazards, including rare events, associated with varicella vaccine, and to assess case reports for clinical and epidemiological implications.

DESIGN AND SETTING

Postlicensure case-series study of suspected vaccine adverse events reported to the US Vaccine Adverse Event Reporting System (VAERS) from March 17, 1995, through July 25, 1998.

MAIN OUTCOME MEASURES

Numbers of reported adverse events, proportions, and reporting rates (reports per 100,000 doses distributed).

RESULTS

VAERS received 6574 case reports of adverse events in recipients of varicella vaccine, a rate of 67.5 reports per 100,000 doses sold. Approximately 4% of reports described serious adverse events, including 14 deaths. The most frequently reported adverse events were rashes, possible vaccine failures, and injection site reactions. Misinterpretation of varicella serology after vaccination appeared to account for 17% of reports of possible vaccine failures. Among 251 patients with herpes zoster, 14 had the vaccine strain of varicella zoster virus (VZV), while 12 had the wild-type virus. None of 30 anaphylaxis cases was fatal. An immunodeficient patient with pneumonia had the vaccine strain of VZV in a lung biopsy. Pregnant women occasionally received varicella vaccine through confusion with varicella zoster immunoglobulin. Although the role of varicella vaccine remained unproven in most serious adverse event reports, there were a few positive rechallenge reports and consistency of many cases with syndromes recognized as complications of natural varicella.

CONCLUSION

Most of the reported adverse events associated with varicella vaccine are minor, and serious risks appear to be rare. We could not confirm a vaccine etiology for most of the reported serious events; several will require further study to clarify whether varicella vaccine plays a role. Education is needed to ensure appropriate use of varicella serologic assays and to eliminate confusion between varicella vaccine and varicella zoster immunoglobulin. JAMA. 2000;284:1271-1279

Magnetic resonance imaging detection of occult skin and subcutaneous abnormalities in juvenile dermatomyositis. Implications for diagnosis and therapy

OBJECTIVE

To assess the utility of magnetic resonance imaging (MRI) of skin, subcutaneous tissue, and fascia in evaluating disease activity in juvenile dermatomyositis (DM).

METHODS

Short tau inversion recovery (STIR) MRI of the proximal thighs and buttocks, cutaneous assessment, and other measures of disease activity were prospectively obtained in 26 children meeting criteria for probable or definite juvenile DM. Also undergoing STIR MRI assessment were 8 subjects who were being evaluated for muscle disorders and who were not diagnosed as having juvenile DM.

RESULTS

Skin, subcutaneous, or fascial edema of the thighs and buttocks were seen on STIR MRI in up to 85% of juvenile DM patients at baseline evaluation compared with no more than 38% of the comparison group without juvenile DM. In juvenile DM, STIR MRI skin and subcutaneous edema scores correlated (r(s) = 0.51, P = 0.008), as did fascial and muscle edema scores (r(s) = 0.58, P = 0.002). Skin global disease activity scores correlated with MRI skin edema scores (r(s) = 0.41, P = 0.04), and serum aldolase levels correlated with both MRI skin and subcutaneous edema scores (r = 0.44 and 0.40, P = 0.03 and 0.05 respectively). The extent and severity of STIR MRI changes in the skin, subcutaneous tissue, and fascia were not predicted by most other measures of juvenile DM disease activity. Five juvenile DM patients with thigh MRI subcutaneous edema developed clinically apparent calcinosis at the same location within 9 months.

CONCLUSION

Edema or inflammation in the skin, subcutaneous tissue, and fascia, found on STIR MRI, is common in juvenile DM patients and is often undetected by standard assessments. These MRI changes can precede the development of calcinosis. STIR MRI may be a useful adjunct for assessing disease activity and guiding the treatment of juvenile DM.

Polymorphisms in the IL-1 receptor antagonist gene VNTR are possible risk factors for juvenile idiopathic inflammatory myopathies

Although HLA-DRB1 and -DQA1 alleles have been associated with adult and juvenile idiopathic inflammatory myopathies (JIIM), they only partially account for the genetic risk for these autoimmune disorders. Because IL-1alpha and IL-1beta, and the anti-inflammatory competitive inhibitor, IL-1 receptor antagonist (IL-1Ra), have been implicated in the pathogenesis of myositis, we assessed the role of variable number tandem repeat (VNTR) polymorphisms of the IL-1Ra gene (IL-1RN) in the aetiology of JIIM: IL-1RN VNTR polymorphisms were performed on 250 JIIM patients and 471 race-matched controls and were correlated with clinical characteristics. The IL-1RN A1 allele, associated with increased proinflammatory activity, was found to be a risk factor for Caucasians with JIIM (96.0% carriage rate versus 90.2% in race-matched controls, Pcorr = 0.037, odds ratio (OR) = 2.5, confidence interval (CI) = 1.1-5.8), but not for African-Americans, in whom the A3 allele was a possible risk factor (7.0% versus 1.1% in race-matched controls, Pcorr = 0.07, OR = 6.5, CI = 1.1-40.3). IL-1RN genotypes did not correlate with circulating levels of IL-1Ra, which were higher in patients than in controls. The polymorphic IL-1RN locus could be the first non-MHC genetic risk factor identified for JIIM, and different alleles may confer susceptibility for different ethnic groups.

Idiopathic inflammatory muscle disease: clinical aspects

Although much remains to be learned about the immune-mediated myositis syndromes, information generated from recent studies in a number of areas may assist physicians in patient management. Topics reviewed here include: data supporting the association of myositis with cancer and the appropriate evaluations for malignancy in a myositis patient; an approach to the assessment of patients with dermatomyositis sine myositis; the usefulness of the clinicopathological and serological classifications; a discussion of whether childhood and adult myositis are the same or different entities; a review of those prognostic factors to consider in the clinical management of myositis patients; current approaches and their limitations for assessing disease activity and damage. To improve our limited understanding of the myositis syndromes, national and international collaborations are needed to obtain the necessary numbers of subjects, given the rarity and heterogeneity of these disorders.

Development of validated disease activity and damage indices for the juvenile idiopathic inflammatory myopathies. II. The Childhood Myositis Assessment Scale (CMAS): a quantitative tool for the evaluation of muscle function. The Juvenile Dermatomyositis Disease Activity Collaborative Study Group

OBJECTIVE

To develop, validate, and determine the measurement characteristics of a quantitative tool for assessing the severity of muscle involvement in children with idiopathic inflammatory myopathies.

METHODS

The Childhood Myositis Assessment Scale (CMAS) was developed from 2 existing observational functional assessment tools to assess muscle function in the areas of strength and endurance across a wide range of ability and ages. The 14 ordinal items included were chosen to assess primarily axial and proximal muscle groups and are ranked with standard performance and scoring methods. Following the development of the CMAS, a training video and written instructions were developed and reviewed by the physicians participating in this study. Subsequently, utilizing a randomized block design, 12 physicians independently scored 10 children (9 with dermatomyositis, 1 with polymyositis; ages 4-15 years) twice in one day (morning and afternoon) on the CMAS. A pediatric physical therapist performed quantitative manual muscle strength testing (MMT) twice on each child (morning and afternoon), including the neck, trunk, and proximal and distal extremity muscle groups.

RESULTS

The CMAS has a potential range of 0-51, with higher scores indicating greater muscle strength and endurance. The observed mean for the 10 patients was 36.4 (median 44, SD 14.1, observed range 5-51). The total score for the CMAS correlated with the physician's global assessment (by visual analog scale) of disease activity, the MMT score, serum creatine kinase level, and the Juvenile Arthritis Functional Assessment Report score. The score on the CMAS was not correlated with patient age. Interrater reliability (Kendall's coefficient of concordance) ranged from 0.77 to 1.0 for individual items (all P < 0.001), and overall, it was 0.95 (P < 0.001). Intrarater reliability for the individual physicians was measured by correlation of the CMAS scores for each patient on 2 separate evaluations and ranged from 0.97 to 0.99, with an overall correlation for all physicians of 0.98 (all P < 0.001).

CONCLUSION

The CMAS demonstrated an acceptable range of observed scores, excellent convergent validity, and excellent inter- and intrarater reliability. The CMAS is validated to quantitatively assess muscle function in the areas of strength and endurance in children with idiopathic inflammatory myopathies. It can be used in routine clinical care as well as therapeutic trials.

Novel gastrointestinal tract manifestations in juvenile dermatomyositis

We report a case of juvenile dermatomyositis in which a dilated atonic esophagus was associated with delayed gastric emptying and intestinal mucosal thickening, resulting in a radiographic "stacked coin" appearance. These findings, which can also occur in infectious, neoplastic, or other immune-mediated diseases, broaden the spectrum of gastrointestinal tract manifestations in juvenile dermatomyositis. Physicians should be alert for these treatable manifestations in children with myositis who present with unexplained gastrointestinal symptoms, which are reversible with immunosuppressive therapy.

Genetic risk and protective factors for idiopathic inflammatory myopathy in Koreans and American whites: a tale of two loci

OBJECTIVE

To better understand genetic contributions to autoimmunity, immunogenetic markers were studied in two racially discrete and geographically isolated populations of patients with idiopathic inflammatory myopathy (IIM).

METHODS

Clinical characteristics, as well as clinical and autoantibody subsets, were defined in 151 American white patients and 50 Korean patients with IIM. HLA-DRB1 and DQA1 genotyping was performed on patients and racially matched controls by standard molecular techniques. Gm allotypes and phenotypes were determined by the hemagglutination-inhibition method.

RESULTS

HLA-DRB1*0301, the linked allele DQA1*0501, and DRB1 alleles sharing the first hypervariable region motif 9EYSTS13 were major genetic risk factors for the development of myositis in whites (corrected P [Pcorr] < 0.0004, odds ratio [OR] 11.2, 4.5, and 3.1, respectively, for each factor versus controls). Although both the white and Korean patients had a similar distribution of clinical characteristics, autoantibody profiles, and clinical groups, no HLA-DRB1 nor DQA1 allele or motif was found to be a risk factor for IIM in the Korean patients. However, DRB1*14 was a protective factor in Korean patients without myositis-specific autoantibodies (Pcorr = 0.004, OR 0.046). In addition, although no Gm phenotype or allotype was identified as a risk factor in whites, Gm 21 was a protective factor for the development of IIM in Koreans (Pcorr = 0.024, OR 0.3).

CONCLUSION

Although myositis patients in the US and Korea share similar clinical and serologic features, the immune response genes predisposing to and protecting from myositis in each of these ethnic groups differ at two chromosomal loci. These data suggest that multiple genetic loci should be studied to identify risk and protective factors for some autoimmune diseases in various ethnic populations.

Juvenile idiopathic inflammatory myopathy: exercise-induced changes in muscle at short inversion time inversion-recovery MR imaging

PURPOSE

To study the effect of exercise on short inversion time inversion-recovery (STIR) magnetic resonance (MR) images of thigh muscles in children with juvenile idiopathic inflammatory myopathy.

MATERIALS AND METHODS

Thirty-two MR studies were performed in 19 patients with juvenile idiopathic inflammatory myopathy who performed stair-stepping exercise for up to 10 minutes (mean, 5.7 minutes). Baseline T1-weighted (n = 32) and STIR (n = 32) images and STIR images immediately (n = 32) and at 30 (n = 24) and 60 (n = 29) minutes after exercise were obtained at 0.5 T. Four radiologists graded STIR signal intensity changes, in observer performance experiments in which they were blinded to the order of image acquisition in relation to exercise.

RESULTS

Changes in muscle signal intensity were observed on STIR images obtained immediately after exercise in 20 of 32 (63%) studies. The mean signal intensity score immediately after exercise (1.7 +/- 1.0 [SD]) increased compared with the mean baseline score (1.4 +/- 1.1) (P = .0005) and resolved by 30 minutes after exercise. The magnitude of exercise-induced changes correlated with the amount of work performed (r = 0.51, P = .003) but not with disease activity or baseline signal intensity when the changes were corrected for work (r < 0.17, P > .35). Radiologists demonstrated moderate to substantial agreement in the grading of signal intensity changes after exercise (kappa = 0.60-0.84).

CONCLUSION

In patients with juvenile idiopathic inflammatory myopathy, stair-stepping exercise induces signal intensity changes on STIR MR studies of muscle for approximately 30 minutes after exercise, in a distribution that may mimic active muscle inflammation.

Clinical, serologic, and immunogenetic features of familial idiopathic inflammatory myopathy

OBJECTIVE

To describe the clinical, serologic, and immunogenetic features of familial idiopathic inflammatory myopathy (IIM) and to compare these with the features of sporadic IIM.

METHODS

Clinical signs and symptoms, autoantibodies, HLA-DRB1 and DQA1 alleles, and GM/KM phenotypes were compared among 36 affected and 28 unaffected members of 16 unrelated families in which 2 or more blood relatives developed an IIM. In addition, findings in patients with familial IIM were compared with those in 181 patients with sporadic IIM. The families included 3 pairs of monozygotic twins with juvenile dermatomyositis, 11 families with other siblings or relatives with polymyositis or dermatomyositis, and 2 families with inclusion body myositis.

RESULTS

The clinical features of familial IIM were similar to those of sporadic IIM, although the frequency of myositis-specific autoantibodies was lower in familial than in sporadic IIM. DRB1*0301 was a common genetic risk factor for familial and sporadic IIM, but contributed less to the genetic risk of familial IIM (etiologic fraction 0.35 versus 0.51 in sporadic IIM). Homozygosity at the HLA-DQA1 locus was found to be a genetic risk factor unique to familial IIM (57% versus 24% of controls; odds ratio 4.2, corrected P = 0.002).

CONCLUSION

These findings emphasize that 1) familial muscle weakness is not always due to inherited metabolic defects or dystrophies, but may be the result of the development of IIM in several members of the same family, and 2) multiple genetic factors are likely important in the etiology and disease expression of familial IIM, as is also the case for sporadic myositis, but DQA1 homozygosity is a distinct risk factor for familial IIM.

Development of validated disease activity and damage indices for the juvenile idiopathic inflammatory myopathies: I. Physician, parent, and patient global assessments. Juvenile Dermatomyositis Disease Activity Collaborative Study Group

OBJECTIVE

To determine the reliability, content validity, and responsiveness of physician global assessments of disease activity and damage in the juvenile idiopathic inflammatory myopathies (IIM), and to investigate concordance among physician, parent, and patient global ratings.

METHODS

Sixteen pediatric rheumatologists rated 10 juvenile IIM paper patient cases for global disease activity and damage, and assessed the importance of 51 clinical and laboratory parameters in formulating their global assessments. Then, 117 juvenile IIM patients were enrolled in a protocol to examine the relationship between Likert and visual analog scale global assessments, their sensitivity to change, and the comparability of physician, parent, and patient global ratings.

RESULTS

Pediatric rheumatologists demonstrated excellent interrater reliability in their global assessments of juvenile IIM disease activity and damage (97.7% and 94.7% agreement among raters, respectively), and agreed on a core set of clinical parameters in formulating their judgments. Likert scale ratings correlated with those on a visual analog scale, and both were comparable in responsiveness (standardized response means -0.56 for disease activity, 0.02 [Likert] and 0.14 [visual analog] for damage, measured over 8 months). Parent global ratings of disease activity correlated with physician assessments, but were not colinear (Spearman's correlation [r] = 0.41-0.45). Patient global disease activity assessments correlated with those done by parents (r = 0.57-0.84) and physicians (r = 0.37-0.63), but demonstrated less responsiveness (standardized response means -0.21 and -0.12, respectively, over 8 months).

CONCLUSION

Physician global assessments of juvenile IIM disease activity and damage demonstrated high interrater reliability and were shown to be comprehensive measures. Both physician and parent disease activity assessments should be considered valuable as quantitative measures for evaluating therapeutic responses in juvenile IIM patients.

Classification and treatment of the juvenile idiopathic inflammatory myopathies

This article reviews the current status of the classification and treatment of the juvenile idiopathic inflammatory myopathies. The intent of classification is to define homogeneous groups that share similar clinical features, disease courses, and responses to therapy. The classification scheme proposed includes clinicopathologic subsets, serologic subjects based on the presence of myositis-specific and myositis-associated autoantibodies, and environmental triggers of myositis. Juvenile dermatomyositis is the most common and widely recognized of these disorders. The second part reviews the history of treatment of juvenile dermatomyositis and discusses agents to consider for patients with refractory disease, unacceptable steroid toxicity, or poor prognostic factors.

Assessment of disease activity and its sequelae in children and adults with myositis

Validated, comprehensive measures for assessing disease activity and its irreversible sequelae, known as disease damage, have not been developed for the idiopathic inflammatory myopathies (IIM), thus limiting our capacity to assess individual patients and responses to therapies. This review summarizes current approaches for assessing disease activity and damage in the idiopathic inflammatory myopathies and speculates on possibly useful novel approaches for the future. Disease activity and damage indices that combine a number of these assessments are proposed for use in all therapeutic trials. Methods for assessing target organs of the idiopathic inflammatory myopathies will likely evolve as more sensitive and specific measures are developed that can distinguish active inflammation from the irreversible effects of disease.

Activation of the mitogen-activated protein kinase cascade is suppressed by low concentrations of dexamethasone in mast cells

Antigen stimulation of mast cells via the IgE receptor, Fc epsilon RI, results in recruitment of the cytosolic tyrosine kinases, Lyn and Syk, and the phosphorylation of proteins. We examined the effects of the glucocorticoid dexamethasone on these events in a cultured (RBL-2H3) mast cell line. Nanomolar concentrations of dexamethasone suppressed phosphorylation of proteins that were associated with the activation of the mitogen-activated protein (MAP) kinase/phospholipase A2 pathway without inhibiting initial events. For example, tyrosine phosphorylation of the subunits of Fc epsilon RI, Lyn, or Syk or of the Ras-guanine nucleotide exchange factor, Vav, was not suppressed in cells treated with up to 1 microM dexamethasone. In contrast, phosphorylation of Raf1, MEK1, p42mapk, and cytosolic phospholipase A2, as well as the associated increase in MAP kinase activity and release of arachidonic acid, were markedly inhibited in cells treated with as little as 10 nM dexamethasone--a concentration that only partially inhibited hydrolysis of inositol phospholipids or release of secretory granules. Prolonged exposure to dexamethasone also resulted in a partial decrease in expression of MEK1, p42mapk, and cytosolic phospholipase A2, which may contribute further to the effects of dexamethasone on this pathway. Activation of the MAP kinase/phospholipase A2 pathway by the calcium-mobilizing agent thapsigargin was similarly suppressed in dexamethasone-treated cells. These findings suggested that an early step in the pathway, possibly a step immediately before the activation of Raf1, was suppressed by low concentrations of dexamethasone.

Activation of the mitogen-activated protein kinase cascade is suppressed by low concentrations of dexamethasone in mast cells

Antigen stimulation of mast cells via the IgE receptor, Fc epsilon RI, results in recruitment of the cytosolic tyrosine kinases, Lyn and Syk, and the phosphorylation of proteins. We examined the effects of the glucocorticoid dexamethasone on these events in a cultured (RBL-2H3) mast cell line. Nanomolar concentrations of dexamethasone suppressed phosphorylation of proteins that were associated with the activation of the mitogen-activated protein (MAP) kinase/phospholipase A2 pathway without inhibiting initial events. For example, tyrosine phosphorylation of the subunits of Fc epsilon RI, Lyn, or Syk or of the Ras-guanine nucleotide exchange factor, Vav, was not suppressed in cells treated with up to 1 microM dexamethasone. In contrast, phosphorylation of Raf1, MEK1, p42mapk, and cytosolic phospholipase A2, as well as the associated increase in MAP kinase activity and release of arachidonic acid, were markedly inhibited in cells treated with as little as 10 nM dexamethasone--a concentration that only partially inhibited hydrolysis of inositol phospholipids or release of secretory granules. Prolonged exposure to dexamethasone also resulted in a partial decrease in expression of MEK1, p42mapk, and cytosolic phospholipase A2, which may contribute further to the effects of dexamethasone on this pathway. Activation of the MAP kinase/phospholipase A2 pathway by the calcium-mobilizing agent thapsigargin was similarly suppressed in dexamethasone-treated cells. These findings suggested that an early step in the pathway, possibly a step immediately before the activation of Raf1, was suppressed by low concentrations of dexamethasone.

Cerebrospinal fluid analysis in children with seizures

Cerebrospinal fluid (CSF) examinations of 212 children aged two to 24 months with idiopathic nonfebrile seizures, complex febrile seizures, or status epilepticus, who had a lumbar puncture within 24 hours of the convulsion, were reviewed to determine whether an idiopathic convulsion can result in CSF abnormalities. Children with complex febrile seizures had a median CSF white blood cell count of 1 cell/mm3 (range 0-19 cells/mm3) and a median CSF polymorphonuclear (PMN) cell count of 0 cells/mm3 (range 0-8 cells/mm3). The CSF white blood cell (WBC) count was elevated above the upper limit of normal of 5 cells/mm3 in 9.8% and the absolute number of polymorphonuclear cells was more than 0 cells/mm3 in 26.2% of the complex febrile seizure subjects. Values at the 95th percentile were calculated; a total of 8 WBC/mm,3 4 PMN/mm,3 protein of 73 mg/dl and glucose of 119 mg/dl determined the 95th percentile CSF values for the patients with complex febrile seizures. Patients with nonfebrile seizures or with status epilepticus had similar findings. We conclude that complex febrile, idiopathic nonfebrile convulsions or status epilepticus may affect CSF findings in children: CSF with > 20 WBC/mm3 or > 10 PMN/mm3 should not be attributed to seizures.

NIH conference. Myositis: immunologic contributions to understanding cause, pathogenesis, and therapy

The myositis syndromes, the most common forms of which are polymyositis and dermatomyositis, are defined by idiopathic chronic inflammation in skeletal muscle. Although initially described more than a century ago, these diseases are so rare and heterogeneous that we have only a limited understanding of their causes and treatment. Recently, autoimmune responses to nuclear and cytoplasmic autoantigens that are unique to patients with myositis, the myositis-specific autoantibodies, have proved clinically useful in helping predict signs and symptoms of myositis, immunogenetics, responses to therapy, and prognosis. We summarize this new information on the variety and nature of these autoantibodies, their target epitopes, and their possible use in identifying causes, pathogenetic mechanisms, and better therapies for these increasingly recognized disorders.

Laboratory evaluation of the inflammatory myopathies

The laboratory plays an important role in the diagnosis, evaluation, and classification of the heterogeneous group of diseases known as the IIM, which are characterized by chronic muscle inflammation. Serial measurements of the levels of muscle-derived enzymes in serum are the traditional laboratory studies used to follow the clinical course of patients with IIM, although other laboratory tests can also be useful in assessing myositis disease activity. Several markers of immune system activation, including cytokines and lymphocyte markers, show promise as possibly more sensitive measures of myositis disease activity. Discovery of a unique group of MSAs over the past decade has provided an immunologic basis for defining relatively homogeneous subsets of patients who share similar clinical features, disease courses, and responses to therapy. Future investigations of novel immunologic activation markers, as well as the cloning and expression of target autoantigens of the MSAs, should allow better diagnostic assays, enhanced prognosis, and a better understanding of the pathogenesis of these disorders.

New perspectives on the idiopathic inflammatory myopathies of childhood

The idiopathic inflammatory myopathies (IIMs) of childhood are a heterogenous group of rare diseases characterized by chronic skeletal muscle inflammation. Although juvenile dermatomyositis is the most common of these disorders, children may develop any of the other types of myositis that have been better studied in adults. These include not only the IIMs delineated by clinicopathologic features but also the serologic groups of myositis, recently defined by myositis-specific and myositis-associated autoantibodies. Differences in the frequencies of IIM groups between children and adults suggest differences in exposures to myositis-inducing environmental agents or differences in the frequencies of susceptibility genes between these two populations. Further investigation of the heterogeneity of the childhood IIMs and of the newly described clinicopathologic and autoantibody groups should improve our understanding and treatment of these disorders.

A broadened spectrum of juvenile myositis. Myositis-specific autoantibodies in children

OBJECTIVE

Myositis-specific autoantibodies (MSA) define relatively homogeneous clinical and immunogenetic patient groups in adults with idiopathic inflammatory myopathies (IIM). This study explores the usefulness of MSA in defining groups of children with myositis.

METHODS

Sera from 77 children with myositis and other connective tissue diseases were tested for MSA by immunoprecipitation and immunodiffusion. Clinical data were collected and analyzed.

RESULTS

The MSA anti-PL-12 (alanyl-transfer RNA synthetase), anti-Jo-1 (histidyl-tRNA synthetase), anti-signal recognition particle, and anti-Mi-2 were each identified in the sera of 12 children with IIM. In these patients, the clinical manifestations, disease courses, and responses to therapy closely resembled those in adults with the same autoantibodies.

CONCLUSION

These observations suggest that the clinical syndromes defined by particular MSA are similar in children and adults with IIM. By defining similar clinical syndromes in children who have MSA, this study provides a basis for future studies of MSA in the idiopathic inflammatory myopathies of childhood, which may be useful in predicting the clinical courses of a subset of these patients and improving their therapy.

The cDNAs encoding two forms of the LYN protein tyrosine kinase are expressed in rat mast cells and human myeloid cells

Two isoforms of lck/yes-related novel (LYN) protein tyrosine kinase (PTK) appear to play a role in B-cell-IgM and FcERI receptor signaling. The cDNAs lynA and lynB encoding these two forms were isolated and sequenced; they were derived from rat mucosal mast cell and human myeloid cell lines. The nucleotide (nt) and deduced amino acid (aa) sequences share 94 and 97% identity between rat and mouse lyn, respectively, and 88 and 96% identity between rat and human lyn. In all three species, a region of 20 aa is uniformly inserted at an identical site and its sequence is highly conserved. This suggests an important regulatory role for this region mediated by this PTK.

Autoantibody production in Kawasaki syndrome

Although a variety of autoantibodies are produced in patients with Kawasaki syndrome (KS), their specificities in many instances are controversial and their role in disease pathogenesis is undetermined. Autoantibody production was studied in 14 patients with Kawasaki syndrome (KS). Antibodies to myeloperoxidase (MPO), the dominant antigen responsible for perinuclear antineutrophil cytoplasmic antibody (pANCA) reactivity, were detected by ELISA in 73% of acute phase and 89% of convalescent phase KS specimens, in contrast to 4% of normal adult control subjects (p < 0.002 and p < 0.001, respectively). MPO and cytoplasmic antineutrophil antibody (cANCA) levels measured by ELISA were significantly elevated above levels for adult normal control subjects (p < 0.005 and p < 0.01, respectively), but not above recently ill childhood controls. Among patients who developed a positive ANCA, antibody titers tended to rise in serial specimens despite clinical improvement. Antibodies to myocardial muscle, cardiac perimysial connective tissue, nuclear antigens (ANA), and smooth muscle were also detected in some KS patients, but titers did not differ significantly from control patients. Autoantibody results were not predictive of patients with echocardiographic abnormalities.

Treatment of neonatal lupus: case report and review of the literature

A critically ill infant with congenital complete heart block and neonatal lupus was treated with pulse steroids, exchange transfusion and intravenous gammaglobulin. Transient improvement in clinical status and laboratory results occurred, although the infant died. Based on this report and review of prior experience with immunosuppressive therapy, prenatal treatment of the mother with betamethasone or dexamethasone has been successful in resolving the cardiomyopathy/myocarditis associated with neonatal lupus. Postnatal treatment of the infant with steroids appears to be beneficial for persistent hepatic and hematologic manifestations. The evidence for exchange transfusion is less certain.

Phorbol diesters and dioctanoylglycerol stimulate accumulation of both diacylglycerols and alkylacylglycerols in human neutrophils

Human neutrophils treated with phorbol 12-myristate 13-acetate (PMA) or dioctanoylglycerol exhibited a large (10-fold), sustained accumulation of the mass of diradylglycerol, beginning 1 min after stimulation and continuing for 30 to 60 min. Phorbol dibutyrate was less potent than PMA in stimulating diradylglycerol accumulation, whereas the 4-alpha analogs of PMA and phorbol dibutyrate were inactive. Submaximal concentrations of PMA (0.5 to 2.5 nM) plus the calcium ionophore, ionomycin (15 to 60 nM), led to synergistic accumulation of diradylglycerols. Chlorpromazine and sphingosine, inhibitors of protein kinase C, blocked PMA-stimulated accumulation of diradylglycerol with IC50 concentrations of 32 and 9 microM, respectively, paralleling their inhibition of PMA-stimulated O2- production. These compounds also inhibited the ionomycin-stimulated accumulation of diradylglycerols. A third protein kinase C inhibitor, H-7, was less effective, inhibiting PMA-stimulated accumulation of diradylglycerol by 25% at 100 microM. Differential sensitivity to alkaline hydrolysis suggests that diradylglycerols that accumulate in response to PMA or ionomycin stimulation are composed of a mixture of two distinct diglyceride species, diacylglycerols and alkylacylglycerols. Whereas diacylglycerol may activate cellular protein kinase C, the importance of the production of alkylacylglycerols is uncertain.

Phorbol diesters and dioctanoylglycerol stimulate accumulation of both diacylglycerols and alkylacylglycerols in human neutrophils

Human neutrophils treated with phorbol 12-myristate 13-acetate (PMA) or dioctanoylglycerol exhibited a large (10-fold), sustained accumulation of the mass of diradylglycerol, beginning 1 min after stimulation and continuing for 30 to 60 min. Phorbol dibutyrate was less potent than PMA in stimulating diradylglycerol accumulation, whereas the 4-alpha analogs of PMA and phorbol dibutyrate were inactive. Submaximal concentrations of PMA (0.5 to 2.5 nM) plus the calcium ionophore, ionomycin (15 to 60 nM), led to synergistic accumulation of diradylglycerols. Chlorpromazine and sphingosine, inhibitors of protein kinase C, blocked PMA-stimulated accumulation of diradylglycerol with IC50 concentrations of 32 and 9 microM, respectively, paralleling their inhibition of PMA-stimulated O2- production. These compounds also inhibited the ionomycin-stimulated accumulation of diradylglycerols. A third protein kinase C inhibitor, H-7, was less effective, inhibiting PMA-stimulated accumulation of diradylglycerol by 25% at 100 microM. Differential sensitivity to alkaline hydrolysis suggests that diradylglycerols that accumulate in response to PMA or ionomycin stimulation are composed of a mixture of two distinct diglyceride species, diacylglycerols and alkylacylglycerols. Whereas diacylglycerol may activate cellular protein kinase C, the importance of the production of alkylacylglycerols is uncertain.

Diacylglycerol accumulation and superoxide anion production in stimulated human neutrophils

Exogenous diacylglycerols stimulate neutrophil superoxide anion production, suggesting that endogenous diacylglycerols may function as second messengers for this biological response. We have measured the diacylglycerol mass in human neutrophils stimulated by fMet-Leu-Phe, ionomycin, and concanavalin A and have correlated the kinetics and magnitude of the diacylglycerol response with those for superoxide anion production. For each stimulus, no increase in diacylglycerol mass was detected prior to the onset of superoxide anion generation. However, large sustained increases in diacylglycerol concentration (260-2000% of basal levels) occurred in parallel with the rise in superoxide anion. The cessation or continuation of diacylglycerol accumulation and superoxide anion production also correlated. The diacylglycerol response was proportional to the stimulus concentration and correlated with the concentration dependence for superoxide anion. Pretreatment of neutrophils with cytochalasin B enhanced both superoxide anion and diacylglycerol responses with all three stimuli. These data support the hypothesis that diacylglycerol functions as a modulator of superoxide anion generation causing a sustained or augmented respiratory burst.