Strategies for evaluating idiopathic inflammatory myopathy disease susceptibility genes

This review outlines the progress that has been made in understanding the genetics of the idiopathic inflammatory myopathies in the previous 2 years, with a particular focus on dermatomyositis and polymyositis. A recent genome-wide association study in dermatomyositis has confirmed the importance of the major histocompatibility region in this disease, and has suggested a shared genetic etiology with other autoimmune disorders. This has led to an ongoing study of additional immune-related loci using the Immunochip array. Candidate gene studies have identified novel risk associations in non-Europeans, such as STAT4 and HLA-DRB1 in the Japanese population. Evidence for gene-environment interactions has come from two recent studies implicating smoking status and statin use with HLA alleles. This review also touches on future approaches to genetic research in myositis, including bioinformatics tools to identify causal variants, HLA imputation from existing genetic data and statistical methods to investigate shared effects between subgroups of myositis.

In the idiopathic inflammatory myopathies (IIM), do reactive oxygen species (ROS) contribute to muscle weakness?

The idiopathic inflammatory myopathies (IIMs) are a group of rare autoimmune disorders, collectively known as myositis. Affected patients present with proximal muscle weakness, which usually improves following treatment with immunosuppressants, but often incompletely so, thus many patients remain weak. IIMs are characterised histologically by inflammatory cell infiltrates into skeletal muscle and overexpression of major histocompatibility complex I on muscle cell surfaces. Although inflammatory cell infiltrates represent a major feature of myositis there is growing evidence that muscle weakness correlates only poorly with the degree of cellular infiltration, while weakness may in fact precede such infiltrations. The mechanisms underpinning such non-immune cell mediated weakness in IIM are poorly understood. Activation of the endoplasmic reticulum stress pathways appears to be a potential contributor. Data from non-muscle cells indicate that endoplasmic reticulum stress results in altered redox homeostasis capable of causing oxidative damage. In myopathological situations other than IIM, as seen in ageing and sepsis, evidence supports an important role for reactive oxygen species (ROS). Modified ROS generation is associated with mitochondrial dysfunction, depressed force generation and activation of muscle catabolic and autophagy pathways. Despite the growing evidence demonstrating a key role for ROS in skeletal muscle dysfunction in myopathologies other than IIM, no research has yet investigated the role of modified generation of ROS in inducing the weakness characteristic of IIM. This article reviews current knowledge regarding muscle weakness in the absence of immune cells in IIM, and provides a background to the potential role of modified ROS generation as a mechanism of muscle dysfunction. The authors suggest that ROS-mediated mechanisms are potentially involved in non-immune cell mediated weakness seen in IIM and outline how these mechanisms might be investigated in this context. This appears a timely strategy, given recent developments in targeted therapies which specifically modify ROS generation.

Disease specificity of autoantibodies to cytosolic 5'-nucleotidase 1A in sporadic inclusion body myositis versus known autoimmune diseases

OBJECTIVES

The diagnosis of inclusion body myositis (IBM) can be challenging as it can be difficult to clinically distinguish from other forms of myositis, particularly polymyositis (PM). Recent studies have shown frequent presence of autoantibodies directed against cytosolic 5'-nucleotidase 1A (cN-1A) in patients with IBM. We therefore, examined the autoantigenicity and disease specificity of major epitopes of cN-1A in patients with sporadic IBM compared with healthy and disease controls.

METHODS

Serum samples obtained from patients with IBM (n=238), PM and dermatomyositis (DM) (n=185), other autoimmune diseases (n=246), other neuromuscular diseases (n=93) and healthy controls (n=35) were analysed for the presence of autoantibodies using immunodominant cN-1A peptide ELISAs.

RESULTS

Autoantibodies directed against major epitopes of cN-1A were frequent in patients with IBM (37%) but not in PM, DM or non-autoimmune neuromuscular diseases (<5%). Anti-cN-1A reactivity was also observed in some other autoimmune diseases, particularly Sjögren's syndrome (SjS; 36%) and systemic lupus erythematosus (SLE; 20%).

CONCLUSIONS

In summary, we found frequent anti-cN-1A autoantibodies in sera from patients with IBM. Heterogeneity in reactivity with the three immunodominant epitopes indicates that serological assays should not be limited to a distinct epitope region. The similar reactivities observed for SjS and SLE demonstrate the need to further investigate whether distinct IBM-specific epitopes exist.

Second-line agents in myositis: 1-year factorial trial of additional immunosuppression in patients who have partially responded to steroids

OBJECTIVE

Ciclosporin and MTX are used in idiopathic inflammatory myopathies (DM and PM) when patients incompletely respond to glucocorticoids. Their effectiveness is unproved in randomized controlled trials (RCTs). We evaluated their benefits in a placebo-controlled factorial RCT.

METHODS

A 56-week multicentre factorial-design double-blind placebo-controlled RCT compared steroids alone, MTX (15-25 mg weekly) plus steroids, ciclosporin (1-5 mg/kg/day) plus steroids and all three treatments. It enrolled adults with myositis (by Bohan and Peter criteria) with active disease receiving corticosteroids.

RESULTS

A total of 359 patients were screened and 58 randomized. Of the latter, 37 patients completed 12 months of treatment, 7 were lost to follow-up and 14 discontinued treatment. Patients completing 12 months of treatment showed significant improvement (P < 0.001 on paired t-tests) in manual muscle testing (14% change), walking time (22% change) and function (9% change). Intention to treat and completer analyses indicated that ciclosporin monotherapy, MTX monotherapy and ciclosporin/MTX combination therapy showed no significant treatment effects in comparison with placebo.

CONCLUSION

Neither MTX nor ciclosporin (by themselves or in combination) improved clinical features in myositis patients who had incompletely responded to glucocorticoids.

TRIAL REGISTRATION

International Standard Randomized Controlled Trial Number Register; http://www.controlled-trials.com/; ISRCTN40085050.

Phenotype standardization for statin-induced myotoxicity

Statins are widely used lipid-lowering drugs that are effective in reducing cardiovascular disease risk. Although they are generally well tolerated, they can cause muscle toxicity, which can lead to severe rhabdomyolysis. Research in this area has been hampered to some extent by the lack of standardized nomenclature and phenotypic definitions. We have used numerical and descriptive classifications and developed an algorithm to define statin-related myotoxicity phenotypes, including myalgia, myopathy, rhabdomyolysis, and necrotizing autoimmune myopathy.

Genome-wide association study of dermatomyositis reveals genetic overlap with other autoimmune disorders

OBJECTIVE

To identify new genetic associations with juvenile and adult dermatomyositis (DM).

METHODS

We performed a genome-wide association study (GWAS) of adult and juvenile DM patients of European ancestry (n = 1,178) and controls (n = 4,724). To assess genetic overlap with other autoimmune disorders, we examined whether 141 single-nucleotide polymorphisms (SNPs) outside the major histocompatibility complex (MHC) locus, and previously associated with autoimmune diseases, predispose to DM.

RESULTS

Compared to controls, patients with DM had a strong signal in the MHC region consisting of GWAS-level significance (P < 5 × 10(-8)) at 80 genotyped SNPs. An analysis of 141 non-MHC SNPs previously associated with autoimmune diseases showed that 3 SNPs linked with 3 genes were associated with DM, with a false discovery rate (FDR) of <0.05. These genes were phospholipase C-like 1 (PLCL1; rs6738825, FDR = 0.00089), B lymphoid tyrosine kinase (BLK; rs2736340, FDR = 0.0031), and chemokine (C-C motif) ligand 21 (CCL21; rs951005, FDR = 0.0076). None of these genes was previously reported to be associated with DM.

CONCLUSION

Our findings confirm the MHC as the major genetic region associated with DM and indicate that DM shares non-MHC genetic features with other autoimmune diseases, suggesting the presence of additional novel risk loci. This first identification of autoimmune disease genetic predispositions shared with DM may lead to enhanced understanding of pathogenesis and novel diagnostic and therapeutic approaches.

Sex-related differences of morphometric, densitometric, and geometric parameters of tibia and tarsometatarsal bone in 14-month-old ostriches (Struthio camelus)

The aim of the current study was to investigate basic morphometric, geometric, and densitometric parameters of tibia and tarsometatarsus in 14-mo-old male and female ostriches, and interrelationships between these parameters. The study was conducted on 20 tibiae and 20 tarsometatarsal bones of the left pelvic limb derived from 20 healthy 14-mo-old ostriches (Struthio camelus): 10 males and 10 females. The following parameters were determined using peripheral quantitative computed tomography: bone mineral content (BMC), volumetric bone mineral density (vBMD), cortical content (CRT_CNT), cortical density (CRT_DEN), trabecular content, trabecular density (TRAB_DEN), bone area (TOT_A), trabecular area (TRAB_A), cortical area (CRT_A), cortical thickness (CRT_THK_C), periosteal circumference (PERI_C), endocortical circumference (ENDO_C), and strength-strain index (SSI) in the metaphysis and diaphysis of the bones. Statistical evaluation of the obtained results was performed using Student's t-test, and the Pearson correlation coefficient between the investigated parameters was determined. The obtained results have shown significant differences in proximal metaphysis between males and females when evaluating such parameters as CRT_DEN, TOT_A, TRAB_A, PERI_C, SSI in tibia (P < 0.05), and BMC, vBMD, TRAB_DEN, CRT_CNT, TOT_A, TRAB_A, cortical area, PERI_C, ENDO_C, SSI in tarsometatarsus (P < 0.05). Significant differences between the 2 sexes were found in all the investigated parameters of diaphysis of tibia, except for CRT_DEN and ENDO_C (P < 0.05). Significant positive correlations between BW and bone weight were found (P < 0.05). Furthermore, numerous correlations of morphometric, geometric, and densitometric parameters of metaphysis and diaphysis of the tibia and tarsometatarsus were stated (P < 0.05). In conclusion, the present investigation demonstrated sex-related differences in morphometric, densitometric, and geometric properties of tibia and tarsometatarsus in 14-mo-old ostriches. Numerous correleations observed between the investigated parameters have shown that ostrich tibia and tarsometatarsus may present a valuable model for further studies on bone tissue metabolism regulation in breeding birds.

Dermatomyositis is associated with an increased risk of cardiovascular and cerebrovascular events: a Taiwanese population-based longitudinal follow-up study

BACKGROUND

While the chronic inflammation related to autoimmune diseases is known to be associated with an increased cardiovascular risk, much less is known about cerebrovascular risks.

OBJECTIVES

The present population-based, age- and sex-matched follow-up study was undertaken to investigate the risks of acute myocardial infarction (AMI) and ischaemic stroke in patients with dermatomyositis (DMS).

METHODS

In total 907 patients with DMS were enrolled and compared with a non-DMS control group consisting of 4535 age- and sex-matched, randomly sampled subjects without DMS. The AMI-free and ischaemic stroke-free survival curves were generated using the Kaplan-Meier method. Cox proportional hazard regression was used to estimate the DMS-associated risks of AMI and ischaemic stroke.

RESULTS

During the 2-year follow-up period, 14 patients with DMS (1.5%) and 18 patients in the non-DMS control group (0.4%) suffered AMIs. The crude hazard ratio (HR) for suffering an AMI in patients with DMS compared with subjects in the non-DMS group was 3.96 [95% confidence interval (CI) 1.97-7.96, P = 0.0001], while the adjusted HR was 3.37 (95% CI 1.67-6.80, P = 0.0007), after taking into account demographic characteristics and cardiovascular comorbidities. During the same follow-up period, 46 patients (5.1%) and 133 subjects in the control group (2.9%) developed ischaemic strokes. The crude HR for developing an ischaemic stroke in patients with DMS compared with subjects in the non-DMS group was 1.78 (95% CI 1.27-2.49, P = 0.0007), and the adjusted HR was 1.67 (95% CI, 1.19-2.34, P = 0.0028).

CONCLUSIONS

These findings suggest that DMS is associated with an increased risk of cardiovascular and cerebrovascular events.

Statin-induced necrotizing myositis - a discrete autoimmune entity within the "statin-induced myopathy spectrum"

Statin-induced necrotizing myositis is increasingly being recognised as part of the "statin-induced myopathy spectrum". As in other immune-mediated necrotizing myopathies, statin-induced myositis is characterised by proximal muscle weakness with marked serum creatinine kinase elevations and histological evidence of myonecrosis, with little or no inflammatory cell infiltration. Unlike other necrotizing myopathies, statin-induced myopathy is associated with the presence of autoantibodies directed against 3-hydroxy-3-methylglutaryl- coenzyme A reductase (the enzyme target of statin therapies), and with Human Leukocyte Antigen-DRB1*11. This article summarises the clinical presentation, investigations and management of this rare, but serious complication of statin therapy.

ANO5 gene analysis in a large cohort of patients with anoctaminopathy: confirmation of male prevalence and high occurrence of the common exon 5 gene mutation

Limb girdle muscular dystrophy type 2L or anoctaminopathy is a condition mainly characterized by adult onset proximal lower limb muscular weakness and raised CK values, due to recessive ANO5 gene mutations. An exon 5 founder mutation (c.191dupA) has been identified in most of the British and German LGMD2L patients so far reported. We aimed to further investigate the prevalence and spectrum of ANO5 gene mutations and related clinical phenotypes, by screening 205 undiagnosed patients referred to our molecular service with a clinical suspicion of anoctaminopathy. A total of 42 unrelated patients had two ANO5 mutations (21%), whereas 14 carried a single change. We identified 34 pathogenic changes, 15 of which are novel. The c.191dupA mutation represents 61% of mutated alleles and appears to be less prevalent in non-Northern European populations. Retrospective clinical analysis corroborates the prevalently proximal lower limb phenotype, the male predominance and absence of major cardiac or respiratory involvement. Identification of cases with isolated hyperCKaemia and very late symptomatic male and female subjects confirms the extension of the phenotypic spectrum of the disease. Anoctaminopathy appears to be one of the most common adult muscular dystrophies in Northern Europe, with a prevalence of about 20%-25% in unselected undiagnosed cases.

Association of an MHC class II haplotype with increased risk of polymyositis in Hungarian Vizsla dogs

A breed-specific polymyositis is frequently observed in the Hungarian Vizsla. Beneficial clinical response to immunosuppressive therapies has been demonstrated which points to an immune-mediated aetiology. Canine inflammatory myopathies share clinical and histological similarities with the human immune-mediated myopathies. As MHC class II associations have been reported in the human conditions we investigated whether an MHC class II association was present in the canine myopathy seen in this breed. 212 Hungarian Vizsla pedigree dogs were stratified both on disease status and degree of relatedness to an affected dog. This generated a group of 29 cases and 183 "graded" controls: 93 unaffected dogs with a first degree affected relative, 44 unaffected dogs with a second degree affected relative, and 46 unaffected dogs with no known affected relatives. Eleven DLA class II haplotypes were identified, of which, DLA-DRB1*02001/DQA1*00401/DQB1*01303, was at significantly raised frequency in cases compared to controls (OR = 1.92, p = 0.032). When only control dogs with no family history of the disease were compared to cases, the association was further strengthened (OR = 4.08, p = 0.00011). Additionally, a single copy of the risk haplotype was sufficient to increase disease risk, with the risk substantially increasing for homozygotes. There was a trend of increasing frequency of this haplotype with degree of relatedness, indicating low disease penetrance. These findings support the hypothesis of an immune-mediated aetiology for this canine myopathy and give credibility to potentially using the Hungarian Vizsla as a genetic model for comparative studies with human myositis.

A search for genetic markers associated with egg production in the ostrich (Struthio camelus)

The aim of the current study was to search for genetic markers, microsatellite loci associated with laying performance in ostriches. The material consisted of two groups of ostrich hens characterized by high or low laying performance (over 75 and less than 25 eggs per season, respectively). The investigation covered 30 microsatellite loci characteristic for the ostrich (the CAU group) and led to identification of significant differences in allele and genotype frequencies between the two groups of hens considered. Out of a total of 30 microsatellite loci examined, 28 showed different alleles in relation to analyzed performance groups. In hens of high laying performance (HP group, n = 12), specific alleles occurred in 23 microsatellite loci (40 alleles of 243 identified), while in those of low egg production (LP group, n = 12), they occurred in 22 (51 alleles of 243 identified). The results indicate the usefulness of the microsatellite loci as the potential genetic markers associated with laying performance that can be applied for genetic improvement of ostrich flocks.

Genetic association study of NF-κB genes in UK Caucasian adult and juvenile onset idiopathic inflammatory myopathy

Objective. Treatment-resistant muscle wasting is an increasingly recognized problem in idiopathic inflammatory myopathy (IIM). TNF-α is thought to induce muscle catabolism via activation of nuclear factor-kappa B (NF-κB). Several genes share homology with the NF-κB family of proteins. This study investigated the role of NF-κB-related genes in disease susceptibility in UK Caucasian IIM.

Methods. Data from 362 IIM cases [274 adults, 49 (±14.0) years, 72% female; 88 juveniles, 6 (±3.6) years, 73% female) were compared with 307 randomly selected Caucasian controls. DNA was genotyped for 63 single nucleotide polymorphisms (SNPs) from NF-κB-related genes. Data were stratified by IIM subgroup/serotype.

Results. A significant allele association was observed in the overall IIM group vs controls for the IKBL-62T allele (rs2071592, odds ratio 1.5, 95% CI 1.21, 1.89, corrected P = 0.0086), which strengthened after stratification by anti-Jo-1 or -PM-Scl antibodies. Genotype analysis revealed an increase for the AT genotype in cases under a dominant model. No other SNP was associated in the overall IIM group. Strong pairwise linkage disequilibrium was noted between IKBL-62T, TNF-308A and HLA-B*08 (D′ = 1). Using multivariate regression, the IKBL-62T IIM association was lost after adjustment for TNF-308A or HLA-B*08.

Conclusion. An association was noted between IKBL-62T and IIM, with increased risk noted in anti-Jo-1- and -PM-Scl antibody-positive patients. However, the IKBL-62T association is dependent on TNF-308A and HLA-B*08, due to strong shared linkage disequilibrium between these alleles. After adjustment of the 8.1 HLA haplotype, NF-κB genes therefore do not independently confer susceptibility in IIM.

Interaction of HLA-DRB1*03 and smoking for the development of anti-Jo-1 antibodies in adult idiopathic inflammatory myopathies: a European-wide case study

Objectives

HLA-DRB1*03 is strongly associated with anti-Jo-1-positive idiopathic inflammatory myopathies (IIM) and there is now increasing evidence that Jo-1 antigen is preferentially expressed in lung tissue. This study examined whether smoking was associated with the development of anti-Jo-1 antibodies in HLA-DRB1*03-positive IIM.

Methods

IIM cases were selected with concurrent information regarding HLA-DRB1 status, smoking history and anti-Jo-1 antibody status. DNA was genotyped at DRB1 using a commercial sequence-specific oligonucleotide kit. Anti-Jo-1 antibody status was established using a line blot assay or immunoprecipitation.

Results

557 Caucasian IIM patients were recruited from Hungary (181), UK (99), Sweden (94) and Czech Republic (183). Smoking frequency was increased in anti-Jo-1-positive IIM cases, and reached statistical significance in Hungarian IIM (45% Jo-1-positive vs 17% Jo-1-negative, OR 3.94, 95% CI 1.53 to 9.89, p<0.0001). A strong association between HLA-DRB1*03 and anti-Jo-1 status was observed across all four cohorts (DRB1*03 frequency: 74% Jo-1-positive vs 35% Jo-1-negative, OR 5.55, 95% CI 3.42 to 9.14, p<0.0001). The frequency of HLA-DRB1*03 was increased in smokers. The frequency of anti-Jo-1 was increased in DRB1*03-positive smokers vs DRB1*03-negative non-smokers (42% vs 8%, OR 7.75, 95% CI 4.21 to 14.28, p<0.0001) and DRB1*03-positive non-smokers (42% vs 31%, p=0.08). In DRB1*03-negative patients, anti-Jo-1 status between smokers and non-smokers was not significantly different. No significant interaction was noted between smoking and DRB1*03 status using anti-Jo-1 as the outcome measure.

Conclusion

Smoking appears to be associated with an increased risk of possession of anti-Jo-1 in HLA-DRB1*03-positive IIM cases. The authors hypothesise that an interaction between HLA-DRB1*03 and smoking may prime the development of anti-Jo-1 antibodies.

Food consumption patterns of female undergraduate students in the United Arab Emirates

BACKGROUND

Studies on food intake in the UAE especially in relation to the student life are lacking.

OBJECTIVE

To investigate eating habits of undergraduate students.

METHODS

A cohort of 146 undergraduate students studying Physiology at Zayed University completed a semi-structured questionnaire. A student response was accepted for analysis only those weeks with adequate responses not more than six.

RESULTS

The mean student age was 19.28 (1.22) years with a minimum-maximum 18-23 years. The mean weight was 56.67(13.31) with a minimum-maximum of 40-89 kg. Of 1,250 United Arab Emirates Dirham; 10 indicated they worked but did not specify income; and three were married. More foods were consumed seven times in a week. Amongst the principal foods consumed were: bread, cereal, starch; white bread, cornflakes and rice; fruits-apple, banana and orange; vegetables -cucumber, tomato and lettuce; meat-fish, chicken and beef; and eggs and dairy-(milk, cheese and yoghurt).

CONCLUSION

Dubai female undergraduates have a height intake of milk and fruits and less fanciful breads. Further studies should measure the exact quantity/mass of foods consumed per week.

Recent advances in the immunogenetics of idiopathic inflammatory myopathy

This review summarizes the previous and current literature on the immunogenetics of idiopathic inflammatory myopathy (IIM) and updates the research progress that has been made over the past decade. A substantial part of the genetic risk for developing adult- and juvenile-onset IIM lies within the major histocompatibility complex (MHC), and a tight relationship exists between individual human leukocyte antigen alleles and specific serological subtypes, which in turn dictate clinical disease phenotypes. Multiple genetic regions outside of the MHC are increasingly being identified in conferring IIM disease susceptibility. We are still challenged with the task of studying a serologically and clinically heterogeneous disorder that is rarer by orders of magnitude than the likes of rheumatoid arthritis. An ongoing and internationally coordinated IIM genome-wide association study may provide further insights into IIM immunogenetics.

Computer-generated radiological imagery of the structure of the spongious substance in the postnatal development of the tibiotarsal bones of the Peking domestic duck (Anas platyrhynchos var. domestica)

The evaluation of the structure of the spongious substance of the tibiotarsal (TT) bones of the domestic duck aged 4 to 8 wk was performed using radiological analysis. The Trabecula program (Czerwiński, 1994) used in the study identified a map of radiological trabeculae and calculated the number, average volume, density, and width of trabeculae. It was stated that the number of trabeculae differed significantly (P ≤ 0.05) variant on age, sex, and a unique fragment of the studied bone. Six-week-old hens whose TT bones were most often exposed to deformities and fractures possessed attenuated bone mass. The number of trabeculae per 1 mm(2) during breeding was the lowest (10.34 and 9.54 mm(2) in the proximal and distal epiphyses, respectively). The tibial bones of the 6-wk-old hens also possessed the lowest volume of trabeculae (44.62 and 39.84% for the proximal and distal epiphyses, respectively). Dependant variances between the BW, the number of recognized radiological trabeculae, and the volume, density, and width of trabeculae were calculated using a selected correlation and regression coefficient (r = 0.41; P ≤ 0.05). Results expounded a unique linear relationship between BW and the volume of trabeculae. Indeed, the larger the BW, the more numerous the trabeculae observed. No significant correlation was determined between the BW and the number of recognized trabeculae nor their density and width. A small number of trabeculae and the lowered density may be the cause of fractures and deformities of the TT bones of the domestic duck.

Quantitative nailfold video capillaroscopy in patients with idiopathic inflammatory myopathy

OBJECTIVES

To quantify nailfold capillary density and dimensions in patients with idiopathic inflammatory myopathy (IIM) and compare them with those in healthy controls; to look for associations with microvascular disease in IIM; and to determine whether nailfold capillary density and dimensions change over time.

METHODS

Nailfold video microscopy (x300 magnification) was performed on 24 patients with IIM and 35 healthy controls. Capillary density and dimensions (total width and apical width) were quantified. Patients were clinically assessed and disease activity recorded using the Myositis Disease Activity Assessment Tool. Disease severity and physical function were assessed using the myositis damage index and Stanford HAQ, respectively. Findings were analysed using linear and logistic regression, adjusted for age and sex. In a subgroup of 16 patients with IIM and 27 controls, the process was repeated 6-12 months later and the results were analysed using Student's t-test.

RESULTS

Capillary density was lower and dimensions were higher in patients with IIM compared with healthy controls (P < 0.001 for all). Anti-Jo-1 antibody was associated with reduced capillary density. In the longitudinal cohort, the mean change in capillary density was -1.4 in patients vs -0.4 in controls (P = 0.07). Mean change in capillary dimensions did not differ between patients and controls, but some patients demonstrated pronounced changes in capillary morphology over time.

CONCLUSIONS

Reduced capillary density and increased dimensions in patients with IIM can be quantified using nailfold capillaroscopy, suggesting that nailfold capillaroscopy may be useful as an outcome measure of microvascular disease in studies of IIM.

An update on the immunogenetics of idiopathic inflammatory myopathies: major histocompatibility complex and beyond

PURPOSE OF REVIEW

To update the reader on immunogenetic advances in idiopathic inflammatory myopathy (IIM) over the past 18 months.

RECENT FINDINGS

In Caucasian IIM, despite a shared association with the human leukocyte antigen (HLA) 8.1 ancestral haplotype (HLA-DRB1*03-DQA1*05-DQB1*02), anti-Jo-1 and anti-PM-Scl antibody-positive cases have differing IIM clinical phenotypes. A study of the HLA-DPB1 region has shown that DPB1*0101 is associated with anti-Jo-1 positivity but not with anti-PM-Scl. IIM single nucleotide polymorphism studies have demonstrated associations in the protein tyrosine phosphatase, nonreceptor type 22, tumour necrosis factor alpha and interleukin-1 genes. The GM 13 allotype has been confirmed as a risk factor in Caucasian IIM. In inclusion body myositis, the HLA 8.1 ancestral haplotype may not only influence disease susceptibility but also disease expression. A follow-up study including a meta-analysis of the apolipoprotein E gene in inclusion body myositis suggests that this gene does not confer risk of disease.

SUMMARY

Although a substantial part of the genetic risk for developing adult and juvenile IIM lies within the major histocompatibility complex, recent research suggests that genetic regions outside of the major histocompatibility complex are also potentially involved in conferring IIM disease susceptibility, although with more modest effect sizes. An ongoing and internationally coordinated IIM genome-wide association scan may provide further insights into IIM immunogenetics.

Skeletal muscle contractile properties and proinflammatory cytokine gene expression in human endotoxaemia

Background

Muscle dysfunction associated with sepsis contributes to morbidity and mortality but the underlying mechanisms are unclear. This study examined whether muscle weakness relates to an intrinsic defect in contraction, or to central mechanisms associated with acute illness, and whether systemic endotoxaemia induces changes in gene expression for proinflammatory cytokines within human muscle in vivo.

Methods

In this experimental study, 12 healthy men received intravenous Escherichia coli lipopolysaccharide (LPS, 4 ng/kg) or saline (control). Voluntary and electrically stimulated quadriceps contraction, and tumour necrosis factor (TNF) α mRNA expression in quadriceps muscle biopsies were studied before and after the infusion.

Results

Endotoxaemia induced transient weakness of voluntary quadriceps contraction, equivalent to a 7·8 (95 per cent confidence interval 2·1 to 13·5) per cent reduction in contractile force at 180 min (P = 0·027) and a 9·0 (5·2 to 12·8) per cent reduction at 300 min (P = 0·008). Electrically stimulated contraction was unaffected. LPS administration resulted in an apparent fibre-specific induction of TNF-α mRNA.

Conclusion

Endotoxaemia results in a reduction in voluntary muscle contractile force without an apparent defect in stimulated muscle contraction. Loss of volition may be a more important factor than intrinsic dysfunction in acute sepsis-associated human muscle weakness.

HLA-DPB1 associations differ between DRB1*03 positive anti-Jo-1 and anti-PM-Scl antibody positive idiopathic inflammatory myopathy

OBJECTIVE

The HLA 8.1 ancestral haplotype (HLA-B*08/DRB1*03/DQA1*05/DQB1*02) is associated with adult/juvenile idiopathic inflammatory myopathy (IIM), but confers a greater strength of association in patients possessing anti-Jo-1 or anti-PM-Scl antibodies. The HLA-DPB1 gene is centromeric to other HLA class II loci and separated by a recombination hotspot. We investigated whether HLA-DPB1 associations differ between anti-Jo-1 and anti-PM-Scl antibody-positive IIM cases.

METHODS

Two hundred and thirty-three adult IIM patients (73% females, 49.4 +/- 13.6 years) with PM (n = 89), DM (n = 88) and myositis associated with another CTD (n = 55) and 85 juvenile DM patients (75% females, 6.2 +/- 3.6 years) were compared with 678 UK Caucasian controls. Patients/controls were genotyped for HLA-DPB1 and DRB1 alleles. Myositis-specific and associated antibodies were identified in cases using immunoprecipitation.

RESULTS

HLA-DPB1*0101 was associated with IIM overall [22 vs 13% controls, corrected probability (P(corr)) = 2 x 10(-03); odds ratio (OR) 2.0; 95% CI 1.4, 2.9], PM (P(corr) = 7 x 10(-03); OR 2.5; 95% CI 1.5, 4.4) and anti-Jo-1 (P(corr) = 3 x 10(-5); OR 4.1; 95% CI 2.1, 7.8). No significant DPB1*0101 difference was present between anti-PM-Scl cases and controls. The HLA-DPB1*0101 association in IIM overall cases was dependent on the presence of DRB1*03. A number of HLA-DRB1*03/DPB1 haplotypes were identified, but only DRB1*03/DPB1*0101 was associated with anti-Jo-1 antibody-positive cases.

CONCLUSIONS

The HLA-DRB1*03/DPB1*0101 haplotype is a risk factor for anti-Jo-1 antibody-positive IIM. Thus, although DRB1*03 is strongly associated with possession of either anti-Jo-1 or anti-PM-Scl, differing antibody associations are observed at the HLA-DPB1 locus.

Autoantibodies to a 140-kd protein in juvenile dermatomyositis are associated with calcinosis

OBJECTIVE

The identification of novel autoantibodies in juvenile dermatomyositis (DM) may have etiologic and clinical implications. The aim of this study was to describe autoantibodies to a 140-kd protein in children recruited to the Juvenile DM National Registry and Repository for UK and Ireland.

METHODS

Clinical data and sera were collected from children with juvenile myositis. Sera that recognized a 140-kd protein by immunoprecipitation were identified. The identity of the p140 autoantigen was investigated by immunoprecipitation/immunodepletion, using commercial monoclonal antibodies to NXP-2, reference anti-p140, and anti-p155/140, the other autoantibody recently described in juvenile DM. DNA samples from 100 Caucasian children with myositis were genotyped for HLA class II haplotype associations and compared with those from 864 randomly selected UK Caucasian control subjects.

RESULTS

Sera from 37 (23%) of 162 patients with juvenile myositis were positive for anti-p140 autoantibodies, which were detected exclusively in patients with juvenile DM and not in patients with juvenile DM-overlap syndrome or control subjects. No anti-p140 antibody-positive patients were positive for other recognized autoantibodies. Immunodepletion suggested that the identity of p140 was consistent with NXP-2 (the previously identified MJ autoantigen). In children with anti-p140 antibodies, the association with calcinosis was significant compared with the rest of the cohort (corrected P < 0.005, odds ratio 7.0, 95% confidence interval 3.0-16.1). The clinical features of patients with anti-p140 autoantibodies were different from those of children with anti-p155/140 autoantibodies. The presence of HLA-DRB1*08 was a possible risk factor for anti-p140 autoantibody positivity.

CONCLUSION

This study has established that anti-p140 autoantibodies represent a major autoantibody subset in juvenile DM. This specificity may identify a further immunogenetic and clinical phenotype within the juvenile myositis spectrum that includes an association with calcinosis.

Defining cancer risk in dermatomyositis. Part II. Assessing diagnostic usefulness of myositis serology

In part 1 of this review, we examined the evidence behind the association between idiopathic inflammatory myopathies (IIM) and cancers. In view of the well-recognized association between cancer and myositis (hence the term cancer-associated myositis, or CAM), clinicians responsible for the management of patients with myositis must make important decisions regarding how intensively they undertake searches for malignancy. Clinicians must also decide how often such searches are repeated, and again how intensively, to optimize both cancer detection and treatment, and thus patient survival. As the risks of CAM are greatest in dermatomyositis, this is an issue of obvious importance to dermatologists. In this second of two reviews, we examine the role of autoantibodies as potential predictors of cancer risk in patients with IIM.

The wild ostrich (Struthio camelus): a review

The aim of the current report was to study the literature pertinent to wild populations of ostriches and their ecological and behavioural adaptations in the wild. Selected areas included palaeontology; ostrich distribution; conservation status and relationships with humans and habitat. There is an immediate and urgent need to conserve and protect the apparently rapidly declining populations of wild ostriches with the committed involvement of governments and funding bodies. Wildlife management is an important complement to the farming of livestock. Scientists need to understand the elements of ostrich behaviour in the wild in order to make informed decisions on their management and contact with other animals. Information of the like should be included in readily-accessible and annually updated wildlife manuals. We deemed that such information was an essential part in the conservation of this dwindling ratite.

Defining cancer risk in dermatomyositis. Part I

The idiopathic inflammatory myopathies (IIMs) comprise polymyositis, myositis overlapping with another connective tissue disease, dermatomyositis (DM) and inclusion-body myositis (IBM). IIMs are characterized by the presence of proximal muscle weakness, increased levels of muscle-specific enzymes, specific electromyographic abnormalities, and the presence of inflammatory cell infiltrates in skeletal muscle. Clinical, serological and histological criteria can be used to define individual IIM subtypes. In the first of this two-part review series, we examine the evidence for the existence of cancer-associated myositis (CAM), and in part 2, we discuss recent discoveries that provide insight into identification of patients with DM, who may be most at risk of developing CAM.

Sex-based comparison of limb segmentation in ostriches aged 14 months with and without tibiotarsal rotation

The aim of this study was to propose equations to predict changes that occur over time in the angular position of the bones during motion and the angular velocity of the bones in forward motion as a consequence of tibiotarsal rotation (TTR) in ostriches aged 14 months. Twenty-four normal 14-month-old ostriches (12 cocks and 12 hens) and 20 birds with TTR (9 cocks and 11 hens) were used in the study. Daily readings of temperature, relative humidity and rainfall, the lengths of the different segments of the legs and wings, the perpendicular height from the top of the torso to ground level and the length of the erect neck were recorded. Measurements of the degree of valgus deformity in the left foot were made where applicable. TTR hens and cocks were smaller in stature than normal birds. Comparing TTR hens and cocks, the toe, claw, humerus, perpendicular height and angle of rotation were larger in cocks, indicating a larger body in cocks. Hens were more severely affected by TTR. We suggest that the equations used in this study will assist in measuring movement of ostriches and how movement is compromised by overcrowding and TTR. Birds suffering from TTR may experience an increased degree of stress due to movement restrictions in confinement.

Wild ostrich (Struthio camelus australis) reproduction in Orbata, a nature reserve in Tunisia

The aim of the current investigation was to determine wild ostrich reproductive behaviour in Orbata Nature Reserve by observing 16 hens and 28 cocks over a seven-year period. Intense laying commenced in January, one month after the cessation of the rainy season, and 92% of the eggs were produced during the dry season (January to May, peaking in March). Over the seven years, 1,322 eggs were laid in 69 nests, which corresponded to an annual average production of 19.2 +/- 9.1 eggs/nest and 11.8 eggs/hen. 24 nests (34.78%) were non-brooded, 17 nests (24.64%) were deserted in the course of incubation, and 28 nests (40.58%) possessed hatched eggs. All the non-incubated nests had egg losses equivalent to 46.6 +/- 12.6%. Hatchability success of incubated eggs was 41.9 +/- 12.0%. Ostriches tended to dig their nests adjacent to the reserve enclosure which had direct access by road and track, the latter subjecting them to human disturbance and predation. The systematic obstruction of these nests stimulated ostriches to build additional nests within the reserve perimeter. The authors discussed the results recorded in an ostrich flock in relation to the environmental factors (climatic factors, food disponibility and predation) and suggested possibilities for improved wildlife management.

Reliability and validity of the myositis disease activity assessment tool

OBJECTIVE

To test the interrater reliability and validity of the Myositis Disease Activity Assessment Tool, which consists of the Myositis Intention-to-Treat Activity Index and the Myositis Disease Activity Assessment Visual Analog Scales.

METHODS

Two phases of the study were conducted to assess the reliability and validity of the tool, which was modified following the first phase. In the first phase of the reliability study, 123 adult myositis patients were evaluated in 7 centers, and in the second phase 40 patients were evaluated in 2 centers. The validity study included 294 patients in 5 centers in the first phase and 65 patients in 3 centers in the second phase. The interrater reliability was assessed using intraclass correlation coefficients. The criterion validity was calculated using sensitivity, specificity, and positive predictive value (PPV) of a grade of A in any system. Spearman's rank correlation coefficient was used to measure the convergent validity of cross-sectional scores between the 2 instruments.

RESULTS

There was a 2:1 ratio of female to male patients. There was no significant difference in mean age at diagnosis (46.3 versus 46.8 years) and mean disease duration (7.7 versus 10 years) between the 2 groups recruited for the different phases of the study. There was an improvement in interrater reliability in the second phase of the study. There was a significant improvement in the validity of the assessment tool following modification of the tool. The sensitivity, specificity, and PPV of a grade of A in any system improved from 86%, 92%, and 67% in the first phase to 96%, 94%, and 83%, respectively, in the second phase. Convergent validity between the 2 activity tools showed good correlation, ranging from 0.8 to 0.94, for the individual organ systems.

CONCLUSION

This is the first major attempt to assess the reliability and validity of a disease activity index in myositis. Our findings indicate that, following within-study modification, the tool appears to be a reliable and valid instrument to assess myositis disease activity.

The nutritional intake of undergraduates at the University of Zimbabwe College of Health Sciences

In developing countries the cost of treating disease is much more than prevention and so there is now a lot of interest in understanding nutrition. In this pilot study we selected a cohort of pre-clinical students studying at the College of Health Sciences in the University of Zimbabwe. This study was carried to investigate the gender-based weekly consumption of different food categories amongst University of Zimbabwe students. Semi-structured questionnaires distributed to 100 undergraduate students (male= 47; female= 52). The proportion of male and female respondents, age and body weight did not differ significantly. Principal foods consumed by males included sadza and cerevita; naartjies, bananas and avocado pears; tomatoes, onions, covo and spinach; beef; and condensed milk and powdered milk occupied the larger proportions. Females frequently ate a lot of bread, cerevita, sadza and cereal; lemons and avocado pears; onions, tomatoes, rape and covo; beef and soya meat; creamer, powdered milk and milk. This study suggests that females consumed a greater variety of food, including the infrequent types by comparison with men.

The protein tyrosine phosphatase N22 gene is associated with juvenile and adult idiopathic inflammatory myopathy independent of the HLA 8.1 haplotype in British Caucasian patients

OBJECTIVE

To examine single-nucleotide polymorphisms (SNPs) of the protein tyrosine phosphatase N22 gene (PTPN22) and to study the relationship between PTPN22 and the HLA region in patients with idiopathic inflammatory myopathies (IIMs).

METHODS

PTPN22 SNPs were assessed in a large, cross-sectional, case-control study from the UK involving patients with adult or juvenile IIM, comprising patients with polymyositis (PM) (n=114), dermatomyositis (DM) (n=102), myositis associated with another connective tissue disease (myositis-CTD overlap syndrome) (n=64), or juvenile DM (n=101), in comparison with 748 control subjects. Seventeen PTPN22 SNPs were genotyped using the Sequenom MassArray iPLEX platform. Serotyping for myositis-specific/myositis-associated autoantibodies (MSAs/MAAs) was performed by radioimmunoprecipitation.

RESULTS

A significant association was noted between the R620W variant (rs2476601) and IIM (corrected P [Pcorr]=0.0009 versus controls), and specifically with the clinical subgroup of PM (Pcorr=0.003 versus controls). A weaker association was noted with juvenile DM (Pcorr=0.009 versus controls). No significant associations were noted after stratification by serologic subgroups. The association with the R620W variant was independent of alleles forming the HLA 8.1 haplotype. No other PTPN22 SNPs were associated with IIM. The PTPN22 haplotype containing the R620W T allele was the only haplotype significantly associated with IIM.

CONCLUSION

The R620W variant is a significant risk factor for IIM, independent of the HLA 8.1 haplotype. Unlike that in the HLA region, risk is not increased in individuals possessing MSAs/MAAs. These results are further evidence that the PTPN22 gene confers autoimmune susceptibility.

Care, husbandry and diseases of the African giant rat (Cricetomys gambianus)

The African giant rat lives up to 14 years in captivity, reaching maximum body weights of approximately 2.80 kg in bucks and 1.39 kg in does. In Britain, the African giant rat is increasingly becoming a popular exotic pet. A survey was conducted on 41 licensed pet shops in the UK. The range of ages of giant rat presented for sale, single price per rat, paired prices (buck and doe) and transport costs were 4-12 weeks, pounds sterling 320-pounds sterling 370, pounds sterling 352.50-400.00 including VAT, and pounds sterling 10-37.50, respectively Ivermectin injected at 200-400 microg/kg subcutaneously once a week for 3 weeks will eliminate ectoparasites (and many endoparasites). Nematode infections can also be treated with fenbendazole or piperazine. Bladder threadworms can be treated with fenbendazole, protozoa with metronidazole (not in gravid does) and cestodes with praziquantel. Treatment of leptospirosis with doxycycline administered 4.29-5.36 mg once a week is useful prophylactically, although for insurance of effectiveness, 10 mg/kg for 5 days is recommended. An identical dosage is recommended for the treatment of rickettsia. African trypanosomosis infection, following diagnosis of parasites in a blood smear, can be treated with a variety of antiprotozoal drugs like diminazene diaceturate at 3.5 mg/kg for 5 days. Leishmaniasis is treated at the same dose. Staphylococcosis is treated with amoxycillian trihydrate at 5 mg/kg 3 times a day for 7 days. Helminthosis is treated with broad-spectrum deworming solution. Coccidiosis is treated with cotrimoxazole at 100 mg/kg daily for 3 days. Non-steroidal anti-inflammatories are administered to combat secondary bacterial infection after viral invasion.

Renal function in male Sprague-Dawley rats concurrently exposed to long-term nicotine (3-{1-methyl-2-pyrrolidinyl}pyridine) and methylated spirits (methyl alcohol)

Abuse of nicotine and methylated spirits is a global problem. The current study determined the concurrent influence of nicotine and methylated spirits on renal hemodynamics. Two series of experimental protocols were designed: conscious and anesthetized vehicle loading. Conscious animals received nicotine (0.1 mg x kg(-1) bwt, 0.26-0.30 mL), methylated spirits (1.0 g x kg (-1) bwt, 0.26-0.30 mL), combined nicotine and methylated spirits, and control animals (water, 0.26-0.30 mL). Anesthetized animals were challenged with a continuous jugular infusion of 0.077M NaCl. Plasma nicotine concentration was significantly elevated in combined conscious treatments by comparison with animals infused nicotine alone. Plasma arginine vasopressin was significantly attenuated in combined conscious groups, and those infused methylated spirits alone. Aldosterone was elevated in all conscious groups. Both plasma ethanol and methanol concentrations were elevated in rats concurrently administered nicotine and methylated spirits compared with those given methylated spirits alone. Urinary Na(+) levels were significantly elevated in all anesthetized groups associated with attenuated aldosterone concentrations. Plasma nicotine concentrations were increased in combined treatments. Plasma ethanol levels were significantly reduced and elevated in rats concurrently exposed to nicotine and methylated spirits, respectively. The present study suggests that chronic exposure to methylated spirits alone and in combination with nicotine increases urinary Na(+) loss. The renal toxicity is manifested hypothetically via elevations in plasma nicotine and methanol concentrations. This implies that people who concurrently consume methylated spirits and smoke cigarettes have an increased risk of renal failure by being predisposed to fluid and electrolyte disturbances.

Chloroquine: novel uses & manifestations

Chloroquine (CHQ) is a cheap, relatively well tolerated drug initially developed for the treatment of malaria in the 1930s. CHQ has, however, since accrued a plethora of uses in the treatment and amelioration of several other diseases and conditions because of its lysosomotropic properties. It also has characteristic physiological and systemic effects. This review gives an overview of the history and pharmacology of CHQ, and progresses to consider some of the mechanisms that may underlie its biochemical and physiological effects. Additionally, an overview of some of the novel uses of CHQ in the treatment of viral infections and cancer are presented. The antimalarial mechanisms of CHQ were not discussed in this review. The message is that CHQ, despite its welldocumented toxicity and adverse side effects may have important future uses that are associated with its lysosomotropic and immunomodulatory mechanisms. The possibility exists therefore that CHQ might be re-introduced into regular malaria treatment.

Spread bow leg syndrome in ostrich (Struthio camelus) chicks aged 2 to 12 weeks

1. The incidence of spread bow leg syndrome and associated pathology in 15 ostrich chicks aged 2, 4, 8 and 12 weeks is reported. Measurements were made of hind limbs: femur plus tibiotarsus; tarsometatarus; phalanx I, digit III; phalanx II, digit III plus phalanx III, digit III; and phalanx IV, digit III. 2. A run was constructed (6 m x 1.7 m) and subdivided into 2 m sections and the time taken to traverse it was recorded. Measurements (cm) were made of the left and right footprints; the number of footprints and average stride length in 0 to 2, 3 to 4 and 5 to 6 m. Speed was calculated using distance run (m) divided by time taken (s). 3. The number of steps was greater in bow leg chicks aged 4 and 8 weeks by comparison with healthy birds. Stride length, however, was smaller in all age groups with bow leg. All speeds in bow leg chicks were lower than those in healthy birds, except for that recorded at 2 m in chicks aged 2 weeks which did not differ markedly. 4. In affected birds, feathers were sparse. Icterus was present. The tarsometatarsus was twisted, with severely inflamed joints, eroded distal ends, thickening of the cartilage and the presence of fibrous material surrounding the ligaments. Muscles in the hind limb were emaciated. 5. The syndrome compromises the ability of chicks to keep up with adults in flocks, and may compromise their ability to escape predation.

Hyperzincaemia in a pet African giant rat (Cricetomys gambianus Waterhouse, 1840)

Presented is an African giant rat (Cricetomys gambianus) following zinc ingestion. The sick rat was lethargic, withdrawn, had soft, mucus-impregnated faeces and diahorrea, foot twitching and icterus. Comparative age, sex and body weight (b.wt.)-matched analyses were made with a healthy giant rat. Twelve-hourly Urine volume (UV), Haematocrit (Hct), urinary glucose, plasma zinc and Alkaline Phosphatase (ALP) were performed over an 8-week period. Full blood counts were performed and differential WBC counts and microscopic observations were made on blood smears obtained from both healthy and sick rats. Consecutive blood samples were drawn at the end of each week (Weeks <2-6 treatment; Weeks 7-8 post-treatment). Treatment involved oral vitamin B12 supplement at 4 microg/day and 2 ml diethylenetriaminepentaacetic acid (DTPA) intramuscular injections at 1 ml/450g b.wt./5 wks (Week 2 - 6). Day 1 showed neutropaenia, Heinz bodies on RBCs (reticulocytes and immature forms). Zinc (Day 1 - end Week 7), glucose (Day 1 - end Week 4), ALP (Day 1 -Week 4) and UV were elevated (Day 1 - end Week 6). Indications of moderate zinc toxicosis following ingestion and stress-associated glucosuria were concluded.

Nitric oxide-mediated pathogenesis during nicotine and alcohol consumption

Nitric oxide (NO) is formed by different cell types in response to a variety of physiological and patho-physiological stimuli. The intake of nicotine and/or alcohol has patho-physiological effects on organ function, and the progression of alcohol-/tobacco-related diseases seem to be directly influenced by NO-mediated mechanisms. Nicotine has an adverse influence on blood vessel functionality, repair and maintenance. Chronic nicotine exposure augments atherosclerosis by enhancing the production of proinflammatory cytokines by macrophages which then activate atherogenic NF-kB target genes in aortic lesions. Alcohol produces NO which speeds up the apoptosis of neutrophils. Alcohol sensitizes the liver to endotoxemic shock. Nitrosative stress and increased basal levels of NO contribute to tumour growth. The progression of disease seems to be directed via a definite NO-mediated mechanism. This review gives an insight into how intake of tobacco and alcohol may affect quality of life.