Pathophysiology of ankylosing spondylitis: what's new?

Analysis of the Literature on Cervical Spine Fractures in Ankylosing Spinal Disorders

STUDY DESIGN

Narrative literature review.

OBJECTIVE

The numbers of low-energy cervical fractures seen in patients suffering from ankylosing spondylitis (also known as Bechterew disease) or diffuse idiopathic skeletal hyperostosis (also known as Forestier disease) have greatly increased over recent decades. These fractures tend to be particularly overlooked, leading to delayed diagnosis and secondary neurological deterioration. The aim of the present evaluation was to summarize current knowledge on cervical fractures in patients with ankylosing spinal disorders (ASDs).

METHODS

The literature was analyzed through an extensive PubMed search focusing on cervical fractures, especially with delayed diagnosis.

RESULTS

In ASDs, it was mainly the cervical spine that was found to be affected by fractures. Fifty percent of ASD patients had neurological deficits at admission, with a high probability of secondary deterioration due to an initially missed diagnosis. Multislice high-resolution imaging techniques should be the radiological standard of care if a vertebral fracture is suspected. Nevertheless, many of these spinal fractures are overlooked, leading to feared secondary deterioration of existing unstable fractures. Long posterior instrumentations were found to be the treatment of choice, followed by anterior and combined anterior-posterior instrumentations.

CONCLUSIONS

Delayed diagnosis of cervical fractures in ASDs contributes to initially misinterpreted clinical symptoms, inadequate imaging techniques, and a lack of knowledge about this disease entity due to its peculiarities. Thorough assessment of the patients' neurological morbidity at admission might reduce the occurrence of the associated fractures. The biomechanical behavior of ASD fractures is completely different from that of non-ASD fractures, so that the treatment strategy for these patients should be at least surgical, in combination with long dorsal instrumentations or combined anterior-posterior approaches.

Bone Loss Triggered by the Cytokine Network in Inflammatory Autoimmune Diseases

Bone remodeling is a lifelong process in vertebrates that relies on the correct balance between bone resorption by osteoclasts and bone formation by osteoblasts. Bone loss and fracture risk are implicated in inflammatory autoimmune diseases such as rheumatoid arthritis, ankylosing spondylitis, inflammatory bowel disease, and systemic lupus erythematosus. The network of inflammatory cytokines produced during chronic inflammation induces an uncoupling of bone formation and resorption, resulting in significant bone loss in patients with inflammatory autoimmune diseases. Here, we review and discuss the involvement of the inflammatory cytokine network in the pathophysiological aspects and the therapeutic advances in inflammatory autoimmune diseases.

The risk of asthma in patients with ankylosing spondylitis: a population-based cohort study

Background

The relationship between asthma and ankylosing spondylitis (AS) is controversial. We examined the risk of asthma among AS patients in a nationwide population.

Methods

We conducted a retrospective cohort study using data from the National Health Insurance (NHI) system of Taiwan. The cohort included 5,974 patients newly diagnosed with AS from 2000 to 2010. The date of diagnosis was defined as the index date. A 4-fold of general population without AS was randomly selected frequency matched by age, gender and the index year. The occurrence and hazard ratio (HR) of asthma were estimated by the end of 2011.

Results

The overall incidence of asthma was 1.74 folds greater in the AS cohort than in the non-AS cohort (8.26 versus 4.74 per 1000 person-years) with a multivariable Cox method measured adjusted HR of 1.54 (95% confidence interval (CI), 1.34–1.76). The adjusted HR of asthma associated with AS was higher in women (1.59; 95% CI, 1.33–1.90), those aged 50–64 years (1.66; 95% CI, 1.31–2.09), or those without comorbidities (1.82; 95% CI, 1.54–2.13).

Conclusion

Patients with AS are at a higher risk of developing asthma than the general population, regardless of gender and age. The pathophysiology needs further investigation.

Preoperative computer-based simulations for the correction of kyphotic deformities in ankylosing spondylitis patients

BACKGROUND CONTEXT

A preoperative plan is important to obtain appropriate balance of the sagittal plane in patients with kyphotic deformity. Previous methods to calculate the correction angle are inconvenient and complicated, whereas the method using computer simulations may be very effective and much simpler than existing methods.

PURPOSE

To evaluate the efficacy of preoperative measurements using a computer simulation for corrective osteotomy for the surgical treatment of kyphosis caused by ankylosing spondylitis (AS).

STUDY DESIGN

Retrospective clinical data analysis.

PATIENT SAMPLE

The sample comprises 18 AS patients with fixed kyphotic deformity who underwent corrective osteotomies at our hospital between October 2007 and January 2010.

OUTCOME MEASURES

Thoracic kyphosis, lumbar lordosis, and the sagittal vertical axis (SVA) of the spine were evaluated by preoperative computer simulation and radiologic measurement. Clinical assessments were performed according to the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Short Form-36 (SF-36), and EuroQol-5 dimension (EQ-5D) before and after the surgery.

METHODS

The coincidence between the preoperative computer simulation and postoperative radiologic parameters was evaluated. We also analyzed the changes derived from each clinical and radiologic measurement before and after the surgery.

RESULTS

Mean thoracic kyphosis changed from 32.4° to 31.9°, mean lumbar lordosis was corrected from 11.5° to 26.9°, and the SVA was improved from 125.7 to 65.1 mm after surgery (p<.001). The correlation coefficients within groups between the computer simulations and radiologic parameters were 0.9, 0.6, and 0.7, showing significant congruency. Although BASDAI and BASFI did not significantly differ (p=.53 and p=.45, respectively), SF-36 and EQ-5D were significantly increased (p<.05 and p<.001, respectively).

CONCLUSIONS

Comparisons of preoperative simulations and actual surgical outcomes showed significant coincidences; thus, evaluations through computer simulations before surgery are expected to help predict the level of correction possible after surgery and improve surgical planning.

Insights into the pathogenesis of axial spondyloarthropathy from network and pathway analysis

Background

Complex chronic diseases are usually not caused by changes in a single causal gene but by an unbalanced regulating network resulting from the dysfunctions of multiple genes or their products. Therefore, network based systems approach can be helpful for the identification of candidate genes related to complex diseases and their relationships. Axial spondyloarthropathy (SpA) is a group of chronic inflammatory joint diseases that mainly affect the spine and the sacroiliac joints. The pathogenesis of SpA remains largely unknown.

Results

In this paper, we conducted a network study of the pathogenesis of SpA. We integrated data related to SpA, from the OMIM database, proteomics and microarray experiments of SpA, to prioritize SpA candidate disease genes in the context of human protein interactome. Based on the top ranked SpA related genes, we constructed a SpA specific PPI network, identified potential pathways associated with SpA, and finally sketched an overview of biological processes involved in the development of SpA.

Conclusions

The protein-protein interaction (PPI) network and pathways reflect the link between the two pathological processes of SpA, i.e., immune mediated inflammation, as well as imbalanced bone modelling caused new boneformation and bone loss. We found that some known disease causative genes, such as TNFand ILs, play pivotal roles in this interaction.

Sleep disturbance in Moroccan patients with ankylosing spondylitis: prevalence and relationships with disease-specific variables, psychological status and quality of life

Sleep disturbance is often reported by the patients with ankylosing spondylitis (AS), with awakenings produced by inflammatory pain. There are limited studies about sleep disturbance on these patients, and especially its association with psychological state and quality of life to examine the prevalence of sleep disturbance and to assess its association with disease-specific variables, psychological status and quality of life. One hundred and ten patients were included in this cross-sectional study according to the modified New York criteria for AS. Clinical and biological parameters were evaluated. Sleep disturbance was assessed by the fourth item of Hamilton Anxiety Scale. Psychological status was assessed by The Hospital Anxiety and Depression Scale including depression subscale and anxiety subscale. The quality of life was evaluated by the short form-36 (SF-36). Sleep disturbance was found in 64.5 %, depression in 55.5 % and anxiety in 60.9 % amongst our patients. Significantly, worse pain, higher disease activity and functional disability were present in patients with sleep disturbance. Likewise, sleep problems were significantly higher in patients with depression, anxiety and in patients with low scores of the SF36. Multivariate logistic regression analysis revealed that the pain (OR = 1.019) and depression (OR = 1.304) were independent risk factors that influenced sleep disturbance. Sleep problems are prevalent amongst Moroccan patients with AS. Our findings suggest that pain and depression were the independent risk factors that influenced the sleep disturbance and hence, the need for evaluation and optimal management of pain and depression to improve sleep quality in AS patients.

Comparison of the BASDAI and the miniBASDAI in assessing disease activity in patients with ankylosing spondylitis

The BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) is the most widely used instrument for the assessment of disease activity in ankylosing spondylitis (AS). Objective. The aims to investigate whether the alternative BASDAI, here termed as the miniBASDAI [(Question (Q) 1 fatigue + Q2 spinal pain) + mean of (Q5 strength morning stiffness + Q6 duration morning stiffness)] / 3], measures disease activity more accurately in the subgroup of AS patients without peripheral manifestations. One hundred and ten patients were included in this cross-sectional study according to the modified New York criteria for AS. Clinical and biological parameters were evaluated. The disease activity was evaluated by the BASDAI. We calculated the miniBASDAI by omitting both the peripheral joints and the enthesitis questions: questions 3 and 4. Patients were dichotomized into a "P+" group if peripheral manifestations were present (at least arthritis or enthesitis) and a "P-" group, the subgroup without peripheral involvement (with either arthritis or enthesitis). Correlation of the BASDAI and miniBASDAI with other disease parameters were examined with the Spearman's rank correlation analysis. One hundred and ten patients were recruited. The percentage of patients with pure axial disease manifestation without peripheral involvement "P - group" was 42.7%. We found a similarly good correlation of the miniBASDAI with patient global, physician on disease activity, BASFI, ESR and CRP if compared to the correlation of the original BASDAI with these disease parameters, also in the group without peripheral involvement. Our study suggests that the BASDAI remains valid in assessing disease activity in AS patients with and without peripheral manifestations.

Genetic studies of ankylosing spondylitis in Koreans confirm associations with ERAP1 and 2p15 reported in white patients

OBJECTIVE

Investigators from the Australo-Anglo-American Spondyloarthritis Consortium have reported additional genes associated with ankylosing spondylitis (AS) susceptibility including IL1R2, ANTXR2, and gene deserts at 2p15 and 21q22. We evaluated these new candidate genes in a large cohort of Korean patients with AS.

METHODS

A group of 1164 patients with AS and 752 healthy controls were enrolled for our study. Eight single-nucleotide polymorphisms (SNP) were analyzed to define genetic association with AS by MassARRAY system.

RESULTS

Significant positive associations of AS with endoplasmic reticulum aminopeptidase 1 SNP, rs27037 (p = 1.31 × 10(-4)), and rs27434 (p = 4.59 × 10(-6)), were observed. The rs10865331 of gene desert at 2p15 also showed a significant association with AS (p = 4.63 × 10(-5)).

CONCLUSION

This is the first confirmation in a nonwhite population that genetic polymorphisms of rs27037, rs27434, and rs10865331 are associated with AS, implicating common pathogenetic mechanisms in Korean and white patients with AS.

Association ofARTS1Gene Polymorphisms with Ankylosing Spondylitis in the Hungarian Population: The rs27044 Variant Is Associated with HLA-B*2705 Subtype in Hungarian Patients with Ankylosing Spondylitis

Objective.

Associations have been found between ankylosing spondylitis (AS) and polymorphisms in the aminopeptidase regulator of TNFR1 shedding (ARTS1) gene. We studied the association of 5 polymorphisms within theARTS1gene with AS in Hungarian patients. We also investigated the prevalence of HLA-B27 subtypes in the Hungarian population.

Methods.

A case-control study including 297 patients with AS and 200 sex and ethnically matched healthy controls was performed. Patients and controls were genotyped for rs27044, rs17482078, rs10050860, rs30187, and rs2287987 single-nucleotide polymorphisms using real-time polymerase chain reaction (PCR) allelic discrimination. HLA-B27 subtypes were determined with PCR sequence-specific primer (PCR-SSP) technique.

Results.

We observed a significant increase in the minor allele frequency of rs27044 (p = 0.001) in the AS group compared to controls. The minor allele frequencies of rs10050860 (p = 0.006) and rs2287987 (p = 0.002) showed a significant decrease in AS patients compared to controls. Haplotype analysis revealed association of 2 ARTS1 haplotypes with AS in the Hungarian population. We found that HLA-B*2705 was the predominant subtype in Hungarians with AS. Carriage of the G allele of rs27044 was significantly associated with the HLA-B*2705 subtype (p = 0.009) in AS patients.

Conclusion.

We confirmed reported associations ofARTS1gene polymorphisms with AS in a Hungarian cohort study. We found HLA-B*2705 as the predominant subtype in Hungarian AS patients in accord with other studies on Caucasian populations. Our results suggest that theARTS1gene variants together with HLA-B27 strongly contribute to disease susceptibility in patients with AS.