ANKH and susceptibility to and severity of ankylosing spondylitis

Deciphering the Relationship between Obesity and Various Diseases from a Network Perspective

The number of obesity cases is rapidly increasing in developed and developing countries, thereby causing significant health problems worldwide. The pathologic factors of obesity at the molecular level are not fully characterized, although the imbalance between energy intake and consumption is widely recognized as the main reason for fat accumulation. Previous studies reported that obesity can be caused by the dysfunction of genes associated with other diseases, such as myocardial infarction, hence providing new insights into dissecting the pathogenesis of obesity by investigating its associations with other diseases. In this study, we investigated the relationship between obesity and diseases from Online Mendelian Inheritance in Man (OMIM) databases on the protein–protein interaction (PPI) network. The obesity genes and genes of one OMIM disease were mapped onto the network, and the interaction scores between the two gene sets were investigated on the basis of the PPI of individual gene pairs, thereby inferring the relationship between obesity and this disease. Results suggested that diseases related to nutrition and endocrine are the top two diseases that are closely associated with obesity. This finding is consistent with our general knowledge and indicates the reliability of our obtained results. Moreover, we inferred that diseases related to psychiatric factors and bone may also be highly related to obesity because the two diseases followed the diseases related to nutrition and endocrine according to our results. Numerous obesity–disease associations were identified in the literature to confirm the relationships between obesity and the aforementioned four diseases. These new results may help understand the underlying molecular mechanisms of obesity–disease co-occurrence and provide useful insights for disease prevention and intervention.

Genetic loci that regulate ectopic calcification in response to knee trauma in LG/J by SM/J advanced intercross mice

This study reports on genetic susceptibility to ectopic calcification in the LG/J and SM/J advanced intercross mice. Using 347 mice in 98 full-sibships, destabilization of medial meniscus (DMM) was performed to induce joint injury. We found that joint destabilization instigated ectopic calcifications as detected and quantified by micro-CT. We performed quantitative trait locus (QTL) analysis to map ectopic calcification phenotypes to discrete genomic locations. To validate the functional significance of the selected QTL candidate genes, we compared mRNA expression between parental LG/J and SM/J inbred strains. Overall, we detected 20 QTLs affecting synovial and meniscus calcification phenotypes with 11 QTLs linked to synovial calcification. Functional and bioinformatic analyses of single nucleotide polymorphism (SNP) identified functional classifications relevant to angiogenesis (Myo1e, Kif26b, Nprl3, Stab2, Fam105b), bone metabolism/calcification (Tle3, Tgfb2, Lipc, Nfe2l1, Ank, Fam105b), arthritis (Stab2, Tbx21, Map4k4, Hoxb9, Larp6, Col1a2, Adam10, Timp3, Nfe2l1, Trpm3), and ankylosing-spondylitis (Ank, Pon1, Il1r2, Tbkbp1) indicating that ectopic calcification involves multiple mechanisms. Furthermore, the expression of 11 out of 78 candidate genes was significantly different between LG/J and SM/J. Correlation analysis showed that Aff3, Fam81a, Syn3, and Ank were correlated with synovial calcification. Taken together, our findings of multiple genetic loci suggest the involvement of multiple genes contributing to ectopic calcification.

Gender differences in axial spondyloarthritis

Within the concept of axial spondyloarthritis (axSpA), relevant differences between men and women have been described for patients with the radiographic disease form [ankylosing spondylitis (AS)]. The subjective perception of disease activity (spinal and peripheral pain, fatigue, morning stiffness) has been shown to be higher in female than in male patients. Moreover, women experience more functional limitations and a lower quality of life, despite lower degrees of radiographic spinal damage. Peripheral clinical involvement (arthritis and enthesitis) is, additionally, more predominant in women. On the other hand, a higher level of objective signs of inflammation (C-reactive protein, erythrocyte sedimentation rate, magnetic resonance imaging of sacroiliac joints and spine) has been reported in men. Whether these differences might explain the better response to treatment with anti-tumor necrosis factor agents observed in male patients remains unclear. The underlying causes of the discrepancies are still unknown and genetic, environmental, cultural and/or societal factors may be involved. While AS is still more prevalent in men in a ratio of 2-3:1, the prevalence of males and females in patients with axSpA without radiographic sacroiliac damage is similar. Gender differences in this subgroup of patients have not been adequately addressed, and are particularly needed to further validate the Assessment of SpondyloArthritis international Society classification criteria.

Bone morphogenetic protein 6 polymorphisms are associated with radiographic progression in ankylosing spondylitis

BACKGROUND AND OBJECT

Nearly 25 genetic loci associated with susceptibility to ankylosing spondylitis (AS) have been identified by several large studies. However, there have been limited studies to identify the genes associated with radiographic severity of the disease. Thus we investigated which genes involved in bone formation pathways might be associated with radiographic severity in AS.

METHODS

A total of 417 Korean AS patients were classified into two groups based on the radiographic severity as defined by the modified Stoke' Ankylosing Spondylitis Spinal Score (mSASSS) system. Severe AS was defined by the presence of syndesmophytes and/or fusion in the lumbar or cervical spine (n = 195). Mild AS was defined by the absence of any syndesmophyte or fusion (n = 170). A total of 251 single nucleotide polymorphisms (SNPs) within 52 genes related to bone formation were selected and genotyped. Odds ratios (OR) and 95% confidence interval (95% CI) were analysed by multivariate logistic regression controlling for age at onset of symptoms, sex, disease duration, and smoking status as covariates.

RESULTS

We identified new loci of bone morphogenetic protein 6 (BMP6) associated with radiographic severity in patients with AS that passed false discovery rate threshold. Two SNPs in BMP6 were significantly associated with radiologic severity [rs270378 (OR 1.97, p = 6.74 × 10(-4)) and rs1235192 [OR 1.92, p = 1.17 × 10(-3)]) adjusted by covariates.

CONCLUSION

This is the first study to demonstrate that BMP6 is associated with radiographic severity in AS, supporting the role wingless-type like/BMP pathway on radiographic progression in AS.