Clinical and genetic characteristics of ankylosing spondylitis patients with peripheral arthritis at disease onset.

OBJECTIVES: The aim of this study was to assess the clinical and genetic characteristics associated with the presence of peripheral arthritis (PA) at disease onset in patients with ankylosing spondylitis (AS). METHODS: 456 Spanish AS patients, diagnosed according to the modified New York Criteria, who had at least ten years of follow-up since initial disease onset were selected from the National Spondyloarthropathies Registry (REGISPONSER). 18.9% of AS patients initially presented PA. Clinical variables and 384 single nucleotide polymorphisms (SNPs) distributed in 190 genes were analysed. SNP genotyping was performed using the Illumina GoldenGate genotyping platform. Association tests for allele frequencies and for categorical clinical variables were performed by the χ2 test and with the unpaired t-test for continuous variables. p-values of <0.05 were considered statistically significant. RESULTS: AS patients with PA showed an earlier age of disease onset (p=0.021), longer disease duration (p=0.020) and longer duration of AS symptoms from onset (p=0.034) than AS patients without PA. We found significant associations with the presence of PA at disease onset in 14 SNPs located in 10 genes: HLA-DQB2 (rs2857210 and rs9276615), HLA-DOB (rs2857151, rs2621332 and rs1383261), JAK2 (rs7857730), IL-23R (rs11209008 and rs10489630), CYP1B1 (rs1056836), NELL1 (rs8176786), KL (rs564481), and MEFV (rs224204), IL-2RB (rs743777) and IL-1A (rs1800587). CONCLUSIONS: Both clinical and genetic factors are associated with the presence of PA at disease onset in Spanish AS patients. The results suggest that this subset of AS patients with PA at disease onset might have differentiation factors involved in disease pathogenesis.

A genetic predictive model for canine hip dysplasia: integration of Genome Wide Association Study (GWAS) and candidate gene approaches.

Canine hip dysplasia is one of the most prevalent developmental orthopedic diseases in dogs worldwide. Unfortunately, the success of eradication programs against this disease based on radiographic diagnosis is low. Adding the use of diagnostic genetic tools to the current phenotype-based approach might be beneficial. The aim of this study was to develop a genetic prognostic test for early diagnosis of hip dysplasia in Labrador Retrievers. To develop our DNA test, 775 Labrador Retrievers were recruited. For each dog, a blood sample and a ventrodorsal hip radiograph were taken. Dogs were divided into two groups according to their FCI hip score: control (A/B) and case (D/E). C dogs were not included in the sample. Genetic characterization combining a GWAS and a candidate gene strategy using SNPs allowed a case-control population association study. A mathematical model which included 7 SNPs was developed using logistic regression. The model showed a good accuracy (Area under the ROC curve = 0.85) and was validated in an independent population of 114 dogs. This prognostic genetic test represents a useful tool for choosing the most appropriate therapeutic approach once genetic predisposition to hip dysplasia is known. Therefore, it allows a more individualized management of the disease. It is also applicable during genetic selection processes, since breeders can benefit from the information given by this test as soon as a blood sample can be collected, and act accordingly. In the authors' opinion, a shift towards genomic screening might importantly contribute to reducing canine hip dysplasia in the future. In conclusion, based on genetic and radiographic information from Labrador Retrievers with hip dysplasia, we developed an accurate predictive genetic test for early diagnosis of hip dysplasia in Labrador Retrievers. However, further research is warranted in order to evaluate the validity of this genetic test in other dog breeds.

Improved prediction of knee osteoarthritis progression by genetic polymorphisms: the Arthrotest Study.

OBJECTIVE: The aim of this study was to develop a genetic prognostic tool to predict radiographic progression towards severe disease in primary knee OA (KOA) patients. METHODS: This investigation was a cross-sectional, retrospective, multicentric association study in 595 Spanish KOA patients. Caucasian patients aged ≥40 years at the time of diagnosis of primary KOA of Kellgren-Lawrence grade 2 or 3 were included. Patients who progressed to Kellgren-Lawrence score 4 or who were referred for total knee replacement within 8 years after diagnosis were classified as progressors to severe disease. Clinical variables of the initial stages of the disease (gender, BMI, age at diagnosis, OA in the contralateral knee, and OA in other joints) were registered as potential predictors. Single nucleotide polymorphisms and clinical variables with an association of P < 0.05 were included in the multivariate analysis using forward logistic regression. RESULTS: A total of 23 single nucleotide polymorphisms and the time of primary KOA diagnosis were significantly associated with KOA severe progression in the exploratory cohort (n = 220; P < 0.05). The predictive accuracy of the clinical variables was limited: area under the curve (AUC) = 0.66. When genetic variables were added to the clinical model (full model), the prediction of KOA progression was significantly improved (AUC = 0.82). Combining only genetic variables (rs2073508, rs10845493, rs2206593, rs10519263, rs874692, rs7342880, rs780094 and rs12009), a predictive model with good accuracy was also obtained (AUC = 0.78). The predictive ability for KOA progression of the full model was confirmed on the replication cohort (two-sample Z-test; n = 62; P = 0.190). CONCLUSION: An accurate prognostic tool to predict primary KOA progression has been developed based on genetic and clinical information from OA patients.

Candidate's single-nucleotide polymorphism predictors of treatment nonresponse to the first anti-TNF inhibitor in ankylosing spondylitis.

The objective of this study is to identify single-nucleotide polymorphisms (SNPs) predictors of treatment nonresponse to the first anti-TNF-alpha agent in ankylosing spondylitis (AS). Patients were classified as "nonresponders" if they failed to achieve improvement ≥50 % of the initial BASDAI. We selected candidate SNPs previously reported, associated with susceptibility or pathogenesis of AS and with other spondylarthropaties (SpAs). The predictors of nonresponse were modeled with multiple logistic regression. The predictive power of the genetic model of nonresponse to treatment was tested with AUC-ROC. One hundred and twenty-one (121) AS patients fulfilled the inclusion criteria. Of the candidate SNPs tested for association with treatment effectiveness, five independent predictors were identified: rs917997, rs755622, rs1800896, rs3740691, and rs1061622. The genetic model of nonresponse to treatment had a predictive power of 0.77 (95 % CI 0.68-0.86). Our study identified several polymorphisms which could be the useful genetic biomarkers in predicting nonresponse to anti-TNF-alpha therapy.

Both baseline clinical factors and genetic polymorphisms influence the development of severe functional status in ankylosing spondylitis.

Functional severity in ankylosing spondylitis (AS) patients is variable and difficult to predict early. The aim of our study was to assess whether a combination of baseline clinical factors and genetic markers may predict the development of severe functional status in AS. We performed a cross-sectional association study on AS patients included in the Spanish National Registry of Spondyloarthropathies--REGISPONSER. Bath Ankylosing Spondylitis Functional Index (BASFI) was standardized by adjusting for disease duration since the first symptoms (BASFI/t). We considered as severe functional status the values of BASFI/t in the top of the 60th (p60), 65th (p65), 70th (p70), and 75th (p75) percentile. We selected 384 single nucleotide polymorphisms (SNPs) distributed in 190 genes to be analyzed. The study cohort included 456 patients with mean age 50.8(± 10.5) years and with mean disease duration since first symptoms 24.7 (± 10.1) years. Older age at disease onset and neck pain at baseline showed statistical significant association with severe BASFI/t. Polymorphisms associated in the allele frequencies test with severe BASFI/t in all classifications were: rs2542151 (p60 [P = .04], p65 [P = .04], p70 [P = .001] and p75 [P = .001]) and rs2254441 (p60 [P = .004], p65 [P = .02], p70 [P = .01] and p75 [P<.001]).. Genotype association, after adjustment for covariates, found an association in three of the four patients' classifications for rs2542151 and in two of the classifications for rs2254441.Forward logistic regression did not identify any model with a good predictive power for severe functional development.In our study we identified clinical factors and 24 polymorphisms associated with development of severe functional status in AS patients. Validation of these results in other cohorts is required.

Genetic polymorphisms inside and outside the MHC improve prediction of AS radiographic severity in addition to clinical variables.

OBJECTIVE: The aim of this study was to analyse if single nucleotide polymorphisms (SNPs) inside and outside the MHC region might improve the prediction of radiographic severity in AS. METHODS: A cross-sectional multi-centre study was performed including 473 Spanish AS patients previously diagnosed with AS following the Modified New York Criteria and with at least 10 years of follow-up from the first symptoms of AS. Clinical variables and 384 SNPs were analysed to predict radiographic severity [BASRI-total (BASRI-t) corrected for the duration of AS since first symptoms] using multivariate forward logistic regression. Predictive power was measured by the area under the receiver operating characteristic curve (AUC), specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV). RESULTS: The model with the best fit measured radiographic severity as the BASRI-t 60th percentile and combined eight variables: male gender, older age at disease onset and six SNPs at ADRB1 (rs1801253), NELL1 (rs8176785) and MHC (rs1634747, rs9270986, rs7451962 and rs241453) genes. The model predictive power was defined by AUC = 0.76 (95% CI 0.71, 0.80), being significantly better than the model with only clinical variables, AUC = 0.68 (95% CI 0.63, 0.73), P = 0.0004. Internal split-sample analysis proved the validation of the model. Patient genotype for SNPs outside the MHC region, inside the MHC region and clinical variables account for 26, 38 and 36%, respectively, of the explained variability on radiographic severity prediction. CONCLUSION: Prediction of radiographic severity in AS based on clinical variables can be significantly improved by including SNPs both inside and outside the MHC region.

Biphasic adaptative responses in VLDL metabolism and lipoprotein homeostasis during Gram-negative endotoxemia.

Dyslipidemia and hepatic overproduction of very low density lipoprotein (VLDL) are hallmarks of the septic response, yet the underlying mechanisms are not fully defined. We evaluated the lipoprotein subclasses profile and hepatic VLDL assembly machinery over 24 h in fasted LPS-treated rats. The response of serum non-esterified fatty acids (NEFA) and glucose to endotoxin was biphasic, with increased levels of NEFA and hypoglycemia in the first 12 h-phase, and low NEFA and high glucose in the second 12 h-phase. Hypertriglyceridemia was more marked in the first 12 h (6.8-fold), when triglyceride abundance increased in all lipoprotein subclasses, and preferentially in large VLDL. The abundance of medium-sized VLDL and the increase in the number of VLDL particles was higher in the second phase (10-fold vs 5-fold in the first phase); however, apoB gene transcript abundance increased only in the second phase. Analysis of putative pre-translational mechanisms revealed that neither increased Apob transcription rate nor increased transcript binding to mRNA stabilizing HuR (Hu antigen R) protein paralleled the increase in apoB transcripts. In conclusion, endotoxin challenge induces increases in plasma NEFA and large, triglyceride-rich VLDL. After approximately 12 h, the triglyceride-rich VLDLs are replaced by medium-sized, triglyceride-poor VLDL particles. Hepatic apoB mRNA abundance also increases during the second period, suggesting a role for apoB protein expression in the acute reaction against sepsis.

ERAP1 polymorphisms and haplotypes are associated with ankylosing spondylitis susceptibility and functional severity in a Spanish population.

OBJECTIVES: The aim of this study was to assess the involvement of the endoplasmic reticulum aminopeptidase 1 (ERAP1) gene in AS susceptibility and functional severity in a Spanish population. METHODS: Eight single nucleotide polymorphisms (SNPs) spanning the ERAP1 gene were genotyped by allele-specific fluorescent PCR in 300 AS Spanish patients and 300 spondylarthritis-free controls. The influence of the ERAP1 SNPs on the functional severity of AS was analysed with the BASFI corrected for disease duration. Association analyses with AS susceptibility and functional severity were performed. RESULTS: Significant ERAP1 single marker association with AS susceptibility was found for five SNPs, namely rs30187 (allele T: P = 0.035), rs17482078 (allele C: P = 0.030), rs2287987 (allele T: P = 0.028), rs26653 (allele C: P = 0.041) and rs10050860 (allele C: P = 0.018). Three of the associated SNPs (rs17482078, rs2287987 and rs10050860) were in strong linkage disequilibrium. After imputing genotypes with the HapMap CEU data as reference, the strongest association was with rs41135 (P = 0.0046) in the 5'-upstream region of ERAP1. In addition, the SNP rs17481856 was found to be a risk factor for functional severity in AS and a borderline trend was observed for rs27044. CONCLUSIONS: These results suggest that the ERAP1 gene is associated with genetic predisposition to AS and influences the functional severity of the disease in a Spanish population.

Association of the intergenic single-nucleotide polymorphism rs10865331 (2p15) with ankylosing spondylitis in a Spanish population.

OBJECTIVE: A recent genome-wide association study has identified 2 single-nucleotide polymorphisms (SNP) associated with ankylosing spondylitis (AS), rs10865331 (2p15) and rs2242944 (21q22). We assessed the association of these SNP with AS in a Spanish population. METHODS: Four hundred fifty-six patients with AS fulfilling the modified New York Criteria and 300 healthy donors were analyzed. Result. SNP rs10865331 (allele A: p = 0.039; genotype: p = 0.016) was significantly associated with AS, while no association was found for rs2242944. CONCLUSION: This is the first study that replicates in an independent cohort the association of the intergenic SNP rs10865331 with susceptibility to AS.

Kupffer cell products and interleukin 1beta directly promote VLDL secretion and apoB mRNA up-regulation in rodent hepatocytes.

Plasma VLDL accumulation in Gram-negative sepsis is partly ascribed to an increased hepatic VLDL production driven by pro-inflammatory cytokines. We previously showed that hepatocytes of the Kupffer cell (KC)-rich periportal area are major contributors to enhanced VLDL production in lipopolysaccharide (LPS)-injected rats. However, it remains to be established whether KC generated products directly affect the number (apoB) and composition of secreted VLDL. Using rat primary cells, we show here that hepatocytes respond to stimulation by soluble mediators released by LPS-stimulated Kupffer cells with enhanced secretion of apoB and triglycerides in phospholipid-rich VLDL particles. Unstimulated KC products also augmented the secretion of normal VLDL, doubling apoB mRNA abundance. IL-1beta treatment resulted in concentration-dependent increases of hepatocyte apoB mRNA and protein secretion, increases that were greater, but not additive, when combined with IL-6 and TNF-alpha. Lipid secretion and MTP mRNA levels were unaffected by cytokines. In summary: (i) enhanced secretion of phospholipid-rich VLDL particles is a net hepatocyte response to LPS-stimulated KC products, which gives a clue about the local role of Kupffer cells in septic dyslipidemia induction; and (ii) pro-inflammatory cytokines act redundantly to enhance apoB secretion involving translational apoB up-regulation, but other humoral components or KC mediators are necessary to accomplish increased lipid association.

Upregulation of apolipoprotein B secretion, but not lipid, by tumor necrosis factor-alpha in rat hepatocyte cultures in the absence of extracellular fatty acids.

Tumor necrosis factor-alpha (TNF-alpha) plays a pivotal role in the host response to infection. Rapidly liberated to the bloodstream, TNF-alpha triggers the production of other cytokines and the acute-phase response. Hypertriglyceridemia is a sepsis hallmark associated with high plasma levels of very low-density lipoprotein (VLDL) particles, partly ascribed to increased hepatic production. The kinetics of the hepatocyte response, the cytokine/s responsible, and the underlying mechanisms are not fully elucidated. VLDL biogenesis is a complex, time-consuming process that depends on lipid availability and microsomal triglyceride transfer protein (MTP) activity for correct apolipoprotein B (apoB) lipidation. Studies were performed to define the direct effect of TNF-alpha on VLDL secretion rate and composition in rat hepatocytes cultured in conditions resembling the fed situation. Increases of 17-24% in the number of VLDL particles secreted and of 44-88% in the cellular levels of apoB mRNA were caused by 5, 20, or 100 ng/mL TNF-alpha in 8 h. Lipoprotein secretion returned to baseline levels in 16 h, whereas TNF-alpha-treated cells continued to exhibit higher apoB transcript levels. The mass of each lipid class in secreted VLDL and of MTP mRNA in cells was not affected by any of the tested TNF-alpha doses or treatment periods. These findings indicate that over a wide range of concentrations, TNF-alpha was capable of inducing sustained upregulation of apoB mRNA expression and transient increase in secretion of its protein, but, apparently, VLDL triglyceride secretion was not a TNF-alpha target under conditions in which fatty acids were not extracellularly provided.

Isolation and characterization of the rat SND p102 gene promoter: putative role for nuclear factor-Y in regulation of transcription.

In this work, we report the isolation and characterization of a 1,688-bp sequence corresponding to the promoter region of the rat endoplasmic reticulum (ER) cholesterol ester hydrolase gene, renamed as staphylococcal nuclease domain-containing protein of 102 kDa (SND p102) in GenBank database according to the structural properties and molecular weight of the protein. The transcription start site was located 216 bases upstream of the ATG start codon by RNA ligase mediated-rapid amplification of cDNA ends (RLM-RACE). Bioinformatic analysis of the isolated sequence revealed a lack of typical promoter TATA box and the presence of GC-rich motifs and CCAAT boxes recognized by Sp 1 and nuclear factor-Y among other putative binding sites for a number of transcription factors implicated in both basal and regulated processes. Electrophoretic mobility shift and supershift assays using nuclear extracts from human (HepG2) and rat (McA-RH7777) hepatoma cells demonstrated that nuclear factor-Y (NF-Y) transcription factor bound to the core sequences at (-257, -253), (-290, -286), and (-370, -366) upstream translation initiation site. The absence of TATA box and the location and reverse orientation of the CCAAT boxes in the promoter region strongly suggest a role for NF-Y in the regulation of transcription of SND p102 gene.