Genetics, environment, and gene-environment interactions in the development of systemic rheumatic diseases

Vitamin D and Marine n-3 Fatty Acids for Autoimmune Disease Prevention: Outcomes Two Years After Completion of a Double-Blind, Placebo-Controlled Trial

OBJECTIVE

In the 5.3-year randomized, 2 × 2 factorial, double-blind, placebo-controlled Vitamin D and Omega-3 Trial (VITAL), vitamin D supplementation reduced autoimmune disease (AD) incidence (hazard ratio [HR] 0.78, 95% confidence interval [CI] 0.61-0.99). Omega-3 (n-3) fatty acid supplementation showed a statistically nonsignificant reduction (HR 0.85, 95% CI 0.67-1.08). We aimed to confirm further AD cases arising during and after randomization and assess sustained effects with two years of postintervention observation.

METHODS

Of the 12,786 men aged ≥50 and 13,085 women aged ≥55 initially randomized, we observed surviving and willing participants for two more years. We continued to confirm annual participant-reported new AD by medical record review. Cox models calculated HRs for all confirmed incident AD, (and secondary endpoints, including probable cases, and individual ADs), during the observational and randomized periods.

RESULTS

A total of 21,592 participants (83.5%) were observed for two more years; 514 participants developed incident confirmed AD (236 since prior report), of whom 255 had been randomized to vitamin D versus 259 to vitamin D placebo (HR 0.98 [95% CI 0.83-1.17] at 7 years). AD was confirmed in 234 participants initially randomized to n-3 fatty acids versus 280 randomized to its placebo (HR 0.83 [95% CI 0.70-0.99] at 7 years). Of newly confirmed cases, 65 had onset during randomization; their inclusion changed randomized results as follows: HR 0.85 (95% CI 0.70-1.04) for vitamin D and HR 0.87 (95% CI 0.71-1.06) for n-3 fatty acids.

CONCLUSION

Two years after trial termination, the protective effects of 2000 IU/day of vitamin D dissipated, but 1,000 mg/day of n-3 fatty acids had a sustained effect in reducing AD incidence.

American College of Rheumatology White Paper: The Effects of Climate Change on Rheumatic Conditions-An Evolving Landscape and a Path Forward

OBJECTIVE

Increases in global temperatures and extreme weather events associated with climate change have complex yet poorly understood detrimental impacts on human health. We reviewed the current published literature on climate change-related effects and rheumatic conditions.

METHODS

To summarize our current understanding of the likely effects of climate change, including increased air pollution, on rheumatic disease, we searched the published, peer-reviewed English-language literature from January 2000 to December 2022. Articles were reviewed by a team of rheumatologists and clinical and translational science researchers. Systematic review articles were not included but informed additional literature searches.

RESULTS

After extensive examination and adjudication, 88 articles met inclusion criteria and were selected for review. Much of the epidemiologic investigations assessed associations between air pollution and increased risk of development of rheumatoid arthritis, anti-citrullinated protein antibodies, flares of gout, and hospitalizations for systemic lupus erythematosus. Increased heat vulnerability was associated with higher odds of recurrent hospitalizations across rheumatic conditions. Mechanisms for observed associations are poorly understood but could include the effects of epigenetic changes, oxidative stress, and inflammatory cytokines. Studies had limitations, including restricted geography and populations studied without focus on historically marginalized communities at highest risk for adverse effects from pollution and climate change, the relative lack of mechanistic evaluations, and most with only indirect links to climate change.

CONCLUSION

To date, the published literature lacks studies that directly examine effects of climate change on rheumatic diseases. Collaborative translational and epidemiologic research is needed to enhance our understanding and awareness in this area.

Tumor necrosis factor alpha induced protein 3, interleukin 10, tumor necrosis factor alpha, and interleukin 17 F genes polymorphisms in Algerian patients with rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a systemic autoimmune disease with chronic inflammation. Its pathogenesis involves immunological, genetic, and environmental factors. We investigate the association between Tumor Necrosis Factor α Protein 3 (TNFAIP3), Interleukin 10 (IL10), Tumor Necrosis Factor α (TNF α), and Interleukin 17 F (IL17F) polymorphisms with susceptibility to RA.

METHODS AND RESULTS

191 patients with RA diagnosed according to the American College of Rheumatology (ACR)/ European League Against Rheumatism (EULAR) classification and 190 healthy subjects were recruited. Rheumatoid factor (RF), anti-citrullinated peptide antibodies (ACPA), and C-reactive protein (CRP) were measured. Genotyping of the polymorphisms was performed by real-time PCR. Analysis of the allelic frequencies of TNFAIP3 showed a positive association OR (95% CI) = 1.46 (1.01-2.09); p = 0.04, but failed to meet the criteria of significance after Bonferroni Correction. The genotypic and allelic distribution of the IL10, IL17F, and TNFα showed no significant difference when comparing the RA group with controls. Furthermore, the genotype codominant model shows a moderate positive association in the presence of ACPA (OR (95% CI) = 2.82 (1.22-6.24); p = 0.01. None of the polymorphisms studied was associated with RF and CRP production.

CONCLUSION

Our results show that there is a tendency for the AG genotype of IL10-1082 to be associated with the production of ACPA in patients with RA. None of the variants studied were associated with RA susceptibility in Algerians.

Programmed cell death 10 can be used as a potential biomarker for ankylosing spondylitis diagnosis and treatment

STUDY DESIGN

Diagnostic study.

OBJECTIVE

Programmed cell death 10 (PDCD10) is a new versatile molecule involved in signal transduction regulation in angiogenesis and tumors. The potential of using it as a biomarker for the diagnosis of ankylosing spondylitis (AS) is still unknown.

SETTING

University laboratory in Gannan Medical University, China.

METHODS

Expression of PDCD10 was analyzed using clinical samples of patients with AS and Gene Expression Omnibus (GEO) data GDS5231. To explore its function, PDCD10 was upregulated and downregulated in synovial cells. Spearman analysis was used to study the association between PDCD10 and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). The Receiver operating characteristic (ROC) curve was applied to evaluate the sensitivity and specificity of PDCD10.

RESULTS

Expression of PDCD10 was upregulated in patients with AS and it is capable of promoting the calcification of synovial cells. A positive association between PDCD10 and the BASDAI and the mSASSS was observed. The area under the ROC curve (AUC) of PDCD10 was 82% with a 95% confidence interval of [0.772, 0.868].

CONCLUSIONS

PDCD10 is upregulated in patients with AS and it can promote the calcification of synovial cells in vitro. PDCD10 is positively associated with outcome parameters of AS. ROC analysis of PDCD10 suggests that it can be used as a biomarker for the diagnosis and treatment of AS.

Peptidyl Arginine Deiminases in Chronic Diseases: A Focus on Rheumatoid Arthritis and Interstitial Lung Disease

Protein citrullination is accomplished by a broad enzyme family named Peptidyl Arginine Deiminases (PADs), which makes this post-translational modification in many proteins that perform physiological and pathologic mechanisms in the body. Due to these modifications, citrullination has become a significant topic in the study of pathological processes. It has been related to some chronic and autoimmune diseases, including rheumatoid arthritis (RA), interstitial lung diseases (ILD), multiple sclerosis (MS), and certain types of cancer, among others. Antibody production against different targets, including filaggrin, vimentin, and collagen, results in an immune response if they are citrullinated, which triggers a continuous inflammatory process characteristic of autoimmune and certain chronic diseases. PAD coding genes (PADI1 to PADI4 and PADI6) harbor variations that can be important in these enzymes' folding, activity, function, and half-life. However, few studies have considered these genetic factors in the context of chronic diseases. Exploring PAD pathways and their role in autoimmune and chronic diseases is a major topic in developing new pharmacological targets and valuable biomarkers to improve diagnosis and prevention. The present review addresses and highlights genetic, molecular, biochemical, and physiopathological factors where PAD enzymes perform a major role in autoimmune and chronic diseases.

Population genetics and external proficiency testing for HLA disease associations

Numerous associations of HLA variants with susceptibility to diseases, namely, those with an immunopathological component, have been described to date. The strongest HLA associations were incorporated into the standard algorithms for the diagnostics. Disease-associated HLA variants are routinely detected by various techniques including DNA-based assays. For the identification of HLA markers or their combinations with the highest diagnostic value and those with frequent clinical indications (e.g., HLA-B*27, -B*57:01, -DQ2/-DQ8, -DQB1*06:02), diagnostic tests that focus on a single or limited number of specific HLA antigens/alleles, have already been developed; the use of complete typing for particular HLA loci is a relevant alternative. Importantly, external proficiency testing (EPT) became an integral part of good laboratory practice for HLA disease associations in accredited laboratories and not only supports correct "technical" identification of the associated HLA variants, but also adequate interpretation of the results to the clinicians. In the present article selected aspects of EPT for HLA disease associations related to population genetics are reviewed and discussed with the emphasis on the optimal level of HLA typing resolution, population-based differences in disease associated HLA alleles within the allelic group, distribution and linkage disequilibrium of HLA alleles in particular populations and interpretation of the presence of less common HLA variants/haplotypes. In conclusion, the laboratories that perform and interpret the tests to the clinicians, producers of the certified diagnostics and EPT providers should consider, among others, the genetic characteristics of the populations in order to optimise the diagnostic value of the tests for disease-associated HLA variants.

Protective effects of Typhonii Rhizoma in rheumatoid arthritis rats revealed by integrated metabolomics and network pharmacology

Rheumatoid arthritis (RA) is an autoimmune disease with a 0.5% prevalence worldwide. Inflammation, periosteal proliferation and joint destruction are the main clinical symptoms of RA. Typhonii Rhizoma (TR) is the dry tuber of the Araceae plant Typhonium giganteum Engl, and possesses many uses such as dispelling obstructive wind-phlegm and relieving pain. It is used for the clinical treatment of arthromyodynia and RA. However, the mechanism of action remains unclear. In this study, we first evaluated the effects of TR in type II collagen-induced RA model rats. Secondly, in serum metabolomics, TR could ameliorate 11 potential metabolites in RA model rats and reversed RA through pentose and glucuronate interconversions, sphingolipid metabolism, glycerophospholipid metabolism and tryptophan metabolism. To further explore the mechanisms of TR, 40 chemical constituents were used to establish a component-target interaction network. Some key genes were verified by in vitro pharmacological tests by integrating the results from the network pharmacology and metabolomics. The verification results showed that the mechanisms of TR against RA may be related to the inhibition of the production of inflammatory cytokines and the expression and function of HIF1-α. This study serves as a theoretical basis for the treatment of RA with TR.

Identification of candidate genes and pathways associated with juvenile idiopathic arthritis by integrative transcriptome-wide association studies and mRNA expression profiles

AIM

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease of childhood, with genetic susceptibility and pathological processes such as autoimmunity and autoinflammation, but its pathogenesis is unclear. We conducted a transcriptome-wide association study (TWAS) using expression interpolation from a large-scale genome-wide association study (GWAS) dataset to identify genes, biological pathways, and environmental chemicals associated with JIA.

METHODS

We obtained published GWAS data on JIA for TWAS and used mRNA expression profiling to validate the genes identified by TWAS. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. A protein-protein interaction (PPI) network was generated, and central genes were obtained using Molecular Complex Detection (MCODE). Finally, chemical gene expression datasets were obtained from the Comparative Toxicogenomics database for chemical genome enrichment analysis.

RESULTS

TWAS identified 1481 genes associated with JIA, and 154 differentially expressed genes were identified based on mRNA expression profiles. After comparing the results of TWAS and mRNA expression profiles, we obtained eight overlapping genes. GO and KEGG enrichment analyses of the genes identified by TWAS yielded 163 pathways, and PPI network analysis as well as MCODE resolution identified a total of eight clusters. Through chemical gene set enrichment analysis, 287 environmental chemicals associated with JIA were identified.

CONCLUSION

By integrating TWAS and mRNA expression profiles, genes, biological pathways, and environmental chemicals associated with JIA were identified. Our findings provide new insights into the pathogenesis of JIA, including candidate genetic and environmental factors contributing to its onset and progression.

MicrobiomeGWAS: A Tool for Identifying Host Genetic Variants Associated with Microbiome Composition

The microbiome is the collection of all microbial genes and can be investigated by sequencing highly variable regions of 16S ribosomal RNA (rRNA) genes. Evidence suggests that environmental factors and host genetics may interact to impact human microbiome composition. Identifying host genetic variants associated with human microbiome composition not only provides clues for characterizing microbiome variation but also helps to elucidate biological mechanisms of genetic associations, prioritize genetic variants, and improve genetic risk prediction. Since a microbiota functions as a community, it is best characterized by β diversity; that is, a pairwise distance matrix. We develop a statistical framework and a computationally efficient software package, microbiomeGWAS, for identifying host genetic variants associated with microbiome β diversity with or without interacting with an environmental factor. We show that the score statistics have positive skewness and kurtosis due to the dependent nature of the pairwise data, which makes p-value approximations based on asymptotic distributions unacceptably liberal. By correcting for skewness and kurtosis, we develop accurate p-value approximations, whose accuracy was verified by extensive simulations. We exemplify our methods by analyzing a set of 147 genotyped subjects with 16S rRNA microbiome profiles from non-malignant lung tissues. Correcting for skewness and kurtosis eliminated the dramatic deviation in the quantile–quantile plots. We provided preliminary evidence that six established lung cancer risk SNPs were collectively associated with microbiome composition for both unweighted (p = 0.0032) and weighted (p = 0.011) UniFrac distance matrices. In summary, our methods will facilitate analyzing large-scale genome-wide association studies of the human microbiome.

The Geospatial Distribution of Myositis and Its Phenotypes in the United States and Associations With Roadways: Findings From a National Myositis Patient Registry

Background

Little is known about the spatial distribution of idiopathic inflammatory myopathies (IIM) in the United States (U.S.), or their geospatial associations.

Methods

We studied a national myositis patient registry, with cases diagnosed in the contiguous U.S. from 1985–2011 and comprised of dermatomyositis (DM, n = 484), polymyositis (PM, n = 358), and inclusion body myositis (IBM, n = 318) patients. To assess the association of myositis prevalence with distance from roads, we employed log-Gaussian Cox process models, offset with population density.

Results

The U.S. IIM case distribution demonstrated a higher concentration in the Northest. DM, IBM, and cases with lung disease were more common in the East, whereas PM cases were more common in the Southeast. One area in the West and one area in the South had a significant excess in cases of DM relative to PM and of cases with lung disease relative to those without lung disease, respectively. IIM cases tended to cluster, with between-points interactions more intense in the Northeast and less in the South. There was a trend of a higher prevalence of IIM and its major phenotypes among people living within 50 m of a roadway relative to living beyond 200 m. Demographic characteristics, rural-urban commuting area, and female percentage were significantly associated with the prevalence of IIM and with major phenotypes.

Conclusions

Using a large U.S. database to evaluate the spatial distribution of IIM and its phenotypes, this study suggests clustering in some regions of the U.S. and a possible association of proximity to roadways.

Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial

OBJECTIVE

To investigate whether vitamin D and marine derived long chain omega 3 fatty acids reduce autoimmune disease risk.

DESIGN

Vitamin D and omega 3 trial (VITAL), a nationwide, randomized, double blind, placebo controlled trial with a two-by-two factorial design.

SETTING

Nationwide in the United States.

PARTICIPANTS

25 871 participants, consisting of 12 786 men ≥50 years and 13 085 women ≥55 years at enrollment.

INTERVENTIONS

Vitamin D (2000 IU/day) or matched placebo, and omega 3 fatty acids (1000 mg/day) or matched placebo. Participants self-reported all incident autoimmune diseases from baseline to a median of 5.3 years of follow-up; these diseases were confirmed by extensive medical record review. Cox proportional hazard models were used to test the effects of vitamin D and omega 3 fatty acids on autoimmune disease incidence.

MAIN OUTCOME MEASURES

The primary endpoint was all incident autoimmune diseases confirmed by medical record review: rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease, psoriasis, and all others.

RESULTS

25 871 participants were enrolled and followed for a median of 5.3 years. 18 046 self-identified as non-Hispanic white, 5106 as black, and 2152 as other racial and ethnic groups. The mean age was 67.1 years. For the vitamin D arm, 123 participants in the treatment group and 155 in the placebo group had a confirmed autoimmune disease (hazard ratio 0.78, 95% confidence interval 0.61 to 0.99, P=0.05). In the omega 3 fatty acids arm, 130 participants in the treatment group and 148 in the placebo group had a confirmed autoimmune disease (0.85, 0.67 to 1.08, P=0.19). Compared with the reference arm (vitamin D placebo and omega 3 fatty acid placebo; 88 with confirmed autoimmune disease), 63 participants who received vitamin D and omega 3 fatty acids (0.69, 0.49 to 0.96), 60 who received only vitamin D (0.68, 0.48 to 0.94), and 67 who received only omega 3 fatty acids (0.74, 0.54 to 1.03) had confirmed autoimmune disease.

CONCLUSIONS

Vitamin D supplementation for five years, with or without omega 3 fatty acids, reduced autoimmune disease by 22%, while omega 3 fatty acid supplementation with or without vitamin D reduced the autoimmune disease rate by 15% (not statistically significant). Both treatment arms showed larger effects than the reference arm (vitamin D placebo and omega 3 fatty acid placebo).

STUDY REGISTRATION

ClinicalTrials.gov NCT01351805 and NCT01169259.

Passive Smoking Throughout the Life Course and the Risk of Incident Rheumatoid Arthritis in Adulthood Among Women

OBJECTIVE

To investigate passive smoking throughout the life course and the risk of rheumatoid arthritis (RA), while accounting for personal smoking.

METHODS

We analyzed the Nurses' Health Study II prospective cohort, using information collected via biennial questionnaires. We assessed the influence of 1) maternal smoking during pregnancy (in utero exposure), 2) childhood parental smoking, and 3) years lived with smokers since age 18. Incident RA and serostatus were determined by medical record review. Using the marginal structural model framework, we estimated the controlled direct effect of each passive smoking exposure on adult incident RA risk by serologic phenotype, controlling for early-life factors and time-updated adulthood factors including personal smoking.

RESULTS

Among 90,923 women, we identified 532 incident RA cases (66% seropositive) during a median of 27.7 years of follow-up. Maternal smoking during pregnancy was associated with RA after adjustment for confounders, with a hazard ratio (HR) of 1.25 (95% confidence interval [95% CI] 1.03-1.52), but not after accounting for subsequent smoking exposures. Childhood parental smoking was associated with seropositive RA after adjustment for confounders (HR 1.41 [95% CI 1.08-1.83]). In the controlled direct effect analyses, childhood parental smoking was associated with seropositive RA (HR 1.75 [95% CI 1.03-2.98]) after controlling for adulthood personal smoking, and the association was accentuated among ever smokers (HR 2.18 [95% CI 1.23-3.88]). There was no significant association of adulthood passive smoking with RA (HR 1.30 for ≥20 years of living with a smoker versus none [95% CI 0.97-1.74]).

CONCLUSION

We found a potential direct influence of childhood parental smoking on adult-onset incident seropositive RA even after controlling for adulthood personal smoking.

Regulatory Role of the RNA N6-Methyladenosine Modification in Immunoregulatory Cells and Immune-Related Bone Homeostasis Associated With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease for which the etiology has not been fully elucidated. Previous studies have shown that the development of RA has genetic and epigenetic components. As one of the most highly abundant RNA modifications, the N⁶-methyladenosine (m⁶A) modification is necessary for the biogenesis and functioning of RNA, and modification aberrancies are associated with various diseases. However, the specific functions of m⁶A in the cellular processes of RA remain unclear. Recent studies have revealed the relationship between m⁶A modification and immune cells associated with RA. Therefore, in this review, we focused on discussing the functions of m⁶A modification in the regulation of immune cells and immune-related bone homeostasis associated with RA. In addition, to gain a better understanding of the progress in this field of study and provide the proper direction and suggestions for further study, clinical application studies of m⁶A modification were also summarized.

T cell immunoglobulin and mucin domain-3 is associated with disease activity and progressive joint damage in rheumatoid arthritis patients

T cell immunoglobulin and mucin domain-3 (TIM-3) is a surface molecule expressed on immune cells which play a role in immune regulation. The aims of the present study were to determine whether circulating soluble T cell immunoglobulin domain and mucin-3 (sTIM-3) are elevated in rheumatoid arthritis (RA) patients, and investigate the relationships between sTIM-3 and clinical features of RA.The study included 116 patients with established RA and 27 healthy control subjects. Serum levels of sTIM-3 were measured via the enzyme-linked immunosorbent assays (ELISA). Correlations between serum sTIM-3 and a range of parameters including anti-citrullinated peptide antibody (ACPA) titer, erythrocyte sedimentation rate (ESR), and matrix metalloproteinase-3 (MMP-3) were assessed.Serum sTIM-3 was significantly elevated in RA patients compared with those in healthy subjects, and it was positively correlated with ACPA titer (r = 0.27 P = .005), ESR (r = 0.27, P = .004) and MMP-3 (r = 0.35, P < .001). In RA patients with high ACPA titers (≥200 U/mL), sTIM-3 was not correlated with ESR or MMP-3. Whereas, sTIM-3 was significantly correlated with ESR and MMP-3 in RA patients with low ACPA titers (<200 U/mL).Serum sTIM-3 was increased in RA patients, and it was associated with proinflammatory markers and disease activity in RA patients under a particular ACPA status. Our data suggest that circulating sTIM-3 may be a useful biomarker for the determination of disease activity in RA patients.

Contribution of Multiplex Immunoassays to Rheumatoid Arthritis Management: From Biomarker Discovery to Personalized Medicine

Rheumatoid arthritis (RA) is a multifactorial, inflammatory and progressive autoimmune disease that affects approximately 1% of the population worldwide. RA primarily involves the joints and causes local inflammation and cartilage destruction. Immediate and effective therapies are crucial to control inflammation and prevent deterioration, functional disability and unfavourable progression in RA patients. Thus, early diagnosis is critical to prevent joint damage and physical disability, increasing the chance of achieving remission. A large number of biomarkers have been investigated in RA, although only a few have made it through the discovery and validation phases and reached the clinic. The single biomarker approach mostly used in clinical laboratories is not sufficiently accurate due to its low sensitivity and specificity. Multiplex immunoassays could provide a more complete picture of the disease and the pathways involved. In this review, we discuss the latest proposed protein biomarkers and the advantages of using protein panels for the clinical management of RA. Simultaneous analysis of multiple proteins could yield biomarker signatures of RA subtypes to enable patients to benefit from personalized medicine.

Latin American Genes: The Great Forgotten in Rheumatoid Arthritis

The successful implementation of personalized medicine will rely on the integration of information obtained at the level of populations with the specific biological, genetic, and clinical characteristics of an individual. However, because genome-wide association studies tend to focus on populations of European descent, there is a wide gap to bridge between Caucasian and non-Caucasian populations before personalized medicine can be fully implemented, and rheumatoid arthritis (RA) is not an exception. In this review, we discuss advances in our understanding of genetic determinants of RA risk among global populations, with a focus on the Latin American population. Geographically restricted genetic diversity may have important implications for health and disease that will remain unknown until genetic association studies have been extended to include Latin American and other currently under-represented ancestries. The next few years will witness many breakthroughs in personalized medicine, including applications for common diseases and risk stratification instruments for targeted prevention/intervention strategies. Not all of these applications may be extrapolated from the Caucasian experience to Latin American or other under-represented populations.

The Genetics of Spondyloarthritis

The term spondyloarthritis (SpA) encompasses a group of chronic inflammatory diseases with common features in terms of clinical presentation and genetic predisposition. SpA is characterized by inflammation of the spine and peripheral joints, and is also be associated with extra-articular inflammatory manifestations such as psoriasis, uveitis, or inflammatory bowel disease (IBD). The etiology of SpA is not completely understood, but it is known to have a strong genetic component dominated by the human leukocyte antigen (HLA)-B27. In the last few years, our understanding of genetic susceptibility to SpA, particularly ankylosing spondylitis (AS), has greatly improved thanks to the findings derived from powered genome-wide association studies (GWAS) based on single nucleotide polymorphism (SNP) arrays. These studies have identified many candidate genes, therefore providing new potential directions in the exploration of disease mechanisms, especially with regard to the key role of the immune system in the pathogenesis of SpA. SpA is a complex disease where genetic variability, environmental factors, and random events interact to trigger pathological pathways. The aim of this review is to summarize current findings on the genetics of SpA, some of which might help to study new treatment approaches.

Interactions Between Genome-Wide Genetic Factors and Smoking Influencing Risk of Systemic Lupus Erythematosus

OBJECTIVE

To identify interactions between genetic factors and current or recent smoking in relation to risk of developing systemic lupus erythematosus (SLE).

METHODS

For the study, 673 patients with SLE (diagnosed according to the American College of Rheumatology 1997 updated classification criteria) were matched by age, sex, and race (first 3 genetic principal components) to 3,272 control subjects without a history of connective tissue disease. Smoking status was classified as current smoking/having recently quit smoking within 4 years before diagnosis (or matched index date for controls) versus distant past/never smoking. In total, 86 single-nucleotide polymorphisms and 10 classic HLA alleles previously associated with SLE were included in a weighted genetic risk score (wGRS), with scores dichotomized as either low or high based on the median value in control subjects (low wGRS being defined as less than or equal to the control median; high wGRS being defined as greater than the control median). Conditional logistic regression models were used to estimate both the risk of SLE and risk of anti-double-stranded DNA autoantibody-positive (dsDNA+) SLE. Additive interactions were assessed using the attributable proportion (AP) due to interaction, and multiplicative interactions were assessed using a chi-square test (with 1 degree of freedom) for the wGRS and for individual risk alleles. Separate repeated analyses were carried out among subjects of European ancestry only.

RESULTS

The mean ± SD age of the SLE patients at the time of diagnosis was 36.4 ± 15.3 years. Among the 673 SLE patients included, 92.3% were female and 59.3% were dsDNA+. Ethnic distributions were as follows: 75.6% of European ancestry, 4.5% of Asian ancestry, 11.7% of African ancestry, and 8.2% classified as other ancestry. A high wGRS (odds ratio [OR] 2.0, P = 1.0 × 10^-51 versus low wGRS) and a status of current/recent smoking (OR 1.5, P = 0.0003 versus distant past/never smoking) were strongly associated with SLE risk, with significant additive interaction (AP 0.33, P = 0.0012), and associations with the risk of anti-dsDNA+ SLE were even stronger. No significant multiplicative interactions with the total wGRS (P = 0.58) or with the HLA-only wGRS (P = 0.06) were found. Findings were similar in analyses restricted to only subjects of European ancestry.

CONCLUSION

The strong additive interaction between an updated SLE genetic risk score and current/recent smoking suggests that smoking may influence specific genes in the pathogenesis of SLE.

[Characteristics of intestinal flora in patients with primary Sjögren syndrome]

OBJECTIVE

To investigate changes in intestinal flora in patients with primary Sj?gren syndrome (pSS) and explore the relationship between pSS disease activity and intestinal flora structure.

METHODS

Fecal samples were collected from 18 female pSS patients, including 9 patients with active disease (group A) and 9 with disease inactivity or low activity (group B), with 10 healthy subjects as the control group. The total bacterial DNA was extracted from the fecal samples for PCR amplification, and Illumina Hiseq 2500 high-throughput sequencing was performed for the v3-v4 region of 16Sr DNA gene to obtain the biological information of the intestinal flora. The intergroup OTU analysis, structural diversity analysis, significant difference analysis and LEFSE analysis were performed with information mining of the literature think tanks.

RESULTS

The dilution curves generated based on the OTUshannon index for analysis of sample complexity showed that the measured data were relatively complete and could reflect the diversity of the microorganisms in the subjects. Analysis of the Alpha diversity index showed that the Shannon index differed significantly between group A and group B, and the Simpson index differed significantly between group A and group B and between group A and the control group (P &lt; 0.05). Sequence analysis the 3 groups all consisted mainly of 4 phylum (Firmicutes, Bacteroidetes, Actinobacteria, showed that the intestinal flora in and proteobacteria) and 4 genera (finegoldia, Prevotella, Streptococcus, and Corynebacterium_1), all showing no significant differences among the 3 groups (P &gt; 0.05) with the exception of Streptococcus genus, which differed significantly among the 3 groups (P &lt; 0.05). The 16S v3-v4 region in the genus Alloscardovia, Bacteroides, Barnesiella, Butyricicoccus, Facklamia, Faecalibacterium, Lachnospiraceae_FCS020_group, Lachnospiraceae_ND3007_group, Lachnospiraceae_UCG-001, Lachnospirace, Lachnospirace, Ruminococcaceae_UCG-002, Streptococcus and Coprococcus_1 differed significantly among the 3 groups (P &lt; 0.05). The high-dimensional biometrics and genomic characteristics of the intestinal microorganisms differed significantly among the 3 groups (P &lt; 0.05). According to the size of LDA SCORE (effect size), the core flora in group A included the genera Barnesiellaccae, Aerococcaceae, Family-XIII, Bacteroidaceae, Lachnospiraceae_UCG-001, Barnesiella, Facklamia, Alloscardovia, Faecalibacterium and Bacteroides, as compared with the genera Streptococcaceae, Streptococcus, Coprococcus_1, Ruminococcaceae_ucg-002, Lachnospiraceae_FCS020_group, Lachnospiraceae_ucg-004, Lachnospiraceae_ND3007_group, Lachnospiraceae_ucg-008 and Butyricicoccus in the control group.

CONCLUSIONS

Patients with pSS have significant changes in the diversity of intestinal flora, especially in some specific bacteria in Streptococcu genus and in 16S v3-v4 region of the bacteria. The differences in the core bacteria in the intestinal flora of pSS patients suggest the role of flora structure changes in the pathogenesis of pSS.

Genetic Polymorphisms Associated with Rheumatoid Arthritis Development and Antirheumatic Therapy Response

Rheumatoid arthritis (RA) is the most common inflammatory arthropathy worldwide. Possible manifestations of RA can be represented by a wide variability of symptoms, clinical forms, and course options. This multifactorial disease is triggered by a genetic predisposition and environmental factors. Both clinical and genealogical studies have demonstrated disease case accumulation in families. Revealing the impact of candidate gene missense variants on the disease course elucidates understanding of RA molecular pathogenesis. A multivariate genomewide association study (GWAS) based analysis identified the genes and signalling pathways involved in the pathogenesis of the disease. However, these identified RA candidate gene variants only explain 30% of familial disease cases. The genetic causes for a significant proportion of familial RA have not been determined until now. Therefore, it is important to identify RA risk groups in different populations, as well as the possible prognostic value of some genetic variants for disease development, progression, and treatment. Our review has two purposes. First, to summarise the data on RA candidate genes and the increased disease risk associated with these alleles in various populations. Second, to describe how the genetic variants can be used in the selection of drugs for the treatment of RA.

Efficacy and safety of sarilumab in combination with csDMARDs or as monotherapy in subpopulations of patients with moderately to severely active rheumatoid arthritis in three phase III randomized, controlled studies

Background

The interleukin-6 receptor inhibitor sarilumab demonstrated efficacy in combination with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or as monotherapy in patients with moderately to severely active rheumatoid arthritis (RA) with an inadequate response (IR) or intolerant (INT) to methotrexate (MTX) or tumour necrosis factor (TNF)-α inhibitors. This analysis investigated the efficacy and safety of sarilumab in patient subgroups.

Methods

Data were included from phase III studies: two placebo-controlled studies of subcutaneous sarilumab 150/200 mg every 2 weeks (q2w) either + MTX in MTX-IR patients (52 weeks) or + csDMARDs in TNF-IR/INT patients (24 weeks), and a monotherapy study of sarilumab 200 mg q2w vs. adalimumab 40 mg q2w in MTX-IR/INT patients (24 weeks). Prespecified and post hoc subgroups included patient demographics, disease characteristics, and prior treatments. Prespecified and post hoc endpoints included clinical, radiographic, and physical function measures, and p values are considered nominal. Safety was assessed during double-blind treatment.

Results

The superiority of sarilumab (either as monotherapy vs. adalimumab or in combination with csDMARDs vs. placebo + csDMARDs) across clinical endpoints was generally consistent across subgroups defined by patient demographics, disease characteristics, and prior treatments, demonstrating the benefit of sarilumab treatment for a wide range of patient types. Interaction p values of < 0.05 were consistently observed across studies only for baseline anti-cyclic citrullinated peptide antibody (ACPA) status for American College of Rheumatology 20% response, but not American College of Rheumatology 50% or 70% response. Adverse events and worsening laboratory parameters occurred more frequently in sarilumab-treated vs. placebo-treated patients and were more frequent in the small number of patients ≥ 65 years (n = 289) vs. patients < 65 years (n = 1819). Serious infections occurred in six patients aged ≥ 65 years receiving sarilumab, although the incidence of serious infections was generally higher in patients aged ≥ 65 years regardless of treatment.

Conclusions

Apart from ACPA status, there were no consistent signals indicating differential effects of sarilumab in any of the subpopulations assessed. Sarilumab demonstrated consistent efficacy and safety across a wide range of patients with RA.

Trial registration

ClinicalTrials.gov NCT01061736, registered on February 03, 2010; ClinicalTrials.gov NCT01709578, registered on October 18, 2012; ClinicalTrials.gov NCT02332590, registered on January 07, 2015

Relationship of CARD8 Gene Polymorphisms with Susceptibility to Ankylosing Spondylitis: A Case-Control Study

BACKGROUND The aim of this case-control study was to evaluate the correlation of caspase recruitment domain-containing protein 8 (CARD8) gene rs2043211 (exon) and rs7253718 (intron) polymorphisms with the susceptibility of ankylosing spondylitis (AS) in the Chinese Han population. MATERIAL AND METHODS CARD8 polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 118 AS patients and 122 healthy persons. Linkage disequilibrium (LD) and haplotype analysis were carried out using Haploview software. Distribution differences of genotypes, alleles and haplotypes between the case and control groups were tested by chi-square test. Relative risk of AS was expressed by odds ratios (ORs) and 95% confidence intervals (CIs). Logistic regression analysis was used to adjust the results of association by clinical parameters. RESULTS For rs2043211, distribution of variant allele T was obviously different between AS patients and healthy controls (P=0.046). It indicated that T allele might increase the susceptibility of AS (OR=1.441, 95%CI=1.006-2.065). Adjusted by clinical characteristics, the significance of difference was slightly decreased (P=0.050, OR=1.439, 95%CI=0.999-2.072). Strong LD existed between rs2043211 and rs7253718 polymorphisms, and rs2043211T-rs7253718G haplotype was significantly associated with increased AS susceptibility (OR=1.787, 95%CI=1.165-2.740). In subgroup analysis, we found that the TT genotype and T allele of rs2043211 significantly increased the risk of AS in males (TT versus AA: OR=2.554, 95%CI=1.079-6.049; T versus A: OR=1.661, 95%CI=1.067-2.586), but not females. CONCLUSIONS CARD8 polymorphisms are likely to be associated with the elevated susceptibility of AS. Present results should be confirmed in the future studies.

Fatigue in Ankylosing Spondylitis Is Associated With Psychological Factors and Brain Gray Matter

Background: Ankylosing spondylitis (AS) is a rheumatic inflammatory disease with unknown etiology, and fatigue is one of the main systemic symptoms of AS. The aim of the current study was to explore the mechanism of AS-associated fatigue (ASF) from multiple aspects, including neuropsychological changes.

Method: A total of 120 AS patients and 78 age- and sex-matched healthy individuals were recruited into the study. Fatigue was assessed by the fatigue item of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Multidimensional Assessment of Fatigue (MAF) scale. Anxiety and depression were assessed by the Hospital Anxiety and Depression Scale (HADS). The cortical thickness and subcortical gray matter volume were assessed using a Philips Achieva 3.0 T TX MRI scanner.

Result: Of the 120 AS patients, 103 (85.8%) reported varying degrees of fatigue. Among these fatigue cases, 33 (32.0%) were in the severe fatigue group (BASDAI-Fatigue ≥ 5), and 70 patients (68.0%) were considered to be in the mild fatigue group (BASDAI-Fatigue > 0 but <5). The BASDAI, ASDAS-CRP, HAD-A, and HAD-D scores of AS patients in the severe fatigue group were all significantly higher than those of patients in the mild fatigue and non-fatigue groups (all, P < 0.05). The structural equation model suggested that AS activity triggered the occurrence of fatigue by inducing psychological change. Finally, head MRI imaging found that the left thalamus volume in AS patients with severe fatigue was significantly larger than that in non-fatigue AS patients and healthy controls (both, P < 0.05).

Conclusion: The study revealed neuropsychological factors involved in fatigue in AS.

Treatment failure in inflammatory arthritis: time to think about syndemics?

Social determinants of health play a crucial role in health and disease. In current times, it has become increasingly known that biological and non-biological factors are potentially linked and help to drive disease. For example, links between various comorbidities, both physical and mental illnesses, are known to be driven by social, environmental and economic determinants. This contributes to worse disease outcomes. This article discusses the concept of syndemics, which although well-described in some conditions, represents a novel concept in the context of rheumatic and musculoskeletal diseases. Written in the form of a viewpoint, the article focuses on a novel theoretical framework for studying inflammatory arthritis, based on a syndemic approach that takes into account the social context, biocultural disease interaction, and socio-economic characteristics of the setting. Syndemics involving inflammatory arthritis may be most likely in a social context involving limited access to health care, lack of physical activity and obesogenic diets, high rates of alcohol consumption, and high exposure to stressful life events.

Epigenetic Changes in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease that affects about 1% of the world’s population. The etiology of RA remains unknown. It is considered to occur in the presence of genetic and environmental factors. An increasing body of evidence pinpoints that epigenetic modifications play an important role in the regulation of RA pathogenesis. Epigenetics causes heritable phenotype changes that are not determined by changes in the DNA sequence. The major epigenetic mechanisms include DNA methylation, histone proteins modifications and changes in gene expression caused by microRNAs and other non-coding RNAs. These modifications are reversible and could be modulated by diet, drugs, and other environmental factors. Specific changes in DNA methylation, histone modifications and abnormal expression of non-coding RNAs associated with RA have already been identified. This review focuses on the role of these multiple epigenetic factors in the pathogenesis and progression of the disease, not only in synovial fibroblasts, immune cells, but also in the peripheral blood of patients with RA, which clearly shows their high diagnostic potential and promising targets for therapy in the future.

The study of interactions between genome and exposome in the development of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic inflammatory autoimmune disease characterized by a broad spectrum of clinical and serological manifestations. This may reflect a complex and multifactorial etiology involving several identified genetic and environmental factors, though not explaining the full risk of SLE. Established SLE risk genotypes are either very rare or with modest effect sizes and twin studies indicate that other factors besides genetics must be operative in SLE etiology. The exposome comprises the cumulative environmental influences on an individual and associated biological responses through the lifespan. It has been demonstrated that exposure to silica, smoking and exogenous hormones candidate as environmental risk factors in SLE, while alcohol consumption seems to be protective. Very few studies have investigated potential gene-environment interactions to determine if some of the unexplained SLE risk is attributable hereto. Even less have focused on interactions between specific risk genotypes and environmental exposures relevant to SLE pathogenesis. Cohort and case-control studies may provide data to suggest such biological interactions and various statistical measures of interaction can indicate the magnitude of such. However, such studies do often have very large sample-size requirements and we suggest that the rarity of SLE to some extent can be compensated by increasing the ratio of controls. This review summarizes the current body of knowledge on gene-environment interactions in SLE. We argue for the prioritization of studies that comprise the increasing details available of the genome and exposome relevant to SLE as they have the potential to disclose new aspects of SLE pathogenesis including phenotype heterogeneity.

Hidradenitis Suppurativa: A Systematic Review Integrating Inflammatory Pathways Into a Cohesive Pathogenic Model

Background: The pathogenesis of hidradenitis suppurativa (HS) is not fully understood. This systematic review examined the latest evidence for molecular inflammatory pathways involved in HS as a chronic inflammatory skin disease.

Methods: A systematic literature search was performed in PubMed/Medline and EMBASE from January 2013 through September 2017, according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA). Findings on HS pathogenesis were also compared with those of other immune-mediated inflammatory diseases (IMIDs) in a non-systematic review. In addition, current therapeutic options for HS are briefly discussed on the basis of the findings for the inflammatory pathways involved in HS.

Results: A total of 32 eligible publications were identified by the systematic search; these were supplemented with three additional publications. The extracted data indicated that four key themes underlie the pathogenesis of HS and related syndromic conditions. First, nicastrin (NCSTN) and PSTPIP1 mutations are directly associated with auto-inflammatory disease. Secondly, the up-regulation of several cytokines including tumor necrosis factor-α and T helper-17/interleukin-23 are connected to auto-inflammatory mechanisms in the pathogenesis of HS. Thirdly, the microbiome of lesional skin differs significantly vs. normal-appearing skin. Fourthly, HS risk is enhanced through physiological and environmental factors such as smoking, obesity, and mechanical friction. There is significant overlap between the pathogenesis of HS, its syndromic forms and other IMIDs, particularly with respect to aberrations in the innate immune response.

Conclusions: The evidence presented in this review supports HS as an auto-inflammatory skin disorder associated with alterations in the innate immune system. Based on these most recent data, an integrative viewpoint is presented on the pathogenesis of HS. Current management strategies on HS consist of anti-inflammatory therapies, surgical removal of chronic lesions, and lifestyle changes such as smoking cessation and weight loss. As large gaps remain in the understanding of the pathogenesis of HS, further research is warranted to ultimately improve the management and treatment of patients with HS and related syndromic conditions.

Association between MEFV polymorphisms and the susceptibility to ankylosing spondylitis in a Chinese Han population: A case-control study

The aim of this study was to explore the genetic association of Mediterranean fever (MEFV) gene polymorphisms rs3743930 and rs11466023 with ankylosing spondylitis (AS) susceptibility in a cohort of Chinese Han population.Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used for genotyping MEFV polymorphisms in 131 AS patients and 127 healthy controls. Chi-square test was employed to compare the genotype and allele distributions between the case and control groups. Odds ratio (OR) with 95% confidence interval (CI) was calculated to assess the association between MEFV gene polymorphisms and AS incidence.The frequency of the G allele of MEFV polymorphism rs3743930 in the AS group was significantly higher than that in the healthy control group (36.64% vs 28.35%, P < .05). And individuals carrying the GG genotype showed 2.896 folds higher risk of developing AS when compared with CC genotype carriers (OR = 2.896, 95% CI = 1.115-7.519). But no significant differences were detected in either genotype or allele distributions between case and control groups for the polymorphism rs11466023 (P > .05).MEFV gene polymorphism rs3743930 might be significantly associated with AS susceptibility in Chinese Han population, and its G allele might predict high risk of AS.

Cigarette smoking and the pathogenesis of systemic lupus erythematosus

INTRODUCTION

Systemic lupus erythematosus (SLE) is a multi-system inflammatory autoimmune disease of incompletely understood etiology. It is thought that environmental exposures 'trigger' or accelerate the disease in genetically-predisposed individuals. Areas covered: Substantial epidemiological evidence exists to support the association between cigarette smoking and the risk of incident SLE. Recent evidence points to current smoking as the specific risk factor, with decreasing risk 5 years after smoking cessation, and the greatest risk for disease characterized by the presence of SLE-specific autoantibodies. Research has begun to search for possible explanations for the temporal nature of the relationship between current smoking and autoantibody positive-SLE. Here we review potential biologic mechanisms linking smoking and SLE risk, including effects upon T and B cells, inflammatory cytokines, oxidative stress, and the formation of short-lived DNA adducts. Expert commentary: The directions for future research in this field include studies of gene-environment interactions, epigenetics, metabolomics and putative biologic mechanisms.

Delayed-type hypersensitivity to metals in connective tissue diseases and fibromyalgia

Rheumatic diseases include a group of autoimmune disorders with environmental and genetic etiology that are characterized as a subgroup of connective tissue diseases (CTD). Rheumatoid arthritis (RA) often involves the small joints of the hands in a symmetrical fashion that can lead to loss of joint function, and RA, as well as Sjögren's syndrome (SS) and other rheumatic diseases, are often accompanied by sensitivity to metals. Numerous investigations on metal sensitivity were evaluated in this review. A detailed metal exposure history was collected by different evaluation of studies. In all subjects, the main source of metal exposure was nickel, mercury, gold, palladium, titanium, and chromium. All of SLE (systemic lupus erythematosus), RA and SS patients appeared to have an increased frequency of metal delayed-type hypersensitivity (DTH) (Type IV allergy). As dental restorative materials release minor amounts of their metals (including mercury, gold, and nickel), many adults are commonly exposed to these metal ions by vapor or corrosion into saliva. Metal-related DTH in these patients will induce an inflammatory response. Such inflammations are important factors in CTD progress. It is hypothesized that metal-specific T cell reactivity can act as an etiological agent in the propagation and chronification of rheumatic inflammation. The key responses of metal delayed-type hypersensitivity in autoimmunity are precipitating as an appealing challenge for further investigations.

ABO blood groups and rheumatic diseases

Objective

Various genetic and environmental risk factors have been shown to be associated with the incidence of rheumatic diseases. However, the pathogenesis of rheumatic diseases poorly understood. Several studies have shown associations of ABO blood groups with various diseases. Our study aimed to determine whether there is an association between the types of rheumatic diseases and ABO and Rh blood groups.

Material and Methods

The study included the patients, followed up at the Immunology-Rheumatology clinic between January 2016 and December 2016 for diagnosis of rheumatic disease, who had an ABO Rh blood data. Age, gender, type of rheumatic disease, ABO Rh blood groups were recorded.

Results

When 823 patients were assessed for blood types, 42.5% patients had A type, 33.2% had O type, 15.4% had B type, and 8.9% had AB type. There was significant difference in the distribution of blood types in rheumatic diseases. While SpA, vasculitis, UCTD, Behçet's and RA were more common in the patients with A blood type; FMF, SLE, SSc and SjS were more common in the patients with O blood type. In addition, the blood type where all the diseases are observed the least commonly was AB. There was significant difference in the distribution of Rh factor in rheumatic diseases. 92.2% patients were Rh positive and 7.8% patients were Rh negative.

Conclusion

In our study, we thought that the higher incidence of different rheumatic diseases in different blood types was associated with different genetic predisposition.

The Role of High-Mobility Group Box-1 and Its Crosstalk with Microbiome in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, definitely disabling, and potentially severe autoimmune disease. Although an increasing number of patients are affected, a key treatment for all patients has not been discovered. High-mobility group box-1 (HMGB1) is a nuclear protein passively and actively released by almost all cell types after several stimuli. HMGB1 is involved in RA pathogenesis, but a convincing explanation about its role and possible modulation in RA is still lacking. Microbiome and its homeostasis are altered in patients with RA, and the microbiota restoration has been proposed to patients with RA. The purpose of the present review is to analyze the available evidences regarding HMGB1 and microbiome roles in RA and the possible implications of the crosstalk between the nuclear protein and microbiome in understanding and possibly treating patients affected by this harmful condition.

Correlation of PON1 polymorphisms with ankylosing spondylitis susceptibility: A case-control study in Chinese Han population

Paraoxonase 1 (PON1) modulates the oxidative stress and inflammatory response, thus, it might relate to the risk of ankylosing spondylitis (AS). The aim of present study was to discover the correlation of PON1 polymorphisms (rs662 and rs854560) with PON1 activity and AS risk.Around 128 AS patients and 146 healthy controls were recruited in this case-control study. PON1 polymorphisms were genotyped by direct sequencing. Serum PON1 activity was detected and compared by nonparametric test in different genotypes of PON1 polymorphisms. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to present the relative risk for AS.GG genotype and G allele of rs662 polymorphism were closely correlated with enhanced AS risk (P = .034, OR = 2.318, 95%CI = 1.051-5.113; P = .032, OR = 1.485, 95%CI = 1.033-2.135). PON1 activity was obviously higher in controls than that in AS patients. Significant difference of PON1 activity has been discovered in the different rs662 genotypes (P < .01). rs662 GG genotype carriers had the lowest PON1 activity, followed by AG carriers and the AA carriers. Besides, no significant relationship existed between rs854560 genotypes and AS risk.PON1 rs662 polymorphism is significantly correlated with increased AS risk via inhibiting PON1 activity.

The role of gut microbiota in the pathogenesis of rheumatic diseases

Rheumatic diseases refer to many diseases with a loss of immune self-tolerance, leading to a chronic inflammation, degeneration, or metabolic derangement in multiple organs or tissues. The cause of rheumatic diseases remains to be elucidated, though both environmental and genetic factors are required for the development of rheumatic diseases. Over the past decades, emerging studies suggested that alteration of intestinal microbiota, known as gut dysbiosis, contributed to the occurrence or development of a range of rheumatic diseases, including rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, systemic sclerosis, and Sjogren's syndrome, through profoundly affecting the balance between pro- and anti-inflammatory immune responses. In this article, we discussed the role of gut microbiota in the pathogenesis of rheumatic diseases based on a large number of experimental and clinical materials, thereby providing a new insight for microbiota-targeted therapies to prevent or cure rheumatic diseases.

Effects of HLA-DRB1 alleles on susceptibility and clinical manifestations in Japanese patients with adult onset Still's disease

Background

HLA-DRB1 alleles are major determinants of genetic predisposition to rheumatic diseases. We assessed whether DRB1 alleles are associated with susceptibility to particular clinical features of adult onset Still’s disease (AOSD) in a Japanese population by determining the DRB1 allele distributions.

Methods

DRB1 genotyping of 96 patients with AOSD and 1,026 healthy controls was performed. Genomic DNA samples from the AOSD patients were also genotyped for MEFV exons 1, 2, 3, and 10 by direct sequencing.

Results

In Japanese patients with AOSD, we observed a predisposing association of DRB1*15:01 (p = 8.60 × 10⁻⁶, corrected p (Pc) = 0.0002, odds ratio (OR) = 3.04, 95% confidence interval (95% CI) = 1.91–4.84) and DR5 serological group (p = 0.0006, OR = 2.39, 95% CI = 1.49–3.83) and a protective association of DRB1*09:01 (p = 0.0004, Pc = 0.0110, OR = 0.34, 95% CI = 0.18–0.66) with AOSD, and amino acid residues 86 and 98 of the DRβ chain were protectively associated with AOSD. MEFV variants were identified in 49 patients with AOSD (56.3%). The predisposing effect of DR5 was confirmed only in patients with AOSD who had MEFV variants and not in those without MEFV variants. Additionally, DR5 in patients with AOSD are associated with macrophage activation syndrome (MAS) and steroid pulse therapy.

Conclusion

The DRB1*15:01 and DR5 are both associated with AOSD susceptibility in Japanese subjects. A protective association between the DRB1*09:01 allele and AOSD was also observed in these patients. Our data also highlight the effects of DRB1 alleles in susceptibility to AOSD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1406-x) contains supplementary material, which is available to authorized users.

The role of dietary sodium intake on the modulation of T helper 17 cells and regulatory T cells in patients with rheumatoid arthritis and systemic lupus erythematosus

We aimed at investigating whether the frequency and function of T helper 17 (Th17) and regulatory T cells (Treg) are affected by a restriction of dietary sodium intake in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). We enrolled RA and SLE patients not receiving drugs known to increase urinary sodium excretion. Patients underwent a dietary regimen starting with a restricted daily sodium intake followed by a normal-sodium daily intake. The timepoints were identified at baseline (T0), after 3 weeks of low-sodium dietary regimen (T3), after 2 weeks of normal-sodium dietary regimen (T5). On these visits, we measured the 24-hour urinary sodium excretion, the frequency and function of Th17 and Treg cells in the peripheral blood, the serum levels of cytokines. Analysis of urinary sodium excretion confirmed adherence to the dietary regimen. In RA patients, a trend toward a reduction in the frequencies of Th17 cells over the low-sodium dietary regimen followed by an increase at T5 was observed, while Treg cells exhibited the opposite trend. SLE patients showed a progressive reduction in the percentage of Th17 cells that reached a significance at T5 compared to T0 (p = 0.01) and an increase in the percentage of Treg cells following the low-sodium dietary regimen at both T1 and T3 compared to T0 (p = 0.04 and p = 0.02, respectively). No significant apoptosis or proliferation modulation was found. In RA patients, we found a reduction at T5 compared to T0 in serum levels of both TGFβ (p = 0.0016) and IL-9 (p = 0.0007); serum IL-9 levels were also reduced in SLE patients at T5 with respect to T0 (p = 0.03). This is the first study investigating the effects of dietary sodium intake on adaptive immunity. Based on the results, we hypothesize that a restricted sodium dietary intake may dampen the inflammatory response in RA and SLE patients.

The genetic association between polymorphisms in lymphotoxin-α gene and ankylosing spondylitis susceptibility in Chinese group: A case-control study

The study was designed to reveal the genetic relationship of lymphotoxin-α (LTA) polymorphisms with risk of ankylosing spondylitis (AS) in Chinese Han population.LTA polymorphisms were genotyped by polymerase chain reaction-direct sequencing (PCR-DS) in 138 AS patients and 141 healthy controls. The genotype distribution in control group was checked the status of Hardy-Weinberg equilibrium (HWE). Odds ratio (OR) with 95% confidence interval (95%CI) calculated by χ test was used to show effects of LTA polymorphisms on AS risk. Logistic regressive analysis was used to calculate the adjusted OR values. Additionally, the linkage disequilibrium of LTA polymorphisms was examined by Haploview.G allele of rs909253 was significantly higher frequency in AS patients (P = .02), which was associated with the increased risk of AS (OR = 1.53, 95%CI = 1.07-2.18). The carriages of GG genotype in rs909253 showed a high risk of AS occurrence, compared with AA genotype carriers (OR = 2.46, 95%CI = 1.13-5.35). Multivariate analysis demonstrated that the G allele (OR = 1.52, 95%CI = 1.05-2.15) and GG genotype (OR = 2.36, 95%CI = 1.06-5.24) of rs909253 were still positively associated with AS susceptibility. However, there was no significant association between AS risk and rs2239704 or rs2229094.LTA rs909253 polymorphism contributes to the occurrence of AS.

Association of novel polymorphisms in TMEM39A gene with systemic lupus erythematosus in a Chinese Han population

BACKGROUND

This study aimed to assess the association between 14 single nucleotide polymorphisms (SNPs) in six genes (IRF8, TMEM39A, IKZF3, ORMDL3, GSDMB, and ZPBP2) and systemic lupus erythematosus (SLE) in a Chinese Han population sample.

METHODS

We carried out a case-control study of 415 patients with SLE and 470 healthy controls without autoimmune disease or cancer. DNA for genetic analysis was isolated from the blood of all subjects using standard phenol-chloroform method. TagSNPs were identified using genotype data from the panel (Han Chinese in Beijing) of the HapMap Project and were selected using the Haploview program. Genotyping assay was conducted using the Sequenom MassARRAY iPLEX Gold platform. The frequencies of the alleles and genotypes were calculated and analyzed. Association studies and haplotype analysis were also performed.

RESULTS

The genotypic frequencies of rs12493175 and rs13062955 were significantly different between the SLE patients and the healthy controls. Compared with the common homozygous genotype, the CT and CT + TT genotypes in rs12493175 and the AC and AC + AA genotypes in rs13062955 was observed to significantly reduce the risk of SLE. The haplotype analysis of TMEM39A polymorphisms showed that the CGTA haplotype frequency was significantly low in the SLE patients.

CONCLUSION

Our findings identified three novel associations in SNPs located in the TMEM39A gene associated with SLE susceptibility in a Chinese Han population.

Interactions Between Genetics, Lifestyle, and Environmental Factors for Healthcare

The occurrence and progression of diseases are strongly associated with a combination of genetic, lifestyle, and environmental factors. Understanding the interplay between genetic and nongenetic components provides deep insights into disease pathogenesis and promotes personalized strategies for people healthcare. Recently, the paradigm of systems medicine, which integrates biomedical data and knowledge at multidimensional levels, is considered to be an optimal way for disease management and clinical decision-making in the era of precision medicine. In this chapter, epigenetic-mediated genetics-lifestyle-environment interactions within specific diseases and different ethnic groups are systematically discussed, and data sources, computational models, and translational platforms for systems medicine research are sequentially presented. Moreover, feasible suggestions on precision healthcare and healthy longevity are kindly proposed based on the comprehensive review of current studies.

A Possible Role of Intestinal Microbiota in the Pathogenesis of Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the sacroiliac joints and the spine, for which the pathogenesis is thought to be a result of the combination of host genetic factors and environmental triggers. However, the precise factors that determine one’s susceptibility to AS remain to be unraveled. With 100 trillion bacteria residing in the mammalian gut having established a symbiotic relation with their host influencing many aspects of host metabolism, physiology, and immunity, a growing body of evidence suggests that intestinal microbiota may play an important role in AS. Several mechanisms have been suggested to explain the potential role of the microbiome in the etiology of AS, such as alterations of intestinal permeability, stimulation of immune responses, and molecular mimicry. In this review, the existing evidence for the involvement of the microbiome in AS pathogenesis was discussed and the potential of intestinal microbiome-targeting strategies in the prevention and treatment of AS was evaluated.

Protective effect of taraxasterol against rheumatoid arthritis by the modulation of inflammatory responses in mice

Taraxasterol is an effective component of dandelion that has anti-inflammatory effects in vivo and in vitro. The present study was performed to explore whether taraxasterol exhibits a protective effect against rheumatoid arthritis through the modulation of inflammatory responses in mice. Eight-week-old CCR9-deficient mice were injected with a collagen II monoclonal antibody cocktail to create a rheumatoid arthritis model. In the experimental group, arthritic model mice were treated with 10 mg/kg taraxasterol once per day for 5 days. Treatment with taraxasterol significantly increased the pain thresholds and reduced the clinical arthritic scores of the mice in the experimental group compared with those of the model group. Furthermore, treatment with taraxasterol significantly suppressed tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and nuclear factor-κB protein expression levels compared with those in the rheumatoid arthritis model mice. Taraxasterol treatment also significantly reduced nitric oxide, prostaglandin E2 and cyclooxygenase-2 levels compared with those in the rheumatoid arthritis model group. These observations indicate that the protective effect of taraxasterol against rheumatoid arthritis is mediated via the modulation of inflammatory responses in mice.