Susceptibility to ankylosing spondylitis: no evidence for the involvement of transforming growth factor beta 1 (TGFB1) gene polymorphisms

Investigating the causal relationship between ankylosing spondylitis and osteoporosis in the European population: a bidirectional Mendelian randomization study

Background

Ankylosing Spondylitis (AS) is an inflammatory condition affecting the spine, which may lead to complications such as osteoporosis (OP). Many observational studies have demonstrated a close relationship with strong evidence between OP and AS. The combination of AS and OP is already an indisputable fact, but the exact mechanism of AS complicated with OP is unclear. To better prevent and treat OP in patients with AS, it is necessary to understand the specific mechanism of OP in these patients. In addition, there is a study showing that OP is a risk factor for AS, but the causal relationship between them is not yet clear. Therefore, we conducted a bidirectional Mendelian randomization (MR) analysis to determine whether there is a direct causal effect between AS and OP and to investigate the co-inherited genetic information between the two.

Methods

Bone mineral density (BMD) was used as a phenotype for OP. The AS dataset was taken from the IGAS consortium and included people of European ancestry (9,069 cases and 13,578 controls). BMD datasets were obtained from the GEFOS consortium, a large GWAS meta-analysis study, and the UK Biobank and were categorized based on site (total body (TB): 56,284 cases; lumbar spine (LS): 28,498 cases; femoral neck (FN): 32,735 cases; forearm (FA): 8,143 cases; and heel: 265,627 cases) and age (0-15: 11,807 cases; 15-30: 4,180 cases; 30-45: 10,062 cases; 45-60: 18,062 cases; and over 60: 22,504 cases).To obtain the casual estimates, the inverse variant weighted (IVW) method was mainly used due to its good statistical power and robustness. The presence of heterogeneity was evaluated using Cochran's Q test. Pleiotropy was assessed utilizing MR-Egger regression and MR-pleiotropy residual sum and outlier (MR-PRESSO).

Results

Generally, there were no significant causal associations between genetically predicted AS and decreased BMD levels. The results of MR-Egger regression, Weighted Median, and Weighted Mode methods were consistent with those of the IVW method. However, there was a sign of a connection between genetically elevated BMD levels and a decreased risk of AS (Heel-BMD: OR = 0.879, 95% CI: 0.795-0.971, P = 0.012; Total-BMD: OR = 0.948, 95% CI: 0.907-0.990, P = 0.017; LS-BMD: OR = 0.919, 95% CI: 0.861-0.980, P = 0.010). The results were confirmed to be reliable by sensitivity analysis.

Conclusion

This MR study found that the causal association between genetic liability to AS and the risk of OP or lower BMD in the European population was not evident, which highlights the second effect (e.g., mechanical reasons such as limited movement) of AS on OP. However, genetically predicted decreased BMD/OP is a risk factor for AS with a causal relationship, implying that patients with OP should be aware of the potential risk of developing AS. Moreover, OP and AS share similar pathogenesis and pathways.

The association of transforming growth factor beta 1 gene polymorphisms with arthritis: a systematic review and meta-analysis

The objective of this study was to explore the association between transformation growth factor beta 1 (TGF-β1) gene polymorphisms and different types of arthritis. PubMed, Medline, Web of Science, Cochrane Library, Biosis and four Chinese databases: China Biology Medicine, China National Knowledge Infrastructure, Wanfang and CQVIP, were searched. Studies that analyzed the association of the TGF-β1 polymorphisms with different types of arthritis were included. OR, 95% confidence interval and P value were calculated in three models including allele, dominant and recessive models, using D + L method. The Newcastle-Ottawa Scale was used to assess the quality of the included studies. TGF-β1 869T > C polymorphism was significantly associated with rheumatoid arthritis (RA) in allele and recessive models, but not in dominant model (allele model T vs. C: OR = 1.30, 95% CI = 1.13-1.49, P < 0.001; recessive model CC vs. TT + TC: OR = 0.57, 95% CI = 0.43-0.76, P < 0.001; dominant model TT vs. TC + CC: OR = 1.20, 95% CI = 0.99-1.45, P = 0.063). Additionally, allele and recessive models showed that TGF-β1 -509C > T was significantly correlated with RA susceptibility, while dominant model revealed nonsignificant correlation (allele model: C vs. T: OR = 1.51; 95% CI = 1.00-2.28; P = 0.049; recessive model: TT vs. CC + TC: OR = 0.52, 95% CI = 0.37-0.72, P = 0.000; dominant model: CC vs. TT + TC: OR = 1.48; 95% CI = 0.79-2.76; P = 0.223). However, no significant association was found between TGF-β1 polymorphisms and ankylosing spondylitis (AS) or osteoarthritis (OA) risk. This study demonstrated that 869T > C, -509 C > T polymorphisms of TGF-β1 gene were associated with increased susceptibility of RA, while polymorphisms of TGF-β1 gene were not associated with OA and AS. These findings suggest that studying TGF-β1 genotype may be useful in the prevention and management of RA. However, more studies are needed to evaluate the association of TGF-β1 gene polymorphisms with the susceptibility of OA and AS.

Association between gene polymorphisms of TGF-β and Smad3 and susceptibility to arthritis: a meta-analysis

OBJECTIVES

This meta-analysis was performed to investigate the associations between single-nucleotide polymorphisms (SNPs) in the TGF- β and Smad3 genes and arthritis.

METHODS

A meta-analysis was performed in STATA 14.0, with publication bias and meta-regression analysis. All types of arthritis were included, and subgroup analyses were performed to interpret variations among different types of arthritis.

RESULTS

Twenty-two qualified studieswere selected to analyze the pooled accuracy, and 4 SNP sites were involved. The analysis of the TGFB1 SNP rs1800470 showed an association with arthritis in allelic (P = 0.011), homozygous (P = 0.034) and recessive (P = 0.021) genetic models. The analysis of the TGFB1 SNP rs1800471 demonstrated a close association with rheumatoid arthritis (RA) in homozygous (P = 0.000, 95%) and recessive (P = 0.008) models. The analysis of the SMAD3 SNP rs12901499 revealed a close association with osteoarthritis (OA) in the allelic (P = 0.001) model.

CONCLUSION

This research showed that genetic variants of the TGF-β pathway impact arthritis. The polymorphisms rs1800470, rs1800471 and rs12901499 were correlated with a higher prevalence of arthritis.

H19 Increases IL-17A/IL-23 Releases via Regulating VDR by Interacting with miR675-5p/miR22-5p in Ankylosing Spondylitis

Long non-coding RNA (lncRNA) H19 is associated with inflammatory diseases, but the molecular mechanism of H19 in the inflammatory process of ankylosing spondylitis (AS) is unclear. Here, we investigated the role of H19 and its downstream molecules in the inflammation of AS by microarray analysis, qRT-PCR, western blot, and dual-luciferase reporter assay. H19 small interfering RNA (siRNA) (Si-H19) and adenovirus (AD-H19) were used to decrease and increase H19 expression, respectively. 42 annotated lncRNAs were identified, and H19 was overexpressed. H19, vitamin D receptor (VDR), and transforming growth factor β (TGF-β) can bind to microRNA22-5p (miR22-5p) and miR675-5p. Si-H19 significantly downregulated miR22-5p and upregulated miR675-5p expression; Si-H19 decreased the protein and mRNA expression of VDR and decreased the cytokine and mRNA levels of interleukin-17A (IL-17A) and IL-23. These results were verified by AD-H19. In addition, miR22-5p and miR675-5p inhibitors increased the protein and mRNA expression of VDR and increased the cytokine and mRNA levels of IL-17A and IL-23. These results were also confirmed by miRNA mimics. Furthermore, H19 directly interfered with miR22-5p and miR675-5p expression, whereas the two miRNAs directly inhibited VDR expression. Overall, the H19-miR22-5p/miR675-5p-VDR-IL-17A/IL-23 signaling pathways have important roles in the pathogenesis of AS.

Systems Pharmacology Dissecting Holistic Medicine for Treatment of Complex Diseases: An Example Using Cardiocerebrovascular Diseases Treated by TCM

Holistic medicine is an interdisciplinary field of study that integrates all types of biological information (protein, small molecules, tissues, organs, external environmental signals, etc.) to lead to predictive and actionable models for health care and disease treatment. Despite the global and integrative character of this discipline, a comprehensive picture of holistic medicine for the treatment of complex diseases is still lacking. In this study, we develop a novel systems pharmacology approach to dissect holistic medicine in treating cardiocerebrovascular diseases (CCDs) by TCM (traditional Chinese medicine). Firstly, by applying the TCM active ingredients screened out by a systems-ADME process, we explored and experimentalized the signed drug-target interactions for revealing the pharmacological actions of drugs at a molecule level. Then, at a/an tissue/organ level, the drug therapeutic mechanisms were further investigated by a target-organ location method. Finally, a translational integrating pathway approach was applied to extract the diseases-therapeutic modules for understanding the complex disease and its therapy at systems level. For the first time, the feature of the drug-target-pathway-organ-cooperations for treatment of multiple organ diseases in holistic medicine was revealed, facilitating the development of novel treatment paradigm for complex diseases in the future.

Susceptibility to ankylosing spondylitis: evidence for the role of ERAP1, TGFb1 and TLR9 gene polymorphisms

Genetic factors are thought to be crucial in the pathogenesis of ankylosing spondylitis (AS). Recent studies have reported that ERAP1, TGBβ1 and TLRs genes are likely to have association with AS in different populations. We carried out this study to determine whether single-nucleotide polymorphisms covering the three genes are associated with AS in a Chinese Han population. Genomic DNA was isolated from the peripheral blood of 328 patients with AS and 627 healthy blood donors from Jinan region as a case-control study. The diagnosis of AS was made according to the modified New York criteria. The ERAP1 rs27044, TGBβ1 rs1800470 and TLR9 rs55704465 were genotyped by a polymerase chain reaction--restriction fragment length polymorphism method. Strong association with AS was observed for marker rs27044, but no significant differences were observed between AS patients and controls in the frequencies of the carriership of the alleles rs55704465 and rs1800470. Our data thus indicate that ERAP1 likely constitutes one of AS-associated loci of susceptibility after HLA in Chinese Han population. On the contrary, TGFB1 and TLR9 variations show no association with the susceptibility of AS.

The genetic background of ankylosing spondylitis

It has long been known that the major histocompatibility complex (MHC) is essentially involved in genetic susceptibility to ankylosing spondylitis (AS). The HLA-B27 antigen has been accounted for 20 to 50% of the total genetic risk for this disease. However, susceptibility to AS cannot be fully explained by associations with the MHC. Recent studies including linkage analyses as well as candidate gene and, most recently, genome-wide association studies indicate significant associations of the interleukin-1 gene cluster, interleukin-23 receptor and ARTS1 genes as well as other possible loci with AS. In the murine model of proteoglycan-induced spondylitis, two susceptibility loci termed Pgis1 and Pgis2 were identified. Thus, AS is not a single-gene disease and the involvement of multiple non-MHC genes may account for the individual as well as geographical differences seen in AS.

The contribution of genes outside the major histocompatibility complex to susceptibility to ankylosing spondylitis

PURPOSE OF REVIEW

Recent data have presented several new nonmajor histocompatibility complex genes in predisposition to ankylosing spondylitis, which will be summarized here.

RECENT FINDINGS

A retrospective meta-analysis of three previous whole genome linkage scans confirmed a strong linkage at chromosome 16q and moderate linkage at sites on chromosomes 3, 10, and 19q, and a meta-analysis of studies of the interleukin-1 (IL-1) region genes in ankylosing spondylitis suggested the susceptibility to be conferred by the IL-1A gene. More recently, the use of genotyping chips, derived from the International Hapmap resource, which provides an extensive genomic coverage of large disease cohorts, have made it possible to conduct successful genome-wide association studies. One such study has led to the identification and validation of two new genes, IL23R and ARTS1, in ankylosing spondylitis pathogenesis.

SUMMARY

A tremendous amount of progress has been made with respect to understanding the genetic basis of ankylosing spondylitis. The recent identification of two new genes, ARTS1 and IL23R, and confirmation of IL-1A association further substantiate that ankylosing spondylitis is determined to a large extent by genes outside the major histocompatibility complex.

TGFB1 gene polymorphisms: their relevance in the susceptibility to Helicobacter pylori-related diseases

Recent studies have revealed elevated expression of transforming growth factor beta1 (TGF-beta1) in gastric mucosa of patients with gastric cancer (GC) and those undergoing ulcer repair. As production of TGF-beta1 is genetically regulated, we aimed to assess whether functional polymorphisms of the TGFB1 gene are involved in susceptibility to and clinical characteristics of Helicobacter pylori-related diseases. DNA from 142 unrelated Spanish patients with GC, 200 with peptic ulcer and 342 healthy controls was typed for the MspA1I T+869C, and the Sau96I G+915C polymorphisms of the TGFB1 gene using polymerase chain reaction and RFLP analysis. H. pylori infection and CagA/VacA antibody status were determined by Western blot in patients and controls. H. pylori infection (odds ratio (OR): 11.44; 95% confidence interval (CI): 4.45-29.42; P<0.001) and non-steroidal anti-inflammatory drugs (OR: 5.07; 95% CI: 2.53-10.16; P<0.001) were identified as independent risks factors for duodenal ulcer (DU), whereas the TGFB1+869(*)C/C genotype was associated with reduced risk of developing the disease (OR: 0.32; 95% CI=0.15-0.68; P=0.003). Our results show that the TGFB1 T+869C gene polymorphism is involved in the susceptibility to DU and provide further evidence that host genetic factors play a key role in the pathogenesis of H. pylori-related diseases.

The genetic basis of ankylosing spondylitis

PURPOSE OF REVIEW

Genetic factors provide over 90% of the overall susceptibility to ankylosing spondylitis, with about half of the genetic contribution attributed to HLA-B27 and other major histocompatibility complex genes. Recent studies have focused on non-major histocompatibility complex genes. This review is aimed at summarizing the status of major histocompatibility complex and non-major histocompatibility complex genes in ankylosing spondylitis susceptibility, and suggests areas for future studies.

RECENT FINDINGS

A recent meta-analysis of published scans of ankylosing spondylitis susceptibility has confirmed sites on chromosomes 3q, 6p (the major histocompatibility complex), 10q, 16q and 19q in ankylosing spondylitis susceptibility. Non-major histocompatibility complex candidate gene analyses have confirmed a role for the IL-1 gene complex. The search for other non-major histocompatibility complex candidate genes, however, has been complicated by inadequate power in most previous studies. Innovations in genetic methodologies will allow thorough genome wide linkage disequilibrium mapping studies in large cohorts of patients that will result in the dissection of the genetic susceptibility to ankylosing spondylitis.

SUMMARY

Nearly half of the susceptibility to ankylosing spondylitis is provided by major histocompatibility complex genes. Non-major histocompatibility complex genes, most notably the IL-1 gene complex, have been identified and novel technologies promise that a more thorough examination of the rest of the genome will soon elucidate the genetic basis of this disease.