The Role of Macrophages in Connective Tissue Disease-Associated Interstitial Lung Disease: Focusing on Molecular Mechanisms and Potential Treatment Strategies

Connective tissue disease-associated interstitial lung disease (CTD-ILD) is a severe manifestation of CTD that leads to significant morbidity and mortality. Clinically, ILD can occur in diverse CTDs. Pathologically, CTD-ILD is characterized by various histologic patterns, such as nonspecific interstitial pneumonia, organizing pneumonia, and usual interstitial pneumonia. Abnormal immune system responses have traditionally been instrumental in its pathophysiology, and various changes in immune cells have been described, especially in macrophages. This article first briefly overviews the epidemiology, clinical characteristics, impacts, and histopathologic changes associated with CTD-ILD. Next, it summarizes the roles of various signaling pathways in macrophages or products of macrophages in ILD, helped by insights gained from animal models. In the following sections, this review returns to studies of macrophages in CTD-ILD in humans for an overall picture of the current understanding. Finally, we direct attention to potential therapies targeting macrophages in CTD-ILD in investigation or in clinical trials, as well as the future directions regarding macrophages in the context of CTD-ILD. Although the field of macrophages in CTD-ILD is still in its infancy, several lines of evidence suggest the potential of this area.

Methylation of TET2 Promoter Is Associated with Global Hypomethylation and Hypohydroxymethylation in Peripheral Blood Mononuclear Cells of Systemic Lupus Erythematosus Patients

(1) Background: It is widely accepted that aberrant methylation patterns contribute to the development of systemic lupus erythematosus (SLE). Ten-eleven translocation (TET) methylcytosine dioxygenase is an essential enzyme of which there are three members, TET1, 2, and 3, involved in hydroxymethylation, a newly uncovered mechanism of active DNA methylation. The epigenomes of gene transcription are regulated by 5-hydroxymethylcytocine (5-hmC) and TETs, leading to dysregulation of the immune system in SLE. The purpose of this study was to investigate the global hydroxymethylation status in SLE peripheral blood mononuclear cells (PBMCs) and to explore the role of TETs in changing the patterns of methylation. (2) Methods: We collected PBMCs from 101 SLE patients and 100 healthy donors. TaqMan real-time polymerase chain-reaction assay was performed for the detection of 5-methylcytosine (5-mC), 5-hmC, and TET2 mRNA expression and single-nucleotide polymorphism genotyping. The methylation rates in different CpG sites of TET2 promoters were examined using next-generation sequencing-based deep bisulfite sequencing. Putative transcription factors were investigated using the UCSC Genome Browser on the Human Dec. 2013 (GRCh38/hg38) Assembly. (3) Results: 5-mC and 5-hmC were both decreased in SLE. The mRNA expression level of TET2 was notably high and found to be correlated with the levels of immunologic biomarkers that are indicative of SLE disease activity. The analysis of methylation rates in the TET2 promoter revealed that SLE patients had significantly higher and lower rates of methylation in TET2 105146072-154 and TET2 105146218-331, respectively. (4) Conclusions: TET2 may play an important role in 5-mC/5-hmC dynamics in the PBMCs of SLE patients. The epigenetic modification of TET2 promoters could contribute to the pathogenesis of SLE and the intensity of the immunologic reaction.

Genetic and epigenetic alterations of cyclic AMP response element modulator in rheumatoid arthritis

BACKGROUND

Genetic and epigenetic factors are strongly associated with the autoimmune disease rheumatoid arthritis (RA). Cyclic AMP response element modulator (CREM), a gene related to immune system regulation, has been implicated in various immune-mediated inflammatory processes, although it remains unknown whether CREM is involved in RA.

METHODS

This study enrolled 278 RA patients and 262 controls. Three variants [rs12765063, rs17499247, rs1213386] were identified through linkage disequilibrium and expression quantitative trait locus analysis, and CREM transcript abundance was determined by quantitative real-time polymerase chain reaction. The identified variants were genotyped using the TaqMan Allelic Discrimination assay, and CREM promoter methylation was assessed by bisulphite sequencing. Differences between groups and correlations between variables were assessed with Student's t-tests and Pearson's correlation coefficients. Associations between phenotypes and genotypes were evaluated with logistic regression.

RESULTS

Rheumatoid arthritis patients exhibited increased CREM expression (p < .0001), which was decreased by methotrexate (p = .0223) and biologics (p = .0001), but could not be attributed to CREM variants. Interestingly, rs17499247 displayed a significant association with serositis (p = .0377), and rs1213386 increased the risk of lymphadenopathy (p = .0398). Furthermore, seven CpG sites showed decreased methylation in RA (p = .0477~ p < .0001).

CONCLUSIONS

Collectively, our results indicate that CREM hypomethylation and CREM upregulation occur in RA and that CREM variants are involved in the development of serositis and lymphadenopathy in RA. This study highlights the novel roles of CREM in RA pathophysiology.

Association of F11R polymorphisms and gene expression with primary Sjögren's syndrome patients

AIMS

F11R gene encodes junctional adhesion molecule-A protein (JAM-A), which is expressed in various types of cells and is involved in leukocyte extravasation during inflammation. Sjögren's syndrome (SS) is a chronic systemic inflammatory disease that involves lymphocytes invasion of exocrine glands. F11R has been studied in autoimmune diseases, but any association between F11R and SS has not yet been investigated. Therefore, experiments were undertaken to examine the relationships among F11R gene polymorphism, messenger RNA (mRNA) expression and SS patients.

METHODS

Three hundred and twenty-nine patients with SS, and 223 healthy controls were enrolled in their recruitment from the Kaohsiung Medical University Hospital. Genomic DNA was extracted from peripheral blood mononuclear cells and gene polymorphisms were genotyped by TaqMan real-time polymerase chain reaction (PCR). F11R mRNA expression was quantitated by quantitative real-time PCR with TaqMan Gene Expression Assay.

RESULTS

Our study showed the genotype -688A/C (rs6695707) was not found in relation to SS patients. The odds ratio of -436A/G (rs12567886) genotype was notably associated with less susceptibility of SS in human leukocyte antigen (HLA)-DR2 negative and HLA-DR3 negative individuals. F11R mRNA expression was lower in SS patients than in the cells of healthy controls.

CONCLUSION

The result indicated that G allele of -436A/G genotype has the potential protective effect against SS disease condition. F11R mRNA was expressed significantly lower in SS patients.

Dual Role of Chondrocytes in Rheumatoid Arthritis: The Chicken and the Egg

Rheumatoid arthritis (RA) is one of the inflammatory joint diseases that display features of articular cartilage destruction. The underlying disturbance results from immune dysregulation that directly and indirectly influence chondrocyte physiology. In the last years, significant evidence inferred from studies in vitro and in the animal model offered a more holistic vision of chondrocytes in RA. Chondrocytes, despite being one of injured cells in RA, also undergo molecular alterations to actively participate in inflammation and matrix destruction in the human rheumatoid joint. This review covers current knowledge about the specific cellular and biochemical mechanisms that account for the chondrocyte signatures of RA and its potential applications for diagnosis and prognosis in RA.

Genetic and epigenetic alteration of the programmed cell death 1 in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease where both genetics and epigenetics are contributing factors. In order to discover genetic and epigenetic associations with RA and its phenotypes, we analysed RNA expression, DNA variations and DNA methylation of programmed cell death 1 (PDCD1) in a cohort of RA patients and healthy controls.

METHODS

RA patients (n = 206) and healthy controls (n = 234) were included for analysis of PDCD1 expression, PDCD1 polymorphisms and PDCD1 methylation. Differences in continuous variables between groups were compared by applying t tests. Associations between phenotypes and genotypes were evaluated with contingency tables. Sensitivity analyses were conducted to confirm the robustness of results, considering potential confounding factors and different treatment response definitions. Odds ratio (OR) and 95% confidence interval (95% CI) were calculated.

RESULTS

Higher expression of PDCD1 was found in RA compared to controls (P < 0.001), with similar PDCD1 polymorphisms in RA and controls. rs36084323 decreased inadequate response to conventional synthetic disease-modifying antirheumatic drugs (OR = 0.37, 95% CI = 0.19-0.72, P = 0.003), and rs41386349 increased rheumatoid factor seropositivity (OR = 11.89, 95% CI = 1.57-89.87, P = 0.003). Sensitivity analysis adjusting for further potential confounders and using different treatment response definition indicated similar results. Additionally, DNA methylation change at regulatory region of PDCD1 was detected in RA (P = 0.036).

CONCLUSION

Altogether, this was the first study to suggest genetic and epigenetic changes of PDCD1 in RA subsets and RA. Independent prospective cohorts are awaited to address the implications of these genetic and epigenetic changes in disease pathogenesis and phenotypes of RA.

Differential Expression Profiles of the Transcriptome and miRNA Interactome in Synovial Fibroblasts of Rheumatoid Arthritis Revealed by Next Generation Sequencing

Using next-generation sequencing to decipher the molecular mechanisms underlying aberrant rheumatoid arthritis synovial fibroblasts (RASF) activation, we performed transcriptome-wide RNA-seq and small RNA-seq on synovial fibroblasts from rheumatoid arthritis (RA) subject and normal donor. Differential expression of mRNA and miRNA was integrated with interaction analysis, functional annotation, regulatory network mapping and experimentally verified miRNA–target interaction data, further validated with microarray expression profiles. In this study, 3049 upregulated mRNA and 3552 downregulated mRNA, together with 50 upregulated miRNA and 35 downregulated miRNA in RASF were identified. Interaction analysis highlighted contribution of miRNA to altered transcriptome. Functional annotation revealed metabolic deregulation and oncogenic signatures of RASF. Regulatory network mapping identified downregulated FOXO1 as master transcription factor resulting in altered transcriptome of RASF. Differential expression in three miRNA and corresponding targets (hsa-miR-31-5p:WASF3, hsa-miR-132-3p:RB1, hsa-miR-29c-3p:COL1A1) were also validated. The interactions of these three miRNA–target genes were experimentally validated with past literature. Our transcriptomic and miRNA interactomic investigation identified gene signatures associated with RASF and revealed the involvement of transcription factors and miRNA in an altered transcriptome. These findings help facilitate our understanding of RA with the hope of serving as a springboard for further discoveries relating to the disease.

GADD45a and GADD45b Genes in Rheumatoid Arthritis and Systemic Lupus Erythematosus Patients

Background: GADD45 genes are stress sensors in response to cellular stress response, activated signal pathways leading to the stimulation of inflammatory cytokines. This study is to examine the associations of GADD45a and GADD45b genes with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) patients. Methods: 230 patients of RA, 140 patients of SLE, and 191 healthy controls were enrolled. Genomic DNA was extracted from peripheral blood mononuclear cells and gene polymorphisms were genotyped by TaqMan assay. RNA expression was quantitated with real-time polymerase chain reaction. Results: The RNA expression of the GADD45b gene was significantly lower in RA patients than the control cases (p = 0.03). The odds ratio of GADD45a genotype -589 CC (rs581000) was significantly low (OR = 0.36, 95% CI, 0.15–0.87) in DR4-negative RA patients. The odds ratio of GADD45b genotype -712CT (rs3795024) in DR4-negative RA patients was 0.41 (95% CI, 0.18–0.95). In clinical manifestation, the odds ratio of GADD45b -712CT genotype with anti-RNP antibody was 4.14 (95% CI, 1.10–15.63) in SLE patients. GADD45a genotype -589GG+GC was associated with rheumatoid factor (RF) in SLE patients. Conclusions: Genotypes GADD45a -589CC and GADD45b -712CT were shown to be less susceptible to RA and related to the disease state in SLE patients.

Nebulizer versus Inhaler with Spacer for Beta-Agonist Treatment in Acute Bronchospastic Disease

Objectives

To compare the efficacy of nebulized wet aerosol with metered-dose inhaler with a spacer (MDIS) in the management of acute bronchospasm.

Methods

It was a retrospective study by reviewing the clinical records of patients with acute exacerbation (chief complaint of shortness of breath) of asthma or chronic obstructive pulmonary disease (COPD) presenting to the Accident and Emergency Department (AED) of Tuen Mun Hospital from 1st to 30th November 2002 and 2003 respectively. All patients received beta-agonist by nebulizer, in the year 2002 (pre-SARS period) while all patients received treatment by MDIS in the year 2003 (post-SARS period). Treatment outcome measures included admission rate, length of hospitalisation for those admitted and AED re-attendance within 7 days for those discharged from the AED.

Results

Altogether 821 patients were recruited in this retrospective study, 522 belonged to the nebulizer group and 299 were of the MDIS group. The two groups had similar demographic characteristics. Concerning the admission rate (47% in the nebulizer group and 41% in the MDIS group; p=0.089) and re-attendance rate (7% in the nebulizer group and 6% in the MDIS group; p=0.607), the differences were not statistically significant. For the length of hospital stay, it was shorter in the nebulizer group than the MDIS group (3.65±SD 1.88 days vs 4.10±SD 1.94 days; p=0.035). However, the admission rate in the adult subgroup (61% in the nebulizer group and 47% in the MDIS group; p=0.002) was shown to be statistically significant. In multivariate analysis, usage of nebulizer, increase in respiratory rate and age were associated with a higher admission rate. Increase in SpO2, absence of co-morbidity and asthma patients were associated with a lower admission rate. Increase in age, respiratory rate and usage of MDIS were associated with an increase in hospital stay. Asthma was associated with a decrease in AED re-attendance rate as compared to COPD.

Conclusions

This retrospective study showed that both nebulizer and MDIS were effective for beta-agonist therapy in acute bronchospasm in AED with respect to hospital admission rate and AED re-attendance rate, but the length of hospital stay was slightly prolonged when using MDIS.

Sex differential association of dermatomyositis with Sjögren syndrome

BACKGROUND

Although dermatomyositis and Sjögren syndrome share serologic autoantibodies and genetic polymorphisms, population data about the incidence of Sjögren syndrome in patients with dermatomyositis is unavailable. We performed a nationwide cohort study to explore the potential relation between dermatomyositis and Sjögren syndrome and, if an association exists, to elucidate whether it varies by sex.

METHODS

We identified all patients with newly diagnosed dermatomyositis from the Registry of Catastrophic Illness Database in Taiwan between Jan. 1, 1998, and Dec. 31, 2011. Each patient was matched to, at most, 5 control patients from the National Health Insurance Research Database by age, sex and entry date. Cox regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) of Sjögren syndrome after adjusting for age, sex, rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis.

RESULTS

A total of 1602 patients with dermatomyositis and 7981 control patients were enrolled in the study. There was a positive association of having Sjögren syndrome among patients with dermatomyositis after adjusting for age, sex, rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis (HR 2.67, 95% CI 2.01-3.54). The association was more pronounced in the male cohort (HR 2.69, 95% CI 1.19-6.09).

INTERPRETATION

We found a sex differential association of Sjögren syndrome among patients with dermatomyositis independent of age and concomitant autoimmune disease. Further studies are required to determine the clinical importance of this association for both outcomes and therapeutic options.

Increased Incidence of Amyotrophic Lateral Sclerosis in Polymyositis: A Nationwide Cohort Study

OBJECTIVE

Past studies have shown common pathologic characteristics and shared immunologic features between polymyositis (PM) and amyotrophic lateral sclerosis (ALS). To explore the potential relationship between the 2 diseases, we performed a nationwide cohort study.

METHODS

We identified all newly diagnosed patients with PM from Taiwan's Registry of Catastrophic Illness Database between January 1, 1998 and December 31, 2011. Each PM patient was matched to ≤5 control patients from the National Health Insurance Research Database by sex, age, and entry date. Cumulative incidence of ALS was calculated by the Kaplan-Meier method and compared using the log rank test. Cox hazard regression was used to calculate the hazard ratio of ALS.

RESULTS

A total of 1,778 PM patients and 8,124 control patients were enrolled. PM patients had a higher cumulative incidence of ALS (P < 0.001). There was a positive correlation in being diagnosed with ALS in patients previously diagnosed with PM when stratified by sex. Consistent trends were conserved across different age strata. The strength of this association remained statistically significant after adjusting for sex, age, and concomitant autoimmune diseases (hazard ratio 25.72 [95% confidence interval 2.95-224.58]; P = 0.003).

CONCLUSION

This study demonstrates that a diagnosis of PM increased the likelihood of a subsequent ALS diagnosis, independent of sex, age, and concomitant autoimmune diseases. Future studies are warranted to clarify the underlying biologic mechanisms and to translate them into clinical therapeutic options.

Increased Cumulative Incidence of Dermatomyositis in Ulcerative Colitis: a Nationwide Cohort Study

On a molecular level, two autoimmune diseases: ulcerative colitis (UC) and dermatomyositis share common genetic determinants. On a clinical level, case reports evidenced the co-occurrence of these two diseases. We therefore hypothesize that UC is potentially associated with increased cumulative incidence of dermatomyositis. The goals of this retrospective cohort study were to evaluate whether UC is associated with increased cumulative incidence of dermatomyositis independent of sex and age. For comparison, we also assessed the cumulative incidence of polymyositis in UC and control subjects. The study enrolled 3,133 UC subjects and 14,726 control subjects. The cumulative incidence of dermatomyositis was significantly higher in UC than that of control subjects (p = 0.026), but the cumulative incidence of polymyositis was comparable between UC and control subjects (p = 0.596). UC was independently associated with the increased incident dermatomyositis (hazard ratio: 6.19, 95% confidence interval = 1.77-21.59, p = 0.004) after adjusting for sex, age, and concomitant rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis. Similar trends of increased dermatomyositis in UC were observed when patients were stratified based on sex and age. In conclusion, our findings suggest that UC is probably associated with increased cumulative incidence of dermatomyositis, independent of sex, age, and concomitant autoimmune diseases.

Increased incidence of rheumatoid arthritis in multiple sclerosis: A nationwide cohort study

Past studies have shown inconsistent results on whether there is an association between multiple sclerosis (MS) and rheumatoid arthritis. To investigate the possible relationship between the 2 autoimmune diseases, we performed a nationwide cohort study utilizing the National Health Insurance Research Database and the Registry of Catastrophic Illness.A total of 1456 newly diagnosed patients with MS and 10,362 control patients were matched for age, sex, and initial diagnosis date. Patients with MS had a higher incidence of rheumatoid arthritis (age-adjusted standardized incidence ratio: 1.72; 95% confidence interval = 1.01-2.91). There was a positive correlation in being diagnosed with rheumatoid arthritis in patients previously diagnosed with MS when stratified by sex and age. The strength of this association remained statistically significant after adjusting for sex, age, and smoking history (hazard ratio: 1.78, 95% confidence interval = 1.24-2.56, P = 0.002).In conclusion, this study demonstrates that a diagnosis of MS increased the likelihood of a subsequent diagnosis of rheumatoid arthritis in patients, independent of sex, age, and smoking history.

Reduced incidence of Crohn's disease in systemic sclerosis: a nationwide population study

Background

To date, there has been no studies to evaluate the incidence of Crohn’s disease in systemic sclerosis patients. The goals of this study were to evaluate the incidence of Crohn’s disease and its relationship with sex and age in patients with systemic sclerosis.

Methods

We enrolled patients with systemic sclerosis and controls from Taiwan’s Registry of Catastrophic Illness Database and National Health Insurance Research Database. Every systemic sclerosis patient was matched to at most three controls by sex, age, month and year of initial diagnosis of systemic sclerosis. The standardized incidence ratio (SIR) of Crohn’s disease in systemic sclerosis patients, and 95 % confidence interval (95 % CI) were calculated. Cox hazard regression was used to calculate the hazard ratio (HR).

Results

The study enrolled 2,829 patients with systemic sclerosis and 8,257 controls. Male and female patients with systemic sclerosis both had lower rates of incident Crohn’s disease (SIR: 0.18, 95 % CI = 0.05–0.62; SIR: 0.10, 95 % CI = 0.05–0.21, respectively). The risk of incident Crohn’s disease in systemic sclerosis was still lower than in controls when we stratified the patients according to their ages. In Cox hazard regression, the hazard rates of Crohn’s disease were lower in systemic sclerosis patients after adjusting for genders and ages (HR: 0.12, 95 % CI = 0.06–0.21, p < 0.001).

Conclusions

Systemic sclerosis is associated with decreased incidence of, irrespective of sex and age of the patients.

Increased incidence of Sjogren's syndrome in systemic sclerosis: A nationwide population study

In the past, there were no studies to evaluate the incidence of Sjogren's syndrome and its relationship with sex and age in patients with systemic sclerosis. In this study, we enrolled 2217 patients with systemic sclerosis and 6485 controls from Taiwan's Registry of Catastrophic Illness database and National Health Insurance Research Database. Every patient with systemic sclerosis was matched to at most three controls by sex, age, month, and year of first diagnosis of systemic sclerosis. Standardized incidence ratio (SIR) of Sjogren's syndrome in patients with systemic sclerosis and 95% confidence interval (95% CI) were calculated. Cox hazard regression was used to calculate the hazard ratio (HR). Both male and female patients with systemic sclerosis had higher incidences of Sjogren's syndrome (SIR: 7.59, 95% CI = 2.97-19.51; SIR: 7.59, 95% CI = 5.56-10.42, respectively). The incidence of Sjogren's syndrome in patients with systemic sclerosis was still higher compared with control when stratified according to age. Age at diagnosis of Sjogren's syndrome was earlier in patients with systemic sclerosis in both male and female groups (p = 0.018; p < 0.001, respectively). Systemic sclerosis was associated with Sjogren's syndrome after adjusting for age, sex, and various autoimmune diseases (HR: 5.98, 95% CI = 4.79-7.47, p < 0.001). Common cytokines, overlapping antibodies, and similar risk alleles were all potential causes of increased incidence of Sjogren's syndrome in systemic sclerosis.