Genetic contributors and soluble mediators in prediction of autoimmune comorbidity

Identification of the shared mechanisms and common biomarkers between Sjögren's syndrome and atherosclerosis using integrated bioinformatics analysis

Background

Sjögren's syndrome (SS) is a chronic autoimmune disease characterized by exocrine and extra-glandular symptoms. The literature indicates that SS is an independent risk factor for atherosclerosis (AS); however, its pathophysiological mechanism remains undetermined. This investigation aimed to elucidate the crosstalk genes and pathways influencing the pathophysiology of SS and AS via bioinformatic analysis of microarray data.

Methods

Microarray datasets of SS (GSE40611) and AS (GSE28829) were retrieved from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were acquired using R software's "limma" packages, and the functions of common DEGs were determined using Gene Ontology and Kyoto Encyclopedia analyses. The protein-protein interaction (PPI) was established using the STRING database. The hub genes were assessed via cytoHubba plug-in and validated by external validation datasets (GSE84844 for SS; GSE43292 for AS). Gene set enrichment analysis (GSEA) and immune infiltration of hub genes were also conducted.

Results

Eight 8 hub genes were identified using the intersection of four topological algorithms in the PPI network. Four genes (CTSS, IRF8, CYBB, and PTPRC) were then verified as important cross-talk genes between AS and SS with an area under the curve (AUC) ≥0.7. Furthermore, the immune infiltration analysis revealed that lymphocytes and macrophages are essentially linked with the pathogenesis of AS and SS. Moreover, the shared genes were enriched in multiple metabolisms and autoimmune disease-related pathways, as evidenced by GSEA analyses.

Conclusion

This is the first study to explore the common mechanism between SS and AS. Four key genes, including CTSS, CYBB, IRF8, and PTPRC, were associated with the pathogenesis of SS and AS. These hub genes and their correlation with immune cells could be a potential diagnostic and therapeutic target.

Genetics and epigenetics of primary Sjögren syndrome: implications for future therapies

In primary Sjögren syndrome (pSS), chronic inflammation of exocrine glands results in tissue destruction and sicca symptoms, primarily of the mouth and eyes. Fatigue, arthralgia and myalgia are also common symptoms, whereas extraglandular manifestations that involve the respiratory, nervous and vascular systems occur in a subset of patients. The disease predominantly affects women, with an estimated female to male ratio of 14 to 1. The aetiology of pSS, however, remains incompletely understood, and effective treatment is lacking. Large-scale genetic and epigenetic investigations have revealed associations between pSS and genes in both innate and adaptive immune pathways. The genetic variants mediate context-dependent effects, and both sex and environmental factors can influence the outcome. As such, genetic and epigenetic studies can provide insight into the dysregulated molecular mechanisms, which in turn might reveal new therapeutic possibilities. This Review discusses the genetic and epigenetic features that have been robustly connected with pSS, putting them into the context of cellular function, carrier sex and environmental challenges. In all, the observations point to several novel opportunities for early detection, treatment development and the pathway towards personalized medicine.

Risk of ischaemic heart diseases and stroke in behçet disease: A systematic review and meta-analysis

BACKGROUND

Behçet disease (BD) is a systemic vasculitis. In addition to the mucocutaneous lesions, the vascular injury of pathophysiology in BD is theoretically correlated with cardiovascular diseases. This study aimed to elucidate the association of BD with ischaemic heart diseases (IHDs) and stroke.

METHODS

A systematic search of PubMed, Embase, Web of Science and Cochrane Library databases was performed for all relevant observational studies from database inception until 10 July 2021. No language restriction was applied. A random-effects model was used for meta-analysis.

RESULTS

A total of six observational studies consisting of three cohort studies, two cross-sectional studies and one study with both study designs were adopted in the meta-analysis. The numbers of patients with BD and healthy controls were 9,813 and 41,802, respectively. The pooled analysis demonstrated no significant association between BD and IHD. By contrast, we found that patients with BD had a significantly higher risk of stroke (adjusted hazard ratio, 2.083; 95% confidence interval, 1.339-3.240; p = 0.001) than healthy controls. We observed substantial heterogeneity across studies in few meta-analyses, but no significant publication bias was detected in any of the meta-analyses.

CONCLUSIONS

BD was significantly associated with stroke but not IHD. Physicians should be aware of possible vascular and neurological complications during care of patients with BD.

Sjogren's Syndrome: Recent Updates

Primary Sjögren's syndrome (SS) is a chronic systemic autoimmune disorder affecting primarily perimenopausal women [...].

The Therapeutic Strategies for SLE by Targeting Anti-dsDNA Antibodies

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by diverse serological autoantibodies. Anti-dsDNA antibodies are involved in multiple organ damage, especially the kidney, skin, and central nervous system. Anti-dsDNA antibodies play a pivotal role in SLE, and researchers have developed therapeutic strategies targeting these antibodies. Approaches to reduce anti-dsDNA antibodies via B cell targeted biologics against B cell surface antigens, B cell survival factors, or Bruton's tyrosine kinase have effectively eliminated B cells. However, their non-specific depletion hampers normal immune system functioning and limits the therapeutic benefits. Thus, scientists have attempted anti-dsDNA antibodies or lupus-specific strategies, such as the immature dendritic cell vaccine and immunoadsorption. Recently, synthetic mimic peptides (hCDR1, pCONs, DWEYS, FISLE-412, and ALW) that directly block anti-dsDNA autoantibodies have attracted attention, which could ameliorate lupus, decrease the serological autoantibody titer, reduce the deposition of renal autoantibodies, and improve pathological performance. These potent small peptide molecules are well tolerated, non-toxic, and non-immunogenic, which have demonstrated a benign safety profile and are expected to be hopeful candidates for SLE management. In this review, we clarify the role of anti-dsDNA antibodies in SLE, mainly focus on the current strategies targeting anti-dsDNA antibodies, and discuss their potential clinical value.

Cardiovascular disease in systemic lupus erythematosus

There is a well-known increased risk for cardiovascular disease that contributes to morbidity and mortality in systemic lupus erythematosus (SLE). Major adverse cardiovascular events and subclinical atherosclerosis are both increased in this patient population. While traditional cardiac risk factors do contribute to the increased risk that is seen, lupus disease-related factors, medications, and genetic factors also impact the overall risk. SLE-specific inflammation, including oxidized lipids, cytokines, and altered immune cell subtypes all are likely to play a role in the pathogenesis of atherosclerotic plaques. Research is ongoing to identify biomarkers that can help clinicians to predict which SLE patients are at the greatest risk for cardiovascular disease (CVD). While SLE-specific treatment regimens for the prevention of cardiovascular events have not been identified, current strategies include minimization of traditional cardiac risk factors and lowering of overall lupus disease activity.

Interferon (IFN)-stimulated gene 15: A novel biomarker for lymphoma development in Sjögren's syndrome

OBJECTIVE

We investigated whether interferon (IFN) induced genes could serve as biomarkers for the detection of lymphoma development among patients with Sjögren's syndrome (SS).

METHODS

Total RNA was extracted from 98 labial minor salivary glands (LMSG) biopsies of SS patients [61 not complicated by lymphoma (SS-nL) and 37 complicated by Non-Hodgkin Lymphoma (NHL) (SS-L)] and 67 matched peripheral blood (PB) samples, as well as from 30 LMSG biopsies and 17 matched PB derived from sicca controls (SC). RNA sequencing was performed in LMSG biopsies of high and low risk SS patients for lymphoma development and SC. Expression analysis of type I (MX-1, IFIT-1, IFI44 and ISG-15) and type II IFN induced (CXCL9/MIG-1, GBP-1) genes was performed by real time PCR.

RESULTS

ISG-15 transcript levels were significantly higher in SS-L patients compared to SS-nL patients in both LMSG tissues and PB specimens. Additionally, MIG-1 was found to display higher expression values in LMSG tissues, but not in PB derived from SS-L patients compared to the SS-nL group. A coordinate expression in PB/LMSG of type I IFN (ISG-15, MX-1 and IFI44), but not type II IFN induced genes was also observed.

CONCLUSION

ISG-15 gene expression was able to distinguish SS-nL and SS-L at both periphery and tissue level and therefore could represent a novel biomarker for lymphoma development among SS patients. PB and LSMG seem to share a common transcriptional profile of type I IFN pathway.

Lipoprotein-Associated Phospholipase A2: A Novel Contributor in Sjögren's Syndrome-Related Lymphoma?

Background

B-cell non-Hodgkin’s lymphoma (B-NHL) is one of the major complications of primary Sjögren’s syndrome (SS). Chronic inflammation and macrophages in SS minor salivary glands have been previously suggested as significant predictors for lymphoma development among SS patients. Lipoprotein-associated phospholipase A2 (Lp-PLA2)—a product mainly of tissue macrophages—is found in the circulation associated with lipoproteins and has been previously involved in cardiovascular, autoimmune, and malignant diseases, including lymphoma.

Objective

The purpose of the current study was to investigate the contributory role of Lp-PLA2 in B-NHL development in the setting of primary SS.

Methods

Lp-PLA2 activity in serum samples collected from 50 primary SS patients with no lymphoma (SS-nL), 9 primary SS patients with lymphoma (SS-L), and 42 healthy controls (HC) was determined by detection of [³H]PAF degradation products by liquid scintillation counter. Moreover, additional sera from 50 SS-nL, 28 SS-L, and 32 HC were tested for Lp-PLA2 activity using a commercially available ELISA kit. Lp-PLA2 mRNA, and protein expression in minor salivary gland (MSG) tissue samples derived from SS-nL, SS-L patients, and sicca controls (SC) were analyzed by real-time PCR, Western blot, and immunohistochemistry.

Results

Serum Lp-PLA2 activity was significantly increased in SS-L compared to both SS-nL and HC by two independent methods implemented [mean ± SD (nmol/min/ml): 62.0 ± 13.4 vs 47.6 ± 14.4 vs 50.7 ± 16.6, p-values: 0.003 and 0.04, respectively, and 19.4 ± 4.5 vs 15.2 ± 3.3 vs 14.5 ± 3.0, p-values: <0.0001, in both comparisons]. ROC analysis revealed that the serum Lp-PLA2 activity measured either by radioimmunoassay or ELISA has the potential to distinguish between SS-L and SS-nL patients (area under the curve [AUC]: 0.8022, CI [95%]: 0.64–0.96, p-value: 0.004 for radioimmunoassay, and AUC: 0.7696, CI [95%]: 0.66–0.88, p-value: <0.0001, for ELISA). Lp-PLA2 expression in MSG tissues was also increased in SS-L compared to SS-nL and SC at both mRNA and protein level. ROC analysis revealed that both MSG mRNA and protein Lp-PLA2 have the potential to distinguish between SS-nL and SS-L patients (area under the curve [AUC] values of 0.8490, CI [95%]: 0.71–0.99, p-value: 0.0019 and 0.9444, CI [95%]: 0.79–1.00, p- value: 0.0389 respectively). No significant difference in either serum Lp-PLA2 activity or MSG tissue expression was observed between SS-nL and HC.

Conclusions

Lp-PLA2 serum activity and MSG tissue mRNA/protein expression could be a new biomarker and possibly a novel therapeutic target for B-cell lymphoproliferation in the setting of SS.

Is Behçet's syndrome associated with an increased risk of ischemic heart disease? A real-world evidence in Taiwan

BACKGROUND

A variety of chronic inflammatory diseases are linked to ischemic heart disease (IHD); however, this association is less well studied in patients with Behçet's syndrome (BS). The primary objective of this study was to examine the impact of BS on the risk of IHD. The secondary objective was to estimate the long-term mortality risk in patients with BS.

METHODS

Using a retrospective cohort design based on the Taiwan National Health Insurance Database, patients diagnosed with BS between 2000 and 2013, without prior history of IHD, were compared to non-BS individuals. The BS and non-BS cohorts were matched with a 1:2 ratio by propensity score, accounting for the following confounders: age, sex, year of index date, comorbidities, and drug exposure. Cox proportional hazard regression was used to derive the hazard ratio (HR) for IHD and mortality. The long-term survival rate was estimated using the Kaplan-Meier method.

RESULTS

After propensity score matching, a total of 1554 patients newly diagnosed with BS and 3108 control subjects were identified. The incidence rate of IHD in the BS and control groups was 2.7 and 2.9 per 1000 person-years, respectively. The risk of IHD was comparable between BS and control cohorts [adjusted HR, 1.03; 95% confidence interval (CI), 0.66 to 1.62]. The 5- and 10-year survival rate of BS patients was 96.8% and 95.0%, respectively. Patients with BS exhibited a significantly higher risk of mortality than the sex- and age-matched general population (adjusted HR, 1.73; 95% CI, 1.30 to 2.32).

CONCLUSION

Unlike other chronic systemic autoimmune disorders, BS does not appear to be associated with an excess risk of IHD.

Autoimmune Rheumatic Diseases: An Update on the Role of Atherogenic Electronegative LDL and Potential Therapeutic Strategies

Atherosclerosis has been linked with an increased risk of atherosclerotic cardiovascular disease (ASCVD). Autoimmune rheumatic diseases (AIRDs) are associated with accelerated atherosclerosis and ASCVD. However, the mechanisms underlying the high ASCVD burden in patients with AIRDs cannot be explained only by conventional risk factors despite disease-specific factors and chronic inflammation. Nevertheless, the normal levels of plasma low-density lipoprotein (LDL) cholesterol observed in most patients with AIRDs do not exclude the possibility of increased LDL atherogenicity. By using anion-exchange chromatography, human LDL can be divided into five increasingly electronegative subfractions, L1 to L5, or into electropositive and electronegative counterparts, LDL (+) and LDL (-). Electronegative L5 and LDL (-) have similar chemical compositions and can induce adverse inflammatory reactions in vascular cells. Notably, the percentage of L5 or LDL (-) in total LDL is increased in normolipidemic patients with AIRDs. Electronegative L5 and LDL (-) are not recognized by the normal LDL receptor but instead signal through the lectin-like oxidized LDL receptor 1 (LOX-1) to activate inflammasomes involving interleukin 1β (IL-1β). Here, we describe the detailed mechanisms of AIRD-related ASCVD mediated by L5 or LDL (-) and discuss the potential targeting of LOX-1 or IL-1β signaling as new therapeutic modalities for these diseases.

Upregulated expression of leukocyte immunoglobulin-like receptor A3 in patients with severe aplastic anemia

Severe aplastic anemia (SAA) is a rare and potentially life-threatening disease characterized by pancytopenia and bone marrow (BM) hypoplasia. In a previous study by our group, increased expression of leukocyte immunoglobulin-like receptors A (LILRA), LILRA3 in myeloid dendritic cells (mDCs) and LILRA5 in CD34⁺ cells in SAA was detected using proteomics techniques, highlighting their potential role in disease pathogenesis. In the present study, the expression of LILRA1-6 mRNA was assessed in the BM mononuclear cells of patients with SAA using reverse transcription-quantitative (RT-q)PCR. The expression of homogenic LILRA3 and LILRA5 isoform on mDCs, as well as CD34⁺, CD3⁺CD8⁺, CD19⁺ and CD14⁺ cells, was detected using flow cytometry. mDCs were then induced, cultured and sorted. The expression of LILRA3 was confirmed using RT-qPCR and western blot analyses. The serum levels of soluble LILRA3 were measured using ELISA. Furthermore, the relationship between LILRA3 expression and disease severity was assessed. The results indicated increased LILRA3 mRNA expression in patients with SAA. The percentage of LILRA3⁺ in BM mDCs and CD34⁺ cells was increased. Compared with controls, the relative LILRA3 mRNA expression and the relative protein intensity were highly increased in SAA mDCs. The serum LILRA3 levels in patients with SAA were also increased. The proportion of LILRA3⁺CD11C⁺ human leukocyte antigen (HLA)-DR⁺/CD11C⁺HLA-DR⁺ cells was positively correlated with the ratio of LILRA3⁺CD34⁺/CD34⁺ cells and the expression of LILRA3 mRNA. Taken together, the expression of LILRA3 on mDCs of patients with SAA was increased, which may affect the function of mDCs. LILRA3 may have a significant role in the immune pathogenesis of SAA.

Leukocyte Immunoglobulin-Like Receptor A3 (LILRA3): A Novel Marker for Lymphoma Development among Patients with Young Onset Sjogren's Syndrome

Background: Primary Sjogren’s syndrome (SS) is an autoimmune disease with a strong predilection for lymphoma development, with earlier disease onset being postulated as an independent risk factor for this complication. Variations of the Leukocyte immunoglobulin-like receptor A3(LILRA3) gene have been previously shown to increase susceptibility for both SS and non-Hodgkin B-cell lymphoma (B-NHL) in the general population. We aimed to investigate whether variations of the LILRA3 gene could predispose for lymphoma development in the context of SS. Methods: Study population, all of Greek origin, included 101 SS cases with a current or previous diagnosis of lymphoma (SS-lymphoma, SS-L) and 301 primary SS patients not complicated by lymphoma (SS-non-lymphoma, SS-nL). All SS patients fulfilled the 2016 SS American College of Rheumatology/European league against Rheumatism (ACR/EULAR) classification criteria. A total of 381 healthy controls (HC) of similar age/sex/race distribution were also included. On the basis of the age of SS onset and the presence or absence of adverse predictors for lymphoma development, SS patients were further stratified into younger (≤40 years) and older (>40 years) age of disease onset, as well as into high/medium and low risk groups. Polymerase chain reaction (PCR) was implemented for the detection of the following LILRA3 gene variants: homozygous non-deleted or functional wild type (+/+) heterozygous (+/−) and homozygous deleted (−/−). LILRA3 serum protein levels were quantitated by enzyme-linked immunosorbent assay (ELISA) in 85 individuals (29 SS-L, 35 SS-nL patients and 21 HC). Results: While no statistically significant differences were detected in the overall frequency of LILRA3 gene variants between SS-L, SS-nL and HC groups, LILRA3 serum protein levels were increased in the SS-L group compared to HC (1.27 ± 1.34 vs. 0.38 ± 0.34 ng/mL, p-value: 0.004). After stratification according to the age of SS onset and history of lymphoma, as well as the presence or absence of adverse predictors for lymphoma development, the prevalence of the functional LILRA3 gene variant was found to be significantly increased in the young onset SS-L group compared to the HC of similar age and sex distribution (100% vs. 82.9%, p = 0.03), as well as in the high/medium risk SS compared to the low risk SS (91.3 vs. 78.3%, p = 0.0012). Of note, young onset SS-L and SS-nL groups displayed higher LILRA3 serum levels compared to their older counterparts (p-values: 0.007 and 0.0005, respectively). Conclusion: The functional LILRA3 gene variant increases susceptibility to SS-related lymphoma development in patients with a disease onset of <40 years old, implying that genetically determined deranged immune responses in younger SS individuals could underly their pronounced risk for lymphoma development.