Th1-related transcription factors and cytokines in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an inflammatory disorder related to immunity dysfunction. The Th1 cell family including Th1 cells, transcription factor T-bet, and related cytokines IFNγ, TNFα, IL-2, IL-18, TGF-β, and IL-12 have been widely discussed in autoimmunity, such as SLE. In this review, we will comprehensively discuss the expression profile of the Th1 cell family in both SLE patients and animal models and clarify how the family members are involved in lupus development. Interestingly, T-bet-related age-associated B cells (ABCs) and low-dose IL-2 treatment in lupus were emergently discussed as well. Collection of the evidence will better understand the roles of the Th1 cell family in lupus pathogenesis, especially targeting IL-2 in lupus.

Association between interleukin 12B and interleukin 23R gene polymorphisms and systemic lupus erythematosus: a meta-analysis

OBJECTIVE

To determine whether polymorphisms of interleukin 12B (IL12B) and IL23 receptor genes (IL23R) confer susceptibility to systemic lupus erythematosus (SLE).

METHODS

A meta-analysis was conducted to analyze the associations between SLE and IL12B rs3212227 and rs17860508 and IL23R rs7517847, rs10489629, rs10889677, rs1004819, rs11209026, rs11209032, rs1343151, and rs1884444 polymorphisms using allele contrast, dominant, recessive, heterozygote, and homozygote models. Ten studies involving 1989 patients with SLE and 2394 controls were considered for the meta-analysis.

RESULTS

The meta-analysis using the homozygote model revealed that IL23R rs10889677 was significantly associated with SLE susceptibility in the overall population (AA vs. CC) (odds ratio = 0.70, 95% confidence interval = 0.50-0.98) but not in the Asian population. Other polymorphisms of IL12B and IL23R were not significantly associated with SLE protection.

CONCLUSIONS

These findings suggest that the IL23R rs10889677 polymorphism confers SLE susceptibility to individuals of certain ethnicities. (Research Registry number: 1268).

CCL3L3-null status is associated with susceptibility to systemic lupus erythematosus

The correlation between copy number variation (CNV) and the susceptibility to systemic lupus erythematosus (SLE) has been reported for various immunity-related genes. However, the contribution of CNVs to SLE susceptibility awaits more investigation. To evaluate the copy numbers in immunity-related genes such as TNFAIP3, TNIP1, IL12B, TBX21 (T-bet), TLR7, C4A, C4B, CCL3L1, and CCL3L3, the modified real competitive polymerase chain reaction (mrcPCR) assay was employed, and the association between the copy numbers and SLE susceptibility was analyzed in 334 SLE patients and 338 controls. CCL3L3-null status was significantly associated with SLE susceptibility (OR > 18, P < 0.0001), which remained significant by Bonferroni's correction (corrected P = 0.0007). However, the significant association between C4B low-copy status and SLE susceptibility (OR = 1.6051, P = 0.0331) became non-significant by Bonferroni's correction (corrected P = 0.3938). Except for these results, no other significant association between SLE susceptibility and copy number status in other genes was observed. The CCL3L3-null status may be a significant factor for SLE susceptibility.

CD52 Is Elevated on B cells of SLE Patients and Regulates B Cell Function

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by B cell dysregulation and breaks in tolerance that lead to the production of pathogenic autoantibodies. We performed single-cell RNA sequencing of B cells from healthy donors and individuals with SLE which revealed upregulated CD52 expression in SLE patients. We further demonstrate that SLE patients exhibit significantly increased levels of B cell surface CD52 expression and plasma soluble CD52, and levels of soluble CD52 positively correlate with measures of lupus disease activity. Using CD52-deficient JeKo-1 cells, we show that cells lacking surface CD52 expression are hyperresponsive to B cell receptor (BCR) signaling, suggesting an inhibitory role for the surface-bound protein. In healthy donor B cells, antigen-specific BCR-activation initiated CD52 cleavage in a phospholipase C dependent manner, significantly reducing cell surface levels. Experiments with recombinant CD52-Fc showed that soluble CD52 inhibits BCR signaling in a manner partially-dependent on Siglec-10. Moreover, incubation of unstimulated B cells with CD52-Fc resulted in the reduction of surface immunoglobulin and CXCR5. Prolonged incubation of B cells with CD52 resulted in the expansion of IgD+IgMlo anergic B cells. In summary, our findings suggest that CD52 functions as a homeostatic protein on B cells, by inhibiting responses to BCR signaling. Further, our data demonstrate that CD52 is cleaved from the B cell surface upon antigen engagement, and can suppress B cell function in an autocrine and paracrine manner. We propose that increased expression of CD52 by B cells in SLE represents a homeostatic mechanism to suppress B cell hyperactivity.

The STAT4 SLE risk allele rs7574865[T] is associated with increased IL-12-induced IFN-γ production in T cells from patients with SLE

Objectives

Genetic variants in the transcription factor STAT4 are associated with increased susceptibility to systemic lupus erythematosus (SLE) and a more severe disease phenotype. This study aimed to clarify how the SLE-associated intronic STAT4 risk allele rs7574865[T] affects the function of immune cells in SLE.

Methods

Peripheral blood mononuclear cells (PBMCs) were isolated from 52 genotyped patients with SLE. Phosphorylation of STAT4 (pSTAT4) and STAT1 (pSTAT1) in response to interferon (IFN)-α, IFN-γ or interleukin (IL)-12, total levels of STAT4, STAT1 and T-bet, and frequency of IFN-γ⁺ cells on IL-12 stimulation were determined by flow cytometry in subsets of immune cells before and after preactivation of cells with phytohaemagglutinin (PHA) and IL-2. Cellular responses and phenotypes were correlated to STAT4 risk allele carriership. Janus kinase inhibitors (JAKi) selective for TYK2 (TYK2i) or JAK2 (JAK2i) were evaluated for inhibition of IL-12 or IFN-γ-induced activation of SLE PBMCs.

Results

In resting PBMCs, the STAT4 risk allele was neither associated with total levels of STAT4 or STAT1, nor cytokine-induced pSTAT4 or pSTAT1. Following PHA/IL-2 activation, CD8⁺ T cells from STAT4 risk allele carriers displayed increased levels of STAT4 resulting in increased pSTAT4 in response to IL-12 and IFN-α, and an augmented IL-12-induced IFN-γ production in CD8⁺ and CD4⁺ T cells. The TYK2i and the JAK2i efficiently blocked IL-12 and IFN-γ-induced activation of PBMCs from STAT4 risk patients, respectively.

Conclusions

T cells from patients with SLE carrying the STAT4 risk allele rs7574865[T] display an augmented response to IL-12 and IFN-α. This subset of patients may benefit from JAKi treatment.

Clinical significance of germline copy number variation in susceptibility of human diseases

Germline copy number variation (CNV) is considered to be an important form of human genetic polymorphisms. Previous studies have identified amounts of CNVs in human genome by advanced technologies, such as comparative genomic hybridization, single nucleotide genotyping, and high-throughput sequencing. CNV is speculated to be derived from multiple mechanisms, such as nonallelic homologous recombination (NAHR) and nonhomologous end-joining (NHEJ). CNVs cover a much larger genome scale than single nucleotide polymorphisms (SNPs), and may alter gene expression levels by means of gene dosage, gene fusion, gene disruption, and long-range regulation effects, thus affecting individual phenotypes and playing crucial roles in human pathogenesis. The number of studies linking CNVs with common complex diseases has increased dramatically in recent years. Here, we provide a comprehensive review of the current understanding of germline CNVs, and summarize the association of germline CNVs with the susceptibility to a wide variety of human diseases that were identified in recent years. We also propose potential issues that should be addressed in future studies.

Genetic Variants in IL-12B and IL-27 in the Polish Patients with Systemic Lupus Erythematosus

To investigate the potential association between IL-12B and IL-27 gene polymorphisms and systemic lupus erythematosus (SLE), we performed a case-control study based on the Polish population. Patients with SLE and healthy individuals were examined for -6415 CTCTAA/GC (rs17860508) and +1188A/C (rs3212227) in IL-12B and -924A/G (rs153109) and 4730T/C (rs181206) in IL-27 gene polymorphisms using the high-resolution melting method, PCR-RFLP method and TaqMan SNP genotyping assay, respectively. An increased frequency of GC/GC genotype as well as GC allele of the IL-12B rs17860508 was found in patients with SLE, as compared with healthy subjects (P < 0.001). We did not find differences in genotype and allele frequencies of the IL-12B rs3212227 and IL-27 rs153109 and rs181206 variants between patients with SLE and controls. IL-27 haplotype rs181206C/rs153109G indicated higher risk for SLE (P = 0.002), whereas haplotype rs181206T/rs153109G indicated reduced risk for SLE (P = 0.005). The IL-12B rs3212227 A/C polymorphism was associated with the mean value of the platelets (PLT), urea and complement C3 level. Furthermore, IL-12B rs17860508 genetic variant showed correlation with PLT, prothrombin time, international normalized ratio and alkaline phosphatase. Our results revealed that IL-12B rs17860508 and IL-27 haplotype CG are genetic risk factors for SLE and that both IL-12B rs17860508 and rs3212227 predict disease phenotype.

Relationship between the IL12B (rs3212227) gene polymorphism and susceptibility to multiple autoimmune diseases: A meta-analysis

OBJECTIVES

The purpose of this study was to evaluate whether a single-nucleotide polymorphism (SNP) IL12B 3(')UTR +1188A/C (rs3212227) confers susceptibility to several autoimmune diseases.

METHODS

A systematic literature search was conducted to identify relevant studies. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to estimate the strength of association.

RESULTS

Twenty-five studies were included in the meta-analysis, which contained 9794 cases and 11,330 controls. Our result indicated that IL12B +1188A/C (rs3212227) polymorphism was associated with type-1 diabetes (T1D) in the dominant model (p = 0.008), and an increased risk was found in East Asians in the dominant model (p < 0.001). East Asians rheumatoid arthritis (RA) patients seemed to be at risk of allelic model (p = 0.011). As to Behcet's disease (BD), there was a risk in dominant model (p = 0.020) and positive associations of dominant model, allelic model in East Asians (p = 0.009; p < 0.001, respectively). But we failed to find any association between IL12B +1188A/C (rs3212227) polymorphism with Graves' disease (GD) and ankylosing spondylitis (AS).

CONCLUSIONS

The present study suggests that the IL12B +1188A/C (rs3212227) polymorphism might be associated with genetic susceptibility to autoimmune diseases, such as T1D, RA, BD, but not GD and AS.

Copy number variants and genetic polymorphisms in TBX21, GATA3, Rorc, Foxp3 and susceptibility to Behcet's disease and Vogt-Koyanagi-Harada syndrome

This study aimed to investigate the role of genetic variants including single nucleotide polymorphisms (SNPs) and copy number variants (CNVs) of TBX21, GATA3, Rorc and Foxp3 genes in Behcet's disease (BD) and Vogt-Koyanagi-Harada (VKH) syndrome in a Chinese Han population. Genotyping of 25 SNPs was performed by iPLEX system (Sequenom) or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). TaqMan real time PCR was used to assess CNVs. The expression of Rorc and Foxp3 were examined by real-time PCR and cytokine production was measured by ELISA. High Rorc CNV was associated with the susceptibility to BD (P = 8.99 × 10(-8), OR = 3.0), and low Foxp3 CNV predisposed to BD in female patients (P = 1.92 × 10(-5), OR = 3.1). CNVs for the investigated genes were not altered in VKH syndrome. Further functional studies demonstrated that the relative mRNA expression levels of Rorc were increased in individuals with high Rorc copy number, but not for Foxp3. Increased production of IL-1β and IL-6 was found in individuals carrying a high CNV of Rorc. Our study showed that high CNVs of Rorc and low CNVs of Foxp3 confer risk for BD but not for VKH syndrome. The tested 25 SNPs in TBX21, GATA3, Rorc and Foxp3 did not associate with BD and VKH syndrome.

The polymorphisms of T cell-specific TBX21 gene may contribute to the susceptibility of chronic immune thrombocytopenia in Chinese population

Chronic primary immune thrombocytopenia (ITP) is an acquired autoimmune hemorrhagic disease characterized by both reduced platelet counts and suppression of megakaryocyte and platelet development. T cell-specific T-box transcription factor gene (TBX21) plays a critical role in the development and maintenance of T helper 1 (Th1) cells. Recently, several studies have confirmed that the T-1554C and T-1993C polymorphisms of this gene can influence its expression level and are associated with autoimmune diseases. Therefore, we speculated that TBX21 polymorphisms might be associated with the susceptibility of chronic ITP in Chinese population. We investigated the distributions of TBX21 (T-1514C and T-1993C) polymorphisms in 275 patients with chronic ITP and 261 healthy controls by polymerase chain reaction-restriction fragment length polymorphism. We observed significant overrepresentation of T allele and T/T genotype at T-1993C (but not T-1514C) in patients compared with controls. Stratified analysis by gender and age of disease onset revealed comparable observations in both female and childhood ITP cohorts. In conclusion, the T-1993C polymorphisms of TBX21 gene may be associated with the susceptibility of chronic primary ITP in Chinese population.

Biomarkers in systemic lupus erythematosus: challenges and prospects for the future

The search for lupus biomarkers to diagnose, monitor, stratify, and predict individual response to therapy is currently more intense than ever before. This effort is essential for several reasons. First, epidemic overdiagnosis and underdiagnosis of lupus, even by certified rheumatologists, leads to errors in therapy with concomitant side effects which may be more serious than the disease itself. Second, identification of lupus flares remains as much an art as it is a science. Third, the capacity to stratify patients so as to predict those who will develop specific patterns of organ involvement is not currently possible but would potentially lead to preventive therapeutic strategies. Fourth, only one new drug for the treatment of lupus has been approved by the US Food and Drug Administration in over 50 years. A major obstacle in this pipeline is the dearth of biomarkers available to prove a patient has responded to an experimental therapeutic intervention. This review will summarize the challenges faced in the discovery and validation of lupus biomarkers, the most promising lupus biomarkers identified to date, and the promise of future directions.

Role of cytokines in systemic lupus erythematosus: recent progress from GWAS and sequencing

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder, known to have a strong genetic component. Concordance between monozygotic twins is approximately 30-40%, which is 8-20 times higher than that of dizygotic twins. In the last decade, genome-wide approaches to understanding SLE have yielded many candidate genes, which are important to understanding the pathophysiology of the disease and potential targets for pharmaceutical intervention. In this paper, we focus on the role of cytokines and examine how genome-wide association studies, copy number variation studies, and next-generation sequencing are being employed to understand the etiology of SLE. Prominent genes identified by these approaches include BLK, FCγR3B, and TREX1. Our goal is to present a brief overview of genomic approaches to SLE and to introduce some of the key discussion points pertinent to the field.

The dysregulation of cytokine networks in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease associated with chronic immune activation and tissue damage. Organ damage in SLE results from the deposition of immune complexes and the infiltration of activated T cells into susceptible organs. Cytokines are intimately involved in every step of the SLE pathogenesis. Defective immune regulation and uncontrolled lymphocyte activation, as well as increased antigen presenting cell maturation are all influenced by cytokines. Moreover, expansion of local immune responses as well as tissue infiltration by pathogenic cells is instigated by cytokines. In this review, we describe the main cytokine abnormalities reported in SLE and discuss the mechanisms that drive their aberrant production as well as the pathogenic pathways that their presence promotes.