Type III Interferons in Systemic Lupus Erythematosus: Association Between Interferon λ3, Disease Activity, and Anti-Ro/SSA Antibodies

Type 2 hypersensitivity disorders, including systemic lupus erythematosus, Sjögren's syndrome, Graves' disease, myasthenia gravis, immune thrombocytopenia, autoimmune hemolytic anemia, dermatomyositis, and graft-versus-host disease, are THαβ-dominant autoimmune diseases

The THαβ host immunological pathway contributes to the response to infectious particles (viruses and prions). Furthermore, there is increasing evidence for associations between autoimmune diseases, and particularly type 2 hypersensitivity disorders, and the THαβ immune response. For example, patients with systemic lupus erythematosus often produce anti-double stranded DNA antibodies and anti-nuclear antibodies and show elevated levels of type 1 interferons, type 3 interferons, interleukin-10, IgG1, and IgA1 throughout the disease course. These cytokines and antibody isotypes are associated with the THαβ host immunological pathway. Similarly, the type 2 hypersensitivity disorders myasthenia gravis, Graves' disease, graft-versus-host disease, autoimmune hemolytic anemia, immune thrombocytopenia, dermatomyositis, and Sjögren's syndrome have also been linked to the THαβ pathway. Considering the potential associations between these diseases and dysregulated THαβ immune responses, therapeutic strategies such as anti-interleukin-10 or anti-interferon α/β could be explored for effective management.

Uncoupling interferons and the interferon signature explains clinical and transcriptional subsets in SLE

Systemic lupus erythematosus (SLE) displays a hallmark interferon (IFN) signature. Yet, clinical trials targeting type I IFN (IFN-I) have shown variable efficacy, and blocking IFN-II failed to treat SLE. Here, we show that IFN type levels in SLE vary significantly across clinical and transcriptional endotypes. Whereas skin involvement correlated with IFN-I alone, systemic features like nephritis associated with co-elevation of IFN-I, IFN-II, and IFN-III, indicating additive IFN effects in severe SLE. Notably, while high IFN-II/-III levels without IFN-I had a limited effect on disease activity, IFN-II was linked to IFN-I-independent transcriptional profiles (e.g., OXPHOS and CD8+GZMH+ cells), and IFN-III enhanced IFN-induced gene expression when co-elevated with IFN-I. Moreover, dysregulated IFNs do not explain the IFN signature in 64% of patients or clinical manifestations including cytopenia, serositis, and anti-phospholipid syndrome, implying IFN-independent endotypes in SLE. This study sheds light on mechanisms underlying SLE heterogeneity and the variable response to IFN-targeted therapies in clinical trials.

Prognostic Role of Interferon-λ3 in Anti-Melanoma Differentiation-Associated Gene 5-Positive Dermatomyositis-Associated Interstitial Lung Disease

OBJECTIVE

Interferon-λ3 (IFNλ3) is a cytokine with antiviral functions on barrier surfaces, and it is associated with disease activity in autoimmune diseases. This study assessed the clinical significance of serum IFNλ3 levels in polymyositis/dermatomyositis (PM/DM)-associated interstitial lung disease (ILD).

METHODS

We measured serum IFNλ3 levels in 221 patients with PM/DM-ILD (155 in the derivation cohort, 66 in the validation cohort) and 38 controls. We evaluated factors associated with mortality risk among 79 patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive DM-ILD.

RESULTS

Serum IFNλ3 levels at diagnosis were significantly higher in patients with PM/DM-ILD than in healthy controls. Remarkably, serum IFNλ3 levels were specifically increased in patients with anti-MDA5 antibody-positive DM-ILD in both the derivation and validation cohorts. In anti-MDA5 antibody-positive DM-ILD, patients with high IFNλ3 levels (>120 pg/mL) had significantly lower survival rates than those with low IFNλ3 levels (≤120 pg/mL). A multivariate analysis revealed that high IFNλ3 levels, as well as old age and low Pao2, were significantly associated with poor prognoses in patients with anti-MDA5 antibody-positive DM-ILD. In a classification analysis of patients with anti-MDA5 antibody-positive DM-ILD based on age, IFNλ3 level, and Pao2, patients with old age (>53 years), high IFNλ3 levels (>120 pg/mL), and low Pao2 (<75 mm Hg) had the worst survival. In lung pathologic analyses, IFNλ3-positive staining was observed in macrophages, airway epithelial cells, the pleural region, and intrapulmonary veins in patients with anti-MDA5 antibody-positive DM-ILD.

CONCLUSION

Serum IFNλ3 is a promising biomarker for identifying patients at high risk of poor outcomes in anti-MDA5 antibody-positive DM-ILD.

Association between endothelin-1 and systemic lupus erythematosus: insights from a case-control study

Systemic lupus erythematosus (SLE) is a chronic rheumatic disorder. Endothelin-1, a vasoconstrictor, belongs to the endothelin family and is associated with vascular-related damages. To date, association between ET-1 and pathogenesis of SLE remains unclear. This case-control study was carried out by 314 SLE, 252 non-SLE diseases patients and 500 healthy controls. Serum ET-1, CCN3, IL-28B levels were detected by ELISA, and ET-1 gene polymorphisms (rs5369, rs5370, rs1476046, rs2070699, rs2071942, rs2071943, rs3087459, rs4145451, rs6458155, rs9369217) were genotyped with Kompetitive Allele-Specific PCR. SLE patients had high levels of ET-1, which were correlated with some clinical, laboratory features. Serum CCN3, IL-28B levels were higher in SLE patients, and ET-1 levels were positively correlated with the two cytokines. Rs5370, rs1476046, rs2070699, rs2071942, rs2071943, rs3087459, rs6458155 and rs2070699 were associated with SLE risk. Rs2070699 (T, TT) was related to SLE patients with alopecia. Rs5370 (T, TT, TG), rs1476046 (G,GA), rs2071942 (G,GA) and rs2071943 (G,GA) were associated with SLE patients with pericarditis, pyuria and fever manifestation, respectively. Rs3087459 (CC) and rs9369217 (TC) were related to SLE patients with positive anti-SSB antibody. Rs5369 (AA) was associated with IgG and CRP levels in SLE patients. In conclusion, elevated serum ET-1 in SLE patients may be a potential disease marker, and its gene polymorphisms were related to SLE susceptibility.

Uncoupling interferons and the interferon signature explain clinical and transcriptional subsets in SLE

Interferons (IFN) are thought to be key players in systemic lupus erythematosus (SLE). The unique and interactive roles of the different IFN families in SLE pathogenesis, however, remain poorly understood. Using reporter cells engineered to precisely quantify IFN-I, IFN-II and IFN-III activity levels in serum/plasma, we found that while IFNs play essential role in SLE pathogenesis and disease activity, they are only significant in specific subsets of patients. Interestingly, whereas IFN-I is the main IFN that governs disease activity in SLE, clinical subsets are defined by the co-elevation of IFN-II and IFN-III. Thus, increased IFN-I alone was only associated with cutaneous lupus. In contrast, systemic features, such as nephritis, were linked to co-elevation of IFN-I plus IFN-II and IFN-III, implying a synergistic effect of IFNs in severe SLE. Intriguingly, while increased IFN-I levels were strongly associated with IFN-induced gene expression (93.5%), in up to 64% of cases, the IFN signature was not associated with IFN-I. Importantly, neither IFN-II nor IFN-III explained IFN-induced gene expression in patients with normal IFN-I levels, and not every feature in SLE was associated with elevated IFNs, suggesting IFN-independent subsets in SLE. Together, the data suggest that, unlike the IFN signature, direct quantification of bioactive IFNs can identify pathogenic and clinically relevant SLE subsets amenable for precise anti-IFN therapies. Since IFN-I is only elevated in a subset of SLE patients expressing the IFN signature, this study explains the heterogeneous response in clinical trials targeting IFN-I, where patients were selected based on IFN-induced gene expression rather than IFN-I levels.

Performance analysis of Luminex and ELISA to profile serum IP-10 as a biomarker in systemic lupus erythematosus

OBJECTIVE

Interferon-γ inducible protein-10 (IP-10) is a promising biomarker in systemic lupus erythematosus (SLE). The optimal quantification platform has not yet been identified. We compared the performance of bead-based multiplex assay (Luminex) and high-sensitivity enzyme-linked immunosorbent assay (hs-ELISA) for profiling serum IP-10 as a biomarker of lupus activity.

METHODS

A cross-sectional study was conducted on outpatients with SLE. Serum IP-10 was measured simultaneously on Luminex and hs-ELISA, and correlation between platforms was assessed. Additionally, IP-10 levels were tested against disease activity and organ involvement.

RESULTS

One-hundred and forty-one patients (88% women; 38 years old) were studied. Median IP-10 levels were 100.9 (125.2) pg/mL by Luminex and 156.5 (191.7) pg/mL by hs-ELISA. Correlation analysis showed Spearman's ρ = 0.621 (p < 0.0001) between Luminex and hs-ELISA. Quantification of IP-10 by Luminex showed a significant correlation (ρ = 0.198; p = 0.021) with disease activity, while this was not observed (ρ = 0.036; p = 0.683) when measured using hs-ELISA. Serum IP-10 levels were lower in quiescent patients than in those with active disease (70.8 [68.4] versus 114.3 [123.9] pg/mL; p = 0.024), with an AUC-ROC = 0.62 (p = 0.029), sensitivity = 47.9%, specificity = 77.5%, and positive likelihood ratio = 2.1. Patients with active arthritis had higher IP-10 levels than non-arthritis patients (158.1 [505.4] versus 94.1 [114.0] pg/mL; p = 0.008), with an AUC-ROC = 0.73 (p = 0.0009), sensitivity = 72.7%, specificity = 66.4%, and positive likelihood ratio = 2.1. No other type of organ involvement was identified by serum IP-10.

CONCLUSIONS

Luminex performs better than hs-ELISA as a quantification platform for IP-10 as it correlates with disease activity and identifies active arthritis in SLE.

Placental damage in pregnancies with systemic lupus erythematosus: A narrative review

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease of unknown cause, which mainly affects women of childbearing age, especially between 15 and 55 years of age. During pregnancy, SLE is associated with a high risk of perinatal morbidity and mortality. Among the most frequent complications are spontaneous abortion, fetal death, prematurity, intrauterine Fetal growth restriction (FGR), and preeclampsia (PE). The pathophysiology underlying obstetric mortality and morbidity in SLE is still under investigation, but several studies in recent years have suggested that placental dysfunction may play a crucial role. Understanding this association will contribute to developing therapeutic options and improving patient management thus reducing the occurrence of adverse pregnancy outcomes in this group of women. In this review, we will focus on the relationship between SLE and placental insufficiency leading to adverse pregnancy outcomes.

Interferon Lambda Regulates Cellular and Humoral Immunity in Pristane-Induced Lupus

A pivotal role of type I interferons in systemic lupus erythematosus (SLE) is widely accepted. Type III interferons (IFN-λ) however, the most recently discovered cytokines grouped within the interferon family, have not been extensively studied in lupus disease models yet. Growing evidence suggests a role for IFN-λ in regulating both innate and adaptive immune responses, and increased serum concentrations have been described in multiple autoimmune diseases including SLE. Using the pristane-induced lupus model, we found that mice with defective IFN-λ receptors (Ifnlr1^−/−) showed increased survival rates, decreased lipogranuloma formation and reduced anti-dsDNA autoantibody titers in the early phase of autoimmunity development compared to pristane-treated wild-type mice. Moreover, Ifnlr1^−/− mice treated with pristane had reduced numbers of inflammatory mononuclear phagocytes and cNK cells in their kidneys, resembling untreated control mice. Systemically, circulating B cells and monocytes (CD115⁺Ly6C⁺) were reduced in pristane-treated Ifnlr1^−/− mice. The present study supports a significant role for type III interferons in the pathogenesis of pristane-induced murine autoimmunity as well as in systemic and renal inflammation. Although the absence of type III interferon receptors does not completely prevent the development of autoantibodies, type III interferon signaling accelerates the development of autoimmunity and promotes a pro-inflammatory environment in autoimmune-prone hosts.

Cytokines as Biomarkers in Systemic Lupus Erythematosus: Value for Diagnosis and Drug Therapy

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease. The disease is characterized by activation and dysregulation of both the innate and the adaptive immune systems. The autoimmune response targets self-molecules including cell nuclei, double stranded DNA and other intra and extracellular structures. Multiple susceptibility genes within the immune system have been identified, as well as disturbances in different immune pathways. SLE may affect different organs and organ systems, and organ involvement is diverse among individuals. A universal understanding of pathophysiological mechanism of the disease, as well as directed therapies, are still missing. Cytokines are immunomodulating molecules produced by cells of the immune system. Interferons (IFNs) are a broad group of cytokines, primarily produced by the innate immune system. The IFN system has been observed to be dysregulated in SLE, and therefore IFNs have been extensively studied with a hope to understand the disease mechanisms and identify novel targeted therapies. In several autoimmune diseases identification and subsequent blockade of specific cytokines has led to successful therapies, for example tumor necrosis factor-alpha (TNF-α) inhibition in rheumatoid arthritis. Authors of this review have sought corresponding developments in SLE. In the current review, we cover the actual knowledge on IFNs and other studied cytokines as biomarkers and treatment targets in SLE.

Roles of IL-1 and IL-10 family cytokines in the progression of systemic lupus erythematosus: Friends or foes?

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease of unknown etiology that can affect nearly every organ system in the body. Besides genetic and environmental factors, unbalanced pro-inflammatory and anti-inflammatory cytokines contribute to immune dysregulation, trigger an inflammatory response, and induce tissue and organ damage. Inflammatory responses in SLE can be promoted and/or maintained by the availability of cytokines that are overproduced systemically and/or in local tissues. Several key cytokines have been considered potential targets for the reduction of chronic inflammation in SLE. Recent studies indicated that dysregulated production of several cytokines, including those of the IL-1 family and IL-10 family, orchestrate immune activation and self-tolerance, play critical roles in the pathogenesis of SLE. Among IL-1 family cytokines, IL-1, IL-18, IL-33, IL-36, IL-37, and IL-38 had been the most thoroughly investigated in SLE. Additionally, IL-10 family cytokines, IL-10, IL-20, IL-22, IL-26, IL-28, and IL-29 are dysregulated in SLE. Therefore, a better understanding of the initiation and progression of SLE may provide suitable novel targets for therapeutic intervention. In this review, we discuss the involvement of inflammation in the pathogenesis of SLE, with a focus on IL-1 family and IL-10 family cytokines, and highlight pathophysiological approaches and therapeutic potential for treating SLE.

Regulation of B Cell Responses in SLE by Three Classes of Interferons

There are three classes of interferons (type 1, 2, and 3) that can contribute to the development and maintenance of various autoimmune diseases, including systemic lupus erythematosus (SLE). Each class of interferons promotes the generation of autoreactive B cells and SLE-associated autoantibodies by distinct signaling mechanisms. SLE patients treated with various type 1 interferon-blocking biologics have diverse outcomes, suggesting that additional environmental and genetic factors may dictate how these cytokines contribute to the development of autoreactive B cells and SLE. Understanding how each class of interferons controls B cell responses in SLE is necessary for developing optimized B cell- and interferon-targeted therapeutics. In this review, we will discuss how each class of interferons differentially promotes the loss of peripheral B cell tolerance and leads to the development of autoreactive B cells, autoantibodies, and SLE.

Interferon lambda in inflammation and autoimmune rheumatic diseases

Interferons are potent antiviral cytokines that modulate immunity in response to infection or other danger signals. In addition to their antiviral functions, type I interferons (IFNα and IFNβ) are important in the pathogenesis of autoimmune diseases. Type III interferons (IFNλs) were initially described as a specialized system that inhibits viral replication at epithelial barrier surfaces while limiting inflammatory damage. However, evidence now suggests that type III interferons have complex effects on both innate and adaptive immune responses and might also be pathogenic in systemic autoimmune diseases. Concentrations of IFNλs are increased in blood and tissues in a number of autoimmune rheumatic diseases, including systemic lupus erythematosus, and are further associated with specific clinical and laboratory parameters. This Review is aimed at providing a critical evaluation of the current literature on IFNλ biology and how type III interferons might contribute to immune dysregulation and tissue damage in autoimmunity. The potential effects of type III interferons on treatment strategies for autoimmune rheumatic diseases, such as interferon blockade, are also considered.

Characterization of autoantibodies and cytokines related to cutaneous lupus erythematosus

OBJECTIVE

To investigate the profiles of anti-RPLP0, anti-galectin3 antibodies, interferon-α (IFN-α), interferon-λ1(IFN-λ1) and interleukin-17A/F(IL-17A/F) in the subtypes of cutaneous lupus erythematosus (CLE) including acute CLE (ACLE), subacute CLE (SCLE) and discoid lupus erythematosus (DLE).

METHODS

Serum levels of autoantibodies and cytokines were determined by enzyme-linked immunoabsorbent assay (ELISA). Lupus lesions were evaluated by cutaneous lupus erythematosus disease area and severity index (CLASI).

RESULTS

Serum anti-RPLP0, anti-galectin3 antibodies and IFN-λ1 were higher in systemic lupus erythematosus (SLE) patients with skin lesions than those without skin lesions, compared to healthy controls. IFN-α, IL-17A and IL-17F was elevated in all patients regardless of skin lesions. The two antibodies, IFN-α and IL-17A were positively correlated with the CLASI score in all patients with CLE. In addition, serum IL-17A was positively correlated to the CLASI score of ACLE, SCLE and DLE, while anti-RPLP0 and anti-galectin3 antibodies were only correlated to the score of SCLE and IL-17F to DLE.

CONCLUSION

Serum anti-RPLP0, anti-galectin3 antibodies, IFN-α, IFN-λ1 and IL-17A/F are associated with the occurrence of lupus skin lesions regardless of the systemic complications, whereas the profiles of these inflammatory mediators vary with the subtypes of lupus skin lesions.

Impact of IL-34, IFN-α and IFN-λ1 on activity of systemic lupus erythematosus in Egyptian patients

Background

Systemic lupus erythematosus (SLE) is an autoimmune, multi-system inflammatory disease. Among cytokines involved in SLE pathogenesis, interferons (particularly IFN-α) and interleukin 34 play a pivotal role. Interestingly, the gene signatures of type III (IFN-λ1) and type I IFNs may overlap. Increased levels of IFN-λ also have been reported in SLE.

Objectives: The aim of this study was to assess serum levels of IL-34, IFN-λ1, IFN-α and the relationship between these cytokines and clinical and laboratory parameters and response to treatment in a cohort of Egyptian SLE patients.

Material and methods

The study included 82 newly diagnosed SLE patients: male 17.1% (n = 14), female 82.9% (n = 68), mean age ±SD: 48.6 ±8.2 and 60 healthy subjects matched by age and gender as a control group. Medical history, physical examination and laboratory tests for confirming SLE diagnosis and assessment of disease activity were collected. The assessment of serum levels of studied cytokines were performed using the ELISA method.

All studied patients after first cytokine evaluation were treated with a combination of antimalarial drugs, glucocorticosteroids and/or immunosuppressive drugs with follow-up after six months of treatment.

Results

In the SLE group the mean serum levels of IL-34, IFN-α and IFN-λ1 were 175.9 ±125.9 pg/ml, 109.3 ±32.5 pg/ml and 227.9 ±144.8 pg/ml respectively. These cytokine levels were significantly higher in the SLE group than in healthy controls. 39% of SLE patients (n = 32) had SLAM > 6 and 26.8% (n = 22) had SLEDAI >6. There were 21 SLE patients (25.6%) with lupus nephritis.

IL-34 and IFN-λ1 were positively correlated with anti-dsDNA antibodies but negatively correlated with C3 complement component (p ≤ 0.05). IL-34, INF-α and IFN-λ1 were significantly higher in lupus nephritis patients, and correlated with poorest response to treatment.

IL-34 and IFN-λ1 were correlated with higher SLAM > 6 and SLEDAI > 6 results; there was no such correlation between IFN-α and disease activity.

Accumulation of three or more clinical features during follow-up was significantly associated with high levels of studied cytokines. Triple high positivity was found in 17 patients (20.7%) and correlated with presence of anti-dsDNA antibodies, low levels of C3 component of complement and lupus nephritis.

Conclusions

SLE patients with high serum levels of IL-34, IFN-α and IFN-λ1 more often had lupus nephritis and poor response to immunosuppressive treatment.

The triple cytokine elevation was strongly associated with higher disease activity. These results may indicate the need to distinguish this group of patients with such aggressive phenotype and consider targeted multi-therapy.

The regulation and pharmacological modulation of immune complex induced type III IFN production by plasmacytoid dendritic cells

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) have an ongoing interferon (IFN) production due to an activation of plasmacytoid dendritic cells (pDCs), which can be triggered to type I IFN synthesis by RNA containing immune complexes (RNA-IC). Considering emerging data suggesting a role of type III IFN in the SLE disease process, we asked if RNA-IC can induce type III IFN production in pDC and how this production can be regulated.

METHODS

Peripheral blood mononuclear cells (PBMCs) or immune cell subsets were isolated from healthy blood donors or SLE patients and stimulated with IC containing U1 snRNP and SLE-IgG (RNA-IC). Hydroxychloroquine (HCQ) and an interleukin receptor 1-associated kinase 4 inhibitor (IRAK4i) were added to cell cultures. Cytokine mRNA levels were determined with a microarray and protein levels with immunoassays. Single-cell RNA sequencing of pDCs using ddSEQ technology was performed.

RESULTS

Type III IFN mRNA and protein was induced in RNA-IC-stimulated pDC-NK and pDC-B cell co-cultures. A subset of activated pDCs (3%) expressed both type III and type I IFN mRNA. IFN-λ2, IFN-α2b, interleukin (IL)-3, IL-6, or granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced IFN-λ1/3 production 2-5-fold. HCQ and an IRAK4i blocked the RNA-IC-triggered IFN-λ1/3 production (p < 0.01). IFN-α2b and GM-CSF increased the proportion of SLE patients producing IFN-λ1/3 in response to RNA-IC from 11 to 33%.

CONCLUSIONS

Type III IFN production is triggered by RNA-IC in pDCs in a TLR-MyD88-dependent manner, enhanced by NK and B cells as well as several pro-inflammatory cytokines. These results support a contributing role for both type I and type III IFNs in SLE, which needs to be considered when targeting the IFN system in this disease.

The presence of IFL3/4 rs12979860 C allele influences the in vitro IP-10 production by mononuclear cells from patients with systemic lupus erythematosus

OBJECTIVE

To explore whether the IFNL3/4 rs12979860 genotype may influence serum levels or production of interferon-inducible protein-10 (IP-10) by peripheral blood mononuclear cells from patients with systemic lupus erythematosus (SLE).

METHODS

Sixty-six patients with SLE and 22 healthy blood donors (controls) were included. The IFNL3/4 rs12979860 polymorphism was genotyped by real-time polymerase chain reaction. IP-10 levels in sera supernatants of IFNα stimulated peripheral blood mononuclear cells were measured by enzime-linked immunosorbent assay.

RESULTS

Allelic frequencies were CC (29%), CT (52%) and TT (20%) in SLE, and CC (32%), CT (41%) and TT (27%) in healthy controls. Median serum IP-10 levels were higher in SLE patients than in controls (190.8 versus 118.1 pg/ml; p < 0.001), particularly in those with high disease activity (278.5 versus 177.2 pg/ml; p = 0.037). However, serum IP-10 levels were not influenced by IFNL3/4 genotypes. Higher IP-10 production by peripheral blood mononuclear cells was found in both SLE patients (median 519.3 versus 207.6 pg/ml; p = 0.012) and controls (median 454.0 versus 201.7 pg/ml; p = 0.034) carrying the IFNL3/4 C allele compared with carriers of the T allele.

CONCLUSIONS

Although IFNL3/4 rs12979860 allele C does not appear to influence serum IP-10 levels in SLE, it plays an important role in the production of IP-10 by peripheral blood mononuclear cells after IFNα stimulation.

Type III Interferons (Lambda Interferons) in Rheumatic Autoimmune Diseases

The last 2 decades have witnessed the discovery and characterization of a new family of cytokines with immunological characteristics similar to those described for type I interferons, type III or lambda interferons. Unraveling the molecular mechanisms underlying each type of interferon has allowed us to understand how some autoimmune diseases can be considered as interferonopathies. Under normal conditions, type III interferons play a key role in the defense against viruses by modulating the functioning of several types of innate and adaptive immune cells. These effects include upregulation of major histocompatibility complex molecules by myeloid dendritic cells, increased functioning of pattern recognition receptors by plasmacytoid dendritic cells, decreased activity of regulatory T cells, enhanced production of antibodies by plasmatic cells and increased expression of chemokines and adhesion molecules by leukocytes and endothelial cells. Notably, all these mechanisms have been described to boost autoimmunity, and type III interferons pathway activation has been related to the pathogenesis of autoimmune conditions such as systemic lupus erythematosus, systemic sclerosis and Sjögren's syndrome. This review provides an overview of the current evidence on the contribution of type III interferons in the pathogenesis of rheumatic autoimmune diseases in humans.

Independent association of low IFNλ1 gene expression and type I IFN score/IFNλ1 ratio with obstetric manifestations and triple antiphospholipid antibody positivity in primary antiphospholipid syndrome

Recent data suggest an important role of type I interferons (IFN) in antiphospholipid syndrome (APS). Here we aimed to evaluate the interplay of type I and type III (or IFNλs) IFNs in APS and potential clinical and serological associations. Our findings suggest that patients with primary APS (PAPS) and systemic lupus erythematosus (SLE)/APS displayed increased type I IFN scores but decreased IFNλ1 gene expression levels compared to healthy individuals, as assessed with real-time qPCR analysis in isolated peripheral blood mononuclear cells (PBMCs). Type I IFN score/IFNλ1 ratio was remarkably higher in patients with PAPS and SLE/APS as well as in SLE patients with or without antiphospholipid antibodies (aPL) vs controls. In conclusion, our results reveal an association between low IFNλ1 expression and obstetric APS. Moreover, the type I IFN score/IFNλ1 ratio seems to be a potential marker of high risk APS given its associations with triple aPL positivity.

Interferon Lambda and Liver Fibrosis

Fibrosis is a highly conserved and coordinated wound healing response to injury. In the liver, injury is promoted by immune effector mechanisms that are common across various disease etiologies and even between organs such as lungs, kidneys, heart, and other organs. Thus, the liver represents a useful model to study inflammation and repair, particularly as it is frequently biopsied in clinical contexts. Currently, strong evidence implicates IFNL3/4 polymorphisms and interferon (IFN)-λ3 levels as determinants of the extent of hepatic inflammation and fibrosis in viral and nonviral liver diseases, as well as in governing the severity of nonhepatotropic viral diseases. Interestingly, IFNL3/4 polymorphisms and IFN-λ3 levels correlate with fibrosis extent in other organs such as the lung and kidney. In this review, we discuss the association between IFN-λ and tissue inflammation and fibrosis in human disease and the potential clinical utility of the findings.

Signaling Pathways of Type I and Type III Interferons and Targeted Therapies in Systemic Lupus Erythematosus

Type I and type III interferons (IFNs) share several properties in common, including the induction of signaling pathways, the activation of gene transcripts, and immune responses, against viral infection. Recent advances in the understanding of the molecular basis of innate and adaptive immunity have led to the re-examination of the role of these IFNs in autoimmune diseases. To date, a variety of IFN-regulated genes, termed IFN signature genes, have been identified. The expressions of these genes significantly increase in systemic lupus erythematosus (SLE), highlighting the role of type I and type III IFNs in the pathogenesis of SLE. In this review, we first discussed the signaling pathways and the immunoregulatory roles of type I and type III IFNs. Next, we discussed the roles of these IFNs in the pathogenesis of autoimmune diseases, including SLE. In SLE, IFN-stimulated genes induced by IFN signaling contribute to a positive feedback loop of autoimmunity, resulting in perpetual autoimmune inflammation. Based on this, we discussed the use of several specific IFN blocking strategies using anti-IFN-α antibodies, anti-IFN-α receptor antibodies, and IFN-α-kinoid or downstream small molecules, which intervene in Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathways, in clinical trials for SLE patients. Hopefully, the development of novel regimens targeting IFN signaling pathways will shed light on promising future therapeutic applications for SLE patients.

Photosensitivity and type I IFN responses in cutaneous lupus are driven by epidermal-derived interferon kappa

OBJECTIVE

Skin inflammation and photosensitivity are common in patients with cutaneous lupus erythematosus (CLE) and systemic lupus erythematosus (SLE), yet little is known about the mechanisms that regulate these traits. Here we investigate the role of interferon kappa (IFN-κ) in regulation of type I interferon (IFN) and photosensitive responses and examine its dysregulation in lupus skin.

METHODS

mRNA expression of type I IFN genes was analysed from microarray data of CLE lesions and healthy control skin. Similar expression in cultured primary keratinocytes, fibroblasts and endothelial cells was analysed via RNA-seq. IFNK knock-out (KO) keratinocytes were generated using CRISPR/Cas9. Keratinocytes stably overexpressing IFN-κ were created via G418 selection of transfected cells. IFN responses were assessed via phosphorylation of STAT1 and STAT2 and qRT-PCR for IFN-regulated genes. Ultraviolet B-mediated apoptosis was analysed via TUNEL staining. In vivo protein expression was assessed via immunofluorescent staining of normal and CLE lesional skin.

RESULTS

IFNK is one of two type I IFNs significantly increased (1.5-fold change, false discovery rate (FDR) q<0.001) in lesional CLE skin. Gene ontology (GO) analysis showed that type I IFN responses were enriched (FDR=6.8×10-04) in keratinocytes not in fibroblast and endothelial cells, and this epithelial-derived IFN-κ is responsible for maintaining baseline type I IFN responses in healthy skin. Increased levels of IFN-κ, such as seen in SLE, amplify and accelerate responsiveness of epithelia to IFN-α and increase keratinocyte sensitivity to UV irradiation. Notably, KO of IFN-κ or inhibition of IFN signalling with baricitinib abrogates UVB-induced apoptosis.

CONCLUSION

Collectively, our data identify IFN-κ as a critical IFN in CLE pathology via promotion of enhanced IFN responses and photosensitivity. IFN-κ is a potential novel target for UVB prophylaxis and CLE-directed therapy.

Interferon-λ3/4 genetic variants and interferon-λ3 serum levels are biomarkers of lupus nephritis and disease activity in Taiwanese

BACKGROUND

Type III interferons (IFNs) or IFN-λs are the newly discovered cytokines that primarily target the cells of epithelial and myeloid lineages, which are major components of kidneys. The current study aimed to investigate whether IFN-λs are involved in the pathogenesis of systemic lupus erythematosus (SLE) and lupus nephritis.

METHODS

TaqMan allele discrimination assays were used to determine IFNL3/4 SNP genotypes of 1620 healthy controls and 1013 SLE patients (two independent cohorts consisting of 831 and 182 subjects, respectively) from Taiwan. The distributions of IFNL3/4 SNP genotypes and allele frequencies were compared between SLE patients and healthy controls and among SLE patients stratified by clinical phenotypes. ELISA was used to determine the serum IFN-λ3 concentrations of SLE patients.

RESULTS

All major IFN3/4 SNP alleles were significantly associated with the risk for lupus nephritis (rs8099917T, PFDR = 0.0021, OR 1.75, 95% CI 1.24-2.47; rs12979860C, PFDR = 0.0034, OR 1.65, 95% CI 1.18-2.30; rs4803217C, PFDR = 0.0021, OR 1.76, 95% CI 1.25-2.48; and ss469415590TT, PFDR = 0.0021, OR 1.73, 95% CI 1.23-2.42) among SLE patients. Similarly, the major IFNL3/4 SNP haplotype rs8099917T-ss469415590TT-rs12979860C-rs4803217C (or T-TT-C-C) was a significant risk factor for lupus nephritis (P = 0.0015, OR 1.68, 95% CI 1.22-2.32). Additionally, all minor IFN3/4 SNP alleles were significantly associated with SLE susceptibility in nephritis-negative SLE patients as compared to normal healthy controls (rs8099917G, PFDR = 0.00177, OR 1.68, 95% CI 1.24-2.28; rs12979860T, PFDR = 0.00299, OR 1.58, 95% CI 1.18-2.32; rs4803217A, PFDR = 0.00176, OR 1.65, 95% CI 1.22-2.23; and ss469415590ΔG, PFDR = 0.00176, OR 1.70, 95% CI 1.26-2.29). Furthermore, the elevated serum levels of IFN-λ3 were significantly correlated with the complement depression and the high SLE disease activities in SLE patients.

CONCLUSIONS

IFN-λ3/4 genetic variants play a unique role in the development of lupus nephritis and SLE.