A pathogenic IFNα, BLyS and IL-17 axis in Systemic Lupus Erythematosus patients

Causal associations between both psoriasis and psoriatic arthritis and multiple autoimmune diseases: a bidirectional two-sample Mendelian randomization study

Background

Numerous observational studies have identified associations between both psoriasis (PsO) and psoriatic arthritis (PsA), and autoimmune diseases (AIDs); however, the causality of these associations remains undetermined.

Methods

We conducted a bidirectional two-sample Mendelian Randomization study to identify causal associations and directions between both PsO and PsA and AIDs, such as systemic lupus erythematosus (SLE), Crohn's disease (CD), ulcerative colitis (UC), multiple sclerosis (MS), uveitis, bullous pemphigoid (BP), Hashimoto's thyroiditis (HT), rheumatoid arthritis (RA), vitiligo, and ankylosing spondylitis (AS). The causal inferences were drawn by integrating results from four regression models: Inverse Variance Weighting (IVW), MR-Egger, Weighted Median, and Maximum Likelihood. Furthermore, we performed sensitivity analyses to confirm the reliability of our findings.

Results

The results showed that CD [IVW odds ratio (ORIVW), 1.11; 95% confidence interval (CI), 1.06-1.17; P = 8.40E-06], vitiligo (ORIVW, 1.16; 95% CI, 1.05-1.28; P = 2.45E-03) were risk factors for PsO, while BP may reduce the incidence of PsO (ORIVW, 0.91; 95% CI, 0.87-0.96; P = 1.26E-04). CD (ORIVW, 1.07; 95% CI, 1.02-1.12; P = 0.01), HT (ORIVW, 1.23; 95% CI, 1.08-1.40; P = 1.43E-03), RA (ORIVW, 1.11; 95% CI, 1.02-1.21, P = 2.05E-02), AS (ORIVW, 2.18; 95% CI, 1.46-3.27; P = 1.55E-04), SLE (ORIVW, 1.04; 95% CI, 1.01-1.08; P = 1.07E-02) and vitiligo (ORIVW, 1.27; 95% CI, 1.14-1.42; P = 2.67E-05) were risk factors for PsA. Sensitivity analyses had validated the reliability of the results.

Conclusions

Our study provides evidence for potential causal relationships between certain AIDs and both PsO and PsA. Specifically, CD and vitiligo may increase the risk of developing PsO, while CD, HT, SLE, RA, AS, and vitiligo may elevate the risk for PsA. Additionally, it is crucial to closely monitor the condition of PsO patients with specific AIDs, as they have a higher likelihood of developing PsA than those without AIDs. Moving forward, greater attention should be paid to PsA and further exploration of other PsO subtypes is warranted.

Toll-like Receptor Homologue CD180 Ligation of B Cells Upregulates Type I IFN Signature in Diffuse Cutaneous Systemic Sclerosis

Type I interferon (IFN-I) signaling has been shown to be upregulated in systemic sclerosis (SSc). Dysregulated B-cell functions, including antigen presentation, as well as antibody and cytokine production, all of which may be affected by IFN-I signaling, play an important role in the pathogenesis of the disease. We investigated the IFN-I signature in 71 patients with the more severe form of the disease, diffuse cutaneous SSc (dcSSc), and 33 healthy controls (HCs). Activation via Toll-like receptors (TLRs) can influence the IFN-I signaling cascade; thus, we analyzed the effects of the TLR homologue CD180 ligation on the IFN-I signature in B cells. CD180 stimulation augmented the phosphorylation of signal transducer and activator of transcription 1 (STAT1) in dcSSc B cells (p = 0.0123). The expression of IFN-I receptor (IFNAR1) in non-switched memory B cells producing natural autoantibodies was elevated in dcSSc (p = 0.0109), which was enhanced following anti-CD180 antibody treatment (p = 0.0125). Autoantibodies to IFN-Is (IFN-alpha and omega) correlated (dcSSc p = 0.0003, HC p = 0.0192) and were present at similar levels in B cells from dcSSc and HC, suggesting their regulatory role as natural autoantibodies. It can be concluded that factors other than IFN-alpha may contribute to the elevated IFN-I signature of dcSSc B cells, and one possible candidate is B-cell activation via CD180.

IFN-α affects Th17/Treg cell balance through c-Maf and associated with the progression of EBV- SLE

OBJECTIVES

Systemic lupus erythematosus (SLE) is a multi-organ autoimmune disease, of which the pathogens is remains obscure. Viral infection, particularly Epstein Barr viru (EBV) infection, has been considered a common pathogenic factor. This study suggests that c-Maf may be an important target in T cell differentiation during SLE progression, providing a potentially new perspective on the role of viral infection in the pathogenesis of autoimmune diseases.

METHODS

Cytokines of EBV-infected SLE patients were measured by ELISA and assessed in conjunction with their clinical data. IFN-α, c-Maf, and the differentiation of Th17/Treg cells in SLE patients and MRL/LPR mice were analyzed using FCM, WB, RT-PCR, etc. Following the infection of cells and mice with EBV or viral mimic poly (dA:dT), the changes of the aforementioned indicators were investigated. The relationship among IFN-α, STAT3, c-Maf and Th17 cells was determined by si-RNA technique.

RESULTS

Many SLE patients are found to be complicated by viral infections; Further, studies have demonstrated that viral infection, especially EBV, is involved in SLE development. This study showed that viral infections might promote IFN-α secretion, inhibit c-Maf expression by activating STAT3, increase Th17 cell differentiation, and lead to the immune imbalance of Th17/Treg cells, thus playing a role in the onset and progression of SLE.

CONCLUSION

This study demonstrates that EBV infections may contribute to SLE development by activating STAT3 through IFN-α, inhibiting c-Maf, and causing Th17/Treg immune imbalance. Our work provided a new insight into the pathogenesis and treatment of SLE.

Systemic lupus erythematosus therapeutic strategy: From immunotherapy to gut microbiota modulation

Systemic lupus erythematosus (SLE) is characterized by a systemic dysfunction of the innate and adaptive immune systems, leading to an attack on healthy tissues of the body. During the development of SLE, pathogenic features, such as the formation of autoantibodies to self-nuclear antigens, caused tissue damage including necrosis and fibrosis, with an increased expression of type Ⅰ interferon (IFN) regulated genes. Treatment of lupus with immunosuppressants and glucocorticoids, which are used as the standard therapy, is not effective enough and causes side effects. As an alternative, more effective immunotherapies have been developed, including monoclonal and bispecific antibodies that target B cells, T cells, co-stimulatory molecules, cytokines or their receptors, and signaling molecules. Encouraging results have been observed in clinical trials with some of these therapies. Furthermore, a chimeric antigen receptor T cells (CAR-T) therapy has emerged as the most effective, safe, and promising treatment option for SLE, as demonstrated by successful pilot studies. Additionally, emerging evidence suggests that gut microbiota dysbiosis may play a significant role in the severity of SLE, and the use of methods to normalize the gut microbiota, particularly fecal microbiota transplantation (FMT), opens up new opportunities for effective treatment of SLE.

Noninvasive biomarkers for lupus nephritis

Lupus nephritis (LN) is one of the most severe clinical manifestations of systemic lupus erythematosus (SLE). Notably, the clinical manifestations of LN are not always consistent with the histopathological findings. Therefore, the diagnosis and activity monitoring of this disease are challenging and largely depend on invasive renal biopsy. Renal biopsy has side effects and is associated with the risk of bleeding and infection. There is a growing interest in the development of novel noninvasive biomarkers for LN. In this review, we summarize most of the LN biomarkers discovered so far by correlating current knowledge with future perspectives. These biomarkers fundamentally reflect the biological processes of kidney damage and repair during disease. Furthermore, this review highlights the role of urinary cell phenotype detection in the diagnosis, monitoring, and treatment of LN and summarizes the limitations and countermeasures of this test.

Immunotherapy Strategy for Systemic Autoimmune Diseases: Betting on CAR-T Cells and Antibodies

Systemic autoimmune diseases (SAIDs), such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and rheumatoid arthritis (RA), are fully related to the unregulated innate and adaptive immune systems involved in their pathogenesis. They have similar pathogenic characteristics, including the interferon signature, loss of tolerance to self-nuclear antigens, and enhanced tissue damage like necrosis and fibrosis. Glucocorticoids and immunosuppressants, which have limited specificity and are prone to tolerance, are used as the first-line therapy. A plethora of novel immunotherapies have been developed, including monoclonal and bispecific antibodies, and other biological agents to target cellular and soluble factors involved in disease pathogenesis, such as B cells, co-stimulatory molecules, cytokines or their receptors, and signaling molecules. Many of these have shown encouraging results in clinical trials. CAR-T cell therapy is considered the most promising technique for curing autoimmune diseases, with recent successes in the treatment of SLE and SSc. Here, we overview novel therapeutic approaches based on CAR-T cells and antibodies for targeting systemic autoimmune diseases.

Association of IL-17 serum levels with clinical findings and systemic lupus erythematosus disease activity index

The current study aims to investigate the relationship betweSen serum IL-17 (IL-17) levels and systemic lupus erythematosus disease activity index (SLE-DAEI) in systemic lupus erythematosus (SLE) patients. In this case-control study, 36 patients with SLE and 40 healthy individuals matched for age and sex were included as the control group. The study measured serum IL-17 in both groups. The correlation between serum IL-17 with disease activity (as per SLE-DAI) and organ involvement in SLE patients. The case group in this study consisted of 4 males and 32 females with a mean age of 35 (17-54) years old, and the control group included six males and 34 females with a mean age of 37 (25-53) years old (p = .35). Serum IL-17 was higher in the cases than in the controls (536 pg/mL vs. 110 pg/mL; p < .001). There was a positive correlation between the serum levels of IL-17 and disease activity index (p < .001, rho = 0.93) among cases. Additionally, the serum levels of IL-17 were higher in patients with renal (p = .003) or central nervous system involvement (p < .001) than in patients without such involvement. Serum Il-17 is associated with SLE, and its serum levels correlate positively with the disease activity and renal and nervous system involvement.

Molecular consideration relevant to the mechanism of the comorbidity between psoriasis and systemic lupus erythematosus (Review)

Systemic lupus erythematosus (SLE), a common autoimmune disease with a global incidence and newly diagnosed population estimated at 5.14 (range, 1.4-15.13) per 100,000 person-years and 0.40 million people annually, respectively, affects multiple tissues and organs; for example, skin, blood system, heart and kidneys. Accumulating data has also demonstrated that psoriasis (PS) can be a systemic inflammatory disease, which can affect organs other than the skin and occur alongside other autoimmune diseases, such as inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis and SLE. The current explanations for the possible comorbidity of PS and SLE include: i) The two diseases share susceptible gene loci; ii) they share a common IL-23/T helper 17 (Th17) axis inflammatory pathway; and iii) the immunopathogenesis of the two conditions is a consequence of the interactions between IL-17 cytokines with effector Th17 cells, T regulatory cells, as well as B cells. In addition, the therapeutic efficacy of IL-17 or TNF-α inhibitors has been demonstrated in PS, and has also become evident in SLE. However, the mechanisms have not been investigated. To the best of our knowledge, there remains a lack of substantial studies on the correlation between PS and SLE. In the present review, the literature, with regards to the epidemiology, genetic predisposition, inflammatory mechanisms and treatment of the patients with both PS and SLE, has been reviewed. Further investigations into the molecular pathogenic mechanism may provide drug targets that could benefit the patients with concomitant PS and SLE.

Cytokines in Systemic Lupus Erythematosus-Focus on TNF-α and IL-17

Systemic lupus erythematosus (SLE) is an autoimmune disorder known for its complex pathogenesis, in which cytokines play an essential role. It seems that the modulation of these cytokines may impact disease progression, being considered potential biomarkers. Thus, TNF (tumor necrosis factor)-α and IL (interleukin)-17 are molecules of great interest in SLE. TNF-α plays a dual role in SLE, with both immunosuppressive and proinflammatory functions. The role of IL-17 is clearly described in the pathogenesis of SLE, having a close association with IL-23 in stimulating the inflammatory response and consecutive tissue destruction. It appears that patients with elevated levels of these cytokines are associated with high disease activity expressed by the SLE disease activity index (SLEDAI) score, although some studies do not confirm this association. However, TNF-α and IL-17 are found in increased titers in lupus patients compared to the general population. Whether inhibition of these cytokines would lead to effective treatment is under discussion. In the case of anti-TNF-α therapies in SLE, the possibility of ATIL (anti-TNF-induced lupus) is a serious concern that limits their use. The use of anti-IL-17 therapies in SLE is a promising option, but not yet approved. Future studies of these cytokines in large cohorts will provide valuable information for the management of SLE.

Advances in the Pathogenesis and Treatment of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a genetically predisposed, female-predominant disease, characterized by multiple organ damage, that in its most severe forms can be life-threatening. The pathogenesis of SLE is complex and involves cells of both innate and adaptive immunity. The distinguishing feature of SLE is the production of autoantibodies, with the formation of immune complexes that precipitate at the vascular level, causing organ damage. Although progress in understanding the pathogenesis of SLE has been slower than in other rheumatic diseases, new knowledge has recently led to the development of effective targeted therapies, that hold out hope for personalized therapy. However, the new drugs available to date are still an adjunct to conventional therapy, which is known to be toxic in the short and long term. The purpose of this review is to summarize recent advances in understanding the pathogenesis of the disease and discuss the results obtained from the use of new targeted drugs, with a look at future therapies that may be used in the absence of the current standard of care or may even cure this serious systemic autoimmune disease.

The star target in SLE: IL-17

PURPOSE

The purpose of this review is to discuss the significance of IL-17 in SLE and the potential of IL-17-targeted therapy.

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect many organs and tissues throughout the body. It is characterized by overactive B and T cells and loss of immune tolerance to autoantigens. Interleukin-17 (IL-17) is a cytokine that promotes inflammation and has been implicated in the pathogenesis of several autoimmune diseases as well as inflammatory diseases. In in vitro cellular experiments in lupus susceptible mice or SLE patients, there is substantial evidence that IL-17 is a highly promising therapeutic target.

METHODS

We searched papers from PubMed database using the search terms, such as interleukin-17, systemic lupus erythematosus, treatment targets, T cells, lupus nephritis, and other relevant terms.

RESULTS

We discuss in this paper the molecular mechanisms of IL-17 expression, Th17 cell proliferation, and the relationship between IL-17 and Th17. The significance of IL-17 in SLE and the potential of IL-17-targeted therapy are further discussed in detail.

CONCLUSION

IL-17 has a very high potential for the development as a star target in SLE.

SARS-CoV-2 vaccine-triggered conversion from systemic lupus erythematosus (SLE) to bullous SLE and dipeptidyl peptidase 4 inhibitors-associated bullous pemphigoid

Bullous systemic lupus erythematosus (BSLE) is a rare blistering disease in patients with SLE. BSLE is a heterogenous disease caused by autoantibodies to the basement membrane, mainly type VII collagen. The pathogenesis of the development of autoantibodies in BSLE remains unknown. We report a case of SLE taking dipeptidyl peptidase 4 inhibitors (DPP4i) who developed tense blister lesions after administration of SARS-CoV-2 vaccine. Initial erythematous lesion before administration of SARS-CoV-2 vaccine had not shown IgG deposition at basement membrane both direct and indirect immunofluorescence (IIF). However, the result of those examinations became positive after the administration of SARS-CoV-2 vaccine. Furthermore, IIF test results using NaCl split skin had shown positive against epidermal side. These observations suggest that SARS-CoV-2 vaccination triggered production of autoantibodies that cause bullous SLE. The present case fulfills the diagnostic criteria for both BSLE and DPP4i-associated bullous pemphigoid. Skin lesions were cleared after withdrawal of DPP4i. Therefore, physicians should ask patients who develop blisters after the vaccination whether they are taking DPP4i.

Unraveling the Link between Interferon-α and Systemic Lupus Erythematosus: From the Molecular Mechanisms to Target Therapies

Systemic lupus erythematosus (SLE) is a chronic, systemic autoimmune disease with a wide range of clinical expressions. The kidney is often affected, usually within 5 years of the onset of SLE, and lupus nephropathy (LN) carries a high risk for increased morbidity. The clinical heterogeneity of the disease is accompanied by complex disturbances affecting the immune system with inflammation and tissue damage due to loss of tolerance to nuclear antigens and the deposition of immune complexes in tissues. Several studies have reported that in human SLE, there is an important role of the Type-I-interferons (INF) system suggested by the upregulation of INF-inducible genes observed in serial gene expression microarray studies. This review aims to describe the transduction pathways of Type-I-interferons, in particular INFα, and its immune-regulatory function in the pathogenesis of SLE and, in particular, in LN. In addition, recent novelties concerning biologic therapy in LN will be discussed.

Antiviral Innate Immune Responses in Autoimmunity: Receptors, Pathways, and Therapeutic Targeting

Innate immune receptors sense nucleic acids derived from viral pathogens or self-constituents and initiate an immune response, which involves, among other things, the secretion of cytokines including interferon (IFN) and the activation of IFN-stimulated genes (ISGs). This robust and well-coordinated immune response is mediated by the innate immune cells and is critical to preserving and restoring homeostasis. Like an antiviral response, during an autoimmune disease, aberrations of immune tolerance promote inflammatory responses to self-components, such as nucleic acids and immune complexes (ICs), leading to the secretion of cytokines, inflammation, and tissue damage. The aberrant immune response within the inflammatory milieu of the autoimmune diseases may lead to defective viral responses, predispose to autoimmunity, or precipitate a flare of an existing autoimmune disease. Herein, we review the literature on the crosstalk between innate antiviral immune responses and autoimmune responses and discuss the pitfalls and challenges regarding the therapeutic targeting of the mechanisms involved.

Arthritis in Systemic Lupus Erythematosus: From 2022 International GISEA/OEG Symposium

Musculoskeletal involvement is one of the most common manifestations of systemic lupus erythematosus (SLE), with a negative impact on both quality of life and overall prognosis. SLE arthritis can be classified into three different subtypes, with different prevalence and characteristic biomarkers and MRI findings. Identifying the pathogenetic mechanisms underlying musculoskeletal manifestations’ development is crucial to develop therapeutic strategies to suppress synovial inflammation, prevent erosions and deformities, and improve SLE patients’ quality of life. Hence, here we discuss the main pathogenetic mechanisms and therapeutic approaches of musculoskeletal manifestations of SLE from the 2022 International GISEA/OEG Symposium.

Gut microbiota in systemic lupus erythematosus: A fuse and a solution

Gut commensals help shape and mold host immune system and deeply influence human health. The disease spectrum of mankind that gut microbiome may associate with is ever-growing, but the mechanisms are still enigmas. Characterized by loss of self-tolerance and sustained self-attack, systemic lupus erythematosus (SLE) is labeled with chronic inflammation, production of autoantibodies and multisystem injury, which so far are mostly incurable. Gut microbiota and their metabolites, now known as important environmental triggers of local/systemic immune responses, have been proposed to be involved in SLE development and progression probably through the following mechanisms: translocation beyond their niches; molecular mimicry to cross-activate immune response targeting self-antigens; epitope spreading to expand autoantibodies spectrum; and bystander activation to promote systemic inflammation. Gut microbiota which varies between individuals may also influence the metabolism and bio-transformation of disease-modifying anti-rheumatic drugs, thus associated with the efficacy and toxicity of these drugs, adding another explanation for heterogenic therapeutic responses. Modulation of gut microbiota via diet, probiotics/prebiotics, antibiotics/phages, fecal microbiota transplantation, or helminth to restore immune tolerance and homeostasis is expected to be a promising neoadjuvant therapy for SLE. We reviewed the advances in this territory and discussed the application prospect of modulating gut microbiota in controlling SLE.

Evaluation of Immune Response and Disease Status in Systemic Lupus Erythematosus Patients Following SARS-CoV-2 Vaccination

OBJECTIVE

To evaluate seroreactivity and disease flares after COVID-19 vaccination in a multiethnic/multiracial cohort of patients with systemic lupus erythematosus (SLE).

METHODS

Ninety SLE patients and 20 healthy controls receiving a complete COVID-19 vaccine regimen were included. IgG seroreactivity to the SARS-CoV-2 spike receptor-binding domain (RBD) and SARS-CoV-2 microneutralization were used to evaluate B cell responses; interferon-γ (IFNγ) production was measured by enzyme-linked immunospot (ELISpot) assay in order to assess T cell responses. Disease activity was measured by the hybrid SLE Disease Activity Index (SLEDAI), and flares were identified according to the Safety of Estrogens in Lupus Erythematosus National Assessment-SLEDAI flare index.

RESULTS

Overall, fully vaccinated SLE patients produced significantly lower IgG antibodies against SARS-CoV-2 spike RBD compared to fully vaccinated controls. Twenty-six SLE patients (28.8%) generated an IgG response below that of the lowest control (<100 units/ml). In logistic regression analyses, the use of any immunosuppressant or prednisone and a normal anti-double-stranded DNA antibody level prior to vaccination were associated with decreased vaccine responses. IgG seroreactivity to the SARS-CoV-2 spike RBD strongly correlated with the SARS-CoV-2 microneutralization titers and correlated with antigen-specific IFNγ production determined by ELISpot. In a subset of patients with poor antibody responses, IFNγ production was similarly diminished. Pre- and postvaccination SLEDAI scores were similar in both groups. Postvaccination flares occurred in 11.4% of patients; 1.3% of these were severe.

CONCLUSION

In a multiethnic/multiracial study of SLE patients, 29% had a low response to the COVID-19 vaccine which was associated with receiving immunosuppressive therapy. Reassuringly, severe disease flares were rare. While minimal protective levels remain unknown, these data suggest that protocol development is needed to assess the efficacy of booster vaccination.

Polymorphonuclear Neutrophils in Rheumatoid Arthritis and Systemic Lupus Erythematosus: More Complicated Than Anticipated

Polymorphonuclear neutrophils (PMN) are the most abundant leucocytes in the circulation in humans. They represent a heterogeneous population exerting diverse functions through several activities. Usually described as typical pro-inflammatory cells, immunomodulatory properties of PMNs have been reported. Among others, once activated and depending on the stimulus, PMNs expel neutrophil extracellular traps (NET) in the extracellular space. NETs are complexes made of DNA and granule proteins representing an innate immune mechanism fighting infections. Nevertheless, an excess of NET formation might be involved in the development of inflammatory or autoimmune responses. Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are two chronic, inflammatory, autoimmune diseases of unknown etiology and affecting mostly women. Several abnormal or non-classical functions of PMNs or PMN sub-populations have been described in SLE and RA. Particularly, NETs have been suggested to trigger pro-inflammatory responses by exposing pro-inflammatory mediators. Likewise, NETs may be the targets of autoantibodies or even might trigger the development of autoantibodies by exposing autoantigens. In the present review, we will summarize heterogeneous properties of human PMNs and we will discuss recent evidence linking PMNs and NETs to the pathogenesis of both SLE and RA.

Current Evidence for IL-17/23 Blockade for the Treatment of Lupus Nephritis

In the current medical literature, there is increasing evidence for the involvement of the interleukin (IL)-17/23 axis and the potential role of Th17 cells in the pathogenesis of lupus nephritis. Knowledge about the interaction of these immunological pathways in the development of autoimmune diseases has led to the identification of new therapeutic strategies aimed at blocking them. For this reason, the main objective of this review focuses on knowing the recent evidence of the different anti-IL-17/23 treatment strategies in lupus nephritis and their future perspectives. A non-systematic narrative review of the literature was carried out following the objective of having the most representative information on the different anti-IL-17/23 drugs available together with the description of the pathophysiological mechanisms of this pathway involved in systemic lupus erythematosus and lupus nephritis. Despite the great existing theoretical foundation, today few clinical studies support the use of these therapies in both contexts. Nevertheless, the publication of research with a better methodology is expected to approve the indication of some of these drugs in lupus nephritis. However, the clinical response seen with ustekinumab and secukinumab in clinical studies and case reports published to date has been encouraging.

Increased IL-23R+ Th Cells Population Exhibits Higher SLEDAI-2K Scores in Systemic Lupus Erythematosus Patients

The IL-23/IL-17 axis plays causative roles in the development and progression of systemic lupus erythematosus (SLE). However, it remains unclear if the IL-17RA⁺ and IL-23R⁺ T helper (Th) cells populations are associated with the serum IL-17 and IL-23 levels, or with the immunological parameters and disease activities in SLE patients. Herein, we examined the proportion of IL-17RA⁺ and IL-23R⁺ Th cells and serum levels of IL-17 and IL-23 in established SLE patients (n = 50) compared with healthy controls (n = 50). The associations of these interleukins and their receptors with immunological parameters [anti-nuclear antibody (ANA), anti-dsDNA antibody, and C-reactive protein (CRP)] and SLE disease activity (SLEDAI-2K scores) in SLE patients were assessed. CD3⁺CD4⁺ Th cells of SLE patients demonstrated significantly elevated IL-17RA⁺ (p = 1.12 x 10^-4) or IL-23R⁺ (p = 1.98 x 10^-29) populations compared with the healthy controls. Serum IL-17 levels were significantly lower in SLE patients compared with the healthy controls (p = 8.32 x 10^-5), while no significant difference was observed for the IL-23 serum levels between both groups. IL-23R⁺ Th cells population was significantly associated with higher SLEDAI-2K scores (p = 0.017). In multivariate analysis, the proportion of IL-23R⁺ Th cells remained significantly associated with higher SLEDAI-2K scores independent of prednisolone intake (p = 0.027). No associations were observed between the interleukin parameters (i.e., IL-17, IL-23, IL-17RA⁺ Th cells, and IL-23R⁺ Th cells) with ANA, anti-dsDNA, and CRP status, suggesting that the IL-17/IL-23 axis acts independently of these immunological parameters. In conclusion, our results support that therapeutic inhibition of the IL-23/IL-17 axis receptors on Th cells, particularly IL-23R, is potentially relevant in SLE patients.

The Th17/IL-17 Axis and Kidney Diseases, With Focus on Lupus Nephritis

Systemic lupus erythematosus (SLE) is a disease characterized by dysregulation and hyperreactivity of the immune response at various levels, including hyperactivation of effector cell subtypes, autoantibodies production, immune complex formation, and deposition in tissues. The consequences of hyperreactivity to the self are systemic and local inflammation and tissue damage in multiple organs. Lupus nephritis (LN) is one of the most worrying manifestations of SLE, and most patients have this involvement at some point in the course of the disease. Among the effector cells involved, the Th17, a subtype of T helper cells (CD4+), has shown significant hyperactivation and participates in kidney damage and many other organs. Th17 cells have IL-17A and IL-17F as main cytokines with receptors expressed in most renal cells, being involved in the activation of many proinflammatory and profibrotic pathways. The Th17/IL-17 axis promotes and maintains repetitive tissue damage and maladaptive repair; leading to fibrosis, loss of organ architecture and function. In the podocytes, the Th17/IL-17 axis effects include changes of the cytoskeleton with increased motility, decreased expression of health proteins, increased oxidative stress, and activation of the inflammasome and caspases resulting in podocytes apoptosis. In renal tubular epithelial cells, the Th17/IL-17 axis promotes the activation of profibrotic pathways such as increased TGF-β expression and epithelial-mesenchymal transition (EMT) with consequent increase of extracellular matrix proteins. In addition, the IL-17 promotes a proinflammatory environment by stimulating the synthesis of inflammatory cytokines by intrinsic renal cells and immune cells, and the synthesis of growth factors and chemokines, which together result in granulopoiesis/myelopoiesis, and further recruitment of immune cells to the kidney. The purpose of this work is to present the prognostic and immunopathologic role of the Th17/IL-17 axis in Kidney diseases, with a special focus on LN, including its exploration as a potential immunotherapeutic target in this complication.

T Cells in Systemic Lupus Erythematosus

T-cell dysregulation has been implicated in the loss of tolerance and overactivation of B cells in systemic lupus erythematosus (SLE). Recent studies have identified T-cell subsets and genetic, epigenetic, and environmental factors that contribute to pathogenic T-cell differentiation, as well as disease pathogenesis and clinical phenotypes in SLE. Many therapeutics targeting T-cell pathways are under development, and although many have not progressed in clinical trials, the recent approval of the calcineurin inhibitor voclosporin is encouraging. Further study of T-cell subsets and biomarkers of T-cell action may pave the way for specific targeting of pathogenic T-cell populations in SLE.

Change of serum B-cell activating factor level in patients with positive antiphospholipid antibodies and previous adverse pregnancy outcomes and its significance

Background:

B-cell activating factor (BAFF) is vital for B cell survival. Serum BAFF levels are elevated in thrombotic antiphospholipid syndrome, but little is known about levels in patients with positive antiphospholipid antibodies (aPLs) and previous adverse pregnancy outcomes (APOs). We aimed to analyze serum BAFF concentrations of these patients in early pregnancy along with different pregnancy outcomes.

Methods:

Thirty-six pregnant patients positive for aPLs and previous APOs (patient group), 25 healthy pregnant females (HP group) and 35 healthy non-pregnant females (HNP group) from the Peking University Third Hospital, between October 2018 and March 2019, were enrolled in this study. Serum of HNP and serum of patients as well as HP in the first gestational trimester were collected. Enzyme-linked immunosorbent assay kits were used to measure serum BAFF and interferon-alpha (IFN-α) concentrations. Cytometric bead array analysis was used to measure serum concentrations of cytokines. The patient group was further divided into APOs and non-APOs (NAPOs) group, fetal loss and live birth group according to pregnancy outcomes. The Mann-Whitney U-test was used to assess significance between and within groups. Spearman rank-order was used to evaluate correlation coefficients between BAFF and related cytokines.

Results:

The serum BAFF level in HP group was significantly lower than HNP group (245.24 [218.80, 265.90] vs. 326.94 [267.31, 414.80] pg/mL, Z = −3.966, P < 0.001). The BAFF level was obviously elevated in patient group compared to that in HP group (307.77 [219.86, 415.65] vs. 245.24 [218.80, 265.90] pg/mL, Z = −2.464, P = 0.013). BAFF levels in APOs group tended to be higher than that in NAPOs group (416.52 [307.07, 511.12] vs. 259.37 [203.59, 375.81] pg/mL, Z = −2.718, P = 0.006). Compared to HP group, concentrations of IFN-α, interleukin (IL-6) and tumor necrosis factor were higher in patient group (33.37 [18.85, 48.12] vs. 13.10 [6.85, 25.47] pg/mL, Z = −2.023, P = 0.043; 39.16 [4.41, 195.87] vs. 3.37 [2.92, 3.90] pg/mL, Z = −3.650, P < 0.001; 8.23 [2.27, 64.46] vs. 1.53 [1.25, 2.31] pg/mL, Z = −3.604, P < 0.001, respectively). Serum BAFF levels had a positive correlation with the concentrations of both IL-6 and IL-10 (IL-6: r = 0.525, P = 0.002; IL-10: r = 0.438, P = 0.012).

Conclusions:

Serum BAFF levels are increased in patients with positive aPLs and previous APOs as compared to healthy pregnant females and tend to be higher in individuals with current APOs. The BAFF levels have a positive correlation with serum IL-6 and IL-10.

Acute skin exposure to ultraviolet light triggers neutrophil-mediated kidney inflammation

Photosensitivity to ultraviolet (UV) light affects up to ∼80% of lupus patients. Sunlight exposure can exacerbate local as well as systemic manifestations of lupus, including nephritis, by mechanisms that are poorly understood. Here, we report that acute skin exposure to UV light triggers a neutrophil-dependent injury response in the kidney characterized by upregulated expression of endothelial adhesion molecules as well as inflammatory and injury markers associated with transient proteinuria. We showed that UV light stimulates neutrophil migration not only to the skin but also to the kidney in an IL-17A-dependent manner. Using a photoactivatable lineage tracing approach, we observed that a subset of neutrophils found in the kidney had transited through UV light-exposed skin, suggesting reverse transmigration. Besides being required for the renal induction of genes encoding mediators of inflammation (vcam-1, s100A9, and Il-1b) and injury (lipocalin-2 and kim-1), neutrophils significantly contributed to the kidney type I interferon signature triggered by UV light. Together, these findings demonstrate that neutrophils mediate subclinical renal inflammation and injury following skin exposure to UV light. Of interest, patients with lupus have subpopulations of blood neutrophils and low-density granulocytes with similar phenotypes to reverse transmigrating neutrophils observed in the mice post-UV exposure, suggesting that these cells could have transmigrated from inflamed tissue, such as the skin.

Current Insights and Future Prospects for Targeting IL-17 to Treat Patients With Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune cell abnormalities which lead to the production of autoantibodies and the deposition of immune complexes. Interleukin (IL)-17-producing cells play an important role in the pathogenesis of the disease, making them an attractive therapeutic target. Studies in lupus-prone mice and of ex vivo cells from patients with SLE humans have shown that IL-17 represents a promising therapeutic target. Here we review molecular mechanisms involved in IL-17 production and Th17 cell differentiation and function and an update on the role of IL-17 in autoimmune diseases and the expected usefulness for targeting IL-17 therapeutically.

Bite of the wolf: innate immune responses propagate autoimmunity in lupus

The etiopathogenesis of systemic lupus erythematosus (SLE), a clinically heterogeneous multisystemic syndrome that derives its name from the initial characterization of facial lesions that resemble the bite of a wolf, is considered a complex, multifactorial interplay between underlying genetic susceptibility factors and the environment. Prominent pathogenic factors include the induction of aberrant cell death pathways coupled with defective cell death clearance mechanisms that promote excessive externalization of modified cellular and nuclear debris with subsequent loss of tolerance to a wide variety of autoantigens and innate and adaptive immune dysregulation. While abnormalities in adaptive immunity are well recognized and are key to the pathogenesis of SLE, recent findings have emphasized fundamental roles of the innate immune system in the initiation and propagation of autoimmunity and the development of organ damage in this disease. This Review focuses on recent discoveries regarding the role of components of the innate immune system, specifically neutrophils and interferons, in promoting various aspects of lupus pathogenesis, with potential implications for novel therapeutic strategies.

Calcineurin and Systemic Lupus Erythematosus: The Rationale for Using Calcineurin Inhibitors in the Treatment of Lupus Nephritis

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a broad spectrum of clinical presentations that can affect almost all organ systems. Lupus nephritis (LN) is a severe complication that affects approximately half of the systemic erythematosus lupus (SLE) patients, which significantly increases the morbidity and the mortality risk. LN is characterized by the accumulation of immune complexes, ultimately leading to renal failure. Aberrant activation of T cells plays a critical role in the pathogenesis of both SLE and LN and is involved in the production of inflammatory cytokines, the recruitment of inflammatory cells to the affected tissues and the co-stimulation of B cells. Calcineurin is a serine-threonine phosphatase that, as a consequence of the T cell hyperactivation, induces the production of inflammatory mediators. Moreover, calcineurin is also involved in the alterations of the podocyte phenotype, which contribute to proteinuria and kidney damage observed in LN patients. Therefore, calcineurin inhibitors have been postulated as a potential treatment strategy in LN, since they reduce T cell activation and promote podocyte cytoskeleton stabilization, both being key aspects in the development of LN. Here, we review the role of calcineurin in SLE and the latest findings about calcineurin inhibitors and their mechanisms of action in the treatment of LN.

Relationship Between T-Cell Exosomes and Cellular Subsets in SLE According to Type I IFN-Signaling

Objective: To quantify the levels of circulating exosomes derived from T-cells and monocytes and their possible associations with leukocyte subpopulations and cytokine milieu in Systemic Lupus Erythematosus (SLE).

Methods: Total circulating exosomes (CD9⁺-Ex) and those derived from T-cells (CD3⁺-Ex) and monocytes (CD14⁺-Ex) were quantified by flow cytometry in 82 SLE patients and 32 controls. Leukocyte subsets and serum cytokines were analyzed by flow cytometry or by immunoassays. IFN-score was evaluated by real time RT-PCR in whole blood samples from a subgroup of 73 patients and 24 controls.

Results: Activation markers (IFNR1 and BLyS) on monocytes, neutrophils and B-cells correlated inversely with circulating exosomes (CD9⁺-Ex, CD3⁺-Ex, and CD14⁺-Ex) in controls but directly with CD3⁺-Ex in patients (all p < 0.05). Although CD9⁺-Ex were increased in SLE, no differences were found in CD3⁺-Ex, supporting that exosome content accounts for this opposite role. Interestingly, CD4⁺CD28^null cells correlated with CD3⁺-Ex in patients and controls, and displayed similar associations with leukocyte subsets in both groups. Additionally, CD3⁺-Ex correlated in patients with the expression of CD25 in CD4⁺CD28^null cells. Furthermore, the activated status of this senescent subset was related to IFNα serum levels in controls and to IFN-score in SLE patients. Finally, patients presenting high IFN-score, in addition to elevated CD25⁺CD28^null cells associated with the activation of myeloid cells, displayed higher levels of inflammatory cytokines and chemokines.

Conclusion: Our results support a relationship between T-cell exosomes and cellular subsets in SLE according to type I IFN-signaling, which could amplify chronic immune activation and excessive cytokine/chemokine response.

IFN-I Mediates Dysfunction of Endothelial Progenitor Cells in Atherosclerosis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease including the cardiovascular system. Atherosclerosis is the most common cardiovascular complication of SLE and a significant risk factor for morbidity and mortality. Vascular damage/protection mechanism in SLE patients is out of balance, caused by the cascade reaction among oxidative stress, proinflammatory cytokines, Neutrophil Extracellular Traps, activation of B cells and autoantibodies and abnormal T cells. As a precursor cell repairing vascular endothelium, endothelial progenitor cells (EPCs) belong to the protective mechanism and show the reduced number and impaired function in SLE. However, the pathological mechanism of EPCs dysfunction in SLE remains ill-defined. This paper reviews the latest SLE epidemiology and pathogenesis, discusses the changes in the number and function of EPCs in SLE, expounds the role of EPCs in SLE atherosclerosis, and provides new guidance and theoretical basis for exploring novel targets for SLE treatment.

Quaternary Ammonium Compound Disinfectants Reduce Lupus-Associated Splenomegaly by Targeting Neutrophil Migration and T-Cell Fate

Hypersensitivity reactions and immune dysregulation have been reported with the use of quaternary ammonium compound disinfectants (QACs). We hypothesized that QAC exposure would exacerbate autoimmunity associated with systemic lupus erythematosus (lupus). Surprisingly, however, we found that compared to QAC-free mice, ambient exposure of lupus-prone mice to QACs led to smaller spleens with no change in circulating autoantibodies or the severity of glomerulonephritis. This suggests that QACs may have immunosuppressive effects on lupus. Using a microfluidic device, we showed that ambient exposure to QACs reduced directional migration of bone marrow-derived neutrophils toward an inflammatory chemoattractant ex vivo. Consistent with this, we found decreased infiltration of neutrophils into the spleen. While bone marrow-derived neutrophils appeared to exhibit a pro-inflammatory profile, upregulated expression of PD-L1 was observed on neutrophils that infiltrated the spleen, which in turn interacted with PD-1 on T cells and modulated their fate. Specifically, QAC exposure hindered activation of splenic T cells and increased apoptosis of effector T-cell populations. Collectively, these results suggest that ambient QAC exposure decreases lupus-associated splenomegaly likely through neutrophil-mediated toning of T-cell activation and/or apoptosis. However, our findings also indicate that even ambient exposure could alter immune cell phenotypes, functions, and their fate. Further investigations on how QACs affect immunity under steady-state conditions are warranted.

Blocking IL-17: A Promising Strategy in the Treatment of Systemic Rheumatic Diseases

Systemic rheumatic diseases are a heterogeneous group of autoimmune disorders that affect the connective tissue, characterized by the involvement of multiple organs, leading to disability, organ failure and premature mortality. Despite the advances in recent years, the therapeutic options for these diseases are still limited and some patients do not respond to the current treatments. Interleukin-17 (IL-17) is a cytokine essential in the defense against extracellular bacteria and fungi. Disruption of IL-17 homeostasis has been associated with the development and progression of rheumatic diseases, and the approval of different biological therapies targeting IL-17 for the treatment of psoriatic arthritis (PsA) and ankylosing spondylitis (AS) has highlighted the key role of this cytokine. IL-17 has been also implicated in the pathogenesis of systemic rheumatic diseases, including systemic lupus erythematosus (SLE), Sjögren's syndrome (SS) and systemic sclerosis (SSc). The aim of this review is to summarize and discuss the most recent findings about the pathogenic role of IL-17 in systemic rheumatic and its potential use as a therapeutic option.

Mechanisms and Functions of Mitophagy and Potential Roles in Renal Disease

Mitophagy is an evolutionarily conserved process to selectively remove damaged or unnecessary mitochondria via the autophagic machinery. In this review, we focus on recent advances in the molecular mechanisms of mitophagy and how mitophagy contributes to cellular homeostasis in physiological and pathological contexts. We also briefly review and discuss the crosstalk between mitophagy and renal disease, highlighting its modulation as a potentially effective therapeutic strategy to treat kidney diseases such as acute kidney injury (AKI), diabetic kidney disease (DKD), and lupus nephritis (LN).

Characterization of Type-I IFN subtype autoantibodies and activity in SLE serum and urine

BACKGROUND/OBJECTIVE

Type-I interferons contribute to pathogenesis in systemic lupus erythematosus, including nephritis. Interferons consist of a family of 16 proteins yet are often characterized in patients without knowledge of the specific interferon subtypes involved. Different interferons may function in the kidneys, and other organs, relative to what is often measured in patient blood. Moreover, antibodies to interferons may potentially modulate systemic or organ-specific interferon activity. The aim of this study was to characterize global interferon activity levels and identify autoantibodies to the 12 interferon α subtypes in patient serum and urine.

METHODS

Interferon activity levels in serum and urine were measured using an interferon bioassay. Anti-interferon and anti-cytokine autoantibodies were measured by ELISA. Serum and urine samples were also characterized for their ability to neutralize the biological activity of exogenously added interferons.

RESULTS

Serum interferon activity was increased in 62% of systemic lupus erythematosus patient samples, relative to healthy donor controls, whereas binding interferon α autoantibodies to at least one interferon α subtype were found in 68% of the samples evaluated. High Systemic Lupus Erythematosus Disease Activity Index scores were significantly (p = 0.001) associated with patient samples containing interferon α autoantibodies to three or more interferon α subtypes in their serum. Interferon α autoantibodies that potently block interferon activity were rare (∼5% of samples), but collectively bound to all 12 interferon α subtypes. Urine interferon activity and interferon α autoantibody profiles did not correlate with their serum counterparts, suggesting immune responses in systemic lupus erythematosus kidneys can be distinct from those measured in serum. Analysis of autoantibodies to 15 additional cytokines in serum identified higher frequencies of granulocyte-macrophage colony-stimulating factor and interleukin 17A autoantibodies, suggesting these signaling pathways may potentially contribute, with interferons, to systemic lupus erythematosus pathogenesis.

CONCLUSIONS

The measurement of autoantibodies to multiple interferon subtypes in serum and urine may provide an alternative method for following interferon-mediated systemic lupus erythematosus disease activity. The results suggest autoantibodies might be used for patient monitoring and/or identifying additional cytokine signaling pathways that are functioning in different systemic lupus erythematosus patients.

The epigenetic face of lupus: Focus on antigen-presenting cells

In recent years, epigenetic mechanisms became widely known due to their ability to regulate and maintain physiological processes such as cell growth, development, differentiation and genomic stability. When dysregulated, epigenetic mechanisms, may introduce gene expression changes and disturbance in immune homeostasis leading to autoimmune diseases. Systemic lupus erythematosus (SLE), the most extensively studied autoimmune disorder, has already been correlated with epigenetic modifications, especially in T cells. Since these cell rely on antigen presentation, it may be assumed that erroneous activity of antigen-presenting cells (APCs), culminates in T cell abnormalities. In this review we summarize and discuss the epigenetic modifications in SLE affected APCs, with the focus on dendritic cells (DCs), B cells and monocytes. Unravelling this aspect of SLE pathogenesis, might result in identification of new disease biomarkers and putative therapeutic approaches.

Dysregulation of T Follicular Helper Cells in Lupus

Although multiple and overlapping mechanisms are ultimately responsible for the immunopathology observed in patients with systemic lupus erythematosus, autoreactive Abs secreted by autoreactive plasma cells (PCs) are considered to play a critical role in disease progression and immunopathology. Given that PCs derive from the germinal centers (GC), long-term dysregulated GC reactions are often associated with the development of spontaneous autoantibody responses and immunopathology in systemic lupus erythematosus patients. In this review, we summarize the emerging evidence concerning the roles of T follicular helper cells in regulating pathogenic GC and autoreactive PC responses in lupus.

Interleukin-17 and lupus: enough to be a target? For which patients?

The involvement of the interleukin (IL)-17 axis in many inflammatory and autoimmune diseases is now well established, and this has led to the development of successful targeted therapies. Its role in systemic lupus erythematosus (SLE) is less described, since SLE is characterized by the impairment of many other immune actors. However, results from animal models and patients strongly suggest that IL-17 and its producing cells are involved in SLE pathogenesis. Circulating levels of IL-17 are increased in lupus, and tissue staining shows the presence of IL-17-producing cells in organ lesions. Through different mechanisms, the IL-17 axis promotes autoantibody production, immune complex deposition, complement activation and then tissue damage. There are also many interactions with other immune and non-immune actors, which account for the broad spectrum of clinical manifestations and disease heterogeneity. SLE treatment faces challenges with many disappointing trials and persistent unmet needs. The identification of subsets of SLE patients with an IL-17-driven disease now constitutes the key priority before starting trials. More preclinical studies are needed to improve the selection of the right patients able to respond and tolerate the many inhibitors that are already available.

Neutrophils-Important Communicators in Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are two autoimmune diseases that can occur together or separately. Insights into the pathogenesis have revealed similarities, such as development of autoantibodies targeting subcellular antigens as well as a shared increased risk of cardiovascular morbidity, potentially due to mutual pathologic mechanisms. In this review, we will address the evidence implicating neutrophils in the pathogenesis of these conditions, highlighting their shared features. The neutrophil is the most abundant leukocyte, recognized for its role in infectious and inflammatory diseases, but dysregulation of neutrophil effector functions, including phagocytosis, oxidative burst and formation of neutrophil extracellular traps (NETs) may also contribute to an autoimmune process. The phenotype of neutrophils in SLE and APS differs from neutrophils of healthy individuals, where neutrophils in SLE and APS are activated and prone to aggregate. A specific subset of low-density neutrophils with different function compared to normal-density neutrophils can also be found within the peripheral blood mononuclear cell (PBMC) fraction after density gradient centrifugation of whole blood. Neutrophil phagocytosis is required for regular clearance of cell remnants and nuclear material. Reactive oxygen species (ROS) released by neutrophils during oxidative burst are important for immune suppression and impairment of ROS production is seen in SLE. NETs mediate pathology in both SLE and APS via several mechanisms, including exposure of autoantigens, priming of T-cells and activation of autoreactive B-cells. NETs are also involved in cardiovascular events by forming a pro-thrombotic scaffolding surface. Lastly, neutrophils communicate with other cells by producing cytokines, such as Interferon (IFN) -α, and via direct cell-cell contact. Physiological neutrophil effector functions are necessary to prevent autoimmunity, but in SLE and APS these are altered.

MAP4K Family Kinases and DUSP Family Phosphatases in T-Cell Signaling and Systemic Lupus Erythematosus

T cells play a critical role in the pathogenesis of systemic lupus erythematosus (SLE), which is a severe autoimmune disease. In the past 60 years, only one new therapeutic agent with limited efficacy has been approved for SLE treatment; therefore, the development of early diagnostic biomarkers and therapeutic targets for SLE is desirable. Mitogen-activated protein kinase kinase kinase kinases (MAP4Ks) and dual-specificity phosphatases (DUSPs) are regulators of MAP kinases. Several MAP4Ks and DUSPs are involved in T-cell signaling and autoimmune responses. HPK1 (MAP4K1), DUSP22 (JKAP), and DUSP14 are negative regulators of T-cell activation. Consistently, HPK1 and DUSP22 are downregulated in the T cells of human SLE patients. In contrast, MAP4K3 (GLK) is a positive regulator of T-cell signaling and T-cell-mediated immune responses. MAP4K3 overexpression-induced RORγt–AhR complex specifically controls interleukin 17A (IL-17A) production in T cells, leading to autoimmune responses. Consistently, MAP4K3 and the RORγt–AhR complex are overexpressed in the T cells of human SLE patients, as are DUSP4 and DUSP23. In addition, DUSPs are also involved in either human autoimmune diseases (DUSP2, DUSP7, DUSP10, and DUSP12) or T-cell activation (DUSP1, DUSP5, and DUSP14). In this review, we summarize the MAP4Ks and DUSPs that are potential biomarkers and/or therapeutic targets for SLE.

AhR-ROR-γt complex is a therapeutic target for MAP4K3/GLKhighIL-17Ahigh subpopulation of systemic lupus erythematosus

The cytokine IL-17A plays critical roles in the pathogenesis of autoimmune diseases. The frequencies of MAP kinase kinase kinase kinase 3 [also named germinal center kinase-like kinase (GLK)]-overexpressing T cells are correlated with disease severity of systemic lupus erythematosus (SLE). T-cell-specific GLK-transgenic mice develop spontaneous autoimmune responses through IL-17A. GLK signaling selectively stimulates IL-17A production in murine T cells through inducing aryl hydrocarbon receptor (AhR)-retinoic acid receptor-related orphan nuclear receptor-γt (ROR-γt) complex formation. Here, we investigated whether GLK-induced AhR-ROR-γt complex in T cells is a therapeutic target for human SLE. The population of GLK⁺IL-17A⁺ T cells was enhanced in the peripheral blood from patients with SLE compared with that of healthy controls using flow cytometry. The receiver operating characteristic curve analysis showed that increased GLK⁺IL-17A⁺ T-cell population in peripheral blood reflected an active stage of SLE. In addition, peripheral blood T cells from patients with SLE displayed induction of ROR-γt phosphorylation and the AhR-ROR-γt (and AhR-phosphorylated ROR-γt) complex. Moreover, we identified a small-molecule inhibitor, verteporfin, that inhibited GLK kinase activity and AhR-ROR-γt interaction. The small-molecule inhibitor verteporfin suppressed the disease severity in autoimmune mouse models and IL-17A production in T cells from patients with SLE. Collectively, the GLK-induced AhR-ROR-γt (and AhR-phosphorylated ROR-γt) complex is a therapeutic target for the GLK^highIL-17A^high subpopulation of human patients with SLE.-Chuang, H.-C., Chen, Y.-M., Chen, M.-H., Hung, W.-T., Yang, H.-Y., Tseng, Y.-H., Tan, T.-H. AhR-ROR-γt complex is a therapeutic target for MAP4K3/GLK^highIL-17A^high subpopulation of systemic lupus erythematosus.

Development of tibulizumab, a tetravalent bispecific antibody targeting BAFF and IL-17A for the treatment of autoimmune disease

We describe a bispecific dual-antagonist antibody against human B cell activating factor (BAFF) and interleukin 17A (IL-17). An anti-IL-17 single-chain variable fragment (scFv) derived from ixekizumab (Taltz®) was fused via a glycine-rich linker to anti-BAFF tabalumab. The IgG-scFv bound both BAFF and IL-17 simultaneously with identical stoichiometry as the parental mAbs. Stability studies of the initial IgG-scFv revealed chemical degradation and aggregation not observed in either parental antibody. The anti-IL-17 scFv showed a high melting temperature (Tm) by differential scanning calorimetry (73.1°C), but also concentration-dependent, initially reversible, protein self-association. To engineer scFv stability, three parallel approaches were taken: labile complementary-determining region (CDR) residues were replaced by stable, affinity-neutral amino acids, CDR charge distribution was balanced, and a H44-L100 interface disulfide bond was introduced. The Tm of the disulfide-stabilized scFv was largely unperturbed, yet it remained monodispersed at high protein concentration. Fluorescent dye binding titrations indicated reduced solvent exposure of hydrophobic residues and decreased proteolytic susceptibility was observed, both indicative of enhanced conformational stability. Superimposition of the H44-L100 scFv (PDB id: 6NOU) and ixekizumab antigen-binding fragment (PDB id: 6NOV) crystal structures revealed nearly identical orientation of the frameworks and CDR loops. The stabilized bispecific molecule LY3090106 (tibulizumab) potently antagonized both BAFF and IL-17 in cell-based and in vivo mouse models. In cynomolgus monkey, it suppressed B cell development and survival and remained functionally intact in circulation, with a prolonged half-life. In summary, we engineered a potent bispecific antibody targeting two key cytokines involved in human autoimmunity amenable to clinical development.

Serum and urine interleukin-17A levels as biomarkers of disease activity in systemic lupus erythematosus

OBJECTIVES

This study examined the correlations of both serum and urine interleukin-17A (IL-17A) levels with disease activity in systemic lupus erythematosus (SLE). This study was also aimed at determining their sensitivity and specificity as biomarkers of disease activity in SLE.

METHODS

A cross-sectional study was performed involving SLE patients (n = 120 patients) from Universiti Kebangsaan Malaysia Medical Centre (UKMMC). Serum and urinary IL-17A levels were determined by immunoassay while disease activity was assessed using Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K) and British Isles Lupus Assessment Group's 2004 index (BILAG 2004) scores. The correlations between serum and urinary IL-17A levels with total SLEDAI-2K and BILAG 2004 scores were determined using bivariate correlation analyses. Receiver operating characteristic curves were calculated to determine their sensitivity and specificity as disease activity biomarkers.

RESULTS

Both serum and urinary IL-17A levels correlated with total scores of BILAG 2004, BILAG renal, BILAG mucocutaneous, and SLEDAI-2K (P < 0.05). Urine IL-17A levels correlated positively with urine protein : creatinine index while serum IL-17 level correlated with the BILAG hematology score (all P < 0.05). The area under curve of serum IL-17A and urine IL-17A with BILAG and SLEDAI scores were low (<0.75).

CONCLUSION

Despite positive correlations between serum and urine IL-17A with SLE disease activity, both were neither sensitive nor specific as biomarkers to predict active disease. Hence, IL-17 measurement has no role in SLE disease activity assessments and future studies are needed to search for other reliable activity biomarkers.

Type I interferons in host defence and inflammatory diseases

Type I interferons (IFN) can have dual and opposing roles in immunity, with effects that are beneficial or detrimental to the individual depending on whether IFN pathway activation is transient or sustained. Determinants of IFN production and its functional consequences include the nature of the microbial or nucleic acid stimulus, the type of nucleic acid sensor involved in inducing IFN, the predominant subtype of type I IFN produced and the immune ecology of the tissue at the time of IFN expression. When dysregulated, the type I IFN system drives many autoimmune and non-autoimmune inflammatory diseases, including SLE and the tissue inflammation associated with chronic infection. The type I IFN system may also contribute to outcomes for patients affected by solid cancers or myocardial infarction. Significantly more research is needed to discern the mechanisms of induction and response to type I IFNs across these diseases, and patient endophenotyping may help determine whether the cytokine is acting as 'friend' or 'foe', within a particular patient, and at the time of treatment. This review summarises key concepts and discussions from the second International Summit on Interferons in Inflammatory Diseases, during which expert clinicians and scientists evaluated the evidence for the role of type I IFNs in autoimmune and other inflammatory diseases.

IL-17 is Aberrantly Overexpressed Among Under-treatment Systemic Lupus Erythematosus Patients

BACKGROUND & OBJECTIVE

Systemic lupus erythematosus (SLE) is an autoimmune disease with chronic inflammatory immune response. Current therapies mostly rely on glucocorticoids which are accompanied by side-effects and mostly fail to achieve a favorable remission. Th17 subpopulation of T cells is increased in exacerbated SLE as IL-17 cytokine is overexpressed. However, IL-17 is reported to be resistant to glucocorticoids in various disorders. Here, we evaluated the plasma level of IL-17 among newly diagnosed and under-treatment SLE patients to understand the effect of glucocorticoids on Th17 response.

METHODS

A total of 40 female SLE patients and 20 age- and sex- matched normal subjects were enrolled. IL-17 plasma level was evaluated using ELISA cytokine assay and analyzed with previously obtained IL-10, IFN-γ, and GILZ levels.

RESULTS

Our findings revealed that IL-17 was overexpressed among under-treatment SLE patients. There was a significant correlation between IL-17 and IFN-γ and significant reverse correlations between IL-17, IL-10, and GILZ levels. IL-17 was not significantly correlated with the disease activity.

CONCLUSION

According to the role of IL-17 in tissue injury and the fact that glucocorticoids are not successful in preventing organ damages in SLE, the overexpressed IL-17 in response to therapies could be introduced as an underlying reason.

Cytokine production by human neutrophils: Revisiting the "dark side of the moon"

Polymorphonuclear neutrophils are the most numerous leucocytes present in human blood, and function as crucial players in innate immune responses. Neutrophils are indispensable for the defence towards microbes, as they effectively counter them by releasing toxic enzymes, by synthetizing reactive oxygen species and by producing inflammatory mediators. Interestingly, recent findings have highlighted an important role of neutrophils also as promoters of the resolution of inflammation process, indicating that their biological functions go well beyond simple pathogen killing. Consistently, data from the last decades have highlighted that neutrophils may even contribute to the development of adaptive immunity by performing previously unanticipated functions, including the capacity to extend their survival, directly interact with other leucocytes or cell types, and produce and release a variety of cytokines. In this article, we will summarize the main features of, as well as emphasize some important concepts on, the production of cytokines by human neutrophils.

Profiling of B-Cell Factors and Their Decoy Receptors in Rheumatoid Arthritis: Association With Clinical Features and Treatment Outcomes

Introduction: B-cell activation is pivotal in rheumatoid arthritis (RA) pathogenesis and represents a relevant therapeutic target. The main aim of this study was to characterize the profiles of B-cell factors and their decoy receptors in RA and evaluate their clinical relevance.

Methods: sBLyS, sAPRIL, sBCMA, sTACI, sBLyS-R, and several cytokines' serum levels were measured by immunoassays in 104 RA patients and 33 healthy controls (HC). An additional group of 42 systemic lupus erythematosus (SLE) patients were enrolled as disease controls. Whole blood IFI44, IFI44L, IFI6, and MX1 gene expression was measured and averaged into an IFN-score. BLyS membrane expression (mBLyS) was assessed on blood cell subsets by flow cytometry.

Results: increased sAPRIL and sBCMA levels were found in RA, whereas BLyS was elevated in very early RA (VERA). No differences were observed for sTACI and sBLyS-R. An increased sBLyS/sBLyS-R ratio was associated with poor clinical outcome at 6 and 12 months in VERA, whereas a positive association with disease activity was observed in established disease. Increased mBLyS expression was found on monocytes, mDCs, neutrophils and B-cells in RA, to a similar extent that in SLE patients. Cluster analysis identified a specific B-cell factors profile overrepresented in RA and associated with autoantibodies, elevated proinflammatory cytokines (IFNα, MIP1α, TNFα, IL-37, and GM-CSF) and increased type-I IFN signature. Increasing sBCMA and sBLyS serum levels upon treatment and mBLyS expression at baseline on monocytes and mDCs, but not B-cells, were associated with poor clinical outcome upon TNFα-blockade.

Conclusions: profound and complex alterations of soluble and membrane-bound B-cell factors are observed in RA associated with clinical outcomes, thus supporting its applicability to guide patient stratification along disease course.

A Reappraisal on the Potential Ability of Human Neutrophils to Express and Produce IL-17 Family Members In Vitro: Failure to Reproducibly Detect It

Neutrophils are known to perform a series of effector functions that are crucial for the innate and adaptive responses, including the synthesis and secretion of a variety of cytokines. In light of the controversial data in the literature, the main objective of this study was to more in-depth reevaluate the capacity of human neutrophils to express and produce cytokines of the IL-17 family in vitro. By reverse transcription quantitative real-time PCR, protein measurement via commercial ELISA, immunohistochemistry (IHC) and immunofluorescence (IF), flow cytometry, immunoblotting, chromatin immunoprecipitation (ChIP), and ChIP-seq experiments, we found that highly pure (>99.7%) populations of human neutrophils do not express/produce IL-17A, IL-17F, IL-17AF, or IL-17B mRNA/protein upon incubation with a variety of agonists. Similar findings were observed by analyzing neutrophils isolated from active psoriatic patients. In contrast with published studies, IL-17A and IL-17F mRNA expression/production was not even found when neutrophils were incubated with extremely high concentrations of IL-6 plus IL-23, regardless of their combination with inactivated hyphae or conidia from Aspergillus fumigatus. Consistently, no deposition of histone marks for active (H3K27Ac) and poised (H3K4me1) genomic regulatory elements was detected at the IL-17A and IL-17F locus of resting and IL-6 plus IL-23-stimulated neutrophils, indicating a closed chromatin conformation. Concurrent experiments revealed that some commercial anti-IL-17A and anti-IL-17B antibodies (Abs), although staining neutrophils either spotted on cytospin slides or present in inflamed tissue samples by IHC/IF, do not recognize intracellular protein having the molecular weight corresponding to IL-17A or IL-17B, respectively, in immunoblotting experiments of whole neutrophil lysates. By contrast, the same Abs were found to more specifically recognize other intracellular proteins of neutrophils, suggesting that their ability to positively stain neutrophils in cytospin preparations and, eventually, tissue samples derives from IL-17A- or IL-17B-independent detections. In sum, our data confirm and extend, also at epigenetic level, previous findings on the inability of highly purified populations of human neutrophils to express/produce IL-17A, IL-17B, and IL-17F mRNAs/proteins in vitro, at least under the experimental conditions herein tested. Data also provide a number of justifications explaining, in part, why it is possible to false positively detect IL-17A⁺-neutrophils.

The Potential Role of Trained Immunity in Autoimmune and Autoinflammatory Disorders

During induction of trained immunity, monocytes and macrophages undergo a functional and transcriptional reprogramming toward increased activation. Important rewiring of cellular metabolism of the myeloid cells takes place during induction of trained immunity, including a shift toward glycolysis induced through the mTOR pathway, as well as glutaminolysis and cholesterol synthesis. Subsequently, this leads to modulation of the function of epigenetic enzymes, resulting in important changes in chromatin architecture that enables increased gene transcription. However, in addition to the beneficial effects of trained immunity as a host defense mechanism, we hypothesize that trained immunity also plays a deleterious role in the induction and/or maintenance of autoimmune and autoinflammatory diseases if inappropriately activated.