Trigger For Systemic Lupus Erythematosus Research Articles

Deletion of the Mitochondrial Membrane Protein Fam210b Is Associated with the Development of Systemic Lupus Erythematosus.

Mitochondrial dysfunction has been increasingly recognized as a trigger for systemic lupus erythematosus (SLE). Recent bioinformatics studies have suggested Fam210b as a significant candidate for the classification and therapeutic targeting of SLE. To experimentally prove the role of Fam210b in SLE, we constructed Fam210b knockout (Fam210b-/-) mice using the CRISPR-Cas9 method. We found that approximately 15.68% of Fam210b-/- mice spontaneously developed lupus-like autoimmunity, which was characterized by skin ulcerations, splenomegaly, and an increase in anti-double-stranded DNA (anti-dsDNA) IgG antibodies and anti-nuclear antibodies(ANA). Single-cell sequencing showed that Fam210b was mainly expressed in erythroid cells. Critically, the knockout of Fam210b resulted in abnormal erythrocyte differentiation and development in the spleens of mice. Concurrently, the spleens exhibited an increased number of CD71+ erythroid cells, along with elevated levels of reactive oxygen species (ROS) in the erythrocytes. The co-culture of CD71+ erythroid cells and lymphocytes resulted in lymphocyte activation and promoted dsDNA and IgG production. In summary, Fam210b knockout leads to a low probability of lupus-like symptoms in mice through the overproduction of ROS in CD71+ erythroid cells. Thus, Fam210b reduction may serve as a novel key marker that triggers the development of SLE.

Quantitative annotations of T-Cell repertoire specificity.

The specificity of a T-cell receptor (TCR) repertoire determines personalized immune capacity. Existing methods have modeled the qualitative aspects of TCR specificity, while the quantitative aspects remained unaddressed. We developed a package, TCRanno, to quantify the specificity of TCR repertoires. We created deep-learning-based, epitope-aware vector embeddings to infer individual TCR specificity. Then we aggregated clonotype frequencies of TCRs to obtain a quantitative profile of repertoire specificity at epitope, antigen and organism levels. Applying TCRanno to 4195 TCR repertoires revealed quantitative changes in repertoire specificity upon infections, autoimmunity and cancers. Specifically, TCRanno found cytomegalovirus-specific TCRs in seronegative healthy individuals, supporting the possibility of abortive infections. TCRanno discovered age-accumulated fraction of severe acute respiratory syndrome coronavirus 2 specific TCRs in pre-pandemic samples, which may explain the aggressive symptoms and age-related severity of coronavirus disease 2019. TCRanno also identified the encounter of Hepatitis B antigens as a potential trigger of systemic lupus erythematosus. TCRanno annotations showed capability in distinguishing TCR repertoires of healthy and cancers including melanoma, lung and breast cancers. TCRanno also demonstrated usefulness to single-cell TCRseq+gene expression data analyses by isolating T-cells with the specificity of interest.

Should asymptomatic bacteriuria be treated in lupus nephritis?

The risk of infection in systemic lupus erythematosus (SLE) is associated with factors related to disease activity and immunosuppressive treatment. Recently, the persistence of asymptomatic bacteriuria (ASB) has been proposed as an environmental trigger for SLE and its flares, raising the question whether it should be treated systematically to reduce the risk of infection. To our knowledge, there is limited evidence on the screening and treatment of ASB in SLE. The objective is to analyze the occurrence of infection and flare in patients with lupus nephritis with and without ASB. A cross-sectional study of a cohort of patients with lupus nephritis during induction therapy with high-dose cyclophosphamide regimen was carried out between January 2018 and 2020, with a total of 37 patients investigated. Urine and blood samples from the two groups (with ASB and without ASB) where taken before the administration of cyclophosphamide. From the sampled 37 patients, 19 (51.4%) had ASB and 18 (48.6%) without ASB; both groups were well balanced in their demographics and clinical characteristics. No statistically significant association was found between the presence of ASB and the systemic lupus erythematosus disease activity index score (p = 0.604), and neither with the 24-h urine protein and leukocyte count (p > 0.177). Urinary tract infection occurred in 5.3% (1) of the patients with ASB, while 5.6% (1) of the patients in the group without ASB presented the infection, and the RR was 0.944 (0.06, 16.33) 95% CI; in addition, no statistically significant association was found between the presence of ASB and the occurrence of infection (p = 1,000). Our study did not find a statistically significant association of ASB with the occurrence of infection or disease activity. Further studies need it to clarify this, since treatment of ASB has been recognized as an important contributor to inappropriate antimicrobial use, which promotes emergence of antimicrobial resistance.

Association of Viral Infection With the Development and Pathogenesis of Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease that causes multiple organ damage in women of childbearing age and has a relapsing-remitting course. SLE is caused by the interaction between genetic and environmental factors, however, its underlying triggers remain unknown. Among the environmental factors, the involvement of infections as a trigger for SLE, especially those of viral etiology, has been widely reported. Human endogenous retroviruses (HERVs) may put patients at a genetic predisposition to SLE, while the Epstein-Barr virus (EBV) may play a role as an environmental factor that triggers the development of SLE. It has been suggested that EBV-infected B-cells may become resistant to apoptosis, resulting in the activation, proliferation, and antibody production of autoreactive B-cells, which cause tissue damage in SLE. However, the interaction between the virus and immune cells, as well as the impact of the virus on the differentiation and dysfunction of immune cells, remain unclear. In this review, we focus on the relationship between the development and pathogenesis of SLE and viral infections, as well as the mechanism of SLE exacerbation via activation of immune cells, such as B-cells, based on the latest findings.

Cytomegalovirus-Associated Autoantibody against TAF9 Protein in Patients with Systemic Lupus Erythematosus

Background: Evidence indicates a causal link between cytomegalovirus (CMV) infection and the triggering of systemic lupus erythematosus (SLE). Animal studies have revealed that CMV phosphoprotein 65 (pp65) induces autoantibodies against nuclear materials and causes the autoantibody attack of glomeruli. IgG eluted from the glomeruli of CMVpp65-peptide-immunized mice exhibited cross-reactivity against dsDNA and TATA-box-binding protein associated factor 9 (TAF9). Whether the elevation of anti-TAF9 IgG is associated with anti-CMV reactivity in human lupus remains unclear. Methods: The sera from patients with rheumatic diseases, including ankylosing spondylitis (AS), gout, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and Sjögren syndrome (SS) were examined using ELISA for antibodies of CMV, CMVpp65, and TAF9. Results: In total, 83.8% of the rheumatic patients had acquired CMV infections. The SLE patients had a high prevalence of anti-CMV IgM. The highest seropositivity rates for anti-HCMVpp65 and anti-TAF9 IgG were observed in the SLE patients. Purified anti-CMVpp65 IgG from CMVpp65/TAF9 dual-positive SLE sera reacted to both TAF9 and dsDNA. An increased prevalence of proteinuria and low hemoglobin levels were found in CMV IgG- and CMVpp65 IgG-positive SLE patients. Conclusions: This observation suggests that immunity to CMVpp65 is associated with cross-reactivity with TAF9 and dsDNA and that it is involved in the development of clinical manifestations in SLE.

Human cytomegalovirus pp65 peptide-induced autoantibodies cross-reacts with TAF9 protein and induces lupus-like autoimmunity in BALB/c mice

Human cytomegalovirus (HCMV) has been linked to the triggering of systemic lupus erythematosus (SLE). We proposed that B cell epitope region of HCMV phosphoprotein 65 (HCMVpp65)422–439 mimics an endogenous antigen and initiates lupus-like autoimmunity. Amino acid homology between HCMVpp65422-439 and TAF9134-144 (TATA-box binding protein associated factor 9, TAF9) was investigated using a similarity search in NCBI protein BLAST program (BLASTP). A murine model was used to confirm their antigenicity and ability to induce lupus-like symptoms. HCMVpp65422-439 induced immune responses with the presence of specific antibodies against HCMVpp65422-439 and TAF9134-144, as well as anti-nuclear and anti-double-stranded (ds)DNA antibodies that are characteristic of SLE. In addition, the majority of HCMVpp65422-439 and TAF9134-144 immunized mice developed proteinuria, and their renal pathology revealed glomerulonephritis with typical abnormalities, such as mesangial hypercellularity and immune complex deposition. Immunoglobulin eluted from the glomeruli of HCMVpp65422-439 immunized mice showed cross-reactivity with TAF9134-144 and dsDNA. Increased anti-TAF9 antibody activity was also observed in the sera from SLE patients compared with healthy people and disease controls. Molecular mimicry between HCMVpp65 peptide and host protein has the potential to drive lupus-like autoimmunity. This proof-of-concept study highlights the mechanisms underlying the link between HCMV infection and the induction of SLE.

Leptospirosis as Unusual Trigger of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder of an unknown origin. The role of leptospirosis as a triggering factor for SLE is unknown. This paper reports an uncommon case of SLE following a leptospira infection. A 29-year-old female was referred due to fevers, myalgia, and facial edema with rash. Laboratory investigations revealed a hepatic dysfunction, significantly raised lactate dehydrogenase with marked leukopenia and thrombocytopenia. A diagnosis of leptospirosis was confirmed. The patient was treated with antibiotic therapy for leptospirosis. She developed dyspnea after one week. The echocardiogram revealed global hypokinesia with a decreased ejection fraction. A positivity of antinuclear, anti-DNA, and anti-Smith antibodies, together with clinical and laboratory improvement by steroid therapy, led to the diagnosis of SLE. This case highlights the presence of concurrent SLE and leptospirosis. As the symptoms of SLE are similar to leptospirosis, accurate diagnosis through high suspicion is essential for appropriate treatment.

Human and Murine Evidence for Mechanisms Driving Autoimmune Photosensitivity.

Ultraviolet (UV) light is an important environmental trigger for systemic lupus erythematosus (SLE) patients, yet the mechanisms by which UV light impacts disease are not fully known. This review covers evidence in both human and murine systems for the impacts of UV light on DNA damage, apoptosis, autoantigen exposure, cytokine production, inflammatory cell recruitment, and systemic flare induction. In addition, the role of the circadian clock is discussed. Evidence is compared in healthy individuals and SLE patients as well as in wild-type and lupus-prone mice. Further research is needed into the effects of UV light on cutaneous and systemic immune responses to understand how to prevent UV-light mediated lupus flares.

Serum milk fat globule epidermal growth factor 8 elevation may subdivide systemic lupus erythematosus into two pathophysiologically distinct subsets

Impaired clearance of apoptotic cells is a potential trigger of systemic lupus erythematosus (SLE). Milk fat globule epidermal growth factor 8 (MFG-E8) plays an important role in the clearance of dying cells. Previously, we reported serum MFG-E8 was elevated in some SLE patients. Here we further investigated the prevalence of MFG-E8 in active SLE and other autoimmune diseases and also tried to clarify the characteristics of MFG-E8-positive and -negative SLE. Serum MFG-E8 was measured in 40 active non-treated SLE patients, 104 disease controls and 104 healthy controls by ELISA. Clinical characteristics and serum cytokine profiles were compared between MFG-E8-positive and MFG-E8-negative SLE patients. Prevalence of MFG-E8 was significantly higher in SLE patients (40%) than in various controls (p < 0.05). MFG-E8 level became negative after treatment, and increased again upon relapse. When compared, MFG-E8-positive SLE patients showed higher immune complex (p = 0.021) and lower complement (p = 0.004 for CH50). In contrast, MFG-E8-negative SLE patients tended to show higher CRP (p = 0.094). There was a positive correlation between MFG-E8 level and immune complex level (r s = 0.49, p = 0.049). TNF-α (p = 0.019), IFN-γ (p = 0.031) and IL-10 (p = 0.013) were significantly higher in MFG-E8-positive SLE. MFG-E8-positive SLE and -negative SLE may have different clinical features, the one with stronger immunological response and the other with stronger inflammatory response, and those two groups may be two distinct subtypes of SLE driven by different mechanisms. Further, MFG-E8 could be used as a biomarker for diagnosis and monitoring of disease activity in certain SLE patients.

Opportunistic infections in systemic lupus erythematosus

Opportunistic infections (OIs) are not frequently seen in systemic lupus erythematosus (SLE). However, when present they are very dangerous, being potentially fatal in the majority of cases. Immunosuppressive therapy is the strongest risk factor for OI and correlates with death during infective episodes, but there are other factors predisposing to infection in SLE patients, such as several defects of the immune system that are intrinsic to the disease. The diagnosis of OI in SLE may be overlooked, owing to the fact that SLE flares may mimic infection with fever and inflammatory syndrome, and needs special attention in patients at risk. Finally, we have to consider that OIs could be a trigger of SLE too.

Peroxynitrite-induced modification of H2A histone presents epitopes which are strongly bound by human anti-DNA autoantibodies: Role of peroxynitrite-modified-H2A in SLE induction and progression

Peroxynitrite is a potent oxidant and nitrating agent and has in vivo existence. It is a powerful proinflammatory substance and may increase vascular permeability in inflamed tissues. Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease of unknown etiology. Since its discovery, numerous self- and non-self, nuclear, and cytoplasmic antigens have been suggested as stimuli for SLE initiation, but the exact trigger is yet to be identified. In this study, an attempt has been made to investigate the binding characteristics of SLE anti-DNA autoantibodies to native DNA and native and peroxynitrite-modified H2A histone to explore the possible role of modified protein antigen(s) in SLE initiation and progression. The nuclear protein (H2A histone) was modified by peroxynitrite synthesized in our laboratory. The peroxynitrite-modified H2A revealed generation of nitrotyrosine, dityrosine, and carbonyls when subjected to investigation by physicochemical methods. Binding characteristics and specificity of SLE anti-DNA antibodies were analyzed by direct binding and inhibition enzyme-linked immunosorbent assay. The data show preferential binding of SLE autoantibodies to peroxynitrite-modified H2A histone in comparison with native H2A histone or native DNA. A band shift assay further substantiated the enhanced recognition of peroxynitirite-modified H2A histone by anti-DNA autoantibodies. The results suggest that peroxynitrite modification of self-antigen(s) can generate neoepitopes capable of inducing SLE characteristic autoantibodies. The preferential binding of peroxynitrite-modified H2A histone by SLE anti-DNA antibodies points out the likely role of oxidatively modified and nitrated H2A histone in the initiation/progression of SLE. Moreover, oxidatively modified and nitrated nuclear protein antigen, rather than nucleic acid antigens, appear to be more suitable as a trigger for SLE.

Cytomegalovirus as a Trigger for Systemic Lupus Erythematosus

Cytomegalovirus (CMV) infections have been associated with exacerbations of systemic lupus erythematosus (SLE). Their role in triggering this disease, however, remains a subject of debate. We present a 43-year-old man with no history of systemic illness who developed persistent signs and symptoms of a CMV-associated mononucleosis-like syndrome while fulfilling diagnostic criteria for previously undiagnosed SLE. The patient was admitted with persistent fever for 3 weeks, cervical lymphadenopathy, elevated liver function tests, and leukopenia. Further laboratory studies revealed positive antinuclear antibody, anti-dsDNA, anti-Sm/RNP, rheumatoid factor, and anticardiolipin antibodies along with decreased complement levels and proteinuria of 876 mg/dL. CMV immunoglobulin M was positive in the absence of CMV immunoglobulin G, supporting acute CMV infection. Symptoms improved with intravenous administration of methylprednisolone and ganciclovir therapy. Mechanisms by which CMV may trigger autoimmunity have been proposed, and this case could support CMV infection as a potential trigger for SLE in susceptible individuals.

Oral contraceptives and risk of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) predominantly affects women and its incidence is highest during child-bearing years. Therefore, endogenous sex hormones are thought to be an important causal factor in SLE etiology. Furthermore, exogenous hormonal factors, such as estrogen-containing oral contraceptives (OCs), have for many years been suspected in triggering SLE. Up to now, the etiologic role of OCs in SLE was a matter of debate, since studies had suggested conflicting results. Although several case reports showed an association between OC exposure and SLE onset, case–control studies did not confirm this. However, in recent years, data incriminating OCs as a potential trigger of SLE are now accumulating. The purpose of this paper is to present a systematic review of this literature.

Fc epsilon receptor type I gamma chain replaces the deficient T cell receptor zeta chain in T cells of patients with systemic lupus erythematosus.

T cells from the majority of patients with systemic lupus erythematosus (SLE) express significantly lower levels of T cell receptor zeta chain, a critical signaling molecule. However, TCR/CD3 triggering of SLE T cells shows increased phosphorylation of downstream signaling intermediates and increased [Ca2+]i response, suggesting the presence of alternative signaling mechanisms. We investigated whether Fcepsilon receptor type I gamma chain (FcepsilonRIgamma) could substitute for TCR zeta chain and contribute to T cell signaling in SLE. T cells were purified from the peripheral blood of 21 patients with SLE and 5 healthy volunteers. The expression of FcepsilonRIgamma was investigated using immunoblotting, reverse transcriptase-polymerase chain reaction, and flow cytometry methods. Involvement of the FcepsilonRIgamma in T cell signaling was studied by immunoprecipitation and/or immunoblotting after TCR/CD3 stimulation. Western blotting and densitometric analysis showed that the expression of FcepsilonRIgamma in SLE T cells was 4.3-fold higher than in normal T cells (P < 0.001). Flow cytometric analyses of T lymphocyte subsets revealed that the proportions of FcepsilonRIgamma+,CD3+, FcepsilonRIgamma+,CD4+, and FcepsilonRIgamma+, CD8+ cells were significantly greater in SLE patients than in healthy controls (P < 0.001). Immunoprecipitation of SLE T cell lysates with an anti-FcepsilonRIgamma antibody showed that FcepsilonRIgamma associates with the tyrosine kinase Syk and the CD3epsilon chain, suggesting that FcepsilonRIgamma is functionally involved in TCR signaling. These results demonstrate that the FcepsilonRIgamma chain is expressed at high levels in a large proportion of SLE T cells. The increased expression of FcepsilonRIgamma chain in SLE T cells may account in part for the aberrant antigen receptor-initiated signaling and contribute to the diverse cellular abnormalities found in this disease.