The Anti-DNA Antibodies: Their Specificities for Unique DNA Structures and Their Unresolved Clinical Impact—A System Criticism and a Hypothesis

Systemic lupus erythematosus (SLE) is diagnosed and classified by criteria, or by experience, intuition and traditions, and not by scientifically well-defined etiology(ies) or pathogenicity(ies). One central criterion and diagnostic factor is founded on theoretical and analytical approaches based on our imperfect definition of the term “The anti-dsDNA antibody”. “The anti-dsDNA antibody” holds an archaic position in SLE as a unique classification criterium and pathogenic factor. In a wider sense, antibodies to unique transcriptionally active or silent DNA structures and chromatin components may have individual and profound nephritogenic impact although not considered yet – not in theoretical nor in descriptive or experimental contexts. This hypothesis is contemplated here. In this analysis, our state-of-the-art conception of these antibodies is probed and found too deficient with respect to their origin, structural DNA specificities and clinical/pathogenic impact. Discoveries of DNA structures and functions started with Miescher’s Nuclein (1871), via Chargaff, Franklin, Watson and Crick, and continues today. The discoveries have left us with a DNA helix that presents distinct structures expressing unique operations of DNA. All structures are proven immunogenic! Unique autoimmune antibodies are described against e.g. ssDNA, elongated B DNA, bent B DNA, Z DNA, cruciform DNA, or individual components of chromatin. In light of the massive scientific interest in anti-DNA antibodies over decades, it is an unexpected observation that the spectrum of DNA structures has been known for decades without being implemented in clinical immunology. This leads consequently to a critical analysis of historical and contemporary evidence-based data and of ignored and one-dimensional contexts and hypotheses: i.e. “one antibody - one disease”. In this study radical viewpoints on the impact of DNA and chromatin immunity/autoimmunity are considered and discussed in context of the pathogenesis of lupus nephritis.

Variable presentations of systemic lupus erythematosus based on presence or absence of antidouble stranded DNA antibodies: A case series

Systemic lupus erythematosus (SLE) presents with diverse clinical features causing diagnostic challenges. Apart from the clinical features, autoantibodies are important for diagnosis along with certain laboratory parameters. Diagnosis is made with the European League against Rheumatism/American College of Rheumatology 2019 Criteria. The case series presented here signifies the correlation between anti ds DNA positivity and its association with poor prognosis and renal disease, whereas antidouble stranded DNA (anti-dsDNA) negativity may lead to lack of renal involvement and may be associated with polyserositis. The importance lies in the fact that these patients with anti-dsDNA negativity should be followed up for assessing conversion to positivity of anti-dsDNA, thus altering the prognosis and leading to renal involvement. Moreover, anti-SSA positive SLE patients must be followed up for possible development of sicca symptoms.

A case of spontaneous hypoglycemia

We describe a case of systemic lupus erythematosus with POEMS syndrome presenting as spontaneous hypoglycemia. A 58-year-old female suffered repeated episodes of hypoglycemia. During thesehypoglycemic episodes, her postprandial insulin level was inappropriately high. Further blood tests revealed the presence of antinuclear antibodies, anti-double-stranded DNA antibodies,low C4level.Altered albumin-globulin ratio,monoclonal gammopathy (IgG LAMBDA), polyneuropathy and organomegaly lead to suspicion of concurrent presence of POEMS syndrome.Bone marrow examination revealed plasma cell dyscrasia and plasmacytoma in trephine biopsy confirmed the diagnosis.Here, we emphasize on autoimmune cause of hypoglycemia. BIRDEM Med J 2022; 12(1): 70-73

Neutrophil Extracellular Traps-DNase Balance and Autoimmunity

Neutrophil extracellular traps (NETs) are macromolecular structures programmed to trap circulating bacteria and viruses. The accumulation of NETs in the circulation correlates with the formation of anti-double-stranded (ds) DNA antibodies and is considered a causative factor for systemic lupus erythematosus (SLE). The digestion of DNA by DNase1 and DNases1L3 is the rate- limiting factor for NET accumulation. Mutations occurring in one of these two DNASE genes determine anti-DNA formation and are associated with severe Lupus-like syndromes and lupus nephritis (LN). A second mechanism that may lead to DNase functional impairment is the presence of circulating DNase inhibitors in patients with low DNase activity, or the generation of anti-DNase antibodies. This phenomenon has been described in a relevant number of patients with SLE and may represent an important mechanism determining autoimmunity flares. On the basis of the reviewed studies, it is tempting to suppose that the blockade or selective depletion of anti-DNase autoantibodies could represent a potential novel therapeutic approach to prevent or halt SLE and LN. In general, strategies aimed at reducing NET formation might have a similar impact on the progression of SLE and LN.

Autoimmune anti-DNA and anti-phosphatidylserine antibodies predict development of severe COVID-19

High levels of autoimmune antibodies are observed in COVID-19 patients but their specific contribution to disease severity and clinical manifestations remains poorly understood. We performed a retrospective study of 115 COVID-19 hospitalized patients with different degrees of severity to analyze the generation of autoimmune antibodies to common antigens: a lysate of erythrocytes, the lipid phosphatidylserine (PS) and DNA. High levels of IgG autoantibodies against erythrocyte lysates were observed in a large percentage (up to 36%) of patients. Anti-DNA and anti-PS antibodies determined upon hospital admission correlated strongly with later development of severe disease, showing a positive predictive value of 85.7% and 92.8%, respectively. Patients with positive values for at least one of the two autoantibodies accounted for 24% of total severe cases. Statistical analysis identified strong correlations between anti-DNA antibodies and markers of cell injury, coagulation, neutrophil levels and erythrocyte size. Anti-DNA and anti-PS autoantibodies may play an important role in the pathogenesis of COVID-19 and could be developed as predictive biomarkers for disease severity and specific clinical manifestations.

The DNA sensors AIM2 and IFI16 are NET-binding SLE autoantigens

Nucleic acid binding proteins are frequently targeted as autoantigens in systemic lupus erythematosus (SLE) and other interferon (IFN)-linked rheumatic diseases. The AIM-like receptors (ALRs) are IFNinducible innate sensors that form supramolecular assemblies along double-stranded DNA of various origins. Here, we identify the ALR Absent in melanoma 2 (AIM2) as a novel autoantigen in SLE, with similar properties to the established ALR autoantigen interferon-inducible protein 16 (IFI16). Our SLE cohort revealed a frequent co-occurrence of anti-AIM2, anti-IFI16 and anti-DNA antibodies, and higher clinical measures of disease activity in patients positive for antibodies against these ALRs. We examined neutrophil extracellular traps (NETs) as DNA scaffolds on which these antigens might interact in a proimmune context, finding that both ALRs bind NETs in vitro and in SLE renal tissues. We demonstrate that ALR binding causes NETs to resist degradation by DNase I, suggesting a mechanism whereby extracellular ALR-NET interactions may promote sustained IFN signaling. Our work suggests that extracellular ALRs bind NETs, leading to DNase resistant nucleoprotein fibers that are targeted as autoantigens in SLE.

The Binding of Monoclonal and Polyclonal Anti-Z-DNA Antibodies to DNA of Various Species Origin

DNA is a polymeric macromolecule that can display a variety of backbone conformations. While the classical B-DNA is a right-handed double helix, Z-DNA is a left-handed helix with a zig-zag orientation. The Z conformation depends upon the base sequence, base modification and supercoiling and is considered to be transient. To determine whether the presence of Z-DNA can be detected immunochemically, the binding of monoclonal and polyclonal anti-Z-DNA antibodies to a panel of natural DNA antigens was assessed by an ELISA using brominated poly(dG-dC) as a control for Z-DNA. As these studies showed, among natural DNA tested (Micrococcus luteus, calf thymus, Escherichiacoli, salmon sperm, lambda phage), micrococcal (MC) DNA showed the highest binding with both anti-Z-DNA preparations, and E. coli DNA showed binding with the monoclonal anti-DNA preparation. The specificity for Z-DNA conformation in MC DNA was demonstrated by an inhibition binding assay. An algorithm to identify propensity to form Z-DNA indicated that DNA from Mycobacterium tuberculosis could form Z-DNA, a prediction confirmed by immunoassay. Together, these findings indicate that anti-Z-DNA antibodies can serve as probes for the presence of Z-DNA in DNA of various species origin and that the content of Z-DNA varies significantly among DNA sources.

Not all that is ‘full house’ is systemic lupus erythematosus: a case of membranous nephropathy due to syphilis infection

We describe an unusual case of membranous nephropathy precipitated by syphilis infection in a patient without systemic lupus erythematosus (SLE). A previously healthy 20-year-old man presented with leg and facial swelling. Laboratory investigation revealed nephrotic range proteinuria, acute kidney injury, hypocomplementaemia and a highly positive rapid plasma reagin. Kidney biopsy showed membranous nephropathy with ‘full-house’ immunofluorescence (IgG, IgA, IgM, C1q and C3), mimicking lupus nephritis class Vb. However, the patient had no features of SLE and had negative antinuclear and anti-double-stranded DNA antibodies. He was treated with high-dose methylprednisolone and mycophenolate mofetil for lupus nephritis and with penicillin for syphilis. After 2 months of therapy, his proteinuria resolved, and his renal function and C4 level normalised. This case illustrates that syphilis infection can be a mimicker of lupus nephritis. A literature review suggests that ful-house nephropathy may occur independently of lupus nephritis and may or may not develop into SLE.

MO320LUPUS FLARE MIMICKING COVID-19 INFECTION: A CASE REPORT

Background and Aims The world is in midst of the coronavirus disease 2019 (COVID-19) pandemic. Method Studies of the COVID-19 pathophysiology show that its defining character is an overt inflammatory response, similar to cytokine release syndrome, causing a dysregulated immune response. Systemic lupus erythematosus (SLE) is also a disease of immune dysregulation contributing to multisystem compromise. There is very little literature to suggest that COVID-19 could potentially mimick SLE presentation. We describe the case of a female patient who presented with typical Covid19 clinical features, later diagnosed as a new-onset SLE. Results A 51-year-old female presented with fever, dyspnea, cough and desaturation at the emergency room. Chest computed tomography scan showed bilateral areas of ground-glass opacities in a peripheral distribution. She was admitted in a Covid-19 ICU. She then progressed to severe acute respiratory distress syndrome, and worsening renal function with proteinuria and hematuria. Further investigations showed bilateral pleural effusions, ascites, leukopenia and thrombocytopenia, positive antinuclear and anti-double-stranded DNA antibodies, and low levels of C3 and C4. SARS-Cov-2 PCR was negative twice. After the establishment of the diagnosis, the patient was transferred to the internal medicine department where she received decongestive therapy, intravenous (IV) pulses of methylprednisolone, along with hydroxychloroquine. She improved sustainably and was discharged after two weeks. Conclusion A patient with new-onset lupus presented with clinical features typically seen in COVID-19 patients. The adequate management of the patient was delayed due to the misguided diagnosis.