Serum soluble tumour necrosis factor receptor-2 (sTNFR2) as a biomarker of kidney tissue damage and long-term renal outcome in lupus nephritis

Lupus Nephritis Biomarkers: A Critical Review

Lupus nephritis (LN), a major complication in individuals diagnosed with systemic lupus erythematosus, substantially increases morbidity and mortality. Despite marked improvements in the survival of patients with severe LN over the past 50 years, complete clinical remission after immunosuppressive therapy is achieved in only half of the patients. Therefore, timely detection of LN is vital for initiating prompt therapeutic interventions and improving patient outcomes. Biomarkers have emerged as valuable tools for LN detection and monitoring; however, the complex role of these biomarkers in LN pathogenesis remains unclear. Renal biopsy remains the gold standard for the identification of the histological phenotypes of LN and guides disease management. However, the molecular pathophysiology of specific renal lesions remains poorly understood. In this review, we provide a critical, up-to-date overview of the latest developments in the field of LN biomarkers.

Novel biomarker discovery through comprehensive proteomic analysis of lupus mouse serum

OBJECTIVES

The difficulty of monitoring organ-specific pathology in systemic lupus erythematosus (SLE) often complicates disease prognostication and treatment. Improved non-invasive biomarkers of active organ pathology, particularly lupus nephritis, would improve patient care. We sought to validate and apply a novel strategy to generate the first comprehensive serum proteome of a lupus mouse model and identify mechanism-linked lupus biomarker candidates for subsequent clinical investigation.

METHODS

Serum levels of 1308 diverse proteins were measured in eight adult female MRL/lpr lupus mice and eight control MRL/mpj mice. ELISA validation confirmed fold increases. Protein enrichment analysis provided biological relevance to findings. Individual protein levels were correlated with measures of lymphoproliferative, humoral, and renal disease.

RESULTS

Four hundred and six proteins were increased in MRL/lpr serum, including proteins increased in human SLE such as VCAM-1, L-selectin, TNFRI/II, TWEAK, CXCL13, MCP-1, IP-10, IL-10, and TARC. Newly validated proteins included IL-6, IL-17, and MDC. Results of pathway enrichment analysis, which revealed enhancement of cytokine signaling and immune cell migration, reinforced the similarity of the MRL/lpr disease to human pathology. Fifty-two proteins positively correlated with at least one measure of lupus-like disease. TECK, TSLP, PDGFR-alpha, and MDC were identified as novel candidate biomarkers of renal disease.

CONCLUSIONS

We successfully validated a novel serum proteomic screening strategy in a spontaneous murine lupus model that highlighted potential new biomarkers. Importantly, we generated a comprehensive snapshot of the serum proteome which will enable identification of other candidates and serve as a reference for future mechanistic and therapeutic studies in lupus.

Biomarkers Associated with Drugs for the Treatment of Lupus Nephritis

The constant updating of lupus drug treatment guidelines has led to a question. How can the efficacy of treatment be more effectively monitored? Systemic lupus erythematosus (SLE) is a complex autoimmune disease that often presents clinically with multi-organ involvement, and approximately 30% of patients with SLE develop lupus nephritis (LN). Therefore, it is important to better track disease progression and drug efficacy. Now, kidney biopsy is still the gold standard for diagnosing and guiding the treatment of LN, but it is invasive and expensive. If simple, non-invasive and effective biomarkers can be found, drug intervention and prognosis can be better monitored and targeted. In this review, we focus on LN and explore biomarkers related to LN therapeutics, providing clinicians with more possibilities to track the therapeutic effect of drugs, improve treatment options and assess patient outcomes.

Searching for a prognostic index in lupus nephritis

BACKGROUND

Currently we do not have an ideal biomarker in lupus nephritis (LN) that should help us to identify those patients with SLE at risk of developing LN or to determine those patients at risk of renal progression. We aimed to evaluate the development of a prognostic index for LN, through the evaluation of clinical, analytical and histological factors used in a cohort of lupus. We have proposed to determine which factors, 6 months after the diagnosis of LN, could help us to define which patients will have a worse evolution of the disease and may be, more aggressive treatment and closer follow-up.

METHODS

A retrospective study to identify prognostic factors was carried out. We have included patients over 18 years of age with a clinical diagnosis of systemic lupus erythematosus (SLE) and kidney involvement confirmed by biopsy, who are followed up in our centre during the last 20 years. A multi-step statistical approach will be used in order to obtain a limited set of parameters, optimally selected and weighted, that show a satisfactory ability to discriminate between patients with different levels of prognosis.

RESULTS

We analysed 92 patients with LN, although only 73 have been able to be classified according to whether or not they have presented poor renal evolution. The age of onset (44 vs. 32; p = 0.024), the value of serum creatinine (1.41 vs. 1.04; p = 0.041), greater frequency of thrombocytopenia (30 vs. 7%; p = 0.038), higher score in the renal chronicity index (2.47 vs. 1.04; p = 0.015), proliferative histological type (100%) and higher frequency of interstitial fibrosis (67 vs. 32%; p = 0.017) and tubular atrophy (67 vs. 32%; p = 0.018) was observed between two groups. The multivariate analysis allowed us to select the best predictive model for poor outcome at 6 months based on different adjustment and discrimination parameters.

CONCLUSION

We have developed a prognostic index of poor renal evolution in patients with LN that combines demographic, clinical, analytical and histopathological factors, easy to use in routine clinical practice and that could be an effective tool in the early detection and management.

MiR-125b-5p modulates the function of regulatory T cells in tumor microenvironment by targeting TNFR2

BACKGROUND

Tumor necrosis factor receptor type 2 (TNFR2) is primarily expressed by CD4⁺FoxP3⁺ regulatory T cells (Tregs), especially those present in tumor microenvironment. There is compelling evidence that TNFR2 plays a crucial role in the activation, expansion, and phenotypic stability of Tregs and promotes tumor immune evasion. Understanding of epigenetic regulation of TNFR2 expression in Tregs may help device a novel strategy in cancer immunotherapy.

METHODS

MiR-125b-5p-overexpressing or knockdown murine CD4 T cells and Tregs were constructed, and the effect of miR-125b-5p on Tregs proliferation, suppressive function and TNFR2 expression were examined. In vivo antitumor efficacy of Ago-125b-5p (miR-125b-5p agomir) was evaluated in MC38 tumor bearing mice, and tumor-infiltrating Tregs and CD8⁺ cytotoxic T lymphocytes (CTLs) were analyzed. RNA-seq analysis was applied to reveal the genes and signaling pathways regulated by miR-125b-5p in Tregs.

RESULTS

In this study, we found that TNFR2 was a direct target of miR-125b-5p. Overexpression of miR-125b-5p decreased the proportion of Tregs and their expression of TNFR2 and consequently inhibited its proliferation and suppressive function by regulating the metabolism-related signaling pathways. Moreover, in colon cancer bearing mice, the administration of Ago-125b-5p markedly inhibited the tumor growth, which was associated with reduction of Tregs and increase of IFNγ⁺CD8⁺ T cells in tumor environment. Furthermore, in human colon adenocarcinoma patients, we verified that miR-125b-5p expression was downregulated, and low levels of miR-125b-5p were associated with poor prognosis. Interestingly, the expression of miR-125b-5p and TNFR2 were negatively correlated.

CONCLUSIONS

Our study for the first time found that the expression of TNFR2 by Tregs was regulated by miR-125b-5p. Our results showed that miR-125b-5p had the capacity to inhibit the expression of TNFR2 and immunosuppressive activity of Tregs and consequently enhanced the antitumor efficacy. This property of miR-125b-5p may be therapeutically harnessed in the treatment of human cancers.

Targeted biomarkers of progression in chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is an increasingly significant health issue worldwide. Early stages of CKD can be asymptomatic and disease trajectory difficult to predict. Not everyone with CKD progresses to kidney failure, where kidney replacement therapy is the only life-sustaining therapy. Predicting which patients will progress to kidney failure would allow better use of targeted treatments and more effective allocation of health resources. Current diagnostic tests to identify patients with progressive disease perform poorly but there is a suite of new and emerging predictive biomarkers with great clinical promise.

METHODS

This narrative review describes new and emerging biomarkers of pathophysiologic processes of CKD development and progression, accessible in blood or urine liquid biopsies. Biomarkers were selected based on their reported pathobiological functions in kidney injury, inflammation, oxidative stress, repair and fibrosis. Biomarker function and evidence of involvement in CKD development and progression are reported.

CONCLUSION

Many biomarkers reviewed here have received little attention to date, perhaps because of conflicting conclusions of their utility in CKD. The functional roles of the selected biomarkers in the underlying pathobiology of progression of CKD are a powerful rationale for advancing and validating these molecules as prognosticators and predictors of CKD trajectory.

Efficiency of Disease and Disease Activity Diagnosis Models of Systemic Lupus Erythematosus Based on Protein Array Analysis

Background

Systemic lupus erythematosus (SLE) has become increasingly common in the clinic and requires complicated evidence of both clinical manifestations and laboratory examinations. Additionally, the assessment and monitoring of lupus disease activity are challenging. We hope to find efficient biomarkers and establish diagnostic models of SLE.

Materials and Methods

We detected and quantified 40 proteins using a quantitative protein array of 76 SLE patients and 21 healthy controls, and differentially expressed proteins were screened out by volcano plot. Logistic regression analysis was used to recognize biomarkers that could be enrolled in the disease diagnosis model and disease activity diagnosis model, and a receiver operating characteristic (ROC) curve was drawn to evaluate the efficiency of the model. A nomogram was depicted for convenient and visualized application of our models in the clinic. Decision curves and clinical impact curves were also plotted to validate our models.

Results

The protein levels of TNF RII, BLC, TNF RI, MIP-1b, eotaxin, MIG, MCSF, IL-8, MCP-1, and IL-10 showed significant differences between patients with SLE and healthy controls. TNF RII and MIP-1b were included in the SLE diagnosis model with logistic regression analysis, and the value of the area under the ROC curve (AUC) was 0.914 (95% confidence interval (CI), 0.859-0.969). TNF RII, BLC, and MIP-1b were enrolled in the disease activity diagnosis model, and the AUC value was 0.823 (95% CI 0.729-0.916). Both of the models that we established showed high efficiency. Additionally, the three protein biomarkers contained in the disease activity distinguish model provided additional benefit to conventional biomarkers in predicting active lupus.

Conclusions

The disease diagnosis model and disease activity diagnosis model that we developed based on protein array chip results showed high efficiency in differentiating patients with SLE from healthy controls and recognizing SLE patients with high disease activity, and they have also been validated. This implied that they might greatly benefit clinical decisions and the treatment of SLE.

Treatment of Lupus Nephritis from Iranian Traditional Medicine and Modern Medicine Points of View: A Comparative Study

Objective

Nephritis or kidney inflammation is characterized as one of the most common renal disorders leading to serious damage to the kidneys. Nephritis, especially lupus nephritis (LN), has remained as the main cause of chronic renal failure which needs serious therapeutic approaches such as dialysis and kidney transplant. Heredity, infection, high blood pressure, inflammatory diseases such as lupus erythematosus and inflammatory bowel disease, and drug-related side effects are known as the main causes of the disease. According to Iranian traditional medicine (ITM), infectious diseases and fever are the main reasons of nephritis, which is called “Varam-e-Kolye” (VK).

Results

There are various plant-based remedies recommended by ITM for the treatment of nephritis, as discussed herein, comparing with those available in the modern medicine. There is no definite cure for the treatment of nephritis, and immunosuppressive drugs such as corticosteroids and nonsteroidal anti-inflammatory drugs, antibiotics, diuretics, analgesics, and finally dialysis and kidney transplantation are usually used. Based on the efficacy of medicinal plants, jujube (Ziziphus jujuba), almond (Prunus amygdalus), pumpkin seeds (Cucurbita pepo), purslane (Portulaca oleracea), and fig (Ficus carica) were found to be effective for the treatment of kidney inflammation in ITM.

Conclusion

Considering the fact that there is no efficient strategy for the treatment of nephritis, use of herbal medicine, particularly based on the fruits or nuts that have been safely used for several years can be considered as a versatile supplement along with other therapeutic methods.

The lupus nephritis management renaissance

Over the past year, and for the first time ever, the US Food and Drug Administration approved 2 drugs specifically for the treatment of lupus nephritis (LN). As the lupus community works toward understanding how to best use these new therapies, it is also an ideal time to begin to rethink the overall management strategy of LN. In addition to new drugs, this must include how to use kidney biopsies for management and not just diagnosis, how molecular technologies can be applied to interrogate biopsies and how such data can impact management, and how to incorporate LN biomarkers into management paradigms. Herein, we will review new developments in these areas of LN and put them into perspective for disease management now and in the future.

Associations Between Preoperative Biomarkers and Cardiac Surgery-Associated Acute Kidney Injury in Elderly Patients: A Cohort Study

BACKGROUND

Acute kidney injury (AKI) is associated with mortality after cardiac surgery. Novel risk factors may improve identification of patients at risk for renal injury. The authors evaluated the association between preoperative biomarkers that reflect cardiac, inflammatory, renal, and metabolic disorders and cardiac surgery-associated AKI (CSA-AKI) in elderly patients.

METHODS

This was a secondary analysis of the 2-center prospective cohort study "Anesthesia Geriatric Evaluation." Twelve biomarkers were determined preoperatively in 539 patients. Primary outcome was CSA-AKI. The association between biomarkers and CSA-AKI was investigated with multivariable logistic regression analysis. Secondary outcomes were 1-year mortality and patient-reported disability and were assessed with relative risks (RR) between patients with and without CSA-AKI.

RESULTS

CSA-AKI occurred in 88 (16.3%) patients and was associated with increased risk of mortality (RR, 6.70 [95% confidence interval {CI}, 3.38-13.30]) and disability (RR, 2.13 [95% CI, 1.53-2.95]). Preoperative concentrations of N-terminal pro B-type natriuretic peptide (NT-proBNP), high-sensitive C-reactive protein (hs-CRP), hemoglobin, and magnesium had the strongest association with CSA-AKI. Identification of patients with CSA-AKI improved when a biomarker panel was used (area under the curve [AUC] 0.75 [95% CI, 0.69-0.80]) compared to when only clinical risk factors were used (European System for Cardiac Operative Risk Evaluation [EuroSCORE II] AUC 0.67 [95% CI, 0.62-0.73]).

CONCLUSIONS

Preoperative cardiac, inflammatory, renal, and metabolic biomarkers are associated with CSA-AKI and may improve identification of patients at risk.

Prediction of prognosis and renal outcome in lupus nephritis

Lupus nephritis (LN) is a severe manifestation of SLE, characterised by subendothelial and/or subepithelial immune complex depositions in the afflicted kidney, resulting in extensive injury and nephron loss during the acute phase and eventually chronic irreversible damage and renal function impairment if not treated effectively. The therapeutic management of LN has improved during the last decades, but the imperative need for consensual outcome measures remains. In order to design trials with success potentiality, it is important to define clinically important short-term and long-term targets of therapeutic and non-therapeutic intervention. While it is known that early response to treatment is coupled with favourable renal outcomes, early predictors of renal function impairment are lacking. The information gleaned from kidney biopsies may provide important insights in this direction. Alas, baseline clinical and histopathological information has not been shown to be informative. By contrast, accumulating evidence of pronounced discrepancies between clinical and histopathological outcomes after the initial phase of immunosuppression has prompted investigations of the potential usefulness of per-protocol repeat kidney biopsies as an integral part of treatment evaluation, including patients showing adequate clinical response. This approach appears to have merit. Hopefully, clinical, molecular or genetic markers that reliably reflect kidney histopathology and portend the long-term prognosis will be identified. Novel non-invasive imaging methods and employment of the evolving artificial intelligence in pattern recognition may also be helpful towards these goals. The molecular and cellular characterisation of SLE and LN will hopefully result in novel therapeutic modalities, maybe new taxonomy perspectives, and ultimately personalised management.

Stratifying risk of acute kidney injury in pre and post cardiac surgery patients using a novel biomarker-based algorithm and clinical risk score

Acute kidney injury (AKI) following cardiac surgery significantly increases morbidity and mortality risks. Improving existing clinical methods of identifying patients at risk of perioperative AKI may advance management and treatment options. This study investigated whether a combination of biomarkers and clinical factors pre and post cardiac surgery could stratify patients at risk of developing AKI. Patients (n = 401) consecutively scheduled for elective cardiac surgery were prospectively studied. Clinical data was recorded and blood samples were tested for 31 biomarkers. Areas under receiver operating characteristic (AUROCs) were generated for biomarkers pre and postoperatively to stratify patients at risk of AKI. Preoperatively sTNFR1 had the highest predictive ability to identify risk of developing AKI postoperatively (AUROC 0.748). Postoperatively a combination of H-FABP, midkine and sTNFR2 had the highest predictive ability to identify AKI risk (AUROC 0.836). Preoperative clinical risk factors included patient age, body mass index and diabetes. Perioperative factors included cardio pulmonary bypass, cross-clamp and operation times, intra-aortic balloon pump, blood products and resternotomy. Combining biomarker risk score (BRS) with clinical risk score (CRS) enabled pre and postoperative assignment of patients to AKI risk categories. Combining BRS with CRS will allow better management of cardiac patients at risk of developing AKI.

Serum Axl predicts histology-based response to induction therapy and long-term renal outcome in lupus nephritis

Axl is a receptor tyrosine kinase with important functions in immune regulation. We investigated serum levels of soluble (s)Axl in lupus nephritis (LN) in association with renal disease activity, tissue damage and treatment response. We surveyed 52 patients with International Society of Nephrology/Renal Pathology Society (ISN/RPS) class III/IV LN and 20 healthy controls. Renal biopsies were performed at the time of active LN and post-treatment. Patients were classified as clinical responders (CRs) or clinical non-responders based on the American College of Rheumatology (ACR) criteria. Improvement by ≥50% in renal activity index scores defined histological responders (HRs). sAxl levels were elevated in patients compared to controls (median: 18.9 ng/mL), both at baseline (median: 45.7; P<0.001) and post-treatment (median: 41.2 ng/mL; P<0.001). Baseline sAxl levels were higher in patients with class IV (median: 47.7 ng/mL) versus class III (median: 37.5 ng/mL) nephritis (P = 0.008), and showed moderate correlations with albuminuria (r = 0.30, P = 0.030) and creatinine (r = 0.35, P = 0.010). Baseline sAxl levels decreased in CRs (P = 0.002) and HRs (P<0.001), but not in non-responders; levels ≥36.6 ng/mL yielded a >5 times higher probability of histology-based response (odds ratio, OR: 5.5; 95% confidence interval, CI: 1.2-25.1). High post-treatment sAxl levels were associated with worsening in chronicity index scores (P = 0.025); low levels predicted favourable renal outcome (creatinine ≤88.4 μmol/L) 10 years after the baseline renal biopsy (area under the curve: 0.71; 95% CI: 0.54-0.89). In conclusion, sAxl may prove useful as a marker of renal activity, histological response to immunosuppression, and renal damage progression in LN. Persistently high sAxl levels after completion of treatment may be indicative of a need for treatment intensification.

TNF-α and plasma albumin as biomarkers of disease activity in systemic lupus erythematosus

OBJECTIVES

Composite criteria/indices are presently used to diagnose and monitor patients with systemic lupus erythematosus (SLE). Biomarkers for these purposes would be helpful in clinical practice. We therefore evaluated a large panel of cytokines and basic laboratory tests and investigated their performance as discriminators versus controls and as biomarkers of disease activity (DA).

METHODS

We examined 437 patients with SLE, fulfilling American College of Rheumatology-82 criteria, and 322 matched controls. DA was assessed according to both SLE DA Index 2000 (SLEDAI-2K) and SLE Activity Measure (SLAM). British Isles Lupus Activity Group (BILAG) was used to assess renal DA. Additionally, 132 patients self-assessed their Global Disease Activity (PtGDA). Mesoscale Discovery 30-plex cytokine assay and routine blood chemistry was performed on fasting EDTA-plasma.

RESULTS

Of 26 tested biomarkers, we identified TNF-α as the superior discriminator between patients with SLE and controls (median=4.5 pg/mL, IQR=3.1-6.2 vs median=2.3 pg/mL, IQR=2.0-2.8). The strongest correlations to SLEDAI-2K and SLAM were obtained with TNF-α (Spearman rho (ρ)=0.32 and ρ=0.34, respectively), partly driven by the nephritis subgroup, and with p-albumin (ρ=-0.33 and ρ=-0.31, respectively). P-albumin was decreased and TNF-α was increased in patients with kidney involvement (renal BILAG A/B vs C/D/E, p=4×10-16 and p=6×10-9 respectively). IP-10 was increased in patients with joint involvement (SLAM item 24≥2 vs ≤1, p=0.0005) but did not differ when comparing patients with active/inactive kidney involvement. The most powerful correlations to PtGDA was observed with p-albumin (ρ=-0.42), IL-6 (ρ=0.30) and TNF-α (ρ=0.29).

CONCLUSION

TNF-α and p-albumin both performed well as discriminators between patients with SLE and controls and as proxies for DA according to both rheumatologists' and patients' assessments. In particular, renal DA was well reflected by TNF-α. We propose that the TNF-α and p-albumin merit further investigations as clinically useful biomarkers in SLE. We also observed that the pattern of activated cytokines varies with organ involvement.

Plasma biomarkers are associated with renal outcomes in individuals with APOL1 risk variants

G1/G2 variants in the Apolipoprotein L1 (APOL1) gene are associated with end-stage renal disease (ESRD) in people with African ancestry. Plasma biomarkers may have utility for risk stratification in APOL1 high-risk individuals of African ancestry. To evaluate this, we measured tumor necrosis factor receptor 1/2 (TNFR1/2) and kidney injury molecule-1 (KIM1) in baseline plasma specimens from individuals of African ancestry with high-risk APOL1 genotype. Biomarker association with a composite renal outcome of ESRD or 40% sustained decline in estimated glomerular filtration rate (eGFR) was then determined and then assessed as improvement in area under curve. Among the 498 participants, the median age was 56 years, 67.7% were female, and the baseline eGFR was 83.3 ml/min/1.73 m2 with 80 reaching outcome over 5.9 years. TNFR1, TNFR2, and KIM1 at enrollment were independently associated with renal outcome continuously (adjusted hazard ratio 2.0 [95% confidence interval 1.3-3.1]; 1.5 [1.2-1.9]; and 1.6 [1.3-1.9] per doubling in levels, respectively) or by tertiles. The area under the curve significantly improved from 0.75 with the clinical model to 0.79 with the biomarker-enhanced model. The event rate was 40% with all 3 biomarkers elevated (adjusted odds ratio of 5.3 (2.3-12.0) vs. 17% (adjusted odds ratio 1.8 [0.9-3.6] with 1 or 2 elevated and 7% with no biomarkers elevated. Thus, plasma concentrations of TNFR1, TNFR2, and KIM1 are independently associated with renal outcome and improve discrimination or reclassification of African ancestry individuals with a high-risk APOL1 genotype and preserve renal function. Elevation of all markers had higher risk of outcome and can assist with better clinical prediction and improved clinical trial efficiency by enriching event rates.

Autoimmune reactivity to malondialdehyde adducts in systemic lupus erythematosus is associated with disease activity and nephritis

BACKGROUND

Immunoglobulin M (IgM) autoreactivity to malondialdehyde (MDA) protein modifications is part of the natural antibody repertoire in health and may have beneficial functions. In contrast, IgG anti-MDA are increased in chronic inflammation and autoimmunity and may instead have pathogenic properties.

METHODS

Herein, we investigated serum IgG anti-MDA levels by enzyme-linked immunosorbent assay (ELISA) in 398 systemic lupus erythematosus (SLE) patients in the Swedish Karolinska SLE cohort and compared these to findings in 225 US SLE patients from New York University and Johns Hopkins University.

RESULTS

In two independent cohorts, IgG anti-MDA levels correlated positively with disease activity by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI; p < 0.0001, Spearman R = 0.3). Meta-analysis found an odds ratio of 2.7 (confidence interval (CI) 1.9-3.9; p < 0.0001) for high anti-MDA IgG levels with active disease (SLEDAI ≥ 6). Furthermore, IgG anti-MDA correlated directly with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), soluble tumor necrosis factor receptors (sTNFR-1, sTNFR-2), and vascular cell adhesion molecule 1 (VCAM-1) measurements, and inversely with complement factors (C1q, C2, C3, C4). Importantly, IgG anti-MDA levels were significantly elevated in SLE patients with active nephritis (p = 0.0005) and correlated with cystatin C estimated glomerular filtration rate and albuminuria.

CONCLUSIONS

Elevated IgG anti-MDA in SLE patients was associated with high disease activity, with active lupus nephritis, and with biomarkers of systemic inflammation. This natural antibody reactivity may have potential prognostic utility, and may also actively contribute to pathogenesis.