The relationship between anti-C-reactive protein and disease activity in patients with systemic lupus erythematosus

The Role of Anti-mCRP Autoantibodies in Lupus Nephritis

Background

Lupus nephritis is characterized by multiple autoantibodies production. However, there are few autoantibodies associated with disease activity and prognosis. CRP exists in at least two conformationally distinct forms: native pentameric C-reactive protein (pCRP) and modified/monomeric CRP (mCRP). Autoantibodies against mCRP are prevalent in sera of patients with lupus nephritis and are reported to be pathogenic.

Summary

The levels of serum anti-mCRP autoantibodies are associated with clinical disease activity, tubulointerstitial lesions, treatment response, and prognosis in patients with lupus nephritis. The key epitope of mCRP was amino acid 35-47. Furthermore, emerging evidence indicated that anti-mCRP autoantibodies could participate in the pathogenesis of lupus nephritis by forming in situ immune complexes or interfering with the biological functions of mCRP, such as binding to complement C1q and factor H.

Key Messages

Here, we review the recent advances in the prevalence, clinical-pathological associations, and potential pathogenesis of anti-mCRP autoantibodies in lupus nephritis, which may provide a promising novel therapeutic strategy for lupus nephritis.

Recurrent lupus enteritis in a child-chase the calm before the storm

Systemic lupus erythematosus (SLE) is a complex multisystemic autoimmune disease. Lupus enteritis (LE), one of the less commonly described manifestations of childhood SLE, presents with relatively nonspecific clinical and laboratory features. In addition, recurrent episodes of LE occurring in temporal proximity are rare in children. Presence of disease activity at other sites (which may not be seen universally) supports the diagnosis of LE in an appropriate setting. Because of its potential role to cause ischemic complications, early recognition and prompt treatment are necessary for a good outcome. Herein, we describe a child with recurrent LE with an interval of about 3 months between the first and the second episode. The first episode correlated with systemic disease activity and bowel thickening was noted on abdominal ultrasonography. This episode was successfully managed with intravenous methylprednisolone pulse therapy. Conversely, the second episode was not associated with significant clinical and laboratory evidence of disease activity at other sites and the initial abdominal ultrasonography was non-contributory. Diagnostic and therapeutic delays, hence, led to the development of fatal complications. We highlight that a high index of suspicion of LE and a timely aggressive treatment is imperative for optimal outcomes even in rare pediatric cases of recurrent LE that may have normal imaging findings initially and may not be associated with systemic lupus erythematosus disease activity index (SLEDAI).

A Review of Anti-C Reactive Protein Antibodies in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE), the prototype autoimmune disease, is characterized by the production of a plethora of autoantibodies with various roles in the development of disease-related tissue damage. C-reactive protein (CRP) is an acute phase reactant with a pentameric structure. Under acidic or alkaline conditions, or when urea levels are high and/or calcium levels are low, the pentamer (pCRP) dissociates irreversibly into monomeric CRP (mCRP) and exposes new epitopes (neo-CRP). Importantly, anti-mCRP (but not anti-pCRP) antibodies have been described in patients with SLE, their prevalence varying from 4% to 78% in different cohorts. Numerous studies have investigated the relationship between autoantibodies directed against CRP (anti-CRP) and disease activity as well as their association with lupus nephritis (LN), frequently reporting discrepant findings. The main objective of the present review is to describe the role of anti-mCRP antibodies in SLE according to the currently available data.

Anti-Pentraxin Antibodies in Autoimmune Diseases: Bystanders or Pathophysiological Actors?

Pentraxins are soluble innate immunity receptors involved in sensing danger molecules. They are classified as short (CRP, SAP) and long pentraxin subfamilies, including the prototypic long pentraxin PTX3. Pentraxins act mainly as bridging molecules favoring the clearance of microbes and dead cells. They are also involved in many other biological processes, such as regulation of complement activation, inflammation and tissue homeostasis. Autoantibodies directed against pentraxins have been reported in various autoimmune diseases, especially in systemic lupus erythematosus and ANCA-associated vasculitis. In this review, we review the main biological characteristics and functions of pentraxins and summarize data concerning autoantibodies directed against pentraxins in the context of autoimmune diseases and discuss their potential pathological role.

Infections in hospitalized children with newly diagnosed systemic lupus erythematosus in underresourced areas

Background

The administration of induction immunosuppressive therapy to children with newly diagnosed systemic lupus erythematosus (SLE) and concurrent infections can lead to unfavourable outcomes. This study was conducted to describe characteristics of infections occurring before the initiation of immunosuppressants in hospitalized children with newly diagnosed SLE in underresourced areas.

Methods

Medical records of paediatric patients with the diagnosis of SLE, who were admitted to a university-based hospital from 2002 to 2018, were reviewed. Only patients younger than 18 years of age with newly diagnosed SLE were included in the study. The primary outcome was infection before the administration of immunosuppressants. Logistic regression analysis was used to determine factors associated with infection and adjusted odds ratio (OR). The diagnostic accuracy of CRP was assessed.

Results

Infections were confirmed in 52/124 (41.9%) children. Pathogens were identified in 24 (46.2%) patients with bacterial predominance. The most common site was respiratory infections (36.5%). Fever and serosal involvement were more prevalent in patients with infection. Serum CRP levels were significantly higher in patients with infection than in those without infection (median 5.5 mg/L (interquartile range (IQR) 3.6–76.3 mg/L) vs. 3.5 mg/L (IQR 3.0–3.6 mg/L), p = 0.004). When a positive CRP level of >5 mg/L was used, positive CRP was found with a higher prevalence in patients with infection and was independently associated with infection (adjusted odds ratio (OR) = 28.6, 95% confidence interval (CI) 2.3–350.6; p = 0.009). Patients with infection had a longer hospital stay than patients without infection (median 20 days (IQR 13–25 days) vs. 15 days (IQR 9–24 days), p = 0.04). Sensitivity, specificity, positive predictive value and negative predictive value with 95% CI of CRP >5 mg/L were 62.5% (35.4–84.8%), 88.9% (65.3–98.6%), 80.3% (51.0–94.1%) and 76.6% (63.1–86.3%), respectively.

Conclusions

Infections were common among hospitalized children with newly diagnosed SLE. Children with infections had a prolonged course of hospitalization. Positive CRP was associated with a predisposition towards infection. However, the diagnostic accuracy of CRP requires further validation in a larger study.

Changes in MiRNA-5196 Expression as a Potential Biomarker of Anti-TNF-α Therapy in Rheumatoid Arthritis and Ankylosing Spondylitis Patients

In this study, we analysed the expression level of sera circulating miRNA-5196 in rheumatoid arthritis (RA) and ankylosing spondylitis (AS) patients before and after tumor necrosis factor (TNF)-α therapy as biomarkers predicting positive treatment outcome. We enrolled 10 RA patients, 13 AS patients, and 12 healthy individuals in the study. The expression of miRNA-5196 was measured by real-time polymerase chain reaction before and after anti-TNF-α therapy. Disease activity of RA patients was assessed using disease activity score 28 (DAS28), whereas ankylosing spondylitis DAS (ASDAS) was used in AS patients. MiRNA-5196 expression was significantly higher in patients with RA and AS before TNF-α therapy than in those following anti-TNF-α therapy and healthy controls. Changes in miRNA-5196 expression positively correlated with delta DAS28 or delta ASDAS, respectively, following TNF-α therapy. In contrast, changes in C-reactive protein (CRP) levels in RA and AS patients did not positively correlate with DAS28 or ASDAS changes. Receiver-operating characteristic analysis showed better diagnostic accuracy of miRNA-5196 expression both in RA (area under curve (AUC) = 0.87, p = 0.055) and AS patients (AUC = 0.90, p = 0.050) compared to CRP levels in RA (AUC = 0.75, p = 0.201) and AS patients (AUC = 0.85, p = 0.086) upon biologic therapy treatment. Finding novel biomarkers, including miRNA-5196 which allow to predict and monitor anti-TNF-α response, would be of clinical value especially during the early phase of RA or AS development.