Antinuclear antibodies in sickle cell disease

A Review of the Relationship between the Immune Response, Inflammation, Oxidative Stress, and the Pathogenesis of Sickle Cell Anaemia

Sickle cell anaemia (SCD) is a life-threatening haematological disorder which is predominant in sub-Saharan Africa and is triggered by a genetic mutation of the β-chain haemoglobin gene resulting in the substitution of glutamic acid with valine. This mutation leads to the production of an abnormal haemoglobin molecule called haemoglobin S (HbS). When deoxygenated, haemoglobin S (HbS) polymerises and results in a sickle-shaped red blood cell which is rigid and has a significantly shortened life span. Various reports have shown a strong link between oxidative stress, inflammation, the immune response, and the pathogenesis of sickle cell disease. The consequence of these processes leads to the development of vasculopathy (disease of the blood vessels) and several other complications. The role of the immune system, particularly the innate immune system, in the pathogenesis of SCD has become increasingly clear in recent years of research; however, little is known about the roles of the adaptive immune system in this disease. This review examines the interaction between the immune system, inflammation, oxidative stress, blood transfusion, and their effects on the pathogenesis of sickle cell anaemia.

Oxidized hemoglobin triggers polyreactivity and autoreactivity of human IgG via transfer of heme

Intravascular hemolysis occurs in diverse pathological conditions. Extracellular hemoglobin and heme have strong pro-oxidative and pro-inflammatory potentials that can contribute to the pathology of hemolytic diseases. However, many of the effects of extracellular hemoglobin and heme in hemolytic diseases are still not well understood. Here we demonstrate that oxidized hemoglobin (methemoglobin) can modify the antigen-binding characteristics of human immunoglobulins. Thus, incubation of polyclonal or some monoclonal human IgG in the presence of methemoglobin results in an appearance of binding reactivities towards distinct unrelated self-proteins, including the protein constituent of hemoglobin i.e., globin. We demonstrate that a transfer of heme from methemoglobin to IgG is indispensable for this acquisition of antibody polyreactivity. Our data also show that only oxidized form of hemoglobin have the capacity to induce polyreactivity of antibodies. Site-directed mutagenesis of a heme-sensitive human monoclonal IgG1 reveals details about the mechanism of methemoglobin-induced antigen-binding polyreactivity. Further here we assess the kinetics and thermodynamics of interaction of a heme-induced polyreactive human antibody with hemoglobin and myoglobin. Taken together presented data contribute to a better understanding of the functions of extracellular hemoglobin in the context of hemolytic diseases.

Hyperoxidized Species of Heme Have a Potent Capacity to Induce Autoreactivity of Human IgG Antibodies

The interaction of some human antibodies with heme results in posttranslational acquisition of binding to various self- and pathogen-derived antigens. The previous studies on this phenomenon were performed with oxidized heme (Fe³⁺). In the present study, we elucidated the effect of other pathologically relevant species of heme, i.e., species that were formed after contact of heme with oxidizing agents such as hydrogen peroxide, situations in which heme's iron could acquire higher oxidation states. Our data reveal that hyperoxidized species of heme have a superior capacity to heme (Fe³⁺) in triggering the autoreactivity of human IgG. Mechanistic studies demonstrated that oxidation status of iron was of critical importance for the heme's effect on antibodies. We also demonstrated that hyperoxidized heme species interacted at higher affinities with IgG and that this binding occurred through a different mechanism as compared to heme (Fe³⁺). Regardless of their profound functional impact on the antigen-binding properties of antibodies, hyperoxidized species of heme did not affect Fc-mediated functions of IgG, such as binding to the neonatal Fc receptor. The obtained data contribute to a better understanding of the pathophysiological mechanism of hemolytic diseases and of the origin of elevated antibody autoreactivity in patients with some hemolytic disorders.

Risk of vaso-occlusive episodes in patients with sickle cell disease exposed to systemic corticosteroids: a comprehensive review

INTRODUCTION

Sickle cell disease (SCD) is the most frequent inherited disorder in the world. It is caused by a single amino acid mutation on the beta-globin chain, which lead to red blood cell deformation, haemolysis, and chronic inflammation. Clinical consequences are vaso-occlusives crisis, acute chest syndrome, thrombosis, infection, and chronic endothelial injury.

AREAS COVERED

Corticosteroids are an old therapeutic class, that are inexpensive and widely available, which can be administered in different forms. Their adverse effects are numerous and well-known. This class could appear to be useful in SCD treatment due to its anti-inflammatory effect. Moreover, corticosteroids remain an essential therapeutic class for many indications, besides SCD. Although specific adverse effects of corticosteroids have been suspected in SCD patients for decades, recent papers has reported strong evidence of specific and severe adverse effects in this population. Based on a literature review, we will discuss pathophysiological considerations, consequences, and practical use of corticosteroids in SCD.

EXPERT OPINION

High corticosteroid doses, for any indication , induce vaso-occlusive crises, acute chest syndrome, and re-hospitalization in patients with SCD. There is no evidence of any benefits of corticosteroid use in the SCD acute events. Prevention by hydroxyurea and/or red blood cell transfusion or exchange should be discussed when corticosteroid use is indispensable.

Autoimmune disease and sickle cell anaemia: 'Intersecting pathways and differential diagnosis'

Sickle cell disease (SCD) is an inherited disorder, which occurs due to a single gene mutation. It has multisystemic manifestations, affecting millions of people worldwide. The effect of SCD on joints and musculature can overlap with clinical features of autoimmune disease (AD). It is therefore difficult for clinical haematologists and physicians treating SCD patients to discriminate between these two conditions clinically. A delay in diagnosis leads to untreated symptoms and treatment differs considerably. An accurate knowledge of clinical findings and laboratory results of AD and SCD can help physicians avoid this. In the review that follows, we examine the existing literature on SCD and AD, and describe the features that may distinguish SCD and autoimmune disease such as systemic lupus erythematosus and rheumatoid arthritis. We aim to guide clinical haematologists and physicians towards a more rapid diagnosis of AD in sickle cell anaemia patients, by correct interpretation of the clinical assessment and commonly available diagnostics.

Immune mechanisms involved in sickle cell disease pathogenesis: current knowledge and perspectives

Sickle cell disease (SCD) is caused by a single point mutation in the β-chain of the hemoglobin gene that results in the replacement of glutamic acid with valine in the hemoglobin protein. However, recent studies have demonstrated that alterations in several other genes, especially immune related genes, may be associated with complications of SCD. In fact, higher chronic inflammatory status is related to more severe clinical symptoms in SCD patients, suggesting crucial roles of the immune system in SCD physiopathology. Nevertheless, although participation of innate immune cells in SCD pathogenesis has been broadly and extensively described, little is known about the roles of the adaptive immune system in this disease. In addition, the influence of treatments on the immune system of SCD patients and their complications (such as alloimmunization) are not yet completely understood. Thus, we reviewed the current knowledge about the immune mechanisms involved in SCD pathogenesis. We suggest recommendations for future studies to allow for a broader understanding of SCD pathogenesis, helping in the development of new therapies and improvement in the life quality and expectancy of patients.

Serum Immunoglobulin Levels in Children with Sickle Cell Disease: A Large Prospective Study

Over the past 3 decades, the pediatric department of the university Intercommunal Créteil hospital, a referral center for sickle cell disease (SCD), has prospectively evaluated immunoglobulin (Ig) levels in a cohort of 888 children with SCD, including 731 with severe sickle genotypes (HbSS and HbSβ⁰ thalassemia) and 157 with milder genotypes (HbSC and HbSβ⁺ thalassemia). We found consistent sickle genotype differences in levels of IgG and IgA, with increased levels of IgA and IgG in the severe versus milder genotype, from early childhood to late adolescence. Additionally, our results revealed a low serum IgM level, irrespective of sickle genotype. Finally, we found that IgA and IgG levels were significantly increased after therapeutic intensification with hydroxyurea but were stabilized in children receiving a transfusion program. The mechanisms contributing to these changes in Ig levels are unclear as is their clinical significance. We believe they should be further investigated.

Sickle cell disease: a case report of renal amyloidosis

BACKGROUND

The development of proteinuria and reduced glomerular filtration rate is associated with higher mortality among patients with sickle cell disease (SCD). AA amyloidosis, also associated with increased mortality, in SCD is rare. We present a case of a woman with homozygous sickle cell disease with nephrotic syndrome and antibodies to double stranded DNA without clinical features of systemic lupus erythematosus. Kidney biopsy reveals AA amyloidosis and is the first report of concomitant AA amyloidosis with antibodies to double stranded DNA in SCD.

CASE PRESENTATION

A 40-year-old Central African woman with homozygous sickle cell disease and history of vaso-occlusive pain crises undergoes kidney biopsy for nephrotic-range proteinuria. Kidney biopsy reveals AA type amyloidosis, which is a rare manifestation of SCD in the kidney. Her anemia worsens with an ACE inhibitor, initiated to reduce proteinuria and limit GFR decline, so it was discontinued. Hydroxyurea, shown to decrease the frequency of vaso-occlusive crises and lower proteinuria, was subsequently initiated but then discontinued due to worsening anemia. Unfortunately, her glomerular filtration rate worsens.

CONCLUSIONS

AA amyloidosis and antibodies to double stranded DNA can occur in sickle cell disease. ACE inhibition and hydroxyurea decrease proteinuria so they may limit progression of chronic kidney disease. Hydroxyurea also decreases frequency of vaso-occlusive pain crises so it might be helpful in limiting progression of renal AA amyloidosis. However, further studies are needed to determine optimal treatment strategies for AA amyloidosis in sickle cell disease.

Coexistent sickle-cell anemia and autoimmune disease in eight children: pitfalls and challenges

BACKGROUND

Patients with sickle cell disease (SCD) present a defective activation of the alternate complement pathway that increases the risk of infection and is thought to predispose to autoimmune disease (AID). However, coexisting AID and SCD is rarely reported, suggesting possible underdiagnosis due to an overlapping of the symptoms.

STUDY DESIGN

Among 603 patients with SCD followed between 1999 and June 2016, we retrospectively searched for patients with coexisting SCD and AID.

RESULTS

We identified 8 patients aged from 7 to 17 years diagnosed with AID; juvenile idiopathic arthritis (n = 3), systemic lupus erythematosus (n = 2), Sjögren's syndrome (n = 1) and autoimmune hepatitis (n = 2). The diagnosis of AID was often delayed due to similarities of the symptoms with those of SCD. Patients treated with steroids experienced multiple vaso-occlusive crises and received prophylactic chronic blood transfusions when it was possible. Tolerance to other immunosuppressive and biological treatments, such as anti-TNF agents, was good. A remission of AID was achieved in 4 patients, without worsening the course of the SCD. One patient underwent a geno-identical hematopoietic stem cell transplantation that cured both diseases. Another one underwent a successful liver transplantation.

CONCLUSION

Coexistence of AID and SCD generates diagnostic and therapeutic challenges. Early diagnosis of AID is important to define the best treatment, which may include targeted biological therapy.

Systemic lupus erythematosus associated with sickle-cell disease: a case report and literature review

Introduction

The occurrence of systemic lupus erythematosus has been only rarely reported in patients with sickle-cell disease.

Case presentation

We describe the case of a 23-year-old North-African woman with sickle-cell disease and systemic lupus erythematosus, and discuss the pointers to the diagnosis of this combination of conditions and also present a review of literature. The diagnosis of systemic lupus erythematosus was delayed because our patient’s symptoms were initially attributed to sickle-cell disease.

Conclusions

Physicians should be alerted to the possible association of sickle-cell disease and systemic lupus erythematosus so as not to delay correct diagnosis and initiation of appropriate treatment.

Reversible diffuse neurological deficits in systemic lupus erythematosus: Report of a case

We report a case of lupus presenting with focal as well as diffuse neurological deficits with intracranial and subarachnoid haemorrhages and diffuse hyperintense lesions in T2-weighted and fluid-attenuated inversion recovery images of brain magnetic resonance imaging proved by further investigation as demyelination, which completely recovered with intravenous methylprednisolone therapy. During the patient’s hospital stay there was one episode of transient hypertensive episode lasting a few hours, promptly reverting to normal with low-dose ramipril therapy. Complete neurological and radiological recovery of such diffuse leucoencephalopathy-like central nervous system lesions has been rarely reported before.

High titers of autoantibodies in patients with sickle-cell disease

OBJECTIVE

Frequency and titers of autoantibodies in patients with sickle-cell disease (SCD) have been reported as relatively high. In a prospective study of 88 patients, we examined this "hyper-autoreactivity" and its clinical consequences.

METHODS

For 1 year, patients with SCD were screened for the presence in their serum of antinuclear, anti-double-stranded DNA, antiextractible nuclear antigens, anticardiolipin antibodies, and rheumatoid factors. A population of 85 sex-matched individuals of similar ethnic origin served as controls.

RESULTS

Whereas prevalence of autoantibodies did not differ between the 2 groups, the type and rate of antinuclear antibodies were different. Autoantibodies from the SCD patients showed various immunofluorescence patterns, whereas only speckled patterns at low titers were present in controls. No antibody specificity was found in either group. SCD patients and controls displayed similar rates of anticardiolipin antibodies, but the SCD patients tended to be more frequently positive for rheumatoid factors. Six-year followup of the SCD patients did not provide any clinical evidence for onset of an autoimmune disease, except for 1 patient who developed rheumatoid arthritis, with increasing antinuclear antibodies followed by emergence of specific markers 5 years later.

CONCLUSION

Patients with SCD displayed high titers of autoantibodies. This observation may be due only to immune activation and/or dysfunction in SCD, as neither pathogenic specificity of autoantibodies nor autoimmune clinical signs appeared in the majority of cases in our study.

Coexisting Systemic Lupus Erythematosus and Sickle Cell Disease

Systemic lupus erythematosus (SLE) and sickle cell disease (SCD) are relatively common disorders with comparable prevalence among blacks. The coexistence of these 2 conditions in the same individual appears to be rare. We report 4 cases of coexisting SLE and SCD. These patients displayed a broad spectrum of musculoskeletal, central nervous system, and renal complications that may be associated with either SCD or SLE. Because of a substantial overlap between the clinical manifestations of these 2 disorders, the diagnosis of SLE in patients with SCD may be difficult to establish and is often delayed. Up to 23% of patients with SCD may have antinuclear antibodies. All patients in this series had antecedent SCD but new important complications from SLE.

Antinuclear antibodies in children with chronic nonspecific complaints

Children who are chronically complaining nonspecific symptoms such as headache, fatigue, abdominal pain, and low grade fever are commonly seen in daily pediatric outpatient clinics. Some of them are unable to go to school and are diagnosed as school refusal by physicians or educational staff. On the other hand, there are children who do not fulfill any criteria of collagen diseases and whose anti-nuclear antibodies (ANA) are found to be positive. Some of these children have chronic nonspecific complaints. We prospectively studied the prevalence of ANA in children who visited a pediatric outpatient clinic because of chronic nonspecific complaints. Surprisingly, 74 out of 140 symptomatic children (52.4%) were positive for ANA, while only 5 out of 82 healthy control children (6.1%) were positive (p < 0.0001). 39 of 74 ANA positive patients (52.1%) have low ANA titers < or = 1:80, nevertheless 36 patients (47.9%) have high ANA titers > or = 1:160. ANA fluorescent patterns were homogeneous and speckled in 75.3%, speckled in 17.6% and others in 6.8%. ANA positive patients tended to have general fatigue and low grade fever, while gastrointestinal problems such as abdominal pain and diarrhea and orthostatic dysregulation symptoms were commonly seen in ANA negative patients. Children who were unable to go to school more than 1 day a week were seen significantly more in ANA positive patients than in negative patients. Autoantibody analysis using Western immunoblot revealed that 26 out of 63 ANA positive sera (41.3%) had antibodies to the 62 kD protein which had not been previously noticed. These data suggest that autoimmune mechanism may play a role in childhood chronic nonspecific symptoms. We therefore propose a new disease entity of the autoimmune fatigue syndrome in children. When chronically complaining children visit a pediatric out-patient clinic, immunological approaches should be considered before they are discriminated as school refusal or having psychogenic disorders.