Early Complement Component Deficiency in a Single-Centre Cohort of Pediatric Onset Lupus

Childhood-onset systemic lupus erythematosus: A descriptive and comparative study of clinical, laboratory, and treatment characteristics in two populations

OBJECTIVE

The aim of this study was to characterize childhood-onset systemic lupus erythematosus (SLE) in two large cohorts from Turkey and the United States.

METHODS

Patients diagnosed with childhood-onset SLE who fulfilled the 1997 American College of Rheumatology classification criteria for SLE from four reference centers in Turkey and the University of Pittsburgh School of Medicine in the United States were included in this study. A comparative analysis was conducted to evaluate the similarities and differences in clinical and laboratory features, damage accrual, and treatment experiences between the two populations.

RESULTS

A total of 174 patients with childhood-onset SLE were included in this study (108 patients from Turkey and 66 patients from the United States). The female-to-male ratio was similar between the two cohorts (∼3:1, p = .73). The median age at diagnosis was 11.67 years (2.19-17.93) in the Turkish cohort and 13.68 years (2.74-17.93) in the U.S. cohort (p < .001). Photosensitivity (45.4% and 21.2%; p = .007) and renal involvement (41.7% and 36.4%; p = .045) were higher in the Turkish cohort. Anti-Ro/SSA (34.8% and 15.7%; p < .001), anti-Sm (59.1% and 19.4%; p < .001), and anti-RNP (47.0% and 14.8%; p < .001) positivity was more frequent in the U.S. cohort. Current use of rituximab (37.9% and 1.9%; p < .001) and belimumab (19.7% and 0%; p < .001) was more prevalent in the U.S. cohort, while the use of cyclophosphamide (often according to the low dose Euro-Lupus protocol) throughout the disease course (24.1% and 4.5%; p < .001) was more frequent in the Turkish cohort. SLICC/ACR Damage Index scores were not different between the two cohorts.

CONCLUSION

This study provides detailed clinical and laboratory features of childhood-onset SLE in two independent and geographically divergent cohorts. Our findings suggest an earlier age of disease onset and a higher prevalence of kidney involvement in Turkish patients. Differences in treatment approaches were also noted. However, damage accrual related to SLE does not appear to be different between the two patient populations.

Profile of juvenile systemic lupus erythematosus patients with a special reference to monogenic lupus and lupus nephritis: a cross-sectional study

To study the clinical, laboratory profile and outcome of juvenile Systemic Lupus Erythematosus (jSLE) patients at a tertiary care centre in South India. A retrospective review of the medical records of all jSLE patients visiting the Pediatric Immunology and Rheumatology Unit, Aster CMI Hospital, India from February 2017 to December 2023 was performed. The clinical characteristics, treatment and outcomes were recorded and tabulated. Seventy patients diagnosed with jSLE were included in the study. The female-to-male ratio was 4.4:1. Mean age at onset and delay in diagnosis were 120.1 (+/- 56.8) and 11.7 (+/- 22.7) months respectively. The median follow-up period was 13 months (range 4, 29 months). Nine patients presented with early onset SLE (< 5 years). Most common manifestations were constitutional symptoms (n = 56), followed by haematologic (n = 55), and mucocutaneous(n = 50) involvement. Immunological workup showed SLE-specific antibody positivity in 38 patients, hypocomplementemia in 40 patients, and anti-phospholipid antibody positivity in 13 patients. Mortality was observed in five patients with LN while there was no mortality in the non-nephritis group (p 0.004). C1q deficiency was the most common cause of monogenic lupus seen in 5/9 patients; protein kinase C delta (PRKCD) defect and chronic granulomatous disease (CYBB mutation) were seen in one patient each. We describe a large cohort of jSLE from Southern India. Lupus nephritis was noted in 35.7% of our cohort and had a direct correlation with mortality. 10% of patients had monogenic lupus. Serious infections were more frequent in patients with monogenic lupus.

Vasculitis and vasculopathy associated with inborn errors of immunity: an overview

Systemic autoinflammatory diseases (SAIDs) are disorders of innate immunity, which are characterized by unprovoked recurrent flares of systemic inflammation often characterized by fever associated with clinical manifestations mainly involving the musculoskeletal, mucocutaneous, gastrointestinal, and nervous systems. Several conditions also present with varied, sometimes prominent, involvement of the vascular system, with features of vasculitis characterized by variable target vessel involvement and organ damage. Here, we report a systematic review of vasculitis and vasculopathy associated with inborn errors of immunity.

Sirolimus for the treatment of patients with refractory connective tissue disease-related thrombocytopenia: a pilot study

OBJECTIVE

CTD-related immune thrombocytopenia (CTD-ITP) represents an unmet medical need because the drugs that are available are only partly effective and have considerable side-effects. The aim of this study was to assess the efficacy and safety of sirolimus in refractory CTD-ITP patients.

METHODS

We did a single-arm, open-label, pilot study of sirolimus in patients with CTD-ITP unresponsive to, or intolerant of, conventional medications. Patients received oral sirolimus for 6 months at a starting dose of 0.5-1 mg per day, with dose adjusted according to tolerance and to maintain a therapeutic range of 6-15 ng/ml. The primary efficacy end point was changes in platelet count, and overall response assessed according to the ITP International Working Group Criteria. Safety outcomes included tolerance as assessed by the occurrence of common side-effects.

RESULTS

Between November 2020 and February 2022, 12 consecutively hospitalized patients with refractory CTD-ITP were enrolled and prospectively followed. Of these, six patients (50%) achieved complete response, two (16.7%) achieved partial response, and four (33.3%) were no response under therapy. Three of four patients with primary Sjögren's syndrome and two of three patients with systemic lupus erythematosus achieved overall response. One of two patients with overlapping Sjögren's syndrome and systemic lupus erythematosus achieved complete response at 6 months. No severe drug-related toxicities were observed.

CONCLUSION

Our results do support sirolimus as an alternative regimen for refractory CTD-ITP patients, including systemic lupus erythematosus and primary SS.

Phenotype and disease course differences in monogenic and sporadic childhood lupus

OBJECTIVE

To report the differences in phenotypic characteristics, disease course, and outcome in monogenic and sporadic childhood lupus (SC-lupus) from a single tertiary childhood lupus clinic.

METHODS

A descriptive, observational, cross-sectional study was conducted. Data were retrospectively collected at the last follow-up visit on patients with monogenic lupus proven by genetic variants and SC-lupus seen between June 1997 and July 2022. SC-lupus patients were selected by systematic sampling from lupus patients presenting to our lupus clinic; the first patient was chosen randomly, and the subsequent patients were chosen at intervals of three. Data comprised the clinical and laboratory findings, disease activity using the SLEDAI, and damage measured by the pSDI.

RESULTS

A total of 54 patients with a median disease duration of 6.8 (IQR 3.5-10.5) years were included. There were 27 patients with monogenic lupus and 27 patients with SC-lupus, with a median age at disease onset of 3.5 (IQR 1.0-6.0), and 9.5 (IQR 7.0-11.8), respectively. (p < 0.05). The rate of consanguinity and family history of lupus were higher in monogenic lupus patients. The two groups were comparable. However, monogenic lupus patients showed more gastrointestinal tract symptoms, and failure to thrive (p < 0.05). They also had more infections. The frequency of the autoantibody profile was higher in monogenic lupus patients. Belimumab was more frequently used in monogenic lupus while rituximab in SC-lupus patients. Monogenic lupus patients had a higher mean SLEDAI, but statistically, it was insignificant. Patients with monogenic lupus had greater disease damage, with a higher mean pSDI and a higher mortality rate (p < 0.05).

CONCLUSION

Patients with monogenic lupus are likely to have an early disease onset and a strong family history of lupus, as well as a guarded prognosis, which is likely due to the disease's severity and frequent infections. These differences may be related to the high consanguinity rate and underlying genetic variants.

Current views on lupus in children

PURPOSE OF REVIEW

This manuscript provides an update on clinical and pathophysiological features of juvenile-onset systemic lupus erythematosis (jSLE), challenges applying adult-derived classification criteria, and recent advances in treatment and care.

RECENT FINDINGS

Significant scientific advances have improved the understanding of genetic factors (both genetic causes and risk alleles) and associated phenotypic features. Panels of urine/blood biomarker candidates aid in diagnosing jSLE, monitoring disease activity and predicting treatment response. Available classification criteria have been extensively assessed, with differences in clinical and immunological phenotypes of patients across age groups and ethnicities affecting their performance in jSLE. Therapeutic options remain limited and are based on protocols for adult-onset SLE patients. International efforts to inform development of a treat-to-target (T2T) approach for jSLE have yielded cohort-level evidence that target attainment reduces the risk of severe flare and new damage, and treatment compliance.

SUMMARY

Recent studies have significantly improved our understanding of jSLE pathogenesis, highlighting important differences between jSLE and adult SLE, and providing the basis of biomarker development and target-directed individualized treatment and care. Future work focused on development of a T2T approach in jSLE is eagerly awaited.

Pediatric systemic lupus erythematosus: phagocytic defect and oxidase activity of neutrophils

BACKGROUND

There are limited data on neutrophil function in pediatric-onset systemic lupus erythematosus (pSLE) patients. This study aimed to evaluate phagocytosis and oxidase activity of neutrophils in patients with pSLE.

PATIENTS AND METHODS

Eighty-seven patients with pSLE and 44 controls were enrolled. Phagocytic activity was assayed using pHrodoTMRed E. coli BioParticles Phagocytosis Kit by flow cytometry. Determination of NADPH oxidase activity was carried out by Dihyrdrorhodamine-123 (DHR-123) flow cytometry assay.

RESULTS

Phagocytic activity of patients' neutrophils (mean 76.59%) was lower than that in controls (91.30%) (p < 0.001). Median delta median fluorescence intensity (ΔMFI) and stimulation index (SI) in patients (ΔMFI: 0.09; SI: 2.79) were also decreased compared to controls (ΔMFI: 0.18; SI: 5.00) (p < 0.002; p < 0.001 respectively). Disease activity showed an inverse correlation with phagocytic activity. Oxidase activity was also significantly low (SI DHR < 40) in 16% of patients. No significant correlation was found between oxidative burst and disease activity.

CONCLUSION

Neutrophil function is impaired in patients with pSLE, as evidenced by the markedly reduced phagocytic activity. Phagocytic activity is also inversely correlated with disease activity. The oxidative activity was also reduced but not significantly.

IMPACT

Neutrophil phagocytic function is impaired in pediatric-onset systemic lupus erythematosus (pSLE). There is an inverse correlation between disease activity in pSLE and phagocytic activity. NADPH oxidase activity in patients with pSLE did not show significant correlation with disease activity.

The yin and the yang of early classical pathway complement disorders

The classical pathway of the complement cascade has been recognized as a key activation arm, partnering with the lectin activation arm and the alternative pathway to cleave C3 and initiate the assembly of the terminal components. While deficiencies of classical pathway components have been recognized since 1966, only recently have gain-of-function variants been described for some of these proteins. Loss-of-function variants in C1, C4, and C2 are most often associated with lupus and systemic infections with encapsulated bacteria. C3 deficiency varies slightly from this phenotypic class with membranoproliferative glomerulonephritis and infection as the dominant phenotypes. The gain-of-function variants recently described for C1r and C1s lead to periodontal Ehlers Danlos syndrome, a surprisingly structural phenotype. Gain-of-function in C3 and C2 are associated with endothelial manifestations including hemolytic uremic syndrome and vasculitis with C2 gain-of-function variants thus far having been reported in patients with a C3 glomerulopathy. This review will discuss the loss-of-function and gain-of-function phenotypes and place them within the larger context of complement deficiencies.

Systemic lupus erythematosus - Are children miniature adults?

Systemic lupus erythematosus (SLE) is a systemic autoimmune/inflammatory disease that can affect any organ system and cause significant damage and organ failure. Disease-onset during childhood (juvenile-onset SLE) is associated with less typical autoantibody patterns, diffuse organ involvement, more damage already at diagnoses, and a higher need of immunomodulating treatment, including corticosteroids, when compared to adult-onset SLE. Differences in the molecular pathophysiology within SLE, and over-representation of patients with "genetic SLE" contribute to differences in clinical presentation and treatment responses between children and adults. This manuscript summarizes currently available literature focusing on parallels and differences between clinical pictures, known pathomechanisms, and available treatment options in juvenile- versus adult-onset SLE.

[Systemic lupus erythematosus-are children small adults?]

Systemic lupus erythematosus (SLE) is a systemic inflammatory disease that can affect any organ of the human body and cause significant damage. As compared to patients with adult-onset SLE, children and young people (juvenile SLE) more frequently experience extensive diffuse organ involvement, more organ damage at diagnoses, and resistance to immunomodulatory treatment. This manuscript emphasizes parallels and differences between the clinical pictures, known pathomechanisms, and available treatment options of juvenile and adult-onset SLE.

Monogenic lupus with homozygous C4A deficiency presenting as bronchiectasis and immune-mediated thrombocytopenia

Monogenic lupus is a subset of lupus caused by single-gene disorders, integrating the paradoxical combination of autoimmunity and immunodeficiency. Pulmonary manifestations with recurrent pneumonia and bronchiectasis have rarely been described as the predominant presentation of juvenile lupus and may suggest an alternate differential like primary immunodeficiency, especially in early childhood. We describe a case of 10-year girl who presented with a history of recurrent pneumonia, arthritis, alopecia, and poor weight gain for the past 2 years. On examination, she had respiratory distress, bilateral diffuse crackles and arthritis of the small joints of hands. Lab investigations showed pancytopenia, low complement levels and high titers of ANA and anti-dsDNA antibodies. The patient was diagnosed with juvenile lupus. Imaging studies revealed evidence of multiple lobar collapse and consolidation with bronchiectasis. She was started on steroids, HCQ and supportive measures for bronchiectasis. The child reported relief in initial symptoms of lupus on follow-up but developed recurrent thrombocytopenia requiring IVIG and escalating the doses of oral steroids. The young age and atypical presentation prompted a screening for monogenic lupus, and clinical exome sequencing revealed a novel homozygous missense variation in exon 20 of the C4Agene with clinically reduced C4 levels, consistent with the diagnosis of C4A deficiency.

New Horizons in the Genetic Etiology of Systemic Lupus Erythematosus and Lupus-Like Disease: Monogenic Lupus and Beyond

Systemic lupus erythematosus (SLE) is a clinically and genetically heterogeneous autoimmune disease. The etiology of lupus and the contribution of genetic, environmental, infectious and hormonal factors to this phenotype have yet to be elucidated. The most straightforward approach to unravel the molecular pathogenesis of lupus may rely on studies of patients who present with early-onset severe phenotypes. Typically, they have at least one of the following clinical features: childhood onset of severe disease (<5 years), parental consanguinity, and presence of family history for autoimmune diseases in a first-degree relative. These patients account for a small proportion of patients with lupus but they inform considerable knowledge about cellular pathways contributing to this inflammatory phenotype. In recent years with the aid of new sequencing technologies, novel or rare pathogenic variants have been reported in over 30 genes predisposing to SLE and SLE-like diseases. Future studies will likely discover many more genes with private variants associated to lupus-like phenotypes. In addition, genome-wide association studies (GWAS) have identified a number of common alleles (SNPs), which increase the risk of developing lupus in adult age. Discovery of a possible shared immune pathway in SLE patients, either with rare or common variants, can provide important clues to better understand this complex disorder, it's prognosis and can help guide new therapeutic approaches. The aim of this review is to summarize the current knowledge of the clinical presentation, genetic diagnosis and mechanisms of disease in patents with lupus and lupus-related phenotypes.

Complement deficiency in pediatric-onset systemic lupus erythematosus

BACKGROUND:

Pediatric-onset systemic lupus erythematosus (pSLE) accounts for about 10%–20% of all patients with SLE. Deficiencies in early complement components of the classical pathway are the strong genetic risk factor for the development of SLE. In this study, clinical and laboratory manifestations of both complement-deficient and normal complement pSLE patients were compared.

MATERIALS AND METHODS:

To investigate clinical and immunological manifestations of pSLE in Iran, 36 consecutive pSLE patients (onset before 18 years) who were followed up over a period of 2 years, were studied. Complement C1q and C2 levels were measured using radial immunodifusion assay and complement C3 and C4 levels were measured using nephelometry. Medical records were retrospectively evaluated from patient database of Children Medical Center Hospital. Data were assessed through descriptive analysis (confidence interval = 95%), paired t-test, and Pearson correlation test.

RESULTS:

Twenty-one patients (58%) had at least one component of complement deficiency. Ten patients (27%) had low C1q level, 11 patients (30.5%) had low C2, nine patients (25%) had low C3, and four patients (11%) had low C4 level. Serum level of complement in pSLE was significantly lower than the control group, except C4 (P = 0.005). The low C1q patients had an earlier age of onset of disease (P < 0.0001). The cutaneous manifestations were more frequent and much more severe in pSLE with low complement (100% vs. 73%). The frequency of renal and musculoskeletal symptoms was equal, but renal morbidity was more common in pSLE with low complement. Positivity for anti-ds-DNA was less common in pSLE with low complement (71% vs. 86%).

CONCLUSION:

In pSLE patients with early disease onset and more aggressive SLE manifestations and negative anti-ds-DNA test, complement deficiency should be considered.

Whole Exome Sequencing in Early-onset Systemic Lupus Erythematosus

Objective.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder. Early-onset, familial, and/or syndromic SLE may reveal monogenic pathologies. The aim of this study was to examine genetic associations in patients with early-onset or familial SLE.

Methods.

We enrolled 7 SLE cases (from different families) with disease onset ≤ 5 years of age and family history consistent with an autosomal recessive inheritance. Whole exome sequencing (WES) was performed in 6 index cases. Suspected variants were confirmed by Sanger sequencing. We did not perform WES in 1 patient who had features similar to the first 3 cases; only the exons of C1QA, C1QB, and C1QC were screened with Sanger sequencing.

Results.

We demonstrated 2 novel and 3 previously reported variants in genes associated with SLE: a homozygous non-sense alteration (c.622C>T/p.Gln208Ter) in C1QA in 2 patients; homozygous non-sense alteration (c.79C>T/p.Gln27Ter) in C1QC in 1 (novel variant); homozygous missense alteration (c.100G>A/p.Gly34Arg) in C1QC in 1; homozygous missense alteration (c.1945G>C/p.Ala649Pro) in C1S in 1 (novel variant); and homozygous frameshift alteration (c.289_290delAC/p.Thr97Ilefs*2) in DNASE1L3 in 1 patient. Further, in 1 patient, we determined a strong candidate variant in HDAC7 (histone decetylase 7).

Conclusion.

Five patients had homozygous alterations in genes coding early complement proteins. This may lead to decreased clearance of apoptotic bodies. One patient had DNASE1L3 variant, which functions in the clearance of self-antigens. In 1 patient, we determined a novel gene that may be important in SLE pathogenesis. We suggest that monogenic causes/associations should be sought in early-onset and/or familial SLE.

The association between expression of IFIT1 in podocytes of MRL/lpr mice and the renal pathological changes it causes: An animal study

Renal damage is the major cause of SLE associated mortality, and IFIT1expression was elevated in SLE cases in accordance of previous studies. Therefore, we conducted an animal study to identify the role of IFIT1 expression in renal pathological changes.18 female MRL/lpr mice and same number of female BALB/c mice were enrolled in present study. Quantitative analysis of urine protein, Complement C3 and C4, and anti-ds DNA antibody were conducted. HE and PAS staining and TEM analysis were employed to observe the pathological changes in renal tissue. Significant elevation on urine protein and anti-dsDNA and reduction on Complement C3 and C4 were observed in MRL/lpr mice when comparing the controls in same age. Staining and TEM analysis observed several pathological changes in glomerulus among MRL/lpr mice, including cellular enlargement, basement membrane thickening, and increased cellularcasts. The linear regression analysis found the optical density of IFIT1 was inversely associated with F-actin, Nephrin, and Podocin, but not Synatopodin. In summary, IFIT1 expression is associated with podocytes damage, and capable of suppressing some proteins essential to glomerular filtration.

Functional mannose binding lectin levels in patients with pediatric onset systemic lupus erythematosus in remission

BACKGROUND

Complement system plays a crucial role in the pathogenesis of systemic lupus erythematosus (SLE). Excessive activation of complement causes tissue injury and SLE occurrence is typically associated with congenital deficiencies of the early components of the classical complement pathway. Mannose-binding lectin (MBL) is recognized as important causative factor in the etio-pathogenesis of SLE and MBL-2 gene has evolved as a candidate gene for SLE susceptibility.

AIM

This study was done to assess the functional MBL (fMBL) level in SLE patients in remission and its co-relation with disease severity and outcome.

METHODS

Functional MBL levels were compared with age and sex matched healthy controls and were correlated with duration of illness,complement levels and anti-double- stranded DNA antibody levels.

RESULTS

Mean fMBL level in patients was found to be 696.19 ± 408.98 U/mL and 579.52 ± 393.87 U/mL in the control group. Four children had very low fMBL levels (< 40 U/mL). Functional MBL levels were higher in patients with SLE even when the disease was in remission as compared to healthy controls, although not statistically significant.

CONCLUSION

Large variation exists in fMBL levels in patients with SLE even when in remission. Very low fMBL levels were found in some children with younger age of onset of SLE, multisystem involvement and severe course of the disease. Positive correlation of MBL levels with anti-ds DNA titers suggest that its values vary with activity and could be a potential biomarker of the disease.

Approach to a Child with Primary Immunodeficiency Made Simple

Primary immunodeficiency disorders (PIDs) are a group of disorders affecting the capability to fight against infection. These include defects in T cells and B cells affecting cell-mediated and humoral immunity, respectively, combined humoral and cell-mediated immunodeficiency, defects in phagocytosis, complement defects, and defects in cytokine or cytokine signalling pathways which are detrimental for immune function. Depending upon the type and severity, age at onset of symptoms can vary from neonatal period to late childhood. Clinically, this group of disorders can involve any organ system of an individual such as respiratory system, gastrointestinal system, skin and mucous membrane, bone and joints, endocrine organs, and nervous system. Common dermatological manifestations include eczema, warts, molluscum contagiosum, mucocutaneous candidiasis, recurrent nonhealing ulcers, skin abscesses, erythroderma, petechiae, and nail changes. The common skin manifestations of various PIDs include eczema (seen in Wiskott-Aldrich syndrome and autosomal dominant hyper IgE syndrome); erythroderma (in Omen syndrome); viral warts or molluscum contagiosum (in autosomal recessive hyper IgE syndrome); chronic mucocutaneous candidiasis (in hyper IgE syndrome, autoimmune polyendocrinopathy candidiasis ectodermal dysplasia syndrome, Th17 cell defects); recurrent nonhealing ulcers (in leucocyte adhesion defect); skin abscesses (in antibody defects, hyper IgE syndrome, and chronic granulomatous disease); petechial or purpuric spots (in Wiskott-Aldrich syndrome).

Systemic Lupus Erythematosus and Deficiencies of Early Components of the Complement Classical Pathway

The complement system plays an important role in the innate and acquired immune response against pathogens. It consists of more than 30 proteins found in soluble form or attached to cell membranes. Most complement proteins circulate in inactive forms and can be sequentially activated by the classical, alternative, or lectin pathways. Biological functions, such as opsonization, removal of apoptotic cells, adjuvant function, activation of B lymphocytes, degranulation of mast cells and basophils, and solubilization and clearance of immune complex and cell lysis, are dependent on complement activation. Although the activation of the complement system is important to avoid infections, it also can contribute to the inflammatory response triggered by immune complex deposition in tissues in autoimmune diseases. Paradoxically, the deficiency of early complement proteins from the classical pathway (CP) is strongly associated with development of systemic lupus erythematous (SLE) - mainly C1q deficiency (93%) and C4 deficiency (75%). The aim of this review is to focus on the deficiencies of early components of the CP (C1q, C1r, C1s, C4, and C2) proteins in SLE patients.