The association of low complement with disease activity in systemic sclerosis: a prospective cohort study

Application and performance of disease activity indices proposed for patients with systemic sclerosis in an international cohort of patients with juvenile systemic sclerosis

Objectives

Juvenile systemic sclerosis is a rare childhood disease. Three disease activity indices have been published for adult patients with systemic sclerosis: the European Scleroderma Study Group Index, a modified version of the European Scleroderma Study Group Index and the revised European Scleroderma Trials and Research index. The objective of this study was to determine the feasibility and performance of the three disease activity indices in a prospectively followed cohort of patients with juvenile systemic sclerosis.

Methods

The analysis cohort was selected from the prospective international inception cohort enrolling juvenile systemic sclerosis patients. The correlation of the disease activity indices with the physicians' and the patients' global assessment of disease activity was determined. The disease activity indices were compared between patients with active and inactive disease. Sensitivity to change between 6- and 12-month follow-up was investigated by mixed models.

Results

Eighty percent of the 70 patients had a diffuse cutaneous subtype. The revised European Scleroderma Trials and Research index was highly correlated with the physician-reported global disease activity/parents-reported global disease activity (r = 0.74/0.64), followed by the European Scleroderma Study Group activity index (r = 0.61/0.55) and the modified version of the European Scleroderma Study Group activity index (r = 0.51/0.43). The disease activity indices significantly differed between active and inactive patients. The disease activity indices showed sensitivity to change between 6- and 12-month follow-up among patients who improved or worsened according to the physician-reported global disease activity and the parents-reported global disease activity.

Conclusion

Overall, no disease activity score is superior to the other, and all three scores have limitations in the application in juvenile systemic sclerosis patients. Furthermore, research on the concept of disease activity and suitable scores to measure disease activity in patients with juvenile systemic sclerosis is necessary in future.

Complement component C4 structural variation and quantitative traits contribute to sex-biased vulnerability in systemic sclerosis

Copy number (CN) polymorphisms of complement C4 play distinct roles in many conditions, including immune-mediated diseases. We investigated the association of C4 CN with systemic sclerosis (SSc) risk. Imputed total C4, C4A, C4B, and HERV-K CN were analyzed in 26,633 individuals and validated in an independent cohort. Our results showed that higher C4 CN confers protection to SSc, and deviations from CN parity of C4A and C4B augmented risk. The protection contributed per copy of C4A and C4B differed by sex. Stronger protection was afforded by C4A in men and by C4B in women. C4 CN correlated well with its gene expression and serum protein levels, and less C4 was detected for both in SSc patients. Conditioned analysis suggests that C4 genetics strongly contributes to the SSc association within the major histocompatibility complex locus and highlights classical alleles and amino acid variants of HLA-DRB1 and HLA-DPB1 as C4-independent signals.

Innate Immunity: A Balance between Disease and Adaption to Stress

Since first being documented in ancient times, the relation of inflammation with injury and disease has evolved in complexity and causality. Early observations supported a cause (injury) and effect (inflammation) relationship, but the number of pathologies linked to chronic inflammation suggests that inflammation itself acts as a potent promoter of injury and disease. Additionally, results from studies over the last 25 years point to chronic inflammation and innate immune signaling as a critical link between stress (exogenous and endogenous) and adaptation. This brief review looks to highlight the role of the innate immune response in disease pathology, and recent findings indicating the innate immune response to chronic stresses as an influence in driving adaptation.

Beyond Systemic Lupus Erythematosus and Anti-Phospholipid Syndrome: The Relevance of Complement From Pathogenesis to Pregnancy Outcome in Other Systemic Rheumatologic Diseases

Evidence about the relevance of the complement system, a highly conserved constituent of the innate immunity response that orchestrates the elimination of pathogens and the inflammatory processes, has been recently accumulated in many different rheumatologic conditions. In rheumatoid arthritis, complement, mainly the classical pathway, contributes to tissue damage especially in seropositive subjects, with complement activation occurring in the joint. Data about complement pathways in psoriatic arthritis are dated and poorly consistent; among patients with Sjögren syndrome, hypocomplementemia exerts a prognostic role, identifying patients at risk of extra-glandular manifestations. Hints about complement involvement in systemic sclerosis have been recently raised, following the evidence of complement deposition in affected skin and in renal samples from patients with scleroderma renal crisis. In vasculitides, complement plays a dual role: on one hand, stimulation of neutrophils with anti-neutrophil cytoplasmic antibodies (ANCA) results in the activation of the alternative pathway, on the other, C5a induces translocation of ANCA antigens, favouring the detrimental role of antibodies. Complement deposition in the kidneys identifies patients with more aggressive renal disease; patients with active disease display low serum levels of C3 and C4. Even though in dermatomyositis sC5b-9 deposits are invariably present in affected muscles, data on C3 and C4 fluctuation during disease course are scarce. C3 and C1q serum levels have been explored as potential markers of disease activity in Takayasu arteritis, whereas data in Behçet disease are limited to in vitro observations. Pregnancies in women with rheumatologic conditions are still burdened by a higher rate of pregnancy complications, thus the early identification of women at risk would be invaluable. A fine-tuning of complement activation is required from a physiological progression of pregnancy, from pre-implantation stages, through placentation to labour. Complement deregulation has been implicated in several pregnancy complications, such as recurrent abortion, eclampsia and premature birth; low complement levels have been shown to reliably identify women at risk of complications. Given its physiologic role in orchestrating pregnancy progression and its involvement as pathogenic effector in several rheumatologic conditions, complement system is an attractive candidate biomarker to stratify the obstetric risk among women with rheumatologic conditions.

Increased Complement Activation in Systemic Sclerosis Patients with Skin and Lung Fibrosis

Introduction: The involvement of complement system in the phenotypic expression of systemic sclerosis (SSc) is a debated topic. We aimed to assay complement fractions in SSc patients and to correlate their levels with the clinical course of disease. Key points: 1. CH50 is increased in SSc patients compared to HC; 2. Serum C2 levels are increased in SSc patients compared to HC; 3. CH50 may represent a biomarker of skin and lung fibrosis severity in SSc patients. Method: Complement hemolysis 50% (CH50), C2, C3 and C4 levels have been assessed in 85 SSc patients and 47 healthy controls (HC). Results: SSc patients displayed a statistically significant higher value of CH50 [76.3 U/mL (IQR 65.8–89.4 U/mL) vs. 29.6 U/mL (IQR 24.7–34 U/mL); p < 0.0001] and of C2 [26.1 mg/L (IQR 24.1–32.1 mg/L) vs. 22.7 mg/L (IQR 20.6–24.4 mg/L); p < 0.0001] if compared to HC. Patients with diffuse cutaneous SSc (dcSSc) had higher levels of CH50 than patients with limited cutaneous SSc (lcSSc) [83.6 U/mL (IQR 72.3–102.7 U/mL) vs. 71.3 U/mL (IQR 63.7–83.6 U/mL); p = 0.003]. SSc patients with interstitial lung disease (ILD) had higher CH50 levels if compared to SSc patients without ILD [79.6 U/mL (IQR 68.3–97.4 U/mL) vs. 69.7 U/mL (54.6–85.7 U/mL); p = 0.042]. A positive linear correlation existed between CH50 and the modified Rodnan Skin Score (mRSS) (r = 0.285, p = 0.008) and disease severity scale (DSS) (r = 0.285, p = 0.005); a negative linear correlation was demonstrated between CH50 and the diffusing capacity of carbon monoxide (DLco) (r = −0.252, p = 0.012). In multiple linear regression analysis, only DSS was significant (p = 0.01, beta coefficient 2.446). Conclusions: Our results show an increment of CH50 and serum C2 levels in SSc patients in comparison to HC; we retain that CH50 may represent a biomarker of disease severity and of skin and lung fibrosis in these patients.

Usefulness of high-frequency ultrasonography in the evaluation and monitoring of sclerosing dermatoses: a cohort study

BACKGROUND

Monitoring of disease activity in sclerosing dermatoses (SD) can be challenging and tools to support clinical decision-making are lacking.

AIM

To analyse the impact of high-frequency ultrasonography (HFUS) on the clinical management of SD and to describe the US characteristics of disease activity.

METHODS

This was a cohort study of patients with various SD [morphoea, systemic sclerosis (SS) and chronic graft-versus-host disease (cGvHD)] who underwent HFUS between January 2017 and August 2019. HFUS criteria for diagnosing active SD were increased Doppler vascularity and/or meeting all B-mode greyscale US signs of activity. Discordance in SD activity between HFUS and clinical examination was evaluated at the time of the first US assessment. Changes in patient management were instituted after HFUS were recorded.

RESULTS

In total, 72 patients (31 with morphoea, 19 with SS and 22 with cGvHD), who underwent 163 HFUS sessions in total, were included. All HFUS-active morphoea lesions exhibited increased vascularity, and all HFUS-active SS exhibited dermal thickening and dermal hypoechogenicity. HFUS-active cGvHD displayed increased dermal thickness and loss of definition of the dermal-hypodermal junction, and there were signs of panniculitis in 80% of cases and of increased vascularity in 70%. Discordance in disease activity between clinical and HFUS evaluation was found in 17 (23.6%) patients. Changes in clinical management after HFUS were made for 14 (19.4%) patients: treatment discontinuation for 6 patients (42.9%), treatment initiation for 5 (35.7%), medication change for 2 (14.3%) and skin biopsy taken for 1 (7.1%).

CONCLUSION

HFUS seems an efficacious support tool in the monitoring of SD activity with a notable impact on clinical management. Further studies are warranted to evaluate the impact of HFUS-supported management changes on SD outcomes.

[Endothelial dysfunction in thrombotic thrombocytopenic purpura: therapeutic perspectives]

Immune Thrombotic Thrombocytopenic Purpura (iTTP) is a rare but severe disease with a mortality rate of almost 100 % in the absence of adequate treatment. iTTP is caused by a severe deficiency in ADAMTS13 activity due to the production of inhibitory antibodies. Age has been shown to be a major prognostic factor. iTTP patients in the elderly (60yo and over) have more frequent organ involvement, especially heart and kidney failures compared with younger patients. They also have non-specific neurologic symptoms leading to a delayed diagnosis. Factors influencing this impaired survival among older patients remain unknown so far. Alteration of the functional capacity of involved organs could be part of the explanation as could be the consequences of vascular aging. In fact, severe ADAMTS13 deficiency is necessary but likely not sufficient for iTTP physiopathology. A second hit leading to endothelial activation is thought to play a central role in iTTP. Interestingly, the mechanisms involved in endothelial activation may share common features with those involved in vascular aging, potentially leading to endothelial dysfunction. It could thus be interesting to better investigate the causes of mid- and long-term mortality among older iTTP patients to confirm whether inflammation and endothelial activation really impact vascular aging and long-term mortality in those patients, in addition to their presumed role at iTTP acute phase. If so, further insights into the mechanisms involved could lead to new therapeutic targets.

Analysis of serum interleukin(IL)-1α, IL-1β and IL-18 in patients with systemic sclerosis

Objectives

Systemic sclerosis (SSc) is an autoimmune disease characterised by fibrosis, vascular dysfunction and immune dysregulation. The pathogenesis of SSc remains poorly understood, although studies have indicated a role for the innate immune response.

Methods

Here, we measured serum interleukin (IL)‐1α, IL‐1β and IL‐18 levels in 105 SSc patients and 47 healthy controls (HC) and analysed them with respect to multiple clinical parameters.

Results

Serum IL‐18 concentrations were significantly higher in SSc patients than in HC, while no significant differences in concentrations of IL‐1α and IL‐1β were observed between SSc and HC. In both SSc and HC serum, IL‐1α and IL‐1β were positively correlated, while in SSc, both cytokines negatively correlated with IL‐18. Serum IL‐18 was significantly negatively correlated with both carbon monoxide transfer coefficient (KCO) and diffusing capacity of the lungs for carbon monoxide (DLCO). Serum IL‐1β was positively correlated with the modified Rodnan skin score (mRSS), particularly in patients with limited subtype. DLCO, KCO and tricuspid regurgitation (TR) velocity were significantly higher in patients with high serum IL‐1β. Serum IL‐1α was significantly lower in SSc patients with low KCO and positively correlated with KCO. SSc patients with high serum IL‐1α concentrations were more likely to have digital ulcers.

Conclusions

Our data suggest that these IL‐1 family cytokines may have different roles in the pathogenesis of SSc fibrotic complications.

Role of lectin pathway complement proteins and genetic variants in organ damage and disease severity of systemic sclerosis: a cross-sectional study

BACKGROUND

The role of the complement system in the pathogenesis of systemic sclerosis (SSc) is controversial. This study investigated the role of the lectin pathway of complement as a mediator of ischemia/reperfusion injury in SSc.

METHODS

This is a prospective observational cross-sectional study of 211 SSc patients and 29 patients with Raynaud's phenomenon in undifferentiated connective tissue disease (UCTD) at risk of developing SSc from two outpatient clinics. Serum levels of lectin pathway proteins (FCN-2, FCN-3, MBL, and MASP-2) and eight MBL2 and FCN2 single-nucleotide polymorphisms (SNP) were analyzed by sandwich-type immunoassays and genotyping and examined for their association with disease manifestations.

RESULTS

Lectin pathway protein levels and SNPs were similar between SSc and UCTD patients. FCN-2 levels were however higher in SSc patients with present evidence of digital ulcers (mean 1.4 vs. 1.0 μg/mL, p = 0.05), pitting scars (mean 1.3 vs. 1.0 μg/mL, p = 0.01), and puffy fingers (mean 1.2 vs. 1.0 μg/mL, p = 0.04). Similarly, higher FCN-2 levels were observed in SSc patients with Scl-70 autoantibodies (mean 1.5 vs. 1.0 μg/mL, p = 0.001), interstitial lung disease (mean 1.2 vs. 0.9 μg/mL, p = 0.02), and a forced vital capacity (FVC) below 80% (mean 1.4 vs. 1.0 μg/mL, p = 0.02). In line, variant alleles in the FCN-2 SNP at position + 6359 were associated with a significantly reduced FVC and diffusion capacity. Furthermore, patients with SSc renal crisis harbored higher MBL levels (mean 2.7 vs. 1.5 μg/mL, p = 0.04). No other lectin pathway protein levels or polymorphisms were associated with disease manifestations, low complement C3 and/or C4 levels, or inflammatory markers.

CONCLUSIONS

This study does not support a relevant role for several lectin pathway complement proteins in the pathogenesis of SSc. Higher FCN-2 levels were however associated with Scl-70 autoantibody positivity, interstitial lung involvement, and digital vasculopathy. Elevated MBL levels were associated with renal crisis.

Scleroderma Renal Crisis Debute with Thrombotic Microangiopathy: A Successful Case Treated with Eculizumab

We had the challenged to treat a 40-year-old female with Systemic Scleroderma who was showing unspecific symptoms. During her time at the hospital she rapidly develops renal dysfunction, associated with hypertension. She required renal replacement therapy initiation and we observed a decline in hemoglobin and platelets numbers. We confirm a microangiopathic hemolytic anemia and rule out other immune diseases or thrombotic thrombocytopenic purpura. Systemic Sclerosis is a chronic immune disorder of unknown origin that it is not completely understood. It is believed that environmental factors may contribute and also altered genes may be implicated in the immune system's function. Microangiopathic hemolytic anemia occurs in 43% of patients who develop scleroderma renal crisis and an activation of the complement system through the classical pathway may be involved. Given that context we decided to treat the patients with C5 blocker Eculizumab and obtain an extraordinary positive response.

Complement activation in atypical hemolytic uremic syndrome and scleroderma renal crisis: a critical analysis of pathophysiology

Scleroderma is an autoimmune disease that affects multiple systems. While pathophysiologic mechanisms governing the development of scleroderma are relatively poorly understood, advances in our understanding of the complement system are clarifying the role of complement pathways in the development of atypical hemolytic uremic syndrome and scleroderma renal crisis. The abundant similarities in their presentation as well as the clinical course are raising the possibility of a common underlying pathogenesis. Recent reports are emphasizing that complement pathways appear to be the unifying link. This article reviews the role of complement system in the development of atypical hemolytic uremic syndrome and scleroderma renal crisis, and calls for heightened awareness to the development of thrombotic angiopathy in patients with scleroderma.