Serum cystatin C is associated with kidney function but not with cardiovascular risk factors or subclinical atherosclerosis in patients with Systemic Lupus Erythematosus

Proteomic analyses reveal cystatin c is a promising biomarker for evaluation of systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease with multiple organ involvement, especially the kidneys. However, the underlying mechanism remains unclear, and accurate biomarkers are still lacking. This study aimed to identify biomarkers to assess organ damage and disease activity in patients with SLE using quantitative proteomics.

METHODS

Proteomic analysis was performed using mass spectrometry in 15 patients with SLE and 15 age-matched healthy controls. Proteomic profiles were compared in four main subtypes: SLE with proteinuria (SLE-PN), SLE without proteinuria (SLE-non-PN), SLE with anti-dsDNA positivity (SLE-DP), and SLE with anti-dsDNA negativity (SLE-non-DP). Gene ontology biological process analysis revealed differentially expressed protein networks. Cystatin C (CysC) levels were measured in 200 patients with SLE using an immunoturbidimetric assay. Clinical and laboratory data were collected to assess their correlation with serum CysC levels.

RESULTS

Proteomic analysis showed that upregulated proteins in both the SLE-PN and SLE-DP groups were mainly mapped to neutrophil activation networks. Moreover, CysC from neutrophil activation networks was upregulated in both the SLE-PN and SLE-DP groups. The associations of serum CysC level with proteinuria, anti-dsDNA positivity, lower complement C3 levels, and SLE disease activity index score in patients with SLE were further validated in a large independent cohort.

CONCLUSIONS

Neutrophil activation is more prominent in SLE with proteinuria and anti-dsDNA positivity, and CysC is a promising marker for monitoring organ damage and disease activity in SLE.

No causal association between plasma cystatin C and cardiovascular diseases: Mendelian randomization analyses in UK biobank

Background

We aimed to determine whether the plasma cystatin C is a causal risk factor for cardiovascular events, stroke, myocardial infarction (MI), and cardiovascular disease (CVD) mortality by conducting Mendelian randomization (MR) designs.

Methods

Our study included 277,057 individuals free of CVDs or cancer at baseline in the UK Biobank. The genetic scores of plasma cystatin C comprising 67 single-nucleotide polymorphisms were calculated on the basis of data from a large genome-wide association study. By stratifying the genetic score, we conducted cox regression to assess the relationship between plasma cystatin C and CVDs. In this study, linear MR analysis was used to estimate the causal association between plasma cystatin C and CVDs.

Results

Observational analyses showed that plasma cystatin C concentrations were associated with the risk of CVDs [hazard ratios (HR) per standard deviation (SD) 1.09, 95% confidence interval (CI); 1.07-1.10] and CVD mortality (1.14, 1.11-1.17). Among CVDs, plasma cystatin C were associated with stroke (1.10, 1.08-1.11) and MI (1.08, 1.07-1.10). Linear MR analysis did not provide evidence of a causal association between plasma cystatin C and the risk of CVDs [odds ratio (OR) per SD 0.96, 95% CI;0.90-1.03], stroke (0.96, 0.93-1.01), MI (0.97, 0.91-1.03), and CVD mortality (0.98, 0.96-1.01), with consistent estimates from sensitivity analyses.

Conclusion

Observational findings indicated that higher plasma cystatin C is associated with a higher risk of CVDs; According to MR studies, there is no causal association between plasma cystatin C and the risk of CVDs and CVD mortality.

Obesity, Diabetes, and Cardiovascular Risk Burden in Systemic Lupus Erythematosus: Current Approaches and Knowledge Gaps-A Rapid Scoping Review

Obesity, diabetes mellitus, and cardiovascular risk are real challenges in systemic lupus erythematosus (SLE) clinical practice and research. The evidence of the burden of these health problems in SLE patients is determined by the methods used to assess them. Therefore, the aim of this scoping review is to map current approaches in assessing obesity, diabetes mellitus, and cardiovascular risk burden in SLE patients and to identify existing knowledge gaps in this field. This rapid scoping review was conducted according to the Joanna Briggs Institute methodology and identified 274 articles, of which 73 were included. Most studies were conducted at European institutions and patients were recruited from specialist hospital clinics, the majority of whom were women. The burden of obesity and diabetes mellitus for SLE patients was assessed mainly in terms of prevalence, impact on disease activity, and cardiometabolic risk. The burden of cardiovascular risk was assessed using multiple approaches, mainly imaging and laboratory methods, and risk factor-based scores, although there is great heterogeneity and uncertainty between the methods used. This review highlights the importance of improving and standardizing the approach to obesity, diabetes, and cardiovascular risk in SLE patients through a holistic assessment that includes lifestyle, clinical, biological, and social aspects.

Role of Cystatin C in Predicting Disease Activity and Flare-Up in Systemic Lupus Erythematosus: A Longitudinal Follow-Up Study

Background:

We aimed to determine the sensitivity of serum cystatin C (Cys-C) in predicting lupus flare-up.

Methods:

In a longitudinal study, 77 patients were followed-up for up to 15 months. Cys-C, physician global assessment (PGA), and lupus activity index (SLEDAI) were recorded during each visit. Flare-up was defined as an increase ≥4 scores in SLEDAI compared to the last visit. The predictability of flare-up by Cys-C was evaluated by generalized linear-mixed effect model (GLMM) and generalized estimating equation (GEE). Predictive power of Cys-C, SLEDAI, and PGA was compared by the area under the curves (AUC) and application of receiver operating characteristic (ROC) curves.

Results:

Lupus flare-up was observed in 14 out of 77 patients on the 1^st visit, 3 out of 41 patients on the 2^nd visit, 2 out of 26 patients on the 3^rd visit, 1 out of 14 patients on the 4^th visit, and 1 out of 3 patients on the 5^th visit. Mean Cys-C levels in patients with flare-up vs. those with no flare-up in the 1^st, 2^nd, and 3^rd visits were 1769 vs. 1603 (P = 0.6), 5701 vs. 2117 (p = 0.2) and 1409 vs. 1731 (p = 0.9), respectively. Cys-C had lower predictive power than PGA and SLEDAI for either flare-up, active nephritis or SLEDAI in GLMM/GEE models. Cys-C also showed lower sensitivity (AUC = 0.701, 95%CI = 0.579-0.823, P = 0.003) than PGA and SLEDAI, to distinguish patients prone to flare-ups.

Conclusions:

Although Cys-C had some sensitivity for predicting flare-up, active nephritis or SLEDAI, its sensitivity was lower than that in PGA and SLEDAI.

Endothelial dysfunction and arterial stiffness in patients with systemic lupus erythematosus: A systematic review and meta-analysis

BACKGROUND AND AIMS

Non-invasive surrogates of cardiovascular (CV) disease such as endothelial dysfunction (ED) and peripheral arterial stiffness (AS) have been evaluated in systemic lupus erythematosus (SLE) patients. The aim of this study was to systematically review and meta-analyze reports of cardiovascular disease (CVD) in SLE patients, as measured by ED and AS.

METHODS

Studies analyzing the relationship of SLE with ED (flow-mediated dilatation [FMD], nitroglycerin-mediated dilatation [NMD] and peripheral arterial tonometry [PAT]) and AS (augmentation index [AIx], pulse wave velocity [PWV]) were systematically searched for in PubMed, Cochrane library, EMBASE, VHL, SciELO and Web of Science databases. Inclusion criteria included peer-review and English language. Mean differences (MD) and 95% confidence intervals (CIs) were estimated using the random effect model. The study was registered with PROSPERO, number CRD42019121068.

RESULTS

The meta-analysis included 49 studies. FMD data from 18 studies including 943 SLE subjects (mean age = 38.71 [95%CI 36.21, 41.21] years) and 644 unaffected controls (mean age = 38.63 [95%CI 36.11, 41.15] years) were included. When compared with unaffected controls, FMD in SLE subjects was decreased by 4.3% (95%CI: -6.13%, -2.47%): p < 0.001). However, NMD did not significantly differ between SLE patients and controls (MD = - 2.68%; 95% CI -6.00, 0.62; p = 0.11). A significantly increased AS between SLE patients and controls according to overall PWV (MD = 1.12 m/s; 95% CI 0.72-1.52; p < 0.001) was observed, but not for the brachial-ankle PWV. AIx was also increased in SLE patients compared with healthy controls (MD = 4.55%; 95% CI 1.48-7.63; p = 0.003).

CONCLUSIONS

Overall, SLE patients showed impaired FMD, an independent predictor of CV events. There was a higher degree of AS in SLE patients compared with controls. ED and AS in SLE should be considered when planning preventive strategies and therapies.

Diagnostic performance of serum cystatin C and complement component 1q in lupus nephritis

BACKGROUND

The information concerning non-invasive, easily obtainable, and accurate biomarkers for diagnosis of lupus nephritis (LN) is extremely limited. The aim of this study was to evaluate the diagnostic performance of cystatin C (CysC) and complement component 1q (C1q) for LN.

METHODS

A case-control study that included 905 patients with systemic lupus erythematosus (SLE) without LN (group SLE), 334 patients with active lupus nephritis (group LNA), 255 patients with inactive lupus nephritis (group LNI), and 497 healthy individuals (group HC) was performed in Mianyang Central Hospital from March 2017 to December 2018. The serum levels of CysC, C1q, urea (Urea), and creatinine (Creat) were measured, and 2 estimated glomerular filtration rates (eGFRCysC and eGFRCreat) were calculated by equations which were based on serum CysC established by our group and the modification of diet in renal disease (MDRD), respectively. ANOVA analysis or Kruskal-Wallis test was used for comparing the differences among the groups, and receiver operating characteristic (ROC) curve was applied to identify the diagnostic efficiencies of individual or combined multiple indicators.

RESULTS

Significantly elevated CysC and decreased C1q were observed in the LNA and LNI groups, which was in contrast to their levels in the SLE and HC groups. CysC (AUC = 0.906) or eGFRCysC (AUC = 0.907) assessed the highest diagnostic performance on LNA when detected individually, followed by C1q (AUC = 0.753). Joint utilization of C1q and CysC achieved very good performance (AUC = 0.933) which approximated to the best one observed in the combinations of C1q, Urea, CysC, eGFRCreat, and Creat (AUC = 0.975).

CONCLUSION

The separately detected CysC (eGFRCysC) and C1q were superior to the conventional biomarkers Urea, Creat, and eGFRCreat in the diagnosis of LNA. Moreover, although the combined detection of Urea, Creat, C1q, CysC, and eGFRCreat had the greatest diagnostic performance, the joint utilization of CysC and C1q could be prioritized for rapid discrimination of LNA if the economic burden is taken into consideration.

Correlations of serum cystatin C and hs-CRP with vascular endothelial cell injury in patients with systemic lupus erythematosus

BACKGROUND

To investigate the correlations of serum cystatin C and high-sensitivity C-reactive protein (hs-CRP) with vascular endothelial cell injury in patients with active systemic lupus erythematosus (SLE).

METHODS

A total of 80 patients with SLE treated in our hospital from January 2016 to September 2017 were selected and randomly divided into stable-stage group (N.=40) and active-stage group (N.=40) using a random number table. The expressions of cystatin C and hs-CRP in stable and active stages were compared, and the inner diameters of brachial artery and levels of vascular endothelial growth factors in stable and active stages were also compared. The correlations of expressions of cystatin C and hs-CRP in active stage with the inner diameter of brachial artery and vascular endothelial growth factor were analyzed. At the same time, the correlation between vascular endothelial growth factor and inner diameter of brachial artery in active stage was analyzed.

RESULTS

The level of cystatin C in active stage was higher than that in stable stage (P<0.05), and the expression level of hs-CRP in active stage was also higher than that in stable stage (P<0.05). The inner diameter of brachial artery in active stage was smaller than that in stable stage (P<0.05), but the level of vascular endothelial growth factor (VEGF) was higher than that in stable stage (P<0.05). The expressions of cystatin C and hs-CRP were negatively correlated with the inner diameter of brachial artery in active stage (P<0.05). The expressions of cystatin C and hs-CRP were positively correlated with VEGF in active stage (P<0.05). Moreover, there was a negative correlation between VEGF and inner diameter of brachial artery in active stage (P<0.05).

CONCLUSIONS

Levels of cystatin C and hs-CRP are significantly increased in patients with active SLE, and the increase degrees are negatively correlated with the inner diameter of brachial artery under ultrasound, but positively correlated with the level of VEGF in vivo.