Serum elastin-derived peptides and anti-elastin antibody in patients with systemic sclerosis

Humoral immunity to lung antigens early post-transplant confers risk for chronic lung allograft dysfunction

BACKGROUND

Autoantibodies and de novo donor HLA-specific antibodies (dnDSA) may contribute to chronic lung allograft dysfunction (CLAD). However, the breadth of reactivities against self-antigens and their association with CLAD has been underexamined. In a single-centre study, we screened lung transplant (LTx) recipients for novel autoantibodies at transplant and 6 months post-LTx, assessed dnDSA exposure, and tested their relationship with CLAD-free survival.

METHODS

Serum samples were collected from 89 crossmatch-negative bilateral lung transplant recipients at the time of LTx and 6 months post-LTx, prior to a CLAD diagnosis, for autoantibody screening using a custom antigen microarray optimized for IgM and IgG detection.

RESULTS

Patients who developed CLAD by 5 years post-LTx demonstrated a decrease in average IgG reactivity, but no decrease in IgM reactivity when measured at 6 months post-LTx. IgG anti-tropoelastin, SP-D, and thyroglobulin autoantibodies were significantly elevated 6 months post-LTx in patients who developed CLAD by 5 years, compared to those who remained CLAD-free at 5 years. In contrast, patients who remained CLAD-free at 5 years had elevated levels of IgG anti-CENP-B at both timepoints and PM/SCL100 at 6 months post-LTx, suggesting these may confer protection. Exposure to autoantibodies against lung-enriched targets, as opposed to ubiquitous antigens, and dnDSA conferred increased CLAD risk.

CONCLUSIONS

We have identified novel autoantibodies associated with CLAD-free survival. Our results bolster the independent relationship between autoantibodies and CLAD. We also identified autoantibody signatures that are associated with a marked increase in CLAD risk. Exposure to lung-enriched targets and dnDSA may have a reciprocal amplifying effect that lies on a tissue-specific mechanistic pathway leading to CLAD.

Elastin-derived peptides (EDPs) as a potential pro-malignancy factor in human leukemia cell lines

The extracellular matrix (ECM) is currently considered to be an important factor influencing the migration and progression of cancer cells. Therefore, the aim of our study was to investigate the mechanism of action of elastin-derived peptides in cancerous cells derived from the immunological system, i.e., HL-60, K562, and MEG-A2 cell lines. Moreover, an attempt to clarify the involvement of c-SRC kinase in EDP mechanism of action was also undertaken. Our data show that the VGVAPG and VVGPGA peptides are not toxic in the studied cell lines. Moreover, due to the involvement of KI67 and PCNA proteins in the cell cycle and proliferation, we can assume that neither peptide stimulates cell proliferation. Our data suggest that both peptides could initiate the differentiation process in all the studied cell lines. However, due to the different origins (HL-60 and K562-leukemic cell line vs. MEG-A2-megakaryoblastic origin) of the cell lines, the mechanism may differ. The increase in the ELANE mRNA expression noted in our experiments may also suggest enhancement of the migration of the tested cells. However, more research is needed to fully explain the mechanism of action of the VGVAPG and VVGPGA peptides in the HL-60, K562, and MEG-A2 cell lines. HIGHLIGHTS: • VGVAPG and VVGPGA peptides do not affect the metabolic activity of HL-60, K562, and MEG-A2 cells. • mTOR and PPARγ proteins are involved in the mechanism of action of VGVAPG and VVGPGA peptides. • Both peptides may initiate differentiation in HL-60, K562, and MEG-A2 cell lines.

Mucopolysaccharidosis Type IVA: Extracellular Matrix Biomarkers in Cardiovascular Disease

Cardiovascular disease (CVD) in Mucopolysaccharidosis Type IVA (Morquio A), signified by valvular disease and cardiac hypertrophy, is the second leading cause of death and remains untouched by current therapies. Enzyme replacement therapy (ERT) is the gold-standard treatment for MPS disorders including Morquio A. Early administration of ERT improves outcomes of patients from childhood to adulthood while posing new challenges including prognosis of CVD and ERT's negligible effect on cardiovascular health. Thus, having accurate biomarkers for CVD could be critical. Here we show that cathepsin S (CTSS) and elastin (ELN) can be used as biomarkers of extracellular matrix remodeling in Morquio A disease. We found in a cohort of 54 treatment naïve Morquio A patients and 74 normal controls that CTSS shows promising attributes as a biomarker in young Morquio A children. On the other hand, ELN shows promising attributes as a biomarker in adolescent and adult Morquio A. Plasma/urine keratan sulfate (KS), and urinary glycosaminoglycan (GAG) levels were significantly higher in Morquio A patients (p < 0.001) which decreased with age of patients. CTSS levels did not correlate with patients' phenotypic severity but differed significantly between patients (median range 5.45-8.52 ng/mL) and normal controls (median range 9.61-15.9 ng/mL; p < 0.001). We also studied α -2-macroglobulin (A2M), C-reactive protein (CRP), and circulating vascular cell adhesion molecule-1 (sVCAM-1) in a subset of samples to understand the relation between ECM biomarkers and the severity of CVD in Morquio A patients. Our experiments revealed that CRP and sVCAM-1 levels were lower in Morquio A patients compared to normal controls. We also observed a strong inverse correlation between urine/plasma KS and CRP (p = 0.013 and p = 0.022, respectively) in Morquio A patients as well as a moderate correlation between sVCAM-1 and CTSS in Morquio A patients at all ages (p = 0.03). As the first study to date investigating CTSS and ELN levels in Morquio A patients and in the normal population, our results establish a starting point for more elaborate studies in larger populations to understand how CTSS and ELN levels correlate with Morquio A severity.

Systemic sclerosis skin is a primed microenvironment for soft tissue calcification-a hypothesis

Calcinosis cutis, defined as sub-epidermal deposition of calcium salts, is a major clinical problem in patients with SSc, affecting 20-40% of patients. A number of recognized factors associated with calcinosis have been identified, including disease duration, digital ischaemia and acro-osteolysis. Yet, to date, the pathogenesis of SSc-related calcinosis remains unknown, and currently there is no effective disease-modifying pharmacotherapy. Following onset of SSc, there are marked changes in the extracellular matrix (ECM) of the skin, notably a breakdown in the microfibrillar network and accumulation of type I collagen. Our hypothesis is that these pathological changes reflect a changing cellular phenotype and result in a primed microenvironment for soft tissue calcification, with SSc fibroblasts adopting a pro-osteogenic profile, and specific driving forces promoting tissue mineralization. Considering the role of the ECM in disease progression may help elucidate the mechanism(s) behind SSc-related calcinosis and inform the development of future therapeutic interventions.

The Elastin-Derived Peptide VGVAPG Does Not Activate the Inflammatory Process in Mouse Cortical Astrocytes In Vitro

During vascular aging or in pathological conditions in humans, elastin is degraded and its by-products, the elastin-derived peptides (EDPs), enter the blood circulation. EDPs may be detected in the serum of healthy subjects or people who suffered a stroke. Moreover, recent evidence suggests a potential role of inflammatory mechanisms in neurological conditions, which are usually not categorized as inflammatory. Therefore, the present in vitro study was conducted to investigate the impact of the VGVAPG peptide on the activation of inflammatory process in mouse primary astrocytes, which were maintained in phenol red-free DMEM/F12 supplemented with 10% fetal bovine serum. The cells were exposed to VGVAPG or VVGPGA peptides for 24 and 48 h; this was followed by the determination of the activity of caspase-1 and levels of SOD, CAT, PPARγ, NF-κB, IL-1β, and IL-1βR1. Furthermore, rosiglitazone-a PPARγ agonist-was applied. Our study pioneered the finding that the VGVAPG peptide increases caspase-1 activity in astrocytes in vitro. The VGVAPG peptide simultaneously decreases the release of IL-1β into the cell-culture medium from astrocytes. The ELISA method revealed that the VGVAPG peptide increases the protein expression of SOD1 whereas it decreases the expression of IL-1βR1, CAT, and NF-κB. Therefore, the available data suggest that the VGVAPG peptide (concentration 10 nM) synergistically acts with agonists of PPARγ in mouse astrocytes. However, given the lack of sufficient data to explain the molecular mechanism of action of the VGVAPG peptide in the nervous system, more studies in this area are necessary.

Combined pulmonary fibrosis and emphysema in systemic sclerosis: A syndrome associated with heavy morbidity and mortality

BACKGROUND

The syndrome of combined pulmonary fibrosis and emphysema (CPFE) primarily due to tobacco smoking has been reported in connective tissue disease, but little is known about its characteristics in systemic sclerosis (SSc).

METHODS

In this retrospective multi-center case-control study, we identified 36 SSc patients with CPFE, and compared them with 72 SSc controls with interstitial lung disease (ILD) without emphysema.

RESULTS

Rate of CPFE in SSc patients with CT scan was 3.6%, and 7.6% among SSc patients with ILD. CPFE-SSc patients were more likely to be male (75 % vs 18%, p < 0.0001), smokers (83 % vs 33%, p < 0.0001), and to have limited cutaneous SSc (53 % vs 24% p < 0.01) than ILD-SSc controls. No specific autoantibody was significantly associated with CPFE. At diagnosis, CPFE-SSc patients had a greater decrease in carbon monoxide diffusing capacity (DLCO 39 ± 13 % vs 51 ± 12% of predicted value, p < 0.0001) when compared to SSc-ILD controls, whereas lung volumes (total lung capacity and forced vital capacity) were similar. During follow-up, CPFE-SSc patients more frequently developed precapillary pulmonary hypertension (PH) (44 % vs 11%, p < 10^-4), experienced more frequent unscheduled hospitalizations (50 % vs 25%, p < 0.01), and had decreased survival (p < 0.02 by Kaplan-Meier survival analysis) as compared to ILD-SSc controls.

CONCLUSIONS

The CPFE syndrome is a distinct pulmonary manifestation in SSc, with higher morbidity and mortality. Early diagnosis of CPFE by chest CT in SSc patients (especially smokers) may result in earlier smoking cessation, screening for PH, and appropriate management.

Elastin molecular aging promotes MDA-MB-231 breast cancer cell invasiveness

Elastin is a long-lived extracellular matrix protein responsible for the structural integrity and function of tissues. Breast cancer elastosis is a complex phenomenon resulting in both the deposition of elastotic masses and the local production of elastin fragments. In invasive human breast cancers, an increase in elastosis is correlated with severity of the disease and age of the patient. Elastin-derived peptides (EDPs) are a hallmark of aging and are matrikines - matrix fragments having the ability to regulate cell physiology. They are known to promote processes linked to tumor progression, but their effects on breast cancer cells remain unexplored. Our data show that EDPs enhance the invasiveness of MDA-MB-231 breast cancer cells through the engagement of matrix metalloproteases 14 and 2. We therefore suggest that elastosis and/or an aged stroma could promote breast cancer cell invasiveness.

Circulating Anti-Elastin Antibody Levels and Arterial Disease Characteristics: Associations with Arterial Stiffness and Atherosclerosis

PURPOSE

Elastin is a major arterial structural protein, and elastin-derived peptides are related to arterial change. We previously reported on a novel assay developed using aortic elastin peptides; however, its clinical implications remain unclear. In this study, we assessed whether anti-elastin antibody titers reflect the risk of coronary artery disease (CAD) or its characteristics.

MATERIALS AND METHODS

We included 174 CAD patients and 171 age- and sex-matched controls. Anti-elastin antibody titers were quantified by enzyme-linked immunosorbent assay. Parameters of arterial stiffness, including the augmentation index (AI) and heart-to-femoral pulse wave velocity (hfPWV), were measured non-invasively. The clinical and angiographic characteristics of CAD patients were also evaluated. Associations between anti-elastin levels and vascular characteristics were examined by linear regression analysis.

RESULTS

The median blood level of anti-elastin was significantly lower in the CAD group than in the controls [197 arbitrary unit (a.u.) vs. 63 a.u., p<0.001]. Levels of anti-elastin were significantly lower in men and in subjects with hypertension, diabetes mellitus, hyperlipidemia, or high hfPWV. Nevertheless, anti-elastin levels were not dependent on atherothrombotic events or the angiographic severity of CAD. In a multivariate analysis, male sex (β=-0.38, p<0.001), diabetes mellitus (β=-0.62, p<0.001), hyperlipidemia (β=-0.29, p<0.001), and AI (β=-0.006, p=0.02) were ultimately identified as determinants of anti-elastin levels.

CONCLUSION

Lower levels of anti-elastin are related to CAD. The association between antibody titers and CAD is linked to arterial stiffness rather than the advancement of atherosclerosis.

Elastin-derived peptides are new regulators of thrombosis

OBJECTIVE

Elastin is the major structural extracellular matrix component of the arterial wall that provides the elastic recoil properties and resilience essential for proper vascular function. Elastin-derived peptides (EDP) originating from elastin fragmentation during vascular remodeling have been shown to play an important role in cell physiology and development of cardiovascular diseases. However, their involvement in thrombosis has been unexplored to date. In this study, we investigated the effects of EDP on (1) platelet aggregation and related signaling and (2) thrombus formation. We also characterized the mechanism by which EDP regulate thrombosis.

APPROACH AND RESULTS

We show that EDP, derived from organo-alkaline hydrolysate of bovine insoluble elastin (kappa-elastin), decrease human platelet aggregation in whole blood induced by weak and strong agonists, such as ADP, epinephrine, arachidonic acid, collagen, TRAP, and U46619. In a mouse whole blood perfusion assay over a collagen matrix, kappa-elastin and VGVAPG, the canonical peptide recognizing the elastin receptor complex, significantly decrease thrombus formation under arterial shear conditions. We confirmed these results in vivo by demonstrating that both kappa-elastin and VGVAPG significantly prolonged the time for complete arteriole occlusion in a mouse model of thrombosis and increased tail bleeding times. Finally, we demonstrate that the regulatory role of EDP on thrombosis relies on platelets that express a functional elastin receptor complex and on the ability of EDP to disrupt plasma von Willebrand factor interaction with collagen.

CONCLUSIONS

These results highlight the complex nature of the mechanisms governing thrombus formation and reveal an unsuspected regulatory role for circulating EDP in thrombosis.