AB0151 THE ROLE OF PLASMA MICROVESICLES IN LVVs: NOT ONLY BIOLOGICAL MARKERS

Background

Microvesicles (MVs) are membrane enclosed extracellular vesicles released upon cellular activation and stress, which maintains features and maintain features and constituents of their parental cells. Large vessel vasculitides (LVVs) are inflammatory conditions of the wall of large-sized arteries, mainly represented by giant cell arteritis (GCA) and Takayasu arteritis (TA). Arterial stenosis and dilatation directly affect prognosis and, according to latest EULAR guidelines can be investigated by positron emission tomography and magnetic resonance angiography. Endothelial cells are believed to play a role in the pathogenesis of LVVs and circulating microvesicles could be a biomarker of vessel wall injury.

Objectives

To verify whether arterial wall derived-MVs detectable in the blood of TA patients and expressing bioactive molecules potentially involved in arterial injury, inflammation and remodeling could correlate with clinical and radiological features of those patients.

Methods

Platelet was obtained from 112 LVV pts (73 TA, 39 GCA). Plasma flow cytometry was performed with anti-CD14, CD16, anti-CD144 (VE-cadherin, an endothelial marker), anti-CD140a/b (PDGF receptor A/B a vascular stromal marker), anti-HMGB1, anti-PTX3, Mitotracker green and MitoSox, which are expression of mitochondrial moieties and ROS. Vascular imaging was carried out by angio-RM and PET. Circulating microvesicles from LVVs patients were correlated with disease characteristics, namely CRP, NIH activity, PGA, ITAS2010, ITAS2011 activity, immunosuppressant intake (IS), intake of glucocorticoids (yes/no) and biologics, and daily dose of glucocorticoids as well as radiological parameters. Pearson’s and Spearman’s correlation tests were used for parametric and non-parametric analysis. The SPSS IBM Software was used for statistics.

Results

The number of total MVs negatively correlate to CRP levels positively correlate to IS (p 0.052 and 0.013). CD 14 and 16 + MVs do not correlate with disease activity, extent or vascular inflammation at either MR or PET. PTX3+ MVs positively correlate to disease activity (NIH criteria and VAS), steroid intake, and disease extent (number of vessels at imaging). CD144+ MVs negatively correlate to IS and positively to SUV max at FDG PET. CD140a+ MVs significantly correlate to disease activity (PGA, VAS, and ITAS2010). Mitotracker+ Mvs negatively correlate to SNR max and positively to FDG-PET positivity.

Conclusion

Monocyte-derived MVs, despite being increased in LVV, do not correlate with disease activity, extent and vascular inflammation. Despite this, endothelial and stromal-derived MVs reflect some disease-related domains including clinical activity and imaging activity at PET. Furthermore, bioactive signals on MVs such as the long pentraxin PTX3 and mitochondria are more promising biomarkers. Accordingly, other studies have shown that systemic pentraxin-3 levels reflect vascular enhancement and progression in Takayasu arteritis, being PCR and ESR more a mirror of the burden of systemic inflammation. However, further studies are required to verify the pathogenic role of MVs in LVVs and to assess the impact of potential confounders such as therapy.

References

[1]van Niel G et al, Nat Rev Mol Cell Biol. 2018

[2]Mason JC. Nat Rev Rheumatol. 2010

[3]Tombetti et al, Arthirtis Research therapy 2014

Disclosure of Interests

None declared

OP0056 PLASMA MICROVESICLES AS LIQUID BIOPSIES OF THE ARTERIAL WALL IN LARGE VESSEL VASCULITIS

Background:

Large-vessel vasculitides comprise Takayasu arteritis (TA)and giant cell arteritis (GCA). Arterial stenosis and dilatation directly affect prognosis but the mechanism(s) underlying remodeling of the vessel wall have not been identified. Microvesicles (MVs) are membrane-enclosed extracellular vesicles released upon cellular activation and stress and as a consequence of environmental inflammation. MVs maintain features and constituents of their parental cells. They have been proposed to serve as potential liquid biopsies in oncology.

Objectives:

To verify whether arterial wall derived-MVs are recognizable in the blood of TA patients and express bioactive molecules potentially involved in arterial injury, inflammation and remodeling.

Methods:

Platelet was obtained from 112 LVV pts (73 TA, 39 GCA), 42 age and age- and sex-matched healthy controls (HC) and 30 pts with severe carotid atherosclerosis requiring vascular surgery. Plasma flow cytometry was performed with anti-CD14, CD16, anti-CD144 (VE-cadherin, an endothelial marker), anti-CD140a/b (PDGF receptor A/B a vascular stromal marker), anti-HMGB1, anti-PTX3, mitotracker green (that identifies mithochondrial moieties) and mitosox (that revels mitochondrial reactive oxygen species). MVs were identified by physical parameters using Gigamix beads. Medium- to large-sized MVs were defined as MVs with >240nm-eq diameter.

Results:

Preliminary results are available for 49 LVV (42 TA, 7 GCA), 8 severe carotidatherosclerosis and 14 age- and sex-matched HC. As compared to HC or CA, LVV plasma contains a higher number of MVs and in particular of medium- to large- sized MVs (p<0.001 for all comparisons) (Figure, panels A-B). Next, we evaluated the MVs surface expression of markers of leukocytic, endothelial and stromal/vascular stromal lineages. Total counts of CD14+, CD16+, CD66b+, CD140a+, CD140b+, CD144+ MVs were increased in LVV plasma with very high level of significance (Figure, panels C-G) while higher percentage of CD16+ and CD140a+ medium-to large-sized MVs was found in atherosclerosis. Expression of molecules involved in inflammation or repair, PTX3 or HMGB1 mitochondrial antigens and mitochondrial ROS all were consistently higher in LVV (Figure, panels H-M).

Conclusion:

MVs, including those expressing arterial stromal biomarkers, are increased in LVV plasma, suggesting a communication between the vessel wall and peripheral blood. MV express signals that may in turn contribute to persisting vascular inflammation in large vessel vascultis Further analysis is required to dissect their potential use as disease biomarkers

References:

[1]van Niel G et al, Nat Rev Mol Cell Biol. 2018

[2]Mason JC. Nat Rev Rheumatol. 2010

Disclosure of Interests:

None declared

HLA-G and anti-HCV in patients on the waiting list for kidney transplantation

PURPOSE

Human leukocyte antigen (HLA)-G is a non-classic major histocompatibility complex HLA class I molecule. HLA-G may have tolerogenic properties which are linked to epigenetic-sensitive pathways. There is a correlation of sHLA-G levels and graft acceptance in transplantation studies. There are previous data on correlation of sHLA-G with graft rejection as well as with viral infections such as hepatitis C virus (HCV) in kidney transplanted patients. Here, we report the sHLA-G expression in patients on the waiting list for kidney transplantation, with and without anti-HCV compared to a control group.

METHODS

Serum of 67 patients on the waiting list for kidney transplantation (n = 43 with anti-HCV and n = 24 without anti-HCV) was analyzed. Among these patients, n = 39 were on the waiting list for the first transplantation, while n = 28 were patients who returned in the list. The control group included n = 23 blood donors with anti-HCV (n = 13) and without anti-HCV (n = 10).

RESULTS

The expression of sHLA-G was significantly lower in the control group (39.6 ± 34.1 U/ml) compared to both - patients on the waiting list for the first transplantation (62.5 ± 42.4 U/ml, p=0.031) and patients who returned in the list (76.7 ± 53.9 U/ml, p=0.006). No significant differences were observed in all anti-HCV positive groups. A positive linear correlation between sHLA-G and TNF-α, and patient age was observed.

CONCLUSIONS

Serum sHLA-G values were significantly increased in both - patients on the waiting list for the first transplantation and patients who returned in the list, as compared to control group. Our findings confirm the key tolerogenic role of sHLA-G levels as epigenetic-related marker for measuring the state of kidney allograft acceptance.

Occult Hepatitis Infection in Transfusion Medicine: Screening Policy and Assessment of Current Use of Anti-HBc Testing

HBV still represents a global risk factor in transfusion medicine. The residual risk of HBV is not limited to pre-seroconversion window period but it extends to donors with occult HBV infection (OBI) characterized by the presence of HBV DNA in liver and by the absence of the virus surface antigen. Each country developed an appropriate blood screening policy according to local HBV prevalence, yields of infectious units per different screening methods and cost-effectiveness. We underline the need of maintaining a high level of attention for OBI carrier identification in all blood banks worldwide where the screening procedures are generally based on a combination of both serological markers and nucleic acid amplification test. In this context, markers such as hepatitis B surface antibodies and hepatitis B core antibodies (anti-HBc) might be useful, although the use of this latter is highly debated and still controversial. Our aim is to give an overview on the relevant diagnostic approaches for the routine screening for HBV focusing on the feasibility of anti-HBc testing as precautionary measure in preventing OBI transmission worldwide. In our tailored algorithm, the loss of about 1% of 'anti-HBc only' donors, does not significantly affect the blood supply while improving recipient safety.

Comparison of performance of two Treponema pallidum automated chemiluminescent immunoassays in blood donors

The recrudescence of syphilis is leading to the development of new serological tests. The goal of this study was to compare the performance of the more recent Elecsys Syphilis assay, the Electro Chemiluminescence Immunoassay (ECLIA), with the former Architect Syphilis TP assay, the Chemiluminescent Microparticle Immunoassay (CMIA), for the detection of antibodies against Treponema pallidum in blood donors. Serum samples of 5543 voluntary blood donors were screened in parallel with two tests. All repeatedly reactive (RR) samples by one or both assays were further analysed for confirmation by immmunoblot INNO-LIA and TPHA. Of 32 RR samples by CMIA, 21 were confirmed positive; of 21 RR samples by ECLIA, 20 were confirmed positive. The sensitivities of CMIA and ECLIA were 100% and 95.24% (95% CI = 85.71-100), respectively, not significant (p > 0.05). The specificity and predictive positive value (PPV) of CMIA were 99.86% (95% CI = 99.74-99.94) and 72.41%, respectively, while the specificity and PPV of ECLIA were both 100%, being statistically significant (p = 0.01 for both). The overall agreement was 99.80% and the Cohen's kappa coefficients was 0.79. In conclusion, the recent Elecsys Syphilis assay could represent another reliable assay for blood donor screening.

Innate and adaptive immune response in stroke: Focus on epigenetic regulation

Inflammation and immune response play a pivotal role in the pathophysiology of ischemic stroke giving their contribution to tissue damage and repair. Emerging evidence supports the involvement of epigenetic mechanisms such as methylation, histone modification and miRNAs in the pathogenesis of stroke. Interestingly, epigenetics can influence the molecular events involved in ischemic injury by controlling the switch from pro- to anti-inflammatory response, however, this is still a field to be fully explored. The knowledge of epigenetic processes could to allow for the discovery of more sensitive and specific biomarkers for risk, onset, and progression of disease as well as further novel tools to be used in both primary prevention and therapy of stroke. Indeed, studies performed in vitro and in small animal models seem to suggest a neuroprotective role of HDAC inhibitors (e.g. valproic acid) and antagomir (e.g. anti-miR-181a) in ischemic condition by modulation of both immune and inflammatory pathways. Thus, the clinical implications of altered epigenetic mechanisms for the prevention of stroke are very promising but clinical prospective studies and translational approaches are still warranted.

Syphilis detection: evaluation of serological screening and pilot reverse confirmatory assay algorithm in blood donors

Serological assays are still considered the most useful tests in the diagnosis of syphilis. Since no single serological assay is able to provide a satisfactory result, in our laboratory we have evaluated the usefulness of a commercially-available immunoblot to diagnose syphilis infection among blood donors. From October 2012 to June 2013, 4572 blood donors were screened for syphilis with an automated chemiluminescent microparticle immunoassay (CMIA). To confirm the presence of treponemal antibodies, CMIA-reactive sera were tested by standard Treponema pallidum haemagglutination assay (TPHA). In addition, an alternative confirmatory test - the immunoblot INNO-LIA assay was introduced in our laboratory. Since two additional positives among CMIA-reactive-TPHA-negative samples were found, we concluded that the INNO-LIA immunoblot allowed a better detection of syphilis compared to TPHA. A confirmatory strategy based on the use of two treponemal assays could meet the screening requirements for blood donors as well as in our centre.

Screening tests for hepatitis B virus, hepatitis C virus, and human immunodeficiency virus in blood donors: evaluation of two chemiluminescent immunoassay systems

Automated chemiluminescent immunoassays (CLIAs) are useful for the detection of hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus 1/2 antigen/antibodies (HIV 1/2 Ag/Ab) in blood donor screening. Eight hundred and forty serum samples were tested for hepatitis B surface antigen (HBsAg), HCV antibodies (anti-HCV), and HIV1/2 Ag/Ab in parallel using 2 different CLIAs (Abbott Architect i2000SR and Roche Cobas e411). The concordance between the 2 systems was high (Cohen's kappa 0.97 for HBsAg, 0.77 for anti-HCV, 0.92 for HIV1/2 Ag/Ab) and the specificity and the positive predictive value were comparable. Among the 12 discrepant results, 11 were false-positive and 1 (reactive by Architect) was true-positive for anti-HCV. Positivity for HBV DNA, HCV RNA, and HIV RNA was recorded in 90.9%, 38.9%, and 100% of true-positive samples, respectively. This study represents the first stringent comparison between Architect i2000SR and Cobas e411 in blood donors. We observed a good correlation and high agreement among HBV, HCV, and HIV with the 2 automated systems.

Comparison between screening and confirmatory serological assays in blood donors in a region of South Italy

BACKGROUND

Screening assays are needed in order to guarantee safety of donated blood, but a significant number of safe donations are removed from blood supply because of reactive screening results. It is important to evaluate the positive predictive value (PPV) of screening assays in order to modulate confirmatory algorithm and implement an adequate counseling.

METHODS

An analysis of 17,912 blood donations has been conducted at Transfusion Medicine at Second University Naples, Italy, in 2009-2012. Serological screening for syphilis, hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) was performed by ARCHITECT (Abbott Diagnostics, Wiesbaden, Germany); repeatedly reactive (RR) samples were checked by respective confirmatory tests. The relationship between sample/cutoff and confirmed seropositivity were analyzed.

RESULTS

RR rates were low as expected in blood donors: 0.47% for syphilis, 0.42% for HBV, 0.50% for HCV, and 0.15% for HIV. The specificity on RR + gray zone (GZ) was 99.67%, 99.79%, 99.77%, and 99.88%, respectively; due to the low prevalence, PPV value was 30.6% for syphilis, 50.7% for HBV, 42.2% for HCV, and 18.5% for HIV. These values increased substantially reaching a plateau of 89.3% for syphilis, 94.6% for HBV, 85.7% for HCV, and 100% for HIV at the threshold established by receiver operating characteristics curve analysis.

CONCLUSIONS

Supplemental testing on samples with high signal by screening assays seems to add little information. GZ settings and confirmatory testing for positive screening results should be designed taking in account several factors, including difference in the natural history among blood-borne infections, the characteristics of first- and second-level tests, and, when available, the results of nucleic acid amplification testing.

Is the Beck Depression Inventory reliable over time? An evaluation of multiple test-retest reliability in a nonclinical college student sample

The Beck Depression Inventory (BDI) is one of the most widely used measures of depression. Many studies have examined the reliability and validity of the BDI. However, we found no published studies that considered the stability of the BDI over multiple administrations (i.e., more than 3 trials), such as is common in clinical trials research and during some clinical interventions. The purpose of this study is to examine the multiple test-retest reliability of the BDI in a presumably nonclinical sample. Results show a 40% decline in BDI scores over 8 weeks, a main effect that accounts for approximately 10% of the variance. We achieved a 40% decrease in self-reported symptoms of depression due to repeated measurement alone, not due to any intervention. This change likely represents measurement error with this instrument rather than any "real" change in depression. The limitations of this study, its implications for research, and its applications to clinical practice are discussed.