POS0368 CITRULLINATION INDUCES EPIGENETIC MEMORY OF THE INNATE IMMUNE SYSTEM

Background:

During trained immunity, monocytes and macrophages undergo a functional and transcriptional reprogramming toward activation, which is induced by a priming stimulus and results in enhanced responsiveness to subsequent triggers. Monocytes from patients with rheumatoid arthritis (RA) display features consistent with a trained immunity phenotype. Citrullinated proteins as citrullinated vimentin (c-vimentin), which function as damage-associated patterns in RA, may be implicated in the process of trained immunity.

Objectives:

We aimed to investigate if c-vimentin induces trained immunity in vitro in healthy individuals.

Methods:

Monocytes were isolated from the peripheral blood (EDTA blood, n=22; buffy coats, n=6) from healthy donors by Ficoll-paque centrifugation and negative selection using CD3/CD19/CD56 magnetic beads. The cells were stimulated with c-vimentin (0.1 μg/ml) for 24h and re-stimulated 5 days later with the lipopolysaccharide of E.coli (LPS) (10 ng/ml). Protein as well as lactate release were estimated in cell culture supernatants at day 6 by ELISA. RT-PCR and/or Western Blotting were applied to measure mRNA and/or protein expression. The Ligand-receptor glycocapture technology LRC-TRiCEPS was used to identify candidate cell surface targets of c-vimentin. The methylation of histone H3 at lysine 4 (H3K4) was examined by chromatin immunoprecipitation.

Results:

Priming with citrullinated vimentin induced training in human monocytes, as suggested by the significantly increased levels of secreted interleukin-6 (IL-6), upon restimulation with LPS (1.29-fold increase, n=22, p<0.001). Likewise, the release of chemokines CXCL1 and CCL20/Macrophage Inflammatory Protein 3a was significantly increased (1.81-fold and 2.32-fold increase, respectively, n=14, both p<0.001). LRC-TRiCEPS enabled the identification of STING cell surface receptor for the ligand c-vimentin. Indeed, c-vimentin induced activation of TBK1, which is implicated in the STING signaling pathway, by phosphorylation, while STING inhibition with the covalent small molecule H151 (2μM) abolished this effect. Besides, H151 inhibited trained immunity by decreasing IL-6 release and expression (1.61-fold and 1.93-fold decrease, respectively, n=5). Trained monocytes also displayed high lactate production (primed vs. unprimed cells, n=9, p=0.004), reflecting a shift in metabolism with an increase in glycolysis. By inhibiting the metabolic pathway of glycolysis by 2-deoxyglucose (11mM), the induction of trained immunity could be counteracted (5.32-fold decrease in IL-6 release, n=7, p=0.016). Finally, c-vimentin induced H3K4 methylation with increased levels of this mark in the promoter of the IL-6 gene. By modulating the function of epigenetic enzymes with methylthioadenosine (1mM), which specifically inhibits histone methyltransferase, trained immunity was reversed (8.43-fold decrease in IL-6 release, n=6, p=0.031).

Conclusion:

Citrullinated vimentin induces epigenetic modifications and metabolic changes in monocytes, probably through a STING and TBK1-dependent activation, resulting in enhanced cytokine and chemokine production upon restimulation. Inhibition of the STING signaling pathway may be a novel therapeutic target for myeloid activation in RA.

Disclosure of Interests:

None declared

Losing Themselves From Following Up: Barriers to Accessing Further Clinical Investigations for Women With Abnormal Clinical Breast Examination (CBE) Findings in Klang Valley, Malaysia

Background: Clinical breast examination (CBE) is one of the most accessible screening methods for breast cancer and widely used in the Malaysian public health system due to the wide availability of trained healthcare personnel and low costs; especially in government hospitals. However, discovery of an abnormal finding from the CBE does not necessarily translate into action for further clinical investigations. An understanding of the patients' motivations in decision making, which causes them to ignore the need for further clinical investigations despite abnormal findings in CBEs may be an important element to improve holistic cancer prevention efforts; of which early detection is a key strategy. Aim: The aim of this study was to investigate the barriers for women to receive follow-up care upon obtaining abnormal results for CBE. Methods: The National Cancer Society of Malaysia has an active ongoing public outreach program in which trained healthcare personnel conduct CBEs at various screening campaigns throughout the Klang Valley with a total of 1017 women screened in 2017. Women who were screened and found to have an abnormal finding from the CBE were referred for further investigations at a center of their choice. Women found to have an abnormal CBE finding were reached via a phone call to determine whether they had proceeded to i) get an appointment for further clinical examination; or ii) had already undergone a further clinical examination. Those who had done neither were interviewed via phone to determine their reasons for not proceeding with further clinical investigations despite an abnormal CBE finding. Results: Out of the 1017 women screened, 38 were found to have an abnormal CBE finding. Of them, 16 women had not sought further investigations. Qualitative interviews revealed that there strong issues that posed barriers to these women pursuing further investigations. These barriers included a lack of knowledge and understanding about breast cancer or rationale of undergoing a CBE; a lack of urgency pertaining to CBE results and feeling of embarrassment engaging with family members on facilitating attendance to the investigation. Conclusion: Significant barriers remain which deter women who have abnormal CBE findings from pursuing further clinical investigations which ultimately reduces the effectiveness of current breast cancer screening strategies. These findings may prove to be important for designing effective methods to encourage confirmatory clinical examination among those already found to have abnormal findings from tests such as the CBE.

Factors Associated With an Abnormal Mammogram Finding in Women Undergoing Screening in Kuala Lumpur, Malaysia

Background: Breast cancer is the most common cancer among Malaysian women, with a rising incidence from 16.5% in 2006%–17.7% in 2011. One of the key strategies in breast cancer control is early screening; of which mammography is a highly accurate tool, having been shown to reduce the number of mortality rates due to breast cancer up to 30%. However, mammography is often not as widely available in Malaysia; and in many local settings, healthcare providers have to limit screenings to only particular groups such as those with abnormal clinical breast examinations due to limited resources. Knowledge of other predictive factors may assist in further decision-making to prioritize patients for screening mammography in a low-resource setting. Aim: This study aimed to determine such predictive factors for abnormal mammogram findings among women who underwent mammography examination at a center in Kuala Lumpur, Malaysia. Methods: This was a cross-sectional study of women (n = 5491) who underwent a three-dimensional tomosynthesis mammography procedure at the Cancer and Health Screening Clinic, National Cancer Society of Malaysia (NCSM) in Kuala Lumpur, from Jan 2016 until Dec 2017 (2 years). Patients were surveyed on: i) age, ii) ethnicity, iii) family history of breast or any cancers, if any, iv) reproductive history (age of menarche, age of first delivery, age of menopause); and v) history of postmenopausal estrogen and hormone replacement therapy (HRT). Bivariate analysis was conducted by using χ2 tests in determining associations between variables and a multiple logistic regression model built to identify factors which were predictive of an abnormal mammogram finding (BI-RADS 4 & 5). Results: From the bivariate analysis; nulliparous status ( P = 0.02), a family history of breast cancer ( P = 0.04), and a history of postmenopausal hormone replacement therapy (HRT) ( P = 0.01) were determined to significantly associated with an abnormal mammogram finding. There were also significant ethnic differences between women who had abnormal mammogram findings; with Chinese women having highest odds of this (OR:3.22; 95% CI 1.86-5.74). Women within the age group of 45-54 (OR:1.84, 95% CI 1.19-3.12), a family history of breast cancer (OR 2.03, 95% CI 1.31-3.27) or any cancer (OR 1.56, 95% CI 1.06-2.94), age of menopause (OR 2.86; 95% CI 1.43-4.02) and age of first delivery above 30 (OR 1.73, 95% CI 1.26-3.45) were significantly associated with abnormal mammogram findings. Conclusion: Factors which predict abnormal mammogram findings in a Malaysian setting can be used as baseline evidence to formulate criteria which can be used to carry out targeted screening programs or even as cutoff criteria for focusing screening resources in resource-limited settings. This data may be of benefit in aiding healthcare providers in provisioning of services at a macro level as well as for frontline healthcare personnel in helping them profile women who should be focused on to be screened for the disease.

Optical detection and charge-state analysis of MALDI-generated particles with molecular masses larger than 5 MDa

Charged polystyrene nanoparticles are generated by matrix-assisted laser desorption/ionization (MALDI) and detected by laser-induced fluorescence (LIF) in a quadrupole ion trap. Employing the LIF technique, observations of individual fluorescent nanospheres (27 nm in diameter and containing 180 fluorescein dye equivalents) have been achieved with an average signal-to-noise ratio of approximately 10. With the trap operating at a frequency around 5 kHz, charge state analysis of the particles reveals that the number of charges carried by the spheres is between 1 and 10. It suggests a mass-to-charge ratio (m/z) in the range of 10(5)-10(6) for the MALDI-generated particles. To effectively trap such large particles (m > 5 MDa), damping of the particles' motions by using approximately 50 mTorr He buffer gas is absolutely required. Similar findings are obtained for particles with a nominal size of 1 microm in diameter, demonstrating that production of charged particles with a molecular mass as high as 10(12) Da is possible using the MALDI technique.