POS0732 IDENTIFICATION OF AUTOPHAGY-RELATED PHENOTYPES IN PRIMARY SJOGREN’S SYNDROME

Background:

Primary Sjogren’s syndrome (pSS) is a chronic systemic autoimmune disease characterized by disorders of effector T cell subpopulations such as Th1, Th2, Th17, regulatory T cells, and follicular helper T cells 1 2. Autophagy is an evolutionarily conserved self-digestion process that plays an important role in T cell-mediated immune response3. The relationship between autophagy and T cell subsets was unclear in pSS up till now.

Objectives:

To landscape the autophagy-related multiple gene expression signature in pSS classification and discover the influence of autophagy in T cell subsets.

Methods:

Gene expression profiles of pSS samples (GSE66795, GSE51092, GSE154926) were acquired from GEO database. A set of significant G-ATGs were intersected from the global gene of patients and 232 autophagy genes (ATGs) which were obtained from the Human Autophagy Database (HADb, http://www.autophagy.lu/). In training dataset (GSE66795, including 155 patients and 29 healthy controls), non-negative matrix factorization was used to divided patients by G-ATGs expression microarray data. An autophagy score model divided patients into the high-autophagy score and low groups by ssGSEA scores of gene according to normalized G-ATGs training data. Further, new classifications were validated by both peripheral blood samples (GSE51092, 90 patients) and salivary gland tissue (GSE154926, 43 participants).

Results:

Two distinct subtypes were identified and validated by 206 selected significant G-ATGs in training datasets (figure 1A,B) and validation datasets according to the autophagy score (figure 1D,E,F) Combined with clinical information of salivary gland dataset, it was found that most patients with early pSS were grouped in the high autophagy, while advanced patients were grouped in the low (figure 1G). Patients in high-autophagy group had higher levels of Treg cells and Th2 cells but lower concentrations of Th17 and Th1 in peripheral blood (figure 1C, P <0.05). Similar results were also observed in salivary gland tissue (figure 1H, P <0.05).

Conclusion:

Patients with different autophagy status differs from each other. Autophagy is closely corelated with lymphocyte subpopulations in patients with pSS. This work may help inform therapeutic decision-making for the treatment of pSS.

References:

[1]Colafrancesco S, Vomero M, Iannizzotto V, et al. Autophagy occurs in lymphocytes infiltrating Sjögren’s syndrome minor salivary glands and correlates with histological severity of salivary gland lesions. Arthritis research & therapy 2020;22(1):238. doi: 10.1186/s13075-020-02317-6 [published Online First: 2020/10/15].

[2]Alessandri C, Ciccia F, Priori R, et al. CD4 T lymphocyte autophagy is upregulated in the salivary glands of primary Sjögren’s syndrome patients and correlates with focus score and disease activity. Arthritis research & therapy 2017;19(1):178. doi: 10.1186/s13075-017-1385-y [published Online First: 2017/07/27].

[3]Wei J, Long L, Yang K, et al. Autophagy enforces functional integrity of regulatory T cells by coupling environmental cues and metabolic homeostasis. Nature immunology 2016;17(3):277-85. doi: 10.1038/ni.3365 [published Online First: 2016/01/26].

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

AB0824 ANALYSIS OF GUT MICROBIOTA IN RHEUMATOID ARTHRITIS PATIENTS

Background:

Gastrointestinal microbiota, particularly gut microbiota is an indispensable environmental factor in the progression of Rheumatoid Arthritis (RA). Understanding the diversity and function of the intestinal flora in patients with RA is part and parcel to understand the relationship between microbiota and human health.

Objectives:

This study aimed to identify the diversity and function of the intestinal flora in patients with RA.

Methods:

A total of 166 participants were recruited in this study, comprising 93 RA patients and 73 age and sex-matched healthy controls (HCs). Microbial genome was extracted from approximately 250mg fresh fecal samples from all participants using QIAamp PowerFecal DNA Kit (Qiagen). The V3-V4 variable regions of bacterial 16S rRNA genes were sequenced with the Illumina Miseq PE300 system. Sequence data were compiled and processed using Qiime2. Sequences were grouped into operational taxonomic units (ASVs)1. Microbial diversity was estimated by the Simpson index. PICRUSt2 was used to predict KEGG functional pathway differences between RA and HC intestinal flora functions based on ASV Tables2. Linear Discriminant Analysis (LDA) Effect Size (LEfSe) analysis was performed using LEfSe software to discovery the different intestinal flora and functions between RA and healthy.

Results:

The alpha-diversity index of Simpson the microbiome in RA patients was lower than that of HCs (Figure 1a, P <0.05). Compared with HCs, bacterial Bacilli and Lactobacillales were more abundant in patients with RA (Figure 1b, P <0.05). In contrast, Marinifilaceae, Peptococcaceae, Peptococcales and Phascolarcto bacterium were less abundant in the RA group (Figure 1b, P <0.05). As shown in Figure 1c, propanoate metabolism, taurine and hypotaurine metabolism, ascorbate and aldarate metabolism, biosynthesis of siderophore group nonribosomal peptides and glutathione metabolism were the most significantly altered pathways in RA (P <0.05). Epithelial cell signaling in Helicobacter pylori infection, RNA transport, RNA degradation and plant-pathogen interaction were the most significantly altered pathways in HC (P <0.05). The different KEGG metabolic pathways were mainly concentrated in carbohydrate and amino acid metabolism.

Conclusion:

Gut dysbiosis in RA patients mainly characterized by reduced the diversity and impaired abundance of the intestinal flora, which severely influence the metabolism of gastrointestinal microbiota. The discovery of the associated intestinal microbiota of RA may provide a new idea for RA treatment.

References:

[1]Han L, Zhao K, Li Y, et al. A gut microbiota score predicting acute graft-versus-host disease following myeloablative allogeneic hematopoietic stem cell transplantation. Am J Transplant 2020;20(4):1014-27. doi: 10.1111/ajt.15654 [published Online First: 2019/10/13]

[2]Liss MA, White JR, Goros M, et al. Metabolic Biosynthesis Pathways Identified from Fecal Microbiome Associated with Prostate Cancer. Eur Urol 2018;74(5):575-82. doi: 10.1016/j.eururo.2018.06.033 [published Online First: 2018/07/17]

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

POS0736 IDENTIFICATION OF MOLECULAR PHENOTYPES AND IMMUNE CELL INFILTRATION IN SYSTEMIC LUPUS ERYTHEMATOSUS PATIENTS ACCORDING TO LONGITUDINAL GENE EXPRESSION

Background:

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with highly heterogeneous clinical presentation characterized by disease unpredictable flares and multi-systemic involvement1 2. This clinical heterogeneity calls for design a molecular stratification to improve clinical trial design and formulate personalization treatment therapies.

Objectives:

This research was conducted to develop a reliable method to stratify SLE patients combined gene expression information and disease status.

Methods:

The mRNA expression profile of GSE138458 (contained 307 patients and 23 controls) and GSE49454 (contained 111 patients and 16 controls) were downloaded from the publicly GEO databases. After background adjustment, batch correction, and other pre-procession, obtaining a big gene matrix to identify the differentially expressed genes (DEGs) in SLE compared with healthy controls, which were screened by P value < 0.01. SLE subtypes were identified by non-negative matrix factorization (NMF) based on DEGs. Acquired signature genes in different SLE subtypes were conducted to process pathway enrichment analysis in Metascape. SLEDAI score and immune cell infiltration was also performed between subtypes by software package R (version 4.0.3).

Results:

Total 1202 DEGs were imputed to NMF unsupervised machine learning method. Patients with SLE were stratified into two subsets based on 184 signature genes derived from obtained DEGs(Fig.1A, 1B). GO and KEGG enrichment analysis showed that signature genes were mainly involved in negative regulation of innate immune response, toll-like receptor signaling pathway, regulation of immune effector process and so on(Fig.1C). Patients in Sub1 group had severe disease activity measures compared with those in Sub2(Fig.1D). SLEDAI scores from GSE49454 dataset were also higher in Sub1 compare with Sub2(Fig.1E). Further, immune cell infiltration results revealed an insufficient of regulatory T cell, CD8 T cells and naive CD4 T cells in Sub1 and neutrophils cells in Sub2(P<0.05)(Fig.1F).

Conclusion:

Our findings indicate that patients with SLE could be stratified into 2 subtypes which had different lymphocyte status and closely related to disease activity. This phenotyping may help us understand the etiology of the disease, inform patient in the design of clinical trials and guide treatment decision.

References:

[1]Dorner T, Furie R. Novel paradigms in systemic lupus erythematosus. Lancet 2019;393(10188):2344-58. doi: 10.1016/S0140-6736(19)30546-X [published Online First: 2019/06/11].

[2]Fanouriakis A, Tziolos N, Bertsias G, et al. Update οn the diagnosis and management of systemic lupus erythematosus. Annals of the rheumatic diseases 2021;80(1):14-25. doi: 10.1136/annrheumdis-2020-218272 [published Online First: 2020/10/15].

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

POS0859 DEEP PHENOTYPING OF DERMATOMYOSITIS BASED ON LIPID FERROPTOSIS-RELATED GENES BY MACHINE LEARNING

Background:

Dermatomyositis (DM) is an idiopathic inflammatory myopathy with heterogeneous clinical manifestation that raise challenges regarding diagnosis and therapy1. Ferroptosis is a newly discovered form of regulated cell death that is the nexus between metabolism, redox biology, and rheumatic immune diseases2. However, how ferroptosis maintains the balance of lymphocyte T cells and affect disease activity in DM is unclear.

Objectives:

To investigate an ferroptosis-related multiple gene expression signature for classification by assessing the global gene expression profile, and calculate the lymphocyte T cells status in the different subsets.

Methods:

Gene expression profiles of skeletal muscle from DM samples were acquired from GEO database. GSE143323 (30 patients and 20 HCs) was selected as the training set. The GSE3307 contained 21 DM patients and was selected as the validation set. The 60 ferroptosis genes were obtained from previous literature3. The intersection of the global gene and ferroptosis genes was considered the set of significant G-Ferroptosis genes for further analysis. The “NMF” (R-package) was applied as an unsupervised clustering method for sample classification by using G-Ferroptosis genes expression microarray data from the training datasets. An ferroptosis score model was constructed. The performance of the ferroptosis genes-based risk score model constructed by the DM training set was validated in the batch-1 and batch-2 DM sets. Normalized ferroptosis genes training data was used to compare the ssGSEA scores of gene sets between the high risk and low risk group. The statistical software package R (version 4.0.3) was used for all analyses. P value < 0.05 were considered statistically significant.

Results:

We selected 54 significant G-Ferroptosis genes for further analysis in training set. There were 2 distinct subtypes (high-ferroptosis-score groups and low-ferroptosis-score groups) identified in G-Ferroptosis genes cohort which were also identified in validation datasets (Fig.1A, C, D). Metallothionein 1G (MT1G) was a characteristic gene of low-ferroptosis-score group. The characteristic genes of high-ferroptosis-score group were acyl-CoA synthetase family member 2(ACSF2) and aconitase 1(ACO1) (Fig.1B). Patients in high-ferroptosis-score group had a lower level of Tregs compared with that of low-ferroptosis-score patients in both training and validation set (P <0.05, Fig.1E).

Conclusion:

The biological process of ferroptosis is associated with the lever of Tregs, suggesting the process of ferroptosis may be involved in the disease progression of DM. Identificating ferroptosis-related features for DM might provide a new idea for clinical treatment.

References:

[1]DeWane ME, Waldman R, Lu J. Dermatomyositis: Clinical features and pathogenesis. Journal of the American Academy of Dermatology 2020;82(2):267-81. doi: 10.1016/j.jaad.2019.06.1309 [published Online First: 2019/07/08].

[2]Liang C, Zhang X, Yang M, et al. Recent Progress in Ferroptosis Inducers for Cancer Therapy. Advanced materials (Deerfield Beach, Fla) 2019;31(51):e1904197. doi: 10.1002/adma.201904197 [published Online First: 2019/10/09].

[3]Liang JY, Wang DS, Lin HC, et al. A Novel Ferroptosis-related Gene Signature for Overall Survival Prediction in Patients with Hepatocellular Carcinoma. International journal of biological sciences 2020;16(13):2430-41. doi: 10.7150/ijbs.45050 [published Online First: 2020/08/08].

Acknowledgements:

This project was supported by National Science Foundation of China (82001740).Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

Circular RNA hsa_circ_0091579 facilitates the Warburg effect and malignancy of hepatocellular carcinoma cells via the miR-624/H3F3B axis

BACKGROUND

Hepatocellular carcinoma (HCC) is a primary liver cancer with a high mortality rate. It has been reported that circular RNA hsa_circ_0091579 (circ_0091579) is involved in HCC progression. Nevertheless, the molecular mechanism by which circ_0091579 modulates HCC advancement is indistinct.

METHODS

The expression of circ_0091579, microRNA (miR)-624, and H3 histone family member 3B (H3F3B) mRNA was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of HCC cells were analyzed using an extracellular flux analyzer. Adenosine triphosphate (ATP) level was evaluated using a commercial kit. Cell migration, invasion, and apoptosis were assessed by wound-healing, transwell, or flow cytometry assay. The relationship between miR-624 and circ_0091579 or H3F3B was verified using luciferase reporter assay and/or RNA immunoprecipitation (RIP) assay. H3F3B protein level was detected by western blotting.

RESULTS

Circ_0091579 was upregulated in HCC tissues and cells. Circ_0091579 inhibition decreased xenograft tumor growth in vivo and repressed Warburg effect, migration, invasion, and induced apoptosis of HCC cells in vitro. MiR-624 was downregulated, while H3F3B was upregulated in HCC tissues and cells. Circ_0091579 acted as a miR-624 sponge and regulated H3F3B expression by adsorbing miR-624. MiR-624 inhibitor reversed circ_0091579 downregulation-mediated effects on the Warburg effect and malignant behaviors of HCC cells. H3F3B overexpression reversed the repressive impact of miR-624 mimic on the Warburg effect and malignancy of HCC cells.

CONCLUSIONS

Circ_0091579 accelerated Warburg effect and tumor growth via upregulating H3F3B via adsorbing miR-624 in HCC, providing evidence to support the involvement of circ_0091579 in the progression of HCC.

Emerging materials for the electrochemical detection of COVID-19

The SARS-CoV-2 virus is still causing a dramatic loss of human lives worldwide, constituting an unprecedented challenge for the society, public health and economy, to overcome. The up-to-date diagnostic tests, PCR, antibody ELISA and Rapid Antigen, require special equipment, hours of analysis and special staff. For this reason, many research groups have focused recently on the design and development of electrochemical biosensors for the SARS-CoV-2 detection, indicating that they can play a significant role in controlling COVID disease. In this review we thoroughly discuss the transducer electrode nanomaterials investigated in order to improve the sensitivity, specificity and response time of the as-developed SARS-CoV-2 electrochemical biosensors. Particularly, we mainly focus on the results appeard on Au-based and carbon or graphene-based electrodes, which are the main material groups recently investigated worldwidely. Additionally, the adopted electrochemical detection techniques are also discussed, highlighting their pros and cos. The nanomaterial-based electrochemical biosensors could enable a fast, accurate and without special cost, virus detection. However, further research is required in terms of new nanomaterials and synthesis strategies in order the SARS-CoV-2 electrochemical biosensors to be commercialized.

Unraveling COVID-19: a large-scale characterization of 4.5 million COVID-19 cases using CHARYBDIS

Background: Routinely collected real world data (RWD) have great utility in aiding the novel coronavirus disease (COVID-19) pandemic response [1,2]. Here we present the international Observational Health Data Sciences and Informatics (OHDSI) [3] Characterizing Health Associated Risks, and Your Baseline Disease In SARS-COV-2 (CHARYBDIS) framework for standardisation and analysis of COVID-19 RWD. Methods: We conducted a descriptive cohort study using a federated network of data partners in the United States, Europe (the Netherlands, Spain, the UK, Germany, France and Italy) and Asia (South Korea and China). The study protocol and analytical package were released on 11 th June 2020 and are iteratively updated via GitHub [4]. Findings: We identified three non-mutually exclusive cohorts of 4,537,153 individuals with a clinical COVID-19 diagnosis or positive test, 886,193 hospitalized with COVID-19 , and 113,627 hospitalized with COVID-19 requiring intensive services . All comorbidities, symptoms, medications, and outcomes are described by cohort in aggregate counts, and are available in an interactive website: https://data.ohdsi.org/Covid19CharacterizationCharybdis/. Interpretation: CHARYBDIS findings provide benchmarks that contribute to our understanding of COVID-19 progression, management and evolution over time. This can enable timely assessment of real-world outcomes of preventative and therapeutic options as they are introduced in clinical practice.

[Determination of mifepristone in workplace air by ultra-performance liquid chromatography]

Objective: To establish an ultra-high performance liquid chromatography method for the determination of mifepristone in the air of workplaces. Methods: From January to July 2018, glass fiber filter membrane was used to collect mifepristone in the workplace air, eluted with acetonitrile/water solution, and determined by ultra-high performance liquid chromatography-UV method. Results: The detection limit of mifepristone determination method was 0.005 μg/ml, the lower limit of quantification was 0.015 μg/ml, and the lowest detection concentration was 0.14 μg/m(3) (calculated by collecting 75 L air samples) . The concentration of mifepristone has a good linear relationship between 0.015-40.24 μg/ml, r=0.9999. The accuracy and elution efficiency of the method were calculated based on the recovery rate, ranging from 92.7% to 100.0%. The average sampling efficiency was 99.6%-100.0%. The intra-assay precision of the method was 0.92% to 5.41%, and the inter-assay precision was 0.89% to 6.25%. The sample could be stored stably for 3 days at 4°C. Conclusion: The ultra-high performance liquid chromatography method for determination of mifepristone is easy to operate, and its indicators meet the requirements of GBZ/T 201.4-2008 "Guidelines for the Establishment of Occupational Hygiene Standards Part 4: Methods for Determination of Chemical Substances in Workplace Air", which is suitable for the detection of mifepristone in the air of the workplace.

Deep phenotyping of 34,128 adult patients hospitalised with COVID-19 in an international network study

Comorbid conditions appear to be common among individuals hospitalised with coronavirus disease 2019 (COVID-19) but estimates of prevalence vary and little is known about the prior medication use of patients. Here, we describe the characteristics of adults hospitalised with COVID-19 and compare them with influenza patients. We include 34,128 (US: 8362, South Korea: 7341, Spain: 18,425) COVID-19 patients, summarising between 4811 and 11,643 unique aggregate characteristics. COVID-19 patients have been majority male in the US and Spain, but predominantly female in South Korea. Age profiles vary across data sources. Compared to 84,585 individuals hospitalised with influenza in 2014-19, COVID-19 patients have more typically been male, younger, and with fewer comorbidities and lower medication use. While protecting groups vulnerable to influenza is likely a useful starting point in the response to COVID-19, strategies will likely need to be broadened to reflect the particular characteristics of individuals being hospitalised with COVID-19.

Reduced miR-363-3p expression in non-small cell lung cancer is associated with gemcitabine resistance via targeting of CUL4A

OBJECTIVE

Accumulating evidence has suggested that aberrant expression of microRNAs (miRNAs) is associated with non-small cell lung cancer (NSCLC) proliferation, migration, invasion and chemotherapy resistance. Cullin4A (CUL4A) has been previously reported to desensitize NSCLC cells to chemotherapy treatment. However, whether miRNAs regulate CUL4A to promote chemotherapy resistance remains unknown.

PATIENTS AND METHODS

Tissues were obtained from 40 NSCLC patients who received surgery at the Yancheng City No. 1 People's Hospital. Cell Counting Kit-8 (CCK-8) assays were applied for the detection of cell proliferation; mRNA and protein levels were determined by Real Time-quantitative Polymerase Chain Reaction (RT-qPCR) and Western blot, respectively. The interaction between mRNA 3'UTR and miRNA was predicted by TargetScan and verified by Dual-Luciferase reporter assay.

RESULTS

In the present study, miR-363-3p levels were revealed to be significantly decreased in tumor tissues obtained from NSCLC patients compared with adjacent normal tissues. The results of the CCK-8 assays showed that the overexpression of miR-363-3p may slightly inhibit the proliferation of A549 and H23 cells. Notably, the transfection with miR-363-3p antagonists reduced the sensitivity of A549 and H23 cells to gemcitabine treatment, whereas the overexpression of miR-363-3p markedly increased the sensitivity of A549 and H23 cells to gemcitabine treatment. Furthermore, CUL4A mRNA and protein levels were revealed to be decreased in A549 cells transfected with miR-363-3p mimics. The Dual-Luciferase reporter assay results further suggested that CUL4A represents a target gene of miR-363-3p.

CONCLUSIONS

The results indicated that decreased miR-363-3p expression enhanced gemcitabine resistance in NSCLC cells via regulation of CUL4A.

Deep phenotyping of 34,128 patients hospitalised with COVID-19 and a comparison with 81,596 influenza patients in America, Europe and Asia: an international network study

Background In this study we phenotyped individuals hospitalised with coronavirus disease 2019 (COVID-19) in depth, summarising entire medical histories, including medications, as captured in routinely collected data drawn from databases across three continents. We then compared individuals hospitalised with COVID-19 to those previously hospitalised with influenza. Methods We report demographics, previously recorded conditions and medication use of patients hospitalised with COVID-19 in the US (Columbia University Irving Medical Center [CUIMC], Premier Healthcare Database [PHD], UCHealth System Health Data Compass Database [UC HDC], and the Department of Veterans Affairs [VA OMOP]), in South Korea (Health Insurance Review & Assessment [HIRA]), and Spain (The Information System for Research in Primary Care [SIDIAP] and HM Hospitales [HM]). These patients were then compared with patients hospitalised with influenza in 2014-19. Results 34,128 (US: 8,362, South Korea: 7,341, Spain: 18,425) individuals hospitalised with COVID-19 were included. Between 4,811 (HM) and 11,643 (CUIMC) unique aggregate characteristics were extracted per patient, with all summarised in an accompanying interactive website (http://evidence.ohdsi.org/Covid19CharacterizationHospitalization/). Patients were majority male in the US (CUIMC: 52%, PHD: 52%, UC HDC: 54%, VA OMOP: 94%,) and Spain (SIDIAP: 54%, HM: 60%), but were predominantly female in South Korea (HIRA: 60%). Age profiles varied across data sources. Prevalence of asthma ranged from 4% to 15%, diabetes from 13% to 43%, and hypertensive disorder from 24% to 70% across data sources. Between 14% and 33% were taking drugs acting on the renin-angiotensin system in the 30 days prior to hospitalisation. Compared to 81,596 individuals hospitalised with influenza in 2014-19, patients admitted with COVID-19 were more typically male, younger, and healthier, with fewer comorbidities and lower medication use. Conclusions We provide a detailed characterisation of patients hospitalised with COVID-19. Protecting groups known to be vulnerable to influenza is a useful starting point to minimize the number of hospital admissions needed for COVID-19. However, such strategies will also likely need to be broadened so as to reflect the particular characteristics of individuals hospitalised with COVID-19.

Risk of SARS-CoV-2 infection among contacts of individuals with COVID-19 in Hangzhou, China

Objectives

This study determined the rate of secondary infection among contacts of individuals with confirmed coronavirus disease 2019 (COVID-19) in Hangzhou according to the type of contacts, the intensity of contacts, and their relationship with the index patient.

Study design

This is a retrospective cohort study.

Methods

The analysis used the data of 2994 contacts of 144 individuals with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The contacts were categorized according to the information source, type of contact, location, intensity of contact, and relationship with the index patient.

Results

The incidence of infection differed significantly according to contact type. Of the contacts, 186 (6.2%) developed symptoms, and 71 (2.4%) had confirmed SARS-CoV-2 infection. The main symptoms were cough and fever. Compared with those who had brief contact with the index case, those who had dined with the index case had 2.6 times higher risk of acquiring infection; those who had shared transport with, had visited, or had contact with the index case in a medical institution had 3.6 times higher risk of acquiring infection; and household contacts had 41.7 times higher risk of acquiring infection. Family members had 31.6 times higher risk of acquiring infection than healthcare providers or other patients exposed to an index case.

Conclusions

The form and frequency of contact are the main factors affecting the risk of infection among contacts of individuals with COVID-19. Centralized isolation and observation of close contacts of individuals with confirmed SARS-CoV-2 infection, in addition to population-based control measures, can reduce the risk of secondary infections and curb the spread of the infection.

•

The incidence of infection differed significantly according to contact type.

•

Contact form and frequency are important to the risk of COVID-19.

•

Centralized isolation and observation of contacts curbed the spread of the infection.

Abstract PR05: A genetic variant at 6q25 associated with estrogen receptor-negative breast cancer subtypes in Peruvian breast cancer patients

Background: We have previously identified a genetic variant, rs140068132, which has a strong protective effect on breast cancer risk. This variant is located near the estrogen receptor 1 gene (ESR1) on chromosome 6q25, a locus which has been repeatedly implicated in breast cancer risk. Women who carry two copies of the protective variant (GG) have 60-70% reduction in risk of developing breast cancer compared to women with none. The G variant has relatively high frequency in Latin American women (up to 23% in the 1000 Genomes Project Peruvians); it is only common in people of Indigenous American ancestry and almost absent in all other populations. We investigated whether the rs140068132-A/G polymorphism is associated with a specific breast cancer subtype among Peruvian women with breast cancer.

Methods: Blood samples and clinical data were collected from 441 women with breast cancer at the Instituto Nacional de Enfermedades Neoplasicas in Lima, Peru. Genotypic profiles were generated using the Affymetrix Precision Medicine Research Array. Four major breast cancer subtypes were identified based on immunohistochemical markers (luminal A, luminal B, triple-negative, and human epidermal growth factor receptor 2 (HER2) overexpressing). Quality control of the genotyped data was performed in PLINK. Genetic ancestry was determined for each individual using ADMIXTURE. ANOVAs were performed on the proportion of genetic ancestry and disease subtype. PLINK was used to perform a binary logistic regression on the rs140068132 variant and ER status (ER-negative versus-ER positive), with age and genetic ancestry as covariates.

Results: The breast cancer patients analyzed have the following average ancestry proportions: 77.3% Indigenous American, 17.4% European, 3.8% African and 1.5% East Asian. The frequency of the G allele in the Peruvian breast cancer patients is 14% (compared to 23% in healthy individuals from the 1000 Genomes Project). We found that the G allele of rs140068132 was associated with ER-negative status among cases (OR = 0.6443, P = 0.086) for both HER2 overexpressing and triple-negative. We also examined the proportions of ancestry in relation to subtypes of disease. The proportion of Indigenous American ancestry was associated with the HER2 overexpressing subtype (P = 0.06), with an average Indigenous American ancestry among these patients of 83.1% compared to 77.3% among all patients. The proportion of African ancestry was higher in women with the triple-negative subtype, with an average African ancestry of 4.8% among patients with the triple-negative subtype compared to a 3.8% average among all patients, but this trend was not statistically significant (P = 0.21).

Conclusions: The lower frequency of the variant in Peruvian breast cancer cases is consistent with a protective effect in this population. We have confirmed that the protective effect of the rs140068132 variant is stronger for ER-negative subtypes. Additional analyses are under way in a larger sample of Peruvian breast cancer patients.

This abstract is also being presented as Poster C051.

Citation Format: K.M. Marker, T. Vidaurre, L.I. Tamayo, J.N. Vásquez, R. Meza Florez, S. Casavilca, M. Calderon, J.E. Abugattas, H.L. Gómez, H.A. Fuentes, C.L. Monge Pimentel, S. Song, D. Cherry, S. Huntsman, D. Hu, E. Ziv, L. Fejerman. A genetic variant at 6q25 associated with estrogen receptor-negative breast cancer subtypes in Peruvian breast cancer patients [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr PR05.

[Determination of tungsten and insoluble compounds in the air of workplace by ICP-OES]

Objective: To establish the method for determination of tungsten and insoluble compounds in the air of workplace by inductively coupled plasma optical emission spectrometry (ICP-OES) . Methods: The tungsten and insoluble compounds were digested by microwave digestion apparatus using nitric acid and hydrofluoric acid, detected by ICP-OES. Results: The linearity of tungsten and insoluble compounds (as tungsten) were good at the range of 0.16-100.0 μg/ml, the minimum quantitation concentration was 0.11 mg/m(3), the recovery was ranged from 81.9%-97.1%, the RSD of intra-and inter-batch precision were 0.5%-2.5% and 1.2%-4.4%, respectively. Conclusion: The determination method meet the requirement of analysis and apply to the determination of tungsten and insoluble compounds in the air of workplace.

Direct investigation of current transport in cells by conductive atomic force microscopy

Currents play critical roles in neurons. Direct observation of current flows in cells at nanometre dimensions and picoampere current resolution is still a daunting task. In this study, we investigated the current flows in hippocampal neurons, PC12 cells and astrocytes in response to voltages applied to the cell membranes using conductive atomic force microscopy (CAFM). The spines in the hippocampal neurons play crucial roles in nerve signal transfer. When the applied voltage was greater than 7.2 V, PC12 cells even show metallic nanowire-like characteristics. Both the cell body and glial filaments of astrocytes yielded CAFM test results that reflect different electrical conductance. To our best knowledge, the electrical characteristics and current transport through components of cells (especially neurons) in response to an applied external voltage have been revealed for the first time at nanometre dimensions and picoampere current levels. We believe that such studies will pave new ways to study and model the electrical characteristics and physiological behaviours in cells and other biological samples.