AB0143 EXPRESSION OF HERV-E CLONE 4.1 GAG TRANSCRIPTS IN PERIPHERAL BLOOD MONONUCLEAR CELLS OF SYSTEMIC LUPUS ERYTHEMATOSUS PATIENTS

Abstract

Background:Human endogenous retrovirus (HERV)-E clone 4.1gagtranscripts have been detected in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus (SLE) patients and seem to be associated to autoantibody production. To date, no study aimed to investigate whether their expression in cytokine-stimulated vs. unstimulated PBMCs of SLE patients could be related with clinical manifestations.Objectives:We aimed to correlate the expression of HERV-E clone 4.1gagtranscripts of unstimulated and phyto-haemoagglutinin (PHA) and interleukin-2 (IL-2)-stimulated PBMCs of SLE patients and healthy controls (HCs) and to evaluate the association between their expression and the demographic and clinical data of the SLE cohort.Methods:PBMCs were isolated from 18 SLE patients and 22 age- and gender-matched controls. Cells from 10 SLE patients and 15 HCs were harvested for RNA isolation, HERV-E clone 4.1gag- and RPL-13-selective cDNA synthesis and SYBR Green RT-PCR analysis. The expression ofgagtranscripts was normalized to that of the housekeeping gene RPL-13, using the Pfaffl method. PBMCs of the remaining patients and HCs were stimulated with PHA/IL-2 and HERV- E clone 4.1gagexpression assessed as described before. Statistical analysis was carried using a SPSS software, version n.23.Results:Table 1 presents the demographic data of patients. The normalized mean ± SDgagexpression was 1.6 ± 2.2 and 0.80 ± 0.79 in unstimulated PBMCs of SLE patients and HCs, respectively; and 1.1 ± 0.7 and 1.1 ± 0.4 in stimulated SLE and HC PBMCs, respectively. No significant difference emerged between patients and controls and between stimulated and unstimulated PBMCs (fig. 1).Gagtranscripts expressed in PHA/IL-2-stimulated PBMCs of SLE patients significantly correlated with oronasal ulcers and high titers of anti- dsDNA antibodies (p=0.01 and p=0.004, respectively), whilegagtranscripts of unstimulated SLE PBMCs were significantly associated to the number of ACR criteria fulfilled (p=0.02).Table 1Demographic and clinical characteristics of SLE patientsOverall cohort of SLE patients (n.18)Unstimulated conditionsStimulated conditionsPNumber of patients109>0.05GenderFemaleFemale>0.05Mean age ± SD at diagnosis (years)40.6 ± 14.626.4 ± 6.50.001Mean disease duration ± SD (years)12.9 ± 6.311.8 ± 7.6>0.05Mean SLEDAI ± SD8.0 ± 5.85.7 ± 4.60.004Mean SLICC ± SD2.3 ± 2.31.6 ± 1.4>0.05Central nervous system involvement (n.,%)1, 10%1, 11.1%>0.05Renal involvement (n.,%)0, 0%1, 11.1%>0.05Cutaneous involvement and photosensitivity (n.,%)9, 90%8, 88.8%>0.05Oronasal ulcers (n., %)3, 30%3, 33.3%>0.05Joint involvement (n.,%)8, 80%6, 66.6%>0.05Hematologic involvement (n., %)4, 40%6, 66.6%0.003Serositis (n., %)1, 10%4, 44.4%0.046Anti-nuclear antibodies (n., %)10, 100%9, 100%>0.05Anti-double stranded DNA antibodies (*103IU/L), mean ± SD15.4 ± 16.726.8 ± 74.3>0.05Mean C3 ± SD levels (g/L)0.88 ± 0.121.2 ± 1.10.001Mean C4 ± SD levels (g/L)0.11 ± 0.030.16 ± 0.08>0.05Chloroquine (n., %)5, 50%8, 88.8%>0.05Figure 1.HERV-E clone 4.1gagtranscript normalized expression in unstimulated (a) and PHA/IL-2- stimulated (b) PBMCs of SLE patients and controlsConclusion:According to these preliminary findings, the expression of HERV-E clone 4.1gagtranscripts in unstimulated and stimulated PBMCs does not significantly differ between SLE patients and controls. The significant association with some clinical variables in SLE patients needs to be confirmed on wider cohorts.