Tissue-Specific Knockdown of Genes of the Argonaute Family Modulates Lifespan and Radioresistance in Drosophila Melanogaster

Small RNAs are essential to coordinate many cellular processes, including the regulation of gene expression patterns, the prevention of genomic instability, and the suppression of the mutagenic transposon activity. These processes determine the aging, longevity, and sensitivity of cells and an organism to stress factors (particularly, ionizing radiation). The biogenesis and activity of small RNAs are provided by proteins of the Argonaute family. These proteins participate in the processing of small RNA precursors and the formation of an RNA-induced silencing complex. However, the role of Argonaute proteins in regulating lifespan and radioresistance remains poorly explored. We studied the effect of knockdown of Argonaute genes (AGO1, AGO2, AGO3, piwi) in various tissues on the Drosophila melanogaster lifespan and survival after the γ-irradiation at a dose of 700 Gy. In most cases, these parameters are reduced or did not change significantly in flies with tissue-specific RNA interference. Surprisingly, piwi knockdown in both the fat body and the nervous system causes a lifespan increase. But changes in radioresistance depend on the tissue in which the gene was knocked out. In addition, analysis of changes in retrotransposon levels and expression of stress response genes allow us to determine associated molecular mechanisms.

AB0497 RENAL INVOLVEMENT IN ANCA-ASSOCIATED VASCULITIS: DO THE PRESENCE OF ANCA AND THEIR TYPE MATTER?

Background:

The role of ANCA type is well established for the risk of relapses of ANCA-associated vasculitis (AAV). However their association with renal involvement and its outcomes is less well understood.

Objectives:

To assess clinical and morphological features of ANCA-associated glomerulonephritis (ANCA-GN) and renal survival in ANCA-negative patients, proteinase-3-ANCA (pr3-ANCA) positive and myeloperoxidase-ANCA (MPO-ANCA) positive patients.

Methods:

We enrolled 53 patients with AAV, diagnosed according to Chapel Hill Consensus Conference (2012) definition and/or ACR (1990) criteria, with histologically proven renal involvement. There were 13 (24.5%) males, median age at onset was 48 (33; 57) years. Seven patients were ANCA-negative (13.3%), 17 (32.0%) patients were pr-3-ANCA positive and 29 (54.7%) patients were MPO-ANCA-positive. ANCA-associates glomerulonephritis (ANCA-GN) class was established according to Berden et al classification.1We retrospectively assessed ANCA renal risk score (ARRS) at disease onset.2Twelve patients (22.6%) developed end-stage renal disease (ESRD) after a median of 12 (6.5; 28) months. Renal survival rates were assessed by Kaplan-Meier method and compared by log-rank test.

Results:

The only significant difference was median BVAS score which was significantly higher in pr3-ANCA-positive (18 (17;20)) than in MPO-ANCA positive patients (15 (12; 18), p=0.012). Creatinine levels, eGFR, percentage of glomeruli with crescents, global sclerosis, and interstitial fibrosis and tubular atrophy didn’t depend on the presence of ANCA or type of the antibodies. The proportion of patients with focal, crescentic, mixed of sclerotic class of ANCA-GN was similar in all groups. There was no significant difference in the numbers of patients with low, medium or high risk of ESRD according to ARRS. One- and three-year renal survival rates were similar in ANCA-negative (81.7% and 60.0% respectively) and ANCA-positive patients (84.2% and 74.6% respectively, Figure 1A). One-year and three-year survival rates were higher in MPO-ANCA-positive (84.4% and 84.4% respectively) than in pr3-ANCA-positive patients (73.1% and 50.1% respectively), however the difference was not statistically significant (Figure 1B).

Figure 1.

Kaplan-Meier curves showing renal survival in ANCA-positive and ANCA-negative patients (A), and pr3-ANCA-positive and MPO-ANCA-positive patients (B)

Conclusion:

Our small study indicates that clinical and morphological features of renal involvement, as well as renal survival are similar in ANCA-negative and ANCA-positive patients and don’t depend on the type of ANCA.

References:

[1]Berden AE, Ferrario F, Hagen EC, et al. Histopathologic Classification of ANCA-Associated Glomerulonephritis. J Am Soc Nephrol. 2010;21(10):1628–1636.

[2]Brix RB, Noriega M, Tennstedt P, et al. Development and validation of a renal risk score in ANCA-associated glomerulonephritis. Kidney Int. 2018;94(6):1177-1188.

Disclosure of Interests: :

Nikolai Bulanov Grant/research support from: This work was supported by the 5-100 Project, Sechenov University, Moscow, Ekaterina Stolyarevich: None declared, Anastasiia Zykova: None declared, Elizaveta Safonova: None declared, Elena Shchegoleva: None declared, Ekaterina Kuznezova: None declared, Mayra Bulanova: None declared, Pavel Novikov Grant/research support from: This work was supported by the 5-100 Project, Sechenov University, Moscow, Sergey Moiseev Grant/research support from: This work was supported by the 5-100 Project, Sechenov University, Moscow