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Systemic lupus erythematosus (SLE) is a complex and common multisystem autoimmune disease, characterized by a loss of immune tolerance, presenting with lupus nephritis (LN) in 30-60% of patients. Macroautophagy can be defined as an intracellular degradation system, it involves the fusion of a double-membrane autophagosome with a lysosome and has been associated with both cell survival and death, which is why it is currently debated whether it is a cause of disease or if it exerts a protective effect for the development of various pathologies. Among the various proteins synthesized from the expression of autophagy-related genes (ATG), there are Beclina1 and LC3, which have become excellent markers for the study of this process. Sato et al described that autophagy in podocytes occurred in 50% of children with evolved IgA nephropathy, correlating with a more aggressive histopathological diagnosis and the presence of LC3-positive autophagosomes was demonstrated in patients with membranous nephropathy compared to pre-transplant renal biopsies. Although it has been shown that autophagy is involved in the pathogenesis of SLE, to what extent it is present in the target organs remains uncertain, so we set out to analyze and describe the presence of macroautophagy in an NL-like experimental model.
Male and female Galectin-3 knockout mice of 8 months of age were used (n:6 for each sex), in which ANAs and renal functional compromise (proteinuria and increased creatinine) have been described, being the controls (C) mice of both sexes of the B6 strain (n:6 per sex). The methodologies used for the evaluation of macroautophagy were: transmission electron microscopy (4% Karnovsky fixative, inclusion in epoxy resins, contrast with heavy metals, observation in a Zeiss Leo 906-E electron microscope) and immunohistochemistry in paraffin for Beclina-1 and LC3, determining the number of immunopositive cells per tubule, counting between 710 and 790 tubules per control and experimental group. Statistics: mean and SD, Mann-Whitney test (two quantitative variable groups, unpaired, without normal distribution). p<0.05. Protocol approved by CICUAL-Universidad de San Martín.
Histopathological evaluation demonstrated, in both male and female NL-like mice, immune complex-mediated mesangial proliferative glomerulonephritis and chronic tubulointerstitial nephritis. The ultrastructural analysis of the experimental groups, unlike the control group and regardless of sex, demonstrated vesicular elements in tubules compatible with macroautophagic vesicles. Both Beclina-1 and LC3 were immunodetected in the renal tubular epithelium, with a significantly higher number of immunopositive cells in the NL-like experimental model compared to the control (example Beclina 1 male C:5±3; NL-like:20±7 *; female C:7±2; similar-NL:25±4**. *p<0.05 vs C and **p<0.05 vs C).
In the NL-like model the macroautophagy mechanism is increased compared to control animals, possibly linked to the proteinuric state of this strain, and may also contribute to the chronic interstitial damage described.
This abstract was also submitted for the XXIV Jornada de Investigación Científica (JIC 2023). By submitting the abstract to WCN’24, abstract authors declare that re-submitting the abstract is permitted by the organizers of the previous meeting.