Beclin-1 dependent autophagy improves renal outcomes following Unilateral Ureteral Obstruction (UUO) injury

• Published in: Frontiers in immunology Vol. 14; p. 1104652
• Main Authors: Lopez-Soler, Reynold I, Nikouee, Azadeh, Kim, Matthew, Khan, Saman, Sivaraman, Lakshmi, Ding, Xiangzhong, Zang, Qun Sophia
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 16.02.2023
• Subjects: Abdominal Injuries; Animals; Autophagy; Beclin-1; Fibrosis; Immunology; Inflammation; Kidney; kidney injury; Male; Mice; Mice, Inbred C57BL; renal transplant; Ureteral Obstruction; Beclin-1; fibrosis; autophagy; kidney injury; renal transplant
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2023.1104652

Interstitial Fibrosis and Tubular Atrophy (IFTA) is the most common cause of long-term graft failure following renal transplant. One of the hallmarks of IFTA is the development of interstitial fibrosis and loss of normal renal architecture. In this study, we evaluated the role of autophagy initiation factor Beclin-1 in protecting against post-renal injury fibrosis. Adult male wild type (WT) C57BL/6 mice were subjected to Unilateral Ureteral Obstruction (UUO), and kidney tissue samples were harvested at 72-hour, 1- and 3-week post-injury. The UUO-injured and uninjured kidney samples were examined histologically for fibrosis, autophagy flux, inflammation as well activation of the Integrated Stress Response (ISR). We compared WT mice with mice carrying a forced expression of constitutively active mutant form of Beclin-1, . In all experiments, UUO injury induces a progressive development of fibrosis and inflammation. These pathological signs were diminished in mice. In WT animals, UUO caused a strong blockage of autophagy flux, indicated by continuously increases in LC3II accompanied by an over 3-fold accumulation of p62 1-week post injury. However, increases in LC3II and unaffected p62 level by UUO were observed in mice, suggesting an alleviation of disrupted autophagy. Beclin-1 F121A mutation causes a significant decrease in phosphorylation of inflammatory STING signal and limited production of IL6 and IFN , but had little effect on TNF- , in response to UUO. Furthermore, activation of ISR signal cascade was detected in UUO-injured in kidneys, namely the phosphorylation signals of elF2S1 and PERK in addition to the stimulated expression of ISR effector ATF4. However, mice did not reveal signs of elF2S1 and PERK activation under the same condition and had a dramatically reduced ATF level at 3-week post injury. The results suggest that UUO causes a insufficient, maladaptive renal autophagy, which triggered downstream activation of inflammatory STING pathway, production of cytokines, and pathological activation of ISR, eventually leading to the development of fibrosis. Enhancing autophagy Beclin-1 improved renal outcomes with diminished fibrosis, underlying mechanisms of differential regulation of inflammatory mediators and control of maladaptive ISR.