Angiotensin-converting enzyme 2 enhances megalin-mediated albumin endocytosis in proximal tubule cells by restraining Angiotensin II/AT1R Helena R. Peixoto, Rodrigo P. Silva‐Aguiar, Douglas E. Teixeira, Diogo B. Peruchetti, Sarah A. S. Alves, et al. Journal of Physiology, 2026 Proximal tubule epithelial cell (PTEC) albumin transport efficiently prevents albuminuria under physiological conditions. This process occurs through a receptor‐mediated endocytosis, being megalin, cubilin and amnionless the receptor complex involved. Evidence suggests that renin–angiotensin system (RAS) components regulate albumin transport in proximal tubules (PTs). However, the impact of angiotensin‐converting enzyme type 2 (ACE2) on this process remains uncertain. Overexpressing ACE2 in HEK‐293 promotes a selective increase in receptor‐mediated albumin endocytosis, without changes in fluid‐phase endocytosis. This effect was correlated with increased albumin cell surface binding and increased megalin expression. Treatment with ACE2 inhibitor MLN‐4760 blocked the increase in albumin endocytosis induced by ACE2 overexpression in an angiotensin II (Ang II) / AT1R dependent manner. These results were confirmed in LLC‐PK1 cells. Using a murine albumin overload model, we observed that proteinuria and reduced PT albumin reabsorption was correlated with lower ACE2 protein expression. Using RNA‐Seq databases, we verified that low ACE2 expression correlated with proteinuria in patients with kidney disease. Our results indicate that ACE2 decreases the Ang II/AT1R pathway and increases megalin expression, which in turn enhances PT albumin transport. This pathway is altered in experimental models and patients with kidney diseases. image Key points ACE2 overexpression increases PT albumin transport. ACE2 overexpression increases megalin expression. ACE2 increases albumin transport by decreasing Ang II / AT1R signalling. Akt activation mediates the increased albumin transport induced by ACE2. Decreased ACE2 expression correlates with proteinuria in mouse models and patients.
Mas-related G protein-coupled receptor type D deficiency promotes tubulointerstitial injury and fibrosis associated with proteinuria in male mice Laura B. F. Oliveira, Arthur F. Iost, Lucas R. A. Ribeiro, Maria Aparecida R. Vieira, Thiago Verano‐Braga, et al. Physiological Reports, 2026 Kidney diseases are non‐communicable, progressive diseases with high morbidity and mortality rates worldwide. A key feature of disease progression is the development of tubulointerstitial injury accompanied by proteinuria, a process mediated in part by dysregulation of the Renin‐Angiotensin System (RAS). Recently, a novel protective RAS axis consisting of alamandine (Ala) and its receptor, the Mas‐related G protein‐coupled receptor type D (MrgD), has been identified. While the Ala/MrgD pathway has been implicated in the cardiovascular regulation, its role in renal physiology remains unknown. In this study, we investigated whether basal MrgD deficiency affects the renal structure and function. Male 8‐12‐week‐old C57Bl6/J wild‐type (WT) and MrgD knockout (MrgD‐KO) mice were used. MrgD‐KO exhibited reduced water intake and urine output, increased tubular reabsorption of Na + and glucose, and marked proteinuria associated with increased fractional excretion of proteins. In addition, MrgD deficiency was associated with elevated urinary lactate dehydrogenase levels, increased urinary proteins: creatinine ratio, enhanced urinary γ‐glutamyltransferase activity, and the presence of tubulointerstitial injury and fibrosis in the renal cortex. Collectively, these findings demonstrate that basal MrgD deficiency promotes tubular dysfunction and injury, thereby expanding current understanding of the role of novel RAS peptides in kidney disease.
Short-term hypothyroidism impairs the daily oscillations of renal circadian clock and function in a sex-dependent manner Derrick Kretli-Souza, Bruno Henrique Gomes, Letícia Selvatici-Tolentino, Yancka Oliveira-Damasceno, Ana Flávia Peixoto-Dias, et al. American Journal of Physiology Renal Physiology, 2025 Hypothyroidism alters the kidney circadian clock machinery and renal function in a sex-dependent manner, potentially contributing to early-stage kidney dysfunction. Female rats exhibited more severe rhythmic impairments under hypothyroid conditions, including reduced creatinine clearance, increased protein and glucose loss in urine over 24 h, and disrupted circadian oscillations in renal clock components, indicating a greater susceptibility of females to hypothyroidism-induced metabolic disturbances associated with circadian disruption.
Transition between Healthy Aging and Renal Dysfunction during Natural Aging: Role of p21, p16, Nicotinamide Adenine Dinucleotide Phosphate Hydrogen Oxidase, Nuclear Factor-Kappa B, and Cyclooxygenase-2 Grazielle Caroline da Silva, Thiago Frederico Diniz, Rosária Dias Aires, Diogo Barros Peruchetti, Rafaela Fernandes da Silva, et al. Gerontology, 2025 Introduction: Aging is a key risk factor for progressive kidney disease, yet the mechanisms underlying age-related renal dysfunction remain poorly understood. This study aimed to investigate the role of cyclooxygenase-2 (COX-2) in the transition from healthy renal aging to dysfunction, focusing on its involvement in cellular senescence, inflammation, and oxidative stress. Methods: Male Swiss mice aged 3 (young), 12 (middle-aged), and 18 (old) months were analyzed to assess renal function via blood and 24-h urine collection. Protein expression was evaluated by Western blot, and renal collagenase and matrix metalloproteinase 2 (MMP-2) activities were assessed by immunofluorescence. Neutrophil accumulation was measured by myeloperoxidase (MPO) activity, cytokine levels were measured by ELISA, and oxidative stress was assessed by fluorescence. Results: Old mice showed elevated expression of senescence markers (p53, p21, and p16), COX-2, nuclear factor-kappa B (NF-κB p65), and pro-inflammatory cytokines (IL-6, MCP-1), along with increased MPO activity. Collagenase and MMP-2 activities were also enhanced, particularly in glomerular and tubular regions. Furthermore, upregulation of NADPH oxidase subunits and decreased antioxidant enzyme expression resulted in heightened renal ROS production. These molecular changes were accompanied by significant renal dysfunction, as indicated by reduced creatinine clearance and increased albumin-to-creatinine ratio (ACR). Notably, COX-2 expression positively correlated with inflammation, oxidative stress, and renal dysfunction. In contrast, middle-aged mice exhibited early signs of senescence and oxidative stress without overt inflammation or functional impairment. Conclusion: These findings highlight a critical transitional phase in kidney aging, where early senescence and oxidative stress emerge before functional decline. COX-2 may serve as a central mediator in this process, offering a potential therapeutic target for mitigating age-related renal dysfunction.
Upregulation of COX-2 and NADPH Oxidase and Reduced eNOS in Perivascular Adipose Tissue Are Associated With Resistance Artery Dysfunction and Hypertension in Naturally Aged Mice Grazielle Caroline da Silva, Maisa Nascimento Soares Amaral, Diogo Barros Peruchetti, Virginia Soares Lemos Journals of Gerontology Series A Biological Sciences and Medical Sciences, 2025 Aging is a major risk factor for cardiovascular disease, with hypertension being the most common outcome. Hypertension often stems from resistance arteries endothelial dysfunction. Recent research highlights the pivotal role of perivascular adipose tissue (PVAT) in regulating endothelial function. We hypothesized that PVAT senescence contributes to vascular dysfunction and hypertension during aging. We showed that naturally aged mice developed hypertension and elevated pro-inflammatory cytokines levels. Moreover, resistance mesenteric arteries showed impaired vascular relaxation that was normalized by apocynin, an antioxidant. The vascular dysfunction was endothelium- and PVAT-dependent, and marked by: decreased nitric oxide- and cyclooxygenase-dependent vascular relaxation, decreased expression of endothelial nitric oxide synthase, and increased cyclooxygenase 2 and NADPH oxidase subunits p22phox and gp91phox expressions in the endothelium and PVAT. Additionally, we observed that PVAT shows greater signs of senescence, particularly with higher p16 expression, indicating that PVAT is more prone to age-related cellular aging. Our findings suggest that in resistance mesenteric arteries PVAT-derived factors are crucial for triggering and amplifying vascular dysfunction in aging, leading to hypertension. The underlying mechanisms involve downregulation of endothelial nitric oxide synthase-derived nitric oxide, NADPH oxidase-dependent oxidative stress, and cyclooxygenase 2-derived vascular contractile factors. This research improves our understanding of the mechanisms behind age-related vascular dysfunction and associated hypertension and opens perspectives for targeted therapeutic strategies.
CD8+ T cells promote tubule-interstitial damage in malaria-induced acute kidney injury Douglas Esteves Teixeira, Sarah Aparecida dos Santos Alves, Alessandro Sá Pinheiro, Leandro Souza Silva, Rodrigo Pacheco Silva-Aguiar, et al. Frontiers in Cellular and Infection Microbiology, 2025 IntroductionMalaria acute kidney injury (MAKI) is associated with severe malaria and correlates with poor prognosis and death of patients infected with Plasmodium falciparum. The pathogenesis of MAKI is not completely understood but some hypotheses are well recognized. Host–parasite interactions lead to mechanical obstruction, disorders in the renal microcirculation, and immune-mediated glomerular injury. We investigated the influence of CD8⁺ T cells in the pathogenesis of malaria-induced renal disease.MethodsTo assess the role of T lymphocytes in MAKI pathogenesis, we used adoptive transfer; antibody-driven CD8+ T cells depletion and treatment with FYT720.ResultsThe transference of total T cells isolated from malaria-infected donor mice into naive recipient animals reproduced kidney tubule-interstitial damage without affecting glomerular function. It was associated with increased accumulation of CD8+ T cells in the kidneys of recipient mice. The selective depletion of CD8+ T cells in infected animals resulted in protection from tubular injury, although glomerular alterations still occurred. Finally, we evaluated FTY720, an immunomodulatory drug that sequesters T cells in lymphoid organs and limits their migration, as a potential therapeutic strategy. Treatment with FTY720 prevented the development of proteinuria and the increase in the urine to creatinine ratio. Moreover, FTY720 reduced urinary γ-glutamyl transferase (γ-GT) levels, a marker of tubular injury, but did not alter plasma urea and creatinine, two markers of glomerular function.DiscussionOur results add new knowledge demonstrating that CD8+ T cells have a specific role in tubule-interstitial injury pathology during MAKI.
O-GlcNAcylation in Renal (Patho)Physiology Rodrigo P. Silva-Aguiar, Diogo B. Peruchetti, Ana Acacia S. Pinheiro, Celso Caruso-Neves, Wagner B. Dias International Journal of Molecular Sciences, 2022